Braking system having a 3 / 2-way valve for selectively connecting the brake master cylinder either to the travel simulator or to at least one brake circuit

Abstract

The invention relates to a hydraulic actuating system for a braking system, comprising the following: at least one brake circuit (BK) having at least one hydraulically actuated wheel brake (RZi); a brake master cylinder (SHZ, THZ) which can be actuated by means of an actuating device (1) and comprises at least one hydraulic working chamber (R1, R2); a hydraulically operating travel simulator (WS) for generating a reaction force in response to the actuating device (1); a controlled 3 / 2-way valve (MV, B-X2, A-X3, A üv-X3) by means of which a working chamber (R1, R2) of the brake master cylinder (SHZ, THZ) can be hydraulically connected either to a brake circuit (BK1) or to the travel simulator (WS); a pressure supply device (DV); and an open-loop and closed-loop control unit (ECU) for the open-loop and closed-loop control of the braking system, characterized in that a protective device is provided in addition to the 3 / 2-way valve (MV, B-X2, A-X3, Aüv-X3) or is integrated therein, which protective device ensures that, in the event of a malfunction, a hydraulic connection from the brake master cylinder (SHZ, THZ) to the brake circuit line (L4) is present or can be established.

Description

[0001] BRAKE SYSTEM WITH A 3 / 2-WAY VALVE FOR THE OPTIONAL CONNECTION OF THE MASTER BRAKE CYLINDER EITHER TO THE TRAVEL SIMULATOR OR TO AT LEAST ONE BRAKE CIRCUIT

[0002] The invention relates to a hydraulic actuation system for a braking system having the features of the preamble of claim 1 and a 3 / 2-way valve designed accordingly.

[0003] A possible previously known braking system is shown in Figure 1. The braking system has a master brake cylinder HZ, which is designed as a tandem master brake cylinder with two working chambers RI and R2, whereby the working chamber RI can be connected to the brake circuit BK2 via the hydraulic line L2 and the connecting valve V3. The working chamber R2 can be connected to the brake circuit BK1 via the hydraulic lines LI and L4 and the connecting valve VI. The hydraulic line LI is also connected to the hydraulic line L3, to which a travel simulator WS is connected, whereby the hydraulic line L3 can be shut off using the connecting valve V2. In addition, the braking system also has at least one pressure supply device DV, which is connected to the brake circuits BK1 and BK2 via hydraulic lines L5 and L6, whereby additional valves (not shown in Figure 1) are generally provided for shutting off the lines L5 and L6.If the braking system is operating without faults, which is referred to as normal operation, the two connecting valves VI and V3 are closed and the connecting valve V2 is open. If the brake pedal 1 is operated by the person driving the vehicle, the brake pressure in the brake circuits BK1 and BK2 is controlled or regulated by at least one pressure supply device DV depending on the brake pedal position, which is determined by means of the sensor 2. When the brake pedal 1 is adjusted, pressure is built up in the master brake cylinder via the tappet 3 and the piston in the master brake cylinder HZ in conjunction with the travel simulator WS, creating a reaction force that gives the person pedal feel. At least the connecting valve V2 is always designed as a 2 / 2-way valve.Should a fault occur in which pressure control in brake circuits BK1 and BK2 is no longer possible using at least one pressure supply device DV, the two connecting valves VI and V3 are opened and the connecting valve V2 is closed. In this state, also known as the fallback level, the master brake cylinder HZ acts as the pressure supply source for brake circuits BK1 and BK2, whereby in this state the pressure in the brake circuits can be built up using brake pedal 1. By closing the connecting valve V2, any influence on the brake pressure build-up by the travel simulator WS is avoided. Without closing the connecting valve V2, the volume of the travel simulator WS would act as a loss volume of the master brake cylinder, which would lead to an increase in the brake pedal travel and thus to lower brake pressure.Due to the lack of brake booster, very long pedal travel would be required if the connecting valve V2 remained open. Due to the lack of brake booster, the master brake cylinder (HZ) is often referred to as the auxiliary circuit.

[0004] A disadvantage of the prescribed braking system is that at least three connecting valves and thus a relatively large number of hydraulic lines are required to shut off the master brake cylinder HZ from the brake circuits BK1 and BK2 as well as the travel simulator WS, which is not only expensive to manufacture but also results in a relatively large construction volume of the hydraulic module in which the valves of the braking system are combined.

[0005] 3 / 2-way valves are widely used in hydraulic drives and especially in automotive braking systems. In braking systems, 2 / 2-way valves are usually used for pressure control and regulation. 3 / 2-way valves, on the other hand, are mostly used to connect and disconnect individual components of the braking system. For example, DE 10 2017 000 472 A1 discloses the use of 3 / 2-way valves to connect the brake circuits either to the motor-driven pressure supply device or to the master brake cylinder. However, the use of 3 / 2-way valves, as known from DE 10 2017 000 472 A1, leads to problems in the event of a failure or a leaky valve seat. For example, if the hydraulic connection from the master brake cylinder to the pressure supply device in the 3 / 2-way valve is defective, i.e.leaks, this leads to a strong pedal reaction, which inevitably leads to the pressure supply device being switched off, which simultaneously eliminates the braking force boost.

[0006] Figure 2 shows a generic braking system known from WO 2022 194 828, in which the connection between the master brake cylinder THZ, the travel simulator WS and one brake circuit BK1 is realized by means of a 3 / 2-way directional control valve MV. The tandem master brake cylinder THZ has a reservoir VB and two working chambers RI and R2. The piston separating the two working chambers RI and R2, which is adjustable via a bolt using pedal 1, is not shown. The first working chamber RI is connected by means of the hydraulic line L2 to the connecting valve V3, which optionally separates the hydraulic line L2 from the brake circuit line L8 of the second brake circuit BK2 or connects it to it. The second working chamber R2 of the tandem master brake cylinder THZ is connected to the 3 / 2-way directional control valve MV by means of the hydraulic line LI.Depending on the switching state of the 3 / 2-way valve MV, the hydraulic line LI is connected to the hydraulic line L3 to the travel simulator WS or to the hydraulic line L4 of the first brake circuit BK1. Figure 2 shows the 3 / 2-way valve MV in the de-energized state. The dashed rectangle shows the three valves PD, BP1, and BP2, which serve to connect the pressure supply device DV to the two brake circuits BK1 and BK2.

[0007] The 3 / 2-way valve MV known from WO 2022 194 828 can be disadvantageously torn open in the event of very rapid pressure reduction from the brake circuit via the 3 / 2-way valve in the direction of the master brake cylinder THZ.

[0008] The object of the present invention is to further develop the generic braking system in such a way that it is even safer, in particular in the event of failure of the power supply or the on-board power supply, the control and regulation unit ECU and / or the pressure supply.

[0009] This object is achieved according to the invention with a braking system having the features of claim 1. Further embodiments of the braking system according to the invention according to claim 1 result from the features of the subclaims. The tearing of the 3 / 2-way valve is advantageously achieved according to the invention in that a protective device is provided in addition to the 3 / 2-way valve or integrated into it, which ensures that in the event of a malfunction, which occurs in particular in the event of failure or partial failure of the pressure supply device, the control and regulating unit and / or the on-board electrical system, a hydraulic connection from the master brake cylinder to the brake circuit line is present or switchable.

[0010] According to the invention, the protective device can be formed either by providing additional valves, appropriate design of already existing valves and / or by appropriate diagnosis and, derived therefrom, appropriate control of the valves.

[0011] Thus, in a first embodiment, the protective device can be an additional valve through which hydraulic fluid can flow from the master brake cylinder line into the brake circuit line. The valve can be either a controlled switching valve, particularly in the form of a 2 / 2-way valve, or an overflow valve. The valve can also be advantageously integrated into the 3 / 2-way valve or connected in parallel to it, particularly to save space and / or costs.

[0012] In a further alternative or supplementary embodiment, the protective device can be formed in that the control and regulating unit controls or regulates the pressures in the brake system in such a way that the differential pressure dp applied to the 3 / 2-way valve does not exceed a limit value, so that the valve spring of the 3 / 2-way valve adjusts the valve in the event of a fault in such a way that hydraulic medium can flow from the master brake cylinder line into the brake circuit line.

[0013] Alternatively or additionally, the protective device can also be formed by the control and regulation unit controlling the volume flow during pressure reduction p ab or the pressure change rate in at least one wheel brake cylinder RZi is limited by controlling the 3 / 2-way valve, in particular in pulse width mode (PWM operation), in such a way that the respective switching valve via which the pressure reduction in the respective wheel brake cylinder RZi takes place, in particular straight, does not close. Alternatively or additionally, the protective device can also be formed in such a way that the valve cross-section of the 3 / 2-way valve is dimensioned in such a way that in the event of a fault and in the event of pressure reduction via the 3 / 2-way valve to the master brake cylinder, the volume flow is limited in such a way that the respective switching valve via which the pressure reduction in the respective wheel brake cylinder takes place, in particular straight, does not close.

[0014] Alternatively or additionally, the protective device can also be formed by providing an electrical energy storage device which, in the event of a failure of the power supply or the on-board network of the vehicle, supplies the control and regulation unit and at least some hydraulic valves, in particular the switching valves, at least for as long as, in particular for at least 20 ms up to a few seconds, until the valves, in particular the 3 / 2-way valve, are adjusted to the correct valve positions for the fault event.

[0015] The measures described above can of course be provided individually or in combination in the braking system according to the invention.

[0016] In the hydraulic actuation system for a brake system according to the invention, one working chamber of the master brake cylinder can be connected either to a brake circuit or to the travel simulator via the controlled 3 / 2-way valve. Furthermore, the brake system has at least one pressure supply device for pressure control or regulation, in particular for pressure buildup and / or pressure reduction, in the at least one brake circuit. Of course, it is also within the scope of the invention if the brake system additionally has at least one outlet valve for pressure reduction and / or an alternative control element, such as an electric motor-driven additional pressure supply device DV for pressure reduction.

[0017] In so-called "normal operation" of the braking system, the pressure is controlled or regulated in at least one brake circuit by means of the pressure supply device. In this operating state, the working chamber of the master brake cylinder is hydraulically connected only to the travel simulator via the 3 / 2-way valve. The hydraulic connection from the working chamber to the brake circuit is interrupted. For this purpose, the 3 / 2-way valve is energized, and the solenoid armature assumes a first position, which is subsequently also referred to as the second switching state of the 3 / 2-way valve, in which it presses a first valve closing body against the associated valve seat, thus closing a first hydraulic connection of the 3 / 2-way valve, which serves to connect the connections for the brake circuit and the master brake cylinder. The pressure prevailing in the brake circuit acts in a supporting manner to the magnetic force on the first valve closing body.To make this possible, the 3 / 2-way valve is arranged in the hydraulic connection between the pressure supply device and the master brake cylinder. The valve spring in the 3 / 2-way valve can thus be dimensioned with increased restoring force, so that the 3 / 2-way valve can still reliably switch from the first position of the solenoid armature to the second position of the solenoid armature, in the second switching state of the 3 / 2-way valve, even when the pressure in the brake circuit is greater than 150 bar, i.e., beyond the pressure during fading. This advantageously increases the reliability of the braking system.

[0018] A diagnosis to determine the failure of the valve spring can be advantageously carried out simply via the switching current of the solenoid valve.

[0019] If a leak occurs in the 3 / 2-way valve, the braking system can advantageously continue to operate with the pressure supply device for pressure control in the wheel brakes or brake circuits. By appropriately controlling the 3 / 2-way valve, a pedal characteristic that is still acceptable to the driver can be adjusted. For this purpose, the pressure in the working chamber of the master brake cylinder can advantageously be adjusted by switching the 3 / 2-way valve between its two switching states to achieve a specific pedal characteristic, using the pressure generated by the pressure supply device.Thus, even in the event of failure of the travel simulator and / or a leak in the 3 / 2-way valve, in particular the hydraulic connection between the connections for the travel simulator and the master brake cylinder, brake force amplification can advantageously still be maintained by means of the at least one pressure supply device.

[0020] Many components of conventional 2 / 2-way valves, such as those used for the anti-lock braking function (ABS), can advantageously be used for the 3 / 2-way valve according to the invention. In particular, the electromagnetic part of a conventional 2 / 2-way valve can be used for the 3 / 2-way valve according to the invention. The additionally required second valve seat with second valve closing body and valve spring can be combined in a separate structural unit. The first valve closing body is arranged in a first valve chamber and the second valve closing body in a second valve chamber. A third valve chamber is arranged between the two valve seats. The first valve chamber is connected via a channel to a first valve connection for the brake circuit, and the second valve chamber is connected via a channel to a second valve connection for the travel simulator.The third valve chamber is connected to the valve connection for the master brake cylinder via a channel. The first valve closing body is advantageously connected to the solenoid armature, with a tappet arranged on the first valve closing body that passes through both valve seats and is dimensioned in such a way that, in the first switching state of the solenoid valve, the second valve closing body is lifted from the second valve seat by the tappet against the valve spring force, thus opening the hydraulic connection between the second and third valve connections.In the second valve position, when the 3 / 2-way valve is de-energized, the second valve closing body is pressed sealingly against the second valve seat by the valve spring force and the first valve closing body is lifted from the first valve seat by the tappet, whereby the first hydraulic connection between the first and the third valve connection is opened and the second hydraulic connection between the third and the second valve connection is interrupted.

[0021] The connecting bolt connecting the solenoid armature to the first valve closing body can be made smaller in diameter than standard 2 / 2-way valves for ABS, advantageously achieving approximately 20% more magnetic force. To reduce the power loss of the 3 / 2-way valve for the high forces, the field winding of the 3 / 2-way valve can be cast into the solenoid housing and provided with a heat sink.

[0022] It is also possible to place a permanent magnet in the yoke to reduce power loss.

[0023] Both a single and a tandem master cylinder can be used as the master cylinder.

[0024] The use of a single master brake cylinder results in cost reduction and increased safety through smart redundancy.

[0025] Wheel brakes are connected to the above-described brake circuits in a known manner via additional valve circuits not further explained here. The brake system according to the invention and the 3 / 2-way valve required for it are explained in more detail below with reference to the figures.

[0026] They show:

[0027] Fig. 1 : conventional braking system with master cylinder, pedal, travel simulator and three 2 / 2-way valves;

[0028] Fig. 2: first possible embodiment of a hydraulic actuation system according to the invention for a brake system with a 3 / 2-way valve for selectively connecting the master brake cylinder designed as a tandem master brake cylinder to the travel simulator or the brake circuit;

[0029] Fig. 3: second possible embodiment of a hydraulic actuation system according to the invention for a brake system with a 3 / 2-way valve for selectively connecting the master brake cylinder designed as a single brake cylinder to the travel simulator or the brake circuit;

[0030] Fig. 3a schematic representation of a first possible embodiment of a 3 / 2-way valve according to the invention for the actuation system according to the invention in the non-energized position;

[0031] Fig. 3b schematic representation of a first possible embodiment of a 3 / 2-way valve according to the invention for the actuation system according to the invention in the energized position;

[0032] Fig. 3c: possible design of a first 3 / 2-way valve;

[0033] Fig. 4: third possible embodiment of a hydraulic actuation system according to the invention for a brake system with a 3 / 2-way valve for selectively connecting the master brake cylinder designed as a single brake cylinder to the travel simulator or the brake circuit;

[0034] Fig. 4a: schematic representation of a second possible embodiment of a 3 / 2-way valve according to the invention for the actuating system according to the invention in the non-energized position; Fig. 4b: schematic representation of a second possible embodiment of a 3 / 2-way valve according to the invention for the actuating system according to the invention in the energized position;

[0035] Fig. 4c: possible design of a second 3 / 2-way valve;

[0036] Fig. 4d pressure curves;

[0037] Fig. 5: first hardware measure to reduce the valve dimension of the

[0038] 3 / 2-way valve A-X3 in Fig. 4 for the situation “braking with high pedal force on a very slippery road surface and ECU failure”;

[0039] Fig. 6: fourth possible embodiment of a hydraulic actuation system according to the invention for a brake system with a 3 / 2-way valve for selectively connecting the master brake cylinder designed as a single brake cylinder to the travel simulator or the brake circuit;

[0040] Fig. 6a: schematic representation of a third possible embodiment of a 3 / 2-way valve according to the invention for the actuation system according to the invention in the non-energized position;

[0041] Fig. 6b: schematic representation of a third possible embodiment of a 3 / 2-way valve according to the invention for the actuation system according to the invention in the energized position;

[0042] Fig. 6c: possible design of a third 3 / 2-way valve;

[0043] Fig. 7: fifth possible embodiment of a hydraulic actuation system according to the invention for a brake system with a 3 / 2-way valve for selectively connecting the master brake cylinder designed as a single brake cylinder to the travel simulator or the brake circuit;

[0044] Fig. 7a: schematic representation of the first possible embodiment of a 3 / 2-way valve according to the invention for the actuation system according to the invention in the energized position;

[0045] Fig. 8: sixth possible embodiment of a hydraulic actuation system according to the invention for a brake system with a 3 / 2-way valve for selectively connecting the master brake cylinder designed as a single brake cylinder to the travel simulator or the brake circuit;

[0046] Fig. 8a: schematic representation of the second possible embodiment of a 3 / 2-way valve according to the invention for the actuation system according to the invention in the energized position;

[0047] Fig. 9: Time course of the brake pedal travel in the event of a fault to generate an acceptable pedal feel during braking with lower pressure in the master brake cylinder than in the brake circuit;

[0048] Fig. 9a: Time course of the brake pedal travel in the event of a fault to generate an acceptable pedal feel during braking with greater pressure in the master brake cylinder than in the brake circuit.

[0049] Figure 3 shows a further second possible embodiment of a hydraulic actuation system according to the invention for a braking system, wherein, in contrast to the braking system according to Figure 2, the master brake cylinder HZ is designed as a single master brake cylinder SHZ with only one working chamber RI. The working chamber RI of the single master brake cylinder SHZ is connected via the hydraulic line LI to the 3 / 2-way valve B-X2, which, analogous to the 3 / 2-way valve MV shown and described in Figure 2, connects the working chamber RI optionally to the travel simulator WS or the brake circuit BK1. In such a braking system, the pressure supply device DV can, for example, be connected to the brake circuit BK1 via a connecting valve PD with a hydraulic line L5.

[0050] Figure 3a shows a schematic representation of a possible embodiment of a 3 / 2-way valve B-X2 according to the invention for the braking system according to the invention. The 3 / 2-way valve B-X2 has an excitation winding 5 arranged around a magnetic yoke 6, in which the magnetic armature 4 is adjustable in the axial direction relative to the connecting pin 7, 7a. A stop element 4a is arranged at the left end of the magnetic armature 4, which abuts the inner wall of the magnetic yoke 6 in the non-energized switching state of the 3 / 2-way valve B-X2 shown in Figure 3a. The first valve closing body VSK1 is arranged at the right end of the connecting pin 7, 7a and is firmly connected to the connecting pin end 7a. The first valve closing body VSK1 interacts with the first valve seat VS1, which may be a component of the magnetic yoke 6.The magnetic yoke 6 forms a first valve chamber Kl in the area of ​​the connecting bolt section 7a, which is connected to the brake circuit BK1 via the first valve connection AN1 and the hydraulic line L4.

[0051] The 3 / 2-way valve B-X2 also has a second valve chamber K2, in which the valve spring VF and a second valve closing body VSK2 are arranged. The second valve chamber K2 is connected to the travel simulator WS via the second valve connection AN2 and the hydraulic line L3. The left side of the second valve chamber K2 forms the second valve seat VS2 of the 3 / 2-way valve B-X2, which interacts with the second valve closing body VSK2. A third valve chamber K3 is arranged between the two valve seats VS1 and VS2 and is connected to the master brake cylinder SHZ or THZ via the third valve connection AN3 and the hydraulic line LI.On the side of the first valve closing body VSK1 facing away from the connecting bolt 7, 7a, a tappet ST is formed or attached. Its length is dimensioned such that it extends through the first valve seat VS1 and the third valve chamber K3, and its free end can act on the second valve closing body VSK2 when the 3 / 2-way valve is energized. Figure 3a shows the "de-energized" state. In this state, the valve spring force, FVF, presses the second valve closing body VSK2 against the second valve seat VS2, with the travel simulator WS being decoupled from the third valve chamber K3. Furthermore, the magnet armature 4 is adjusted to the left, so that the first valve chamber K1 is connected to the third valve chamber K3 via the annular gap between the first valve closing body VSK1 and the first valve seat VS1, thus connecting the master brake cylinder SHZ or THZ to the first brake circuit BK1 via the hydraulic line L4.

[0052] The dimensioning of the valve spring VF determines the opening pressure, i.e., the pressure difference between the pressure in the master brake cylinder SHZ or THZ, PHZ, and the pressure in the travel simulator WS, Pws, at which the valve seat VS2 opens, in the fallback level, e.g., in the event of a failure of the pressure supply device DV. Here, the law requires that a vehicle deceleration of at least 0.24g can be generated with a foot force on the brake pedal 1 of 500N. By dimensioning the valve spring force, FVF, for example, at 75 bar opening pressure, almost three times the deceleration value can be achieved with a correspondingly higher pedal force.

[0053] Figure 3b shows the "energized" state. In this state, the magnetic force FM, which is created by the energization of the excitation coil 5, presses the magnet armature 4 to the right, and thus the valve spring VF together, the first valve closing body VSK1 against the valve seat VS1, the second valve closing body VSK2 away from the second valve seat VS2, so that the second valve chamber K2 is connected to the third valve chamber K3 via the annular gap between the second valve closing body VSK2 and the second valve seat VS2, whereby the master brake cylinder SHZ or THZ is connected to the travel simulator WS via the hydraulic line LI, via the valve chamber K3, via the valve chamber K2 and via the hydraulic line L3. Via the hydraulic line LI, the valve chamber K3, the valve chamber K2 and the hydraulic line L3 there is a pressure equalization between the pressure in the master brake cylinder SHZ or THZ and the pressure in the master brake cylinder SHZ.THZ, PHZ, and the pressure in the travel simulator WS, Pws, so that the pressures in the master brake cylinder SHZ or THZ, PHZ, and in the travel simulator, Pws, apart from dynamic influences, are the same. The connection between the valve chamber Kl and the valve chamber K3 is interrupted, so that a pressure difference between the pressure in the valve chamber Kl, PKI, and the pressure in the valve chamber K3, PK3, is maintained. For example, during automatic emergency braking (Automatic Emergency Brake, AEB), the pressure in the valve chamber Kl, PKI can certainly be the highest pressure that the pressure supply device DV can provide, e.g. PKi = 200 bar, whereby the pressure in the master brake cylinder SHZ or THZ, PHZ, and thus the pressure in the valve chamber K3, PK3 = 0 bar.If the pressure supply device DV fails in this condition, the valve spring VF must restore the connection between the valve chamber K1 and the valve chamber K3 so that the pressure in the brake circuit BK1, PBKI, corresponds to the pressure in the master brake cylinder SHZ or THZ, PHZ. This situation, with the highest pressure in the brake circuit BK1, in the example PBKi = PKi = 200 bar, and the lowest pressure in the master brake cylinder SHZ or THZ, in the example Pnz=PK3=0 bar, places the greatest demands on the force of the spring VF, FVF, and thus on the magnetic force, FM, and thus on the valve dimensioning.

[0054] The dimensioning of the valve spring force, FVF, determines the opening pressure, ie the pressure difference between the pressure in the valve chamber Kl, PKI, or in the brake circuit BK1, PBKI, (in the example PßKi = 200 bar) and pressure in the valve chamber K3, PK3, or in the master brake cylinder SHZ or THZ, PHZ, or in the travel simulator WS, Pws, (in the example Pnz = 0 bar) at which the valve seat VS1 opens.

[0055] In order to be able to quickly increase the pressure in the brake circuit BK1, PBKI, using foot force alone even in the mechanical fallback situation, e.g., in the event of an ECU failure, the seating area of ​​the valve seat VS1 is preferably selected to be large. Since the dimensioning of the valve spring force, FVF, increases proportionally with the seating area of ​​the valve seat VS1, the dimensioning of the valve spring force, FVF, is also large with a large seating area of ​​the valve seat VS1. As described above, when the valve is energized, the spring VF is compressed by the magnetic force, FM. With a large dimensioning of the valve spring force, FVF, the magnetic force, FM, and thus the entire valve dimensioning must be large, which increases the valve costs.

[0056] Figure 3c shows a possible design of the 3 / 2-way valve B-X2 according to the invention. The upper part, consisting of the magnet armature 4, excitation coil 5, and magnet yoke 6, corresponds to the design of a standard 2 / 2-way inlet valve for an anti-lock braking system (ABS). For this reason, a detailed description is omitted here. Only the lower part, which converts the 2 / 2-way valve into a 3 / 2-way valve, is described in detail, with reference to the functions described in Fig. 3a and Fig. 3b.

[0057] The valve is shown in its de-energized state. The magnetic yoke 6 serves to guide the connecting pin 7, 7a, which is connected to the first valve closing body VSK1. The connecting pin 7 can be made smaller in diameter than in the standard design of the 2 / 2-way inlet valve, which increases the effective pole area. The first valve closing body VSK1 works together with the first valve seat VS1 and is hemispherical in shape to achieve and ensure a reliable sealing effect. The first valve seat VS1 is arranged in the magnetic yoke 6. However, the first valve seat VS1 can also be integrated into the magnetic yoke 6 or implemented using a flanged plate. A tappet ST is formed on the first valve closing body VSK1 or connected to the connecting pin 7a.The tappet ST passes through the first valve seat VS1 and acts on the second valve closing body VSK2, which is partially spherical and interacts with the second valve seat VS2.

[0058] As shown, the second valve seat VS2 can be combined with the second valve closing body VSK2 and the valve spring VF in a separate housing as a subassembly. This offers advantages in pre-assembly and valve adjustment. For this purpose, the subassembly is pressed into the magnetic yoke 6. For a secure connection of the subassembly to the magnetic yoke 6, caulking is recommended. To protect against stray dirt particles in the valve seats VS1 and VS2, all ports AN1, AN2, and AN3 are protected with filters Fl, F2, and F3.

[0059] The valve adjustment is carried out in such a way that the tappet ST has a small distance to the ball VSK2.

[0060] To reduce coil heating, the excitation winding 5 can be cast with the magnet housing 9.

[0061] Figure 4 shows a further possible embodiment of a hydraulic actuation system according to the invention for a brake system as in Fig. 3, wherein the 3 / 2-way valve B-X2 is replaced by a 3 / 2-way valve A-X3.

[0062] Figure 4a shows a schematic representation of a possible embodiment of a 3 / 2-way valve A-X3 according to the invention for the braking system according to the invention. The 3 / 2-way valve A-X3 has an excitation winding 5 arranged around a magnetic yoke 6, in which the magnetic armature 4 is adjustable in the axial direction relative to the connecting pin 7, 7a. A stop element 4a is arranged at the left end of the magnetic yoke 4, which abuts the inner wall of the magnetic yoke 6 in the non-energized switching state of the 3 / 2-way valve A-X3 shown in Figure 4a. The valve closing body VSK is arranged at the right end of the connecting pin 7, 7a. The valve closing body VSK interacts with the first valve seat VS1, which can be a component of the magnetic yoke 6. The magnetic yoke 6 forms a first valve chamber Kl in the area of ​​the connecting bolt section 7a, which is connected to the travel simulator WS via the first valve connection AN1 and the hydraulic line L3.

[0063] The 3 / 2-way valve A-X3 also has a second valve chamber K2, in which the valve spring VF is located. The second valve chamber K2 is connected to the brake circuit BK1 via the second valve port AN2 and the hydraulic line L4. The left side of the second valve chamber K2 forms the second valve seat VS2 of the 3 / 2-way valve A-X3, which interacts with the valve closing body VSK. A third valve chamber K3 is arranged between the two valve seats VS1 and VS2, which is connected to the brake master cylinder SHZ or THZ via the third valve port AN3 and the hydraulic line LI.

[0064] Figure 4a shows the "non-energized" state. In this state, the valve spring force, FVF, presses the valve closing body VSK against the first valve seat VS1, whereby the travel simulator WS is decoupled from the third valve chamber K3, whereby the magnet armature 4 is also adjusted to the left, so that the second valve chamber K2 is connected to the third valve chamber K3 via the annular gap between the valve closing body VSK and the second valve seat VS2, whereby the master brake cylinder SHZ or THZ is connected to the first brake circuit BK1 via the hydraulic line LI, the valve connection AN3, the valve chamber K3, the valve chamber K2, the valve connection AN2 and the hydraulic line L4. The dimensioning of the valve spring force, FVF, can be selected to be small in this "non-energized" state of the excitation winding 5, because both when the pedal force is increased and when the pedal force is reduced, the pressure in the valve chamber K3, PK3, or in the master brake cylinder SHZ orTHZ, PHZ, the force of the spring, FVF, on the valve closing body VSK supports.

[0065] Figure 4b shows the "energized" state of the excitation winding 5. In this state, the magnetic force FM, which is created by the energization, presses the magnet armature 4 in the axial direction to the right, and thus, via the connecting bolt 7, 7a and the valve closing body VSK, the valve spring VF together, the valve closing body VSK against the second valve seat VS2, and away from the first valve seat VS1, so that the first valve chamber Kl is connected to the third valve chamber K3 via the annular gap between the valve closing body VSK and the first valve seat VS1, whereby the master brake cylinder SHZ or THZ is connected to the travel simulator WS via the hydraulic line LI, via the valve connection AN3 via the valve chamber K3, via the valve chamber Kl, via the valve connection AN1 and via the hydraulic line L3. Via this connection, there is pressure equalization between the master brake cylinder SHZ or THZ.THZ, PHZ, and the travel simulator WS, so that the pressures in the master brake cylinder SHZ or THZ, PHZ, and in the travel simulator, Pws, are the same, apart from dynamic influences. The connection between the valve chamber K2 and the valve chamber K3 is interrupted, so that a pressure difference between the valve chamber K2, PK2, and the valve chamber K3, PK3, is maintained. During normal braking, the pressure in the master brake cylinder SHZ or THZ, PHZ is significantly lower than the pressure in the brake circuit BK1, PBKI, so that, e.g. when the valve is switched off, the valve seat VS2 is opened by this pressure difference but also by the valve spring force, FVF. During regenerative braking, the pressure in the brake circuit BK1, PBKI, can be lower (e.g. PßKi=0 bar) than the pressure in the master brake cylinder SHZ or THZ, PHZ.During regenerative braking, the dimensioning of the 3-way valve A-X3 must be matched to the pressure difference between the pressure in the master brake cylinder SHZ or THZ, PHZ, and the pressure PBKI in the brake circuit BK1. During regenerative braking with, for example, brake circuit pressure PßKi=0 bar, the pressure in the master brake cylinder SHZ or THZ, PHZ is small, e.g., below 40 bar, so that the pressure difference remains below PHz-PßKi=40-0=40 bar, and the dimensioning of the valve spring force, FVF, e.g., when the valve is deactivated, is also small.

[0066] Braking with high pedal force on a road surface with good grip triggers ABS braking with pressure in brake circuit BK1, PBKI, of e.g. PßKi = 150 bar and high pressure in valve chamber K3, PK3, which can certainly reach a maximum of PK3 = PHz,max = 270 bar. If the valve is switched off in this state, the valve spring VF must restore the connection between valve chamber K2 and valve chamber K3 so that the pressure PBKI in brake circuit BK1 corresponds to the pressure PHZ in the master brake cylinder SHZ or THZ, PBKI = PHZ . To do this, the valve spring force, FVF, must open the valve seat VS2 against the pressure difference between valve chamber K3, PK3, and valve chamber K2, PKZ, (in the example PK3 - PKZ = PHZ, max - PBKI = 270 bar - 150 bar = 120 bar), the opening pressure. The dimensioning of the 3 / 2-way valve A-X3 must be selected to correspond to this pressure difference, in the example of 120 bar, larger than the pressure difference during recuperation of in the example PHz-PßKi=40 bar.

[0067] In order to be able to quickly increase the pressure in the brake circuit using foot force even in the mechanical fallback situation, e.g., in the event of an ECU failure, the seating area of ​​the valve seat VS2 is preferably selected to be large. Since the dimensioning of the valve spring force, FVF, increases proportionally with the seating area of ​​the seat VS2, the dimensioning of the valve spring force, FVF, is also large with a large seating area of ​​the valve seat VS2. As described above, when the valve is energized, the spring VF is compressed by the magnetic force, FM. With a large dimensioning of the valve spring force, FVF, the magnetic force, FM, and thus the entire valve dimensioning, must be large, which increases the valve costs.

[0068] To reduce the opening pressure PHZ-PBKI of the valve seat VS2 during braking with high pedal force on a grippy road surface, in the example Pnz.max-PßKi = 120 bar, there is a software measure with which the pressure in the brake circuit BK1, PBKI, with the effect of the pressure supply device DV, is kept just below the pressure in the valve chamber K3, PK3, i.e. just below the pressure in the master brake cylinder SHZ or THZ, PHZ. The guideline value of the pressure difference is achieved when, at the maximum value of the pressure in the master brake cylinder PHZ, max, the brake circuit pressure PBKI also reaches its maximum value PBKI, max, which can be supplied by the pressure supply device DV, e.g. PHz,max = 270 bar and PBKi,max = PDv,max = 200 bar. The pressure difference between the valve chamber K3, PK3, and the valve chamber K2, PK2, is then maximum APmax = PHz,max - PBKI,max = 270 - 200 = 70 bar. That isIn this example, the opening pressure of the valve seat VS2 is no longer PHZ-PBKI = 120 bar as in the example, but with the software measure is only a maximum of PHZ, max-PBKI, max = APmax = 70 bar. For this to happen, when the valve control is switched off, the valve spring force, FVF, only has to open the valve seat VS2 against the pressure difference APmax between the valve chamber K3, PK3, and the valve chamber K2, PK2, (in this example the reduced opening pressure APmax = 70 bar). By reducing the opening pressure of the valve seat VS2 from 120 bar to APmax = 70 bar, the dimensioning of the valve, i.e. the valve spring force, FVF, can be kept small. It makes sense to select the pressure difference APSW slightly larger than APmax for the dimensioning of the 3 / 2-way valve A-X3, ie for the dimensioning of the valve spring force FVF: APsW > APmax = PhZ,max - PDV,max , e.g. APsw = 90bar (see Fig.4d, where PBKI, max = PDv, max) to allow for a tolerance when setting the brake circuit pressure PBKI CLOSED. Since the force FVF of the valve spring VF is now designed for the value APsw, the pressure difference between the valve chamber K3, PK3, and the valve chamber K2, PK2, must be prevented from becoming greater than APsw, because otherwise the spring force FVF cannot switch the valve to its de-energized state. This means that the pressure PBKI in the brake circuit BK1 must not fall below the pressure PHZ-APSW. For this reason, the brake circuit pressure PBKI must be kept between PHZ-APSW (the minimum value) and Pnz-APmax (the maximum value) by software. With this software measure, with an intact brake system, the valve can be switched to its de-energized position at any time, despite the relatively low spring force FVF, which corresponds to the relatively small pressure difference from APsw, e.g. 90 bar.

[0069] If the master cylinder pressure PHZ is less than PHZ, max, then the pressure difference between the valve chamber K3, PK3, and the valve chamber K2, PK2, could be set even smaller than APmax to ensure even more reliable operation of the valve spring VF. However, this is not preferred, as it would mean that the brake circuit pressure PBKI would then be higher than necessary, placing more stress on the hydraulic components than necessary.

[0070] In the event of a fault, e.g. if the ECU fails, the software measure no longer works. The four closing valves SV1, ..., SV4 in the four hydraulic lines between brake circuit BK1 and the four wheel brake cylinders (not shown, SV1, ..., SV4 correspond to the standard 2 / 2-way inlet valve for an anti-lock braking system, ABS, but without a check valve) open when the ECU fails or are already open, causing the pressure in brake circuit BK1, PBKI, to collapse to the pressure level PRZ of the wheel brake cylinders, e.g. to PBKI = PZ = 120 bar. The valve spring VF must restore the connection between valve chamber K2 and valve chamber K3 so that the pressure in brake circuit BK1, PBKI, corresponds to the pressure in the master brake cylinder SHZ or THZ, PHZ. For this purpose, the valve spring force, FVF, must open the valve seat VS2 against the pressure difference between the valve chamber K3, PK3, and the valve chamber K2, PKZ, (in the example PK3 - PKZ = 270 bar - 120 bar = 150 bar), the opening pressure.The dimensioning of the 3 / 2-way valve A-X3 must be selected to correspond to this pressure difference, in the example of 150 bar, larger than with the reduced pressure difference of e.g. APsw = 90 bar.

[0071] An even greater demand on the spring force FVF is placed on the ECU failure during braking with high pedal force on a very slippery road surface, which triggers ABS braking, with high pressure in the master brake cylinder SHZ or THZ, PHZ, and in the valve chamber K3, PK3, which can certainly reach a maximum of e.g. PHZ, max = PK3 = 270 bar. In the event of an ECU failure, the software measure no longer works, the four closing valves SV1, ..., SV4 to the four wheel brake cylinders open or are already partially open and the pressure in the brake circuit BK1, PBKI, and thus the pressure in the valve chamber K2, PKZ, collapses to the level of the wheel brake cylinders, which during ABS braking on a very slippery road surface can be in the range of PBKI = PRZ = 10 bar, for example. After the ECU failure, the valve spring VF must restore the connection between the valve chamber K2 and the valve chamber K3 so that the pressure in the brake circuit BK1, PBKI, corresponds to the pressure in the master brake cylinder SHZ or THZ, PHZ.To do this, the valve spring force, FVF, must open the valve seat VS2 against the pressure difference between the valve chamber K3, PK3, and the valve chamber K2, PKZ, (in the example PK3 - PKZ = PHZ - PBKI = 270 bar - 10 bar = 260 bar), the opening pressure. In the event of a fault, the dimensioning of the valve spring VF, i.e. the valve spring force FVF, of the 3 / 2-way valve A-X3 must be much larger due to the very high pressure difference of 260 bar than for the reduced pressure difference in the intact braking system of APsw = 90 bar in the example. This situation, braking with high pedal force on a very slippery road surface and ECU failure, places the greatest demands on the valve spring force FVF and thus on the magnetic force FM. For this situation, two hardware measures are provided to reduce the valve dimensioning, the first hardware measure being shown in Fig. 5 and the second hardware measure being shown in Figures 6a to 6c.

[0072] Figure 4c shows a possible design of the 3 / 2-way valve A-X3 according to the invention. The upper part, consisting of the magnet armature 4, excitation coil 5, and magnet yoke 6, corresponds to the design of a standard 2 / 2-way inlet valve for an anti-lock braking system (ABS). For this reason, a detailed description is omitted here. Only the lower part, which converts the 2 / 2-way valve into a 3 / 2-way valve, is described in detail, with reference to the functions described for Fig. 4a and Fig. 4b.

[0073] The magnetic yoke 6 serves as a guide for the connecting pin 7, 7a, which interacts with the valve closing body VSK. The connecting pin 7 can be made smaller in diameter than in the standard design of the 2 / 2-way inlet valve, which increases the effective pole area. The valve closing body VSK interacts with the first valve seat VS1 and has a hemispherical shape to achieve and ensure a reliable sealing effect. The first valve seat VS1 is formed in the magnetic yoke 6 via a flanged cylinder. A tappet ST is connected to the connecting pin 7a. The tappet ST passes through the first valve seat VS1 and interacts with the valve closing body VSK, which is partially spherical and interacts with the second valve seat VS2.

[0074] As shown, the second valve seat VS2 can be combined with the valve closing body VSK and the valve spring VF in a separate housing as a subassembly. This offers advantages in pre-assembly and valve adjustment. For this purpose, the subassembly is pressed into the magnetic yoke 6. For a secure connection of the subassembly to the magnetic yoke, caulking is recommended. To protect against stray dirt particles in the valve seats VS1 and VS2, all ports AN1, AN2, and AN3 are protected with filters Fl, F2, and F3.

[0075] The valve adjustment is carried out in such a way that the tappet ST has a small distance to the valve closing body VSK.

[0076] To reduce coil heating, the excitation winding 5 can be cast with the magnet housing 9.

[0077] Figure 4d shows the pressure curves required for a 3 / 2-way valve, provided the required spring force of the valve spring is reduced so that the valve itself can be dimensioned smaller, since with reduced spring force the required magnetic drive force can also be reduced. On average, a person driving the vehicle can generate a maximum pressure Pnzmax in the master brake cylinder of, for example, 270 bar with their foot force. However, the pressure supply DV can usually only build up a maximum pressure PßKimax of approximately 200 bar. If the 3 / 2-way valve is to be switched off at time ti, the valve spring of the 3 / 2-way valve must be loaded against the pressure difference APmax of approximately 70 bar, with

[0078] APmax = PlHZ.max “ PßKl,max put the valve into the de-energized state.

[0079] With a safety margin, the valve spring force FVF is designed for APsw > APmax. This safety margin results in APsw = 90 bar, instead of 70 bar without the safety margin.

[0080] The brake circuit pressure PBKI should then be greater than or equal to PHZ - APsw: bar so that the valve spring can always counteract the pressure difference

[0081] AP = PHZ - PBKI can put the 3 / 2-way valve into the de-energized state.

[0082] Fig. 5 shows the first hardware measure for reducing the valve dimension of the 3 / 2-way valve A-X3 in Fig. 4 for the situation "braking with high pedal force on a very slippery road surface and ECU failure", e.g., due to voltage failure UB. For this purpose, the ECU is supplemented with a partial ECU, which allows current to be supplied to the four closing valves SV1, ..., SV4 to the four wheel brake cylinders (not shown) for a short time immediately after voltage failure UB. Fig. 5 shows the ECU, which is supplied with a voltage UB from the on-board electrical system. The output of the ECU includes, among other things, the control of the 3 / 2-way valve A-X3, the control of the four closing valves SV1, ..., SV4 to the four wheel brake cylinders, the control of n additional solenoid valves MVx, and the control of the motor of the pressure supply device DV. Furthermore, Fig. 5 shows a partial ECU, which is also supplied with a voltage UB from the vehicle electrical system.The output of the sub-ECU is the control of the four closing valves SV1, ..., SV4 to the four wheel brake cylinders, whereby the sub-ECU maintains the current supply to the four closing valves SV1, ..., SV4 for a short time, e.g., > 20 ms, after the voltage UB fails. This means that the four closing valves SV1, SV4 remain closed for a short time, e.g., 20 ms, after the ECU fails, so that the pressure in the brake circuit BK1, PBKI maintains the pressure level prior to the ECU failure for 20 ms, and the pressure difference between the master brake cylinder SHZ or THZ, PHZ, and the brake circuit BK1, PBKI is small; in the example, PHZ-PBKI< APSW = 90 bar. The shutdown of the 3 / 2-way valve A-X3, caused by the ECU failure, then opens the valve seat VS2 before the pressure PBKI in the brake circuit BK1 drops. The required electrical energy of the partial ECU is estimated to be E = UB xix At = 12 x 4 x 0.02 = 0.96 Ws, where i is the valve current. For this, for example,a capacitor capacity of C = ix At / UB = 4 x 0.02 / 12= 667pF is required.

[0083] The circuit diagrams are shown in the lower part of Fig. 5 for the situation in which, at time t=to of the voltage UB failure, all four closing valves SV1, ..., SV4 are not energized, i.e., open. If the voltage UB fails at time t=to, the four closing valves SV1, ..., SV4 are still energized, i.e., closed, by the sub-ECU for a period of, for example, at least Δt=20 ms. With a switch-off time of the magnetic force, FM, of the 3 / 2-way valve A-X3 of, for example, 5 ms, the valve spring force FVF of the 3 / 2-way valve A-X3 can open the valve seat VS2 if the valve is dimensioned for the pressure difference between the valve chamber K3, PK3, and the valve chamber K2, PKZ, of the 3 / 2-way valve A-X3. The pressure difference is limited to, for example, APsw = 90 bar by the software measure. The opening pressure of the 3 / 2-way valve A-X3 is therefore only 90 bar instead of 260 bar in the example, and the 3 / 2-way valve A-X3 can be dimensioned small.

[0084] Figure 6 shows the second possible embodiment of a hydraulic actuation system according to the invention for a brake system as in Fig. 4, wherein the 3 / 2-way valve A-X3 is replaced by a 3 / 2-way valve AÜV-X3. This 3 / 2-way valve AÜV-X3 contains an overflow valve ÜV as a second possible hardware measure for reducing valve dimensioning in the event of ECU failure, e.g., due to ECU hardware failure. For this purpose, a hydraulic line L9 is provided, which connects the hydraulic lines LI and L4. The overflow valve ÜV is provided in this hydraulic line L9, which is designed with the opening pressure PÜV for the pressure differential APsw that is set via the software measure, e.g., PÜV=APSW = 90 bar. Due to hydraulic pressure fluctuations that can occur in the brake system, the opening pressure of the overflow valve PÜV should be greater than the differential pressure APsw that is set via the software measure, e.g.,at APsw = 90 bar, in the range between PÜV = APsw + 10 bar = 100 bar and PÜV = APSW + 50 bar = 140 bar (see Fig. 4d). The overflow valve ÜV is connected to the master brake cylinder SHZ or THZ via the hydraulic lines L9 and LI and to the brake circuit BK1 via the hydraulic lines L9 and L4. In normal operation, in which the pressure difference between the master brake cylinder SHZ or THZ, PHZ, and the brake circuit BK1, PBKI, is limited by the software measure, in the example to APsw = 90 bar, the overflow valve ÜV, with e.g. Püv = 100 bar, remains closed. In this case, no volume flows through the hydraulic line L9 from the master brake cylinder SHZ or THZ into the brake circuit BK1. If the pressure in the master brake cylinder SHZ orTHZ, PHZ, but by more than the opening pressure PÜV of the overflow valve ÜV, in the example PÜV = 100 bar, greater than the pressure in the brake circuit BK1, PBKI, SO opens the overflow valve ÜV and thus creates a hydraulic connection between the master brake cylinder SHZ or THZ, via the hydraulic lines LI and L9, via the overflow valve ÜV and via the hydraulic lines L9 and L4, with the brake circuit BK1.

[0085] Figure 6a shows a schematic representation of a possible embodiment of a 3 / 2-way valve AÜV-X3 according to the invention for the braking system according to the invention. The 3 / 2-way valve AÜV-X3 is based on the 3 / 2-way valve A-X3, with the hydraulic line L9 and the overflow valve ÜV being integrated into the valve closing body VSK, as an alternative to the arrangement in Fig. 6.

[0086] Figure 6a shows the "non-energized" state. In this state, both ends of the hydraulic line L9 are connected to the valve chamber K3, so that there is no pressure difference across the overflow valve ÜV, and the overflow valve ÜV remains closed. The dimensioning of the valve spring force, FVF, can be selected small in this "non-energized" state of the excitation winding 5, as with the 3 / 2-way valve A-X3, because both when the pedal force is increased and when the pedal force is reduced, the pressure in the valve chamber K3, PK3, or in the master brake cylinder SHZ or THZ, PHZ, supports the force of the spring VF on the valve closing body VSK.

[0087] Figure 6b shows the "energized" state of the excitation winding 5 of the valve AÜV-X3. The function builds on the function of the 3 / 2-way valve A-X3, Fig. 4b, and supplements it with the overflow valve ÜV. In this, the magnetic force, FM, which is created by the current supply, presses the magnet armature 4 in the axial direction to the right, and thus via the connecting bolt 7, 7a and the valve closing body VSK the valve spring VF together, the valve closing body VSK against the second valve seat VS2, and away from the first valve seat VS1, so that via the annular gap between the valve closing body VSK and the first valve seat VS1 the first valve chamber Kl is connected to the third valve chamber K3, whereby the master brake cylinder SHZ or THZ is connected to the travel simulator WS via the hydraulic line LI, via the valve connection AN3 via the valve chamber K3, via the valve chamber Kl, via the valve connection AN1 and via the hydraulic line L3.This connection ensures pressure equalization between the master brake cylinder SHZ or THZ, PHZ, and the travel simulator WS, Pws, so that the pressures in the master brake cylinder SHZ or THZ, PHZ, and in the travel simulator, Pws, are the same, apart from dynamic influences, Pws = PHZ. The connection between the valve chamber K2 and the valve chamber K3 is interrupted, so that a pressure difference is maintained between the valve chamber K2, PKZ, and the valve chamber K3, PK3. During normal braking, the pressure in the master brake cylinder SHZ or THZ, PHZ is significantly lower than the pressure in the brake circuit BK1, PBKI, so that, e.g. in the event of an ECU failure, the valve seat VS2 is opened by this pressure difference but also by the valve spring force, FVF, and the overflow valve ÜV remains closed. During normal recuperative braking, the pressure in the brake circuit BK1, PBKI, may be lower (e.g. Obar) than the pressure in the master brake cylinder SHZ or THZ, PHZ.The dimensioning of the 3 / 2-way valve A-X3 must then be matched to the pressure difference between the pressure in the master brake cylinder SHZ or THZ, PHZ, and the pressure in the brake circuit BK1, PBKI. During normal regenerative braking, the pressure in the master brake cylinder SHZ or THZ, PHZ is low, e.g., below Pnz-PBKi=40 bar, so that the overflow valve ÜV does not open with an opening pressure of, e.g., Püv=100 bar, and the pressure difference remains below 40 bar, and the dimensioning of the valve spring force, FVF, is also low. It is therefore important that the opening pressure PÜV of the overflow valve ÜV is not less than the maximum pressure difference between the master brake cylinder SHZ or THZ, PHZ, and the brake circuit BK1, PBKI, at which recuperation is still taking place, so that during recuperation no brake fluid volume flows inadvertently from the master brake cylinder SHZ or THZ into the brake circuit BK1, and so that the brake pedal 1 does not move forward inadvertently.

[0088] The software measure ensures that in normal operation the pressure difference between the master brake cylinder SHZ or THZ, PHZ, and the brake circuit BK1, PBKI, PHZ-PBKI, remains less than or equal to APsw, so that in normal operation PÜV > APsw and the overflow valve remains closed (see Fig. 4d).

[0089] As already explained for the 3 / 2-way valve A-X3, the most critical case for dimensioning the valve is an ECU failure during braking with high pedal force on a very slippery road surface, during which ABS braking is triggered with high pressure in the master brake cylinder SHZ or THZ, PHZ, and in the valve chamber K3, PK3, which can certainly be a maximum of e.g. PK3 = PHZ, max = 270 bar. If the ECU fails, the software measure no longer works, the four closing valves of the four wheel brake cylinders SV1, ..., SV4 open or are already partially open and the pressure in the brake circuit BK1, PBKI, and thus the pressure in the valve chamber K2, PK2, collapses to the level of the wheel brake cylinders, PRZ, which during ABS braking on a very slippery road surface can be in the range of PZ = 10 bar, for example. However, due to the overflow valve ÜV, the valve dimensioning of the 3 / 2-way valve A-X3, ie the spring force FVF of the valve, does not have to be adjusted to this high differential pressure of e.g.PHZ - PBKI = 270-10 = 260 bar. At this high pressure difference of, for example, PHZ - PBKI = 260 bar, the overflow valve ÜV is opened with a small opening pressure of, for example, Püv = 100 bar. This creates the necessary connection in the event of an ECU failure between the master brake cylinder SHZ or THZ and the brake circuit BK1, via the hydraulic line LI, the connection AN3, the valve chamber K3, the hydraulic line L9, the overflow valve ÜV, the valve chamber K2, the connection AN2, and the line L4, when the valve seat VS2 is closed. This is the case when the brake circuit pressure PBKI is lower than the pressure PHZ - PÜV (see Fig. 4d). As a result, brake fluid volume flows from the master brake cylinder SHZ or THZ into the wheel brake cylinders and the pressure PRZ in the wheel brake cylinders increases and thus the pressure in the brake circuit BK1, PBKI, and the pressure difference between the pressure in the master brake cylinder SHZ or THZ, PHZ, and the pressure in the brake circuit BK1, PBKI, decreases.If this pressure difference falls below the opening pressure of the overflow valve PÜV, the overflow valve ÜV closes and the connection between the hydraulic lines LI and L4 via line L9 is interrupted. Now, the valve spring force, FVF, must open the connection between the hydraulic lines LI and L4 via the opening of the valve seat VS2, whereby the differential pressure across the valve seat VS2 APVF is selected to be slightly larger than the small opening pressure PÜV of the overflow valve, e.g.

[0090] APvF=Püv+5bar=100+5 = 105bar. The valve spring force, FVF, opens the valve seat VS2 when the brake circuit pressure PBKI is greater than the pressure PHZ-APVF (see Fig. 4d). In the transition range, when the pressure PBKI in brake circuit BK1 is greater than PHZ- APVF but less than PHZ- PÜV, both the open valve seat VS2 of the 3 / 2-way valve A-X3 and the open overflow valve ÜV connect the master brake cylinder SHZ or THZ with the brake circuit BK1 (see Fig. 4d). This means that the valve dimensioning can remain small even in this most critical case. This means that the valve dimensioning, i.e. the valve spring force FVF, does not have to be designed for the above-mentioned, very critical differential pressure of e.g. 260bar but only for the differential pressure of e.g. APvF=105bar.In summary, in case of ECU failure, if the pressure PBKI in the brake circuit BK1 is below PHZ-PÜV, then the overflow valve ÜV opens, if the pressure PBKI in the brake circuit BK1 is above PHZ-APVF, then the spring force FVF opens the valve seat VS2 of the 3 / 2-way valve A-X3, if the pressure PBKI in the brake circuit BK1 is both below PHZ-PÜV and above PHZ-APVF, then both the overflow valve ÜV and the valve seat VS2 of the 3 / 2-way valve A-X3 open. Despite this possible second hardware measure (ÜV), in an intact braking system, the software measure is intended to maintain the brake circuit pressure PBKI between the brake pressures Pnz-APmax and PHZ-APSW, i.e. PHZ-APSW < PBKI < Pnz-APmax, although the spring force FVF can still open the valve seat VS2 in the second hardware measure even with the larger pressure difference APVF > APsw. The reason is that if the pressure PBKI in the brake circuit BK1 is inadvertently too low, e.g.Due to tolerances in the control PBKI < PHZ-APÜV, the overflow valve ÜV could open unintentionally, and in the intact brake system, brake fluid volume could flow unintentionally from the master brake cylinder SHZ or THZ through the overflow valve ÜV into the brake circuit BK1 and the brake pedal could move forward unintentionally.

[0091] Figure 6c shows a possible design of the 3 / 2-way valve AÜV-X3 according to the invention. Here, only the differences to the 3 / 2-way valve A-X3 are described, which are limited to the valve closing body VSK. The valve closing body VSK consists of two parts, the valve closing body sealing head VSKD and the valve closing body seat sleeve VSKS. In the valve closing body VSK, an overflow valve chamber ÜVK for the overflow valve ÜV is provided, in which the closing body of the overflow valve ÜVS and the spring of the overflow valve ÜVF are housed. The valve closing body sealing head VSKD and the valve closing body seat sleeve VSKS have bores which represent the hydraulic line L9. On the side of the overflow valve chamber ÜVK, the valve closing body sealing head VSKD has a valve seat ÜVVS for the closing body ÜVS of the overflow valve ÜV.The valve seat ÜVVS works together with the closing body ÜVS to achieve and ensure the sealing effect of the overflow valve ÜV. The opening pressure PÜV of the overflow valve ÜV is adjusted during assembly of the valve closing body sealing head VSKD and the valve closing body seat sleeve VSKS by spring tensioning the spring ÜVF of the overflow valve ÜV. Thus, the opening pressure PÜV of the overflow valve ÜV can be determined via the spring characteristics. For a secure connection of the valve closing body sealing head VSKD and the valve closing body seat sleeve VSKS, caulking is recommended.

[0092] Figure 7 shows a further possible embodiment of a hydraulic actuation system according to the invention for a braking system as in Fig. 3, wherein, in addition to the braking system of Fig. 3, a hydraulic line LIO is provided which connects the hydraulic lines LI and L4. As a further addition, a 2 / 2-way valve, isolating valve TV, is provided in this hydraulic line LIO. With these additions, the dimensioning of the 3 / 2-way valve B-X2 can be kept small. In Fig. 3b, it was already established that the greatest requirement for the dimensioning of the 3 / 2-way valve B-X2 occurs in the ECU failure situation during automatic emergency braking (AEB) with the valve seat VS1 closed (Fig. 7a). The requirement for the force of the valve spring FVF to open the valve seat VS1 is the highest in this case. If the ECU fails, the control of the isolation valve TV also fails, so that the magnetic force, FM, of the isolation valve TV is lost.The only things that then act on the valve armature of the isolating valve TV are the force of the spring FVF of the isolating valve TV and the hydraulic force exerted by the pressure difference between the BKl pressure, PBKI, and the pressure in the master brake cylinder SHZ or THZ, PHZ, whereby in addition to the valve spring force FVF of the isolating valve TV, the hydraulic force also acts in the direction of "valve opening" and the isolating valve TV opens. It is important to ensure that the connections of the isolating valve TV are correctly connected to the hydraulic line LIO, as shown in Figure 7, so that the hydraulic force acts in the direction of "valve opening". In this situation, the required connection between the master brake cylinder SHZ and the THZ is created via the hydraulic line LIO and the isolating valve TV.THZ and the brake circuit BK1 without the valve seat VS1 of the 3 / 2-way valve B-X2 having to open, so that in this situation no high demands are placed on the dimensioning of the 3 / 2-way valve B-X2, and the dimensioning of the 3 / 2-way valve B-X2 can be kept small. Figure 8 shows a further possible embodiment of a hydraulic actuation system according to the invention for a brake system as in Fig. 4, wherein, in addition to the brake system of Fig. 4, a hydraulic line LIO is provided which connects the hydraulic lines LI and L4. As a further addition, a 2 / 2-way valve, isolating valve TV, is provided in this hydraulic line LIO. With these additions, the dimensioning of the 3 / 2-way valve A-X3 can be kept small.4b, it was already established that the greatest demands on the dimensioning of the 3 / 2-way valve A-X3 are placed in the ECU failure situation during ABS braking on a very slippery road surface with very high pedal force, e.g., PHZ = 270 bar, with the valve seat VS2 closed (Fig. 8a). The demand on the valve spring force, FVF, to open the valve seat VS2 of the 3 / 2-way valve A-X3 is highest in this case. If the ECU fails, the control of the isolation valve TV also fails, so that the magnetic force, FM, of the isolation valve TV is lost. Then, only the force of the valve spring of the isolating valve TV, FVF, and the hydraulic force exerted by the pressure difference between the pressure in the master brake cylinder SHZ or THZ, PHZ, and the BKl pressure, PBKI, act on the valve armature of the isolating valve TV, whereby in addition to the valve spring force FVF of the isolating valve TV, the hydraulic force also acts in the direction of "valve opening", and the isolating valve TV opens.It is important to ensure that the connections of the isolating valve TV, as shown in Figure 8, are correctly connected to the hydraulic line LIO so that the hydraulic force acts in the direction of "valve opening". In this situation, the required connection between the master brake cylinder SHZ or THZ and the brake circuit BK1 is established via the hydraulic line LIO and the isolating valve TV without the valve seat VS2 of the 3 / 2-way valve A-X3 having to open. This means that in this situation, no high demands need to be placed on the dimensioning of the 3 / 2-way valve A-X3, and the dimensioning of the 3 / 2-way valve A-X3 can be kept small.

[0093] Figure 9 and Figure 9a show a time course of the brake pedal travel PW in the event of a fault to generate an acceptable pedal feel.

[0094] A possible fault can be caused by a leak in the valve seat VS1 (in the 3 / 2-way valve B-X2, Fig. 3b) or VS2 (in the 3 / 2-way valve A-X3, Fig. 4b) of the 3 / 2-way valve. When the 3 / 2-way valve is activated, this valve seat can leak, for example, due to dirt particles penetrating it. In this case, the braking system according to the invention can create a fallback level in which the brake pedal characteristics or pedal feel are maintained by brake pedal travel blending with the pressure supply device DV. This is described below with reference to Figures 4 and 4b, with brake pedal travel blending with the pressure supply device DV taking place in a similar way for Figures 3, 6, 7, 8.

[0095] Normally, when the driver brakes, the pressure in the brake circuit BK1, PBKI is regulated by the pressure supply device DV to the target pressure of the wheel brake cylinder, which is derived, for example, from the brake pedal travel PW, which is measured with the brake pedal travel sensor PWS.

[0096] In a functioning braking system, each pressure in the master brake cylinder SHZ or THZ, PHZ corresponds to a defined brake pedal travel PW, which determines the pedal characteristic, which is stored in the electronic control unit (ECU). The pressure in the master brake cylinder SHZ or THZ, PHZ is measured, e.g., directly with a pressure sensor DGHZ (see Fig. 4) or indirectly with a force-displacement sensor 2 (see Fig. 1) that can measure the pedal force. Thus, for each brake pressure in the master brake cylinder SHZ or THZ, PHZ, a target brake pedal travel PWsoii can be determined using the pedal characteristic.

[0097] Fig. 9 qualitatively shows the result of brake pedal travel blending with the pressure supply device DV, whereby the pressure in the brake circuit BK1, PBKI, is greater than the pressure in the master brake cylinder SHZ or THZ, PHZ, which is generally the case during normal operation and without recuperation. Due to the error, brake fluid flows from the brake circuit BK1, via the hydraulic line L4, the leaking 3 / 2-way valve A-X3, and via the hydraulic line LI into the master brake cylinder SHZ or THZ, which, at constant pedal force, pushes the brake pedal back and reduces the brake pedal travel PW, or which, at constant brake pedal travel PW, increases the pressure in the master brake cylinder SHZ or THZ, PHZ, and in the travel simulator WS, Pws. In general, however, both the brake pedal travel PW will become shorter and the pressure in the master brake cylinder SHZ or THZ, PHZ, and thus also in the travel simulator WS, Pws, will increase, compared to braking with an intact brake system.

[0098] The following example explains how, by comparing the actual brake pedal travel PWactual, which is measured by a brake pedal travel sensor PWS, and the target brake pedal travel PWtarget, which is determined from the pressure in the master brake cylinder SHZ or THZ, PHZ, based on the brake pedal characteristics, the pressure supply device DV is used to generate an acceptable pedal feel by regulating the brake pedal travel PW in the event of a fault.

[0099] The error is detected by continuously comparing the actual brake pedal travel PWactual with the target brake pedal travel PWtarget. If the actual brake pedal travel PWactual falls below a selectable lower limit value below the target brake pedal travel PWtarget, in Fig. 9 at time 0.05 s, then too much brake fluid has flowed from the brake circuit BK1, through the hydraulic line L4, through the leaking 3 / 2-way directional valve A-X3, through the hydraulic line LI into the master brake cylinder SHZ or THZ, and into the travel simulator WS, and the brake pedal travel PW is too small. In this state, the pressure supply device DV is stopped, and the four closing valves SV1, ..., SV4 to the four wheel brake cylinders (not shown) are closed. The control of the 3 / 2-way valve A-X3 is switched off, whereby the pressure in the path simulator WS, Pws, no longer changes.Now, by controlling the pressure supply device DV, brake fluid volume is drawn from the master brake cylinder SHZ or THZ via the hydraulic line L4, the 3 / 2-way valve A-X3, and the hydraulic line LI. This reduces the pressure in the master brake cylinder SHZ or THZ, PHZ, advances the brake pedal, and increases the brake pedal travel PW. This adjusts the brake pedal travel PW to the pressure in the travel simulator, Pws. If the actual brake pedal travel PWactual exceeds a selectable upper limit value above the target brake pedal travel PWtarget, in Fig. 9 at time 0.1s, the 3 / 2-way valve A-X3 is activated again, so that a pressure equalization takes place between the pressure in the travel simulator, Pws, and the pressure in the master brake cylinder SHZ or THZ, PHZ, via the hydraulic line L3, the 3 / 2-way valve A-X3 and via the line LI, the four closing valves SV1, ..., SV4 to the four wheel brake cylinders are opened and the pressure in brake circuit BK1, PBKI, and in the four wheel brake cylinders, PRZ, is again adjusted using the pressure supply device DV according to the brake pedal travel PWactual. As already described, this will cause the brake pedal travel PWactual to increase too little compared to the target brake pedal travel PWsoll due to an error. If the actual brake pedal travel PWactual falls below the previously mentioned selectable lower limit value below the target brake pedal travel PWsoll, in Fig. 9 at time 0.2s, the pressure supply device DV is stopped again, the four closing valves SV1, ..., SV4 to the four wheel brake cylinders are closed, and the control of the 3 / 2-way valve A-X3 is switched off, repeating the process. The brake pedal feel therefore remains largely normal. However, slight vibrations of the brake pedal may occur.

[0100] Fig. 9a shows a qualitative result of brake pedal travel blending with the pressure supply device DV, whereby the pressure in brake circuit BK1, PBKI, is lower than the pressure in the master brake cylinder SHZ or THZ, PHZ, which is only the case with very high pedal forces and can be the case during recuperation. For the following description of brake pedal travel blending, braking with recuperation is assumed as an example, in which the pressure in brake circuit BK1 and in the four wheel brake cylinders PBKi = Pßz=Obar. The pressure in brake circuit BK1, PBKI, and in the four wheel brake cylinders, PRZ, is maintained at PßKi = P z=Obar in the example with the help of the pressure supply device DV. Due to a fault, brake fluid flows out of the master brake cylinder SHZ orTHZ and from the travel simulator WS, via the hydraulic line LI, the leaking 3 / 2-way valve A-X3, via the hydraulic line L4 into the brake circuit BK1, which, at constant pedal force, advances the brake pedal and increases the brake pedal travel PW, or, at constant brake pedal travel PW, decreases the pressure in the master brake cylinder SHZ or THZ, PHZ, and in the travel simulator WS, Pws. In general, however, both the brake pedal travel PW will increase and the pressure in the master brake cylinder SHZ or THZ, PHZ, and thus also in the travel simulator WS, Pws, will decrease, compared to braking with an intact brake system.

[0101] The following example explains how, by comparing the actual brake pedal travel PWactual, which is measured by a brake pedal travel sensor PWS, and the target brake pedal travel PWtarget, which is determined from the pressure in the master brake cylinder SHZ or THZ, PHZ, based on the brake pedal characteristics, the pressure supply device DV is used to generate an acceptable pedal feel by controlling the brake pedal travel PW in the event of a fault.

[0102] The error is detected by continuously comparing the actual brake pedal travel PWactual with the target brake pedal travel PWtarget. If the actual brake pedal travel PWactual exceeds a selectable upper limit above the target brake pedal travel PWtarget, in Fig. 9a at time 0.05 s, then too much brake fluid volume has flowed from the master brake cylinder SHZ or THZ and from the travel simulator WS, through the hydraulic lines LI and L3, through the leaking 3 / 2-way valve A-X3, through the hydraulic line L4 into the brake circuit BK1, and the brake pedal travel PW is too large. In this state, the pressure supply device DV is stopped, and the four closing valves SV1, ..., SV4 to the four wheel brake cylinders (not shown) are closed. The control of the 3 / 2-way valve A-X3 is switched off, whereby the pressure in the path simulator WS, Pws, no longer changes.Now, by controlling the pressure supply device DV, brake fluid is pumped into the master brake cylinder SHZ or THZ via the hydraulic line L4, the 3 / 2-way valve A-X3, and the hydraulic line LI. This increases the pressure in the master brake cylinder SHZ or THZ, PHZ, pushes the brake pedal back, and decreases the brake pedal travel PW. This adjusts the brake pedal travel PW to the pressure in the travel simulator WS, Pws. If the actual brake pedal travel PWact falls below a selectable lower limit value below the target brake pedal travel PWsoll, in Fig. 9a at time 0.1 s, the 3 / 2-way valve A-X3 is activated again, so that a pressure equalization takes place between the pressure in the travel simulator, Pws, and the pressure in the master brake cylinder SHZ or THZ, PHZ, via the hydraulic line L3, the 3 / 2-way valve A-X3 and via the hydraulic line LI, the four closing valves SV1, ..., SV4 to the four wheel brake cylinders are opened and the pressure in the four wheel brake cylinders, PRZ, and in the brake circuit BK1, PBKI, is again adjusted to the target pressure (in the example PBKI = PZ = 0 bar) using the pressure supply device DV. As already described, this will cause the brake pedal travel PWactual to increase too much compared to the target brake pedal travel PWsoll due to an error. If the actual brake pedal travel PWactual exceeds the previously mentioned selectable upper limit above the target brake pedal travel PWsoll, in Fig. 9a at time 0.2s, the pressure supply device DV is stopped again, the four closing valves SV1, ..., SV4 to the four wheel brake cylinders are closed, the control of the 3 / 2-way valve A-X3 is switched off, and the process is repeated. The brake pedal feel therefore remains largely normal. However, slight vibrations of the brake pedal may occur.

[0103] List of reference symbols:

[0104] 1 brake pedal

[0105] 2 sensors

[0106] 3 piston tappets

[0107] Magnet armature

[0108] 4a Stop element of the magnet armature 4

[0109] 5 Excitation winding

[0110] 6 Magnetic yoke

[0111] 7, 7a connecting bolt

[0112] 9 Magnet housing

[0113] AN1, AN2, AN3 valve connections

[0114] A-X3 3 / 2-way valve

[0115] AÜV-X3 3 / 2-way valve with overflow valve ÜV

[0116] BE unit

[0117] BK1, BK2 Brake circuit 1, Brake circuit 2

[0118] BP1, BP2 connecting valves

[0119] B-X2 3 / 2-way valve

[0120] DGHZ pressure sensor for measuring the master brake cylinder pressure PHZ

[0121] DGBKI pressure sensor for measuring the brake circuit pressure PBKI

[0122] DV pressure supply device

[0123] ECU electronic control unit, Electronic Control Unit

[0124] Fl, F2, F3 valve filters

[0125] FM magnetic force of the valve

[0126] FP force through hydraulic pressure

[0127] FVF spring force of the valve spring VF

[0128] H stroke of the magnet armature

[0129] HV1 first hydraulic connection

[0130] HV2 second hydraulic connection

[0131] HZ master brake cylinder

[0132] Kl, K2, K3 valve chamber

[0133] LI, ..., LIO Hydraulic lines

[0134] MV 3 / 2-way valve

[0135] PBKI pressure in brake circuit BK1

[0136] PBKI,max maximum achievable pressure in brake circuit BK1

[0137] PD connecting valve

[0138] PDV,max maximum achievable pressure of the pressure supply device

[0139] PHZ pressure in the master brake cylinder SHZ / THZ

[0140] PHZ, max specified maximum pressure in the master brake cylinder SHZ / THZ

[0141] PKI, PK2, PK3 Pressure in valve chambers Kl, K2, K3

[0142] PRZ pressure in the wheel brake cylinder

[0143] APsw pressure difference for dimensioning the valve spring force

[0144] FVF

[0145] Püv Opening pressure of the overflow valve ÜV

[0146] Pws pressure in the path simulator WS

[0147] APVF pressure difference in case of failure for the dimensioning of the

[0148] Valve spring force FVF PW Brake pedal travel PWactual measured brake pedal travel PWS Brake pedal travel sensor PWdesired Brake pedal travel according to pedal characteristics RI, R2 Working chambers of the master brake cylinder SHZ / THZ Single or tandem master brake cylinder ST Tappet

[0149] SV1, SV4 2 / 2-way valves, closing valves TV Isolating valve t Time to Time of voltage drop UB UB Electrical voltage from the vehicle electrical system ÜV Overflow valve ÜVF Spring of the overflow valve ÜV ÜVK Chamber of the overflow valve ÜV ÜVS Closing body of the overflow valve ÜV ÜVVS Valve seat of the overflow valve ÜV VI, V2, V3 2 / 2-way valves, connecting valves VB Reservoir VF Valve spring VS1 First valve seat VS2 Second valve seat VSK Valve closing body VSK1 First valve closing body VSK2 Second valve closing body VSKD Sealing head of the valve closing body VSK VSKS Seat sleeve of the valve closing body VSK WS Travel simulator

Claims

Patent claims 1. A braking system or hydraulic actuation system for a braking system, comprising: - at least one brake circuit (BK) with at least one hydraulically operated wheel brake (RZi), - a master brake cylinder (SHZ, THZ) which can be actuated by means of an actuating device (1), in particular in the form of a brake pedal, and which has at least one hydraulic working chamber (RI, R2), - a hydraulically acting travel simulator (WS) for generating a reaction force on the actuating device (1), - a controlled 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) with which a working chamber (RI, R2) of the master brake cylinder (SHZ, THZ) can be hydraulically connected either to a brake circuit (BK1) or to the travel simulator (WS), whereby the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) has three hydraulic connections (AN1, AN2, AN3) for connection to the brake circuit line (L4), the travel simulator line (L3) and the master brake cylinder line (LI), - a pressure supply device (DV), - a control and regulating unit (ECU) for controlling and regulating the braking system, characterized in that in addition to the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) or integrated into it, a protective device is provided which ensures that in the event of a fault, which occurs in particular in the event of failure or partial failure of the pressure supply device (DV), the control and regulating unit (ECU) and / or the on-board network, a hydraulic connection from the master brake cylinder (SHZ, THZ) to the brake circuit line (L4) is present or switchable.

2. Brake system or hydraulic actuation system for a brake system according to claim 1, characterized in that the protective device is a valve (ÜV, TV) through which hydraulic medium can pass from the master brake cylinder line (LI) into the brake circuit line (L4), wherein the valve (ÜV, TV) is either a controlled switching valve (TV), in particular in the form of a 2 / 2-way valve, or an overflow valve (ÜV). 230044WO - Registration text / GE / 30.04.2024 3. Brake system or hydraulic actuation system for a brake system according to claim 2, characterized in that the valve (ÜV, TV) is integrated into the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) or connected in parallel thereto.

4. Brake system or hydraulic actuation system for a brake system according to one of claims 1 to 3, characterized in that a valve return spring (VF) of the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) in the de-energized state applies force to and adjusts the at least one valve actuator (VSK, VSK1, VSK2) of the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) in such a way that the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) connects the master brake cylinder line (LI) to the brake circuit line (L4).

5. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that the 3 / 2-way valve (MV, A-X3, AÜV-X3) has a valve actuator (VSK), in particular in the form of a ball or a cylinder-like part with rounded or conical end faces, which is arranged between two valve seats (VS1, VS2) so as to be adjustable back and forth in a third valve chamber (K3), which in turn is arranged between a first and a second valve chamber (K1, K2).

6. Brake system or hydraulic actuation system for a brake system according to one of claims 1 to 4, characterized in that the 3 / 2-way valve (MV, B-X2) has two valve actuators (VSK1, VSK2), in particular each in the form of a ball or partial ball, which each interact with a valve seat (VS1, VS2) and are arranged in the valve chamber (Kl, K2), wherein in particular between the valve chambers (Kl, K2) a third valve chamber (K3) is arranged.

7. Brake system or hydraulic actuation system for a brake system according to claim 5 or 6, characterized in that the third valve chamber (K3) is connected to the valve connection (AN3) and thus to the master brake cylinder line (LI), and that in the case of the 3 / 2-way valve (MV, B-X2) the valve chambers (Kl, K2) are connected to the brake circuit line (L4) or to the travel simulator line (L3) and in the case of the 3 / 2-way valve (A-X3, B-B2) the valve chambers (Kl, K2) are connected to the travel simulator line (L3) or brake circuit line (L4). 230044WO - Registration text / GE / 30.04.2024 8. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) has an electromagnetic drive (4, 5) which acts on the at least one valve actuator (VSK, VSK1, VSK2) via at least one force transmission means, in particular in the form of a connecting bolt (7, 7a), and the first and third valve chambers (K1, K3) and the valve seats (VS1, VS2) are arranged between the second valve chamber (K2) and the drive (4, 5), the valve return spring (VF) being arranged in the second valve chamber (K2).

9. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that the brake circuit line (L4) is connected to the second valve connection (AN2) of the 3 / 2-way valve (MV, A-X3) in such a way that a pressure in the brake circuit line (L4) supports the valve return spring (VF) when adjusting the valve actuator (VSK) to the de-energized position, and that the valve (TV) is connected to the master brake cylinder line (LI) and the brake circuit line (L4) in such a way that a pressure in the master brake cylinder (SHZ, THZ) acts in a supporting manner to the force of the valve spring of the valve (TV) in order to open the hydraulic connection between the master brake cylinder line (LI) and the brake circuit line (L4) interrupted by the valve (TV).

10. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that the brake circuit line (L4) is connected to the second valve connection (AN2) of the 3 / 2-way valve (MV, AÜV-X3) in such a way that a pressure in the brake circuit line (L4) supports the valve return spring (VF) when adjusting the valve actuator (VSK) to the de-energized position, and that the valve (ÜV) is connected to the master brake cylinder line (LI) and the brake circuit line (L4) in such a way that a pressure in the master brake cylinder (SHZ, THZ) opens the hydraulic connection between the master brake cylinder line (LI) and the brake circuit line (L4) interrupted by the 3 / 2-way valve (MV, AÜV-X3).

11. Brake system or hydraulic actuation system for a brake system according to one of claims 1 to 10, characterized in that the brake circuit line (L4) is connected to the first valve connection (AN1) of the 3 / 2- 230044WO - Registration text / GE / 30.04.2024 Directional control valve (MV, B-X2,) is connected in such a way that a pressure in the master brake cylinder (SHZ, THZ) supports the valve return spring (VF) when adjusting the valve actuator (VSK1, VSK2) into the de-energized position, and that the valve (TV) is connected to the master brake cylinder line (LI) and the brake circuit line (L4) in such a way that a pressure in the brake circuit line (L4) acts in a supporting manner to the force of the valve spring of the valve (TV) in order to open the hydraulic connection between the master brake cylinder line (LI) and the brake circuit line (L4) interrupted by the valve (TV).

12. Brake system or hydraulic actuation system for a brake system according to one of claims 1 to 11, characterized in that the control and regulating unit (ECU) controls or regulates the pressures in the brake system in such a way that the differential pressure (dp) applied to the 3 / 2-way valve (MV, A-X3, AÜV-X3) does not exceed a limit value, so that the valve spring of the 3 / 2-way valve (MV, A-X3, AÜV-X3) adjusts the valve when the valve is switched off in such a way that hydraulic medium can pass from the master brake cylinder line (LI) into the brake circuit line (L4).

13. Brake system or hydraulic actuation system for a brake system according to claim 11, characterized in that the control and regulating unit (ECU) controls the brake system in such a way that the pressure (PBKI) in the brake circuit (BK1) falls below the pressure (PTHZ, PSHZ) in the master brake cylinder (SHZ, THZ) by less than a limit value APSW, which is at least the difference (AP-max) between the maximum pressure (Pnzmax) of the master brake cylinder (SHZ, THZ) and the maximum pressure of the pressure supply device (DV).

14. Brake system or hydraulic actuation system for a brake system according to claim 12, characterized in that the limit value of the software measure at which the set pressure difference (APSW) is equal to the difference (APSW = PHZmax - PDVmax) between the specified maximum pressure (Phz,max) in the master brake cylinder (SHZ, THZ) and the maximum achievable pressure (PDVmax) of the pressure supply device (DV).

15. Brake system or hydraulic actuation system for a brake system according to claim 1, characterized in that the control and regulating unit (ECU) controls the volume flow during pressure reduction (p a b) or the pressure change rate in at least one wheel brake cylinder (RZi) by 230044WO - Registration text / GE / 30.04.2024 Control of the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3), in particular in pulse width mode (PWM operation), is limited in such a way that the respective switching valve (SVi) via which the pressure reduction in the respective wheel brake cylinder (RZi) takes place, in particular just, does not close.

16. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that the valve cross section of the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) is dimensioned such that in the event of a fault and when the pressure is reduced via the 3 / 2-way valve (MV, B-X2, A-X3, AÜV-X3) to the master brake cylinder (SHZ, THZ), the volume flow is limited so that the respective switching valve (SVi) via which the pressure is reduced in the respective wheel brake cylinder (RZi) does not close, in particular just close.

17. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that an electrical energy store (C) is provided which, in the event of a failure of the voltage supply or the on-board network of the vehicle, supplies the control and regulating unit (ECU, partial ECU) and at least some hydraulic valves, in particular the switching valves (SVi), in particular for at least 20 ms up to a few seconds, until the valves, in particular the 3 / 2-way valve (MV, B-X2, A-X3), are adjusted to the correct valve positions for the fault situation.

18. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that by means of the control and regulating unit (ECU) the switching functions of the valves during a braking operation and / or when the vehicle is stationary and / or when the vehicle is moving slowly, (V F vehicle g< 30 km / h), in particular by comparing the switching signals with the determined pressure change in the master brake cylinder (HZ, DGHZ) and / or the determined pressure change in the brake circuit (BK, DGBKI) and / or by means of a volume measurement (see Fig. 3).

19. Brake system or hydraulic actuation system for a brake system according to one of the preceding claims, characterized in that in the case of a leaky 3 / 2-way valve, in particular due to a leaky 230044WO - Registration text / GE / 30.04.2024 Valve seat, the control of the pedal characteristics is carried out by means of the pressure supply (DV).

20. Brake system or hydraulic actuation system for a brake system according to claim 18, characterized in that for adjusting a pedal travel of the brake pedal (1), the pressure in the working chamber of the master brake cylinder (HZ) is regulated by appropriately switching the 3 / 2-way valve (MV, B-X2, A-X3) between its two switching states in order to regulate a specific pedal characteristic, the pressure generated by means of the pressure supply device (DV) being used for this purpose.

21. Brake system or hydraulic actuation system for a brake system according to claim 18 or 19, characterized in that in the event of failure of the travel simulator (WS) and / or a leak in the 3 / 2-way valve (MV, B-X2, A-X3), in particular the hydraulic connection between the connections for the travel simulator (WS) and the master brake cylinder (HZ), a brake force boost can still be maintained by means of the at least one pressure supply device (DV). 230044WO - Registration text / GE / 30.04.2024

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