Hydraulic assembly for a vehicle braking system

Abstract

Hydraulic assembly for a vehicle braking system (100) with at least two brake circuits (102, 104) and wheel brakes (106, 108, 110, 112) assigned to the brake circuits (102, 104), wherein the hydraulic assembly comprises the following: a pressure generator (116) for the driver-independent generation of a central hydraulic pressure for the brake circuits (102, 104) at least during a service braking initiated by a driver; and at least one pressure adjustment device (134) for brake circuit-specific adjustment of the central hydraulic pressure generated by the pressure generator (116) independently of the driver, characterized in that the components included by the hydraulic assembly are assembled to form the hydraulic assembly and the hydraulic assembly as a whole can be mounted in the vehicle.

Description

Technical field

[0001] The present disclosure relates to a hydraulic assembly for a multi-circuit vehicle braking system. The hydraulic assembly comprises a pressure generator for generating hydraulic pressure in the brake circuits independently of the driver. background

[0002] Conventional vehicle braking systems can be operated either by a driver or independently of the driver. A braking process initiated by the driver is also referred to as service braking. During service braking initiated by the driver, or independently of it, a vehicle safety system can initiate braking independently of the driver. In this case, it is called system braking, which can occur either superimposed on or separately from service braking. Well-known vehicle safety systems include, for example, an anti-lock braking system (ABS), electronic stability control (ESC or ESP), and similar systems.

[0003] In conventional vehicle braking systems, the hydraulic pressure in the brake circuits is generated by the driver during service braking. For this purpose, the brake circuits are hydraulically coupled to a master cylinder, which is actuated by the driver in the usual way using a brake pedal.

[0004] In modern vehicle braking systems, hydraulic pressure generation during service braking can also be achieved using a pressure generator that can be operated independently of the driver. Such a pressure generator is typically a hydraulic pump, which is, for example, part of an electro-hydraulic vehicle braking system or a regenerative vehicle braking system ("hybrid braking system").

[0005] In an electro-hydraulic braking system, according to the "brake-by-wire" principle, the master cylinder is fluidically decoupled from the brake circuits during service braking. Hydraulic pressure is generated by a hydraulic pump, which is controlled depending on the brake pedal's position. In a regenerative braking system, the master cylinder is also hydraulically decoupled from the brake circuits during service braking. In this case, the vehicle is decelerated by a generator that charges a vehicle battery. If the driver requests greater deceleration than the generator can provide, the hydraulic pump generates supplemental hydraulic pressure in the brake circuits. This process is also known as "blending."

[0006] A dual-circuit electro-hydraulic brake system is known from DE 10 2007 047 208 A1. The brake system comprises two electrically driven pressure generators, which are implemented as a dual-circuit fluid supply pump. An individual hydraulic pressure can be generated in each of the two brake circuits by means of the dual-circuit fluid supply pump. demolition

[0007] A vehicle braking system is desired that efficiently generates hydraulic pressure in the brake circuits independently of the driver during service braking initiated by the driver. A hydraulic assembly for such a vehicle braking system should also be specified.

[0008] Within the scope of the present disclosure, a hydraulic assembly for a vehicle braking system with at least two brake circuits and wheel brakes assigned to the brake circuits is provided. The vehicle braking system includes a pressure generator for generating a central hydraulic pressure for the brake circuits independently of the driver, at least during service braking. Furthermore, the hydraulic assembly includes at least one pressure adjustment device for adjusting the central hydraulic pressure generated by the pressure generator independently of the driver for each brake circuit.

[0009] The pressure generator can be configured to provide central hydraulic pressure even during system braking. System braking can occur simultaneously with service braking or separately. Here, system braking generally refers to a driver-independent braking intervention by a vehicle safety system. This automatic braking intervention can, for example, lead to a build-up of hydraulic pressure or an increase, decrease, or maintenance of a prevailing hydraulic pressure.

[0010] The pressure generator centrally produces a common hydraulic pressure for all brake circuits, which can then be individually adjusted for each brake circuit as needed using the pressure adjustment device. In this way, a pressure differential can be set between the brake circuits despite the central hydraulic pressure generation. According to one variant, the hydraulic pressure adjustment is made over a continuous pressure range. According to an alternative variant, the adjustment relates to a discrete or even binary ("on / off") hydraulic pressure supply to an individual brake circuit.

[0011] The pressure regulating device can comprise one or more valve assemblies. Each valve assembly can, in turn, have one or more valve groups, and each valve group can contain one or more valves. For example, it would be conceivable that each valve assembly of the pressure regulating device for each brake circuit comprises a valve group with at least one valve.

[0012] Alternatively or in addition to at least one valve assembly, the pressure control device can also include control electronics, such as a control unit for the pressure generator. Each valve assembly can also be assigned its own control electronics for actuating the valve assembly. In one implementation of this concept, the pressure control device comprises a first valve assembly that is electrically actuated to set (e.g., regulate) a hydraulic pressure corresponding to the actuation state. The first valve assembly can be electrically actuated by means of pulse width modulation. In this case, the actuation state of the first valve assembly is adjustable via the pulse width.

[0013] One implementation of the hydraulic assembly provides that the first valve assembly includes at least one adjusting valve that is adjustable (at least) between an open and a closed valve position. Such an adjusting valve can be digitally, discretely, or continuously adjustable and can be provided for each brake circuit.

[0014] The first valve assembly can further comprise a first check valve connected in parallel to each adjusting valve. In an exemplary implementation, the first check valve is connected in parallel to the adjusting valve in such a way that, when the adjusting valve is closed, flow is allowed to bypass the adjusting valve and flow towards the wheel brakes. In this exemplary implementation, the check valve therefore allows further hydraulic pressure build-up in at least one of the brake circuits by means of the pressure generator, even when the adjusting valve is closed.

[0015] The pressure generator can include a suction port for hydraulic fluid and a discharge port for hydraulic fluid. These ports can be provided separately. Alternatively, the ports can be implemented via a single common port through which both suction and discharge of the hydraulic fluid occur. In the latter case, the ports are fluidically coupled to each other via this common port. In the former case, the fluidic coupling of the two ports can occur within the pressure generator. Alternatively or additionally, the suction port and the discharge port can also be fluidically coupled to each other outside the pressure generator.

[0016] A second valve assembly can be provided in a suction line that leads into the suction port. This second valve assembly can, for example, include a second check valve that opens when the printing element is drawn in (e.g., during a suction stroke) and closes when the printing element is expelled (e.g., during an ejection stroke).

[0017] The pressure generator can include a hydraulic chamber for holding hydraulic fluid, allowing the brake circuits to be supplied with hydraulic fluid from this chamber. Both the intake and exhaust ports (or a corresponding combined port) can lead into the hydraulic chamber.

[0018] The pressure generator can be a conventional multi-piston pump that generates the desired hydraulic pressure by means of a multiple piston strokes. According to an alternative embodiment, the pressure generator includes a plunger piston movable within the hydraulic chamber. Advantageously, a single hydraulic chamber with a single plunger piston is provided for all brake circuits. With the pressure generator equipped with a plunger piston, the desired hydraulic pressure can be built up by means of a single ejection stroke, provided the hydraulic chamber is sufficiently large.

[0019] The pressure generator can include an electric motor to actuate the piston pump or plunger piston. A gearbox (typically a reduction gearbox) can be provided between the electric motor and the pressure generator if necessary. The gearbox can be a belt drive, a gear drive, or a combination of both.

[0020] The electric motor can be arranged coaxially or axially offset from the plunger piston. In one implementation, the electric motor is arranged axially offset but parallel to the plunger piston.

[0021] The pressure control device may also include a first control unit for the electric motor. This first control unit may be configured to supply the electric motor with control signals depending on the hydraulic pressure to be generated. For controlled control of the electric motor, a pressure sensor may also be provided (e.g., in the hydraulic chamber or in the brake circuits), the output signal of which is evaluated by the first control unit for the purpose of comparing the actual value with the setpoint.

[0022] The hydraulic assembly may include a switching device. This switching device is designed to supply the wheel brakes either with hydraulic pressure generated independently of the driver or with hydraulic pressure generated by the driver. The switching device may be electrically actuated, in which case, in the unactuated state, it connects the wheel brakes to a driver-operated master cylinder, and in the actuated state, it connects the wheel brakes to the pressure generator. The switching device can therefore be configured according to the "push-through" principle to ensure, for example, that driver-induced hydraulic pressure generation is always possible even if the pressure generator fails.

[0023] Several implementations are possible regarding the switching device. For example, the switching device could comprise a 3 / 2-way valve or two 2 / 2-way valves. Of course, other valve configurations would also be conceivable.

[0024] The hydraulic assembly can have a modular design consisting of two or more independently manageable sub-assemblies. Several technically different versions of individual sub-assemblies can exist. In this way, the hydraulic assembly can be configured differently for different vehicle types according to a modular principle.

[0025] For example, the switching device, the pressure setting device, and the pressure generator can form a first, independently manageable subassembly (although the switching device does not necessarily have to be part of the first subassembly). Several different types of this first subassembly can exist, differing, for example, in the hydraulic fluid delivery capacity of the respective pressure generator and / or in the configuration of the pressure setting device. The main cylinder can also be part of the first subassembly or a further subassembly.

[0026] A third valve assembly can be provided between the pressure adjustment device and the wheel brakes to allow for brake interventions at the wheel brakes independent of the driver. This third valve assembly can, for example, be part of a vehicle safety system (e.g., an ABS and / or ESC system).

[0027] According to one variant, the third valve assembly is part of the first subassembly. According to another variant, the third valve assembly is part of a separately operable second subassembly. The second subassembly can also exist in various types, differing, for example, in their respective valve configurations. Thus, according to one configuration, the third valve assembly may consist exclusively of non-adjustable shut-off valves that can only be switched in a binary ("on / off") manner. According to an alternative configuration, the third valve assembly may include adjustable valves (in addition to or as an alternative to non-adjustable shut-off valves).

[0028] A second control unit can be provided to enable driver-independent braking interventions at the wheel brakes. This second control unit can be part of the vehicle safety system and designed to control the pressure generator to build up hydraulic pressure independently of the driver in a safety-critical situation. Furthermore, the second control unit can be designed to influence the prevailing hydraulic pressure in a safety-critical situation by appropriately controlling the third valve assembly.

[0029] According to one implementation, the first control unit is part of the first subassembly, while the second control unit is part of the second subassembly. However, it would also be conceivable to implement the functionalities of the first and second control units in a single, shared control unit. This shared control unit could then (like the third valve assembly) be part of the first subassembly.

[0030] For a regenerative braking system, a third control unit can also be provided for regenerative braking operation. This third control unit is designed to activate the pressure generator during regenerative braking in order to build up hydraulic brake pressure independently of the driver. The hydraulic brake pressure at the wheel brakes can be built up during generator operation ("blending").

[0031] In a regenerative braking system, the hydraulic assembly can further include a pedal feedback simulation unit, which can be actuated during regenerative braking by hydraulic pressure generated by the driver (for example, in the master cylinder). The pedal feedback simulation unit can be part of the first sub-assembly. Alternatively, the pedal feedback simulation unit, possibly together with the master cylinder, can form a self-contained third sub-assembly. Again, various types of the third sub-assembly can be provided, differing, for example, in the volumetric design of the master cylinder and / or the pedal feedback simulation unit.

[0032] The hydraulic assembly described here can be part of an electro-hydraulic or regenerative vehicle braking system. The corresponding braking system can also include suitable devices for brake-by-wire operation. Such devices can include a brake pedal with an associated pedal sensor, as well as control electronics that actuate the pressure generator based on an output signal from the pedal sensor. The respective braking system can also include the brake circuits with associated brake lines and wheel brakes.

[0033] In the case of a regenerative braking system, a generator can also be provided in addition to the pedal feedback simulation unit. The generator serves to charge a vehicle battery during generator operation during service braking. Brief description of the drawings

[0034] Further details, features, and advantages of the hydraulic assemblies and vehicle braking systems described here will become apparent from the following descriptions of exemplary embodiments, which are explained with reference to the drawings. The drawings show: Fig. 1 a first embodiment of a vehicle braking system; Fig. 2A-2C further examples of a vehicle braking system; Fig. 3 a first embodiment of a modular design of the vehicle braking system according to Fig. 1; Fig. 4 a second embodiment of a modular design of the vehicle braking system according to Fig. 1; Fig. 5 a third embodiment of a modular design of the vehicle braking system according to Fig. 1; Fig. 6 a fourth embodiment of a modular design of the vehicle braking system according to Fig. 1; Fig. 7 an embodiment of a subassembly in an exploded view; Fig. 8 a perspective view of the subassembly according to Fig. 7; Fig. 9 a sectional view of the subassembly according to the Fig. 7 and Fig. 8; and Fig. 10 a perspective view of a subassembly supplemented by a main cylinder and a pedal feedback simulation unit according to the Fig. 7 and Fig. 8. Detailed description

[0035] The following section explains various embodiments of a vehicle braking system and a corresponding hydraulic assembly with reference to the drawings. In the drawings, identical elements are identified by the same reference numerals.

[0036] Although the exemplary embodiments are explained in connection with an exemplary motor vehicle braking system and an exemplary pressure generator, it should be noted that the invention is not limited to the implementations described here. The pressure generator can operate not only according to the plunger principle presented here, but can also be designed as a cyclically operating multi-piston pump, to which a pressure accumulator can optionally be assigned. Furthermore, the concept described here can also be implemented in braking systems with more than two brake circuits, with a different brake circuit distribution (e.g., diagonal distribution), etc.

[0037] Fig. Figure 1 shows a first embodiment of a vehicle braking system 100. The vehicle braking system 100 is an electro-hydraulic vehicle braking system or a regenerative vehicle braking system (or a combination thereof).

[0038] The vehicle braking system 100 according to Fig. 1 comprises a variety of components that can be configured as one or more independently manageable hydraulic assemblies, depending on requirements. Different hydraulic assemblies can be installed in spaced-apart areas of a motor vehicle.

[0039] The following section will first explain the individual hydraulic components and their functions in more detail. Following this, possible configurations of the hydraulic components in conjunction with independently manageable subassemblies will be presented.

[0040] As in Fig. As shown in Figure 1, the vehicle braking system 100 is a dual-circuit braking system. A first brake circuit 102 is designed to supply two rear wheel brakes 106, 108 with hydraulic fluid. A second brake circuit 104 performs the same function with regard to two front wheel brakes 110, 112.

[0041] Hydraulic fluid can be supplied to the two brake circuits 102 and 104 either by a driver-operated master cylinder 114 or by an electrically operated pressure generator 116. The pressure generator 116 thus allows hydraulic pressure to be generated in both brake circuits 102 and 104 independently of the driver.

[0042] A switching device 118 is functionally provided between the wheel brakes 106, 108, 110, 112 on the one hand and the master cylinder 114 and the pressure generator 116 on the other. In the exemplary embodiment shown, the switching device 118 comprises Fig. 1 per brake circuit 102, 104 each one electrically operated 3 / 2-way valve 120, 122.

[0043] In the electrically unactuated state, valves 120 and 122 couple the wheel brakes 106, 108, 110, and 112 to the master cylinder according to the "push-through" principle. This ensures that, in the event of a failure of the vehicle's electrical or electronic systems, the vehicle can still be braked by means of hydraulic pressure generated by the driver in the master cylinder 114. In the electrically actuated state, according to... Fig. 1. The two valves 120 and 122 connect the wheel brakes 106, 108, 110, and 112 to the pressure generator 116. In this case, the pressure generator 116 can build up hydraulic pressure in the two brake circuits 102 and 104 during both driver-initiated service braking and system braking. Possible control scenarios for the pressure generator 116 in the case of electro-hydraulic and / or regenerative service braking will be explained in more detail later.

[0044] The master cylinder 114 is supplied with hydraulic fluid via a pressureless reservoir 124. When the 3 / 2-way valves 120, 122 are electrically actuated – i.e., when the master cylinder 114 is decoupled from the wheel brakes 106, 108, 110, 112 – the hydraulic fluid taken from the pressureless reservoir 124 is pumped by the master cylinder 114 into a pressurized reservoir 126. The pressurized reservoir 126 is a pedal feedback simulator which, due to the decoupling of the master cylinder 114 from the wheel brakes 106, 108, 110, 112, provides the driver with the familiar feedback behavior of a brake pedal 128 actuating the master cylinder 114. The main cylinder 114 and the pedal feedback simulation unit 126 can, for example, have the design known from DE 199 50 862 A1.The pedal feedback simulation unit 126 is based on the principle of the mechanical "cut-off", according to which the pedal feedback simulation function is switched on and off as a result of the displacement of a piston of the main cylinder 114.

[0045] As in Fig. As can be seen in Figure 1, a combined return / suction line 130 leads into the unpressurized hydraulic fluid reservoir 124. Hydraulic fluid from the wheel brakes 106, 108, 110, and 112 can flow back into the reservoir 124 via line 130. Furthermore, the pressure generator 116 can draw hydraulic fluid through this line 130. Following the suction process, the drawn hydraulic fluid is fed into the brake circuits 102 and 104 to build up hydraulic pressure in the wheel brakes 106, 108, 110, and 112 during service or system braking.

[0046] A valve assembly 132 is provided between the switching device 118 and the wheel brakes 106, 108, 110, 112 for driver-independent execution of brake interventions at the wheel brakes 106, 108, 110, 112. The valve assembly 132 comprises two (preferably non-controllable) shut-off valves per wheel brake, designed as 2 / 2-way valves. These valves allow pressure build-up, pressure holding, and pressure release phases to be carried out in a known manner within the framework of system braking, i.e., safety-relevant, driver-independent brake interventions. Such brake interventions can include, for example, ABS control interventions or ESC control interventions. Since such control interventions are known per se, they will not be described in more detail here.

[0047] The brake system 100 according to Fig. 1 further comprises a pressure adjusting device 134 for adjusting the hydraulic pressure centrally generated by the pressure generator 116 for individual brake circuits. In the exemplary embodiment according to Fig. 1 a control electronics unit 136 and a valve assembly with two (preferably non-controllable) shut-off valves 138, 140. As in Fig. As shown in Figure 1, valves 138 and 140 are electrically actuated valves that are open in the unactuated state ("Normally Open" or "NO"). The control electronics 136 are primarily intended for the pressure generator 116 and also enable optional control of valves 138 and 140.

[0048] As in Fig. As shown in Figure 1, each of the two valves 138, 140 is connected in parallel to a spring-loaded check valve 142, 144. The parallel connection of the check valves 142, 144 allows flow to bypass the closed valves 138, 140 towards the wheel brakes 106, 108, 110, 112. In this way, even when these valves 138, 140 are closed, pressure can be built up or increased at the wheel brakes 106, 108, 110, 112 by means of the pressure generator 116, provided that the pressure generated by the pressure generator 116 exceeds a predetermined threshold. This threshold is determined by the spring force acting on the check valves 142, 144.

[0049] Closing the two valves 138 and 140 is necessary, for example, when, during a driver-independent braking intervention (system braking), hydraulic fluid needs to be drawn from the unpressurized reservoir 124 by the pressure generator 116. This braking intervention could be an ABS or ESC control process.

[0050] The following explains the design and operation of the pressure generator 116. The function of the pressure generator 116 is to generate a central (i.e., single or uniform) hydraulic pressure for both brake circuits 102 and 104. The individual adjustment of the hydraulic pressure for each brake circuit is then carried out, as described above, by means of the pressure adjusting device 134 located downstream of the pressure generator 116.

[0051] The pressure generator 116 comprises an electric motor 146 controllable by means of the control electronics 136, a gearbox 148 downstream of the electric motor 146, and a cylinder / piston system 160 downstream of the gearbox 148. The cylinder / piston system 160 comprises a single hydraulic chamber 150, within which a plunger piston 152 is movably guided. The position of the plunger piston 152 within the hydraulic chamber 150—and thus the hydraulic pressure within the hydraulic chamber 150—is adjustable by means of the electric motor 146.

[0052] As in Fig. As shown in Figure 1, the hydraulic chamber 150 has a connection 154 through which hydraulic fluid can be drawn into and expelled from the chamber 150. The drawing in and expulsion of hydraulic fluid is effected by a stroke movement of the plunger piston 152.

[0053] Port 154 is fluidically coupled to the inlet side of each of the two valves 138, 140 of the pressure adjusting device 134. Port 154 is also fluidically coupled to the return line 130 via a spring-loaded check valve 156. The check valve 156 is arranged such that it opens during a suction stroke of the plunger piston and closes during a discharge stroke. In this way, hydraulic fluid can be pumped from the unpressurized reservoir 124 into the hydraulic chamber 150 without hydraulic fluid discharged from the hydraulic chamber 150 being able to flow directly back into the unpressurized reservoir 124.

[0054] Also fluidically coupled to connection 154 is a pressure sensor 158. The pressure sensor 158 provides an output signal to the control electronics 136. Based on this output signal, the control electronics 136 performs an actual value / target value comparison and generates control signals for the electric motor 136 based on this comparison. In this way, a closed control loop for hydraulic pressure generation during service braking or system braking is realized.

[0055] The embodiment according to Fig. The illustrated implementation of the pressure generator 116 has certain advantages over the use of other pressure generators such as multi-piston pumps. For example, the pressure accumulator for hydraulic fluid typically required in conventional multi-piston pumps can be omitted. Furthermore, the pressure pulsations typical of multi-piston pumps are eliminated, since, due to the dimensioning of the hydraulic chamber 150, a single stroke of the plunger piston 152 is generally sufficient to reduce a desired hydraulic pressure. In addition, the plunger approach proposed here is particularly suitable for the rapid build-up (on the order of 1000 bar / s) of a central hydraulic pressure with subsequent individual hydraulic pressure adjustment for each brake circuit.

[0056] The following describes the operation of the vehicle braking system 100 according to Fig. 1 and the brake circuit-specific adjustment of the hydraulic pressure centrally generated by the pressure generator 116 by means of the two valves 136, 140 of the pressure adjustment device 134 is described in more detail.

[0057] In an electro-hydraulic service brake, the control electronics 136 are designed to receive an output signal from a position or force sensor assigned to the brake pedal 128 (in Fig. (1 not shown) to evaluate. The control electronics 136 then generates control signals for the pressure generator 116 based on this output signal, so that it generates hydraulic pressure in the brake circuits 102, 104. The hydraulic pressure generated by the pressure generator 116 corresponds to the vehicle deceleration requested by the driver and communicated via the brake pedal 128.

[0058] During service braking in regenerative mode, the pressure generator 116 is activated by the control electronics 136 only if the driver's desired deceleration exceeds the vehicle deceleration achievable in generator mode (e.g., during a sudden re-entry of the brake pedal 128 during a previously initiated service braking maneuver). In this case, the control electronics 136 generates control signals for the pressure generator 116, which, during generator operation, are directed to additionally generate hydraulic pressure at at least two of the wheel brakes 106, 108, 110, 112 (front axle and / or rear axle). A first deceleration component therefore results from generator operation, while a second deceleration component is due to the actuation of at least two of the wheel brakes 106, 108, 110, 112.The control electronics 136 ensures that both deceleration components together correspond to the deceleration value requested by the driver at the brake pedal 128 for service braking.

[0059] As an alternative to the two scenarios described above, the printer 116 can also be controlled by the control electronics 136 in the event of system braking (and thus independently of actuation of the brake pedal 128). In the exemplary embodiment according to Fig. 1. The hydraulic pressure generated centrally by the pressure generator 116 can be adjusted individually for each brake circuit using the valves 138 and 140 of the pressure adjusting device 134. This brake circuit-specific hydraulic pressure adjustment will now be explained in more detail.

[0060] To build up hydraulic pressure in brake circuits 102 and 104, and thus at the wheel brakes 106, 108, 110, and 112, hydraulic pressure centrally supplied by pressure generator 116 is built up in both brake circuits 102 and 104, regardless of the position of the shut-off valves 138 and 140. This is due to the check valves 142 and 144, which are connected in parallel and open even at low pressure levels. To maintain pressure, both valves 138 and 140 are closed, preventing the hydraulic pressure built up in brake circuits 102 and 104 from escaping. However, these hydraulic pressures can be increased at any time via the check valves 142 and 144 (equal in magnitude for both brake circuits 102 and 104). For this purpose, the hydraulic pressure centrally supplied by pressure generator 116 simply needs to be increased further.

[0061] To reduce pressure, the hydraulic pressure centrally supplied by pressure generator 116 must be lowered again. The hydraulic pressures built up in brake circuits 102 and 104 can be reduced (and thus adjusted) individually for each brake circuit. For example, if, during a suction stroke of pressure generator 116, valve 138 assigned to brake circuit 102 is opened while valve 140 assigned to brake circuit 104 remains closed, only the hydraulic pressure in brake circuit 102 is reduced, while the hydraulic pressure in brake circuit 104 is maintained. Consequently, a hydraulic pressure difference arises between the two brake circuits 102 and 104.

[0062] In practical operation of the vehicle braking system 100, when the driver and / or automatically initiates braking, the desired hydraulic pressures or hydraulic pressure profiles are set by a targeted sequence of pressure build-up, pressure holding, and pressure release phases. For this purpose, the pressure generator 116 and the valves 138, 140 are controlled by the control electronics 136 in a suitable manner to implement brake circuit-specific hydraulic pressure settings if necessary. In the exemplary embodiment according to Fig. 1 The brake circuit-specific adjustment of the hydraulic pressures results primarily from the fact that, during pressure reduction phases, a pressure difference between the brake circuits 102, 104 can be set by individually opening one of the valves 138, 140.

[0063] The third valve unit 132 is available for ABS control, but also for supporting other driver-independent braking interventions (e.g. ESP control, brake assist or regenerative braking). As already mentioned, the third valve assembly 132 allows, in a known manner, individual wheel control of the hydraulic pressures and thus of the brake pressures in the wheel brakes 106, 108, 110, 112. For example, in order to pump hydraulic fluid drained into the unpressurized reservoir 124 during ABS control back into the brake circuits 102, 104, the associated brake circuits 102, 104 are brought into a pressure holding phase by closing both valves 138, 140 and the hydraulic pressure supplied centrally by the pressure generator 116 is reduced so much that hydraulic fluid from the unpressurized reservoir 124 can flow back into the hydraulic chamber 150 of the pressure generator 116 via the check valve 156.Subsequently, it is possible to further increase the hydraulic pressure maintained by the closed valves 138, 140 using the pressure generator 116 (by overflowing the closed valves 138, 140 via the check valves 142, 144).

[0064] Fig. Figure 2A shows a second embodiment of a vehicle braking system 100. The vehicle braking system 100 according to Fig. 2A largely corresponds to the vehicle braking system of the first embodiment. For this reason, only the differing design features are explained in more detail below. The deviations primarily concern the configuration of the pedal feedback simulation unit 126, the switching device 118, and the pressure adjustment device 134.

[0065] The pedal feedback simulation unit 126 was modified such that the simulation functionality is now switched on and off via an electromagnetically actuated 2 / 2-way valve. One possible implementation of the pedal feedback simulation unit 126 designed in this way is known from DE 196 38 102 A1. Another possible implementation for the pedal feedback simulation unit 126 with an external simulation spring is described in DE 10 2007 047 208 A1.

[0066] Both in the embodiment of the pedal feedback simulation unit 126 according to Fig. 1 as well as in the corresponding version in Fig. 2A The master cylinder 114 is designed for push-through operation according to a "twin" arrangement. This means that each of the two brake circuits 102, 104 is assigned its own actuating piston, with the two actuating pistons arranged parallel to each other. The relevant design details of the master cylinder 114 can be found in DE 10 2005 037 792 A1.

[0067] As in Fig. As shown in Figure 2A, the modified switching device now comprises four 2 / 2-way valves 120A, 122A, 120B, 122B instead of the two 3 / 2-way valves 120, 122 provided in the first embodiment. These valves are distributed across two functional units 118A, 118B of the switching device. A first functional unit 118A comprises one electrically actuated shut-off valve 120A, 122A per brake circuit, which is open in the unactuated state (“NO”). The second functional unit 118B comprises one electrically actuated shut-off valve 120B, 122B per brake circuit 102, 104, which is closed in the unactuated state (“Normally Closed” or “NC”). The second functional unit 118B further comprises a check valve 142, 144 connected in parallel to each valve 120B, 122B. The operation of the check valves 142, 144 with regard to overflow has already been explained in connection with the first embodiment.

[0068] Fig. Figure 2A illustrates the initial position of valves 120A, 122A, 120B, 122B in the electrically unactuated state. This state corresponds to the "push-through" operation, in which the wheel brakes 106, 108, 110, 112 are fluidically coupled to the master cylinder 114. To couple the pressure generator 116 to the wheel brakes 106, 108, 110, 112, valves 120A, 122A, 120B, 122B are electrically actuated, which simultaneously decouples the master cylinder 114 fluidically from the wheel brakes 106, 108, 112.

[0069] The modified pressure setting device 134 is provided between the two functional units 118A and 118B. In the exemplary embodiment, the pressure setting device 134 comprises as follows: Fig. 2A per brake circuit 102, 104, a controllable 2 / 2-way valve 138A, 140A. The pressure adjustment device 134 further includes control electronics 136A for controlling the two control valves 138A, 140A by means of pulse width modulation. The actuation state of the two valves 138A, 140A is thus individually and continuously adjustable between a fully open valve position and a fully closed valve position via the pulse width of the control signals supplied to the respective valve 138A, 140A.

[0070] Each valve 138A, 140A is connected in parallel to a check valve 138B, 140B. The combination of check valve 138B, 140B on the one hand and control valve 138A, 140A on the other hand enables pressure differential-based, brake circuit-specific hydraulic pressure adjustment, as described in more detail in DE 102 47 651 A1. The disclosure content of DE 102 47 651 A1 with regard to the design and operation of the control valves 138A, 140A is hereby incorporated by reference.

[0071] The key difference between the two embodiments of the Fig. 1 and Fig. 2A concerns the hydraulic pressure control. In the exemplary embodiment according to Fig. 1. The electric motor 146 is precisely controlled based on a comparison of actual and target values ​​using a signal provided by the pressure sensor 158. The pressure sensor 158 is connected directly downstream of the pressure generator 116. The hydraulic pressure is then adjusted individually for each brake circuit during pressure reduction phases using the adjustment device 134.

[0072] In the second embodiment according to Fig. In contrast, a different control concept is used in 2A. Here, for brake circuit-specific hydraulic pressure control, control signals are supplied to the two control valves 138A and 140A, each individually for its respective brake circuit. The control electronics 136A generate these control signals based on a comparison of actual and target values, taking into account output signals from the pressure sensors 158A and 158B downstream of the valves 138A and 140A.

[0073] In contrast to the embodiment according to Fig. 1 enables the embodiment according to Fig. 2A provides for brake circuit-specific hydraulic pressure adjustment, even during a pressure build-up phase. For example, when building up central hydraulic pressure using the pressure generator 116, the valve 120B assigned to brake circuit 102 can be opened and the valve 122B assigned to brake circuit 104 can be closed, regardless of the position of valves 138 and 140. In this switching state of valves 120B and 122B, only the hydraulic pressure in brake circuit 102 is increased, while the hydraulic pressure in brake circuit 104 is maintained. Accordingly, valves 120B and 122B can be functionally assigned to the pressure adjustment device 134 and controlled by the control electronics 136A.

[0074] Fig. Figure 2B illustrates a third embodiment of a vehicle braking system 100. The vehicle braking system 100 according to Fig. 2B largely corresponds to the vehicle braking system of the second embodiment. The key difference to the vehicle braking system of the second embodiment is that the valves 138A, 140A are no longer controlled based on a pressure differential. The check valves 138B, 140B have therefore been omitted.

[0075] Fig. Figure 2C shows a fourth embodiment of a vehicle braking system 100. The vehicle braking system 100 according to Fig. 2C largely corresponds to the vehicle braking system of the second embodiment. The main difference is that the two shut-off valves 138A, 140A with their associated check valves 138B, 140B have been omitted. Functionally, the valves 120B, 122B thus take over the function of the valves 138, 140 (with associated check valves 142, 144) of the second embodiment. Fig. 1. Compared to the embodiment shown in Fig. Therefore, the possibility of setting a pressure difference between brake circuits 102 and 104, even during a pressure build-up phase, was omitted in 2B.

[0076] In the embodiment according to Fig. 1. For safety reasons, the 3 / 2-way valves 120, 122 of the switching device 118 must be designed such that, in their electrically unactuated position, determined solely mechanically (by spring force), a connection exists between the master cylinder 114 and the brake circuits 102, 104, and a connection to the pressure generator 116 and the two 2 / 2-way valves 138, 140 is blocked. Therefore, the 2 / 2-way valves 138, 140 can be designed as either normally closed (NC) or normally open (NO) valves. In the embodiment according to Fig. For safety reasons, the two 2 / 2-way valves 120A, 122A, which connect to the master cylinder 114, must be designed as normally open (NO) valves. Furthermore, at least one of the two series-connected 2 / 2-way valves 138, 120B, 140, 122B must be designed as normally closed (NC) valves to prevent the connection to the pressure generator 116. The same applies to the embodiment according to 2B, and accordingly, the embodiment according to Fig. 2C the two 2 / 2-way valves 120A, 122A are designed as normally open (NO) valves and the other two 2 / 2-way valves 1208 / 138, 122B / 140 as normally closed (NC) valves.

[0077] As already mentioned, the desired hydraulic pressures or hydraulic pressure profiles are set by a targeted sequence of pressure build-up, pressure holding, and pressure release phases, which are achieved by selectively controlling the pressure generator 116 and the respective valves 120B, 122B, 138, 140, 142, 144 of the pressure setting device 134. In principle, brake circuit-specific hydraulic pressure setting is possible using "simple" valves that only have two defined switching positions. This requires the use of a relatively precisely adjustable central pressure generator 116. However, to find a compromise for reasons of complexity and associated costs, precisely controllable—and therefore technically more complex—valves can be used, which, for example, are proportional and / or controlled via a pressure differential (see...). Fig. 2A) are adjustable. Conversely, mechanical components of the pressure generator 116, such as the motor 146 and / or the gearbox 148, can be designed more simply – and therefore more cheaply.

[0078] Now, with reference to the Fig. Three to six different modular concepts for a hydraulic assembly are explained. The hydraulic assembly is for a vehicle braking system according to the [document / reference] in [document / reference]. Fig. 1 first embodiment is provided, wherein, to substantiate the modularity, the second embodiment is provided according to Fig. The unit presented in 2A consists of the master cylinder 114 and the pedal feedback simulation unit 126. For the sake of clarity, the following were included in the Fig. 3 to 6 not all reference symbols were adopted and the control electronics 136 was omitted.

[0079] In the following exemplary embodiments, the individual components of the vehicle's braking system are distributed across various subassemblies in different ways. Different types of each subassembly can exist, differing in the design of their individual components. Following a modular principle, the required type can then be selected from each subassembly in a first step. In a subsequent step, the selected types are assembled into the hydraulic assembly. The hydraulic assembly is then installed in the vehicle as a whole.

[0080] A first embodiment of the modular construction of a hydraulic assembly 300 is shown in Fig. Figure 3 shows the hydraulic assembly 300 comprising three subassemblies 302, 304, and 306. A first subassembly 302 comprises the master cylinder 114 with an associated pedal feedback simulation unit. A second subassembly 304 comprises the pressure generator 116, the switching device 118, and the pressure adjusting device 134. The second subassembly 304 also includes a control unit (“Electronic Control Unit” or “ECU”), which contains all the electronic components required for controlling the pressure generator 116, the switching device 118, and the pressure adjusting device 134 (such as the control electronics 136 according to Figure 3). Fig. 1) comprises. A third sub-assembly 106 includes the valve assembly 132 and a standard control unit 306A for controlling the valve assembly 132.

[0081] Fig. Figure 4 illustrates a further embodiment of the modular construction of a hydraulic assembly 400. Compared to the embodiment of Fig. In section 3, the two subassemblies 302 and 304 were combined into a single subassembly 402. A control unit 402A assigned to subassembly 402 largely corresponds functionally to control unit 304A according to... Fig. 3. A second subassembly 306 matches the corresponding subassembly. Fig. 3 match.

[0082] Fig. Figure 5 shows a third embodiment for the modular construction of a hydraulic assembly 500. According to Fig. The hydraulic assembly 500 is implemented in the form of a single sub-assembly 502. The sub-assembly 502 comprises a control unit 502A, which includes the necessary electronic components for controlling the pressure generator 116, the switching device 118, the valve assembly 132, and the pressure adjusting device 134.

[0083] Fig. Figure 6 shows a fourth embodiment of the modular construction of a hydraulic assembly 600. The hydraulic assembly 600 according to Fig. 6 comprises a first assembly 302, which is connected to the corresponding assembly from Fig. 3 corresponds. A second assembly 602 includes the pressure generator 116, the switching device 118, the valve device 132, and the pressure adjusting device 134. The subassembly 602 also includes a control unit 602A for the electrical control of the individual components of the subassembly 602.

[0084] Fig. Figure 7 shows an exploded view of subassembly 602 according to Fig. 6., and Fig. Figure 8 shows the subassembly 602 in its fully assembled state. As can be seen from these two figures, the electric motor 146, together with the gearbox 148 and the cylinder / piston system 160, forms a first assembly unit. A second assembly unit is formed by a housing block 702, which accommodates the valves and pressure sensors of the switching device 118, the valve assembly 132, and the pressure adjusting device 134. The valves and pressure sensors are located in Fig. 7 protrudes to the right over housing block 702 to be contacted by control unit 602A. For this purpose, control unit 602A is placed on housing block 702. Inside housing block 702 are the Fig. 6 illustrated fluid lines.

[0085] Fig. 9 is a sectional view of subassembly 602 according to the Fig. 7 and Fig. 8. Clearly visible are the electric motor 146, the gearbox 148 coupled to the electric motor on the output side (in the form of a belt drive), and a nut / spindle assembly 162 actuated by the gearbox 148. The nut / spindle assembly 162 comprises a spindle 166 driven by a belt 164 of the gearbox 148. The spindle 166 is coupled to a nut 170 of the nut / spindle assembly 162 via bearing balls 168. A rotational movement of the spindle 166 causes a translational movement of the nut 170, depending on the direction of rotation. Fig. 9 either to the left or right.

[0086] The nut 170 is rigidly coupled to the piston 152, which is guided in a fluid-tight manner in the hydraulic chamber 150. A translational movement of the nut 170 thus directly causes a stroke movement of the plunger piston 152 in the hydraulic chamber 150. During a suction stroke, the plunger piston 152 is Fig. 9 moves to the right, while during an ejection stroke the plunger piston 152 moves to the left.

[0087] In the section view according to Fig. Not visible is the combined intake / exhaust port 154. This is provided on the end face of the housing block 702 facing the plunger piston 152. Fig. Figure 9 clearly shows that the electric motor 146 is arranged parallel to the axis of the plunger piston 152. This arrangement allows for a compact design for the sub-assembly 602.

[0088] Fig. Figure 10 shows a perspective view of sub-assembly 502 of the modular concept according to Fig. 5. Subassembly 502 includes, in addition to those already mentioned in connection with the Fig. 7 and Fig. The 8 assembly units described include a master cylinder 114 and a pedal feedback simulation unit 126 (the unpressurized reservoir is in Fig.9 not shown, as it is not necessarily part of the subassembly).

[0089] As the exemplary description of the embodiments demonstrates, combining a central hydraulic pressure generator with subsequent brake circuit-specific hydraulic pressure adjustment results in a number of significant advantages. Further advantages arise from the various implementations of the optional modular system, according to which the hydraulic assembly is divided into different sub-assemblies. Naturally, the divisions of the hydraulic assembly into individual sub-assemblies described above are merely examples. In other words, alternative divisions are also possible.

Claims

[1] Hydraulic assembly for a vehicle braking system (100) with at least two brake circuits (102, 104) and wheel brakes (106, 108, 110, 112) assigned to the brake circuits (102, 104), wherein the hydraulic assembly comprises the following: a pressure generator (116) for the driver-independent generation of a central hydraulic pressure for the brake circuits (102, 104) at least during a service braking initiated by a driver; and at least one pressure adjustment device (134) for brake circuit-specific adjustment of the central hydraulic pressure generated by the pressure generator (116) independently of the driver, characterized by that the components included in the hydraulic assembly are assembled to form the hydraulic assembly and that the hydraulic assembly as a whole can be installed in the vehicle. [2] Hydraulic assembly according to claim 1, wherein the pressure adjusting device (134) comprises a first valve assembly (138, 140; 138A, 140A). [3] Hydraulic assembly according to claim 2, wherein the first valve assembly (130, 140; 138A, 140A) is electrically actuated to set a hydraulic pressure corresponding to the actuation state. [4] Hydraulic assembly according to claim 3, wherein the first valve device is electrically actuated by means of pulse width modulation, wherein the actuation state is adjustable via the pulse width. [5] Hydraulic assembly according to any one of claims 2 to 4, wherein the first valve assembly comprises: at least one adjusting valve (138, 140) that is adjustable at least between an open valve position and a closed valve position; and a first check valve (142, 144) connected in parallel to the adjusting valve (138, 140) in such a way that, in the closed valve position, an overflow of the adjusting valve towards the wheel brakes (106, 108, 110, 112) is made possible. [6] Hydraulic assembly according to one of the preceding claims, wherein the pressure generator (116) comprises a suction port (154) for hydraulic fluid and a discharge port (154) for hydraulic fluid which are fluidically coupled or can be coupled together, wherein a second valve assembly (156) is provided in a suction line (130) which opens into the suction port (154). [7] Hydraulic assembly according to claim 6, wherein the second valve assembly comprises a second check valve (156) which opens when hydraulic fluid is drawn in by the pressure generator (116) and closes when hydraulic fluid is expelled by the pressure generator (116). [8] Hydraulic assembly according to one of the preceding claims, wherein the pressure generator (116) comprises a hydraulic chamber (150) for receiving hydraulic fluid and a plunger piston (152) movable within the hydraulic chamber for generating the central hydraulic pressure independently of the driver, wherein the brake circuits (102, 104) can be supplied with hydraulic fluid from the hydraulic chamber (150). [9] Hydraulic assembly according to claim 8, further comprising an electric motor (146) for actuating the plunger piston (152). [10] Hydraulic assembly according to claim 9, wherein the pressure adjustment device (134) comprises a first control unit (136) for the electric motor (146). [11] Hydraulic assembly according to claim 9 or 10, wherein the electric motor (146) is arranged parallel to the axis of the plunger piston (152). [12] Hydraulic assembly according to one of claims 9 to 11, wherein a gearbox (148) is provided between the electric motor (146) and the pressure generator (116). [13] Hydraulic assembly according to one of the preceding claims, further comprising a switching device (118) for selectively coupling the wheel brakes (106, 108, 110, 112) with either the hydraulic pressure generated independently of the driver or a hydraulic pressure generated by a driver. [14] Hydraulic assembly according to claim 13, wherein the switching device (118) is electrically actuated and in an unactuated state couples the wheel brakes (106, 108, 110, 112) with a driver-operated master cylinder (114) and in an actuated state couples the wheel brakes (106, 108, 110, 112) with the pressure generator (116). [15] Hydraulic assembly according to claim 13 or 14, wherein the switching device (118) comprises one 3 / 2-way valve (120, 122) or two 2 / 2-way valves (120A, 122A; 12013, 12213) per brake circuit (102, 104). [16] Hydraulic assembly according to one of claims 13 to 15, wherein at least the switching device (118), the pressure setting device (134) and the pressure generator (116) form a self-manageable first subassembly. [17] Hydraulic assembly according to claim 16 in combination with claim 14, wherein the main cylinder (114) is part of the first subassembly (402, 502). [18] Hydraulic assembly according to one of the preceding claims, further comprising a third valve assembly (132) for driver-independent execution of brake interventions on the wheel brakes (106, 108, 110, 112), wherein the third valve assembly (132) is arranged in the brake circuits between the pressure adjusting device and the wheel brakes (106, 108, 110, 112). [19] Hydraulic assembly according to claim 18 in combination with claim 16, wherein the third valve assembly (132) is part of the first subassembly (502, 602). [20] Hydraulic assembly according to one of claims 18 or 19, wherein the third valve arrangement (132) comprises exclusively non-controllable shut-off valves. [21] Hydraulic assembly according to one of the preceding claims, further comprising a second control unit (306A, 502A, 602A) for driver-independent execution of brake interventions on the wheel brakes (106, 108, 110, 112), wherein the second control unit (306A, 502A, 602A) is designed to control the pressure generator (116) in order to build up brake pressure independently of the driver. [22] Hydraulic assembly according to claim 21 in combination with claims 10, 16 and 19, wherein the first control unit and the second control unit are designed as a common control unit (502A, 602A) which is part of the first subassembly (502, 602). [23] Hydraulic assembly according to one of the preceding claims, further comprising a third control unit (502A, 602A) for regenerative braking operation, wherein the third control unit (502A, 602A) is designed to control the pressure generator (116) in regenerative braking operation in order to build up brake pressure independently of the driver. [24] Hydraulic assembly according to claim 23, further comprising a pedal feedback simulation unit (126) which can be actuated in regenerative braking operation by a hydraulic pressure generated by a driver. [25] Hydraulic assembly according to claim 24 in combination with claim 16 or 17, wherein the pedal feedback simulation unit (126) is part of the first subassembly (402, 502). [26] Electro-hydraulic vehicle braking system (100) comprising the hydraulic assembly according to any of the preceding claims. [27] Regenerative vehicle braking system (100) comprising the hydraulic assembly according to any one of claims 1 to 25.

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