Pressure providing assembly for brake system and brake system

Abstract

The invention relates to a pressure providing arrangement for a brake system of a motor vehicle, the pressure providing arrangement having two pumps and at least one pressure-controlled first valve, the first valve deactivating one of the two pumps at a greater pressure. The invention also relates to a brake system having such a pressure providing assembly.

Description

Technical Field

[0001] The invention relates to a pressure supply assembly for a brake system of a motor vehicle and to a brake system having such a pressure supply assembly. Background Art

[0002] Braking systems are typically used to intentionally decelerate motor vehicles. While earlier braking systems typically relied on human muscle power to build up pressure in brake cylinders, which was then applied to the wheel brakes, with additional pressure applied as needed, newer braking systems are typically designed so that pressure is generated electrically, at least during normal braking operation. This typically involves a pump, typically driven by an electric motor, to build up pressure. Combining two pumps, and optionally additional components, can be referred to as a pressure supply assembly. Summary of the Invention

[0003] The present invention is based on the object of providing a pressure supply assembly that is designed as an alternative or better alternative to known embodiments. Furthermore, the present invention is based on the object of providing a brake system having such a pressure supply assembly. According to the invention, this is achieved by a pressure supply assembly and a brake system according to the corresponding main claim. Advantageous embodiments can be derived, for example, from the corresponding dependent claims. The content of the claims is provided by explicit reference to the description.

[0004] The present invention relates to a pressure supply assembly for a braking system of a motor vehicle. The pressure supply assembly comprises a first pump, a second pump, and a first pressure-controlled valve. The output of the first pump is fluidically connected to a common reference point via the first valve. The output of the second pump is fluidically connected directly to the common reference point. The first valve is designed to assume an open state when the pressure at the common reference point is below a first pressure threshold and to assume a closed state when the pressure at the common reference point is at least as great as the first pressure threshold.

[0005] With the aid of such a pressure supply assembly, pressure can be built up via the two pumps mentioned. At low pressures, the two pumps work together, thereby accelerating pressure buildup. At higher pressures, particularly above a first pressure threshold, only the second pump becomes active, decoupling the first pump. Consequently, the torque required to operate the first pump can be used to operate the second pump. This allows for more efficient use of the available torque and the achievement of higher pressures.

[0006] A pressure control valve is generally understood to be a valve that connects two interfaces in a switchable manner and is controlled based on the pressure at one of the interfaces. This pressure can be an absolute pressure or a pressure difference between the two interfaces. The common reference point is an auxiliary structure with the above-mentioned characteristics and can, in principle, be any suitable point in the line or reservoir. Specifically, the output of the first pump is fluidically connected to the common reference point via the first valve, and the output of the second pump is fluidically connected directly to the common reference point.

[0007] According to an advantageous embodiment, the pressure supply assembly includes a pressure-controlled second valve. The second valve can, in particular, fluidically connect the first pump's output to its input at a point between the first valve and the first pump. Therefore, when the second valve is open, the first pump is short-circuited, and the wheel brakes are connected to the input of the first pump, which is typically connected to a brake fluid reservoir, via the two valves. This protects the wheel brakes from overpressure, particularly when stationary.

[0008] The second valve can be pressure-controlled and can be designed to be open when the pressure at the pressure tapping point between the output of the first pump and the first valve is below a second pressure threshold, and to be closed when the pressure at the pressure tapping point is at least as high as the second pressure threshold. Thus, in the event of low pressure, it can be provided that the first pump is short-circuited.

[0009] The pressure tapping point can be arbitrarily located between the output of the first pump and the first valve. Typically, a line is connected to the pressure tapping point, which is connected to the second valve in such a way that the second valve is controlled based on the pressure applied to the pressure tapping point. The pressure tapping point can coincide with the point to which the second valve is connected, but it can also be located elsewhere. Typically, the back pressure generated by the first valve acts on the pressure tapping point, causing the pressure at the pressure tapping point to increase when the first pump is running.

[0010] In particular, the first valve can be designed to open the second valve when the first valve is closed. Thus, in situations where only the second pump should be responsible for pressure buildup, the first pump can be forced to short-circuit, in particular regardless of the applied pressure. This minimizes the energy demand of the first pump during idling.

[0011] In particular, the first valve can be mechanically connected to the second valve to close the second valve. This allows for simple and reliable actuation. Alternatively, the state of the first valve can also be detected electronically and the first valve can be controlled based on this.

[0012] In particular, the first pressure threshold can be greater than the second pressure threshold. The first pump typically generates back pressure at the first valve, which in turn actuates the second valve. When the second pressure threshold is exceeded, the second valve closes, allowing further pressure buildup via both pumps. When the first pressure threshold is exceeded, pressure buildup is again solely performed by the second pump, allowing even greater pressures to be achieved.

[0013] In particular, the pressure supply assembly can include a brake fluid reservoir, to which the first and second pumps are connected on the inlet side. This allows for appropriate replenishment of the brake fluid via both pumps. A connection for such a brake fluid reservoir may also be provided.

[0014] In particular, the pressure supply assembly can include a motor, which can be an electric motor, and which is preferably designed to drive the first pump and the second pump. In particular, the first pump and the second pump are driven by a single motor. This can be achieved, in particular, via a shared shaft. Typically, the two pumps are driven at the same speed and with the drive torque for both pumps added. This advantageously eliminates the need for an additional motor.

[0015] The first pump can be designed in particular as a reversible rotary working pump. The second pump can be designed in particular as a reversible rotary working pump. Such pumps have proven to be particularly effective for the applications described herein. In particular, gear pumps, vane unit pumps, or other pumps of suitable design can be used.

[0016] The present invention further relates to a braking system for a motor vehicle. The braking system has a pressure supply assembly as described herein for providing hydraulic pressure. With regard to the pressure supply assembly, all embodiments and variants described herein can be used.

[0017] In particular, an actuator assembly or a pressure supply component for generating brake pressure is provided. In particular, the pressure supply component has the following:

[0018] an electric motor, in particular having an electric regulating unit;

[0019] Two rotary and reversible pumps, for example gear pumps, which are driven by a motor via a common shaft;

[0020] a first pressure valve which, if the pressure at the output of the second pump is exceeded, cuts off the connection to the output of the first pump, actuates the second pressure valve and opens the connection from the first pump to the container;

[0021] a second pressure valve which, as a result of the pressure buildup at the output of the first pump, shuts off the connection to the container;

[0022] A brake fluid reservoir, which preferably has at least two chambers and preferably has an alarm device.

[0023] When actuating the brake, the motor is typically operated, and both pumps deliver in parallel. Here, the back pressure at the output of the first pump closes the second pressure valve, thereby blocking the return flow to the reservoir. As the pressure increases, the first pressure valve closes, and a mechanical connection with the second pressure valve opens the connection from the output of the first pump to the reservoir. Thus, circulation from the output of the first pump to the reservoir occurs at a low back pressure. Consequently, the torque required by the motor is reduced, and can be used to further increase the pressure in the brake even with a reduced volume flow from the second pump.

[0024] The delivery volume of a pump (e.g., expressed in cubic centimeters per revolution) generally determines the delivery performance (as a linear function of the rotational speed) and the required drive torque (as a function of the pressure). When two pumps are connected in parallel, both the volume flow and the torque are additive. By "switching off" or deactivating the first pump at the switching point configured by the first valve, the delivery performance is reduced proportionally to the volumes of both pumps. This is generally compatible with the function, as the brake caliper absorbs a smaller volume as the pressure increases. This advantageously reduces the torque, allowing significantly higher pressures to be achieved with the same motor torque.

[0025] In general, the rotary-translational transmission can be omitted in this embodiment. Conventional motors can be used, especially those without a hollow shaft and / or axial bearings, which are often subject to high loads. The two-stage transmission allows the motor design to significantly reduce torque. Size, weight, and costs can be significantly reduced. The electronic control does not necessarily have to be assigned to the solenoid valves or pressure sensors, so the control can, for example, be advantageously integrated into the motor housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A person skilled in the art will derive further features and advantages from the embodiments described below with reference to the accompanying drawings. In the drawings:

[0027] Figure 1 : shows a braking system according to an embodiment. DETAILED DESCRIPTION

[0028] Figure 1 The figure shows a brake system 10 according to an embodiment of the present invention. The brake system 10 has a pressure supply component 21 in the form of an actuator and a regulator 22. These components are distributed as shown. Alternatively, they can also be implemented together in a single block.

[0029] The pressure supply assembly 21 includes a first pump ZP1 and a second pump ZP2. These pumps are designed as rotary, reversible gear pumps. They are connected to a motor 25, which drives both pumps ZP1 and ZP2 via a common shaft and, therefore, in principle, at the same rotational speed. The motor 25 is an electric motor.

[0030] The two pumps ZP1, ZP2 are connected to the brake fluid reservoir 30 on the input side. Thus, these pumps can draw in brake fluid. The first pump ZP1 is connected to a first pressure-controlled valve DV1 and a second pressure-controlled valve DV2 on the output side. The second pump ZP2 is directly connected to the common reference point 27. The first valve DV1 is also connected to the common reference point 27. Figure 1 This is clearly visible. In principle, the first valve DV1 opens and closes based on the pressure applied at the common reference point 27. In principle, the second valve DV2 opens and closes based on the pressure applied downstream of the output of the first pump ZP1. When the first pump ZP1 is operating, a certain backpressure already exists due to the first valve DV1. Opposite the output of the first pump ZP1, the second valve is connected to the brake fluid reservoir 30 and to the inputs of both pumps ZP1 and ZP2. Thus, opening the second valve DV2 can short-circuit the first pump ZP1. Both valves DV1 and DV2 are designed to be open when pressure is depleted.

[0031] As illustrated by the upwardly pointing stem, the first valve DV1 is designed to open the second valve DV2 when the first valve DV1 is closed.

[0032] Common reference point 27 is connected via a sequence valve PFV (Zuschaltventil) to two inlet valves E3 and E4. The sequence valve PFV is also connected to two further inlet valves E1 and E2 via a circuit separation valve CSV. Two electrically driven piston pumps KP1 and KP2 are also connected to the circuit separation valve CSV and the two inlet valves E1 and E2. In contrast to the pump connections, the inlet valves E are each connected to the corresponding wheel brakes B1, B2, B3, and B4. The corresponding outlet valves A1, A2, A3, and A4 are also each connected to the wheel brakes B, which in turn are connected to the brake fluid reservoir 30. This embodiment will only be briefly discussed here.

[0033] In principle, the two piston pumps KP1, KP2 can be used independently of the first and second pumps ZP1, ZP2 to build up pressure. This can be important, for example, if the pressure supply assembly 21 fails due to a fault and the regulator 22 is solely responsible for building up pressure. To this end, the regulator 22 has a control unit ECU Mod.

[0034] When pressure supply assembly 21 is used to build pressure, motor 25 is activated. An electronic control unit (ECUAct) is used for this purpose. In principle, motor 25 drives first pump ZP1 and second pump ZP2 at the same speed. At very low pressures (as would be expected when both pumps ZP1 and ZP2 are at rest), both valves DV1 and DV2 are open. When the output of first pump ZP1 reaches a second pressure threshold due to drive and back pressure, second valve DV2 closes, thereby ensuring that first pump ZP1 can deliver volume and build pressure. Thus, both pumps ZP1 and ZP2 build pressure together, promoting faster pressure buildup. When the pressure reaches the first pressure threshold, first valve DV1 closes, thereby decoupling first pump ZP1 from the common reference point 27. Simultaneously, through a mechanical coupling, first valve DV1 opens second valve DV2, short-circuiting first pump ZP1. The torque generated by motor 25 then acts solely on second pump ZP2. Although the first pump ZP1 is still running, it no longer generates pressure and, due to the short circuit between its input and its output, is almost no longer relevant in terms of torque and energy consumption. Therefore, the second pump ZP2 can generate an even greater pressure alone, at which almost the entire torque of the motor 25 is available.

[0035] In particular, it has proven advantageous that the functionality of the two valves DV1 , DV2 can be realized solely mechanically and that it is therefore sufficient to control only the motor 25 for the pressure supply assembly 21 . The actuator control device ECUAct can therefore be designed in a simple manner.

[0036] It should be noted that, for example, for ease of understanding, features may be described in combination in the claims and description even if these features can also be used separately from each other. Those skilled in the art recognize that such features can also be combined independently of each other with other features or combinations of features.

[0037] The references in the dependent claims may characterize preferred combinations of individual features, but do not exclude other combinations of features.

[0038] List of Reference Numerals

[0039] 10. Braking system

[0040] 21 Pressure supply assembly

[0041] 22 Regulator

[0042] 25 motor

[0043] 27 Common reference point

[0044] 30 Brake fluid container

[0045] ECU Act Electronic Control Unit for Pressure Supply Components or Actuators

[0046] ECU Mod Regulator Electronic Control Unit

[0047] ZP1 first pump

[0048] ZP2 Second Pump

[0049] DV1 first valve

[0050] DV2 Second valve

[0051] PFV Sequence Valve

[0052] E Inlet valve

[0053] A Outlet valve

[0054] B wheel brake

[0055] KP piston pump

[0056] CSV circuit separation valve

Claims

1. A pressure supply assembly (21) for a braking system (10) of a motor vehicle, wherein the pressure supply assembly (21) comprises: - a first pump (ZP1); - a second pump (ZP2); and - pressure-controlled first valve (DV1), - wherein the output of the first pump (ZP1) is fluidically connected to a common reference point (27) via the first valve (DV1), - wherein the output of the second pump (ZP2) is directly fluidically connected to the common reference point (27), and - wherein the first valve (DV1) is designed to: assume an open state when the pressure at the common reference point (27) is below a first pressure threshold; and to assume a closed state when the pressure at the common reference point (27) is at least as great as the first pressure threshold.

2. The pressure providing assembly (21) according to claim 1, - wherein the pressure supply assembly (21) has a second valve (DV2), - wherein the second valve (DV2) fluidically connects a point between the output of the first pump (ZP1) and the first valve (DV1) to the input of the first pump (ZP1).

3. The pressure providing assembly (21) according to claim 2, - wherein the second valve (DV2) is pressure-controlled and is designed to: assume an open state when the pressure at a pressure tapping point between the output end of the first pump (ZP1) and the first valve (DV1) is lower than a second pressure threshold; and to assume a closed state when the pressure at the pressure tapping point is at least as great as the second pressure threshold.

4. The pressure providing assembly (21) according to claim 2 or 3, - wherein the first valve (DV1) is designed to open the second valve (DV2) when the first valve (DV1) is closed.

5. The pressure providing assembly (21) according to claim 4, - wherein the first valve (DV1) is mechanically connected to the second valve (DV2) to close the second valve (DV2).

6. A pressure providing assembly (21) according to claim 3 or a claim appended thereto, - wherein the first pressure threshold is greater than the second pressure threshold.

7. The pressure providing assembly (21) according to one of the preceding claims, The pressure supply assembly further comprises a brake fluid reservoir (30), to which the first pump (ZP1) and the second pump (ZP2) are connected on the input side.

8. The pressure providing assembly (21) according to one of the preceding claims, The pressure supply assembly further comprises a motor (25) designed to drive the first pump (ZP1) and the second pump (ZP2).

9. The pressure providing assembly (21) according to one of the preceding claims, - wherein the first pump (ZP1) is designed as a reversible rotary working pump, and / or - wherein the second pump (ZP2) is designed as a reversible rotary working pump.

10. A braking system (10) of a motor vehicle, wherein the braking system (10) comprises a pressure supply assembly (21) according to one of the preceding claims for providing hydraulic pressure.

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