Pressure detecting apparatus

Pressure detecting apparatus includes: a housing; a pipe extending from one end of the housing and having an elongated shape; and a pressure sensitive element for detecting pressure and outputting a signal corresponding to the pressure. The pipe includes a top end capable of receiving the pressure. The pressure sensitive element is disposed on the top end of the pipe. The housing includes a connector for retrieving the signal from the pressure sensitive element. The pipe further includes a wiring member disposed inside the pipe so that the wiring member connects between the pressure sensitive element and connector electrically.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Applications No. 2004-146095 filed on May 17, 2004, No. 2004-146096 filed on May 17, 2004, and No. 2004-332054 filed on Nov. 16, 2004, the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a pressure sensor.

BACKGROUND OF THE INVENTION

The present invention is related to pressure detecting apparatus, i.e., a pressure sensor arranged in such a manner that a pressure sensitive element is provided inside a housing containing an elongate-shaped pipe portion which is projected from one edge side of the housing.

This sort of pressure detecting apparatus is arranged by employing a housing, an elongate-shaped pipe portion, and a pressure sensitive element, the apparatus which is disclosed, for instance, in Japanese Laid-open Patent Application No. H05-34231. The elongate-shaped pipe portion is provided in such a manner that the pipe portion is projected from one edge side of the housing. The pressure sensing element is provided in the housing and outputs a signal in response to detected pressure.

In the above-described pressure detecting apparatus, the pipe portion of the housing is inserted into an object to be detected, the pressure of which will be detected, and then, pressure to be detected (namely, detecting pressure) derived from the object to be detected is applied to a tip portion of the pipe portion. Then, this detecting pressure is applied to the pressure sensitive element provided in the housing so as to detect the pressure.

In the conventional pressure detecting apparatus, while a diaphragm for receiving the detecting pressure is provided on the tip portion of the pipe portion, and a pressure transferring member having a rod shape (referred to as “rod”), the detecting pressure may be transferred from the diaphragm via the rod to the pressure sensitive element.

Such a pressure detecting apparatus equipped with the rod functioning as the rod-shaped pressure transferring member is applied to a combustion pressure sensor, and the like. The combustion pressure sensor detects pressure (namely, internal cylinder pressure) in a combustion chamber of an engine. In this case, the pipe portion of the housing is inserted into a mounting hole of an engine block which corresponds to the object to be detected. As a result, the length of the rod must be elongated in response to the length of the pipe portion, namely, a transfer distance of pressure.

However, as explained above, if the length of the rod is made longer, then the weight of this rod is increased. As a result, a resonant frequency of the rod is superimposed with a vibration frequency of knocking of combustion, so that a resonant phenomenon may occur in the rod. Accordingly, such a problem may occur with respect to a sensor characteristic. That is, knocking signals are embedded in noise which is produced by the resonant phenomenon of the rod, so that the knocking signals cannot be measured.

Also, in the case that the length of the rod is made long, since the rod itself may be easily deformed, contact conditions between the rod and either the diaphragm or the pressure sensitive element are changed. If such a change in the contact conditions happens to occur, then precision in pressure transfer characteristics is deteriorated, which may give an advance influence to the sensor characteristic.

Further, in the case of such a pressure detecting apparatus that a pressure sensitive element has been connected to a flexible printed-circuit board by way of a flip flop joint, if a cooling/heating cycle is repeatedly carried out, then a large amount of stresses may be produced in the bump joint portions, because of differences in thermal expansion coefficients of these structural elements, in particular, a difference between a thermal expansion coefficient as to the pressure sensitive element made of silicon, and another thermal expansion coefficient as to the flexible printed-circuit board made of resin.

Also, while the sensing unit repeatedly receives pressure by the detected pressure, bumps are depressed by this pressure, so that a large amount of stresses may be produced in the bump joint portions. Then, in the bump joint portions which have received the stresses, there is such a risk that a wire disconnection may eventually occur.

Furthermore, if the flexible printed-circuit board is bent in such a manner that the bending angle “θ” becomes smaller than, or equal to 90 degrees, then such a stress applied to a direction along which one edge portion is stripped from the strain gauge is not substantially produced at one edge portion of the flexible printed-circuit board, namely at the joint portion to the strain gauge under this bending condition.

However, when the flexible printed-circuit board is bent under such a bending condition that the bending angle “θ” becomes smaller than, or equal to 90 degrees, the stress which is applied to the bending portion of the flexible printed-circuit board is large, so that a damage may readily occur. As a result, the following problems may probably occur. That is, cracks, bends, and breaks may be produced in a base, a copper foil, and the like, which constitute the flexible printed-circuit board.

SUMMARY OF THE INVENTION

In view of the above-described problem, it is an object of the present invention to provide a pressure detecting apparatus. The apparatus has excellent sensor characteristics and excellent durability.

Pressure detecting apparatus includes: a housing; a pipe extending from one end of the housing and having an elongated shape; and a pressure sensitive element for detecting pressure and outputting a signal corresponding to the pressure. The pipe includes a top end capable of receiving the pressure. The pressure sensitive element is disposed on the top end of the pipe. The housing includes a connector for retrieving the signal from the pressure sensitive element. The pipe further includes a wiring member disposed in the pipe so that the wiring member connects between the pressure sensitive element and connector electrically.

In the above apparatus, since the pressure sensitive element is disposed on the top end of the pipe, the length of the pipe can be reduced. Thus, resonance of the pipe generated by external engine and the like and deformation of the pipe can be suppressed. Accordingly, the apparatus has excellent sensor characteristics and excellent durability.

Preferably, the apparatus further includes: a pressure transferring member disposed between the diaphragm and the pressure sensitive element. The pressure transferring member includes a first surface contacting the diaphragm and a second surface contacting the pressure sensitive element. The first and the second surfaces are spherical surfaces. The pressure sensitive element is capable of receiving the pressure through the diaphragm and the pressure transferring member. In this case, the contact between the diaphragm and the pressure transferring member and the contact between the pressure sensitive element and the pressure transferring member provide stable point contacts. Thus, contact area of them can be reduced. Therefore, change of contact characteristics does not affect the sensor characteristics of the apparatus. Thus, the apparatus has excellent pressure transfer.

Preferably, the apparatus further includes: a diaphragm having a circular shape and disposed on the top end of the pipe for covering the pressure sensitive element. The pressure sensitive element is capable of receiving the pressure through the diaphragm. The pressure sensitive element includes a strain gauge deformable by a load introduced from the diaphragm. The strain gauge has a contact area contacting the diaphragm. The contact area of the strain gauge is equal to or smaller than one-fourth of an area of the diaphragm. In this case, the pressure received by the diaphragm can be applied to the pressure sensitive element directly. Specifically, the force applied to the pressure sensitive element is equal to or larger than the received pressure. Thus, even when the dimensions of the pressure sensitive element are reduced, the sensitivity of the pressure is not reduced.

Preferably, the wiring member is a flexible printed circuit board. The flexible printed circuit board includes a first end connecting to the pressure sensitive element, a second end, and a bending portion. The flexible printed circuit board is bent with a bending angle at the bending portion. The second end of the flexible printed circuit board extends toward the connector. The bending angle is equal to or smaller than 90 degrees so that stress at the bending portion is smaller than a case where the bending angle is larger than 90 degrees.

Preferably, the first end of the flexible printed circuit board is disposed in the pipe on one side of an inner wall of the pipe. The second end of the flexible printed circuit board is disposed in the pipe on the other side of the inner wall of the pipe. The one end of the inner wall of the pipe faces the other side of the inner wall of the pipe. In this case, it can be performed appropriately that the bending angle is set to be equal to or smaller than 90 degrees. Further, the stress of removing the pressure sensitive element from the printed circuit board is reduced. Thus, the connection between the element and the board can be appropriately secured.

Further, pressure detecting apparatus includes: a housing; a flexible printed circuit board disposed in the housing; a sensing portion for detecting pressure and outputting a signal corresponding to the pressure; and a connector disposed in the housing and retrieving the signal from the sensing portion. The sensing portion is disposed on one side of the housing so that the one side of the housing is capable of receiving the pressure. The flexible printed circuit board connects between the sensing portion and the connector electrically. The sensing portion is connected to the flexible printed circuit board electrically and mechanically through a plurality of bumps disposed on the flexible printed circuit board. The flexible printed circuit board has a stress relaxation construction for reducing stress applied to the bumps.

In this case, even if the stress is applied to the bump, the stress is reduced by the stress relaxation construction. Accordingly, the apparatus has excellent sensor characteristics and excellent durability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1is a sectional view for schematically showing an entire structure of a pressure detecting apparatus100according to a first embodiment of the present invention. Also,FIG. 2is an enlarged view for representing a portion ofFIG. 1, which is a top end of the apparatus100. It should be noted that inFIG. 2, an engine block200is also represented.

Although usage of the pressure detecting apparatus100is not limited, this pressure detecting apparatus100may be applied as a combustion pressure sensor, while a pipe portion12of a housing10is mounted in a mounting hole201formed in, for example, an engine block200of an automobile as an object to be detected by way of a screw coupling manner (seeFIG. 2). This combustion pressure sensor detects pressure (namely, internal cylinder pressure) within a combustion chamber202as a detecting pressure.

The housing10is constituted by a cylindrical main body portion11and the pipe portion12. The pipe portion12having as elongated cylindrical shape is made narrower than the main body portion11. Both of the main body portion11and the pipe portion12are made of a metal such as stainless steel, which has been processed by cutting, cold forging operation, and the like. In this first embodiment, the pipe portion12has a cylindrical pipe shape, for example, the outer diameter of which is 4 mm, and the inner diameter of which is 3 mm. Alternatively, the pipe portion12may have a rectangular pipe shape.

It should also be noted that in the housing10, the main body portion11and the pipe portion12may be formed in an integral body. Alternatively, the main body portion11and the pipe portion12may be separately formed, and thereafter, both of these portions11and12may be joined with each other to be formed in an integral body by way of welding, adhering, press-fitting, screw coupling, caulking etc.

Also, a screw portion13has been formed on an outer peripheral plane of the pipe portion12in the housing10. The screw portion13can be screw-coupled to the above-described engine block200functioning as the object to be detected. As previously explained, the pressure detecting apparatus100of this first embodiment has been arranged in such a manner that the housing10is provided with the pipe portion12having the elongate shape, while the pipe portion12is projected from one edge side of this housing10.

In this case, the pipe portion12of the housing10is inserted into the mounting hole201, and is mounted via the screw portion13. The mounting hole201has been formed in the engine block200as a screw hole. As a result, the pressure detecting apparatus100is mounted on the engine block200.

Then, under such a condition that this pressure detecting apparatus100is mounted on the engine block200, pressure (namely, internal cylinder pressure) within the combustion chamber202as detecting pressure is applied to the tip portion of the pipe portion12as indicated by an arrow “Y” inFIG. 1andFIG. 2in a reverse printing manner.

Also, a pressure sensitive element20has been provided on the tip portion of the pipe portion12in the housing10. The pressure sensitive element20outputs a signal in response to detected pressure. In this case, as represented inFIG. 2, the pressure sensitive element20has been arranged under environment of detected pressure, namely, arranged in such a manner that the pressure sensitive element20is exposed to the combustion chamber202. Thus, the above-described internal cylinder pressure as the detecting pressure may be directly applied to the pressure sensitive element20.

This pressure sensitive element20owns strain gauge function. The strain gauge function may output a signal in response to detected pressure based upon strain caused by the detected pressure.

Concretely speaking, as shown inFIG. 2, the pressure sensitive element20is constituted by a metal stem21having a hollow cylindrical shape, and a strain gauge30. One edge side of this metal stem21is an opening portion22, and the other edge side thereof is a diaphragm23. The strain gauge30has been provided on a surface of the diaphragm23of this metal stem21by way of glass welding, or the like.

The metal stem21is such a metal member, which has been processed so as to have the hollow cylindrical shape. A flange24has been formed on an opening edge portion of the opening portion22, while this flange24is projected along a direction perpendicular to a circumferential plane thereof. In this first embodiment, the hollow portion of the metal stem21has a cylindrical shape. Alternatively, this hollow portion may have a rectangular cylindrical shape.

Then, the metal stem21has been inserted into the pipe portion12in such a manner that the diaphragm-sided portion23of this metal stem21is directed to the inner portion of the pipe portion12, and the opening portion-sided portion22thereof is directed to the combustion chamber202. Then, the flange24of the metal stem21has been fixed to the opening edge portion of the tip portion of the pipe portion12by way of an adhering, or welding manner.

Alternatively, under such a condition that the pressure detecting apparatus100is mounted on the engine block200, since the flange24of the metal stem21is sandwiched by the pipe portion12and the engine block200made of a metal such as aluminum, the metal stem21may be fixed under pressure welding condition.

As previously explained, in the metal stem21, the opening portion22thereof is exposed to the combustion chamber202, and the pressure of the combustion chamber202is applied to a rear surface of the diaphragm23of the metal stem21.

Also, the strain gauge30provided on a front surface of the diagram23of the metal stem21is made of a silicon semiconductor chip in which, for example, a bridge circuit and the like has been formed. The strain gauge30owns such a function that when the diaphragm23of the metal stem21is deformed by receiving pressure, a change in resistance values produced in response to this deformation is converted into an electric signal, and then, this electric signal is outputted.

While the diaphragm23of the metal stem21and the strain gauge30are arranged as strain portions23and30, which are strained by receiving weights produced by the detected pressure, these strain portions23and30may give an influence to basic performance of the pressure detecting apparatus100.

In this case, as to metal materials which constitute the metal stem21, high strengths of the metal materials are necessarily required since these metal materials receive high pressure, and also, low thermal expansion coefficients are necessarily required, since the strain gauge30made of a Si semiconductor and the like is joined to the metal stem21by low melting glass.

Concretely speaking, as the metal stem21, while Fe, Ni, Co, or Fe, Ni are employed as a major material, a material to which Ti, Nb, Al, or Ti, Nb have been added as a precipation emphasizing material may be selected. For example, precipation hardening type stainless steel may be selected. This metal stem21may be formed by way of pressing, cutting, and cold forging operation.

Also, as shown inFIG. 1, a circuit board40manufactured by a ceramic substrate, or the like, has been provided inside the main body portion11of the housing10. The circuit board40has been provided in such a manner that this circuit board40covers the opening portion of the pipe portion12in the main body portion11. A peripheral portion of the circuit board40has been fixed on the housing10by way of, for example, an adhering manner.

An IC chip42has been adhered on a plane of the circuit board40so as to be mounted thereon. This plane is located opposite to the opening portion of the pipe portion12. In this IC chip42, such a circuit has been manufactured, which amplifies and adjusts an output signal from the strain gauge30.

Then, this IC chip42has been electrically connected to the circuit board40by using a bonding wire44made of aluminum (Al). Further, as represented inFIG. 1andFIG. 2, the circuit board40has been electrically connected to the above-explained pressure sensitive element20by employing a wiring member (flexible printed-circuit board: FPC)50.

In this case, as the wiring member50, the flexible printed-circuit board (FPC)50has been employed. Apparently, other members than FPC, for instance, a lead wire may be alternatively employed as the wiring member50.

As the flexible printed-circuit board50, such a general-purpose printed-circuit board may be employed which has been manufactured by patterning a conductor such as a copper (Cu) on a base, e.g., polyimide resin. As indicated inFIG. 1, this flexible printed-circuit board50has been arranged inside the pipe portion12of the housing10in such a manner that the flexible printed-circuit board50extends along the longitudinal direction of the pipe portion12.

In this first embodiment, one edge portion51of the flexible printed-circuit board50has been electrically and mechanically joined with respect to the strain gauge30provided in the pressure sensitive element20by using solder, and the like.

Then, the flexible printed-circuit board50has been bent from one edge portion51of this flexible printed-circuit board50, and a portion of this flexible printed-circuit board50which is located on the side of the other edge portion52thereof is elongated inside the pipe portion12along the direction of the circuit board40. The above-described one edge portion51corresponds to the joint portion of the flexible printed-circuit board50to the pressure sensitive element20.

On the other hand, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is positioned at the main body portion11of the housing10. Then, the other edge portion52of the flexible printed-circuit board50is positioned via a through hole46from a mounting plane of the circuit board40, which mounts thereon the IC chip42to a plane of this circuit board40, which is located opposite to the IC chip mounting plane. The through hole46is formed in the circuit board40.

Then, the other edge portion52of the flexible printed-circuit board50has been electrically connected to the circuit board40on the plane of the circuit board40, which is located opposite to the mounting plane of the IC chip42by way of solder, and the like.

Also, as shown inFIG. 1, in the housing10, a connector case60having a terminal61has been provided at a position opposite to the connecting plane of the circuit board40with respect to the flexible printed-circuit board50.

This connector case60is made of such a resin as PPS (polyphenylene salfide). The terminal61has been formed with the connector case60in an integral form by way of insert molding, and the like. This connector case60has been constructed as a connector portion capable of deriving a signal from the pressure sensitive element20.

Then, the terminal61of the connector case60has been electrically connected to the circuit board40via a spring member62by way of a spring contact. As a result, the pressure sensitive element20has been electrically connected via both the flexible printed-circuit board50and the circuit board40to the connector case60.

Also, since the edge portion14of the main body portion11of the housing10is caulked to the connector case60, the connector case60has been fixed on the housing10in an integral manner. Then, the terminal61may be electrically connected via a wiring member (not shown) to an ECU of an automobile, and the like.

A description is made of one example as to a method for assembling the pressure detecting apparatus100having the above-explained structure. That is, one edge portion51of the flexible printed-circuit board50is firstly connected with respect to the pressure sensitive element20by way of solder, or the like. In the pressure sensitive element20, the metal stem21and the strain gauge30have been formed in the integral body.

Next, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is inserted from the tip portion of the pipe portion12of the housing10, and then, the other edge portion52of the flexible printed-circuit board50is drawn out up to an internal portion of the main body portion11of the housing10.

Subsequently, the other edge portion52of the flexible printed-circuit board50is penetrated through the through hole46of the circuit board40, and is connected to the circuit board40by way of solder, or the like. The IC chip42has been mounted on this circuit board40by way of the wire bonding manner.

Next, the circuit board40is joined to the main body portion11of the housing10so as to be fixed on this main body portion11. Thereafter, the connector case60is assembled to the main body portion11of the housing10, and since the edge portion14of the housing10is caulked, the connector case60is fixed with the housing10.

When this connector case60is assembled in the housing10, the terminal61is contacted via the spring member62to the circuit board40in the spring contact manner so as to electrically connect the terminal61with the circuit board40. As a result, the pressure detecting apparatus100shown inFIG. 1may be accomplished in accordance with the above-explained manner.

Since the accomplished pressure detecting apparatus100is mounted via the screw portion13of the housing10in the screw hole201, this pressure detecting apparatus100may be connected/fixed on the engine block200. The screw hole201has been formed in the engine block200functioning as the object to be detected.

Then, when pressure (namely, internal cylinder pressure) within the combustion chamber202is applied to the diaphragm23of the pressure sensitive element20as indicated by the arrow “Y” inFIG. 1andFIG. 2, the diaphragm23of the metal stem21is deformed by this applied pressure, and then, this deformation is converted into an electric signal by the strain gauge30so as to detect the pressure.

Then, the electric signal derived from the strain gauge30is transferred via the flexible printed-circuit board50to the circuit board40, and is processed by the IC chip42, and thereafter, the processed signal is outputted from the terminal61to an external unit.

On the other hand, according to this first embodiment, in the pressure detecting apparatus comprising: the housing10; the pipe portion12having the elongate shape provided in the housing10in such a manner that the pipe portion12is projected from one edge side of the housing10; and the pressure sensitive element20for outputting the signal in response to the detecting pressure, in which the detecting pressure is applied to the tip portion of the pipe portion12, such a pressure detecting apparatus100is provided which is featured by that the pressure sensitive element20is provided on this tip portion of the pipe portion12; the connector portion60for deriving the signal from the pressure sensitive element20is provided in the housing10; and the wiring member50for electrically connecting the pressure sensitive element20to the connector portion60is stored inside the pipe portion12.

In accordance with the pressure detecting apparatus100, since such an arrangement is employed that the pressure sensitive element20has been provided on the tip portion of the pipe portion12, the conventionally provided rod can be omitted.

More specifically in this first embodiment, the pressure sensitive element20has been arranged under the environment of the detecting pressure, namely, this pressure sensitive element20has been exposed to the combustion chamber202. Thus, the detecting pressure is directly applied to the pressure sensitive element20.

As previously explained, if the pressure detecting apparatus100is constituted by omitting the rod, then such a problem caused by this rod can be solved. That is, as to this problem, the resonant phenomenon of the rod occurs, and the pressure transferring precision is deteriorated.

Also, while the connector case60has been mounted on the housing10and this connector case60functions as the connector portion60for deriving the signal from the pressure sensitive element20, this connector portion60is electrically connected to the pressure sensitive element20provided on the tip portion of the pipe portion12by employing the flexible printed-circuit board50, so that there is no problem as to the output of the signal. The flexible printed-circuit board50has been stored inside the pipe portion12as the wiring member.

As a consequence, in accordance with this first embodiment, in such a pressure detecting apparatus100arranged by that the pressure sensitive element20is provided inside the housing10having the elongate-shaped pipe portion12which is projected from one edge side of the housing10, and the connector portion60is provided in the housing10, the adverse influence given to the sensor characteristic can be suppressed, which is caused by the elongate pipe portion and the rod stored in this elongate pipe portion.

Also, as shown inFIG. 1andFIG. 2, in this first embodiment, under the mounting condition of the pressure detecting apparatus100, as to the metal stem21, only the flange24of this metal stem21is sandwiched by the engine block200and the pipe portion12.

Since such a structure for sandwiching only the flange24within the metal stem21is employed, this structure can avoid that the metal stem21is deformed along the upper/lower directions shown inFIG. 2, namely the longitudinal direction of the metal stem21. In other words, when the pressure detecting apparatus100is screwed so as to be mounted on the engine block200, it is possible to avoid an occurrence of an abnormal output caused by screwing the pressure detecting apparatus100.

Second Embodiment

FIG. 3is a sectional view for schematically indicating a major portion of a pressure detecting apparatus according to a second embodiment of the present invention. A different point of this pressure detecting apparatus from that of the first embodiment will now be mainly described.

In the above-described first embodiment, while the pressure sensitive element20has been arranged in such a manner that this pressure sensitive element20is exposed under the environment of the detecting pressure, the detecting pressure has been directly applied to the pressure sensitive element20.

In contrast to the first embodiment, in the pressure detecting apparatus of this second embodiment, as indicated inFIG. 3, a diaphragm15has been provided on the tip portion of the pipe portion12in the housing10in such a manner that this diaphragm15covers the pressure sensitive element20. Thus, detecting pressure may be applied via this diaphragm15to the pressure sensitive element20.

It should be understood that this diaphragm15will be referred to as “pressure-receiving-purpose diaphragm15” hereinafter in order that this pressure-receiving-purpose diaphragm15may be discriminated from the above-explained diaphragm23of the metal stem21.

In particular, in this second embodiment, the pressure-receiving-purpose diaphragm15is directly made contact to the pressure sensitive element20. Concretely speaking, as shown inFIG. 3, a convex portion15awhich is projected along the direction of the pressure sensitive element20has been formed on the pressure-receiving-purpose diaphragm15, and a tip portion projected from this convex portion15ahas been contracted to the rear plane of the diaphragm23of the metal stem21.

In this case, the pressure-receiving-purpose diaphragm15is made in, for example, a disk shape, and the convex portion15ahas a shape similar to a “navel” which is located at a center position of this circle. Also, since the peripheral portion of the pressure-receiving-purpose diaphragm15is joined to the flange24of the metal stem21by way of welding so as to be fixed on this flange24, this pressure-receiving-purpose diaphragm15has been formed with the pressure sensitive element20in an integral body.

The pressure detecting apparatus of this second embodiment can be manufactured as follows: That is, with respect to the pressure sensitive element20formed with the pressure-receiving-purpose diaphragm15in the integral body, one edge portion51of the flexible printed-circuit board50is connected by way of solder, or the like. Thereafter, a manufacturing method similar to that of the first embodiment is carried out so as to manufacture the above-explained pressure detecting apparatus of this second embodiment.

Then, in a pressure detecting operation of this second embodiment, when pressure (internal cylinder pressure) within the combustion chamber202is applied to the pressure-receiving-purpose diaphragm15, this weight is applied from the convex portion15aof the pressure-receiving-purpose diaphragm15to the diaphragm23of the metal stem21. Then, a deformation of the diaphragm23of the metal stem21is converted into an electric signal by the strain gauge30in order to detect pressure.

On the other hand, in accordance with this second embodiment, such a pressure detecting apparatus is provided which is featured by that the pressure sensitive element20is provided on the tip portion of the pipe portion12; the connector portion60is provided on the housing10; the wiring member50for electrically connecting the pressure sensitive element20to the connector portion60is stored inside the pipe portion12; and further, the pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12in a such a manner that this diaphragm15covers the pressure sensitive element20; so that the detecting pressure is applied via the pressure-receiving-purpose diaphragm15to the pressure sensitive element20.

In accordance with this pressure detecting apparatus, similar to the above-explained embodiment, the adverse influence given to the sensor characteristic can be suppressed, which is caused by the elongate pipe portion and the rod stored in this elongate pipe portion. Also, in this second embodiment, while the convex portion15ais provided on the pressure-receiving-purpose diaphragm15, this pressure-receiving-purpose diaphragm15is directly made contact to the pressure sensitive element20, so that this pressure detecting apparatus can be arranged by omitting the rod.

Now,FIG. 4is a sectional view for schematically indicating a modification of this second embodiment. InFIG. 3, the convex portion15aof the pressure-receiving-purpose diaphragm15has been formed by way of a cutting process or the like. In contrast, in a pressure-receiving-purpose diaphragm15shown inFIG. 4, a convex portion15ahas been manufactured by conceiving a diaphragm plane having a flat plate shape by way of a pressing process, so that this convex portion15amay be formed in a simple manner.

Third Embodiment

FIG. 5is a sectional view for schematically indicating a major portion of a pressure detecting apparatus according to a third embodiment of the present invention. A different point of this pressure detecting apparatus from that of the above-described embodiment will now be explained.

As shown inFIG. 5, also in this third embodiment, similar to the above-described second embodiment, the pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12in such a manner that this diaphragm15covers the pressure sensitive element20, so that detecting pressure is applied via the pressure-receiving-purpose diaphragm15to the pressure sensitive element20.

In accordance with the pressure detecting apparatus of the above-described second embodiment, while the convex portion15ahas been provided on the pressure-receiving-purpose diaphragm15, this pressure-receiving-purpose diaphragm15has been directly made contact to the pressure sensitive element20, so that this pressure detecting apparatus can be arranged by omitting the rod.

In contrast to the second embodiment, in this third embodiment, as shown inFIG. 5, one piece of a pressure transferring member16is interposed between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20. Then, detecting pressure is applied from the pressure-receiving-purpose diaphragm15via the pressure transferring member16to the pressure sensitive element20.

In accordance with this third embodiment, since the pressure sensitive element20is provided on the tip portion of the pipe portion12, a distance between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20can be made as short as possible, and thus, such an arrangement that the pressure transferring member16(namely, rod) is shortened can be realized. As a result, the above-explained resonance problem caused by prolonging the rod, and such a problem that the rod itself is deformed can be suppressed as being permitted as possible.

As the pressure transferring member16employed in this third embodiment, a rod-shaped member which is similar to the rod of the conventional pressure detecting apparatus may be employed. More specifically, in the example shown inFIG. 5, a spherical-shaped member16has been employed as the pressure transferring member16.

In the case of this specific arrangement, as to the spherical-shaped member16functioning as the pressure transferring member, both a plane of this spherical-shaped member16which is contacted to the pressure-receiving-purpose diaphragm15, and another plane thereof which is contacted to the pressure sensitive element20(namely, diaphragm23of metal stem21) constitute spheres.

That is to say, according to this third embodiment, with respect to the pressure detecting apparatus in which the pressure sensitive element20is provided on the tip portion of the pipe portion12; the connector portion60is provided on the housing10; the wiring member50is stored in the pipe portion12; and further, the pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12in such a manner that this pressure-receiving-purpose diaphragm15covers the pressure sensitive element20, such a pressure detecting apparatus may be provided which is featured by that one piece of the pressure transferring member16is interposed between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, while the planes of this pressure transferring member16which are contacted to both the diaphragm15and the element20constitute the spheres.

Similar to the above-described embodiment, in accordance with this pressure detecting apparatus, the adverse influence given to the sensor characteristic can be suppressed, which is caused by the elongate pipe portion and the rod stored in this elongate pipe portion.

Also, in this third embodiment, the contacts between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, and the pressure transferring member16can be set as stable point contacts. Further, a total contact number between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, and the pressure transferring member16can be reduced.

As a consequence, the changes of the contact conditions between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, and the pressure transferring member16can be suppressed as minimum as possible, the stable contact conditions can be secured in the respective contact portions, and also, deteriorations of the pressure transfer precision can be suppressed.

In specifically, in the example shown inFIG. 5, the pressure transferring member16corresponds to the spherical member16. In this case, the spherical member16functioning as the pressure transferring member can be hardly deformed, as compared with the rod of the prior art. As a result, the stable contact conditions between this spherical member16, and the pressure-receiving-purpose diaphragm15and the pressure sensitive element20can be preferably maintained under suitable contact conditions.

It should also be noted that this spherical member16may not be a complete spherical shape, and may be alternatively replaced by a slightly elliptical sphere, or a “Rugby ball” shape. Also, as the pressure transferring member16whose contact planes with respect to the pressure-receiving-purpose diaphragm15and the pressure sensitive element20become the spherical planes, the invention is not limited only to a spherical-shaped member. For instance, both the contact planes may be made of spherical planes, but an intermediate portion between both the spherical contact planes may be made of a pillar shape.

Fourth Embodiment

FIG. 6Ais a sectional view for schematically showing a major portion of a pressure detecting apparatus according to a fourth embodiment of the present invention.FIG. 6BandFIG. 6Care a plan view and a longitudinal sectional view for representing an upper portion of a heat radiation member70shown inFIG. 6A.

As previously explained, in a related art, the detecting pressure is applied via the elongate-shaped rod to the pressure sensitive element. As a result, the pressure sensitive element is arranged in such a manner that this pressure sensitive element is separated from the pressure detecting environment such as the engine combustion chamber in order to reduce the temperature of the pressure sensitive element.

To the contrary, in the above-described respective embodiments of the invention, the pressure sensitive element20is provided on the tip portion of the pipe portion12, which is located close to the pressure detecting environment, so that the temperature of the pressure sensitive element20may be easily increased.

As a consequence, in this fourth embodiment, as indicated inFIG. 6AtoFIG. 6C, a heat radiation member70is arranged in such a manner that this heat radiation member70is contacted to the pressure sensitive element20. This heat radiation member70is made of a material having a superior heat resisting characteristic and a superior heat radiating characteristic such as aluminum and stainless steel. In this example, a honeycomb-shaped member having a through hole71is employed which is used in a heat exchanger.

While the heat radiation member70has been stored from the opening portion22of the metal stem21into a hollow portion, this heat radiation member70has been fixed with respect to the metal stem21in such a manner that the heat radiation member71is connected to, for example, in inner peripheral plane of the metal stem21by way of welding, or solder.

In accordance with this fourth embodiment, since heat of the pressure sensitive element20is radiated through the heat radiation member70, the temperature reduction of the pressure sensitive element20can be preferably improved.

The through hole71formed in the heat radiation member70may contribute that a relative surface area of the heat radiation member70is increased so as to improve the heat radiating characteristic. In addition, detecting pressure may be conducted via this through hole71to the diaphragm23of the metal stem21. In other words, since this through hole71is formed, it is possible to avoid that the pressure conduction to the pressure sensitive element20is blocked.

Also, as indicated inFIG. 6A, both the heat radiation member70and the strain portion23of the pressure sensitive element20have a space.

Concretely speaking, in the pressure sensitive element20, the diaphragm23corresponding to the strain portion has been constructed as a concaved plane of an inner plane of the metal stem21in such a manner that a lower plane of the heat radiation member70is not contacted to the diaphragm23. As a result, a strain deformation of the diaphragm23is not blocked by the heat radiation portion70.

Also, in the example shown inFIG. 6A, under such a condition that the pressure detecting apparatus is mounted on the engine block200, the flange24of the metal stem21is directly contacted to the engine block200. There is another effect that the metal stem21may be cooled by cooling water which flows through this engine block200.

In the example shown inFIG. 6AtoFIG. 6C, the heat radiation member70has been provided in such an arrangement that the pressure sensitive element20is exposed under the environment of the detecting pressure and a pressure-receiving-purpose diaphragm is omitted. Alternatively, even in such a case that the pressure-receiving-purpose diaphragm15as explained in the second and third embodiments is provided, for instance, the heat radiation member70may be interposed between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20.

Fifth Embodiment

As explained in the respective embodiments of the invention, in such a case that the pressure sensitive element20is provided on the tip portion of the elongate pipe portion12, the size of the pressure sensitive element20must be made smaller than that of the prior art.

As described in the above-explained embodiments, in such a case that the pressure sensitive element20owns the strain gauge function, namely, has the strain portions23and30which are strained by receiving the weight, if the size of this pressure sensitive element20is decreased, then the areas of the strain portions23and30are also decreased, namely, both the area of the diaphragm23of the metal stem21and the area of the strain gauge30are also reduced.

As a consequence, there are some possibilities that lowering of sensitivity may occur. Accordingly, an increase of the weight which is applied to the pressure sensitive element20is required. This fifth embodiment has been made in order to increase the weight applied to the pressure sensitive element20.

This fifth embodiment has been arranged as follows: That is, as indicated in such arrangement of the second embodiment and the third embodiment shown inFIG. 3toFIG. 5, a pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12in such a manner that this diaphragm15covers the pressure sensitive element20, and this pressure-receiving-purpose diaphragm15has a circular shape.

In this case, detecting pressure is applied from the above-described convex portion15a(seeFIG. 3andFIG. 4) of the pressure-receiving-purpose diaphragm15, or the pressure-receiving-purpose diaphragm15via the pressure transferring member16to the strain portions23and30of the pressure sensitive element20.

Then, in this fifth embodiment, in such an arrangement, an area of a contact portion in the strain portions23and30of the pressure element20with respect to the pressure-receiving-purpose diaphragm15is made smaller than, or equal to ¼ of the area of the pressure-receiving-purpose diaphragm15.

Concretely speaking, in the examples shown inFIG. 3toFIG. 5, the area of the contact portion in the strain portions23and30of the pressure element20with respect to the pressure-receiving-purpose diaphragm15corresponds to a portion within the rear plane of the diaphragm23of the metal stem21, to which the convex portion15aof the pressure-receiving-purpose diaphragm15is contacted, or another portion where the pressure-receiving-purpose diaphragm15is contacted via the pressure transferring member16.

Then, an area of this contact portion corresponds to an area of a portion within the rear plane of the diaphragm23of the metal stem21, to which the projected tip portion of the convex portion15ais contacted, or another area of a portion to which the pressure transferring member16is contacted.

In such an arrangement, even when pressure applied to the pressure-receiving-purpose diaphragm15is equal to each other, if the area of the pressure-receiving-purpose diaphragm15is increased, large weight may be obtained. Then, since this weight is applied to a narrow area of the diaphragm23of the metal stem21, this weight may be transferred as the large weight.

In accordance with the analysis result obtained by executing FEM (finite element method) by the Inventors of the invention, in the case of the pressure-receiving-purpose diaphragm15having the circular shape, a weight transfer efficiency of a spring is approximately 25%.

As a result, since the area of the above-described contact portion in the diaphragm23of the metal stem21is made smaller than, or equal to ¼ with respect to the area of the pressure-receiving-purpose diaphragm15having the circular shape, high pressure may be applied to the diaphragm23of the metal stem21, namely the pressure sensitive element20.

This fact will now be explained in a more concrete manner by employing formulae. It is so assumed that a radius of the pressure-receiving-purpose diaphragm15is defined as “r”, and detecting pressure having a magnitude of “a” in MPa is applied to this pressure-receiving-purpose diaphragm15.

In this case, the area of the pressure-receiving-purpose diaphragm15is “πr2”, and weight “F” given to the pressure-receiving-purpose diaphragm15is F=a×πr2. Also, in the case that the area of the contact portion in the diaphragm23of the metal stem21is made equal to ¼ with respect to the area of the pressure-receiving-purpose diaphragm15, this area is equal to ¼ (πr2).

Then, assuming now that the pressure applied to the contact portion in the diaphragm23of the metal stem21is “B” in MPa, weight “f” applied to this contact portion is given by f=B×(πr2/4). In this case, since a weight converting efficiency of the circular-shaped diaphragm15is approximately 25%, F=f/4, namely, (¼)×a×πr2=B×(πr2/4).

In other words, in such a case that the area of the above-described contact portion in the diaphragm23of the metal stem21is made equal to ¼ with respect to the area of the pressure-receiving-purpose diaphragm15, B=a, so that there is no change in the pressure applied between the pressure-receiving-purpose diaphragm15and the diaphragm23of the metal stem21.

Furthermore, in such a case that the area of the above-described contact portion in the diaphragm23of the metal stem21is made smaller than, or equal to ¼ with respect to the area of the pressure-receiving-purpose diaphragm15, the pressure “B” applied to the diaphragm23of the metal stem21becomes higher than the pressure “a” applied to the pressure-receiving-purpose diaphragm15. As a result, the application of the weight may be concentrated to the pressure sensitive element20.

As previously explained, according to this fifth embodiment, such a pressure detecting apparatus may be provided in which the pressure sensitive element20is provided on the tip portion of the pipe portion12; the connector portion60is provided on the housing10; the wiring member50is stored in the pipe portion12; and further, the pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12in such a manner that this pressure-receiving-purpose diaphragm15covers the pressure sensitive element20; the pressure sensitive element20owns the strain portions23and30which are strained by receiving the weight from the pressure-receiving-purpose diaphragm15; and the area of the contact portion in the strain portions21and30of the pressure sensitive element20with the pressure-receiving-purpose diagram15is made smaller than, or equal to ¼ with respect to the area of the pressure-receiving-purpose diaphragm15.

In accordance with the above-described pressure detecting apparatus, as previously explained, the force which is received by the pressure-receiving-purpose diaphragm15can be directly applied, or the higher force than this received force can be applied to the strain portions23and30of the pressure sensitive element20. Similar to the above-explained embodiments, the pressure detecting apparatus can suppress the adverse influence given to the sensor characteristic, which is caused by the elongate pipe portion and the rod stored in this elongate pipe portion, and further, can secure the sufficiently high sensor sensitivity.

It should be understood that the above embodiments owns the following major structure. That is, in the pressure detecting apparatus comprising: the housing10; the pipe portion12having the elongate shape provided in the housing10in such a manner that the pipe portion12is projected from one edge side of the housing10; and the pressure sensitive element20for outputting the signal in response to the detecting pressure, in which the detecting pressure is applied to the tip portion of the pipe portion12, such a major structure is featured by that the pressure sensitive element20is provided on the tip portion of the pipe portion12; the connector portion60is provided in the housing10; and the wiring member50for electrically connecting the pressure sensitive element20to the connector portion60is stored inside the pipe portion12; and other structural portions may be properly changed.

As apparent from the foregoing descriptions, the pressure detecting apparatus of the invention is not limited to be utilized as the above-explained combustion pressure sensor for detecting the pressure (internal cylinder pressure) within the combustion chamber.

Sixth Embodiment

The inventors have tried to arrange such a construction that in pressure detecting apparatus, the pressure sensitive element is located closer to the pressure detecting environment in order to improve the sensitivity.

Normally, in this sort of pressure detecting apparatus, signal processing units such as a connector unit for deriving a signal from the pressure sensitive element are provided in the housing. Conventionally, the pressure sensitive element is electrically connected to these signal processing units by using a wire bonding technique.

However, in the case that the pressure sensitive element is located closer to the pressure detecting environment side, the pressure sensitive element is arranged on the tip portion side of the pipe portion in the housing, so that the distance between the pressure sensitive element and the signal processing unit becomes long. As a result, in the case that the pressure sensitive element is electrically connected to the signal processing unit, this electrical connection cannot be realized by way of such a wire bonding technique.

Then, the inventors of the invention have employed a flexible printed-circuit board as a connection member in such a case that the pressure sensitive element is connected to the signal processing unit which is located far from this pressure sensitive element, while the Inventors have considered an easy handling characteristic, a compactness, and an easy connecting characteristic.

While the inventors of the invention have considered the following technical points, the Inventors have tried to manufacture such a pressure detecting apparatus as shown inFIG. 12. As the technical points, the pressure sensitive element is arranged on the tip portion of the pipe portion in the housing; and the flexible printed-circuit board is employed in order to connect the pressure sensitive element to the signal processing unit containing the connector unit.

FIG. 12is a sectional view for schematically indicating an entire structure of the pressure detecting apparatus as a prototype model manufactured by the inventors.

Although usage of the pressure detecting apparatus is not limited, this pressure detecting apparatus may be applied as a combustion pressure sensor, while a pipe portion12of a housing10is mounted in a mounting hole formed in, for example, an engine block of an automobile by way of a screw coupling manner. This combustion pressure sensor detects pressure (namely, internal cylinder pressure) within a combustion chamber.

The housing10made of a metal is constituted by a cylindrical-shaped main body portion11, and a pipe portion12having an elongate cylindrical shape which is narrower than this main body portion11. A screw portion13has been formed on an outer peripheral plane of the pipe portion12in the housing10. The screw portion13can be screw-coupled to the above-explained engine block.

In this case, in the pressure detecting apparatus, detecting pressure is applied to the tip portion of the pipe portion12as indicated by an arrow “Y” inFIG. 12in a reverse printing manner.

Also, a pressure sensitive element20has been provided on the tip portion of the pipe portion12in the housing10. The pressure sensitive element20outputs a signal in response to detected pressure. In this case, the pressure sensitive element20has been arranged under environment of detected pressure. Thus, the above-described internal cylinder pressure as the detecting pressure may be directly applied to the pressure sensitive element20.

This pressure sensitive element20owns a strain gauge function. The strain gauge function may output a signal in response to, for example, detected pressure based upon strain caused by the detected pressure.

Concretely speaking, as shown inFIG. 12, the pressure sensitive element20is constituted by a metal stem21having a hollow cylindrical shape, and a strain gauge30. One edge side of this metal stem21is an opening portion22, and the other edge side thereof is a diaphragm23. The strain gauge30has been provided on a surface of the diaphragm23of this metal stem21.

In this metal stem21, while the opening portion22is exposed to the detecting environment, detecting pressure is applied from this opening portion22to a rear plane of a diaphragm23of the metal stem21. Then, when the diaphragm23of the metal stem21is deformed by pressure, an electric signal may be outputted from the strain gauge30in response to this deformation.

Also, as shown inFIG. 12, a circuit board40has been provided inside the main body portion11of the housing10. An IC chip42has been adhered on one plane of the circuit board40so as to be mounted thereon. In this IC chip42, such a circuit is provided which processes an output signal from the strain gauge30.

Then, this IC chip42has been electrically connected to the circuit board40via a bonding wire44. Further, the circuit board40has been electrically connected to the above-explained pressure sensitive element20by employing a flexible printed-circuit board50. This flexible printed-circuit board50has been arranged inside the pipe portion12of the housing10in such a manner that the flexible printed-circuit board50is elongated along the longitudinal direction of the pipe portion12.

In this pressure detecting apparatus, one edge portion51of the flexible printed-circuit board50has been electrically joined with respect to the strain gauge30. Then, the flexible printed-circuit board50has been bent from one edge portion51as a joint portion and a portion54located on the side of the other edge portion52rather than the bending portion653is elongated inside the pipe portion12along the direction of the circuit board40.

On the other hand, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is positioned at the main body portion11of the housing10. Then, this other edge portion52of the flexible printed-circuit board50is positioned via a through hole46from a mounting plane of the circuit board40, which mounts thereon the IC chip42, to a plane of this circuit board40, which is located opposite to the IC chip mounting plane. The through hole46is formed in the circuit board40.

Then, the other edge portion52of the flexible printed-circuit board50has been electrically connected to the circuit board40on the plane of the circuit board40, which is located opposite to the mounting plane of the IC chip42by way of solder, and the like.

Also, in the housing10, a connector case60having a terminal61has been provided at a position opposite to the connecting plane of the circuit board40with respect to the flexible printed-circuit board50. This connector case60has been constructed as a connector portion capable of deriving a signal from the pressure sensitive element20.

Then, the terminal61of the connector case60has been electrically connected to the circuit board40via a spring member62by way of a spring contact. As a result, the pressure sensitive element20has been electrically connected via both the flexible printed-circuit board50and the circuit board40to the connector case60, namely the connector portion60.

In accordance with the pressure detecting apparatus shown inFIG. 12, since such an arrangement is employed that the pressure sensitive element20has been provided on the tip portion of the pipe portion12, the conventionally provided rod can be omitted the length of the rod can be made as short as possible.

As previously explained, in the pressure detecting apparatus shown inFIG. 12, the electrical connection from the present sensitive element20located at the tip portion of the pipe portion12to the connector portion60is realized by employing the flexible printed-circuit board50.

FIG. 13AandFIG. 13Bare diagrams for indicating a detailed joint of the flexible printed-circuit board50.FIG. 13Ais a plan view for showing such a condition before the flexible printed-circuit board50is bent.FIG. 13Bis a side view for indicating such a condition after the flexible printed-circuit board50has been bent, namely such a condition that the flexible printed-circuit board50has been assembled to the pressure detecting apparatus.

As indicated inFIG. 13A, after one edge portion51of the flexible printed-circuit board50has been connected via a joint member650asuch as solder with respect to the strain gauge30of the pressure sensitive element20, the other edge portion52thereof is inserted into the pipe portion12. As a result, the portion53ais bent as represented inFIG. 13B.

In this case, a bending angle “θ2” of a bending portion653in the flexible printed-circuit board50becomes 90 degrees, or an obtuse angle larger than, or equal to 90 degrees. In this case, as indicated inFIG. 13B, the bending angle “θ2” implies such an angle which is defined between a plane of the joint portion51continued via the bending portion653and another plane of an extension portion654extended within the pipe portion12. Specifically, the bending angle “θ2” is disposed between a dotted line inFIG. 13Band the extension portion654. The dotted line is obtained by extending the extension portion654. Thus, the bending angle “θ2” is equal to or larger than 90 degrees (i.e., the obtuse angle). The one edge portion51of the board50is bent from the extension portion654at the bending portion653with the bending angle “θ2” equal to or larger than 90 degrees.

Also, if the flexible printed-circuit board50is bent in such a manner that the bending angle “θ2” becomes smaller than, or equal to 90 degrees (i.e., the bent angle is equal to or smaller than 90 degrees), then such a stress applied to a direction along which one edge portion51is stripped from the strain gauge30is not substantially produced at one edge portion51of the flexible printed-circuit board50, namely at the joint portion to the strain gauge30under this bending condition.

However, when the flexible printed-circuit board50is bent under such a bending condition that the bending angle “θ2” becomes larger than, or equal to 90 degrees, the stress which is applied to the bending portion653of the flexible printed-circuit board50is large, so that a damage may readily occur. As a result, the following problems may probably occur. That is, cracks, bends, and breaks may be produced in a base, a copper foil, and the like, which constitute the flexible printed-circuit board50.

In view of the above problem, a flexible printed-circuit board50according to a sixth embodiment of the present invention is provided.FIG. 8AandFIG. 8Bare diagrams for indicating a detailed joint of this flexible printed-circuit board50.FIG. 8Ais a plan view for showing such a condition before the flexible printed-circuit board50is bent.FIG. 8Bis a side view for indicating such a condition after the flexible printed-circuit board50has been bent, namely such a condition that the flexible printed-circuit board50has been assembled to the pressure detecting apparatus100. Referring also toFIGS. 8A and 8B, the flexible printed-circuit board50will now be described.

One edge portion51of the flexible printed-circuit board50has been electrically and mechanically joined with respect to the strain gauge30in the pressure sensitive element20by employing the joint member650asuch as solder. In this case, as shown inFIG. 8A, the joint members650ahave been arranged at four corner portions of the strain gauge30.

Then, the flexible printed-circuit board50is bent from one edge portion51corresponding to a joint portion of the flexible printed-circuit board50to the pressure sensitive element20. A portion of the flexible printed-circuit board50, which is located on the side of the other edge portion52rather than this bending portion is elongated along the direction of the circuit board40within the pipe portion12, namely, along a direction of the connector portion as a connector case60(will be explained later).

Now, in this embodiment, a bending angle “θ1” of a bending portion653in the flexible printed-circuit board50becomes an acute angle or an angle equal to or smaller than 90 degrees. In this case, as indicated inFIG. 8B, the bending angle “θ1” implies such an angle which is defined between a plane continued via the bending portion653and another plane of an extension portion654extended within the pipe portion12. Specifically, the bending angle “θ1” is defined as a bent angle, which is disposed between the one edge portion51of the board50and the extension portion654inFIG. 8B. The bending angle “θ1” is equal to or smaller than 90 degrees. Thus, the extension portion654is firstly bent at the bending portion653with the bending angle equal to or smaller than 90 degrees. Then, the extension portion654is secondary bent at a portion653bwith another bending angle equal to or smaller than 90 degrees.

Thus, as indicated inFIG. 7,FIGS. 8A and 8B, the flexible printed-circuit board50has also been bent at the portion653bof the other edge portion52rather than the bending portion653. In other words, in this example, the flexible printed-circuit board50has been bent not at one place (namely, in prior art), but at a plurality of places.

Also, as shown inFIG. 7, the bending portion653within the flexible printed-circuit board50is located at a position close to one inner wall (namely, right-sided inner wall inFIG. 7) of opposite walls in the pipe portion12, whereas the extension portion654is located at a position close to another inner wall (namely, left-sided inner wall inFIG. 7) of the opposite inner walls, contrary to the above-explained bending portion653. This extension portion654of the flexible printed-circuit board50is extended along the direction of the connector portion60within the pipe portion12. In this example, as shown inFIG. 7, the extension portion654is extended along the direction of the connector portion50under such a condition that this extension portion654is contacted to the other inner wall of the opposite inner walls.

Moreover, as shown inFIGS. 8A and 8B, a through hole655has been formed in one edge portion51in such a manner that the pressure sensitive element20, namely, the strain gauge30is exposed. One edge portion51corresponds to the joint portion within the flexible printed-circuit board50with respect to the pressure sensitive element20, namely, the strain gauge30.

Also, a boundary portion between this through hole655and the bending portion653constitutes an “R” portion655ahaving an R-shape which is not made in a rectangular shape, but is rounded. This “R” portion655amay reduce concentration of stresses, and may suppress damages given to the flexible printed-circuit board50, as compared with such a case that this boundary portion is made in the rectangular portion.

On the other hand, as shown inFIG. 7, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is positioned at the main body portion11of the housing10. Then, the other edge portion52of the flexible printed-circuit board50is positioned via a through hole46from a mounting plane of the circuit board40, which mounts thereon the IC chip42to a plane of this circuit board40, which is located opposite to the IC chip mounting plane. The though hole46is formed in the circuit board40.

Then, the other edge portion52of the flexible printed-circuit board50has been electrically connected to the circuit board40on the plane of the circuit board40, which is located opposite to the mounting plane of the IC chip42by way of solder, and the like.

Also, as shown inFIG. 7, in the housing10, a connector case60having a terminal61has been provided as the connector portion at a position opposite to the connecting plane of the circuit board40with respect to the flexible printed-circuit board50.

This connector case60is made of a resin such as PPS (polyphenylene salfide). The terminal61has been formed with the connector case60in an integral form by way of insert molding, and the like. This connector case60has been constructed as a connector portion capable of deriving a signal from the pressure sensitive element20.

Then, the terminal61of the connector case60has been electrically connected to the circuit board40via a spring member62by way of a spring contact. As a result, the pressure sensitive element20has been electrically connected via both the flexible printed-circuit board50and the circuit board40to the connector case60.

Also, since the edge portion14of the main body portion11of the housing10is caulked to the connector case60, the connector case60has been fixed on the housing10in an internal manner. Then, the terminal61may be electrically connected via a wiring member (not shown) to an ECU of an automobile, and the like.

A description is made of one example as to a method for assembling the pressure detecting apparatus100having the above-explained structure. First, the pressure sensitive element20in which the metal stem21and the strain gauge30have been formed in an integral body is prepared. The one edge portion51of the flexible printed-circuit board50is connected via the joint member650asuch as solder with respect to the strain gauge30of this pressure sensitive element20. This condition is represented inFIG. 8A.

Thereafter, in order to insert the other edge portion52of the flexible printed-circuit board50into the pipe portion12, the flexible printed-circuit board50is bent to be formed. This condition is shown inFIG. 8B.

Next, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is inserted from the tip portion of the pipe portion12of the housing10, and then, the other edge portion52of the flexible printed-circuit board50is drawn out up to an internal portion of the main body portion11of the housing10.

Subsequently, the other edge portion52of the flexible printed-circuit board50is penetrated through the through hole60of the circuit board40, and the circuit board40is joined to the main body portion11of the housing10so as to be fixed on this main body portion11. Next, the other edge portion52of the flexible printed-circuit board50is connected to the circuit board40by way of solder, or the like. The IC chip42has been mounted on this circuit board40by way of the wire bonding manner.

Thereafter, the connector case60is assembled to the main body portion11of the housing10, and since the edge portion14of the housing10is caulked, the connector case60is fixed with the housing10.

When this connector case60is assembled in the housing10, the terminal61is contacted via the spring member62to the circuit board40in the spring contact manner so as to electrically connect the terminal61with the circuit board40. As a result, the pressure detecting apparatus100shown inFIG. 7may be accomplished in accordance with the above-explained manner.

Since the accomplished pressure detecting apparatus100is mounted via the screw portion13of the housing10in the screw hole, this pressure detecting apparatus100may be connected/fixed on the engine block. The screw hole20has been formed in the engine block functioning as the object to be detected.

Then, when pressure (namely, internal cylinder pressure) within the combustion chamber is applied to the diaphragm23of the pressure sensitive element20as indicated by the arrow “Y” inFIG. 7, the diaphragm23of the metal stem21is deformed by this applied pressure, and then, this deformation is converted into an electric signal by the strain gauge30so as to detect the pressure.

Then, the electric signal derived from the strain gauge30is transferred via the flexible printed-circuit board50to the circuit board40, and is processed by the IC chip42, and thereafter, the processed signal is outputted from the terminal61to an external unit.

On the other hand, according to this embodiment, in the pressure detecting apparatus100comprising: the housing10; the pipe portion12having the elongate shape provided in the housing10in such a manner that the pipe portion12is projected from one edge side of the housing10; and the pressure sensitive element20for outputting the signal in response to the detecting pressure, in which the detecting pressure is applied to the tip portion of the pipe portion12, the below-mentioned featured points are provided.

That is, the pressure sensitive element20is provided on the tip portion of the pipe portion12, and the connector portion60for deriving the signal from the pressure sensitive element20is provided in the housing10(refer toFIG. 7).

The flexible printed-circuit board50for electrically connecting the pressure sensitive element20to the connector portion60is stored inside the pipe portion12. The one edge portion51of this flexible printed-circuit board50is jointed to the pressure sensitive element20, and also, is bent from the one edge portion51as this joint portion. The portion of the flexible printed-circuit board50on the side of the other edge portion52rather than this bending portion653is extended along the direction of the connector portion60in the pipe portion12(refer toFIG. 7).

The bending angle “θ1” of the bending portion653in the flexible printed-circuit board50becomes the acute angle smaller than 90 degrees (refer toFIGS. 8A and 8B).

In accordance with the pressure detecting apparatus100of this embodiment with employment of these featured structures, since the bending angle “θ1” of the bending portion653in the flexible printed-circuit board50is set to the acute angle smaller than 90 degrees, the damages caused by bending the flexible printed-circuit board50can be reduced, as compared with the conventional pressure detecting apparatus in which the bending angle has been set to such an angle larger than, or equal to 90 degrees.

Also, in the pressure detecting apparatus100of this embodiment, the flexible printed-circuit board50has also been bent at such a portion thereon on the side of the other edge portion (52) rather than the bending portion653in addition to the bending portion653(refer toFIG. 7andFIGS. 8A and 8B).

As previously explained, the flexible printed-circuit board50is bent not at one place as explained in the prior art, but is bent plural times, so that the bending angle of each of the bending portions can be decreased. As a result, such a technical idea that the bending angle “θ1” of the bending portion653in the flexible printed-circuit board50is set to the acute angle smaller than 90 degrees may be properly realized.

Also, in the pressure detecting apparatus100of this embodiment, the bending portion653within the flexible printed-circuit board50is located at the position close to one inner wall of opposite walls in the pipe portion12, whereas the extension portion654is located at the position close to another inner wall of the opposite inner walls in the pipe portion12. This extension portion654of the flexible printed-circuit board50is extended along the direction of the connector portion60within the pipe portion12(seeFIG. 7).

In other words, in this embodiment, both the bending portion653of the extension portion654of the flexible printed-circuit board50are located at such positions which are close to the different inner walls within the opposite inner walls in the pipe portion12.

As a consequence, such a technical idea that the bending angle “θ1” of the bending portion653in the flexible printed-circuit board50is set to the acute angle smaller than 90 degrees may be properly realized. In addition, in the joint portion51with respect to the pressure sensitive element20in the flexible printed-circuit board50, the stress applied to the direction along which the flexible printed-circuit board50is stripped from the strain gauge30can be reduced, and the joint strength in this joint portion51can be properly secured.

For instance, in the structure of the conventional flexible printed-circuit board50shown inFIG. 13, since both the bending portion653and the extension portion654in this conventional flexible printed-circuit board50are located at the positions close to the same-sided inner wall of the opposite inner walls in the pipe portion12, it is practically difficult that the above-described bending angle “θ2” is set to such an angle smaller than 90 degrees.

Also, in the pressure detecting apparatus100of this embodiment, a through hole655has been formed in one edge portion51in such a manner that the pressure sensitive element20is exposed (refer toFIGS. 8A and 8B). This one edge portion51corresponds to the joint portion with respect to the pressure sensitive element20in the flexible printed-circuit board50.

As a result, there is no opportunity that the detecting plane of the pressure sensitive element20is tightly closed by the flexible printed-circuit board50, and thus, air can be freely entered and derived into/from the detecting plane of the pressure sensitive element20, namely the detecting plane of the strain gauge30inFIG. 7. Accordingly, it is possible to avoid disturbance as to the pressure detection by the pressure sensitive element20. As a consequence, the pressure detecting apparatus100having the higher sensitivity can be realized.

It should be noted that this through hole655need not be formed in the center portion of the one edge portion51in the flexible printed-circuit board50. Also, a total number of the through hole655need not be selected to be 1, but may be alternatively selected to be plural pieces.

Also, in accordance with the pressure detecting apparatus100of this embodiment, since this pressure detecting apparatus100is arranged in such a manner that the pressure sensitive element20is provided in the tip portion of the pipe portion12, the conventionally provided rod can be omitted.

In particular, in this embodiment, while the pressure sensitive element20has been arranged under such an environment of the detecting pressure, namely, in this example, this pressure sensitive element20is exposed to the combustion chamber, the detecting pressure may be directly applied to the pressure sensitive element20.

In the conventional pressure detecting apparatus, while the diaphragm for receiving the detecting pressure is provided on the tip portion of the pipe portion, and the pressure transferring member having the rod shape (referred to as “rod”) is provided in the pipe portion, the detecting pressure may be transferred from the diaphragm via the rod to the pressure sensitive element.

In this case, the length of the rod must be elongated in response to the length of the pipe portion, namely, the transfer distance of pressure. For example, in the combustion pressure sensor, if the length of the rod is made longer, then the weight of this rod is increased. As a result, a resonant frequency of the rod is superimposed with a vibration frequency of knocking of combustion, so that a resonant phenomenon may occur in the rod. Accordingly, such a problem may occur with respect to a sensor characteristic. That is, knocking signals are embedded in noise which is produced by the resonant phenomenon of the rod, so that the knocking signals cannot be measured.

Also, in the case that the length of the rod is made long, since the rod itself may be easily deformed, contact conditions between the rod and either the diaphragm or the pressure sensitive element are changed. If such a change in the contact conditions happens to occur, then precision in pressure transfer characteristics is deteriorated, which may give an adverse influence to the sensor characteristic.

To the contrary, as explained in this embodiment, if the pressure detecting apparatus100is constituted by omitting the rod, then such a problem caused by this rod can be solved. That is, as to this problem, the resonant phenomenon of the rod occurs, and the pressure transferring precision is deteriorated.

As a consequence, in accordance with this embodiment, in such a pressure detecting apparatus100arranged by that the pressure sensitive element20is provided inside the housing10having the elongate-shaped pipe portion12which is projected from one edge side of the housing10, and the connector portion60is provided in the housing10, the adverse influence given to the sensor characteristic can be suppressed, which is caused by the elongate pipe portion and the rod stored in this elongate pipe portion.

Seventh Embodiment

On the other hand, in the pressure detecting apparatus100shown inFIG. 7andFIGS. 8A and 8B, while the pressure sensitive element20has been arranged in such a manner that this pressure sensitive element20is exposed under the environment of the detecting pressure, the detecting pressure has been directly applied to the pressure sensitive element20.

In the below-mentioned seventh embodiment of the present invention, such arrangements that detecting pressure is applied via diaphragms to the pressure sensitive element20is provided.

FIG. 9is a sectional view for schematically indicating a major portion of a pressure detecting apparatus as a first example according to the seventh embodiment of the present invention.

In the pressure detecting apparatus indicated inFIG. 9, a diaphragm15has been provided on the tip portion of the pipe portion12in the housing10in such a manner that this diaphragm15covers the pressure sensitive element20. Thus, detecting pressure may be applied via this diaphragm15to the pressure sensitive element20.

It should be understood that this diaphragm15will be referred to as “pressure-receiving-purpose diaphragm15” hereinafter in order that this pressure-receiving-purpose diaphragm15may be discriminated from the above-explained diaphragm23of the metal stem21.

In particular, in this first example, the pressure-receiving-purpose diaphragm15is directly made contact to the pressure sensitive element20. Concretely speaking, as shown inFIG. 9, a convex portion15awhich is projected along the direction of the pressure sensitive element20has been formed on the pressure-receiving-purpose diaphragm15, and a tip portion projected from this convex portion15ahas been contracted to the rear plane of the diaphragm23of the metal stem21.

In this case, the pressure-receiving-purpose diaphragm15is made in, for example, a disk shape, and the convex portion15ahas a shape similar to a “navel” which is located at a center position of this circle. Also, since the peripheral portion of the pressure-receiving-purpose diaphragm15is joined to the flange24of the metal stem21by way of welding so as to be fixed on this flange24, this pressure-receiving-purpose diaphragm15has been formed with the pressure sensitive element20in an integral body.

The pressure detecting apparatus of this first example can be manufactured as follows: That is, with respect to the pressure sensitive element20formed with the pressure-receiving-purpose diaphragm15in the integral body, one edge portion51of the flexible printed-circuit board50is connected by way of solder, or the like. Thereafter, an assembling method similar to that of the sixth embodiment is carried out so as to manufacture the above-explained pressure detecting apparatus of this embodiment.

Then, in a pressure detecting operation of this first example, when pressure (internal cylinder pressure) within the combustion chamber is applied to the pressure-receiving-purpose diaphragm15, this weight is applied from the convex portion15aof the pressure-receiving-purpose diaphragm15to the diaphragm23of the metal stem21. Then, a deformation of the diaphragm23of the metal stem21is converted into an electric signal by the strain gauge30in order to detect pressure.

FIG. 10is a sectional view for schematically indicating a major portion of a pressure detecting apparatus as a second example according to the seventh embodiment of the present invention.

In the above-described first modification shown inFIG. 9, the convex portion15aof the pressure-receiving-purpose diaphragm15has been formed by way of a cutting process or the like. In contract, in a pressure-receiving-purpose diaphragm15shown inFIG. 10, a convex portion15ahas been manufactured by denting a diaphragm plane having a flat plate shape by way of a pressing process, so that this convex portion15amay be formed in a simple manner.

FIG. 11is a sectional view for schematically indicating a major portion of a pressure detecting apparatus as a third example according to the seventh embodiment of the present invention.

As shown inFIG. 11, also in this third example, similar to the above-described first and second examples, the pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12in such a manner that this diaphragm15covers the pressure sensitive element20, so that detecting pressure is applied via the pressure-receiving-purpose diaphragm15to the pressure sensitive element20.

In the above-described first and second examples, while the convex portion15ahas been provided on the pressure-receiving-purpose diaphragm15, this pressure-receiving-purpose diaphragm15has been directly made contact to the pressure sensitive element20, so that this pressure detecting apparatus can be arranged by omitting the rod.

In contrast to the first and second examples, in this third example shown inFIG. 11, one piece of a pressure transferring member16is interposed between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20. Then, detecting pressure is applied from the pressure-receiving-purpose diaphragm15via the pressure transferring member16to the pressure sensitive element20.

In accordance with this third example, since the pressure sensitive element20is provided on the tip portion of the pipe portion12, a distance between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20can be made as short as possible, and thus, such an arrangement that the pressure transferring member16(namely, rod) is shortened can be realized. As a result, the above-explained resonance problem caused by prolonging the rod, and such a problem that the rod itself is deformed can be suppressed as being permitted as possible.

As the pressure transferring member16employed in the arrangement as explained in this third example, a rod-shaped member which is similar to the rod of the conventional pressure detecting apparatus may be employed. More specifically, in the example shown inFIG. 11, a spherical-shaped member16has been employed as the pressure transferring member16.

In the case of this arrangement, as to the spherical-shaped member16functioning as the pressure transferring member, both a plane of this spherical-shaped member16which is contacted to the pressure-receiving-purpose diaphragm15, and another plane thereof which is contacted to the pressure sensitive element20(namely, diaphragm23of metal stem21) constitute spheres.

According to this example, the contacts between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, and the pressure transferring member16can be set as stable point contacts. Further, a total contact number between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, and the pressure transferring member16can be reduced.

As a consequence, the changes of the contact conditions between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, and the pressure transferring member16can be suppressed as minimum as possible, the stable contact conditions can be secured in the respective contact portions, and also, deteriorations of the pressure transfer precision can be suppressed.

In specifically, in such a case that the pressure transferring member16is constructed of the spherical member16, the spherical member16functioning as the pressure transferring member can be hardly deformed, as compared with the rod of the prior art. As a result, the stable contact conditions between this spherical member16, and the pressure-receiving-purpose diaphragm15and the pressure sensitive element20can be preferably maintained under suitable contact conditions.

It should also be noted that this spherical member16may not be a complete spherical shape, and may be alternatively replaced by a slightly elliptical sphere, or a “Rugby ball” shape. Also, as the pressure transferring member16whose contact planes with respect to the pressure-receiving-purpose diaphragm15and the pressure sensitive element20become the spherical planes, the invention is not limited only to a spherical-shaped member in this example. For instance, both the contact planes may be made of spherical planes, but an intermediate portion between both the spherical contact planes may be made of a pillar shape.

It should also be noted that the extension portion654of the flexible printed-circuit board50, which is elongated within the above-explained pipe portion12, may be alternatively twisted so as to form a spiral shape.

Alternatively, in the pipe portion12, the flexible printed-circuit board50may be adhered to the pipe portion12so as to be fixed thereon.

Further, in the flexible printed-circuit board50located within the pipe portion12, a component having light weight such as a capacitor may be alternatively mounted on the surface of this flexible printed-circuit board50.

Also, in the above-described respective embodiments, the pressure sensitive element20is provided on the tip portion of the pipe portion12which is located close to the pressure to be detected environment, so that the temperature of the pressure sensitive element20may be easily increased.

As a solving measure in such a case, in the pressure detecting apparatus, a heat radiation member may be provided in such a way that this heat radiation member is made in contact with the pressure sensitive element20. In accordance with this embodiment, since heat of the pressure sensitive element20is radiated through the heat radiation member, the temperature reduction of the pressure sensitive element20can be preferably improved.

As such a heat radiation member, for example, the following heat radiation member may be employed which is made of a material having a superior heat resisting characteristic and a superior heat radiating characteristic such as aluminum and stainless steel. Then, such a heat radiation member may be fixed with respect to the metal stem21in such a manner that the heat radiation member is connected to, for example, the metal stem21by way of welding, or solder.

In summary, the invention owns the following major structure. That is, in the pressure detecting apparatus comprising: the housing10; the pipe portion12having the elongate shape provided in the housing10in such a manner that the pipe portion12is projected from one edge side of the housing10; and the pressure sensitive element20for outputting the signal in response to the detecting pressure, in which the detecting pressure is applied to the tip portion of the pipe portion12, such a major structure is featured by that the pressure sensitive element20is provided on the tip portion of the pipe portion12; the connector portion60is provided in the housing10; and the wiring member50for electrically connecting the pressure sensitive element20to the connector portion60is stored inside the pipe portion12; further, as explained above, the bending angle “θ1” of the bending portion653in the flexible printed-circuit board50is set to the acute angle equal to or smaller than 90 degrees; and other structural portions may be properly changed.

As apparent from the foregoing descriptions, the pressure detecting apparatus of the invention is not limited to be utilized as the above-explained combustion pressure sensor for detecting the pressure (internal cylinder pressure) within the combustion chamber.

Eighth Embodiment

The inventors have tried to manufacture such an arrangement that in a pressure detecting apparatus, a sensing unit is located closer to the pressure detecting environment side in order to improve the sensitivity thereof.

FIG. 26is a sectional view for schematically indicating an entire structure of the pressure detecting apparatus as a prototype model manufactured by the inventors.

Also, a sensing unit831for outputting a signal in response to detected pressure has been provided on the tip portion of the pipe portion12in the housing10.

In this case, the sensing unit831has been constituted by a pressure-receiving-purpose diaphragm15, a metal stem21, a pressure transferring member16, and a pressure sensitive element20. The pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12, and is to receive detected pressure (namely, pressure which should be detected). The pressure transferring member16has been provided in the metal stem21. The detected pressure is transferred from the pressure-receiving-purpose diaphragm15via the pressure transferring member16to the pressure sensitive element20.

Concretely speaking, the pressure sensitive element20has been mounted on a surface of a diaphragm23by way of a glass joint in the metal stem21functioning as a holding member having a hollow cylindrical shape, one edge side of which is an opening portion22, and the other edge side of which is the diaphragm23. This pressure sensitive element20owns a strain gauge function. This strain gauge function may output a signal in response to, for example, detected pressure based upon a strain caused by the detected pressure.

The pressure transferring member16has been provided in the hollow portion of this metal stem21. The pressure-receiving-purpose diaphragm15has been fixed on the opening portion22of the metal stem21in such a manner that this diaphragm15may cover the opening21.

Then, as indicated by an arrow “Y” inFIG. 26, the detected pressure may be applied from the pressure-receiving-purpose diaphragm15via the pressure transferring member16to a rear plane of the diaphragm23of the metal stem21.

Then, when the diaphragm23of the metal stem21is deformed by pressure, an electric signal may be outputted from the pressure sensitive element20in response to this deformation.

Also, as shown inFIG. 26, a circuit board40has been provided inside the main body portion11of the housing10. An IC chip42has been mounted on one plane of the circuit board40so as to be fixed thereon by way of adhesion. In this IC chip42, a circuit is provided which processes an output signal from the pressure sensitive element20of the sensing unit831.

Then, this IC chip42has been electrically connected to the circuit board40via a bonding wire44. Further, the circuit board40has been electrically connected to the above-explained pressure sensitive element20of the sensing unit831by employing a flexible printed-circuit board50. This flexible printed-circuit board50has been arranged inside the pipe portion12of the housing10in such a manner that the flexible printed-circuit board50extends along the longitudinal direction of the pipe portion12.

In this pressure detecting apparatus, one edge portion51of the flexible printed-circuit board50has been electrically joined with respect to the pressure sensitive element20, and the other edge portion52thereof is elongated inside the pipe portion12along the direction of the circuit board40. Then, the other edge portion52of the flexible printed-circuit board50has been electrically connected to the circuit board40by way of solder, and the like.

Also, in the housing10, a connector case60having a terminal61has been provided at a position opposite to the circuit board40. This connector case60has been constructed as a connector portion capable of deriving a signal from the pressure sensitive element20of the sensing unit831in this pressure detecting apparatus.

Then, the terminal61of the connector case60has been electrically connected to the circuit board40via a spring member62by way of a spring contact. As a result, the pressure sensitive element20of the sensing unit831has been electrically connected via both the flexible printed-circuit board50and the circuit board40to the connector case60, namely a connector portion60.

In accordance with the pressure detecting apparatus shown inFIG. 26, since such an arrangement is employed that the sensing unit831has been provided on the tip portion of the pipe portion12corresponding to one edge portion of the housing10, the length of the pressure transferring member can be shortened as being permitted as possible, although this pressure transferring member has been conventionally arranged so as to extend over the entire pipe portion.

As previously explained, in the pressure detecting apparatus shown inFIG. 26, the electrical connection from the pressure sensitive element20located at the tip portion of the pipe portion12to the connector portion60is realized by employing the flexible printed-circuit board50.

In this case, it can be conceived that the connection between the pressure sensitive element20of the sensing unit831and the flexible printed-circuit board50is realized by a joint by way of a wire bonding technique. However, the inventors of the invention conceived to employ a flip chip joint whose necessary area is smaller than that of a wire bonding joint so as to realize a more compact structure instead of the wire bonding joint.

FIG. 27AandFIG. 27Bare diagrams for indicating detailed structures as to a flip chip joint between one edge portion51of the flexible printed-circuit board50and the pressure sensitive element20of the sensing unit831in the pressure detecting apparatus functioning as the prototype model shown inFIG. 26. This flip chip joint has employed a typical arrangement of bumps832.

In the drawings,FIG. 27Ais a plan view for indicating a condition of a flip chip joint in the flexible printed-circuit board50before being bent.FIG. 27Bis a side view for representing a condition of a flip chip joint under such a status that the flexible printed-circuit board50has been assembled to the pressure detecting apparatus, namely, after the flexible printed-circuit board50has been bent.

It should be understood thatFIG. 27Ais the plan view which corresponds to such a plane ofFIG. 27Bviewed from the upper direction. The bumps832which are located under the pressure sensitive element20should be indicated by using a hidden line. However, for the sake of a simple observation, the bumps832are indicated by using a solid line inFIG. 27A.

As to the flexible printed-circuit board50, after one edge portion51thereof has been connected to the pressure sensitive element20via the bumps832such as solder bumps, or stud bumps, the other edge portion52thereof is inserted into the pipe portion12. As a result, a portion853of this flexible printed-circuit board50is bent as represented inFIG. 27B.

Then, in this case, as a typical arrangement of the bumps832on the arranging plane of the bumps832in the sensing unit831, the bumps832have been arranged at four corner portions of a surface of the pressure sensitive element20. Thus, the pressure sensitive element20has been electrically and mechanically connected to the flexible printed-circuit board50by way of the flip chip joint via these bumps832.

As previously explained, in the case of such a pressure detecting apparatus that the pressure sensitive element20, namely the sensing unit831has been connected to the flexible printed-circuit board50by way of the flip flop joint, if a cooling/heating cycle is repeatedly carried out, then a large amount of stresses may be produced in the bump joint portions, because of differences in thermal expansion coefficients of these structural elements, in particular, a difference between a thermal expansion coefficient as to the pressure sensitive element20made of silicon, and another thermal expansion coefficient as to the flexible printed-circuit board50made of resin.

Also, while the sensing unit831repeatedly receives pressure by the detected pressure, the bumps832are depressed by this pressure, so that a large amount of stresses may be produced in the bump joint portions. Then, in the bump joint portions which have received the stresses, there is such a risk that a wire disconnection may eventually occur.

In view of the above problem, pressure detecting apparatus according to an eighth embodiment of the present invention is provided.FIG. 14is a sectional view for schematically showing an entire structure of the pressure detecting apparatus100according to the eighth embodiment.

Also,FIG. 15AandFIG. 15Bare enlarged views for showing flip chip joint portions between a pressure sensitive element20of a sensing unit831and a flexible printed-circuit board50indicated inFIG. 14.FIG. 15Ais a plan view for indicating a condition of a flip chip joint in the flexible printed-circuit board50before being bent.FIG. 15Bis a side view for representing a condition of a flip chip joint under such a status that the flexible printed-circuit board50has been assembled to the pressure detecting apparatus, namely, after the flexible printed-circuit board50has been bent.

It should be understood thatFIG. 15Ais a plan view which corresponds to such a plane ofFIG. 15Bviewed from the upper direction. Bumps832and dummy bumps833which are located under the pressure sensitive element20should be indicated by using a hidden line. However, for the sake of a simple observation, both the dummy bump833and the bumps832are indicated by using a solid line inFIG. 15A. Further, inFIG. 15A, in order to discriminate the bump832from the dummy bums833, the dummy bumps833have been hatched.

Although usage of the pressure detecting apparatus100is not limited, this pressure detecting apparatus100may be applied as a combustion pressure sensor.

In this case, the combustion pressure sensor corresponds to such a sensor that while a pipe portion12of a housing10is mounted in a mounting hole formed in, for example, an engine block of an automobile as an object to be detected by way of a screw coupling manner, pressure (namely, internal cylinder pressure) within a combustion chamber is detected as detected pressure.

The pressure detecting apparatus100according to this embodiment is arranged by mainly comprising: the housing10; the sensing unit831provided on the housing10, for outputting a signal in response to detected pressure; a connector unit as a connector case60provided on the housing10, for deriving the signal from the sensing unit831; and also, the flexible printed-circuit board50stored in the housing10, for electrically connecting the sensing unit831to the connector unit as a connector case60.

The housing10is constituted by a cylindrical main body portion11and the pipe portion12. The pipe portion12having as elongated cylindrical shape is made narrower than the main body portion11.

These main body portion11and pipe portion12are made of a metal such as a stainless steel, which has been processed by cutting, cold forging operation, and the like. In this embodiment, although the pipe portion12has a cylindrical pipe shape, the pipe portion12may alternatively have a rectangular pipe shape.

It should also be noted that in the housing10, the main body portion11and the pipe portion12may be formed in an integral body. Alternatively, the main body portion11and the pipe portion12may be separately formed, and thereafter, both of these portions11and12may be joined with each other to be formed in an integral body by way of welding, adhering, press-fitting, screw coupling, caulking etc.

Also, a screw portion13has been formed on an outer peripheral plane of the pipe portion12in the housing10. The screw portion13can be screw-coupled to the above-described engine block functioning as the object to be detected.

As previously described, the pressure detecting apparatus100of this embodiment has been arranged in such a manner that the housing10is provided with the pipe portion12having the elongate shape, while the pipe portion12is projected from one edge side of this housing10.

In this case, the pipe portion12of the housing10is inserted into the mounting hole, and is mounted via the screw portion13. The mounting hole has been formed in the engine block as a screw hole. As a result, the pressure detecting apparatus100is mounted on the engine block.

Then, under such a condition that this pressure detecting apparatus100is mounted on the engine block, pressure (namely, internal cylinder pressure) within the combustion chamber as detected pressure is applied from the tip portion of the pipe portion12as indicated by an arrow “Y” inFIG. 14andFIG. 15A,FIG. 15Bin a reverse printing manner. In other words, in the pressure detecting apparatus100of this first embodiment, the detected pressure is applied to one edge portion of the housing10.

Also, in this pressure detecting apparatus100, the sensing unit831for outputting a signal in response to detected pressure has been provided on one edge portion of the housing10, namely, the tip portion of the pipe portion12.

In this case, the sensing unit831has been constituted by a pressure-receiving-purpose diaphragm15, a metal stem21, a pressure transferring member16, and a pressure sensitive element20. The pressure-receiving-purpose diaphragm15is provided on the tip portion of the pipe portion12, and is to receive detected pressure (namely, pressure which should be detected). The pressure transferring member16has been provided in the metal stem21. The detected pressure is transferred from the pressure-receiving-purpose diaphragm15via the pressure transferring member16to the pressure sensitive element20.

Concretely speaking, the pressure sensitive element20has been mounted on a surface of a diaphragm23by way of a glass joint in the metal stem21functioning as a holding member having a hollow cylindrical shape, one edge side of which is an opening portion22, and the other edge side of which is the diaphragm23.

In this pressure detecting apparatus100, this pressure sensitive element20owns a strain gauge function. This strain gauge function may output a signal in response to, for example, detected pressure based upon a strain caused by the detected pressure.

The metal stem21is such a metal member which has been processed so as to have the hollow cylindrical shape. A flange24has been formed on an opening edge portion of the opening portion22, while this flange24is projected along a direction perpendicular to a circumferential plane thereof. In this embodiment, although the hollow portion of the metal stem21has a cylindrical shape, the invention is not limited thereto. Alternatively, this hollow portion may have a rectangular cylindrical shape.

Then, the metal stem21has been inserted into the pipe portion12in such a manner that the diaphragm-sided portion23of this metal stem21is directed to the inner portion of the pipe portion12, and the opening portion-sided portion thereof is directed to the combustion chamber. Then, the flange24of the metal stem21has been fixed to the opening edge portion of the tip portion of the pipe portion12by way of an adhering member, a welding manner, or a pressure welding manner.

Furthermore, in the pressure detecting apparatus100of this embodiment, as indicated inFIG. 14,FIG. 15AandFIG. 15B, a diaphragm15has been provided on the tip portion of the pipe portion12in the housing10in such a manner that this diaphragm15covers the opening portion22of the metal stem21.

It should be understood that this diaphragm15will be referred to as “pressure-receiving-purpose diaphragm15” hereinafter in order to be discriminated from the above-explained diaphragm23of the metal stem21in this embodiment and the respective embodiments (will be explained later).

In this case, the pressure-receiving-purpose diaphragm15is made to a disk shape, for example, from stainless steel. A peripheral portion of the pressure-receiving-purpose diaphragm15is joined to the flange24of the metal stem21by way of welding so as to be fixed on this flange24. As a result, this pressure-receiving-purpose diaphragm15has been formed with the metal stem21in an integral body.

Then, this pressure-receiving-purpose diaphragm15receives the detected pressure as indicated by the arrow in the reverse printing manner inFIG. 14. Concretely speaking, the pressure-receiving-purpose diaphragm15is set so as to receive combustion pressure (internal cylinder pressure), while this diaphragm15is faced to the combustion chamber under such a condition that the pressure detecting apparatus100is mounted on the engine block.

Also, as shown inFIG. 14,FIG. 15A, andFIG. 15B, in this pressure detecting apparatus100, a pressure transferring member16has been provided in the hollow portion of the metal stem21. In other words, the pressure transferring member16has been interposed between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20. This pressure transferring member16is made of, for example, a metal, ceramics, or the like.

In this case, one edge portion of the pressure transferring member16is contacted to the diaphragm23of the metal stem21under such a condition that this pressure transferring member16applies weight to this diaphragm23. The other edge portion of the pressure transferring member16is contacted to the pressure-receiving-purpose diaphragm15under such a condition that this other edge portion applies weight to this diaphragm15.

As a consequence, as previously explained, even when the pressure transferring member16is shrunk by the linear expansion coefficient thereof, and the pressure within the combustion chamber becomes negative pressure, the contacts between the pressure transferring member16and both the diaphragms15and23can be properly secured.

In the examples shown inFIG. 14,FIG. 15A, andFIG. 15B, although the pressure transferring member16is a spherical-shaped member, the shape of the pressure transferring member16is not limited only to this spherical shape in this pressure detecting apparatus100.

Then, the detected pressure is received by the pressure-receiving-purpose diaphragm15, and is applied from this pressure-receiving-purpose diaphragm15via the pressure transferring member16to both the diaphragm23of the metal stem21and the pressure sensitive element20.

Also, although not limited to the above-described pressure sensitive element20in this embodiment, such an element may be employed as the pressure sensitive element20having the strain gauge function. That is, in this pressure sensitive element, a bridge circuit constructed of a diffusion resistance element is formed with respect to a silicon semiconductor chip by way of, for example, a semiconductor process.

Such a semiconductor chip having the strain gauge function may own the following function. That is, when the diaphragm23of the metal stem21is deformed by pressure, since the strain gauge30itself is strained in response to this deformation, a change in resistance values which is produced by this strain, is converted into an electric signal, and then, this electric signal is outputted.

While the diaphragm23of the metal stem21and the pressure sensitive element20are arranged as strain portions which are strained by receiving weights produced by the detected pressure, these strain portions may give an influence to basic performance of the pressure detecting apparatus100.

In this case, as to metal materials which constitute the metal stem21, low thermal expansion coefficients are necessarily required, since these metal materials receive high pressure, so that strengths of the metal materials are high, and also, since the pressure sensitive element20made of a Si semiconductor and the like is joined to the metal stem21by low melting glass.

Concretely speaking, as a metal material for the metal stem21, Fe, Ni, Co, or a material whose primary constituent is Fe or Ni and to which Ti, Nb, Al, or Ti, Nb are added as a precipation emphasizing material may be selected. For example, precipation hardening type stainless steel may be selected. The metal stem21may be formed by way of pressing, cutting, and cold forging operation.

Also, as shown inFIG. 14, a circuit board40formed of a ceramic substrate, or the like, has been provided inside the main body portion11of the housing10in the pressure detecting apparatus100of this embodiment.

This circuit board40has been provided so as to cover the opening portion of the pipe portion12at a boundary with respect to the main body portion11. A peripheral portion of the circuit board40has been fixed on the housing10by way of, for example, an adhering manner.

An IC chip42has been adhered on a plane of the circuit board40so as to be mounted thereon. This plane is located opposite to the opening portion of the pipe portion12. In this IC chip42, a circuit has been manufactured which amplifies and adjusts an output signal from the pressure sensitive element20.

Then, this IC chip42has been electrically connected to the circuit board40by using a bonding wire44made of aluminum (Al), or gold.

Further, as indicated inFIG. 14,FIG. 15A, andFIG. 15B, in this pressure detecting apparatus100, the circuit board40has been electrically connected to the above-explained pressure sensitive element20of the sensing unit831by employing the flexible printed-circuit board50corresponding to the wiring member.

As the flexible printed-circuit board50, a general-purpose printed-circuit board may be employed which has been manufactured by patterning a conductor such a copper (Cu) on a base, e.g., polyimide resin. As indicated inFIG. 14, this flexible printed-circuit board50has been arranged inside the pipe portion12of the housing10so as to extend along the longitudinal direction of the pipe portion12.

In the example as shown inFIG. 15AandFIG. 15B, one edge portion51of the flexible printed-circuit board50has been electrically and mechanically joined via a plurality of bumps832with respect to the pressure sensitive element20of the sensing unit831by way of a flip chip joint.

As this bump832, a solder bump, a stud bump such as gold, and the like may be employed. Concretely speaking, although not shown in the drawing, pads formed on the surface of the pressure sensitive element20have been connected via the bumps832to conductor portions such as pads formed on the surface of the flexible printed-circuit board50.

In this case, in this embodiment, the pressure sensitive element20corresponds to a connection portion with respect to the bumps832in the sensing unit831. The surface of the pressure sensitive element20which is located opposite to the flexible printed-circuit board50constitutes an arranging plane of the bumps832of the sensing unit831.

Then, as shown inFIG. 15A, in this embodiment, similar to the typical bump arrangement (refer toFIG. 27A), the bumps832have been arranged at 4 corner portions on the arranging plane, namely the surface of the pressure sensitive element20.

Further, as shown inFIG. 15AandFIG. 15B, in the pressure detecting apparatus100of this first embodiment, dummy bumps833have been provided in the vicinity of the bumps832between the sensing unit831, namely the pressure sensitive element20, and the one edge portion51of the flexible printed-circuit board50. The dummy bumps833are used so as to relax stresses which are applied to the bumps832.

As this dummy bump833, such a bump constructed of a solder bump, a stud bump, or the like, may be employed similar to the above-explained bumps832which are employed so as to flip-chip-join the pressure sensitive element20to the flexible printed-circuit board50.

Then, the pressure sensitive element20of the sensing unit831has been mechanically connected to the one edge portion51of the flexible printed-circuit board50via the dummy bumps833. It should also be noted that the dummy bumps833may not electrically connect the pressure sensitive element20to the flexible printed-circuit board50.

Then, as shown inFIG. 14, the flexible printed-circuit board50has been bent from the one edge portion51of this flexible printed-circuit board50, and a portion of this flexible printed-circuit board50which is located on the side of the other edge portion52thereof rather than a bending portion653corresponding to this bending portion is elongated inside the pipe portion12along the direction of the circuit board40. The above-described one edge portion51corresponds to the joint portion of the flexible printed-circuit board50to the pressure sensitive element20.

On the other hand, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is positioned at the main body portion11of the housing10. Then, the other edge portion52of the flexible printed-circuit board50is positioned, on the circuit board40via a through hole46provided on the circuit board40, on a plane opposite to the plane on which the IC chip42is mounted.

Then, the other edge portion52of the flexible printed-circuit board50has been electrically connected to the circuit board40on the plane of the circuit board40, which is located opposite to the mounting plane of the IC chip42by way of solder, and the like.

Also, in this pressure detecting apparatus100, as shown inFIG. 14, in the housing10, a connector case60having a terminal61has been provided at a position opposite to the connecting plane of the circuit board40with respect to the flexible printed-circuit board50.

This connector case60is made of such a resin as PPS (polyphenylene salfide). The terminal61has been formed with the connector case60in an integral form by way of insert molding, and the like. This connector case60has been constructed as a connector portion60capable of deriving a signal from the pressure sensitive element20of the sensing unit831.

Then, the terminal61of the connector case60has been electrically connected to the circuit board40via a spring member62by way of a spring contact. As a result, the pressure sensitive element20of the sensing unit831has been electrically connected via both the flexible printed-circuit board50and the circuit board40to the connector case60.

Also, as indicated inFIG. 14, since the edge portion14of the main body portion11of the housing10is caulked to the connector case60, the connector case60has been fixed on the housing10in an integral manner.

Then, the terminal61of the connect portion60may be electrically connected via a wiring member (not shown) to an ECU of an automobile, and the like. As a result, this pressure detecting apparatus100may transmit/receive a signal with respect to an external unit.

A description is made of a method for manufacturing the pressure detecting apparatus100having the above-described structure.

First, the pressure transferring member16is interposed between the metal stem21and the pressure-receiving-purpose diaphragm15. Concretely speaking, the pressure transferring member16is inserted into the hollow portion of the metal stem21, and then, the pressure-receiving-purpose diaphragm15is mounted so as to cover the opening portion22of the metal stem21.

Next, under such a condition that weight is applied from the pressure-receiving-purpose diaphragm15via the pressure transferring member16to the diaphragm23of the metal stem21, this pressure-receiving-purpose diaphragm15is welded. As a result, the pressure-receiving-purpose diaphragm15is connected to the metal stem21in an integral body.

In other words, while keeping such a condition that the weight is applied in a direction along which the pressure transferring member16is sandwiched by both the metal stem21and the pressure-receiving-purpose diaphragm15, the entire peripheral portion of the pressure-receiving purpose diaphragm15is welded with respect to the flange24by way of a laser welding manner.

After the pressure-receiving-purpose diaphragm15has been welded so as to connect this pressure-receiving-purpose diaphragm15to the metal stem21in the integral body in the above-explained manner, the pressure sensitive element20is mounted on the metal stem21.

Concretely speaking, the pressure sensitive element20is mounted on an outer surface of the diaphragm23of the metal stem21while interposing low-melting-point glass (not shown). Then, this glass is sintered in order that the pressure sensitive element20is glass-joined to the metal stem21.

Next, in such a unit that the pressure transferring member16, the metal stem21, the pressure sensitive element20, and the pressure-receiving-purpose diaphragm15have been assembled in the integral form, namely in the sensing unit831, the one edge portion51of the flexible printed-circuit board50is joined via the bumps832with respect to the pressure sensitive element20in the flip chip joint manner.

Now, while the bumps832have been previously formed on the surface of the pressure sensitive element20, the one edge portion51of the flexible printed-circuit board50is contacted to the pressure sensitive element20formed on the bumps832, and then, the connection is carried out via the bumps832by way of solder reflow, and pressure adhesion manners.

Next, the portion of the flexible printed-circuit board50on the side of the other edge portion52thereof is inserted from the tip portion of the pipe portion12of the housing10, and then, the other edge portion52of the flexible printed-circuit board50is drawn out up to an internal portion of the main body portion11of the housing10.

Subsequently, the other edge portion52of the flexible printed-circuit board50is penetrated through the through hole60of the circuit board40, and is connected to the circuit board40by way of solder, or the like. The IC chip42has been mounted on this circuit board40by way of the wire bonding manner.

Next, the circuit board40is joined to the main body portion11of the housing10so as to be fixed on this main body portion11. Thereafter, the connector case60is assembled to the main body portion11of the housing10, and since the edge portion14of the housing10is caulked, the connector case60is fixed with the housing10.

When this connector case60is assembled in the housing10, the terminal61is contacted via the spring member62to the circuit board40in the spring contact manner so as to electrically connect the terminal61with the circuit board40. As a result, the pressure detecting apparatus100shown inFIG. 14may be accomplished in accordance with the above-explained manner.

Since the accomplished pressure detecting apparatus100is mounted via the screw portion13of the housing10in the screw hole formed in the engine block, the object to be detected, this pressure detecting apparatus100may be connected/fixed on the engine block.

Then, when pressure (namely, internal cylinder pressure) within the combustion chamber is applied to the diaphragm23of the metal stem21as indicated by the arrow “Y” inFIG. 14,FIG. 15A, andFIG. 15B, from the pressure-receiving-purpose diaphragm15via the pressure transferring member16, the diagram22of the metal stem21is deformed by this applied pressure, and then, this deformation is converted into an electric signal by the pressure sensitive element20so as to detect the pressure.

Then, the electric signal derived from the pressure sensitive element20of the sensing unit831is transferred via the flexible printed-circuit board50to the circuit board40, and is processed by the IC chip42, for example. The processed signal is outputted from the terminal61to an external unit.

In the above-described manufacturing method, after the pressure-receiving-purpose diaphragm15had been welded so as to construct the pressure-receiving-purpose diaphragm15, the pressure transferring member16, and the metal stem21in the integral form, the pressure sensitive element20has been mounted on the metal stem21. Alternatively, after the pressure sensitive element20has been mounted on the metal stem21, the pressure-receiving-purpose diaphragm15, the pressure transferring member16, and the metal stem21may be formed in an integral body.

However, the following manufacturing method may be preferably employed as explained in the above-described manufacturing method. That is, while the pressure transferring member16is interposed between the metal stem21and the pressure-receiving-purpose diaphragm15, under such a condition that the weight is applied from the pressure-receiving-purpose diagram15via the pressure transferring member16to the metal stem21, after the pressure-receiving-purpose diaphragm15is welded, the pressure sensitive element20is mounted on the metal stem21.

This reason is given as follows: That is, in such a method that after the pressure receiving element20has been mounted on the metal stem21by way of the glass joint, the pressure-receiving-purpose diaphragm15is welded to the metal stem21, the below-mentioned problems may occur.

As a first problem, since the length of the pressure transferring member16is shortened so as to reduce the distance between the pressure sensitive element20and the welding portion of the pressure-receiving-purpose diaphragm15, an adverse influence caused by the welding heat becomes large. As a result, the welding heat of the pressure-receiving-purpose diaphragm15may give a thermal damage with respect to the pressure sensitive element20on the metal stem21.

As a second problem, after the pressure sensitive element20has been attached to the metal stem21, under such a condition that the weight is applied from the pressure transferring member16via the diaphragm23of the metal stem21to the pressure sensitive element20, the pressure-receiving-purpose diaphragm15is fixed in the welding manner. As a result, the weight which was applied at this time is left in the pressure sensitive element20after the pressure-receiving-purpose diaphragm15has been welded. As a consequence, this remaining weight may produce an offset of an output.

To the contrary, in accordance with this preferred manufacturing method, before the pressure sensitive element20is mounted on the metal stem21, while the weight is applied from the pressure-receiving-purpose diaphragm15via the pressure transferring member16, the pressure-receiving-purpose diaphragm15is welded to the metal stem21.

As a result, when the pressure-receiving-purpose diaphragm15is welded while applying the weight, the pressure sensitive element20is not yet mounted on the metal stem21but is not present. As a consequence, there is no such a problem that the thermal damage is given to the pressure sensitive element20by welding the pressure-receiving-purpose diaphragm15, and the weight is applied. Based upon this reason, the above-explained manufacturing method is preferable.

On the other hand, according to this embodiment, in the pressure detecting apparatus comprising: the housing10; the sensing unit831provided in the housing10, for outputting the signal in response to the detected pressure; and the connector portion60provided on the housing10, for deriving the signal from the sensing unit831, such a pressure detecting apparatus100having the below-mentioned feature points may be provided.

That is, the sensing unit831is provided on the one edge side of the housing10, namely, the tip portion of the pipe portion12in this embodiment, and also, the detected pressure is applied to the one edge portion of the housing10.

The flexible printed-circuit board50for electrically connecting the sensing unit831to the connector portion60is stored inside the housing10. The sensing unit831is mechanically and electrically connected to the one edge portion51of the flexible printed-circuit board50via the plurality of bumps832by way of the flip chip joint manner.

Furthermore, the dummy bumps833for relaxing the stresses applied to the bumps832are provided between the sensing unit831and the one edge portion51of the flexible printed-circuit board50in the vicinity of the bumps832. The sensing unit831is mechanically connected via the dummy bumps833to the one edge portion51of the flexible printed-circuit board50.

In accordance with the pressure detecting apparatus100having such featured points, since the sensing unit831can be located in the vicinity of the pressure detecting environment, sensor characteristics such as sensitivity can be improved.

Concretely speaking, since the sensing unit831is located close to the pressure detecting environment, the distance between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20can be shortened, and the length of the pressure transferring member16can be made shorter than that of the prior art. As a result, the sensor characteristic may be improved.

For instance, in such a case that the pressure detecting apparatus100is applied as a combustion pressure sensor of an engine, when the length of the pressure transferring member16is made long, a resonant frequency of the pressure transferring member16is superimposed with a vibration frequency of knocking of combustion, so that a resonant phenomenon may occur in the pressure transferring member16. Accordingly, such a problem may occur with respect to a sensor characteristic. That is, knocking signals which are not originally large are embedded in noise which is produced by the resonant phenomenon of the pressure transferring member16, so that the knocking signals cannot be measured.

Also, in the case that the length of the pressure transferring member16is long, since the pressure transferring member16itself may be easily deformed, contact conditions between the pressure transferring member16and either the pressure-receiving-purpose diaphragm15or the pressure sensitive element20are changed. If such a change in the contact conditions happens to occur, then precision in pressure transfer characteristics is deteriorated, which may give an adverse influence to the sensor characteristic.

To the contrary, since the pressure detecting apparatus100of the present embodiment is constituted by positing the pressure sensitive element20closer to the pressure detecting environment so as to shorten the pressure transferring member16, it is possible to suppress the resonant problem and the deformation of the pressure transferring member16as much as possible, which are caused by making the pressure transferring member16long. Thus, the sensor characteristic can be improved.

Also, in accordance with the pressure detecting apparatus100of this embodiment, the electric connection between the sensing unit831and the connector portion60which is separated far from the sensing unit831can be properly realized by employing the flexible printed-circuit board50. Furthermore, since the sensing unit831is joined to the flexible printed-circuit board50by way of the flip chip joint manner, such an arrangement capable of suitably making the pressure detecting apparatus100compact may be realized.

Also, in accordance with this pressure detecting apparatus100, by the dummy bumps833, such an equivalent effect may be achieved as when the distances between the bumps832which are essentially located adjacent to each other are reduced. As a result, expansion strains between the bumps832can be decreased. Also, since the total number of the bumps832is essentially increased, a strain amount per one piece of the bump832can be reduced.

In other words, in this pressure detecting apparatus100, since by the structure of providing the dummy bumps833, a stress relaxing construction capable of relaxing the stress applied to the bumps832may be realized. Then, since such a stress relaxing construction using the dummy bumps833is employed, even when the stresses are applied to the bumps833, the applied stresses may be relaxed.

As a consequence, in accordance with this embodiment, in such a pressure detecting apparatus100that the sensing unit831provided on the one edge portion of the housing10is connected to the connector portion60provided on the housing10by the flexible printed-circuit board50, when the sensing unit831is joined to the flexible printed-circuit board50by the flip chip joint, even if the stresses are applied to the bumps832by the detected pressure and the cooling/heating cycle, line disconnections of the bump joint portions can be suppressed.

Also, in the pressure detecting apparatus100of this embodiment, the following construction may cause one of the features. That is, while the one edge portion51of the housing10has been arranged as the pipe portion12having the elongate shape, the sensing unit831is provided on the tip portion of the pipe portion12; the flexible printed-circuit board50is provided inside the pipe portion12, and the one edge portion51is joined to the sensing unit831and is bent from this joint portion; and, the portion on the side of the other edge portion52rather then this bending portion653is extended along the connector portion60within the pipe portion12to be electrically connected (via circuit board40in this example) to the connector portion60.

As explained above, according to the pressure detecting apparatus100having the elongate shape, this structure may be suitably arranged as a combustion pressure sensor, and the like.

Also, in the pressure detecting apparatus100of this embodiment, the following arrangement may constitute one of the featured arrangements thereof. That is, the sensing unit831is arranged by employing the pressure-receiving-purpose diaphragm15which is strained by receiving the detected pressure, and the pressure sensitive element20for outputting the signal based upon this strain of the pressure-receiving-purpose diaphragm15; and the pressure sensitive element20constitutes the connecting portions with the bumps832in the sensing unit831.

Then, in the pressure detecting apparatus100of this embodiment, the following arrangement may constitute one of the featured arrangements thereof. That is, the pressure sensitive element20has the strain gauge function for outputting the signal in response to the detected pressure based upon the strain caused by the detected pressure.

Moreover, in the pressure detecting apparatus100of this embodiment, the following arrangement may constitute one of the featured arrangements thereof. That is, the pressure transferring member16is interposed between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, while this pressure transferring member16transfers the pressure received by the pressure-receiving-purpose diaphragm15to the pressure sensitive element20.

As the pressure transferring member16, although a rod-shaped member may be employed, a spherical-shaped member has been employed as the pressure transferring member16in the example. In the case of the specific arrangement, as to the spherical-shaped member16functioning as the pressure transferring member, both a plane of this spherical-shaped member16which is contacted to the pressure-receiving-purpose diaphragm15, and another plane thereof which is contacted to the diaphragm23of metal stem21are spheres.

As a result, the contacts between these contact planes can be set as stable point contacts. Further, a total contact number between the pressure-receiving-purpose diaphragm15and the diaphragm23of the metal stem21, and the pressure transferring member16can be reduced.

As a consequence, the changes of the contact conditions between the pressure-receiving-purpose diaphragm15and the diaphragm23, and the pressure transferring member16can be suppressed as much as possible, the stable contact conditions can be secured in the respective contact portions, and also, deteriorations of the pressure transfer precision can be suppressed.

In this case, the spherical member functioning as the pressure transferring member16is hardly deformed, as compared with the rod-shaped pressure transferring member of the prior art, due to its shape effect. As a result, the stable contact conditions between this spherical member, and the pressure-receiving-purpose diaphragm15and the diaphragm23can be preferably maintained under suitable contact conditions.

It should also be noted that this spherical member as the pressure transferring member16may be not be a complete spherical shape as shown inFIG. 14,FIG. 15A, andFIG. 15B, but may be replaced by a slightly deformed sphere. For example, an elliptical sphere, or a “rugby ball” shaped sphere may be employed as this spherical member.

Also, as the pressure transferring member16whose contact planes with respect to the pressure-receiving-purpose diaphragm15and the diaphragm23of the metal stem21are spherical planes, the invention is not limited only to a spherical-shaped member. For instance, a member whose contact planes with the diaphragms15,23are spherical, but whose intermediate portion between both the spherical contact planes is a pillar shape may be employed.

In the above-described embodiment shown inFIG. 14,FIG. 15A, andFIG. 15B, the sensing unit831is comprised of the pressure-receiving-purpose diaphragm15and the metal stem21which are provided on the tip portion of the pipe portion12, the pressure transferring member15provided inside the metal stem21, and the pressure sensitive element20provided in the diaphragm23of the metal stem21.

The sensing unit831of this embodiment is not limited only to the example represented inFIG. 14,FIG. 15A, andFIG. 15B, but any type of sensing unit may be employed if it may output signals in response to the pressure received by these sensing units.

Next, other examples of the sensing unit831, which may be employed in this first embodiment, are indicated inFIG. 16toFIG. 18.

FIG. 16is a sectional view for schematically showing a sensing unit831as a first modification.FIG. 17is a sectional view for schematically showing a sensing unit831as a second modification.FIG. 18is a sectional view for schematically showing a sensing unit831as a third modification. It should also be understood that these sensing units31may be alternatively employed in the below-mentioned respective embodiments.

In the first modification shown inFIG. 16, the sensing unit831comprises the pressure-receiving-purpose diaphragm15, the metal stem21, and the pressure sensitive element20. The pressure sensitive element20constitutes a connecting portion with the bumps832in the sensing unit831, which is similar to the above-explained sensing unit831.

However, in this first modification, there is no pressure transferring member between the pressure-receiving-purpose diaphragm15and the pressure sensitive element20, whereas the pressure-receiving-purpose diaphragm15is directly contacted to the diaphragm23of the metal stem21.

Concretely speaking, as shown inFIG. 16, a convex portion15awhich is projected along the direction of the pressure sensitive element20has been formed on the pressure-receiving-purpose diaphragm15, and a projected tip portion of this convex portion15ahas been contracted to the rear plane of the diaphragm23of the metal stem21. In this case, the pressure-receiving-purpose diaphragm15is in, for example, a disk shape, and the convex portion15ahas such a shape similar to a “navel” which is located at a center position of this circle.

In the sensing unit831of this first modification, the detected pressure which has been applied the pressure-receiving-purpose diaphragm15is applied via the convex portion15ato the diaphragm23of the metal stem21. Then, the diaphragm23of the metal stem21is deformed, and the deformation is converted into an electric signal by the pressure sensitive element20in order to detect pressure.

In the second modification shown inFIG. 17, similar to the first modification shown inFIG. 16, this sensing unit831is also arranged in such a manner that while the convex portion15ais provided on the pressure-receiving-purpose diaphragm15, this pressure-receiving-purpose diaphragm15is directly made contact to the diaphragm23of the metal stem21, so that a pressure transferring member is omitted. In this case, the convex portion15ais further deformed.

InFIG. 16, the convex portion15aof the pressure-receiving-purpose diaphragm15has been formed by way of a cutting process or the like. In contrast, in a pressure-receiving-purpose diaphragm15shown inFIG. 17, the convex portion15ahas been manufactured by conceiving a diaphragm plane having a flat plate shape by way of a pressing process, so that this convex portion15amay be formed in a simple manner.

In the third modification shown inFIG. 18, the sensing unit831has been arranged by both the metal stem21and the pressure sensitive element20, while a diaphragm has also been omitted.

As shown inFIG. 18, the opening portion22of the metal stem21is directly exposed to a pressure detecting environment such as a combustion chamber, and detected pressure such as internal cylinder pressure is directly applied to the diaphragm23of the metal stem21.

In other words, in the sensing unit831of this third modification, the detected pressure is directly applied to the diaphragm23of the metal stem21; the diaphragm23of the metal stem21is deformed by this pressure; and then, this deformation is converted into an electric signal by the pressure sensitive element20so as to detect the pressure.

Ninth Embodiment

FIGS. 19A to 19Iare diagrams for schematically indicating plain structures of flip chip joint portions between a sensing unit831and one edge portion51of a flexible printed-circuit board50, according to a ninth embodiment of the present invention. It should be noted that different points from the above-described embodiment will be mainly described, and the same portions thereof will be simply described.

It should be also understood that inFIGS. 19A to 19I, bumps832which are located under a pressure sensitive element20should be indicated by using a hidden line, however, for the sake of a simple observation, the bumps832are indicated by using a solid line.

Also, in a pressure detecting apparatus of this embodiment, the below-mentioned arrangements are similar to those of the above-described embodiments. That is, in the pressure detecting apparatus comprising: a housing10, the above-described sensing unit831provided on the housing10, and the above-described connector portion60provided on the housing10, the sensing unit831is provided on one edge portion of the housing10, and detected pressure is applied to the one edge portion of the housing10; the flexible printed-circuit board has been stored inside the housing10; and the pressure sensitive element20of the sensing unit831is electrically and mechanically connected via a plurality of bumps832with respect to the one edge portion51of the flexible printed-circuit board50by way of a flip chip joint.

The pressure detecting apparatus of this embodiment is featured by that as a stress relaxing structure in a flip chip joint portion between the sensing unit831and the flexible printed-circuit board50, an arranging plane as to the bumps832of the sensing unit831has a feature, namely, an arranging mode of the bumps832on the surface of the pressure sensitive element20owns a feature.

In other words, the pressure detecting apparatus of this embodiment is featured by that in the pressure detecting apparatus100shown inFIG. 14, the structure of the flip chip joint portion between the sensing unit831and the flexible printed-circuit board50is modified, and other structural portions are similar to those shown inFIG. 14.

As indicated inFIG. 15A, these bumps832are generally arranged on the surface of the pressure sensitive element20at the four corner portions of the arranging plane of the bumps832, namely, the surface of the pressure sensitive element20.

In contract, in this embodiment, as shown inFIG. 19AtoFIG. 19I, various sorts of examples may be employed.

In the examples shown inFIG. 19AtoFIG. 19F, on the surface of the pressure sensitive element20having a rectangular disk shape, namely, on the arranging plane of the bumps832, all of the bumps832are arrayed in one column from one side to the other of the opposing sides.

In the examples shown inFIG. 19GtoFIG. 19H, on the surface of the pressure sensitive element20having a rectangular disk shape, namely, on the arranging plane of the bumps832, all of the bumps832are arrayed in one column along a diagonal line.

In the example shown inFIG. 19I, on the surface of the pressure sensitive element20having a rectangular disk shape, namely, on the arranging plane of the bumps832, all the bumps832are arranged in the center portion thereof, instead of in the outer peripheral portion as explained in the prior art.

As previously explained, in this embodiment, such a pressure detecting apparatus may be provided in which on the arranging plane of the bumps832of the sensing units31, namely, on the surface of the pressure sensitive element20, all of the bumps832are arrayed in one column from one edge portion of the relevant arranging plane to the other edge portion thereof, or are arranged in the center portion of the arranging plane.

In accordance with this embodiment, the distances between the adjoining bumps832can be made shorter than those of the conventional arranging structure (refer toFIGS. 27A and 27B) of the bumps, and the expansion strains between the bumps832can be decreased. In other words, in this embodiment, one mode of the bumps832capable of reducing the distances between the bumps832may be provided.

As a consequence, in accordance with this embodiment, in such a pressure detecting apparatus100that the sensing unit831provided on the one edge portion of the housing10is connected to the connector portion60provided on the housing10by the flexible printed-circuit board50, when the sensing unit831is joined to the flexible printed-circuit board50by the flip chip joint, even if the stresses are applied to the bumps832by the detected pressure and the cooling/heating cycle, line disconnections of the bump joint portions can be suppressed.

As apparently, such pressure detecting apparatus having the various sorts of featured points shown in the above-described embodiments may be additionally provided in this embodiment.

Tenth Embodiment

FIG. 20is a diagram for schematically indicating plain structures of flip chip joint portions between a sensing unit831and one edge portion51of a flexible printed-circuit board50, according to a tenth embodiment of the present invention. It should be noted that different points from the above-described embodiments will be mainly described, and the same portions thereof will be simply described.

Also, in a pressure detecting apparatus of this embodiment, the below-mentioned arrangements are similar to those of the above-described embodiments. That is, in the pressure detecting apparatus comprising: a housing10, the above-described sensing unit831provided on the housing10, and the above-described connector portion60provided on the housing10, the sensing unit831is provided on the one edge portion of the housing10, and detected pressure is applied to the one edge portion of the housing10; the flexible printed-circuit board has been stored inside the housing10; and the pressure sensitive element20of the sensing unit831is electrically and mechanically connected via a plurality of bumps832with respect to the one edge portion51of the flexible printed-circuit board50by way of a flip chip joint.

The pressure detecting apparatus of this embodiment is featured by that as a stress relaxing structure in a flip chip joint portion between the sensing unit831and the flexible printed-circuit board50, the below-mentioned interference member970is employed.

In other words, the pressure detecting apparatus of this embodiment is featured by that in the pressure detecting apparatus100shown inFIG. 14, the structure of the flip chip joint portion between the sensing unit831and the flexible printed-circuit board50is modified, and other structural portions are similar to those shown inFIG. 14.

Then, as shown inFIG. 20, in accordance with this embodiment, a pressure detecting apparatus is provided which is featured by that an interference member970capable of relaxing a stress produced by a difference in thermal expansion coefficients between the sensing unit831and the flexible printed-circuit board50is provided on the flexible printed-circuit board50.

In the example shown inFIG. 20, the interference member970corresponds to a board970. A thermal expansion coefficient of this board970is equal to that of the connection portion30with respect to the bump832in the sensing unit831, namely that of the pressure sensitive element20. Otherwise, the thermal expansion coefficient of the board970is equal to such an intermediate coefficient value between this pressure sensitive element20and the flexible printed-circuit board50.

Then, the board970functioning as this interference member is interposed and fixed between the bumps832and the flexible printed-circuit board50.

In this example, the bumps832are electrically and mechanically joined to the board970, whereas the board970is electrically and mechanically joined via an electric conductive adhesive agent, or solder (which are not shown) to the flexible printed-circuit board50. As a result, an electric conduction between the pressure sensitive element20and the flexible printed-circuit board50can be established.

Normally, since the pressure sensitive element20is made of silicon and the flexible printed-circuit board50is made of polyimide, as the board970having the above-explained thermal expansion coefficient characteristic, for instance, a board whose thermal expansion coefficient is nearly equal to that of silicon or intermediate between the thermal expansion coefficients of silicon and polyimide may be employed.

Although not limited, concretely speaking, in this embodiment, such a board made of ceramics, e.g., alumina and silica may be employed as the board970functioning as the interference member.

If such a board970is employed as the interference member, then the difference in the thermal expansion coefficients among the adjoining portions in the bump joint portion can be reduced. As a consequence, the stress which is produced by the cooling/heating cycle is the bump joint portion can be relaxed by the board970functioning as this interference member, and also, a strain amount per one bump832can be decreased by this board970.

As a consequence, in accordance with this embodiment, in such a pressure detecting apparatus100that the sensing unit831provided on the one edge portion of the housing10is connected to the connector portion60provided on the housing10by the flexible printed-circuit board50, when the sensing unit831is joined to the flexible printed-circuit board50by the flip chip joint, even if the stresses are applied to the bumps832by the detected pressure and the cooling/heating cycle, line disconnections of the bump joint portions can be suppressed.

Now, in this embodiment, as the interference member provided on the flexible printed-circuit board50, if such an interference member is available that may relax the stress produced by the difference in the thermal expansion coefficients between the sensing unit831and the flexible printed-circuit board50, then any types of interference members may be employed, and thus, the invention is not limited only to the board970shown inFIG. 20.

Next, other examples of the interference member which may be employed in this third embodiment are represented inFIG. 21andFIG. 22.

FIG. 21is a diagram for schematically showing a side structure of a flip chip joint portion with employment of an interference member971as a first modification of this embodiment.

In the first modification shown inFIG. 21, the interference member971has been arranged in such a manner that a plurality of bumps832are stacked between the sensing unit831and the flexible printed-circuit board50. InFIG. 21, while 3 pieces of these bumps832have been stacked, this stacked body71has been constructed as the interference member971.

If such a stacked body of the bumps832is employed as the interference member971, a distance between the sensing unit831and the flexible printed-circuit board970can be made long so that a tolerance with respect to a strain produced by a stress may be improved. As a result, a strain amount per one piece of the bump832can be reduced.

FIG. 22is a diagram for schematically showing a side structure of a flip chip joint portion with employment of an interference member972as a second modification of this embodiment.

In the second modification indicated inFIG. 22, the interference member972corresponds to a dummy board972made of the same material as that of the connection portion30with respect to the bumps832in the sensing unit831, namely that of the pressure sensitive element20. Although not concretely limited, since the pressure sensitive element20is normally made of a silicon semiconductor, this dummy board972may also be made as a silicon semiconductor substrate.

Then, the dummy board972is provided on a plane which is located opposite to such a plane that the pressure sensitive element20of the sensing unit831is connected in one edge portion51of the flexible printed-circuit board50, and is joined via the bumps832.

In accordance with this second modification, since the flexible printed-circuit board50is sandwiched by the pressure sensitive element20corresponding to the connection portion with respect to the bumps832in the sensing unit831, and the dummy board972made of the same material, a deformation of the flexible printed-circuit board50can be suppressed. As a consequence, a strain amount per one piece of the bump832can be reduced.

As previously explained, also in the first and second modifications shown inFIG. 21andFIG. 22, the above-explained operations and effects of this embodiment may be achieved. Also, as apparent from the foregoing description, in this embodiment, a pressure detecting apparatus having the various sorts of featured points shown in the above-described embodiment may be alternatively provided.

Eleventh Embodiment

FIG. 23is a diagram for schematically representing a plain structure of one edge portion51of a flexible printed-circuit board50according to an eleventh embodiment of the present invention, namely for showing the flexible printed-circuit board50before this flexible printed-circuit board50is bent. In this embodiment, different points from those of the above-explained embodiments will be mainly described, and the same portions will be simply explained.

Also in a pressure detecting apparatus of this embodiment, the below-mentioned arrangements are similar to those of the above-described embodiments. That is, in the pressure detecting apparatus comprising: a housing10, the above-described sensing unit831provided on the housing10, and the above-described connector portion60provided on the housing10, the sensing unit831is provided on the one edge portion side of the housing10, and detected pressure is applied to the one edge portion of the housing10; the flexible printed-circuit board has been stored inside the housing10; and the pressure sensitive element20of the sensing unit831is electrically and mechanically connected via a plurality of bumps832with respect to the one edge portion51of the flexible printed-circuit board50by way of a flip chip joint.

The pressure detecting apparatus of this embodiment employs the below-mentioned notch structure of the flexible printed-circuit board50as a stress relaxing structure in the flip chip joint portion between the sensing portion31and the flexible printed-circuit board50.

In other words, the pressure detecting apparatus of this embodiment is featured by that in the pressure detecting apparatus100shown inFIG. 14, the structure of the flip chip joint portion between the sensing unit831and the flexible printed-circuit board50is modified, and other structural portions thereof are similar to those shown inFIG. 14.

In this embodiment, as shown inFIG. 23, such a pressure detecting apparatus may be provided with the following featured structure. That is, on the one edge portion51of the flexible printed-circuit board50, notches855are formed among pads854corresponding to respective portions to which the bumps832are connected, so that the respective pads854can be independently displaced. These notches855may be formed by way of a press process, or a cutting tool.

As a result, the respective pads854to which the bumps832are connected can be independently displaced on the one edge portion51of the flexible printed-circuit board50, so that strains of the respective bumps832which are caused by stresses can be readily escaped, and a strain amount per one piece of the bump832can be reduced.

As a consequence, in accordance with this fourth embodiment, in such a pressure detecting apparatus100that the sensing unit831provided on the one edge portion of the housing10is connected to the connector portion60provided on the housing10by the flexible printed-circuit board50, when the sensing unit831is joined to the flexible printed-circuit board50by the flip chip joint, even if the stresses are applied to the bumps832by the detected pressure and the cooling/heating cycle, line disconnections of the bump joint portions can be suppressed.

In this embodiment, as to the notches855provided on the one edge portion51of the flexible printed-circuit board50, the invention is not limited only to the example shown inFIG. 23, but other examples may be employed if the respective pads854may be independently displaced while the notches855are used as boundaries.

FIG. 24AandFIG. 24Bare plan views for schematically showing other examples as to the notches855which may be employed in this embodiment. Although the notches855are the line shapes in the example shown inFIG. 23, the notches855indicated inFIG. 24AandFIG. 24Bmay have widths.

Also, in the examples shown inFIG. 23,FIG. 24A, and FIG.24B, the one edge portions51of the flexible printed-circuit boards50have been formed in the two-dimensional shape. Alternatively, as another modification shown inFIG. 25AandFIG. 25B, one edge portions51of flexible printed-circuit boards50may be formed in a three-dimensional shape.

In this modification,FIG. 25Ais a diagram for schematically representing a plain structure of the one edge portion51of the flexible printed-circuit board50under such a condition before this flexible printed-circuit board50is bent.FIG. 25Bis a diagram for schematically showing a side structure as to such a condition that the pressure sensitive element20is joined to the one edge portion51of the flexible printed-circuit board50shown inFIG. 25Ain a flip chip joint manner.

In the example shown inFIG. 25aandFIG. 25B, the respective pads854to which the bumps832are connected have been bent on the one edge portion51of the flexible printed-circuit board50in such a manner that the respective pads854are brought up along the direction of the bumps832, namely the direction of the sensing unit831.

According to this modification, the respective components to which the bumps832are connected in the flexible printed-circuit board50, namely the respective pads854can be readily displaced along the stacking direction of the sensing unit831, the bump832, and the flexible printed-circuit board50. As a consequence, a strain amount per one piece of the bump832can be further reduced.

As previously explained, also in the modifications shown inFIG. 24A,FIG. 24B,FIG. 25A, andFIG. 25B, the above-explained operations and effects of this fourth embodiment may be achieved. Also, as apparent from the foregoing description, in this embodiment, pressure detecting apparatus having the various sorts of featured points shown in the above-described embodiments may be alternatively provided.

In the example shown inFIG. 14, the IC chip42, the circuit board40, and various sorts of electric connecting members have been arranged on the portion between the pressure sensitive element20and the connector portion60within the housing10. However, the invention is not limited only to the structure of this portion, but may be properly modified.

Also, as to the shape of the housing10employed in the pressure detecting apparatus of the invention, the invention is not limited only to the housings10having such pipe portions12as indicated in the above-described embodiments.

In summary, the invention owns the following major structure. That is, in the pressure detecting apparatus arranged by that both the sensing unit and the connector portion are provided in the housing, the sensing unit is provided on the one edge portion side of the housing and the detected pressure is applied to the one edge portion of the housing; the flexible printed-circuit board for electrically connecting the sensing unit to the connector portion is stored inside the housing; the sensing unit is electrically and mechanically connected via the plural bumps to the one edge portion of the flexible printed-circuit board in the flip chip joint manner; and further, the stress relaxing structure capable of relaxing the stresses applied to the bumps is provided; and other structural portions may be properly changed in a design sense.