US3733448A

US3733448A - Inertia type switch with adjustable selective seating surface for movable contact

Info

Publication number: US3733448A
Application number: US00217053A
Authority: US
Inventors: C Brady
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-11
Filing date: 1972-01-11
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

A movement responsive switch assembly comprising a housing, a vertical conductive post reciprocally mounted in the housing and including inner and outer elements threaded together to define a seat of adjustable depth for supporting a conductive ball, and an adjustable stabilizing spring depending from the housing to apply stabilizing forces to the top of the ball, which together with the seat depth determines the directions and magnitude of the forces under which the ball is dislodged to effect switching.

Description

United States Patent [1 1 Brady 51 May 15, 1973 [54] INERTIA TYPE SWITCH WITH ADJUSTABLE SELECTIVE SEATING SURFACE FOR MOVABLE CONTACT [76] Inventor: Clifford H. Brady, PO. Box 812,

Sulphur Springs, Tex. 75482 22 Filed: J'an.ll, 1972 21 Appl.No.: 217,053'

[52] US. Cl. ..200/6l.45 R, ZOO/61.52 [51] Int. Cl. ..H0lh 35/02 [58] Field of Search ..200/61.45 R, 61.53,

' ZOO/61.8

[56] References Cited UNITED STATES PATENTS 2,056,494 10/1936 Tucker, Jr. et al ..200/61.45 R

2,912,534 11/1959 Row'ell et al. ..200/6l.45 R 2,415,086 2/1947 Detwiler ..200/6l.45 R 2,898,415 8/1959 Clurman.... .....200/61.52 X 2,898,416 8/1959 Clurman ..200/6l.45 M

Primary Examiner-J. R. Scott A ttorney- Harvey B. Jacobson [57] ABSTRACT 11 Claims, 4 Drawing Figures INERTIA TYPE SWITCH WITH ADJUSTABLE SELECTIVE SEATING SURFACE FOR MOVABLE CONTACT The present invention is generally related to inertia and movement responsive switches and, more particularly, to an improved movement responsive switch assembly including means for adjusting the magnitude and type of forces required for response.

It is an object of the present invention to provide an improved switch assembly capable of accurately responding to selected conditions of vibration, tilting, or acceleration.

It is a further object of the present invention to provide a novel movement responsive switch assembly including an adjustable stabilizing spring engaging a normally seated conductive ball, whereby the forces required to dislodge the ball may be preset for anticipated conditions.

Another object of the present invention is to provide a unique movement responsive switch assembly including means for convenient adjustment of the effective depth of the ball retaining seat, thereby controlling the type of response condition.

It is a further object of the present invention to provide a versatile movement responsive switch assembly which is comprised of a relatively small number of parts, yet is rugged, durable, selectively adjustable for use under different conditions and relatively inexpensive to manufacture.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming-a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. 1 is a perspective view of the movement responsive switch assembly of the present invention.

FIG. 2 is a sectional view taken along section 2-2 of FIG. 1.

FIG. 3 is a sectional view taken along section 3-3 of FIG. 2.

FIG. 4 is a sectional view similar to that of FIG. 2'but with the reset knob in a reset position.

Referring now, more particularly, to FIG. 1 of the drawings, the switch assembly of the present invention is generally indicated by the numeral and includes a housing 12, preferably of cylindrical configuration and made of insulating materials such as melamine, plastic, or the like. A pair of

connection terminals

14 and 16 extend from one side of the housing with a reset knob 18 depending from the bottom of the housing for reset of the switch, as hereinafter explained. A transparent plastic cover 20 is fastened in a suitable manner to the top of housing 12 and is provided with a threaded bushing 22 which receives an adjustable thumbscrew 24. A conductive ball 26 may be viewed through cover 20 to determine whether it is in a seated or dislodged position. A center post 28 is reciprocally mounted in the housing and is provided with a concave seating surface 30 adapted to receive conductive ball 26.

Referring to FIGS. 24, it will be appreciated that the housing is provided with an internal conical surface 32 with an annular conductive member 34 embedded therein and connected to terminal 14. Conductive member 34 is spaced from center post 28 by a distance not greater than the diameter of the conductive ball. The center post is comprised of an outer element 36 of conductive material which is in sliding contact with a spring-biased brush 38 connected to terminal 16. As such, an external indicating circuit is completed through

terminals

14 and 16 by way of the conductive ball when dislodged from seat 30 as illustrated in dash in FIG. 2.

Outer element 36 is provided with a threaded axial bore adapted to receive the threaded portion of an inner post element 40, the top of which provides the seating surface 30. Element 40 is also provided with an integral shaft 42 which extends downwardly through an opening 44 in the bottom of the housing for attachment to a reset knob 46, by way of a setscrew 48, or similar means. A coil compression spring 50 biases the post upward to maintain it in the normal operating position, illustrated in FIG. 2, as determined by engagement of the reset knob surfaces with the bottom surfaces of housing 12.

It will be appreciated that for proper operation the switch assembly is mounted in a vertical position, such that the conductive ball rests in seat 30 under the influence of gravity. Horizontal forces acting upon the ball due to vibration, tilting of the switch assembly, or acceleration may be sufficient to dislodge the ball for completion of the circuit. The conditions under which the ball is dislodged may be selected by conductive proper adjustment of a stabilizing spring 52 and/or the effective depth and configuration of seating surfaces 30. The stabilizing spring is supported by a swivel fitting 54 mounted to the lower end of the thumbscrew 24. The bottom convolution of the stabilizing spring cradles the top of the conductive ball in such a manner to provide mild restraining forces which tend to prevent dislodgement of the ball from its seat. The magnitude of the restraining forces which stabilize the conductive ball may be appropriately adjusted through thumbscrew 24. As such, if the switch assembly is being utilized for response to a mild vibration condition, the stabilizing spring is positioned to provide very mild restraining forces to the conductive ball or is removed altogether from the switch assembly. On the other hand, if the switch assembly is utilized as an inertia switch for response to an acceleration condition, such as the rapid braking of a vehicle, the restraining forces of the stabilizing spring may be appropriately increased to prevent false signalling due to mild vibrations.

It will be appreciated that the conductive ball may be conveniently reset after dislodgement by pulling the reset knob downward against spring 50 as illustrated in FIG. 4. This positions the top of the post at the bottom of the conical surface 32 to permit the ball to roll into seat 30. Return of the reset knob to its original position is effective to bring the ball into alignment with the stabilizing spring to set the switch assembly for subsequent operation. It will be appreciated that the outer post element 36 is provided with a slot 56 which is adapted to engage a key 58 associated with housing 12 upon manipulation of knob 46 to the reset position illustrated in FIG. 4. This provides a detent which locks the outer pos't element against rotation, thereby permitting vertical adjustment of the inner post element which is effective to alter the depth of the seating surface 30. Such an adjustment is illustrated in dash in FIG. 4. It will be appreciated that such an arrangement permits coarse adjustment or selection of the type of response condition. If, for example, the switch assembly is being utilized to respond to vibrations of great magnitude and substantially in a vertical direction, lowering of the ball seat will be effective to prevent dislodgement of the ball due to mild vibrations or horizontal acceleration conditions, vibrations of greater magnitude being required to dislodge or hop the ball out of the seat. Furthermore, it will be appreciated that such an adjustment may render the switch nonresponsive to forces acting upon the ball in a horizontal direction. For example, when the center element is lowered substantially, slight tilting or horizontal acceleration forces will be ineffective to dislodge the ball.

From the foregoing description, it will be appreciated that the switch assembly of the present invention is provided with versatile means of adjusting both the type and magnitude of the condition to which it is intended to respond. The adjustable stabilizing spring provides a means of fine adjustment of the response condition, while the seating surface adjustment provides a coarse setting which has a greater effect upon the type of condition to which the switch will respond. While the switch illustrated is effective to complete a circuit upon dislodgement of the conductive ball, minor changes in construction may be made to provide breaking of a circuit normally maintained through the thumbscrew or center post element. Also, minor changes in the shapes or materials of the housing or its associated cover or the exact location of the terminals are deemed to fall within the scope of the present invention.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. A movement responsive switch assembly comprising a housing, a first vertical post element mounted in said housing and including an upper end portion, a second vertical post element threadedly received by said upper end portion of said first vertical post element and including an upper seating surface adjacent to the upper end portion of said first vertical post element, a stationary contact mounted in said housing and spaced from said post elements, a conductive ball defining a movable contact engageable with said stationary contact and normally positioned on said seating surface and being dislodgeable therefrom to a signalling position in response to predetermined forces acting upon the switch assembly, and means associated with said post elements for selective rotation of one of said post elements relative to the other of said post elements to ad jist the vertical position of said seating surface relative to the upper end portion of said first vertical post element, thereby adjusting the effective depth of said seating surface.

2. The structure set forth in claim 1 wherein said first post element is conductive, said conductive ball engaging both said stationary contact and said first post element when dislodged from said seating surface to said signaling position to complete a circuit.

3. The structure set forth in claim 2 wherein said switch assembly includes a first terminal external of said housing connected to said stationary contact, a conductive brush slidably engaging said first post element, and a second terminal exterior of said housing connected to said brush.

4. The structure set forth in claim 3 wherein said comprises an annular conductive member surrounding said first post element.

5. The structure set forth in claim 1 wherein said means for selective rotation of one of said post elements includes an adjustment knob operatively connected to said one post element and external of said housing for rotation of said one post element.

6. The structure set forth in claim 5 wherein said means for selective rotation of one of said post elements includes detent means associated with said housing for preventing rotation of said other post element relative to said housing, said post elements being reciprocally mounted in an opening in said housing and selectively movable by said adjustment knob between an upper position and a lower position, said detent means operatively engaging said other post element when said post elements, are in said lower position.

7. The structure set forth in claim 6 wherein said switch assembly includes biasing means associated with said housing for biasing said post elements away from said lower position to said upper position.

8. A movement responsive switch assembly comprising a housing, a vertical conductive post reciprocally mounted in said housing and being movable between a set position and a reset position, an opening in said housing, a portion of said post extending through said opening to the exterior of said housing, a reset knob affixed to said post exterior of said housing, spring means biasing said post toward said set position, a stationary contact attached to said housing and spaced from said post, said post having an upper seating surface, a conductive ball defining a movable contact normally resting in said seating surface, an elongated stabilizing compression spring carried by said housing and extending downwardly to normally embrace an upper portion of said ball when in said seating surface, and means for adjusting the compression of said stabilizing spring against said conductive ball to set the magnitude of force required to dislodge said conductive ball from said seating surface.

9. The structure set forth in claim 8 wherein said post is comprised of inner and outer elements in adjustable threaded engagement with each other, said seating surface being associated with said inner element with the effective depth thereof being defined by the relative position of said inner element to said outer element.

10. The structure set forth in claim 9 wherein said switch assembly includes detent means for locking said outer post element against rotation relative to said housing, said reset knob being affixed to said inner post element to permit rotation thereof to adjust the vertical position of said seating surface relative to said outer post element.

11. The structure set forth in claim 10 wherein said outer post element is generally cylindrical in configura tion and includes a threaded axial bore receiving said inner post element.

Claims

1. A movement responsive switch assembly comprising a housing, a first vertical post element mounted in said housing and including an upper end portion, a second vertical post element threadedly received by said upper end portion of said first vertical post element and including an upper seating surface adjacent to the upper end portion of said first vertical post element, a stationary contact mounted in said housing and spaced from said post elements, a conductive ball defining a movable contact engageable with said stationary contact and normally positioned on said seating surface and being dislodgeable therefrom to a signalling position in response to predetermined forces acting upon the switch assembly, and means associated with said post elements for selective rotation of one of said post elements relative to the other of said post elements to adjust the vertical position of said seating surface relative to the upper end portion of said first vertical post element, thereby adjusting the effective depth of said seating surface.

6. The structure set forth in claim 5 wherein said means for selective rotation of one of said post elements includes detent means associated with said housing for prevenTing rotation of said other post element relative to said housing, said post elements being reciprocally mounted in an opening in said housing and selectively movable by said adjustment knob between an upper position and a lower position, said detent means operatively engaging said other post element when said post elements are in said lower position.

11. The structure set forth in claim 10 wherein said outer post element is generally cylindrical in configuration and includes a threaded axial bore receiving said inner post element.