Title of Invention

COMBINED SERVICE BRAKE AND SPRING BRAKE CYLINDER

Abstract

The invention relates to a combined service brake and spring brake cylinder (1) for the braking system of a motor vehicle, in particular for vehicles comprising service and spring brake pistons (4, 8) guided inside a casing (10) which is common for two brake cylinders (2, 6), wherein the spring brake piston (8) is loaded by at least one storage spring (28) and has an external diameter greater than that of the service brake piston (4). According to said invention, the spring brake piston (8) is embodied in the form of an annular piston and at least a part of the rod thereof is constructed in the form of a piston tube which surrounds the service brake piston (4) and forms an external radial running and sealing surface therefor.

Full Text

WO 2006/027148 PCT/EP2005/009373 Combined service brake and spring brake cylinder Description Prior art The invention relates to a combined service brake and spring cylinder for brake systems of vehicles, in particular of commercial vehicles, with a spring and service brake piston guided within a housing common to both brake cylinders, the spring piston being loaded by at least one preloaded spring and having a larger outside diameter than the service brake piston, according to the preamble of patent claim 1. Such a combined service brake and spring brake cylinder is known from EP 0 452 621 Bl. Within the housing is inserted an inner housing which is formed from a bottom and a cylinder and within which the service brake piston is guided displaceably, a pressure chamber capable of being acted upon by pressure medium for the service brake piston being formed between the service brake piston and the inner housing bottom facing the spring piston. The spring piston surrounds the inner housing in a pot-shaped manner and is guided displaceably by means of a seal on the outer wall of the inner housing. The pressure chamber of the spring piston is formed between the bottom of the inner housing and the spring piston. The object on which the present invention is based is to develop further a combined service brake and spring brake cylinder of the type initially mentioned, in such a way that it is of simpler, more compact, more cost-effective and lighter construction. This object is achieved, according to the invention, by means of the features of patent claim 1. WO 2006/027148 PCT/EP2005/009373 - 2 - Advantages of the invention The invention proposes that the spring brake piston be an annular piston, and at least part of its piston rod designed as a piston tube surround the service brake piston and form a radially outer running and sealing surface for the latter. The inner housing of the prior art, which has hitherto guided this service brake piston and the spring brake piston, may then be dispensed with, thus resulting in a simpler and more cost-effective manufacture and assembly of the combined service brake and spring brake cylinder. Moreover, the weight falls as a result. As seen in the radial direction, the spring brake piston or its piston tube overlaps the service brake piston, so that the actuating travels of the two pistons do not accumulate, but run parallel to one another. The combined service brake and spring brake cylinder according to the invention can therefore have a very short and compact build. Advantageous developments and improvements of the invention specified in patent claim 1 are possible as a result of the measures listed in the subclaims. Particularly preferably, the spring brake piston is connected axially to the piston tube approximately at its middle diameter, the preloaded spring surrounding the piston tube. A radially inner circumferential surface of the housing then constitutes a radially outer running and sealing surface for the spring brake piston, and between said running and sealing surface and a housing cover composed of a bottom and a cylinder, is formed a pressure chamber of the spring brake piston. WO 2006/027148 PCT/EP2005/009373 - 3 - Preferably, the piston tube of the spring brake piston carries, on its side facing away from the spring piston, an axially displaceable bottom, a pressure chamber of the service brake being formed between this bottom and the service brake piston. A return spring supported on the housing cover urges the service brake piston toward the displaceable bottom of the pressure chamber of the service brake, said bottom, in turn, being capable of butting against a housing bottom. A central pressure rod acting on a brake mechanism and projecting through a passage orifice of the housing cover projects away from the service brake piston. Last but not least, when the spring brake is actuated in the application direction, the service brake piston is designed to be capable of being driven in the brake application direction by the bottom, this bottom being provided with at least one connection for the aeration and/or deaeration of the pressure chamber of the service brake. The further construction of the combined service brake and spring brake cylinder according to the invention becomes clear from the following description of an exemplary embodiment. Drawings An exemplary embodiment of the invention is illustrated below in the drawing and is explained in more detail in the following description. In the drawing, the single figures shows a highly diagrammatic cross-sectional illustration of a combined service brake and spring brake cylinder according to a preferred embodiment of the invention. Description of the exemplary embodiment WO 2006/027148 PCT/EP2005/009373 - 4 - The preferred embodiment, designated as a whole by 1 in the figure, of a combined service brake and spring brake cylinder forms a brake actuator, for example, for disk brakes of commercial vehicles and is actuated pneumatically. It contains a service brake cylinder 2, in which a service brake piston 4 is guided displaceably, and a spring brake cylinder 6, which guides a spring piston 8. Both brake cylinders 2, 6 are received in a single housing 10 which preferably has an internally smooth cylindrical form and is of bowl-shaped design, that is to say it is delimited at one end by a housing bottom 12 and at its other end has an orifice 20 closed by means of a housing cover 18 composed of a bottom 14 and of a cylinder 16. The cylinder 14 and housing 10 are coaxial to one another. The spring piston is designed as an annular piston 8 and has a central passage orifice. A radially inner circumferential surface of that end of the housing 10 which faces the orifice 20 and also the cylinder 16 form in each case a running and sealing surface for the spring piston 8 which can carry corresponding seals on its circumference. Furthermore, between the radially inner circumferential surface of the housing 10 and the housing cover 18 composed of the bottom 14 and of the cylinder 16 is formed a pressure chamber 22 for the spring brake piston 8. The bottom 14 of the pressure chamber 22 is consequently to be treated as equivalent to the annular end face of the housing cover 10 or of the housing 10 itself. The housing cover 18 may be produced in one piece, in which case the cylinder 16 and the bottom 14 form a single part which is flanged to the housing 10, or it may also be produced in more than one piece. A piston rod designed as a piston tube 24 closed on the circumference projects from the spring brake piston 8 away in the direction of the housing bottom 12, the piston tube 24 having approximately the middle diameter of the spring brake piston 8. WO 2006/027148 PCT/EP2005/009373 - 5 - In an annular space 2 6 between a radially inner circumferential surface of the housing 10 and a radially outer circumferential surface of the piston tube 24 is accommodated a preloaded spring 2 8 which is supported, on the one hand, on the spring brake piston 8 and, on the other hand, on the housing bottom 12. The preloaded spring 2 8 thus surrounds the piston tube 24 of the spring brake piston 8 completely. By means of an air connection 30 connected to the pressure chamber 22 of the spring brake piston, said pressure chamber can be aerated and deaerated. The spring brake is a passive brake, that is to say it is released, counter to the action of the preloaded spring 28, by the aeration of the pressure chamber 22 and, after deaeration of the pressure chamber 22, is applied by the spring forces of the preloaded spring 28. The spring brake piston 8 has a larger outside diameter than the preferably cylindrical service brake piston 4. The latter is guided axially displaceably along its entire actuating travel with its radially outer circumference on the radially inner circumference of the piston tube 24 of the spring brake piston 8. That is to say, the piston tube 24 forms a radially outer running and sealing surface for the circumference of the service brake piston 4, into which, for example, seals, not shown here, may be embedded. A central pressure rod 32 projects away from the service brake piston 4 and through the orifice 20 of the housing cover 18 and acts on a brake mechanism, not relevant here, of the disk brake. A release system for the disk brake may be integrated into the pressure rod. Furthermore, the service brake piston 4 is supported by a return spring 34 on a collar 36 of the housing cover 18, said collar projecting radially inward on the end face. The return spring 34 is shaped in longitudinal WO 2006/027148 PCT/EP2005/009373 - 6 - cross section, for example, so as to bulge outward or inward, so that, during compression, the turns can penetrate axially one into the other so as to save construction length. The piston tube 24 carries on the end face, on its side facing away from the spring brake piston 8, an axially displaceable bottom 38, a pressure chamber 4 0 of the service brake being formed between this bottom 3 8 and the service brake piston 4. The service brake piston 4 is urged toward the displaceable bottom 3 8 by the return spring 34. Last but not least, the displaceable bottom 3 8 and the piston tube 24 fastened, pressuretight, to it form together the outer wall of the axially displaceable service brake cylinder 2. The displaceable bottom 38 of the pressure chamber 40 of the service brake is capable of butting against the housing bottom 12, in particular the return spring 34 urges it into this position. Furthermore, during the actuation of the spring brake in the application direction, the service brake piston 4 is designed to be capable of being driven in the brake application direction by the bottom 38. The may be implemented, for example, in that the bottom 38, with the exception of its radially outer annular portion 42, which is fastened to the piston tube 24 and which must be manufactured from rigid material so as to be capable of butting against the service brake piston 4, is formed by a flexible diaphragm 44 which is fastened to the annular portion 42 radially on the inside and which can be supported on the housing bottom 12 when the pressure chamber 4 0 is aerated. In order to make this situation clear, the bottom 3 8 of the pressure chamber 4 0 is illustrated as a sawtooth profile. In actual fact, the bottom 3 8 may even be flat. Preferably, the bottom 38 is provided with a central connection for aerating the pressure chamber 4 0 of the WO 2006/027148 PCT/EP2005/009373 - 7 - service brake, said connection consisting, for example, of a rigid tube projecting through the housing bottom 12 from outside and issuing to the bottom 38. This connection cooperates with an inlet valve 46, not shown in detail for reasons of scale. An outlet valve 4 8 for deaerating the pressure chamber 4 0 is introduced, for example, into the annular portion 42 of the bottom 38. The outlet and inlet valves 4 6 and 4 8 are, for example, electrically controlled valves and are actuated by an electronic control apparatus, not shown for reasons of scale. The service brake is an active brake, that is to say it is applied as a result of the aeration of the assigned pressure chamber 40 and is released due to deaeration. The space 5 0 between the service brake piston 4 and the housing cover 12 is protected against dirt and moisture, for example, by means of a sleeve 52, the sleeve having a central sealing passage orifice for the pressure rod 32 and being fastened to the housing cover 18 radially on the inside. A radially outer sealing ring 5 8 on the service brake piston 4 ensures the leaktight guidance of the latter on the piston tube 24. Alternatively, this could also be implemented by a diaphragm. With the aid of bolts 56, the housing 10 carrying the brake actuator can be connected to a flange of the disk brake. Against this background, the functioning of the combined service brake and spring brake cylinder 1 according to the invention is as follows: To apply the service brake, with the spring brake released, compressed air is fed into the pressure chamber 4 0 of the service brake via the open inlet valve 46 when the outlet valve 48 is closed. As a result, on the one hand, the diaphragm 44 forming the bottom 3 8 of the pressure chamber 4 0 is urged toward WO 2006/027148 PCT/EP2005/009373 - 8 - the housing bottom 12 and, on the other hand, the service brake piston 4 is displaced to the left in the figure, its radially outer circumference sliding sealingly along on the radially inner circumferential surface of the piston tube 24. The pressure prevailing in the pressure chamber 22 of the spring brake ensures that, as shown in the figure, the preloaded spring 2 8 is compressed and the spring brake is consequently also released. To release the service brake, the assigned pressure chamber 4 0 merely has to be deaerated, the return spring 34 pushing the service brake piston 4 back into its initial position. To engage the spring brake, for example in a parking brake situation, the pressure chamber 4 0 of the service brake is deaerated by the outlet valve 48, and at the same time also the pressure chamber 22 of the spring brake, whereupon the preloaded spring 2 8 displaces the spring brake piston 8 to the left. The latter, via the piston tube 24, can drive the bottom 3 8 of the then deaerated pressure chamber 4 0 of the service brake, because no pressure resistance is opposed to this movement on account of the deaerated pressure chamber 40. When the spring brake piston 8 has reached its application position, the service brake piston 4 is consequently also detained in the applied position owing to the action of the preloaded spring forces. To engage the parking brake, the spring brake piston can also detain the already previously applied service brake piston 4, in that the initially aerated pressure chamber 4 0 of the service brake is deaerated and the spring brake piston 8, is displaced to the left into the application position due to the dearation of its pressure chamber 22. No compressed air is therefore required in order to hold the parking brake in the applied position for a lengthy period of time. WO 2006/027148 PCT/EP2005/009373 - 9 - To release the spring brake, the pressure chamber 22 of the spring brake is aerated, whereupon the spring brake piston 8 is moved to the right, counter to the action of the preloaded spring 28, together with the piston tube 24 and the bottom 3 8 of the pressure chamber 4 0 of the service brake. This movement can be followed by the service brake piston 4 which is in abutment against the bottom 3 8 of its pressure chamber, because the return spring 34 urges said service brake piston toward there, and because the pressure chamber 40, deaerated as before, of the service brake affords no pressure resistance. WO 2006/027148 PCT/EP2005/009373 - 10 - List of reference symbols 1 Combined service brake and spring brake cylinder 2 Service brake cylinder 4 Service brake piston 6 Spring brake cylinder 8 Spring brake piston 10 Housing 12 Housing bottom 14 Bottom 16 Cylinder 18 Housing cover 20 Orifice 22 Pressure chamber 24 Piston tube 2 6 Annular space 2 8 Preloaded spring 3 0 Air connection 32 Pressure rod 3 4 Return spring 36 Collar 3 8 Bottom 4 0 Pressure chamber 4 2 Annular portion 44 Diaphragm 4 6 Inlet valve 48 Outlet valve 5 0 Space 52 Sleeve 56 Bolt 58 Seal WO 2006/027148 PCT/EP2005/009373 - 11 - Patent claims 1. A combined service brake and spring brake cylinder (1) for brake systems of vehicles, in particular of commercial vehicles, with a spring and service brake piston (4, 8) guided within a housing (10) common to both brake cylinders (2, 6), the spring brake piston (8) being loaded by at least one preloaded spring (28) and having a larger outside diameter than the service brake piston (4), characterized in that the spring brake piston (8) is an annular piston, and at least part of its piston rod designed as a piston tube (24) surrounds the service brake piston (4) and forms a radially outer running and sealing surface for the latter. 2. The service brake and spring brake cylinder as claimed in claim 1, characterized in that the spring brake piston (8) is connected axially to the piston tube (24) approximately at its middle diameter. 3. The service brake and spring brake cylinder as claimed in at least one of the preceding claims, characterized in that the preloaded spring (28) surrounds the piston tube (24) of the spring brake piston (8). 4. The service brake and spring brake cylinder as claimed in at least one of the preceding claims, characterized in that a radially inner circumferential surface of the housing (10) forms a radially outer running and sealing surface for the spring brake piston 3 5 5. The service brake and spring brake cylinder as claimed in claim 4, characterized in that a pressure chamber (22) of the spring brake is formed between the radially inner circumferential surface of the housing WO 2006/027148 PCT/EP2005/009373 - 12 - (10) and a housing cover (18) composed of a bottom (14) and of a cylinder (16) . 6. The service brake and spring brake cylinder as claimed in claim 5, characterized in that a return spring (34) of the service brake piston (4) is supported on the housing cover (18). 7. The service brake and spring brake cylinder as claimed in claim 6, characterized in that the piston tube (24) of the spring brake piston (8) carries, on its side facing away from the spring brake piston (8), an axially displaceable bottom (38), a pressure chamber (4 0) of the service brake being formed between this bottom (38) and the service brake piston (4). 8. The service brake and spring brake cylinder as claimed in claim 7, characterized in that the return spring (34) urges the service brake piston (4) toward the displaceable bottom (38) of the pressure chamber (4 0) of the service brake. 9. The service brake and spring brake cylinder as claimed in claim 8, characterized in that the displaceable bottom (38) of the pressure chamber (40) of the service brake is capable of butting against a housing bottom (12). 10. The service brake and spring brake cylinder as claimed in claim 9, characterized in that, during the actuation of the spring brake in the application direction, the service brake piston (4) is designed to be capable of being driven in the brake application direction by the bottom (38). 11. The service brake and spring brake cylinder as claimed in claim 10, characterized in that the bottom (38) is provided with at least one connection (46, 48) WO 2006/027148 PCT/EP2005/009373 - 13 - for the aeration and/or deaeration of the pressure chamber (4 0) of the service brake. 12. The service brake and spring brake cylinder as claimed in claim 11, characterized in that a central pressure rod (32) projects away from the service brake piston (4) and acts on a brake mechanism. 13 . The service brake and spring brake cylinder as claimed in claim 12, characterized in that the pressure rod (32) projects through a passage orifice of the housing cover (18). 14. The service brake and spring brake cylinder as claimed in claim 13, characterized in that the preloaded spring (28) is supported, on the one hand, on the spring brake piston (8) and, on the other hand, on the housing bottom (12). The invention relates to a combined service brake and spring cylinder (1) for the braking system of a motor vehicle, in particular for vehicles comprising service and spring brake pistons (4,8) guided inside a casing (10) which is common for two brake cylinders (2,6) wherein the spring brake piston (8) is loaded by at least one storage spring (28) and has an external diameter greater than that of the service brake piston (4). According to said invention, the spring brake piston (8) is embodied in the form of an annular piston and at least a part of the rod thereof is constructed in the form of a piston tube which surrounds the service brake piston (4) and forms an external radial running and sealing surface therefor.

Documents:

00959-kolnp-2007- correspondence-1.1.pdf

00959-kolnp-2007-correspondence-1.2.pdf

00959-kolnp-2007-international search authority report-1.1.pdf

00959-kolnp-2007-others document-1.1.pdf

00959-kolnp-2007-p.a.pdf

00959-kolnp-2007-priority document-1.1.pdf

0959-kolnp-2007-abstract.pdf

0959-kolnp-2007-claims.pdf

0959-kolnp-2007-correspondence others.pdf

0959-kolnp-2007-description (complete).pdf

0959-kolnp-2007-drawings.pdf

0959-kolnp-2007-form1.pdf

0959-kolnp-2007-form2.pdf

0959-kolnp-2007-form3.pdf

0959-kolnp-2007-form5.pdf

0959-kolnp-2007-international publication.pdf

0959-kolnp-2007-international search authority report.pdf

0959-kolnp-2007-other document.pdf

0959-kolnp-2007-pct form.pdf

0959-kolnp-2007-pct others.pdf

0959-kolnp-2007-priority document.pdf

959-KOLNP-2007-(13-05-2014)-CORRESPONDENCE.pdf

959-KOLNP-2007-(13-05-2014)-FORM-1.pdf

959-KOLNP-2007-(13-05-2014)-FORM-5.pdf

959-KOLNP-2007-(30-01-2014)-ABSTRACT.pdf

959-KOLNP-2007-(30-01-2014)-ANNEXURE TO FORM 3.pdf

959-KOLNP-2007-(30-01-2014)-CLAIMS.pdf

959-KOLNP-2007-(30-01-2014)-CORRESPONDENCE.pdf

959-KOLNP-2007-(30-01-2014)-DESCRIPTION (COMPLETE).pdf

959-KOLNP-2007-(30-01-2014)-DRAWINGS.pdf

959-KOLNP-2007-(30-01-2014)-FORM-1.pdf

959-KOLNP-2007-(30-01-2014)-FORM-2.pdf

959-KOLNP-2007-(30-01-2014)-OTHERS.pdf

959-KOLNP-2007-(30-01-2014)-PETITION UNDER RULE 137.pdf

959-KOLNP-2007-CORRESPONDENCE-1.2.pdf

959-kolnp-2007-form 18.pdf

abstract-00959-kolnp-2007.jpg