WO2015104122A1

WO2015104122A1 - Brake system for motor vehicles

Info

Publication number: WO2015104122A1
Application number: PCT/EP2014/077211
Authority: WO
Inventors: Hans-Jörg Feigel
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2014-01-10
Filing date: 2014-12-10
Publication date: 2015-07-16
Also published as: DE102014200269A1; KR20160106600A; CN105899416A; CN105899416B

Abstract

The invention relates to a brake system for motor vehicles having a plurality of operating modes, which brake system can be controlled both by the vehicle driver and also independently of the vehicle driver in a preferably used "brake-by-wire" operating mode and can be controlled only directly by the vehicle driver in a fall-back operating mode. According to the invention, in order to reduce the number of constantly electrically energized valves required for brake pressure control in normal operation, means (38, 50, 51) are provided which make it possible, during the pressure reduction in the "brake-by-wire" operating mode, to keep the pressure at a pressure equalization connection (49) of the second pressure chamber (18a, 18b) at the level of the pressure-providing device (5) and to conduct the pressure-reduction volumetric flow from the pressure equalization connection (49) into the pressure-providing device (5).

Description

Brake system for motor vehicles

The present invention relates to a brake system for

Motor vehicles according to the preamble of claim 1.

Such a brake system for motor vehicles is known for example from DE 102011081463 AI. The known brake system comprises an actuatable by means of a brake pedal main ^¬ brake cylinder with two pressure chambers, wheel brakes, an electrically controllable pressure supply device, a pressure control valve assembly with two valves per wheel brake, two more isolation valves per brake circuit for decoupling the main ^¬ brake cylinder pressure chambers of the wheel brakes in Brake pedal travel simulation device, which is connected to the pressure chambers of the master cylinder and which can be switched on and off via a simulator release valve, in order to ensure a high availability of the brake system, also in the fallback mode, the brake system comprises a total of thirteen valves and the simulator release valve must be made normally closed, so that in case of failure of the electrical power supply to the brake system in the fallback mode, a shutdown of the brake pedal travel simulation be ensured direction and the possibility of a hydraulic pressure build-up on the wheel brakes by the driver. A disadvantage of the known brake system is the large number of valves, which leads to high production costs for the brake system. Furthermore, the large number of valves is disadvantageous, which must be activated for a normal braking in the "brake-by-wire" mode.

Object of the present invention is therefore to provide a brake system that can be realized with reduced effort on valves and at the same time inexpensive to produce. This object is achieved by a brake system according to claim 1.

The invention is based on the idea that means are provided which make it possible during a pressure reduction in the

"Brake-by-wire" mode to keep the pressure at a pressure equalization port of the second pressure chamber at the level of Druckbe ^¬ provisioning device and to direct the pressure reduction flow from the pressure equalization port in the pressure supply device.

Preferably, the means are formed by an electrically actuated, normally open 2/2-way valve in a connection between the pressure equalization port and the pressure medium reservoir and a hydraulic connection between the pressure equalization ^¬ connection and the pressure supply device.

According to a preferred embodiment of the invention, a check valve opening towards the pressure supply device is inserted in the connection between the pressure equalization connection and the pressure supply device.

The invention has the advantage that can be dispensed with an additional isolation valve per brake circuit between the master cylinder and exhaust valve.

Preferably, the second pressure chamber of the master cylinder is formed by two parallel partial pressure chambers, which are each bounded by a second piston and which are hydraulically connected to each other separable. Particularly preferably, the first piston with the second piston in force-transmitting connection, for example, a mechanical Vebindung, brought. According to a space-saving embodiment of the invention, one of the partial pressure chambers is connected downstream of the first piston and the first pressure chamber coaxially. The other partial pressure chamber with the associated second piston is arranged at a distance from the first pressure chamber. Particularly preferably, the associated second piston can be acted upon via a hydraulic connecting line with the pressure introduced in the first pressure chamber.

Preferably, the restoring spring biasing the first piston is disposed outside the first pressure chamber coaxially with the first piston.

According to one embodiment of the invention, the return spring is arranged in a coaxial with the first piston formed hydraulic annular chamber having a closable by the first piston connection to the first pressure chamber. Particularly preferably, a hydraulic connection is provided between the annular chamber and the pressure medium reservoir, in which a parallel connection of an electrically actuated, normally open simulator valve is connected with a valve opening to the annular chamber between.

Preferably, the brake pedal travel simulator is integrated in the first piston.

Preferably, both the electrically actuated intake valves and the electrically actuated exhaust valves are designed as normally open 2/2-way valves. The number of valves to be supplied for normal braking in the "brake-by-wire" mode is then particularly low.

Alternatively, it is preferred that the electrically actuated intake valves are designed as normally closed 2/2-way valves with electrical amplification of the closing force. "

In the hydraulic connections between the pressure-providing device and the inlet valves, a check valve which closes in the direction of the pressure supply device is preferably arranged in each case.

Preferably, between the first pressure chamber of the main brake ^¬ cylinder and a chamber of the pressure medium reservoir, a hydraulic connection is provided in which an electrically actuated, normally closed drain valve is connected between.

Furthermore, it is preferred that a hydraulic connection is provided with an electrically actuated valve, by means of which the pressure supply device is connected to the first pressure chamber separable. The valve is particularly preferably carried out normally closed. The hydraulic connection is particularly preferred

Between the pressure supply device and the hydraulic connection between the first pressure chamber and the pressure medium reservoir, or

Between the pressure supply device and the hydraulic connection between the annular chamber, which is separably connected to the first pressure chamber, and the pressure medium reservoir

arranged.

The electrically controllable pressure supply device is preferably designed as a single-circuit electrohydraulic actuator.

The actuator of the pressure supply device is preferably formed by an electric motor and a cylinder-piston arrangement, which is connected downstream of the electric motor, wherein the piston is driven by the electric motor and wherein at least one of a state quantity of the electric motor detecting sensor is provided. Further preferred embodiments of the invention will become apparent from the subclaims and the following description with reference to figures.

Show it

Fig. 1 is a hydraulic circuit diagram of a first embodiment of a brake system according to the invention, and

Fig. 2 is a hydraulic circuit diagram of a second embodiment of a brake system according to the invention.

The brake system shown in Fig. 1 consists essentially of a by means of an actuating or not shown

Brake pedal operated hydraulic actuator 1, one of the hydraulic actuator 1 associated pressure fluid reservoir 2 with an electrical

Level warning device 3, a cooperating with the hydraulic actuator 1 brake pedal travel simulator 4, an electrically controllable pressure supply device 5, electrically controllable Druckmodulations- or intake and exhaust valves 6a-6d, 7a-7d, to the wheel brakes 8, 9, 10, 11th a motor vehicle, not shown, are connected. The exhaust valves 7b, 7d of the wheel brakes 9 and 11, which are associated with the front axle of the vehicle, are in this case connected to the master cylinder 1 closing check valves 57b, 57d connected in parallel, the exhaust valves 7a-7d as normally open

(SO-), analog controllable 2/2-way valves are formed. The inlet ports of the intake valves 6a-6d shown in FIG Embodiment as a normally open (SO) analog

controllable 2/2-way valves are shown are supplied by system pressure line sections 12a, 12b with a pressure which is referred to as system pressure. The aforementioned components 6a - 6d, 7a - 7d, 12a, 12b, 57b, 57d can be combined to form an electrohydraulic module and thus form a pressure modulation unit, not designated in more detail.

As also shown in the drawing, the hydraulic actuation unit 1 of the brake system according to the invention is embodied in an electrohydraulic control and regulation unit 31 and has hydraulic pistons 15, 16a, 16b, the hydraulic chambers or. Limit pressure chambers 17, 18a, 18b, which together with the pistons 15, 16a, 16b form a dual-circuit master cylinder. In this case, the first piston 15 is also referred to as the primary piston and its associated pressure chamber 17 as a primary pressure chamber, while the primary pressure chamber 17 on the one hand and the second (secondary) eildruckräume 18a, 18b limiting second piston 16a, 16b be referred to as a secondary piston. The (secondary) eildruckräume 18 a, 18 b with the associated secondary pistons 16 a, 16 b are adjacent in the embodiment shown next to each other (eg parallel). The (secondary) partial pressure chambers 18a, 18b receive return springs 19a, 19b, which position the secondary pistons 16a, 16b in an initial position when the master brake cylinder is not actuated. A provided for the same purpose, the primary piston 15 biasing return spring 25 is arranged coaxially to the primary piston 15 in a hydraulic annular chamber 24, which is in unconfirmed master cylinder 1 with the primary pressure chamber 17 in conjunction. The return spring 25, which is supported on an unspecified stop in the electro-hydraulic control unit 31, can of course also be arranged in the primary pressure chamber 17. The hydraulic annular chamber 24 communicates with the pressure medium reservoir 2 by means of a Pressure medium line 46 in conjunction, in which a normally open (SO) 2/2-way valve or simulator valve 47 is inserted.

The pressure chambers 17 and 18a, 18b are connected via the pressure medium lines 46 and 33 with the pressure medium reservoir 2 in connection, which can be shut off by a relative movement of the pistons 15 and 16a, 16b relative to the electro-hydraulic control and regulation unit 31. The (secondary) eildruckräume 18 a and 18 b are hydraulically connected to each other, wherein the connection by a relative movement of the piston 16 a, 16 b is shut off.

The first piston 15 and the second pistons 16a, 16b are arranged such that the first piston 15 can be brought into a force-transmitting (mechanical) connection with the second pistons 16a, 16b.

Furthermore, the first pressure chamber 17 is by means of a pressure medium telleitung 58 with an advantageously energized ge ^¬ closed, drain valve 20 is connected separably to the pressure medium reservoir. 2 Thus, the pressure chamber 17 in the actuated state of the piston 15 "depressurized" are switched by pressure chamber 17 by opening the drain valve 20 with the

Pressure medium reservoir 2 is connected.

On the other hand, the secondary partial pressure chambers 18a, 18b by means of hydraulic lines 22a (brake circuit I), 22b (brake circuit II) with the exhaust valves 7a, 7b and 7c, 7d, and thus the wheel brakes 8-11, in conjunction.

A connected to the annular chamber 24 pressure sensor 56 detects the pressure built up in the annular chamber 24 by a displacement of the first piston 15. A piston rod 23 couples the Pivoting movement of the brake pedal, not shown, due to a pedal operation with the translational movement of the first

(Primary) piston 15, the actuation path is detected by a preferably before ^¬ redundantly designed displacement sensor 30. As a result, the corresponding piston travel signal is a measure of the brake pedal actuation angle. It represents a braking request of a driver.

The control of all, previously mentioned electrically actuated components is an electronic control and regulation unit 39th

It is also apparent from the graphic representation of the exemplary brake system that the aforementioned brake pedal travel simulator 4 is hydraulically actuated and substantially from a connected to the hydraulic annular chamber 24 simulator chamber 26, a a

Elastomer simulator spring 29 receiving simulator spring chamber 27 and a two spaces 26, 27 separated from each other simulator piston 28 consists. The sealing of the simulator piston 28 is only a schematically indicated sealing ring 55th

The simulator effect is by activating the

Simulator valve 47 switchable. Parallel to the simulator valve 47, a check valve 21 is arranged, which allows a largely unge ^¬ hindered backflow of the pressure medium from the Druckmit ^¬ telvorratsbehälter 2 to the annular chamber 24, regardless of the switching state of the simulator 47. 1, the previously mentioned electrohydraulic pressure supply device 5 consists essentially of a hydraulic cylinder-piston arrangement 34 and an electromechanical drive unit 35, for example, by an electric motor _

y is formed with a downstream mechanical transmission, which converts a rotational movement of the electric motor into a translational movement of a hydraulic piston 36, so that in a pressure chamber 37 of the hydraulic cylinder-piston assembly 34, a hydraulic pressure is built up. The electromechanical

Drive unit 35 is powered by an electrical energy storage, not shown, with energy. In order to enable a suitable control of the electric current supplied to the electric motor 35 are the characteristic operating variables of the electric motor 35 detecting sensors, in particular Stromsen ^¬ sensors 40 provided for the phase currents. As a further example, one of the detection of the rotor position of the electric motor 35 serving, only schematically indicated rotor position sensor is designated by the reference numeral 41. In addition, a temperature sensor 42 for detecting the temperature of the motor winding may also be used. The piston stroke is in this case preferably detected indirectly before ^¬ on the rotational angle of the electric motor 35th This is particularly advantageous if an electronically commutated electric motor is used with a rotor position sensor which is already present anyway. The detection of the hydraulic pressure or system pressure generated by the electrohydraulic pressure supply device 5 is a pressure sensor, which is provided with the reference numeral 45. To the pressure chamber 37 of the hydraulic piston-cylinder assembly 34, a system pressure line 54 is connected, which connects the pressure chamber 37 via a respective line section 54a, 54b with the above-mentioned system pressure line sections 12a, 12b. In the line sections 54a and 54b in each case one of the wheel brakes 8, 9 and 10, 11 opening check valve 51a, 51b is inserted. A suction of pressure medium from the pressure fluid reservoir 2 in the pressure chamber 37 via a pressure medium supply line 44, which to minimize Ansaugwiderständen a large selected flow cross-section has. In the pressure medium supply line 44 is a for

Pressure medium reservoir 2 toward closing check valve 43 inserted, which allows the mentioned sucking of pressure medium in the pressure chamber 37.

In order to make it possible, during the pressure reduction in the "brake-by-wire" mode, to maintain the pressure at the pressure compensation port 49 of the second pressure chamber 18a, 18b (in pressure equalization line 33) at the level of the pressure supply device 5 and to reduce the pressure reduction from the pressure equalization port 49 in FIG To direct the pressure supply device 5, between the pressure chamber 37 of the electro-hydraulic pressure supply device 5 and the aforementioned pressure medium supply line 44 and the pressure equalization port 49 (or pressure medium line 33) a line section 50 is provided in which a non-return valve 51c opening to the pressure chamber 37 of the electrohydraulic pressure supply device 5 is inserted. serves the same purpose in the pressure with a ^¬ telleitung 33 between the pressure equalization connection 49 and the pressure fluid reservoir 2 is arranged, preferably analog controllable, normally open 2/2-way valve 38.

A normally closed (SG) 2/2-way switching valve 52 is inserted in a line section 53 between the pressure medium supply line 44 and the above-mentioned pressure medium line 58.

For normal braking in the "brake-by-wire" mode of operation, only the valves 38, 20 and 47 are to be activated, ie to be energized, so that the exemplary embodiment offers the advantage that the number of times for a normal braking in the "brake -by-wire "mode to be energized valves is low. Fig. 2 shows a hydraulic circuit diagram of a second guide from ^¬ a brake system according to the invention, which is particularly space-saving. For the components of the second exporting ^¬ approximately example corresponding to those in Fig. 1, the same reference numerals are used. In the second embodiment, the aforementioned brake pedal travel simulator 4 is arranged in the primary piston 150, in particular in its central region.

The normally closed (SG) 2/2-way switching valve 52 is inserted according to the example in a line section 53 between the pressure medium supply line 44 and the pressure medium line 46. This is an alternative arrangement of the line ^¬ section 53 with switching valve 52, which also in a

Brake system may be executed, which otherwise corresponds to the ^exemplary embodiment of FIG. 1 ^¬ . Accordingly, in a brake system, which otherwise corresponds to the second embodiment, the line section 53 with

Switching valve 52 between pressure medium supply line 44 and pressure medium line 58 may be arranged (as in Fig. 1).

Furthermore, the second differs from the first exemplary embodiment in that the first secondary partial pressure space 180a bounded by a first secondary piston 160a is "free" in the second exemplary embodiment in the electrohydraulic control and regulation unit 31 (eg spaced apart from the primary pressure chamber 170, secondary piston 160b and secondary Teedruckraum 180b), preferably parallel, to the second secondary partial pressure space 180b is arranged such that the first secondary piston 160a with the in the first (primary) pressure chamber 170 controlled pressure

can be acted upon.

Primary pressure chamber 170 is limited, for example, by the primary piston 150 and the second secondary piston 160b (and the control unit 31). Furthermore, primary pressure space is 170 connected via an unspecified hydraulic connection ^¬ line with an unspecified hydraulic pressure chamber, which is bounded by the first secondary piston 160 a and the control unit 31.

The second secondary partial pressure space 180b is connected downstream of the primary piston 150 coaxially therewith so that mechanical transmission of power from the primary piston 150 to the second secondary piston 160b is possible in the event of failure of the pressure introduced in the primary pressure chamber 170. A mechanical power transmission from the primary piston 150 to the first secondary piston 160a is not possible due to the objected arrangement.

In the second exemplary embodiment, the inlet valves 106a-106d are designed as normally closed (SG), analogously controllable 2/2 directional control valves. Such can also be used in the first embodiment.

For normal braking in the "brake-by-wire" mode, the valves 38, 20, 47 and 106a-106d are to be activated, i.e. energized.

Otherwise, numerous modifications may be proposed in the present invention without departing from the scope of the invention. As an example, the possibility to imagine ^¬ it to carry out the Radmodulationsventile such that they are driven in multiplex mode. In this case, each wheel brake 8-11 is associated with only one, preferably normally open (SO), analogously controllable 2/2-way valve. When

Pressure supply device 5, a simple (pulsation low) pump or a reversing pump can be used. In addition, by omitting the check valves 57b, 57d at the exhaust valves 7b, 7d a real, wheel individual Multiplexing also be implemented as desired for the pressure reduction with the Druckbereitstel ^¬ treatment device.

The operation of the brake system according to the invention both in the preferred mode "brake-by-wire" and in the so-called. Fallback mode results for the working in the relevant technical field expert from the disclosure of the present patent application and therefore need not be explained in detail.

Claims

Brake system for motor vehicles, which can be controlled in a "brake-by-wire" mode both by the driver and independently of the driver, is normally operated in the "brake-by-wire" mode and operated in at least one fallback mode can, in which only the operation by the driver is possible, with

Hydraulic wheel brakes (8, 9, 10, 11),

A brake pedal for actuating a master brake cylinder (1), the pressure of which in the fallback mode can be applied to the wheel brakes (8, 9, 10, 11), the master brake cylinder (1) comprising at least a first (15; 150) and a second piston (15). 16a, 16b, 160a, 160b) which define a first (17, 170) and a second pressure space (18a, 18b, 180a, 180b) and are positioned by return springs (25, 19a, 19b) in a starting position,

A pressure medium reservoir (2) which is under atmospheric pressure and can be connected to the second pressure chamber via a pressure equalization connection (49),

A displacement detection device (30) which detects the actuating travel of the first piston (15),

• a brake pedal travel simulator (4), the "ke-by-wire flying colors" in the; mode the driver provides a braking ^¬ pedal feel and with the master brake cylinder (1) is hydraulically connected with a simulator piston

(28), a simulator chamber (26) in the "brake-by-wire" mode that from the master cylinder

(1) receives displaced pressure medium volume, and a simulator spring space receiving a simulator spring (29)

(27), An electrically controllable pressure supply device (5) for actuating the wheel brakes (8, 9, 10, 11),

• per wheel brake an electrically actuated inlet valve (6a-6d, 106a-106d), and in particular an electrically actuated exhaust valve (7a-7d), for setting wheel-specific brake pressures, and

• an electronic control unit (39), in particular for controlling the pressure provisioning ^¬ means (5) and the intake valves, and in particular ^¬ sondere of the exhaust valves,

characterized in that

Means (38, 50, 51) are provided which allow the pressure at the pressure equalization port (49) of the second pressure chamber (18a, 18b, 180a) during pressure reduction in the "brake-by-wire" mode 180b) to be maintained at the level of the pressure supply device (5) and to direct the pressure reduction volume flow from the pressure equalization connection (49) into the pressure ^preparation device (5).

Brake system according to claim 1, characterized in that the means by an electrically operable, normally open 2/2-way valve (38) in a connection (33) between the pressure equalization port (49) and the

Pressure medium reservoir (2) and a hydraulic connection (50) between the pressure equalization port (49) and the pressure supply device (5) are formed.

Brake system according to claim 2, characterized in that in the connection (50) between the pressure equalization port and the pressure supply device to the pressure supply device towards opening check valve (51) is inserted.

Brake system according to one of claims 1 to 3, characterized in that the second pressure chamber of the main ^¬ brake cylinder by two parallel part ^¬ pressure chambers (18a, 18b, 180a, 180b) is formed, each by one, in particular with the first piston ( 15, 150) can be brought into force-transmitting connection, the second piston (16a, 16b, 160a, 160b) are limited and which are hydraulically connected to each other separable.

Brake system according to claim 4, characterized in that one of the partial pressure chambers (180b) is connected coaxially downstream of the first piston (150) and the first pressure chamber (170) and in that the other partial pressure chamber (180a) with the associated second piston (160a) is spaced from the first Pressure chamber (170) is arranged, wherein the associated second piston (160a), in particular via a hydraulic connecting line, with the in the first pressure chamber (170) controlled pressure can be acted upon.

Brake system according to one of claims 1 to 5, characterized in that the first piston (15, 150) biasing return spring (25) outside the first pressure chamber (17, 170) is arranged coaxially to the first piston.

Brake system according to claim 6, characterized in that the first piston (15, 150) biasing return spring (25) is arranged in a coaxial with the first piston formed hydraulic annular chamber (24) having a lockable by the first piston connection with the first pressure chamber (17, 170), in particular between between the annular chamber (24) and the pressure fluid reservoir (2) a hydraulic connection (46) is provided, in which a parallel connection of an electrically actuated, normally open simulator valve (47) with a to the annular chamber (24) opening towards non-return valve (21) is interposed.

8. Brake system according to one of claims 1 to 7, characterized

in that the brake pedal travel simulator (4) is integrated in the first piston (150). 9. Brake system according to one of claims 1 to 8, characterized in that both the electrically operable inlet valves (6a-6d) and the electrically actuatable exhaust valves (7a-7d) are designed as normally open 2/2-way valves.

10. Brake system according to one of claims 1 to 8, characterized

in that the electrically actuatable inlet valves (106a-106d) are normally closed

2/2-way valves with electrical amplification

Closing force are formed.

11. Brake system according to one of claims 1 to 10, characterized in that in the hydraulic connections (54a, 54b) between the pressure supply device (5) and the inlet valves (6a-6d, 106a-106d) j e in the direction of

Pressure supply device (5) towards closing check valve (51 a, 51 b) is arranged.

12. Brake system according to one of claims 1 to 11, characterized in that between the first pressure chamber (17, 170) of the master cylinder (1) and a chamber of the pressure ^¬ medium reservoir (2), a hydraulic connection (58) is provided in the an electrically actuated, normally closed drain valve (20) between is switched.

Brake system according to one of claims 1 to 12, characterized in that a hydraulic connection (53) with an electrically actuated, in particular normally closed, valve (52) is provided, by means of which the pressure supply device (5) with the first pressure chamber (17, 170 ) is separably connected.

Brake system according to one of claims 1 to 13, characterized in that the electrically controllable Druckbe ^¬ provisioning device (5) is designed as a single-circuit electric rohydraulischer actuator (35, 36, 37).