Device for controlling speed of an engine

Abstract: In a carburetor (2) of a motor vehicle engine having an accelerating pump (12) for supplying additional fuel when an accelerator pedal (3) is depressed to a large extent, the accelerator pedal (3) is connected to a slider (6) which is connected through an accelerating pump cable (8) to a swing arm (9) for actuating the accelerating pump (12) via a link (9b) and a lever (9c). The slider (6) is connected also to a throttle lever (10) through a throttle cable (7). The throttle (10) lever is coupled to a throttle shaft (13) of a throttle valve by means of a torsion spring (15). When the accelerator pedal (3) is depressed, the throttle cable (7) and the accelerating pump cable (8) are pulled, and the control lever (10) is turned to rotate the throttle shaft (13) by way of the spring (15) in a direction toward an open position of the throttling valve so that the engine (1) is accelerated, while the accelerating fuel pump (12) is operated through the swing arm (9), the link (9b) and the lever (9c) so that an increased amount of fuel is supplied by the pump (12). Since the throttle valve and the accelerating pump (12) are operated separately by way of the respective cables (7, 8), the throttle shaft (13) can be rotated with a small torque and the speed control can be carried out exactly without delay.

Description: The present invention relates to a device for controlling the speed of an engine, and, more particularly, to a device for controlling the engine speed with an improved response. As is well known in the art, an engine mounted on a motor vehicle has a carburetor. The carburetor has a throttle valve with a throttle shaft which rotates in response to depression of an accelerator pedal to control the amount of air fuel mixture supplied to the engine. The carburetor is provided with an accelerating pump for increasing fuel supply to the engine when the accelerator pedal is depressed to a large extent. The accelerating pump has an adjusting rod. The adjusting rod is coupled to the throttle shaft through a lever mechanism, as disclosed in Japanese Utility Model Laid Open Nos. 62-56752, 62-110558 and 62-116154. When the throttle shaft is rotated, the rotation is transmitted to the adjusting rod through the lever mechanism to displace the rod longitudinally, and the rod causes a piston to slide for increasing the amount of fuel supplied to the engine by means of the accelerating pump. However, a relatively large torque is required for rotating the throttle shaft because of the mechanical connection of the accelerating pump to the throttle valve. In FR-A-2 511 083 an operating device for an accelerating pump is disclosed, in which a throttle valve may be operated by a cable arrangement in common with an accelerating pump, however, using a return spring for closing the throttle valve. On the other hand, the engines of recent motor vehicles are installed with an engine speed control device. In EP-A-0 230 516 a speed control of a vehicle engine is disclosed, which comprises an accelerator, a carburetor with a throttle valve operatively connected to a rotatable throttle shaft, a throttle cable operatively connected between the accelerator and the throttle shaft, and a governor device for limiting the maximum speed of the engine, said governor device being mechanically connected by means of a governor cable to a control lever for rotating the throttle shaft toward a closed position of the throttle valve against the force of a spring which is connected to said throttle cable by means of a throttle lever when a predetermined speed of the vehicle is reached, an accelerating pump not being mentioned. However, an engine speed control device is typically in the form of a governor device having governor weights which swing or expand radially outwardly for maintaining a predetermined vehicle speed, to cause a governor lever to swing so as to rotate the throttle shaft in a direction toward a close position of the throttle valve. Consequently, the vehicle speed does not exceed 105 Km/h, for example, in the case of a small motor vehicle. As mentioned above, a relatively large torque is required for rotating the throttle shaft in the known devices, wherefore there occurs a delay in the response of the engine speed control device together with deviation of the maximun vehicle speed at which the throttle shaft is rotated in a direction toward the close position of the throttle valve. It is the problem underlying the present invention to provide a device for controlling the speed of an engine in which the engine speed control device can rotate the throttle shaft with a torque amount as small as possible, so as to respond rapidly without delay and deviation in rotating the throttle shaft. This problem is solved by claim 1. In a device of the invention, as there is no mechanical connection between the throttle valve and the accelerating pump, when the governor device closes the throttle valve, a considerable reduction of the force necessary for closing the throttle valve and, thereby, a rapid response on an action of the governor device is achieved. A preferred embodiment of the present invention will become understood from the following detailed description referring to the accompanying drawings. Fig. 1 is a diagrammatic perspective view showing a device for controlling speed of an engine according to the present invention; FIG. 2 is a left side view of a carburetor shown in FIG. 1; FIG. 3 is a rear view of the carburetor; FIG. 4A is a view as seen in the direction of arrow Z in FIG. 1; FIG. 4B is a plan view of FIG. 4A; FIG. 5 is a diagrammatic plan view of a driving system of a motor vehicle; FIG. 6 is a side view of a governor; FIG. 7 is a view of a governor chamber, as seen from the inside of a transmission; and FIG. 8 is a sectional view taken along the line VIII-VIII of FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 5, an intake pipe 1a of an engine 1 has a carburetor 2 operatively coupled to an accelerator such as an accelerator pedal 3. As shown in FIG. 1, the accelerator pedal 3 is connected to one end of an accelerator cable 4, and the other end of the cable 4 is fixedly coupled to a slider 6 which is slidable in a guide cylinder 5 mounted on a motor vehicle. The respective ends of a throttle cable 7 and an accelerator pump cable 8 are fixedly connected to the slider 6. The throttle cable 7 and the accelerator pump cable 8 extend to the carburetor 2. The cable 8 is connected at the opposite end thereof to a swing arm 9 (FIG. 2), which is pivotally supported on one side of the body of the carburetor 2 by means of a pivot pin 9a. The opposite end of the throttle cable 7 is coupled to a throttle lever 10 swingably mounted on the opposite side of the carburetor body. The throttle cable 7 extends along a guide 10b (FIG. 4B) formed on the throttle lever 10. The end of the cable 7 is coupled to the throttle lever 10 by means of a fitting hole 10c as shown in FIG. 4A. An accelerating pump 12 is fixedly provided adjacent to the carburetor 2 as shown. As shown in FIG. 1, the swing arm 9 is linked to an adjusting rod 12a of the accelerating pump 12 through a link 9b and a lever 9c. One end of the link 9b is joined to the swing arm 9 as shown in FIG. 3, and the other end of the link 9b is pivotally connected to one end of the lever 9c. As shown in FIG. 1, the lever 9c is pivoted by a pin 9d to the body of the carburetor 2. The other end of the lever 9c is pivotally connected at 9e to the adjusting rod 12a. When the accelerator pedal 3 is depressed, the amount of fuel supplied to a venturi tube of the carburetor 2 is increased according to the degree of the depression. As indicated in FIG. 1, the throttle lever 10 is freely rotatably fitted on a throttle shaft 13 to which a known throttle valve 13a in the form of a butterfly valve is secured. A control lever 14 is securely mounted on the throttle shaft 13 so as to rotate with the throttle shaft 13. A stopper 10a (FIGS. 4A and 4B) of the throttle lever 10 is disposed above the control lever 14. One end of a coiled torsion spring 15, which is mounted on the throttle shaft 13, is engaged with a pin 10d of the throttle lever 10, and the other end of the spring 15 is engaged with an angularly bent tip part 14a of the control lever 14, so that angular movement of the throttle lever 10 may be transmitted to the control lever 14 through the spring 15. More specifically, when the accelerator pedal 3 is depressed to pull the throttle cable 7, the throttle lever 10 is rotated to transmit clockwise rotation as viewed in FIG. 1 to the control lever 14 via the spring 15 so as to rotate the throttle shaft 13 toward a fully open position of the throttle valve 13a. One end of a return coil spring 16 is anchored at 16a to an extension 10e of the throttle lever 10, extending in a direction different from the main part of the throttle lever 10, as shown in FIGS. 1 and 4A. The other end of the return spring 16 is anchored at 16b (FIG. 1) to a stationary bracket. As a result, the throttle lever 10 is resiliently urged in an angular direction counter to the direction in which the throttle lever 10 is rotated by the pulling force of the throttle cable 7. As shown in FIG. 1, the control lever 14 has an integral extension 14b projecting in a direction opposite to the bent tip part 14a, and a governor cable 17 is anchored at one end thereof to the extension 14b. The other end of the governor cable 17 extends toward the engine 1. As shown in FIG. 5, a transmission 18 is connected to the engine 1 in such a manner that an input shaft 18a of the transmission may be coupled to a crankshaft 1b of the engine 1 through a clutch 1c. An output shaft 18b of the transmission 4 extends in parallel with the input shaft 18a in the transmission 4. The output shaft 18b and the input shaft 18a are drivingly coupled to each other through a plurality of transmission gears 18c which can be meshed with each other in different combinations by a shift lever 20' disposed adjacent to a driver's seat. The output shaft 18b is drivingly coupled to driving wheels 19 of the motor vehicle through output gears 19a. Referring next to FIG. 8, a governor chamber 21 defined by a cover 21a is provided in one side of the transmission 18, and one end of the output shaft 18b extends into the governor chamber 21 and slidably carries thereon a governor sleeve 22. A bush 20 is fixedly mounted on the output shaft 18b and the sleeve 22 is slidable thereon. A plurality of governor weights 22a are provided for shifting the governor sleeve 22. Each governor weight 22a is pivoted with a pivot pin 22b to an annular flange 20b of the bush 20. Therefore, when the rotational speed of the driving wheels 19 reaches a speed corresponding to, for instance, a speed of 105 Km/hr, each weight 22a is rotated by centrifugal force about the pivot pin 22b radially outwardly, so that an arm 22c of each weight 22a is axially pressed against the governor sleeve 22 which in turn is caused to slide in the rightward direction as viewed in FIG. 8 with respect to the output shaft 18b. The above described members constitutes a governor device 26. Referring also to FIG. 7, a governor shaft 23 extends rotatably through a boss 21b integrally extended inwardly from the cover 21a and securely carries at the inner end thereof the base end of a swing member 23a, which is in contact with the governor sleeve 20. It therefore follows that when the governor sleeve 20 is caused to slide to push the swing member 23a in the rightward direction as viewed in FIG. 8, the governor shaft 23 is rotated in a counterclockwise direction. One end of a governor lever 24 is securely fixed to the outer end of the governor shaft 23 extending beyond the governor chamber 21 while the other end of the governor lever 24 is securely attached to one end of the governor cable 17, as shown also in FIG. 6. As best shown in FIG. 6, one end of a governor spring 25a is anchored to the governor lever 24 at an intermediate point between the ends thereof, while the other end of the governor spring 25a is anchored to a bracket 25 on the casing of the transmission 18. The device for controlling the engine speed, as described above operates in the manner described below. When the accelerator pedal 3 is depressed, the accelerator cable 4 is pulled so that the slider 6 is caused to slide in the guide cylinder 5. Consequently, the throttle cable 7 and the accelerating fuel pump cable 8 are pulled by the slider 6, so that the swing arm 9 is swung about the pivot pin 9a in a counterclockwise direction as viewed in FIG. 3 while the throttle lever 10 rotates about the throttle shaft 13 in a clockwise direction as viewed in FIG. 1 against the force of the return spring 16. The rotary movement of the throttle lever 10 is transmitted to the control lever 14 through the torsion spring 15, whereby the throttle shaft 13 fixedly carrying the control lever 14 is rotated in a direction toward an open position of the throttle valve so that the engine speed increases. When the accelerator pedal 3 is depressed to a large extent, the swing arm 9 is swung accordingly, and the accelerating pump 12 is operated through the link 9b, the lever 9c and the adjusting rod 12a. That is, the adjusting rod 12a is so displaced in the longitudinal direction thereof as to increase the amount of fuel supplied to the engine 1 by the accelerating fuel pump 12. When the engine speed thus increases, the rotational speed of the input shaft 18a of the transmission 18 also increases, and the increased speed of the shaft 18a causes an increase of the rotational speed of the wheels 19 via the transmission gears 18c, the output shaft 18b and the output gears 19a. When the transmission gears 18c are changed to a higher gear ratio by the shift lever 20', the speed of the wheels 19 is further increased. When the rotational speed of the output shaft 18b increases to a value corresponding to a speed of 105 Km/h, for example, of the wheels 19, the centrifugal force produced by the rotation of the output shaft 18b causes the governor weights 22a to swing radially outwardly about the pin 22b to cause the governor sleeve 22 to slide in the rightward direction in FIG. 8. Thereupon, the governor sleeve 22 causes the swinging member 23a to swing counterclockwise as viewed in FIG. 8 so that the governor shaft 23 is rotated in the same direction and therefore the rotating torque is produced by the governor lever 24. When the rotational speed of the output shaft 18b exceeds a predetermined rotational speed so that the governor weights 22a press against the governor sleeve 22, the rotating torque of the governor lever 24 increases and overcomes the force of the governor spring 25a whereby the governor lever 24 is rotated. Thereupon, the governor cable 17 is pulled by the governor lever 24, and therefore the control lever 14 fixed to the throttle shaft 13 is rotated against the force of the torsion spring 15 in a direction counter to the direction in which the control lever 14 is urged by the spring 15 as a result of the depression of the accelerator pedal 3. As a consequence, the throttle shaft 13 is rotated by the control lever 14 in a direction to cause the throttle valve 13a to move toward a closed position thereof, independently of the degree of depression of the accelerator pedal 3. Therefore, the amount of fuel supplied to the engine 1 is reduced to cause decrease of the engine speed. What resists the rotation of the throttle shaft 13 during the above operation is only the urging force of the torsion spring 15. Therefore, it is possible to rotate the throttle shaft 13 with a smaller torque than in the conventional device in which the accelerating fuel pump 12 is coupled to the throttle shaft 13. This means that the governor device 26 can operate without delay and can follow speed increase instantaneously and that there occurs no deviation of the highest vehicle speed at which the throttle shaft 13 is rotated toward the close position of the throttle valve. Consequently, the motor vehicle speed is prevented exactly from exceeding a set speed of 105 Km/h, for example. When the vehicle slows down, the speed of the output shaft 18b coupled to the wheels 19 decreases, so that the centrifugal force acting on the governor weights 22a also decreases. Therefore, the governor lever 24 is returned by the force of the governor spring 25a since the rotating torque of the control lever 14 decreases. Consequently, the control lever 14 returns due to the force of the torsion spring 15 to a position corresponding to the degree of depression of the acceleration pedal 3. While the embodiment of the present invention has been described as applied to a motor vehicle with a transmission coupled to the engine, the present invention may be applied to motor vehicles without a transmission or to general purpose engines. Moreover, the accelerator and the engine speed control device are not limited to the accelerator pedal and the governor device of the type described above. Furthermore, the set maximum speed need not be limited to 105 Km/h. It will be understood from the foregoing that the present invention is useful in that the throttle shaft can be rotated with a smaller torque than in the conventional devices since the throttle shaft is not coupled to the accelerating pump and that the engine speed control device can respond without delay and deviation in rotating the throttle shaft.

Claims: A speed control device of a vehicle engine (1) having an accelerator (3), a carburetor (2) with a throttle valve (13a) Securely connected to a rotatable throttle shaft (13), a control lever (14) rigidly mounted to the throttle shaft (13), a throttle lever (10), rotatably mounted on said throttle shaft (13) and connected to said control lever (14) by means of resilient means (15) and to a throttle cable (7), the engine further comprising an accelerating pump (12) supplying additional fuel to the engine and being actuated by a pump cable (8), the device comprising a slider (6) connected at an output end thereof to said pump cable (8) and to said throttle cable (7), and at an input end thereof to an accelerator (3) by means of an accelerator cable (4), a governor device (26) for limiting the maximum speed of the vehicle being connected to said control device by a governor cable (17) for rotating the throttle shaft (13) toward a closed position of the throttle valve (13a) against the force of the resilient means (15) when a predetermined speed of the vehicle is reached. The device according to claim 1, wherein the pump cable (8) is coupled to a swing arm (9) pivotable responsive to pulling of the accelerating pump cable (8), the swing arm (9) being connected to an adjusting rod (12a) of the accelerating pump (12) through a motion transmittting mechanism (9b, 9c, 9d). The device according to claim 1 or 2, wherein the slider (6) is connected to said throttle lever (10) through the throttle cable (7).

Inventors: MIYAMOTO YASUHIKO C O FUJI JUK, MIYAMOTO, YASUHIKO, C/O FUJI JUKOGYO K.K.
Applicants: FUJI HEAVY IND LTD, FUJI JUKOGYO KABUSHIKI KAISHA
Application year: 1990
Main classification: F02M19
IPC codes: F02D11, F02M7, F02M19, F02D9