Throttle valve control device for an internal combustion engine

Information

  • Patent Grant
  • 6739315
  • Patent Number
    6,739,315
  • Date Filed
    Wednesday, December 5, 2001
    23 years ago
  • Date Issued
    Tuesday, May 25, 2004
    20 years ago
Abstract
A throttle valve control device for an internal combustion engine is obtained which has an improved sector gear 20 capable of suppressing inclinations of tooth surfaces 22a of its resin teeth 22 due to shrinkage of a resin upon hardening thereof at the time of insert molding. The throttle valve control device includes a motor 2 and the sector gear 20 operatively connected with the motor 2 for driving a shaft 8, on which a throttle valve 20 is fixedly mounted, by means of power transmitted thereto from said motor. The sector gear 20 has a sector-shaped rigid core member 21, and a resin molded portion 23 with the teeth 22 formed on the core member 21 by insert molding. The core member 21 has a support portion 24 with a curved surface 24a formed to extend along bottoms 22b of the teeth 22 and project in an axial direction as well.
Description




This application is based on Application No. 2001-162100, filed in Japan on May 30, 2001, the contents of which are hereby incorporated by reference.




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a throttle valve control device for an internal combustion engine in which the rotation of a motor corresponding to an amount of operation of an accelerator pedal is transmitted through a gear mechanism to a shaft of a throttle valve, which adjusts the amount of intake air sucked into the internal combustion engine.




2. Description of the Related Art





FIG. 7

is a cross sectional side view of a known throttle valve control device for an internal combustion engine. This throttle valve control device for an internal combustion engine includes a housing


1


, a motor


2


provided in the housing


1


, a small gear wheel


4


fixed to a rotating shaft


3


of the motor


2


, an intermediate gear wheel


5


in mesh with the small gear wheel


4


, a sector gear


6


in mesh with the intermediate gear wheel


5


, a shaft


7


rotatably mounted on the housing


1


across an intake passage formed therein with the sector gear


6


fixedly attached thereto at its one end, a throttle valve


8


fixedly mounted on the shaft


7


for rotation therewith, a return spring


9


for urging the throttle valve


8


in its closing direction at all times through the shaft


7


, and an opening sensor


10


fixedly attached to the shaft


7


on one side of the sector gear


6


opposite the throttle valve


8


for detecting the opening of the throttle valve


8


.





FIG. 8

is a front elevation of the sector gear


6


, and

FIG. 9

is a cross sectional view along line IX—IX of the sector gear


6


of FIG.


8


. The sector gear


6


is comprised of a generally sector-shaped core member


11


and a resin molded portion


13


with teeth


12


formed on the core member


11


by means of insert molding. The core member


11


is formed by pressing a metal sheet. The metal sheet is used for ensuring the proper strength of the sector gear


6


.





FIG. 10

is a front elevation of a sector gear


15


of another example, and

FIG. 11

is a cross sectional view along line XI—XI of the sector gear


15


of FIG.


10


. This sector gear


15


is formed on the whole by sinter molding a ferrous material.




With the known sector gear


6


as described above, the resin molded portion


13


having the teeth


12


is formed on the core member


11


by means of insert molding, but in this case, there arises a problem that a molding sink


16


as shown by a dotted line in

FIG. 12

is caused on the tooth surfaces


12




a


of the teeth


12


under the action of shrinkage occurring upon hardening of the resin, whereby the tooth surfaces or crest surfaces


12




a


are caused to incline in a diametral or radial direction from a horizontal line, as illustrated in

FIGS. 13A and 13B

.




In addition, with the sector gear


15


which on the whole is molded by sintering, inclinations of the tooth surfaces of the teeth


12


can be avoided, and hence the sector gear


15


is improved in accuracy and reliability, but gives rise to another problem that the weight of the sector gear


15


is substantially increased.




SUMMARY OF THE INVENTION




The present invention is intended to obviate the problems as referred to above, and has for its object to provide a throttle valve control device for an internal combustion engine which has a sector gear with improved teeth accuracy by preventing inclinations of the teeth surfaces.




Bearing the above object in mind, the present invention resides in a throttle valve control device for an internal combustion engine comprising a motor and a sector gear operatively connected with the motor for driving a shaft having a throttle valve fixedly mounted thereon, the sector gear including a sector-shaped core member and a resin molded portion with teeth formed on the core member by insert molding. The throttle valve control device is characterized in that the core member has a support portion with a curved surface formed to extend along bottoms of the teeth and project in an axial direction.




The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a front elevation of a sector gear used with a throttle valve control device for an internal combustion engine according to a first embodiment of the present invention.





FIG. 2

is a cross sectional view of the sector gear along line II—II of FIG.


1


.





FIG. 3

is a front elevation of the sector gear used with a throttle valve control device for an internal combustion engine according to a second embodiment of the present invention.





FIG. 4

is a cross sectional view of the sector gear along line IV—IV of FIG.


3


.





FIG. 5

is a front elevation of a sector gear used with a throttle valve control device for an internal combustion engine according to a third embodiment of the present invention.





FIG. 6

is a cross sectional view of the sector gear along line VI—VI of FIG.


5


.





FIG. 7

is a side cross sectional view of a known throttle valve control device for an internal combustion engine.





FIG. 8

is a front elevation of the sector gear of FIG.


7


.





FIG. 9

is a cross sectional view of the sector gear along line IX—IX of FIG.


8


.





FIG. 10

is a front elevation of a known sector gear of another example.





FIG. 11

is a cross sectional view of the sector gear along line XI—XI of FIG.


10


.





FIG. 12

is a front elevation of the sector gear when the sector gear of

FIG. 8

is deformed by a molding sink of a resin.





FIG. 13A

is a cross sectional view along line XIII—XIII of FIG.


12


.





FIG. 13B

is an enlarged view of a circled part A of FIG.


13


A.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Now, preferred embodiments of the present invention will be described in detail while referring to the accompanying drawings. The following description will be made by identifying the same or corresponding parts or locations with the same symbols as employed in

FIGS. 7 through 12

and

FIGS. 13A and 13B

.




Embodiment 1.





FIG. 1

is a front elevation of a sector gear


20


used with a throttle valve control device for an internal combustion engine in accordance with a first embodiment of the present invention.

FIG. 2

is a cross sectional view of the sector gear


20


along line II—II of FIG.


1


. The sector gear


20


is comprised of a sector-shaped core member


21


and a resin molded portion


23


with teeth


22


formed on or fitted over the core member


21


by insert molding. The core member


21


is formed by cutting a metal member into a T-shaped cross sectional configuration along an axial direction. The core member


21


has a support portion


24


which is formed to extend along bottoms


22




b


of the teeth


22


in a circumferential direction and project in an axial direction as well. The support portion


24


is formed along the bottoms


22




b


of the teeth


22


and has a curved surface


24




a.






In the sector gear


20


of this embodiment, the resin molded portion


23


having the teeth


22


is formed on or fitted over the core member


21


by insert molding, but in this case, the support portion


24


of the core member


21


serves to suppress a molding sink or shrinkage of the resin due to a shrinking action occurring upon hardening of the resin. As a result, inclinations of the tooth surfaces


22




a


of the teeth


22


can be suppressed. In addition, by enhancing the cutting accuracy of the support portion


24


, it is possible to more effectively prevent the tooth surfaces


22




a


of the teeth


22


from being inclined.




Embodiment 2.





FIG. 3

is a front elevation of a sector gear


30


used with a throttle valve control device for an internal combustion engine in accordance with a second embodiment of the present invention.

FIG. 4

is a cross sectional view of the sector gear


30


along line IV—IV of FIG.


3


. The sector gear


30


is comprised of a sector-shaped core member


31


and a resin molded portion


33


with teeth


32


formed on or fitted over the core member


31


by insert molding. The core member


31


is formed of a sheet metal which has a support portion


34


folded in an axial direction. The support portion


34


is formed along the bottoms


32




b


of the teeth


32


, and has a curved surface


34




a.






In this embodiment, the support portion


34


can be formed by the folding processing of the sheet metal, and hence the folding processing is simple and easy as compared with the cutting processing in the first embodiment, thus making it possible to manufacture the sector gear


30


at low costs.




Embodiment 3.





FIG. 5

is a front elevation of a sector gear


40


used with a throttle valve control device for an internal combustion engine in accordance with a third embodiment of the present invention.

FIG. 6

is a cross sectional view of the sector gear


40


along line VI—VI of FIG.


5


.




This embodiment is different from the second embodiment in that a core member


41


of the sector gear


40


is formed with a plurality of holes


42


for integrally combining the core member


41


and a resin molded portion


44


with each other, and a plurality of windows


43


are formed in the core member


41


at one side thereof opposite the teeth


32


.




In this embodiment, the core member


41


and the resin molded portion


44


are integrally formed with each other through the resin filled in the holes


42


, so it is unnecessary to cover the entire core member


41


with the resin, as in the second embodiment. Additionally, the most parts of the resin molded portion


44


are occupied by the teeth


32


, and the windows


43


are formed in the core member


41


. As a result, the weight of the sector gear


40


is reduced.




As described in the foregoing, the present invention provides the following advantages.




According to the present invention, a throttle valve control device for an internal combustion engine comprises a motor and a sector gear operatively connected with the motor for driving a shaft having a throttle valve fixedly mounted thereon, the sector gear including a sector-shaped core member and a resin molded portion with teeth formed on the core member by insert molding. The core member has a support portion with a curved surface formed to extend along bottoms of the teeth and project in an axial direction. With this arrangement, the support portion serves to prevent inclinations of tooth surfaces of the teeth due to a molding sink of the resin caused under the action of shrinkage upon hardening of the resin, thus improving the accuracy of the sector gear.




In addition, in comparison with the aforementioned known sector gear which on the whole is formed of a metal sintered material, the sector gear of the invention is light in weight and has the teeth formed of a resin, so that it is possible to suppress to an extremely limited level the collision sounds of the teeth generated when the teeth of the sector gear come into meshing engagement with the teeth of a mating gear wheel.




In another preferred form of the invention, the core member has a T-shaped cross section along an axial direction. Thus, it is possible to prevent the tooth surfaces of the teeth from being inclined due to a molding sink of the resin under the action of the support portion.




In a further preferred form of the invention, the core member comprises a metal member formed by cutting. Thus, the support portion can be easily formed.




In a yet further preferred form of the invention, the core member comprises a sheet metal which is folded to form a support portion. Thus, the support portion can be easily formed by means of folding processing.




In a still further preferred form of the invention, the core member is formed with holes for integrally combining the core member and the resin molded portion with each other, whereby the core member and the resin molded portion are strongly integrated with each other by means of a resin filled in the holes.




In a further preferred form of the invention, the core member has windows formed at its one side opposite the teeth, so the weight of the stator can be reduced.




While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.



Claims
  • 1. A throttle valve control device for an internal combustion engine, comprising a motor and a sector gear operatively connected with said motor for driving a shaft having a throttle valve fixedly mounted thereon by means of power transmitted thereto from said motor, wherein:said sector gear comprises a sector-shaped core member and a resin molded portion with teeth formed on said core member by insert molding, and said core member has a support portion with a curved surface formed to extend along bottoms of said teeth and project in an axial direction.
  • 2. The throttle valve control device for an internal combustion engine according to claim 1, wherein said core member has a T-shaped cross section along an axial direction.
  • 3. The throttle valve control device for an internal combustion engine according to claim 2, wherein said core member comprises a metal member formed by cutting.
  • 4. The throttle valve control device for an internal combustion engine according to claim 1, wherein said core member comprises a section of sheet metal which is folded to form a support portion.
  • 5. The throttle valve control device for an internal combustion engine according to claim 1, wherein said core member has holes for integrally combining said core member and said resin molded portion with each other.
  • 6. The throttle valve control device for an internal combustion engine according to claim 1, wherein said core member has windows formed at its one side opposite said teeth.
  • 7. The throttle valve control device for an internal combustion engine according to claim 1, wherein said core member has a generally L-shaped cross section along an axial direction, and said vertex of said L-shape is laterally offset from a plane where the majority of said core member extends.
  • 8. The throttle valve control device for an internal combustion engine according to claim 1, wherein said support portion projects in an axial direction both in front of and behind said core member.
  • 9. The throttle valve control device for an internal combustion engine according to claim 1, wherein said teeth are substantially supported along their axial dimension by said support portion.
  • 10. The throttle valve control device for an internal combustion engine according to claim 1, wherein said teeth are fully supported along their axial dimension by said support portion.
  • 11. The throttle valve control device for an internal combustion engine according to claim 1, wherein said teeth project radially outward.
  • 12. The throttle valve control device for an internal combustion engine according to claim 1, wherein said resin molded portion covers only a radially outer portion of said core member.
  • 13. The throttle valve control device for an internal combustion engine according to claim 1, wherein said core member has a window formed on a radially inner portion.
  • 14. The throttle valve control device for an internal combustion engine according to claim 13, wherein said resin molded portion covers a portion of said core member radially outside said window.
  • 15. The throttle valve control device for an internal combustion engine according to claim 13, wherein said window is polygon shaped.
Priority Claims (1)
Number Date Country Kind
2001-162100 May 2001 JP
US Referenced Citations (2)
Number Name Date Kind
6092506 Takagi et al. Jul 2000 A
6173939 Dottavio et al. Jan 2001 B1
Foreign Referenced Citations (1)
Number Date Country
2000-282898 Oct 2000 JP
Non-Patent Literature Citations (2)
Entry
“Gears from Scratch” by Paul Sharke; Dec. 2001, Mechanical Engineering.*
Palomar Integral Field Spectrograph (PIFS) webpage dated Aug. 18, 1998 by Tom Murphy et al. at California Institute of Technology.