DE102024108994A1 - Pressure supply arrangement for a braking system and braking system - Google Patents

Abstract

The invention relates to a pressure supply arrangement for a braking system of a motor vehicle, wherein the pressure supply arrangement comprises two pumps and at least one pressure-controlled first valve, which deactivates one of the two pumps at higher pressure. The invention further relates to a braking system with such a pressure supply arrangement.

Description

The invention relates to a pressure supply arrangement for a braking system of a motor vehicle and to a braking system with such a pressure supply arrangement.

Braking systems are typically used to deliberately decelerate motor vehicles. While earlier braking systems were typically based on human muscle power building up pressure in a brake cylinder, which then acts on the wheel brakes, with this pressure being assisted if necessary, newer braking systems are typically designed so that the pressure is generated electrically, at least during normal braking operation. Pumps are typically used for this purpose, which serve to build up pressure and are typically driven by an electric motor. If two pumps, and possibly other components, are combined, this can be referred to as a pressure supply arrangement.

It is an object of the invention to provide a pressure supply arrangement that is alternative to or better than known designs. It is also an object of the invention to provide a braking system with such a pressure supply arrangement. This is achieved according to the invention by a pressure supply arrangement and a braking system according to the respective main claims. Advantageous embodiments can be found, for example, in the respective subclaims. The content of the claims is incorporated into the content of the description by express reference.

The invention relates to a pressure supply arrangement for a braking system of a motor vehicle. The pressure supply arrangement comprises a first pump and a second pump, as well as a pressure-controlled first valve. An output of the first pump is fluidically connected to a common reference point via the first valve. An 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 a 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 high as the first pressure threshold.

Using such a pressure supply arrangement, pressure can be built up via the two aforementioned pumps. At low pressure, the two pumps work together, thus accelerating the pressure buildup. At higher pressures, particularly at a pressure above the first pressure threshold, only the second pump operates, with the first pump being disconnected, thus making the torque required to drive the first pump available to operate the second pump. This allows for more efficient use of the available torque and the achievement of a higher pressure.

A pressure-controlled valve is typically understood to be a valve that switchably connects two ports and is controlled based on a pressure at one of the two ports. This can be either an absolute pressure or a pressure difference between the two ports. The aforementioned common reference point is an auxiliary construct and can fundamentally refer to any suitable point in a line or reservoir that has the aforementioned properties, i.e., in particular, that the outlet of the first pump is fluidically connected to the common reference point via the first valve and the outlet of the second pump is fluidically connected directly to the common reference point.

According to an advantageous embodiment, the pressure supply arrangement has a pressure-controlled second valve. The second valve can, in particular, fluidically connect a point between the outlet of the first pump and the first valve to an inlet of the first pump. As a result, when the second valve is opened, the first pump is short-circuited, and the wheel brakes are connected via both valves to the inlet of the first pump, which is typically connected to a brake fluid reservoir. This allows the wheel brakes to be kept free of excess pressure, especially when stationary.

The second valve can, in particular, be pressure-controlled and can, in particular, be configured to assume an open state when a pressure at a pressure tap point between the outlet of the first pump and the first valve is below a second pressure threshold, and to assume a closed state when the pressure at the pressure tap point is at least as high as the second pressure threshold. This allows for the first pump to be short-circuited in the case of low pressures.

The pressure tap point can be located anywhere between the outlet of the first pump and the first valve. Typically, a line is connected to the pressure tap point, which is connected to the second valve in such a way that The second valve is controlled depending on the pressure at the pressure tap point. The pressure tap point can be identical to the point to which the second valve is connected, but it can also be located at a different location. Typically, a back pressure generated by the first valve acts at the pressure tap point, so that when the first pump is operating, the pressure at the pressure tap point is increased.

In particular, the first valve can be configured to open the second valve when the first valve closes. This allows the first pump to be forced to short-circuit if only the second pump is required to build up pressure, regardless of the pressure present. This minimizes the energy consumption of the first pump during idle operation.

In particular, the first valve can be mechanically connected to the second valve to close the second valve. This allows for simple and reliable operation. Alternatively, electronic detection of the state of the first valve and subsequent activation of the first valve would also be possible.

In particular, the first pressure threshold can be greater than the second pressure threshold. The first pump typically generates a back pressure at the first valve, which controls the second valve. If the second pressure threshold is exceeded, the second valve closes, thus further pressure buildup occurs through both pumps. If the first pressure threshold is exceeded, the pressure buildup occurs again only through the second pump, allowing an even higher pressure to be achieved.

In particular, the pressure supply arrangement can comprise a brake fluid reservoir to which the first pump and the second pump are connected on the inlet side. This allows for suitable replenishment of brake fluid by the two pumps. A connection for such a brake fluid reservoir can also be provided.

In particular, the pressure supply arrangement can comprise a motor, which can in particular be an electric motor, and which is preferably designed to drive the first pump and the second pump. In particular, both the first pump and the second pump are driven by a single motor. This can be achieved, in particular, via a common shaft. Typically, the two pumps are driven at the same speed and by adding the drive torques of both pumps. The provision of an additional motor can thus advantageously be dispensed with.

The first pump can be designed, in particular, as a reversible rotary pump. The second pump can be designed, in particular, as a reversible rotary pump. Such pumps have proven particularly suitable for the application described herein. In particular, gear pumps, vane pumps, or other suitably designed pumps can be used.

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

• - Elektromotor, insbesondere mit elektrischer Regeleinheit,
• - zwei mittels einer gemeinsamen Welle vom Motor angetriebene rotatorische und reversierbare Pumpen, beispielsweise Zahnradpumpen,
• - ein erstes Druckventil, welches bei Überschreiten eines Drucks am Ausgang der zweiten Pumpe sowohl eine Verbindung zum Ausgang der ersten Pumpe schließt als auch ein zweites Druckventil betätigt und eine Verbindung von der ersten Pumpe zu einem Behälter öffnet,
• - ein zweites Druckventil, welches durch Druckaufbau am Ausgang einer ersten Pumpe eine Verbindung zum Behälter schließt,
• - einen Bremsflüssigkeitsbehälter mit vorzugsweise mindestens zwei Kammern und vorzugsweise mit Warneinrichtung.

In particular, an actuator unit or a pressure supply arrangement for generating brake pressure is provided herein. In particular, this comprises the following:

• - electric motor, in particular with electric control unit,
• - two rotary and reversible pumps driven by the motor via a common shaft, for example gear pumps,
• - a first pressure valve which, when a pressure at the outlet of the second pump is exceeded, closes a connection to the outlet of the first pump and also actuates a second pressure valve and opens a connection from the first pump to a container,
• - a second pressure valve, which closes a connection to the container by building up pressure at the outlet of a first pump,
• - a brake fluid reservoir with preferably at least two chambers and preferably with a warning device.

When the brake is applied, the motor is typically activated, and both pumps deliver in parallel. The back pressure at the outlet of the first pump closes the second pressure valve and thus the return line to the reservoir. As the pressure increases, the first pressure valve is closed, and a connection from the outlet of the first pump to the reservoir is opened by mechanical coupling with the second pressure valve. This creates a circulation path from the outlet of the first pump to the reservoir with a low back pressure. The torque required by the motor is thus reduced and can be used to further increase the pressure in the brake. with reduced flow rate from the second pump.

The pump's displacement (specified, for example, in cubic centimeters per revolution) typically determines both the flow rate (as a linear function of speed) and the required drive torque as a function of pressure. In the selected parallel connection of both pumps, both the flow rate and the torque add up. By "switching off" or deactivating the first pump at a switching point configured by the first valve, the flow rate is reduced in proportion to the volumes of both pumps. This is generally compatible with the function because brake calipers absorb less volume as pressure increases. Reducing the torque is advantageous, as it allows a significantly higher pressure to be achieved with the same motor torque.

Typically, this design eliminates the need for a rotation-translation gearbox. A conventional motor can be used, particularly one without a hollow shaft and/or without axial bearings, which are often subject to high loads. A two-stage gearbox allows the motor to be designed for significantly lower torque. Size, weight, and costs can be significantly reduced. An electronic control device does not necessarily have to be associated with solenoid valves or pressure sensors, allowing a control device to be advantageously integrated into a motor housing, for example.

• 1: ein Bremssystem gemäß einem Ausführungsbeispiel.

Further features and advantages will become apparent to those skilled in the art from the exemplary embodiment described below with reference to the accompanying drawings. These show:

• 1 : a braking system according to an embodiment.

1 shows a braking system 10 according to an embodiment of the invention. The braking system 10 comprises a pressure supply arrangement 21 in the form of an actuator and a modulator 22. These are divided as shown. Alternatively, a combined design in a single block would also be possible.

The pressure supply arrangement 21 comprises a first pump ZP1 and a second pump ZP2. These are designed as rotary and reversible gear pumps. They are connected to a motor 25, which drives both pumps ZP1 and ZP2 via a common shaft and thus generally at the same speed. The motor 25 is an electric motor.

On the inlet side, the two pumps ZP1 and ZP2 are connected to a brake fluid reservoir 30. This allows them to draw in brake fluid. The first pump ZP1 is connected on the outlet side to a pressure-controlled first valve DV1 and a pressure-controlled second valve DV2. The second pump ZP2 is directly connected to a common reference point 27. The first valve DV1 is also connected to this common reference point 27, as shown in 1 can be clearly seen. The first valve DV1 basically opens and closes based on the pressure present at the common reference point 27. The second valve DV2 basically opens and closes based on a pressure present downstream of the outlet of the first pump ZP1, whereby a certain back pressure is already exerted by the first valve DV1 when the first pump ZP1 is in operation. It is connected to the brake fluid reservoir 30 and to the inlets of the two pumps ZP1, ZP2, opposite the outlet of the first pump ZP1. This means that the first pump ZP1 can be short-circuited by opening the second valve DV2. Both valves DV1, DV2 are designed to be open when depressurized.

The first valve DV1 is designed, as indicated by an upwardly pointing rod, to open the second valve DV2 when the first valve DV1 is closed.

The common reference point 27 is connected to two inlet valves E3, E4 via a PFV sequence valve. The PFV sequence valve is also connected to two further inlet valves E1, E2 via a CSV circuit isolation valve. Two electrically driven piston pumps KP1, KP2 are also connected to the CSV circuit isolation valve and the two inlet valves E1, E2. Opposite the connections to the pumps, the inlet valves E are connected to the respective wheel brakes B1, B2, B3, B4. Also connected to these wheel brakes B are respective outlet valves A1, A2, A3, A4, which in turn are connected to the brake fluid reservoir 30. This embodiment will only be briefly discussed here.

The two piston pumps KP1, KP2 can, in principle, be used to build up pressure independently of the first pump ZP1 and the second pump ZP2. This can be relevant, for example, if the pressure supply arrangement 21 fails due to a malfunction and the modulator 22 alone ensures pressure buildup. For this purpose, the modulator 22 has a control device ECU Mod.

When the pressure supply arrangement 21 is used to build up pressure, the engine 25 is activated. An electronic control unit ECU Act is used for this purpose. The motor 25 generally drives the first pump ZP1 and the second pump ZP2 at the same speed. At very low pressure, as can be expected when both pumps ZP1, ZP2 are at a standstill, both valves DV1, DV2 are open. When the second pressure threshold is reached at the outlet of the first pump ZP1 due to drive and back pressure, the second valve DV2 closes and thus ensures that the first pump ZP1 can deliver volume and build up pressure. The two pumps ZP1, ZP2 then build up pressure together, which leads to a faster pressure build-up. When the pressure reaches a first pressure threshold, the first valve DV1 closes, thereby decoupling the first pump ZP1 from the common reference point 27. At the same time, the first valve DV1 opens the second valve DV2 via a mechanical coupling, so that the first pump ZP1 is short-circuited. The torque generated by motor 25 then acts only on the second pump ZP2. The first pump ZP1 is still running, but no longer builds up pressure and, due to the short circuit between its input and output, is no longer relevant in terms of absorbing torque and energy. The second pump ZP2 can thus build up even greater pressure on its own, for which almost the entire torque of motor 25 is available.

It has proven particularly advantageous that the functionality of the two valves DV1, DV2 can be implemented purely mechanically, and therefore, for the pressure supply arrangement 21, only control of the motor 25 is sufficient. Accordingly, the actuator's control device ECU Act can be designed simply.

It should be noted that features may be described in combination in the claims and the description, for example, to facilitate understanding, although they may also be used separately. Those skilled in the art will recognize that such features may also be combined independently with other features or combinations of features.

References in subclaims may indicate preferred combinations of the respective features, but do not exclude other combinations of features.

List of reference symbols

10

braking system

21

Print provision arrangement

22

modulator

25

Motor

27

common reference point

30

brake fluid reservoir

ECU

Act electronic control device of the pressure supply arrangement or actuator

ECU

Mod electronic control device of the modulator

ZP1

first pump

ZP2

second pump

DV1

first valve

DV2

second valve

PFV

Sequence valve

E

Inlet valve

A

outlet valve

B

Wheel brake

KP

Piston pump

CSV

Circuit isolation valve

Claims (10)

A pressure supply arrangement (21) for a braking system (10) of a motor vehicle, the pressure supply arrangement (21) comprising: - a first pump (ZP1), - a second pump (ZP2), and - a pressure-controlled first valve (DV1), - wherein an output of the first pump (ZP1) is fluidically connected to a common reference point (27) via the first valve (DV1), - wherein an output of the second pump (ZP2) is fluidically connected directly to the common reference point (27), and - wherein the first valve (DV1) is configured to assume an open state when a pressure at the common reference point (27) is below a first pressure threshold value, and to assume a closed state when the pressure at the common reference point (27) is at least as high as the first pressure threshold value. Pressure supply arrangement (21) according to Claim 1 , - wherein the pressure supply arrangement (21) has a second valve (DV2), - wherein the second valve (DV2) fluidly connects a point between the outlet of the first pump (ZP1) and the first valve (DV1) to an inlet of the first pump (ZP1). Pressure supply arrangement (21) according to Claim 2 , - wherein the second valve (DV2) is pressure-controlled and is designed to assume an open state when a pressure at a pressure tapping point between the outlet of the first pump (ZP1) and the first valve (DV2) is below a second pressure threshold, and to assume a closed state when the pressure at the pressure tapping point is at least as high as the second pressure threshold. Pressure supply arrangement (21) according to one of the Claims 2 or 3 , - wherein the first valve (DV1) is designed to open the second valve (DV2) when the first valve (DV1) closes. Pressure supply arrangement (21) according to Claim 4 , - wherein the first valve (DV1) is mechanically connected to the second valve (DV2) for closing the second valve (DV2). Pressure supply arrangement (21) according to Claim 3 or a claim dependent thereon, - wherein the first pressure threshold is greater than the second pressure threshold. Pressure supply arrangement (21) according to one of the preceding claims, - further comprising a brake fluid reservoir (30) to which the first pump (ZP1) and the second pump (ZP2) are connected on the inlet side. Pressure supply arrangement (21) according to one of the preceding claims, - further comprising a motor (25) which is designed to drive the first pump (ZP1) and the second pump (ZP2). Pressure supply arrangement (21) according to one of the preceding claims, - wherein the first pump (ZP1) is designed as a reversible rotary pump, and/or - wherein the second pump (ZP2) is designed as a reversible rotary pump. Braking system (10) of a motor vehicle, wherein the braking system (10) has a pressure supply arrangement (21) according to one of the preceding claims for providing a hydraulic pressure.