CN112384420A

CN112384420A - Brake system

Info

Publication number: CN112384420A
Application number: CN201980047004.6A
Authority: CN
Inventors: B·维特
Original assignee: Volkswagen Automotive Co ltd
Current assignee: Volkswagen Automotive Co ltd
Priority date: 2018-07-13
Filing date: 2019-06-20
Publication date: 2021-02-19
Anticipated expiration: 2039-06-20
Also published as: WO2020011506A1; DE102018211706B3; CN112384420B

Abstract

The invention relates to a brake system (100) for a vehicle that is driven without a driver and without a brake pedal, comprising: a brake pressure generating and distributing system (10) is used for generating and distributing a braking force to wheel brakes (101) of a vehicle by means of a brake fluid and a brake fluid balancing reservoir (20). In this respect, according to the invention, the brake fluid balancing container (20) is directly fluidically connected to the brake pressure generating and distributing system (10).

Description

Brake system

Technical Field

The present invention relates to a brake system for a vehicle which is driven without a driver and without a brake pedal according to the preamble of independent claim 1 and to a corresponding vehicle according to independent claim 10.

Background

In vehicles, a distinction is made between the following different degrees of automation:

0: conventional vehicles without a driver assistance system,

1: vehicles with driver assistance systems in the longitudinal or transverse direction of the vehicle, for example with Adaptive Cruise Control (ACC) for longitudinal guidance of the vehicle, in which the driver additionally has to steer the vehicle,

2: vehicles with driver assistance systems in the longitudinal and transverse directions of the vehicle, for example with an autopilot, in which the driver only has to monitor the system and intervenes only in the event of a fault by actuating the brake pedal or the steering wheel,

3: highly automated vehicles, in which the driver has to take over the guidance of the vehicle again within 10 seconds in the event of a fault,

4: fully automated driving vehicles, in which the driver is allowed to sleep, wherein, however, the vehicle still has a steering wheel and pedals for manual driving,

5: a vehicle which is driven without a driver, wherein the vehicle is driven without a driver and furthermore has no pedal or steering handle.

An automatically driven vehicle has a brake system with at least one electromechanical brake booster (Bremsskraftertier) and a slip control system (Schlupfreegelsystem) as a redundancy with respect to one another. The energy and data onboard networks are present here doubly.

Disclosure of Invention

The object of the present invention is therefore to provide an improved brake system for a vehicle which is driven automatically, in particular without a driver, preferably without a brake pedal. In particular, the object of the invention is to provide a cost-effective, weight-saving, energy-improving, safe, reliable and sensitive brake system for a vehicle, in particular for a vehicle which is driven without a driver, preferably without a brake pedal.

The object according to the invention is achieved by a brake system with the features of independent claim 1, in particular with the features of the same, and by a corresponding vehicle with the features of independent claim 10. Preferred developments of the invention are listed in the dependent claims. The features disclosed for the individual inventive aspects can be combined with one another in such a way that the disclosure with regard to the inventive aspects of the invention is always or can be made with reference to one another.

The invention provides a brake system for a vehicle which is driven without a driver and without a brake pedal, comprising: a brake pressure generating and distributing system, which is preferably electronically controllable, is used to generate and distribute brake pressure to the wheel brakes of the vehicle by means of a brake fluid, in particular via hydraulic lines; and a brake fluid balancing reservoir. In this respect, according to the invention, it is provided that the brake fluid compensation reservoir is directly fluidically coupled to the brake pressure generating and distributing system.

In the sense of the present invention, this means permanently, that is to say that no structural, structural parts (e.g. brake cylinders, etc.) are located between them. Directly in a fluid manner means in the sense of the present invention only via a direct, uninterrupted and open or valveless hydraulic line or preferably even directly without a hydraulic line. In the sense of the invention, the presence of a brake pedal is no longer necessary for vehicles which are driven by no driver. The braking system may be referred to herein as a force braking system (fremdkraftbremsystem). In the sense of the invention, the brake system meets the high requirements in terms of availability according to the classification in ASIL C or D.

The present invention recognizes that certain driving assistance systems are redundantly used in most autonomous vehicles. As an example, an electronic brake booster and a slip control system may be considered here, which however provide brake pressure to the wheel brakes during braking or starting in different driving situations and, if necessary, enable driver interaction or generate a brake pedal feel (bremspledgefuehl).

Furthermore, the invention recognizes that in a vehicle which is driven by no driver, any type of brake booster, master brake cylinder or pedal simulator can be dispensed with by eliminating the brake pedal.

The inventive concept here consists in hydraulically coupling the brake fluid balancing reservoir directly to the input of the brake pressure generating and distributing system. A simple, cost-effective, weight-reduced, energy-improved, safe, reliable and sensitive braking system can thus be provided by means of the invention. In addition to the brake booster, the master brake cylinder or the pedal simulator, within the framework of the invention, a pre-pressure sensor can be dispensed with, which in conventional brake systems measures the brake pressure built up by the master brake cylinder at the input of the brake pressure generating and distributing system. This value is required as an initial value of a differential equation for pressure regulation in each wheel. If, without the brake pedal, there is no longer any possibility of actuation by the driver, but instead the brake fluid balancing reservoir is coupled directly to the input of the brake pressure generating and distributing system, the pre-pressure is always 1 bar ambient pressure. Therefore, the pre-pressure sensor can now be dispensed with, which leads to additional reductions in costs, weight, energy and control effort.

Furthermore, the invention can provide that the brake pressure generating and distributing system has at least one return pump (rueckfoerdepumpe), wherein the return pump is directly fluidically coupled from the suction side to the brake fluid balancing container. Directly in a fluid manner here also means that no structurally important components (e.g. a separation valve (Trennventil) etc.) are mounted between them. In the sense of the invention, the coupling takes place only via a direct, uninterrupted and open or valve-free hydraulic line. A conventional brake pressure generating and distributing system has an inlet valve and an outlet valve for each wheel and two so-called separation valves for each hydraulic circuit. These separating valves are necessary in order that, when pressure builds up in the brake pressure generating and distributing system, the return pump pumps pressure fluid directly into the brake fluid balancing reservoir, not via the master brake cylinder, so that no hydraulic pressure builds up in the wheel brakes and in order that the return pump can suck brake fluid from the brake fluid balancing reservoir. In conventional brake pressure generating and distributing systems, the connection of the brake fluid balancing reservoir to the return pump is moved from the pressure side to the suction side by means of a separating valve in the event of an active pressure buildup by the return pump. If the brake fluid compensation reservoir is permanently connected to the suction side of the return pump, it is advantageously possible within the framework of the invention to dispense with two separating valves (i.e. four in total) for each hydraulic circuit.

In addition, the invention can provide that the return pump is fluidically connected only or exclusively from the suction side to the brake fluid balancing reservoir. Thereby creating significant advantages for coupling in brake pressure generating and distributing systems. Fewer lines and fewer valves are required. And thereby also the energy supply and the amount of calculation (rechakapazitaet) when operating the brake pressure generating and distributing system. If the brake fluid balancing reservoir is permanently connected to the suction side of the return pump, a low-pressure reservoir between the outlet valve of the wheel and the suction side of the return pump can be dispensed with, since excess pressure fluid can be directly displaced into the brake fluid balancing reservoir.

Furthermore, the invention can provide that the brake pressure generating and distributing system has a first hydraulic circuit, preferably for the front left and rear right wheel brakes or for both front wheel brakes, and a second hydraulic circuit, preferably for the front right and rear left wheel brakes or for both rear wheel brakes. Each hydraulic circuit can hydraulically operate both wheel brakes. Thus, the brake system can meet high availability requirements.

Furthermore, the invention can provide that the first and second hydraulic circuits have an inlet valve and an outlet valve for each wheel brake, wherein the first and second hydraulic circuits have in particular no return valve (rueckstmentl) for the wheel brakes. In conventional brake pressure generating and distributing systems, a return valve is present parallel to each inlet valve, which is operated by a pressure difference. If the driver wants to reduce the brake pressure during the pressure holding phase, the wheel pressure should be able to immediately follow the reduction. The return valve is therefore always open if the brake pressure in the wheel is greater than the pressure prevailing before the inlet valve. This is to avoid self-braking (Selbstbremsern). Since there is no longer any interaction by the driver, these four return valves can be dispensed with. In addition to the return valve, a low-pressure accumulator and a shut-off valve (Sperrventil) can advantageously be dispensed with. This makes it possible to achieve a simple construction of the hydraulic circuit.

Furthermore, the invention can provide that the first and second hydraulic circuits have a respective return pump, which can be driven in each hydraulic circuit by a respective motor. The return pump is responsible for the throughflow of brake fluid. The two hydraulic circuits can be completely separated from each other by means of two separate motors.

According to a further advantage of the invention, the brake pressure generating and distributing system can have an electric parking brake for each rear wheel brake or each front wheel brake of the vehicle, respectively. An all-electric brake system may be provided by an electric parking brake. The control of the electric parking brake can be carried out in the framework of the invention in the control of the brake system.

Furthermore, the invention can provide that the electric parking brake can be actuated at each wheel brake by a motor-transmission unit close to the wheel. A separately actuatable parking brake can be provided in each case by means of a motor-gear unit which is located close to the wheel at each wheel brake.

Furthermore, it is conceivable within the framework of the invention for at least one hydraulic circuit to be associated with at least one electric parking brake which brakes a wheel which is not hydraulically braked by the associated hydraulic circuit. In other words, the parking brake may preferably be fitted at a wheel that is not associated with the hydraulic circuit. For each hydraulic circuit (in which in particular two diagonal hydraulic circuits can be provided), for example, two wheels (for example, the front left VL and the rear right HR) can be hydraulically braked and the other wheel (for example, the front right VR or the rear left HL) can be braked via the parking brake. A reliable all-electric brake system can thus be provided.

In addition, the invention can provide that a control device is provided for operating the brake pressure generating and distributing system, wherein the control device has a control unit in particular for each hydraulic circuit. Thus, a fault tolerant reliability (ausfallisiheheit) of the control unit can be achieved. A central, upper-level control device can furthermore be advantageous in order to coordinate the hydraulic circuits with one another.

Furthermore, within the framework of the invention, it can be advantageous if the control device provides the vehicle with at least one electronically controllable safety or driving assistance system, such as an anti-lock system and/or a drive slip control (antitrichlupfregueling) and/or an electronic stability program, by means of the brake pressure generating and distributing system, preferably in addition to the electronic brake force distribution. In other words, the brake system according to the invention makes it possible to implement a total safety and driving assistance system for determining the braking force by means of the brake pressure generating and distributing system according to the invention.

In addition, the invention can provide that the brake system has only one brake fluid balancing reservoir, but in particular no low-pressure reservoir. The construction of the brake system can thus also be simplified, wherein at the same time the controllability of the brake system can be improved.

The object is also achieved according to the invention by a vehicle which is driven without a driver and without a brake pedal and which has a brake system which can be implemented as described above. The same advantages as described above in connection with the brake system according to the invention are obtained here. Reference is now made in full to these advantages.

Drawings

Further measures which improve the invention are shown in detail below with the description of preferred embodiments of the invention in accordance with the drawings. The features mentioned in the claims and in the description may be essential for the invention in each case individually or in any combination. It should be noted herein that the drawings are merely illustrative features and are not intended to limit the invention in any way. Wherein:

figure 1 shows a schematic view of a conventional brake system,

fig. 2 shows a schematic view of a brake system according to the invention.

Detailed Description

Fig. 1 shows a known brake system 100, which is provided with redundancy. Also shown in fig. 2 is a braking system 100 according to the present invention. The brake system 100 according to the invention is advantageously designed for a vehicle which is driven without a driver and without a brake pedal 4. The brake system 100 comprises a brake pressure generating and distributing system 10 for generating and distributing brake pressure by means of brake fluid onto wheel brakes 101 of a vehicle and a brake fluid balancing container 20. The invention provides for this purpose that the brake fluid balancing container 20 is fluidically connected directly, i.e. without structural components between it, only via the open, valveless hydraulic line 3, or preferably directly without the hydraulic line 3, to the brake pressure generating and distributing system 10.

The invention is illustrated by comparing fig. 1 and 2. By eliminating the brake pedal 4 in the vehicle, any type of brake booster 1, master brake cylinder 2 or pedal simulator 4 can be dispensed with.

As shown in fig. 1, conventional brake pressure generating and distributing system 10 has a pre-pressure sensor 5, which measures the brake pressure built up by master brake cylinder 2 before brake pressure generating and distributing system 10. This value is required as an initial value of a differential equation for pressure regulation in each wheel. If now there is no longer any possibility of actuation by the driver, but instead the brake fluid balancing container 20 is coupled directly to the input of the brake pressure generating and distributing system 10, the pre-pressure is always 1 bar ambient pressure. Within the framework of the invention, therefore, the pre-pressure sensor can now be dispensed with, as can be seen in fig. 2.

As is also shown in fig. 1, a conventional brake pressure generating and distributing system 10 has an inlet valve 6 and an outlet valve 7 per wheel and two so-called separating valves 8,9 per hydraulic circuit I, II. These separating valves 8,9 are necessary in order that, when the brake pressure is built up in the brake pressure generating and distributing system 10, the return pump 11 does not pump pressure fluid or pressure fluid directly into the brake fluid balancing reservoir 20 via the master brake cylinder 2, so that no hydraulic pressure is built up in the wheel brakes 101 and in order that the return pump 11 can suck brake fluid from the brake fluid balancing reservoir 20. The function of the separating valves 8,9 is to move the connection of the brake fluid compensation reservoir 20 to the return pump 11 from the pump side P to the suction side S, i.e. in the event of an active pressure build-up by the return pump 11. Within the framework of the invention, two separating valves 8,9 per hydraulic circuit I, II (i.e. a total of four separating valves 8,9) can be dispensed with (see fig. 2). The constructional point is that the brake fluid balancing reservoir 20 can be permanently connected to the suction side of the return pump 11.

That is, if the brake fluid balancing reservoir 20 is permanently connected to the suction side of the return pump 11 (as shown in fig. 2), the low-pressure accumulator 12 between the outlet valve 7 of the respective wheel brake 101 and the suction side S of the return pump 11 can also be dispensed with. Excess pressure fluid may be sprayed directly into the brake fluid balancing container 20. A wheel sensor (Drehradsensor)102 may be provided at each wheel brake 101.

As can be seen from fig. 1, in the conventional brake pressure generating and distributing system 10, a return valve 13 which can be actuated by a pressure difference is present parallel to each inlet valve 6. If the driver wants to reduce the brake pressure during the pressure holding phase, the wheel pressure should be able to immediately follow the reduction. The return valve 13 is therefore always open if the brake pressure in the wheel is greater than the pressure prevailing before the inlet valve 6. This serves to avoid self-braking. Since there is no longer any interaction by the driver, the four return valves 13 can be dispensed with (as shown in fig. 2).

As also shown in fig. 2, the brake system 100 may have two hydraulic circuits I, II. Each hydraulic circuit I, II may fluidly operate two wheels. It is conceivable here that the first hydraulic circuit I can operate the left front wheel brake VL and the right rear wheel brake HR (so-called diagonal split) or both front wheel brakes VL, VR (so-called axial split). The second hydraulic circuit II can operate, for example, a right front wheel brake VR and a left rear wheel brake HL or two rear wheel brakes HL, HR. Each hydraulic circuit I, II is able to hydraulically operate two wheels respectively. Thus, the brake system 100 may meet high availability requirements.

Within the framework of the invention, it is conceivable for each hydraulic circuit I, II to have its own return pump 11 with its own drive motor 14. It is also conceivable, however, for the hydraulic circuits I, II to have the return pump 11 on the same axis (so-called coaxial connection).

Furthermore, it is conceivable that each hydraulic circuit I, II has its

own control unit

31,32 for adjusting its

valves

6,7 and its return pump 11 in the frame of the control device 30. The

control units

31,32 may use a common sensor cluster 33 for detecting longitudinal and/or lateral acceleration and/or deflection rate (girrat). The two

control units

31,32 can communicate with each other via a data bus 36. The energy supply takes place via

energy stores

34, 35. It is conceivable here for each hydraulic circuit I, II to have its own

electrical energy supply

34, 35. Communication between the brake system 100 and the vehicle and within the brake system 100 may likewise be effected via the data bus 36.

The control device 30 may be provided as a separate control device 30 or executed in a central control device of the vehicle. By means of the control unit 30 within the framework of the invention, it is possible to provide the vehicle with all safety and driving assistance systems by means of the brake pressure generating and distributing system 10, while at least an electronic brake pressure distribution, an anti-lock braking system ABS and/or a drive slip control ASR and/or an electronic stability program ESP are provided. In other words, the brake system 100 according to the invention makes it possible to implement all safety systems and driving assistance systems that determine and/or generate a braking force by means of the brake pressure generating and distributing system 10 according to the invention.

Furthermore, each hydraulic circuit I, II has its own electric parking brake EPB. The electric parking brake EPB is preferably associated with wheels that are not hydraulically braked by the respective hydraulic circuit I, II. In other words, each hydraulic circuit I, II can hydraulically brake two wheels and electrically brake one wheel.

The foregoing description of the drawings merely describes the invention in an illustrative context. Of course, the individual features of the embodiments can be freely combined with one another as far as is technically appropriate, without leaving the scope of the invention.

List of reference numerals

1 brake force booster

2 master brake cylinder

3 pipeline

4 brake pedal, pedal simulator

5 Pre-pressure sensor

6-inlet valve

7 discharge valve

8 separating valve

9 separating valve

100 braking system

10 brake pressure generating and distributing system

11 feedback pump

12 low voltage storage

13 reflux valve

20 brake fluid balance container

30 control device

31 control unit

32 control unit

33 sensor cluster

34 energy accumulator

35 energy accumulator

36 data bus

101 wheel brake

102 wheel speed sensor

P pumping side

S suction side

EPB electric parking brake

VL left front wheel brake

VR Right front wheel brake

HL left rear wheel brake

HR right rear wheel brake.

Claims

1. A braking system (100) for a vehicle driven without a driver and without a brake pedal, having:

a brake pressure generating and distributing system (10) for generating and distributing brake pressure to wheel brakes (101) of said vehicle by means of brake fluid, and

a brake fluid balancing reservoir (20),

it is characterized in that the preparation method is characterized in that,

the brake fluid balancing container (20) is directly fluidically coupled to the brake pressure generating and distributing system (10).

2. The braking system (100) of claim 1,

it is characterized in that the preparation method is characterized in that,

the brake pressure generating and distributing system (10) has at least one feedback pump (11), wherein the feedback pump (11) is directly fluidically coupled at its suction side (S) to the brake fluid balancing container (20) and/or the feedback pump (11) is fluidically coupled only from the suction side (S) to the brake fluid balancing container (20).

3. The brake system (100) according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

the direct fluid connection of the brake fluid balancing container (20) to the brake pressure generating and distributing system (10) is established via a direct, uninterrupted, open and/or valveless hydraulic line (3),

and/or the brake fluid balancing container (20) is directly fixed at the brake pressure generating and distributing system (10).

4. The braking system (100) of any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the brake pressure generating and distributing system (10) has a first hydraulic circuit (I) and a second hydraulic circuit (II).

5. The braking system (100) of the preceding claim,

it is characterized in that the preparation method is characterized in that,

the first hydraulic circuit (I) and the second hydraulic circuit (II) each have an inlet valve (6) and an outlet valve (7) for each wheel brake (101).

6. The braking system (100) of any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the first hydraulic circuit (I) and the second hydraulic circuit (II) have a respective return pump (11) which can be driven in each hydraulic circuit (I, II) by a respective motor (14).

7. The braking system (100) of any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the brake pressure generating and distributing system (10) has an Electric Parking Brake (EPB) for each rear wheel brake (HL, HR) or for each front wheel brake (VL, VR) of the vehicle,

and/or the Electric Parking Brake (EPB) can be driven at each wheel brake (101) by a motor-transmission unit close to the wheel,

and/or at least one hydraulic circuit (I, II) is associated with at least one Electric Parking Brake (EPB) which brakes a wheel which is not hydraulically braked by the associated hydraulic circuit (I, II).

8. The braking system (100) of any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

a control device (30) is provided for operating the brake pressure generating and distributing system (10),

and/or the control device (30) has a control unit (31,32) for each hydraulic circuit (I, II),

and/or the control device (30) provides the vehicle with at least one electronically controllable safety or driving assistance system by means of the brake pressure generating and distributing system (10).

9. The braking system (100) of any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the brake system (100) has only one brake fluid balancing container (20).

10. A driver-free and brake pedal-free driven vehicle with a brake system (100) according to any one of the preceding claims.