WO2023227173A1

WO2023227173A1 - Brake system for motor vehicles with a pressure supply device

Info

Publication number: WO2023227173A1
Application number: PCT/DE2023/200095
Authority: WO
Inventors: Stefan Gottschalk
Original assignee: Continental Automotive Technologies GmbH
Priority date: 2022-05-24
Filing date: 2023-05-12
Publication date: 2023-11-30
Also published as: DE102022205185A1

Abstract

The invention relates to a brake system (2) for motor vehicles, comprising: an electrically controllable pressure supply device (6); a pressure modulator (10) to which hydraulic wheel brakes (88, 92, 124, 128) are connected; and a reservoir (80) for brake fluid, wherein the electrically controllable pressure supply device (6) has a open- and closed-loop control unit (60) which, on the signal input side, is connected to a brake request apparatus (20), wherein in an idle state, the electrically controllable pressure supply device (6) is connected to the reservoir (80) via at least one compensation opening (164, 168).

Description

Brake system for motor vehicles with a pressure supply device

The invention relates to a brake system for motor vehicles, comprising an electrically controllable pressure supply device and a pressure modulator to which hydraulic wheel brakes are connected, as well as a reservoir for brake fluid.

Vehicles are continually being further developed in their electrification, with the trend leading to braking systems that generate brake pressure independently of vacuum. Examples of vacuum-independent brake systems are brake systems with a brake pedal-operated master brake cylinder and an electrically controllable pressure supply device. An electric motor moves a hydraulic piston of the pressure supply device in order to provide the desired pressure. In the normal operating mode (by-wire operating mode), at least during braking, the brake pedal is decoupled from the two brake circuits and connected to a simulator, which realizes the pedal feel. However, these systems still have a mechanical/hydraulic connection from the brake pedal to the hydraulic wheel brakes or a hydraulic fallback level in which the driver can generate braking force on the wheels using muscle power and with the help of the hydraulic transmission of the brake system.

In partially or fully autonomous vehicles, the driver is not always actively involved in the driving situation. This means that a second electrically controllable pressure actuator is required in order to still be able to brake if the main pressure actuator fails.

By-wire braking systems are also becoming increasingly relevant due to the development of modular vehicle systems or skateboard chassis. The need for more flexibility and freedom in the arrangement of the brake system components is becoming apparent. The component that generates the brake pressure is referred to below as the pressure provision device or pressure provider. The brake pressure generated is the same for all wheels and is therefore referred to as central pressure. If the pressure on individual wheels needs to be limited, e.g. B. because a wheel needs to be slip-controlled, this task is taken over by the pressure modulator of the brake system.

From DE 102010 024 739 A1 a vehicle brake system with an electrically operated brake force generator, which is arranged between a brake pedal and a tandem master brake cylinder, and a pneumatic pedal simulator, which is coupled to the brake pedal, is known. The tandem master brake cylinder is actuated by the driver in a mechanical fallback via the brake pedal. The pneumatic pedal simulator includes a housing with a compression chamber and a device for reducing the volume of the compression chamber.

The DE 10 2019 213 886 A1 describes a brake system for motor vehicles with an ESC module and an electric brake booster, the electric brake booster being preceded by a pedal simulator unit comprising a brake pedal with a mechanical gap, so that after the mechanical gap has been overcome, the brake booster is mechanically actuated takes place using the brake pedal.

The disadvantage of the systems described above with a mechanical/hydraulic connection from the brake pedal to the hydraulic wheel brakes and a hydraulic fallback level is that they have narrow limits with regard to their installation in the vehicle. The mechanical components must be designed and positioned so that the driver can operate them from the driver's seat. This actuation can be ensured purely mechanically using a linkage or by hydraulic transmission using a Wegbau pedal actuation unit (remote PAU). However Flexibility is also limited in this case. When using an electric brake pedal, this mechanical connection is eliminated.

Purely electric braking systems are known, in which the driver's braking request is transmitted purely electrically. However, an electric brake pedal for detecting driver requests without a hydraulic connection to the braking system requires redundancy in the generation of braking force, ideally with a very high level of reliability.

If hydraulic brake calipers are used in the brake system, which are still completely or only partially based on hydraulic energy transmission, a new type of brake force actuator is required, which is intended to shift the volume of brake fluid and thereby generate pressure in the brake system.

The invention is based on the object of specifying a braking system with hydraulic wheel brakes with high availability in the event of a fault and a high level of reliability, in which the braking request can be generated or detected electrically.

This object is achieved according to the invention by a brake system according to claim 1.

The pressure provision device has a control and regulation unit, which is connected to a braking request device on the signal input side, the pressure provision device being connected to the reservoir via at least one compensation opening in the idle state.

Advantageous embodiments of the invention are the subject of the subclaims.

The invention is based on the idea that it would be advantageous if brake pressure generation that is decoupled from the driver can be provided by means of a brake force actuator (pressure supply device), which functions as a main pressure actuator and as a volume actuator. This system should be in Work in combination with an electric brake pedal that detects the driver's request, or in an autonomous vehicle that calculates its braking needs. The brake force actuator (pressure supply device) should work in conjunction with the ESC system or pressure modulator, which can be used as a redundant pressure actuator and is also used for wheel control functions.

Additional requirements for such a system should be high availability in the event of an error and high reliability. Problems with residual pressures, which occur, for example, when applying the integrated parking brake (IPB) or when components expand, should be avoided. The system should have redundancy for the pressure position and optional redundancy for the integrated parking brake. The system should have few components and therefore be cost-effective to produce. If there is wear, it should be possible to supply the brake system with brake fluid. Finally, the emerging need for a braking system should be met with an exclusively electric brake pedal. Problems with residual pressures, which occur, for example, when applying the integrated parking brake (IPB) or when components expand, should be avoided.

As has now been recognized, these requirements can be met by the brake force actuator (the electrically controllable pressure supply device) working in conjunction with the ESC system or pressure modulator, which can be used as a redundant pressure actuator and is also used for wheel control functions.

The electrically controllable pressure supply device is connected to the reservoir in a resting state via at least one compensation opening.

The idle state of the print provision device is preferably an inactive state of the print provision device. Preferably, the electrically controllable pressure supply device cannot be actuated either mechanically or hydraulically by a driver using a brake pedal.

The braking system preferably does not include a driver-operated mechanical and/or hydraulic fallback level.

In an advantageous embodiment, the braking request device is designed as an electric brake pedal or as an autonomous driver (in particular a control device or sensor which receives electrical information from the pressure actuator via CAN). The electric brake pedal preferably includes a redundant pedal sensor for detecting the pedal position or the pedal travel/pedal angle.

The pressure modulator is preferably electrically controllable and has at least one electrically actuated inlet valve for each of the hydraulic wheel brakes.

The electrically controllable pressure supply device, the pressure modulator and the braking request device are preferably designed as three separate modules or structural units. A hydraulic connection is particularly preferably only present between the electrically controllable pressure supply device and the pressure modulator.

The pressure supply device and the pressure modulator are preferably connected to one another via two hydraulic, pressure-tight connecting lines.

Further hydraulic connecting lines between the pressure supply device and the pressure modulator are not provided. A hydraulic connecting line between the pressure supply device and the braking request device and between the pressure modulator and the braking request device are not provided.

The pressure modulator advantageously has a separate control and regulation unit, which is connected to the braking request device on the signal input side connected is. If the signal connection between the braking request device and the control and regulation unit is disturbed, the braking request is still available in the other control and regulation unit, so that redundancy is created in the control and regulation. In an alternative advantageous embodiment, only one control and regulation unit is provided, which has two separate circuit boards, with the control and regulation routines for the print provision device on the first circuit board and the control and regulation routines for the pressure actuator on the second circuit board being software and/or or implemented in hardware.

The pressure modulator advantageously has at least one electrically controllable pressure actuator. In this way, the pressure modulator can still build up brake pressure if the pressure supply device fails or malfunctions.

The respective pressure actuator is preferably designed as a pump. If two different pumps are used, for example a plunger pump and a two-piston pump, their respective disadvantages can be compensated for. Costs can be saved by using a two-piston pump.

In a preferred embodiment, the two control and regulation units are configured in such a way that if one of the two control and regulation units fails or malfunctions, the other control and regulation unit takes over the control and regulation tasks of the failed or faulty control and regulation unit.

The pressure supply device advantageously comprises a cylinder-piston arrangement with a primary chamber and a secondary chamber and an electric motor that can be controlled by the open-loop and closed-loop control unit, as well as a primary piston that can be displaced into the primary chamber by a rotation-translation gear. The primary chamber and secondary chamber are advantageously separated from each other by a secondary piston (floating piston). Both the primary chamber and the are particularly preferred Secondary chamber in the resting state, ie in an unactuated state of the cylinder-piston arrangement with the (primary) piston retracted, hydraulically connected or connectable to the reservoir through compensating openings and corresponding compensating lines. Particularly preferably, a spring element is arranged in the primary chamber and in the secondary chamber, which brings or holds the primary piston and floating piston into an unactuated state (eg to a rear stop) when the electric motor is not actuated.

Two brake circuits are preferably formed in the pressure modulator, each brake circuit being hydraulically connected to two wheel brakes, and each wheel brake being assigned an inlet valve and an outlet valve.

The primary chamber is preferably connected to one brake circuit of the pressure modulator via a single, first hydraulic connecting line and the secondary chamber is preferably connected to the other brake circuit of the pressure modulator via a single, second hydraulic connecting line.

Advantageously, at least two wheel brakes are equipped with an integrated parking brake. In this way, a third electric brake actuation unit is provided, which can be used to brake or safely park the vehicle. If these are distributed redundantly to the control devices, pressure actuators and modulator, then parking can also be done redundantly.

The brake system preferably has a pressure sensor in the pressure modulator, which is connected to at least one control and regulation unit on the signal input side.

The advantages of the invention are, in particular, that pressure actuators (electrically controllable pressure provision device) and pressure modulator (components of ESC systems) can be used with an electric brake pedal. Signal redundancy from the wheel speed sensors means that in addition to the normal wheel-specific ABS control using a pressure modulator in the event of a fault An emergency ABS can also be implemented with central pressure via the pressure actuator. The system has redundancy for the pressure position and optional redundancy for the integrated parking brake. The braking system has few components and can be produced inexpensively. If there is wear, it is still possible to supply the brake system with brake fluid. The IPB function can be distributed between the pressure actuator and pressure modulator ECUs to ensure redundancy for the integrated parking brake.

An exemplary embodiment of the invention is explained in more detail with reference to a drawing. It shows in a highly schematic representation:

FIG. 1 a brake system in a first schematic representation, and

FIG. 2 a brake system in a second schematic representation.

The same parts are given the same reference numbers in both figures.

A in FIG. 1 brake system 2 shown includes an electrically controllable pressure supply device 6, a (e.g. electrically controllable) pressure modulator 10, hydraulic wheel brakes 14 and a braking request device 20. The braking request device 20 can, as in the present case, be used as a pedal unit with an electric brake pedal 24 with a redundant pedal sensor or alternatively as an autonomous driver (level 5) be trained.

The pressure provision device 6 or the pressure provider works in conjunction with an electric brake pedal 24, which determines the driver's braking request or driver actuation and transmits it to the pressure provision device 6, which is shown by an arrow 28. Likewise, the driver's braking request is redundantly forwarded to the pressure modulator 10, which is shown by an arrow 30. The pressure supply device 6 generates the desired pressure in the brake system 2. If necessary, the pressure modulator 10 regulates the wheel brake pressure in the wheel brakes 14, in particular based on a control function such as the wheel slip controller. The brake system 2 further comprises wheel speed sensors, which are connected on the signal input side to a control and regulation unit 60 of the pressure supply device 6 (arrow 34) and the control and regulation unit 64 of the pressure modulator 10 (arrow 38), see FIG. 2.

In FIG. 2, the brake system 2 is shown in a further schematic representation. The electrically controllable pressure supply device 6 is designed as a (dual-circuit) linear actuator with a cylinder-piston arrangement 40 with a primary piston 44, which can be moved back and forth into a hydraulic primary chamber 48, and a floating secondary piston 52, which can be moved into a secondary chamber 54 is. The pressure supply device 6 comprises an electric motor 68 and a motor position sensor 72, in particular of redundant design. With the aid of a rotation-translation gear 76, which is designed, for example, as a ball screw drive, the rotation of the rotor of the electric motor 68 is converted into a translation of the primary piston 44. The two chambers 48, 54 are connected via compensation openings 164, 168 (“sniffer holes”) and compensation lines 170, 174 in the idle state (unactuated state) of the pressure supply device 6 with a reservoir 80 for brake fluid.

By using the cylinder-piston arrangement 40 with sniffer holes, the connection to the atmosphere and thus the reduction of residual pressure in the system is ensured. It is also ensured that brake fluid can flow from the brake fluid container or reservoir 80 into the system in the event of wear. There is a dual circuit system, which is always ensured, even if the supply energy fails.

The primary chamber 48 of the cylinder-piston arrangement 40 is hydraulically connected to a first brake circuit 84 formed in the pressure modulator 10, to which two wheel brakes 88, 92 are connected. Each wheel brake 88, 92 is an electrically operable inlet valve 100, 104 and an electrically operable Associated with exhaust valve 104, 108. Furthermore, a pump 112 and a low-pressure accumulator 116 are arranged in the first brake circuit 84.

The secondary chamber 54 of the cylinder-piston arrangement 40 is hydraulically connected to a second brake circuit 120 formed in the pressure modulator 10, to which two wheel brakes 124, 128 are connected. Each wheel brake 124, 128 is assigned an inlet valve 132, 134 and an outlet valve 140, 144.

Furthermore, a pump 148 and a low-pressure accumulator 152 are arranged in the first brake circuit 84.

For errors with a high FIT rate, the operation of the pressure provision device 6 must be possible independently of the pressure modulator 10. The control and regulation functions are therefore based on the two different control devices or

Control and regulation units 60, 64 or alternatively at least distributed on two different ECU boards. In the event of an electrical failure of a control and regulation unit 60, 64 or circuit board, the remaining part can continue to enable braking force to be generated.

In the event of both electrical and mechanical errors in the pressure supply device 6, all four wheels are decelerated by the pressure modulator 10. The pressure buildup is generated by the respective pump 112, 148 in the pressure modulator 10. The required brake fluid volume is obtained from the pressure supply device 6.

In the event of a leak, the dual circuit nature of the brake system 2 ensures that at least 50% of the brake pressure of the hydraulic system can still be built up. This proportion can be increased additionally by isolating the leak or by using an integrated parking brake as a brake force actuator. A leak is detected with the help of a brake fluid sensor 156 or also detected by an increased volume absorption during pressure generation. To ensure pressure generation, a pressure sensor 160 is used in the pressure modulator 10. The pressure provision device has no valves. It only has two sensors, namely the motor position sensor 72 or position sensor of the drive and the brake fluid level sensor 156. This enables simple functionality with few requirements from the operating software. Through the described combination of the pressure supply device 6 and the pressure modulator 10, both a diagonal division and a front-rear division of the brake system 2 can be represented. The braking system can therefore be easily adapted to the vehicle.

Reference symbol list

2 braking system

6 print provision device

10 pressure modulator

14 wheel brakes

20 brake request device

24 brake pedal

28 arrow

30 arrow

34 arrow

38 arrow

40 cylinder-piston arrangement

44 primary pistons

48 primary chamber

52 secondary pistons

54 secondary chamber

60 control and regulation unit

64 control and regulation unit

68 electric motor

72 Motor position sensor

76 rotary translation gears

80 Reservoir

84. first brake circuit

88 wheel brake

92 wheel brake

96 inlet valve

100 inlet valve

104 exhaust valve

108 exhaust valve

112 pump

116 low pressure accumulators

RECTIFIED SHEET (RULE 91) ISA/EP 120 second brake circuit

124 wheel brake

128 wheel brake

132 inlet valve 134 inlet valve

140 exhaust valve

144 exhaust valve

148 pump

152 low pressure accumulator 156 brake fluid sensor

160 pressure sensor

164 compensation opening

168 compensation opening

170 compensation line 174 compensation line

Claims

Patent claims

1. Brake system (2) for motor vehicles, comprising an electrically controllable pressure supply device (6) and a pressure modulator (10), to which hydraulic wheel brakes (88, 92, 124, 128) are connected, and a reservoir (80) for brake fluid, wherein the electrically controllable pressure provision device (6) has a control and regulating unit (60), which is connected on the signal input side to a braking request device (20), the electrically controllable pressure provision device (6) being in a rest state with the at least one compensation opening (164, 168). Reservoir (80) is connected.

2. Brake system (2) according to claim 1, wherein the brake request device (20) is designed as an electric brake pedal (24) or as an autonomous driver.

3. Brake system (2) according to claim 1 or 2, wherein the pressure modulator (10) has a control and regulation unit (64) which is connected to the braking request device (20) on the signal input side.

4. Brake system (2) according to claim 3, wherein the pressure modulator (10) comprises at least one pressure actuator.

5. Brake system (2) according to claim 4, wherein the respective pressure actuator is designed as a pump (112, 148).

6. Brake system (2) according to one of claims 3 to 5, wherein the two control and regulating units (60, 64) are configured such that in the event of failure or malfunction of one of the two control and regulating units (60, 64) the other Control and regulation unit (60, 64) takes over the control and regulation tasks of the failed or faulty control and regulation unit (60, 64).

7. Brake system (2) according to one of the preceding claims, wherein the electrically controllable pressure supply device (6) is a cylinder-piston arrangement (40) with a primary chamber (48) and a secondary chamber (54) and an electric motor that can be controlled by the open-loop and closed-loop control unit (60) and a primary piston (44) that can be displaced into the primary chamber (48) by a rotation-translation gear (76). .

8. Brake system (2) according to one of the preceding claims, wherein the electrically controllable pressure supply device (6) cannot be actuated by a driver either mechanically or hydraulically by means of a brake pedal.

9. Brake system (2) according to one of the preceding claims, wherein this does not include a driver-operated mechanical and / or hydraulic fallback level.

10. Brake system (2) according to one of the preceding claims, wherein two brake circuits (84, 120) are formed in the pressure modulator (10), each brake circuit (84, 120) being hydraulically connected to two wheel brakes (88, 92; 124, 128). is, and wherein each wheel brake (88, 92; 124, 128) is assigned an inlet valve (132, 134) and an outlet valve (140, 144).

11. Braking system (2) according to one of the preceding claims, wherein at least two wheel brakes (88, 92; 124, 128) are equipped with an integrated parking brake.

12. Brake system (2) according to one of the preceding claims, with a pressure sensor (160) in the pressure modulator (10), which is connected on the signal input side to at least one control and regulation unit (60, 54).

13. Brake system (2) according to one of the preceding claims, wherein the electrically controllable pressure supply device (6), the pressure modulator (10) and the braking request device (20) are designed as three separate modules or structural units, in particular a hydraulic connection only between the electrically controllable pressure provision device (6) and the pressure modulator (10).