THROTTLE VALVE CONTROLLER

Abstract: The system controls the opening of a throttle valve (2) to an optimum value which is calculated by an arithmetic control unit (12) based on signals from an accelerator pedal quantity sensor (11) and an operation condition sensor (9). Two independent motors (71, 72) rotate independently from each other. A drive force converter (70) synthesies the rotational motions of the two motors into a linear motion for transmission (3,4,5) and opens the throttle valve until the opening becomes optimum.

Description: SPECIFICATION THROTTLE VALVE CONTROL DEVICE FIELD OF TECHNOLOGY The present invention relates to a throttle valve control device of an automobile engine and, particularly, to such device in which a throttle valve of the engine is controlled by an electronic controlled actuator. BACKGROUND OF TECHNOLOGY Recently, as a portion of an engine control for improving the feeling of running and the fuel economy of an automobile, a throttle valve control by means of an electronic controlled actuator which does not use any mechanical linkage between a throttle valve and an acceleration pedal and controls an opening of the throttle valve in response to an electric signal obtained by converting an amount of depression of an acceleration pedal and other signals such as engine rotation signal which is representative of engine operating condition and gear position signal which is representative of automobile running condition has been developped. In the throttle valve control device using such electronic controlled actuator, the throttle valve opening is regulated by a driving motor actuated upon instructions from an automobile control device comprising an operation control portion for sequentially operating an optimum throttle opening according to signals representative of an engine operating condition and automobile running condition. Therefore, it is necessary to have a safety device capable of preventing an uncontrolled running of the automobile even if the electronic controlled actuator becomes inoperative during running of the automobile, and examples of such safety device are shown in Japanese Patent Application Laidopen No. 145867/1980 as (1) provision of a return spring on a throttle shaft which functions to return a throttle valve to a closed position when a control is lost, (2) provision of an electromagnetic clutch for disconnecting a throttle shaft from an electronic controlled actuator when it becomes uncontrollable, or (3) provision of a construction which is a combination of a return spring and an electromagnetic clutch and functions to make the return spring effective when the electromagnetic clutch is separated. A throttle valve control device according to the preamble part of claim 1 is known from EP-A-0 154 036. This reference discloses a throttle valve controlling apparatus comprising a throttle valve, the opening degree of which is regulated to vary an output of the engine. Moreover, the known throttle valve control device comprises an operation control portion in the form of a control unit for calculating an aimed opening degree of said throttle valve on the basis of an opening information of said throttle valve, a running condition information of an automobile and a depression amount of an acceleration pedal. Moreover, the known control device comprises an opening sensor in the form of a detector and a driving motor. With this known apparatus the position of the throttle valve is feedback controlled with the signals of the throttle valve position sensor. On page 7, first paragraph of this reference it has been described that if the motor gets out of order, it is impossible to control the throttle valve but the return torque of a torsion coil-spring can close the throttle valve such that an irregular operation of the engine is prevented even when either the torsion coil-spring or the motor becomes out of order. With the generic control device, however, it is impossible to maintain a running of the automobile and thus it becomes impossible to move the automobile to a reparing place although it is possible to prevent an uncontrolled running of the automobile. Finally, EP-A-0 241 841 and US-A-1 669 107 disclose apparatuses having driving force conversion mechanisms in the form of a differential gear which combine the rotational movements of two motors and convert the combined movements into a movement. It is an object underlying the present invention to provide a throttle valve control device according to the preamble part of claim 1 which is highly reliable and has a high speed response. DISCLOSURE OF THE INVENTION This solution of this object is achieved by the features of claim 1. That is, the throttle valve control device according to the present invention comprises a first and a second driving motors which are independent on each other and a driving force conversion mechanism which combines rotational movements of these driving motors and converts a combined movement into a linear movement. The first and the second driving motors are controlled on the basis of control signals from an operation control portion for calculating an optimum throttle opening sequentially. With this construction, the throttle valve opening can be controlled so long as both the first and the second driving motors become inoperative. When both of the driving motors are operative, an operation speed of the throttle valve becomes twice that when one of the motors operates, resulting in a highly safe control device which is inexpensive and has a high response speed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a general construction of an automobile control device including the present throttle valve control device and Figs. 2 and 3 show concrete embodiments of the present invention, respectively. BEST MODE FOR PRACTICIZING THE PRESENT INVENTION The present invention will be described in detail with reference to the drawings. Fig. 1 shows a general construction of an automobile control device including the present throotle valve control device, in which 1 depicts an air suction tube of an engine (not shown) and 2 a throttle valve. The throttle valve 2 rotates around a vavle shaft 3 to which a disc 4 is fixedly secured. An acceleration wire 5 is wound in a groove of the disc 4. The acceleration wire 5 is tensioned by a return spring 6. The return spring 6 is mounted on the valve shaft 3 helically and has one end fixed to the disc 4. A torque in a direction in which the throttle valve 2 is returned to a closed position is applied to the valve shaft 3 by this return spring 6. An opening sensor 8 is mounted on the valve shaft 3. The opening sensor 8 is to detect an opening A of the throttle valve and a detection output thereof is supplied to an operation control portion 12. 7 depicts a base of an actuator. A pair of driving motors 71 and 72 which have identical characteristics are provided on the base 7. Rotational movements of the driving motors 71 and 72 are transmitted to a driving force conversion mechanism 70, independently, in which these movements are converted into a linear movement to pull-up the acceleration wire 5. Fig. 2 shows an embodiment of the driving force conversion mechanism 70. In the embodiment in Fig. 2, worm gears 73 and 74 are mounted on output shafts of the respective driving motors 71 and 72, which mesh with worm wheels 75 and 76, respectively. Pulleys 77 and 78 are provided integrally with the worm wheels 75 and 76, respectively, and are mounted rotatably on the base 7. One end of a wire 79 is connected to the pulley 77 and can be wound thereon and the other end is connected to the pulley 78 and can be wounded thereon. A third pulley 80 is disposed in contact with the wire 79. A center shaft 81 of the third pulley 80 is inserted into a groove 82 formed in the base 7 slidably in vertical directions. A hook 83 is fitted on the center shaft 81, to which one end of the acceleration wire 5 is fixed. The other end of the acceleration wire 5 is wounded on the groove of the disc 4. A running condition detecting sensor 9 detects, for example, engine rotation N and running speed V as running condition of an automobile. The engine rotation N and the running speed V are sent to the operation control portion 12. A depression amount of an acceleration pedal 10 is detected by an acceleration amount sensor 11. An output of the depression amount sensor 11 is also supplied to the operation control portion 12. The operation control portion 12 receives the outputs of the running condition detecting sensor 9 and the acceleration amount sensor 11 and processes them according to predetermined programs to provide an aimed opening of the throttle valve 2 and to compare an output signal of the throttle opening sensor 8 with the aimed opening to provide rotation signals to the driving motors 71 and 72 according to a deviation therebetween. An operation of the invention will be described. The rotational forces of the driving motors 71 and 72 are applied through the worm wheels 73 and 75 and the worm wheels 74 and 76 to the pulleys 77 and 78, respectively independently. The wire 79 provided between the pulleys 77 and 78 have the one end connected to the pulley 77 and the other end connected to the pulley 78, as mentioned. Therefore, in Fig. 2, when the pulley 77 is rotated in clockwise direction while the pulley 78 is rotated in counterclockwise direction, the wire 79 is wound on the respective pulleys and thus the thirdpulley 80 sidposed in contact with the wire 79 is pulled up. A moving speed v₀ of the third pulley 80 has the following relation with respect to moving speeds v₁ and v₂ (v₁ and v₂ include directions, respectively) of the wire 79 on the sides of the respective pulleys 77 and 78 v₀ = (v₁ + v₂)/2 Assuming v₁ = v₂, the third pulley 80 moves at the same speed that of the wire 79 without rotation and when v₁ is different from v₂, the pulley 80 moves at an average speed while rotating. When the third pullley 80 moves in this manner, the acceleration wire 5 is pulled through the hook 83 mounted on the third pulley 80 to thereby regulate the opening of the throttle valve 2. The operation control portion 12 calculates an aimed opening of the throttle valve 2 on the basis of an acceleration opening A detected by the opening sensor 8, the engine rotation N and the speed V of the automobile and supplies rotation instructions to the driving motors 71 and 72 of the above described driving portion such that a difference between the opening of the throttle valve 2 and the output signal of the opening sensor 8 becomes zero. Contents of each rotation instruction includes rotation direction, power supply (rotation), power stop (stop), braking, etc., of the associated driving motor depending upon the operation mode thereof. In the throttle valve control device according to the present invention, it is possible to control the opening of the throttle valve 2 so long as both of the driving motors 71 and 72 become inoperative simultaneously. When both of the motors 71 and 72 operate, the moving speed of the throttle valve 2 becomes twice that when only one driving motor operates. Although, in the described embodiment, the driving force conversion mechanism 70 includes the worm gears 73 and 74, the worm wheels 75 and 76, the pulleys 77, 78 and 80 and the wire 79, the construction of the driving force conversion mechanism 70 is not limited to this embodiment and it is possible to realize the mechanism by a construction shown in, for example, Fig. 3. That is, in Fig. 3, the worm gears 73 and 74 are driven by the driving motors 71 and 72, respectively. The worm gears 73 and 74 are fixedly secured onto the shafts of the driving motors 71 and 72, respectively. Center shafts of pinions 750 and 760 are rotatably inserted into the base 7. One ends of the pinions 750 and 760 mesh with the worm gears 73 and 74, respectively, and the other ends of these pinions mesh with racks 770 and 780, respectively. Thus, the worm gears 73 and 74, the pinions 750 and 760 and the racks 770 and 780 constitute two sets of pinion and rack assemblies. The raks 770 and 780 are slidable on the base 7 along longitudinal directions thereof. A gear 800 is arranged between the racks 770 and 780 in a meshing relation thereto. A center shaft 81 of the gear 800 is fitted in a groove 82 formed in the base 7 such that it is shiftable freely vertically. A hook 83 is fitted on the center shaft 81 of the gear 800 and one end of the acceleration wre 5 is fixed to the hook 83. An operation of the device constructed as shown in Fig. 3 will be described. Rotational forces of the driving motors 71 and 72 are transmitted independently through the worm gears 73 and 74 and the pinions 750 and 760 having the worm wheels at one ends thereof to the racks 770 and 780, respectively. Therefore, the racks 770 and 780 are driven vertically. On the other hand, since the gear 800 meshes with the racks 770 and 780 in between them, the gear moves vertically with the vertical movements of the racks 770 and 780. Representing the moving speeds of the racks 770 and 780 by v₁ and v₂ with moving directions inclusive and the moving speed of the gear 800 by v₀, a relation of v₀ = (v₁ + v₂)/2 is established as in the case shown in Fig. 2 so long as the two sets of gear mechanisms arranged in an opposing relation have identcal specifications. Although, in the above mentioned embodiment, the acceleration wire 5 and the disc 5 are used as means for operating the throttle valve 2, it is needless to say that the same effect may be obtained by using a link coupling.

Claims: 1. A throttle valve control device comprising: a throttle valve (2) having an opening degree (A) which is regulated to vary an output of an engine, an operation control portion (12) for calculating an aimed opening degree (A) of said throttle valve (2) on the basis of an opening information of said throttle valve (2), a running condition information of an automobile and a depression amount of an acceleration pedal (10), an opening sensor (8) for detecting the opening degree (A) of the throttle valve (2), and at least a first driving motor (71), being characterized in that a second driving motor (72) is provided, that a driving force conversion mechanism (70) is provided which combines rotational movements of said first and second motors (71, 72) and converts the combined movements into a linear movement by which linear movement the opening degree (A) of said throttle valve (2) is regulated, and that said operation control portion (12) supplies rotation instructions to said first and second driving motors (71, 72) such that a deviation between the opening degree (A) of said throttle valve (2) and an output signal of said opening sensor (8) becomes zero. 2. The throttle valve control device as claimed in claim 1, wherein said driving force conversion mechanism (70) comprises a first and a second pulley (77, 78) adapted to be driven through worm gears (75, 76) driven independently by said first and said second driving motors (71, 72) respectively, a wire (79) arranged between said first and said second pulleys and having ends connected to said first and said second pulleys (77, 78), respectively, said wire (79) capable of being wound on said first and said second pulleys (77, 78), and a third pulley (80) arranged between said first and said second pulleys (77, 78) and slidable with respect to said wire (79), whereby an opening (A) of said throttle valve (2) is regulated by a movement of said third pulley (80). 3. The throttle valve control device as claimed in claim 1, wherein said driving force conversion mechanism (70) is constituted with a first and a second rack-pinion mechanism arranged such that said first and second rack-pinion mechanisms are driven by said first and said second driving motors (71, 72), respectively and independently, so that a single gear (800) is operated thereby differentially, whereby an opening (A) degree of said throttle valve (2) is regulated by a movement of said single gear (800). 4. The throttle valve control device as claimed in claim 3, wherein said first and second rack-pinion mechanisms comprise first and second worm gears (73, 74) driven by said first and second driving motors (71, 72) and first and second pinions (750, 760) meshed with said first and second worm gears (73, 74) and first and second racks (770, 780), respectively.

Inventors: SHIRAKAWA, HIROYUKI SOUGOU JIDOUSHA ANZEN KOUGAI
Applicants: MITSUBISHI DENKI KABUSHIKI KAISHA, SOUGOU JIDOUSHA ANZEN KOUGAI GIJUTSU KENKYU KUMIAI
Application year: 1987
Main classification: F02D9
IPC codes: F02D11