# US 5,704,319 A · Hydraulic clearance compensation element for valve control units of internal-combustion engines

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- Number: US 5,704,319 A
- Document ID: US5704319A
- Status: Granted
- Kind: A
- Application number: 08/776,280
- Filed: 1997-01-14
- Granted: 1998-01-06
- Earliest claimed: 1994-08-06
- Assignees: INA Walzlager Schaeffler KG
- Inventors: Helmut Engelhardt; Dieter Schmidt
- Web page: https://patentgrep.com/patent/US5704319A

## CPC

- F01L 1/25: between cam and valve stem
- F01L 1/245: Hydraulic tappets
- F01L 1/46: Component parts, details, or accessories, not provided for in preceding subgroups
- F01L: CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES

## Abstract

The invention concerns a hydraulic play-compensation element including a groove (11) in the housing (1) to be located in such a way that, whatever the position of the plunger (2), a length (19) of the plunger is always supported by the cylinder wall above the groove and the securing ring (12) is centered radially around the plunger by means of a recess (14) in the plunger, the recess having a ramp at least at its lower end. The invention thus avoids weakening of the material in the upper part of the plunger.

## Claims

### Claim 1

A hydraulic clearance compensation element for valve control units of internal combustion engines comprising a piston (2) guided slidably in a housing (1), piston (2) and housing (1) defining therebetween a pressure chamber (5) which communicates through a one-way valve arranged on a lower end of the piston (2) with a reservoir (3) disposed within the piston (2), an elastic securing ring (12) being arranged in a circumferential groove (11) characterized in that the groove (11) is arranged in the housing (1) so that a piston supporting length (19) remains above the groove (11) in every position of lift of the piston (2), and a diameter of the groove (11 ) is larger than a diameter of the securing ring (12) which is radially centered by a recess (14) of the piston (2) comprising a ramp (10) at least at a lower end (FIGS. 1 and 3).

### Claim 2

A hydraulic clearance compensation element for valve control units of internal combustion engines comprising a piston (2) guided slidably in a housing (1), piston (2) and housing (1) defining therebetween a pressure chamber (5) which communicates through a one-way valve arranged on a lower end of the piston (2) with a reservoir (3) disposed within the piston (2), an elastic securing ring (12) being arranged in a circumferential groove (11), characterized in that the groove (11) is arranged in the piston (2) so that a piston supporting length (19) remains above the groove (11) in every position of lift of the piston (2), and a diameter of the groove (11) is smaller than a diameter of the securing ring (12) which is radially centered by a recess (14) of the housing (1) comprising a ramp (10) at least at an upper end (FIGS. 2 and 4).

### Claim 3 (depends on 1)

A hydraulic clearance compensation element of claim 1 wherein the securing ring (12) is configured as a polygonal ring (FIG. 6).

### Claim 4 (depends on 1)

A hydraulic clearance compensation element of claim 1 wherein the piston (2) comprises a bevel (10a) at a lower end (FIG. 1).

### Claim 5 (depends on 2)

A hydraulic clearance compensation element of claim 2 wherein the housing (1) comprises a bevel (10a) at an upper end (FIG. 2).

### Claim 6 (depends on 1)

A hydraulic clearance compensation element of claim 1 wherein at least one of the groove (11) and the recess (14) comprises at least one oil transfer bore (15, 16) (FIGS. 3 and 4).

### Claim 7 (depends on 1)

A hydraulic clearance compensation element of claim 1 wherein the securing ring (12) is made of a metallic or a non-metallic material.

### Claim 8 (depends on 6)

A hydraulic clearance compensation element of claim 6 wherein the securing ring (12) is configured as a polygonal ring (FIG. 6).

### Claim 9 (depends on 6)

A hydraulic clearance compensation element of claim 6 wherein at least one of the groove (11) and the recess (14) comprises at least one oil transfer bore (15, 16) (FIGS. 3 and 4).

### Claim 10 (depends on 6)

A hydraulic clearance compensation element of claim 6 wherein the securing ring (12) is made of a metallic or a non-metallic material.