DE102013213280A1 - Steering brake actuation unit for a hydraulic brake system - Google Patents

Abstract

Steering brake actuation unit (1) for a hydraulic brake system (100) for a motor vehicle, in particular a commercial vehicle, wherein the brake system (100) has at least one left wheel brake (2) with respect to a preferred direction of travel with a left brake circuit acting on the left wheel brake (2) (4) and at least one in relation to a preferred direction right wheel brake (3) with a right wheel brake (3) acting right brake circuit (5), at least one master cylinder (6) for generating brake pressure in at least one of the brake circuits (4 , 5) and at least one with the master cylinder (6) coupled brake pedal (7), wherein the brake system (100) is such that in the brake circuits (4, 5) for steering braking, a brake pressure difference can be brought about. In order to make such a brake system cheaper, more compact and easier to use is proposed according to the invention that the steering brake actuation unit (1) has a single master cylinder (6) for generating brake pressure for both brake circuits (4, 5), wherein the master cylinder (6) Switching valve unit (8) is assigned, which is adapted to the brake pressure from the master cylinder (6) at the same time on both brake circuits (4, 5) or one of the brake circuits (4, 5) separate from the brake pressure.

Description

The invention relates to a steering brake actuation unit for a hydraulic brake system for a motor vehicle.

Brake systems with a steering brake function are known in principle. In particular, in commercial vehicles such as tractors or farm tractors is a conventional wheel steering often not sufficiently effective or even ineffective in many applications such as field processing or to achieve very small turning circles. In order to assist the wheel steering in such cases, it is known to construct the brake system so that when required can be selectively braked only on the right or left side.

State of the art

For example, brake systems are known which each have separate brake circuits, each with its own master cylinder for the right and left sides. These master cylinders are foot-operated separately for steering braking, each with a brake pedal coupled to the respective master cylinder. Thus, for a steering brake alternately (rear brake right or rear brake on the left) is a single pedal for operation available.

If a steering brake function is not needed or undesirable, for example, for driving on the road, it is known to connect the two individual brake pedals with a clamp, a pivoting rocker or a similar mechanical coupling device.

Through the use of two separate individual master brake cylinders, two individual brake pedals together with associated mechanics, the mechanical coupling for the brake pedals and the need to regularly connect the brake pedals and decouple such braking systems are considered complex, and consuming in the operation and maintenance, also claim a relatively large amount of space.

Task:

It is therefore an object to provide an improvement for a braking system with steering braking, which makes such a brake system cheaper, more compact and easier to operate.

Solution and advantages:

The object is achieved according to the invention together with the characterizing features of the independent claim 1. Subclaims and figures indicate further possible advantageous embodiments and developments.

Characterized in that a single master cylinder is provided for generating brake pressure for both brake circuits and that a mechanically actuated and hydraulically coupled to the master cylinder Umschaltventileinheit to trigger the brake pressure difference can be provided in the brake circuits, it is easily possible, a steering brake hydraulic brake system with only a single Instead of designing two main brake cylinders and a single instead of two brake pedals, which can be much easier and more efficient operation in the operating process no cumbersome operations for coupling and decoupling of the brake pedals requires and requires less space. The activation of a steering brake function is possible at any time and without additional cumbersome measures such as the coupling and decoupling of the brake pedals

In an advantageous development of the invention, the changeover valve unit may comprise two valve bodies and a valve piston with two opposite valve seats, which is clamped between two return springs and axially displaceable between two end positions in a bore such that in each end position a respective valve seat bears against a valve body, so that a brake circuit is separated from the brake pressure, whereby a brake pressure difference can be generated in the brake circuits. This makes it possible to connect and disconnect a steering brake function particularly quickly, directly and directly, as well as in a small installation space. In addition, the braking force outside the steering brake function is particularly evenly distributed from a common pressure chamber on the brake circuits, tolerance compensation and non-uniformities, which would result in two non-inventive coupled brake pedals and separate brake circuit specific master cylinders are avoided.

In a further advantageous development of the invention, the switching valve unit may have a limited rotatable actuating shaft which is mechanically coupled to the valve piston, so that by rotation of the actuating shaft by a defined rotation angle, an axial displacement of the valve piston is triggered. In this way, an activation or deactivation of the steering brake function can be realized particularly accurately, efficiently, with a small amount of force and, if necessary, remotely operable and / or automatable.

In a particularly advantageous embodiment of the invention, the changeover valve unit can be arranged on the master cylinder, for example screwed or provided directly integrated. As a result, a compact modular design and particularly space-saving steering brake actuation unit is possible, and the installation and commissioning of the brake system are simplified.

In a further advantageous development, the changeover valve unit can be made operable by a remote control device, for example, with the interposition of a hydraulic or a mechanical pressure / train connection actuated by a mechanical manual changeover.

Likewise, in another embodiment of the invention, the remote control device can be made electromechanical and be actuated by an electrical switch. For example, the electrical switch can activate an electromechanical actuator by means of an electrical line, which acts on the actuating shaft.

As a result, the operation of the switching unit for the driver can be designed particularly ergonomically advantageous, for example by the release of the steering brake operations is particularly simple and energy-saving only by alternately pressing the manual switch or switch.

In a further embodiment of the invention, the manual switch or the switch can be configured lockable in at least three positions, wherein at least one middle position for a deactivated steering brake function and simultaneous braking with both wheel brakes and two end position for steering braking, each with a wheel brake can be provided. For example, the locking can be done within the invention by integrated catch or even by separate fixing devices. As a result, the respective active brake can be clearly optically detectable by the driver at any time, since the manual switch or the switch can be arranged with advantage in a direct viewing and gripping environment of the driver, for example on a dashboard and the active brake clearly by the locked position of the Hand switch or the switch is identifiable.

In another advantageous embodiment of the invention, the changeover valve unit and / or the master cylinder can be made of an extruded profile, preferably an extruded aluminum profile, for example, the extruded profiles can be designed so that this in addition to an outer contour and pressure chambers and / or holes for mounting screws already at least partially. As a result, an efficient and flexible modular construction of the steering brake actuation unit can be realized in a particularly simple and cost-effective manner, the expenditure for production and reworking is reduced, expensive molds or molds can be completely dispensed with. In addition, a modular system can be realized particularly cost-effective, which can flexibly serve different requirement profiles by exchanging individual standardized components in their dimensions.

Brief Description:

Other objects, features, advantages and applications of the invention will become apparent from the dependent claims together with the description with reference to the drawings. Matching components and construction elements will be given the same reference numbers if possible. Below shows:

1 Schematic diagram of a known brake system with two separate master cylinders, brake pedals and a coupling device

2 Schematic diagram of an improved brake system with a steering brake actuation unit according to the invention.

3 An embodiment of a steering brake actuation unit according to the invention with a mechanical remote control device.

4 Spatial sectional view of an embodiment of a switching valve unit according to the invention.

5 Sectional view of a switching valve unit according to 4 with a deactivated steering brake function.

6 Sectional view of a switching valve unit according to 4 with an activated steering brake function.

7 An embodiment of a steering brake actuation unit according to the invention with an electromechanical remote control device

Fig. 1

In the 1 is a well-known hydraulic brake system 100 shown with a steering brake function for a tractor.

The brake system 100 includes a left wheel brake 2 with one on the left wheel brake 2 acting left brake circuit 4 and a right wheel brake 3 with one on the right wheel brake 3 acting right brake circuit 5 , Each of the brake circuits 4 . 5 is each a separate master cylinder 6 . 6 ' each with a brake pedal coupled thereto 7 . 7 ' assigned. Further, a coupling device 15 provided in a coupled position 16 the two brake pedals 7 . 7 ' connects with each other and in a decoupled position 17 the aforementioned connection is resolved. In the coupled position 16 the coupling device 15 can the two brake pedals 7 . 7 ' only dependent on each other, to be moved simultaneously, whereas in the decoupled position 17 the brake pedals 7 and 7 ' can be moved independently of each other.

For a steering brake operation, the coupling device 15 in the decoupled situation 17 shifted and optionally just one of the brake pedals as needed 7 . 7 ' or one brake pedal is stronger than the other. This will be in one of the master cylinder 6 . 6 ' and therefore in one of the brake circuits 4 . 5 a relatively higher brake pressure is generated. This brake pressure differential causes one of the wheel brakes 2 . 3 stronger than the other is applied, a yaw moment arises and the tractor rotates or steers in the direction of the stronger braking wheel brake.

Furthermore, a pressure medium container 14 provided, which via hydraulic lines the two master cylinder 6 . 6 ' during operation of the brake system 100 feeds or absorbs the pressure medium.

Fig. 2

The 2 shows the schematic diagram of an improved brake system 100 with an embodiment of a steering brake actuating unit according to the invention 1 , The steering brake actuation unit according to the invention 1 has, in contrast to the known brake system 1 only 1 piece master cylinder 6 with a single, to the brake cylinder 6 coupled brake pedal 7 , The master cylinder 6 the steering brake actuation unit according to the invention 1 operates both brake circuits 4 and 5 and is dimensioned such that, in a simultaneous braking operation of both wheel brakes 2 and 3 a for a proper brake function sufficient pressure medium volume and brake pressure can provide. Preferably, a stroke volume of the master cylinder is 6 the steering brake actuation unit according to the invention 1 the sum of the stroke volumes of the two individual master brake cylinders 6 . 6 ' a braking performance comparable comparable known brake system 1 , It is of course possible within the invention, the master cylinder 6 to connect a brake booster, not shown here. It is also conceivable within the invention instead of the brake pedal 7 to provide a further additional or a different actuator, such as a brake lever, an electromagnetic or electromechanical actuator or other device.

The master cylinder 6 is a switching valve unit 8th hydraulically downstream, the input side with a pressure chamber, not shown, within the master cylinder 6 , on the output side with the brake circuits 4 and 5 is connected and via an arrangement of valves for selectively or simultaneously connecting the brake circuits 4 and 5 to the pressure chamber, not shown, within the master cylinder 6 features. Preferably, the switching valve unit 8th directly on the master cylinder 6 However, it can also be from the master cylinder 6 spatially resolved mounted in another location and via hydraulic lines to the pressure chamber within the master cylinder 6 be executed connected.

Upon actuation of the brake pedal 7 is in the master cylinder 6 Brake pressure built, which by the switching valve unit 8th depending on the driver's request, either only to the brake circuit 4 or to the brake circuit 5 or passed on to both brake circuits at the same time. As a result, depending on the driver's request, a printed brake pedal can also be used to decide directly whether a steering brake maneuver or a conventional braking should be initiated.

Fig. 3

The 3 shows a simplified embodiment of a first embodiment of a steering brake actuation unit according to the invention 1 with a mechanical remote control device 11 , Both the case 37 of the master cylinder 6 as well as the case 36 the switching unit 8th are made in the embodiment shown from an extruded profile, preferably an extruded aluminum profile. This can be used to manufacture the two housings 36 . 37 to be dispensed with costly molds or molds altogether. However, it is of course possible within the invention for the manufacture of housings 36 . 37 To use other manufacturing processes, such as casting or die casting.

The master cylinder 6 is by means of a push rod 18 operated, which in turn can be coupled to a brake pedal, not shown, a brake booster or another actuator. About a connection 20 Furthermore, the pressure medium container, not shown 14 hydraulically connected.

Departure is on the master cylinder 6 the changeover valve unit 8th attached, which over the connections 19 . 19 ' in each case to the brake circuits, not shown 4 and 5 hydraulically connected and via the rotatable actuating shaft 10 by means of a remote control device 11 can be operated and controlled.

The remote control device 11 includes a hand switch 12 which ergonomically favorable in a direct viewing or gripping environment of the driver, for example, can be attached to a dashboard. Via a mechanical pressure / train connection 21 For example, a Bowden cable, the movements of the hand switch 12 to the actuating shaft 10 transfer. Other transmission solutions, such as mechanically with rods, trains, or via separate hydraulic lines are also conceivable without departing from the invention.

By operating the manual switch 12 becomes the actuating shaft 10 twisted by the rotation angle W, causing the connections 19 . 19 ' and thus the brake circuits 4 . 5 either individually from the master cylinder 6 hydraulically shut off or released simultaneously.

Fig. 4

In the 4 is an embodiment of a switching valve unit according to the invention 8th in a spatial sectional view. The internal structure of the switching valve unit is designed to be substantially symmetrical, so that the rights and the left halves have largely identical structural elements and for the supply of the left 4 and the right one 5 Serve brake circuit. The housing 36 has two cavities 23 . 23 ' on which with a hole 38 connected to each other and at their ends facing away from each other by plugs 25 . 25 ' are sealed pressure-tight. In the hole 38 guided is a valve piston 9 displaceable and by means of the two return springs 26 . 26 ' elastic between the plugs 25 . 25 ' biased arranged. In every cavity 23 . 23 ' are in front of the respective stopper 25 . 25 ' each cavities 24 . 24 ' formed, with the connections not shown here 19 . 19 ' and thus the brake circuits 4 and 5 hydraulically connected.

Another bore forms a pressure chamber 27 which the bore 38 crosses and hydraulically with a Druckkamer the master cylinder, not shown 6 hydraulically connected in which brake pressure is established. Thus lies in the pressure chamber 27 the same pressure as in the master cylinder 6 , A breakthrough 28 and an axial bore 29 in the valve piston 9 provide a hydraulic coupling and pressure equalization of the chambers 24 . 24 ' with the pressure chamber 27 ,

Transverse to the hole 38 is in the case 36 actuating shaft 10 arranged, which can rotate limited about its longitudinal axis. By a firm with the actuating shaft 10 connected fingers 22 which is in a radial groove 39 in the valve piston 9 engages, the rotational movement of the drive shaft 10 in an axial movement of the valve piston 9 translated. Will the drive shaft 10 rotated by a rotation angle W left or right side, the valve piston is in the bore 38 shifted between two mutual stops or end positions, this will each one of the return springs 26 . 26 ' curious; excited. This additional biasing force is effective to assist in a rearward movement of the valve piston 9 back to its original or neutral position.

In the embodiment shown, the cavities 23 . 23 ' together with the chambers 24 . 24 ' and the hole 38 designed as a stepped bore, however, other embodiments such as simple cylindrical holes, blind holes or cavities with non-circular cross-sectional profiles are also conceivable within the invention. Likewise, the drive shaft 10 within the invention in one piece with the finger 22 be executed.

Fig. 5

The 5 shows the switching valve unit 8th to 4 with a deactivated steering brake function or in a neutral position.

The pressure medium passes out of the pressure chamber 27 about the breakthrough 28 and the axial bore 29 at the same time in both chambers 24 . 24 ' , There is thus a hydraulic connection between the two chambers 24 . 24 ' and the master cylinder 6 , a pressure equalization between the chambers 24 . 24 ' and the pressure chamber 27 and thereby also between the brake circuit 4 and the brake circuit 5 , Both wheel brakes 2 and 3 (please refer 1 ) are subjected to the same brake pressure and brake simultaneously and evenly.

The plugs 25 . 25 ' each have a pin-like valve body 30 respectively. 30 ' with a conical tip 31 respectively. 31 ' on. The valve piston 9 has two opposing valve seats designed as conical grooves 32 . 32 ' which are designed so that they at a particular plant at the top 31 . 31 ' a brake pressure-tight sealing seat 33 form and thus the pressure medium flow through the breakthrough 28 and the axial bore 29 optionally in one of the chambers 24 . 24 ' prevention.

At the same time limit the peaks 31 . 31 ' the way of the valve piston 9 at its displacement in the hole 38 , thus serve as stops and define the two end positions for the valve piston 9 ,

Fig. 6

Unlike the 5 is the switching valve unit 8th in the 6 mapped in a shift or steering brake position.

The tips 31 . 31 ' the valve body 30 . 30 '' form through the system at the valve seats 32 . 32 ' for the valve body 9 two mutual attacks. Will the valve body 9 by a rotation of the actuating shaft 10 from the finger 22 moved in the direction of one of the valve body, its movement is in an end position by the application of the

In the position shown is the valve body 9 in the picture has been moved to the right, so that on the valve body 30 one between the valve seat 32 and the top 31 a sealing seat 33 is formed. This is the chamber 24 from the pressure chamber 27 separated hydraulically and the associated not shown brake circuit 5 off. The entire brake pressure is applied to the chamber 24 opposite chamber 24 ' and the associated brake circuit, not shown 4 Transfer, so that the wheel brake 2 at least stronger than the wheel brake 3 decelerating. This creates a yaw moment on the vehicle about the direction of travel, which leads to a change of direction and thus a steering operation or steering braking.

This is how the movement of the actuating axis leads 10 for alternately switching off one of the brake circuits 4 . 5 and thus for steering braking. Thus, when selecting a steering brake direction on the in the 3 shown hand switch 12 on / in the dashboard and pressing the single master cylinder 6 about a single brake pedal 7 guaranteed in the selected direction.

Preselecting the triggering of a normal braking by locking the manual switch, for example by means of detent in the center position, gives middle or neutral position of the valve piston 9 to 5 and thus prepare for braking with both wheel brakes 2 and 3 ,

Fig. 7

Unlike the embodiment according to 3 has the steering brake actuation unit 1 via an electromechanical remote control device 11 , The actuating shaft 10 is powered by an electromechanical actuator 34 moved by means of an electrical line 35 associated switch 13 or button is controlled.

LIST OF REFERENCE NUMBERS

1

 Steering brake actuation unit

2

 wheel brake

3

 wheel brake

4

 brake circuit

5

 brake circuit

6, 6 '

 Master Cylinder

7, 7 '

 brake pedal

8th

 change-over valve

9

 plunger

10

 actuating shaft

11

 remote control device

12

 hand switch

13

 switch

14

 Pressure fluid reservoir

15

 coupling device

16

 coupled location

17

 decoupled situation

18

 pushrod

19

 connection

20

 connection

21

 Pressure / train

22

 finger

23, 23 '

 cavity

24, 24 '

 chamber

25, 25 '

 Plug

26, 26 '

 Return spring

27

 pressure chamber

28

 breakthrough

29

 axial bore

30, 30 '

 mandrel

31

 top

32, 32 '

 valve seat

33

 sealing seat

34

 actuator

35

 electrical line

36

 casing

37

 casing

38

 drilling

39

 radial groove

100

 braking system

W

 rotation angle

Claims (9)

Steering brake actuation unit ( 1 ) for a hydraulic braking system ( 100 ) for a motor vehicle, in particular a commercial vehicle, wherein the brake system ( 100 ) at least one in relation to a direction of travel left wheel brake ( 2 ) with one on the left wheel brake ( 2 ) acting left brake circuit ( 4 ) and at least one in relation to a preferred direction of travel right wheel brake ( 3 ) with one on the right wheel brake ( 3 ) acting right brake circuit ( 5 ), at least one master cylinder ( 6 ) for generating brake pressure in at least one of the brake circuits ( 4 . 5 ) and at least one with the master cylinder ( 6 ) coupled brake pedal ( 7 ), wherein the brake system ( 100 ) is such that in the brake circuits ( 4 . 5 ) for steering braking, a brake pressure difference can be brought about, characterized in that the steering brake actuation unit ( 1 ) a single master cylinder ( 6 ) for generating brake pressure for both brake circuits ( 4 . 5 ), wherein the master cylinder ( 6 ) a switching valve unit ( 8th ), which is arranged in such a way, the brake pressure at the same time on both brake circuits ( 4 . 5 ) or one of the brake circuits ( 4 . 5 ) to be separated from the brake pressure. Steering brake actuation unit ( 1 ) according to claim 1, characterized in that the switching valve unit ( 8th ) a hole ( 38 ), two valve bodies ( 30 . 30 ' ) and a valve piston ( 9 ), wherein the valve piston ( 9 ) via two opposite valve seats ( 32 . 32 ' ), between two return springs ( 26 . 26 ' ) elastically clamped and so between two end positions in the bore ( 38 ) is arranged displaceably, that in each end position of the valve seats ( 32 . 32 ' ) for engagement with one of the valve bodies ( 30 . 30 ' ) comes. Steering brake actuation unit ( 1 ) according to claim 2, characterized in that the switching valve unit ( 8th ) a limited rotatable actuating shaft ( 10 ), wherein the actuating shaft ( 10 ) in such a way with the valve piston ( 9 ) is mechanically coupled, that the displacement of the valve piston ( 9 ) by a rotation of the actuating shaft ( 10 ) is triggered by a defined angle of rotation (W). Steering brake actuation unit ( 1 ) according to claim 1, characterized in that the switching valve unit ( 8th ) on the master cylinder ( 6 ) is arranged. Steering brake actuation unit ( 1 ) according to claim 1, characterized in that the switching valve unit ( 8th ) by a remote control device ( 11 ) is operable. Steering brake actuation unit ( 1 ) according to claim 5, characterized in that the remote control device ( 11 ) hydraulically or mechanically and by a mechanical hand switch ( 12 ) is pressed. Steering brake actuation unit ( 1 ) according to claim 5, characterized in that the remote control device ( 11 ) electromechanically and by an electrical switch ( 13 ) is pressed. Steering brake actuation unit ( 1 ) according to claim 6 or 7, characterized in that the hand switch ( 12 ) or the switch ( 13 ) is lockable in at least three positions, wherein at least one middle position for a deactivated steering brake function and simultaneous braking with both wheel brakes ( 2 . 3 ), an end position for a steering brake with wheel brake ( 2 ) and an end position for a steering brake with wheel brake ( 3 ) are provided. Steering brake actuation unit ( 1 ) according to claim 1, characterized in that the switching valve unit ( 8th ) is made of an extruded profile.

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