WO2008119621A1

WO2008119621A1 - Plate valve embodied as a check valve for a hydraulic system

Info

Publication number: WO2008119621A1
Application number: PCT/EP2008/052853
Authority: WO
Inventors: Wolfgang Lorz
Original assignee: Schaeffler Kg
Priority date: 2007-04-03
Filing date: 2008-03-11
Publication date: 2008-10-09
Also published as: DE102007016010A1

Abstract

The invention relates to a plate valve (8) that is preferably used as a check valve in a tensioning system or a hydraulic system. The plate valve (8) comprises a pot-shaped housing (2) for accommodating a displaceably disposed piston (3) that, along with the housing (2), limits a pressure chamber (4) filled with hydraulic fluid. For admitting the hydraulic fluid into the pressure chamber (4), openings (6a, 6b) are incorporated in the floor (5), said openings cooperating with a highly elastic valve disk (9) placed in the housing (2). In the case of a negative pressure in the pressure chamber (4), automatic lifting of the valve disk (9) in the region of the openings (6a, 6b) occurs due to the openings (6a, 6b), which are radially offset relative to a support surface of the spring means (7) on the valve disk (9).

Description

Name of the invention

Plate valve, designed as a check valve for a hydraulic system

description

Field of the invention

The invention relates to a plate valve, which is used in particular as a check valve in a hydraulic system. The construction of the plate valve comprises a rotationally symmetrical designed cup-shaped housing having at least one opening in a bottom for the entry of a hydraulic fluid. The opening is associated with a disk-like shaped valve body within the housing, which is spring-loaded against the ground.

Background of the invention

A hydraulic tensioning system for traction drives of internal combustion engines requires a fast response, in order to always ensure sufficient prestressing or damping, for example, in the case of high-frequency vibrations of the traction means. In accordance with this requirement, the non-return valves integrated in the clamping systems are to be designed so that, after the hydraulic fluid has been scavenged via a leakage gap within the clamping system, the pressure chamber can be briefly filled with hydraulic fluid via the supply line.

A clamping device with a closed hydraulic fluid circuit disclosed in US 49 40 447. In this device, the hydraulic fluid is replaced by a check valve for damping between a storage chamber and a pressure chamber. As a check valve is a rigid plate-shaped valve body which cooperates with a central opening for the hydraulic fluid. This arrangement can lead to unstable positions of the valve Body lead, as this is not supported over the entire surface. In addition, there is the risk of adverse noise for this arrangement.

From DE 10 2004 018 566 A1 a clamping device is known, which includes a disk-shaped valve body. The design concept provided here comprises at least three individual parts required to complete the check valve, each of which requires a complex manufacturing process.

Object of the invention

The invention has for its object to provide a space-optimized, inexpensive manufacturable check valve.

Summary of the invention

To solve this problem, the plate valve according to the invention comprises a directly acted upon by a spring means valve disc which cooperates with at least two openings of the housing outside a support region of a spring means. An opening of the plate valve takes place when the pressure prevailing at the bottom of the housing hydraulic fluid pressure exceeds the pressure within the housing, wherein the hydraulic fluid entering through the openings partially lifts the highly elastic valve disc from the ground. The valve body according to the invention, designed as a plate valve in the form of an elastic disc is inexpensive to produce. In the installed state, the valve body is permanently positionally positioned over the spring means and consequently requires no further guidance. The installation position has the effect that an outer peripheral region of the plate valve radially enclosing the support surface of the spring means lifts off freely in the event of a pressure difference that occurs and thus allows the hydraulic fluid to flow unhindered into the housing. The plate valve according to the invention is preferably used for cost-optimized clamping systems. Further advantageous embodiments of the invention are the subject of the dependent claims 2 to 8.

As a preferred material for the valve disc according to the invention is a rubber material or a plastic, such as HNBR provided. Valve discs made of this material meet all the fatigue strength and function requirements of a plate valve for clamping devices.

A desired fast response, d. H. optimum switching hysteresis of the plate valve is achieved by the largest possible distance between the outer contour of the spring means and the arrangement of the openings is provided in the bottom of the housing, which are covered by the plate valve. To achieve this aim, the spring means designed as a helical spring is supported on the valve disk with a conically tapering or retracted spring end. This measure causes a desired increased radial distance between the outer contour of the spring means and the openings in the bottom of the housing, which at the same time has an advantageous effect on the elasticity of the valve disc. For a relatively large housing bottom whose diameter clearly exceeds the diameter of the plate valve, a centered mounting position of the valve disc is recommended. For this purpose, the valve disk is preferably provided with centering lugs which bring about a centered installation position at the bottom of the housing.

A further embodiment of the invention includes a Stellwegbegrenzung or stroke limitation of the valve disc. For this purpose, offers a separate used in the housing flange. In the installed state of the spaced from the bottom of the housing, the valve disc radially overlapping board limits an opening degree of the edge zone of the valve disc. Brief description of the drawings

Two exemplary embodiments clarifying the invention will be described in more detail below. Show it:

Figure 1 is an integrated in a piston-cylinder unit of a hydraulic system according to the invention plate valve;

FIG. 2 shows an enlarged view of the arrangement of the plate valve according to FIG. 1.

Detailed description of the drawings

A piston-cylinder unit 1, which is part of a tensioning device or a hydraulic system, not shown, is shown in FIG 1. The piston-cylinder unit 1 comprises a cup-shaped, non-cutting, in particular produced by a thermoforming process housing 2, in which a piston is guided linearly displaceable. Together with the housing 2, the piston 3 delimits a pressure chamber 4 filled with a hydraulic fluid. To fill the pressure chamber 4 with a hydraulic fluid, openings 6a, 6b are introduced into a bottom 5 of the housing 2 and communicate with a supply line. The pressure chamber 4 serves to receive a designed as a helical compression spring spring means 7, which exerts a force in the arrow direction on the piston 3. Furthermore, a plate valve 8 is integrated in the pressure chamber 4, which includes a highly elastic valve disc 9 as a valve body. For the valve disc 9, an installation position is provided, in which the spring means 7 frictionally rests against the bottom 5 and at the same time covers the openings 6a, 6b. The spring means 7 is supported on the valve disc 9 via an annular surface defined by the diameter "d", the openings 6a, 6b being arranged outside the support surface of the spring means 7.

Below is a description of the operation of the plate valve 8. When a movement of the piston 3 in the opposite direction of the arrow, a partial amount of hydraulic fluid via a self-adjusting leakage gap 10 between a lateral surface of the piston 3 and an inner wall 11 of the housing 3 displaced from the pressure chamber 4. This adjusting movement of the piston 3 causes an increased pressure in the pressure chamber 4, whereby the valve disc 9 is pressed against the bottom 5 and thus the openings 6a, 6b effectively closes. In a direction of arrow directed adjusting movement of the piston 3 is formed in the pressure chamber 4, a pressure difference or a negative pressure, whereby the pending in the supply line hydraulic fluid via the openings 6a, 6b can flow into the pressure chamber 4. At the same time, the highly elastic valve disk 9 rises at least locally in the region of the openings 6a, 6b from the bottom 5 until pressure equalization between the supply line and the pressure chamber 4 is reached. Alternatively, the solution shown in FIG Piston-cylinder unit 1 to be provided with more than two openings in the bottom 5.

Further details of the piston-cylinder unit 1 are shown in FIG. 2. In order to achieve improved elasticity of the valve disk 9, the spring means 7 designed as a helical compression spring is supported on the valve disk 9 with a conically tapering spring end 12. This design of the spring means 7 has the consequence that sets a greater radial distance between a defined by the diameter "d" contact zone or support surface of the spring end 12 on the valve disc 9 and the position of the diameter marked by the "D" openings 6a, 6b , As travel limit for the opening region of the valve disc 9, a flange 13 is inserted into the housing 2. The flanged wheel 13 can also optionally include a board 14 which, offset from the base 5, has a radial overlap with the outer contour of the valve disk 9. The flanged wheel 13 limits a pivoting angle of the locally lifting area of the valve disk 9 in the region of the openings 6a, 6b, illustrated by the dash-dot area. The flange 13 secures the local lifting area of the valve disc 9 in particular in a pulse-like adjusting movement of the piston 3 in the arrow direction. The valve disc 9 is further provided in the region of the outer contour with symmetrically arranged centering lugs 15, over the a centered mounting position of the valve disc 9 relative to the flanged wheel 13 sets.

LIST OF REFERENCE NUMBERS

1 piston-cylinder unit

2 housings

3 pistons

pressure chamber

5 floor

6a opening

6b opening

7 spring means

8 plate valve

9 valve disc

10 leakage gap

11 inner wall

12 spring end

13 flanged wheel

14 board

15 centering nose

Claims

claims

1. plate valve, in particular used as a check valve in a hydraulic system, comprising a rotationssymmethsch designed, cup-like housing (2), for receiving a linearly displaceable piston

(3) which together with the housing (2) delimits a pressure chamber (4) filled with hydraulic fluid, at least one opening (6a, 6b) being provided for entry of the hydraulic fluid into a bottom (5) of the housing (2), is associated with a disk-like designed, spring-loaded valve body, characterized in that of a

Spring means (7) acted upon valve body is designed as a highly elastic valve disc (9) outside a support region of the spring means (7) with at least two openings (6a, 6b) of the housing (2) and the valve disc (9) ei at a pressure difference - ensures ne flow of hydraulic fluid in the pressure chamber (4).

2. Plate valve according to claim 1, characterized in that the valve disc (9) is made of a rubber material or a plastic, such as HNBR or RSHB.

3. plate valve according to claim 1, characterized in that the openings (6a, 6b) radially offset from an outer contour of a designed as a helical compression spring spring means (7) in the bottom (5) of the housing (2) are introduced.

4. plate valve according to claim 3, characterized in that the spring means (7) with a conically tapered spring end (12) on the valve disc (9) is supported.

5. plate valve according to claim 1, characterized in that the circular disc forming a valve disc (9) in the housing (2) or on the bottom (5) is centered.

6. plate valve according to claim 4, characterized in that the valve disc (9) arranged on the outside, an installation position of the valve disc (9) defining centering lugs (15) includes.

7. plate valve according to claim 1, characterized in that for the valve disc (9) at least in the region of the openings (6 a, 6 b) a Stellwegbegrenzung is provided.

8. plate valve according to claim 7, characterized in that in the housing (2) a flanged disc (13) is inserted, with one of the bottom (5) of the housing (2) spaced board (14) has an opening degree of the valve disc (9 ) limited.