US3735061A

US3735061A - Electrical switch assembly

Info

Publication number: US3735061A
Application number: US00208694A
Authority: US
Inventors: L Byrd
Original assignee: CARTER PRECISION ELECTRIC CO
Current assignee: CARTER PRECISION ELECTRIC CO
Priority date: 1971-12-16
Filing date: 1971-12-16
Publication date: 1973-05-22
Anticipated expiration: 1990-05-22
Also published as: CA964705A

Abstract

An electrical switch assembly having multiple on switch positions operated by an actuator lever and a pair of normally open switch contacts. One of the switch contacts is disposed along the path traced by the actuator lever in moving between the multiple on switch positions. Lever biasing means are provided to enable the actuator lever to be moved perpendicular to the switch path for closing the pair of switch contacts in any of the multiple on switch positions. A resistor subassembly encased in a heat conducting casing is mounted on the switch housing in a manner to provide a heat sink arrangement.

Description

United States Patent [191 [111 3,735,061 [451 May 22,1973

yrd

[54] ELECTRICAL SWITCH ASSEMBLY [75] Inventor: Lucid Lincoln Byrd, Mount Prospect, 111.

[73] Assignee: Carter Precision Electric Company,

Skokie, 111.

[22] Filed: Dec. 16, 1971 [21] Appl. No.: 208,694

[52] US. Cl. ..200/16 R, 338/200 [51] Int. Cl. ..I-l01h 15/00 [58] Field of Search ..200/3, 4, 6 R, 6 A,

[56] References Cited UNITED STATES PATENTS 3,413,341 11/1968 Bang ..338/200 X 2,596,503 5/1952 Newn Ham ..338/159 3,604,863 9/1971 Schink ..200/16 C 2,748,233 5/1956 Craine ..338/51 X 3,271,536 9/1966 Schink ..200/16 C Scow et a1. ..200/6 A 3,316,365 4/1967 Cobb ....200/l6 C 3,329,778 7/1967 Bedocs ..200/16 C 3,372,359 3/1968 Wilson ..200/6 A X 3,427,415 2/1969 Avner ..200/16 C X Primary Examiner-Richard B. Wilkinson Assistant Examiner-U. Weldon Attorney-John A. Dienner et a1.

[57] ABSTRACT An electrical switch assembly having multiple on switch positions operated by an actuator lever and a pair of normally open switch contacts. One of the 9 Claims, 12 Drawing Figures ELECTRICAL SWITCH ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to an electrical switch assembly, and in particular to an electrical switch assembly adapted to be used for energizing the windshield washer and wiper blade operations in an automobile.

It is common practice in the automobile industry to provide the above type switch assemblies with several electrical resistors for selectively varying the speed of the wiper blades. These resistors must be designed to carry relatively large currents and are thus preferably large in size to avoid heat dissipation problems. Because of the small space available for the many controls and dials needed on dashboard, the physical size and mounting of these resistors on the dashboard present design problems.

Many of the prior art electrical switch assemblies use a single actuator lever to operate both the multi-speed wiper blade operation and the washer operation. The disadvantage of these types of prior art switches is that the washer operation can only be energized at one of the speed positions, usually low" speed.

Accordingly, one object of this invention is to provide an electrical switch assembly having a means for mounting several electrical resistors of relatively small size on the switch housing in a manner to avoid heat dissipation problems.

Another object of this invention is to provide a multispeed electrical switch assembly having a single actuator lever which will energize the windshield washer operation for all wiper blade speed positions.

SUMMARY OF THE INVENTION An electrical switch assembly adapted for use to energize both automotive windshield washer and wiper blade operations housed in a block-shaped case having means for mounting on the dashboard. A contacts terminal board carrying blade contacts on one surface,

which are electrically connected to contact strips on the opposite surface, covers the open rear face of the block-shaped case. A contact carrier block is slidably mounted in the case and a pivotally mounted actuator lever extending through the front of the case provides means for selective positioning of the carrier block to a plurality of switch positions. Lever biasing means permits the actuator lever to close the windshield washer switch contact when in any of the switch positions. Power resistors used to vary the voltage applied to the wiper blade motor are encased in a metal housing and mounted on the switch case in such a manner to provide good heat conduction away from the resistors.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, there is shown an electrical switch assembly embodying the principles of my invention and generally designated by the reference numeral 10. Electrical switch assembly 10 has a blockshaped housing 12 having an open rear face 14 and a pair of integral mounting flanges 16 extending lengthwise from its front face 18. A pair of spaced mounting ears 20 (FIG. I) extend upwardly from front face 18 for supporting a resistor subassembly 21 on the housing 12.

The rear face 14 of housing 12 is covered by contacts terminal board 22 (FIG. 3) having a plurality of blade connectors 24 (four shown) extending rearwardly and adapted to be plugged into a female connector (not shown). Blade connectors extend through spaced openings in terminal board 22, and their inner ends are electrically connected to one of conductor strips 26 which are attached or printed on the inner surface 28 of contacts terminal board 22.

Switching action is provided by the selective positioning of contact subassembly 30 which is slidably supported in housing 12. Contact subassembly 30 comprises a contact carrier block 32 (FIGS. 8 and 9) and a plurality of contacts 34 (FIG. 6). Contacts 34 have a U-shaped configuration'and their bight portion 36 is slidingly disposed in one of the square recesses 38 FIG. 9 formed in the outer surface 40 of carrier block 32. Tension springs 42 (FIG. 3) seated in square recesses 38 urge the contacts 34 outwardly into frictional engagement with the inner surface 28 of terminal block 22. As contacts carrier block 32 is moved lengthwise of housing 12, the outer ears 44 of contacts 34 make electrical contact with various conductor strips (see FIG. 3) to electrically interconnect adjacent conductor strips 26 in a manner well known in the electrical switch art.

The contact subassembly 30 is selectively positioned by a switch actuator device 50, which includes pivotally mounted actuator lever 52. A forwardly extending housing nose section 54 projects from front surface 18 of housing 12 and actuator lever 52 is pivotally mounted in its central opening or passageway 58 by means of pin 60 extending crosswise at its forward end and through an intermediate portion of the actuator lever. The inner end 62 of lever 52 projects into recess 64 (FIG. 8) formed inwardly of the inner surface 66 of carrier block 32. Recess 64 flares outwardly to accommodate relatively large off-center displacements of lever 52 in both directions.

In the illustrated embodiment, there are four switch positions, including three on switch positions: OFF, LOW, MED, and HIGH. Indexing means 68 is provided for holding the actuator lever 52 in one of these four positions. Indexing means 68 comprises a pair of parallel guide tracks 70 extending lengthwise on the inside surface 72 (FIG. 7) of front face 18, and the tracks have four mating V-grooves 72. Detent ball and spring member 74 is held between one of the four sets of mating V-grooves 72. The intermediate portion of detent ball and spring member 74 is disposed in the elongated recess 76 (FIG. 8) formed on the inside surface 66 of carrier block 32. It will be appreciated that as contacts carrier block 32 is displaced, detent ball and spring member 74 will be moved along guide tracks 70 to index the switch actuator device 50 sequentially in one of the four switch positions.

One of the novel features of this invention is that the switch actuator device 50 can energize the windshield washer operation at any switch position. This feature is possible by virtue of the unique manner actuator lever 52 is mounted and its cooperation with washer switch contact which includes a spring biased lever 78. As shown in FIG. 4, the spring biased lever 78 comprises a spring leaf type contact extending lengthwise of terminal block 22 in a spaced apart relation and having one end 80 fastened to the inner surface 28 and electrically connected to one of the contact blades 24. The contact button 82 at the outer end of washer switch contact 78 when displaced upwardly makes electrical contact with the outturned flange 84 of contact 86 which is electrically connected to another of the blade contacts 24. As diagrammatically shown in FIG. 12, spring biased lever 78 is made sufficiently long to enable its intermediate portion to be engaged by the inner end of the actuator lever 52 for the three on switch positions, i.e., the length of the path traced by the inner end in moving between the three on switch positions.

To enable the actuator lever 52 to close switch contact 78 for the three on switch positions, a lever biasing means 86 cooperates with actuator lever to provide a substantially constant return spring force on the lever 52 at all three on positions. Lever biasing means 86 comprises a spring member 88 (FIG. having a heel portion 90 and a forward bowed resilient portion 92. The width of the spring member 88 is sufficiently large to cover the entire arcuate span of lever actuator 52 for moving between the three on switch positions. Spring member 88 is disposed in passageway 58 with the pivot pin 60 extending through opening 93 in the resilient portion 92 adjacent to heel portion 90. To permit free flexing of the resilient portion, opening 93 has an oval shape extending longitudinally of spring member 88.

By depressing downwardly on the knob 94 (FIG. 3) secured on the outer end of actuator lever 52, the resilient portion 92 of spring member 88 is flexed and the inner end 62 moves to the dotted position of FIG. 3. Upon releasing this downward force, resilient portion 92 springs back to its bowed position to return the actuator lever to its starting position. It is noted that the perpendicular relation of the heel portion 90 with the actuator lever prevents any movement of the actuator lever in the reverse direction.

To withstand the stresses and strains on the actuator lever 52, it is preferably made of a high strength metal, such as hard cold rolled steel. An insulator cap 96 is fitted on the outer end 62 of lever 52 for electrical insulation purposes.

To enable the washer and wiper blade operations to be simultaneously energized from the OFF position by merely depressing the actuator lever, guide means in the form of a cam surface 98 (FIG. 7) is provided at the rear end of passageway 58. With respect to FIG. 7, the actuator lever 52 is at the left side of passageway 58 when in the OFF position, and upon depressing downwardly on knob 94, the inner end 62 of lever 52 swings upwardly. By virtue of the sliding engagement of inner end 62 with cam surface 96, actuator lever 52 is simultaneously driven to the right into the LOW position. Thus, it will be understood that the wash operation can be energized from any of the four switch positions.

The electrical resistor subassembly 21 is included in the electrical switch assembly 10 to permit multi-speed control of the wiper blade motor. In this embodiment, two

resistors

100 and 102 are used to selectively step down the voltage applied to the wiper blade motor in two increments. Because the use of resistors for this purpose is well known in the motor control art and forms no part of this invention, the particular circuit connections to provide a three-speed operation of the wiper blade motor are not shown or described.

As mentioned above, the resistors used for speed control generate a considerable amount of heat. Because of the crowded space condition of automobile dashboards, it is desirable to use resistors of relatively small dimensions. However, serious heat dissipation problems arise when the smaller sized resistors are used. To prevent these heat dissipation problems and yet provide a very compact switch assembly design, this invention employs a novel heat sink arrangement. For this purpose, the electrical resistors and 102 are housed in a heat conducting case 106, preferably metal, and the case 106 is mounted on the top of metal case 12. The

electrical resistors

100, 102 are preferably wire wound power resistors. Case 106 is filled with an insulating material 108 of good heat conducting characteristics. Plastic sleeves 110 electrically insulate the leads of the resistors from the metal case 106.

It will be appreciated that the insulating material 108, metal case 106 and switch housing case 12 provide a direct heat conducting path that permits the resistors to carry unusually high currents.

As depicted in FIG. 4, the electrical switch assembly 10 includes a bimetal element 112 to prevent damage to the wiper blade motor from excessively high currents.

Although the preferred embodiment of this invention has been described in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details of the structure may be modified or changed without departing from the spirit or scope of the invention.

I claim:

1. An improvement in an electrical switch assembly having multiple on switch positions selected by sliding a contact carrier block across a contacts terminal board supported across the rear of the switch housing by means of an actuator lever pivotally mounted through a passageway formed inwardly of the front of said housing, the improvement comprising a pair of normally open switch contacts mounted on said terminal board, one of said contacts including lever means disposed along the entire path traced by the inner end of said actuator lever in moving between said multiple on switch positions and spring biased away from the other of said pair of contact, and actuator lever biasing means for enabling said inner end of said actuator lever to be moved transversely of said path into engagement with said lever means to close said pair of switch contacts from any of said on switch positions and for returning said actuator lever when the transverse depressing force exerted on the outer end of said actuator lever is released.

2. An improvement in an electrical switch assembly as defined in claim 1, further comprising cam means for guiding said actuator lever to move along said path from the off switch position to the first of said on switch positions whenever said transverse depressing force is exerted on said outer end of said actuator lever in said off position.

3. An improvement in an electrical switch assembly as defined in claim 1, wherein said lever biasing means comprises a spring member having a heel portion and integral resilient bowed portion, said spring member disposed lengthwise in said passageway with said heel portion transverse to said actuator lever and a part of said bowed portion in engagement with said lever, the width of said spring member being of sufficient dimension to cause said bowed portion to engage said actuator lever at all on switch positions.

4. An improvement in an electrical switch assembly having multiple on switch positions selected by sliding a contact carrier block across a contacts terminal board supported across the rear of the switch housing by means of a pivotally mounted actuator lever, the improvement comprising a nose section projecting forwardly from the front surface of said switch housing having a central passageway through which said actuator lever extends, pivot pin extending across said passageway at its forward end and through an intermediate portion of said actuator lever, a pair of normally open switch contacts mounted on said terminal board, one of said contacts including lever means disposed along the entire path traced by the inner end of said actuator lever in moving between said multiple on switch positions and spring biased away from the other of said pair of contacts, and a spring member disposed lengthwise I of said passageway and in biasing engagement with said intermediate portion of said actuator lever for all of said on switch positions to urge said inner end of said actuator lever away from engagement with said lever means.

5. An improvement in an electrical switch assembly as defined in claim 4, further comprising cam means for guiding said actuator lever to move along said path from the off switch position to the first of said on switch positions whenever a depressing force is exerted on the outer end of said actuator lever in a direction to swing said inner end toward said lever means.

6. An improvement in an electrical switch assembly as defined in claim 5, wherein said cam means comprises a cam surface formed at the rear end of said passageway to be engaged by said actuator lever at said off position upon the application of said depressing force which guides said actuator lever to move along said path from said off position to said first on switch position.

7. An improvement in an electrical switch assembly as defined in claim 4, wherein said spring member comprises a heel portion and integral resilient bowed portion, said heel portion disposed in said passageway adjacent said forward end and extending generally perpendicular to said actuator lever, said bowed portion extending lengthwise of said passageway with the part adjacent said heel portion in engagement with said intermediate portion of said lever, said pivot pin extending through an aperture formed in said adjacent part of said bowed portion, and the width of said adjacent part of said bowed portion of sufficient length to engage said intermediate lever portion.

8. An improvement in an electrical switch assembly as defined in claim 7, wherein said aperture is oval shaped extending lengthwise of said bowed portion to allow unrestricted flexing of said spring member.

9. An improvement in an electrical switch assembly as defined in claim 4, wherein said switch housing is formed of a metal casing, and further comprising a resistor subassembly including at least one power resistor connected to said contacts terminal board for electrical interconnection with said contacts carrier block to provide said multiple on switch positions, a metal housing for encasing said power resistor and electrical insulating material having good heat conducting characteristics filling said metal housing to space said power resistor from the inside surfaces of said metal housing, and metal mounting means for securing said resistor subassembly on said metal housing, whereby the heat generated by said power resistor is conducted away through said insulating material, said metal housing and said metal mounting means to said metal casing.

l i I.

Claims

4. An improvement in an electrical switch assembly having multiple on switch positions selected by sliding a contact carrier block across a contacts terminal board supported across the rear of the switch housing by means of a pivotally mounted actuator lever, the improvement comprising a nose section projecting forwardly from the front surface of said switch housing having a central passageway through which said actuator lever extends, pivot pin extending across said passageway at its forward end and through an intermediate portion of said actuator lever, a pair of normally open switch contacts mounted on said terminal board, one of said contacts including lever means disposed along the entire path traced by the inner end of said actuator lever in moving between said multiple on switch positions and spring biased away from the other of said pair of contacts, and a spring member disposed lengthwise of said passageway and in biasing engagement with said intermediate portion of said actuator lever for all of said on switch positions to urge said inner end of said actuator lever away from engagement with said lever means.