DE102013105377A1 - Actuating device for a vehicle brake system - Google Patents

Abstract

The invention relates to an actuating device for a vehicle brake system, with a first piston-cylinder unit, the at least one working space of which is to be connected to at least one wheel brake of the vehicle via at least one hydraulic line, furthermore with an electro-mechanical drive device and an actuating device, in particular a brake pedal and with a further piston-cylinder unit, the piston of which can be actuated by means of the actuating device and which is connected to a path simulator via a hydraulic line, and a working space of the further piston-cylinder unit (28, 30) via a hydraulic line (60), into which at least one solenoid valve (64, 66) is connected, is connected to at least one brake circuit and to an electronic control and regulating device (ECU). According to the invention, a device is provided for the purpose of controlling the free travel between a piston (4) of the first piston-cylinder unit (master cylinder) (2) and the piston of the further piston-cylinder unit (auxiliary piston) (30) , in the event of failure of the drive device when the piston (30) of the further piston-cylinder unit or a part connected to it hits the piston (4) of the first piston-cylinder unit (2) or a part connected thereto or shortly before opening a solenoid valve (70), through which hydraulic medium can be discharged from the auxiliary piston circuit.

Description

The present invention relates to an actuating device for a vehicle brake system according to the preamble of patent claim 1.

State of the art

Modern brake systems have a waysimulator (WS), on the one hand to produce the desired reaction to the brake pedal; On the other hand, the path simulator u. a. necessary for hybrid and electric vehicles with recuperation. Here, the driver controls the brake pedal and the brake management controls the brake pressure depending on the generator braking torque. The pedal plunger must not hit the master cylinder piston. It is therefore provided in these systems a Leerwegsteuerung in addition to a lock of the pedal plunger with full control of the path simulator.

These are electromechanical solutions from the DE 10 2005 018 649 and DE 10 2006 059 840 and electrohydraulic solutions from the DE 10 2009 055 721 and DE 10 2010 045 617 the applicant known. In the case of the former, the brake circuit is opened by means of solenoid valves for additional delivery, which represents a certain safety problem and is covered by appropriate diagnostic measures.

Furthermore, these known concepts have a good fallback in case of failure of the brake booster (BKV) with a relatively small master cylinder piston. Since the way of the master cylinder piston and thus the volume is limited, devices are by additional plunger from the DE 195 38 794 , Nachfördern from the DE 10 2007 062 839 and DE 10 2010 045 617 or by means of additional piston from the DE 10 2011 111 369 the applicant known.

Object of the invention

Object of the present invention is to reduce the cost of the Leerwegsteuerung.

Solution of the task

The object of the invention is solved by the features of claim 1.

With the solution according to the invention an actuating device is provided in a surprisingly simple manner, in which, in particular in case of failure of the drive device or the brake booster (BKV) with little effort, a control of the free travel can be made. In known hydraulic Leerwegfreischaltungen switching noise caused by the solenoid valves. This is prevented as a result of the fixed free travel provided by the invention.

In case of failure of the BKV is by means of the (auxiliary) piston of the further piston-cylinder unit which is connected to the pedal plunger, hydraulic means via the at least one solenoid valve (ESU1, ESU2) directly into the or the brake circuit (s) controlled. For this purpose, the piston must be dimensioned accordingly that he z. B. has the same cross-sectional area as the master cylinder piston, depending on the desired pedal characteristics in the fallback level. This avoids pedal diarrhea. When the pedal plunger or the auxiliary piston strikes the piston of the master cylinder or its extension, the result is a jump in force, since then the pressure forces of the master cylinder piston and the auxiliary piston act on the pedal plunger.

In order to largely avoid such a force jump, two embodiments of the invention are provided according to further claims:
In a first embodiment, a sensor device is provided, by means of which the pedal or piston stroke can be measured, wherein furthermore, in particular from the dimensioning of the further piston-cylinder unit (auxiliary piston), which pressure means via a solenoid valve (feed valve) in the or the Brake circuit (s) feeds the way is determined, in which an impact of the piston takes place and wherein the ECU opens shortly before striking a solenoid-separating valve and the feed valve closes and wherein at least one solenoid-separating valve is provided, which is connected in a hydraulic line is that connects the or the working or pressure chamber of the first piston-cylinder unit with a surge tank. In the phase of the short path or distance to the impact of the piston, the pedal force may drop. Upon impact of the piston acts in the aforementioned valve circuit (feeding finished, separating valve open) the pedal force fully on the master cylinder piston. So that in the feed phase, the pressure medium does not flow through the open beak hole of the master cylinder in the reservoir, a solenoid valve to the reservoir is closed.

When feeding, ie if in a failure of the BKV hydraulic medium is conveyed from the auxiliary piston directly into at least one brake circuit, the two pistons remain in the known starting position, which is known from braking before the BKV failure. On the other hand, the pedal stroke is measured by a sensor. From the piston dimensioning of the auxiliary piston, the way can be determined, at which an impact takes place or the feeding is terminated. Shortly before hitting the (WA) valve is opened, which causes no pressure on the auxiliary piston acts and he without Force jump or pedal force increase hits the master cylinder piston.

In the second embodiment, a sensor device is provided, which allows a force-displacement measurement and wherein when detected by means of the sensor device impingement of the piston opens the separating valve and closes the feed valve.

The advantage of this solution is a small pressure build-up interruption until the pedal force acts on the piston.

In a further advantageous embodiment of the invention, a transmission device is provided with an elastic member as shown in FIG DE 10 2010 045 617 the applicant is described. The elastic member measures the reaction forces on the auxiliary piston and the pedal piston via the deflection of the spring, whose characteristic is tuned to the system and at a certain pedal force to stop. Indirectly, the pressure in the auxiliary piston is measured here via the force-displacement curve and the differential path between the pedal travel and the auxiliary piston stroke. If now a failure of the brake booster on, which is detected by appropriate diagnosis, closes when pedal movement, the solenoid valve to the reservoir, the feed valve opens and the separating valve closes. About the differential path of the force or pressure increase is measured in the auxiliary piston. This value can also be compared with the signal of the pressure transducer from the brake circuit. Now meets the auxiliary piston on the (DK) piston of the master cylinder or its plunger, it immediately creates a strong increase in force, since both the force of the DK piston and the auxiliary piston act as a total force, resulting in a corresponding spring deflection = differential path. The sequence is as follows: Close the feed valve, open the isolation valve, open the solenoid valve to the reservoir.

Another very expedient embodiment of the invention provides an additional piston in front of the drive, in particular the spindle of the transmission is moved ( 2 ).

The solution with auxiliary piston and valve circuit with multiplex, i. with four valves, wherein in the brake line only one solenoid valve per wheel is provided, has the advantage of a larger delivery volume, so that no Nachfördern is required and in all functions of the brake circuit always remains closed. Should additional volume be required in the extreme case of heavy fading, additional volume can be drawn in by appropriate engine control via the master cylinder pistons and their sealing collars with closed solenoid valves. Further embodiments or embodiments of the invention and their advantages are contained in the further claims and are described in more detail below with reference to the drawing.

Show it:

1 a first embodiment of the invention, and

2 A second embodiment of the invention.

The embodiments of the invention shown in the drawing, show actuators for brake systems, with a first piston-cylinder unit (master cylinder), a drive with engine and transmission, a second piston-cylinder unit (auxiliary piston), a travel simulator, an actuator unit, and various valves and sensors (a further provided electronic control device is not shown). These components are also in the DE 10 2005 018 649 A1 The applicant described to the simplicity here in this regard. In the 1 illustrated embodiment of an actuating device for a vehicle brake has a first piston-cylinder unit 2 in whose housing a first piston (DK) 4 and a second piston (SK) 6 are arranged axially displaceable. The pistons 4 . 6 are about springs 4a . 6a supported against each other and at the bottom of the cylinder. The first piston 4 is designed as a hollow piston. The pistons 4 . 6 each limit working or pressure chambers 5 . 7 via hydraulic lines 9 respectively. 11 in which solenoid valves 15 . 17 respectively. 19 . 21 are arranged with wheel cylinders RZ or wheel brakes (not shown) are connected. These four solenoid valves are for pressure control according to the multiplexing method (MUX) described above. However, it can also be the usual eight solenoid valves, that is provided in each case one inlet and one outlet valve per wheel.

The piston 4 the piston-cylinder unit 2 is with an amplification device 10 connected, which is a bidirectional, driven by a (not shown) electronic control unit (ECU), electric motor rotary drive with stator 12 and rotor 14 and a gearbox 16 to implement a rotational movement in a linear movement and the translation. The rotor 14 is about two bearings in the housing 19 stored the drive. It is also useful (not shown) one-sided storage, in which the or the bearings are arranged on one side of the housing, that the bearing forces are transmitted substantially on one side into the housing. The gearbox is equipped with a ball screw 18 provided, the axially movable but rotationally concentric in the rotor 14 is arranged. The ball screw 18 rests with its front end 18a which is flange-shaped on an intermediate floor 4b of the piston 4 from and is positively or non-positively with the piston, advantageously via a magnetic coupling 20 , releasably coupled, allowing movements of the spindle 18 in both directions according to the piston 4 be transmitted. One inside the spindle 18 coaxial and slidably mounted ram 22 is with its front end on the piston 4 or on the extension 30a (the latter not shown) coupled. By means of a rotation angle sensor 24 can the movements of the rotor 14 measured and the corresponding signals of the electronic control unit (ECU) are supplied.

A second piston-cylinder unit 26 is the gearbox, in particular coaxial, upstream. The second piston-cylinder unit 26 has a cylinder 28 in which a piston 30 (Auxiliary piston) is arranged. A central extension 30a of the piston 30 Penetrates a provided with a seal central opening of the cylinder 28 and sticks out in one of the spindle 18 formed cavity. Between the pestle 22 and the end of the central extension 30a is a fixed free-path Lw installed (when the plunger 22 on the extension 30a is coupled, the idle Lw is provided in accordance between the end of the plunger and the auxiliary piston), which is dimensioned so that at full modulation of the (described below) path simulator 56 and locking the auxiliary piston via the solenoid valve 70 still no impact on the pestle 22 takes place when it is only slightly modulated when recuperation or low μ, ie hub makes.

Between a brake pedal 40 or a ram coupled thereto 42 and the auxiliary piston 30 is a transmission device 44 provided, which is a transmission element 46 having, with a cylindrical extension or transfer ram 46a in a corresponding cylindrical recess on the auxiliary piston 30 or its extension 30a is arranged axially displaceable and on the an elastic member or a spring 50 acts. The feather 50 can also be at another place between the transmission element 46 and the auxiliary piston 30 be arranged. The cylinder 28 or housing may be connected via a one-piece or multi-part intermediate housing, preferably made of plastic to the motor.

The auxiliary piston 30 and the transmission element 46 each have transmission means, such as extensions 31 respectively. 47 on that with their movement on at least two displacement sensors 52 respectively. 53 is transmitted. The operation of the brake pedal 40 over the pestle 42 , the transmission element 46 and the auxiliary piston 30 is thereby on the transmission means separately to the sensors 52 . 53 transfer. The signals of the displacement sensors are supplied to the aforementioned ECU and processed there, so that malfunctions can be detected if, for example, the auxiliary piston 30 or other related components jam. By measuring the length of the extensions 31 respectively. 47 traveled paths detects the evaluation of the piston force and the piston travel and determines in case of a mismatch on the force-spring characteristic of the elastic member a fault. The auxiliary piston force = pressure can be measured via the elastic member and a differential path measurement and corresponds to a force transmitter, which is also of great importance for fault diagnosis, eg when the auxiliary piston is clamped.

A hydraulic pipe 54 leads to a path simulator 56 consisting essentially of a piston arranged in a cylinder 58 and a spring arranged therebetween 60 consists. For a good response characteristic, it is known to incorporate a speed and direction-dependent throttling of the actuator. This is in the line 54 to the path simulator 56 a throttle 57 built-in and for quick return a check valve 59 ,

From the line 54 branches a line 62 connected to two normally closed solenoid valves (ESV1, ESV2) 64 . 66 leads. Another hydraulic line 68 into which a normally open solenoid valve (WA) 70 is switched, leads from the route simulator 56 to a storage container 72 , A line 74 connects via a check valve 76 the wires 62 and 68 , The working or pressure chambers 5 . 7 of the master cylinder 2 are each via lines 78 . 80 with the reservoir 72 connected, wherein at least in one of these lines, a normally open solenoid valve 82 . 84 is arranged. On the solenoid valve 84 can be omitted if in the switching sequence first the solenoid valve 64 is opened and only at a smaller idle Lw, for example 50% of the solenoid valve 66 is open. This is the piston 6 no longer over the breather hole of the master cylinder. Alternatively to the aforementioned circuit of the valves over the pedal stroke and the elastic member can be used.

The elastic member 50 (as in the DE 10 2010 045 617 the Applicant is described, to which reference is also made in this regard) measures the reaction forces on the auxiliary piston 30 and the pedal piston 46 about the deflection of the spring whose characteristic is tuned to the system and is at a certain pedal force to stop. Indirectly, the pressure in the auxiliary piston is measured here via the force-displacement curve and the differential path between the pedal travel and the auxiliary piston stroke. If now occurs a failure of the brake booster, which is detected by appropriate diagnosis, then closes when pedal movement that magnetic valve 78 to the reservoir 72 , the feed valve 64 . 66 opens and the isolation valve 70 closes. About the differential path of the increase in force or pressure in the auxiliary piston 30 measured. This value can be simultaneously with the signal of the pressure transducer 23 be compared from the brake circuit. Now hits the auxiliary piston 30 on the (DK) piston 4 the master cylinder or its plunger 22 , so immediately a strong increase in force, since both the force of the DK piston and the auxiliary piston act as a total force, resulting in a corresponding spring deflection = differential path. The switching sequence is: feed valve 64 . 66 close, isolation valve 70 open, solenoid valve 78 open to the reservoir.

The brake pedal 40 Acts on the pedal ram when actuated 42 and the transmission device 44 on the auxiliary piston 30 , wherein the displaced volume of this over the line 54 to the hydraulic path simulator 56 arrives. With the movement of the auxiliary piston 30 are over the transmission facility 44 the redundant pedal travel sensors 52 . 53 coupled via the ECU to the motor and at the same time the normally open solenoid valve 70 press, ie close. The path simulator 56 creates the desired reaction to the pedal force. The auxiliary piston 30 is blocked in an intermediate position with about 40% of the total piston stroke SHK when the Wegsimulatorkorkben 58 comes to a stop. According to the spring force of the Wegsimulatorfeder 60 arises at the auxiliary piston 30 a pedal-path-dependent pressure. About the solenoid valve 70 can if necessary pressure medium from the auxiliary piston 30 to the path simulator 56 and the brake circuits leading hydraulic line (auxiliary piston circle) in the reservoir 72 be dissipated. The solenoid valve 70 also has a pressure control function for safety reasons. Should the path simulator piston 58 clamp, so the pedal travel pressure function is disturbed, ie through the fault diagnosis flows through the then opened solenoid valve pressure medium via the line 66 to the reservoir 70 ,

Now occurs an error, eg failure of the brake booster (BKV) on, of the diagnostic circuit via the engine sensor 24 is detected, the function of supplying pressure medium from the auxiliary piston occurs 30 in force with the following switching sequence: feeding by opening the valves 64 and 66 , Closing the solenoid valves 70 and 82 and optionally 84 , Then, as a result of the pedal movement, the distance Lw between 30a and the pestle 22 smaller. This distance is measured by the pedal travel sensor. If the distance is very small, z. B. <1mm, the switching sequence described above is reversed: the valves 64 . 66 close and the solenoid valves 70 and 78 and possibly 84 to open. After that meets 30a / 22 on the DK piston 4 which leads to further pressure build-up. Within the small residual empty path, the pedal force falls imperceptibly, as it is quickly bridged. It can also simplify only through the solenoid valve 64 be fed into the circle, causing an imbalance in the movement of the pistons 4 . 6 leads.

For vehicles with high volume requirements, volume can be via solenoid valves 86 . 88 from the reservoir 72 be sucked. As a cheaper alternative to this without solenoid valves as conventional on the sealing sleeves of the master cylinder by appropriate vacuum generation with appropriate control of the master cylinder piston by means of the engine. For sucking in this case the solenoid valves 15 . 17 . 19 and 21 closed. The advantage here is that the brake circuit is not opened by additional valves. The valves 82 and 84 must be dimensioned accordingly in cross section.

2 shows another embodiment of the invention, which is particularly suitable for large vehicles that require a larger volume of brake fluid. The actuator of the 2 corresponds largely to the 1 , so that corresponding reference numerals are used in this regard. In contrast to the actuator gem. 1 are in the execution acc. 2 with the spindle 18 two additional pistons 86 and 88 coupled in holes 90 . 92 of the cylinder are arranged and which through openings 94 . 96 are in communication with the corresponding working spaces of the cylinder in order to promote additional volume in the brake circuits can. In case of failure of the BKV these do not work because the spindle movement is not effective. It then act only the master cylinder pistons-what the advantages described earlier brings with it. The arrangement of additional piston is already in principle in the DE 10 2011 111 369 the applicant, to which reference is also made in this regard.

In the invention, the brake booster (BKV) and pressure control for ABS / ESP and assistance functions of the brake circuit is always closed for all functions, which is a great safety advantage. Only in case of rare failure of the brake booster, e.g. in the range of 50 ppm, the auxiliary function then comes into force via the feed. In the event of an even more rare failure of the vehicle electrical system, in which the engine, transmission and all electrical functions fail, the auxiliary function is not possible with the comfortable fallback level (RFE) at which almost 3 times the braking effect required by law is achieved. But even in this case, more than double is achieved with pedal diarrhea = Lw.

LIST OF REFERENCE NUMBERS

2

Piston-cylinder unit (master cylinder)

4

first piston (DK)

4a

feather

4b

false floor

5

Working or pressure chamber

6

second piston (SK)

6a

feather

7

Working or pressure chamber

9

hydraulic line

10

reinforcing device

11

hydraulic line

12

stator

14

rotor

15

magnetic valve

16

transmission

17

magnetic valve

18

Ball screw

18a

End of the ball screw

19

casing

20

magnetic coupling

22

tappet

24

Rotation angle sensor

26

second piston-cylinder unit

28

Cylinder or housing

30

Piston (auxiliary piston)

30a

extension

31

extension

40

brake pedal

42

tappet

44

transmission equipment

46

transmission element

46a

extension

47

extension

50

elastic member or spring

52

displacement sensor

53

displacement sensor

54

hydraulic line

56

travel simulator

57

throttle

58

piston

59

check valve

60

feather

62

hydraulic line

64

magnetic valve

66

magnetic valve

68

hydraulic line

70

magnetic valve

72

reservoir

74

hydraulic line

76

check valve

78

hydraulic line

80

hydraulic line

82

magnetic valve

84

magnetic valve

86

additional piston

88

additional piston

90

drilling

92

drilling

94

Through opening

96

Through opening

lw

leerweg

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 102005018649 [0003]
• DE 102006059840 [0003]
• DE 102009055721 [0003]
• DE 102010045617 [0003, 0004, 0013, 0026]
• DE 19538794 [0004]
• DE 102007062839 [0004]
• DE 102011111369 [0004, 0030]
• DE 102005018649 A1 [0019]

Claims (12)

Actuating device for a vehicle brake system, comprising a first piston-cylinder unit, in particular a master cylinder whose at least one working space is to be connected via at least one hydraulic line with at least one wheel brake of the vehicle, further comprising an electro-mechanical drive device and an actuating device, in particular a brake pedal and a further piston-cylinder unit whose piston (auxiliary piston) is actuated by means of the actuating device and which is connected via a hydraulic line to a travel simulator and wherein a working space of the further piston-cylinder unit via a hydraulic line, Auxiliary piston circuit) in which at least one solenoid valve is connected, is connected to at least one brake circuit and is connected to an electronic control unit (ECU), characterized in that, for the purpose of controlling the free travel between a piston ( 4 ) of the first piston-cylinder unit (master cylinder) ( 2 ) and the piston of the further piston-cylinder unit (auxiliary piston) ( 30 ) a device is provided for in case of failure of the drive means upon impact of the piston ( 30 ) of the further piston-cylinder unit or a part connected to it on the piston ( 4 ) of the first piston-cylinder unit ( 2 ) or an associated part or shortly before a solenoid valve ( 70 ), can be removed via the hydraulic medium from the auxiliary piston circle. Actuating device according to claim 1, characterized in that at least one magnetic separating valve ( 82 . 84 ) is provided, which is connected in a hydraulic line, the or the working or pressure chamber of the first piston-cylinder unit ( 2 ) with a surge tank ( 72 ) connects. Actuating device according to claim 1 or 2, characterized in that the device comprises a sensor device ( 52 . 53 ), by means of which the pedal stroke can be measured, that further, in particular from the dimensioning of the further piston-cylinder unit ( 28 . 30 ), the way is determined, in which an impact of the piston ( 30 . 4 ) and that the control unit (ECU) shortly before hitting the solenoid valve ( 70 ) opens. Actuating device according to claim 1 or 2, characterized in that the device comprises a sensor device ( 52 . 53 ), which enables a force-displacement measurement and that the impact of the pistons detected by the sensor device causes the valve ( 70 ) opens. Actuating device according to one of the preceding claims, characterized in that one or two magnetic separating valves ( 82 . 84 ), which are closed when the valve ( 70 ) is open and which are open when the pistons ( 4 . 6 ) of the first piston-cylinder unit ( 2 ) in a position outside the sniffer region of the first piston-cylinder unit ( 2 ) are. Actuating device according to one of the preceding claims, wherein only one solenoid separating valve is provided, characterized in that a feed operation of hydraulic fluid via the valve ( 64 ) in the or the brake circuit (s) then begins when the pedal stroke has a small path, in particular <20% of its total path, go through and a diagnostic circuit has detected a failure of the brake booster. Actuating device according to one of the preceding claims, characterized in that at least one additional piston ( 72 . 74 ) is provided, which is actuated by the drive means to promote hydraulic fluid in at least one brake circuit. Actuating device according to one of the preceding claims, characterized in that the function of the solenoid valves ( 64 . 66 ) by actuating the master cylinder piston ( 4 . 6 ) By means of the engine control and the solenoid valve ( 70 ) is diagnosable in a diagnostic mode. Method for actuating a vehicle brake system having an actuating device with a first piston-cylinder unit, further comprising an electro-mechanical drive device and an actuating device and with a further piston-cylinder unit, as well as with a travel simulator and with an electronic control and Regeleinrichung (ECU), in particular according to one of the preceding claims, characterized in that for the purpose of controlling the free travel between a piston ( 4 ) of the first piston-cylinder unit (master cylinder) ( 2 ) and the piston of the further piston-cylinder unit (auxiliary piston) ( 30 ) in case of failure of the drive means upon impact of the piston ( 30 ) of the further piston-cylinder unit or a part connected to it on the piston ( 4 ) of the first piston-cylinder unit ( 2 ) or an associated part or shortly before hydraulic fluid is discharged from the auxiliary piston circle. Method for actuating a vehicle brake system according to claim 9, characterized in that the pedal stroke is measured, that further the path is determined, in which an impact of the piston takes place and that at or shortly before the impact of the piston hydraulic fluid is discharged from the auxiliary piston circle , Method for actuating a vehicle brake system according to one of claims 9 or 10, characterized in that an outflow of hydraulic medium into a reservoir is made possible when the pistons ( 4 . 6 ) of the first piston-cylinder unit ( 2 ) are in a position outside the sniffer area and the piston ( 46 ) or the plunger ( 46a ) the piston ( 4 ) has already moved. Method for operating a vehicle brake system according to one of claims 9 to 11, characterized in that the feed operation of hydraulic fluid via the valve ( 64 ) in the or the brake circuit (s) then begins when the pedal stroke a small path, in particular <5% of its total path, has passed through and a diagnostic circuit has detected a failure of the brake booster.

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