Linear drive

Patent metadata

Field	Value
Publication number	US-9428147-B2
Application number	US-201214004917-A
Country	US
Kind code	B2
Filing date	Mar 14, 2012
Priority date	Mar 15, 2011
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

A linear drive, especially for a belt tensioner, includes a housing ( 10 ) including a piston seat ( 12 ), a piston element ( 16 ) accommodated in the piston seat ( 12 ) and a pyrotechnical drive element adapted to supply gas for displacing the piston element ( 16 ). The inner wall of the piston seat ( 12 ) includes a groove ( 30 ) extending in the displacing direction (R) of the piston element ( 16 ) through which gas can flow off the piston seat ( 12 ).

First claim

The invention claimed is:

1. A linear drive-for a belt tensioner, comprising a housing ( 10 ) including a piston seat ( 12 ) free of a radial opening, a piston element ( 16 ) connected to a gear rack ( 22 ) being movably accommodated in the piston seat ( 12 ) and a pyrotechnical drive element adapted to supply gas for displacing the piston element ( 16 ),
wherein the inner wall of the piston seat ( 12 ) includes a groove ( 30 ) extending in the displacing direction (R) of the piston element ( 16 ) through which gas can flow off the piston seat ( 12 ),
and the groove ( 30 ) being configured so as to allow a gas flow into the housing ( 10 ) ahead of the piston element ( 16 ) viewed in the displacing direction (R),
and wherein the length of the groove ranges from 35 mm to 70 mm.

2. The linear drive according to claim 1 , wherein the groove ( 30 ) and the piston element ( 16 ) are arranged in the piston seat ( 12 ) so that before the beginning of displacement of the piston element ( 16 ) no gas enters into the groove ( 30 ).

3. The linear drive according to claim 1 , wherein at the piston element ( 16 ) at least one sealing member ( 28 ) is arranged which is located between the piston element ( 16 ) and the inner wall of the piston seat ( 12 ) but is configured so that it does not prevent gas from flowing into the groove ( 30 ).

4. The linear drive according to claim 1 , wherein the cross-sectional area of the groove is larger than 1.5 mm 2 .

5. The linear drive according to claim 1 , wherein the cross-sectional area of the groove is smaller than 15 mm 2 .

6. The linear drive according to claim 1 , wherein the housing ahead of the piston element is in fluid communication with the environment at all times.

7. A linear drive-for a belt tensioner, comprising a housing ( 10 ) including a piston seat ( 12 ), a piston element ( 16 ) connected to a gear rack ( 22 ) being movably accommodated in the piston seat ( 12 ) and a pyrotechnical drive element adapted to supply gas for displacing the piston element ( 16 ),
wherein the inner wall of the piston seat ( 12 ) includes a groove ( 30 ) extending in the displacing direction (R) of the piston element ( 16 ) through which gas can flow off the piston seat ( 12 ),
the groove ( 30 ) being configured so as to allow a gas flow into the housing ( 10 ) ahead of the piston element ( 16 ) viewed in the displacing direction (R),
wherein the groove ( 30 ) extends over more than the length of the displacing distance.

8. The linear drive according to claim 7 , wherein the length of the groove ranges from 35 mm to 70 mm.

9. The linear drive according to claim 7 , wherein a cross-sectional area of the groove increases over the length of the displacing distance.

10. A linear drive-for a belt tensioner, comprising a housing ( 10 ) including a piston seat ( 12 ), a piston element ( 16 ) connected to a gear rack ( 22 ) being movably accommodated in the piston seat ( 12 ) and a pyrotechnical drive element adapted to supply gas for displacing the piston element ( 16 ),
wherein the inner wall of the piston seat ( 12 ) includes a groove ( 30 ) extending in the displacing direction (R) of the piston element ( 16 ) through which gas can flow off the piston seat ( 12 ),
the groove ( 30 ) being configured so as to allow a gas flow into the housing ( 10 ) ahead of the piston element ( 16 ) viewed in the displacing direction (R),
wherein the groove ( 30 ) widens in the displacing direction (R).

Assignees

• Schreiber Simon
• Grau Hermann
• Krukowski Krzysztof
• Trw Automotive Gmbh

Inventors

• Schreiber Simon
• Grau Hermann
• Krukowski Krzysztof

Classifications

• B60R2022/4661

  comprising venting means, e.g. for avoiding overpressure in case of fire or for allowing return motion with energy absorption · CPC title

• F15B15/19

  Pyrotechnical actuators · CPC title

• B60R22/4633 Primary

  Linear actuators, e.g. comprising a piston moving along reel axis and rotating along its own axis · CPC title