GB2109634A - Reversible switch - Google Patents

Abstract

A reversible switch comprises four fixed contact members 10, 11, 12, 13 mounted on a base 1 and having angularly spaced arcuate contacts 10a, 11a, 12a, 13a, respectively, jointly defining an interrupted circular wall, a cylindrical rotatable body 16 fitted in the wall and supporting a pair of springy movable contact members 21, 22 each having contact ends slidable into contact with adjacent two of the four contact members 10, 11, 12, 13 in response to angular movement of the rotatable body which is movable through an interval of 90 degrees between a first position in which each movable contact member 21, 22 electrically connects an adjacent pair (11, 10 and 13, 12) of fixed contact members and a second position in which they each connect another adjacent pair (10, 13, and 12, 11) of fixed contact members. The body 16 has an eccentric pin 20 extending through an arcuate slot in a cover 8 and actuatable to move therein by a lever 29 is pivotably mounted on the cover. The body 16 is selectively retainable in the first or second position by a spring-biased cap 14 receivable in a pair of holes 8, 9 in the cover one at a time. <IMAGE>

Description

SPECIFICATION Reversible switch Background of the invention The present invention relates to a reversible switch for selectively changing polarities in an electrical circuit.

A variety of reversible switches have been proposed and used, which however are unsatisfactory in that they are complex in structure, composed of a large number of parts, and costly to manufacture.

Summary of the invention It is an object of the present invention to provide a reversible switch which is comprised of a reduced number of parts, simple in construction, and can be manufactured less costly.

Another object of the present invention is to provide a reversible switch having fixed and movable contacts slidable against one another without being fused together.

According to the present invention, four fixed contact members having respective arcuate contacts are mounted on a base and have terminals for external connection, the arcuate contacts jointly defining an interrupted circular wall in which there is fitted a rotatable body supporting a pair of movable contact members each having ends slidable into contact with the arcuate contacts of adjacent two of the four fixed contact members. The rotatable body is angulariy movable about its own axis for an angular interval between a first position in which each movable contact member electrically connects an adjacent pair of fixed contact members and a second position in which each movable contact member electrically connects another adjacent pair of fixed contact members.The rotatable body has an axial shaft rotatably fitted in a hole in a cover mounted on the base, and a pin located in eccentric relation to the axial shaft and extending through an arcuate slot defined in the cover, there being a lever pivotably mounted on the cover and held in guiding engagement with the pin projecting through the arcuate slit for angularly moving the rotatable body between the first and second positions. Since the movable and fixed members are slidable against each other, they are prevented from being fused together while the switch is in use.

Brief description of the drawings The present invention will now be described with reference to the drawings, in which: Fig. 1 is an exploded perspective view of a reversible switch according to the present invention; Fig. 2 is a side elevational view of the reversible switch shown in Fig. 1, as attached to a trigger-actuated switch body; Fig. 3 is an enlarged plan view, partly in cross section, of a base on which fixed contact members and a rotatable body with movable contact members are mounted; Fig. 4 is an enlarged front elevational view, partly in cross section, of the rotatable body illustrated in Fig. 1 and Fig. 5 is a wiring diagram of an electrical circuit including the reversible switch of the present invention, the diagram being illustrative of alternative connections selectively provided by the reversible switch.

Detailed description As shown in Fig. 1, a reversible switch according to the present invention comprises four fixed contact members 10, 11, 12, 13 mounted on a base 1 and having four arcuate contacts 1 Oa, 11 a, 1 2a, 1 3a, respectively. The arcuate contacts are each in the shape of an arc of substantially 90 degrees and jointly provide an interrupted circular wall as best shown in Fig. 3. The fixed contact members 10-13 also include retainer end portions lOb, 11 b, 1 2b, 1 3b, respectively, and V- shaped terminal ends 1 0c, 11 c, 1 2c, 1 3c, respectively, for external connection.

The base 1 has a central circular recess 6 and four channels 2, 3, 4, 5 communicating with the central circular recess 6. The central circular recess 6 is defined partly by four arcuate walls 2a, 3a, 4a, 5a, against which the arcuate contacts 1 0a, 11 a, 1 2a, 1 3a are held, respectively. The base 1 also has four slits 2b, 3b, 4b, 5b receiving the recess 6. The central circular recess 6 is defined partly by four arcuate walls 2a, 3a, 4a, 5a against which the arcuate contacts 1 0a, 11 a, 12a, 13a are held, respectively.The base 1 also has four slits 2b, 3b, 4b, 5b receiving the retainer end portions lOb, 11 b, 1 2b, 1 3b respectively therein for positioning the fixed contact members 10-13 on the base 1. The channels 2-5 include slots 2d, 3d, 4d, 5d in which the terminal ends 1 0c-1 3c are housed, respectively. The central circular recess 6 and the channels 2-5 are open at an upper surface of the base 1 so that the fixed contact members 10-1 3 can easily be placed in position on the base 1.

A cylindrical rotatable body 1 6 has a pair of parallel grooves 17, 18 defined in one end thereof and extending in a direction normal to the axis of the cylindrical body 16, and a central axial shaft 11 9 on the other end thereof. A pin 20 is mounted on the other end of the rotatable body 1 6 and located in eccentric relation to the central axial shaft 1 9. A pair of movable contact members 21,22 are received respectively in the grooves 17, 18 as shown in Fig. 3. The movable contact members 21,22 comprise elongate springy elements having curved ends 21 a, 21 b, and 22a, 22b, respectively.The cylindrical rotatable body 16 with the movable contact members 21, 22 retained therein is fitted in the circular recess 6 in the base 1 and surrounded by the circular wall defined by the arcuate contacts 10a, 1 1a, 12a, 13a.Thecurvedends2la,21b, 22a, 22b are held against the arcuate contacts 1 0a, 11 a, 1 2a, 1 3a through open ends of the grooves 1 7, 18 (Fig. 3).

A cover 23 has an arcuate guide slot 24 extending through an angular interval of 90 degrees and receiving the pin 20 extending therethrough. A bearing hole 25 defined in the cover 23 receives therein the central shaft 19 of the rotatable body 16, the arcuate guide slot 24 extending through the bearing hole 25. Thus, the cylindrical rotatable body 1 6 is angularly movable about its own axis through 90 degrees, or is confined in its angular motion by the arcuate guide slot 24. The cover 23 has a pair of opposite sidewalls 28, 28 having therein a pair of openings 27, 27, respectively. The base 1 has on its opposite ends a pair of ledges 7, 7 (fig. 3) which are snapped respectively in the openings 27, 27 in the sidewalls 28, 28 when the cover 23 is mounted on the base 1.

The cylindrical rotatable body 1 6 has a cavity 24 in the end thereof on which the shaft 19 and the pin 20 are disposed, the cavity 34 housing therein a compression spring 1 5 as shown in Fig.

4. A cap 14 is mounted on the compression spring 1 5 and normally urged thereby in a direction to project out of the cavity 34. The cover 23 has a pair of positioning holes 8, 9 angularly spaced from each other with respect to the bearing hole 25 and located in diametrically opposite relation to ends of the arcuate slot 24 across the hole 25. With the cover 23 and the rotatable body 1 6 assembled together, the cap 14 is selectively receivable in the holes 3, 9 when the pin 20 on the rotatable body 1 6 is located at an diametrically opposite end of the arcuate slot 24.

The grooves 1 7, 18, the pin 20, and the holes 8, 9 are relatively positioned such that when the rotatable body 1 6 is in a position angularly spaced 45 degrees from the position illustrated in Fig. 3. The pin 20 is located centrally in the arcuate slot 24.

An actuator lever 29 has a notch 29a defined in a widened end 29a and loosely receiving the pin 20 projecting through the arcuate slot 24, and an opening 29c fitted over a stud 26 mounted on the cover 23, the widened end 29b being of such a size as to cover the arcuate slot 24 whenever the pin 20 is positioned. The stud 26, the bearing hole 25, and the center of the arcuate slot 24 are aligned with each other on an imaginary straight line, the positioning holes 8, 9 being located symmetrically one on each side of the imaginary straight line. The actuator lever 29 is retained on the cover 23 by a fastener 30 fixed to the stud 26 fitted in the opening 29c.

The reversible switch of the present invention is mounted on a trigger-actuated switch body 32 having a trigger 31 and a trigger-actuated switch 33, as shown in Fig. 2.

Fig. 5 shows an electrical circuit including a motor 35 supplied with an electric power from power supply lines 36, 37 through the reversible switch of the invention.

Operation of the reversible switch thus constructed is as follows. The position of the parts shown in Fig. 5, in which the fixed contacts 1 Oa, 1 3a are electrically connected to each other by the movable contact member 21, and the fixed contacts 11 a, 1 2a are electrically connected to each other by the movable contact member 22.

At this time, the pin 20 is held against one of the ends of the arcuate slot 24. When the rotatable body 26 is angularly moved through 45 degrees from the position of Fig. 3, the pin 20 is brought into the central position in the arcuate slot 24, whereupon the movable contact members 21,22 are out of contact with the arcuate contacts 1 Oa, 11 a, 1 2a, 1 3a, breaking the electrical circuit.

Further angular movement of the rotatable body 1 6 through additional 45 degrees causes the movable contact members 21,22 to electrically connect the arcuate contacts 1 0a, 11 a and 12a, 13a, respectively. The motor 35 is now connected to the power supply in an opposite polarity. When the pin 20 is positioned at either one of the ends of the arcuate slot 24, the cap 14 is resiliently retained in either one of the positioning holes 8, 9, thus holding the rotatable body 1 6 stably in a selected position against accidental rotation.

Aithough a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that many changes and modifications may be made therein without departing from the scope of the appended claims.

Claims (12)

Claims

1. A reversible switch comprising: (a) a base; (b) four fixed contact members mounted on said base and having arcuate contacts, respectively, spaced angularly from each other and jointly defining an interrupted circular wall; (c) a rotatable body fitted in said circular wall for angular movement about its own axis; (d) a pair of movable contact members supported on said rotatable body and each having contact ends slidable into contact respectively with adjacent two of said fixed contact members, said rotatable body being angularly movable through an angular interval between a first position in which each movable contact member electrically connects a pair of adjacent fixed contact members and a second position in which each movable contact member electrically connects another pair of adjacent fixed contact members;; (e) a cover mounted on said base and supporting said rotatable body for angular movement thereof; and (f) means on said rotatable body and said cover for angularly moving said rotatable body through said angular interval between said first and second positions.

2. A reversible switch according to claim 1, said base having a circular recess in which said arcuate contacts and said rotatable body are disposed.

3. A reversible switch according to claim 2, said circular recess being partly defined by four angularly spaced arcuate walls against which said arcuate contacts are held, respectively.

4. A reversible switch according to claim 2, said base having four slots communicating with said circular recess, said fixed contact members having terminals, respectively, disposed in said slots for external connection.

5. A reversible switch according to claim 1, said rotatable body being in the form of a cylinder and having a pair of parallel grooves defined in an end of said cylinder and accommodating therein said movable contact members, respectively, each of said grooves having open ends through which the contact ends of one of said movable contact members can be held against said adjacent two of the arcuate contacts.

6. A reversible switch according to claim 5, said cover having a bearing hole, said rotatable body having an axial shaft mounted on the other end of said cylinder and journalled in said bearing hole.

7. A reversible switch according to claim 1, each of said movable contact members comprising an elongate springy body having curved ends serving as said contact ends.

8. A reversible switch according to claim 1, said base having a pair of ledges on opposite ends thereof, said cover including a pair of sidewalls having a pair of openings, respectively, in which said ledges are snappingly fitted.

9. A reversible switch according to claim 1, said rotatable body being in the form of a cylinder retaining in one end thereof said movable contact members and having on the other end an axial shaft rotatably supported on said cover, said means comprising a pin mounted on said other end of said cylinder and located in eccentric relation to said axial shaft, and an arcuate guide slot defined in said cover and through which said pin extends.

10. A reversible switch according to claim 9, said arcuate guide slot extending through an angular interal of 90 degrees.

11. A reversible switch according to claim 9, said rotatable body having in said other end a cavity located in diametrically opposite relation to said pin, including a compression spring disposed in said cavity and a cap mounted on said compression spring and normally urged thereby in a direction to project out of said cavity, said cover having a pair of holes in which said cap is selectively retainable for positioning said rotatable body in one of said first and second positions.

12. A reversible switch according to claim 11, said pair of holes being angularly spaced 90 degrees from each other and located in diametrically opposite relation to ends of said arcuate guide slot.

1 3. A reversible switch according to claim 9, said means further including an actuator lever angularly movably mounted on said cover and held in guiding engagement with said pin projecting through said arcuate guide slot.

1 4. A reversible switch according to claim 13, said actuator lever having a notch receiving said pin.

1 5. A reversible switch constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.