AU2007201311B2 - A rotary switch - Google Patents

Abstract

- 14 A rotary switch (10) is described which comprises a body 5 portion (12), at least one electrical terminal (22, 24, 26) mounted in the body portion (12), and an actuator (18) rotatably mounted in the body portion (12). The actuator (18) is arranged to accommodate an electrical contact member (20) such that rotation of the actuator (18) 10 effects rotation of the electrical contact member (20) so as to dispose the electrical contact member (20) in electrical contact or not in electrical contact with an electrical terminal (22, 24, 26). The rotary switch also comprises disconnecting means (76) separate to the at 15 least one electrical terminal (22, 24, 26) for causing the electrical contact member (20) to lift relative to an electrical terminal as the actuator (18) is rotated so as to thereby break electrical contact between the electrical contact member (20) and the electrical terminal. H:\jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07 Fig. 1 4- 6 Fig. 2

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): H.P.M. INDUSTRIES PTY LTD Invention Title: A ROTARY SWITCH The following statement is a full description of this invention, including the best method of performing it known to me/us: - 2 A ROTARY SWITCH Field of the Invention 5 The present invention relates to a rotary switch for switching electrical currents. Background of the Invention 10 It is known to provide an electrical rotary switch which comprises a body portion, at least one electrical terminal mounted in the body portion, and an actuator rotatably mounted in the body portion, the actuator having an electrical contact member and being arranged such that 15 rotation of the actuator places the member in electrical contact or not in electrical contact with an electrical terminal. However, this type of actuator often suffers from 20 excessive arcing and has a relatively poor tactile feel. Summary of the Invention In accordance with an aspect of the present invention, 25 there is provided a rotary switch comprising: a body portion; at least one electrical terminal mounted in the body portion; an actuator rotatably mounted in the body portion, 30 the actuator being arranged to accommodate an electrical contact member such that rotation of the actuator effects rotation of the electrical contact member so as to move the electrical contact member across the contact surface of the at least one electrical terminal to dispose the 35 electrical contact member in electrical contact or not in electrical contact with the at least one electrical terminal; and - 3 disconnecting means separate to the at least one electrical terminal for causing the electrical contact member to lift off the surface of the at least one electrical terminal as the actuator is rotated so as to 5 thereby break electrical contact between the electrical contact member and the electrical terminal. In one arrangement, the disconnecting means comprises at least one ridge arranged to lift the contact member 10 relative to an electrical terminal as the actuator is rotated. In one embodiment, the electrical contact is lifted relative to an electrical terminal when the actuator is 15 rotated by direct contact between the contact member and the at least one ridge. In one embodiment, the location on the contact member which contacts the at least one electrical terminal during 20 use moves in a first arc, and the location on the contact member which makes contact with the disconnecting means moves in a second arc different to the first arc. In one arrangement, a transverse cross-sectional profile 25 of the contact member is of generally curved shape so as to facilitate smooth connection and disconnection between the contact member and the at least one electrical terminal. 30 The contact member may comprise an upstanding portion which may include a generally concave surface arranged to rest on and rotate relative to a common terminal provided in the body portion. 35 The contact member may be resiliently biased away from the actuator, for example by providing the actuator with a through hole and disposing a spring in the through hole in - 3A contact with the contact member. In this way, the contact member is biased towards the contact surface of the at least one electrical terminal when aligned with that surface.

S

- 4 The actuator may comprise an actuator body and an actuator post extending from the actuator body. The actuator post may include a generally cylindrical portion adjacent the actuator body, the cylindrical portion being formed so as 5 to provide a continuous curved circumferential surface which serves to assist in enabling smooth rotation of the actuator during use. The rotary switch may further comprise an end cap 10 engageable with the body portion so as to close the body portion, the end cap including a locating ring having at least one trough and at least one crest, and the rotary switch further comprising a ball bearing disposed between an end of the spring remote from the contact member and 15 the locating ring, the arrangement being such that the at least one crest, the at least one trough, the ball bearing, and the spring arrangement serve to define predetermined switch positions. 20 Description of the Drawings The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 25 Figure 1 is a diagrammatic perspective view of a rotary switch in accordance with an embodiment of the present invention; Figure 2 is a diagrammatic perspective view of an end cap of the rotary switch shown in Figure 1; 30 Figure 3 is a diagrammatic perspective view of an actuator of the rotary switch shown in Figure 1; Figure 4 is a diagrammatic end view of the actuator shown in Figure 3; Figure 5 is a diagrammatic perspective view of a body 35 portion of the rotary switch shown in Figure 1; Figure 6 is a diagrammatic plan view of the body portion shown in Figure 5; H:\jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07 -5 Figure 7 is a diagrammatic plan view of a contact member of the rotary switch shown in Figure 1; Figure 8 is a diagrammatic end view of the contact member shown in Figure 7; 5 Figure 9 is a diagrammatic first cross-sectional view of the rotary switch shown in Figure 1 taken along the line IX-IX; and Figure 10 is a diagrammatic second cross-sectional view of the rotary switch shown in Figure 1 taken along 10 the line X-X. Description of an Embodiment of the Invention Referring to the drawings, there is shown a rotary switch 15 10 for switching electrical current. The rotary switch 10 comprises a body portion 12, an end cap 14 engagable with the body portion 12 so as to close the body portion 12, and a knob 16 connected to an 20 actuator 18 rotatably mounted in the body portion 12 and arranged such that rotation of the knob 16 effects rotation of the actuator 18. The rotary switch 10 also includes an electrically 25 conductive contact member 20 shown more particularly in Figures 7 and 8 which is accommodated on the actuator 18 such that rotation of the actuator 18 effects rotation of the contact member 20. 30 As shown more particularly in Figures 6, 9 and 10, the rotary switch 10 is provided with first, second and third electrical terminals 22, 24 and 26 respectively, the arrangement being such that when the contact member 20 is rotated, the contact member 20 is able to make contact 35 with one of the first, second or third terminals 22, 24, 26 depending on the rotational position of the contact member 20. H:\jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07 - 6 The actuator 18 is shown more particularly in Figures 3 and 4. The actuator 18 includes a generally cylindrical actuator 5 body 28, and an actuator post 30 extending from the actuator body 28. In order to facilitate mechanical engagement with the knob 16, the actuator post 30 includes a flat portion 32. Between the flat portion 32 and the actuator body 28 is a generally cylindrical portion 34, 10 the cylindrical portion 34 being formed so as to provide a continuous curved circumferential surface which serves to assist in enabling smooth rotation of the actuator 18 during use. 15 The actuator 18 also includes a through hole 36 arranged to receive a ball bearing 40 and a spring 42 as shown more particularly in Figure 9, the ball bearing 40 being disposed at a side of the through hole 36 adjacent the actuator post 30 and the spring 42 being disposed in 20 contact with the ball bearing, with the ball bearing disposed between the actuator post 32 and the spring. The actuator 18 also includes a recess 38 shaped so as to snugly receive the contact member 20, with the contact 25 member 20 extending over the through hole 36 when the contact member 20 is received in the recess 38. In this way, when the contact member 20 is received in the recess 38, the spring 42 rests against the contact member 20 and serves to resiliently bias the contact member 20 and ball 30 bearing 40 in directions away from the actuator body 28. Since the spring 42 directly contacts the contact member, the spring 42 acts to maintain the contact member in a generally perpendicular orientation relative to the spring 35 42 and thereby the actuator post 30. H:\jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COHPL.doc27/03/07 -7 As shown more particularly in Figure 4, the configuration of the actuator 18 is such that a relatively small portion of the actuator post 30 extends over the through hole 36 so as to thereby retain the ball bearing 40 relative to 5 the through hole 36. As shown more particularly in Figure 2, the end cap 14 includes a recess 44 and a ledge 46 disposed in the recess 44, the ledge 46 being disposed adjacent the actuator body 10 28 when the actuator 18 is disposed in the body portion 12 and the end cap 14 is engaged with the body portion 12. The end cap 14 also has a cap aperture 47 which snugly receives the cylindrical portion 34 of the actuator 18 and cooperates with the cylindrical portion so as to 15 facilitate smooth rotation of the actuator 18. The end cap 14 also includes a locating ring 48 having a plurality of crests 50 and a plurality of troughs 52. In this example, four crests 50 and four troughs 52 are 20 provided with the crests 50 and troughs 52 being alternately disposed on the locating ring 48. During use, when the actuator 18 is disposed in the body portion and the end cap 14 is engaged with the body 25 portion 12, the ball bearing 40 locates in a trough 52 and is resiliently biased towards the locating ring 48 by the spring 42. Rotation of the knob 16 and thereby of the actuator 18 causes the ball bearing to travel up a crest 50 adjacent to the trough 52 in which the ball bearing 40 30 is disposed. Further rotation of the knob 16 causes the ball bearing to locate in the adjacent trough 52. It will be understood that the crests 50, troughs 52 and the ball bearing 40 and spring arrangement 42 serve to 35 define predetermined switch positions and provide the switch with a good tactile feel to a user. H:\jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07 -8 The contact member 20 is shown more particularly in Figures 7 and 8. The contact member 20 is of generally elongate 5 configuration and comprises a central portion 60, which in this example is substantially flat, an upstanding portion 62 defining a convex surface 64 on a first side of the contact member 20 and a concave surface 66 on a second opposite side of the contact member 20, and side portions 10 68 which extend upwardly of the central portion 60. The contact member 20 also includes a first end 70 adjacent the upstanding portion 62 and a second opposite end 72. As shown more particularly in Figures 9 and 10, the 15 contact member 20 is received in the recess 38 such that the upstanding portion 62 is disposed generally centrally of the actuator 18 with the convex surface 64 disposed adjacent the recess 38 and the side portions 68 extending towards the recess 38. 20 When the actuator 18 and the contact member 20 are disposed in the body portion 12, the upstanding portion 62 rests on a common terminal 74 disposed generally centrally of the body portion 12, with the concave portion 66 being 25 disposed adjacent and in contact with the common terminal 74. During use, rotation of the knob 16 and thereby the actuator 18 causes the contact member 20 to rotate about 30 the common terminal 74 and to selectively make electrical contact with the first, second or third terminals 22, 24 or 26. The spring 42 also serves to resiliently bias the contact member 20 towards the first, second or third terminals 22, 24, 26. 35 It will be appreciated that since the transverse cross sectional profile of the contact member 20 is of generally H:\Jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07 -9 curved shape, as shown more particularly in Figure 8, relatively smooth connection and disconnection occurs between the contact member 20 and the first, second and third terminals 22, 24, 26. By minimizing sharp edges in 5 contact with the first, second or third terminals during rotation of the contact member 20, the likelihood of arcing is reduced and the lifetime of the terminals is increased. 10 It will also be understood that since the contact member 20 has a relatively flat central portion 60 and curved side portions 68, the current carrying portion provided by the flat central portion 60 is separate to the contact and break locations provided by the side portions. Since wear 15 associated with the contact and break locations is spaced from the current carrying position, operation and active life of the switch is much improved relative to switches known hitherto. 20 As shown more particularly in Figures 5 and 6, the body portion 12 includes means for disconnecting the contact member 20 from the terminals 22, 24, 26, in this example ridges 76 arranged to lift the contact member 20 relative to an electrical terminal 22, 24, 26 as the actuator 18 is 25 rotated so as to thereby break electrical contact between the contact member 20 and the electrical terminal 22, 24, 26. This serves to provide a more positive tactile feel to a user and to reduce arcing by moving the contact member 20 away from the terminals 22, 24, 26 faster than 30 with rotary switches known hitherto. As can be seen in Figure 6, the location on the contact member 20 which contacts the terminals 22, 24, 26 during use moves in first arc 78, and the location on the contact 35 member 20 which makes contact with the ridges 76 moves in a second arc 80 different to the first arc 78. In this way, as the actuator 18 and the contact member 20 rotate, H:\-nelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07 - 10 two wear points rather than one are provided which helps to maintain the life of the rotary switch 10. Modifications and variations as would be apparent to a 5 skilled addressee are deemed to be within the scope of the present invention. H:\jnelson\keep\speci\completes\P63269 A ROTARY SWITCH - COMPL.doc27/03/07

Claims (12)

1. A rotary switch comprising: a body portion; 5 at least one electrical terminal mounted in the body portion; an actuator rotatably mounted in the body portion, the actuator being arranged to accommodate an electrical contact member such that rotation of the actuator effects 10 rotation of the electrical contact member so as to move the electrical contact member across the contact surface of the at least one electrical terminal to dispose the electrical contact member in electrical contact or not in electrical contact with the at least one electrical 15 terminal; and disconnecting means separate to the at least one electrical terminal for causing the electrical contact member to lift off the surface of the at least one electrical terminal as the actuator is rotated so as to 20 thereby break electrical contact between the electrical contact member and the electrical terminal.

2. A rotary switch as claimed in claim 1, wherein the disconnecting means comprises at least one ridge arranged 25 to lift the contact member relative to an electrical terminal as the actuator is rotated.

3. A rotary switch as claimed in claim 2, wherein the electrical contact is lifted relative to an electrical 30 terminal when the actuator is rotated by direct contact between the contact member and the at least one ridge.

4. A rotary switch as claimed in claim 3, wherein the location on the contact member which contacts the at least 35 one electrical terminal during use moves in a first arc, and the location on the contact member which makes contact - 12 with the disconnecting means moves in a second arc different to the first arc.

5. A rotary switch as claimed in any one of the 5 preceding claims, wherein a transverse cross-sectional profile of the contact member is of generally curved shape so as to facilitate smooth connection and disconnection between the contact member and the at least one electrical terminal. 10

6. A rotary switch as claimed in claim 5, wherein the contact member comprises a substantially flat central portion and upwardly curved side portions. 15

7. A rotary switch as claimed in any one of the preceding claims, wherein the contact member comprises a generally concave surface arranged to rest on and rotate relative to a common terminal provided in the body portion. 20

8. A rotary switch as claimed in any one of the preceding claims, wherein the contact member is resiliently biased away from the actuator so as to be biased towards the contact surface of the at least one 25 electrical terminal when aligned with that surface.

9. A rotary switch as claimed in claim 8, wherein the actuator comprises a through hole and the rotary switch comprises a spring disposed in the through hole and in 30 contact with the contact member.

10. A rotary switch as claimed in claim 9, wherein the rotary switch comprises a locating ring having at least one trough and at least one crest, and a ball bearing 35 disposed between the locating ring and an end of the spring remote from the contact member, the arrangement being such that the at least one crest, the at least one - 13 trough, the ball bearing, and the spring serve to define predetermined switch positions.

11. A rotary switch as claimed in any one of the 5 preceding claims, wherein the actuator comprises an actuator body and an actuator post extending from the actuator body, the actuator post including a generally cylindrical portion adjacent the actuator body, and the cylindrical portion being formed so as to provide a 10 continuous curved circumferential surface which serves to assist in enabling smooth rotation of the actuator during use.

12. A rotary switch substantially as hereinbefore 15 described with reference to, and as shown in the accompanying drawings.