Extended dwell shock sensing device

• US 4,877,927 A
• Filed: 04/06/1989
• Issued: 10/31/1989
• Est. Priority Date: 04/06/1989
• Status: Expired due to Term

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Hamlin, Inc. (Littelfuse Incorporated)
• Inventors: Reneau, Daniel R.
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US07/334,311
• Time in Patent Office: 208 Days
• Field of Search: 200/61.45 R-61.53, 200/81.9 M, 200/82 E, 200/83 L, 200/84 C, 335/205, 335/206
• 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: H01H 35/147 the switch being of the reed switch type

Abstract

An extended dwell shock sensing device (10) is constructed to operate in two stages. A carriage (34) that includes a magnet (40) is slidably mounted between a first abutment (20) and a second abutment (22). The carriage (34) also includes a cradle (52) in which a non-magnetic mass (54) is slidably mounted between a first wall (53) and a second wall (55). At a rest position, the carriage (34) is biased away from the second abutment (22) by a spring (50) and the non-magnetic mass (54) is biased away from the second wall (55) by a spring (58). A reed switch (24) is mounted to be responsive to the position of the magnet (40). Upon application of an acceleration force, the shock sensing device (10) operates in two stages. In a first stage, the carriage (34) travels to a position where it approaches the second abutment (22), and activates the reed switch (24). In a second stage, the non-magnetic mass (54) travels toward the second wall (55). The inertia of the non-magnetic mass (54) resisting a rapid change in the return direction of the carriage (54), combined with the relatively long distance to travel back to the first stage position extends the time that the reed switch (24) stays activated.

Claims

1. A shock sensor having an extended activation time 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.

2. The shock sensor of claim 1 wherein the shock sensor operates in two stages such that the carriage magnet will travel past the pre-selected activation position in a first stage and the non-magnetic mass will travel toward the second site when the increased acceleration force is applied in a second stage.

3. A shock sensor having an extended activation time 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 carriage having a first end and a second end, the carriage 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 carriage faces the first abutment and the second end of the carriage faces the second abutment, the carriage further comprising;

(i) a permanent magnet portion that travels coincident with the carriage;

(ii) a cradle having a first wall and a second wall spaced apart from the first wall a fixed distance;

(iii) a non-magnetic mass slidably mounted to travel within the cradle of the carriage between the first wall and the second wall, the cradle defining a path of travel for the non-magnetic mass such that the non-magnetic mass is capable of travel parallel to the direction of travel of the permanent magnet, the first wall of the cradle facing the first abutment and the second wall of the cradle opposite the first wall;

(d) first means for biasing positioned between the carriage and the second abutment, the carriage being held away from the second abutment by the first biasing means until such time that the carriage is subjected to an initial acceleration force of pre-selected magnitude oriented in the direction of the second abutment, the carriage being movable toward the second abutment when subjected to the initial acceleration force;

(e) second means for biasing positioned between the non-magnetic mass and the second wall, the non-magnetic mass being held away from the second wall by the second biasing means until the non-magnetic mass is subjected to an increased acceleration force of pre-selected magnitude oriented in the direction of the second wall, the non-magnetic mass being movable toward the second wall when subjected to the increased acceleration force; and

(f) 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 reaches a pre-selected activation position during movement of the carriage in response to the initial acceleration force, and will remain activated as the non-magnetic mass moves toward the second wall in response to the increased acceleration force, then is moved back toward the first wall by the second biasing means upon cessation of the increased acceleration force, and until the carriage is moved back past the pre-selected activation position by the first biasing means.

4. The shock sensor of claim 3 wherein the shock sensor operates in two stages such that the carriage magnet will travel toward the second abutment when the initial acceleration force is applied in a first stage and the non-magnetic mass will travel toward the second wall when the increased acceleration force is applied in a second stage.

5. The shock sensor of claim 3 wherein the carriage is tubular in shape having an inner diameter that is slidable mounted upon the outside of a compartment of the housing that extends between the first abutment and a second abutment, and wherein the reed switch is positioned within the compartment and is activated as the carriage travels between the first and second abutments.

6. The shock sensor of claim 5 wherein the compartment is horizontal.

7. The shock sensor of claim 5 wherein the compartment is a pipe.

8. The shock sensor of claim 7 wherein the second end of the carriage has a notch and the first spring fits within the notch.

9. The shock sensor of claim 3 wherein the first means for biasing in a first spring.

10. The shock sensor of claim 3 wherein the second means for biasing is a second spring.

11. The shock sensor of claim 10 wherein the non-magnetic mass has a notch and the second spring fits within the notch.

12. The shock sensor of claim 3 where in the first abutment is an outer margin of a compartment of the housing and the second abutment is an inner diameter of a circumferential wall and a ledge extends between the compartment and the circumferential wall, and wherein the carriage is annular in shape having an inner diameter and an outer diameter such that the inner diameter of the carriage forms the first end of the carriage and the outer diameter of the carriage forms the second end of the carriage, the inner diameter of the carriage being positioned about the compartment and being slidably mounted on the ledge, the reed switch being positioned within the compartment to be closed by the magnet as the carriage travels between the outer margin of the compartment and the inner diameter of the circumferential wall.

13. The shock sensor of claim 12 wherein the compartment is vertical.

14. The shock sensor of claim 12 wherein the compartment is a pipe.

15. The shock sensor of claim 12 wherein the first means for biasing is a first ring spring which is engaged between the carriage and the inner diameter of the circumferential wall.

16. The shock sensor of claim 15 wherein the outer diameter of the carriage has a notch and the first ring spring fits within the notch.

17. The shock sensor of claim 12 wherein the second means for biasing is a second ring spring which is engaged between the non-magnetic mass the second wall.

18. The shock sensor of claim 17 wherein the cradle of the carriage is circular and the non-magnetic mass is annular and fits within the circular cradle.

19. The shock sensor of claim 18 wherein the non-magnetic mass has a notch and the second ring spring fits within the notch.

20. A shock sensor having an extended activation time 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 compartment of the housing extending between the first and second abutments;

(d) a carriage having a first end and a second end, the carriage being tubular in shape and having an inner diameter that is slidabaly mounted to travel upon the outside of the compartment, and oriented so that the first end of the carriage faces the first abutment and the second end of the carriage faces the second abutment, and the carriage further comprising;

(i) a permanent magnet portion that travels coincident with the carriage;

(ii) a cradle having a first wall and a second wall spaced apart from the first wall a fixed distance;

(iii) a non-magnetic mass slidably mounted to travel within the cradle, the cradle defining a path of travel for the non-magnetic mass such that the non-magnetic mass is capable of travel generally parallel to the direction of travel of the permanent magnetic portion, the first wall of the carriage facing the first abutment and the second wall of the carriage opposite the first wall;

(d) first means for biasing engaged between the carriage and the second abutment, the carriage being held by the first biasing means away from the second abutment until such time that the carriage is subjected to an initial acceleration force of pre-selected magnitude oriented in the direction of the second abutment, the carriage being movable toward the second abutment when subjected to the initial acceleration force;

(e) second means for biasing engaged between the non-magnetic mass and the second wall, the non-magnetic mass being held away from the second wall by the second biasing means until the non-magnetic mass is subjected an increased acceleration force of pre-selected magnitude oriented in the direction of the second wall, the non-magnetic mass being movable toward the second wall when subjected to the increased acceleration force; and

(f) a reed switch mounted within the compartment and responsive to the position of the magnet such that the reed switch will be activated when the magnet reaches a pre-selected activation position as the carriage travels between the first and second abutments during movement of the carriage in response to the initial acceleration force, and will remain activated as the non-magnetic mass moves toward the second wall in response to the increased acceleration force, then is moved back toward the first wall by the second biasing means upon cessation of the increased acceleration force, and until the carriage is moved back past the pre-selected activation position by the first biasing means.

21. The shock sensor of claim 20 wherein the reed switch extends horizontally within the compartment.

22. The shock sensor of claim 20 wherein the compartment is a pipe.

23. The shock sensor of claim 20 wherein the first means for biasing is a first spring.

24. The shock sensor of claim 20 wherein the second means for biasing is a second spring.

25. The shock sensor of claim 23 wherein the second end of the carriage has a notch and the first spring fits within the notch.

26. The shock sensor of claim 23 wherein the non-magnetic mass has a notch and the second spring fits within the notch.

27. A shock sensor comprising:

(a) a housing having a compartment and a circumferential wall surrounding the compartment, a first abutment formed by the outer margin of the compartment;

(b) a second abutment formed by the inner diameter of the circumferential wall and spaced apart from the first abutment a fixed distance;

(c) a ledge of the housing extending between the first abutment and the second abutment;

(d) an annular carriage having, an inner diameter, an outer diameter, and a bottom end of the carriage being slidably mounted to travel on the ledge and oriented so that the inner diameter of the carriage faces the first abutment and the outer diameter of the carriage faces the second abutment, and the carriage further comprising;

(i) a permanent magnet portion that travels coincident with the carriage;

(ii) a cradle having a first wall and a second wall spaced apart from the first wall a fixed distance;

(iii) a non-magnetic mass slidably mounted to travel within the cradle, the cradle defining a path of travel for the non-magnetic mass from the travel of the magnet such that the non-magnetic mass id capable of travel generally parallel to the direction of travel of the permanent magnetic portion the first wall of the carriage facing the first abutment and the second wall of the carriage opposite the first wall;

(e) first means for biasing engaged between the carriage and the second abutment, the carriage being held by the first biasing means away from the second abutment until such time that the carriage is subjected to an initial acceleration force of pre-selected magnitude oriented in the direction of the second abutment, the carriage being movable toward the second abutment when subjected to the initial acceleration force;

(f) second means for biasing engaged between the non-magnetic mass and the second wall, the non-magnetic mass being held away from the second wall by the second biasing means until the non-magnetic mass is subjected to an increased acceleration force of pre-selected magnitude generally oriented in the direction of the second wall, the non-magnetic mass being movable toward the second wall when subjected to the increased acceleration force; and

(g) a reed switch mounted within the compartment and responsive to the position of the magnet such that the reed switch will be activated when the magnet reaches a pre-selected activation position as the carriage travels between the first and second abutments during movement of the carriage in response to the initial acceleration force, and will remain activated as the non-magnetic mass moves toward the second wall in response to increased acceleration force, then is moved back toward the first wall by the second biasing means upon cessation of the increased acceleration force, and until the carriage is moved back past the pre-selected activation position of the first biasing means.

28. The shock sensor of claim 27 wherein the compartment is vertical.

29. The shock sensor of claim 28 wherein the compartment is a pipe.

30. The shock sensor of claim 27 wherein the first means for biasing is a first ring spring.

31. The shock sensor of claim 27 wherein the second means for biasing is a second ring spring.

32. The shock sensor of claim 30 wherein the carriage has a notch and the first ring spring fits within the notch.

33. The shock sensor of claim 31 wherein the cradle is circular and the non-magnetic mass is annular and fits within the circular cradle.

34. The shock sensor of claim 33 wherein the non-magnetic mass has a notch and the second ring spring fits within the notch.