Acceleration sensor

• US 4,857,680 A
• Filed: 12/22/1988
• Issued: 08/15/1989
• Est. Priority Date: 12/22/1988
• Status: Expired due to Fees

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Janotik, Adam M.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US07/288,382
• Time in Patent Office: 236 Days
• Field of Search: 200/61.45 R, 200/61.45 M, 200/61.48-61.53, 180/282, 180/283, 280/734, 280/735
• US Class Current: 200/61.45R
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002

Abstract

An acceleration sensor is provided for electrically activating electrically operated automotive occupant restraints which employs switch contacts arranged in a cylindrical housing to resiliently bias a sensing mass in columnar fashion and collapse to effect contact upon movement of the sensing mass responsive to an acceleration pulse above a predetermined magnitude and duration.

Claims

1. An acceleration sensor for transmitting an electrical signal from a power supply to an inflatable occupant restraint system of an automobile upon the occurrence of an acceleration pulse of predetermined magnitude and duration, the sensor comprising:

an elongated housing adapted to be mounted in the vehicle and having an axially extending bore extending from an open end of the housing and terminating at a closed end;

a sensing mass slidingly received in the bore and having a cylindrical outer surface sized to define a predetermined diametral clearance with the bore;

a plug sealingly engaged with the housing to close the housing open end and therewith define a closed sensing chamber;

a columnar contact member formed of electrically conductive material as a resilient blade member sealingly carried by the plug and extending therethrough and having a contact portion abuttingly engaging the sensing mass to urge the sensing mass toward the housing closed end and a connecting column portion extending between the contact portion and the plug; and

a ring contact member formed of electrically conductive material, sealingly carried by the plug and extending therethrough and having a circumferentially extending contact plate received in the bore in axial registration with a portion of the connecting column portion and radially spaced therefrom, the collapsing column contact member and the ring contact member defining a normally open switch connected between the power supply and the inflatable occupant restraint system;

whereby upon the occurrence of the predetermined acceleration pulse, the sensing mass slides away from the housing closed end, deflecting the column portion into engagement with the contact plate to transmit the electrical signal from the power supply to the inflatable occupant restraint system.

2. A sensor as defined in claim 1, wherein the housing is fabricated from glass.

3. A sensor as defined in claim 1, wherein the housing and the plug are fabricated from glass.

4. A sensor as defined in claim 1, wherein the sensing chamber is filled with a dry inert gas.

5. A sensor as defined in claim 4, wherein the gas is argon.

6. A sensor as defined in claim 4, wherein the gas is nitrogen.

7. A sensor as defined in claim 1, wherein the columnar contact member and the ring contact member are fabricated from beryllium copper.

8. A sensor as defined in claim 1, wherein the columnar contact member and the ring contact member are fabricated from stainless steel.

9. A sensor as defined in claim 1, wherein the connecting column portion is radially offset from the contact portion.

10. An acceleration sensor for transmitting an electrical signal from a power supply to an inflatable occupant restraint system of an automobile upon the occurrence of an acceleration pulse of predetermined magnitude and duration, the sensor comprising:

an elongated housing adapted to be mounted in the vehicle and having an axially extending bore extending from an open end of the housing and terminating at a closed end;

a sensing mass slidingly received in the bore and having a cylindrical outer surface sized to define a predetermined diametral clearance with the bore;

a plug sealingly engaged with the housing to close the housing open end and therewith define a closed sensing chamber;

a columnar contact member formed of electrically conductive material as a resilient blade member sealingly carried by the plug and extending therethrough and having a contact portion abuttingly engaging the sensing mass to urge the sensing mass toward the housing closed end and a connecting column portion radially offset from the contact portion; and

a ring contact member formed of electrically conductive material, sealingly carried by the plug and extending therethrough and having a circumferentially extending contact plate received in the bore in axial registration with a portion of the connecting column portion and radially spaced therefrom, the collapsing column contact member and the ring contact member defining a normally open switch connected between the power supply and the inflatable occupant restraint system;

whereby upon the occurrence of the predetermined acceleration pulse, the sensing mass slides away from the housing closed end, deflecting the column portion into engagement with the contact plate to transmit the electrical signal from the power supply to the inflatable occupant restraint system.

11. A sensor as defined in claim 10, wherein the housing is fabricated from glass.

12. A sensor as defined in claim 10, wherein the housing and the plug are fabricated from glass.

13. A sensor as defined in claim 10, wherein the sensing chamber is filled with a dry inert gas.

14. A sensor as defined in claim 13, wherein the gas is argon.

15. A sensor as defined in claim 13, wherein the gas is nitrogen.

16. A sensor as defined in claim 10, wherein the columnar contact member and the ring contact member are fabricated from beryllium copper.

17. A sensor as defined in claim 10, wherein the columnar contact member and the ring contact member are fabricated from stainless steel.

18. A sensor as defined in claim 10, wherein the sensing mass comprises a cylindrical member having a central recess formed on at least one end for receiving the contact portion.

19. An acceleration sensor for transmitting an electrical signal upon the occurrence of an acceleration pulse of predetermined magnitude and duration, the sensor comprising:

an elongated housing adapted to be mounted in the vehicle and having an axially extending bore extending from an open end of the housing and terminating at a closed end;

a sensing mass slidingly received in the bore and having a cylindrical outer surface sized to define a predetermined diametral clearance with the bore;

a plug sealingly engaged with the housing to close the housing open end and therewith define a closed sensing chamber;

a columnar contact member formed of electrically conductive material as a resilient blade member sealingly carried by the plug and extending therethrough and having a contact portion abuttingly engaging the sensing mass to urge the sensing mass toward the housing closed end and a connecting column portion extending between the contact portion and the plug; and

a ring contact member formed of electrically conductive material, sealingly carried by the plug and extending therethrough and having a circumferentially extending contact plate received in the bore in axial registration with a portion of the connecting column portion and radially spaced therefrom, the columnar contact member and the ring contact member defining a normally open switch;

whereby upon the occurrence of the predetermined acceleration pulse, the sensing mass slides away from the housing closed end, deflecting the column portion into engagement with the contact plate to transmit the electrical signal.

20. A sensor as defined in claim 19, wherein the connecting column portion is radially offset from the contact portion.

21. An acceleration sensor for transmitting an electrical signal from a power supply to an inflatable occupant restraint system of an automobile, the sensor comprising:

a housing having an axially extending bore including a closed end;

a sensing mass mounted in the housing at the closed end for damped slidable movement along an axis of the housing bore in response to changes in the velocity of the automobile with respect to the axis;

a fixed electrical contact fixedly mounted within the housing bore; and

a deflectable electrical contact having an end fixedly carried with the housing and having a contact portion resiliently engaging the sensing mass in columnar fashion to bias the mass in one direction with respect to the housing, the sensing mass being operative upon the occurrence of an acceleration pulse of predetermined magnitude to move to collapse the deflectable contact, reducing the biasing force thereof porportional to the movement and causing portions of the deflectable contact to engage the fixed electrical contact, thereby transmitting the electrical signal.