Mechanical acceleration sensor

• US 5,533,588 A
• Filed: 10/14/1994
• Issued: 07/09/1996
• Est. Priority Date: 10/15/1993
• Status: Expired due to Fees

• Current Assignee: TRW Repa GmbH
• Original Assignee: TRW Repa GmbH
• Inventors: Bohmler, Klaus, Maiwald, Helmut
• Primary Examiner(s): Culbreth, Eric D.
• Assistant Examiner(s): English, Peter C.
• Application Number:
  US08/323,342
• Time in Patent Office: 634 Days
• Field of Search: 280/734, 280/806, 280/735, 280/737, 180/282, 180/274, 102/252, 102/272, 102/274, 74/2, 200/61.53, 200/61.45 R
• US Class Current: 180/282
• CPC Class Codes: B60R 21/33 Arrangements for non-electric triggering of inflation electrical circuits for triggering safety arrangements B60R21/01
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass

Abstract

An inertial sensor for activating a vehicular passenger restraining system comprises a housing, a sensor body supported in the housing for a sliding translational movement under the action of inertial forces from a rest position to an activating position and a return spring preloading the sensor body towards the rest position. A striking pin is displaceably mounted in the housing for activation of an impact igniter. An additional spring is provided which preloads the striking pin towards the impact igniter in a direction transverse to translational movement of the sensor body. A ramp surface is provided on the housing which rises in a direction of sensor body movement towards the activating position. The striking pin has a lateral shoulder resting on the ramp surface and holding the striking pin in a rest position as long as the sensor body has not reached the activating position. The preloading force of the return spring is overcome by an acceleration as low as approximately 2 g. Following an initial stroke of approximately 2 mm, the movement of the sensor body is counteracted by the axial force component created by the spring load of the striking pin under the effect of the ramp surface. The subsequent actuating stroke amounts to only approximately 0.5 mm. With good reliability in preventing malactivation a fast response is achieved.

Claims

1. An inertial sensor for activating a vehicular passenger restraining system, comprising:

a housing;

an impact igniter mounted in said housing;

a striking pin displaceably mounted in said housing for activation of said impact igniter;

a pressure spring disposed between said housing and said striking pin, said pressure spring preloading said striking pin in a direction towards said impact igniter;

a sensor body supported in said housing for a sliding translational movement in a direction transverse to the displacement direction of said striking pin, said sensor body having a rest position spaced apart from said striking pin and an activating position impacting said striking pin, said sensor body being movable under the action of inertial forces from the rest position to the activating position;

a return spring disposed between said sensor body and said housing, said return spring preloading said sensor body towards the rest position;

and holding means for holding said striking pin in a readiness position spaced from said impact igniter as long as said sensor body has not reached said activating position;

said holding means having a holding effect which is overcome by a momentum accumulated in the sensor body during its travel from the rest position into the activating position when said momentum exceeds a predetermined threshold.

2. The sensor of claim 1, wherein said holding means comprises a ramp surface on said housing which rises in a direction of sensor body movement towards said activating position and said striking pin has a lateral shoulder resting on said ramp surface.

3. The sensor of claim 2, wherein said sensor body carries an actuating pin surrounded by said return spring which is formed as a helical spring.