Pressure-Limiting Valve

Abstract

A pressure-limiting valve includes a housing and a pressure adjustment device provided therein. The pressure-limiting valve further includes a valve seat arranged in the housing and configured to be closed by a spring-loaded closing element of the pressure adjustment device. The housing is composed of cast iron having spherical graphite. The housing is surface-hardened at least in a region of the valve seat.

Claims

1. A pressure-limiting valve comprising: a housing; a spring-loaded closing element; and a valve seat formed in said housing and configured to be closed by the spring-loaded closing element wherein the housing is composed of cast iron with spheroidal graphite, and wherein the housing is surface-hardened at least in a region of the valve seat.

2. The pressure-limiting valve as claimed in claim 1, further comprising: a receptacle formed in the housing, wherein a pressure adjustment device is at least partially arranged in the receptacle, and wherein the receptacle includes the valve seat.

3. The pressure-limiting valve as claimed in claim 2, wherein the valve seat is arranged approximately in a closing direction of the closing element proceeding from the pressure adjustment device.

4. The pressure-limiting valve as claimed in claim 2, wherein the valve seat is accessible from a single side through the receptacle for the surface-hardening and/or for finish machining by a tool.

5. The pressure-limiting valve as claimed in claim 3, wherein: the closing element has a closing cone, and a guide piston is arranged on the closing element in the closing direction proceeding from said closing cone.

6. The pressure-limiting valve as claimed in claim 5, wherein further comprising: a spring plate of the pressure adjustment device arranged on the closing element counter to the closing direction proceeding from the closing cone.

7. The pressure-limiting valve as claimed in claim 6, wherein the closing element and the spring plate are in single-part or multi-part form.

8. The pressure-limiting valve as claimed in claim 6, wherein a transition of the receptacle between the spring plate and the valve seat is at least partially of conical form.

9. The pressure-limiting valve as claimed in claim 1, wherein the valve is constructed in the manner of an intermediate plate.

10. The pressure-limiting valve as claimed in claim 1, wherein the valve is directly controlled.

11. The pressure-limiting valve as claimed in claim 2, wherein the receptacle is a first receptacle and the pressure-limiting valve further comprises: a second receptacle, wherein the first receptacle and the second receptacle are provided substantially mirror-symmetrically with respect to one another in the housing.

12. A method of forming a pressure-limiting valve including a housing, a spring-loaded closing element, and a valve seat, the method comprising: forming the housing from cast iron with spheroidal graphite; forming the valve seat in the housing; and surface-hardening the housing at least in a region of the valve seat, wherein the valve seat is configured to be closed by the spring-loaded closing element.

13. The method of claim 12, further comprising: accessing the valve seat from a single side of the housing through the receptacle with a tool for the surface-hardening.

Description

[0025] In the figures:

[0026] FIG. 1 shows, in a longitudinal section, a front view of a pressure-limiting valve according to the invention as per a first exemplary embodiment, and

[0027] FIG. 2 shows, in a longitudinal section, a front view of a pressure-limiting valve according to the invention as per a second exemplary embodiment.

[0028] The first exemplary embodiment of a pressure-limiting valve 1 according to the invention as illustrated in FIG. 1 comprises a housing 2 in which there is provided a receptacle 4 for a pressure adjustment device 6 which is provided in the housing 2.

[0029] The pressure adjustment device 6 comprises a reduction piece 8, a spring 10 that can be preloaded therein, and a spring plate 12. Here, the spring plate 12 is formed as one part with a spring-loaded closing element 14, which has a closing cone 16 and a guide piston 18 in a closing direction 24 proceeding from the spring plate 12.

[0030] The reduction piece 8 is screwed into the receptacle 4, wherein an internal thread is provided in the receptacle 4 and a corresponding external thread is provided on the reduction piece 8.

[0031] The receptacle 4 comprises a valve seat 20 and a transition 22 from a region of the spring plate 12 in a closed position of the closing element 14 to the valve seat 20. In the region of the valve seat 20, the housing 2 is surface-hardened in order to permanently ensure a sealing function between valve seat 20 and closing cone 16 and thus increase a service life of the pressure-limiting valve.

[0032] The closing element 14 is preloaded in its closing direction 24 against the valve seat 20 by means of the spring 10.

[0033] The transition 22 is formed so as to taper conically in the closing direction 24. The spring plate 12 is, at its section which projects beyond the spring 10, formed so as to taper conically in the closing direction 24.

[0034] Proceeding from the position of the spring plate 12 in its closed position in the receptacle 4 for the pressure adjustment device 6, the transition 22 to the valve seat is arranged in the closing direction 24 of the closing element 14, and further in the closing direction 24, the guide piston 18 is arranged in the receptacle 4. In its closed position, the closing cone 16 is in contact, by means of a contact surface, with the valve seat 20, and seals off a high-pressure side with respect to a low-pressure side.

[0035] Between the guide piston 18 and the closing cone 16, there is arranged a rod section of the closing element 14 with a reduced diameter in relation to the guide piston 18 and/or the contact surface of the closing cone 16. With the receptacle 4, the rod section delimits a ring-shaped chamber 26, and the guide piston 18 delimits a piston chamber 28, wherein a ring-shaped gap is provided between guide piston 18 and receptacle 4. The ring-shaped gap serves for pressure medium equalization between the ring-shaped chamber 26 and the piston chamber 28 as soon as the closing element moves in the receptacle. The size of the ring-shaped gap determines a degree of damping with which the movement of the closing element 14 in the receptacle 4 is dampened, because the interaction between spring 10 and closing element 14, in particular with the spring plate 12, constitutes in physical terms a spring/mass system which could otherwise oscillate in undampened fashion.

[0036] A high pressure prevails in the ring-shaped chamber 26 and in the piston chamber 28, and a low pressure prevails in a pressure medium chamber 30 which is arranged adjacent to the valve seat 22 counter to the closing direction 24. If the high pressure in interaction with the closing element 14 exceeds a value which corresponds to the equivalent of the spring 10, the closing element 14 is lifted with its closing cone 16 from the valve seat 20 counter to the closing direction 24, and pressure medium can flow out via the pressure medium chamber 30 into a pressure medium sink (not illustrated). The high pressure is thus limited to the value that corresponds to the equivalent of the spring 10, wherein the value is settable or adjustable.

[0037] In the second exemplary embodiment of the pressure-limiting valve 1 according to the invention shown in FIG. 2, two pressure adjustment devices 6 with a respectively associated receptacle 4 are arranged in substantially mirror-symmetrical fashion in the housing 2.

[0038] The receptacles 4 illustrated in the second exemplary embodiment correspond to the receptacle 4 of the first exemplary embodiment as shown in FIG. 1 and described above. The pressure adjustment devices 6 used in the second exemplary embodiment substantially correspond to the pressure adjustment device 6 of the first exemplary embodiment as shown in FIG. 1 and described above, wherein two different variants of closing elements 14 and spring plates 12 of multi-part design are illustrated. These different variants will be described below.

[0039] In the variant illustrated on the left-hand side in the drawing, the spring plate 12 and the closing element 14 are of multi-part form, such that a spherical end section of the closing element 14 comes into contact with a correspondingly formed counterpart surface of the spring plate 12. In this way, it is advantageously possible for alignment errors between the spring 10 or the spring plate 12 and the closing element 14 to be compensated.

[0040] In the variant illustrated on the right-hand side in the drawing, the spring plate 12 and the closing element 14 are of multi-part form such that a cylindrical end section of the closing element 14 comes into contact with a correspondingly formed counterpart surface of the spring plate 12. Here, the spring plate 12 is of approximately hat-shaped form. In this way, the closing element 14 can be guided with its cylindrical end section in the spring plate 12 in an effective manner.

[0041] The invention discloses a pressure-limiting valve having a cast housing, the valve seat of which is surface-hardened. In this way, the advantage of inexpensive production of the housing with internal pressure medium ducts receptacles, in particular for a pressure adjustment device, combined with the advantage of a long-term sealing function, is ensured by means of a method which can be carried out in a reliable manner and which, owing to its good dimensional accuracy, requires only reduced finish machining, if any. Owing to this prerequisite, a more compact and thus space-saving arrangement of functional regions accommodated in the housing, in particular of a pressure adjustment device and of an associated receptacle, is made possible. In particular, a valve seat can be arranged so as to be accessible only from a single side, in particular substantially in a closing direction of the closing element, for the surface hardening and/or for finish machining by means of a tool.

LIST OF REFERENCE DESIGNATIONS

[0042] 1 Pressure-limiting valve

2 Housing

4 Receptacle

[0043] 6 Pressure adjustment device
8 Reduction piece

10 Spring

[0044] 12 Spring plate
14 Closing element
16 Closing cone
18 Guide piston
20 Valve seat

22 Transition

[0045] 24 Closing direction
26 Ring-shaped chamber
28 Piston chamber
30 Pressure medium chamber