MX2008006981A - Combined service brake and stored-energy brake cylinder with internal ventilation - Google Patents

Abstract

The invention relates to a combined service brake and the stored-energy brake cylinder (1) having:a) a diaphragm (24) which is arranged in a housing of the service brake cylinder (2) and to which pressure can be applied, said diaphragm (24) bounding on one side a brake chamber (20) to which service brake pressure can be applied and on the other side a chamber which holds a restoring spring, b) a stored-energy brake piston (8) which is arranged in a housing of the stored-energy brake cylinder (4) and can be activated by a pre-loaded spring (10), said stored-energy brake piston (8) bounding on one side a stored-energy brake chamber (12) and on the other side a spring chamber (14) which holds a pre-loaded spring (10), and the said stored-energy brake piston (8) having a piston rod (18) which is fitted with a ventilation valve (16) which forms or shuts off a flow connection between the spring chamber (14) and the service brake chamber (20), which combined service brake and stored-energy brake cylinder (1) is characterized by the fact that the ventilation valve (16) has the following features:c) a piston (38) which is fitted with a valve body (36) is provided, said piston (38) being guided in an axially displaceable fashion in a cylinder (40) which is formed on the piston rod (18), d) at least one compression spring (42) which is supported on the piston (38) loads the valve body (36) against a first valve seat (44) on the piston (38) and against a second valve seat (48) on the cylinder (40), e) the valve body (36) is loaded by the pressure in the spring chamber (14) in a direction which lifts it off from the first valve seat (44) and from the second valve seat (48), f) the piston (38) is loaded by the pressure in the service brake chamber (20) in a direction which forces the first valve seat (44) against the valve body (36) and lifts off the valve body (36) from the second valve seat (48), in which case g) a flow connection is formed between the service brake chamber (20) and the spring chamber (14) when the valve body (36) has been lifted off from the first valve seat (44) and/or when the valve body (36) has been lifted off from the second valve seat (48).

Description

COMBINED BRAKE CYLINDER FOR SERVICE AND BY SPRING ACCUMULATOR WITH INTERNAL VENTILATION DESCRIPTION OF THE INVENTION STATE OF THE ART The invention is based on a combined service brake cylinder and spring accumulator comprising a membrane that can absorb a pressure, arranged in a service brake cylinder housing that delimits on one side a service brake chamber capable of to absorb a service brake pressure and on the other side a chamber that houses a return spring, an accumulator spring brake piston disposed in an accumulator spring brake cylinder housing, which can be operated by an accumulator spring. force and that delimits on one side an accumulator spring brake chamber and on the other side a spring chamber that houses the force accumulator spring and a piston rod, the latter carrying a vent valve that opens or closes a current between the spring chamber and the service brake chamber, according to the general concept of claim 1. A combined service brake cylinder This is how, for example, document DE 40 11 739 A1 is known.

Ventilation is arranged there in the hollow piston tube of the accumulator spring brake piston which can be extended, depending on the operating state, to the service brake chamber. The vent valve has the objective of reducing the overpressure in the spring chamber that is generated in it by releasing the parking brake due to the return of the parking brake piston and the reduction of the volume because of it, because it is changed to the open position due to overpressure and opens a connection for the current between the spring chamber and the service brake chamber. When starting on a flat path, the service brake chamber is ventilated and is connected to a vent of a pressure regulator module since it is not required to operate the service brake after releasing the parking brake. Then at least a part of the excess volume of air in the spring chamber can come out, so that consequently it does not reach there directly from the atmosphere, for example through a valve arranged in the wall of the spring chamber, but by the air inlet and outlet route of the service brake chamber. For this reason, internal ventilation is also discussed in this context. However, when starting in a section of track in ascent it is necessary firstly to be the brake of Applied parking, additionally apply the service brake at least for a short time before releasing the parking brake to prevent the vehicle from rolling backwards during start-up. In this case air is injected into the service brake chamber. If there is a need to brake sufficiently hard on the part of the driver, then the pressure of the service brake acting on the service brake chamber and simultaneously on the side of the piston can keep it against the effect of this increasing pressure in the valve seat, and thus keep the vent valve closed. But if the service brake pressure and / or pressure gradient of the service brake are below a certain threshold value, because of a need to apply the low service brake by the operator, then it is not Sufficient the pressure of the service brake acting on one side of the plunger to keep the vent valve closed. Then the compressed air from the service brake chamber flows through the vent valve open to the spring chamber. From there it escapes through the sealing of the piston and the sealing of the box to the atmosphere, which causes, on the one hand, annoying noises. But on the other hand, the volume of air that comes out through the vent valve is no longer available to generate the force for the service brake. The present invention is based on the objective of improving a combined cylinder of service brake and spring-loaded accumulator brake of the type initially mentioned in such a way that the disadvantages referred to above are avoided. This object is achieved inventively by the features of claim 1. Advantages of the invention The ventilation valve of the combined service brake cylinder and the accumulator spring brake has, according to the invention, the following distinguishing characteristics: piston carrying a valve body which is guided so that it can move axially in a cylinder formed in the piston rod, b) at least one pressure spring that rests on the piston pushes the valve body against a first thrust of the piston rod. valve in the plunger and against a second valve seat in the cylinder, c) the valve body is loaded by the pressure in the spring chamber in a direction that lifts it from the first valve seat and the second valve seat, d ) the plunger is under load due to the pressure in the service brake chamber and in a direction that pushes the first valve seat against the valve body and that lifts the valve body from the second valve seat, so e) the valve body being separated from the first valve seat. valve and / or the second valve seat opens a current connection between the service brake chamber and the spring chamber. This measure guarantees that the ventilation valve remains closed when - when the parking brake is applied - the service brake is applied simultaneously. Thanks to this it is no longer possible for compressed air to flow from the service brake chamber through the vent valve to the spring and exhaust chamber from there to the atmosphere, which suppresses the generation of annoying current noises. Advantageous refinements and improvements of the invention indicated in the independent claims are made possible by the measures mentioned in the dependent claims. More precise details are given from the following description of exemplary embodiments. Drawings An example of embodiment of the invention is shown below in the drawing and is explained with more detail in the following description. In the drawing, FIG. 1 shows a section representation of a combined cylinder for service brake and spring-loaded brake according to a preferred embodiment of the invention having a venting valve; Fig. 2 the vent valve of Fig. 1 in the closed position; Fig. 3 the vent valve of Fig. 1 in an open position during the application of the parking brake; Fig. 4 the vent valve of Fig. 1 in an open position during the release of the parking brake. DESCRIPTION OF THE EXEMPLARY EMBODIMENT FIG. 1 shows, for exemplary explanation, a combined cylinder 1 for the service brake and the accumulator spring brake, hereinafter referred to as a combined cylinder. The combined cylinder consists of a service brake cylinder 2 and an accumulator spring brake cylinder 4 connected to it constructively and functionally. The service brake cylinder 2 and the accumulator spring brake cylinder 4 are separated from one another by an intermediate wall 6. Inside the spring-loaded brake cylinder 4 An accumulator spring brake piston 8 is disposed in a displaceable manner, wherein a force accumulator spring 10 rests on one side of the accumulator spring brake piston 8. The force accumulator spring 10 rests on its opposite end at the bottom of the accumulator spring brake cylinder 4. Between the accumulator spring brake piston 8 and the intermediate wall 6 there is formed an accumulator spring brake chamber 12 which is connected to a pressure regulator module which is not shown for the purpose of scale, in order to inject and extract the air. In the case of air injection, the accumulator spring brake piston 8 is displaced axially, applying pressure to the force accumulation spring 10, to the released position of the parking brake. During this displacement of the accumulator spring brake piston 8, the air present inside the spring chamber 14 which receives the force accumulator spring 10 through a vent valve 16 is expelled. But if the air is withdrawn from the spring chamber 12 for braking, then the force accumulation spring 10 can push the accumulator spring brake piston 8 to the brake application position. The accumulator spring brake piston 8 is connected to a hollow piston rod 8 which extends to through the intermediate wall 6 to a service brake chamber 20 of the service brake cylinder 2. A seal 22 inserted in the intermediate wall 6 seals against the external wall of the piston rod 18 during its longitudinal displacement. In the operating brake chamber 20 an inlet 23 opens through which the entry and exit of compressed air for the actuation of the service brake cylinder 2 is allowed. The compressed air acts on a membrane 24 inserted inside the service brake cylinder 2 on the opposite side of which a pressure element in the form of a membrane plate 26 is provided. The membrane plate 26 is connected to a pressure rod 28 which acts together with a brake actuation mechanism on the outside of the combined cylinder 1. This can be, for example, the drive elements of a disc brake of a motor vehicle. The service brake cylinder 2 is an active brake cylinder, ie, the service brake is applied by air injection to the service brake chamber 20 and released by air extraction. A return spring, not shown, resting on one side on the diaphragm plate 26 and on the other at the bottom of the accumulator spring brake cylinder 2, returns the pressure rod 28 to the released position when evacuated. the brake chamber 20 service The vent valve 16 is disposed at the end of the piston rod 18 which shows in the opposite direction the accumulator spring brake piston 8 and, more precisely, housed in the cavity 32 thereof. In this, of course, an emergency release device 34 is also arranged, which in this context is not interesting, but the cavity 32 of the piston rod 18 may be in communication with the spring chamber 14. The ventilation valve 16 of the combined service brake cylinder and the spring-loaded accumulator brake exhibits the following characteristics according to FIG. 2: a) a piston 38 is provided which carries a valve body 36 which is guided in axially displaceable manner; a cylinder 40, formed in the piston rod 18, b) at least one pressure spring 42 which abuts the piston 28 pushes the valve body 36 against a first valve seat in the piston 38 and against a second seat 48 of valve in the cylinder 40, c) the valve body 36 is charged by the pressure in the spring chamber 14 in a direction separating it from the first valve seat 44 and the second valve seat 48, d) the plunger 38 is loaded by the pressure in the service brake chamber 20 in a direction pushed by the first valve seat 44 against the valve body 36 and separating the valve body 36 from the second valve seat 48, e) between the plunger 38 and the bottom 74 of the cylinder 40 a third valve seat 46 is formed, where f) there is at least one position of the plunger 38 in which the first valve seat 44 is separated from the valve body 36, the valve body 36 seals against the second seat 48, the plunger 38 is separated from the third valve seat 46 and is then charged by the pressure of the service brake chamber 20 in a direction separating the first valve seat 44 from the valve body 36 and / or, as the valve body 36 is separated from the second valve seat 48, a current connection is established between the service brake chamber 20 and the spring chamber 14. As seen from Fig. 2 to Fig. 4, the plunger 38 has essentially three sections; a first piston section facing the spring chamber 14 with a first piston plate 54 in which a first piston surface 50 and a second piston surface 52 are formed; a second piston section that follows it which is configured as piston rod and a third piston section that is configured as a second piston plate 58 in which a third piston surface 60 and a fourth piston surface 62 are configured. The cylinder 40 is clamped in the cavity 32 of the plunger rod 18 rotationally and axially. The piston 40 is axially guided essentially by the second piston plate 48 in the cylinder 40., however, not having a sealed guide, but a narrow annular channel 59 is formed between the external radial circumferential surface of the second piston plate 58 and the internal radial circumferential surface of the cylinder 40 through which the compressed air can flow . Between the third plunger surface 60, the internal radial circumferential surface of the cylinder 40 and an additional bottom 64 of the cylinder 40 is formed by a first chamber 66, the bottom 64 of the cylinder 40 having a central passage opening through which the first piston plate 54. On its surface showing towards the first chamber 66, the second valve seat 48 is formed in the bottom 64 of the cylinder 40. The first valve seat 44 is located on the second piston surface 52 of the piston 38 that shows towards the first chamber 66. In the first chamber 66 there is furthermore accommodated the pressure spring 42 which rests on one side on the body 36. of valve and on the other in the third piston surface 60 in the second piston plate 58. The pressure spring is installed in pre-loaded form. The valve body 36 is preferably configured as a ring that surrounds the piston rod 56, whose external diameter is smaller than the internal diameter of the cylinder 40, so that an open annular gap exists between the ring 36 and the cylinder 40. The ring 36, therefore, seals only in axial direction against the first valve seat 44 in the first piston plate 54, respectively, against the second valve seat 48 in the bottom 64 of the cylinder 40. By at least one bore 68 of radial passage in the cylinder 40, the first chamber 66 is always in current contact with an annular chamber 70, that is, in any axial position of the plunger 38. This axial chamber 70 surrounds the cylinder 40 and is connected, in turn, through at least one bore 72 of radial passage in the piston rod 18 with the service brake chamber 20. In addition, a third chamber 76 is formed between the second piston plate 58 and the bottom 74 of the cylinder 40. In FIG. 2, the ventilation valve 16 is shown in the closed position, ie the ring 36 is supported the first valve seat 44 and in the second valve seat 48 so as to seal axially and that there is no current connection between the cavity 32 of the piston rod 18 - which is under the pressure of the spring chamber 14, and the annular chamber 70, which is connected to the service brake chamber 20. The piston 38 also closes in this position against the third valve seat 46, so that there is no current contact between the third chamber 76 and the first chamber 66. Starting from this state, in which neither the service brake nor the The parking brake is activated, the parking brake is now applied while the service brake is still released. Due to the accumulator spring brake piston 12 the spring chamber 14 is suddenly enlarged, whereby the pressure is reduced there strongly, for example, below the atmospheric pressure. With this, the relatively low pressure of the spring chamber 14, the second piston surface 52 and the third piston surface 60 are now charged by the pressure of the corresponding service brake chamber 20 on the first piston surface 50. , approximately, at atmospheric pressure. Due to the difference in pressure the piston 38 is displaced, in FIG. 3, against the effect of the first pressure spring 42 which is shortened, whereby the first valve seat 44 separates from the ring 36 and releases a cross section for the current, whereby air can flow from the service brake chamber 20 through the passage bore 72 in the piston rod 18 to the annular chamber 70, thence through the bore 68 of radial passage in the cylinder 40 to the first chamber 66 and from there finally to the cavity 32 of the piston rod 18, which in turn is in contact allowing to pass the pressure with the spring chamber 14. Therefore, a pressure compensation can be presented between the spring chamber 14 and the service brake chamber 20. In contrast, the ring 36 is pressed so as to seal against the second valve seat 48 in the bottom 64 of the cylinder 40 because of the effect of the pressure spring 42. Due to the displacement of the plunger 38 in FIG. 3 to the right, this is separated from the third valve seat 46, whereby a current connection is created between the annular channel 59 - which is under the pressure of the service brake chamber - and the third chamber 76 which, due to this, it receives little by little this pressure, which corresponds approximately to the atmospheric pressure. This results in an additional pressing force, acting in the figure to the right on the plunger 38, which is thereby loaded in a direction separating the first valve seat 44 from the valve body 36.

The pressure in the spring chamber 14, which increases little by little, also presses the third piston surface 60, so that the piston 38 is displaced in FIG. 3 to the left because of the pressure force that results therefrom. , until the first valve seat 44 stops and seals again in the ring 36. Simultaneously, the piston 38 again abuts the valve seat 46 in the bottom 74 of the cylinder 40. This displacement is supported by the elastic force of the first spring 42, until the vent valve 16 is again in the closed position shown in Fig. 2. When the parking brake is opened, the pressure in the spring chamber 14 increases due to its reduction. As it is easy to imagine with the help of Fig. 4, this greater pressure acts on the ring 36, so that it moves to the left against the effect of the pressure spring 42, which is reduced. With this, the ring 36 is separated from both the first valve seat 44 and the second valve seat 48. Because the ring 36 does not seal radially neither against the cylinder 40 nor against the piston rod 56, but there always remains an annular gap, the compressed air can now flow from the spring chamber 14 through the cavity 32 of the piston rod 18, the first chamber 66, drilling 68 in the cylinder 40, the annular chamber 70 and the bore 72 passing in the piston rod 18 to the service brake chamber 14 having a lower pressure in comparison. Once the pressure compensation is performed between the spring chamber 14 and the service brake chamber 20, the ring 36 is conveyed to the right, because of the effect of the pressure spring 42, to the closing position, where it rests again, axially sealing, on the first valve seat 44 and on the second valve seat 48. Fig. 2 also characterizes a closing position of the ventilation valve 16 that occurs when the service brake is further actuated when the parking brake is applied. Such a situation results, for example, when starting against a decline. When the parking brake is applied, as already explained in relation to Fig. 3, the pressure in the spring chamber 14 decreases, which has the consequence that the plunger 38 is displaced to the right. Once the pressure is compensated between the spring chamber 14 and the service brake chamber 20, that is, by having a greater pressure in the spring chamber 14 upon entering the air of the service brake chamber 20, it is higher pressure and pressure spring 42 re-establish the closing position. If it is activated, starting from this additionally the service brake, then the pressure in the service brake chamber 20 increases. This increased service brake pressure then also exists in the first chamber 66, because the compressed air can reach there through the passage bore 72 in the piston rod 18, the annular chamber 70 and the passage bore 68 in the cylinder 40. This service brake pressure also acts on the ring 36, whereby it increases its sealing effect against the first valve seat 44 and the second valve seat 48 and supports the effect of the first pressure spring 42 which maintains ring 36 instead. List of reference symbols 1 Combined brake cylinder for service brake and spring brake accumulator 2 Service brake cylinder 4 Accumulator spring-loaded brake cylinder 6 Intermediate wall 8 Spring-loaded brake piston accumulator 10 Force accumulator spring 12 Brake chamber spring accumulator 14 Spring chamber 16 Ventilation valve 18 Piston cup 20 Service brake chamber 22 Seal 23 Inlet 24 Membrane 26 Membrane plate 28 Pressure bar 32 Cavity 34 Emergency release device 36 Valve body 38 Plunger 40 Cylinder 42 Pressure spring 44 First valve seat 46 Third valve seat 48 Second valve seat 50 First piston surface 52 Second plunger surface 54 Plunger first piston 56 Plunger piston 58 Second plate piston 59 Annular channel 60 Third piston surface 62 Fourth piston surface 64 Bottom 66 First chamber 68 Drilling Annular chamber Perforation of passage Fund Third chamber

Claims (6)

1. Combined cylinder of service brake and spring-loaded brake accumulator comprising: a) a membrane that can be put under pressure, arranged in a service brake cylinder housing, which delimits on one side a service brake chamber that can be charged with a service brake pressure and on the other side a chamber that houses a return spring, b) a force-accumulator spring piston, housed in a service brake cylinder and spring-loaded brake cylinder housing, which it can be actuated by a force accumulator spring, the piston being defined on one side by an accumulator spring brake chamber and on the other side by a spring chamber which houses a force accumulator spring, and the piston having a plunger rod. which carries a vent valve that constitutes or closes a current connection between the spring chamber and the service brake chamber, characterized in that the vent valve n exhibits the following features: c) a piston is provided to carry a valve body and is axially displaceable in a cylinder formed in a piston rod, d) at least one pressure spring that rests on the piston pushes the piston valve body against a first seat of valve in the piston and against a second valve seat in the cylinder, e) the valve body is under pressure loading in the spring chamber in a direction separating it from the first valve seat and the second valve seat , f) the plunger is under pressure loading in the service brake chamber in a direction that pushes the first valve seat against the valve body and separates the valve body from the second valve seat, with g) a current connection between the service brake chamber and the spring chamber is established as the valve body is separated from the first valve seat and / or the second valve seat.

2. Service brake cylinder and accumulator spring brake according to claim 1, characterized in that a third valve seat is formed between the piston and a bottom of the cylinder, there being at least one position of the piston in which the first seat valve is separated from the valve body, the valve body seals against the second valve seat, the piston is separated from the third valve seat and is then under load by the pressure in the service brake chamber in a direction that separates the first valve seat of the valve body.

3. Service brake and spring brake cylinder according to claim 2, characterized in that the piston is guided in the cylinder having a play under formation of an annular channel between the piston and the cylinder in which the pressure prevailing in the service brake chamber.

4. The service brake and spring-brake brake cylinders according to claim 3, characterized in that, since the piston is separated from the third valve seat at the bottom of the cylinder, the annular channel can be brought into contact with a chamber in a current connection. which is delimited by the piston and the bottom of the cylinder.

5. Service brake cylinder and accumulator spring brake according to at least one of the preceding claims, characterized in that the valve body is formed by a ring that seals axially and on which the pressure spring rests.

6. Service brake and spring-loaded brake cylinder according to at least one of the preceding claims, characterized in that the cylinder is formed inside the piston rod on the side of its end. SUMMARY The invention relates to a combined cylinder (1) for service brake and spring-loaded battery brake comprising: a) a membrane (24) which is arranged in a housing of the service brake cylinder (2) and which can receive a pressure, delimiting the membrane (24) referred on one side a brake chamber (20) that can receive a service brake pressure and on the other side a chamber that houses a return spring, b) a plunger (8) accumulator spring brake which is arranged in a case of the accumulator spring brake cylinder (4) and which can be activated by a power accumulation spring (10), delimiting the spring-loaded brake piston (8) accumulator referred to on one side a spring-loaded brake chamber (12) and on the other side a spring-loaded force chamber (14) accommodating a preloaded spring (10), and the spring-loaded accumulator brake (8) it has a plunger rod (18) which is equipped with a ventilation valve (16) which forms or closes a current connection between the spring chamber (14) and the service brake chamber (20), the cylinder being (1) combination of service brake and spring-loaded battery brake is characterized in that the valve (16) exhibits the following characteristics: c) a plunger (38) it is provided that it carries a valve body (36) and the referred piston (38) being guided axially displaceable in a cylinder (40) formed in a piston rod (18), d) at least one pressure spring (42) which it rests on the plunger (38) pushes the valve body (36) against a first valve seat (44) on the plunger (38) and against a second valve seat (48) on the cylinder (40), e) the valve body (36) is under pressure loading in the spring chamber (14) in a direction separating it from the first valve seat (44) and the second seat (48) valve, f) the plunger (38) is under pressure loading in the service brake chamber (20) in a direction that urges the first valve seat (44) against the valve body (36) and separating the valve body (36) from the second valve seat (48), in this case g) establishing a current connection between the service brake chamber (20) and the spring chamber (14) being established. the valve body (36) separated from the first seat (44) and / or when the valve body (36) has been separated from the second valve seat (48).