GB2259550A

GB2259550A - Motor vehicle engine throttle valve actuation

Info

Publication number: GB2259550A
Application number: GB9218808A
Authority: GB
Inventors: Rolf Kupper
Original assignee: Hella KGaA Huek and Co
Current assignee: Hella GmbH and Co KGaA
Priority date: 1991-09-10
Filing date: 1992-09-04
Publication date: 1993-03-17
Anticipated expiration: 2012-09-04
Also published as: DE4129960A1; DE4129960C2; GB2259550B; GB9218808D0

Abstract

The throttle valve DK is rotatable in the direction 3 by the electric motor M from the idling position in response to operation of the accelerator pedal FP. The cable operated disc SS permits rotation of the valve DK in the direction 3, when the motor M is inoperative, to provide up to 45 DEG rotation for emergency throttle valve operation. <IMAGE>

Description

1 DEVICE FOR ADJUSTING THE DRIVING SPEED OF A MOTOR VEHICLE This invention

relates to a device for adjusting the driving speed of a motor vehicle.

Such a device is already known from German Patent 33 26 460, having an accelerator pedal, an electrical adjusting device for a throttle valve of the vehicle engine controlled by the accelerator pedal, biasing means which urges the throttle valve towards an idling position, and a disengageable mechanical connection between accelerator pedal and throttle valve. In this known device the mechanical connection of the accelerator pedal to the throttle valve is always disengaged when the electrical connection of the accelerator pedal to the throttle valve is functioning satisfactorily. However, as soon as a functional disturbance occurs of the electrical connection between the accelerator pedal and the throttle valve, the disengagement is cancelled, so that the accelerator pedal is connected directly to the throttle valve via a cable control. At the same time, the electrical connection of the accelerator pedal to the throttle valve is made ineffective.

The known device however, has a comparatively high construction cost, as it requires an auxiliary biasing means acting counter to a spring force for producing the disengagement. In addition, the means of disengagement is embodied in a structurally costly manner, 2 which makes the known device expensive from the point of view of manufacturing costs.

From German Offenlegungsschrift 37 12 927 is already known an arrangement of throttle valves in the intake manifold of an internal combustion engine, which is designed in such a way that two throttle valves are mounted freely rotatably in a throttle valve conduit on a common shaft. Here, one of the two throttle valves is connected electrically and the other of the two throttle valves is connected mechanically to an accelerator pedal. This solution is likewise expensive from a manufacturing cost point of view, as a structurally complicated arrangement of two throttle valves in one throttle valve conduit is necessary. In addition, no measures are stated as to how an emergency running function is intended to be created via the mechanical connection of the accelerator pedal to one of the throttle valves, in the event of a faulty function of the electrical connection.

According to one aspect of the present invention, there is provided a device for adjusting the driving speed of a motor vehicle, operable through an accelerator pedal or the like for a throttle valve of the vehicle engine and comprising an electrical adjusting device for the throttle valve arranged to be controlled by the accelerator pedal and a disengageable mechanical connection for linking the accelerator pedal and the throttle valve, the electrical adjusting device being arranged to open the throttle valve in one direction of 1 3 rotation and the mechanical connection being arranged to open the throttle valve in the other direction of rotation, respective biasing means for urging the throttle valve towards an idling position acting upon the mechanical connection and upon the electrical adjusting device, said biasing means for the mechanical connection and the electrical adjusting device acting on the throttle valve in opposite directions.

According to a further aspect of the invention, there is provided device for adjusting the driving speed of a motor vehicle through an accelerator pedal or the like and comprising a throttle valve of the vehicle engine which is arranged in a freely rotatable manner in a throttle valve conduit, an electrical adjusting device, controllable by the accelerator pedal, means for biasing the throttle valve towards an idling position of said valve and a disengageable mechanical connection between the accelerator pedal and the throttle valve, the electrical adjusting device being arranged to open the throttle valve in one direction of rotation, and the mechanical connection being arranged to open the throttle valve in the opposite direction of rotation, said biasing means acting upon the mechanical connection and a second biasing means.acting upon the electrical adjusting device in a direction counter to the first biasing means and urging the throttle valve towards its idling position.

By arranging the throttle valve freely rotatable in the throttle valve conduit it is possible for the 4 control of fuel to the motor vehicle engine and thus of the driving speed of the vehicle to be achieved not only by opening in the one direction of rotation of the throttle valve, but also by opening in the opposite direction of rotation. This is in contrast to the already known device which has had a stop for the idling position of the throttle valve.

Because the electrical adjusting device opens the throttle valve in one direction of rotation and the mechanical connection opens the throttle valve in the other direction of rotation, a clear separation of the normal electrical adjustment means of the driving speed of the motor vehicle from the emergency mechanical adjustment means can be ensured.

The two biasing forces, which are directed counter to each other, act not only on the mechanical connection but also on the electrical adjusting device. The first force acts upon the mechanical connection in such a way that it biases the throttle valve from the open position which is provided for emergency operation, towards the idling position. The biasing force acting upon the electrical adjustment device is consequently in the opposite direction and acts towards the idling position if the throttle valve is pivoted by means of the electrical adjusting device out of the rest position into a normal electrical operating position.

During the normal electrical operation of the device the throttle valve is displaced by the electrical adjusting device against the second biasing force in the one direction of rotation, as determined by the driver of the vehicle depressing the accelerator pedal. During the normal operating sequence, the mechanical connection between the accelerator pedal and the throttle valve is ineffective, because it has been disengaged.

As soon as a disturbance of the electrical adjusting device occurs which results in the electrical adjusting device no longer being able to displace the throttle valve from the idling position, against the second biasing force, into an open position in the direction of rotation of normal operation, the mechanical connection between the accelerator pedal and the throttle valve is effected thereby, because the disengagement is cancelled. When the driver of the vehicle sets a driving speed by depressing the accelerator pedal, the pedal position is then transmitted by the mechanical connection against the first biasing force to the throttle valve in such a way that the valve is opened from the idling position in the opposite direction of rotation.

As compared with the already known device, it is possible to arrange a device according to the invention so that emergency operation is always guaranteed without the use of further auxiliary biasing means and without the provision of expensive control circuits to generate switching instructions. In particular, by the avoidance of servo drives actuated by auxiliary force, a device according to the invention can be produced in a 6 considerably simpler and more cost-effective manner. Nevertheless, like the already known device, it can make possible a comfortable emergency running function in which by the emergency control of the driving speed of the motor vehicle, it is possible not only to reach the nearest motor vehicle workshop, but dynamic driving techniques, at least within limits, are possible also.

Advantageous arrangements and developments of devices according to the invention appear in features of the subsidiary claims.

It is especially advantageous if the source of the first and/or the second biasing force is a return spring. It is of course basically possible by other measures, such as, for example, an asymmetrical mounting of the throttle valve, to generate resetting forces which act upon the throttle valve. The use of return springs, however, makes possible by suitable selection of the. spring constants and the force action generated in each case, a simple and cost-effective adaptation to the given electro-mechanical conditions of the device.

The means of disengaging the mechanical connection can particularly advantageously comprise a stop which is connected to the accelerator pedal. It may further comprise a lever which is connected to the throttle valve. This mechanical solution is likewise simple and cost-effective. Apart from the aforementioned parts of the device, no further means for effecting the disengagement are necessary in this case.

7 The accelerator pedal can advantageously be connected via a control cable to a cable disc, which is arranged on the throttle valve conduit. Here, the cable disc can have the stop. Such arrangements consisting of an accelerator pedal, control cable, cable disc and throttle valve are already known as conventional mechanical devices for adjusting the driving speed of motor vehicles. These known solutions have proved to be specially simple, cost-effective and reliable in operation. They guarantee the necessary emergency running function in almost all cases. In the application of the invention the provision of a stop on the cable disc is a simple and cost-effective structural measure. In this connection, the first biasing force can also act upon the stop, more especially on the cable disc. This measure is likewise especially simple and costeffective, because then the return spring that is used for example, like the cable disc, can be mounted directly on the throttle valve conduit. 20 Similarly there can be provided a second stop which limits displacement of the throttle valve by the mechanical connection, in the closing direction of the throttle valve, to the fully closed position. With these measures, the throttle valve is prevented from remaining in a position other than the fully closed position as a result of forces differently generated by the return springs, when the accelerator pedal is released. This solution prevents racing of the vehicle engine and 8 increases the reliability of the device.

In this connection, the force of the first biasing means can advantageously be greater than the force of the second biasing means. With this measure, it is ensured that when the electrical adjusting device is not acting against the second biasing force, the throttle valve, eg. through its lever, always butts against the stop of the cable disc. At the same time, it is ensured by the first biasing force acting on the cable disc, for example, that the throttle valve is pressed against the second stop if the accelerator pedal is not depressed, so that the throttle valve remains in the fully closed position.

In order to be able to exploit to the full the power potential of the motor vehicle engine during the normal operation of the vehicle by setting of the driving speed through the electrical adjusting device, it is especially advantageous if the electrical adjusting device can displace the throttle valve between roughly the fully closed position and the fully opened position.

On the other hand, in order to indicate to the driver of the vehicle the failure of the electrical adjusting device, it is especially advantageous if the mechanical connection can only displace the throttle valve between roughly the fully closed position and a partly- opened position. If this is the case, the driver can recognise by the reduced power output that a fault must be present which, if necessary, can be indicated to him by an 9 auxiliary warning device, such as for example a warning light.

In order to simplify the electromechanical construction of the device according to the invention, it is of assistance if at least one electrical reference element is provided which is connected directly to the cable disc on the throttle valve conduit.

As a result of these measures, no reference element need be arranged directly on the accelerator pedal, which shortens the electrical connections between the reference elements and the electrical adjusting device.

An example of an embodiment of the device according to the invention is illustrated in the accompanying drawings and explained in greater detail hereafter by reference to these drawings.

Fig. 1 shows a device according to the invention in a simplified diagrammatic illustration, and Fig. 2 is a diagram indicating the quantity of air flowing through in relation to the throttle valve opening.

In Fig. 1 the device is shown having an electric servomotor (M) as an electrical adjusting device, which is connected by a.shaft to a first actual value transmitter (IG1) and a second actual value transmitter (IG2) in the form of potentiometers. Furthermore, the electric servomotor (M) is connected by the same shaft to a throttle valve (DK), which is mounted in a throttle valve conduit (DKS). on the side of the throttle valve (DK) directed away from the electric servomotor (M) there is a lever (H), which is likewise non- rotatably connected to the right hand shaft in Fig. 1. For clarity of illustration the shaft of the aforementioned throttle valve is shown in Fig. 1 turned through 90' to the plane of the drawing in the area of the throttle valve conduit (DKS), so that in this region the throttle valve shaft is perpendicular to the plane of the drawing.

The output signals of the actual value potentiometers (IG1) and (IG2), which are duplicated for reasons of redundancy, are conveyed to an electrical control appliance (STG), which controls the servomotor (M). Furthermore, the electrical control appliance (STG) receives as input signals the output signals of a first reference element (SG1) and of a second reference element (SG2), both of which are in the form of potentiometers. The use of two reference elements (SG1 and SG2) is likewise for reasons of redundancy.

The wipers of the potentiometers (SG1) and (SG2) are non-rotatably connected to a shaft which appears on the left in Fig. 1, and which has a cable disc (SS) non rotatably secured to its end directed away from the potentiometers (SG1) and (SG2). A control cable (S) runs over the cable disc (SS) and is connected at one end to the disc. The other end of the cable (S) is connected to an accelerator pedal (FP) which is arranged in the interior space of the motor vehicle for operation by the t, 11 vehicle driver.

The cable disc (SS) carries a first stop (A1), which cooperates with the lever (H). Furthermore, the cable disc butts against a second stop (A2) in the nondepressed position of the accelerator pedal (FP), which stop is connected, fixed in its position, to the throttle valve conduit (DKS).

The restoring force of a first return spring (F1) having one arm attached to the cable disc (SS) and its other arm fixed relative to the throttle valve conduit (DKS), acts on the left hand shaft in Fig. 1. The force of a second return spring (F2) having one arm attached to the throttle valve shaft and its other arm fixed in relation to the throttle valve conduit, acts on the throttle valve shaft on the right hand of Fig. 1.

A direction arrow (1) is indicated in Fig. 1, which denotes the direction of flow of the air flowing through the throttle valve conduit and into the motor vehicle engine. A direction arrow (2) indicates the swivelling direction of the throttle valve (DK) from a closed position during emergency running of the engine of the motor vehicle. The direction arrow (3) indicates the swivelling direction of the throttle valve from a closed position during electrical operation of the device the subject of the invention and therefore during normal operation of the motor vehicle. The direction arrow (4) indicates in which direction the biasing force of the second spring (F2) acts to rotate the throttle valve shaft 12 on the right in Fig. 1 and the direction arrow (5) indicates the direction of rotation in which the biasing force of the.first spring (F1) acts to rotate the left hand shaf-t in Fig. 1.

The device according to Fig. 1 functions in the following way.

Let it be assumed that the motor vehicle is stationary and the engine of the vehicle is idling. In this instance then, the-accelerator pedal (FP) is not depressed by the driver of the motor vehicle and the throttle valve (DK) is as far as possible in the fully closed position or idling position which is illustrated in Fig. 1. In this case, because the accelerator pedal (FP) is not depressed, the cable disc (SS) butts against the second stop (A2), because it is urged by the force of the first return spring (F1) against this stop.

At the same time, the reference elements (SG1) and (SG2) deliver to the control appliance (STG) an output signal which reflects the unloaded state of the accelerator pedal (FP). This is evaluated by the electrical control appliance (STG) in such a way that the electric servomotor (M) is not operated. That is to say, merely the restoring force of the second return spring (F2) acts upon the throttle valve shaft on the right in Fig. 1, which force is less than that of the first return spring (F1). This ensures that the throttle valve (DK) remains in the idling position and that the lever (H) butts against the first stop (1). This position of the 13 throttle valve is logged by the actual value transmitters (IG1) and (IG2) and reported back to the control appliance (STG), to eliminate control deviation in the system.

As soon as the driver of the motor vehicle depresses the accelerator pedal (FP), assuming the electrical adjusting device is functioning satisfactorily, the position of rotation of the cable disc (SS) alters in such a way that the left-hand shaft in Fig. 1 is turned counter to the direction of the force of the first spring (F1). This leads to the reference elements (SG1) and (SG2) delivering an appropriate representative setting signal to the electrical control appliance (STG), which immediately causes the electric servomotor (M) to turn the throttle valve shaft on the right in Fig. 1, counter to is the direction of the force of the second spring (F2), and thereby to open the throttle valve (DK) in the swivelling direction (3) for electrical operation.

As a result, the lever (H) rises from the stop (A1) of the cable disc (SS), while the cable disc and also the shaft on the left in Fig. 1 is turned in the opposite direction to the throttle valve shaft on the right in Fig. 1.

Because of these contra-rotating displacements, the mechanical connection between the accelerator pedal (FP) and the throttle valve (DK) is interrupted, because of the disconnection between the first stop (A1) and the lever (H). In this case, and therefore during normal operation of the device according to the invention, the 14 position of the throttle valve (DK) is dependent solely on the operation of the servomotor (M).

The position to which the throttle valve (DK) is moved in this state follows a predetermined relationship according to the position of the accelerator pedal (FP), this relationship being preset in the electrical control appliance (STG). Independently of this predetermined relationship, further functions can naturally be provided, in known manner, which control the electric servomotor (M) more or less independently of the accelerator position. The normal functional sequence of such an electrical accelerator pedal is illustrated, for example, in DEOS 27 14 113.

However, as soon as a fault occurs either in the reference elements (SG1 and SG2) or in the electrical control appliance (STG) or in the electric servomotor (M), the electrical adjusting device is disturbed and can no longer guarantee the functional sequence described. In this case, the electric servomotor (M) is usually no longer being operated. As a result, an adjustment of the throttle valve (DK) by the electrical adjusting device is no longer possible.

In this case, the emergency running function of the device comes into action, in such a way that when the accelerator pedal (FP) is pressed down, the cable disc (SS), as already described, is rotated via the cable control (S) counter to the direction (5) of the force of the first spring (F1). As.the electric servomotor (M) is T not operated in this case, the throttle valve shaft on the right in Fig. 1 is biased by the second spring (F2) in such a way that the lever (H) thereafter butts against the first stop (A1). That is to say, with the turning of the cable disc (SS) already described, the throttle valve shaft is also rotated, so that the throttle valve (DK) in this emergency function is opened in the swivelling direction (2) of the emergency running operation. With the release of the accelerator pedal (FP), because of the greater force of the first spring (F1) as compared with the second spring (F2), the cable disc (SS) returns to the second stop (A2) and the right hand throttle valve shaft in Fig. 1 is likewise rotated by the lever (H) in such a way that the throttle valve (DK) is rotated back into the idling position which is illustrated in Fig. 1.

At the same time, by a warning light (W) which is controlled by the electrical control appliance (STG), it can be indicated to the vehicle driver that the electrical adjusting device has been disturbed.

Independently of this, the adjusting range of the throttle valve (DK) in the swivelling direction for the emergency running operation (2) can be limited as compared with the swivelling direction (3) for the electrical operation, in such a way tha.t the driver can no longer demand full power from the motor vehicle engine.

From what has been described above, it will be clear that through the opposite orientation of the swivelling directions of the throttle valve (DK) in 16 emergency running operation (2) and in electrical operation (3), a comfortable emergency setting of the driving speed of the motor vehicle is possible even with a failure of the electrical adjusting device. For this, only the disconnection with the first stop (A1) and the lever (H) and the second readjusting spring (F2) is necessary.

In Fig. 2, it is now explained in greater detail how the quantity of air (m) flowing through the throttle valve conduit (DKS) is dependent upon the throttle valve angle (DK). It will be recognised that starting from the swivelling angle (0'), which corresponds to the idling position or fully closed position of the throttle valve (DK), if there is electrical operation (E) the throttle valve (DK) is swivelled in the direction (3) and it can be shifted to the throttle valve angle (90') corresponding to the fully opened vertical position of the throttle valve (DK) in Fig. 1. In this electrical operation (E), the full power of the motor vehicle can be demanded by use of the accelerator pedal (FP) and the electrical adjusting device. In this case, therefore, the air mass flow (ffi) can be controlled by the accelerator pedal (FP) from a minimum air mass flow (i MIN) to a maximum air mass flow MAX,E).

The minimum air mass flow (m MIN) arises from the fact that the throttle valve (DK) is mounted freely rotatable in the throttle valve conduit (DKS), so that in the horizontal position of the throttle valve (DK) as 17 illustrated in Fig. 1, a small mass of air can continue to flow through the throttle valve conduit (DKS).

If there is emergency running operation (N), the throttle valve (DK) can only be adjusted by the accelerator pedal (FP) in the swivelling direction (2) within the range from (0'), corresponding to the idling position of the throttle valve according to Fig. 1, to roughly (-45') corresponding to a half-opened position of the throttle valve (DK). This can be ensured by an appropriate transmission ratio through suitable choice of the size of the cable disc (SS) relative to the travel path of the accelerator pedal (FP). In this case, the air mass flow (r) can only be influenced within the range of the minimum mass flow (i MIN) to a maximum mass flow (n MAX,N), so that in this case the driver of the motor vehicle can only demand reduced power of the motor vehicle engine by means of the accelerator pedal.

As a result of these measures, the driver of the vehicle is not left unaware when the electrical adjusting device has faults which impede its proper functioning. On the other hand, the driver is fully in a position, with this emergency driving function, to behave appropriately in road traffic without constituting a traffic hazard and to reach the nearest vehicle workshop to repair the damage.

is 18

Claims

1. Device for adjusting the driving speed of a motor vehicle, operable through an accelerator pedal or the like for a throttle valve of the vehicle engine and comprising an electrical adjusting device for the throttle valve arranged to be controlled by the accelerator pedal and a disengageable mechanical connection for linking the accelerator pedal and the throttle valve, the electrical adjusting device being arranged to open the throttle valve in one direction of rotation and the mechanical connection being arranged- to open the throttle valve in the other direction of rotation, respective biasing means for urging the throttle valve towards an idling position acting upon the mechanical connection and upon the electrical adjusting device, said biasing means for the mechanical connection and the electrical adjusting device acting on the throttle valve in opposite directions.

2. Device for adjusting the driving speed of a motor vehicle through an accelerator pedal or the like and comprising a throttle valve of the vehicle engine which is arranged in a freely rotatable manner in a throttle valve conduit, an electrical adjusting device, controllable by the accelerator pedal, means for biasing the throttle valve towards an idling position of said valve and a disengageable mechanical connection between the accelerator pedal and the throttle valve, the electrical 19 adjusting device being arranged to open the throttle valve in one direction of rotation, and the mechanical connection being arranged to open the throttle valve in the opposite direction of rotation, said biasing means acting upon the mechanical connection, and that a second biasing means urging the throttle valve towards its idling position acting upon the electrical adjusting device in a direction counter to the first biasing means.

3. Device as claimed in claim 1 or claim 2, wherein said biasing means is provided by a return spring at least for one direction of bias.

4. Device as claimed in any one of claims 1 to 3, wherein the means for disengaging said mechanical connection comprises a stop connected to the accelerator pedal and a lever connected to the throttle valve.

5. Device as claimed in claim 4, wherein the accelerator pedal is connected via a control cable to a cable disc, which is provided with said stop.

6. Device as claimed in claim 5, wherein at least one electrical reference element is provided which is connected to the cable disc.

7. Device as claimed in any one of claims 4 to 6, wherein the first biasing means acts upon the stop.

8. Device as claimed in any one of claims 4 to 7, wherein a second stop is provided which limits adjustment of the throttle valve by the mechanical connection in the closing direction of the throttle valve to the fully closed position.

9. Device as claimed in claim 8, wherein the acting force of the first biasing means is greater than the acting force of the second biasing means.

10. Device as claimed in any one of the preceding claims, wherein the electrical adjusting device is arranged to open the throttle valve to approximately between the fully closed position and the fully opened position.

11. Device as claimed in any one of the preceding claims, wherein the mechanical connection is arranged to open the throttle valve to approximately between the fully closed position and a half-open position.

12. Device for adjusting the driving speed of a motor vehicle constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.

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