Throttle valve actuator including separate valve driving devices

Abstract: The invention refers to a throttle valve actuator (300) comprising: accelerator pedal means (9); air pressure type drive means (329) controlled by the accelerator pedal means (9), for sliding a drive rod (335) thereof; sliding/rotating movement converting means (324,326,327, 328) connected to said drive rod (335) and a universal joint (334), for converting sliding force of said drive rod (335) into first rotation force; output shaft means (321) connected to said sliding/rotating movement converting means (324,336,327,328), for transporting said first rotation force to throttle valve means (16); housing means (322) for rotatably supporting said output shaft means (231); and, motor means (340) for rotating said throttle valve means (16) via said housing means (322) and output shaft means (321) by second rotation force, whereby said throttle valve means (16) is driven by both said first and second rotation force, and said second rotation force exerted by said motor means (340) does not give any force to said accelerator pedal means (9) via said sliding/rotating movement converting means (324,236,327,328), universal joint (334), and air pressure type drive means (329).

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention generally relates to a throttle valve actuator used for controlling engine power of an automobile. More specifically, the present invention is directed to a throttle valve actuator mutually controlled by an accelerator pedal and also an electric motor. Description of the Related Art Various attempts have been made in a throttle valve actuator to control a throttle valve of an automobile. One of the conventional throttle valve actuators is disclosed in Japanese KOKAI (Disclosure) patent application No. 61-215436 (1986) filed by Mitsubishi Denki K.K. in Japan. Fig. 1 shows a schematic diagram of the above-described conventional throttle valve actuator. Referring to Fig. 1, reference numeral 1 designates differential gears including a pair of opposed gears 2 and 3 and a pair of opposed gears 5 and 6 meshed with the gears 2 and 3. The gears 2 and 3 are rotatably supported to a shaft 4. A motor 7 is provided to rotate the gear 2 of the differential gears 1 through a gear 8. An accelerator pedal 9 is provided to rotate the gear 3 of the differential gears 1 through an accelerator wire 10, a pulley 11 and a gear 12 by depression force to be applied to the accelerator pedal 9. A gear 13 is mounted on a shaft 14 supporting the gears 5 and 6, and is meshed with a gear 15. A throttle valve 16 is operated through the gear 15 by the rotation of the gear 13. When the accelerator pedal 9 is depressed, the accelerator wire 10 is drawn to rotate the pulley 11 and the gear 12 and thereby rotate the gear 3. At this time, when the motor 7 is in an inoperative condition, the gear 3 is rotated to rotate the gear 13 and the gear 15 and, thereby open and close the throttle valve 16. When the motor 7 and the accelerator pedal 9 are simultaneously operated, both driving force thereof are output, or transported to the gear 13. Accordingly, the driving force of the gear 13 is the sum or difference between both the driving force of the motor 7 and the accelerator pedal 9. However, as the driving force of the motor 7 and the accelerator pedal 9 are applied in parallel to the same gear 13, a reaction of the torque of the motor 7 is transmitted to the accelerator pedal 9. As a result, when a car driver's foot is put on the accelerator pedal 9, a change in the depression force applied to the accelerator pedal 9 is felt through his foot on the pedal 9 by the driver because of the rotation of the motor 7, resulting in deterioration of drive feeling, i.e., drivability. Further, in the event that the motor 7 fails to operate, the throttle valve 16 cannot be returned from a controlled position upon occurrence of such motor malfunction to a valve closing position. Thus, the conventional actuator has a problem in fail-safe structure. Additionally, when the accelerator pedal 9 is rapidly depressed under the condition where the throttle valve 16 is opened at a certain angle by the motor 7, there is a possibility of the throttle valve 16 biting a body 17. If a stopper is provided to prevent such body biting, a depression stroke of the accelerator pedal 9 is shortened to cause deterioration of acceleration feeling. The present invention has been achieved to solve the above-described conventional problems. A primary object of the present invention is therefore to provide a throttle valve actuator which may eliminate the interference between the driving force of the motor and the depression force of the accelerator pedal. It is a second object of the present invention to provide a throttle valve actuator which may ensure fail-safe construction against motor malfunction by quickly interrupting the valve driving by the motor. It is a third object of the present invention to provide a throttle valve actuator which may prevent the throttle valve from biting the body even when the accelerator pedal is rapidly depressed under the condition where the throttle valve is opened at a certain angle by the motor. SUMMARY OF THE INVENTION The above-described objects of the present invention are accomplished by providing a throttle valve actuator as claimed in claim 1. Preferred embodiments of the invention are claimed in the further claims. BRIEF DESCRIPTION OF THE DRAWINGS The above purpose and other useful and novel features of the present invention will become more readily apparent from the following description in connection with the accompanying drawings, in which: Fig. 1 is a schematic diagram of the conventional throttle valve actuator; Fig. 2 schematically illustrates a construction of a throttle valve actuator 300 according to a basic idea of the present invention; Fig. 3 is a sectional view of the throttle valve actuator 300 taken along a line II-II in Fig. 2; Fig. 4 schematically illustrates an arrangement of the throttle valve actuator 300 and a throttle valve device; and Figs. 5 and 6 schematically illustrate modified constructions of the throttle valve actuator 300 shown in Fig. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT BASIC IDEA OF THE THROTTLE VALVE ACTUATOR A basic idea of the throttle valve actuator achieving the object of the present invention as mentioned above is as follows: The throttle valve actuator comprises an air pressure type drive device cooperating with an accelerator pedal to be advanced or retracted, a frame connected through a universal joint to the air pressure type drive device, a housing for rotatably supporting an output shaft connected to a throttle valve and housing a drum of the output shaft. The frame is operatively connected to the drum, wherein when the frame is advanced or retracted by the air pressure type drive device, the drum is rotated by the frame to thereby open/close the throttle valve. On the other hand, the housing and the output shaft are simultaneously rotated by driving a motor. With this arrangement, when the air pressure type drive device is advanced or retracted by depression force of the accelerator pedal, a linear motion of the frame is converted into a rotary motion of the drum engaged with the frame, thereby rotating the output shaft and opening/closing the throttle valve. On the other hand, when the motor is driven, a driving force of the motor is transmitted through gears to the housing, thereby rotating the housing together with the output shaft and opening/closing the throttle valve. Accordingly, no reaction against the driving force of the accelerator pedal and also the motor is applied thereto. Further, there is no possibility of the throttle valve biting a body upon depression of the accelerator pedal. CONSTRUCTION OF THE THROTTLE VALVE ACTUATOR Referring to Fig. 2 which is a sectional view of a throttle valve actuator 300 according to a preferred embodiment, reference numeral 321 designates an output shaft connected to a throttle shaft of a throttle valve 16. The output shaft 321 is rotatably supported through bearings 323A and 323B to a housing 322. The output shaft 321 is formed with a drum 324 having a spiral groove 326 on the outer circumference thereof. A ring 326 is slidably mounted on the drum 324 in its axial direction (i.e., in the horizontal direction as viewed in Fig. 12). As shown in Fig. 3 (a cross section taken along the line II-II in Fig. 2), the ring 326 is formed at its inner circumference with an inwardly projecting pin 327 to be engaged with the spiral groove 325 of the drum 324. A frame 328 is connected at its one end to the ring 326, and axially movably extends out of the housing 322. The frame 328 is connected at the other end to an air pressure type drive device 329 cooperating with an accelerator pedal. The air pressure type drive device 329 includes a casing 330 partitioned into first and second air chambers 332 and 333 by a diaphragm 331, and a rod 335 connected at its one end to the diaphragm 331 and connected at the other end through a universal joint 334 to the frame 328. Return spring 336 is interposed between the casing 329 and the diaphragm 331 so as to return the diaphragm 331 to its neutral position. The casing 329 is provided with air holes 337 and 338 communicated with the first and second air chambers 332 and 333, respectively. Reference numeral 350 designates a motor having an output gear 341 meshing with a gear 329 mounted on the housing 322. Especially, the air pressure type drive device 329 constitutes an essential part of the throttle valve actuator 300. Referring to Fig. 4 which shows an arrangement of the throttle valve actuator 300 adapted to an engine so as to control a throttle valve 16, the throttle valve actuator 300 is connected to an actuator controller 344 for controlling the throttle valve actuator 300 upon receipt of a signal from an accelerator sensor 343 for detecting a depression quantity of an accelerator pedal 9. OPERATION OF THE THROTTLE VALVE ACTUATOR Operation of the throttle valve actuator 300 according to the basic idea of the invention will now be described with reference to Figs. 2 to 4. When the motor 340 is in an inoperative mode under the control of the actuator controller 344 shown in Fig. 4, and air in the first air chamber 332 is extracted from the air hole 337 of the drive device 329, a pressure differential is generated between the first and second air chambers 332 and 333. As a result, the rod 335 is leftwardly urged by the diaphragm 331 to a position where the pressure differential balances a biasing force of the return spring 336, thereby advancing the frame 328 and the ring 326 leftwardly, as viewed in Fig. 2. As the pin 327 of the ring 326 is engaged with the spiral groove 325 of the drum 324, the drum 324 is rotated by the advancing of the ring 326 to thereby rotate the output shaft 321 and open the throttle valve 16 (See Fig. 4). To the contrary, when air pressure in the second air chamber 333 is made greater than the air pressure in the first air chamber 332, the diaphragm 331 is moved rightwardly as viewed in Fig. 2 to thereby retract the rod 335 and the frame 328 rightwardly as viewed in Fig. 2. As a result, the drum 324 is reversely rotated to close the throttle valve 16 via the output shaft 321. On the other hand, when the motor 340 is driven under the control of the actuator controller 344, the housing 322 is rotated through the gears 341 and 339. As a result, the output shaft 321 is rotated together with the housing 322 to control the operation of the throttle valve 16. That is, a total rotational angle of the output shaft 321 results in the sum or difference between a rotational angle by the drive device 329 and a rotational angle by the motor 340. Further, since the frame 328 is connected through the universal joint 335 to the rod 335 of the drive device 325, the torque of the housing 322 is not transmitted to the drive device 329. In summary, the throttle valve actuator 300 exhibits the following effects. First, since the air pressure type drive device 329 is employed as a drive device for driving the throttle valve 16, a cushioning effect may be exhibited when the throttle valve 16 actually contacts the body 17 upon depression of the accelerator pedal 9, thereby preventing the throttle valve 16 from biting the body 17. Second, in the event that the actuator controller 344 is brought into malfunction, the air in the first and second air chambers 332 and 333 of the drive device 329 is released to the atmosphere to return the diaphragm 331 to the neutral position. Accordingly, the throttle valve may be manually controlled to ensure the safety drive of the vehicle. MODIFICATIONS OF THE THROTTLE VALVE ACTUATOR Although the housing 322 is rotated by the motor 340 in the above preferred embodiment, it may be driven directly by a wire connected to the accelerator pedal 9. Further, while a mechanism for converting a linear motion into a rotary motion is established by the combination of the drum 324 and the ring 326 in the above preferred embodiment, any other mechanisms may be employed as shown in Figs. 5 and 6, for example. Referring to Fig. 5, the drum 324 is formed at its outer circumference with a spiral ridge 324A, and the ring 326 is formed at its inner circumference with an oblique groove 326A to be engaged with the spiral ridge 324A of the drum 324. Referring to Fig. 6, the drum 324 is formed at its outer circumference with a plurality of spiral grooves 325, and the ring 326 is formed at its inner circumference with a plurality of inwardly projecting pins 327 to be engaged with the spiral grooves 325 of the drum 324. According to the throttle valve actuator 300 of the present invention, the linear motion of the rod of the air pressure type drive device is converted into the rotary motion of the output shaft to thereby open/close the throttle valve. On the other hand, the output shaft is also rotated with the housing to be driven by the motor, thereby opening or closing the throttle valve. Accordingly, both the driving forces of the air pressure type drive device and the motor do not interfere with each other to improve the drive feeling or drivability. Further, since the air pressure type drive device is employed as a drive device for driving the throttle valve, a cushioning effect may be exhibited when the throttle valve contacts the body upon depression of the accelerator pedal, thereby preventing the throttle valve from biting the body. Moreover, in the event that the actuator controller is brought into malfunction, the air in the first and second air chambers of the drive device is released to the atmosphere to return the diaphragm to the neutral position. Accordingly, the throttle valve may be manually controlled to ensure the safety of the vehicle.

Claims: A throttle valve actuator (300), comprising: accelerator pedal means (9); air pressure type drive means (329) having a drive rod (335), said air pressure type drive means (329) being controlled by said accelerator pedal means (9) to drive said drive rod (335) into axial movement; sliding-rotating movement converting means for converting the axial movement of said drive rod (335) into rotational movement of a throttle valve (16); said converting means including an output shaft (321) connected to said throttle valve (16), a drum (324) securely mounted on said output shaft (321) and having an engaging means (325, 324A) thereon, a frame (326, 328) engaging said drum (324) by said engaging means at its one end and said drive rod (335) via a universal joint (334) at its other end, and a housing (322) for holding said output shaft (321), said drum (324), and said frame (326, 328), said housing (322) being rotatably mounted on said output shaft (321), on both sides of the drum; said universal joint (334) transmitting axial movement of said drive rod (335) to said frame (326, 328) and not transmitting rotational movement of said frame (326, 328) to said drive rod (335); said frame (326, 328) engaging said drum (324) so as to convert the sliding movement of said drive rod (335) into a rotational movement of said drum (324); and motor means (340) for driving said housing means (322) into rotation; whereby said air pressure type drive means (329) and said motor means (340) drive said throttle valve (16) independently of the other. A throttle valve actuator (300) as claimed in claim 1, wherein: said engaging means is a spiral groove (325); and said frame engages said groove (325) by a ring (326) having a pin (327) engageable with said spiral groove (325) of said drum (324). A throttle valve actuator (300) as claimed in claim 1, wherein: said engaging means is a spiral ridge (324 A); and said frame engages said ridge (324 A) by a ring (326) having a spiral groove (326 A) engageable with said spiral ridge (324 A) of said drum (324) under spline engagement. A throttle valve actuator (300) as claimed in claim 1, wherein: said engaging means consists of a plurality of spiral grooves (325); and said frame engages said grooves (325) by a ring (326) having a purality of pins (327) engageable with said plurality of spiral grooves (325) of said drum. A throttle valve actuator (300) according to one of claims 1 to 4, wherein said air pressure type drive means (329) is constructed of a first air chamber (332), a second air chamber (333), a diaphragm (331) for separating said first and second air chambers (332; 333) and connected to said drive rod (335), and a balancing spring (336) provided on said drive rod (335) for giving balancing spring force to said diaphragm (331), whereby said diaphragm (331) is returned to its neutral position by said balancing spring force when both said first and second air chambers (332; 333) are opened to atmospheric pressure.

Inventors: KAJIWARA YASUYA, KAJIWARA, YASUYA
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1988
Main classification: F02D11
IPC codes: F02D11