DE4443869A1 - Hydraulic auxiliary force braking system for motor vehicle - Google Patents

Abstract

The system sets a brake pedal force proportional auxiliary pressure in an amplifying chamber (1) using an auxiliary pressure pump (206) and brake pressure control valve; in the brake actuation position a connection is made between the amplifying chamber and a pressureless return chamber. A reaction force opposing the braking force is felt on the brake pedal, whereby the pressure side of the auxiliary pressure pump is connected to the amplifying chamber and the suction side to a chamber (3) whose vol. varies with amplifying piston displacement.Displacement of the amplifying piston (8) sets up a low pressure which the medium displaced from the chamber delivers to the auxiliary pressure pump. The auxiliary pressure pump is connected via a multiple-way valve (207) to the amplifying chamber and the variable vol. chamber. The multiple-way valve has a switchable hydraulic connection to a braking circuit.

Description

The invention relates to a hydraulic auxiliary brake plant, in particular for motor vehicles according to the Oberbe handle of claim 1.

An auxiliary brake is already from DE 32 09 337 A1 plant became known, by means of an auxiliary pressure pump and actuated by means of a control piston brake valve an auxiliary pressure proportional to the pedal force a pressure chamber is adjustable. With this auxiliary pressure a downstream master cylinder can be operated. In the Brake release position exists between the pressure chamber and one unpressurized container a connection. With brake application is a reaction opposite to the actuating force Feel the force of the brake pedal. The print side of the auxiliary print pump is on the pressure chamber and the suction side on one Volume of the control piston can be changed ren control chamber connected, the flow rate of the Pump to the volume displaced from the control chamber is bordered. This means that the assistant Support when external pressure is required is generated only when needed, which makes the Duty cycle of the drive motor or that of the motor vehicle on-board power supply reduced work. The one described However, braking system has the disadvantage that the pressure medium supply of the pressure chamber exclusively via the auxiliary pressure pump is possible and also the control chamber volume is limited. Another disadvantage arises due to the size of the braking device due to the complex Arrangement and execution of the individual functional elements. Means for controlling the wheel slip are not suggested gene.

The present invention has therefore ge task makes a hydraulic auxiliary brake system the one genus mentioned above continue to function reliably develop that with simple, inexpensive means un ter all operating conditions and with the lowest possible Energy consumption the respective power requirement of the Bremsan through a correspondingly large range of services from Auxiliary pressure supply is covered, taking one Excess power of the auxiliary pressure pump can be dispensed with can and with simple means a regulation of the wheel hatching is possible.

This object is according to the invention Features of claim 1 solved, according to which the auxiliary pressure pump via a multi-way valve on the booster chamber and on the by moving the booster piston in its volume changeable chamber is connected and the multi-way valve a switchable hydraulic Ver has binding to a brake circuit.

By the measures indicated in the subclaims expedient developments of the invention are given, the in connection with the other features and advantages the invention based on several embodiments games are shown and explained.

Show it:

Fig. 1 a first embodiment of the subject invention with a longitudinal section through the braking pressure generator and the floating piston unit and the associated hydraulic circuit,

Fig. 2 shows an alternative embodiment of the Schwimmkol piston unit,

Fig. 3 shows an alternative to the floating piston unit shown in Fig. 2 with an adapted hydraulic circuit.

The illustration of FIG. 1 is structurally simplifier view of a first embodiment of the invention. The brake system is designed, for example, with a diagonal brake circuit division, in the 2/2-way valves 19 opened in the basic position, to establish a connection to the wheel brakes VL, HR, VR, HL. The housing of the brake pressure sensor 14 has two working pistons 2 , 15 in tandem arrangement, the rod 6 can be actuated by means of a guided in a booster piston 8 pressure 6 . A first, on the booster piston 8 and on the push rod 6 working piston 2 is arranged as a stepped piston with its shaft within a first pressure chamber of the brake pressure sensor 14 , the first pressure chamber being divided into a chamber 3 and a booster piston 8 receiving the booster chamber 1 . This is via a in the direction of the booster chamber 1 opening check valve 7 and the chamber 3 is connected via an inlet valve 17 which is open in the electromagnetically non-energized basic position to a trailing tank 20 . A in the line path 12 and in the electromagnetically non-energized basic position closed check valve 13 separates the booster chamber 1 from the wide ren chamber 3 'in the master cylinder. The suction side of the auxiliary pressure pump 206 is connected via a pressure medium line to the annular chamber 211 of the floating piston assembly 210 , which is connected to the chamber 3 . The pressure side of the auxiliary pressure pump connects to line path 12 . Between the two pressure medium lines leading to the auxiliary pressure pump 206, a multi-way valve 207 is arranged in the basic position for passage, which ensures the above-described pump connections. A bypass line 10 , which is provided with a check valve 16 blocking the floating piston assembly 210 , branches off between the multi-way valve 207 and the auxiliary pressure pump 206 . This bypass line 10 represents an extension of the primary circuit structure, which is why this is shown in dashed lines in the figure.

The push rod 6 is guided within a sleeve-shaped piston section of the booster piston 8 . The United amplifier piston 8 has both the sleeve-shaped Kolbenab section, as well as the enlarged portion of the amplifier piston on a seal, so that the amplifier chamber 1 is leak-free sealed. About a kerbolben between the amplifier 8 and the working piston 2 embedded rubber elastic reaction disk 11 , the Bremsdruckein control takes place in the sense of a useful for the manual actuation characteristic of knight.

The brake pressure control valve 216 is composed as in the extension 220 run piston valve executed, the facing with its end face the working piston 2 to the embedded in the shaft of the working piston 2 reaction disc 11 abuts. For this purpose, the booster piston 8 has a coaxial stepped bore in which the piston slide seals with elastomeric sealing elements. An obliquely the reinforcing piston 8 penetrating channel 230 connects in the brake pedal release position via a pressure medium connection in the brake pressure control valve 216, the chamber 3 with the booster chamber 1st The pressure medium connection in the Bremsdrucksteuerven valve 216 is by means of a merging into the end and peripheral surface of the spool provides bore 231 Herge. The closure function is realized by covering the bore 231 on the sleeve-shaped extension 220 and by the ring seal 232 acting as a seat valve on a piston stage of the brake pressure control valve 216 , which corresponds to a projection in the booster piston 8 . The booster piston 8 is coupled via a driver 217 which engages in the annular groove 218 on the working piston 2 .

Both the two working pistons 2 , 15 receiving Kam mers 3 , 3 'and the annular chamber 211 of the floating piston assembly 210 are also like the wheel brakes VL, HR, VR, HL in the brake release position with at least one after run container 20 in connection. A pressure-balanced connection also prevails between the booster chamber 1 via the open brake pressure control valve 216 with the hold tank 20 .

The operation of the brake system described is explained in more detail below. The starting point for consideration is the brake release position, in which the functional parts are in the position shown in the illustration. The United piston 8 is under the action of the two working pistons 2 , 15 associated compression springs at the rear stop of the brake pressure generator housing 14 , so that the two working pistons 2 , 15 release the sniffer holes leading to the trailing containers 20 . Between the pressure rod 6 and a sleeve-shaped extension 20 fasten th wire ring 233 , a conical spring 234 is effective, which also holds the buttoned on the push rod 6 brake pressure control valve 216 in the open position, so that the booster chamber 1 via the channel 3 leading to the channel 230 of the booster piston 8 has a connection to the after-run container 20 .

A compression spring 212 in the floating piston assembly 210 supports the floating piston 213 at the rear housing stop, so that the annular chamber 211 and the suction side of the auxiliary pressure pump 206 are also connected to the unpressurized chamber 3 via the multi-way valve 207 in the basic position. This ensures pressure equalization for all chambers and working spaces, including the wheel brake cylinders.

If a force is exerted on the push rod 6, so initially 216 moves the brake pressure control valve relative to the working piston 2 and the booster piston 8 in the closed Stel lung in which the Bremsdrucksteuerven TILs reaches the Verbohrungen 231,216 with the shell-side bore 235 in the extension 220 to overlap and Corresponding deformation of the reaction disk 11, the ring seal 232 acting as a seat valve bears against the projection of the booster piston 8 . Pressure medium from the booster chamber 1 cannot consequently escape into the chamber 3 .

The multi-way valve 207 connecting the floating piston assembly 210 to the auxiliary pressure pump 206 is in the electromagnetically non-energized open basic position, so that the pressure required for servo action in the booster chamber 1 also comes about after the auxiliary pressure pump 206 starts up. The auxiliary pressure pump 206 receives (with the inlet valve 17 closed) the volume finally pushed out of the chamber 3 into the annular chamber 211 in proportion to the force of the foot and conveys it into the booster chamber 1 . Moreover, the volume delivery 207 connected in parallel conduction path 10 may for booster chamber 1 by means of the auxiliary pressure pump 206 and the multipath Even til such verbes be sert that when quickly Afterwards, the first brake (panic braking), the necessary increased volume requirement of the Verstär kerkammer 1 can be covered quickly, while the auxiliary pressure pump 206 is still starting and building up pressure. The line cross sections to the booster chamber 1 as well as the cross sections in the multi-way valve 207 are accordingly generously dimensioned. In the bypass line 10 in the direction of the floating piston assembly 210 blocking check valve 16 prevents propagation of the pump pressure in the direction of the pressure medium supply. The by-pass line 10 is an advantageous, but not absolutely necessary, functional measure, which is why a dash-line representation has been chosen in the figure for better illustration of this line path. Due to the large amount of pressure medium already provided via the bypass line 10 in proportion to the force of the intensifier chamber 1 , the auxiliary pressure pump 6 then only has to realize the desired pressure increase with a relatively small required pump delivery flow. The check valve 13 remains during the slip-free brake actuation in its electromagnetically non-energized, closed switching position, so that a leakage of pressure medium from the United pressure circuit in the wheel brake is excluded. Consequently, the standing under the servo effect of the amplifier piston 8 working pistons 2 , 15 the beitskammern located in the Ar pressure medium volume exclusively via the two brake circuits in the electromagnetically non-energized and thus open 2/2-way valves 19 , which in connection with the wheel brakes VL , HR, VR, HL stand.

The described auxiliary brake system is unrestricted and without change to use as slip-controlled Brake system suitable, for which only in the Drucklei tion inserted electromagnetically actuated valves are operated as required.

As soon as the control and regulating electronics 9 detect inadmissibly high brake slip values in the service brake position by means of sensors 7 for detecting the wheel speeds, the brake pressure modulation characterized by pressure maintenance, pressure reduction and pressure build-up phases is activated.

To filter out disturbance variables and thus to generate the pressure holding function in both brake circuit diagonals, the normally open 2/2-way valves 19 are closed electromagnetically, so that a hydraulic locking of the push rod 6 and thus a limitation of the activated ones are effected via the volume blocked in the chamber 3 ' manual brake actuation is effective. The check valve 13 , the multi-way valve 207 and the inlet valve 17 remain in the depicted inactive position, while the auxiliary pressure pump 206 conveys pressure medium to the booster chamber 1 beyond the normal braking mode.

To initiate the pressure reduction phase, while the inlet valve 17 is still closed, the shut-off valve 13 opens the hydraulic connection of the brake circuit normally connected to the chamber 3 'in the direction of the intensifier chamber 1 . The multi-way valve 207 connected to the auxiliary pressure pump 206 is now switched over, so that the pressure side of the auxiliary pressure pump 206 is connected to the annular chamber 211 and to the pressure chamber 4 of the floating piston assembly 210 located opposite the annular chamber 211 . Due to the difference in the end faces on the floating piston 213 , this moves under the action of the pump pressure ent against the compression spring 212 , whereby the chamber 3 for locking the push rod 6 is shut off. The suction side of the pump 206 , however, is via the open shut-off valve 13 with the chamber 3 ', so that the pressure of the chamber 3 ' due to the pressure drop generated by the auxiliary pressure pump is also relieved of the pressure on the working piston 15 , so that even in the connected brake circle the pressure can be reduced in the direction of the trailing container 20 attached to the brake pressure transducer, for which purpose the compression spring resets the working piston 15 .

To implement the pressure build-up phase in the wheel brakes, the multi-way valve 207 is switched back to its basic position, in which it enables the pressure medium to be fed to the suction side of the auxiliary pressure pump 6 via the annular chamber 211 . The floating piston 213 is under the action of the compression spring 212 in its original switching position which connects to the chamber 3 . The pressure side of the auxiliary pressure pump 6 is di via the open check valve 13 di rectly connected to a diagonal brake circuit, so that via the open 2/2-way valves 19 of the wheel brakes VR, HL. di rect pressure medium is supplied, and the fluid delivered by the auxiliary pressure pump 206 via the conduction path 12 is also present in the chamber 3 '. The pressure build-up in the second brake circuit takes place indirectly via the working piston 15 . At the end of the manually controlled Bremsbe actuation phase, the switch positions of a let and shut-off valve 17 , 13 are reversed so that these Ven tiles return to their original basic position.

Another embodiment of the floating piston assembly 210 is shown in FIG. 2. The remaining in Fig. 2 th details of the brake system correspond to the conceptual structure already shown in Fig. 1, so that in the following only explicitly on the structural and circuitry deviations to the floating piston assembly 210 will be discussed.

On the floating piston 213 there is a plunger which, in the basic position, holds a check valve 214 open, so that there is a hydraulic connection from the chamber 3 to the multi-way valve 207 .

In the brake release position, the multiway valve 207 connects the suction side of the auxiliary pressure pump 6 with the floating piston assembly 210th

With the actuation of the push rod 6 , the auxiliary pressure pump 206 starts and the inlet valve 17 remains excited electromagnetic table in the locked position. Foot force proportional ver displaced pressure medium passes from the chamber 3 'via the ge opened check valve 214 of the floating piston assembly to the suction side of the auxiliary pressure pump 206 , and via the bypass line 10 to the booster chamber 1st About the bypass line 10 is initially in the braking phase, the supply of the United booster chamber 1 with a relatively large volume flow guaranteed ge, the auxiliary pressure pump 206 of which promotes a partial flow to the desired, increased pressure level. The working pistons 2 , 15 displace brake fluid to the wheel brakes in accordance with the controlled volume / pressure absorption in the booster chamber 1 .

With the need for modulation of the wheel brake pressure in the sense of a pressure maintenance phase, the 2/2-way valves 19 belonging to the wheel brakes are switched into the blocking position.

To reduce the pressure in the wheel brakes VL, HR, VR, HL, the electromagnetically closed 2/2-way valves 19 and the shut-off valve 13 are opened again and the multi-way valve 207 is switched in its opposite position to the pump suction side, thus relieving the pressure on the pump Wheel brakes VL, HR, VR, HL can perform. The pump pressure side is connected to the annular chamber 211 , so that the floating piston 213 is actuated against the action of the compression spring 212 and the check valve 214 closes. The chamber 3 of the brake pressure sensor is shut off due to the closed inlet valve 17 and prevents further manual actuation of the working pistons 2, 15 . Pressure medium is sucked out of the wheel brakes VL, HR, VR, HL by the auxiliary pressure pump 206 .

For the repeated build-up of wheel brake pressure in the blocking protection mode, the multi-way valve 207 switches back to its basic position, so that the pump pressure side is again connected to the booster chamber 1 and the open valve 13 with a brake circuit. The pressure of the brake circuit diagonal is then transferred via the working piston 15 to the further brake circuit. The pressure medium volume required to supply the auxiliary pressure pump 206 or the booster chamber 1 again passes from the chamber 3 via the open check valve 214 to the pump suction side and via the bypass line 10 directly into the booster chamber 1 .

The embodiment for a three-circuit brake according to FIG. 3 shows a structural and functional expansion of the floating piston assembly according to FIG. 2, according to which a further piston 215 is arranged coaxially to the floating piston 213 , which delimits a support chamber 5 , which is connected to the brake circuit of the rear wheel brakes HR, HL is. Between the other piston 215 and the floating piston 213 , the compression spring 212 is supported within a sleeve-shaped shaft section from the floating piston. On the opposite side of the support chamber 318 of the piston 215 there is also a pressure chamber 18 which connects the working chamber ben 2 assigned to the working chamber 3 'with one of the two front wheel brakes VR (2nd brake circuit). The other front wheel brake is actuated via the working piston 15 (3rd brake circuit). The front wheel brakes VL, VR are controlled individually, but the rear wheel brakes HL, HR are regulated jointly.

The elements shown in the drawing are in the brake release position. With the actuation of the pressure Stan 6 and switching on the auxiliary pressure pump 206 , the pressure medium passes with the inlet valve 17 closed to the chamber 3 via the check valve 214 , the bypass line 10 and via the parallel suction port of the auxiliary pressure pump 206 to the booster chamber 1 . At the same time, however, the pressure side of the pump 206 also applies both rear wheel brakes HL, HR via the opened 2/2-way valve 19 and the support chamber 5 . The piston 215 adjoining the support chamber 5 on the left as well as the floating piston 213 arranged on the right consequently remain in the basic position shown in the illustration, while pressure is built up in the front wheel brakes VR, VL via the working pistons 2 , 15 .

For anti-lock control, the 2/2-way valves 19 are closed electromagnetically in the pressure maintenance phase.

The brake pressure reduction in the front wheel brakes VL, VR takes place after excitation and thus by switching the multi-way valve 207 , with subsequent suction of volu men from the support chamber 5 , whereby the further piston 215 due to its pressure movement 18 increasing stroke movement connected to a front brake VR and the second front wheel brake VL is also depressurized via the working piston 15 . The chamber 3 is locked by the locked position of the inlet valve 17 and the check valve 214 , so that no pressure medium volume can be replenished in the brake pressure transmitter.

To build up brake pressure during the anti-lock control, the multi-way valve 207 switches back to the basic position as shown in the illustration, again leading the direct pump pressure supply to the rear wheel brakes HL, HR and directly via the pressurization of the booster piston 8 and the associated working pistons 2 , 15 into the front wheel brakes VR, VL is made possible. For this purpose, the pistons of the floating piston assembly 210 again assume their basic position according to the illustration.

Reference list

1 booster chamber
2 working pistons
3 , 3 ′ chamber
4 pressure room
5 support chamber
6 push rod
7 sensor
8 booster pistons
9 Control and regulating electronics
10 Baypass line
11 reaction disk
12 conduction path
13 shut-off valve
14 brake pressure transmitter
15 working pistons
16 check valve
17 inlet valve
18 pressure chamber
19 2/2-way valve
20 trailing containers
206 pump
207 multi-way valve
210 floating piston assembly
211 ring chamber
212 compression spring
213 floating pistons
214 check valve
215 more pistons
216 brake pressure control valve
217 drivers
218 ring groove
220 sleeve
230 channel
231 drilling
232 seal
233 wire ring
234 conical spring
235 hole

Claims (12)

1.Hydraulic auxiliary brake system, in particular for motor vehicles, in which an auxiliary pressure proportional valve can be set in an booster chamber by means of an auxiliary pressure pump and by means of a brake pressure control valve which can be actuated in the brake pressure transducer, in which a connection between the booster chamber and an unpressurized follow-up tank is established in the brake release position and in which a reaction force opposite to the actuating force can be felt on the brake pedal, the pressure side of the auxiliary pressure pump being connected to the booster chamber and the suction side of the auxiliary pressure pump being connected to a chamber which can be changed in volume by displacement of the booster piston, and a slight pressure being built up when the booster piston is shifted is, which promotes the pressure medium volume displaced from the chamber to the auxiliary pressure pump, characterized in that the auxiliary pressure pump ( 206 ) via a multi-way valve ( 207 ) on the amplifier arm chamber ( 1 ) and to the chamber ( 3 ), which can be changed in volume by moving the booster piston ( 8 ), and that the multi-way valve ( 207 ) has a switchable hydraulic connection to a brake circuit. 2. Hydraulic auxiliary brake system according to claim 1, characterized in that the Mehrwegeven valve ( 207 ) in a first switching position, the suction side of the auxiliary pressure pump ( 206 ) with the chamber ( 3 ) in the brake pressure sensor ( 14 ) and the pressure side of the auxiliary pressure pump ( 206 ) with the booster chamber ( 1 ) and the switchable connection to the wheel brake circuit. 3. Hydraulic auxiliary brake system according to claim 1 or 2, characterized in that between the multi-way valve ( 207 ) and the chamber ( 3 ), a floating piston unit ( 210 ) is connected. 4. Hydraulic auxiliary brake system according to at least egg NEM of the preceding claims, characterized in that between the pressure side of the auxiliary pressure pump ( 206 ) and the multi-way valve ( 207 ) with a chamber ( 3 ) connectable bypass line ( 10 ) opens, the one has check valve ( 16 ) opening towards the pressure side of the auxiliary pressure pump ( 206 ). 5. Hydraulic auxiliary brake system according to at least egg NEM of the preceding claims 1 to 4, characterized in that in a further switching position of the multi-way valve ( 207 ), the suction side of the auxiliary pressure pump ( 206 ) on the booster chamber ( 1 ) and on the brake circuit leading switchable connection (line path 12 ) is connected, and that the pressure side of the auxiliary pressure pump ( 206 ) with the floating piston unit ( 210 ) is connected. 6. Hydraulic auxiliary brake system according to at least egg NEM of the preceding claims, characterized in that the switchable connection (Lei line path 12 ) has an electromagnetically actuated blocking valve ( 13 ) which is arranged in a branch of a brake circuit. 7. Hydraulic auxiliary brake system according to at least egg NEM of the preceding claims, characterized in that an electromagnetically actuated inlet valve ( 17 ) connects the trailing tank ( 20 ) with the cam mer ( 3 ). 8. Hydraulic auxiliary brake system according to claim 3, characterized in that in a Ringkam mer ( 211 ) of the floating piston assembly ( 210 ) a Druckfe the ( 212 ) is arranged, which is supported between the housing front wall and the floating piston ( 213 ), the further end wall section of the floating piston ( 213 ), which is remote from the annular chamber ( 211 ), can be acted upon hydraulically against the pressure spring effect. 9. Hydraulic auxiliary brake system according to claim 8, characterized in that the floating piston ( 211 ) controls the pressure medium connection between the chamber ( 3 ) and the multi-way valve ( 207 ). 10. Hydraulic power brake system according to claim 3, characterized in that the floating piston beneinheit ( 210 ) has a check valve ( 214 ) which, depending on an in the opening direction of the check valve ( 214 ) effective compression spring ( 212 ) and ent opposite to that on the floating piston ( 213 ) effective compression spring ( 212 ) can be acted upon by a hydraulic pressure force in the closing direction of the check valve ( 214 ) in order to control the connection between the chamber ( 3 ) and the multi-way valve ( 207 ). 11. Hydraulic auxiliary brake system according to claim 9, characterized in that the Druckfe of ( 212 ) on a further piston ( 215 ) within the floating piston assembly ( 210 ) is supported, which on its end facing away from the compression spring ( 212 ) a pressure space ( 18 ), which is connected to the brake circuit leading from the brake pressure sensor ( 14 ) to the front wheel brake (VR). 12. Hydraulic auxiliary brake system according to claim 10, characterized in that the further piston ( 215 ) and the floating piston ( 213 ) limit a support chamber ( 5 ) which can be connected to the rear wheel brakes (HR, HL) and the multi-way valve ( 207 ) is.