DE3506886C1 - Drive control device - Google Patents

Abstract

In a drive control device for a motor vehicle, which is equipped with a dual-circuit brake system, a hydraulic brake booster and a four-channel antilock system functioning on the return feed principle, all brakes of the vehicle wheels which can be subjected to the drive control belong to a closed brake circuit. The brake booster has a drive circuit, hydraulically separated from the brake circuits, with a drive piston, actuatable by servo pressure, which directly drives the primary piston of the tandem master cylinder of the brake system. The drive pressure chamber is constantly connected to the pressure outlet of the servo pressure source, and a flow path leading from the servo pressure source to the reservoir is provided, which can be shut off by activation of a drive control valve. In normal braking, the flow resistance of this flow path leading to the reservoir is varied proportionally to the pedal travel.

Description

where the propulsion control is applied to all driven vehicle wheels works. The one that can be operated with pedal power and hydraulic power assistance Brake system comprises a tandem master cylinder in which a primary piston and a secondary piston delimits the primary output pressure chamber in the axial direction is to which the one brake circuit is connected, and in which by the secondary piston and an end wall of the cylinder housing delimits the secondary output pressure space to which the other brake circuit is connected. The primary piston is a plunger formed, which has a significantly smaller cross section than the rest of the Housing bore delimiting the primary outlet pressure chamber and passes through an annular piston with a diameter corresponding to the diameter of the primary bore step through which, under the influence of the im

Primary output pressure chamber of the pressure prevailing against a pedal-side Stop shoulder of the cylinder housing is pushed and remains held. For brake booster a proportional valve that can be actuated by means of the brake pedal is provided via an auxiliary pressure proportional to the pedal travel from an auxiliary pressure source into the primary output pressure chamber of the tandem master cylinder and thus in the brake circuit connected to it can be coupled. The proportional valve intended to control the brake booster is provided with an electromagnetic or hydraulic actuator, with which the proportional valve, if in the context of a propulsion control phase a Braking of one or more of the driven vehicle wheels is required, is controlled in its short-circuit position, in which the full output pressure the auxiliary pressure source is coupled into the primary output pressure chamber of the tandem master cylinder will. The selection of the vehicle wheels to be braked in a propulsion control phase takes place in that their brake pressure control valves remain in the pressure build-up position and the brake pressure control valves of the vehicle wheels not to be braked in their locked position being controlled.

The known propulsion control device is due to their insofar explained structural and functional properties with at least the following Disadvantages: in that in the primary output pressure chamber of the tandem master cylinder the known brake system directly brake fluid from the auxiliary pressure source - one by means of a pump chargeable high-pressure accumulator - is coupled, which at a Brake actuation with high flow speed taking place in the context of a propulsion control phase Via the short-circuit flow path of the pressure control valve into the primary output pressure chamber of the tandem master cylinder flows in, whereby it initially relaxes, inevitably occur Bleeding problems in the brake circuit connected to the primary outlet pressure chamber that affect the long-term reliability of the braking system as a whole. Another disadvantage is that in the event of a leak in the primary outlet pressure chamber connected brake circuit the propulsion control function not only for this Driven vehicle wheels assigned to the brake circuit is omitted, but also for the vehicle wheels that can be braked by the other brake circuit, and that in this case of malfunction also no longer braked with auxiliary power in the secondary brake circuit can be.

The object of the invention is therefore to provide a propulsion control device of the type mentioned at the beginning, whose susceptibility to failure is lower, and the even if one of the vehicle's brake circuits is the result of a leak has failed in the brake line system, in the other brake circuit an auxiliary power-assisted one continues Brake pressure application and, if this brake circuit, driven vehicle wheels includes. also the maintenance of the propulsion control function on these vehicle wheels enables.

This object is achieved according to the invention by the in the characterizing part of claim 1 mentioned features solved.

Technical advantages of the propulsion control device according to the invention resulting therefrom are at least the following: in that the wheel brakes of the driven vehicle vehicle wheels each belong to a closed brake circuit, with a normal, d. H. braking triggered by pedal actuation as well as in the context of Propulsion control carried out activation of one or more of the brakes of the driven Vehicle wheels always build up brake pressure by shifting the master cylinder piston takes place, d. H. the brake circuits are also statically loaded in the propulsion control phases there are ventilation problems in the brake system that would otherwise result from the coupling from brake fluid from a reservoir into the vehicle's brake circuits could result, reliably avoided. It is also advantageous that with a Leak, e.g. B. the primary brake circuit, the secondary brake circuit continues by coupling the auxiliary pressure into the drive pressure chamber of the brake booster remains actuatable and thus also the propulsion control to the brake circuit for this belonging vehicle wheels is maintained.

The features of claims 2 to 4 are structurally simple and functionally reliable designs of a pressure-pilot operated throttle trained pressure control valve and one provided for controlling this throttle, force-controlled pilot valve specified, by pedaling a pedal travel-proportional Output pressure of the pressure control valve and thus the auxiliary pressure source for the normal Power-assisted braking is achieved, whereby the output pressure of the auxiliary pressure source, when the pressure medium flow path by actuation of the regulating control valve is interrupted, assumes its maximum value, which is in the course of a propulsion control phase is exploitable.

The features of claim 5 provide a suitable design for this a hydraulic pump generating the pressure medium flow specified as which, as indicated by the features of claim 6, within the scope of the operating pressure source a servo-steering device already provided hydraulic pump in connection with a power distribution valve can be used, which is a needs-based division of the pressure medium output flow of the hydraulic pump to the power steering and the Brake booster mediated.

The features of claim 7 are a design of the brake booster indicated, which is an inexpensive, compact, integrated design with the tandem master brake cylinder enables; in principle, however, it is also possible to use the brake booster in turn as a construction that can be attached to a normal tandem master cylinder of the usual type and train functional unit.

The features of claim 8 are a design of the propulsion control device specified in which the auxiliary pressure application of the brake booster both in the case of an unregulated braking phase as well as a braking phase subject to the propulsion control takes place from a pressure accumulator, which by means of the hydraulic pump of the auxiliary pressure source is chargeable, the charging controller expediently in the by the features of claim 9 specified manner takes place.

Due to the features of claims 10 and 11 is a special design of the brake booster that can be used within the scope of the propulsion control device according to the invention specified, even if the hydraulic pump of the auxiliary pressure source failed is still for a limited number of braking operations a maintenance the assistant support made possible.

Further details and features of the invention emerge from the following description of specific exemplary embodiments based on the drawing. It shows F i g. 1 shows the electrohydraulic circuit diagram of a propulsion control device according to the invention for a vehicle with power-assisted two-circuit braking system in which the auxiliary pressure for the brake booster by throttling the from a hydraulic pump delivered pressure medium flow is generated, F i g. 2 details of a modification the propulsion control device according to FIG. 1, the auxiliary pressure application of the brake booster in the case of a braking that is subject to the regulation Pressure accumulator takes place, which by means of the pressure medium pump of a power steering device is chargeable and F i g. 3 Details of one in the context of the braking system with propulsion control device according to FIG. 2 usable brake boosters.

In Figure 1, the details of which are expressly referred to; is, essentially by a hydraulic two-circuit brake system 10 with hydraulic Brake booster 11, a motor vehicle otherwise not shown in detail represents that also with a propulsion control device combined with an anti-lock braking system 12 is equipped, which works on the principle, a tending to spin, driven To decelerate the vehicle wheel by activating its brake so far that the drive slip of the driven vehicle wheels within a compatible with good driving stability Range remains. The wheel brakes 13 and 14 of the front wheels and the wheel brakes 16 and 17 of the rear wheels of the vehicle are connected to a front axle brake circuit or combined to form a rear axle brake circuit, each connected to the primary output pressure chamber 18 or the secondary output pressure chamber 19 of a tandem master cylinder 21 is more common Design are connected, the primary piston 22 by means of the brake booster 11, on the control rod 23 of which the brake pedal 24 is supported, with one to the pedal travel proportional - increased - force in the sense of a brake pressure build-up in the brake circuits is movable. The brake circuits 13, 14 and 16, 17 are static brake circuits formed, within which the brake pressure build-up solely by shifting the Primary piston 22 and the secondary piston 26 of the tandem master cylinder 21 takes place. The anti-lock braking system 12 is a so-called one that works according to the return principle Four-channel system formed, within which everyone represented by his brake Vehicle wheel a brake pressure control valve specially designed as a 3/3-way solenoid valve 27 and 28 or 29 and 30 are assigned from their basic position shown 0, in which brake pressure can be built up in wheel brakes 13 and 14 or 16 and 17, in a blocking position I and a pressure reduction position II can be controlled in which the brake pressure in the wheel brakes is kept at the respective set value or - in the return position - can be lowered.

The anti-lock braking system further comprises the vehicle wheels individually assigned Wheel speed sensors 31 to 34, which are characteristic of the state of motion of the vehicle wheels generate electrical output signals, from their processing an electronic Tax- unit 36 as well as the one for controlling the brake pressure regulating valves 27 to 30 in the sense of the anti-lock control as well as for the control of the Brake pressure control valves assigned to driven vehicle wheels in the sense of propulsion control required control signals generated.

For the purpose of explanation, without loss of generality assumed that the vehicle is four-wheel drive with front and rear differential gears have.

The primary output pressure chamber 18 of the tandem master cylinder 21 is via the main brake line 37 of the front axle brake circuit to the brake pressure control valves 27 and 28 to the wheel brakes 13 and 14 further brake line branches 38 and 39 connected, the secondary outlet pressure chamber 19 of the tandem master cylinder 21 Via the main brake line 41 of the rear axle brake circuit to its to the wheel brakes 16 and 17 via the brake pressure control valves 29 and 30 further brake line branches 42 and 43. By-pass flow paths connected in parallel to the brake pressure regulating valves 27 to 30 44 each with a relatively higher pressure on the wheel cylinder side in the opening direction pressurized check valve 46 are provided so that in a normal, i. H.

Braking taking place without anti-lock control when it is terminated Brake fluid can flow quickly from the wheel brake cylinders.

The respective brake pressure control valves are in the return position the wheel brakes 13, 14, 16 or 17 controlled by these via a circulating flow path 49 of the respective brake pressure control valve to a return line 47 or 48 of the Front axle or rear axle brake circuit connected.

There is also a total of 50 as part of the anti-lock braking system designated return pumping device is provided, the two as free piston pumps trained return pumps 51 and 52 includes, which by means of an electric eccentric drive 53 can be driven together. These return pumps 51 and 52 are each about one Inlet check valve 54 and 56 and an outlet check valve 57 and 58, respectively to the return lines 47 or 48 and the main brake lines 37 or 41 of the front axle or the rear axle brake circuit connected so that they are in the pressure reduction phases Anti-lock braking control drained from the respective brake circuit 13, 14 or 16, 17 Brake fluid in the output pressure chamber 18 or 19 of the tandem master cylinder assigned to it Return 21.

Structure and function of the anti-lock braking system explained so far 12 of the brake system 10 can be assumed to be known. From the electronic Control unit 36 to the brake pressure control valves 27 to 30 and to drive the Return pumping device 50 leading control lines are therefore simplicity sake only by output arrows emanating from the control unit 36, which are marked with the corresponding reference numerals are provided, illustrated.

Before in the following on the in the illustrated embodiment according to FIG. 1 implemented type of propulsion control is discussed first the basic structure of the brake booster provided in the context of the brake system 10 11 explains, as far as its special properties for the propulsion control function be exploited.

The tandem master cylinder 21 can be used as one to act on two static brake circuits more common Be designed as a master cylinder, its primary piston 22 can be displaced pressure-tight in a spatially further bore step 61 is performed, which the primary outlet pressure chamber 18 together with the primary piston 22 limited, while the floating secondary piston 26 in a spatially narrower bore step is slidably guided and sealed against this. In one to the - spatially further - bore step 61 subsequent bore step 63, the diameter of which is still is greater than that of the bore step 61 receiving the primary piston 22 a drive piston 64, displaceable in a sealed manner against this further bore step 63 guided and by means of a return spring 66, which is located at the transition stage of Bores 61 and 63 on the one hand and on the other hand on the one facing the primary piston 22 Side of the drive piston 64 is supported, pushed into the basic position shown, in which the drive piston 64 is at a stop step 67 of the tandem master cylinder or the brake booster housing is supported. By the drive piston 64 and the pedal-side end wall 68 of the booster housing is a drive pressure chamber 69 limited, in which the output pressure of an auxiliary pressure source designated as a whole by 70 can be coupled in, which is present at the output 71 of this auxiliary pressure source 70. The control rod 23, on which the brake pedal 24 engages, is against a central bore 75 of the drive piston 64 of the brake booster 11 sealed and displaceable relative to the drive piston 64, so that in the event of a failure of the auxiliary pressure source, they are located directly on the primary piston 22 can support and the tandem master cylinder - operated solely by pedal force remain.

In order to achieve that the can be coupled into the drive pressure chamber 69 The output pressure of the auxiliary pressure source is proportional to the pedal travel and thus to the Expected value of the achievable braking force linked to a certain pedal travel corresponds, is between the pressure outlet 71 of the auxiliary pressure source 70 and its storage container 72 a control valve arrangement 73, 74 switched, whose leading to the storage container 72 Drainage line 76 via a for controlling the propulsion control function to be explained provided 2/2-way solenoid valve 77 leads, as long as the propulsion control is not activated, is in its illustrated basic position 0, the open position, and, when the propulsion control is activated by an electrical output signal the electronic control unit 36 is controlled in its excited position I, in which the drain line 76 is blocked.

The control valve arrangement 73, 74 comprises an auxiliary pressure control valve a pressure-pilot operated throttle valve 73 and as a pilot valve 74 for this throttle 73 a force-controlled throttle valve 74, which has a pedal travel-proportional flow resistance unfolds.

The valve housing 78 of the pressure control valve 73 has a spatially narrower one Bore step 79 and a spatially further bore step 81, which has a conical Seat surface 82 and one between this and the spatially further bore step 81 arranged annular groove 83 merge into one another. The throttle body 84 is three-dimensional further bore step 81 guided pressure-tight and displaceable by means of a spring 86 urged in the direction of the conical throttle seat 82. One of the seats 83 the opposite end face is in turn conical. Within the Throttle housing 78 is through the throttle body 84, a first pressure chamber 87 and a second pressure chamber 88 and a ring room 89 limited. The first pressure chamber 87 is Connected via a back pressure line 91 to the pressure outlet 71 of the auxiliary pressure source 70. This first pressure chamber 87 of the pressure control valve 73 also communicates via a central throttle bore 92 of the throttle body 84 with the second pressure chamber 88 of the Pressure control valve 73. This second pressure chamber 88 is via a further back pressure line 93 connected to the back pressure chamber 94 of the pilot valve 74. The back pressure space 94 of the pilot valve 74 is against its outlet space 96 by a throttle seat 97 discontinued, against which the throttle body 99 is urged by a spring 98, wherein the spring 98 on the one hand on the throttle body 99 and on the other hand through a Pedal actuation displaceable plunger 101 is supported. The outlet space 96 of the pilot valve 74 and the output annular space 89 of the pressure control valve 73 are connected to the control solenoid valve 77 leading section 76 'of the drain line 76 connected. Next is that Output 71 of the auxiliary pressure source 70 via a control pressure line 103 with the Drive pressure chamber 69 of the brake booster 11 connected.

The interpretation of the elements of the auxiliary pressure source explained so far 70, the control valve arrangement 73, 74 and the brake booster 11 is made so that with a normal, d. H. braking that takes place without propulsion control give the following functions, assuming that the auxiliary pressure source 70 deliver a pressure medium output flow of approximately 1 to 3 liters per minute and a hydraulic pump 102 provided for this purpose within the framework of the auxiliary pressure source 70 can generate a maximum output pressure of about 80 bar.

As long as the brake pedal is not yet actuated, the result is pressure medium flow flowing from the outlet 71 of the auxiliary pressure source 70 to the pressure control valve 73 in the first pressure chamber 87 of this valve 73 a dynamic pressure through which the throttle body 84 is shifted somewhat against the restoring force of the spring 86, with an annular Throttle gap between the conical part of the throttle body 84 and the conical Seat surface 82 of throttle housing 78 opens slightly and first pressure chamber 87 in communicating connection with the annular space 89 of the pressure control valve 73 arrives, that via the drain line 76 to the storage container 72 of the auxiliary pressure source 70 communicates. Which is in the equilibrium position of the throttle body 84 Back pressure building up in the first pressure chamber 87 of the pressure control valve 73 is divided Via the throttle bore 92 of the throttle body 84 to the second pressure chamber 84 and above the back pressure line 93 with the back pressure chamber 94 of the pilot control throttle valve 74, the throttle body 99 thereby lifts from its seat, so that pressure medium from the back pressure chamber 94 overflow into the output chamber 96 of the pilot control valve 74 and from there over the output line 104 to the drain line 76 and thus to the reservoir 72 of the Auxiliary pressure source can flow away.

Under the positions of the dynamic equilibrium Throttle bodies 88 and 99 of the valve arrangement 73, 74 result in the first pressure chamber 87 of the pressure control valve 73 and thus also at the outlet 71 of the auxiliary pressure source 70 a back pressure of about 5 bar, which is insufficient to drive piston 64 of the To move the brake booster 11 against the action of the return spring 66, so that the wheel brakes 13, 14, 16 and 17 are not actuated either.

The brake pedal 24 is now in the sense of a brake pressure build-up operated, so the throttle body 99 of the pilot valve 74 is in the direction of the throttle seat 97 pushed, with the result that under the aforementioned flow conditions the back pressure in the back pressure chamber 94 of the pilot valve 74 and thus also in the second Pressure chamber 88 of pressure control valve 73 increased. The throttle body 84 of the pressure control valve 73 is thereby in turn urged against the throttle seat 82, with the result that the back pressure also rises in the first pressure chamber 87 of the pressure control valve 73 and accordingly also at the outlet 71 of the auxiliary pressure source 70 and thus also in the drive pressure chamber 69 of the brake booster, whereby the restoring force of the restoring spring 66 is overcome and through the associated displacement of the drive piston 64, the desired one Braking assistance is achieved. The resulting braking force is dem Pedal travel always proportional. The one in the drive pressure chamber 69 of the brake booster 11 maximum achievable working pressure is slightly lower than - theoretically - Maximum output pressure of the hydraulic pump 102, since the annular throttle gap between the throttle body 84 and the housing 78 of the pressure control valve 73 never completely closes.

Occurs on one or more of the driven vehicle wheels Spin tendency on what the electronic control unit 36 from the evaluation detects the wheel speed sensor output signals, the control unit 36 generates a Output signal through which the 2/2-way solenoid valve is controlled into its blocking position I. as well as control output signals through which those brake pressure regulating valves whose connected wheel brakes should not be activated in their locked position I controlled.

As a result of the transition of the solenoid valve 77 into its blocking position the outlet flow rate normally acting as a bypass to the control pressure line 103 89, 76, which leads from the pressure outlet 71 to the tank 72 of the auxiliary pressure source, interrupted, with the result that in a propulsion control phase in the drive pressure chamber 69 of the full output pressure of the hydraulic pump 102 is available and thus in the tandem master cylinder 21 the one required to activate the wheel brakes on the spinning vehicle wheels Brake pressure is built up quickly.

The F i g. 2, to the details of which reference is now made, shows a simple modification of the FIG. 1 explained propulsion control device in the event that pressure is applied to the brake system in a propulsion control phase 10 is to take place from a pressure accumulator 106. Instead of the 2/2-way solenoid valve 77 of FIG. 1 a control valve designed as a 4/2-way solenoid valve 107 is used, in its illustrated basic position 0 the output 71 of the auxiliary pressure source 70 against the pressure accumulator 106 is shut off and the annular space 89 of the pressure control valve 73 via a flow rate 108 of the control valve 107 to the storage container 72 of the auxiliary pressure source 70 is connected. Incidentally, it is precisely the one based on the F i g. 1, the structure of the brake system 10 is assumed.

In the one assumed when activating the propulsion control energized position 1 of the control valve 107 is now the memory above the alternative Flow path 109 to the pressure outlet 71 of the auxiliary pressure source 70 and via the control pressure line 103 connected to the drive pressure chamber 69 of the brake booster 11, on the other hand now the annular space 89 of the pressure control valve 73 against the reservoir 72 of the Auxiliary pressure source 70 is complete.

The function of the brake system with storage operation is then in principle exactly the same as explained with reference to FIG. The pressure in the pressure accumulator 106 is monitored with the help of a pressure switch 111, which sends a signal to load the Pressure accumulator 106 triggers.

if in this the pressure falls below a minimum threshold value. By the output signal of this pressure switch, the control valve 107 is in its excited position I and at the same time all brake pressure control valves 27 to 30 controlled in their locked position. As a result, as long as the output signal of the pressure switch 111 is pending, the hydraulic pump 102 of the auxiliary pressure source 70 in the pressure accumulator works and charges it until the output signal of the pressure switch 111 drops again and thus the brake pressure regulating valves return to their basic position - the pressure build-up position - fall back. It is useful to have a not shown Provide overpressure valve through which the accumulator 106 can blow off, if the accumulator pressure should get too high.

In the following, with reference to FIGS. 3, on their details now expressly referred to, a special design of a in the context of Brake system 10 usable brake booster 11 'explains the possibility offers, in the event of a failure of the hydraulic pump 102, nevertheless with power assistance to brake, namely with the output pressure provided for the propulsion control Pressure accumulator 106.

The brake booster 11 'differs from the brake booster 11 according to FIG. 1 by an elongated design of the housing part arranged on the pedal side 112, in the bore 113 of which is designated a total of 114 as the drive piston Ring piston is guided pressure-tightly displaceable within this housing part 112 a drive pressure chamber 69 according to FIG. 1 functionally corresponding drive pressure chamber 116, between its two flanges 117 and 118 an annular space 119 and between its one flange 118 and one end wall 121 of the tandem master cylinder housing a further space 122 delimits in which the piston 114 in its rear Basic position urging return spring 123 is arranged. The in the embodiment according to FIG. 3 correspondingly extended control rod 23 ', which is located directly on the Primary piston 22 of the in FIG. 3 otherwise no longer shown tandem master cylinder 21, which can have essentially the same training as in the embodiment according to FIG. 1, is supported.

passes through a central bore 125 of the annular piston 114 and is sealed against this in the manner shown.

The brake booster 11 'is, for the sake of simplicity, based on Its special functional properties are explained, which also make up its Structural features that can be implemented in different ways result: Falls for some reason the auxiliary power support is off, so when actuated of the brake pedal, the control rod 23 'according to FIG. 3 moved to the left, creating a Ball seat valve 126 is pushed open, via which now the through the piston flanges 117 and 118 bounded annulus 119 via a transverse channel and a longitudinal channel of the Control rod 23 'and a further check valve 127 with the drive pressure chamber 116 of the brake booster 11 'communicates.

This causes the piston 114, which extends over a stop ring 128 supported on the control rod 23 ', acted upon with auxiliary pressure, whereby the annular piston 114, according to FIG. 3 moved to the left and the control rod 23 'over the stop ring 128 takes away. It can still do so even if the auxiliary pressure source fails be braked with the assistance of an assistant. The design explained so far of the brake booster 11 'also has the advantage that in cases where only little pressure medium in the first drive pressure chamber 116 of the brake booster 11 'would be fed, e.g. B. because another one connected to the auxiliary pressure source Consumers 'used up' too much working medium, but quickly achieved the desired braking effect entry.

The check valve 127 also prevents that in the event of exhaustion of the pressure accumulator 106, it is assisted by a normal assistant Braking is charged and thus pressure medium would be "consumed" for the achievement the required braking effect is required.

Since the brake booster 11 'provided by the flanges 117 and 118 of the annular piston 114 limited space 119 constantly to a high pressure source, namely the memory 106 is connected, care must also be taken to ensure that that leakage oil which emerges from this space 119 can be discharged. Is critical only the side of the piston 114 facing the tandem master cylinder 21 would namely, the gap 122 is filled with pressurized pressure medium, so the annular piston 114 could no longer be moved and consequently also no braking to be triggered. The discharge of pressure medium entering the space 122 takes place via check valves 128 and 129, via which the intermediate space 122 to the Control pressure line leading from the pressure outlet 71 of the auxiliary pressure source to the drive pressure chamber 116 103 is connected to a center tap 131 of these check valves 128 and 129 a buffer memory 132 is also connected, which has the function of braking, d. H. if the one check valve 129 is blocked, via the other check valve 128 possibly flowing out of the intermediate space 122 To be able to accommodate print media. If you no longer brake, it locks under the pressure of the buffer storage 132, the check valve 128 and that of the buffer storage 132 recorded pressure medium can via the check valve 129, which now opens, flow off into the control pressure line 103. The advantage of this construction of the brake booster 11 'consists in avoiding "long" leakage oil lines to the reservoir. A return spring 133 also ensures that the "burping" of the Ball seat valve 126 only takes place from a minimum actuation force. with which the Control rod 23 'is moved if the power assistance failed was. A stop 134 is provided only for the purpose that the return spring 133 cannot be pressed on block.

In the following, with repeated reference to FIG. 1 and their related details on an advantageous embodiment of the brake system received with propulsion control device, in which as an auxiliary pressure source 70 for the brake booster and the propulsion control the hydraulic pump 102 one Can be assumed to be known in terms of structure and function, designated 135 in total Power steering device is exploited.

For the needs-based distribution of the from the hydraulic pump 102 delivered pressure medium flow to the servo steering device 135 on the one hand and the brake booster 11, on the other hand, a distributor valve 136 is provided, about that, if you neither brake nor steer at the same time, part of the from the Pump 102 conveyed pressure medium flow to the control valve 137 of the power steering device 135 and via this in its neutral position - likewise to the storage container 72 the auxiliary pressure source 70 flows back. The valve housing of the distribution valve 136 has a spatially further bore step 138 and a spatially narrower bore step 139, which accommodate a correspondingly stepped valve piston 141. He's through that Action of a return spring 142 pushed into its basic position shown. Of the Valve piston 141 has a central longitudinal channel 143 and a communicating with this, the piston 141 radially penetrating transverse channel 144. One side of the longitudinal channel outgoing cross channels 146 and 147 open into entrance rooms 148 and

149, which are connected to the pressure outlet 71 of the auxiliary pressure source 70 are. Next is through the valve piston 141 within the smaller bore step 139 of the valve housing limits a reaction pressure chamber 151, which is also connected to the Output 71 of the auxiliary pressure source 70 is connected and via a throttle bore 152 of the valve piston 141 communicates with its longitudinal channel 143. Within the Larger bore step 138 is a further end face through the valve piston 141 Reaction pressure chamber 153 limited, which in turn is connected to the pressure medium inlet of the control valve 137 of the power steering device 135 is connected and via a throttle bore 154 communicates with the transverse channel 144 or the longitudinal channel 143 of the valve piston 141.

Another, depending on the position of the valve piston 141 either with communicating with the entrance space 148 via the transverse channel 144 or - in the basic position of the valve piston 141 against this shut-off outlet pressure chamber 156 - is also connected to the pressure medium input of the steering control valve 137. The valve body of the distributor valve 136 forms between the transverse channel 144 and the outlet pressure chamber 156 a control edge 157, through which a further throttle point is marked, over which, when the valve piston 141 according to FIG. 1 shifts to the right, increasing more pressure medium in the output pressure chamber 156 and from this to the input of the steering control valve 137 can flow. This is in the illustrated basic position of the valve piston Throttle point 157 is completely or almost completely blocked. The valve piston 151 is - against the restoring force of the spring 142 - so far displaceable in extreme cases, that the transverse channels 146 and 147 shut off from the inlet pressure chambers 148 and 149, respectively are.

The distribution valve 136 explained in terms of its structure works as follows: In the illustrated basic position of the distributor valve 136 - and des Pressure control valve 73 - flows when not braked and not steered at the same time is, part of the pressure medium flow conveyed by the pump 102 via the transverse channel 114 and the throttle bore 154 as well as the reaction pressure chamber 153 and via the in the short-circuit flow path of the steering control valve 137 which is open to the normal position to the storage container. Pressure medium through the central channel 143, the throttle bore 152 and according to FIG. 1 right reaction pressure chamber 151 of the distributor valve 136 flows to the pressure control valve 73 and at the same time also to the drive pressure chamber 69 of the brake booster 11 remains under a moderate pressure, which is still is not sufficient to move the drive piston 64 of the brake booster in the actuating direction of the tandem master cylinder 21 to move. Although considerable, if any Quantities of pressure medium can be circulated in the circuit described, takes place no brake pressure build-up takes place. If the servo steering device 135 is actuated, the result is a steady transition of the steering control valve 137 from its shown Short-circuit position in its alternative flow positions. In each of the two The flow position is the reaction space 153 of the distributor valve against the reservoir 72 shut off the auxiliary pressure source, whereby in the reaction pressure chamber 153 a Pressure builds up. This causes the piston 141 of the distributor valve 136 as shown in FIG. 1 shifted to the right. At the same time, the transverse channel 144 comes more and more into communicating connection with the "upper" outlet pressure chamber 156 of the distributor valve, whereby the pressure medium flow of the hydraulic pump 102 more and more - bypassing of the reaction pressure chamber 153 - is passed to the drive cylinder of the power steering 135.

During a braking process, it does not matter whether it is actuated of the brake pedal 24 or triggered by an activation of the propulsion control is, in the reaction pressure chamber 151 of the distributor valve 136 and thus also an increased pressure built up at the pressure outlet 71 of the auxiliary pressure source 70, which is above the control pressure line 103 into the drive pressure chamber 69 of the brake booster is coupled, whereby the auxiliary-assisted brake pressure build-up is achieved will. Due to the displacement triggered by a pressure build-up in the reaction pressure chamber 151 of the valve piston 141 is the flow of pressure medium flowing to the servo-steering device 135 more and more throttled and a larger proportion of the pressure medium flow to the Brake booster 11 directed.

In the brake system 10 according to the invention, the drive circuit is the Brake booster hydraulically separated from the brake circuits and there are both with normal braking as well as with braking caused by the propulsion control the brake circuit (s) involved always in the same way, d. H.

by shifting the master cylinder pistons 22 and 26 with brake pressure applied.

The propulsion control device is particularly suitable for vehicles with four-wheel drive, in a corresponding modification of course also for vehicles with more than two driven axles.

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Claims (11)

Claims: 1. Propulsion control device for a motor vehicle, with a hydraulic dual-circuit brake system, a hydraulic brake booster and a four-channel anti-lock braking system, the wheel speed sensor of which Brake pressure control valves and electronic control unit also for the propulsion control are used, as well as with the further features A by the propulsion control a wheel that tends to spin becomes so far by activating its wheel brake delayed so that the slip of this wheel remains within specified limits, B The brake pressure is applied to the wheel brakes in control phases of the propulsion control taking advantage of an auxiliary pressure source, which also acts as an auxiliary pressure source for the brake booster is provided when braking is triggered by pedal actuation and C is provided for a Braking becomes an output pressure by means of a pedal-operated control valve arrangement the auxiliary pressure source divertable, pedal travel-proportional auxiliary pressure in a drive pressure chamber of the brake booster, in which also in control phases of the propulsion control Pressure from the auxiliary pressure source is coupled in, g e k e n n -drawn by the Combination of the following features: a) all brakes (13, 14, 16, 17) of the Vehicle wheels subject to propulsion control belong to a closed brake circuit; b) the brake booster (11; 11 ') is connected to a drive pressure chamber (69; 116) one-sided limiting drive piston (64; 114) provided mechanically or hydraulically on the primary piston (22) of a tandem master cylinder provided for building up the brake pressure (21) is supported, the primary outlet pressure chamber (18) of which is supported by the primary piston (22) and the secondary piston (26) and its secondary outlet pressure chamber (19) the secondary piston (26) are movably limited; c) the drive pressure chamber (69; 116) of the brake booster (11; 11 ') is constantly connected to the pressure outlet (71) of the auxiliary pressure source (70) connected, and there is one of the pressure outlet (71) of the auxiliary pressure source (70) via a pressure control valve arrangement (73, 74) and via a regulating control valve (77; 102) to the storage container (72) leading flow path (91, 73, 74, 104, 77 or 107, 76, 72) is provided, which by activating the control valve (77; 107) by means of a regulation control output signal from the electronic control unit (36) the propulsion control can be shut off, the flow resistance of this Flow path during normal braking - triggered by pedal actuation, where the tax valve (77; 107) its normal position, which is open for this flow path assumes, by pedaling the control valve arrangement (73, 74) in proportionality is changeable to the pedal travel. 2. Propulsion control device according to claim 1, characterized in that that the control valve arrangement as the output stage is a pressure-controlled throttle (73) has, whose inlet pressure chamber (87) to the outlet (71) of the auxiliary pressure source (70) is connected and its outlet space (89) to the regulation control valve (77; 107) line branch (76 ') leading to the storage container (72) of the auxiliary pressure source (70) leading drain flow path (76) is connected, and that in the control pressure chamber (88) the pressure-controlled throttle (73) the output pressure of a pilot valve (74) can be coupled in, which supplies an output pressure proportional to the pedal travel. 3. Propulsion control device according to claim 2, characterized in that that the pilot valve (74) is designed as a force-controlled throttle valve, against which the throttle channel between the inlet pressure chamber (94) and the outlet pressure chamber (96) limiting throttle seat (97) a throttle body (99) is pushed over a spring (98) against one by pedaling towards the throttle seat (97) displaceable plunger (101) is supported. 4. Propulsion control device according to claim 3, characterized in that that the throttle (73) used as an auxiliary pressure control valve as a throttle body the control pressure chamber (88) against the inlet pressure chamber (87) and the outlet chamber (89), which communicates with the inlet pressure chamber (87) via the throttle gap Has piston (84) which can be displaced in a pressure-tight manner in a bore step (81) of the throttle housing is performed, the cross-section of which is clear, d. H. 5 to 10 times larger than that Cross section of a bore step (79) delimiting the inlet pressure chamber (87) Throttle housing that this throttle body (84) by a pretensioned compression spring (86) is pushed in the direction of the throttle seat (82) that the throttle body (84) has a throttle bore (92) via which the inlet pressure chamber (87) with the control pressure chamber (88) communicates, and that the control pressure chamber (88) of the throttle (73) with the inlet pressure chamber (94) of the pilot valve (74) and its outlet space (96) with that of the outlet space (89) of the throttle (73) branch (76 ') of the to the storage container (72) of the auxiliary pressure source (70) leading drain line (76) are connected in a communicating manner. 5. Propulsion control device according to one of the preceding claims, characterized in that within the auxiliary pressure source (70) a hydraulic pump (102) is provided, which develops a maximum output pressure of 60 to 120 bar and at the outlet (71) of the auxiliary pressure source (70) a pressure medium flow of 1 to 31 / min supplies. 6. Propulsion control device according to claim 5, wherein that the hydraulic pump also as an auxiliary pressure source for a hydraulic power steering device or a hydraulic level control of the vehicle is used, characterized in that that a pressure medium output flow of the hydraulic pump (102) to the power steering circuit and the braking force booster circuit (73, 74, 69) dividing Distribution valve (136) is provided that, when the brake system (10) is actuated, the brake booster (11) increased portion of the pressure medium flow and that to the steering aid (135) reducing the flowing portion of this pressure medium output stream. 7. Propulsion control device according to one of the preceding claims, characterized in that the drive piston (64) of the brake booster (11) in one, compared with the primary stage (61) of the tandem master cylinder (21), spatially arranged further bore step (63) of its housing and sealed against it is, wherein the drive piston (64) in a power-assisted actuation the brake system is mechanically supported on an extension of the primary piston (22) and, as long as the brake system is not actuated, by a return spring (66) is held in its basic position, and that in turn is attached to the primary piston (22) supporting control rod (23) displaceable by pedal actuation by a the central bore (77) of the drive piston (64) is sealed against it and is displaceable relative to the drive piston (64). 8. Propulsion control device according to one of the preceding claims 1 to 7, wherein in a propulsion control phase the drive pressurization of the Brake booster from a provided in the context of the auxiliary pressure source, through the hydraulic pump of which is a rechargeable pressure accumulator, characterized in that that as a control valve for the connection of the pressure accumulator (106) to the output of the Auxiliary pressure source (70) or to the drive pressure chamber (69; 116) of the brake booster (11; 11 ') a 4/2-way solenoid valve (107) is provided, which can be triggered by a a braking in the context of the propulsion control generated output signal from its Basic position 0, in which the memory (106) against the output (71) of the auxiliary pressure source (70) shut off and this via the pressure control valve (73) and a flow-through flow path (108) of the regulation control valve (107) to the reservoir (72) of the auxiliary pressure source (70) is connected, can be controlled into its excited position I, in which the Pressure accumulator (106) connected to the output (71) of the auxiliary pressure source (70) and this is shut off from the storage container (72) of the auxiliary pressure source (70). 9. Propulsion control device according to claim 8, characterized in that that a pressure switch (111) monitoring the pressure in the memory (106) is provided which, when the pressure in the memory (106) falls below a minimum threshold value, a charge control signal triggers the brake pressure control valves (27, 28, 29 and 30) in its blocking position and the regulating control valve (107) in its energized position I controls. 10. Propulsion control device according to one of the preceding claims 7 to 9, characterized in that the drive piston of the brake booster (11 ') as an annular piston (114) with two axially spaced apart, piston flanges (117 and 118) sealed against the housing bore (113) is, between which an annular space (119) extends to which the pressure accumulator (106) is connected that the drive piston (114) with a through the pressure acted upon in the annular space (119) in the closing direction Valve (126) is provided, the through an axial. movement of the control rod limited by stops (128 and 134) (23 ') can be controlled into its open position within the drive piston (114), in which the annular space (119) has a transverse channel and a longitudinal channel of the control rod (23 ') and a check valve (127) provided on the control rod (23'), due to the relatively higher pressure in the annular space (119) than in the drive pressure space (116) is acted upon in the opening direction, with the drive pressure chamber (116) in communicating Connection is, and that a check valve is provided that the connection between the outlet (71) of the auxiliary pressure source (70) and the drive pressure chamber (116) blocks when the pressure prevailing in this is greater than that at the outlet (71) the pressure present in the auxiliary pressure source (70). 11 propulsion control device according to claim 10. characterized in that a between the annular piston (114) and the primary piston (22) of the tandem Hauiptzylinders within the bore step of the Brake booster (11 ') remaining space (122) to one for receiving provided by leak oil buffer storage (132) is connected, and that between this buffer store (132) and the space (122) a first check valve (128) and between the buffer storage (132) and the outlet (71) of the auxiliary pressure source (70) to the control pressure chamber (116) leading control pressure line (103) a second check valve (129) are switched, the first check valve (128) through relatively higher Pressure in the space (122) than in the memory (132) and the second check valve (129) due to the relatively higher pressure in the buffer storage (132) than in the control pressure line (103) are each acted upon in the opening direction. The invention relates to a propulsion control device for a motor vehicle, with a hydraulic dual-circuit brake system, a hydraulic brake booster and a four-channel anti-lock braking system and with the other, im Preamble of claim 1 mentioned. generic features A to C. A propulsion control device of this type is described in DE-OS 34 21 776 known and described there using the example of a vehicle that has an all-wheel drive Has.