Fuel injection valve with cylinder internal pressure sensor

In the interior of a resin mold portion that constitutes a fuel injection valve, an amplifying member to which a power source terminal and a signal terminal are connected, is provided. A signal transmitting unit, which outputs a detection signal from a sensor, is connected electrically to a substrate of the amplifying member. Further, the amplifying member is molded integrally when the resin mold portion is formed. In addition, a pressure inside a combustion chamber of an internal combustion engine, which is detected by the sensor, is output through the signal transmitting unit to the amplifying member, is amplified by the amplifying member, and is output externally from the signal terminal.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2015-008429 filed on Jan. 20, 2015, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a fuel injection valve equipped with a cylinder internal pressure sensor, the sensor being capable of detecting a cylinder internal pressure in the interior of a combustion chamber, the fuel injection valve being used in a direct injection type internal combustion engine in which fuel is injected directly into the combustion chamber in the internal combustion engine.

Description of the Related Art

Heretofore, for example, as disclosed in Japanese Laid-Open Patent Publication No. 09-053483, with the aim of detecting a cylinder internal pressure of a combustion chamber in an internal combustion engine, it has been known to attach an internal pressure sensor to an end of a fuel injection valve. The internal pressure sensor is arranged between the end of the fuel injection valve and an attachment hole of a cylinder head that makes up the internal combustion engine. A lead line for transmitting to the exterior the detected cylinder internal pressure as an output signal is connected to the internal pressure sensor. In addition, the lead line is connected, for example, to an electronic control unit, whereby a control or the like is performed based on the cylinder internal pressure by outputting the cylinder internal pressure as an output signal to the electronic control unit.

SUMMARY OF THE INVENTION

However, with the above-described internal pressure sensor that is mounted on the fuel injection valve, the lead line, which is connected to the internal pressure sensor and the electronic control unit, is exposed to the exterior of the fuel injection valve. Therefore, in an assembled condition, or when the internal pressure sensor is attached to the cylinder head together with the fuel injection valve, there is a concern that a disconnection may occur as a result of loads that are applied with respect to the lead line, and that detection of the cylinder internal pressure cannot be performed due to such a disconnection.

Further, since the internal pressure sensor is arranged in contact with the cylinder head, it is easy for noise caused by vibrations or the like of the internal combustion engine to be generated, thus making it difficult to read out with high accuracy the detection value that is detected by the internal pressure sensor.

A general object of the present invention is to provide a fuel injection valve equipped with a cylinder internal pressure sensor, which protects a signal transmitting unit that transmits an output from the sensor, together with enabling an increase in detection accuracy.

The present invention is characterized by a fuel injection valve equipped with a cylinder internal pressure sensor, the fuel injection valve being configured to directly inject fuel into a combustion chamber of an internal combustion engine, the sensor being provided at an end of the fuel injection valve, the sensor being configured to detect a cylinder internal pressure in the interior of the combustion chamber, the fuel injection valve including a signal transmitting unit disposed in the interior of the fuel injection valve and configured to transmit a detection signal based on the cylinder internal pressure. The signal transmitting unit contains a first transmitting member connected to the sensor, a second transmitting member connected to the first transmitting member and configured to externally output the detection signal, and an amplifying unit disposed on the first transmitting member and configured to amplify the detection signal.

According to the present invention, in the fuel injection valve equipped with the cylinder internal pressure sensor that detects a cylinder internal pressure in the interior of a combustion chamber, the signal transmitting unit is provided which transmits a detection signal detected by the sensor, and the amplifying unit for amplifying the detection signal is disposed on the first transmitting member of the signal transmitting unit which is connected to the sensor.

Consequently, even in the case that noise is generated due to vibrations or the like of the internal combustion engine, it is possible for the detection signal in which noise is comparatively small to be amplified by the amplifying unit at a position near to the sensor, and a highly accurate detection signal can be obtained. Further, by disposing the signal transmitting unit including the amplifying unit in the interior of the housing, the signal transmitting unit can be protected, in contradistinction to the conventional fuel injection valve in which the wiring connected to the sensor is arranged on the exterior of the fuel injection valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIG. 1, a fuel injection valve10equipped with a cylinder internal pressure sensor (hereinafter referred to simply as a fuel injection valve10) includes a housing12, a resin mold portion (resin sealing portion)14provided on an outer circumferential side of the housing12, a fuel supply unit16disposed on a proximal end of the housing12and to which fuel is supplied, a fuel injector18disposed on a distal end of the housing12, a sensor20mounted on a distal end of the fuel injector18, and a signal transmitting unit24that electrically interconnects the sensor20and a signal terminal (second transmitting member)22connected to a non-illustrated electronic control unit (ECU) and thereby transmits output signals therebetween.

Below, the side of the fuel supply unit16in the fuel injection valve10will be referred to as a proximal end side (in the direction of the arrow A), and the side of the fuel injector18will be referred to as a distal end side (in the direction of the arrow B).

The housing12, for example, is constituted as a solenoid unit that drives the fuel injection valve10. The housing12includes a fixed core26that is disposed in the center thereof, a bobbin30that is provided on an outer circumferential side of the fixed core26and retains a coil28, a cylindrical holder32disposed further on a distal end outer circumferential side of the bobbin30, and a movable core (not shown) that is displaced under a magnetically excited action of the coil28.

The fixed core26extends further to the proximal end side (in the direction of the arrow A) of the housing12with respect to the proximal end of the holder32, and is arranged in the center of the later-described resin mold portion14. Annular first grooves34, which are engaged with the later-described resin mold portion14, are formed on the outer circumferential surface of the fixed core26. Further, the fuel supply unit16is disposed on the proximal end side of the fixed core26.

The bobbin30is formed in a cylindrical shape, for example, and is disposed between the fixed core26and the holder32. An engagement pin36(seeFIG. 2), which is engaged with another end of an amplifying member56, is formed on the proximal end side (in the direction of the arrow A) of the bobbin30. Further, on an outer circumferential side of the bobbin30, the coil28is wound in a radially inward recessed cavity, and a second signal transmitting member72that makes up the later-described signal transmitting unit24is disposed on the outer circumferential side of the coil28. The engagement pin36is disposed at a position on the side of a coupler44of the later-described resin mold portion14, in a circumferential direction of the cylindrical bobbin30.

Ends of the coil28extend to the proximal end side (in the direction of the arrow A) of the bobbin30, and are connected respectively to ends of a pair of drive terminals38that are incorporated in the later-described resin mold portion14. In addition, by the coil28being supplied with electric current from non-illustrated connectors through the drive terminals38, the coil28is excited and a magnetic force is generated. As a result, under a magnetic excitation action of the coil28in the housing12, the non-illustrated movable core is displaced inside the bobbin30, a valve element (not shown) disposed in the fuel injector18is attracted, and a valve open condition is brought about.

Further, on a proximal end outer circumferential surface of the holder32, a radially inward recessed annular second groove40is formed, and the later-described resin mold portion14is engaged therein.

The resin mold portion14, for example, is formed on the outer circumferential side of the housing12by being molded from a resin material. The resin mold portion14includes a main body section42, which is formed in a cylindrical shape, a coupler44that projects out sideways from the proximal end of the main body section42, and a connector46that interconnects the main body section42and the coupler44.

In addition, by the resin mold portion14being molded by the resin material, the molten resin material enters respectively into the first grooves34of the fixed core26disposed in the center of the main body section42, and the second groove40of the holder32disposed on the distal end side of the main body section42, whereby under an engaging action between the radially inwardly projecting first and second protrusions50,52and the first and second grooves34,40, the housing12is fixed with respect to the center and the distal end of the resin mold portion14(seeFIG. 2).

As shown inFIGS. 1, 2, and 4, the coupler44is formed, for example, with a rectangular shape in cross section, and projects in an obliquely upward direction, so as to be inclined at a predetermined angle with respect to the axial direction (the direction of arrows A and B) of the main body section42. Further, an end of the coupler44is opened and includes a space in the interior thereof, with power source terminals54and a signal terminal22of the later-described amplifying member (amplifying unit)56, and the pair of drive terminals38for energizing the coil28being provided in an outwardly exposed manner therein, respectively.

As shown inFIGS. 1 through 3, the amplifying member56, for example, is disposed in the interior of the resin mold portion14. The amplifying member56includes a substrate58with a rectangular cross section, the power source terminals54and the signal terminal22that are connected electrically to the substrate58, and a sealing member60, which is formed so as to cover the entirety of the substrate58. The amplifying member56is provided with the aim of amplifying a detection value (detection signal) detected by the sensor20, and outputting the amplified detection value from the signal terminal22to external.

Concerning the power source terminals54and the signal terminal22, as shown inFIGS. 3 and 4, for example, the signal terminal22is arranged substantially in the center in the transverse direction of the substrate58, and the pair of power source terminals54are arranged on both sides of the signal terminal22. In this state, the ends of the power source terminals54and the signal terminal22are connected electrically with respect to the substrate58by solder or the like, and the power source terminals54and the signal terminal22extend at a predetermined angle of inclination with respect to an end portion of the substrate58. More specifically, the two power source terminals54are arranged with respect to the substrate58so as to sandwich the signal terminal22between the pair of power source terminals54.

The sealing member60is formed, for example, from a resin material. In a state in which the ends of the power source terminals54and the signal terminal22are connected with respect to the substrate58, the sealing member60is formed so as to cover at a predetermined thickness the entirety of the substrate58, and to cover the ends of the power source terminals54and the signal terminal22that are connected to the substrate58. Consequently, the connection of the power source terminals54and the signal terminal22with respect to the substrate58is strongly maintained by the sealing member60.

Further, in the sealing member60, an engagement hole62is formed with a rectangular shape in cross section, which penetrates through the sealing member60in a thickness direction, on an end thereof on an opposite side from the end on the side of the power source terminals54. The engagement pin36of the bobbin30that constitutes the housing12is capable of being inserted in the engagement hole62.

In addition, when the resin mold portion14is formed, by insertion of the engagement pin36of the bobbin30into the engagement hole62of the sealing member60, the substrate58and the sealing member60are placed in a position corresponding to the connector46, and the power source terminals54and the signal terminal22are placed in a position corresponding to the coupler44. Then, in the above positional relationship, the amplifying member56is molded integrally with the resin mold portion14. Further, at the same time, an end of the amplifying member56, which resides on an opposite side from the end where the power source terminals54are connected, is connected to the signal transmitting unit24.

At this time, the proximal end sides of the power source terminals54, the signal terminal22, and the drive terminals38project out partially from an inner wall surface in the interior of the coupler44, and as shown inFIGS. 1 and 2, the amplifying member56is arranged at a position between the first protrusions50and the second protrusion52of the resin mold portion14along the axial direction (the direction of arrows A and B) of the fuel injection valve10.

By connecting a non-illustrated connector to the coupler44, electrical power is supplied to the amplifying member56and the sensor20through the power source terminals54, a detection value which is detected by the sensor20is output externally as an electric signal through the signal terminal22, and electric current to energize the coil28of the housing12is supplied from the drive terminals38.

The fuel supply unit16, for example, includes a supply passage (not shown) through which fuel is supplied, in the interior of the fixed core26, and a non-illustrated fuel pipe is connected to an end of the supply passage that opens on the proximal end side (in the direction of the arrow A) of the fuel injection valve10. In addition, the fuel supplied through the fuel pipe passes through the supply passage, and is supplied to the side of the fuel injector18(in the direction of the arrow B) disposed on the distal end side.

As shown inFIG. 1, the fuel injector18comprises a valve housing64that is connected to a distal end of the housing12, and a valve element (not shown) that is incorporated in the distal end of the valve housing64. In addition, fuel is supplied from the fuel supply unit16into the interior of the valve housing64, and by the valve element being moved toward the proximal end side (in the direction of the arrow A) upon excitation of the coil28, fuel is injected from the distal end into the combustion chamber at a predetermined pressure.

The valve housing64, for example, is formed from a metallic material. The valve housing64includes a flange66that closes the distal end of the housing12, and a tubular portion68that extends along a straight line to the distal end side (in the direction of the arrow B) from the flange66. The cylindrical sensor20is press-inserted and fitted on an outer circumferential side on the distal end of the tubular portion68.

The sensor20, for example, is equipped with a piezoelectric element (not shown) in the interior thereof, and connection terminals, which are connected to the piezoelectric element, are exposed on the proximal end side (in the direction of the arrow A). Further, a retaining portion80of a later-described cover member78abuts on the outer circumferential surface of the sensor20. In addition, a distal end inner circumferential side of the sensor20, for example, is coupled by being welded around the entire circumference with respect to the valve housing64.

The signal transmitting unit24includes a first signal transmitting member (first transmitting member)70disposed on the outer circumferential side of the valve housing64and connected to the sensor20, and a second signal transmitting member (first transmitting member)72accommodated in the holder32of the housing12, and which connects the first signal transmitting member70and the signal terminal22.

The first signal transmitting member70, for example, includes an insulating body74formed in a cylindrical shape from a resin material, and which is disposed on the outer circumferential side of the tubular portion68in the valve housing64, and a first conductive layer76disposed in the interior of the insulating body74. In addition, the first conductive layer76is electrically connected, for example by solder or the like, to a connection terminal of the sensor20.

The insulating body74is formed from a resin material such as a heat resistant resin or the like, and is formed such that the proximal end side thereof (in the direction of the arrow A) is expanded in diameter corresponding to the shape of the valve housing64so as to cover the tubular portion68and the flange66. The first conductive layer76, which is made up from a plating layer, for example, is formed in the center in the thickness along a diametrical direction of the insulating body74, and the first conductive layer76is formed in a cylindrical shape along the insulating body74at a substantially constant thickness. A distal end of the insulating body74is press-inserted into the interior of the sensor20and around the tubular portion68of the valve housing64.

On the other hand, on an outer circumferential side of the insulating body74, a cover member78, which is formed, for example, in a cylindrical shape from a metallic material, is mounted so as to cover the insulating body74. The cover member78is formed such that the proximal end side thereof (in the direction of the arrow A) is expanded in diameter corresponding to the shape of the valve housing64so as to cover the tubular portion68and the flange66. The retaining portion80that retains the outer circumferential surface of the proximal end side of the sensor20is formed on the distal end of the cover member78.

The second signal transmitting member72is formed, for example, from a resin material, and is constituted in a plate shape having a predetermined length along the axial direction (the direction of arrows A and B), and a second conductive layer82, which is formed from an electrically conductive material, is formed in the interior of the second signal transmitting member72. The second conductive layer82is formed, for example, from a plating layer, which extends at a substantially constant thickness from the distal end to the proximal end along the axial direction (the direction of arrows A and B) of the second signal transmitting member72.

A first connector84, which projects in a perpendicular direction to the axial direction, is formed at the distal end of the second signal transmitting member72. The first connector84is formed so as to face the proximal end of the first signal transmitting member70. In addition, the first connector84is inserted into a recess or cavity of the first signal transmitting member70. The second conductive layer82, which is exposed in the cavity, and the first conductive layer76of the first signal transmitting member70are connected electrically by solder or the like.

On the other hand, a small diameter second connector86, which is reduced in diameter with respect to the distal end side, is included on the proximal end of the second signal transmitting member72. A portion of the second conductive layer82is exposed in an annular shape on the second connector86along the outer circumferential surface thereof. In addition, by the second connector86being inserted into a connecting hole formed in the substrate58of the amplifying member56and electrically connected to the hole by solder or the like, the second signal transmitting member72is connected electrically with the amplifying member56.

Consequently, a condition is brought about in which the signal terminal22and the power source terminals54are connected electrically and mutually with the sensor20through the first and second signal transmitting members70,72.

The fuel injection valve10equipped with a cylinder internal pressure sensor according to the embodiment of the present invention is constructed basically as described above. Next, operations and advantageous effects of the fuel injection valve10will be described.

In a non-illustrated internal combustion engine during driving, by a control signal from the electronic control unit, the coil28is energized from the drive terminals38of the fuel injection valve10, so that the coil28is excited. Then, the valve element of the fuel injector18is placed in a valve open state, and high pressure fuel, which is supplied to the supply passage of the fuel supply unit16, is injected directly into the combustion chamber of the internal combustion engine through the fuel injector18. At this time, by a pressure (cylinder internal pressure) in the combustion chamber being applied, the piezoelectric element of the sensor20generates a voltage corresponding to the pressure, which is output as a detection signal.

The detection signal is output to the amplifying member56via the sensor20, the first signal transmitting member70, and the second signal transmitting member72, and after the detection signal has been amplified in the amplifying member56, the detection signal is output to the electronic control unit through the signal terminal22.

In addition, for example, in the electronic control unit, the pressure of the combustion chamber is calculated from the amplified output signal, and based on the calculated pressure, a combustion control or the like can be performed.

In the foregoing manner, according to the present embodiment, in the interior of the resin mold portion14in the fuel injection valve10, the amplifying member56is disposed between the signal terminal22that is connected to the connector, and the signal transmitting unit24that is connected to the sensor20. Thus, the detection signal detected by the sensor20is amplified by the amplifying member56, and can be output to the electronic control unit from the signal terminal22.

Therefore, even in the case that noise is generated due to vibrations or the like of the internal combustion engine, since it is possible for the detection signal to be amplified at the interior of the fuel injection valve10which is near to the sensor20and for which noise is comparatively small, a highly accurate detection signal can be obtained.

Further, since the signal terminal22is molded integrally in a state of being connected to the substrate58of the amplifying member56, and the connection location of the signal terminal22is covered by the sealing member60, the connection location can be protected.

Furthermore, the second connector86of the second signal transmitting member72is inserted into the connecting hole that is formed in the substrate58of the amplifying member56, whereby the second signal transmitting member72can easily and reliably be connected electrically to the amplifying member56. Therefore, ease of assembly between the amplifying member56and the signal transmitting unit24including the second signal transmitting member72can be enhanced.

Further still, when the resin mold portion14is formed, since the amplifying member56is molded integrally in the interior thereof, the amplifying member56can be protected, and water resistance and durability can be increased.

Still further, in the interior of the resin mold portion14, the first protrusions50, which are engaged with the first grooves34of the fixed core26, and the second protrusion52, which is engaged with the second groove40of the holder32, are included, and the amplifying member56is arranged between the first protrusions50and the second protrusion52. Therefore, even in the case that moisture penetrates into the interior of the resin mold portion14, the first and second protrusions50,52function as a sealing means, and infiltration of such moisture to the side of the amplifying member56can reliably be prevented.

The fuel injection valve equipped with the cylinder internal pressure sensor according to the present embodiment is not limited to the embodiment described above, and various additional or modified configurations may be adopted therein without departing from the scope of the present invention as set forth in the appended claims.