EP3234426B1 - Pressure-limiting valve - Google Patents

Description

The invention relates to a pressure relief valve according to the preamble of patent claim 1.

In known pressure relief valves, the housing is usually made of steel, in particular a solid steel block, with recordings for pressure adjustment and pressure medium channels must be drilled in the housing. In some cases, bores introduced for manufacturing reasons must also be closed again, since they were only necessary for the production of the boreholes required for operation and would be a hindrance to operation. This customary procedure is complicated in terms of manufacturing technology and therefore cost-intensive.

Out DE 198 04 752 A1 a generic pressure relief valve according to the preamble features of claim 1 is known.

Out DE 196 044 356 A1 a valve is known with a housing made of nodular cast iron, in which a valve seat made of stainless steel is poured. The valve seat is induction hardened subsequently in the cast-in and machined state in the housing.

From the EP 0 698 757 A2 For example, a valve is known in which a stainless steel ring forming the valve seat is welded into a nodular cast iron housing and the seat surface of the stainless steel valve seat is laser hardened.

From the DE 10 2004 040 359 B4 a general pressure regulating valve is known, the housing is made by a casting process. In the production of the housing are required pressure fluid channels and recordings in a cost effective manner with produced, but the valve disclosed there has a very large footprint, not least because of a valve seat accessible from both sides. However, this accessibility of the valve seat is required in the method disclosed there for hardening the valve seat, the work hardening, on the one hand to carry out the work hardening by means of suitable tools, but also to a required after the work hardening machining finishing by means of suitable tools such as milling cutters allow to ensure the dimensional accuracy of the valve seat.

In contrast, the invention is based on the object to provide a pressure relief valve that can be produced in a cost effective manner.

This object is achieved by a pressure relief valve having the features of patent claim 1.

Advantageous developments of the pressure relief valve according to the invention are described in the further subclaims.

A pressure relief valve according to the present invention includes a housing and a valve seat formed in the housing, which is closable via a spring-loaded closing element of the pressure relief valve. According to the invention, the housing consists of spheroidal graphite cast iron, in particular GGG or GJS - called "nodular cast iron", wherein the housing is surface-hardened at least in a region of the valve seat.

Surface hardening includes hardening processes such as induction hardening, laser hardening or flame hardening.

An advantage of the pressure relief valve according to the invention is that pressure fluid channels and other recordings are produced during casting of the housing and not after completion of the housing must be made by machining, the surface hardening is a cost-hardening method, because because of the good dimensional accuracy of a machining finishing is usually not necessary or at least keeps within narrow limits and thus reduces a tool use.

The housing is advantageously produced by means of a precision or investment casting process, such as, for example, a lost wax process, in particular with a wax model enveloped in refractory molding material. As a result, an increased dimensional stability can be achieved, which reduces a tool insert for a subsequent machining. Further, for example, sand cores, made of sand and phenolic resin, as well as so-called print cores, made of plastic after the rapid prototyping and / or rapid manufacturing process can be used.

At least one, in particular blind-hole-shaped, receptacle is advantageously provided in the housing, in which at least partially the pressure adjustment device is arranged, wherein the receptacle contains the valve seat. As a result, a compact and space-saving design of the pressure relief valve can be realized. Furthermore, a simplified production of the housing and thus of the pressure limiting valve can be achieved.

Preferably, the receptacle is approximately rotationally symmetrical. As a result, in particular rotating tools can be introduced into the receptacle, for example, for an optionally required post-processing of the valve seat before or after the surface hardening. In addition, thus can introduce a thread into the receptacle over which the pressure adjustment can be mounted in the receptacle. More preferably, the receptacle is formed as a recess in the housing.

The above-mentioned surface hardening has, in addition to the above-mentioned advantages, the further advantage that because of the resulting reduced use of tools for post-processing, a significantly more compact and space-saving arrangement, in particular of the pressure adjustment device and the receptacle in the housing, can be selected. In particular, the valve seat can be arranged in such a way that it is accessible exclusively from a single side, in particular via the receptacle, for surface hardening, in particular by means of a tool, and / or for post-processing by means of a tool, in particular essentially in the closing direction of the closing element ,

Advantageously, the closing element has a closing cone, from which, starting in the closing direction, a guide piston is arranged on the closing element. The closing cone, in particular a contact surface of the closing cone, is in the closed state of the closing element in contact with the valve seat. Advantageously, the closing element and the guide piston are integrally formed.

Advantageously, starting from the closing cone, opposite to the closing direction, a spring plate of the pressure adjusting device is arranged, in particular adjacent to, the closing element.

The closing element and the spring plate can be formed in one piece or in several pieces.

Advantageously, a transition of the receptacle between the spring plate and the valve seat is at least partially conical. In particular, the transition from a region of the spring plate in a closed position of the closing element to the valve seat is formed at least partially conically tapering. Due to the inventive design of the transition, the housing is weakened less. In particular, compared to a transition with constant diameter in the design of the transition according to the invention, more housing material remains between the receptacle and a fastening recess provided adjacent to the receptacle in the housing, with which the pressure limiting valve can be fastened on or between two plates. Advantageously, a plurality of mounting recesses are provided in the housing, which are preferably formed as through holes to attach the pressure relief valve in a simple manner, for example with through bolts. More preferably, the spring plate is formed on a portion which protrudes beyond a spring of the pressure adjustment, tapered in the closing direction.

The diameter of the receptacle may decrease in the closing direction, in particular gradually and / or continuously.

Preferably, the pressure relief valve is directly controlled, which further favors a compact and space-saving design of the pressure relief valve according to the invention.

Advantageously, in the housing two substantially mirror images of each other arranged receptacles are provided. In this case, in each of the receptacles - as described above - at least partially arranged a Druckverstelleinrichtungen. Next, the valve seat - as described above - included in each of the shots. With this arrangement, in a space-saving manner, a respective pressure in two independent pressure medium circuits can be limited to the value set at the respective pressure adjustment device. Alternatively, the two pressure relief valves may be fluidly connected in series.

Several embodiments of a pressure relief valve according to the invention are shown in the drawings. With reference to the figures of these drawings, the invention will now be explained in more detail.

• Figur 1 in einem Längsschnitt eine Vorderansicht eines erfindungsgemäßen Druckbegrenzungsventils gemäß einem ersten Ausführungsbeispiel, und
• Figur 2 in einem Längsschnitt eine Vorderansicht eines erfindungsgemäßen Druckbegrenzungsventils gemäß einem zweiten Ausführungsbeispiel.

Show it:

• FIG. 1 in a longitudinal section a front view of a pressure relief valve according to the invention according to a first embodiment, and
• FIG. 2 in a longitudinal section a front view of a pressure relief valve according to the invention according to a second embodiment.

This in FIG. 1 illustrated first embodiment of a pressure relief valve 1 according to the invention comprises a housing 2, in which a receptacle 4 is provided for a provided in the housing 2 pressure adjustment device 6.

The pressure adjustment device 6 includes a reducer 8, a spring 10 which can be preloaded therein, and a spring plate 12. Here, the spring plate 12 is formed integrally with a spring-loaded closing element 14 which, starting from the spring plate 12 in the closing direction 24, has a closing cone 16 and a guide piston 18.

The reducer 8 is screwed into the receptacle 4, wherein in the receptacle 4 an internal thread is provided and a corresponding external thread is provided on the reducer 8.

The receptacle 4 contains 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 to a sealing function between the valve seat 20 and closing cone 16 permanently ensure and thus increase a life of the pressure relief valve.

About the spring 10, the closure member 14 is biased in its closing direction 24 against the valve seat 20.

The transition 22 is formed in the closing direction 24 tapered. The spring plate 12 is formed at its projecting beyond the spring 10 section in the closing direction 24 tapered.

Based on the position of the spring plate 12 in its closed position in the receptacle 4 for the pressure adjusting device 6, the transition 22 is arranged in the closing direction 24 of the closing element 14 to the valve seat and further in the closing direction 24 of the guide piston 18 is arranged in the receptacle 4. In its closed position, the closing cone 16 is in contact with a contact surface with the valve seat 20 and seals a high-pressure side against a low-pressure side.

Between the guide piston 18 and the closing cone 16, a rod portion of the closing element 14 is arranged with a reduced diameter compared to the guide piston 18 and / or the contact surface of the closing cone 16. With the receptacle 4, the rod portion defines an annular space 26 and the guide piston 18th a piston chamber 28, wherein between the guide piston 18 and receptacle 4, an annular gap is provided. The annular gap serves to equalize the pressure medium between the annular space 26 and the piston chamber 28 as soon as the closing element moves in the receptacle. The size of the annular gap determines a degree of damping, with which the movement of the closing element 14 is damped in the receptacle 4, as it is in the interaction of spring 10 and closing element 14, in particular with the spring plate 12, physically considered a spring / mass system that could otherwise swing undamped.

In the annular space 26 and in the piston chamber 28 there is a high pressure and in a counter to the closing direction 24 adjacent to the valve seat 22 arranged pressure medium chamber 30, there is a low pressure. Exceeds the high pressure in conjunction with the closing element 14 has a value corresponding to the equivalent of the spring 10, the closing element 14 is lifted against the closing direction 24 with its closing cone 16 of the valve seat 20 and pressure medium can via the pressure medium chamber 30 in a pressure medium sink (not shown ) flow away. The high pressure is thus limited to the value corresponding to the equivalent of the spring 10, wherein the value is adjustable or adjustable.

In the in FIG. 2 shown second embodiment of the pressure relief valve 1 according to the invention two pressure adjustment devices 6, each with an associated receptacle 4 are arranged substantially mirror-inverted in the housing 2.

The receptacles 4 shown in the second embodiment correspond to those in FIG FIG. 1 shown and described above recording 4 of the first embodiment. The pressure adjusting devices 6 used in the second embodiment largely correspond to those in FIG FIG. 1 shown and described above pressure adjusting device 6 of the first embodiment, wherein two different variants of multi-piece closing elements 14 and spring plates 12 are shown. Below, these different variants will be described.

When in the left side of the drawing shown in the drawing, the spring plate 12 and the closing element 14 are formed in such a multi-piece that a spherical end portion of the closing element 14 comes with a correspondingly shaped mating surface of the spring plate 12 in abutment. As a result, alignment errors between the spring 10 or the spring plate 12 and the closing element 14 can advantageously be compensated.

In the variant shown on the right side in the drawing, the spring plate 12 and the closing element 14 are formed in such a way that a cylindrical end portion of the closing element 14 comes into contact with a correspondingly formed counter surface of the spring plate 12. The spring plate 12 is formed here approximately hat-shaped. As a result, the closing element 14 with its cylindrical end section can be guided well in the spring plate 12.

Disclosed is a pressure relief valve with a cast housing, the valve seat is surface hardened. In this way, an advantage of a cost-effective production of the housing with internal pressure fluid channels recordings, especially for a pressure adjustment, combined with an advantage of a durable sealing function, ensures a safe procedure to be performed, which requires - because of its good dimensional stability - only a reduced post-processing , Because of this requirement, a more compact and thus space-saving arrangement of housed in the housing functional areas, in particular a pressure adjustment device and an associated receptacle, allows. In particular, a valve seat can be arranged such that it is accessible exclusively from a single side for surface hardening and / or for post-processing by means of a tool, in particular essentially in the closing direction of the closing element.

LIST OF REFERENCE NUMBERS

1

Pressure relief valve

2

casing

4

admission

6

Druckverstelleinrichtung

8th

reducer

10

feather

12

spring plate

14

closing element

16

closing cone

18

guide piston

20

valve seat

22

crossing

24

closing direction

26

annulus

28

piston chamber

30

Pressure fluid chamber

Claims (9)

1. Pressure-limiting valve having a housing (2) and having a valve seat (20) which is formed in said housing and which can be closed by means of a spring-loaded closing element (14) of the pressure-limiting valve,
   characterized in that the housing (2) is composed of cast iron with spheroidal graphite, wherein the housing (2) is surface-hardened at least in a region of the valve seat (20).
2. Pressure-limiting valve according to Claim 1, wherein, in the housing (2), there is provided a receptacle (4) in which a pressure adjustment device (6) is at least partially arranged, wherein the receptacle (4) comprises the valve seat (20).
3. Pressure-limiting valve according to Claim 2, wherein the valve seat (20) is accessible from a single side through the receptacle (4) for the surface-hardening and/or for finish machining by means of a tool.
4. Pressure-limiting valve according to one of claims 1 to 3, wherein the closing element (14) has a closing cone (16), a guide piston (18) being arranged on the closing element (14) in the closing direction (24) proceeding from said closing cone.
5. Pressure-limiting valve according to Claim 4, wherein a spring plate (12) of the pressure adjustment device (6) is arranged on the closing element (14) counter to the closing direction (24) proceeding from the closing cone (16).
6. Pressure-limiting valve according to Claim 5, wherein the closing element (14) and the spring plate (12) are in single-part or multi-part form.
7. Pressure-limiting valve according to Claim 5 or 6, wherein a transition (22) of the receptacle (4) between the spring plate (12) and the valve seat (20) is at least partially of conical form.
8. Pressure-limiting valve according to one of the preceding claims, which is directly controlled.
9. Pressure-limiting valve according to one of Claims 2 to 8, wherein two receptacles (4) are provided substantially mirror-symmetrically with respect to one another in the housing (2).

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