DE20010608U1 - Device for limiting the pressure in a pressure space filled with gas or liquid - Google Patents

Description

Title: Device for limiting the pressure in a pressure chamber filled with gas or liquid

The invention relates to a device for limiting the pressure in a pressure chamber filled with gas or liquid to values below a critical pressure value.

An example of a pressure chamber that must be protected from excess pressure is the crankcase of the combustion engine of a truck. In the event of engine failure, the pressure in the crankcase can suddenly rise above a critical value. This increase in pressure can then, for example, destroy the oil pan connected to the crankcase, particularly if the oil pan is made of plastic. As a result, large amounts of oil are released into the environment in an uncontrolled manner.

The object of the invention is to provide a device with which the pressure in a pressure chamber filled with gas or liquid can be safely limited to values below a critical pressure value.

The invention proposes providing a pressure equalization channel for the pressure limiting device between the pressure chamber filled with gas or liquid, e.g. a crankcase, and a second pressure area, e.g. the atmosphere. A control body is arranged in the pressure equalization channel, which is subjected to the pressure in the pressure chamber and at least almost completely closes the flow cross-section in the pressure equalization channel at pressures below the critical pressure value. As a result of the pressure being applied, in particular as a result of rapid pressure increases, the control body is axially displaced against the effect of an inhibiting force in the pressure equalization channel. According to the invention, a spring is arranged in the pressure equalization channel, which is axially pre-tensioned via tensioning means. The device now develops the effect according to the invention when the pre-tensioned spring is relaxed by the relaxation means after a predetermined axial displacement path when the critical pressure value is reached, whereby the force inhibiting the axial displacement of the control body is overcome as a result of the spring relaxation and the control body thus releases the flow cross-section for pressure equalization. The control body is then preferably completely pressed out of the pressure equalization channel by the pressure application.

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According to the invention, the entire cross-section of the pressure equalization channel is suddenly released and in this way the pressure in the pressure chamber is reduced before damage can occur. The cross-section of the pressure equalization channel is selected to be as large as possible so that there is little flow resistance in order to be able to quickly discharge the pressurized medium (gas or liquid). A large cross-section of the pressure equalization channel is particularly important when the pressure chamber has a relatively large volume, as is the case with the crankcase of a commercial vehicle, for example, since in this case the amount of gas to be discharged is also relatively large.

According to the invention, the critical pressure is not used directly to release the pressure equalization channel, but rather is used via the control body to generate a control force, which then releases a much greater impact force of the pre-tensioned spring. The critical pressure value at which the pre-tensioned spring is to be suddenly released is determined by the design of the inhibiting force means that counteracts the axial displacement of the control body, and by the size of the area of the control body that is subject to flow. A second pre-tensioned spring is preferably used for the force means that inhibits the axial displacement of the control body, but this is softer than the first spring. At pressures below the critical pressure value, the second spring thus reliably prevents the control body from being moved into the area where the first spring is released.

Of course, depending on the embodiment, the device according to the invention can be used both for overpressure limitation, as in the case of the crankcase, and for underpressure limitation.

In one embodiment, the pressure equalization channel with its housing is part of a component that is connected to the pressure chamber filled with gas or liquid. This component can be, for example, an oil filter housing that is flanged to the pressure chamber formed by the crankcase. By integrating it into such a component, otherwise necessary structural changes to the pressure chamber are no longer necessary.

In addition, however, it is also intended to design the pressure equalization channel as a separate component that can be connected to the pressure chamber (e.g. via a flange connection). This has the advantage that the device according to the invention can be manufactured and sold as an independent pressure limiting device.

In a further embodiment, the pressure equalization channel is part of the pressure chamber filled with gas or liquid. In this way, the pressure limiting device according to the invention can be integrated into the pressure chamber by the manufacturer of the pressure chamber during its manufacture.

In all embodiments, the installation position (orientation in space) of the pressure limiting device according to the invention is arbitrary.

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The invention will be explained in more detail below with reference to the attached drawing. It shows:

Fig. 1 shows a section through a first embodiment of the device according to the invention, Fig. 2 shows a section through a second embodiment of the device according to the invention, Fig. 3 shows a side view of the control body with the two springs, Fig. 4 shows a perspective view of the control body with the two springs, Fig. 5 shows a perspective view of the control body with the clamping cage, wherein the webs of the

clamping cage have predetermined bending lines,
Fig.6 is a perspective view of the control body with the clamping cage, where the webs of the

Clamping cage have support tabs,
Fig.7 is a top view of the pressure equalization channel with grooves for receiving the webs of the clamping cage.

Figure 1 shows a first embodiment of the pressure limiting device. The pressure equalization channel (1) between the pressure chamber to be protected (pressure range p) and the second pressure range (atmosphere, po) is formed by a cylindrical housing (14). A control body (2) is arranged in the pressure equalization channel (14), which at least almost completely closes the flow cross-section of the pressure equalization channel (1) at pressures below the critical pressure value. In the embodiment shown here, the control body (2) is designed as a plate or small piece made of plastic or metal (sheet metal). As a result of the pressure being applied, the control body (2) can be axially displaced in the pressure equalization channel (1) against the effect of an inhibiting force means (4). In addition, a spring (3) is arranged in the pressure equalization channel (1), which is axially pre-tensioned via tensioning means (5). When the critical pressure value is reached, the control body (2) has covered a predetermined axial displacement path. In this position of the control body (2), the pre-tensioned spring (3) is relaxed by a relaxation device (16). As a result of the spring relaxation, the force inhibiting the axial displacement of the control body (2) is overcome. The excess pressure can now act unhindered on the control body (2) and push it out of the pressure compensation channel (1). This releases the flow cross-section for pressure compensation.

The pre-tensioned spring (3) and the tensioning device (5) for this spring (3) can be moved axially with the control body (2). A helical spring is preferably used for this pre-tensioned spring (3). However, another type of spring can also be used, e.g. a gas pressure spring.

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The force means (4) which inhibits the axial displacement of the control body (2) is formed by a second spring (4) which is supported against the control body (2) and which, with its

(2) is supported under pre-tension on a cover (6) which closes the pressure equalization channel (1) as a stop element (6). To limit the pressure, the relaxing 1st spring (3) pushes the cover (6) supporting the 2nd spring (4) away from the pressure equalization channel (1), so that the 2nd spring (4) is also relaxed. This overcomes the obstacle to the axial displacement of the control body (2), so that the control body (2) releases the flow cross-section for pressure equalization by pressing the control body (2) itself out of the pressure equalization channel (1).

In the case of pressures or pressure fluctuations below the critical pressure value, the 2nd spring (4) ensures that the control body (2) is not displaced into the area where the 1st spring (3) is relaxed. Within this non-critical displacement path, the preload of the 1st spring is

(3) not changed.

In the embodiment shown here, the control body does not completely seal the pressure equalization channel (1) from the pressure chamber (p). Rather, the control body (2) is guided in the pressure equalization channel (1) with a tolerance gap between the inner wall (10) of the pressure equalization channel (1) and the control body (2). This gap enables pressure equalization for slow pressure changes between the pressure chamber and the space behind the control body (i.e. the space between the control body and the cover). Due to this pressure equalization, slow pressure changes do not lead to a displacement of the control body (2). However, with rapid pressure changes, pressure equalization is not possible due to the flow resistance formed by the control body (2), so that the desired displacement of the control body (2) is brought about. In addition to the tolerance gap mentioned above, there can also be another opening in the control body (2).

The clamping means (5) for the first spring (3) has a support element (50) for the spring (3) that is radially movable transversely to the direction of displacement of the control body (2) and that can be axially displaced in the pressure compensation channel (1) with the control body (2). In the embodiment shown here, the clamping means (5) is designed as a clamping cage consisting of two or more radially resilient webs (51) with radially inwardly bent retaining lugs as support elements (50). Instead of resilient webs (51), webs that can be pressed radially outwards can also be used.

The radial expansion of the clamping cage (5) is automatically caused by the axially pre-tensioned 1 .spring (3), which presses against the slopes of the support elements (50).

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In the support position, the retaining lugs (50) in a first section (11) of the pressure equalization channel (1) are pressed against the inner wall (10) of the pressure equalization channel (1), with the first spring (3) in this position being supported under pre-tension by its part facing away from the control body (2) on the retaining lugs (50). With its other end, the first spring (3) is supported on the control body (2) or on the clamping cage (5), which has a circumferential U-shaped groove in its lower area for fixing the first spring (3).

The clamping cage (5) is designed here as a separate component, preferably made of sheet metal, and rests on the control body (2). The clamping cage (5) can be connected to the control body (2) in a detachable or non-detachable manner. In an embodiment not shown, the clamping cage (5) or, more generally, the clamping device is made in one piece with the control body (2). Plastic and metal are provided as materials for this one-piece component.

The control body (2) has guide elements (20) for axial guidance on the inner wall of the pressure equalization channel (1). These guide elements (20) are designed as ring segments extending axially from the bottom of the control body (2).

The structural design and mechanism for releasing the first spring are described below: The control body (2) is guided in a first section (11) of the pressure equalization channel (1), wherein the retaining lugs (50) of the clamping cage (5), which support the first spring (3) under prestress, are pressed radially outwards against the inner wall (10) in this section (11) by the prestressed first spring (3). This first section (11) is then followed by a second section (12) in the pressure equalization channel (1), the inner diameter of which is larger than the inner diameter of the first section (11), wherein the step between the first section (11) and the second section (12) forms the control edge (16) and the releasing means for the first spring (3). The excess pressure now causes the control body (2) with the retaining lugs (50) to be axially displaced. If the retaining lugs (50) now pass the control edge (16) as a result of the displacement and reach the second section (12), the retaining lugs (50) are pressed radially outwards there, as a result of which the first spring (3) is no longer supported and relaxes.

To ensure that the relaxing 1st spring (3) does not get caught in the clamping cage (5) with its coils, the spring (3) is preferably conical. The spring coil with the largest diameter is arranged in the area of the retaining lugs (50), while the spring coil with the smallest diameter is arranged in the area of the control body (2).

To support the control body (2) in the pressure equalization channel (1), the latter has a 3rd section (13) whose inner diameter is smaller than the inner diameter of the 1st section, whereby the

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At pressures below the critical pressure value, the control body (2) rests on a support surface (15) in the pressure equalization channel (1), which is formed by the diameter transition from the first section (11) to the third section (13). The control body (2) has raised cams (21) on its base, with which it rests on the support surface (15). This support of the control body (2) via cams (21) ensures that the area of the control body (2) subjected to flow and pressure is always the same, even when the control body (2) has lifted off the support surface (15). Otherwise, the area of the control body (2) subjected to pressure would increase when it lifted off, which would then result in an undesirable sudden increase in the force generated by the pressure in the pressure chamber. In addition, the cams (21) cause a disturbing adhesion or even sticking of the control body base to the support surface, which could occur in particular if the pressure chamber is partially filled with oil.

In a first embodiment, the cover (6) closing the pressure equalization channel (1) is simply pressed tightly into the pressure equalization channel (1) (see Figure 1). In a second embodiment (see Figure 2), the cover (6) is sealed off from the pressure equalization channel (1) by means of a circumferential seal (60), preferably an O-ring. So that the fixation of the cover (6) in the pressure equalization channel (1) can reliably withstand the pressure of the second spring (4), the cover (6) also has a locking lug (61) with which the cover (6) is clipped into the pressure equalization channel (1). A ring (62) is arranged on the cover (6) for radial fixation of the second spring (4). The cover (6) is preferably a plastic cover.

In the embodiment of the clamping cage (5) shown in Figure 5, the webs (51) below the retaining lugs (50) have predetermined bending lines (53), preferably through a material recess in the form of a constriction of the webs (51) in this area. At pressures below the critical pressure value, the webs (51) are only subjected to tensile stress by the pre-stressed 1st spring (3). However, as soon as the critical pressure value is reached and the retaining lugs (50) have passed the control edge (169), the retaining lugs (50) bend away due to the radial force component of the pre-stressed 1st spring (3) now taking effect via the bevels of the retaining lugs (50) in conjunction with the predetermined bending line (53).

In the embodiment of the clamping cage (5) shown in Figure 6, the webs (51) have support tabs (52) with which the webs (51) are supported against the inner wall (10) of the pressure equalization channel (1). In addition, grooves (17) - see Figure 7 - are provided in the 1st section (11) of the pressure equalization channel (1) to accommodate the webs (51) at least in the area of the retaining lugs (50), whereby the webs (51) are pressed into the grooves (17) when the support tabs (52) are moved over the control edge (16). The retaining lugs (50) thus suddenly release the pre-tensioned 1st spring (3). _##

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List of reference symbols

&rgr;) pressure space to be protected

Po) second pressure range

1) Pressure equalization channel

10) Inner wall of the pressure equalization channel

11) 1.Section of the pressure equalization channel

12) 2nd section of the pressure equalization channel

13) 3rd section of the pressure equalization channel

14) Housing of the pressure equalization channel

15) Support surface for the control body

16) Control edge (relaxation device for the 1st spring)

17) Grooves for receiving the pushed-away webs of the clamping cage

2) axially movable control body

20) Guide element

21) Cam on the control body

3) 1.Spring (pre-tensioned striker spring)

4) 2. Spring (the force that inhibits the axial displacement of the control body)

5) Clamping device for the 1st spring

50) radially movable support element for the 1st spring

51) Clamping cage webs

52) Support tabs

53) Support tabs

6) Stop element for the 2nd spring (cover of the pressure equalization channel)

60) O-ring seal on the lid

61) Locking lug on the lid

62) Ring on the cover for radial fixation of the 2nd spring

Claims (22)

1. Device for limiting the pressure in a pressure chamber (p) filled with gas or liquid to values below a critical pressure value, characterized by - a housing ( 1 A) which forms a pressure equalization channel ( 1 ) between the pressure chamber (p) filled with gas or liquid and a second pressure region (p ₀ ), - a control body ( 2 ) arranged in the pressure compensation channel ( 1 ), - which at least almost completely closes the flow cross-section in the pressure equalization channel ( 1 ) at pressures below the critical pressure value, - which is axially displaceable in the pressure equalization channel ( 1 ) as a result of pressure application against the effect of an inhibiting force means ( 4 ), - a spring ( 3 ) arranged in the pressure compensation channel ( 1 ) which is axially preloaded via clamping means ( 5 ), - wherein the prestressed spring ( 1 ) is relaxed by relaxation means ( 16 ) after a predetermined axial displacement of the control body ( 2 ) when the critical pressure value is reached, and as a result of the spring relaxation, the force inhibiting the axial displacement of the control body ( 2 ) is overcome and the control body ( 2 ) thus releases the flow cross-section for pressure equalization. 2. Device according to claim 1, characterized in that the prestressed spring ( 1 ) is axially displaceable together with the control body ( 2 ). 3. Device according to claim 1 or 2, characterized in that the tensioning means ( 5 ) for the prestressed spring ( 3 ) is axially displaceable together with the control body ( 2 ). 4. Device according to one of claims 1 to 3, characterized in that - the clamping means ( 5 ) has at least one support element ( 50 ) for the spring ( 1 ) which is radially movable transversely to the direction of displacement of the control body and which is axially displaceable with the control body ( 2 ) in the pressure compensation channel, - the support element ( 50 ) in the support position is pressed against the inner wall ( 10 ) of the pressure equalization channel ( 1 ) in a first section of the pressure equalization channel ( 1 ), wherein the spring ( 3 ) in this position of the support element ( 50 ) is supported with its part facing away from the control body ( 2 ) on the support element ( 50 ) under prestress, - the pressure equalization channel ( 1 ) has a second section ( 12 ) adjoining the first section ( 11 ), the inner diameter of which is larger than the inner diameter of the first section ( 11 ), the step between the first section ( 11 ) and the second section ( 12 ) forming the relaxation means for the spring ( 3 ) as a control edge ( 16 ), the support element ( 50 ) being pressed radially outwards in the displacement direction behind the control edge ( 16 ) so that the spring ( 3 ) is no longer supported and relaxes. 5. Device according to one of claims 1 to 4, characterized in that the force means ( 4 ) inhibiting the axial displacement of the control body ( 2 ) is formed by a second spring ( 4 ) which is supported against the control body and which, with its part facing away from the control body ( 2 ), is supported under prestress on a stop element ( 6 ) connected to the pressure equalization channel ( 1 ), wherein the relaxing 1st spring ( 3 ) removes the stop element ( 6 ) supporting the 2nd spring from the support position, so that the 2nd spring ( 4 ) is also relaxed and the inhibition for the axial displacement of the control body ( 2 ) is overcome, and the control body ( 2 ) thus releases the flow cross-section for pressure equalization. 6. Device according to claim 5, characterized in that the relaxing first spring knocks the stop element ( 6 ) for the second spring out of the pressure equalization channel ( 1 ). 7. Device according to one of claims 5 or 6, characterized in that the stop element ( 6 ) for the second spring ( 4 ) is formed by a cover which tightly closes the pressure compensation channel ( 1 ). 8. Device according to claim 7, characterized in that the cover ( 6 ) has a circumferential seal ( 60 ), preferably an O-ring, with which the cover ( 6 ) is sealed against the pressure equalization channel ( 1 ). 9. Device according to claim 7 or 8, characterized in that the cover ( 6 ) has a locking lug ( 61 ) with which the cover ( 6 ) is clipped into the pressure equalization channel. 10. Device according to one of claims 7 to 9, characterized in that the cover ( 6 ) has a ring ( 62 ) for radially fixing the second spring ( 4 ). 11. Device according to one of claims 2 to 10, characterized in that the first spring ( 3 ) is conical, the spring winding with the largest diameter being arranged in the region of the support element ( 50 ), and the spring winding with the smallest diameter being arranged in the region of the control body ( 2 ). 12. Device according to one of the preceding claims, characterized in that the tensioning means ( 5 ) for the axial pretension of the first spring ( 3 ) is connected in one piece with the control body ( 2 ). 13. Device according to one of the preceding claims 1 to 11, characterized in that the clamping means ( 5 ) is a separate component which is detachably connected to the control body ( 2 ). 14. Device according to one of the preceding claims 1 to 11, characterized in that the clamping means ( 5 ) is a separate component which rests on the control body ( 2 ). 15. Device according to one of the preceding claims, the control body ( 5 ) has at least one guide element ( 20 ) for axially guiding the control body ( 2 ) in the pressure equalization channel ( 1 ). 16. Device according to one of the preceding claims, characterized in that the pressure equalization channel ( 1 ) has a 3rd section ( 13 ) whose inner diameter is smaller than the inner diameter of the 1st section ( 11 ), wherein the control body ( 2 ) rests on a support surface ( 15 ) in the pressure equalization channel ( 1 ) at pressures below the critical pressure value, which support surface is formed by the diameter transition from the 1st section ( 11 ) to the 3rd section ( 13 ). 17. Device according to one of the preceding claims, characterized in that the pressure equalization channel ( 1 ) is part of the pressure chamber filled with gas or liquid. 18. Device according to one of the preceding claims 1 to 16, characterized in that the pressure equalization channel ( 1 ) is designed as a separate component which can be connected to the pressure chamber filled with gas or liquid. 19. Device according to one of the preceding claims 1 to 16, characterized in that the pressure equalization channel ( 1 ) is an integral part of a component which can be connected to the pressure chamber filled with gas or liquid. 20. Device according to one of the preceding claims, characterized in that the clamping means ( 5 ) for the 1st spring ( 3 ) is designed as a clamping cage consisting of two or more webs ( 51 ) which can be pressed resiliently or plastically radially outwards by the pre-tensioned spring ( 3 ) and have retaining lugs bent radially inwards as support elements ( 50 ), wherein the webs ( 51 ) are pressed against the inner wall ( 10 ) of the pressure equalization channel ( 1 ) at pressures below the critical pressure value in such a way that the retaining lugs ( 50 ) keep the 1st spring ( 3 ) axially pre-tensioned. 21. Device according to claim 20, characterized in that - the webs ( 51 ) have lateral support tabs ( 52 ) with which the webs ( 51 ) are supported against the inner wall ( 10 ) of the pressure equalization channel ( 1 ), - in the first section ( 11 ) of the pressure equalization channel ( 1 ) have grooves ( 17 ) for receiving the webs ( 51 ) at least in the region of the retaining lugs ( 50 ), wherein the webs ( 51 ) are pressed into the grooves ( 17 ) when the support tabs ( 52 ) are displaced over the control edge ( 16 ). 22. Device according to claim 20, characterized in that the webs ( 51 ) have a predetermined bending line ( 53 ), preferably below the retaining lugs ( 50 ), which causes the retaining lugs ( 50 ) to bend radially outward as soon as the webs ( 51 ) are at least partially displaced over the control edge ( 16 ).