Mass in liquid vehicular crash sensor

• US 3,889,130 A
• Filed: 06/04/1973
• Issued: 06/10/1975
• Est. Priority Date: 06/04/1973
• Status: Expired due to Term

• Current Assignee: Breed Automotive Technology, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: David S. Breed
• Inventors: Breed, David S.
• Primary Examiner(s): Schaefer, Robert K.
• Assistant Examiner(s): Ginsburg, M.
• Application Number:
  US05/366,427
• Time in Patent Office: 736 Days
• Field of Search: 307/121 200/61.53,61.45R,61.08 280/15AB 180/91
• US Class Current: 307/121
• 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
• CPC Class Codes: H01H 35/142 Damping means to avoid unwanted response

Abstract

The vehicular crash sensor of this invention comprises a sealed chamber substantially filled with a liquid having a low kinematic viscosity and containing a mass adapted to move through the liquid, a bias force acting on the mass to prevent its moving until a predetermined deceleration of the vehicle occurs. The liquid serves to lubricate hydro-dynamically the motion of the sensing means and to damp inertially its motion.

Claims

1. A crash sensor for sensing acceleration above a predetermined acceleration threshold of a vehicle having a normally inactive passenger restraint system and Means for actuating said system, said sensor comprising a housing having a wall defining a chamber;

a sensing mass occupying said chamber, the crosssectional dimension of said chamber being greater than the corresponding dimension of said mass to provide an annular clearance between said mass and said wall and the longitudinal dimension of said chamber being greater than the corresponding dimension of said mass whereby said mass is enabled to move in a direction longitudinally of said chamber, said mass having a passage extending therethrough in the direction of longitudinal movement thereof;

a liquid having kinematic viscosity lower than 100 centistokes at 70* F. and together with said mass substantially filling said chamber whereby the liquid may flow through said passage and said clearance operating means including means carried by said mass and responsive to predetermined movement of said mass in one direction to operate said actuating means; and

biasing means acting on said mass and disabling said movement thereof in said one direction until said predetermined acceleration threshold is exceeded.

2. The construction set forth in claim 1 wherein said liquid exerts a damping force on said sensing mass.

3. The construction set forth in claim 1 including hydro-dynamic bearing means between said sensing mass and said wall.

4. The construction set forth in claim 1 wherein said actuating means includes electrical contacts.

5. The construction set forth in claim 4 wherein said operating means includes contact means for engaging said electrical contacts, said contact means and said sensing mass being capable of relative movement following engagement of said contacts by said contact means.

6. The construction set forth in claim 1 wherein said actuating means includes an explosive detonator.

7. The construction set forth in claim 1 wherein said operating means includes piston means within said sensing mass acted on by said liquid and operable to amplify said movement of the sensing mass.

8. Vehicular crash sensor and protective apparatus comprising a housing having a wall defining an elongate, cylindrical chamber;

a cylindrical sensing mass within said chamber, said mass having an axial passage therethrough and having a diameter sufficiently less than that of said chamber to provide an annular clearance between said mass and said wall, said mass being shorter than the length of said chamber to enable movement of said mass axially of said chamber;

a liquid having a kinematic viscosity lower than 100 centistokes at 70* F. and together with said mass substantially filling said chamber whereby said liquid may flow through said passage and said clearance means biasing said mass to move in one direction in said chamber and operable to prevent movement of said mass in the opposite direction until said mass is subjected to a predetermined acceleration force in said opposite direction;

a passenger protection device;

means for actuating said device; and

operating means including means carried by said mass for operating said actuating means in response to predetermined movement of said mass in said opposite direction.

9. The construction set forth in claim 8 wherein said liquid exerts a damping force on said sensing mass.

10. The construction set forth in claim 8 including hydro-dynamic bearing means between said sensing mass and said wall.

11. The construction set forth in claim 8 wherein said actuating means includes electrical contacts.

12. The construction set forth in claim 11 wherein said operating means includes contact means for engaging said electrical contacts, said contact means and said sensing mass being capable of relative movement following engagement of said contacts by said contact means.

13. The construction set forth in claim 8 wherein said actuating means includes an explosive detonator.

14. The construction set forth in claim 8 wherein said operating means includes piston means within saiD sensing mass and acted on by said liquid to move in said one direction in response to the movement of the sensing mass in said opposite direction.

15. An inertially damped crash sensor for sensing acceleration above a predetermined acceleration threshold of a vehicle having a normally inactive passenger restraint system and means for actuating said system, said sensor comprising a housing having a wall defining an elongate, sealed chamber;

a sensing mass occupying said chamber and having a cross-sectional dimension sufficiently less than that of said chamber to provide an annular clearance between said mass and said wall, said mass having a length less than that of said chamber whereby said mass is capable of movement longitudinally of said chamber, said mass having a passage extending longitudinally therethrough;

a liquid of low kinematic viscosity together with said mass substantially filling said chamber whereby said liquid may flow through said passage and said clearance and means biasing said mass to move in one direction in said chamber and disabling movement of said mass in the opposite direction until said predetermined acceleration threshold is exceeded, the radius of said clearance, the diameter of said passage, and the viscosity of said liquid being so related that the flow of said liquid through said passage in response to movement of said mass in said opposite direction is at a reynolds number greater than 1, whereby such flow is limited inertially and is substantially independent of temperature variations of said liquid.

16. The construction set forth in claim 15 wherein said mass has a plurality of axially spaced, circumferential grooves in its periphery to provide a plurality of hydrodynamic bearing surfaces confronting said wall.