Diaphragm Brake Cylinder With Reduction Ring Integrated in the Diaphragm

Abstract

A pneumatic diaphragm brake cylinder for motor vehicles includes a housing part on the pressure side and a housing part facing away from the pressure side, as well as a diaphragm arranged therebetween, which divides the interior of the diaphragm brake cylinder into two chambers sealed off from one another, of which a first chamber has a pressure chamber loaded by a pneumatic pressure and a second chamber has a piston chamber for a piston actuated by the diaphragm. A peripheral fastening edge of the diaphragm is clamped between the pressure-side housing part and the housing part facing away from the pressure. The pneumatic pressure loads a surface of the diaphragm which is effective with respect to a working movement of the diaphragm. A reduction ring is provided which extends axially from the diaphragm into the housing part facing away from the pressure and which radially reduces or radially limits the effective area of the diaphragm. At least the reduction ring and the diaphragm are designed as a one-piece component.

Claims

1.-16. (canceled)

17. A pneumatic diaphragm brake cylinder for a motor vehicle, comprising: a pressure-side housing part on a pressure side; a pressure-remote housing part facing away from the pressure side; a diaphragm which is arranged between the housing parts and divides an interior of the diaphragm brake cylinder into two spaces which are sealed off from one another, of which a first chamber comprises a pressure chamber loaded by a pneumatic pressure and a second chamber comprises a piston chamber for a piston actuated by the diaphragm, wherein a peripheral fastening edge of the diaphragm is clamped between the pressure-side housing part and the pressure-remote housing part, wherein the diaphragm is arranged between the pressure-side housing part and the pressure-remote housing part, wherein: a) pneumatic pressure loads an effective surface of the diaphragm with respect to a working movement of the diaphragm, b) a reduction ring extends axially from the diaphragm into the pressure-remote housing part facing away from the pressure, which reduction ring limits an effective area of the diaphragm radially on the outside, and c) at least the reduction ring and the diaphragm are formed as a one-piece component.

18. The pneumatic diaphragm brake cylinder according to claim 17, wherein the reduction ring is axially attached to the diaphragm on the pressure-remote side.

19. The pneumatic diaphragm brake cylinder according to claim 17, wherein the diaphragm consists essentially of a fabric-reinforced elastomer.

20. The pneumatic diaphragm brake cylinder according to claim 17, wherein the reduction ring is made of an elastomer without fabric reinforcement.

21. The pneumatic diaphragm brake cylinder according to claim 17, wherein a centering ring is arranged on the diaphragm and is integrally formed thereon, the centering ring is arranged offset radially inwards with respect to the circumferential fastening edge, projects axially into the pressure-side housing part, and centers the diaphragm with respect to a radially inner circumferential surface of the pressure-side housing part.

22. The pneumatic diaphragm brake cylinder according to claim 21, wherein the centering ring is disposed substantially perpendicular to a center plane of the peripheral fastening edge.

23. The pneumatic diaphragm brake cylinder according to claim 17, wherein the reduction ring is radially interposed between a radially inner circumferential surface of the pressure-remote housing part facing away from the pressure and a piston rod which is actuated by the diaphragm.

24. The pneumatic diaphragm brake cylinder according to claim 23, wherein a radially outer circumferential surface of the reduction ring has at least one recess and/or forms an annular gap with respect to the radially inner circumferential surface of the pressure-remote housing part facing away from the pressure, which annular gap or annular gaps form a flow connection between the second chamber and at least one breathing opening of the pressure-remote housing part.

25. The pneumatic diaphragm brake cylinder according to claim 18, wherein the diaphragm has a bellows-shaped portion extending into the pressure-remote housing part facing away from the pressure, which region adjoins the reduction ring radially on the inside.

26. The pneumatic diaphragm brake cylinder according to claim 17, wherein the brake cylinder comprises a pneumatic service brake cylinder.

27. The pneumatic diaphragm brake cylinder according to claim 17, wherein the pressure-side housing part comprises: a) an intermediate flange, which is designed so that a spring brake cylinder is attachable, or b) a spring brake cylinder.

28. The pneumatic diaphragm brake cylinder according to claim 26, wherein the brake cylinder comprises a combination cylinder of the service brake cylinder and a spring brake cylinder.

29. The pneumatic diaphragm brake cylinder according to claim 17, wherein the peripheral fastening edge has a wedge-shaped cross-section tapering radially inwardly.

30. The pneumatic diaphragm brake cylinder according to claim 29, wherein a first edge of the pressure-side housing part and a second edge of the pressure-remote housing part form axially between them an intermediate space which is complementary with respect to the cross section of the fastening edge tapering radially inwards and increases radially outwards and in which the fastening edge is clamped.

31. The pneumatic diaphragm brake cylinder according to claim 30, wherein the first edge and the second edge are braced against each other by a tension band or are flanged together under plastic deformation.

32. A pneumatic brake device comprising at least one pneumatic diaphragm brake cylinder according to claim 17.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is a partial longitudinal section view of a pneumatic diaphragm brake cylinder according to a preferred embodiment of the invention;

[0035] FIG. 2 is a section view of FIG. 1;

[0036] FIG. 3 is a longitudinal section view of two housing parts and an assembly consisting of a diaphragm and a reduction ring of the pneumatic diaphragm brake cylinder of FIG. 1;

[0037] FIG. 4 is a perspective view of the assembly unit consisting of the diaphragm and the reduction ring of FIG. 3; and

[0038] FIG. 5 illustrates an assembly step of the pneumatic diaphragm brake cylinder of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

[0039] In FIG. 1 to FIG. 5, a combined service brake and spring brake cylinder 1, hereinafter referred to as a combination cylinder, is shown as a preferred embodiment of a pneumatic diaphragm brake cylinder. The combined service brake and spring brake cylinder 1 comprises a service brake cylinder 2, an intermediate flange 6 and a spring brake cylinder 4, wherein the service brake cylinder 2 is structurally and functionally connected to the spring brake cylinder 4 by the intermediate flange 6. A spring brake piston 8 is displaceably arranged within the spring brake cylinder 4, wherein an accumulator spring 10 rests against one side of the spring brake piston 8. The accumulator spring 10 is supported on its opposite side on the base of the spring brake cylinder 4. A spring brake chamber 12 is formed between the spring brake piston 8 and the intermediate flange 6, which chamber communicates, for example, with an electro-pneumatic valve device, not shown for reasons of scale, for venting and exhausting the same. When ventilated, the spring brake piston 8 is displaced axially into the parking brake release position under tension of the accumulator spring 10. During this displacement of the spring brake piston 8, the air which is present inside the spring chamber 14 accommodating the accumulator spring 10 is forced out via a vent not shown here. If, on the other hand, the spring brake chamber 12 is vented for the purpose of braking, then the accumulator spring 10 is able to displace the spring brake piston 8 into the applied position.

[0040] The spring brake piston 8 is connected to a hollow piston rod 18, which extends through the intermediate flange 6 into a pressure chamber 20 of the service brake cylinder 2 and is supported there on a diaphragm plate 26. A seal 22 inserted in the intermediate flange 6 seals against the outer wall of the piston rod 18 during its longitudinal movement. An inlet, which is not shown, opens into the pressure chamber 20, via which compressed air is admitted and discharged for actuating the service brake cylinder 2. The compressed air acts on a diaphragm 24 inserted within the service brake cylinder 2, on the opposite side of which a pressure piece in the form of the rigid diaphragm plate 26 is provided. More precisely, the diaphragm 24 separates the pressure chamber 20 of the service brake cylinder 2, which can be charged and discharged with pressure medium, from a piston chamber 31 accommodating a return spring 30 supported on the diaphragm plate 26. In relation to the service brake function and the pneumatic pressure prevailing in the pressure chamber 20, the intermediate flange 6 therefore forms here a housing part on the pressure side and the service brake cylinder 2 or its piston chamber 31 forms a housing part of the combined service brake and spring brake cylinder 1 facing away from the pressure.

[0041] The diaphragm plate 26 is connected to a push rod 28, which interacts with a brake actuating mechanism external to the combined service brake and spring brake cylinder 1. This may be, for example, actuating elements of a disc brake of a motor vehicle. The service brake cylinder 2 is an active brake cylinder, that is to say that the service brake is applied by venting the service brake chamber 20 and released by venting. The return spring 30, which is supported on the one hand on the diaphragm plate 26 and on the other hand on the base of the service brake cylinder 2, ensures that the pressure rod 28 is returned to the release position when the service brake chamber 20 is vented.

[0042] A radially outer attachment edge 32 of diaphragm 24 has a wedge-shaped cross-section tapering radially inwardly. This radially outer mounting edge 32 of the diaphragm 24, having a wedge-shaped cross-section tapering radially inwardly, is clamped between a first edge 16 of the intermediate flange 6 and a second edge 17 of the service brake cylinder 2 in a complementary shaped intermediate space or gap 34 having a wedge-shaped cross-section flaring radially outwardly. The intermediate flange 6 and the service brake cylinder 2 therefore form their edges 16, 17 as radially outwardly bent flanges, the oppositely facing inner surfaces of which form the intermediate space 34 of wedge-shaped cross-section between them.

[0043] Furthermore, at least one centering ring 40 extending in the axial direction and arranged offset radially inwardly with respect to the fastening edge 32 is formed or integrally formed on the diaphragm 24, which centering ring 40 points axially towards the intermediate flange 6 and by means of which the diaphragm 24 is centered against a radially inner circumferential surface 42 of the wall 44 of the intermediate flange 6. Particularly preferably, the centering ring 40 is arranged substantially perpendicular to a central plane of the peripheral fastening edge 32 and projects away from the diaphragm 24 on one side, for example. However, it is also conceivable that instead of this one centering ring 40, or additionally, a further centering ring is provided which projects in the direction of the spring brake cylinder 4 and centers against the radially inner circumferential surface of the wall thereof.

[0044] Last but not least, the radially inner circumferential surface 42 of the intermediate flange 6, against which the centering ring 40 centers, preferably lies on an imaginary cone, whose center axis is coaxial with the cylinder axis 46.

[0045] As shown, the centering ring 40 may be formed to be completely circumferential, as viewed in the circumferential direction, or to comprise ring sections. The diaphragm 24 and the centering ring 40 integrally formed therewith preferably comprise a fabric-reinforced elastomer.

[0046] Then, an axial component of the clamping force between the intermediate flange 6 and the service brake cylinder 2 causes the centering ring 40 of the diaphragm 24 to be pressed against the radially inner peripheral surface 42 of the wall 44 of the intermediate flange 6. In other words, the axial component of the clamping force ensures that the fastening edge 32 is pulled radially outwards due to the wedge effect and thereby the centering ring 40 is pressed with higher radial force against the radially inner circumferential surface 42 of the wall 44 of the intermediate flange 6 in the sense of a self-reinforcement of the centering.

[0047] Such an axial clamping force component can be realized, for example, by the second edge 17 of the service brake cylinder 2 and the first edge 16 of the intermediate wall 6 being overlapped by a clamping band 48, which then provides the axial component of the clamping force.

[0048] The diaphragm 24, the centering ring 40 and a reduction ring 36 form an integrated, one-piece component 38. While, as explained above, the diaphragm 24 and the centering ring 40 integrally formed therewith preferably comprise a fabric-reinforced elastomer, the reduction ring 36 comprises, for example, the same elastomer but without fabric reinforcement. The centering ring 40 is optional, however, because according to an embodiment not shown here, the one-piece component can also comprise only the diaphragm 24 and the reduction ring 36.

[0049] The reduction ring 36 extends axially from the diaphragm 24 into the service brake cylinder 2. Further, the reduction ring 36 is substantially cylindrical and has a wall thickness which is a difference between the outer diameter and the inner diameter of the reduction ring 36.

[0050] Preferably, the reduction ring 36 is axially attached to the diaphragm 24 on the pressure-relief side, i.e. in the direction of the piston chamber 31 of the service brake cylinder 2. Also, the reduction ring 36 is radially intermediate a radially inner circumferential surface 52 of the service brake cylinder 2 and the push rod 28 which is actuated by the diaphragm 24.

[0051] As FIG. 4 shows, a radially outer circumferential surface 56 of the reduction ring 36 may here, for example, have axial recesses 54 distributed in the circumferential direction and contact with its remaining surface a radially inner circumferential surface 52 of the service brake cylinder 2, as is best illustrated with reference to FIG. 3. Furthermore, breathing openings 62 may be formed in a wall 60 of the service brake cylinder 2 in the region of the piston chamber 31 and here in particular also in the region of the reduction ring 36, which are arranged in such a way that they are permanently connected to the piston chamber 31 of the service brake cylinder 2 by means of the recesses 54. The recesses 54 therefore form a flow connection between the piston chamber 31 and the breathing openings 62 of the service brake cylinder 2. This flow connection comes into effect when, as a result of the axial working movement of the diaphragm 24, the piston chamber is reduced or enlarged so that air is forced out of the piston chamber 31 or drawn into the piston chamber.

[0052] Instead of radially outer recesses 54 or in addition thereto, an annular gap may also be provided between the radially outer peripheral surface 56 of the reduction ring 36 and the radially inner peripheral surface 52 of the service brake cylinder 2, which then also creates such a flow connection.

[0053] As can be readily imagined with reference to FIG. 2, the pneumatic pressure present in the pressure chamber 20 with respect to a working movement of the diaphragm 24 loads an effective area 50 of the diaphragm 24. The effective area 50 of the diaphragm 24 therefore represents an area which can perform the working movement occurring here parallel to the cylinder axis 46 when the pressure chamber 20 is vented.

[0054] The purpose of the reduction ring 36 is then to radially reduce the effective area 50 of the diaphragm 24, whereby the reduction ring 36 then also reduces the internal diameter of the service brake cylinder 2. This reduces the effective area 50 of the diaphragm 24 for the pneumatic pressure, which can deform elastically as a result of the pneumatic pressure in the pressure chamber 20. As a result, the force generated at the diaphragm 24 as a result of the pneumatic pressure in the pressure chamber 20 decreases, for example. The wall thickness of the reduction ring 36 can therefore be used to individually adjust the force exerted by the service brake cylinder 2 via the piston rod 28.

[0055] As can best be seen from FIG. 3, the diaphragm 24 has a bellows-shaped portion 64 extending into the service brake cylinder 2, which is radially inwardly adjacent to the reduction ring 36.

[0056] If the reduction ring 36, the diaphragm 24 and optionally also the centering ring 40 are designed as a one-piece component 38, then the manufacturing of the combined service brake and spring brake cylinder 1 is simplified because instead of two parts, namely a separate diaphragm and a separate reduction ring, only the one one-piece component 38 has to be assembled to the combined service brake and spring brake cylinder 1, as shown with reference to FIG. 5. There, an assembly step of an assembly of the combined service brake and spring brake cylinder 1 is illustrated in which on the other hand, this combination of the diaphragm 24, the reduction ring 36 and optionally also the centering ring 40 also ensures a higher insensitivity of the combined service brake and spring brake cylinder 1 to leaks, because the number of sealing points is reduced.

[0057] The use of the one-piece component 38 according to the invention comprising diaphragm 24, reduction ring 36 and optionally centering ring 40 is not limited to a combined service brake and spring brake cylinder 1, but such a one-piece component can of course be used with any type of pneumatic diaphragm brake cylinder.

LIST OF REFERENCE SIGNS

[0058] 1 combined service brake and spring brake cylinder [0059] 2 service brake cylinder [0060] 4 spring brake cylinder [0061] 6 intermediate flange [0062] 8 spring brake piston [0063] 10 storage spring [0064] 12 spring brake chamber [0065] 14 spring chamber [0066] 16 first edge [0067] 17 second edge [0068] 18 piston rod [0069] 20 pressure chamber [0070] 22 seal [0071] 24 membrane [0072] 26 diaphragm plate [0073] 28 push rod [0074] 30 return spring [0075] 31 piston chamber [0076] 32 peripheral fastening edge [0077] 34 intermediate space [0078] 36 reduction ring [0079] 38 one-piece component [0080] 40 centering ring [0081] 42 radial inner circumferential surface [0082] 44 wall [0083] 46 cylinder axis [0084] 48 tension band [0085] 50 effective area [0086] 52 radial inner circumferential surface [0087] 54 recesses [0088] 56 radial outer circumferential surface [0089] 60 wall [0090] 62 breathing openings [0091] 64 bellows-shaped portion