Contact levers for electrical switch assemblies

Abstract

A contact lever for an electrical switch assembly, allowing the contact lever contact member to be selectively moved within the switch assembly from being electrically connected to a first fixed contact member to being electrically connected to a second fixed contact member, the contact lever comprising: a first lever arm and a second lever arm connected to the contact lever contact member at respective first ends; the first lever arm and the second lever arm having respective second ends, and the first lever arm and the second lever arm being configured to extend away from the contact member and terminate at their respective second ends; a gap provided between the first lever arm and the second lever arm, the gap separating the first lever arm and the second lever arm as the first lever arm and the second lever arm extend away from the contact member, and wherein the gap is configured to allow movement of a spring element of the switch assembly through the gap; and a bridging member configured to be connected to the first lever arm and the second lever arm so as to cross the gap separating the first lever arm and the second lever arm.

Description

Technical Field

[0001] The present invention relates to a contact lever for an electrical switch assembly. Background Art

[0002] In certain existing electrical switch assemblies, such as snap-action switch assemblies, when a relatively small amount of physical force is applied to an actuator component, a contact lever operably connected to the actuator component via a tension spring will quickly and reliably pry a movable contact component from a position electrically connected to one fixed contact component into a position electrically connected to another fixed contact component of the electrical switch assembly. Such electrical switch assemblies will typically utilize a contact lever on which a movable contact is mounted to allow movement of the movable contact from being electrically connected to one fixed contact to being electrically connected to another fixed contact. The contact lever will typically include a pair of generally parallel lever arms separated by a gap through which the tension spring can be appropriately passed during operation of the electrical switch assembly. One disadvantage of contact levers of this construction is that they tend to deform easily in certain circumstances due to exposure to thermal stresses, such as when used in power tools such as angle grinders that require high rated current capacity. Summary of the invention

[0003] The present invention seeks to alleviate at least one of the above problems.

[0004] The present invention may be embodied in several broad forms. Embodiments of the present invention may be embodied in one or any combination of the different broad forms described herein.

[0005] In a first broad form, the present invention provides a contact lever for an electrical switch assembly to allow a contact lever contact member to be selectively moved within the switch assembly from being electrically connected to a first fixed contact member to being electrically connected to a second fixed contact member, the contact lever comprising: a first lever arm and a second lever arm connected to the contact lever contact member at respective first ends; the first lever arm and the second lever arm having respective second ends, and the first lever arm and the second lever arm being configured to extend away from the contact member and terminate at their respective second ends; a gap disposed between the first lever arm and the second lever arm, the gap separating the first lever arm and the second lever arm as the first lever arm and the second lever arm extend away from the contact member, and wherein the gap is configured to allow movement of a spring element of the switch assembly through the gap; and a bridging member configured to be connected to the first lever arm and the second lever arm so as to cross the gap separating the first lever arm and the second lever arm.

[0006] Preferably, the bridge member may be configured to connect the first and second lever arms at a region along the first and second lever arms so as to define an aperture between the bridge member and the contact lever contact member.

[0007] Preferably, the bridge member may comprise a generally U-shaped configuration.

[0008] Preferably, the present invention may include a contact lever contact member plate having at least one structure disposed in a recess, aperture or abamate therein, the at least one structure being configured for securing a contact lever contact member thereto.

[0009] Preferably, the present invention may include an aperture configured for fastening with a first end of an extension spring of a switch assembly.

[0010] Preferably, the bridging member may comprise an electrically conductive material.

[0011] Preferably, the bridging member may comprise a copper alloy material.

[0012] Preferably, the bridge member may be integrally formed with the first lever arm and the second lever arm.

[0013] Preferably, the switch assembly may include a micro switch assembly.

[0014] In another broad form, the present invention provides a contact lever for an electrical switch assembly to allow a contact lever contact member to be selectively moved within the switch assembly from being electrically connected to a first fixed contact member to being electrically connected to a second fixed contact member, the contact lever comprising: a first lever arm and a second lever arm, the first lever arm and the second lever arm being connected to the contact lever contact member at respective first ends; the first lever arm and the second lever arm having respective second ends, and the first lever arm and the second lever arm being configured to extend away from the contact member and terminate at their respective second ends; a gap, the gap being disposed between the first lever arm and the second lever arm, separating the first lever arm and the second lever arm as the first lever arm and the second lever arm extend away from the contact member, and wherein the gap is configured to allow a spring element of the switch assembly to move through the gap; wherein the contact lever comprises a contact lever layer, the contact lever layer being bonded or coupled to the contact lever to form a multilayer structure having an increased cross-sectional thickness.

[0015] Preferably, the contact bar layer may comprise further contact bars which are bonded or joined to the contact bars to form a multilayer structure with an increased cross-sectional thickness.

[0016] Preferably, the present invention may include a bridging member configured to connect with the first lever arm and the second lever arm so as to span a gap separating the first lever arm and the second lever arm.

[0017] Preferably, the bridge member may be configured to connect the first and second lever arms at a region along the first and second lever arms so as to define an aperture between the bridge member and the contact lever contact member.

[0018] Preferably, the bridge member may comprise a generally U-shaped configuration.

[0019] Preferably, the present invention may include a contact lever contact member plate having at least one structure disposed in a recess, aperture or cutout therein, the at least one structure being configured for securing a contact lever contact member thereto.

[0020] Preferably, the present invention may include an aperture configured for fastening with a first end of an extension spring of a switch assembly.

[0021] Preferably, the bridging member may comprise an electrically conductive material.

[0022] Preferably, the bridging member may comprise a copper alloy material.

[0023] Preferably, the bridge member may be integrally formed with the first lever arm and the second lever arm.

[0024] Preferably, the switch assembly may include a micro switch assembly.

[0025] In another broad form the invention provides an electrical switch assembly comprising a contact lever according to any one of the features of the first broad form of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be more fully understood from the following detailed description of preferred but non-limiting embodiments thereof described in conjunction with the accompanying drawings, in which:

[0027] Figure 1 A perspective view showing a prior art contact lever for a micro switch assembly;

[0028] Figure 2A and Figure 2B Accordingly, a side view of a prior art microswitch assembly is shown with a prior art contact lever arranged in a first position and a second position.

[0029] Figure 3A , Figure 3B and Figure 3C A perspective view, a top view and a side view of an exemplary contact rod according to an embodiment of the present invention are shown accordingly.

[0030] Figure 4 Shown where used Figure 3A , Figure 3B and Figure 3CAn exploded view of an exemplary microswitch assembly of an exemplary contact lever embodiment is shown in FIG.

[0031] Figure 5A and Figure 5B Shown where used Figure 3A , Figure 3B and Figure 3C A side view of an exemplary micro switch assembly of an exemplary contact lever embodiment is shown in FIG. Figure 5A In the embodiment, the contact lever is arranged so that a movable contact member mounted thereon is in electrical communication with a contact member of a normally closed (NC) electrical terminal, and Figure 5B wherein the contact lever is arranged so that a movable contact member mounted thereon is in electrical communication with a contact member of a normally open (NO) electrical terminal;

[0032] Fig. 6A , Figure 6B , Figure 6C and Fig.6D A side view, a front view, a top perspective view and a bottom perspective view are respectively shown of an exemplary contact rod according to another embodiment of the present invention, wherein the cross section of the contact rod is thickened by coupling two contact rods together; and

[0033] Fig. 7A and Figure 7B Accordingly, the device is shown with a first position and a second position. Fig. 6A A side view of a microswitch assembly showing an exemplary contact lever is shown. DETAILED DESCRIPTION

[0034] Reference will now be made to the accompanying drawings Figures 1 to 7B Preferred embodiments of the present invention are described herein. Although embodiments of the present invention will be described with respect to use with a micro-switch type electrical switch assembly (also referred to as a micro-snap-action switch), it will be understood that this is for illustrative purposes only and that the electrical switch assembly may not necessarily be limited to a micro-switch type switch assembly.

[0035] In such Figure 1-2BIn the prior art micro switch assembly shown in , when a user's finger applies a relatively small amount of force to the actuator component 21 to press it toward the inside of the housing 20A, the contact rod 25, which is operably connected to the actuator component 21 via the yoke 22 and the tension spring 23, moves the movable contact component 27 from a position electrically connected to one fixed contact component to a position electrically connected to another fixed contact component 28 of the electrical switch assembly. The prior art contact rod 25 is also in a state of fixed electrical connection with the common terminal 26 of the prior art switch assembly. The prior art contact rod 25 used in such an assembly is configured to mount the movable contact 27 of the electrical switch assembly at one end to allow the movable contact 27 to move from being electrically connected to one fixed contact to being electrically connected to another fixed contact. As shown in Figure 1 As shown in , the prior art contact lever 25 used in this assembly will typically include a pair of generally parallel lever arms 11A, 11B separated by a gap 11C therebetween through which the tension spring 23 can be suitably received when the tension spring 23 is operably connected to the contact lever and during normal operation of the prior art electrical switch assembly. Figure 1-2B It will be seen, and will be appreciated by those skilled in the art, that one disadvantage of contact rods 25 having this type of construction and structure is that they tend to deform relatively easily in certain circumstances, such as, for example, due to exposure to heat, temperature and / or mechanical stresses, which is particularly problematic when such contact rod components are used in electrical switch assemblies of power tools such as angle grinders requiring relatively high rated current capacities.

[0036] Now refer to Figure 3- Figure 5B , shows an embodiment of the present invention that helps to alleviate the above problems. In this embodiment, the housing includes a main body 30A and a cover 30C, and the cover 30C can be fastened to the main body 30A to accommodate various components of the electrical switch assembly therein. The main body 30A is molded from any suitable durable material and is configured to seat the various components in appropriate positions relative to each other so that they can interact with other components in an operative manner during normal use of the electrical switch assembly. The main body 30A also includes a pair of mounting apertures 30B to allow the housing to be installed in an electrical device. As shown in Figure 4 , Figure 5A and Figure 5BAs shown in , the electrical switch assembly includes a normally closed (NC) electrical terminal 38B and a normally open (NC) electrical terminal 38A, both of which are seated relative to the main body 30A of the housing so that the first ends of the respective electrical terminals 38A, 38B extend outward from the main body 30A of the housing, while the second ends of the electrical terminals 38A, 38B are located inside the main body 30A of the housing and have respective fixed contact members 39A, 39B attached to the second ends to electrically communicate with the movable contact 39 of the electrical switch assembly. The electrical switch assembly 30 of this embodiment also includes a common electrical terminal 40, which is configured to be in fixed electrical communication with the movable contact member 39 via a conductive contact rod.

[0037] The contact lever is also mounted in the body 30A of the housing in a manner that it can move around the hinge member. Figure 3A-3C Neutralization Figure 4 In the exploded view of the electrical switch assembly in FIG. 1 , the contact lever is shown in isolated form and is Figure 5A and Figure 5B 3 is shown in a fully assembled form of an electrical switch assembly. The contact lever includes a first lever arm 31A and a second lever arm 31B, which are connected to a contact component plate 32 at respective first ends, on which a movable contact component 39 is securely mounted. The movable contact component 39 in this embodiment is configured to be frictionally fitted into an aperture 34 formed in the contact component plate 32. The first lever arm 31A and the second lever arm 31B also have respective second ends, whereby the first lever arm 31A and the second lever arm 31B are configured to extend away from the contact component plate 32 and terminate at their respective second ends. As shown in FIG. 3 , a gap 31C is provided between the first lever arm 31A and the second lever arm 31B, and the gap 31C separates the first lever arm 31A and the second lever arm 31B as the first lever arm 31A and the second lever arm 31B extend away from the movable contact component 39.

[0038] The contact member plate 32 also includes a further aperture 33 configured for anchoring one end of a tension spring 36 (the other end of the tension spring being anchored to a second fixed anchor point 42 molded into the inner surface of the housing body 30A) such that, in use, the body of the tension spring 36 will be freely received within the gap 31C when operably connected to the contact lever and during normal operation of the contact lever. In contrast to the above-described prior art contact lever configuration, the bridging member 35 is configured for connecting the first lever arm 31A and the second lever arm 31B, whereby the bridging member 35 spans the gap 31C separating the first lever arm 31A and the second lever arm 31B, and provides structural support for the contact lever. In particular, by supporting the first lever arm and the second lever arm substantially in a fixedly spaced relationship, the bridging member 35 helps mitigate deformation of the contact lever due to thermal and / or mechanical stresses applied to the material of the contact lever. Furthermore, the novel structure including the bridging member 35 helps to provide the contact rod with a more robust overall structure, which can help to increase the overall product yield of such contact rod components during manufacturing. In particular, compared to the prior art contact rods described herein, which may be relatively susceptible to damage when being stamped during production due to their lack of a bridging structure, this problem is alleviated during stamping due to the overall stronger and / or more rigid structure of the contact rod. Furthermore, because the novel structure including the bridging member 35 increases the overall strength of the contact rod structure, copper alloys with lower stiffness (or any other suitable material known to those skilled in the art) can be utilized, which tends to increase conductivity through the contact rod and thereby allow for a higher rated current capacity. Furthermore, in these embodiments of the present invention, the bridging member 35 is formed and sized in a generally U-shaped configuration so as to not unduly obstruct the movement of the tension spring 36 within the gap 31C. Although in Figure 4 - In the embodiment shown in FIG. 5 , the bridge member 35 appears to extend on the underside of the contact lever, but it may also be positioned to extend above the contact lever, and may also be positioned further along the section of the contact lever arms 31A, 31B away from the movable contact member 39 than as shown in the exemplary drawing, and may have varying dimensions depending on the geometry of other components within the electrical switch assembly. Furthermore, more than one bridge member 35 may also be utilized, and such bridge members may also be shaped and positioned so as not to unduly block the movement of the extension spring within the gap or interfere with the normal operation of other components within the electrical switch assembly.

[0039] The contact lever may typically be constructed of a conductive copper alloy material, and the bridge member 35 may either be integrally formed with the contact lever or may be, for example, welded to the contact lever arms 31A, 31B to connect the first lever arm 31A and the second lever arm 31B.

[0040] The actuator member 31 is also seated relative to the main body 30A of the housing so that a relatively small amount of force applied by a user's finger can press the actuator member 31 inwardly of the main body 30A. A sealing ring 41 is also provided to help prevent dust and water from intruding into the housing 30A through the opening through which the actuator 31 moves. Figure 5A The contact lever is shown, which is arranged so that the movable contact 39 is electrically connected to the fixed contact part 39B of the NC electrical terminal 38B. When the actuator 31 is pressed, the yoke 37 and the tension spring 36 that operably connect the actuator 31 to the contact lever are configured to achieve the movement of the contact lever in a snap-action (or eccentric) manner, so that the movable contact part 39 mounted on the contact lever moves from the fixed contact part 39B to the fixed contact part 39B of the NC electrical terminal 38B. Figure 5A , and is electrically connected to the fixed contact member 39B of the NC electrical terminal 38B, and is moved as shown in Figure 5B 3A is shown in electrical communication with the fixed contact member 39A of the NO electrical terminal 38A.

[0041] In some embodiments, alternatively, or in addition to a bridge member connecting the first and second arms of the contact bar, the contact bar 50 may be formed by combining or coupling two or more separate contact bars 50A, 50B together. Figure 6A-6D (contact rod in independent mode) and Figure 7A-7B As shown in FIG. 6A and FIG. 7 (Contact rod assembled in micro switch device 60), one example of such a contact rod 50 is shown as being formed by welding two separate contact rods 50A, 50B together in a multi-layer manner, thereby thickening the cross-sectional profile of the resulting contact rod 50 by the stacking of layers. In addition to using welding and separate contact rods 50A, 50B, the contact rods 50A, 50B may be joined together by any suitable joining or coupling means, such as by riveting. The separate contact rods 50A, 50B do not need to have the same overall shape and size, however, in this embodiment, the separate contact rods 59A, 59B are formed so that the contact rod arms 59A, 59B and the apertures 54, 54 provided in each contact rod 50A, 50B are appropriately positioned so that the separate contact rods 50A, 50B are aligned when they are joined or coupled together.

[0042] Furthermore, in still further embodiments, instead of bonding or joining two fully formed contact bars together to increase the thickness and strength of the cross-sectional profile, one or more alloy pieces may be bonded or joined together to only specific areas of a contact bar in order to increase the cross-sectional thickness of only those specific areas (e.g., bar arms 59A, 59B) of contact bar 50. By increasing the cross-sectional thickness of contact bar 50 in this manner, this may also help mitigate deformation of contact bar 50 due to thermal and / or mechanical stresses applied to the material of contact bar 50.

[0043] It will be appreciated by those skilled in the art that variations and modifications other than those specifically described may be implemented to the invention described herein without departing from the scope of the invention. All such variations and modifications that will become apparent to those skilled in the art should be considered to fall within the spirit and scope of the invention as broadly described above. It should be understood that the present invention includes all such variations and modifications. The present invention also includes, individually or collectively, all steps and features mentioned or indicated in the specification, and any and all combinations of any two or more of said steps or features.

[0044] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that the prior art forms part of the common general knowledge.

Claims

1. A contact lever for an electrical switch assembly to allow a contact lever contact member to selectively move from being electrically connected to a first fixed contact member to being electrically connected to a second fixed contact member within the switch assembly, the contact lever comprising: a contact lever contact member plate having at least one structure disposed in a recess, aperture, or cutout therein, the at least one structure being configured for securing the contact lever contact member thereto; a first lever arm and a second lever arm connected to the contact lever contact member plate at respective first ends; The first lever arm and the second lever arm have respective second ends, and the first lever arm and the second lever arm are configured to extend away from the contact member and terminate at their respective second ends; a gap disposed between the first lever arm and the second lever arm, the gap separating the first lever arm and the second lever arm as the first lever arm and the second lever arm extend away from the contact member, and wherein the gap is configured to allow movement of a spring element of the switch assembly through the gap; and a bridging member configured to connect with the first lever arm and the second lever arm so as to span the gap separating the first lever arm and the second lever arm; wherein the bridge member is configured to connect the first lever arm and the second lever arm at a region along the first lever arm and the second lever arm so as to define an aperture between the bridge member and the contact lever contact member, the aperture being configured to be fastened with a first end of a tension spring of the switch assembly; Wherein the bridging member is shaped and dimensioned in a generally U-shaped configuration so as not to unduly obstruct movement of an extension spring of the switch assembly within the gap.

2. The contact beam of claim 1, wherein the bridging member comprises an electrically conductive material. The contact beam of claim 1 , wherein the bridge member comprises a copper alloy material.

4. The contact lever of claim 1, wherein the bridge member is integrally formed with the first lever arm and the second lever arm.

5. The contact lever of claim 1, wherein the switch assembly comprises a micro switch assembly.

6. An electrical switch assembly comprising a contact lever according to any one of claims 1 to 5.

Images