DE3421776C2 - Four-wheel drive vehicle - Google Patents

Description

The invention relates to a four-wheel drive vehicle, where both the wheels of an axle with the drive shaft as well as the drive shafts with the drive motor are connected by differential gear.

Such vehicles are known (see e.g. Bosch Kraft Fahrtechnisches Taschenbuch, 18th edition, page 318 and 319). To the disadvantages (starting difficulties with small to avoid nem µ on a wheel) of such vehicles, come with such vehicles with differential a lock to use, whereby at least the Hin Terra wheels and the two drive shafts practically rigid be connected to each other.

Such locks have the disadvantage that critical driving Braking conditions occur that the vehicle can drive worse and that especially Pro bleme erge when installing an anti-lock control system ben.  

When equipping the vehicle according to the characteristics of claim 1, is achieved in terms of Start up the same effect as by the mentioned Lock, but has the advantage of better driving properties ten, e.g. B. traction. All bikes are on optima len traction controlled and thus enable good Side guide. There is also a maxi on the front wheels male traction achieved. In addition, the use of Anti-lock regulators are unproblematic.

A traction control system for the driven wheels it is known per se (DE 31 27 302 A1; DE 30 21 116 A1).

The invention lies in creating an electronic alternative for the Differential locks.

The traction control system is in a known manner carried out. The signals are preferably all Encoder is an approximation of the vehicle speed train size formed, the size of which advantageously from the donors of the wheels lying on one side of the wagon is true and the speed increases only ver hesitates.

According to a development of the invention, additional affect the engine torque via an active connection flows when the last of the wheels is spinning.

One will favorably braking for the purpose of ver Avoid spinning only up to a predetermined one Limit speed, so at a higher Speed lock the influence or switch off Furthermore, only the Influencing the engine torque z. B. by controlling the Throttle valve made.

Exemplary embodiments of the Invention explained in more detail.

Show it:

Fig. 1 shows an embodiment

Fig. 2 and 3 solutions for the brake system 10 of FIG. 1

FIG. 4 shows a detailed illustration of block 6 of FIG. 1.

The drawing shows a four-wheel vehicle whose wheels 1 a-1d are all driven. The torque on the transmission 3 output by the engine 2 through a differential gear to the drive shafts 3 a 4 a and 5 a, and on further Ausgleichsge gear 4 and 5 on the wheels 1 a- 1 d conducted. All wheels are assigned speed sensors 1 a'- 1 d ', which are connected to a control device 6 . This detects one by rotating or spinning wheels and influences valves in block 7 . Brake system 10 also includes a pressure source. Via the valves in block 7 , pressure can thus be fed separately to the individual wheel brakes via lines 8 . The brake pressure control can thus prevent the individual wheels from spinning. Rotate through all the wheels, so is z 9 via the operative connection of the control device 6, the engine torque. B. additionally reduced by adjusting the throttle valve.

Possible and preferred structures of block 10 of FIG. 1 are explained with reference to FIGS. 2 and 3.

In FIG. 2, the brake system 10 includes a hydraulic dual-circuit tandem Hauptbremszyliunder are disposed with a housing 11 and with a stepped cylinder 12, in which behind the other two pistons 13 and 14. The front piston 13 is under the force of a return spring 15 on a shoulder 16 formed in the cylinder and limits an Ar beitskammer 17 to which a first brake circuit I is connected. In the illustrated starting position of the piston 13 , the latter has a connection to a refill container 19 via a housing channel 18 . This front portion of the master cylinder thus forms a closed brake circuit, the piston 13 has an inclined surface 13 a between two treads, along which the plunger 20 a of a switch 20 runs.

The second piston 14 arranged behind the front piston 13 runs within the larger gradation of the cylinder 12 and delimits a chamber 21 to which, for example, a second brake circuit II is then connected. The effective, the reaction of the pressure forces over the surface of the piston piston designed as an annular piston 14 is supplemented by an end face 22 a of a penetrating pedal tappet 22 . The Pedalstö ßel 22 can be actuated together with a control valve 23 via a pedal plate 24 which is steered on the brake pedal 25 . The control valve is designed so that it connects the chamber 21 in its two possible end positions either with a relief point (refill container 19 ) or with a best of pump 26 and accumulator 27 existing pressure medium source 28 . The pressure medium source is completed by a motor 29 for driving the pump 26 and by a responsive to the still existing storage pressure switch 30 to control the motor.

At this point, it should be pointed out that the structure and the operation of the tandem two-circuit master brake cylinder shown in FIG. 2, which will be described below, is only given by way of example for a better understanding of the design of an actuator which acts on the control valve.

The control valve 23 has a control slide 31 which can be actuated by the pedal plate 24 via a travel spring 32 . Due to the relatively long slide surfaces of the control slide can supply the full pedal travel to actuate the device from the pedal tappet 22, for example after an initially free movement later on a not shown coupling device entrained annular piston 14 who uses the even when the power supply fails.

A bias spring 33 presses the spool 31 in the plane of the drawing to the right into its initial position in contact with the pressure plunger 34 on the pedal plate 24, which is under the action of the travel spring 72 .

Brake pressure control elements 35 , 36 , 37, which are connected in the brake lines to the wheel brake cylinders and are designed, for example, as 3/3-way solenoid valves, can also be used to activate ABS control functions (anti-lock protection) in the brake system.

At the actuation end point 39 of the control slide 31 of the control valve 23 , the arbitrarily actuatable actuator 40 engages, which in the embodiment shown in FIG. 2 is an electromagnet 41 designed as a pull magnet. The electromagnet 41 is comprised of coil 42 and armature 43 upon driving the Wick lung with a stream of any shape, amplitude, and timing is drawn in a corresponding manner in the coil interior and erfor sary a in this case, the armature and at the point 39 fixed gemach th cross lever 43 takes control of the control valve 23 with the control slide 31 .

The overall effect is as follows. The control slide 31 can either via the plunger 34 from the pedal plate 24 or when lifting from the plunger 34 even when the brake pedal 25 is not actuated by actuating the actuator 40 , in Fig. 1 with electrical signals, from the initial position to the left, thereby from the energy supply 28 via a pressure inlet 44 on the control valve 23 , an annular recess 45 and a central through hole 46 on the spool 31, the pressure of the auxiliary energy in the pressure chamber 21 and from there to the next in the brake circuit II and by appropriate action of the pressure applied the piston 13 a pressure is generated in the chamber 17, which is effective as a brake pressure in the brake circuit I. It can without brake operation means of the actuator 40 and Actuate the supply of the valves 35-37 pressure at the individual brakes is controlled for traction control will be.

In the embodiment of FIG. 3 is different Lich, that the actuator 40 is designed as a hydraulic working cylinder 47 , the actuating piston 48 un ter carried out a displacement movement by the upstream solenoid valve 49 controlled pressure and via its piston rod 48 a with this and on Attack point 39 for the control slide moored cross lever 50 takes the control slide for actuating the control valve. The control of the Magnetven valve 49 is again carried out by supplying electrical signals, as indicated at 51 ; the brake valve is actuated indirectly via the control piston.

By feeding out if necessary formed electrical signals, clocked and with various those current levels with temporal change to reali Corresponding time-current functions result advantageous options for the pressure feed Brake valves to implement traction control gene.

In FIG. 4, block 6 of Fig. 1 and drawn out in detail. The four lines that come from the transducers 1 a'- 1 d 'lead to a block 60 in which a reference signal is generated which is approximated to the speed of the vehicle. This is achieved in a known manner in that the reference signal adapts to the increasing wheel speeds with a predetermined pitch and thus when the wheels spin. The reference signal is fed to comparators 61, in which the signals of the transmitter are compared with this reference signal, and in which control signals for the valves 7 and 35 - are generated 37th These control signals are also fed to an AND gate 62 , which in turn generates another control signal when all the control signals are present. This further control signal is fed via line 9 to the engine 2 to reduce the engine torque. Both the control signals for the valves 7 and that for the engine 2 are suppressed when the vehicle speed is above a predetermined value. This is achieved with the aid of a block 63 which generates a blocking signal if this size is exceeded. The blocking signal blocks the AND gate 62 and gates 64 in the lines to the valves.

Claims (4)

1. Vehicle with all-wheel drive, in which both the wheels of an axle with the drive shaft and the drive shafts are connected to the drive motor via differential gears, characterized in that the wheels ( 1 a- 1 d) transducer ( 1 a'- 1 d ') are assigned to monitor the wheel speed, that these are connected to a control device ( 6 ) and that a brake pressure control device ( 10 ) containing a pressure source is provided, which is then controlled by the control device ( 6 ) in the sense of braking one or more Wheels is controlled when this wheel or these wheels spin or spin compared to the other wheels. 2. Vehicle according to claim 1, characterized in that the control device ( 6 ) contains a device for forming an approximate reference value of the vehicle speed from the signals of the sensors ( 1 a'- 1 d '), the size of which preferably from the sensors a wheel lying on the side of the car is determined and increases in speed only follow with a predetermined deceleration. 3. Vehicle according to claim 1 or 2, characterized in that between the control device ( 6 ) and a member influencing the engine torque, an operative connection ( 9 ) exists for the purpose of lowering the engine torque, even if the last of the wheels ( 1 a- 1 d ) freaked out. 4. Vehicle according to claim 1 or 2, characterized records that the braking and possibly the loading Influence of the engine torque through the control direction only up to a given limit speed is done.