DE102014203046A1 - Clamp for a traction drive with overpressure system in overhead construction - Google Patents

Abstract

The invention relates to a tensioner (1) for a traction mechanism drive of a motor vehicle with a stationary, first hollow body (2) and a displaceable, second hollow body (3) coupled thereto, wherein the two hollow bodies are coupled such that when a pressurized fluid flows in through a low-pressure space (4) and a downstream non-return valve (5) in a high-pressure chamber (6), the second hollow body (3) for zugmittelspannenden deflection of a clamping rail (7) is moved, wherein the check valve (5) is so integrated and dimensioned that in the pressure drop pressure fluid is fed back against the direction of flow into the low pressure space (4).

Description

Field of the invention

The invention relates to a tensioner, such as a chain or belt tensioner, for a traction mechanism of a motor vehicle, such as a car, a truck or other commercial vehicle, with a stationary, first hollow body and a displaceable second hollow body coupled thereto, wherein the two hollow bodies so coupled are that when inflow of pressurized fluid, such as oil, is moved by a low-pressure chamber and a downstream check valve in a high-pressure chamber of the second hollow body for zugmittelspannenden deflection of a clamping rail / is. Tensioning rails ensure sufficient long-term pre-stressing of the endless drawing means.

Traction drives use endless traction means such as belts or chains. They are used in particular in control and / or auxiliary drives on internal combustion engines.

However, the known in the art Endloszugmittelspanner also bring disadvantages. For example, when overhead hauling continuous tension tensioners, which is usually necessary on a bank of V-engines and boxer engines, when the engine is switched off hot, the endless tensioner tensioner may become idle. This can lead to start-up rattling at the following engine start, because the endless traction means tensioner briefly no oil is available and the piston can thus beat undamped in a so-called blocking position. This effect is possibly reinforced by possible leaks at the pressure relief valve.

The recorded in the piston and biased by a spring check valve is performed by a very well-defined outer diameter of the valve and a very accurately manufactured inner diameter of the piston so far. In this known embodiment, the volume of the high-pressure chamber is increased when a spring force is exceeded and then limited so that the maximum (chain) Spannerabstützkraft. However, this is only possible after a very elaborate production of the piston using Bohrungsschleifverfahren and precise valve production. This is very expensive.

It is the object of the present invention to eliminate the disadvantages of the prior art and to find an adaptation that allows a cost-effective, low-error and modular design. In particular, a hydraulically operating endless traction means tensioner is to be created, in which an overpressure valve is integrated in order to effectively prevent emptying of the endless traction tensioner. In this case, a cost-effective solution should be made available.

Disclosure of the invention

In a generic tensioner, such as a Endloszugmittelspanner for a traction mechanism, this object is achieved in that the check valve is integrated and dimensioned so that in the pressure drop, pressurized fluid is returned against the direction of flow into the low pressure chamber. By this embodiment, there is no danger, in particular when hot shutdown of the engine, that the endless tension medium tensioner idles. For a subsequent engine start there is therefore no tendency to start rattling, since the endless tension medium tensioner continuously enough oil is available. This rules out that the piston can beat unblocked in blocking position.

Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

Thus, the check valve of the tensioner can be mounted axially displaceable in the first hollow body. This allows the check valve to respond to the current load conditions by movement in the hollow body.

It is also advantageous if the non-return valve has play, allowing tilting, to be inserted into the first hollow body. This can quickly cause a pressure reduction.

Advantageous for the function of the invention is when a biasing unit, such as a mechanical spring, pressure applying acts on a valve housing of the check valve, approximately in the direction of the high-pressure chamber. A certain bias can then be used.

An advantageous embodiment is further characterized in that the valve housing sealingly seated with a sealing surface on an inwardly projecting portion of the first hollow body in normal operation and / or in the case of overpressure which lifts off from the biasing unit on the valve housing. The fluid flow can then be completely prevented effectively.

Also, the biasing unit may expediently be designed as a (mechanical) spring, for example as a compression spring, for example as a helical compression spring, and preferably supported on the valve housing on the one hand and on a high-pressure space-distant insert disk in the low-pressure space on the other hand. In the mentioned compression springs such as the helical compression springs are usually standardized standard parts. They are therefore easy to obtain or replace. Likewise, their characteristics are known, which leads to a reduced computational effort in modification or redesign.

It is possible that in the high pressure chamber, a second hollow body of the first hollow body wegdrängende biasing means, such as a compression spring, such as a coil spring, is present.

An improvement in the function can also be achieved in that between the valve housing and the inner wall of the first hollow body, a gap of about 0.05 mm to 0.7 mm, preferably about 0.15, 0.2, 0.25, 0.3 or 0.35 mm, is present.

It is also advantageous if the first hollow body is designed as a piston and is axially displaceably mounted in the second hollow body designed as a housing, for instance as a steel housing. Also, the piston can be connected in a fixed (aluminum) support structure.

The check valve is biased by means of a biasing unit designed as a spring and seals the high-pressure chamber from the supply space. If the pressure in the high-pressure chamber is increased by the collapse of the piston, the pressure in the high-pressure chamber exceeds the bias of the spring, tilts the valve and the pressure in the high-pressure chamber is effectively limited by the outflow of oil back into the supply. A bore grinding is eliminated and the piston is much cheaper to produce.

The invention will be explained in more detail below with the aid of a drawing in which a first embodiment is shown. Show it:

1 a first embodiment of a tensioner for a traction drive with overpressure system in overhead construction.

The figure is merely schematic in nature and is only for understanding the invention.

1 shows an axial cross-sectional view of a tensioner 1 , The tensioner 1 consists of a first hollow body 2 and a second hollow body 3 together. Both the first hollow body 2 as well as the second hollow body 3 are cylindrical in their shape / tubular / sleeve-shaped. The inner and outer diameter of the first hollow body 2 are smaller than the inner and outer diameter of the second hollow body 3 , The outer diameter of the first hollow body 2 is sized so that the first hollow body 2 in the second hollow body 3 can be pushed axially. The outer surface of the first hollow body 2 is sliding in the inner surface of the second hollow body 3 stored.

The smaller (first) hollow body 2 has in its interior a low pressure room 4 on at its lower end, which is the larger (second) hollow body 3 facing, a check valve 5 is appropriate. Pressurized fluid, such as oil, flows from the low pressure space 4 through the check valve 5 in a high pressure room 6 , which in the interior of the adjacent Hohlköpers 3 is trained. This will cause the hollow body 3 for zugmittelspannenden deflecting an only indicated clamping rail 7 emotional.

The check valve 5 is so integrated and dimensioned that in the overpressure pressure fluid against the inflow into the low pressure space 4 is returned. The check valve 5 is game-related. It is in the second hollow body 3 installed that tilting the check valve 5 is possible. Due to this tilting, pressurized fluid can be returned to the low-pressure space 4 reach.

Above the check valve 5 (ie on the oil inflow side of the high pressure space 6 , between the high pressure room 6 and the low-pressure room 4 ) is in the first hollow body 2 a bias unit 8th , like a mechanical spring, installed. The bias unit 8th lies pressure applying approximately in the direction of the hollow body 3 on a valve body 9 the check valve 5 on.

The valve housing 9 sits with a sealing surface 10 on an inwardly projecting heel 11 of the hollow body 2 , In the event of overpressure, the sealing surface lifts 10 axially against the direction of the second hollow body 3 , as well as against the force of the biasing unit 8th from the paragraph 11 from. The support of the pretensioning unit 8th at the upper end of the hollow body 2 can through an insert disc 12 respectively. Between the valve body 9 and an inner wall 13 of the hollow body is then a (in 1 only indicated) gap 14 available.

As in the low pressure room 4 of the first hollow body 2 , is also in the high pressure room 6 of the second hollow body 3 a pretensioner / spring 15 , as in the manner of a compression-loaded coil spring, available.

The valve body of the check valve 5 is designed as a ball and, likewise, as the valve housing 9 , spring-biased, in this case on a sealing surface 10 training sealing seat urged.

LIST OF REFERENCE NUMBERS

1

 Stretcher

2

 First hollow body

3

 Second hollow body

4

 Low-pressure chamber

5

 check valve

6

 High-pressure chamber

7

 tensioning rail

8th

 Preload unit for valve housing

9

 valve housing

10

 sealing surface

11

 paragraph

12

 insert disc

13

 Inner wall of the first hollow body

14

 gap

15

 feather

Claims (10)

Stretcher ( 1 ) for a traction mechanism of a motor vehicle with a stationary, first hollow body ( 2 ) and a displaceable, second hollow body coupled thereto ( 3 ), wherein the two hollow bodies are coupled in such a way that when a pressurized fluid flows in through a low-pressure space ( 4 ) and a downstream check valve ( 5 ) in a high pressure room ( 6 ), the second hollow body ( 3 ) for zugmittelspannenden deflecting a tensioning rail ( 7 ), characterized in that the check valve ( 5 ) is integrated and dimensioned in such a way that, in the overpressure situation, pressurized fluid is directed counter to the direction of inflow into the low-pressure space (FIG. 4 ) is returned. Tensioner according to claim 1, characterized in that the check valve ( 5 ) axially displaceable in the first hollow body ( 2 ) is stored. Tensioner according to one of claims 1 and 2, characterized in that the check valve ( 5 ) play and / or a tilting enabling in the first hollow body ( 2 ) is used. Tensioner according to one of claims 1 to 3, characterized in that a biasing unit ( 8th ), applying pressure to a valve housing ( 9 ) of the check valve ( 6 ) acts. Tensioner according to claim 4, characterized in that the valve housing ( 9 ) with a sealing surface ( 10 ) to an inwardly projecting paragraph ( 11 ) of the first hollow body ( 2 ) is sealingly seated in normal operation and / or in the case of overpressure that of the biasing unit ( 8th ) on the valve housing ( 9 ) takes off. Tensioner according to claim 5, characterized in that the biasing unit ( 8th ) is designed as a spring. Clamping device according to one of claims 1 to 6, characterized in that in the high-pressure chamber ( 6 ) one the second hollow body ( 3 ) from the first hollow body ( 2 ) urging biasing means ( 15 ) is available. Tensioner according to one of claims 1 to 7, characterized in that between the valve housing ( 9 ) and the inner wall ( 13 ) of the first hollow body ( 2 ) A gap ( 14 ) of about 0.05 mm to 0.7 mm is present. Tensioner according to one of claims 1 to 8, characterized in that the first hollow body ( 2 ) is designed as a piston and axially displaceable in the housing formed as a second hollow body ( 3 ) is stored. Clamping device according to claim 9, characterized in that the piston on / in a fixed support structure on / is involved.

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