Pressure equalising device

Abstract

The invention relates to a pressure equalising device (1), in particular for a braking system of a motor vehicle, comprising a pressure chamber (2) which has at least one opening (13) closed by a gas-permeable membrane (14). According to the invention, the pressure chamber (2) has a valve opening (22) which is associated with a movable valve element (8) that is held in a closed position and can be moved into a release position in which a fluid connection from the pressure chamber (2) to the surroundings is established, and the movable valve element (8) has the opening (13) and carries the membrane (14).

Description

[0001] R.411020

[0002] - 1 -

[0003] Description

[0004] title

[0005] Pressure equalization device

[0006] The present invention relates to a pressure equalization device, in particular for a braking system of a motor vehicle, with a pressure chamber having at least one opening which is closed by a gas-permeable membrane.

[0007] State of the art

[0008] Pressure equalization devices of the type mentioned above are already known from the prior art. For example, pressure equalization devices are frequently used in motor vehicle braking systems in the form of bursting throttles or diaphragm valves. The latter, in particular, allow pressure equalization through a gas-permeable diaphragm that seals a pressure chamber or a pressure accumulator. As a rule, such pressure equalization devices are only designed for very high pressures due to their design and overall size, or are technically very complex.

[0009] As a result, they require a relatively large amount of installation space and are not necessarily suitable for use in sensitive areas. Furthermore, known pressure equalization devices have the disadvantage that if the device containing the pressure equalization mechanism is submerged underwater, liquid can enter the pressure chamber after some time.

[0010] Disclosure of the invention

[0011] The pressure equalization device according to the invention with the features of claim 1 has the advantage that, firstly, it is also suitable for very low pressures, and secondly, it meets particularly high requirements. R.411020

[0012] - 2 -

[0013] Tightness is guaranteed even when considering potential leaks, while keeping overall costs low.

[0014] The pressure equalization device according to the invention ensures, firstly, advantageous gas exchange through the membrane, and secondly, in the event that liquid enters the pressure chamber, it also ensures the reliable escape of the liquid, particularly when a predefinable limit pressure is exceeded, without damaging the membrane. According to the invention, the pressure chamber has a valve opening to which a movable valve element is assigned. This element is held in a closed position and can be moved into a release position, in which a fluid connection from the pressure chamber to the outside or to the environment of the pressure equalization device is established. The movable valve element has the opening and supports the membrane.According to the invention, the diaphragm is arranged on a movable valve element, which also has the opening that provides the connection from the pressure chamber to the environment of the pressure equalization device. In addition to the diaphragm, the movable valve element allows for a fluid connection between the pressure chamber and the environment of the pressure equalization device, or, when the valve element is moved into the release position, this connection is established. This allows fluid to escape from the pressure chamber without damaging the diaphragm. Normally, the valve element is held in the closed position, ensuring pressure equalization through the diaphragm via gas exchange. Only in emergencies, for example, if fluid has accumulated in the pressure chamber and a limit pressure is exceeded, does this lead to the valve element moving into the release position with the consequence described above.

[0015] Preferably, the pressure chamber has a base with a hollow cylindrical projection forming the valve opening, which projects particularly into the pressure chamber and in or on which the valve element is held. The hollow cylindrical projection provides an advantageous mounting and arrangement of the valve element on the base. The hollow cylindrical projection preferably provides the valve element with R.411020

[0016] - 3 -

[0017] A longitudinal guide is provided that defines the orientation and displacement of the valve element relative to the pressure chamber or the base. Preferably, the projection is integral with the base, for example as a stamped and bent part or as a plastic component, in particular an injection-molded part.

[0018] Furthermore, it is preferably provided that the valve element is held in the closed position by static friction or by force-fit. For example, the valve element is pressed into the closed position so that it is held against or within the hollow cylindrical projection by static friction. The valve element preferably interacts directly with the projection, or another element is arranged between the projection and the valve element to increase the static friction. Preferably, an elastically deformable element is used for this purpose, ensuring an increased pressing force of the valve element and thus increased static friction.

[0019] Preferably, the valve element has at least one retaining means that interacts, in particular with the base in the release position, to securely hold the valve element on the projection or pressure chamber. The retaining means provides a positive-locking connection between the valve element and the base, ensuring that, in the event of pressure equalization, when the valve element is moved from the closed position to the release position, it remains attached to the pressure chamber or base and cannot completely detach from the rest of the pressure equalization device. This ensures that the valve element, for example, does not fall into the device containing the pressure equalization device and potentially damage other components of the device.

[0020] The valve element preferably has at least one elastically deformable locking lug that forms the retention element. The elastically deformable locking lug allows the valve element to be mounted on the pressure chamber, particularly on the bottom of the pressure chamber, without requiring increased force. For example, when inserting the R.411020

[0021] - 4 -

[0022] The locking lug of the valve element is pressed elastically inwards into the hollow cylindrical projection, in order to spring back laterally outwards again due to its own elasticity after passing through the projection and thereby engage the projection in a form-fitting manner.

[0023] According to a preferred embodiment of the invention, at least one elastically deformed or deformable sealing element, in particular an O-ring, is clamped laterally or radially between the valve element and the base or projection. As mentioned above, this results in improved static friction and thus secure retention of the valve element in the closed position.

[0024] According to a preferred embodiment of the invention, the diaphragm is arranged at the end of the valve element facing into the pressure chamber or at the end of the valve element facing away from the pressure chamber. In either case, the diaphragm covers the opening extending through the valve element.

[0025] Furthermore, the valve element preferably has an open-ended bypass channel that is closed in the closed position and opens into the environment of the pressure equalization device in the released position. The bypass channel extends, in particular, in a groove-like fashion along an outer surface of the valve element to provide the fluid connection from the pressure chamber to the environment in the released position.

[0026] Preferably, the valve element has a projection at one end of the bypass channel that rests against the sealing element and / or the base in the closed position and is spaced apart from it in the open position. The projection thus closes the bypass channel in the closed position of the valve element and opens it in the open position. Optionally, the valve element has several bypass channels arranged around its circumference, each configured like the bypass channel described above.

[0027] Particularly preferably, the valve element has a bypass channel that is closed, especially on its circumference, and extends through the valve element. R.411020

[0028] - 5 -

[0029] The bypass channel extends, in particular parallel to the opening to which the diaphragm is assigned, with at least one valve, in particular a check valve, being assigned to the bypass channel. This embodiment has the particular advantage that the pressure equalization device can be reused even after fluid pressure equalization.

[0030] The invention will now be explained in more detail with reference to the drawing. To this end, we show

[0031] Figures 1 A and B show a first embodiment of the pressure equalization device in different operating states,

[0032] Figures 2A and B show a second embodiment of the pressure equalization device in different operating states.

[0033] Figures 3A and B show a third embodiment of the pressure equalization device in different operating states.

[0034] Figure 4 shows a fourth embodiment of the pressure equalization device and

[0035] Figure 5 shows a fifth embodiment of the pressure equalization device.

[0036] Figures 1 A and B each show in a simplified sectional view an advantageous pressure equalization device 1 in different operating states according to a first embodiment.

[0037] The pressure equalization device 1 has a pressure chamber 2 formed by a cup-shaped housing 3 and a base 4 closing the housing 3. The base 4 is sealed to the free end face of the housing 3, in particular by welding or bonding. The base 4 has a centrally located hollow cylindrical projection 5, which, according to the present R.411020

[0038] - 6 -

[0039] In an exemplary embodiment, the hollow cylindrical projection 5 is defined as having a step, such that it comprises a first section 6 with a first diameter and a second section 7 with a second diameter. In this case, the section 7 with the second diameter, which is located further back in the housing 3, has a smaller diameter than the section 6, which is closer to the base 4. Due to its hollow cylindrical shape, the projection 7 forms a valve opening 22, which connects the pressure chamber 2, for example, to the surroundings of the pressure equalization device or to a connection of a brake system or a component of the brake system.

[0040] Furthermore, the pressure equalization device 1 has a valve element 8 that is held and guided in the valve opening 22 of the projection 7. The valve element 8 is hollow and cylindrical, with a radially projecting collar 9 or 10 at each end face. These collars 9 and 10 each form a retaining element 11 that radially engages the projection 5 at the ends of the section 7, thereby securing the valve element 8 to the base 4. The retaining elements 11 are axially spaced further apart than the length of the section 7, allowing the valve element 8 limited longitudinal displacement relative to the projection 5.

[0041] The valve element 8 is preferably pressed into the projection 5 to hold it in a closed position, as shown in Figure 1A. For this purpose, a sealing element 12 is radially clamped, in particular elastically deformed, between the valve element 8 and the projection 5. The sealing element 12 is, for example, attached to the valve element 8 or to the projection 5. It serves, on the one hand, to retain the valve element 8 in the projection 5 and, on the other hand, to ensure that the valve element 8 seals against the projection 5 at its edges.

[0042] An opening 13, designed as a through-channel, extends through the valve element 8, particularly centrally. A diaphragm 14 is associated with the opening 13 on one of its end faces, in this case, the end face of the valve element 8 located outside the pressure chamber 2, and completely covers the opening 13. The diaphragm 14 is designed to be gas-permeable, allowing gas exchange between the R.411020

[0043] - 7 -

[0044] Pressure chamber 2 and the surrounding area of ​​the pressure equalization device 1 can be used for pressure equalization.

[0045] Furthermore, the valve element 8 has at least one bypass channel 15 on its outer surface, extending from the end of the valve element 8 located in the pressure chamber 2 to a radially projecting projection 21 on which the sealing element 12 is arranged. The bypass channel 15 is thus only in fluid communication with the pressure chamber 2 when the valve element 8 is in the closed position, as shown in Figure 1A. In the closed position, the valve element 8 is held in place by friction between the valve element 8, the sealing element 12, and / or the projection 5.

[0046] If an overpressure arises in the pressure chamber 2 that exceeds a predetermined limit, in particular the existing static friction, the valve element 8 is forced outwards and thereby reaches a release position as shown in Figure 1B. In the release position, the valve element 8 rests with the upper retaining element 11 against the inner end face of the projection 5. The bypass also extends the upper retaining element 11 into the pressure chamber, and the projection 21 is now spaced apart from the section 7 of the projection 5, so that the bypass channel 15 is now in fluid communication with both the pressure chamber 2 and the surroundings of the pressure equalization device 1. Thus, additional pressure equalization can take place.

[0047] In particular, fluid exchange with the environment can also take place via bypass channel 15.

[0048] The valve element 8 is advantageously made of plastic, and the diaphragm 14 is made of, for example, plastic or ceramic. The diaphragm ensures the watertightness of the pressure equalization device under normal conditions. The movable valve element 8 provides a draining function in the event of a malfunction. Optionally, the base 4 and the housing 3 are also made of plastic. The sealing element 12 is preferably an O-ring or an injection-molded seal, in particular an LSR seal. R.411020

[0049] - 8 -

[0050] The further embodiments of the pressure equalization device 1, which are explained below with reference to Figures 2 to 5, differ in details from the first embodiment. Elements already known from the first embodiment are designated with the same reference numerals below, so reference is made to the description above. The following discussion will focus primarily on the differences.

[0051] According to the second embodiment of the pressure equalization device 1 shown in Figures 2A and B, the projection 5 has a reversed arrangement of sections 6 and 7, such that section 6 with the larger diameter is now on the inside and section 7 with the smaller diameter is on the outside, and the diaphragm 14 is arranged on the inner end face of the valve element 8 to close the opening 13. Furthermore, in this case, the sealing element 12 is preferably held on the projection 5 so that the valve element 8 is movable relative to it. The valve element 8 now lacks the external retaining element 11, but otherwise it corresponds at least substantially to the valve element 8 from Figures 1A and B. However, its operation is the same as that of the first embodiment.

[0052] Figures 3A and 3B show a third embodiment of the pressure equalization device 1, also in the closed and released positions of the valve element 8, wherein, in contrast to the previous embodiment, the valve element 8 is not arranged in the hollow cylindrical projection 5, but rather surrounds it and is thus pushed onto the projection 5. Accordingly, the bypass channel 15 is also formed on the inside of the valve element 8, and the sealing element 12 is clamped between the outside of the projection 5 and the inside of the valve element 8.

[0053] The fourth embodiment in Figure 4 shows a further development of the third embodiment, wherein the valve element is shown in the closed position in Figure 4. In the further development of the embodiment of Figures 3A and B, according to the fourth embodiment, the valve element 8 has an internal projection 16 through which the opening R.411020

[0054] - 9 -

[0055] The valve element 8 extends through section 13 and has outwardly projecting locking lugs 17 at its free end, which lies beyond the inner section 7 of the projection 5. These lugs can be displaced inwards by elastic deformation. This allows the valve element 8 with the projection 16 to be easily inserted into the projection 5. The locking lugs 17 then deform elastically, and after penetrating section 7 of the projection 5, their inherent elasticity causes them to push outwards again, thus axially engaging the projection 5 at its distance 7 in a form-fitting manner. This securely holds the valve element 8 to the projection 5.

[0056] Figure 5 shows a further embodiment, which differs from the first embodiment according to Figures 1 A and B, in particular in that the valve element 8 has a further bypass channel 18 that extends through the valve element 8 parallel to the opening 13 and has a check valve 19 at its outer end. The check valve 19 has a valve body 20 that is spring-loaded and forced into a closed position, and is only moved into an open position when the pressure in pressure chamber 2 exceeds a predetermined limit value. In this case, the pressure equalization device 1 is designed to be reversible because continued operation of the pressure equalization device 1 is reliably ensured even after a fluid exchange by opening the check valve 19. In this case, the valve element 8 is preferably fixedly attached to the base 4 or to the projection 5.

Claims

R.411020 - 10 - Claims 1. Pressure equalization device (1), in particular for a braking system of a motor vehicle, with a pressure chamber (2) which has at least one opening (13) which is closed by a gas-permeable membrane (14), characterized in that the pressure chamber (2) has a valve opening (22) to which a movable valve element (8) is assigned, which is held in a closed position and can be moved into a release position in which a fluid connection from the pressure chamber (2) to the environment is established, and that the movable valve element (8) has the opening (13) and carries the membrane (14).

2. Pressure equalization device according to claim 1, characterized in that the pressure chamber (2) has a bottom (4) which has a hollow cylindrical projection (5) forming the valve opening (22), which in particular projects into the pressure chamber (2), and in or on which the valve element (8) is held.

3. Pressure equalization device according to one of the preceding claims, characterized in that the valve element (8) is held in the closed position by frictional engagement.

4. Pressure equalization device according to one of the preceding claims, characterized in that the valve element (8) has at least one retaining means (11) which in particular interacts with the base (4) in the release position to hold the valve element (8) securely on the projection (5).

5. Pressure equalization device according to claim 4, characterized in that the valve element (8) has at least one elastically deformable locking lug (17) which forms the retaining means (11).

6. Pressure equalization device according to one of the preceding claims, characterized in that between the valve element (8) and the R.411020 - 11 - Projection (5) at least one elastically deformed or deformable sealing element (12), in particular an O-ring, is held under tension.

7. Pressure equalization device according to one of the preceding claims, characterized in that the diaphragm (14) is arranged at the end of the valve element (8) pointing into the pressure chamber (2) or at the end of the valve element (8) pointing away from the pressure chamber (2).

8. Pressure equalization device according to one of the preceding claims, characterized in that the valve element (8) preferably has an open-ended bypass channel (15) which is closed in the closed position and opens into the environment in the release position.

9. Pressure equalization device according to one of the preceding claims, characterized in that the valve element (8) has a projection (21) at one end of the bypass channel (15) which, in the closed position, rests against the sealing element (12) and / or against the projection (5) and is spaced apart from it in the release position.

10. Pressure equalization device according to one of the preceding claims, characterized in that the valve element (8) has a bypass channel (18) which is closed on the circumferential side and extends through the valve element (8), wherein at least one automatic valve, in particular a check valve (19), is assigned to the bypass channel (18).

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