DE3430982A1 - Wheel slip control arrangement - Google Patents

Abstract

The wheel slip control arrangement is equipped with measuring sensors (41, 42, 43) for detecting the wheel rotational behaviour and, where necessary, other vehicle-dynamic measured values, with electronic circuits for processing and logic operation of the output signals of these measuring sensors and for the generation of control signals. Lockable differentials (1), in which the wheel slip control circuit (40) intervenes as a function of the rotational behaviour of the wheels (VR, VL, HR, HL) or the handling of the vehicle, are inserted into the drive train of the vehicle. When control commences, the control circuit (40) only controls the wheel brake (13, 14) of the wheel tending to spin. Only after a predetermined delay time are the differential locks (1) actuated as a function of the wheel rotational behaviour and the handling of the vehicle. <IMAGE>

Description

Arrangement for regulating the drive slip

The invention relates to one provided for motor vehicles Arrangement for the regulation of the drive slip, with measuring transducers for the determination of the wheel rotation behavior and, if necessary, further Fahrdyrlamisc, ler measured values and with electronic circuits for processing and logically linking the Measured values as well as for the generation of output signals is equipped to which the Braking effect on the wheels can be controlled individually or in groups.

It is already known to regulate the propulsion or drive slip activate the wheel brake of the drive wheel tending to spin and this Wheel so far that it is within a range for the transmission of the Drive torque favorable slip range remains (DE-PS 31 40 959, DE-OS 32 15 739). This allows both the transmission of the drive power to the road improve as well as the driving stability and, if it is a front wheel, preserve the maneuverability of the vehicle.

However, if it does not succeed or, especially in the case of very different things Coefficient of friction on the left and right drive wheel, the drive torque is not appropriate of the motor very quickly after applying the brake, the in the Wheel brake to be converted into heat energy so high that the brake is released or on very high wear of the units must be accepted. The overall efficiency the drive is also affected by this mode of operation.

A well-known disadvantage of differentials, which are used to compensate for the different distances of the right and left wheels are necessary in curves, consists in the fact that in unfavorable road conditions, i.e. on unpaved terrain, If there is a very low coefficient of friction on one side of the road, etc., spin a wheel can. This makes starting the vehicle more difficult or makes driving behavior worse. In some situations, the driving stability of the vehicle is endangered. As a remedy The installation of a differential lock is known for these phenomena, but may only be switched on in certain situations, because otherwise, e.g.

would make cornering difficult. A lock in the front differential a vehicle driven by the front wheels is therefore generally avoided, because such a differential lock impair the steering ability of the vehicle too much could.

The invention is now based on the problem of the disadvantages outlined to overcome known arrangements and a comparatively simple, safe and for the situations occurring in practice are different Kind of developing suitable traction control.

It has been shown that this task is progressive can be solved with an arrangement of the type mentioned, whose peculiarity consists in the fact that one or more lockable in the drive train of the motor vehicle Differentials are built in and that a drive slip control circuit is available is that depending on the turning behavior of the wheels and / or the driving behavior of the vehicle operates the differential locks.

The measures proposed according to the invention can surprisingly the serious disadvantages of the drive slip control described with the help a Bretnsene intervention and overcome the disadvantages of limited slip differentials and combine the advantages of both systems. The result is an arrangement for traction control, which is able to cope with the various roadway situations that occur during start-up and Acceleration phase without the risk of overloading the brake without restriction can be and which are effective for increasing propulsion and improving straight-line stability contributes at high drive torque.

Mach an advantageous embodiment of the invention controls the Control circuit at the beginning of the control only the wheel brake to spin trending wheel and is only actuated after a specified delay time for example 1 to 3 seconds, preferably 1 to 1.5 seconds, depending on the turning behavior of the wheels and / or the driving behavior of the vehicle the differential locks.

The arrangement according to the invention for motor vehicles is also provided train with front-wheel drive, then the operation of the differential lock additionally on the steering angle or steering angle of the front wheels, the steering wheel position or the steering movements is dependent.

To determine the steering angle or the steering movements is a Steering center sensor is provided, the output signals of which the logic interconnection circuits or the electronic control circuit can be fed.

Furthermore, there is an embodiment of the invention that the differential locks are designed in the form of form-fitting clutches, with which the related axles driven via the differential or Semi-axles can be coupled to one another, both before the clutch is engaged Axes to approximately the same speed of rotation with the aid of the brake are synchronizable. The clutch, which is suitable as a differential lock, acts in this Case is particularly simple and can be produced with comparatively little effort and designed for high drive torques.

The arrangement according to the invention can be a hydraulic brake pressure transducer and have an auxiliary pressure source, the differential locks being in the form of Let form clutches with the help of a shift lever a- and are knockout. This gear lever is e.g.

with the hydraulically displaceable working piston of an actuating or Slave cylinder connected via one or more hydraulic, electromagnetic actuatable multi-way valves can be connected to the auxiliary pressure source.

Further features, advantages and possible uses of the invention go from the following description with reference to the attached illustration of an embodiment of the invention.

The figure shows to explain what the invention is based on Principle in a schematically simplified partial representation of an arrangement with a differential gear or differential 1, which is intended for installation in vehicles with driven front axles is. Only those in the front axle differential are from the vehicle's drive train 1 opening part of a cardan shaft 2 and the drive half-axes 3 and 4 are reproduced.

The differential 1 has a switchable lock 5, which by the The clutch framed in dashed lines is symbolized, which with the help of an actuation or shift lever 6 can be engaged and disengaged. In the drawn rest position or the initial position, the lock is canceled, the clutch 5 is thus disengaged. With the aid of a return spring 7 acting on the lever 6 and a return spring 8 in an actuating or slave cylinder 9, which will be described below, the rest or disengagement position shown can be maintained.

The vehicle described, of which only those used to explain the invention required parts are shown, is equipped with a brake system with the both the brake slip and the starting slip can be regulated. The braking system consists essentially of a two-circuit hydraulic brake pressure transducer 10, its two hydraulic circuits 11, 12 here each with the wheel brakes of a vehicle diagonal are connected.

However, only the front wheels VL, VR with the wheel brakes are shown 13,14, while the hydraulic connection to the rear wheel HL, HR or to the corresponding The rear brake is only indicated by an arrow 10 includes a hydraulic booster and is therefore connected to an auxiliary pressure source rusted out, the main components of which are driven by an electric motor Hydraulic pump 15 with the associated check valve 16 and a hydraulic accumulator 17 are. The suction side of the pump 15 is connected to the pressure equalization tank 18 of the brake pressure transducer 10 connected.

To regulate the brake pressure and thus the slip are in the hydraulic connection lines to the wheel brakes 13,14 electromagnetically actuated, so-called SO valves 19.20 (normally open valves) inserted, which are normally are switched to passage and with which a further pressure increase after switching can be prevented. Via "SG" valves 21, 22 (normally closed valves), each in a wheel brake 13 or 14 illit the pressure compensation tank 18 or 18 ' connecting hydraulic line 23,24 are used, Brake pressure can be reduced for slip control; 18 and 18 'are parts of the same Pressure compensation tank. Corresponding valve arrangements are in the not shown, Hydraulic lines leading to the rear wheels HL, HR are available.

The brake system described here also has valve devices 25,26, with which the auxiliary pressure source (15 - 17) via the 50 valves 19,20, directly can be connected to the wheel brakes 13,14, so that independently of the brake pressure transducer 10, also when the brake pedal 27 is not pressed, brake pressure in the wheel brakes 13,14 can be controlled. The valve devices 25, 26 are only used for regulation of the starting slip required X The shift lever 6 for engaging the lock or the Clutch 5 for the front axle differential 1 is made with the aid of the aforementioned hydraulic servo or slave cylinder 9 actuated. The working piston is used for this purpose 28 inside the cylinder 9 is connected to the lever 6 via a push rod 29. By applying pressure in a working chamber 30 of the cylinder 9, the piston 28 moved against the force of the return spring 8, causing a pivoting of the lever 6 in the direction of arrow 31 and an engagement of the clutch 5 results in the the two drive half-axles 3, 4 connects with each other and thereby the compensating effect of the differential 1 cancels.

The working chamber 30 of the cylinder is in the rest position shown 9 over a pressure fluid line 34 and over a normally open 2/2-way valve 32 connected to an expansion tank 33, so that in the chamber 30 atmospheric pressure If the tank 33 prevails, it can be a component of the expansion tank 18. To Switching over the valve 33 and blocking the pressure medium path to the container 33 can Pressure into the working chamber 30 via a pressure medium line 35 and the line 34 of the slave cylinder 9 are fed. As soon as sufficient pressure is built up is, the piston 28 moves in the cylinder 9 and with this the lever 6, the engages the differential lock.

The pressure to confirm the differential lock is shown at the Arrangement of those already required to operate the brake system and the slip control Auxiliary pressure source 15-17 removed. For this purpose, this source is in one with the actuating cylinder 9 connecting pressure medium line 38,35,34 a 2/2 »way valve 39 inserted, the normally prevents a flow and that by an electrical signal can be switched to flow. This valve 39 is in construction and in the The mode of operation is comparable to that of the SG valves 21, 22 described.

The primary regulation of the braking and drive slip resp.

ur control of the multi-way valves 19-22 in the pressure medium path of the Brake pressure transducer 10 to the wheel brakes 13, 14 of the triggering the differential lock Valves 39 and the valve devices 25,26 required switching signals are with With the help of a common electronic circuit or control system 40 generated, the several hard-wired electronic circuits or programmable ones Construction stages, such as microcomputers. The information about the turning behavior of the individual vehicle wheels, possibly also the cardan shaft, are made with the help of inductive transducers 41, 42, which have a frequency proportional to the rotational movement Deliver the signal, fed to the electronics of the controller 40 via the inputs E1 -En, which through signal processing, logical linking of the signals, the required control signals and sends it to the valves via its outputs A1 An.

According to the invention for regulating and limiting the drive slip First the wheel brakes 13, 14 are activated. Will after a specified period of time e.g. from one second after the delta response of the slip control or after activation the brake, there is still a high difference in value between the two wheels If an axis is detected, signals are output at outputs A01 and Ao2, which for switching over the valves 32, 39 and finally for hydraulic pressure application of the piston 28 in the slave cylinder 9. This engages the differential lock. The electrical connecting the controller 40 with the excitation windings of the valves 32,39 Signal lines are numbered 36.37.

Is the serving to lock the differential 1 clutch 5 according to a particularly favorable embodiment of the invention designed as a form-fitting coupling, is before actuating the lever 6 with the help of the electronics 40 and by appropriate Actuation of the wheel brakes 13, 14 initially increases the speed of the two wheels VL, VR set an approximately the same value and thereby the differential "synchronized" so that now the form-fitting clutch can be engaged.

Locking a front differential could reduce the steering capability of the vehicle to an inadmissible extent. Hence the described and the arrangement shown with a steering sensor 43, i.e. a transducer to determine the steering angle of the wheels, the steering wheel position or the steering movements, equipped, the output signals of which are also fed to the controller 40 and at the logical connection, when controlling the drive slip and, above all, when Engaging and disengaging the clutch 5 of the lockable differential 1 is taken into account will. The steering sensor 43 can be combined with a microswitch that the engagement of the differential lock 5 prevents or releases the lock as soon as the Steering angle, taking into account the vehicle speed Value, or if larger steering movements by the driver are sensed In Another (not shown) embodiment of the invention is used instead of two 2/2-way valves 32,39 a 3/2-way valve used, which is in the output or Rest position also the connection of the slave cylinder 9 to the auxiliary pressure source (15-17) interrupts and the working space 30 of this cylinder 9 with the pressure equalization tank 18 connects.

For vehicles with all-wheel drive, appropriate design the circuit logic 40 or the program, if this logic is programmable components enthci. lt, also differential locks in the manner described controlled in the rear axle differential and / or in an intermediate differential to, among other things

the driving behavior of the vehicle with different levels of grip the left and right sides of the vehicle, wheel stability and other properties to improve.

Claims (8)

Claims 1. Arrangement for motor vehicles for regulation'des Drive slip, with transducers to determine the wheel rotation behavior and If necessary, further measured values of driving dynamics, with electronic circuits for processing and logically linking the measured values and for generating output signals, with which the braking effect on the wheels can be controlled individually or in groups is, by the fact that in the drive train of the vehicle a or several lockable differentials (1) are inserted and that one electronic Afltriebsschlupf control circuit (40) is present, which depends on the Rotational behavior of the wheels (VR, VL, HR, HL) and / or the driving behavior of the vehicle Differential lock (5) actuated. 2. Arrangement according to claim 1, characterized in that g e k e n n -z e i c h ne t that the control circuit (40) at the beginning of the control exclusively the wheel brake (13,14) controls the wheel with a tendency to spin and only after a predetermined one Delay Time depending on the turning behavior of the Xaders and / or the driving behavior of the vehicle actuates the differential locks (5), i. e. inserts and releases again at the appropriate time. 3. Arrangement according to claim 2, characterized in that g e k e n n -z e i c h n e t that the delay time between the response of the slip control and the actuation the differential locks (5) between 1 to 3 seconds, preferably 1 to 1.5 seconds, amounts to. 4. Arrangement according to one of claims 1-3, characterized in that g e k e n n z e i c h n e t that this is designed for front-wheel drive vehicles and that the actuation of the differential lock (5) additionally depends on the steering angle or steering angle of the front wheels (VR, VL), the steering wheel position or the steering movements is dependent. 5. Arrangement according to claim 4, characterized g e k e n n -z e i c h n e t that this to determine the steering angle or the steering movements with a Steering center sensor (43) is equipped, the output signals of which the logical Logic circuits or the electronic control circuit (40) can be fed. 6. Arrangement according to one of claims 1-5, characterized in that g e k e n n z e i c h n e t that the differential locks (5) are in the form of form-fitting couplings are formed, with which the associated, driven by the differential (1) Axes or Semi-axis (3, 4) can be coupled to one another, and that Before engaging the clutch (5), both axles (3, 4) using the wheel brakes (13,14) can be synchronized to approximately the same speed of rotation. 7. Arrangement according to one of claims 1 - 6, characterized g e k e n n z E i c h n e t that this has a hydraulic brake pressure transducer '(10) and an auxiliary pressure source (15-17) and that the differential locks (5) are designed in the form of clutches are, which can be engaged and disengaged with the help of a shift lever (6) that is connected to the hydraulically displaceable working piston (28) of an actuating or slave cylinder (9) is connected. 8. Arrangement according to claim 7, characterized in that g e k e n n -z e i c h n e t that the actuating or slave cylinder (9) via hydraulic, electromagnetically actuated Multi-way valves (32, 39) can be connected to the auxiliary return source (15-17).