JPH04231255A - Hydraulic type two circuit brake gear - Google Patents

Abstract

PURPOSE: To secure sufficient operability even when a large-capacity wheel brake cylinder is used, to fill a brake fluid into the wheel brake cylinder very rapidly and to brake a slipping drive wheel in a hydraulic two-circuit brake device having a skid control system and a traction control system for an automobile. CONSTITUTION: A precharging pump 42 has a sufficient conveying capacity for quickly filling a brake fluid into the wheel brake cylinders 10 of drive wheels 11, 12, and a means is provided to at least partially block the brake fluid filling into low-pressure reservoirs 38, 39 connected to a brake circuit having at least one of drive wheels 11, 12 at least at the start of traction control.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is a hydraulic two-circuit brake system equipped with a skid control system (ABS) and a traction control system (ASR) used in automobiles, in which brake pressure is controlled by brake pedal operation. a master brake cylinder having two separate brake circuit outlets for output control; a brake fluid reservoir connected to the master brake cylinder; and a four-passage hydro unit connected to both brake circuit outlets of the master brake cylinder. is provided, the four-passage hydro unit having four outlet passages divided into two brake circuits for connecting the wheel brake cylinders of the vehicle wheels and supplying the wheel brake cylinders with brake pressure related to wheel slip. An electromagnetic control valve assigned to each one outlet valve for output control and two separate pump elements working in each one brake circuit for returning brake fluid when the brake pressure in the wheel brake cylinder is reduced. , each of which pump elements can be connected on the inlet side via the control valve to the outlet channel assigned to a brake circuit, and on the outlet side a master valve assigned to the brake circuit. connected to the brake circuit outlet of the brake cylinder, the four-channel hydro unit further comprising two low-pressure reservoirs assigned to each one brake circuit for temporarily accommodating brake fluid during brake pressure reduction. each low pressure reservoir is connected to the inlet of each of the pump elements, and an auxiliary hydro unit is provided for forming brake supply pressure during traction control, and the auxiliary hydro unit is connected to the inlet of each of the pump elements on the inlet side. a front charge pump connected to the fluid reservoir, the front charge pump supplying brake fluid to each brake circuit having at least one drive wheel via a check valve during traction control; In addition, the auxiliary hydro unit has a valve unit which, during traction control, controls each pump element of the return feed pump assigned to the brake circuit with at least one drive wheel on the outlet side to a master brake. It relates to a type that is separated from the cylinder and connected to the brake fluid container via a pressure limiting valve.

0002

BACKGROUND OF THE INVENTION In a known two-circuit brake system of this type (German Patent Application No. 3816073) having a front/rear split brake circuit or a front/rear split brake circuit, The outlet of the charge pump is connected to the inlet of a pump element of a return feed pump serving in the brake circuit of the drive wheel. The valve unit has a 3 port 2 position solenoid valve,
Of the three valve connections controlled by this 3-port 2-position solenoid valve, the first valve connection is connected to the outlet of the pump element, and the second valve connection is connected to the drive wheel of the master brake cylinder. A third valve connection is connected to a brake fluid reservoir via a pressure limiting valve. The three-port two-position solenoid valve is such that the first valve connection is connected in the basic position with the second valve connection and in the switching position produced during traction control (ASR function) with the third valve connection. configured to be connected.

During traction control, the front charge pump supplies brake fluid via a switched 3/2-way solenoid valve to the pump element of the return pump, which is assigned to the brake circuit of the drive wheel. This pump element itself abuts the brake tongue and creates a high brake pressure for braking the respective slipping drive wheel.

A two-circuit brake system constructed in this way is designed for wheel brake cylinders which require only a small volume of brake fluid. When large-volume wheel brake cylinders are used, the dynamics of this known two-circuit brake system becomes extremely unsatisfactory. Because of the small volumetric flow provided by the pump element, the filling of the brake fluid into the wheel brake cylinder takes a relatively long time, so that the brake tongue can only be used after an unacceptable dead time.
This is because a slipping drive wheel cannot be braked.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the two-circuit brake system of the type mentioned at the beginning so that the above-mentioned drawbacks are avoided and the power is improved even when using large-volume wheel brake cylinders. To provide a two-circuit brake device in which a wheel brake cylinder is sufficiently filled with brake fluid, and a slipping drive wheel can be quickly braked.

[0006]

In order to achieve this object, the present invention provides that the front charge pump has a sufficient conveying volume for rapid filling of the wheel brake cylinders of the drive wheels with brake fluid. and means are provided for at least partially preventing the filling of brake fluid into a low-pressure reservoir connected to a brake circuit with at least one drive wheel, at least at the beginning of the traction control.

[0007]

The two-circuit brake system according to the present invention has the following advantages over the conventional brake system. That is, for wheel brake cylinders, especially those with extremely large brake fluid volume requirements,
During traction control operation, the large transport flow of the front charge pump makes it possible to fill the brake fluid extremely quickly. Because the filling of the brake fluid into the low-pressure reservoir, which is necessary for rapid brake pressure reduction, is at least partially prevented, the dynamics and precharging pressure of the wheel brake filling process are significantly improved. This results in better utilization of the output performance of the precharge pump. Not filling the low-pressure reservoir with brake fluid, or at most only partially filling it, also has the following advantages: That is, the transition from the ASR function to the ABS operation can be performed extremely quickly. This is because the low pressure reservoir still has sufficient storage volume to accommodate brake fluid during brake pressure reduction.

[0008] The two-circuit brake device according to the present invention
Suitable for both rear axle split brake circuits and diagonal split brake circuits.

[0009] The measures described in the following claims make it possible to advantageously improve the two-circuit braking device according to claim 1.

[0010] In an advantageous embodiment of the invention, the precharge pump is connected during traction control on the one hand via a check valve to the respective brake circuit with a pump element of a return pump assigned to at least one drive wheel. On the other hand, it is directly connected via a second check valve to a control valve which is assigned to the outlet channel for the wheel brake cylinder of the drive wheel. Due to this parallel supply of the brake fluid volume to the wheel brake cylinders, a very rapid pressure profile is thereby achieved. In this case, the shift volume required for the initial application of the brake tongs is supplied directly from the front charge pump to the wheel brake cylinder, so that it does not have to be conveyed by the return feed pump.

[0011] In a further advantageous embodiment of the invention, the means for at least partially preventing the filling of brake fluid into the reservoir at the start of the traction control have a sensor, the sensor comprising at least one detecting the sliding distance of a reservoir piston of a low-pressure reservoir assigned to the brake circuit with the drive wheel, or detecting the reservoir pressure of this low-pressure reservoir and shutting off the front charge pump if a set value is exceeded; It has become. The cut-off time is set in such a way that the low-pressure reservoir is only partially filled with brake fluid, which also allows a faster transition from ASR to ABS operation.

[0012] In a further advantageous embodiment of the invention, the means for preventing brake fluid from entering the reservoir have a check valve, which check valve is connected between each low-pressure reservoir and the associated pump element. is arranged with a blocking direction toward the low pressure reservoir. The low-pressure reservoir and the pump element belong to a brake circuit with at least one drive wheel. This ensures that the low-pressure reservoir is completely isolated from the precharge pump at the start of the ASR function and cannot be filled with brake fluid by this precharge pump. That is, this results in improved dynamics in brake pressure build-up during ASR operation and
This means that a rapid pressure reduction can be obtained both at the end of R operation and at the transition to ABS operation. This is because the low pressure reservoir is completely empty in any case.

A further advantageous refinement of the invention provides that the delivery power of the front charge pump is reduced after the wheel brake cylinder of the drive wheel has first been filled with brake fluid, which means that: This is achieved, for example, by pulsed control of the precharge pump. A.S.
At the start of the R function, the full power performance of the front charge pump is utilized, in which the front charge pump generates a conveying flow of, for example, approximately 30 cm3/s and is directly and quickly applied to the wheel brake cylinder. Approximately 1
Apply a preload of 0 bar. After the first brake fluid filling into the wheel brake cylinders, which takes approximately 100 ms, the precharge pump is reduced in its delivery power by means of a pulsed control. The conveying flow of approximately 5 cm 3 /s generated in this case is sufficient to feed the return feed pump. Due to the pulsed control of the precharge pump, this precharge pump does not have to be designed for continuous operation. Significantly smaller motors can be selected, which saves both construction volume and manufacturing costs.

[0014] In a further advantageous embodiment of the invention, each pump element of the return feed pump, which is assigned to the brake circuit with at least one drive wheel, is connected on the inlet side via a supply line with a check valve. and is connected to the outlet of the front charge pump, which is connected to the brake fluid container. In this case, the means for preventing the filling of brake fluid into the reservoir comprises a switching valve arranged in each supply conduit, which switching valve connects the inlet of the pump element to the corresponding low-pressure reservoir in its basic position. and in its switching position, which occurs during ASR operation, to the front charge pump. In such an arrangement, the low-pressure reservoir assigned to the brake circuit with at least one drive wheel is completely isolated from the corresponding brake circuit during the entire traction control period. The pressure reduction during ASR operation takes place directly in the brake fluid reservoir via a return pump and a valve unit. This allows an extremely quick transition from ASR operation to ABS operation. This is because the low-pressure reservoir is reliably emptied when the ABS function is engaged. This allows AB
During pressure reduction in S operation, a lower wheel brake cylinder pressure is obtained. The supply of brake fluid by the precharge pump takes place only via the corresponding pump element of the return pump and additionally does not take place directly via the check valve to the control valve. This eliminates the risk that, in the event of a failure of the check valve, part of the brake fluid supplied from the master brake cylinder will flow into the precharge circuit during the braking process carried out by operating the brake pedal.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a block circuit diagram of a front/rear split type or front/rear axle split type brake circuit used in passenger cars, a skid control system (ABS), and a traction control system also called a front drive control system. In a hydraulic two-circuit brake system equipped with (ASR), the drive wheel 11
, 12 wheel brake cylinders 10 are arranged in one brake circuit, and the wheels 13 which are not driven are
, 14 wheel brake cylinders 10 are arranged in the other brake circuit. In this case, the drive wheels 11, 12 are generally the rear wheels of a passenger car. A master brake cylinder 15 is assigned to this two-circuit brake system in a known manner. This master brake cylinder has two separate brake circuit outlets 16, 17 for connecting one of the two brake circuits in each case and is connected to a brake fluid reservoir 18. When the brake pedal 19 is actuated, an equal amount of brake pressure is output to the brake circuit via both brake circuit outlets 16, 17.

The illustrated two-circuit brake system further includes four circuits.
A passage hydro unit 20 belongs thereto, and this four passage hydro unit has four outlet passages 21, 22, 23,
24 and two inlet passages 25, 26. Each outlet passage 21, 22, 23, 24 has a wheel 11,
12, 13, and 14 wheel brake cylinders 10 are connected. Each outlet channel 21, 22, 23, 24 is assigned a control valve 31, 32, 33, 34, which is designed as a three-port, three-position solenoid valve with a spring return position. These control valves 31 , 32 , 33 , 34 are controlled by an electronic control device (not shown) to create a wheel slip-related brake pressure in the corresponding wheel brake cylinder 10 . 4 passage hydro unit 20
The return feed pump 27, which is a component of the pump 27, has two pump elements 28, 29, which are driven together by a motor 35. Pump elements 28, 29 serve to transport brake fluid back during brake pressure reduction. One pump element 28, 29 in each case is activated in one brake circuit and on the inlet side is connected to a wheel 11, 12, 13, 13 of the vehicle via a control valve 31, 32 or 33, 34, which is respectively assigned to the same brake circuit. is connectable to
It is connected to the inlet passage 25 or 26 of the four-pass hydro unit 20 on the outlet side. Each pump element 28
, 29, a pump suction valve 36 and a pump discharge valve 3
7 are arranged. Undriven wheel 13,1
A low-pressure reservoir 38 is directly connected on the inlet side to the pump suction valve 36 of the pump element 28, which acts on the brake circuit of the drive wheels 11, 1.
A low-pressure reservoir 39 is connected to the pump suction valve 36 of the pump element 29 acting on the second brake circuit via a check valve 41 having a shutoff direction towards the low-pressure reservoir 39 . A damping chamber 30 is located between the pump delivery valve 37 and the inlet channel 25 or 26 in each case.

The control valves 31, 32, 33, 34 are
The second valve connection is connected in pairs to the inlet channel 25 or 26 assigned to one brake circuit, and the corresponding outlet channel 21, 22 is connected in its second valve connection in pairs to the inlet channel 25 or 26 assigned to one brake circuit.
. The third valve connection of the control valves 33, 34 directly connects the pump suction valve 3 of the pump element 28 to the pump suction valve 36 of the pump element 29.
6 is connected. The control valves 31, 32, 33, 34 are constructed in a known manner, in this case in a first position,
That is, in the non-energized basic position, the inlet passage 25,
26 to the outlet passages 21, 22, 23, 24, and thereby the brake pressure output-controlled from the master brake cylinder 15 is transferred to the wheels 11, 1.
2, 13, and 14 into the wheel brake cylinders 10. In the second valve intermediate position, produced by the excitation of the control valves 31, 32, 33, 34 with half-maximum current, the flow is interrupted and all valve connections are blocked, so that the wheel The brake pressure built up in the brake cylinder 10 is kept constant. In the third valve end position produced by the valve excitation with maximum current, the outlet passages 21, 22 or 23, 24 and thus the wheel brake cylinders 10 of the wheels 11, 12, 13, 14 are in the low-pressure reservoir 38, 39. and the inlets of the pump elements 28, 29, so that the brake fluid flows from the wheel brake cylinders to the low pressure reservoirs 38, 3.
9 and is thereby transported back to the master brake cylinder 15 via the inlet passages 25, 26 by the pump elements 28, 29. In order to connect the master brake cylinder 15 and the four-channel hydro unit 20, the inlet channel 25 of the four-channel hydro unit 20 is connected via a first connecting conduit 51 to the brake circuit outlet 16 of the master brake cylinder 15. The inlet channel 26 is then connected via a second connecting conduit 52 to the brake circuit outlet 17 of the master brake cylinder 15 .

The auxiliary hydro unit 40 serves to create brake supply pressure during traction control (ASR) operation. The precharge pump 42 , which is configured as a low-pressure pump, is connected on the inlet side to the brake fluid reservoir 18 and on the outlet side via a supply line 43 to the auxiliary hydro unit 40 and also to the drive wheel 1 .
It is connected to the pump suction valve 36 of the pump element 29 assigned to the brake circuits 1 and 12. Furthermore, a valve unit 44 is assigned to the auxiliary hydro unit, and this valve unit is used for traction control operation (A
During SR operation), the pump element 29 assigned to the brake circuit of the drive wheels 11 , 12 is disconnected from the master brake cylinder 15 and connected via the pressure limiting valve 45 to the brake fluid reservoir 18 . Mainly valve unit 4
4 has a switching valve 46 configured as a 3-port 2-position solenoid valve with a spring return position, which switching valve 46 is connected at its first valve connection to the inlet passage 26 of the 4-channel hydro unit 20. It is connected with its second valve connection to the brake circuit outlet 17 of the master brake cylinder 15 and further connected with its third valve connection to the pressure limiting valve 45 . The switching valve 46 connects the first connection in its deenergized basic position with a second connection and in the switching position produced during traction control operation with a third connection. The outlet of the pressure limiting valve 45 is connected directly to the brake fluid reservoir or, as in this case, to the outlet of the front charge pump 42 , in which case the front charge pump 4
2 is connected in parallel with a second pressure limiting valve 47 whose opening direction is directed toward the brake fluid container 18 . The opening pressure of this second pressure limiting valve 47 is set to a value several times lower than the opening pressure of the first pressure limiting valve 45, for example 20 bar compared to 250 bar of the first pressure limiting valve 45. .

In order to obtain a high dynamicity of the brake pressure supply in ASR operation, the front charge pump 42 has a sufficient delivery power for rapid filling of the wheel brake cylinders 10 of the drive wheels 11, 12 with pressure medium. Because of this, the precharge pump can utilize a large transport volume. Supply conduit 4 with check valve 48
In addition to the connection between the front charge pump 42 and the pump suction valve 36 of the pump element 29, which is produced via 3, the front charge pump 42 can be connected directly to the drive wheel via a check valve 49 during traction control. It is connected to the second valve connection of the control valves 31, 32 for 11, 12. For this purpose, the check valve 49 is connected to the pressure limiting valve 45.
between the outlet of the front charge pump 42 and the third valve connection of the switching valve 46, which is configured as a 3/2-way solenoid valve, with a direction of flow toward this switching valve. It is connected to the. Therefore, during ASR operation,
The precharge pump 42 supplies the pressure medium on the one hand to the check valve 49
and the control valves 31, 32 directly to the drive wheel 11.
, 12 and, on the other hand, via the check valve 48 and the pump suction valve 36 to the pump element 29 of the return pump 27. This pump element itself is connected via control valves 31, 32 to the wheel brake cylinders 1 of the drive wheels 11, 12.
Serves to fill 0 with pressure medium. The supply of brake fluid to the wheel brake cylinders 10 of the drive wheels 11 , 12 by the front charge pump 42 takes place until the pressure in the pump element 29 is greater than the pressure created by the front charge pump 42 . The check valve 49 then closes and the brake pressure is applied to the pump element 2.
It can only be adjusted by 9. Front charge pump 4
In order to optimally supply brake fluid to the pump element 29 by 2, the supply conduit 43 has a diameter of approximately 6 to 8 mm.

As shown in FIG. 1, the valve unit 44 can additionally have a charging valve 50, which is connected to the supply line 43 and which is connected to the supply line 43 when the brake pedal is actuated. shut off, thereby decoupling the precharge pump 42 from the inlet of the pump element 29 of the return feed pump 27. The charge valve 50 is in this case configured as a pressure-controlled 2-port 2-position valve with a spring return position, the hydraulic control inlet of which is connected to the brake circuit outlet 17 of the master brake cylinder 15. It is connected to the. The non-return valve 48 located in the supply conduit 43 is advantageously integrated into the charging valve 50, in which case said non-return valve, in its deenergized basic valve position, extends continuously into the supply conduit 43. It is connected. brake pedal 19
As soon as the master brake cylinder 15 is actuated, a brake pressure is outputted to the master brake cylinder 15 which causes the switching of the charge valve 50 and thus the interruption of the supply line 43. This charge valve 50 has the advantage that failure of the check valve 48 does not impair the ABS function.

The switching valve 46 of the valve unit 44 is controlled by an electronic control device (not shown), in which case the electronic control device controls the drive slip of at least one of the drive wheels 11, 12. It is switched when notified by a wheel slip sensor (not shown). The activated precharge pump 42 then supplies brake fluid flow to the brake circuits of the drive wheels 11,12. This brake fluid flow enters the pump element 29 on the one hand via the check valve 48 and the pump suction valve 36, and on the other hand via the check valve 49 and the switched switching valve 46 directly into the control valve. 31, 32 and from there into the wheel brake cylinders 10 of the drive wheels 11, 12. As a result, the large required brake fluid volume of the wheel brake cylinder 10 is filled very quickly and the brake tongue can be quickly applied. As soon as the pressure generated by the pump element 29 is greater than the precharge pressure of the precharge pump 42, a direct brake fluid supply from the precharge pump 42 to the wheel brake cylinder 10 takes place via the check valve 49. ends. Next, check valve 4
9 is closed and the front charge pump 42 is connected to the drive wheel 11.
, 12 brake circuits.

For example, if only the drive wheel 11 is slipping, the control valve 32 of the drive wheel 12 that is not slipping is shifted to the valve intermediate position, so that the outlet passage 22
is cut off from the brake pressure supply. Via the other control valve 31, a brake pressure is built up in the wheel brake cylinder 10 of the slipping drive wheel 11, so that this drive wheel is braked. The required brake pressure is regulated by a pressure regulation carried out by switching the control valve 31. Excess brake fluid is conveyed back to the brake fluid container 18 via the switching valve 46, the pressure limiting valve 45, and the pressure limiting valve 47. At the end of the traction control, ie when no drive slip is detected anymore, the electronic control unit switches the control valve 31 into the valve end position produced by maximum current excitation. In this position of the control valve 31, brake fluid flows from the wheel brake cylinder 10 into the low pressure reservoir 39. Since this low-pressure reservoir 39 is completely emptied, the brake pressure in the wheel brake cylinder 10 is reduced very quickly. The pump element 29 itself conveys brake fluid from the low-pressure reservoir 39 via pressure limiting valves 45 , 47 to the brake fluid reservoir 18 . Low pressure reservoir 39 is emptied. To ensure this, the difference formed between the opening pressure of the pressure limiting valve 47 and the pressure drop of the check valve 48 must be equal to the response pressure of the low pressure reservoir 39 and the pressure drop of the low pressure reservoir 39.
is smaller than the difference formed by the pressure drop of the pump suction valve 36 of the pump element 29 and the blocking check valve 41, the pressure limiting valve 47, the check valve 48 and the low pressure reservoir 3
9 and a check valve 41 are designed. Low pressure reservoir 39
When the valve is emptied, both the control valve 31 and the switching valve 46 are switched back to their basic valve positions. Both drive wheels 11, 12
During drive slip, both control valves 31, 32 are switched back and forth between the valve basic position and the valve intermediate position for the purpose of brake pressure adjustment, as described above.

When the brake pedal is operated, the charge valve 5
0 is switched, whereby the supply conduit 43 is disconnected from the brake circuit of the drive wheels 11,12. At the same time, the possible excitation of the switching valve 46 is interrupted, so that this switching valve returns to its basic valve position. Braking processes therefore always take priority over traction control.

The two-circuit brake device shown in the block circuit diagram of FIG. 2 corresponds to the two-circuit brake device described above in terms of function and configuration; however, the two-circuit brake device shown in FIG. It is configured to match the diagonally split brake circuit. In this case one drive wheel 11 in each case,
12 is arranged in each one of the two brake circuits. Generally, the drive wheels 11, 12 are the front wheels of a passenger car. If the two-circuit brake system shown in FIG. 2 corresponds to the two-circuit brake system described with reference to FIG. 1, identical components are provided with the same reference numerals. The difference is that the precharge pump 42 is in this case connected via two supply lines 43, 43' to one pump element 29 or 28 in each case. Each supply conduit 43, 43' has a check valve 48, 48'.
is located. The two low-pressure reservoirs 39, 38 are separated from the pump suction valve 36 of the corresponding pump element 29 or 28 via a check valve 41 or 41'. The valve unit 44 has two switching valves 46, 46', which are of the same type and are constructed as three-port, two-position solenoid valves with a spring return position. A first valve connection of the switching valves 46, 46' is connected to the inlet channel 26 or 25, respectively, and a second valve connection is connected to the respective one brake circuit outlet 17 or 16 of the master brake cylinder 15. The third valve connection is connected to the inlet of a pressure limiting valve 45, to which a check valve 49 is also connected in parallel.

The mode of action during traction control of such a two-circuit brake system with a diagonally split brake circuit is the same as that described above, but:
In this case, the control valves 31, 34 assigned to the outlet passages 21, 24 of the wheels 13, 14 that are not driven are switched to their intermediate positions, so that the wheel brake cylinders 10 of the wheels 13, 14 that are not driven are Cut off from brake pressure supply. Such control of the control valves 31, 34 is achieved by connecting the second valve connection of the control valves 31, 34 directly to the brake circuit outlet 17 of the master brake cylinder 15 or to the inlet passage 26, 25. 16, it can be avoided. If, for safety reasons, it is desired to disconnect the brake circuit from the pre-charging circuit during actuation of the brake pedal, the valve unit 44 must have two charging valves 50, 50' constructed in the same manner. First, in this case each charge valve is arranged in both supply conduits 43, 43'. The control inlets of the two charge valves 50, 50', which are also configured as hydraulically controlled two-port, two-position valves, are connected to the brake circuit outlet 17 or 16 of the master brake cylinder 15, respectively. The check valves 48, 48' connected to the supply lines 43, 43' are advantageously integrated into the charging valves 50, 50', as also described above. The provision of additional charging valves 50, 50' has the advantage that, in the event of a failure of check valves 48, 48', both brake circuits are not impaired during the braking process. If only the check valves 48, 48' are provided in the supply conduits 43, 43', brake fluid will flow out from the master brake cylinder 15 into the pre-charge circuit when this check valve fails, and this will cause This causes gradual instability of the pedal 19.

In the two-circuit brake system shown in FIGS. 1 and 2, the control valves 31, 32, 33, and 34 are connected to one inlet each, as in the embodiment shown in FIGS. 3 and 4, which will be described below. It can be configured as a combination of a valve and an outlet valve.

The structure of the two-circuit brake circuit device shown in the block circuit diagram in FIG. 3, which includes a front and rear split brake circuit, a skid control system, and a traction control system, is fully identical to the two-circuit brake device explained with reference to FIG. Because of the
has been added.

The control valves 131, 132, 133, 134 each consist in this case of a combination of an inlet valve 153 and an outlet valve 154. Inlet valve 153 and outlet valve 154
It is configured as a two-port, two-position solenoid valve with a spring return position. Each inlet valve 153 includes an outlet passage 121,
Check valves 155 with a shutoff direction oriented towards 122, 123, 124 are connected in parallel. In the basic position of the inlet valve 153, there is smooth flow from the inlet passages 125, 126 to the outlet passages 121, 122, 123, 124. The outlet valve 154 closes the outlet passages 121, 122, 1 in its working position caused by excitation.
23, 124 are connected to low pressure reservoirs 138, 139 or to the inlets of pump elements 128, 129 of return feed pump 127. If the inlet valve 153 and the outlet valve 154 are not energized, brake pressure can be built up in the corresponding wheel brake cylinder 110. When the inlet valve 153 is switched, the wheel brake cylinder 110 is shut off and the brake pressure in the wheel brake cylinder 110 is maintained. Additionally, when the outlet valve 154 is energized, the brake fluid is transferred from the wheel brake cylinder 110 to the corresponding low-pressure reservoir 13.
8 or 139, and the brake pressure in the wheel brake cylinder 110 is reduced again.

The auxiliary hydro unit 140 likewise consists of a front charge pump 142 and a valve unit 144. The front charge pump 142 is connected on the outlet side via a supply line 143 with a check valve 148 to a pump suction valve 136 of a pump element 129 assigned to the brake circuit of the drive wheels 111, 112;
In this case, the low pressure reservoir 139
It is also connected to the pump suction valve 136 via a check valve 141 which has a shutoff direction facing . On the other hand,
The front charge pump 142 is connected via a check valve 149 directly to an inlet channel 126, which inlet channel belongs to the brake circuit for the drive wheels 111, 112. The valve unit 144 has a connection valve 156 and a shutoff valve 157, each of which is designed as a two-port, two-position solenoid valve with a spring return position. The isolation valve 157 is connected to the connecting conduit 152 between the inlet channel 126 of the brake circuit for the drive wheels 111, 112 and the brake circuit outlet 117 of the master brake cylinder 115. During excitation, this shutoff valve 157
cuts off this connecting conduit. Check valve 1 with a flow direction parallel to the isolation valve 157 and towards the inlet passage 126
58 are connected. Connection valve 156 connects return flow conduit 15
9 and this return flow conduit connects to the low pressure reservoir 1
39 is connected to the brake fluid container 118. In this case, the connection of the return flow conduit 159 is arranged above the brake fluid reservoir 118 , whereas the connection of the precharge pump 142 is arranged below the brake fluid reservoir 118 . In its unenergized basic position, the connecting valve 156 blocks the return flow conduit 159 and, when energized, opens this return flow conduit. Furthermore, a pressure limiting valve 145 is arranged in the return flow conduit 159, which pressure limiting valve is arranged in the line section located between the inlet channel 126 and the connecting valve 156. Furthermore, the return flow conduit 15
9 is connected to a low pressure reservoir 139, and this low pressure reservoir 139 is connected to the pressure limiting valve 145 and the connecting valve 1.
56.

During ASR operation, the connection valve 156 and the cutoff valve 157 are switched, and the front charge pump 142 is connected. The front charge pump 142 transfers brake fluid from the brake fluid reservoir 118 to the check valve 149 at full delivery power.
and control valves 131, 132 directly to the wheel brake cylinders 110 of the drive wheels 111, 112. At the same time, brake fluid is supplied to the pump element 129 of the return feed pump 127, which pumps the brake fluid to the damping chamber 130 and the control valve 1.
31,132 and the drive wheel 111,1
12 wheel brake cylinders 110. Check valve 141 prevents front charge pump 142 from conveying brake fluid to low pressure reservoir 139 . The switched shutoff valve 157 prevents the brake fluid delivered by the pump element 129 from flowing out into the master brake cylinder 115 . Excess brake fluid is conveyed back to the brake fluid reservoir 118 via the pressure limiting valve 145 and the connection valve 156.

Full power performance of precharge pump 142 is only required at the beginning of ASR operation. In this case, if the drive wheels 111, 112 are slipping,
The wheel brake cylinder 110 of this drive wheel is directly and quickly filled to approximately 10 bar. For this purpose, the transport flow of the front charge pump 142 must be approximately 30 cm.
3/s. After the wheel brake cylinder 110 is first filled, the delivery flow of the front charge pump 142 is switched back, which means that the front charge pump 142
This is done by pulse control. The transport power of the front charge pump 142 is reduced, in this case only 5 cm3/s. This carrier flow is pump element 1
It is sufficient to supply 29. Pump element 129 then generates the required brake pressure, which is adjusted to the desired value by pressure regulation based on switching of inlet valve 153 and outlet valve 154. When both drive wheels 111, 112 slip, brake pressure is built up in both wheel brake cylinders 110. If only one drive wheel 111 or 112 is slipping, the non-slip drive wheel is cut off from the brake pressure supply by switching the inlet valve 153. For pressure reduction at the end of ASR operation,
Inlet valve 153 and outlet valve 15 of control valves 131, 132
4 can be switched. In this case, the brake fluid is supplied to the wheel brake cylinders 11 of the drive wheels 111, 112.
0 to the empty low pressure reservoir 139, whereby the brake pressure in the wheel brake cylinder 110 decreases very quickly. The low-pressure reservoir 139 is emptied via the switched connection valve 156 and the brake fluid flows directly into the brake fluid reservoir 118 . Low pressure reservoir 13
9 additionally connects the pump element 1 via a check valve 141.
29, this pump element is emptied by the damping chamber 130 and the pressure limiting valve 1 arranged in the return flow conduit 159.
45 and the connecting valve 156, the conveyed amount is returned to the brake fluid container 118 and conveyed. This allows the low-pressure reservoir 1 to be removed for possible subsequent ABS operation.
A full storage volume of 39 is once again provided.

In a variant of the two-circuit brake system, the low pressure reservoir 139 can be connected to the supply conduit 143. In this case, however, this low-pressure reservoir is connected to the line section between the check valve 148 and the pump intake valve 136 of the pump element 129. The check valve 141 becomes unnecessary. Low pressure reservoirs typically have a spring loaded reservoir piston. In order to ensure that the low pressure reservoir is not completely charged via the supply conduit 143 by the precharge pump 142 at the start of ASR control, a sensor is provided. This sensor detects the sliding distance of the reservoir piston of the low pressure reservoir or the reservoir pressure of the low pressure reservoir and sends a shutoff signal to the precharge pump 142 when a set value is exceeded. This ensures that the low pressure reservoir is only partially filled with brake pressure when the wheel brake cylinder 110 is first filled at the beginning of each ASR operation, and that when transitioning to ABS operation the low pressure reservoir is still filled with brake fluid during brake pressure reduction. It has a certain storage volume for accommodating.

The hydraulic two-circuit brake system having a skid control system and a traction control system shown in the block circuit diagram in FIG. 4 is constructed in the same manner as the two-circuit brake system shown in FIG. It differs in that it is suitable for diagonally split brake circuits. Identical components are therefore provided with the same reference numerals. The wheel brake cylinders 110 of drive wheels 111, 112 belonging to different brake circuits are connected to the outlet passages 123, 122, whereas the wheel brake cylinders 110 of the wheels 113, 114 that are not driven are connected to the outlet passages 121, 1.
24. Each pump element 128, 129 of the return feed pump 127 is connected to the supply conduit 1 on the inlet side.
43, 143' with the precharging circuit, said supply conduits are combined into a check valve 148.
is connected to the outlet of the precharge pump 142 via. Between each low-pressure reservoir 138, 139 and the inlet of the associated pump element 128, 129 there is a check valve 14 with a shutoff direction towards the low-pressure reservoir 138, 139.
1', 141 are arranged. Each pump element 1
28, 129 are connected to the brake fluid container 118 via return flow conduits 159', 159 on the outlet side. Each return flow conduit 159, 159' includes a pressure limiting valve 145, 14.
5' and the connecting valves 156, 156' of the valve unit 144 are arranged in the manner described in FIG. Furthermore, the valve unit 144 has a total of two shutoff valves 157, 157', each shutoff valve being connected to the master brake cylinder 115.
and the inlet passages 126, 125 of the four-pass hydro unit 120. Each shutoff valve 157
, 157', check valves 158, 158' are connected in parallel.

The mode of operation of the two-circuit brake system having a diagonally divided brake circuit is almost the same as that of the two-circuit brake system having a front and rear divided brake circuit shown in FIG. ,11
In order to prevent brake pressure from being supplied to the wheel brake cylinders 110 of wheels 110 during ASR operation, the inlet valves 1 of wheels 113 and 114 that are not driven during ASR operation are
53 must be shifted to its shut-off position during all ASR functions. The control valve 131 required for this purpose,
The control of the inlet valve 153 of 134 is such that both the inlet valves are connected to the inlet passages 126, 1 of the 4-passage hydro unit 120 on the inlet side.
25 and directly connected to the corresponding brake circuit outlet 117 or 116 of the master brake cylinder 115.

In the hydraulic two-circuit brake system having a front axle/rear axle split brake circuit shown in the block circuit diagram in FIG. 5, the constituent elements are the same as those of the two-circuit brake system shown in FIG. have the same sign, but are added by 200 to distinguish them. The four-channel hydro unit 220 has the same structure as shown in FIG. No, switching valve 2
Pump suction valve 2 of pump element 229 via 60
36. The switching valve 260 is configured as a 3/2-position solenoid valve with a spring return position, in which case its first valve connection is connected to the pump suction valve 236 and its second valve connection is connected to the pump suction valve 236. Low pressure reservoir 23
9 and whose third valve connection is connected to a supply conduit 243 leading to a precharge pump 242 . This supply conduit has a check valve 249. The pump delivery valve 237 is connected on its outlet side via an inlet channel 226 directly to the inlet of a pressure limiting valve 245, which is connected on its outlet side to the brake fluid reservoir 218. In this case, the outlet of the pressure limiting valve 1245 may be connected directly to the brake fluid container 118 or, as in this case, to the outlet of the check valve 249, in which case the Valve 249 and front charge pump 2
A further pressure limiting valve 247 is connected in parallel to the series connection with 42.

The valve unit 244 has a shut-off valve 261 which is configured as a two-port, two-position solenoid valve with a spring return position and which is connected to the drive wheel 211,
Brake circuit outlet 21 belonging to brake circuit 212
7 and the inlet passage 226 of the four-passage hydro unit 220 . Shutoff valve 261
In its basic position, it opens the connecting conduit 252 and in the switching position, which occurs during traction control, it closes off said connecting channel. In its deenergized basic position, the switching valve 260, which is also controlled during traction control, connects a first valve connection connected to the pump suction valve 236 with a second valve connection and thus connects the low-pressure reservoir 239. and the first
is connected in its switching position to the third valve connection and thus to the supply conduit 243.

In the ASR function, the switching valve 260 and the cutoff valve 261 are controlled to be switched to their switching positions. As a result, the brake circuit of the drive wheels 211, 212 is connected to the master brake cylinder 21 by the cutoff valve 261.
5 and connected to the precharge circuit by a switching valve 260. The started precharge pump 242 is connected to the wheel brake cylinders 210 of the drive wheels 211, 212 with drive slip through the pump suction valve 236 and the pump discharge valve 237 of the pump element 229.
Fill with brake fluid. A pressure profile of 10 bar in the wheel cylinder 210 is obtained in this case. The return feed pump 227 is connected to the pre-charge pump 2, since the starting of the pump element 229 is not necessary for this process, but is useful for obtaining the power of the filling process.
42. A general-purpose type control valve 231,
A slipped drive wheel 211,2 obtained by reciprocating switching of 232 between its basic position and an intermediate position.
Due to the pressure regulation in the twelve wheel brake cylinders 210, a brake pressure is built up such that the slipping drive wheels 211, 212 are braked. During all ASR operation, the low pressure reservoir 239 is isolated from the brake circuit by the switching valve 260 and is therefore not supplied with brake pressure. Thereby, upon transition to ABS operation, an empty low-pressure reservoir 239 is always provided, which allows a very quick transition from ASR function to ABS function. In the ABS function, extremely low wheel brake cylinder pressures are also obtained during pressure reduction.

Unlike the previously described two-circuit brake system, the pressure reduction at the end of ASR operation does not occur via the low-pressure reservoir 239, but directly via the control valves 231, 232 switched to their end positions. This is done in the charge circuit. In this case, the brake fluid returns to the brake fluid reservoir 218 via the controlled switching valve 260 and the pressure limiting valve 247. Additionally, a two-port two-position solenoid valve 262 can be connected which bridges the pressure control valve 247.

The two-circuit brake system shown in the block circuit diagram in FIG. 6 is almost identical to the two-circuit brake system shown in FIG. It has a split brake circuit. Since the drive wheels 211, 212 belong to different brake circuits, a switching valve 260, 260' is assigned to each brake circuit. This switching valve connects the pump suction valve 236 of the corresponding pump element 229 or 228 with the respective low-pressure reservoir 239 or 238 and, in its switching position, into an in each case a supply conduit 243 or 243'. Both supply conduits 24
3,243' are grouped together and guided together via a check valve 249 to the outlet of the precharge pump 242. Pump discharge valve 23 of both pump elements 228, 229
7 are connected via inlet passages 225, 226 to the outlet of check valve 249 via separate return flow conduits 259', 259, respectively. However, both return flow conduits 259, 259
' may be in direct communication with the brake fluid container 218. Each return flow conduit 259, 259' includes a pressure limiting valve 245,
245' is arranged. The valve unit 244 has two shutoff valves 261, 261', each shutoff valve being connected to the brake circuit outlet 217 of the master brake cylinder 215,
216 and the inlet passage 2 of the four-passage hydro unit 220
26, 225 in the connecting conduit 252 or 251.

The mode of operation of this two-circuit brake device is shown in FIG.
However, in this case, during ASR operation, the undriven wheel 213
, 214 are switched to their intermediate position, so that the wheel brake cylinder 210 of this undriven wheel 213, 214 is isolated from the brake pressure supply. Control valves 231, 23
If you want to avoid such switching of control valve 2,
31, 234 are separated from the inlet passages 226, 225,
Brake circuit outlet 21 of master brake cylinder 215
7,216.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a first embodiment of a two-circuit brake system according to the present invention, which includes front and rear divided brake circuits.

FIG. 2 is a block circuit diagram showing a first embodiment of a two-circuit brake system according to the present invention using a diagonally divided brake circuit.

FIG. 3 is a block circuit diagram showing a second embodiment of the two-circuit brake system according to the present invention, which includes front and rear divided brake circuits.

FIG. 4 is a block circuit diagram showing a second embodiment of the two-circuit brake system according to the present invention using a diagonally divided brake circuit.

FIG. 5 is a block circuit diagram showing a third embodiment of the two-circuit brake device according to the present invention, with front and rear divided brake circuits.

FIG. 6 is a block circuit diagram showing a third embodiment of the two-circuit brake device according to the present invention using a diagonally divided brake circuit.

[Explanation of symbols]

10 wheel brake cylinder, 11, 12 drive wheel, 13, 14 wheel, 15 master brake cylinder, 16, 17 brake circuit outlet, 18 brake fluid container, 19 brake pedal, 20 4-passage hydro unit,
21, 22, 23, 24 outlet passage, 25, 26
Inlet passage, 27 Return feed pump, 28
, 29 pump element, 30 damping chamber,
31, 32, 33, 34 control valve, 35 motor, 36 pump suction valve, 37 pump discharge valve, 38, 39 low pressure reservoir, 40
Auxiliary hydro unit, 41, 41' Check valve, 42 Front charge pump, 43, 43'
Supply conduit, 44 Valve unit, 45 Pressure limiting valve, 46, 46' switching valve, 47 Pressure limiting valve, 48, 48', 49 Check valve, 50
, 50′ charge valve, 110 wheel brake cylinder, 111, 112 drive wheel,
115 master brake cylinder, 117 brake circuit outlet, 118 brake fluid container, 12
1,122,123,124 Outlet passage, 125,1
26 inlet passage, 127 return feed pump, 128, 129 pump element, 130
Damping chamber, 131, 132, 133, 134 Control valve, 136 Pump suction valve, 138, 139
Low pressure reservoir, 140 auxiliary hydro unit,
141,141' check valve, 142 front charge pump, 143,143' supply conduit,
144 Valve unit, 145, 145' Pressure limiting valve, 148, 148' Check valve, 149
check valve, 152 connecting conduit, 153 inlet valve, 154 outlet valve, 155 check valve,
156,156' Connection valve, 157,157'
Shutoff valve, 158,158' Check valve, 159,1
59' Return flow conduit, 211, 212 Drive wheel, 213, 214 Wheel, 215
Master brake cylinder, 216, 217 Brake circuit outlet, 218 Brake fluid container, 2
20 4 passage hydro unit, 225,226
Inlet passage, 227 Return feed pump, 228
,229 pump element, 231,232,
233,234 control valve, 236 pump suction valve, 237 pump discharge valve, 238,239
Low pressure reservoir, 242 front charge pump,
243, 243' Supply conduit, 244 Valve unit, 245, 245' Pressure limiting valve, 247
pressure limiting valve, 249 check valve, 251,2
52 connection conduit, 259,259' return flow conduit,
260,260' switching valve, 261,261
´ Shutoff valve, 262 2 port 2 position solenoid valve

Claims (23)

[Claims] Claim 1: A hydraulic two-circuit brake system equipped with a skid control system and a traction control system for use in automobiles, comprising two separate brake circuits for controlling output of brake pressure by brake pedal operation. A master brake cylinder having an outlet, a brake fluid container connected to the master brake cylinder, and a four-passage hydro unit connected to both brake circuit outlets of the master brake cylinder are provided, the four-passage hydro unit being connected to both brake circuit outlets of the master brake cylinder. , four outlet passages divided into two brake circuits for connecting wheel brake cylinders of vehicle wheels;
An electromagnetic control valve is assigned to each outlet valve for controlling the output of brake pressure related to wheel slip to the wheel brake cylinder, and each is for returning and conveying brake fluid when the brake pressure in the wheel brake cylinder is reduced. two separate pump elements serving one brake circuit, each pump element being connectable on the inlet side via the control valve to the outlet channel belonging to one brake circuit; The four-channel hydro unit is connected to the brake circuit outlet of the master brake cylinder assigned to the same brake circuit on the outlet side, and the four-channel hydro unit is connected to each one brake cylinder for temporarily storing brake fluid when the brake pressure is reduced. It has two low-pressure reservoirs assigned to the circuit, each low-pressure reservoir being connected to the inlet of each said pump element, and an auxiliary hydro unit is provided for forming the brake supply pressure during traction control. , the auxiliary hydro unit has a front charge pump connected on the inlet side to the brake fluid reservoir, the front charge pump being connected to each drive wheel having at least one drive wheel during traction control via a non-return valve. The auxiliary hydro unit is adapted to supply brake fluid to a brake circuit, and furthermore the auxiliary hydro unit has a valve unit which, during traction control, is configured to provide a return valve assigned to the brake circuit with at least one drive wheel. In the type in which each pump element of the feed pump is separated from the master brake cylinder at the outlet side and connected to the brake fluid container via a pressure limiting valve, the front charge pump (42; 142; 242 )
is the drive wheel (11, 12; 111, 112; 21
1,212) wheel brake cylinder (10;11
0; 210) and has a sufficient conveying volume for rapid brake fluid filling to at least one drive wheel (1
1, 12; 111, 112; 211, 212) connected to a low pressure reservoir (38, 39;
138, 139; 238, 239) A hydraulic two-circuit brake device, characterized in that it is provided with means for at least partially blocking the filling of brake fluid into the brake fluid. 2. When the front charge pump (42; 142) performs traction control, the check valve (48;
A return feed pump (48, 48'; 148) assigned to each brake circuit with at least one drive wheel (11, 12; 111, 112)
27; 127) pump element (28; 28, 29
; 128, 129), and on the other hand via the second check valve (49; 149) the control valve (31, 32;
32, 33; 131, 132; 132, 133), and the control valve is connected to the drive wheel (11, 12; 1
11, 112) wheel brake cylinder (10; 1
10) for outlet passages (21, 22; 22, 23; 1
21. The two-circuit braking device according to claim 1, wherein the two-circuit braking device is assigned to a motor (21, 122; 122, 123). 3. The means for at least partially preventing the filling of brake fluid into the low-pressure reservoir comprises a sensor, the sensor detecting the sliding distance of a reservoir piston of the low-pressure reservoir; When the set value is exceeded, the front charge pump (
3. The two-circuit brake device according to claim 2, wherein the two-circuit brake device is adapted to cut off the circuit (142). 4. The means for preventing the filling of brake fluid into the low pressure reservoir is a check valve (41';41'; 141,
141'), and the check valve is connected to each low pressure reservoir (141').
38, 39; 138, 139) and the associated pump element (28, 29; 128, 129) with a shutoff direction towards said low-pressure reservoir (38, 39; 138, 139). 3. The two-circuit brake system according to claim 2, wherein the pump element and the low-pressure reservoir are assigned to a brake circuit having at least one drive wheel (11, 12; 111, 112). 5. During traction control, after the wheel brake cylinders (110) of the drive wheels (111, 112) are initially filled with brake fluid, the front charge pump (142) is controlled by pulse control of the front charge pump (142). 5. The two-circuit braking device according to claim 1, wherein the conveying output of 142) is reduced. 6. At least one drive wheel (11
, 12), each pump element (29; 28, 29) is connected on the inlet side to a supply conduit (4
3; 43, 43') through the front charge pump (42)
and each supply conduit (43; 43, 43')
A first check valve (48; 48, 48') is connected to the valve unit (44), and the valve unit (44) is connected to at least one switching valve (48, 48').
6; 46, 46'), and the switching valve (46; 46').
6,46') at least one drive wheel (11
, 12), each pump element (29, 28) assigned to a brake circuit having a master brake cylinder (
15) and is arranged in the connecting conduit (52, 51) between the switching valve (46; 46, 46') and
A first valve connection of the two valve connections is connected on the one hand with the outlet of the pump element (29; 29, 28) and on the other hand with the wheel brake cylinder (10) of the drive wheel (11, 12). Exit passage for (2
Control valves (31, 3) assigned to
2; 32, 33), and the second valve connection part is connected to the brake circuit outlet (
17, 16), the third valve connection is connected to the inlet of the pressure limiting valve (45), and the pressure limiting valve is connected to the brake fluid container (18) on the outlet side. ,
A first valve connection of the switching valve (46; 46, 46') is connected with a second valve connection in the valve basic position and with a third valve connection in the switching position produced during traction control. The switching valve is configured to be connected to the pressure limiting valve (45), and a second check valve (49) having a flow direction facing the switching valve (46; 46, 46') The two-circuit brake device according to claim 4 or 5, wherein the two-circuit brake device is connected in parallel to the two circuits. 7. The valve unit (44) has at least one charge valve (50; 50, 50'), which charge valve is connected to at least one drive wheel (11, 50') for the front charge pump (42). pump element (29; 29,
28), said supply conduit (43; 43, 43') being arranged in the supply conduit (43; 43, 43') of said supply conduit (43; 43, 43') in its switching position caused by brake pedal actuation.
7. The two-circuit brake device according to claim 6, wherein the two-circuit brake device is configured to cut off the brake circuit. 8. A check valve (48; 48, 48') provided in each supply conduit (43; 43, 43') is integrated into the charge valve (50; 50, 50'), The supply conduit (
8. The two-circuit braking device according to claim 7, wherein the two-circuit brake device is located at 43; 43, 43'). 9. The charge valve (50; 50, 50'
) is configured as a pressure-controlled 2-port 2-position valve with a spring return position, and the hydraulic control inlet of the 2-port 2-position valve is connected to the master brake cylinder (1
9. The two-circuit brake device according to claim 7 or 8, wherein the two-circuit brake device is connected to the brake circuit outlet (17; 17, 16) of 5). 10. The pressure limiting valve (45) is connected on the outlet side to the outlet of the front charge pump (42), and a brake fluid container (18) is connected to the front charge pump (42).
a second pressure limiting valve (
10. The two-circuit brake device according to claim 6, wherein the circuits 47) are connected in parallel. 11. The difference between the opening pressure of said second pressure limiting valve (47) and the pressure drop across said first check valve (48; 48', 48) ;38,3
9) response pressure and the low pressure reservoir (39; 38, 39)
and the pressure drop at the check valve (41; 41', 41) arranged between the pump element (29; 28, 29). (
47), the first check valve (49), the corresponding low pressure reservoir (39; 38, 39), and the low pressure reservoir (39);
9; 38, 39) and pump element (29; 28, 2
9) check valve (41; 41', 41) disposed between
The two-circuit brake device according to claim 10, wherein: [Claim 12] Each supply conduit (43; 43, 43')
has a diameter of about 6 to 8 mm.
The two-circuit brake device according to any one of the preceding items. 13. At least one drive wheel (1
Each pump element (12) of a return feed pump (127) assigned to a brake circuit with
9; 129, 128) is on the inlet side, and the first check valve (
supply conduit (143; 143, 143') with
) to the outlet of the front charge pump (142) and the outlet passage (121) for the wheel brake cylinder (110) of the drive wheels (111, 112).
, 122; 122, 123) assigned to each control valve (1
31, 132; 132, 133) is the control valve (131
, 132; 132, 133) through a second check valve (149) with a flow direction directed toward
42) and is connected to the outlet of the valve unit (144).
is at least one connection valve (156; 156, 156'
) and at least one isolation valve (157; 157,157
'), the shutoff valve (157; 157') being a return feed pump (
127) of each pump element (129; 129, 12
8) and the brake circuit outlet (117; 117, 116) of the master brake cylinder (115).
152; 152, 151) in such a way that the connection conduit (152; 152, 151) is interrupted in its switching position, which occurs during traction control, and at least one drive wheel (111, 112). ) of the return feed pump (127) assigned to the brake circuit with
129; 129, 128) is connected to the return flow conduit (15
9; 159, 159') through the brake fluid container (11
8) and each return flow conduit (159; 159
, 159') and the pressure limiting valve (145; 145, 145').
) is arranged, and the pressure limiting valve (145; 145,
A connecting valve (154; 159; 159, 159') between each return flow conduit (159;
6; 156, 156') is connected such that in its switching position, which occurs during traction control, the connecting valve opens the normally blocked return flow conduit (159; 159, 159'). The two-circuit brake device according to claim 4 or 5, wherein: Claim 14: Each shutoff valve (157; 157, 157
14. The two-circuit brake system according to claim 13, wherein a check valve (158; 158, 158') having a shutoff direction facing the master brake cylinder (115) is connected in parallel to '). 15. The connection valve (156; 156, 15
15. The two-circuit brake device according to claim 13, wherein the cut-off valve (157; 157, 157') is configured as a two-port, two-position solenoid valve with a spring return position. 16. The two-circuit brake system according to claim 13, wherein a further pressure limiting valve (147) is connected in parallel to the front charge pump (142). 17. The connection part of the front charge pump (142) is arranged at the lower part of the brake fluid container (118), and the connection part of the return flow conduit (159; 159, 159') is arranged in the lower part of the brake fluid container (118). 17. A two-circuit braking device according to any one of claims 13 to 16, wherein the two-circuit brake device is arranged on an upper part of the brake system. 18. At least one drive wheel (2
Each pump element (22) of a return feed pump (227) assigned to a brake circuit with
9; 229, 228) is the inlet side, and the first check valve (24
9) with the outlet of the precharge pump (242), and means for preventing the filling of brake fluid into the reservoir are connected to each supply conduit (243; 243, 243'). ; 243, 243') at least one switching valve (260; 260, 26
0'), and the switching valve has a pump element (2
29; 229, 228) is connected to the corresponding low-pressure reservoir (239; 239, 238) in its basic position and the front charge pump (242) in its switching position, which occurs during traction control.
The two-circuit brake device according to claim 1, wherein the two-circuit brake device is configured to be connected to. 19. At least one drive wheel (2
Each pump element (229; 229, 228) assigned to a brake circuit with a pump (11, 212) is connected on the outlet side via a return flow conduit (259; 259, 259') to a brake fluid reservoir (218). and a pressure limiting valve (245) in each return flow conduit (259; 259, 259').
;245,245') are arranged, and the valve unit (
244) at least one isolation valve (261; 261,
261'), and the shutoff valve (261; 261,
261') at least one drive wheel (211')
, 212) and the master brake cylinder (215).
19. Two-circuit brake system according to claim 18, characterized in that the connecting line (252; 252, 251) is arranged at a switch position (7, 216) and is adapted to interrupt the connecting line (252; 252, 251) in its switching position which occurs during traction control. Claim 20: Switching valve (260; 260, 260'
20. The two-circuit braking device according to claim 18, wherein said valve is configured as a three-port, two-position solenoid valve with a spring return position. Claim 21: Shutoff valve (261; 261, 261'
21. The two-circuit brake system as claimed in claim 18, wherein the valve is configured as an electromagnetic or hydraulic two-port two-position valve with a spring return position. Claim 22. Each return flow conduit (259; 259, 2
59') is connected to the outlet of the front charge pump (242) via the first check valve (249), and the check valve (249) and the front charge pump (242) are connected in series. parallel to the brake fluid container (218), another pressure limiting valve (245; 245, 245') with an opening direction directed towards the brake fluid container (218) and a significantly lower opening pressure than the pressure limiting valve (245; 245, 245').
24. The two-circuit braking device according to any one of claims 19 to 21, wherein: 247) is located. 23. The other pressure limiting valve (247) has two
23. A two-port solenoid valve (262) is connected in parallel, such that in its switching position it bridges the pressure-limiting valve (247). 2-circuit brake device.