DE3127301C2 - "Propulsion control device for a vehicle that is also equipped with an anti-lock braking system. - Google Patents

Abstract

For vehicles that are equipped with a 4-channel anti-lock braking system, a design of a propulsion control device is specified which, including the safety device required for its function monitoring, provides a combined implementation of an effective propulsion control and anti-lock braking control on the vehicle with only little additional effort compared to an anti-lock braking system enables. The basic structure of a propulsion control device integrated with the anti-lock braking system according to the invention is shown. According to this, the wheel speed sensors provided as part of the anti-lock braking system and the brake pressure control valves of the driven vehicle wheels and its return pump, as well as the signal input stage of the anti-lock braking system that receives the output signals of the wheel speed sensors, are appropriately used within the framework of the propulsion control device. The safety circuits of the anti-lock braking system or the propulsion control device are designed in such a way that, in the event of a malfunction in the anti-lock braking system, the propulsion control device is also switched off, while in the event of a malfunction of the latter, only this is switched off.

Description

The invention is based on a propulsion control device for a vehicle, which is also equipped with an anti-lock braking system (ABS) with the other, im The preamble of claim 1 features mentioned.

This generic combination of features corresponds to one made by the applicant in-house Test vehicles realized the state of technical development. One is combined with an ABS Propulsion control device (VR) assumed, which - assuming a driven axle on the vehicle - works on the principle that the drive wheel that tends to spin by actuating its To decelerate the wheel brake again and, if both drive wheels have too high a slip, one To trigger a reduction in the output torque of the drive unit, with wheel speed sensors and brake pressure control valves provided for the ABS in the Frame of the VR are also exploited; In the control phases of the VR, the pressure is supplied to the wheel brake to be applied ^) from an auxiliary pressure source, which must be designed so that it can provide a sufficiently high outlet pressure. To that extent is one with an ABS combined VR described in a now published (DE-OS 30 21 116) earlier patent application. In addition, the generic term of the Claim 1 on details of the electronic control unit of the ABS and the VR and on a das ABS monitoring safety circuit referred to, according to the aforementioned, internal technical level of development

A combined implementation of a drive control device and an ABS as explained above on a vehicle has the advantage that essential components of the ABS under the Propulsion control device can also be used and, in so far, an inexpensive, simple overall structure can be achieved; However, it is disadvantageous that then in one Fault in the propulsion control device or the ABS

the functionality of the other control device can be impaired, which is for safety reasons would be extremely unfavorable. It therefore appears more expedient to use the propulsion control device and the ABS functionally and structurally from one another, at least to the extent of their electronic control units to be separated in order to at least exclude mutual disturbances of the two control devices, but this in turn would be associated with an increased technical effort.

The object of the invention is therefore to provide a propulsion control device combined with an ABS from the above specify the type mentioned including a safety circuit that can be implemented with a simple structure, in the event of malfunctions of these control devices (VR and / or ABS) their automatic, im Carries out joint shutdown if necessary.

This object is achieved by the features A to mentioned in the characterizing part of claim I E solved.

The technical advantages achieved in this way are at least the following:

By jointly using a signal input stage, from the signals received from the wheel speed sensors both in the context of the VR as The ABS control units can also process speed, acceleration or deceleration proportions Generated signals, a favorable simple overall structure of these control units and through the function-specific processing of these characteristic of the state of motion of the vehicle wheels Signals in separate comparison and linking stages still largely decouple the two Control units achieved. Since the safety circuit provided for monitoring the ABS in the event of a malfunction the same also performs a shutdown of the propulsion control device, it is sufficient if their Safety circuit only on monitoring of the functional units connected downstream of the signal input stage the VR control unit is designed, whereby the for the safety circuit of the propulsion control device required effort also remains low. The for an incident of the Propulsion control device provided separate shutdown of the same and for a malfunction of the ABS intended common shutdown of the same with the propulsion control device are for driving safety This is an advantage, since in the former case the ABS safety reserve remains available and in the second case, d. H. if the ABS has failed, at least it is avoided that by a maintenance of the VR function, z. B. by that the vehicle is able to accelerate well even in poor road conditions, in a short time one Fahrsituaticn can arise that can no longer be controlled without the safety reserve of the ABS

Of course, individual assemblies are already known. For example, it is part of the status of the Technology in a vehicle brake system that evaluates the signals by means of a microcomputer undertakes to gain control signals for the ABS to use a test circuit. She's monitoring them Control system in active and passive state; should an error occur, the monitoring computer switches off the blocking protection from (DE-OS29 28 981).

DE-OS 27 56 192 describes a propulsion control device for the wheel speed and wheel acceleration signals in an electronic control unit

advises to be formed and evaluated. If a wheel spins, a wheel is assigned to this wheel Solenoid valve activated and the wheel brake applied. There is no anti-lock braking system here intended.

In DE-AS 18 06 671 it is recommended that the spinning wheel by applying its brake to brake and if both wheels spin to reduce the drive torque of the internal combustion engine.

The problem addressed by the invention of the interaction of the two safety circuits is not addressed in any of these publications.

By the features of claim 2, a subunit of the safety circuit is characterized by its function, which can be implemented in a simple manner according to the features of claim 3 and with a simultaneous occurrence of a signal that indicates a working phase of the propulsion control device, Hie. contradicts an operating state of the vehicle brought about by the driver (e.g. idling), the propulsion control device switches off, which works incorrectly in such a case.

By one with regard to its function by the features of claim 4, in a special embodiment further sub-unit of the safety circuit characterized by those of claim 5 achieves that a reduction in the output torque d '.' s drive unit of the vehicle only then can be triggered if, in an active phase of the propulsion control device, at least one of the brakes of the driven vehicle wheels is activated.

The functional and structural features of a third sub-unit of the VR safety circuit specified, which is a malfunction signal mediating the shutdown of the auxiliary pressure source generated when at least one of the wheel brakes of the driven vehicle wheels Brake pressure increases, although neither the driving brake is applied nor the propulsion control device is activated is. Such a malfunction can e.g. B. by leaks in the hydraulic system of the propulsion control device appear. It is therefore advantageous if the control option mentioned in claim 8 the brake pressure control valves in the sense of a pressure reduction within the scope of the safety device is provided.

By a time monitoring of control output signals of the propulsion control device and of signals that are characteristic of a critical state of motion, in particular of the driven vehicle wheels, a shutdown of the propulsion control device is triggered if such signals are longer than for a A comparison time period Δ t compatible with the physical constraints is available and thus additional security is achieved

The design of the propulsion control device according to the features of claim 10 is for the In the event of a malfunction of the propulsion control device and / or activation of the anti-lock device a redundancy of the shutdown of the propulsion control device, which is advantageous for safety reasons, is achieved and guarantees that this cannot take effect in an inadmissible manner.

In the by the features of claim 11 specified design of the propulsion control device, this can be done in a simple manner by control

a control valve assembly are switched off. In this design the propulsion control device is by means of a separating piston acting as a pressure intensifier also achieved that one on the vehicle, for. B. in Framework of a level control or servo device available pressure source as an auxiliary pressure source for the propulsion control device can be used and through this Mehrfach.iusniitzung the structural effort for the advance control device further reduced. n

It should be added that in this embodiment of the hydraulic circuit of the propulsion control system functional analogue also provided in connection with the anti-lock braking system to the braking pressure reduction recirculating pump for the propulsion control device competi- '~> uses can be. Through the pressure booster, the separating piston of which is floatingly mounted, so that, under the influence of the pressure prevailing in the brake line, when the auxiliary pressure source is switched off, it automatically returns to its basic position - ^!! easily achieved the hydraulic decoupling of the propulsion control device from the anti-lock braking system, so that z. B. an error in the pressure supply of the propulsion control device can not affect the functionality of the anti-lock braking system ^.

A test device suitable for the purpose of checking the function of the evaluation circuit of the propulsion control device, which z. B. can be activated by switching on the ignition and automatically mediates the above Ver.ving within a><> limited test period, its basic structure is indicated by the features of claim 12. This test device is a function of the VR safety circuit> not only in the ^r recommissioning the vehicle propulsion control system checks the functionality, but also monitored during driving their reliability.

The invention is described in more detail using a preferred exemplary embodiment. It shows

F i g. 1 is a block diagram of a propulsion control device combined with an anti-lock braking system according to the invention, in a greatly simplified representation,

F i g. 2 Details of the structure of the generation of the control signals for the brake pressure control valves the anti-lock braking system (ABS) and the propulsion control device (VR) provided electronic control units, and

F i g. 3 Details of one in the context of the advance control device according to FIGS. 1 and 2 provided function monitoring and safety circuit.

1, to the details of which reference is expressly made, shows the example of a motor vehicle with rear axle drive one with a four-channel anti-lock braking system provided on the vehicle structurally and functionally combined propulsion control device 10, for the implementation of which the overall with 11 designated anti-lock braking system components provided with largely utilized in order to achieve the simplest possible construction of the overall system.

The propulsion control device 10 is connected to the antilock braking system 11, which can be assumed to be known adapted so that it can be created as an additional device.

The anti-lock braking system 11 does not include one of the driven front wheels 12 and 13 or the

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⁶⁵ driven rear wheels 14 and 16 of the vehicle associated wheel speed sensors 17 and 18 or 19 and 21, which generate pulse-shaped electrical output signals whose frequency is proportional to the respective wheel speeds of the front wheels 12 and 13 and the rear wheels 14 and 16. An intended for the anti-lock braking system 11, generally designated 22 control electronics processes the output signals of the wheel speed sensors 17, 18, 19 and 21 to electrical control output signals with which the brake pressure control valves 23, 24, 26 and 27 in the sense of the intended anti-lock control in one of the Pressure build-up, pressure holding or pressure reduction phase in the wheel brakes 28, 29, 31 and 32 corresponding to the base (passage), blocking or discharge position can be controlled. The control electronics 22 also generate an output signal for activating the return pump 33 of the anti-lock braking system 11, which feeds SfciTiäiiüääigkcii flowing out of the wheel brake cylinders during the pressure reduction phases back into the BrciTiSiciiüngcfi 34 and 36 of the front axle or rear axle brake circuit.

To monitor the functioning of the anti-lock braking system 11 is a ». \ BS security circuit37 provided, the in the event of a malfunction of the control electronics 22 and / or other monitored components at their output

38 issues a su .ial stating that the Anti-lock braking system 11 triggers and a warning display

39 controls.

The propulsion control device 10, which is in driving mode an optimal transmission of the output torque delivered by the drive unit of the vehicle to convey additional driving safety, works according to the following principle:

As soon as one of the driven wheels 14 or 16 tends to spin, its wheel brake 31 or 32 is activated actuated. If both driven wheels 14 and 16 tend to spin, this is done in addition to activation the wheel brakes 31 and 32 a torque-reducing intervention in the drive unit, z. B. at a carburettor engine through electrically controlled adjustment of the throttle valve (»Ε-gas«). About that It is also assumed that the propulsion control device 10, as soon as defined threshold values of the Vehicle speed as well as the longitudinal and / or transverse acceleration effective on the vehicle are exceeded triggers the torque-reducing intervention in the drive unit if only one of the driven wheels 14 or 16 tends to spin

For regulating the brake pressure in the rear wheel brakes 31 and 32 are the brake pressure Rf 5i \ ntile 26 and 27 of the propulsion control device 10 Anti-lock braking system 11 used

In terms of propulsion control for driving situation-appropriate control of the brake pressure control valves 26 and 27 required control signals are designated by a total of 40 VR control electronics are generated, which these control signals also from a using the Fig.2 in more detail explanatory processing of the speed-proportional output signals of the wheel speed sensors 17, 18, 19 and 21 generated During the active phases of the propulsion control device 10, the brake pressure supply is of the wheel brakes 31 and 32 derived from an auxiliary pressure source designated as a whole by 41 41 is expediently an existing one on the vehicle, e.g. for a servo device

III

Pressure source used, the output pressure of which can be controlled by the VR control electronics Switching valve arrangement 42 in a secondary side coupled to the brake line 34 of the rear axle brake circuit Pressure booster 43 can be coupled in, which is used to adapt the pressure level to that for the propulsion control required value is provided. The pressure booster 43 has a floating mount Piston 44, the secondary-side piston step 46 of which has a Inlet pressure chamber 47 is limited, that of the outlet pressure chamber associated with the rear axle brake circuit of the master cylinder is connected in a communicating manner and via one in the basic position shown of the pressure booster piston 44 open, otherwise closed central valve 49 with the outlet pressure chamber 51 of the pressure booster 43 communicates. This design of the pressure booster 43 is thus also achieved the hydraulic decoupling of the auxiliary pressure source 41 from the master cylinder 48, which for the independent function of the propulsion Regeieinrichiung 10 and the anti-lock braking system is required.

In the following, in connection with FIGS. 2 and 3, the details of which are also expressly referred to be, in detail on the structure of the control electronics 22 and 40 of the anti-lock braking system 11 and the Propulsion control device 10 and the one provided for monitoring the functioning of the entire system 10, 11 Safety circuits 37 and 52 are received, which switch off the anti-lock braking system in the event of a malfunction 11 and / or the propulsion control device 10 mediate.

The control electronics 22 and 40 of the anti-lock braking system 11 and the propulsion control device 10 have a common signal input and processing stage 53, the speed sensor output signals as the input signal are forwarded. From this the signal input stage generates a total of eight output signals, those for the circumferential speed and the circumferential acceleration of one of the vehicle wheels 12, 13 and 16 are characteristic.

In the indexing of these output signals given in the drawing and other signals derived from them, the following assignment is assumed: V = front, H = rear, L = left, R = right and F = vehicle.

The output signals of the signal processing stage 53 are shown in FIG. 2, the details of which are expressly referred to in this regard, the visible combination of one evaluation stage 54 and 56 of the ABS control electronics 22 and the VR control electronics 40, respectively. The evaluation stage 54 of the ABS control electronics 22 uses this to generate characteristic A output signals for the slip of the vehicle wheels 12, 13, 14 and 16, which together with the acceleration signals in a downstream comparison stage 57 with threshold values (λι, Xi, λ $, + b and —B) are compared. The logic output signals of the ABS comparison stage 57 generated as a function of the threshold value are processed in a logic unit 58 connected downstream of this to form the control signals suitable for the control of the brake pressure regulating valves 23, 24 and 27

The evaluation stage is also part of the control electronics 40 of the propulsion control device 10 56 is followed by a comparison stage 59, which is derived from a comparison of the received input signals mii. Generated threshold values for the respective driving situation characteristic logical output signals the linkage of which the VR linkage stage 61 connected downstream of the VR comparison stage 59 is the meaning the control signals for the brake pressure control valves required for the control function explained above 26 and 27 of the driven rear wheels 14 and 16, for the activation of the auxiliary pressure source 41, the return pump 33 mid of the actuator for reducing the output torque of the vehicle drive unit generated.

In the following, reference is made to FIG. 3 in more detail Basic structure of the safety circuit provided in the context of the advance control device 10 52 received.

This receives at a first input 62 -, those output signals of the VR linkage stage 61, with which the brake pressure control valve 26 assigned to the left rear wheel brake in its pressure: or pressure reduction position is controlled, at its second input 63 receives the safety

1 I _ ffr \ J "* -U, n4nn C» nt »» ff>! Fvn <ilA fit r · AiV

Brake pressure control valve 27. The output signal of an accelerator pedal position transmitter is at the third input 64, which is a high level signal when the accelerator pedal is in the neutral position. On one > i fourth input 66 is the control output signal of the VR linkage stage 61 received, the torque-reducing intervention in the drive unit triggers. At a fifth input 67, the safety circuit 52 receives a high-level input signal, jo when the brake light switch is closed, d. H. the Driver applies the driving brake. A sixth input 68 is the slip threshold output signals the VR comparison stage 59 and a seventh input 69 whose acceleration threshold jj value signals.

In the context of a first sub-unit 71 of the safety circuit 52 there is an OR logic element 72 is provided that the brake pressure regulating valve control signals received at the first input 62 and at the second input 63 receives. The subunit 71 further comprises a two-input AND element 73 with a non-negated input 74 and an iron negated one Input 76. This negated input is connected to the third input 64 of the safety circuit 52, the 4> the accelerator pedal position signal is supplied. Through the Subunit 71 monitors the error condition that the propulsion control device is in the idle position the accelerator pedal must not work.

The accelerator pedal position signal is fed to the negated input 76 of the AND element 73 via a time delay element 100, which holds the high level output signal of the accelerator pedal position transmitter for a period of time dt which is so dimensioned that a brief removal of the gas does not occur leads to a shutdown of the propulsion control device.

If a high-level output signal is output at the output 77 of the AND element 73, then a signal is present Error before and the propulsion control device is switched off

60 A second sub-unit 78 of the safety circuit 52 contains a two-input AND element 79, its first input 81, the output signal of the OR gate 72 of the negated by means of an inverter first subunit 71 is supplied, and that at its 65 second input 83 that at the fourth input The input signal received with the receives the torque-reducing intervention in the drive unit can be triggered

Il

This second sub-unit 78 monitors the condition that an intervention in the drive unit May only take place if at least one of the wheel brakes 31 or 32 is activated at the same time is. A third sub-unit 84 of the safety circuit 52 comprises a three-input AND element 85, which has two non-inverting inputs 86 and 87 and one inverting input 88. To the first, non-inverting input 86 of this AND element 84 is the inverted output signal of the OR logic element 72 of the first subunit 71. The second non-inverting E 'input 87 is the output signal of a two-input OR gate 89 is supplied, the inputs of which are connected to the inputs 68 and 69 of the security circuit 52 are connected to which the slip signals or the wheel deceleration signals of the VR comparison stage 59 are fed. To the the inverting input 88 of the AND element 84 is supplied with the braking ready signal. Through this third subunit 84 the condition that the Propulsion control device 10 is not allowed to work when the travel brake is activated. A high level output signal of AND gate 85 indicates that there is an error and triggers the shutdown of the propulsion control device 10 off.

A time comparison element 98 is connected to the output 97 of the three-input AND element 85, which compares the signal duration of the output signal of the AND element 85 with a comparison time period St of approx. 1 to 2 s. If the output signal jl of the AND element 85 is longer than the comparison period, the timing element 98 emits a control signal which triggers the reduction of the brake pressure in the wheel brakes 31 and 32 of the driven vehicle wheels 14 and 16.

The control signals received at the inputs 62, 63 as well as 6it and 69 of the safety circuit 52 for the brake pressure control valves 26 and 27 or for the state of motion of the driven vehicle wheels 14 and 16 characteristic slip and acceleration or deceleration signals of the VR comparison "'stage 59 are compared by means of one timer 92 with a time period of, for example Δι is, Hie corresponds to an empirical value for the maximum occurring at the correct operation of the propulsion control means Si gnaldauer. the signal duration 1st greater, so is

^{1 (1} an error occurs and an output signal is generated to switch off the propulsion control device.

With the error display output via the common output 93 of the safety circuit 52- "· gi'alen a monitoring relay 95 can be controlled, the has an opening contact 94 which is in the excitation circuit of a valve relay 96, daj in turn can be excited by an output signal of the VR control electronics 40, which is in the active phases of the

- ^{> !!} Voiiiieus regulation is pending. During the active phase of the propulsion control device, the operating contact 29 of this valve relay, which is closed in the energized state, is used to supply the battery voltage as a control voltage to the excitation windings of the switching

- 'valve assembly 42 applied.

When a Fchler signal is present at the output 93 of the safety circuit 52, the auxiliary pressure source 41 is switched off against the pressure booster 53.
Finally, through an OR operation 91, the

^! "Error output signals of the ABS safety circuit 37 and the VR safety circuit 52 ensure that in the event of a malfunction of the anti-lock device 11, both this and the propulsion control device 10 are switched off

^ Propulsion control device 10, however, only this one.

In addition 3 Biatt drawings

Claims (12)

Patent claims: 1. Propulsion control device for a vehicle with at least two driven wheels, which is also equipped with an anti-lock braking system (ABS), wherein the propulsion control device (VR), when a drive wheel tends to spin, its The wheel brake is applied and, if both drive wheels tend to spin, a torque-reducing intervention in the drive unit is prevented. takes, and in the context of the ABS and the propulsion control device overall the following Components are provided: a) a speed sensor for each wheel, the one for the wheel speed or peripheral speed generates proportional electrical output signal, b) for each wheel an electrically controllable brake pressure control valve, which is in a passage, constrict - and can be steered into a discharge position, c) an electronic control unit, which is derived from the output signals of the wheel speed sensor slip (A), wheel acceleration and wheel deceleration signals and from a comparison of these signals "with predetermined threshold values (A * + b and - b), as well as a combination of such signals the pressure build-up, pressure maintenance and pressure reduction signals required to control the brake pressure control valves in the sense of the ABS or propulsion control function, d) the operational readiness of at least the Anti-lock braking system monitoring safety circuit, which in the event of a malfunction this switches off and thereby resets the brake pressure control valves to their basic position intended for pressure build-up, e) an auxiliary pressure source, which during the active phases of the propulsion control device Pressure supply of the respectively actuated wheel brake ^) mediates, characterized by the following features: A. the electronic control units (22 and 40) provided for the ABS and the propulsion control device (10) have a common one Signal input stage (53) for the state of motion of the vehicle wheels (12,13,14,16) characteristic speed and acceleration fö / output signals generated, B. the signal input stage (53) is in the context of ABS control unit (22) an evaluation, comparison and linking stage (54, 57, 58) downstream, the signals received from the signal input stage for the ABS control generates control signals for the brake pressure control valves (23,24,26,27), C. within the scope of the control unit (40) of the propulsion control device (10), the signal input stage (53) is also an evaluation, Comparison and linking stage (56, 59, 61) connected downstream, which results from a processing of the received from the signal input stage (53) v- and the ivSignale for controlling the brake pressure control valves (26 and 27) or of the Actuator for the torque reduction necessary control signals are generated, D. A safety circuit (52) monitoring the function of the propulsion control device (10) is provided which, in the event of a malfunction of the propulsion control device only its control unit (40) and the auxiliary pressure source (41) switches off, E. * the safety circuit of the ABS is designed in such a way that in the event of a field function the same both the ABS (11) and the propulsion control device (10) switched off will. 2. Device according to claim 1, characterized in that a first sub-unit (71) of the The safety circuit (52) of the propulsion control device generates an output signal which causes it to be switched off, if a signal for an active phase the characteristic signal of the evaluation circuit (53, 40) or of the drive control device Security switch (52) and a signal at the same time an accelerator pedal position transmitter is present, which indicates that the accelerator pedal is in the idle position is located. 3. Device according to claim 2, characterized in that the accelerator pedal Stelhaigsgeber in the Idle position ^ of the accelerator pedal in high-level output signal and otherwise a low-level output signal generated and that the sub-unit (71) as a Input signal the control signals for the brake pressure control valves (26 and 27) of the driven Vehicle wheels (14 and 16) receiving OR gate (72), and that a Two-input AND gate (73) provided with a negated and a non-negated input is that at the non-negated input (74) the output signal of the OR gate (72) and on its negated input (76) receives the output signal of the accelerator pedal position transmitter. 4. Device according to one of the preceding claims, characterized in that a a second sub-unit (78) of the VR safety circuit (52) is provided, which switches off the latter mediating output signal generated when on the one hand there is a signal indicating that a Reduction of the output torque of the drive unit is to be triggered and on the other hand there is a signal that indicates that neither the one or the other wheel brake (31 or 32) of the driven vehicle wheels (14 or 16) is actuated is. 5. Device according to claim 4 in conjunction with claim 3, characterized in that the second Sub-unit (78) of the VR safety circuit (52) has a two-input AND element (79) which is connected to its one input (81) the inverted output signal of the OR gate (72) of the first sub-unit (71) of the VR safety circuit (52) and on its second input (83) that for triggering the torque reduction of the drive unit receives characteristic high-level signal. 6. Device according to one of the preceding claims, characterized in that a third sub-unit (84) of the VR safety circuit (57) is provided, which generates a malfunction output signal when the drive brake is not actuated and outside an active phase of the propulsion regulation ment for a circumferential delay at least one of the driven vehicle wheels (14 and 16) there are characteristic λ or -6 signals. 7. Device according to claim 6 in conjunction with claim 5, characterized in that the third Sub-unit (84) of the VR security circuit (52) has a three-input AND gate (85) which has two non-inverting inputs (86 and 87) and one inverting input (88)! and on its first, non-inverting input (86) the inverted output signal of the. ÖDER logic element (72) of the first sub-unit (71) of the VR safety circuit (52) and at its second non-inverting input (87) I received the output signal of a two-input OR element (89) begins to which at its one input the (-6 ^ -wheel deceleration signals and at its other input the slip (A) signals of the comparison stage (59) the VR evaluation circuit (4O] I are fed. 8. Device according to claim 7, characterized in that a Zek comparison element (98) is connected to the output (9, 7) of the three-input AND element (85) which, if there »Ausyangssignal of the three-input -AND element (85) is present longer than a defined comparison time period (At) , a signal that triggers the pressure reduction in the wheel brakes (31 and 32) of the driven vehicle wheels (14 and 16) is generated 9. Device according to one of the preceding claims, characterized in that the slip (X) and acceleration ^ + £>,} - or deceleration (-ö / signals of the comparison stage) characteristic of the state of motion of the driven vehicle wheels (14 and 16) (59) the VR evaluation circuit (40) and preferably also its output signals, which control the J5 brake pressure control valves (26 and 27) in their Spen (pressure holding) or discharge (pressure reduction) position, are fed to comparison timing elements (92), which generate an output signal that switches off the propulsion control device if the said signals are present for longer than a defined period of time (Δt) of, for example, 1 s. 10. Device according to one of the preceding claims, characterized in that the electrical control of the coupling of the Hüfsdsuckquellc (41) to the brake circuit of the driven vehicle wheels (14 and 16) mediating control valve arrangement (42) via an in an active phase of the propulsion control device "> o energized valve relay (96) takes place, the excitation circuit via an opening contact (94) of a Monitoring relay (55) leads through malfunction output signals of the VR and ABS safety circuits (52 and 37) as well as through a Function output signal of the anti-blocking system and by an activation of the driving brake, z. B. by the brake light switch, triggered signal can be excited 11. Device according to claim 10, characterized in that the brake line (36) of the brake circuit of the driven vehicle wheels (Ϊ4, 16) is connected to the output pressure chamber (Si) of a pressure booster (43) with a floating piston (44), whose primary-side piston stage (45) can be acted upon via the control valve arrangement (42) with the output pressure of a pressure source present on the vehicle, and its secondary-side piston stage (46) .one associated with the brake circuit of the driven vehicle wheels; Exit rack space of the Hauptliremszyünders (48) of the brake system communicating inlet pressure chamber (47) is limited Via an open *, otherwise closed, in the position of the pressure booster piston (44) Central valve (49) communicates with the output thickening chamber (51) of the pressure booster (43) 12. Device according to one of the preceding claims, characterized in that the safety circuit (52) of the propulsion control device (10) comprises a test device which contains a function generator which can be activated, for example, by switching on the ignition, which within a defined test period of the evaluation circuit (53,40) offers a set of v and δ input signals with a defined time course, from the processing of which a pulse sequence of the possible control output signals corresponding to a predetermined signal pattern can be derived, and that a comparison device is provided which, if this pulse sequence deviates from .A malfunction indicator signal is generated for each specified signal pattern