DE102016218506A1 - braking system - Google Patents

Abstract

The invention relates to a brake system having a pressure piston side of each conveyor (3) hydraulically acted on separating piston assembly (1), which is hydraulically biased by the conveyor devices (3) of both brake circuits (I, II), wherein the separating piston assembly (1) is designed self-sealing, for which the separating piston (10) is provided on both faces with sealing surfaces (38), the differential pressure dependent on the housing-side sealing surfaces (38) of the separating piston assembly (1) can be applied. Furthermore, a valve pair (51) of the separating piston assembly (1) is assigned to the self-locking of the brake circuits (I, II).

Description

The invention relates to a brake system with means for controlling the brake pressure according to the preamble of patent claim 1.

From the DE 10 2013 213 640 A1 is already such a brake system with means for controlling the brake and traction slip and the vehicle dynamics control known. This brake system has a master cylinder, which is connected via brake lines with a plurality of wheel brakes, in which electromagnetically actuated separating valves and intake valves are used. The wheel brakes of each brake circuit are connected via electromagnetically actuated exhaust valves, a low-pressure accumulator and a low-pressure accumulator downstream pressure control valve to the suction side of a conveyor into which also opens a suction line which is connected between the master cylinder and the isolation valve to the brake line. In the suction line, a changeover valve is used, which interrupts the pressure medium connection between the master cylinder and the suction side of the conveyor in its basic position. Furthermore, to reduce the pressure pulsations, a separating piston assembly is provided, which is acted upon hydraulically by the conveying devices of both brake circuits alternately.

In order to meet future requirements for as reliable as possible a brake system measures must be taken that take into account any leaks in the area of the separating piston assembly or within the brake circuits in the sense of functionality.

Therefore, it is the object of the present invention to improve a brake system of the specified type such that remain as simple as possible, functionally reliable means the previous requirements for an operational brake system guaranteed.

This object is achieved according to the invention for a brake system of the specified type with the features of claim 1.

Further features and advantages of the invention will become apparent hereinafter from the description of several embodiments with reference to drawings.

Show it:

1 a hydraulic circuit diagram of a brake system with an arrangement of a separating piston assembly between the brake circuits,

2 a longitudinal section through a separating piston assembly, the separating piston remains to block a chamber during a leak self-sealing on one of the two housing-side piston stops,

3 a longitudinal section through a separating piston assembly, the separating piston faces on one side of a piston stopper having an opening for passing a coil spring, which is supported between the separating piston and a plug housing the housing closing plug,

4 the separating piston assembly after 3 without the stopper closing the receiving housing, so that the helical spring can escape unhindered through the opening of the stop of the piston, whereby the separating piston in the manner of a check valve closes the opening in the stopper in a manner impermeable to leakage,

5 3 a longitudinal section through a separating piston assembly provided with a valve pair consisting of two non-return valves, which is accommodated in a piston stop,

6 a schematic representation of the in 5 structurally separated from the piston stop.

The 1 shows a schematic representation of a dual-circuit brake system with means for controlling the brake and drive slip and the vehicle dynamics control, the one from a master cylinder 15 and a pressure fluid reservoir 16 having formed brake pressure generator. At the master cylinder 15 closes for each brake circuit I . II one on a pair of wheel brakes 18 branched brake line 4 in, in each case a separating valve 31 and an electromagnetically operable inlet valve downstream thereof 17 are used. At the wheel brakes 18 close to each brake circuit I . II a return line 20 on, in the electromagnetically actuated exhaust valves 19 are inserted through the return lines 20 each with a low pressure accumulator 21 and the suction side of a conveyor 3 are connected, the pressure side between the separation and inlet valve 31 . 17 of each brake circuit I . II on the brake line 4 connected. Between the return line 20 and the suction side of the conveyor 3 opens into the return line 20 of each brake circuit I . II a suction line 32 a via an electromagnetic switching valve 33 on the master cylinder 15 connected.

About the suction line 32 each brake circuit I . II There is a hydraulic connection in both a traction slip and vehicle dynamics control between the master cylinder 15 and the suction side of the conveyor 3 , including the switching valve 33 his open and the isolation valve 31 takes his closed position. The regulation of the wheel brake pressure takes place in a known manner as a function of the wheel slip individually on the wheel by suitable switching of the intake and exhaust valves 17 . 19 , wherein excess pressure medium of the wheel brake 18 in the low-pressure accumulator 21 arrives.

In the brake release position as well as in slip-free brake actuation takes the illustration according to each isolation valve 31 the opened and the switching valve 33 the closed switching position. The same applies to the basic position of each inlet and outlet valve 17 . 19 the inlet side in the open and outlet side remains in the closed position.

The 1 discloses a pressure side of each conveyor 3 Hydraulically actuated separating piston assembly 1 , which are reciprocally from the conveyors 3 both brake circuits I . II is hydraulically operated. As continues from the 1 is below, is below the separating piston assembly 1 in every brake circuit I . II a backwater element 5 provided, in each case between the connection of the separating piston assembly 1 to the brake line 4 in the delivery pressure path 6 the conveyors 3 is arranged. In an expedient embodiment, the backwater element 5 executed either as a hydraulic fixed or cascade shutter or only as a throttle.

Furthermore, according to the 1 in a parallel connection to each backwater element 5 one in the direction of the brake line 4 opening check valve 7 arranged, which is connected to the delivery pressure path 6 is connected, so that the image of the backwater 5 in operative connection with the parallel-connected check valve 7 fulfills a cascade function.

The symbolically illustrated two conveyors 3 consist of two preferably 180 ° out of phase delivery piston, due to the action of the backwater 5 over a portion of their delivery each alternately a defined subset in a buffer storage space of the separating piston assembly 1 pump.

As from the synopsis of 1 with the following 2 to 6 is apparent, is with the help of the separating piston assembly 1 a targeted temporary storage of a defined delivery subset of the conveyors 3 in the chambers 8th . 9 guaranteed by, for example, one within the first brake circuit during the first 180 crank angle degree of promotion of a pump piston I in the chamber 8th displaced partial flow rate via the corresponding displaced separating piston 10 in the same amount from the chamber 9 in the second brake circuit II is displaced. Subsequently, this process is reversed again by the pump in the second brake circuit in the phase range of 180 to 360 crank angle degree II displaced partial flow rate the separating piston 10 moved back by the same amount back, so in the present example that in the chamber 8th pressure medium over the backwater 5 in the direction of the first brake circuit I connected wheel brakes 18 flows. Thus, during operation of the conveyor 3 ensures that in each brake circuit I . II at a moderate pressure build-up a permanent volume flow pulsation-free each conveyor 3 leaves.

The 2 shows a longitudinal section through a structurally expedient embodiment of the separating piston assembly 1 , its separating piston 10 securely held in the center position, even if the closure (plug 26 ) should not be effective or present. The separating piston 10 is therefore fundamentally positioned with two opposing springs in a central position. The example as coil springs 29 designed springs serve to overcome the frictional force caused by the two asymmetric single-lip seals of the seal assembly 13 caused. To the seal assembly to be used 13 To make friction as possible, are preferred sealing materials based on PTFE instead of EPDM used

Consequently, those for basic positioning of the separating piston 10 required restoring forces and thus the spring restoring forces are kept low, so that the separating piston 10 characterized by a light response. The separating piston 10 and the seal assembly 13 are in a sleeve-shaped cartridge housing 12 received, which by means of a so-called. Clinch connection liquid-tight in the receiving body 25 the brake system is fixed.

The clinch connection is preferred only on the plug 26 facing side of the cross channel in the cartridge housing 12 leaking leakage connection 11 arranged, including the receiving housing 25 as well as the cartridge case 12 are provided with a step portion to press in the cartridge housing 12 in the receiving housing 25 that opposite the cartridge case 12 softer material of the receiving body 25 in at least one annular groove of the cartridge housing 12 to displace. Thus, in a rational manner a secure attachment and sealing of the separating piston assembly 1 opposite the leakage connection 11 and the two brake circuits I . II guaranteed.

On both sides are outside the seal assembly 13 in the cartridge housing 12 two cap-shaped piston stops 42 in the one with the two brake circuits I . II connected chambers 8th . 9 pressed. The piston stops 42 thus fix the seal assembly 13 in the cartridge case 12 and prevent slipping out of the separating piston 10 from the cartridge case 12 , It is thus permanently fixed and closed by a pre-assembled and testable isolating piston subassembly 1 through the stopper 26 By pressing into the receiving housing 25 at least in sections on the end faces of the cartridge housing 12 and the stopper 26 facing piston stop 42 comes to the plant. This is the stopper 26 analogous to the cartridge housing 12 designed as a clinch lid, which by plastic deformation of the soft bore material within the receiving body 25 in the direction of a stopper 26 circumferential groove the separating piston assembly 1 in the receiving body 25 closes.

The stopper 26 is thus liquid-tight in the receiving body 25 the brake system fixed. At the opposite end portion of the cartridge housing 12 provides a ring seal 45 for the necessary sealing of the Patonengehäuses 12 in the housing 25 , The both sides of the separating piston 10 in the chambers 8th . 9 arranged coil springs 29 are supported within the cap-shaped, preferably made of a light metal piston stops 42 of which at least the one on the side of the plug 26 provided piston stop 42 in the cartridge housing made of a steel 12 pressed or by means of a so-called. Selfclinch 46 is fixed.

For a leak-free sealing of the chambers 8th . 9 To make sure, are both the inner end surfaces of the two piston stops 42 as well as both faces of the finely honed separating piston 10 as sealing surfaces 38 designed in the sense of a metallic seal a flat, finely machined precision surface.

A poor sealing effect of all seals of the seal assembly 13 as well as a failure of one of the two brake circuits thus lead to an automatic sealing measure in the leakage region of the separating piston assembly 1 by the separating piston 10 , due to the leakage pressure loss in one of the two chambers 8th . 9 , differential pressure dependent with its sealing surface 38 against the same as a sealing surface 38 designed inner end face of the piston stop 42 is shifted, in the associated chamber area, the pressure loss has occurred.

Due to this simple yet reliable sealing measure due to the separating piston 10 and in the piston stop 42 trained sealing surfaces 38 can on the presented redundant seal arrangement 13 be dispensed with, which then the within only a single seal assembly 13 occurring piston friction significantly reduced, so consequently also the basic positioning of the separating piston 10 in the chambers 8th . 9 arranged two coil springs 29 can be omitted.

Furthermore, the shows 3 in a longitudinal section, deviating from the in 2 illustrated cartridge design, the isolation valve assembly 1 in dissolved construction, so that dispenses with a cartridge housing and the separating piston 10 directly with the seal assembly 13 in the stepped bore of the receiving housing 25 is used.

According to the 3 is located between the 2 already known sealing arrangement 13 a guide bush 47 for the separating piston 10 , which play free by means of one on the side of the plug 26 arranged cup-shaped piston stop 42 is fixed in the stepped bore, which preferably by means of a clinching force fit in the receiving body 25 is attached. Between the ground 30 of the receiving housing 25 and the separating piston 10 and between the bore in the receiving body 25 closing plug 26 and the separating piston 10 there is one coil spring each 29 for the center alignment of the separating piston 10 , with the advantage that in the absence of stuffing 26 which are usually at the stopper 26 supporting coil spring 29 through the generously sized opening 2 in the piston stop 42 from the receiving body 25 can escape unhindered, so that by the action of the opposite, at the bottom of the receiving body 25 supporting coil spring 29 the separating piston 10 against the inner end face of the piston stopper 42 is pressed, which analogous to 2 in 3 the end face of the separating piston 10 on the inner end face of the piston stop 42 impervious to liquid so that even if the seal assembly leaks 13 an escape of pressure medium from the intact brake circuit via the faulty seal assembly 13 towards the unsealed, on the outside of the receiving housing 25 arranged opening 2 is safely prevented.

In the above and based on the in 4 shown error case thus acts solely by the inner coil spring 29 applied separating piston 10 as a check valve that blocks the leakage in the direction of the atmosphere.

The 5 shows a longitudinal section through a structurally expedient embodiment of the separating piston assembly 1 , its separating piston 10 in Center position is positioned in a suitable sealing arrangement 13 is included. To the seal assembly to be used 13 To make friction as possible, are preferred sealing materials based on PTFE instead of EPDM used. By dispensing with the known from the previous illustrations coil springs 29 results in a slight Absprechverhalten the separating piston 10 ,

To achieve the simplest possible, mechanically tension-free positioning of the guide bushing 47 in the housing 25 to enable that is the separating piston 10 bearing guide bushing 47 positively in the receiving housing 25 held. For this purpose, the receiving housing 25 designed as a decreasing in the interior of the housing in diameter step bore, in the two end faces of the guide bushing 47 in each case an annular seal arrangement 13 is arranged, in which the separating piston 10 thus on both sides of the guide bush 47 opposite the two in the housing 25 integrated chambers 8th . 9 sealed is received.

For the simplest possible positive fixing of the guide bush 47 in the housing 25 is the guide bush 47 in the illustration on the left front side of one in the receiving housing 25 provided obliquely tapered hole stage 52 and on its other, right front side of a positive and / or non-positive in the receiving housing 25 attached, substantially cup-shaped fixing sleeve 42 axially contacted.

For lateral support of the left of the guide bush 47 positioned seal assembly 13 there is another step paragraph 46 to the left of the hole level 52 located so that with little axial play the left seal arrangement 13 between the left end of the guide bush 47 and the step heel 46 is arranged.

Advantageously, the piston stop comprises 42 the right seal assemblies 13 on the outer circumference directly, including in the piston stop 42 an annular circumferential recess 22 is provided, in which this seal arrangement 13 is used.

According to the chosen representation in 5 has the piston stop 42 on the outer circumference a circumferential groove 24 on, in during the insertion process of the piston stop 42 in the stepped bore adjacent material of the receiving housing 25 through a collar of the piston stop 42 is plastically displaced to a permanent attachment of the piston stopper 42 in receiving housing 25 to ensure the nature of a Selfclinch connection.

The separating piston assembly 1 is executed in all embodiments self-sealing, including the separating piston 10 on both faces with sealing surfaces 38 is provided, the differential pressure dependent, ie by a hydraulic actuation of both brake circuits I . II , on the housing side sealing surfaces 38 the separating piston assembly 1 can be applied.

To avoid a total brake circuit failure as a result of an unsealed receiving bore 25 the separating piston acts 10 during the activation of the brake system particularly advantageous as a check valve, including the separating piston 10 with its sealing surface 38 at the sealing surface 38 of the in the receiving bore 25 used piston stop 42 rests, if the the receiving bore 25 normally closing plugs 26 is missing. The piston stop 42 In this case of error, therefore, assumes the hermetic sealing effect of the plug 26 , so no brake fluid from the other, to the chamber 8th connected brake circuit I over the separating piston 10 can escape into the atmosphere when the brake circuit II sealing plugs 26 no longer fulfills its closing effect.

In the preferred construction of the piston stopper 42 this has a stopper contour whose sleeve edge remote from the stopper the guide bushing 47 contacted, wherein within the sleeve wall, the right-side seal assembly 13 for sealing the separating piston 10 is received while the thick-walled plug area of the piston stopper 42 a first check valve 48 receives, which counter to the action of a closing spring in the present example, a hydraulic connection within the piston stop 42 arranged chamber 9 with the outside of the piston stopper 42 into the isolation valve assembly 1 opening brake circuit II allows. A hydraulic connection is in the reverse direction due to the locking action of the first check valve exerted by the closing spring 48 locked out. In the present embodiment, the second brake circuit II to the chamber 9 to be able to connect, located in the plug area of the piston stop 42 a second check valve 49 that the brake circuit II against the action of a closing spring with the chamber 9 connects, while in the reverse direction, as a result of the locking action exerted by the closing action of the second check valve 49 , a hydraulic connection of the chamber 9 to the brake circuit II is excluded.

The hydraulic connection diagram of the chambers 8th . 9 to the brake circuits I . II corresponds to the above-described isolation valve assemblies 1 , where the representation after 5 analogous to the with the first brake circuit I connectable chamber 8th is fully transferable.

Both mutually oppositely effective check valves 48 . 49 are in a simple way in the piston stop 42 integrated as a valve pair, which in case of poor sealing effect of the seal assemblies 13 the two brake circuits I . II functionally separated from each other. Supported by the two closing springs prevents the valve pair in the unactuated state of the brake system, in the usually the separating piston 10 with its sealing surface 38 not on the housing side sealing surface 38 seals, a safe separation of both brake circuits I . II from each other, so in case of failure of one of the two brake circuits I . II the intact brake circuit does not have a poor sealing effect of the seal assemblies 13 can empty into the defective brake circuit.

How out 6 can be seen, the valve pair can be instead of after 5 in the piston stop 42 integrated construction alternative as a separate module 51 at a different location in the housing 25 arrange and via a hydraulic channel 50 to the separator valve assembly designed as a cartridge insert 1 connect in the above operation.

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 102013213640 A1 [0002]

Claims (14)

Brake system with means for controlling the brake pressure in two brake circuits, with a consisting of a master cylinder and a non-pressurized reservoir brake pressure transducer, with a brake in each brake circuit connecting the master cylinder with a wheel brake line receiving an intake valve, connected to a in each brake circuit to the wheel , a discharge valve having return line, which is connected to a low-pressure accumulator, and with a connected in each brake circuit on the low-pressure accumulator conveyor side, the pressure side upstream of the inlet valve to the brake line is connected, and with a pressure side of each conveyor hydraulically acted on separating piston assembly whose separating piston mutually is hydraulically acted upon by the conveying devices of both brake circuits, characterized in that the separating piston assembly ( 1 ) is designed self-sealing. Brake system according to claim 1, characterized in that the separating piston ( 10 ) at both end faces with sealing surfaces ( 38 ), the differential pressure dependent on the housing side sealing surfaces ( 38 ) of the separating piston assembly ( 1 ) can be applied. Brake system according to claim 2, characterized in that the housing-side sealing surfaces ( 38 ) a component of the inner end faces of two in a receiving housing ( 25 ) of the separating piston assembly ( 1 ) inserted piston stops ( 42 ), which are located on both sides of the separating piston ( 10 ) in chambers ( 8th . 9 ) are used, which at the two brake circuits ( I . II ) are connected. Brake system according to claim 3, characterized in that one of the chambers ( 8th . 9 ) in the housing ( 25 ) of the separating piston assembly ( 1 ) with a stopper ( 26 ) closed by one of the two brake circuits ( I . II ) is acted upon hydraulically. Brake system according to claim 4, characterized in that a plug ( 26 ) adjacent piston stop ( 42 ) from an opening ( 2 ) is penetrated centrally, the hydraulic loading of the plug ( 26 ) with the pressure in the at the plug ( 26 ) adjacent chamber ( 9 ). Brake system according to claim 1, characterized in that between the in a receiving bore ( 25 ) of the separating piston assembly ( 1 ) axially movable separating piston ( 10 ) and a receiving bore ( 25 ) closing plugs ( 26 ) a coil spring ( 29 ) is clamped. Brake system according to claim 6, characterized in that the helical spring ( 29 ) through an opening ( 2 ) one between the separating piston ( 10 ) and the plug ( 26 ) in the receiving bore ( 25 ) fixed piston stopper ( 42 ). Brake system according to claim 7, characterized in that diametrically to the coil spring ( 29 ) the separating piston ( 10 ) of another coil spring ( 29 ), which is on the ground ( 30 ) of the receiving bore ( 25 ) is supported. Brake system according to claim 8, characterized in that the bottom of the receiving bore ( 25 ) a housing-side sealing surface ( 38 ), on which the separating piston ( 10 ) with its sealing surface ( 38 ) can be applied. Brake system according to claim 1, characterized in that the separating piston ( 10 ) in conjunction with a at the bottom of the receiving bore ( 25 ) supporting coil spring ( 29 ) forms a check valve assembly, including the separating piston ( 10 ) with its sealing surface ( 38 ) on a sealing surface ( 38 ) one in the receiving bore ( 25 ) used piston stop ( 42 ) can be applied, one of the receiving bore ( 25 ) closing plugs ( 26 ) is directly upstream. Brake system according to claim 1, characterized in that the separating piston assembly ( 1 ) a valve pair ( 51 ), consisting of a first check valve ( 48 ) and one in the opposite direction to the first check valve ( 48 ) locking second check valve ( 49 ), both in their closed basic position one to the separating piston ( 10 ) adjacent chamber ( 9 ) of one with the chamber ( 9 ) connectable brake circuit ( II ). Brake system according to claim 11, characterized in that for the separation of the chamber ( 9 ) from the brake circuit ( II ) the two check valves ( 48 . 49 ) are acted upon by closing springs. Brake system according to claim 11, characterized in that both non-return valves ( 48 . 49 ) in a to the separating piston ( 10 ) in the housing ( 25 ) adjacent piston stop ( 42 ) arranged by a receiving housing ( 25 ) closing plugs ( 26 ) is limited. Brake system according to claim 11, characterized in that the valve pair as independently handleable and functionally pretestable assembly ( 51 ) away from the isolation valve assembly ( 1 ) in the housing ( 25 ) and via a hydraulic channel ( 50 ) with the isolation valve assembly ( 1 ) connected is.

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