EP3126200A1

EP3126200A1 - Damping device and slip-controllable vehicle brake system

Info

Publication number: EP3126200A1
Application number: EP15701999.3A
Authority: EP
Inventors: Bernd Haeusser; Oliver Gaertner; Horst Beling; Oliver Hennig; Michael Schuessler
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-04-03
Filing date: 2015-02-03
Publication date: 2017-02-08
Also published as: KR20160141730A; US20170106842A1; JP2017506598A; WO2015149972A1; CN106163890A

Abstract

The invention relates to a damping device (10), in particular for smoothing of pulsations of a pressure generator, preferably a piston pump of a slip-controllable vehicle brake system. Known damping devices (10) are supplied with pressure medium via an inlet (14) and an outlet (16) and have a first pressure chamber (20) filled with fluid and a second pressure chamber (24) filled with a compressible medium, preferably a gas. The two pressure chambers (20; 24) are separated from one another by a separating device (40). According to the invention a third pressure chamber (30) is proposed which is connected to the first pressure chamber (20) via a pressure medium connection (32) with built-in resistance (34). The separating device (40) is further modified for separating said third pressure chamber (30) from the second pressure chamber (24) and enables the second pressure chamber (24) to be acted upon by the pressure of the third pressure chamber (30). The invention enables an adaptation of the preload pressure in the second pressure chamber (24) to the current system pressure and causes the damping characteristics of the damping device (10) to behave largely independently with respect to the height of the pressure level of the inlet (14).

Description

description

title

Damping device and slip-controllable vehicle brake system prior art

The invention relates to a damping device according to the features of the preamble of claim 1 and a slip-controllable vehicle brake system according to the features of claim 8. Damping devices are particularly in slip-controlled

Vehicle brake systems used to reduce noise caused by pressure pulsations. Pressure pulsations arise, for example, by piston pumps, which are actuated as needed to adjust together with other actuators of the vehicle brake system, the brake pressure of a wheel brakes on the slip conditions of the wheel brake associated wheel.

In this case, the piston pumps carry out in a cyclic change suction strokes and delivery strokes, which trigger in the brake circuits of the vehicle brake system flow or pressure pulsations and can cause disturbing operating noise. Damping devices are ideally located in close proximity to the location of the formation of the pressure pulsations, e.g. near a pump outlet and an outlet valve of a piston pump, respectively. In particularly space-saving solutions, the damping devices are housed together with their associated piston pumps in common mounting holes of a hydraulic block of a hydraulic unit. such

Damping devices are disclosed e.g. DE 101 12 618 AI.

Some of these variants shown use an elastically deformable membrane, which has a fluid filled with a first pressure chamber over a gas-filled second pressure chamber seals. If pulsations occur, the membrane deviates towards the pressure space filled with compressible gas, so that the fluid-filled pressure chamber increases in volume and thus the pressure is increased

Pulsation smoothes. Downstream of the fluid-filled pressure chamber, a throttle is provided to counteract the fluid flowing out a hydraulic resistance.

The first pressure chamber, with the variable storage capacity, forms a so-called C-member, which is the hydraulic resistor, also referred to as R-member downstream. The R-element can be represented as a constant throttle or as a dynamic throttle, which provides a pressure-dependent variable resistor.

A dynamic throttle has the advantage of being able to operate at low pressures, such as those required for comfort functions, e.g. Distance controls, typically (about 40 bar), provide a strong throttle effect and thus high noise attenuation, while at pressures above about 40 bar, like them

especially in safety-related functions, such as. Blockage protection or slip control operations occur, a high flow or a low flow resistance allowed.

The lower the resistance of the throttle, the lower the

Pump operation necessary drive power and vice versa. The effective pressure range of the damping device is thus limited by the

Maximum power of the drive and the maximum storage capacity of the damping device. The latter is essentially determined by space restrictions of the hydraulic block.

A disadvantage of the known solutions is that the damping properties of the damping devices of the instantaneous system pressure of

connected brake system are dependent.

If this system pressure is higher than the pressure which underlayed the design of the diaphragm as well as its installation space, the diaphragm attaches itself to a mechanical stop and occurring pressure pulsations can not no more deflection of the membrane more effect and thus are no longer damped.

On the other hand, if the system pressure is significantly lower than the pressure when designing the damper device, the diaphragm behaves too stiff in the

Low-pressure range occurring pulsations to be able to dampen.

Advantages of the invention

Against this technical background, a damping device

proposed, which acts largely independent of the prevailing operating pressure.

Damping devices according to the features of claim 1 behave independently of the operating pressure and show almost constant

Damping properties over the entire pressure range of the system pressure. They are also characterized by the fact that they have no negative impact on the pressure build-up dynamics of the vehicle brake system, because they have little

Include pressure medium in itself, so have a low absorption volume. Despite particularly effective damping, especially in the low pressure range of the vehicle brake system, the promotion of relatively large

Pressure medium volume and thus a rapid pressure build-up in the event of unexpected emergency braking, such. for collision prevention or pedestrian protection, possible.

A damping device according to the invention has, in addition to the two existing pressure chambers, a third pressure chamber, which is coupled to the first fluid-filled pressure chamber via a fluid connection equipped with a hydraulic resistance. The separator separates the third pressure chamber from the second pressure chamber, but still allows the second pressure chamber can be acted upon by the pressure level of the third pressure chamber.

This constellation allows the second pressure chamber filled with compressible medium to be at the fluid pressure in the pressure chambers one and three and thus to apply the current system pressure. The separating device is equipped with a membrane which can assume a neutral position regardless of the level of the instantaneous system pressure, so that almost all of the mechanical stroke is available for damping pressure pulsations of the membrane. In terms of design, this stroke can be limited by end stops to which the diaphragm can engage if a certain pressure level is exceeded or undershot. About the end stops and the bias pressure in the second pressure chamber, the pulsation diaphragm stroke and thus the maximum absorption

Limit brake fluid through the damping device or set the pressure range within which takes place a damping or from which the effect of the damping device decreases.

Embodiments of the invention are illustrated in the drawings and explained in detail in the following description.

Show it:

1 shows a schematic representation of a one-stage damping device designed according to the invention;

FIG. 2: likewise a schematic illustration of an exemplary embodiment of a two-stage damping device; FIG.

Fig. 3: an alternative embodiment of a single-stage

Damping device and

4 shows a further embodiment of a single-stage damping device

Fig. 5: a illustrated with reference to a hydraulic circuit diagram Bremsreis with provided damping device. Disclosure of the invention

1 shows a first exemplary embodiment of a damping device 10 according to the invention. This is connected to a brake fluid-carrying line 12, which forms an outlet 14 upstream of the damping device 10 and a drain 16 downstream of the damping device.

Inflowing brake fluid first passes from the line 12 into a first pressure chamber 20 which is separated from a second pressure chamber 24 by an elastically deformable membrane 22. The second pressure chamber 24 is filled with a compressible medium, preferably a gas, said gas is under a biasing pressure, which biases the membrane 22. A stroke of this membrane 22 is in both spatial directions by mechanical

Limit stops 26, 28, which are each formed in one of the two pressure chambers 20, 24. If a pressure difference between the two pressure chambers 20, 24 exceeds or falls below a structurally definable order of magnitude, the membrane 22 abuts against one of the stops 26, 28 and is thereby protected against mechanical damage or overloading.

According to the invention, a third pressure chamber 30 is provided, which is contacted via a pressure medium connection 32 with the inlet 14 or with the first pressure chamber 20. The pressure medium connection 32 bypasses the second

Pressure medium chamber 24 and is filled as well as the first pressure chamber 20 with incompressible brake fluid. Downstream of its branch from the inlet 14, the fluid connection 32 is connected to a hydraulic resistance 34, e.g. equipped with a throttle or aperture. The third pressure chamber 30 encloses the second pressure chamber 24 both on its peripheral side and on one of its two end faces. For separating the different media of the second pressure chamber 24 and the third pressure chamber 30 is a cup-shaped

formed, elastically deformable hollow body damping element 36 is provided, which is exemplarily designed as a bellows element. This takes up the second pressure chamber 24 in its interior. Instead of a bellows element, for example, a bubble-shaped damping element could also be provided. The open end of the hollow body damping element 36 is at the mechanical Attached stop 26 for the membrane 22. This membrane 22 spans the second end face of the second pressure chamber 24. Membrane 22 and

Hollow body damping element 36 together form a separating device 40, which separates the second pressure chamber 24 from the first pressure chamber 20 and from the third pressure chamber 30 and yet allows the second pressure chamber 24 from the pressure of the third pressure chamber 30 and the pressure in the first pressure chamber 20 acted upon is.

The hydraulic pressure of the inlet 14 and the first pressure chamber 20 is via the pressure medium connection 32 with the built-hydraulic

Resistor 34 transmitted to the third pressure chamber 30 and acts on the cup-shaped, elastically deformable hollow body damping element 36 on the filled with compressible medium second pressure chamber 24 a. Depending on the respective pressure conditions thereby the membrane 22

applied pneumatic biasing pressure increased or decreased and adapted to the system pressure of the inlet 14. The diaphragm 22 therefore assumes a neutral position within its installation space, since the pneumatic forces acting on it from the second pressure chamber 24 essentially keep the counteracting hydraulic forces from the first pressure chamber 20 in equilibrium. The membrane 22 is therefore for damping of

Pressure fluctuations in both directions almost the entire constructive stroke available.

The second filled with compressible fluid pressure chamber 24 is therefore pressurized in two different ways, these routes differ in their throttle effect from each other. The first way is unthrottled. It comprises the first pressure chamber 20 and is bounded by the membrane 22.

Due to the mechanically limited stroke of the membrane 22, the first way can only the displacement or absorption of a small

Pressure medium volume in the first pressure chamber 20 to.

The second way is throttled and includes the pressure medium connection 32 with the built-hydraulic resistance 34 and the third coupled thereto and bounded by the elastic hollow body damping element 36

Pressure medium chamber 30. The volume of the second path may be due to the Deformability of the hollow body damping element 36 change to a much greater extent than the volume of the first pressure chamber 20, whereby this second way can accommodate a large volume of pressure medium.

High-frequency or rapid pressure fluctuations do not propagate directly into the third pressure chamber 30 due to the hydraulic resistance 34 of the pressure medium connection 32 or only with a time delay. such

Pulsations first propagate into the first pressure chamber 20, where they cause the deflection of the membrane 22 and are effectively damped by the elasticity of the volume contained in the second pressure chamber 24 compressible medium. The damping thus takes place on the unthrottled first path and the damping device 10 extracts the entire system only a relatively small volume of hydraulic pressure fluid, thus showing a low absorption capacity. Despite effective damping measures, the connected hydraulic system thus has almost the entire amount of hydraulic pressure fluid available, thus ensuring that

Vehicle brake system a sufficiently good pressure build-up dynamics for unexpected emergency braking situations.

About the throttled second way the pneumatic biasing force of the diaphragm 22 can be adjusted to the system pressure in the inlet 14. The necessary shift of a larger amount of brake fluid into the third pressure chamber 30, is possible via the above-explained second way. Since this second path is provided with a hydraulic resistor 34, the adaptation to the changed pressure in the inlet 14, however, can only take place with a time delay. The adjustment of the pneumatic biasing force of the diaphragm 22 to the pressure in the inlet 14 allows pressure pulsations occurring after pressure adjustment to be damped as well, without the need to shift large amounts of pressure fluid, which are then no longer available to the rest of the vehicle braking system. for braking maneuvers in which it depends on a high pressure build-up dynamics, so a large amount of available pressure medium.

The second embodiment of the invention of Figure 2 is basically the same structure and also works as related to Embodiment 1 described, but differs from this in that the separator 40 in addition to the membrane 22 and the

Hollow element damping element 36 still with a second membrane 42

is equipped, which shuts off the first pressure chamber 20 to the surrounding atmosphere. The second diaphragm 42 separates a fourth pressure chamber 44 connected to the first pressure chamber 20 with an integrated mechanical stop 46 from a fifth pressure chamber 48 connected to the atmosphere. The first pressure chamber 20 and the fourth pressure chamber 44 are opposite each other and can also be combined to form a single pressure chamber connected to the inlet 14 and the outlet 16.

The second diaphragm 42 is provided because the first diaphragm 22 is only able to damp pressure oscillations which are above the prevailing in the second pressure chamber 24 pneumatic biasing pressure, since only such pressure oscillations can cause a deflection of the first membrane 22 at all. The second membrane 42 is therefore designed in its material and / or in its elasticity and / or in their dimensions so that it abuts exactly at its associated mechanical stop 46 when the brake fluid of the first pressure chamber 20 just below the biasing pressure of the second Pressure chamber 24 is. If a pulsation vibration occurring in the first pressure chamber 20 causes a lower pressure, a deflection of the second diaphragm 42 in the direction toward the atmosphere and can thus also be damped.

In the third embodiment of Figure 3, the second pressure chamber 24 is not filled with compressible medium but with the same hydraulic fluid as the first pressure chamber 20, while in the third pressure chamber 30 now no brake fluid, but compressible medium, preferably a gas is under biasing pressure , The membrane 22 of the separator 40 thus no longer has the task of separating two media from each other and can therefore be provided with a throttle or a diaphragm, via which a

Fluid exchange between the first pressure chamber 20 and the second

Pressure chamber 24 can take place. So the throttle allows one

Pressure equalization between the two pressure chambers 20 and 24 and corresponds thus functionally the hydraulic resistance 34 in the pressure medium connection 32 of the first embodiment (Figure 1). Pressure fluid displacements to a greater extent are taken up here by the second pressure chamber 24, which is located inside the elastic hollow body damping element 36, also exemplified in the form of a bellows element.

Advantageously, by the mutual exchange of the media of the second pressure chamber 24 and the third pressure chamber 30 relative to the

Embodiment of Figure 1 now in this third

Embodiment of Figure 3 on a separately trained

Pressure medium connection can be omitted, which saves in particular space and processing costs for the realization of the damping device 10 on a housing block of a hydraulic unit. The separator 40 comprises an open and elastically deformable unchanged

Hollow body damping element 36, preferably in the form of a bellows for separating the second pressure chamber 24 from the third pressure chamber 30th

However, here is the third pressure chamber 30 filled with compressible medium, preferably gas, under biasing pressure. This preload pressure is user-specific selectable and clamped at this third

Embodiment no longer the membrane 22 of the separator 40, but rather the hollow body damping element 36 before.

In their operation, the embodiments of Figures 1 and 3 are identical, so that in this regard to the relevant embodiments in

Connection with Figure 1 can be referenced.

FIG. 4 shows the embodiment according to FIG. 1, but with the modification that the brake-fluid-carrying line 12, to which the damping device 10 is connected, is no longer continuous, but is divided into an inlet 14 and an outlet 16 separated therefrom and drain 16 open into the first pressure chamber 20 in a spatially separated manner and are aligned substantially perpendicular to the direction of extension of the membrane 22. Such an orientation of the incoming or outgoing

Pressure medium favors the damping effect of the membrane 22. From each other separate and perpendicular to the direction of extension of the membrane 22nd

aligned inlets 14 or drains 16 can be transferred to all three embodiments described above.

Finally, FIG. 5 also shows a hydraulic circuit diagram of a brake circuit 50 of a vehicle brake system, which is equipped with one of the damping devices 10 described above. Shown is an example of the damping device 10 according to the embodiment of Figure 1.

The illustrated brake circuit 50 is operable by a driver

Master cylinder 52 is connected and includes a wheel brake 54. A pressure medium connection from the master cylinder 52 to the wheel brake 54 can be blocked by an electronically controllable switching valve 56, if one

Separation of the master cylinder 52 and thus the driver of the

Wheel brake 54 should be necessary. Downstream of the changeover valve 56, an inlet valve 58 is also arranged in the brake circuit 50, which, together with an exhaust valve 60 also connected to the wheel brake 54, enables a modulation of the pressure in the wheel brake 54.

From the wheel brake 54 effluent pressure fluid flows to a pressure generator 62, preferably a piston pump, which is driven by a drive motor 64. The pressure generator 62 conveys pressure fluid from the wheel brake 54 via the damping device 10 according to the invention back into the brake circuit 50, wherein the discharge point in the brake circuit 50 between the

Switching valve 56 and the inlet valve 58 is located.

If the amount of pressure medium that can be conveyed out of the wheel brake 54 is insufficient, e.g. the pressure in the wheel brake 54 to raise to a required pressure level, the pressure generator 62 via a

High-pressure switching valve 66 are connected directly to the master cylinder 52 and can then suck pressure generator 62 directly from the master cylinder 52.

All of the illustrated valves 56, 58, 60, 66 are a 2/2-way valves which can be switched electromagnetically between a passage and a blocking position. It is possible, in particular for the valves 56 and / or 66 to perform these as proportional valves so that they can take any intermediate positions.

Apart from the master cylinder 52 and the wheel brake 54 are all other components of the described brake circuit 50 at one

Hydraulic block of a hydraulic unit of a vehicle brake system arranged. The hydraulic block is provided with holes that

Make recordings for these components. Such a hydraulic block can be formed or equipped in a particularly space-saving and cost-saving manner when the pressure generator 62 with the damping device 10 is arranged in a common receptacle of the hydraulic block.

Of course, further changes to the described

Embodiments possible without that in the claims

to depart from the basic principles of the invention.

Claims

claims

1. damping device, in particular for smoothing pressure pulsations of a

Pressure generator, preferably a piston pump a slip-controlled

Vehicle brake system, with an inlet (14) and a drain (16) for supplying the damping device (10) with pressure medium, with a with the inlet (14) and with the outlet (16) connected to the first pressure chamber (20) and one with a compressible Medium, preferably a gas, filled second pressure chamber (24) and with a separating device (40) between the first pressure chamber (20) and the second pressure chamber (24), characterized in that a third

Pressure chamber (30) is provided, which is connected via a pressure medium connection (32) with built-in resistor (34), preferably a throttle or orifice, with the first pressure chamber (20) and that the separating device (40) is further developed to separate the third Pressure chamber (30) opposite the second pressure chamber (24) and an admission of the second pressure chamber (24) with the pressure of the third pressure chamber (30).

2. damping device according to claim 1, characterized

in that the separating device (40) is equipped with at least one elastically deformable membrane (22).

3. Damping device according to claim 1 or 2, characterized

in that the separating device (40) has an elastically deformable,

Hollow body damping element (36), preferably a bellows member having.

4. damping device according to claim 2 or 3, characterized

in that the separating device (40) has at least one mechanical stop (26; 28; 46) for the membrane (22).

5. Damping device according to one of claims 2 to 4, characterized in that the separating device (40) has a second diaphragm (42) which shuts off the first pressure chamber (20) to the atmosphere.

6. Damping device according to one of claims 1 to 5, characterized in that the inlet (14) and the outlet (16) spatially spaced from each other in the first pressure chamber (20) open.

7. damping device according to claim 6, characterized

in that the inlet (14) and the outlet (16) open into the first pressure chamber (20) substantially perpendicular to the direction of extension of the membrane (22) of the separating device (40).

8. slip-controllable vehicle brake system having at least one, a wheel brake (54) and a pressure generator (62) having brake circuit (50) equipped with at least one damping device (10) according to one of claims 1 to 7, which is the hydraulic pressure generator (62) downstream ,

9. slip-controllable vehicle brake system according to claim 8, with a one

Housing block having hydraulic unit, wherein the housing block

Components of the brake circuit (50) receiving receptacles are formed and wherein the pressure generator (62) and the damping device (10) are arranged in a common receptacle.