Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/88—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
  • B60T8/92—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means automatically taking corrective action
  • B60T8/94—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means automatically taking corrective action on a fluid pressure regulator
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/343—Systems characterised by their lay-out
  • B60T8/344—Hydraulic systems
  • B60T8/348—4 Channel systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/42—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition having expanding chambers for controlling pressure, i.e. closed systems
  • B60T8/4275—Pump-back systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
  • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
  • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
  • B60T8/4863—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems
  • B60T8/4872—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
  • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
  • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
  • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
  • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
  • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
  • B60T8/4863—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems
  • B60T8/4872—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems
  • B60T8/4881—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems having priming means

Definitions

• the invention relates to a hydraulic dual-circuit brake system with an anti-lock system and traction control for motor vehicles, in particular passenger cars, of the type defined in the preamble of claim 1.
• Control valves for controlling a wheel slip-dependent brake pressure in the outlet channels are in pairs per brake circuit via a connecting line at the assigned brake circuit outputs of the master brake cylinder, to which the output of the pump element of the return pump acting in the respective brake circuit is also connected.
• the changeover valve of the additional hydraulic unit is arranged in the connecting line between the master brake cylinder and the brake circuit of the drive wheels. In the case of traction control, the changeover valve is switched over, which now disconnects the connection of the brake circuit to the brake circuit output and the brake circuit via a pressure-controlled valve to the output of the
• the means for connecting the one pump element of the return pump to the brake fluid container are formed by a hydraulically controllable 2/2-way valve arranged in the additional unit and a third pump element of the return pump acting as a precharge pump, which are arranged one behind the other between the brake fluid container and the inlet of the pump element.
• the control input of the directional control valve is connected to a brake circuit output of the master brake cylinder. With control pressure at the control input, the directional valve is switched to its blocking position.
• the precharge pump which is designed as a low-pressure pump, now feeds the pump element of the return pump, which is designed as a high-pressure pump and generates a high brake pressure which is present at the input of the control valves.
• This brake pressure is fed into the wheel brake cylinders of the drive wheels via the control valves, and these are braked as a result. If only one drive wheel turns, the control valve which is assigned to the outlet channel for the wheel brake cylinder of the non-slipping drive wheel is transferred to its central position, so that no brake pressure can be built up in the wheel brake cylinder of the non-slipping drive wheel.
• the known dual-circuit brake system is designed exclusively for so-called rear-wheel or rear-wheel-drive vehicles which have a so-called "front-rear" or "black and white” brake circuit division.
• the dual-circuit brake system according to the invention with the characterizing features of claim 1 has the advantage that it can be used for front or front wheel drive vehicles and can also be used for rear or rear wheel drive vehicles without modification.
• the additional constructive effort only consists of an additional electromagnetic switch valve in the additional hydraulic unit, which is identical to the existing switch valve, and a few additional line connections between the master brake cylinder or the additional hydraulic unit and the four-channel hydraulic unit.
• the electromagnetic changeover valves guarantee quick response and have little wear as they have no moving elastic seals.
• the means for connecting the one pump element to the brake fluid reservoir can be formed by a pre-feed pump activated with traction control, which is connected on the input side to the brake fluid reservoir and on the output side via a check valve to the input of the pump element, or by a hydraulically controlled two-way valve, the hydraulic control input of which is connected to a Brake circuit output of the master brake cylinder is connected and which is designed so that it connects the input of the self-priming pump element with the brake fluid reservoir in its uncontrolled basic position and opens this connection in its reversed working position.
• a precharge pump with a pressure relief valve can be arranged in series with the two-way valve or an additional accumulator, possibly with a charge and pressure relief valve the connection between the pressure-controlled valve and the changeover valves can be connected.
• the pressure-controlled valve is designed as a pressure relief valve, and in a bypass to the pressure relief valve, an activation valve is switched on, which blocks the bypass during ASR operation and opens when the brake pedal is actuated.
• this allows the pressure relief valve to be set to maximum pressure in ASR operation and, on the other hand, when the ASR control ends and braking during ASR operation, the brake fluid can quickly flow out of the Radbreras cylinders and from the storage chambers in the return circuit of the pump elements into the Brake fluid reservoir to be emptied. This avoids a shift in the characteristic of the brake pedal and an additional load on the central valves in the master brake cylinder.
• the release valve Since the release valve is in the open position when braking, the changeover valves are monitored for leakage. If there is a leak, the brake pedal will drift.
• the release valve can be controlled electromagnetically or hydraulically. In the latter case, the hydraulic control input of the release valve is connected to a brake circuit output of the master brake cylinder, so that it is always switched over to its open position when the brake pedal is actuated.
• the isolation valve can be replaced by a throttle. Then part of the flow flows through the throttle during ASR operation.
• the same mode of operation with regard to rapid relaxation during braking during ASR operation can be realized in that the means " for connecting the one pump element of the return pump to the
• Brake fluid reservoir is formed by a hydraulically controlled 3/2-way valve with spring return, the hydraulic control input of which is connected to the one brake circuit output of the master brake cylinder. That through that
• 3/2-way valve with the brake fluid container connectable pump element is self-priming.
• the arrangement of the 3/2-way valve is such that it connects the self-priming pump element with the brake fluid reservoir in its uncontrolled basic position and disconnects this connection in its reversed working position and at the same time bridges the pressure-controlled valve between the changeover valves and the brake fluid reservoir.
• a check valve is arranged with the flow direction directed towards the input of the pump element, which prevents a negative pressure in the wheel brake cylinders connected to the suction pump element.
• the two changeover valves When braking during ASR operation, the two changeover valves remain activated for a few milliseconds, while the 3/2-way valve is switched over by the brake pressure built up in the master brake cylinder. By bridging the pressure-controlled valve, the brake fluid volume preloaded in the wheel brake cylinders is immediately relieved in the direction of the brake fluid reservoir. Compared to the ⁇ previously described embodiment with
• Isolation valve in the bypass to the pressure-controlled valve is a constructive simplification achieved by saving the said isolation valve.
• a pressure switch with a preselectable pressure response threshold is connected to the connection between the pressure-controlled valve and the changeover valves, the electrical closing contact of which lies in a warning device, the tightness of the changeover valves can be continuously monitored in a simple manner. This is important insofar as the brake circuit separation is canceled if both changeover valves leak. If at least one changeover valve is leaking, the pressure switch responds with each braking operation and switches on the warning device. The time between the application of the brake pedal and the signal from the
• Warning device passes is a measure of the degree of leakage of the switching valve or valves.
• Fig. 1 is a block diagram of one and 2 dual-circuit braking system with a diagonal
• FIG. 3 shows an additional module for modification to 5 of the dual-circuit brake system in FIG. 2.
• Fig. 6 is a block diagram of a modified
• the hydraulic dual-circuit brake system shown in FIG. 1 with a diagonal brake circuit division, anti-lock system (ABS) and traction control system (ASR), also called propulsion control, is shown as an example for a front-wheel drive passenger car.
• the wheels of the motor vehicle are labeled VL (front left), HR (rear right), HL (rear left) and VR (front right).
• the wheel brake cylinders assigned to these wheels are designated by 10.
• the wheel brake cylinders 10 of the wheels VL and HR on the one hand and the wheel brake cylinders 10 of the wheels HL and VR on the other hand each belong to a separate brake circuit.
• the dual-circuit brake system includes, in a manner known per se, a master brake cylinder 11 which has separate brake circuit outputs 12, 13 for connecting one of the two brake circuits in each case and is connected to a brake fluid reservoir 14.
• a brake pedal 15 When a brake pedal 15 is actuated, an equal brake pressure is controlled in the brake circuits via the two brake circuit outputs 12, 13.
• the dual-circuit brake system also includes a four-channel hydraulic unit 16 which has four outlet channels 21-24, to each of which a wheel brake cylinder 10 of the wheels VL, HR, HL and VR is connected.
• Each outlet channel 21-24 is assigned a control valve 25-28 designed as a 3/3-way solenoid valve with spring return, which is controlled by control electronics 30 and builds up a brake pressure dependent on wheel slip in the associated wheel brake cylinders 10.
• the control valves 25 - 28 are connected via an additional hydraulic unit 31 to the two brake circuit outputs 12, 13 of the master brake cylinder 11, the control valves 25 and 26 and the control valves 27 and 28 each being located on the same brake circuit output 12 and 13, respectively.
• control valve 25 is connected to the brake circuit output 12 of the master brake cylinder 11 by means of a connecting line 17 leading via the additional hydraulic unit 31 and the control valve 26 via a direct connecting line 18, while the control valve 27 via a direct connecting line 20 and the control valve 28 via a via the additional hydraulic unit 31 leading connecting line 19 are on the brake circuit output 13 of the master cylinder 11.
• Four-channel hydraulic unit 16 has two pump elements 32, 33, which are driven together by an electric motor 34.
• the pump elements 32, 33 serve to return brake fluid from the wheel brake cylinders 10 in the master brake cylinder 11 when the pressure in the brakes is reduced.
• one pump element 32, 33 is effective in a brake circuit and is connected on the input side to a working connection of the two control valves 25, 26 and 27, 28, each associated with a brake circuit, and on the output side to the connecting line 17 or 19 to the master brake cylinder 11.
• a pump inlet valve 35 and a pump outlet valve 36 are arranged before and after each pump element 32 and 33.
• Low-pressure storage chambers 37 allow a pressure reduction regardless of the pump delivery rate and overcome the opening pressure of the pump inlet valves 35.
• the control valves 25-28 are designed in a known manner so that in their first, non-excited valve position an unobstructed passage from the connecting lines 17 ' - 20 to the outlet channels 21-24, whereby the brake pressure controlled by the master cylinder 11 reaches the wheel brake cylinders 10 of the wheels.
• this passage is interrupted, so that the brake pressure applied in the wheel brake cylinders 10 is kept constant.
• the output channels 21-24, and thus the wheel brake cylinders 10 are connected to the pump elements 32, 33, so that brake fluid is pumped out of the wheel brake cylinders 10 again in order to reduce the brake pressure.
• the additional hydraulic unit 31 is used to generate a brake supply pressure with traction control. It has a precharge or prefeed pump 40 designed as a low-pressure pump and two changeover valves 41, 42 and a pressure-controlled valve 47.
• the prefeed pump 40 driven by an electric motor 43 is on the input side with the brake fluid reservoir 14 and on the output side with the Input of the pump element 33 connected.
• the prefeed pump 40 could also be connected on the output side to the input of the pump element 32 instead.
• a check valve 44 is arranged at the outlet of the pre-feed pump 40. In addition, the output of the prefeed pump 40 is via
• Pressure relief valve 45 connected to the input of the prefeed pump 40.
• the identical switching valves 41, 42 are 3/2-way solenoid valves with spring return.
• the changeover valve 41 is switched on in the connecting line 17 and the changeover valve 42 in the connecting line 19 between the four-channel hydraulic unit 16 and the master brake cylinder 11, the first working connection with the control valve 25 and the outlet of the pump element 32 or with the control valve 28 and the outlet of the pump element 33 and the second working connection is connected to the brake circuit output 12 or 13 of the master brake cylinder 11.
• the third working connection of both changeover valves 41, 42 is via a common connecting line 46 and the pressure-controlled valve 47 at the outlet of the
• the pressure-controlled valve is designed as a check valve 47 with a preset opening pressure, the flow direction of which is directed towards the brake fluid container 14.
• Check valve 47 determines the maximum brake pressure in the traction control system (ASR).
• the changeover valves 41, 42 are designed such that they connect the first working connection in its de-energized basic position with the second working connection and their excited working position with the third working connection, so that the connecting lines 17, 19 are switched through in the basic valve position and the outputs in the valve working position of the two pump elements 32, 33 with the Brake fluid reservoir 14 are connected.
• the two changeover valves 41, 42 are controlled by the control electronics 30. They are always switched over together when the control electronics 30 are informed of a drive slip of at least one of the drive wheels VL, VR by wheel slip sensors, not shown here.
• the pump element 33 fed by the pre-feed pump 40 generates high pressure which is applied to the control valves 25 and 28 which are assigned to the outlet channels 21 and 24 for the wheel brake cylinders 10 of the drive wheels VL and VR. If, for example, the drive wheel VL rotates, the control valve 28, which is assigned to the outlet channel 24 for the wheel brake cylinder 10 of the non-slipping drive wheel VR, is driven into the central position, so that the outlet channel 24 is shut off from the high pressure.
• brake pressure is built up in the wheel brake cylinder 10 of the spinning drive wheel VL, which is therefore braked.
• the required brake pressure is set by pressure modulation, which is brought about by switching the control valve 25.
• the control electronics 30 switch the control valve 25 into its end position that can be brought about by maximum current excitation.
• the pump element 32 pumps brake fluid out of the wheel brake cylinder 10 and returns it to the brake fluid reservoir 14 via the changeover valve 41.
• the brake pressure in the wheel brake cylinder 10 of the drive wheel VL is reduced again and the storage chamber 37 is emptied. Then the changeover valves
• both control valves 25, 28 are activated for brake pressure modulation.
• the outlet channels 21 and 24 are to be connected to the wheel brake cylinders 10 of the rear wheels HR and HL and the outlet channels 22 and 23 are to be connected to the wheel brake cylinders 10 of the front wheels VL and VR.
• a memory 48 can also be connected to the connecting line 46, as is indicated in broken lines in the drawing.
• a pressure switch 49 is connected to the connecting line 46, the electrical switch contact is switched on in a warning device.
• the response threshold of the pressure switch 49 is approximately 5 bar. As soon as the pressure in the connecting line 46 exceeds this threshold value, the switching contact of the pressure switch 49 closes, and the warning device (not shown here) outputs a warning signal.
• a commercial brake light switch is expediently used as the pressure switch 49. The driver can continuously monitor the tightness of the two changeover valves 41, 42 by means of this warning device. If at least one of the two changeover valves 41, 42 is leaking, the
• Brake pedal actuation initiated normal braking process in the connecting line 46, a pressure that is greater than the response threshold of the pressure switch 49.
• the time between the brake pedal actuation and the response of the warning device provides information about the degree of leakage of the switching valve or the switching valve 41 or 42.
• the pre-feed pump is omitted in FIG the one storage chamber 37 and that Pump inlet valve 35 is connected to the self-priming pump element 33 and on the input side to the brake fluid reservoir 14, while its hydraulic control input is connected to the brake circuit output 13 of the master brake cylinder 11.
• the two-way valve 51 is switched over and blocks the connection between the brake fluid reservoir 14 and the pump element 33.
• a check valve 52 is directed towards the pump element 33 Flow direction arranged. This check valve 52 prevents a negative pressure in the wheel brake cylinders 10 of the wheels HL and VR when the brake pressure is reduced at the end of the traction control system.
• the dual-circuit brake system according to the block diagram of FIG. 2 corresponds to that of FIG. 1, so that the same components are provided with the same reference numerals.
• the control electronics 30 in turn switch the changeover valves 42, 41.
• the return pump 29 starts up, and the pump element 33 draws brake fluid from the brake fluid container 14 via the two-way valve 51, which is made available to the drive wheel VR via the control valve 28 and to the drive wheel VL via the two changeover valves 42, 41 and the control valve 25 .
• the opening pressure set on the pressure-controlled valve 47 which is designed as a check valve with a set response threshold, limits the maximum pressure of the brake fluid during ASR operation.
• the control valves 25, 28 are actuated by the control electronics 30 and, as required, switched to the different switching positions.
• the wheel brake cylinders 10 As a result, in the wheel brake cylinders 10 the pressure modulation caused by the drive wheels VL, VR, the drive wheels are braked until no more slip occurs. At the end of the control, the wheel brake cylinders 10 of the drive wheels VL, VR are conveyed empty by the pump elements 32, 33 via the pressure-controlled valve 47 to the brake fluid reservoir 14, and then the changeover valves 41, 42 are switched back to their basic position shown in FIG. 2.
• FIG. 3 in order to modify the dual-circuit brake system according to FIG. 2, an additional module is shown in the block diagram, which is switched on between the connection terminals III and IV in FIG. 2.
• This additional assembly comprises on the one hand a pressure relief valve 54, which takes over the function of the pressure limiting valve 47 in FIG. 2, and on the other hand an isolation valve 53, which is arranged in a bypass 55 to the pressure relief valve 54.
• the release valve 53 is designed so that it blocks the bypass 55 in the event of traction slip and opens when the brake pedal is actuated.
• the release valve 53 is designed as a 2/2-way solenoid valve with spring return, which assumes its open position in its uncontrolled basic position, in which the bypass 55 is continuous, and assumes its blocking position in its controlled working position. With traction control, the 2/2-way solenoid valve is controlled so that it is in its
• the Pressure relief valve 54 can be set to the maximum desired brake fluid pressure during ASR operation, since it is short-circuited by the 2/2-way solenoid valve and is only activated during ASR operation.
• the release valve 53 can also be designed as a hydraulically controlled 2/2-way valve with spring return.
• the control input of this two-way valve is then to be connected to a brake circuit output 12 or 13 of the master brake cylinder 11.
• the two-way valve is designed such that it blocks the bypass 55 in its basic position and releases it in its switched-over working position and thus bridges the pressure relief valve 54.
• a throttle or orifice can also be arranged in the bypass 55.
• part of the pump delivery flow then flows out via the throttle or orifice.
• FIG. 4 shows an assembly which consists of an accumulator 56, an accumulator charging valve 57 and a pressure relief valve 58 connected in parallel with the latter.
• This additional module is connected to the terminal IV in FIG. 2 when the delivery capacity of the pump element 33 is not sufficient or when very long brake fluid lines are required between the hydraulic unit 16 and the brake fluid reservoir 14.
• the additional module outlined in FIG. 5 comprising a precharging pump 59 and a pressure relief valve 60 connected in parallel, can be provided, which after the connection between the
• Terminal VV in Fig. 2 is to be connected to these terminals.
• the additional modules in FIGS. 4 and 5 can alternatively also be used if the dual-circuit brake system according to FIG. 2 is modified by means of the additional module according to FIG. 3.
• FIG. 6 shows a modified additional hydraulic unit 31 * in connection with the master brake cylinder II, which can be used instead of the additional hydraulic unit 31 in the dual-circuit brake system according to FIG. 2.
• This additional hydraulic unit 31 'differs from the additional hydraulic unit 31 in FIG. 2 in that the ° hydraulically controlled 2/2-way valve 51 is replaced by a hydraulically controlled 3/2-way valve 61.
• the hydraulic control input of the 3/2-way valve 61 is in turn connected to the brake circuit output 13 of the master brake cylinder 11, while the first of the three controlled 5 valve connections of the 3/2-way valve 61
• Valve port 62 on the brake fluid reservoir 14 the second valve port 63 on the inflow line of the outlet channels 23, 24 of the four-channel hydraulic unit 16 to the self-priming pump element 33 - and thus ⁇ via the low-pressure storage chamber 37 and the
• Pump inlet valve 35 at the input of the pump element 33 - and the third valve port 64 is at the input of the pressure-controlled valve 47.
• the 3/2-way valve 61 is designed so that the first valve connection 62 in the 5 uncontrolled basic valve position with the second
• Valve connection 63 and in the reversed working position is connected to the third valve connection 64.
• the input of the pump element 33 self-priming formed is always connected to 0 to the brake fluid reservoir 14, excess fluid, during the ASR operation of the pump elements 32,33 through the switched switching valves 41,42 and the pressure-controlled valve 47 conveyed back into the brake fluid container 14.
• the brake pedal 15 is actuated during the ASR operation, the 3/2-way valve 61 is reversed by the brake pressure built up in the master brake cylinder 11, while the two changeover valves 41, 42 remain in their working position for a few milliseconds.
• the pressure-controlled valve 47 is bridged and the brake fluid volumes preloaded in the brake circuits during ASR operation are immediately relieved in the direction of the brake fluid container 14 bypassing the pressure-controlled valve 47.
• Braking achieves a quick release during ASR operation, whereby the operational readiness of ABS operation occurs much faster.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Regulating Braking Force (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=25889976

Family Applications (1)

Country Status (6)

Families Citing this family (14)

Family Cites Families (5)

• 1990
  • 1990-09-17 DE DE4029407A patent/DE4029407A1/de not_active Withdrawn
• 1991
  • 1991-01-17 EP EP19910901697 patent/EP0468004A1/de not_active Withdrawn
  • 1991-01-17 KR KR1019910701264A patent/KR920700975A/ko not_active Application Discontinuation
  • 1991-01-17 WO PCT/DE1991/000034 patent/WO1991012162A1/de not_active Application Discontinuation
  • 1991-01-17 JP JP91502191A patent/JPH04505435A/ja active Pending
  • 1991-02-06 PL PL28897591A patent/PL288975A1/xx unknown

Non-Patent Citations (1)

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