Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
2001-02-09
2001-10-02
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
C123S337000
Reexamination Certificate
active
06295968
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present invention is related to Japanese patent application No. 2000-39709, filed Feb. 17, 2000; 2001-9000, filed Jan. 17, 2001, the contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to a throttle apparatus for an internal combustion engine, and more particularly to a throttle apparatus for an internal combustion engine for adjusting an air flow rate of the engine.
BACKGROUND OF THE INVENTION
In a conventional throttle apparatus, an air path is formed in a throttle body and a valve member adjusts the opening angle of the air path. The valve is driven by electric driving means, such as a motor, such that even when the motor stops due to a breakdown or the like, the valve member is set to a desired open position, such as slightly open to maintain an opening angle in the air path. For example, by providing a return spring that urges the valve member closed, the valve member is set slightly open, even when the motor is unable to drive the valve member. Thus, the valve member is set slightly open, thereby enabling evacuation drive of a vehicle on which the throttle device is mounted.
In the conventional throttle apparatus, the throttle body and a gear housing of the motor are made of a metal material such as aluminum, manufactured with high precision. The rotary shaft of speed reducing gears such as the throttle gear and motor gear are supported by the gear housing.
In recent years, however, because of a demand for reduction in weight and cost of throttle devices, the throttle body is molded from a resin. When the throttle body is made of resin, the gear housing is also made of resin. Accordingly, the gear housing and the throttle body are integrally formed. However, when this is done, the molding may distort in the throttle body and dimensional accuracy between rotary shafts of speed reducing gears largely deteriorates due to insufficient rigidity of the throttle body as compared with one made of metal.
When the dimensional accuracy between the rotary shafts of the speed reducing gears deteriorates, the gear teeth of the gears wear during use, thereby causing motor torque loss. Moreover, it becomes difficult to transmit the motor driving force to the valve member. Further, when the dimensional accuracy between the rotary shafts of the speed reducing gears largely deteriorates, the speed reducing gears are locked and the valve member cannot be driven.
SUMMARY OF THE INVENTION
In view of these and other drawbacks, the present invention provides a throttle apparatus for an engine, having lower weight and cost, and assures high dimensional accuracy by enhancing rigidity.
According to the present invention, a holding member is provided in the throttle body that is made of a material having a higher strength than the resin material used for forming the throttle body. The holding member rotatably supports the valve member and holds the electric driving means. By making the throttle body from a resin material and housing the electric driving means in the throttle body, reduction in weight and cost of the throttle apparatus can be achieved. Further, with the holding member made of a high strength material, the rigidity of the throttle apparatus is enhanced and durability is improved. Further, since the holding member supports the valve member and holds the electric driving means, even when the throttle body is made of a resin material, high dimensional accuracy is assured between the supported portion of the valve member and the driving portion of the electric driving means. Therefore, the driving force of the electric driving means is transmitted to the valve member, and the controllability of the valve member is improved. Therefore, the air flow rate of the air path is properly adjusted.
In another aspect of the invention, a supporting member rotatably supports a transmitting means and is fixed to the holding member. The transmitting means is connected to the electric driving means and transmits a driving force from the electric driving means to the valve member. Consequently, high dimensional accuracy between the supporting member and the supported portion in the valve member and high dimensional accuracy between the supporting member and the driving portion in the electric driving means is assured. Therefore, the driving force of the electric driving means is more effectively transmitted to the valve member and the controllability of the valve member is increased. Accordingly, the air flow rate in the air path is more effectively adjusted.
In another aspect of the invention, the holding member houses the electric driving means. The holding member also serves as the housing of the electric driving means, thereby reducing the number of parts and assembly steps.
In another aspect of the invention, an inner wall of the air path near the valve member is formed by the holding member, so that the supported portion in the valve member and the driving portion of the electric driving means is parallel and held with high accuracy. Consequently, the driving force of the electric driving means is reliably transmitted to the valve member and the valve member is effectively controlled. Further, by integrating the portion where the air path inner wall near the valve member of the holding member is formed and the portion for holding the electric driving means, manufacturing cost is reduced without increasing the number of parts and assembling steps.
In another aspect of the invention, the holding member provided in the resin throttle body is made of a material having strength higher than the resin material of the throttle body. The holding member fixes the supporting member for rotatably supporting the transmitting means for transmitting the driving force of the electric driving means to the valve member. The holding member also and holds the electric driving means.
In another aspect of the invention, the holding member houses the electric driving means. The holding member also serves as the housing of the electric driving means, thereby reducing the number of parts and assembly steps.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
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Miura Yuichiro
Torii Katsuya
Argenbright Tony M.
Denso Corporation
Huynh Hai
Nixon & Vanderhye P.C.
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