Intake-air control device for internal combustion engine

An intake-air control device for an internal combustion engine in which a sensor member can be positioned further accurately is provided. A throttle position sensor includes magnetic field generating means and a magnetic field detecting assembly. The magnetic field detecting assembly includes a plurality of terminal leads, a resin holder secured on the plurality of terminal leads, a sensor member generating a sensor output, and a resin mold body including the plurality of terminal leads, the holder, and the sensor member insert-molded. The resin holder includes a supporting surface which is located on a plane intersecting substantially perpendicularly to an axial line of a throttle shaft, and the sensor member includes a resin mold coat having first and second main surfaces opposing substantially in parallel to each other. The sensor member is held in the resin mold body with the first main surface of the resin mold coat in contact with the supporting surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an intake-air control device for an internal combustion engine.

2. Description of the Related Art

The intake-air control device for an internal combustion engine includes a throttle valve and a throttle position sensor. The throttle position sensor serves to detect the rotational position of the throttle valve, and recently, a non-contact throttle position sensor is integrated. The non-contact throttle position sensor is effective for improving durability and enhancing detection accuracy.

The non-contact throttle position sensor includes magnetic field generating means and a magnetic field detecting assembly. The magnetic field generating means rotates together with the throttle valve, and generates a detecting magnetic field in which the direction of magnetic field varies according to the rotation of the throttle valve. The magnetic field detecting assembly is fixed corresponding to the magnetic field generating means. The magnetic field detecting assembly includes a sensor member arranged in the detecting magnetic field, and the sensor member generates a detection output corresponding to the rotation in the direction of the magnetic field in the detecting magnetic field.

An intake-air control device for an internal combustion engine in which the non-contact throttle position sensor is integrated is disclosed in JP-A-2004-332635 as the related art. The throttle position sensor shown in the related art employs a magnetoresistive element (MR element) in the sensor member, and the sensor member is arranged inside a cylindrical holder and fixed therein by filling potting resin therein. The cylindrical holder is fixed on a printed board, and a detection output of the sensor member is supplied to a plurality of wirings on the printed board via a signal processing IC, whereby the plurality of wirings on the printed board are connected to a plurality of terminal leads introduced toward the outside.

In the throttle position sensor disclosed in the related art, the sensor member needs to be fixed in the cylindrical holder accurately in a predetermined direction. However, since the sensor member is fixed in the interior of the cylindrical holder with the potting resin, and there is no guiding member that guides the sensor member to the predetermined direction in this cylindrical holder, the direction of the sensor member may be varied and hence error may be generated in the detection output. Since the printed board is arranged between the cylindrical holder and the terminal leads, the number of components is increased, and a step of joining the signal processing IC and the wirings on the printed board and a step of joining the wirings on the printed board and the terminal leads are required in an assembly process.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an improved intake-air control device for an internal combustion engine in which error in a detection output is reduced, the number of components is reduced, and the number of steps of joining in an assembly process is reduced.

An intake-air control device for an internal combustion engine according to the invention is an intake-air control device for an internal combustion engine including a throttle valve and a throttle position sensor. The throttle valve controls the amount of intake-air into the internal combustion engine by being rotated about a throttle shaft arranged in an air-intake pipe of the internal combustion engine. The throttle position sensor detects the rotational position of the throttle valve, the throttle position sensor includes magnetic field generating means that rotates together with the throttle valve and generates a detecting magnetic field in which the direction of magnetic field varies according to the rotation thereof and a magnetic field detecting assembly arranged so as to oppose to the magnetic field generating means. The magnetic field detecting assembly of the throttle position sensor includes a plurality of terminal leads, a resin holder secured on the plurality of terminal leads, a sensor member arranged in the detecting magnetic field and generates a sensor output according to the direction of the magnetic field, and a resin mold body including the plurality of terminal leads, the resin holder and the sensor member are insert-molded. The resin holder has a supporting surface positioned on a plane intersecting substantially orthogonally to an axial line of the throttle shaft. The sensor member includes a resin mold coat having first and second main surfaces opposing substantially in parallel with each other. The sensor member is held in the resin mold body with the first main surface of the resin mold coat being in contact with the supporting surface of the resin holder.

In the intake-air control device for an internal combustion engine according to the invention, the resin holder includes the supporting surface positioned on the plane intersecting substantially orthogonally to the axial line of the throttle shaft and the sensor member includes the resin mold coat having the first and second main surfaces opposing substantially in parallel with each other and the sensor member is held in the resin mold body with the first main surface of the resin mold coat being in contact with the supporting surface. Therefore, displacement of the sensor member can be reduced, and hence the error in the detection output can be reduced. Since the resin holder is secured on the plurality of terminal leads, it is not necessary to use the printed board separately from the plurality of the terminal leads, and hence the number of components can be reduced, and the number of steps of joining can also be reduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, some embodiments of the present invention will be described.

First Embodiment

FIG. 1is a front view showing a first embodiment of an intake-air control device for an internal combustion engine according to the invention;FIG. 2is a vertical cross-sectional view showing a state in which part ofFIG. 1is left uncut;FIG. 3is a side view ofFIG. 1;FIG. 4is a front view of a principal portion of a throttle position sensor in the first embodiment;FIG. 5is a cross-sectional view ofFIG. 4;FIG. 6is an exploded perspective view in an assembling step of a magnetic field detecting assembly of the throttle position sensor according to the first embodiment;FIG. 7is a perspective view of a stage in which assembly of the magnetic field detecting assembly of the throttle position sensor in the first embodiment is ended;FIG. 8is a perspective view of a stage in which resin mold of the magnetic field detecting assembly of the throttle position sensor in the first embodiment is ended;FIG. 9is a perspective view showing a state in which the magnetic field detecting assembly of the throttle position sensor in the first embodiment is completed;FIG. 10is a side view showing a resin mold body of the magnetic field detecting assembly of the throttle position sensor in the first embodiment;FIG. 11is a cross-sectional view taken along the line A-A inFIG. 10;FIG. 12is a cross-sectional view taken along the line B-B inFIG. 10; andFIG. 13is a cross-sectional view taken along the line C-C inFIG. 11.

Referring now toFIG. 1,FIG. 2andFIG. 3, the general structure of the intake-air control device for an internal combustion engine according to the first embodiment will be described. The intake-air control device for an internal combustion engine according to the first embodiment includes a case10, and the case10includes a case body11and a cover15. The case10includes a throttle valve assembly20, a drive motor30, a connecting mechanism40, and magnetic field generating means51of a throttle position sensor50integrated therein.

InFIG. 1andFIG. 2, the case body11is formed by die-casting aluminum, for example. The case body11includes the throttle valve assembly20and the magnetic field generating means51of the throttle position sensor50built in an upper part thereof, the drive motor30built in a lower part thereof, and the connecting mechanism40in an intermediate part thereof respectively. The case body11is opened only on a left side end, and the left side end of the case body11is covered by the cover15. The cover15is formed by resin mold, and a magnetic field detecting assembly60of the throttle position sensor50is insert-molded in the cover15.

The throttle valve assembly20includes an air-intake body21, a throttle shaft23, first and second bearings24,25, a throttle valve26, a return coil spring28, and a throttle gear29. The air-intake body21is formed in the case body11, and defines an air-intake passage22for the internal combustion engine. The air-intake passage22has a circular cross-section, and extends perpendicularly with respect to the plane of the drawings ofFIG. 1andFIG. 2.

The throttle shaft23is arranged so that the axis thereof intersects substantially orthogonally to the air-intake passage22. The throttle shaft23is supported by the first and second bearings24,25so as to be rotatable about the axis thereof. The first bearing24is arranged on a right side end of the throttle shaft23. The first bearing24is composed of a ball bearing. The second bearing25is a metal bearing, and is arranged on a left side end of the throttle shaft23.

The throttle valve26is formed of a disk plate having substantially the same size as the air-intake passage22. The throttle valve26is arranged so as to extend across the air-intake passage22. The throttle valve26is secured to the throttle shaft23by a screw27, and rotates with the throttle shaft23. The valve opening of the throttle valve26varies with the rotational position of the throttle valve26and the amount of intake-air into the internal combustion engine is controlled.

The return coil spring28gives a spring force which is applied against the rotation of the throttle shaft23. The throttle gear29is mounted to the left end of the throttle shaft23so as to rotate with the throttle shaft23. The return coil spring28is provided between the throttle gear29and the air-intake body21. Both ends of the return coil spring28are fixed to the throttle gear29and the air-intake body21.

The drive motor30is fixed to the lower part of the case body11so that a motor shaft31thereof extends in parallel with the throttle shaft23. The drive motor30drives the throttle shaft23when it is energized, and increases the valve opening of the throttle valve26against the return coil spring28. When the energization of the drive motor30is discontinued, the throttle valve26is returned to a position of the failsafe opening by the return coil spring28. The motor shaft31of the drive motor30is provided with a motor gear32.

The connecting mechanism40is arranged between the drive motor30and the throttle shaft23, and transmits a drive force of the drive motor30to the throttle shaft23. The connecting mechanism40includes an intermediate shaft41, a first intermediate gear42and a second intermediate gear43. The intermediate shaft41is arranged in parallel with the throttle shaft23and the motor shaft31. The first intermediate gear42is engaged with the motor gear32. The first intermediate gear42has a diameter larger than the motor gear32and is decelerated by the motor gear32.

The second intermediate gear43is formed integrally with the first intermediate gear42, and rotates with the first intermediate gear42. The second intermediate gear43is engaged with the throttle gear29. The second intermediate gear43has a diameter smaller than the throttle gear29, and decelerates the throttle gear29. The drive force of the drive motor30is transmitted to the throttle shaft23via the motor gear32, the first and second intermediate gears42,43, and the throttle gear29. The throttle gear29, the motor gear32, the first and second intermediate gears42,43are formed, for example, of the resin material.

A throttle position sensor50includes the magnetic field generating means51arranged in the case body11and the magnetic field detecting assembly60insert-molded in the cover15, and is arranged so as to be laid across the case body11and the cover15. The magnetic field generating means51is arranged in an inner periphery of the throttle gear29of the throttle valve assembly20, and rotates with the throttle gear29. The magnetic field detecting assembly60is insert-molded in the cover15, and is fixed to the cover15.

The magnetic field generating means51of the throttle position sensor50includes a ring-shaped yoke52and a pair of magnets56,57as shown inFIG. 4andFIG. 5. The ring-shaped yoke52is concentric with the throttle shaft23and fitted in the inner periphery of the throttle gear29and rotates with the throttle gear29. The yoke52includes a pair of magnetic poles53,54opposing to each other on the inner periphery thereof and generates a detecting magnetic field55between the magnetic poles53,54.

The pair of magnets56,57are permanent magnets and are integrated in the yoke52. The magnets56,57are arranged in polarities such that a N-pole is provided to the magnetic pole53, and a S-pole is provided to the magnetic pole54and, consequently, a detecting magnetic flux Φ in the direction from the magnetic pole53toward the magnetic pole54is generated in the detecting magnetic field55. The direction of the detecting magnetic flux Φ is oriented in the direction orthogonal to the axial line of the throttle shaft23, and the direction of the detecting magnetic flux Φ rotates about the axial line according to the rotation of the throttle shaft23.

The magnetic field detecting assembly60is shown inFIG. 6toFIG. 13. The magnetic field detecting assembly60includes a sensor member62and an auxiliary sensor member72as principal parts. The sensor members62,72include a magnetoresistive element (MR element) and a sensor IC molded respectively in resin mold coats63,73. The MR element and the sensor IC molded in the resin mold coats63,73output a sensor output SD of the sensor members62,72, and the sensor output SD has a magnitude proportional to the direction of the detecting magnetic flux Φ, that is, the rotational position of the throttle shaft23and the throttle valve26.

The sensor member62and the auxiliary sensor member72are configured into the same structure, and are arranged so as to generate the same sensor output SD. The sensor member62and the auxiliary sensor member72are arranged in duplicate as the failsafe specification, that is, so that when one of the sensor members is failed and hence abnormality occurs in the sensor output SD thereof, the sensor output SD of the other sensor member can be used.

In order to improve the accuracy of the sensor outputs SD of the sensor member62and the auxiliary sensor member72, it is necessary to arrange the sensor member62and the auxiliary sensor member72accurately at predetermined positions. In the first embodiment, the magnetic field detecting assembly60is configured so that the sensor member62and the auxiliary sensor member72can be arranged accurately at predetermined positions.

Referring now toFIG. 6toFIG. 13, the magnetic field detecting assembly60will be described in detail. The magnetic field detecting assembly60includes a sensor circuit structure61, an auxiliary sensor circuit structure71, a terminal lead structure80, a resin holder85, and a resin mold body90, and is insert-molded in the cover15as shown inFIG. 6andFIG. 7. The magnetic field detecting assembly60is assembled in reference to a reference plane SS which intersects perpendicularly to the axial line of the throttle shaft23. The reference plane SS is defined by an upper surface of the terminal lead structure80as shown inFIG. 6toFIG. 9. InFIG. 6toFIG. 9, description will be made assuming directions X and Y which intersect at orthogonally to each other on the reference plane SS.

The sensor circuit structures61,71are configured into the same structure as the failsafe specification. The sensor circuit structure61includes the sensor member62, a first lead structure65, a signal processing IC66, and a second lead structure68. In the same manner, the auxiliary sensor circuit structure71includes the auxiliary sensor member72, a first lead structure75, an auxiliary signal processing IC76, and a second lead structure78.

The sensor members62,72include, as shown inFIG. 6andFIG. 7, resin mold coats63,73respectively, and the first lead structures65,75are introduced from the resin mold coats63,73, respectively. The MR element and the sensor IC are molded in the resin mold coats63,73respectively, and the MR element and the sensor IC are electrically connected to the first lead structures65,75in a predetermined relation.

The first lead structures65,75include a plurality of leads extending substantially in parallel to each other. All the leads extend in the X-direction. The plurality of leads includes one power source terminal lead, one GND terminal lead, and one output lead. The output lead generates the sensor output SD.

The resin mold coats63,73have flat rectangular parallelepiped respectively, and are formed, for example, of epoxy resin. The resin mold coats63,73are arranged so as to oppose to each other in the direction perpendicular to the reference plane SS. The resin mold coat63includes a lower first main surface63aand an upper second main surface63bwhich oppose in parallel to each other. In the same manner, the resin mold coat73includes a lower first main surface73aand an upper second main surface73bwhich oppose in parallel to each other. The first main surfaces63a,73aand the second main surfaces63b,73bare formed in parallel with the reference plane SS, and is located on a plane which intersects substantially orthogonally to the axial line of the throttle shaft23. The first main surface63aof the resin mold coat63opposes the second main surface73bof the resin mold coat73.

The resin mold coat63includes a pair of projections64a,64bprojecting from a pair of side surfaces opposing in the Y-direction, and in the same manner, the resin mold coat73includes a pair of projections74a,74bprojecting from the pair of side surfaces opposing in the Y-direction. The pair of projections64a,64bproject in the directions opposite from each other in parallel to the first and second main surfaces63a,63bof the resin mold coat63. The pair of projections74a,74bproject in the directions opposite from each other in parallel to the first and second main surfaces73a,73bof the resin mold coat73.

The widths of the resin mold coats63,73in the Y-direction are the same. The projections64a,74aare formed at positions overlapping with each other with the intermediary of a distance in the direction perpendicular to the reference plane SS. In the same manner, the projections64b,74bare formed at positions overlapping with each other with the intermediary of a distance in the direction perpendicular to the reference plane SS. The length of projection in the Y-direction and the length in the X-direction of the pair of projections64a,64band the pair of projections74a,74bare the same.

The first lead structures65,75are, as shown inFIG. 6andFIG. 7, bent at midsections thereof downwardly at a right angle toward a terminal lead structure80, and connect the resin mold coats63,73and the signal processing ICs66,76. The signal processing ICs66,76are semiconductor integrated circuits for processing the signals of the sensor outputs SD from the sensor members62,72, respectively, and include resin mold coats67,77respectively. The resin mold coats67,77are formed, for example, of epoxy resin.

The second lead structures68,78are introduced downward from the resin mold coats67,77toward the terminal lead structure80. The second lead structures68,78each include three leads68a-68c,78a-78cwhich extend substantially in parallel to each other. The leads68a,78aconstitute the source terminal, and are electrically connected to the leads which constitute the power source terminals of the first lead structures65,75. The leads68b,78bconstitute the GND terminals, and are electrically connected to the leads which constitute the GND terminals of the first lead structures65,75. The lead68coutputs an output A and the lead78coutputs an output B. The outputs A and B are outputs from the sensor circuit structures61,71.

The terminal lead structure80includes, as shown in FIG.6toFIG. 9, four terminal leads80a-80daligned in parallel to each other. The terminal lead structure80constitutes an outer terminal of the magnetic field detecting assembly60. The terminal lead80ais a power source terminal lead, and for example, a direct current power source voltage of 5 Volts to the power source terminal lead80a. The leads68a,78aof the second lead structures68,78are connected to the power source terminal lead80a, for example, by electric welding. The direct current power source voltage of 5 Volts supplied to the power source terminal lead80ais supplied to leads68a,78aof the second lead structures68,78. The terminal lead80bis the GND terminal lead, and is connected to a common potential point. The leads68b,78bof the second lead structures68,78are connected to the terminal lead80b, for example, by electric welding. A GND potential common to the leads68b,78bof the second lead structures68,78is provided by the terminal lead80b.

As shown inFIG. 6andFIG. 7, the terminal lead structure80includes a terminal leading section81aand a mounting section81bfor the sensor circuit structures61,71, and the terminal leads80a-80dextend across the terminal leading section81aand the mounting section81b. The terminal leads80a-80dextend substantially in the X-direction in the terminal leading section81aand the mounting section81b, and are connected with respect to each other by an inclined section81cbetween the terminal leading section81aand the mounting section81b. Three mounting holes82a-82cfor mounting the resin holder85are formed on the terminal leads80a,80bpositioned in the mounting section81b. The mounting holes82a,82bare formed on the terminal lead80a, and the mounting hole82cis formed on the terminal lead80b.

The terminal leads80c,80dof the terminal lead structure80are output terminal leads and arranged on both outsides so as to sandwich the terminal leads80a,80b. The lead68cof the second lead structure68is connected to the terminal lead80c, for example, by electric welding, and the output A of the sensor circuit structure61is supplied to the terminal lead80c. The lead78cof the second lead structure78is connected to the terminal lead80dfor example, by electric welding and the output B of the auxiliary sensor circuit structure71is supplied to the terminal lead80d.

The resin holder85is formed, for example, of nylon resin into the shape of a square pole as shown inFIG. 6andFIG. 7. The resin holder85integrally includes a lower base portion86, an upper supporting portion87, and an intermediate supporting portion89between them. Three positioning projections86aare integrally formed on a lower surface of the lower base portion86. The holder85is mounted to the mounting section81bof the terminal lead structure80by inserting the positioning projections86ainto the mounting holes82a-82cand is caulked by heat.

The upper supporting portion87of the holder85is formed with a shoulder88. The shoulder88is formed with a supporting surface88aand an auxiliary supporting surface88bextending in parallel to each other. The supporting surface88ais formed on an upper side of the shoulder88, and the auxiliary supporting surface88bis formed on a lower side thereof. The supporting surfaces88a,88bextend in parallel with the reference plane SS, and are positioned on a plane intersecting substantially orthogonally to the axial line of the throttle shaft23. The intermediate supporting portion89is formed into the shape of a square column, and includes a pair of second supporting surfaces89a,89bopposing to each other in the X-direction. The second supporting surfaces89a,89bextend perpendicularly to the reference plane SS and positioned on a plane substantially in parallel with the axial line of the throttle shaft23.

The resin mold coat63of the sensor circuit structure61is supported by the holder85in a state of being in contact with the supporting surface88a. The resin mold coat73of the auxiliary sensor circuit structure71is supported by the holder85in a state of being in contact with the auxiliary supporting surface88b. More specifically, the resin mold coat63is supported by the holder85in a state in which the first main surface63ais in surface contact with the supporting surface88a. The resin mold coat73is supported by the holder85in a state in which the first main surface73ais in surface contact with the auxiliary supporting surface88b. The resin mold coats63,73come into surface contact with the supporting surface88aand the auxiliary supporting surface88brespectively and oppose to each other perpendicularly to the reference plane SS.

The resin mold coats67,77of the sensor circuit structures61,71are supported by the holder85in a state of being in contact with the intermediate supporting portion89of the holder85. More specifically, the resin mold coat67is supported by the holder in a state of being in surface contact with one second supporting surface89aof the intermediate supporting portion89and the resin mold coat77is supported by the holder in a state of being in surface contact with that other second supporting surface89bof the intermediate supporting portion89.

A resin mold body90is formed of resin material having a coefficient of linear expansion approximate to that of the resin mold coats63,67,73,77of the sensor circuit structures61,71, for example, the epoxy resin which is the same material as the resin mold coats63,67,73,77. The resin mold body90includes a cylindrical portion91and a lower plate portion92as shown inFIG. 8andFIG. 9. The lower plate portion92is formed entirely on the surface of the mounting section81bof the terminal lead structure80. The lower plate portion92is formed across an upper surface and a lower surface of the mounting section81bof the terminal lead structure80, and the terminal lead structure80is insert-molded on the lower plate portion92. The lower plate portion92connects the respective terminal leads80a-80dof the mounting section81bto each other.

The cylindrical portion91is formed on the lower plate portion92. The cylindrical portion91is formed so as to integrally connect the sensor circuit structures61,71and the resin holder85. The sensor circuit structures61,71and the resin holder85are insert-molded in the cylindrical portion91. In particular, the sensor circuit structures61,71are insert-molded in the cylindrical portion91in a state in which the first main surfaces63a,73aof the resin mold coats63,73are in surface contact with the supporting surface88aand the auxiliary supporting surface88b, and the resin mold coats67,77are in surface contact with the second supporting surfaces89a,89b, respectively.

Subsequently, the manufacturing process of the magnet field detecting assembly60will be described referring again toFIG. 6toFIG. 13. InFIG. 6, the sensor circuit structures61,71, the terminal lead structure80, and the resin holder85in a state before assembly are shown. It should be understood that the terminal lead structure80includes an outer frame83and a plurality of connecting strips84integrally in the state before assembly shown inFIG. 6. The outer frame83is formed so as to surround the respective terminal leads80a-80dof the terminal lead structure80, and the plurality of connecting strips84connect the respective terminal leads80a-80dwith respect each other, and between the terminal leads80c,80dand the outer frame83. The terminal lead structure80holds the respective terminal leads80a-80dintegrally to each other by the outer frame83and the plurality of connecting strips84.

In the state shown inFIG. 6, the resin holder85is firstly positioned and mounted to the mounting section81bof the terminal lead structure80. Mounting of the holder85is performed by inserting the positioning projections86ainto the mounting holes82a-82c, and caulking by heat.

After having mounted the resin holder85to the terminal lead structure80, the sensor circuit structures61,71are secured to the terminal lead structure80. The sensor circuit structure61is secured to the terminal lead structure80by electrically welding the three leads68a-68cof the second lead structure68to the terminal leads80a-80crespectively in the mounting section81bof the terminal lead structure80in a state in which the first main surface63aof the resin mold coat63is in surface contact with the supporting surface88aof the holder85and the resin mold coat67is in surface contact with the second supporting surface89arespectively. Likewise, the sensor circuit structure71is secured to the terminal lead structure80by electrically welding the three leads78a-78cof the second lead structure78to the terminal leads80a,80b,80drespectively in the mounting section81bof the terminal lead structure80in a state in which the first main surface73aof the resin mold coat73is in surface contact with the auxiliary supporting surface88bof the holder85and the resin mold coat77is in surface contact with the second supporting surface89brespectively.

FIG. 7shows a state in which assembly of the sensor circuit structures61,71, the terminal lead structure80, and the holder85is completed. In the completely assembled state shown inFIG. 7, the resin mold body90is molded as shown inFIG. 8. InFIG. 8, a stage in which the molding process of forming the resin mold body90is ended is shown. In the state in which the resin mold body90is formed, the outer frame83and the plurality of connecting strips84of the terminal lead structure80are removed. Since the resin mold body90connects the terminal leads80a-80d, the terminal leads80a-80ddo not come apart from each other. The terminal leads80a-80dare electrically separated and become independent by removal of the plurality of connecting strips84. The completed magnetic field detecting assembly60is shown inFIG. 9.

Referring toFIG. 10toFIG. 12, the internal structure of the cylindrical portion91of the resin mold body90will be described further in detail.FIG. 10shows the resin mold body90. InFIG. 10, a rectangular exposure hole91bis formed on an end surface91awhich is located on top of the cylindrical portion91. The exposure hole91bexposes a principal portion of the second main surface63bof the resin mold coat63in the sensor circuit structure61from the resin mold body90. The principal portion of the second main surface63bof the resin mold coat63exposed through the exposure hole91bcomes into surface contact with the inner surface of a mold die95in the molding process for forming the resin mold body90so that the position of the resin mold coat63is constrained and prevented from moving between the mold die95and the supporting surface88a. The positional constraint is effective for preventing the resin mold coat63from being displaced with respect to the direction of the detecting magnetic flux Φ.

InFIG. 10, the end surface91apositioned on top of the cylindrical portion91is formed with a circular exposure hole91c. The exposure hole91cexposes part of the second main surface73bof the resin mold coat73in the auxiliary sensor circuit structure71from the resin mold body90as shown inFIG. 11andFIG. 12. The second main surface73bof the resin mold coat73exposed from the exposure hole91ccomes into surface contact with a pin formed on the inner surface of the mold die95, and constrains the position of the resin mold coat73so as not to move between the pin on the mold die95and the auxiliary supporting surface88bin the molding process for molding the resin mold body90. The positional constraint is effective for preventing the resin mold coat73from being displaced with respect to the direction of the detecting magnetic flux Φ.

A resin part90aof the resin mold body90is injected into a portion between the resin mold coats63and73of the sensor circuit structures61,71as shown inFIG. 11andFIG. 12. The resin part90ais filled between the resin mold coats63and73when molding the resin mold body90for pressing the principal portion of the second main surface63bof the resin mold coat63against the inner surface of the mold die95, and pressing the first main surface73aof the resin mold coat73against the auxiliary supporting surface88b. Pressing by the resin part90ais effective for constraining the positions of the resin mold coats63,73and is effective for preventing the resin mold coats63,73from being displaced with respect to the direction of the detecting magnetic flux Φ.

The mold die95includes a pair of opposing position constraining grooves95a,95bat positions opposing to the pairs of projections64a,64b,74a,74bof the resin mold coats63,73as specifically shown inFIG. 13. The pair of position constraining grooves95a,95bextend toward the terminal lead structure80perpendicularly to the reference plane SS. The projections64a,74aare fitted to the position constraining groove95a, and the projections64b,74bare fitted to the position constraining groove95bboth tightly. The positional constraint of the projections64a,64b,74a,74bby the position constraining grooves95a,95bis effective for preventing the resin mold coats63,73from being displaced with respect to the direction of the detecting magnetic flux Φ. As shown inFIG. 8,FIG. 9, andFIG. 10, projecting ridges92a,92bformed by the pair of position constraining grooves95a,95bon an upper peripheral surface of the cylindrical portion91of the resin mold body90.

Terminal leads30a,30bof the drive motor30is insert-molded with the terminal lead structure80of the magnetic field detecting assembly60in the cover15as shown inFIG. 1. The terminal leads30a,30bare aligned with the terminal leads80a-80dand arranged in the lower portion thereof. The terminal leads30a,30bare connected to the drive motor30via contacts, not shown, and supply drive voltage to the drive motor30as needed.

As described above, in the intake-air control device for an internal combustion engine according to the first embodiment of the present invention, the magnetic field detecting assembly60of the throttle position sensor50includes the plurality of terminal leads80a-80d, the resin holder85secured on the plurality of terminal leads80a-80d, at least one sensor member62that is arranged in the detecting magnetic field55and generates the sensor output SD according to the direction of the magnetic field, and the resin mold body90in which the plurality of terminal leads80a-80d, the holder85, and the sensor member62are insert-molded; the resin holder85includes the supporting surface88apositioned on the plane which intersects substantially perpendicularly to the axial line of the throttle shaft23; the sensor member62includes the resin mold coat63having the opposing the first and second main surfaces63a,63b; and the first main surface63ais held in the resin mold body90in contact with the supporting surface88aof the resin holder85. In the magnetic field detecting assembly60, since the first main surface63aof the sensor member62is positioned in contact with the supporting surface88aof the resin holder85, the sensor member62is prevented from being displaced with respect to the magnetic field generating means51, and hence further accurate detection of the throttle position is achieved.

According to the magnetic field detecting assembly60in the first embodiment, the sensor member62includes the pair of projections64a,64bprojecting in the direction in parallel to the first and second main surfaces63a,63bfrom the resin mold coat63, and the pair of projections project from the resin mold coat63in the directions opposite from each other. Therefore, by positioning the pair of projections64a,64b, for example, in the mold die95, the sensor member62can be positioned more accurately.

According to the magnetic field detecting assembly60in the first embodiment, since at least part of the second main surface63bof the sensor member62is exposed from the resin mold body90, by positioning the second main surface63bof the sensor member62in abutment, for example, with the mold die95, the sensor member62can be positioned more accurately.

The magnetic field detecting assembly60in the first embodiment further includes a signal processing IC66connected to the sensor member62, and the resin holder85includes the second supporting surface89apositioned in the plane which extends substantially in parallel to the axial line of the throttle shaft23, and then the signal processing IC66is held in the resin mold body90in contact with the second supporting surface89aof the resin holder85, the signal processing IC66can also be positioned further accurately.

The magnetic field detecting assembly60in the first embodiment further includes the auxiliary sensor member72arranged in the detecting magnetic field55; the resin holder85includes the auxiliary supporting surface88bwhich extends substantially in parallel to the supporting surface88a; and the auxiliary sensor member72includes the resin mold coat73having the opposing first and second main surfaces73a,73band held in the resin mold body90with the first main surface73ain contact with the auxiliary supporting surface88b. Therefore, the positional displacement of the auxiliary sensor member72with respect to the magnetic field generating means51is prevented, and hence further accurate detection of the throttle position is enabled.

According to the magnetic field detecting assembly60in the first embodiment, the resin mold coat73of the auxiliary sensor member72is arranged so as to oppose to the resin mold coat63of the sensor member62, and the resin mold body90is filled in the space between the resin mold coat63of the sensor member62and the resin mold coat73of the auxiliary sensor member72. Therefore, further accurate positioning of both of the sensor members62,72is achieved.

According to the magnetic field detecting assembly60in the first embodiment, since the resin mold body90includes the exposure hole91bfor exposing at least part of the second main surface63bof the sensor member62, and the resin mold body90includes the exposure hole91cfor exposing part of the second main surface73bof the resin mold coat73of the auxiliary sensor member72, positioning the second main surface63bof the sensor member62in abutment, for example, with the mold die95, and positioning the second main surface73bof the auxiliary sensor member72in abutment with the pin of the mold die95, further accurate positioning of the sensor member62and the auxiliary sensor member72is achieved.

According to the magnetic field detecting assembly60in the first embodiment, since the resin mold coat63has the coefficient of linear expansion which is approximate to that of the resin mold body90, a thermal stress applied between the resin mold coat63and the resin mold body90according to the difference of the coefficients of the linear expansion thereof on the basis of a thermal change during manufacturing or operation can be reduced, and positional displacement of the sensor member62caused by the thermal stress can be prevented.

Since the magnetic field detecting assembly60in the first embodiment includes positioning means82a-82c,86afor positioning at least one of the terminal leads of the plurality of terminal leads80a,80band the resin holder85, the resin holder85can be positioned on the terminal lead, and then the sensor member62can be positioned by the resin holder85.

According to the magnetic field detecting assembly60in the first embodiment, the positioning means includes the positioning projection86aformed on the resin holder85, and the positioning projection86ais caulked to at least one terminal lead by heat. Therefore, positioning of the resin holder85can be achieved easily.

Second Embodiment

Referring now toFIG. 14toFIG. 19, a second embodiment of the intake-air control device for an internal combustion engine according to the invention will be described.FIG. 14is a perspective view showing a state before assembly of a sensor circuit structure of a magnetic field detecting assembly and a resin holder according to the second embodiment;FIG. 15is a perspective view showing a state before assembly of the sensor circuit structure and the resin holder to a terminal lead structure according to the second embodiment;FIG. 16is a perspective view showing a state in which assembly of the magnetic field detecting assembly of a throttle position sensor is completed according to the second embodiment;FIG. 17is a front view showing a state in which the magnetic field detecting assembly shown inFIG. 16is completed;FIG. 18is a cross-sectional view taken along the line E-E inFIG. 17; andFIG. 19is a cross-sectional view taken along the line D-D inFIG. 17. All the drawings fromFIG. 14toFIG. 19show a stage before molding the resin mold body90.

According to the throttle position sensor50in the second embodiment, a magnetic field detecting assembly60A in which the magnetic field detecting assembly60in the first embodiment is deformed is used, and in this magnetic field detecting assembly60A, a resin holder85A in which the resin holder85in the first embodiment is deformed, and a terminal lead structure80A in which the terminal lead structure80is deformed are used. Other structures are the same as in the first embodiment.

The resin holder85A used in the magnetic field detecting assembly60A in the second embodiment includes holding portions185,186for holding the respective signal processing ICs66,76of the sensor circuit structures61,71, and also a pair of snap strips187a,187bfor snap-fitting the holder85A to the terminal lead structure80A.

The resin holder85A is formed, for example, of nylon resin into the shape of a square pole, and integrally includes the lower base portion86, the upper supporting portion87, and the intermediate supporting portion89as in the case of the resin holder85in the first embodiment. The holding portions185,186are integrally formed with the intermediate supporting portion89on the supporting surfaces89a,89bof the intermediate supporting portion89. The holding portions185,186include pairs of opposing holding arms185a,185band186a,186brespectively, and the respective holding arms185a,185band186a,186bare integrally formed with the intermediate supporting portion89so as to be capable of resilient deformation.

As shown inFIGS. 15,16, and19, the pair of holding arms185a,185bof the holding portion185hold the signal processing IC66of the sensor circuit structure61so as to embrace the same. The holding arms186a,186bof the holding portion186hold the auxiliary signal processing IC76of the sensor circuit structure71so as to embrace the same.

A pair of snap strips187a,187bare formed on the lower base portion86of the resin holder85A. The pair of snap strips187a,187bare formed integrally with the lower base portion86so as to project in the directions opposite from each other. The pair of snap strips187a,187bare formed on the lower base portion86so as to be capable of resilient deformation, and, as shown inFIG. 16andFIG. 18, snap-fitting the resin holder85A to a mounting section81bof the terminal lead structure80A while being resiliently deformed. The terminal lead80bis formed with one positioning hole82cand the holder85A is formed with one positioning projection86a, so that the holder85A is positioned on the terminal lead structure80A by fitting the positioning projection86ainto the positioning hole82c.

According to the terminal lead structure80A in the second embodiment, arrangement of the terminal leads80a-80dis changed from that of the terminal lead structure80in the first embodiment. The terminal leads80c,80dare arranged so as to align on one side of the terminal lead80awhich receives the supply of power source voltage and the terminal lead80bwhich has the GND potential. On the mounting section81bof the terminal lead structure80A, the output terminal lead68cof the sensor circuit structure61is connected to the terminal lead80c, and the output terminal lead78cof the sensor circuit structure71is connected to the terminal lead80dby, for example, electrically welding, so that the output A and the output B of the sensor circuit structures61,71are supplied to the terminal leads80c,80d.

In the terminal lead structure80A, the inclined section81cbetween the terminal leading section81aand the mounting section81bis eliminated. Although the connecting strips84are not shown in the drawing, the frame portion83surrounds the terminal leads80a-80das in the case of the terminal lead structure80in the first embodiment, and is to be removed after the resin mold body90is molded.

In the second embodiment, the signal processing ICs66,76can easily be held by the respective holding arms185a,185b,186a,186bof the holding portions185,186, and the resin holder85A can easily be secured to the terminal lead structure80A by the snap strips187a,187b. In the second embodiment in which the snap strips187a,187bare used, the positioning projection86amust simply be fitted into the positioning hole68c, and caulking by heat is not necessary.

The intake-air control device for an internal combustion engine according to the invention can be used, for example, as an intake-air control device for an internal combustion engine which is to be mounted to an automotive vehicle.