DE102017207954A1 - Brake system and method of operating such a brake system - Google Patents

Abstract

Braking system comprising at least four hydraulically actuable wheel brakes (9a-9d), each wheel brake being associated with a first wheel valve (1a-1d) and a second wheel valve (2a-2d), a pressure medium reservoir (6), a first electrically actuatable pressure supply device (4) which is connected for actuating the wheel brakes with each of the wheel brakes (9a-9d) via the respective first wheel valve (1a-1d), and a second electrically actuatable pressure supply device (5) which is connected to each of the wheel brakes for actuating the wheel brakes, wherein the second electrically operable pressure supplying means (5) is connected to each of the wheel brakes (9a-9d) via the respective second wheel valve (2a-2d), and wherein the first and second wheel valves (1a-1d, 2a-2d) are normally closed are executed, and methods for operating the brake system.

Description

The invention relates to a brake system according to the preamble of claim 1 and a method for operating such a brake system.

From the DE 10 2013 217 954 A1 a "brake-by-wire" -Bremsanlage for motor vehicles is known, which comprises four hydraulically actuated wheel brakes, a first electrically actuated pressure supply device and a second electrically actuated pressure supply device. Each wheel brake is assigned a normally open wheel valve (intake valve) and a normally closed wheel valve (exhaust valve). To actuate the four wheel brakes, both the first and second pressure supply means are hydraulically connected to each of the four wheel brakes via the respective inlet valve or connectable. The brake system furthermore comprises, per pressure supply device, a connection valve which is arranged between the pressure supply device and the inlet valves. The additional valves have the function of connecting the pressure supply devices with the wheel brakes if necessary and, in the event of an error, separating the lack of pressure supply device. It is further provided a Kreistrennventil which hydraulically separates two brake circuits in a disconnected position such that in the first brake circuit two of the four wheel brakes from the first pressure supply device via the two associated intake valves and in the second brake circuit, the other two wheel brakes from the second pressure supply device on the two associated intake valves are subjected to brake pressure.

It is an object of the present invention to provide a brake system with two electrically operable pressure supply devices and a method for operating the brake system, which is suitable for highly automated or autonomously driving motor vehicles and is inexpensive to produce.

This object is achieved by a braking system according to claim 1 and a method for operating a brake system according to claim 12.

The invention is based on the idea that the first electrically actuable pressure supply device is connected to each of the wheel brakes via the respective first wheel valve and the second electrically operable pressure supply device is connected to each of the wheel brakes via the respective second wheel valve, wherein the first and the second wheel valves de-energized are executed closed.

An advantage of the invention is that the function of the pressure delivery device on-off valves is integrated into the wheel valves. This means that it is possible to dispense with connecting valves for separating the pressure supply devices in the event of a fault. Thus, e.g. a brake system with only eight electrically actuated valves can be realized.

Preferably, the first and the second wheel valves are analogized or analog controlled executed to achieve an accurate pressure control at each wheel.

Preferably, in the hydraulic connection between the first electrically actuatable pressure-providing device and the first wheel valves, no electrically actuable valve, particularly preferably no valve, is arranged. As a result, costs are saved and unnecessary flow resistance between pressure supply device and wheel valves avoided.

With the same advantage, preferably no electrically operable valve, more preferably no valve, is arranged in the hydraulic connection between the second pressure supply device and the second wheel valves.

In order to increase the availability of the brake system, according to a development of the invention, a first electrical energy source and a second electrical energy source independent of the first electrical energy source are provided, wherein the first electrical energy source is the first pressure supply device and the first wheel valves and the second electrical energy source is the second pressure supply device and supplies the second wheel valves with electrical energy. Thus, even if one of the energy sources fails, a pressure build-up on all wheel brakes as well as by multiplexing a wheel-individual pressure control (for example anti-lock control) on all wheel brakes is possible.

In order to ensure pressure regulation, preferably the first pressure supply device is assigned a first pressure sensor, which is supplied with electrical energy by the first electrical energy source, and the second pressure supply device is assigned a second pressure sensor, which is supplied with electrical energy by the second electrical energy source.

The hydraulic components of the brake system, such as pressure-providing devices, valves and possibly pressure sensors are preferably arranged in a single electro-hydraulic unit.

Alternatively, it is preferred that the hydraulic components, which are assigned to the same electrical energy source, are arranged in a separate electro-hydraulic unit. The brake system then comprises at least two units. For reasons of cost reduction, the two units are particularly preferably constructed identically.

According to a preferred embodiment of the braking system according to the invention, at least one of the two pressure-supplying devices is designed as a piston pump or gear pump whose suction side is connected to the pressure medium reservoir and the pressure side with the wheel brakes. In order to obtain a symmetrical structure or identical aggregates, two pressure supply devices are particularly preferably designed as a respective piston pump or gear pump.

In order to allow pressure control by overflow, the piston pump or gear pump is a, advantageously normally closed, isolation valve connected in parallel hydraulically.

Preferably, the piston pump or gear pump, a check valve is hydraulically connected in parallel, which blocks in the direction of the pressure medium reservoir.

According to a further preferred embodiment of the brake system according to the invention at least one of the two pressure-supplying devices is designed as a cylinder-piston arrangement with a pressure chamber which is delimited by a piston which by means of an electric motor and a rotational-translation gear for a pressure build-up in the wheel brakes in a Actuating direction or for a pressure reduction in the wheel brakes in the direction opposite to the direction of actuation is shifted. In order to obtain a symmetrical structure or identical units, particularly preferably two pressure supply devices are each designed as such a cylinder-piston arrangement.

For discharging pressure medium into the pressure fluid reservoir, the pressure chamber of the pressure supply device is preferably connected via a, advantageously normally open, separating valve to the pressure medium reservoir. Particularly preferably, a check valve is hydraulically connected in parallel to the separating valve, which blocks in the direction of the pressure fluid reservoir to be able to draw pressure medium into the pressure chamber even when the separating valve is closed by moving the piston counter to the actuating direction.

It is preferred that a return element is provided in the pressure chamber, which positions the piston in an unactuated state at a stop against the actuation direction when the electric motor is de-energized.

Preferably, the pressure chamber is connected in the unactuated state of the piston via at least one Schnüffelloch with the pressure medium reservoir, wherein this connection is interrupted upon actuation of the piston.

Preferably, the rotation-translation gear is not designed to be self-locking.

Preferably, the first wheel valves are connected via a first, advantageously normally open, separating valve with the pressure medium reservoir. Particularly preferably, first check valve is hydraulically connected in parallel to the first isolation valve, which blocks in the direction of the pressure medium reservoir.

The second wheel valves are preferably connected via a second, preferably normally open, separating valve to the pressure medium reservoir. Particularly preferably, a second check valve is hydraulically connected in parallel to the second isolation valve.

The invention also relates to a method for operating a brake system. In this case, in a normal braking for actuating the wheel brakes the first and second pressure supply means are driven to build up a pressure, wherein the first pressure supply device is connected by opening two first wheel valves with two of the wheel brakes and the second pressure supply means by opening the corresponding second wheel valves with the other Wheel brakes is connected. Thus, a dynamic pressure build-up can be achieved on all wheel brakes.

A normal braking is understood to mean a braking initiated by a driver or an autopilot function in which all wheel brakes are subjected to the same brake pressure and no wheel-specific brake pressure regulation takes place.

In the case of a brake system with one or more isolation valves, the isolation valve or the isolation valves are preferably closed.

The opened first and second wheel valves preferably remain open at least until the end of normal braking.

Further preferred embodiments of the invention will become apparent from the dependent claims and the description below with reference to figures.

• 1 ein erstes beispielsgemäßes Bremssystem,
• 2 ein zweites beispielsgemäßes Bremssystem, und
• 3 ein drittes beispielsgemäßes Bremssystem.

They show schematically:

• 1 a first example brake system,
• 2 a second exemplary brake system, and
• 3 a third exemplary braking system.

This in 1 illustrated exemplary brake system comprises four hydraulically actuated wheel brakes 9a - 9d , a first electrically operable pressure supply device 4 , a second electrically operable pressure supply device 5 and a pressure medium reservoir under atmospheric pressure 6 , To operate the wheel brakes 9a - 9d is both the first electrically operable pressure delivery device 4 as well as the second electrically operable pressure delivery device 5 with each of the wheel brakes 9a - 9d connected hydraulically separable.

Each of the wheel brakes 9a - 9d is a first normally closed closed running wheel valve 1a - 1d and a second normally closed closed executed wheel valve 2a - 2d assigned, wherein the first electrically actuable pressure supply device 4 with the wheel brakes 9a - 9d over the first wheel valves 1a - 1d is connected and the second electrically actuated pressure supply device 5 over the second wheel valves 2a - 2d with the wheel brakes 9a - 9d connected is. The brake system contains no further (wheel) valves, which are the individual wheel brakes 9a - 9d assigned.

Per wheel brake 9a . 9b . 9c . 9d is an output port of the first wheel valve 1a . 1b . 1c . 1d and an output port of the second wheel valve 2a . 2 B . 2c . 2d connected to the wheel brake. The inlet connections of the first wheel valves 1a - 1d are over a connection line 8a with the first pressure supply device 4 or the pressure chamber directly connected hydraulically and the input terminals of the second wheel valves 2a - 2d are over a connection line 8b with the second pressure supply device 5 or their pressure chamber connected directly hydraulically. "Directly hydraulically connected" is to be understood here in the sense that no electrically actuated valve or no valve (eg check valve) in the connecting line 8a . 8b is arranged.

The first and second wheel valves 1a - 1d . 2a - 2d are advantageously carried out analogized or analog controlled, to an exact pressure setting on the wheel brakes 9a . 9b . 9c . 9d to enable.

According to the example, the brake system comprises an electronic control unit (not shown) for controlling the wheel valves 1a - 1d . 2a - 2d and the pressure delivery devices 4 . 5 ,

The first pressure delivery device 4 is a first pressure sensor 12a associated with that of the pressure supply device 4 provided pressure measures. Likewise, the second pressure providing device 5 a (second) pressure sensor 12b is associated with which of the pressure-providing device 5 provided pressure measures.

Normal braking is controlled via the pressure supply devices 4 . 5 and the pressure sensors 12a . 12b for brake pressure buildup and dismantling.

By way of example, both are pressure delivery devices 4 . 5 formed by a so-called linear actuator or linear pump. For this purpose, both have pressure supply facilities 4 . 5 each an electric motor 22 on, whose rotational movement by means of a schematically indicated rotation-translation gear 23 in a translatory movement of a piston 21 is implemented, which is for a pressure build-up at the pressure supply device in an actuating direction 24 in a hydraulic pressure chamber 20 is moved. For a pressure reduction at the pressure supply device of the piston 21 in the direction of actuation 24 shifted opposite direction.

Per pressure supply facilities 4 . 5 is the pressure room 20 or the connection line 8a . 8b via a suction line 11a . 11b with the pressure medium reservoir 6 connected. It is always in the intake 11a . 11b a parallel connection of a normally open isolation valve 3a . 3b and a check valve 7a . 7b arranged, with the check valve 7a . 7b a flow of pressure medium from the pressure medium reservoir 6 in the pressure room 20 allowed and locked in the opposite direction. About the check valve 7a . 7b can with closed isolation valve 3a . 3b Pressure medium from the pressure fluid reservoir 6 in the pressure room 20 be sucked. The respective isolation valve 3a . 3b can at a desired brake pressure reduction during an anti-skid control for discharging pressure medium from one or more wheel brakes in the pressure medium reservoir 6 be used. The isolation valves 3a . 3b are therefore advantageously carried out analogized or analog controlled.

Accordingly, the first wheel valves 1a - 1d over the first separating valve 3a and the second wheel valves 2a - 2d over the second isolation valve 3b with the pressure medium reservoir 6 separably connected.

According to another, not shown embodiment of the brake system, one of the two pressure-providing devices 4 . 5 or can both pressure delivery devices 4 . 5 be designed as a piston pump or as a gear pump. The suction side of the piston pump or gear pump is then (respectively) via a suction line with the pressure medium reservoir 6 and its pressure side is, according to the connection line 8a or 8b , with the corresponding wheel valves 1a - 1d or 2a - 2d connected. Advantageously, the piston pump or gear pump is a parallel circuit of one, eg normally open, isolation valve 3a . 3b and one in the direction of the pressure medium reservoir 6 locking check valve 7a . 7b hydraulically connected in parallel. The isolation valve 3a . 3b is advantageously carried out analogized or analog controlled, so the isolation valve can be used to control the pressure of the piston pump or gear pump by overflow.

The exemplary brake system of 1 As well as the above-described, not shown embodiment of a brake system advantageously comprises a total of only ten solenoid valves 1a - 1d . 2a - 2d . 3a . 3b ,

This in 2 illustrated second embodiment of a brake system according to the invention corresponds to the embodiment of the. with respect to the hydraulic structure 1 , whereby in addition two, independent electrical energy sources (eg Bordnetze) 13A . 13B are provided.

The one (first) electrical energy source 13A supplies the first pressure supply device 4 as well as the first wheel valves 1a - 1d (this is in 2 indicated by the letter A on the components), while the second pressure-providing devices 5 as well as the second wheel valves 2a - 2d from the other (second) source of electrical energy 13B be supplied (this is in 2 indicated by the letter B on the components).

Due to the fact that the parallel-connected wheel valves (ie the first wheel valves 1a - 1d or the second wheel valves 2a - 2d ) at the same energy supply ( 13A or 13B ) like the pressure delivery device ( 4 or 5 ) are connected, it is ensured that in case of failure of a power supply ( 13A or 13B ) the corresponding pressure supply device ( 4 or 5 ) by switching off and de-energized closing of the corresponding wheel valves ( 1a - 1d or 2a - 2d ) is hydraulically isolated from the remaining redundant brake system.

To a pressure control of the corresponding pressure supply device 4 . 5 to perform, is advantageously the first pressure sensor 12a from the first energy source 13A (indicated by A) and the second pressure sensor 12b from the second energy source 13B supplied by B).

In the case of a pressure delivery device 4 or 5 an electrically actuated isolation valve 3a or 3b is assigned, the separating valve is advantageously supplied or fed by the same power source as the associated pressure supply device. In the embodiment of 2 will therefore be the isolation valve 3a (indicated by A) from the first energy source 13A and the isolation valve 3b (indicated by B) from the second energy source 13B provided. The same applies if the pressure-providing device (s) is designed as a piston pump or gear pump / are.

The hydraulic components of the braking system are preferably arranged in a single electro-hydraulic control unit (i.e., in an electro-hydraulic unit).

Alternatively, it is preferred that the hydraulic components which the first electrical system 13A are assigned, in a first electro-hydraulic unit and the hydraulic components, which the second electrical system 13B are assigned, are arranged in a second electro-hydraulic unit, the units through pipes outside with the wheel brakes 9a - 9d are connected. Particularly preferably, the two aggregates are identical.

Method for operating the brake systems according to the invention 1 and 2 are described below.

In a normal braking both pressure supply facilities are for dynamic brake pressure build-up 4 . 5 used, wherein one of the pressure-providing facilities (eg Druckbereitstellungsseinrichtung 4 ) by opening two of the wheel valves connected to it (eg two of the first wheel valves 1a - 1d ) is connected to two of the wheel brakes, and wherein the other pressure providing means (eg pressure supply device 5 ) by means of two of its associated wheel valves (eg two of the second wheel valves 2a - 2d ) is connected to the other wheel brakes. The normally open isolation valves 3a . 3b will be closed.

For example, the one pressure supply device (eg 4) with the wheel brakes 9a and 9b the left front wheel FL and the right rear wheel RR are connected and the other pressure supply device (eg 5) is connected to the wheel brakes 9c and 9d the right front wheel RL and the left rear wheel RL connected (diagonal division).

The division can also be done by axle (a pressure supply device is connected to the wheel brakes of the front wheels FL, FR and the other pressure supply device with the wheel brakes of the rear wheels RL, RR). Then additional functions, such as axiswise blending, can be performed.

The pressure regulation takes place via the pressure supply devices 4 . 5 and the pressure sensors 12a . 12b for brake pressure buildup and brake pressure reduction. The wheel valves 1a - 1d and 2a - 2d remain open at least until the end of braking.

For an Aniblockierregelung (generally wheel-individual slip control) is advantageously proceeded as follows.

Device one wheel (or more wheels) in slippage (eg wheel brake 9a ), the corresponding, previously open wheel valve is closed (eg 1a) (phase 1 ).

To brake pressure reduction (phase 2 ), one of the two pressure supply devices is stopped and the associated isolation valve is opened. Now the other (the now depressurized circuit assigned) wheel valve by opening a pressure reduction via the separating valve in the reservoir 6 carry out.

The other pressure-providing device continues to serve as a pressure source and allows by pressure control and modulation of the four wheel valves associated therewith the wheel-individual pressure build-up (phase 3 ) for controlling the desired Radschlupfverlaufs. The modulation takes place individually and independently of one another, ie no multiplexing is carried out.

The function of the pressure source and pressure sink in the slip control can take over both pressure equalization facilities equivalent. In the event of failure of one of the two pressure delivery devices, unlimited pressure build-up dynamics provide unrestricted anti-lock control on all wheel brakes 9a - 9d possible (if the availability of all wheel valves is given).

In 3 a third exemplary braking system is shown. In contrast to the hydraulic structure of the brake systems 1 and 2 are the two pressure delivery devices 4 . 5 each designed as a linear actuator, the one in his pressure chamber 20 arranged return element 25 and sniffer holes for connection to the pressure medium reservoir 6 includes. So can the two isolation valves 3a . 3b as well as the suction valves 7a . 7b (as well as a suction line 11a . 11b between the connection line 8a . 8b and the pressure fluid reservoir 6 according to 1 . 2 ) accounted for.

The pressure room 20 is in an unactuated state of the piston 21 over the sniffer holes and a suction pipe 11a . 11b hydraulically with the pressure fluid reservoir 6 connected, wherein the connection at a sufficient actuation of the piston 21 is disconnected. The linear actuator thus has a connection to the reservoir 6 via at least one sniffer hole, the path-dependent on actuation of the piston 21 closes, so no isolation valve is needed with this feature.

By the return element 25 , eg a compression spring, becomes the piston 21 against friction against a stop (contrary to the direction of actuation 24 ) So reset that in the de-energized state of the linear actuator or the sniffer holes are opened (so-called. Unactuated state of the piston). To make this possible, the rotation-translation gear is not designed to be self-locking.

The exemplary brake system of 3 advantageously comprises a total of only eight solenoid valves, namely the wheel valves 1a - 1d . 2a - 2d ,

A method of operating the brake system of the invention 3 in a normal braking is described below.

For dynamic brake pressure build-up both pressure supply facilities 4 . 5 used, wherein one of the pressure-providing facilities (eg Druckbereitstellungsseinrichtung 4 ) by opening two of the wheel valves connected to it (eg two of the first wheel valves 1a - 1d ) is connected to two of the wheel brakes, and wherein the other pressure providing means (eg pressure supply device 5 ) by means of two of its associated wheel valves (eg two of the second wheel valves 2a - 2d ) is connected to the other wheel brakes.

For example, the one pressure providing device with the wheel brakes 9a and 9b the left front wheel FL and the right rear wheel RR connected and the other pressure-providing device is connected to the wheel brakes 9c and 9d the right front wheel RL and the left rear wheel RL connected. The division can also be done by axle.

Pressure regulation takes place via the pressure supply devices 4 . 5 and the pressure sensors 12a . 12b for brake pressure buildup and brake pressure reduction. The wheel valves 1a - 1d and 2a - 2d remain open at least until the end of braking.

The exemplary brake systems offer the following advantages:

No valves (e.g., electrically operable) are required to disconnect a pressure delivery device in the event of failure. This function is integrated in the wheel valves, so to speak.

The brake systems are symmetrical, they each consist of two identical redundant subsystems.

Only one valve type (normally closed) is required for all wheel valves.

There is a 4-channel redundancy of the Raddruckreglers in case of failure of a pressure supply device.

In case of failure of a vehicle electrical system is an anti-skid control in multiplex mode via the pressure supply device possible.

According to the second embodiment, two independent electrical energy sources (eg, electrical systems) 13A, 13B are advantageously also provided in this embodiment (not shown in FIG 3 ). The first electrical energy source 13A supplies the first pressure supply device 4 as well as the first wheel valves 1a - 1d (this is in 3 indicated by the letter A on the components), while the second pressure-providing devices 5 as well as the second wheel valves 2a - 2d from the other (second) source of electrical energy 13B be supplied (this is in 3 indicated by the letter B on the components). Furthermore, the first pressure sensor 12a from the first energy source 13A (indicated by A) and the second pressure sensor 12b from the second energy source 13B supplied by B).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013217954 A1 [0002]

Claims (13)

Braking system comprising • at least four hydraulically actuated wheel brakes (9a-9d), wherein each wheel brake a first wheel valve (1a-1d) and a second wheel valve (2a-2d) are assigned, • one, in particular under atmospheric pressure, pressure fluid reservoir (6), A first electrically actuatable pressure supply device (4) which is connected to each of the wheel brakes (9a-9d) via the respective first wheel valve (1a-1d) for actuation of the wheel brakes, and a second electrically actuatable pressure supply device (5) which is connected to Operation of the wheel brakes is connected to each of the wheel brakes, characterized in that the second electrically actuatable pressure supply means (5) with each of the wheel brakes (9a-9d) via the respective second wheel valve (2a-2d) is connected, wherein the first and the second Wheel valves (1a-1d, 2a-2d) are executed normally closed. Brake system after Claim 1 , characterized in that the first and the second wheel valves are analogized or analog controlled. Brake system after Claim 1 or 2 , characterized in that in the hydraulic connection (8a) between the first electrically actuable pressure supply device (4) and the first wheel valves (1a-1d) no electrically actuated valve, in particular no valve, is arranged. Brake system according to one of the preceding claims, characterized in that in the hydraulic connection (8b) between the second electrically actuated pressure supply device (5) and the second wheel valves (2a-2d) no electrically actuated valve, in particular no valve, is arranged. Braking system according to one of the preceding claims, characterized in that a first electrical energy source (13A) and a second electrical energy source (13B) independent of the first electrical energy source are provided, wherein the first electrical energy source is the first pressure supply device (4) and the first Wheel valves (1a-1d) and the second electric power source, the second pressure supply device (5) and the second wheel valves (2a-2) supplied with electrical energy. Brake system after Claim 5 , Characterized in that the first pressure generating device (4) is associated with a first pressure sensor (12a) extending from the first electrical power source (13A) is supplied with electrical energy, and that the second pressure generating device (5) associated with a second pressure sensor (12b) is which of the second electrical energy source (13B) is supplied with electrical energy. Brake system according to one of the preceding claims, characterized in that at least one of the two pressure- providing devices (4, 5) is designed as a cylinder-piston arrangement with a pressure chamber (20) which is bounded by a piston (21) by means of a Electric motor and a rotary-translation gear for a pressure build-up in the wheel brakes in an operating direction and for a pressure reduction in the wheel brakes in the direction opposite to the direction of actuation is displaceable. Brake system after Claim 7 , characterized in that the pressure chamber (20) via a, in particular normally open, separating valve (3a, 3b) with the pressure medium reservoir (6) is connected, in particular the separating valve, a check valve (7a, 7b) is connected in parallel hydraulically, which in Direction of the pressure medium reservoir locks. Brake system after Claim 7 , characterized in that in the pressure chamber (20), a return element (25) is provided, which in electroless electric motor (22) the piston (21) in an unactuated state, positioned against a stop against the actuating direction (24). Brake system after Claim 9 , characterized in that the rotation-translation gear (23) is not designed to be self-locking. Brake system after Claim 9 or 10 , characterized in that the pressure chamber (20) is connected in the unactuated state of the piston (21) via at least one Schnüffelloch with the pressure medium reservoir (6), said connection being interrupted upon actuation of the piston (21). Method for operating a brake system according to one of the preceding claims, characterized in that during normal braking for actuating the wheel brakes the first and second pressure supply means (4, 5) are driven to build up a pressure, wherein the first pressure supply means (4) by opening two first wheel valves (1a, 1b) are connected to two of the wheel brakes (9a, 9b) and the second pressure supply device (5) is connected to the other wheel brakes (9c, 9d) by opening the corresponding second wheel valves (2c, 2d). Method according to Claim 12 , characterized in that the opened first and second wheel valves remain open at least until the end of normal braking.

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