GB2171558A - Rotary switch with means to effect limitation of movement - Google Patents

Abstract

A rotary switch comprises a housing 20 in which is mounted an angularly movable rotor 21. Angular movement of the rotor within the housing is arranged in use to actuate as required different contact means or different combinations of contact means mounted in the switch. The housing has a pair of spaced parallel sides 17 and 18 interconnected by a base portion 19 which extends at right angles to the sides, and the rotor has a generally radially extending projection 23 which is adapted to co-act with a fixed abutment 24 so as to form therewith stop means for limiting the angular movement of the rotor. Said fixed abutment has a pair of abutment faces 25 and 26 which are respectively engageable with a pair of abutment faces provided on the projection and said abutment faces 25 and 26 are disposed so that they lie within a sector which is bounded by a pair of intersecting planes which each contain the axis of rotation of the rotor 21 and which are respectively parallel to said base portion 19 of the housing and to said parallel sides 17 and 18 thereof. <IMAGE>

Description

SPECIFICATION Rotaryswi This invention relates to a rotary electric switch.

Such a switch incorporates an angularly movable rotorwhich is arranged to actuate on rotation different contact means or different combinations of contact means and it is common practice to arrangethatsaid rotor can be turned through a maximum angle ofturn which does not exceed 360 , stop means being provided which act to effect limitation of movement.

The stop means may comprise a projection on the angularly movable rotor or a member angularly movable therewith which co-acts with a fixed abutment provided on a relatively stationary part such as the housing of the switch. It is however inevitable that the combination of such a movable projection and fixed abutment will itself occupy a part of the angle through which the angularly movable rotor might otherwise be able toturn. In other words, although itis necessary to provide stop means to prevent the angularly movable rotorfrom turning through an angle which is greater than 360", the arcuate "spread" ofsuch stop means will result in the maximum angle ofturn which is available being less (and sometimes substantially less) than 360". Such loss of available angular adjustment becomes more serious when the rotary switch is required to incorporate a plurality of switch positions (defined for example by cam means) corresponding respectively to a plurality of angular positions ofthe anguiarly movable rotor, and especiallywhen such a switch is required to be of a relatively small size because the aforementioned "loss" of available angular adjustment ofthe rotary switch meansthatthe number of possible separate angularswitch positions may be unduly limited.Of course it is possible to reducethe aforementioned "loss" of available angular adjustment by reducing thearcuate thickness of said projection and/or said fixed abutment but obviously any such reduction will also reduce the strength of the projection and/orfixed abutment.

Accordingly the object of the present invention is to provide an improved form of rotary switch in which the aforesaid "loss" of available angular adjustment ofthe angularly movable rotor is reduced to a relatively small angle whilst atthe same time the strength of said projection on the angularly movable rotor and/or said fixed abutment is not reduced below an acceptable level.

In accordance with the invention there is provided a rotary switch comprising a housing having a pair of spaced parallel sides which are interconnected by a base portion extending at right anglesto said sides and an angularly movable rotorwhich is mounted in said housing and arranged in use to actuate as required different contact means ordifferent combinations of contact means according to its angular position relative to the housing wherein there is provided on said rotor a projection which is adapted to co-act with a fixed abutment so as to form therewith stop means for limiting the angularmovementof said rotor, said fixed abutment having a pair of abutment faces which are respectively engageable with a pair of abutment faces provided on said projection, the two abutment faces of said fixed abutment being disposed so that they lie within a sector which is bounded by a pair of intersecting planes which each contain the axis of rotation of said rotor and which are respectively parallel to said base portion ofthe housing and to said parallel sides thereof.

Each pair of inter-engageable faces which comprise one of said faces on the fixed abutment and one of said faces on the rotor projection are preferable of planar configuration and arranged so that, when engaged, they will lie in a common plane. Furthermore, either the pairoffacesformed on the fixed abutmentorthe pair offaces formed on the rotor projection may be disposed sothatthey lie in a pair of mutually perpendicular planes.

The invention will now be more particularly described with reference to the accompanying drawing wherein: Figures 1 and 2 are diagrammatic views which illustrate one example of a rotary switch constructed in accordance with the invention and showing a housing in which is mounted an angularly movable rotor together with a fixed abutment which is mounted in said housing,thetwo figures showing respectively the two limiting angular positions of the angularly movable rotor.

Referring nowtothe drawingsthe housing of one example of a rotary switch constructed in accordance with the invention is diagrammatically shown and indicated by reference numeral 20, said housing having a pairofspaced parallel sides 17 and 18 which are interconnected bya base portion 19 extending at right angles to said sides 17 and 18. Within said housing is mounted an angularly movable rotor 21 which forms an index/stop wheel. The member 21 would be adapted in use and when rotated to different angular positions to actuate different contact means (not shown) or different combinations of contact means.

As shown in the drawjngs the rotor 21 isformed with a generally radially extending projection 23 and the switch is also provided with a fixed abutment 24 which may be integrally moulded with the housing 20 or be otherwise secured thereto. Said fixed abutment 24 incorporates a pair of mutually perpendicular planar abutment faces respectively indicated by reference numerals 25 and 26 and said faces are respectively adapted to co-operate with a pair of mutually inclined co-acting planarfaces27 and 28 which are formed on the aforesaid projection 23.

Moreover, said fixed abutment is arranged so that said abutmentfaces 25 and 26 lie in the housing ina sector which is bounded by a pair of intersecting planes which each contain the axis of rotation of said rotor and which are respectively parallel to said base portion 19 ofthe housing and to said parallel sides 17 and 18 thereof.

Both of the aforementioned figures show, by means of chain dotted lines extending radially from the aforementioned axis of rotation of the rotor 21, a plurality of separate and distinct switch positions into which said rotor 21 can be set. Thus the comptete circle of 360" has been divided into a total of 16 sectors which each comprise an included angle of 22.5" and 15 ofthesesectors are indicated by reference numerals 1-15 respectively. These spaced switch positions may conveniently be located and defined by yieldable detent means such as may be formed for example by a plurality of spaced lobes of a cam which are arranged to engage in succession one or more spring loaded bails or rollers.

In Figure 1 the rotor 21 is shown in one iimiting position ofthe total possible angular movement and in this position the face 27 of the projection 23 engages the face 25 of the fixed abutment 24, said faces 27 and 25 then lying in a common plane. If the chain dotted radial line 29 is then taken as a reference line, the switch in Figure 1 can be said to lie in the position which is indicated by reference numeral 1.From this position the angularly movable rotor21 canthen be turned in a clockwise direction through the successive switchpositions2,3,4,5,6,7,8,9,10,11,12, 13, l4and 15 (i.e. the aforementioned reference line 29 reaches the index position 15 as is shown in Figure 2) and in this position the other face namely the face 26 of the fixed abutment24will then engagetheface 28 of the projection 23.

In this position said faces 26 and 28 will lie in a common plane.

Thus it will be realised that the stop means formed by said projection 23 and fixed abutment24will allow angular movement of rotor 21 through an arc which amounts to 337.5 , allowing said members 21 and 22 to take up anyone of the 15 switch positions which are separated by angles of 22.5 . It will also be observed that the fixed abutment 24 and the projection 23 are each of relatively thick construction, thereby provid ing strong stop means which cannot easily be damaged orfractured.

It will also be understood that instead of providing the two mutually perpendicular planarabutmentfaces 25 and 26 on thefixed abutment, such faces can be formed on the projection 23, in which case the two mutually inclined planarfaces 27 and 28 would be formed on the fixed abutment instead of on the angularly movable projection. The switch will of course be provided with a suitable knob which is accessibletotheuserandwherebythe rotor2l can be turned when desired.

Claims (4)

1. A rotary switch comprising a housing having a pairofspaced parallel sides which are interconnected by a base portion extending at right angles to said sides and an angularly movable rotor which is mounted in said housing and arranged in use to actuate as required different contact means or diffe rentcombinations of contact means according to its angular position relative to the housing wherein there is provided on said rotor a projection which is adapted to co-actwith a fixed abutment so as to form therewith stop means for limiting the angular movement of said rotor, said fixed abutment having a pair of abutment faces which are respectively engageable with a pair of abutmentfaces provided on said projection, the two abutmentfaces of saidfixed abutment being disposed so thatthey lie within a sector which is bounded by a pair of intersecting planes which each contain the axis of rotation of said rotor and which are respectively parallel to said base portion of the housing and to said parallelsides thereof.

2. A rotary switch as claimed in Claim 1 wherein each pairofinter-engageablefaceswhichcomprise one of said faces on the fixed abutment and one of said faces on the rotor projection are of planar configuration and are arranged so that, when engaged,theywill lie in a common plane.

3. A rotary switch as claimed in either ofthe preceding claims wherein either the pair of faces formed on the fixed abutment orthe pair offaces formed on the rotor projection are disposed so that they lie in a pair of mutually perpendicular planes.

4. A rotary switch substantially as hereinbefore described with reference to and as shown in the accompanying drawings.