DE102007053129A1 - Hydraulic clamping unit with integrated pressure relief valve - Google Patents

Abstract

Hydraulic clamping unit having a piston (2) arranged in a hydraulically actuated cylinder housing (1), in which an overpressure valve (4) for overload protection is integrated, in that the overpressure valve (4) consists of a valve part (6) inserted in a cylindrical upper recess (5) ) fixed by a sleeve member (7) pressed therein.

Description

Field of the invention

The The invention relates to a hydraulic clamping unit with a in one arranged hydraulically acted cylinder housing Piston, in which a pressure relief valve for overload protection is integrated.

The Field of application of the present invention extends primarily on traction means, such as chain or belt drives, which are to achieve a maximum of efficiency and lifetime optimum preload need. Since the length of the traction means by Warming and wear changes, must whose preload are constantly readjusted. Serve this purpose inventive hydraulic clamping units.

From the DE 10 2004 048 281 A1 goes out a generic hydraulic clamping unit. This essentially consists of a cylinder housing in which an oil-pressure-loaded piston is arranged to be axially movable. The piston is additionally acted upon by a pressure spring arranged in the cylinder housing. Through a check valve in the cylinder housing gets additional oil in the cylinder housing for the purpose of adjustment of the piston. As a result, and by the compression spring, the piston is acted upon and can move in the direction of pulling means to tension this. If a traction mechanism drive passes through a resonance speed, increased loads of the traction mechanism occur. This in turn leads to pressure increases in Ölldbeaufschlagten cylinder housing, which can cause an overload under certain circumstances. To avoid this, an outwardly opening pressure limiting valve is provided in the piston head of the hydraulic clamping unit. The limit pressure from which opens the pressure relief valve is adjusted by the strength of the compression spring which presses a valve ball against a valve seat formed in the piston. The valve seat is formed by the shoulder of a stepped axial center bore in the piston crown.

adversely In this technical solution is that the manufacturing effort for the preparation of the center bore and valve seat because of here to maintain tight tolerances is quite high. The required stepped axial center hole can be only by several Making drilling steps by machining.

It is therefore the object of the present invention, a hydraulic Clamping unit of the generic type to that effect to further improve that the integrated overpressure valve in easy to produce without cutting with few manufacturing steps leaves.

The Task is based on a hydraulic clamping unit according to The preamble of claim 1 in conjunction with the characterizing one Characteristics solved. The subsequent dependent ones Claims give advantageous developments of the invention again.

The The invention includes the technical teaching that the piston side integrated pressure relief valve from a into a cylindrical one upper recess of the piston inserted valve member, the is fixed by a sleeve member pressed therein.

Of the Advantage of the invention is solution in particular in that the recess with respect to the State of the art made much larger diameter can be. For such a production is more suitable a molding process, so that the piston, for example, finished cast can be. In the context of the solution according to the invention forms the valve member to be inserted into this recess preferably a separate unit, which is pressed by the in the recess Sleeve element is fixed non-positively.

Preferably the sleeve element is cup-shaped, wherein in the bottom surface of a drain opening is provided. This drain is required possibly hydraulic fluid drained through the pressure relief valve dissipate to the outside.

The cup-shaped sleeve member accommodates according to a the invention improving measure at the same time the pressure spring required for the function of the pressure relief valve, Which in this respect the front side on the valve part on the one hand and on the bottom surface the cup-shaped sleeve member on the other hand to Plant comes. By this measure, the pressure spring housed protected and is along her stroke passed through the cup-shaped sleeve member.

advantageously, the upper recess of the piston is one of a breakthrough bounded to a lower recess releasing inner paragraph, in which the valve part comes to the front end to the plant. Such a the insertion depth for the valve part limiting inner paragraph can also be manufactured in the manufacture of the essentially sleeve-shaped piston by prototyping generate in a simple manner.

According to another measure improving the invention, it is proposed that the valve member is designed as a preassembled structural unit. In this respect, the valve member according to a preferred embodiment, a spring housed in a cup-shaped guide cage acted Ver closing ball for the valve seat include. According to According to another preferred embodiment, the valve member may comprise a spring loaded for the valve seat in a spring accommodated in an annular guide cage. In that regard, the valve member is flexibly designed with regard to the choice of the closure element.

in the Frame of the above-mentioned first preferred embodiment It is suggested that the breakthrough in the piston at the same time as well the valve seat of the valve member designed as a closure ball forms. In this respect, the separate embodiment of a valve seat be dispensed with the pre-assembled valve part.

advantageously, is the piston in addition to the hydraulic loading in cooperation with the cylinder housing also by a parallel Pressure spring acted upon, which according to a other measure further developing the invention at least partially from a lower recess of the substantially sleeve-shaped piston is surrounded and frontally on the inner shoulder of the piston to the plant comes.

Further, The measures improving the invention will be described below together with the description of a preferred embodiment of the invention with reference to the figures shown in more detail. It shows:

1 a longitudinal section through a hydraulic clamping unit with integrated pressure relief valve,

2 a longitudinal section of the piston of the hydraulic clamping unit with mounted pressure relief valve,

3 a detailed view of a valve member of the pressure relief valve in a first embodiment, and

4 a detailed view of a valve member of the pressure relief valve in a second embodiment.

According to 1 is the hydraulic clamping unit of a cylinder housing 1 with axially movable therein piston 2 formed, which with the cylinder unit 1 cooperates in the manner of a plunger. Bottom side of the cylinder housing 1 is a connection 3 intended for hydraulic loading. In the piston 2 is a pressure relief valve 4 integrated for overload protection.

According to 2 there is the pressure relief valve 4 essentially from a into a cylindrical upper recess 5 inserted valve part 6 that from one into the upper recess 5 pressed-in sleeve element 7 is fixed. The sleeve element 7 has a substantially cup-shaped shape and is bottom side with a drain opening 8th Mistake. About the drainage hole 8th this gets the pressure relief valve 4 passing hydraulic oil to the outside. The pot-shaped sleeve element 7 also houses a pressure spring 9 pointing to the valve part 6 acts. The overpressure spring 9 is so far between the bottom surface of the cup-shaped sleeve member 7 and the valve part 6 clamped on the front side.

The upper recess 5 of the piston 2 gets a breakthrough from you 10 to a lower recess 11 free-standing interior heel 12 limited. On the side of the upper recess 5 comes the valve part 6 on this inside paragraph 12 to the frontal installation. Opposite by the lower recess 11 comes on the inside paragraph 12 a compression spring 13 to the plant. The compression spring 13 is here completely within the lower recess 11 of the piston 2 accommodated.

The valve part 6 is designed as a preassembled unit and can be constructed, for example, according to the variants described below:
According to 3 there is the valve part 6 essentially from a closure ball 14 in a cup-shaped guide cage 15 is housed, with waiving a separate compression spring here also within the guide cage 15 integrated return spring for the closing ball 14 is provided. The locking ball 14 acts with a valve seat 17 together.

According to 4 there is the valve part 6 ' essentially from an annular guide cage 18 in which a spring acted upon closure disc 19 is housed. At the guide cage 18 is still a valve seat 20 molded, which with the shutter disc 19 interacts.

1

cylinder housing

2

piston

3

connection

4

Pressure relief valve

5

upper recess

6

valve part

7

sleeve member

8th

drain opening

9

About compression spring

10

breakthrough

11

lower recess

12

internal sales

13

compression spring

14

guide cage

15

ball Size

16

compression spring

17

valve seat

18

guide cage

19

sealing washer

20

valve seat

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102004048281 A1 [0003]

Claims (10)

Hydraulic clamping unit with a hydraulically actuated cylinder housing ( 1 ) arranged piston ( 2 ), in which a pressure relief valve ( 4 ) is integrated for overload protection, characterized in that the pressure relief valve ( 4 ) from a into a cylindrical upper recess ( 5 ) inserted valve part ( 6 ), which is supported by a sleeve element pressed in ( 7 ) is fixed. Hydraulic tensioning unit according to claim 1, characterized in that the sleeve element ( 7 ) has a cup-shaped shape, in the bottom surface of a drain opening ( 8th ) is provided. Hydraulic tensioning unit according to claim 1 or 2, characterized in that the cup-shaped sleeve element ( 7 ) a pressure spring ( 9 ), the front side of the valve member ( 6 ) and at the bottom surface of the pot-shaped sleeve element ( 7 ) comes to the plant. Hydraulic clamping unit according to claim 1, characterized in that the upper recess ( 5 ) of the piston ( 2 ) from a breakthrough ( 10 ) to a lower recess ( 11 ) free-standing inside paragraph ( 12 ) is limited, on which the valve part ( 6 ) comes to the front of the plant. Hydraulic clamping unit according to claim 1, characterized in that the valve part ( 6 ) one in a cup-shaped guide cage ( 14 ) accommodated spring-loaded locking ball ( 15 ) for a valve seat ( 17 ). Hydraulic clamping unit according to claim 1, characterized in that the valve part ( 6 ' ) one in an annular guide cage ( 18 ) accommodated spring loaded shutter disc ( 19 ) for a valve seat ( 20 ). Hydraulic clamping unit according to claim 1, characterized in that the valve part ( 6 ) is designed as a preassembled unit. Hydraulic clamping unit according to claim 1, characterized in that the Durchbuch ( 10 ) in the piston ( 2 ) the valve seat of the valve member ( 6 ). Hydraulic clamping unit according to one of the preceding claims, characterized in that the piston ( 2 ) in addition to the hydraulic loading by an at least partially from a lower recess ( 11 ) of the piston ( 2 ) surrounded compression spring ( 13 ) is acted upon, the front side on the inner shoulder ( 12 ) comes to the plant. Hydraulic clamping unit according to one of the preceding claims, characterized in that the piston ( 2 ) is made of a steel by prototyping.