Background Art The speed limits prevailing on the roads aim at increasing road safety. Nevertheless it is common for vehicles to exceed the permissible speeds. It goes with- out saying that this is not satisfactory from the view- point of road safety.

For this reason, various systems have been developed to ensure that the prevailing speed limits are obeyed.

For example, German Published Application DE 19638900 discloses a system preferably for vehicles with diesel engines, said system comprising a speed limiting device which is activated in case a permissible speed is exceeded. The speed is adjusted by pressing an acce- lerator for controlling a pump for fuel injection to the engine. The speed limiting device is, on activation, arranged in such manner that, independently of the posi- tion of the accelerator, the pump adjusts the fuel injec- tion so that the speed of the vehicle does not exceed the permissible speed.

Moreover, German Published Application DE 2836342 discloses a system for vehicles, which system comprises a speed limiting device which, in case a permissible speed is exceeded, is activated in such manner that a coupling rod arranged between an accelerator and a

throttle is extended, thereby reducing the speed provid- ed by pressing down the accelerator. When the speed of the vehicle has been reduced to the necessary extent, the rod is retracted, whereby the speed of the vehicle can again be adjusted by operating the accelerator.

When these prior-art systems are activated, it is thus not possible to increase or even maintain the cur- rent speed, which of course in some cases can be disad- vantageous or even dangerous, such as in overhauling.

When the above-described prior-art systems for adjusting the speed of a vehicle to the permissible speed are activated, the driver thus loses his capability of controlling the speed. The driver's only way of avoiding this is to accurately observe on a speedometer the speed with which he drives his vehicle, and thereby ensure that this speed is at all times below the permissible speed.

A solution to this problem is disclosed in e. g.

DE 2444518. The described system comprises a means for returning the accelerator, said means being activated if a permissible speed is exceeded. The accelerator can, however, still be pressed down, which requires an extra effort. It will thus be possible to drive the vehicle at a speed above the permissible maximum speed. However, the accelerator will be difficult to operate, which probably means that the driver chooses to lower the speed of the vehicle for the accelerator again to be easily operated.

Also the system according to DE 2444518 relates to a system which is not activated until a permissible speed has been exceeded. Thus, there is a need for a system which can be used to better promote the adjustment of the speed of a vehicle, i. e. a system which helps to ensure that the current speed limits are obeyed.

Summary of the Invention A first object of the present invention thus is to provide an improved system for adjusting the speed of a vehicle. The system should be designed so that it can be used to adjust the speed of a vehicle to a currently pre-

vailing permissible maximum speed. More specifically, the system should promote such adaptation of the speed and at the same time allow driving of the vehicle at a speed exceeding the currently prevailing permissible maximum speed.

It is also advantageous if the system is designed in such manner that it draws the driver's attention to the speed which is the currently permissible maximum speed.

A second object of the present invention is to provide a device which can be arranged in a system for adjusting the speed of a vehicle, said device being designed so as to promote adaptation of the speed of the vehicle to the currently permissible maximum speed.

A third object of the present invention is to pro- vide an improved method for adjusting the speed of a vehicle, said method promoting adaptation of the speed of the vehicle to the permissible speed while the driver of the vehicle has the possibility of choosing to drive his vehicle at a speed exceeding the currently permis- sible maximum speed.

To achieve the first object, a system according to claim 1 is provided. Preferred embodiments of the system are defined in the dependent claims 2-18.

To achieve the second object, a control unit accord- ing to claim 19 is provided. A preferred embodiment of the control unit is defined in the dependent claim 20.

To achieve the third object, a method according to claim 21 is provided.

More specifically, according to the invention a speed adjusting system for vehicles is provided, compris- ing an accelerator, such as a throttle pedal, a speed adjusting means, such as a throttle or a fuel injection pump, which is adjustable by operating the accelerator, and a control unit which is connected to the accelerator and which is settable between a first operating position, in which the accelerator is operable without difficulty and a second operating position, in which the accelerator

is operable with difficulty, said system being char- acterised in that the second operating position is a basic state of the control unit, the difficulty, with which the accelerator is operable when the control unit is arranged in said basic state, appearing as a resis- tance which is generated by the control unit and acting on the accelerator and which must be overcome for operat- ing the accelerator and which clearly exceeds the resis- tance that exists for operating a conventional accelera- tor, and that the control unit comprises a drive means, the drive means, on activation, being adapted to counter- act said resistance, which control unit will thus be arranged in its first operating position through activa- tion of the drive means.

Thus a system is provided, which can be used to promote adaptation of the speed of the vehicle so that a permissible maximum speed is not exceeded while the driver of the vehicle always has the possibility of driving his vehicle at the desired speed.

The control unit is suitably arranged in its first operating position for driving the vehicle at a speed which is lower than or corresponds to a currently pre- vailing permissible maximum speed and in its second ope- rating position when exceeding said permissible maximum speed. Thus, a system is provided, which when exceeding a permissible maximum speed makes the accelerator difficult to operate. The driver can choose either to reduce the speed, in which case the control unit is arranged in its first operating position when the speed falls below the permissible speed-which makes the accelerator once more easy to operate-or to maintain or even increase the speed, in which case the control unit will remain in its second operating position-whereby the accelerator remains difficult to operate. The system thus is satis- factory in terms of road safety since the driver all the time keeps control of the vehicle. At the same time it is, of course, most favourable for the driver to drive

the vehicle at a permissible speed since this makes the accelerator easier to operate.

A particularly advantageous effect obtained in the inventive system is that the driver's attention is at all times attracted to the speed which is the permissible maximum speed. This is achieved by the driver, when ope- rating the accelerator, senses a final position of the accelerator, in which final position the throttle pedal will be stiff to operate. It will thus be extremely simple for the driver to drive the vehicle at the permis- sible speed by always seeing to it that the accelerator is never moved past said final position. The final posi- tion is provided by the drive means, which in the first operating position of the control unit counteracts the resistance acting on the accelerator. Thus the drive means will assist in operating the accelerator as long as the control unit is arranged in its first operating position. This assistance ceases immediately when the control unit is arranged in its second operating posi- tion, which, as mentioned above, suitably corresponds to the driving of the vehicle at a speed exceeding the per- missible maximum speed. Operation of the accelerator with assistance is thus allowed to a certain extent. Continued operation thus occurs without assistance and requires an increased effort. Consequently the permissible maximum speed will be clearly perceptible to the driver in the form of a final position when operating the accelerator.

The inventive system will also be extremely reliable and safe. In case of damage or malfunction in the system, the only consequence will be that the control unit is arranged in its non-activated basic state corresponding to the second operating position. The accelerator will thus be difficult to operate in case of malfunction. This eliminates the risk of locking the accelerator to a non- desirable extent.

Preferably, the control unit is arranged for gradual setting from one of the first and the second operating

position to the other of the first and the second operat- ing position.

Preferably the system comprises a controller, which is adapted to receive information about the speed of the vehicle and the current speed-limit regulations from a monitoring system; and to control the control unit on the basis of the information received from the monitor- ing system.

According to a preferred embodiment of the system, the control unit is also connected to the speed adjusting means, the control unit being arranged in such manner that the speed adjusting means is adjustable via the con- trol unit by operating the accelerator.

Preferred embodiments of the control unit of the system are defined in the dependent claims.

The features stated in the dependent claims can, of course, be combined in an optional manner.

Moreover, according to the present invention, a control unit is provided for adjusting the speed of a vehicle, comprising a first arm turnable by means of an accelerator, a second turnable arm, and a third arm turn- able with the aid of a drive means, said first arm being spring loaded in such manner that, for turning thereof, a first force must be applied thereto, and said second arm being spring loaded in such manner that, for turning thereof, a second force must be applied thereto, the first arm, after turning through an angle, being arrang- ed for engagement with and co-turning of the second arm, whereby, for turning of the second arm by operating the accelerator, this must be operated by applying a force corresponding to the sum of the first force and the second force, the third arm, on turning, being arranged for engagement with and co-turning of the second arm and the drive means, on activation, being arranged for such turning of the third arm and, thus, also of the second arm that the angle between the first arm and the second arm is maintained upon turning of the first arm.

As a result a control unit is provided, which is extremely suitable for use in a system according to the present invention. When the drive means is activated, a turning, caused by e. g. a throttle pedal, of the first arm will cause a suitable turning of the second arm for maintaining the angle between the arms. The first arm will thus not engage with the second arm, whereby the throttle pedal need only be operated with the first force for adjusting the speed. When the drive means is switched off or deactivated, said angle will not be maintained, and thus the throttle pedal must be subjected to a force corresponding to the sum of the first and the second force. By seeing to it that this sum is sufficient, it is possible to ensure that the operation of the throttle pedal will be difficult. It is thus suitable to arrange the control unit in such manner that it is switched off in case the speed is exceeded, thereby promoting driving of the vehicle at a permissible speed.

The second arm of the control unit can be connected with a speed adjusting means, whereby the speed adjusting means can be adjusted by turning of the second arm.

Finally, according to the present invention a method is provided for controlling the speed of a vehicle, com- prising the steps of arranging an accelerator in such manner that it can only be operated with difficulty to adjust a speed adjusting means, counteracting, by means of a control unit, said difficulty to such an extent that it is essentially eliminated, and ceasing, if the vehicle is driven at a speed exceeding a currently prevailing permissible maximum speed, to counteract said difficulty, whereby the exceeding of the speed is made evident to the driver of the vehicle in such manner that the accelerator can be operated only with difficulty to adjust the speed adjusting means.

Preferred embodiments of the invention will now be described in more detail with reference to the accompany- ing drawings.

Brief Description of the Drawings Fig. 1 is a schematic view of a system according to the invention.

Fig. 2 is a side view of a first embodiment of a control unit for the inventive system.

Fig. 3 is a top plan view of the control unit shown in Fig. 2.

Fig. 4 is a side view of a second embodiment of a control unit for the inventive system.

Fig. 5 is a top plan view of the control unit shown in Fig. 4.

Description of Embodiments Fig. 1 shows schematically the composition of a sys- tem according to a preferred embodiment of the present invention.

The system, which is intended to be arranged in a powered vehicle such as a car, comprises a control unit 3 connected between an accelerator, such as a throttle pedal 1, and a gas adjusting means, such as a throttle 2. The throttle pedal 1 is more specifically connected to the control unit 3 via a first connecting means in the form of a first wire 4 and the throttle 2 is connected to the control unit 3 via a second connecting means in the form of a second wire 5.

A first transducer means in the form of a transducer 6 of electromagnetic type acting in a contactless manner is arranged adjacent to the control unit 3 for reading an angular position which is provided by means of the throttle pedal 1 and corresponds to the desired adjust- ment of the speed. Moreover, a second transducer means in the form of a transducer 7 of electromagnetic type acting in a contactless manner is arranged adjacent to the throttle 2 for reading its angular position corre- sponding to the actual speed adjustment.

Finally, a controller 8 is arranged for controlling the control unit 3 in the manner described below. The

controller 8 is also adapted to receive information about the speed of the vehicle and the prevailing speed limits from a monitoring system 9.

The control unit 3, which will be described more clearly below, is settable between a first and a second operating position.

The first operating position, which is taken on activation of the control unit 3, is arranged in such manner that the degree of opening of the throttle 2 can easily be controlled by operating the throttle pedal 1.

More specifically, the throttle pedal 1 need only be operated with a force necessary for operating a conven- tional throttle pedal, normally 30-50 N.

The second operating position, which is taken when the control unit 3 is not activated and which thus constitutes the basic state of the control unit 3, is arranged in such manner that the degree of opening of the throttle 2 can only with difficulty be adjusted by operating the throttle pedal 1. When the control unit 3 is arranged in this second operating position, it is thus difficult for the driver of the vehicle to increase the speed. The required force can be varied in the range 80-120 N.

The control unit 3 is thus arranged in such manner that it assists the operation of the throttle pedal 1 when said control unit 3 is arranged in its first ope- rating position and does not assist said operation when it is arranged in its second operating position.

In a vehicle equipped with such an inventive sys- tem, the controller 8 thus receives relevant information regarding the speed of the vehicle and the prevailing speed limits from the monitoring system 9. If the speed of the vehicle is below the permissible speed, the con- troller 8 activates the control unit 3, which is thus arranged in its first operating position, in which the throttle pedal 1 can be operated without difficulty for adjusting the opening degree of the throttle 2. Should

the vehicle be driven at a speed exceeding the permis- sible speed, the controller 8 switches off or deactivates the control unit 3, whereby the driver's attention is attracted to the exceeding of the speed by the throttle pedal 1 being difficult to operate. Then the driver may choose either to continue to drive the vehicle at an impermissible speed-although with difficulty since the throttle pedal 1 is then difficult to operate-or to release the throttle pedal 1 until the permissible speed is not exceeded, whereby the control unit 3 is again activated by the controller 8 and the throttle pedal 1 will be easy to operate.

It should, however, be noted that the inventive system promotes the driving of the vehicle at a speed below the permissible maximum speed in such a manner that the speed limit need never be exceeded. In fact the system works in such manner that the driver continuous- ly via the throttle pedal 1 senses the permissible maxi- mum speed. When operating the throttle pedal 1, the driver will in fact feel a pressure point or a"final position"when pressing the throttle pedal 1. This"final position"corresponds to the adjustment of the speed which corresponds to the permissible maximum speed. In this final position, the control unit 3 thus ceases to assist the operation of the throttle pedal 1. In other words, the driver will feel"the law in the throttle pedal"which promotes the driving of the vehicle at a speed that never exceeds the permissible maximum speed.

The control unit is preferably arranged for gradual passing between the two operating positions.

The above-mentioned monitoring system 9 may consist of, for example, a GPS-based satellite monitoring system which supplies information about the speed of the vehicle and the prevailing speed limit regulations to a receiver unit (not shown) in the controller 8, or of transmitters, which are mounted along the road and which supply infor- mation about the prevailing speed limit regulations to a

similar receiver unit in the controller 8 of the vehicle.

In the latter case, the vehicle also comprises equipment for determining the speed with which the vehicle is driven.

A first preferred embodiment, which is shown in Figs 2 and 3 and to which reference is now made, of a control unit 3 according to the present invention com- prises essentially three arms 10,11,12 and a drive means in the form of an electric motor 13.

A holder 15 fixed to a frame 14 supports a shaft 16 in which the first arm 10 is turnably mounted. The first arm 10 is in a fixing point 17 connected to the throttle pedal 1 by means of a first wire 4, as shown in Fig. 1.

Said first arm 10 is spring loaded (not shown) in such manner that for turning thereof the throttle pedal 1 must be pressed down by applying a force corresponding to the force required for pressing down a conventional throttle pedal.

Also the second arm 11 is turnably mounted in the shaft 16. The second arm 11 is in a fixing point 18 con- nected to the throttle 2 by means of a second wire 5, as shown in Fig. 1, and is spring loaded (not shown) in such manner that for turning thereof a force must be applied thereto, which corresponds to or exceeds the force that is required for pressing down a conventional throttle pedal. The second arm 11 extends parallel with and under the first arm 10, which is evident from Fig. 2, and with a certain angular displacement a thereto, which is evi- dent from Fig. 3. The second arm 11 further supports a lug 19 which extends upwards. The first arm 10 will, when turning about the shaft 16, by pressing down of the throttle pedal 1, after a certain degree of turning cor- responding to said angular displacement a, engage with the lug 19 and thus turn along the second arm 11.

It is thus possible to control the degree of open- ing of the throttle 2 by operating the throttle pedal 1.

However it should be noted that in this case the throttle

pedal 1 must be operated with a force that clearly exceeds the force required for operating a conventional throttle pedal, which thus depends on the fact that for turning the second arm 11 it is necessary to operate the throttle pedal 1 by applying the force that is required for jointly turning the first arm 10 and the second arm 11.

The electric motor 13, which is mounted in the frame 14, has a motor shaft 20, on which the third arm 12 is arranged. The third arm 12 is turnable by means of the motor 13 and extends under and parallel with the second arm 11.

The motor shaft 20 is concentrically arranged under the first shaft 16, whereby all arms 10,11,12 are turn- ed about a common axis. A lug 21 is arranged on the third arm 12 and, on turning of the third arm 13, engages with and turns along the second arm 11. The degree of opening of the throttle 2 can thus be controlled by means of the motor 13.

The control unit 3 further comprises a transducer 6, which is adapted to read the angular position of the first arm 10.

When an inventive system comprising a control unit 3 in accordance with this first embodiment is arranged in a vehicle, the system operates as follows.

As long as the vehicle is driven with a speed below the permissible speed, which information as described above is transferred to the controller 8 from the moni- toring system 9, the controller 8 provides for the elec- tric motor 13 to be activated, whereby the control unit 3 thus takes its first operating position. A pressing-down of the throttle pedal 1 will cause a turning of the first arm 10, said turning being read as a desired value by the first transducer 6. The desired value, which thus indi- cates the desired adjustment of the speed, is transferred to the controller 8. A second transducer 7, which as shown in Fig. 1 is arranged adjacent to the throttle 2

reads the angular position of the throttle 2, which thus represents an actual value corresponding to the actual degree of opening of the throttle 2. It will be appre- ciated that said transducer 7 can be replaced by some other means, such as a pulse counter, which establishes the angular position of the electric motor 13, i. e. the turning of the second arm, which in turn controls the actual adjustment of the speed. Also the actual value is transferred to the controller 8, which compares the two values. The controller 8 then controls the motor 13 in such a way that it turns the third arm 12 and, thus, also the second arm 11 for adjusting the degree of opening of the throttle 2. When the actual value conforms with the desired value, the motor 13 interrupts the adjusting of the degree of opening of the throttle 2. It is conse- quently ensured that the angular displacement a between the first 10 and the second arm 11 is maintained. This ensures that the first arm 10, during turning, does not engage with the lug 19 of the second arm 11, and conse- quently the throttle pedal 1 need not be subjected to a force corresponding to the force required for turning the second arm 11. When driving the vehicle with a permis- sible speed, the driver of the vehicle will consequently not experience any difficulties whatever in operating the throttle pedal 1 since the adjustment of the degree of opening of the throttle 2-i. e. the turning of the second arm 11-is assisted by the electric motor 13.

If the speed of the vehicle exceeds the permissible speed, the controller 8 is adapted to deactivate the electric motor 13. In other words, the assistance provid- ed by the electric motor 13 for adjusting the degree of opening of the throttle 2 will cease.

When the electric motor 1 is deactivated, the third arm 12 is adapted to return to a starting position, in which no adjustment of the speed is obtained. The second arm 11 will, as a consequence of its spring load, strive to return to the same starting position. The lug 19 sup-

ported by the second arm 11 will thus engage with the first arm 10 during this return motion. The driver will notice this as a resistance that is applied to the throttle pedal 1. The driver may choose either to release the throttle pedal 1, whereby the increase of the speed is throttled and the speed of the vehicle decreases, or to maintain or even increase the speed. In the latter case, the driver must operate the throttle pedal 1 by applying a force clearly exceeding the force required for operating a conventional throttle pedal. The driver will of course find this inconvenient, which means that in the normal case he will probably choose to lower the speed of the vehicle by releasing the throttle pedal 1. However, it is important to note that the driver can all the time choose how to proceed. There are in fact opportunities when it may be necessary to drive the vehicle with a non- permissible speed, such as in overhauling.

If the driver chooses to release the throttle pedal 1, the controller 8, as soon as the speed of the vehicle has been adjusted to the permissible speed, will once more activate the electric motor 13, whereby the adjust- ment of the speed will again be assisted by the electric motor and consequently be comfortable to the driver.

It is worth noticing once more that the inventive system promotes the adaptation of the speed in such a manner that the permissible maximum speed need not be exceeded. As soon as the drive means in the form of the electric motor 13 is deactivated, the assistance provided by the electric motor 13 ceases. The operation of the throttle pedal 1 is thus to a certain extent allowed with assistance and, to an increased extent, without assis- tance. The limit position is very distinct. Immediately as the electric motor 13 is deactivated the assistance ceases. The driver will thus clearly feel in the throttle pedal 1 the position in which the assistance ceases. This results in a final position corresponding to the per- missible maximum increase of the speed for driving the

vehicle with the permissible maximum speed. To drive the vehicle at a speed not exceeding the permissible maximum speed, the driver can consequently operate the throttle pedal 1 so as to move it to said final position. The force with which the driver operates the throttle pedal 1 is thus adjusted so as not to exceed the force requir- ed to move the throttle pedal 1 past said final position.

The driver can then maintain the throttle pedal in said final position. The place of the final position may thus be changed depending on the road conditions. When driv- ing uphill, an increased speed adjustment, i. e. further pressing of the throttle pedal, is required to maintain the same speed. The final position will thus be changed to allow the throttle pedal to be pressed, which means that throttle pedal 1 and thus also the driver's foot will automatically come along to the new final position.

The inverse condition applies when driving the vehicle downhill. The final position will be moved in order to accomplish a reduced speed adjustment, i. e. release of the throttle pedal, whereby the throttle pedal 1 and the driver's foot once more come along.

As is evident from Fig. 3, the first wire 4 is con- nected to the control unit 3 from a first side while the second wire 5 is connected to the control unit 3 from a second, opposite side. It may, however, in some cases be desirable for both wires 4,5 to be connected to the control unit 3 from one and the same side. The second preferred embodiment of the control unit 3 shown in Figs 4 and 5 allows such a connection of the wires 4,5.

Also this embodiment comprises essentially three arms 110,111,112 and an electric motor 113, which are all mounted on a base plate 122.

The electric motor 113 is mounted on the underside 123 of the base plate 122 and comprises a motor shaft 120 which extends up through an opening 124 in the base plate 122.

The first arm 110 is turnably mounted in a first shaft 125 which is arranged on the upper side 126 of the base plate 122. The first arm 110 further comprises a curved portion 127, which is arranged outside the posi- tion, in which the motor shaft 120 projects on the upper side 126 of the base plate 122. A long hole 129 is formed at one end 128 of the first arm 110 for fixing the first wire 4. An engaging means in the form of an oval ring 131 is arranged at the opposite end 130 of the arm 110.

The second arm 111 is at one end 132 turnably mount- ed in a second shaft 133 which is concentric with the motor shaft 120. Also the second arm 111 has a long hole 134 for fixing the second wire 5. Finally, an engaging means in the form of a downwardly extending pin 119 is arranged at the other end 135 of the arm 111. This pin 119 is arranged inside the ring 131 of the first arm 110.

The motor shaft 120 supports the third arm 112, which in turn supports a lug 121. The third arm 112 is turnable by means of the electric motor 113.

As is evident especially from Fig. 4, the two wires 4,5 are connected to the respective arms 110,111 on the same side of the control unit 3, which may be advan- tageous from the viewpoint of mounting in some cases. The long holes 129,134 allow satisfactory setting of the desired turning.

When turning the first arm 110, its oval ring 131 will, after a certain degree of turning, engage with the pin 119 of the second arm 111, which is thus turned along with the first arm 110. The first 110 and the second 111 arm are spring loaded in the same manner as described with reference to the first embodiment of the control unit 3.

By means of the electric motor 113, the third arm 112 will be turned, whereby its lug 121 engages with the second arm 111 and thus turns along the second arm 111.

The control unit 3 according to this second embodi- ment is thus adapted to act in essentially the same man-

ner as in the first embodiment of the control unit 3. The essential difference is that the wires 4,5 are connected to the control unit 3 on the same side thereof. Moreover it is possible to exchange the turning of the second arm 111. In the example shown, an essentially 90 degree turn- ing of the first arm 110 (said turning being effected by pressing down the throttle pedal 1) causes an essentially 120 degree turning of the second arm 111. The final posi- tions of the first arm 110 are indicated by dashed lines.

This exchange is advantageous since the angular position through which the throttle pedal 1 is operable normally does not conform with the angular range through which the throttle 2 is adjustable.

A system is thus provided, which promotes driving of a vehicle with a permissible speed where the driver of the vehicle may nevertheless choose to drive the vehicle with a non-permissible speed if he desires so.

A developed road system which has a monitoring sys- tem and in which all vehicles have the inventive system for adjusting the speed can be used for efficient control of the traffic. If the monitoring system, for example, discovers a queue along a certain distance where the vehicles have come to a halt in several lanes, the sys- tem can reduce the permissible maximum speed a distance before said distance so that the queue has disappeared before vehicles behind said queue have reached the same.

This means that vehicles coming from behind do not have to stop, which is advantageous in environmental terms and also accelerates the dissolving of the queue. In fact the number of passing vehicles will be greater if the vehicles move continuously than in the case where every vehicle is forced to come to a halt repeatedly.

It will be appreciated that the present invention is not restricted to the embodiments illustrated.

The inventive system is, for example, possible to use in vehicles which do not comprise a speed adjusting means in the form of a throttle. Consequently it is

possible to use, for example, the inventive system in vehicles with injection engines.

Nor is it necessary to connect the control unit to the speed adjusting means for adjusting the speed. In particular it is possible to adjust the speed by detect- ing the desired adjustment of the speed indicated by means of the accelerator and then, with a separate device, adjust the actual adjustment of the speed in the gas adjusting means in correspondence with the desired adjustment of the speed. The control unit is thus not used to adjust the speed. With reference to Figs 2 and 3, this is achieved most easily by the second arm 11 of the control unit 3 not being connected to the speed adjust- ing means 2. While driving the vehicle at a permissible speed, the electric motor 13 thus ensures that the first arm 10 when operating the throttle pedal 1 does not engage with the second arm 11, i. e. that the angle a between the first arm 10 and the second arm 11 is main- tained. Should the permissible speed be exceeded, the electric motor 13 will be switched off, and it is thus not ensured that the angle a is maintained, which causes the first arm 10 to engage with the second arm 11, thus making it difficult to operate the throttle pedal 1. The turning of the second arm 11 is in this case thus not used to perform the adjustment of the speed adjusting means 2.

It is also possible to modify the control unit so that the second arm is turnable for increasing the speed independently of the first arm if the first arm is arranged in a non-actuated position, as shown in Figs 2 and 3. In the embodiment illustrated in Figs 4 and 5, this is achieved by designed the ring 131 so that it is not closed, but has a discontinuity, which allows the pin 119 to be removed from the ring during turning of the second arm for increasing the speed. This makes it pos- sible to use the electric motor in the control unit as cruise control.

Consequently several modifications and variations are thus possible and the scope of the invention is thus only defined by the accompanying claims.