US3272948A - Electric switch structure - Google Patents

Description

Sept. 13, 1966 S. J. GLOVIAK ET AL ELECTRIC SWITCH STRUCTURE Filed June 5, 1964 INVENTORS ROGER AWE/LE1? ATTORNEYS United States Pate M 3,272,948 ELECTRIE SWITQH STRUCTURE Stanley .1. Gloviak, Westchester, and Roger A. Weiler, Skokie, Ill, assignors to Carter Precision Electric Co., Sliokie, IlL, a corporation of Illinois Filed June 3, 1964, er. No. 372,276 7 Claims. (Cl. 200-466) This invention relates to an electric switch structure. In particular, it is concerned with a switch of the type used in automobiles to prevent the closing of the circuit to the engine starter if the power transmission is not in the correct position.

The particular embodiment of the switch disclosed herein is designed to be mounted directly upon the housing of an automatic transmission in which one of the planetary gears is provided with a metal bracket having a comb-like formation on one edge thereof. The switch is provided with a pin element which extends into the transmission housing at a location such that a tooth on the comb will mechanically engage the end of the pin, when the planetary gears are in proper position, and such engagement completes the electrical circuit for controlling the engine starting motor, when the ignition key is rotated to the start position. If the comb in the transmission does not make contact with the pin of the safety switch, it is impossible to start the car with the transmission in that position. In this type of arrangement, the mechanical position of the planetary gears in the transmission determines whether or not the engine starter can be energized electrically. After the engine starts, the comb automatically moves away from the switch pin.

Briefly, our improved switch structure comprises a metallic housing in the form of a tubular shell having an externally threaded end portion for mounting in a tapped hole in the housing wall of the power transmission. Within the end of the shell which extends into the transmission casing, a plunger is mounted to slide longitudinally of the switch shell, with the inner end of the plunger extending beyond the inner end of the shell. The contact element of the switch which engages the comb on the planetary gear is formed of a pin which is mounted upon a metallic core part of the plunger and extends through the insulating covering of the sleeve. The extent to which the end of the pin projects beyond the inner end of the plunger is important, and one object of the present invention is to devise a switch structure by which the end of the contact pin may be accurately and quickly positioned with respect to the end of the mounting sleeve.

A further object of the invention is to devise a method of positioning the end of the pin with the right clearance with respect to the mounting sleeve so that the positioning is automatic and is independent of variations due to manual judgment or control.

A suitable embodiment of the invention is illustrated in the accompanying drawing in which FIGURE 1 is a longitudinal sectional view of the complete switch structure; FIGURE 2 is a rear-end view of the insulating sleeve or cup of the plunger; FIGURE 3 is a sectional view of FIGURE 2 along the plane 3-3; and FIGURE 4 is a view in elevation of FIGURE 2 as seen from the lower side of FIGURE 2.

Referring to FIGURE 1, the casing or shell "of the switch is formed of a metallic sleeve 1 having the end portion 1a externally threaded at 1b by which the switch structure is mounted within a tapped hole in the casing wall of the power transmission. An intermediate section of the casing 1 is enlarged and is formed as a nutshaped section by which the switch housing may be screwed tightly into the tapped hole in the transmission casing. The externally threaded portion 1a of sleeve 1 3,272,948 Patented Sept. 13, 1966 has a smaller internal diameter than the outer nut-shaped portion 10, to provide an internal shoulder 1d at the junction between the smaller threaded section and the larger nut section.

Mounted within the bore of the sleeve section 1a is the plunger of the switch includes an outer insulating sleeve 2 surrounding metal core part 3 which forms a holder for switch pin 4.

Insulating sleeve 2 has a sliding fit with the inner walls of the sleeve section 1a and is provided at its inner end with an external radial flange 2a which engaged the shoulder 1d on the housing shell 1 and prevents the sleeve 2 from moving out of the end of the sleeve section tla.

As shown in the drawing, the sleeve 2 is made in the form of a cup having a bottom wall 2b which covers the inner end of core part 3 and extends inwardly beyond the end of the sleeve section In. The central part of the end wall 2b has a flat outer face of circular shape, as shown at 212', and the outer portion of the end wall 212 surrounding the circular control portion 2b is beveled as shown at 2b.

The contact pin 4 is mounted within a central bore in metal core part 3. The pin 4 is formed of a diameter to have a close sliding fit within the bore of the core part 3, and is securely held in any adjusted position within this bore by means of two sets of longitudinal serrations or ribs 4a and 41; formed on the outside of the pin at locations spaced from the two ends, the outer points of the ribs being located on a circle having a diameter somewhat larger than the bore in the core part 3, so that the ribs will bite into the wall of the bore when the pin is forced into the bore. It should be noted that one end 4c of the contact pin 4 extends through a central opening 20 in the end wall 212 of the insulating sleeve 2 and extends beyond the flat end surface 2b of the end wall 2b to a certain extent which must be accurately set at the time of assembly of the switch structure.

A number of equallyspaced grooves 2d are formed in the outer surface of the insulating sleeve 2 and its flange 2a, longitudinally of the sleeve, as shown in FIGURES 2 to 4, for the purpose of allowing oil to pass from the switch shell breach into the transmission casing.

The end of the core part 3 extending out of the open end of cap 2 within the shell I has a radial flange 3a formed thereon which provides an abutment against which one end of a coil spring 5 is seated. The end turn of the coil spring may be located within an annular groove formed in the core part 3 immediately adjacent the flange 3a.

The outer end of the shell l terminates in a thin wall section 12 which is closed by a cover piece 6 formed of molded insulating material surrounding a plug element 7 having a pair of knurled rings on the surface thereof which are embedded in the cover piece 6.

The outer end portion of the thin wall section 12 is turned over and embraces the outer edge portion of the cover piece 6, as shown at 1e, to hold the cover piece in position on a seating flange at the inner end of the thin wall section lie. A sealing ring 8 of the usual O-ring is interposed between the cover piece 6 and an internal shoulder on the nut section lie of the shell 1 and is held under compression by the cover piece 6, to provide an air-tight seal.

The inner end of the plug element 7 is tapered at 7a to receive the other end of the coiled spring 5, and the end turn of the spring is seated within an annular groove formed at the end of the tapered portion of the plug. It will be understood that spring 5 normally urges the core piece 3 in a direction to maintain seating relation between the end of the core part and the end wall 2b of the insulating cap 2, and the section of the spring also holds the flange 2a of the cap in seating engagement with the internal shoulder 1d within the shell 1. The outer end of plug 7 is formed as a thread terminal stem 712. Thus, spring holds the cap 2d extended to the full extent out of the threaded end portion 1a of the shell 1, and also maintains the pin 4 in position such that the end 40 extends out of the aperture in end wall 212 of the cap 2 to the desired extent.

When a tooth on the comb carried by one of the planetary gears in the power transmission moves into proper position with respect to the switch contact, it will first engage the tapered or beveled annular area 217" of the cap end wall 2b and will force the cap back into the shell against the action of spring 5 until the end of the tooth moves into the fiat area 2b, and further movement of the comb tooth will cause it to engage the end 40 of the pin 4 and to move the pin and the attached core part 3 to a further small extent within the shell 1, while maintaining electric contact between the comb tooth and the contact pin 4. When in this position, a circuit will be closed to effect energization of the motor starter switch, as soon as the ignition switch has been turned to proper position.

As stated above, it is important that the end 40 of the contact pin 4 be accurately positioned with respect to the flat area 2b of the end of the cap 2. This would not present any problem if the cap 2 could be manufactured with the same invariable dimensions for all caps, but this is not possible due to the fact that in mass production of molded caps, it is customary to form such molded articles by means of multiple cavity dies in molding presses, and there will be a certain amount of variation between the different cavities which will prevent all caps from being identical in dimension. For example, there may be a small but appreciable variation in the thickness of the end wall 2b which must be taken into account in adjusting the position of the end 4c of the pin 4. It is for this reason that the pin 4 has been formed as a separate element from the pin carrier or core part 3. By this arrangement, it is possible to individually adjust each pin with respect to its mounting part 3, in order to allow for variations in the thickness of the end wall 212.

Another advantage of this arrangement is that it permits of proper location of the end of the pin with respect to the cap end surface 212' without machining either the end surface of the pin or the cap surface 2b. It is preferred to form the cap 2 of nylon and that the end surfaces 2b and 2b" remain in their original molded state. Also, the pin 4 is plated during manufacture, and it is important that the plating should remain on the end surface of the pin.

In order to insure proper adjustment of the end 40 of the pin 4 with respect to the outer surface 2b on the end wall of cap 2, each pin and its carrier part 3 is individually fitted to an insulating cap 2, and this threeelement sub-assembly, formed of a pin, a core part 3, and a cap 2, once assembled and adjusted, is never disassembled but is kept assembled during storage and distribution to the trade.

The preferred method of assembly is as follows: An insulating cup is placed within a suitable press with the surface 2b resting upon an anvil which is provided with an opening allowing the end portion 40 of pin 4 to move beyond the plane of the anvil surface. An insulated electric contact is carried by the anvil and is located in a position to engage the end 40 of pin 4 as it moves into the opening in the anvil.

After the cap 2 is in proper position within the press, a core part 3 is inserted within the cap 2, the core part 3 having free but close sliding fit with the inner walls of cap 2. Next, a pin 4 is selected and its end is inserted into the central bore in the core part 3 until the ribs in section 4b engage the walls of the bore. At this point the movable platen of the press acts upon the outer end of the pin 4 to force the pin into the bore, and this action is continued until the end 40 of the pin comes into engagement with the insulating contact carried by the anvil of the press, and contact between the pin 4 and the insulated press contact closes a circuit to energize suitable control apparatus to reverse the operation of the press and to withdraw the movable platen. This completes one sub-assembly which is then wrapped or packaged separately from other sub-assemblies. The operation is repeated for each sub-assembly.

The insulated contact carried by the anvil of the press may be suitably mounted for adjustment along the axis of the pin 4 to provide for adjustment of the amount to which the end of the pin must be projected beyond the surface 2b of the cap before it engages the insulated contact carried by the anvil.

It will be noted that the exposed end 40 of pin 4 has a relatively small diameter with respect to the internal diameter of shell portion 1a. Bay way of example only, in one embodiment the shell portion 1a has an internal diameter of substantially 0.5 inch and the pin diameter is substantially 0.1 inch. The outside diameter of the flat circular area 2b on the cap 2 is substantially 0.25 inch. The amount of projection of the end of the pin beyond the flat surface 2b may be set to a value between 0.001 and 0.003 inch.

We claim:

1. An electric switch structure comprising a tubular metallic shell having an end portion provided with external threads for screwing into a tapped hole, an intermediate portion having a nut-shaped exterior, insulating means closing the other end portion of said shell, a plunger mounted for reciprocating movement within said threaded end portion and comprising an insulating sleeve having free sliding movement with the inner wall of said externally threaded shell portion, a metallic core part mounted within said insulating sleeve and having free sliding movement with respect to said sleeve, said sleeve having an end wall extending outside of said externally threaded shell portion, said end wall having a central aperture therein, said core part having a central bore formed therein in axial alignment with the aperture in the end wall of said insulating sleeve, and a metallic contact pin mounted within the central bore of said core part and being frictionally held within said core part for adjustment longitudinally of said core part, said contact pin having one end thereof extending through the aperture in the end wall of said insulating sleeve, and spring means mounted within said shell and acting on said core part to resiliently bias said core part into a position where an end portion of said pin extends through said aperture.

2. A switch structure according to claim -1 wherein the end wall of said insulating sleeve has a flat circular outer surface surrounding said aperture, and a beveled annular surface surrounding said fiat circular surface.

3. A switch structure according to claim 1 and including an external terminal carried by the insulated cover on said other end of said shell, and means electrically connecting said external terminal with said spring means within said shell.

4. An electric switch structure comprising a tubular metallic shell having an open end portion, insulating means closing the other end portion of said shell, a plunger mounted for reciprocating movement within said open end portion and comprising an insulating sleeve having free sliding movement with the inner wall of said openend shell portion, said sleeve having an end wall extending outside of said open-end shell portion, said end wall having a central aperture therein, a metallic contact pin mounted within said insulating sleeve and having one end thereof extending through the aperture in the end wall of said insulating sleeve, a holder for said pin contained within said shell and frictionally holding said pin for longitudinal adjustment of the pin with respect to said sleeve, and spring means mounted within said shell and acting on said holder to resiliently bias said holder into a position Where an end portion of said pin extends through said aperture.

5. A switch structure according to claim 4 wherein the end Wall of said insulating sleeve has a tflat circular outer surface surrounding said aperture, and a beveled annular surface surrounding said flat circular surface.

6. An electric switch structure comprising a tubular metallic shell having an open end portion, insulating means closing the other end portion of said shell, a plunger mounted for reciprocating movement Within said open end portion and comprising an insulating member having free sliding movement with the inner wall of said ope11-end shell portion, said insulating member having an end portion extending outside of said -open-end portion and having a central aperture formed therein, a metallic contact pin mounted within said shell and having one end thereof extending through the aperture in said insulating member, a holder for said pin formed separately from said insulating member and frictionally hold ing said pin for longitudinally adjusting said pin With respect to said insulating member, and spring means mounted within said shell and acting on said pin holder to resiliently bias said holder into a position Where an end portion of said pin extends through said aperture.

7. A switch structure according to claim 6 wherein the end portion of said insulating member extending out of said shell has a flat annular surface surrounding said aperture, and a beveled annular sur-face surrounding said flat circular surface.

No references cited.

ROBERT K. SCHAEFER, Primary Examiner.

Claims (1)

1. 6. AN ELECTRIC SWITCH STRUCTURE COMPRISING A TUBULAR METALLIC SHELL HAVING AN OPEN END PORTION, INSULATING MEANS CLOSING THE OTHER END PORTION OF SAID SHELL, A PLUNGER MOUNTED FOR RECIPROCATING MOVEMENT WITHIN SAID OPEN END PORTION AND COMPRISING AN INSULATING MEMBER HAVING FREE SLIDING MOVEMENT WITH THE INNER WALL OF SAID OPEN-END SHELL PORTION, SAID INSULATING MEMBER HAVING AN END PORTION EXTENDING OUTSIDE OF SAID OPEN-END PORTION AND HAVING A CENTRAL APERTURE FORMED THEREIN, A METALLIC CONTACT PIN MOUNTED WITHIN SAID SHELL AND HAVING ONE END THEREOF EXTENDING THROUGH THE APERTURE IN SAID INSULATING MEMBER, A HOLDER FOR SAID PIN FORMED SEPARATELY FROM SAID INSULATING MEMBER AND FRICTIONALLY HOLDING SAID PIN FOR LONGITUDINALLY ADJUSTING SAID PIN WITH RESPECT TO SAID INSULATING MEMBER, AND SPRING MEANS MOUNTED WITHIN SAID SHELL AND ACTING ON SAID PIN HOLDER TO RESILIENTLY BIAS SAID HOLDER INTO A POSITION WHERE AN END PORTION OF SAID PIN EXTENDS THROUGH SAID APERTURE.

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