Device and method for testing acceleration shock sensors

• US 4,980,526 A
• Filed: 04/06/1989
• Issued: 12/25/1990
• Est. Priority Date: 04/06/1989
• Status: Expired due to Fees

• Current Assignee: Daimler-Benz AG (Mercedes-Benz Group AG), Breed Automotive Technology, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Hamlin, Inc. (Littelfuse Incorporated), Daimler-Benz AG (Mercedes-Benz Group AG)
• Inventors: Reneau, Daniel R.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US07/334,310
• Time in Patent Office: 628 Days
• Field of Search: 200/61.45 R, 200/61.53, 335/205-207, 335/256, 335/266, 335/151
• US Class Current: 200/61.45M
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: H01H 35/147 the switch being of the reed switch type

Abstract

A testing device (11) is applied to an acceleration shock sensor (10) of the type having a reed switch (24) that operates such that the net mass of a magnet (40) is accelerated against a spring (50) upon vehicle impact or rapid deceleration of the vehicle. The change in magnet (40) position causes a change in the magnetic field that activates the reed switch (24). The testing device (11) includes an electromagnetic coil (90) mounted in an area of minimal reed switch (24) sensitivity. The electromagnetic coil (90) is connected to be capable of providing a current flow that creates a magnetic field that opposes the magnetic field of the magnet (40). Upon energizing of the coil (90), the magnet (40) is urged to accelerate in a manner that emulates the acceleration of the magnet (40) caused by vehicle collision.

Claims

1. A shock sensor comprising:

(a) a housing;

(b) a magnet slidably mounted on the housing for travel;

(c) a reed switch mounted on the housing to be responsive to the position of the magnet such that the switch is activated when the magnet travels to a pre-selected activation position during movement of the magnet in response to an acceleration force applied to the housing; and

(d) an electromagnetic coil positioned to provide a magnetic field that urges the magnet to travel to the pre-selected activation position in a manner that emulates the acceleration of the magnet induced by rapid deceleration of the shock sensor to confirm the operation of the shock sensor, the electromagnetic coil being located on the housing at a position distant enough from the reed switch such that the reed switch will not be directly activated by energizing the coil.

2. The shock sensor of claim 1 further comprising leads to the electromagnetic coil and wherein the magnetic field of the electromagnetic coil is variable by changing the coil current pulse by application of different trigger voltages through the leads.

3. The shock sensor of claim 1 wherein the electromagnetic coil is a spool having two ends and windings wound circumferentially about the spool, and wherein one end of the spool is positioned perpendicular to the travel of the magnet.

4. The shock sensor of claim 1 wherein the magnetic field of the electromagnetic coil opposes the magnet.

5. The shock sensor of claim 1 wherein the magnet is a tubular magnet slidably mounted on the housing so as to surround the reed switch at the pre-selected position.

6. A testing device for a shock sensor of the type that includes a housing and a magnet slidably mounted on the housing for travel, and a reed switch mounted on the housing to be responsive to the position of the magnet such that the switch is activated when the magnet travels to a pre-selected position during movement of the magnet in response to an acceleration force applied to the housing, the testing device comprising an electromagnetic coil positioned to provide a magnetic field that opposes the magnet such that the magnet is urged to travel to the pre-selected position in a manner that emulates the acceleration of the magnet induced by rapid deceleration of the shock sensor to test the operation of the shock sensor, the electromagnetic coil being located on the housing at a position distant enough from the reed switch such that the reed switch will not be directly activated by energizing the coil.

7. The testing device of claim 6 further comprising leads to the electromagnetic coil and wherein the magnetic field of the electromagnetic coil is variable by changing the coil current pulse by application of different trigger voltages through the leads.

8. The testing device of claim 6 wherein the electromagnetic coil is a spool having two ends and windings wound circumferentially about the spool, and wherein one end of the spool is positioned perpendicular to the travel of the magnet.

9. The testing device of claim 6 wherein the magnetic field of the electromagnetic coil opposes the magnet.

10. A shock sensor comprising:

(a) a housing having a first abutment;

(b) a second abutment of the housing spaced apart from the first abutment a fixed distance;

(c) a magnet having a first end and a second end, the magnet being slidably mounted on the housing to travel between the first abutment and the second abutment and oriented so that the first end of the magnet faces the first abutment and the second end of the magnet faces the second abutment;

(d) means for biasing positioned between the magnet and the second abutment, the magnet being biased away from the second abutment by the biasing means until such time as the magnet is subjected to an acceleration force of pre-selected magnitude;

(e) reed switch mounted on the housing to be responsive to the position of the magnet such that the switch is activated when the magnet reaches a pre-selected activation position during movement of the magnet in response to a pre-selected acceleration force applied to the housing; and

(f) an electromagnetic coil positioned to provide a magnetic field that urges the magnet to travel between the first abutment and the second abutment in a manner that emulates the acceleration of the magnet induced by rapid deceleration of the shock sensor to test the operation of the shock sensor, the electromagnetic coil being located on the housing at a position distant enough from the reed switch that the reed switch is not directly activated by energizing the coil.

11. The shock sensor of claim 10 further comprising leads to the electromagnetic coil and wherein the magnetic field of the electromagnetic coil is variable by changing the coil current pulse by application of different trigger voltages through the leads.

12. The shock sensor of claim 10 wherein the means for biasing is a spring.

13. The shock sensor of claim 10 wherein the coil is a spool having two ends and windings about the spool, and wherein one end of the spool is positioned outside of the housing perpendicular to the travel of the magnet.

14. The shock sensor of claim 10 wherein the magnetic field of the electromagnetic coil opposes the magnet.

15. A testing device for a shock sensor of the type that includes a housing having a first abutment, a second abutment of the housing spaced apart from the first abutment a fixed distance, a magnet having a first end and a second end, the magnet being slidably mounted on the housing to travel between the first abutment and the second abutment and oriented so that the first end of the magnet faces the first abutment and the second end of the magnet faces the second abutment, means for biasing positioned between the magnet and the second abutment, the magnet being held away from the second abutment by the biasing means until such time as the magnet is subjected to an acceleration force of pre-selected magnitude, and a reed switch mounted on the housing to be responsive to the position of the magnet such that the switch is activated when the magnet reaches a position during movement of the magnet in response to the pre-selected acceleration force applied to the housing, the testing device comprising an electromagnetic coil positioned to provide a magnetic field that urges the magnet to travel between the first abutment and the second abutment in a manner that emulates the acceleration of the magnet induced by rapid deceleration of the shock sensor, the electromagnetic coil being located on the housing at a position distant enough from the reed switch such that the reed switch is not directly activated by energizing the coil.

16. The testing device of claim 15 further comprising leads to the electromagnetic coil and wherein the magnetic field of the electromagnetic coil is variable by changing the coil current pulse by application of different trigger voltages through the leads.

17. The testing device of claim 15 wherein the means for biasing is a spring.

18. The testing device of claim 15 wherein the coil is a spool having two ends and windings about the spool, and wherein one end of the spool is positioned outside of the housing perpendicular to the travel of the magnet.

19. The testing device of claim 15 wherein the magnetic field of the electromagnetic coil opposes the magnet.

20. A method of testing a shock sensor of the type that includes a housing, a magnet slidably mounted on the housing for travel, and a reed switch mounted on the housing to be responsive to the position of the magnet such that the switch is activated when the magnet travels to a pre-selected position during movement of the magnet in response to an acceleration force applied to the housing, the method comprising the step of applying a magnetic field that opposes the magnet to urge the magnet to travel in a manner that emulates the acceleration of the magnet induced by rapid deceleration of the shock sensor, the electromagnetic field being applied by an electromagnetic coil located on the housing at a position distance enough from the reed switch such that the reed switch will not be directly activated by energizing the coil.

21. The method of claim 20 wherein the shock sensor has leads to the electromagnetic coil and wherein the magnetic field of the electromagnetic coil is varied by changing the coil current pulse by application of different trigger voltages through the leads to test the shock sensor'"'"'s response to varied accelerations.

22. The method of claim 20 wherein the electromagnetic coil is a spool having two ends and windings wound circumferentially about the spool, and wherein one end of the spool is positioned perpendicular to the travel of the magnet.

23. The method of claim 20 wherein the magnetic field of the electromagnetic coil opposes the magnet.

24. A method of testing a shock sensor of the type that includes a housing having a first abutment, a second abutment of the housing spaced apart from the first abutment a fixed distance, a magnet having a first end and a second end, the magnet being slidably mounted on the housing to travel between the first abutment and the second abutment and oriented so that the first end of the magnet faces the first abutment and the second end of the magnet faces the second abutment, a spring positioned between the magnet and the second abutment, the magnet being biased away from the second abutment by the spring until such time that the magnet is subjected to an acceleration force of pre-selected magnitude, and a reed switch mounted on the housing to be responsive to the position of the magnet such that the switch is activated when the magnet reaches a position during movement of the magnet in response to the pre-selected acceleration force applied to the housing, the method comprising the step of applying a magnetic field that opposes the magnet to urge the magnet to travel between the first abutment and the second abutment in a manner that emulates the acceleration of the magnet induced by rapid deceleration of the shock sensor, the electromagnetic field being applied by an electromagnetic coil located on the housing at a position distant enough from the reed switch such that the reed switch will not be directly activated by energizing the coil.

25. The method of claim 24 further comprising leads to the electromagnetic coil and wherein the magnetic field of the electromagnetic coil is variable by changing the coil current pulse by application of different trigger voltages through the leads.

26. The method of claim 24 wherein the electromagnetic coil is positioned adjacent the first abutment.

27. The method of claim 24 wherein the magnetic field of the electromagnetic coil opposes the magnet.

28. A shock sensor comprising:

(a) a housing;

(b) a carriage slidably mounted on the housing for travel and including a magnet portion;

(c) a non-magnetic mass slidable on the carriage between a first site and a second site on the carriage;

(d) a reed switch mounted on the housing to be responsive to the position of the magnet such that the reed switch is activated when the magnet travels to a pre-selected activation position during movement of the carriage in response to an initial acceleration force applied to the housing, and the reed switch will remain activated as the non-magnetic mass moves from the first site to the second site in response to an increased acceleration force, then the non-magnetic mass is moved back toward the first site upon cessation of the increased acceleration force, and until the carriage is moved back past the pre-selected activation position;

(e) an electromagnetic coil positioned on the housing to provide a magnetic field that urges the magnet portion to travel in a manner that emulates the acceleration of the magnet induced by rapid acceleration of the shock sensor to confirm the operation of the shock sensor, the electromagnetic coil being located on the housing at a position distant enough from the reed switch such that the reed switch will not be directly activated by energizing the coil.