Technical Field

The disclosure relates generally to switches, and more particularly, to mechanically- actuated plunger switches.

Summary

The disclosure relates generally to switches, and more particularly, to mechanically- actuated plunger switches. In one illustrative embodiment, a plunger switch includes at least a first fixed pair of conductors secured to a housing. Each of the first fixed pair of conductors may have an external connection end and an internal contact end. The switch may further include a movable contact assembly movable with respect to the housing and the first fixed pair of conductors. The movable contact assembly may include a plunger having a rod fixed to a cage. The housing may constrain movement of the rod and the cage along an actuation axis. The movable contact assembly may further include a first shorting bar moveable with respect to the cage of the plunger along the actuation axis, but at least partially constrained by the cage of the plunger. The first shorting bar may have contact ends that are in line with the internal contact ends of the first fixed pair of conductors. The plunger may be movable along the actuation axis between an unactuated position and an actuated position. The first shorting bar may conductively connect the first pair of conductors via the contact ends of the first shorting bar in only one of the unactuated position or the actuated position. The plunger switch may also include a return spring positioned between the housing and the plunger such that the return spring biases the plunger toward the unactuated position. A retention spring may be situated in the cage of the plunger for biasing the first shorting bar toward the first fixed pair of conductors. In some cases, the plunger switch may include a second fixed pair of conductors, and the movable contact assembly may include a second shorting bar. In some instances, the plunger switch may include a flexible boot sealingly fixed to the rod of the movable contact assembly and to the housing.

The above summary is not intended to describe each and every disclosed illustrative example or every implementation of the disclosure. The Description that follows more particularly exemplifies various illustrative embodiments. Brief Description of the Figures

The following description should be read with reference to the drawings. The drawings, which are not necessarily to scale, depict selected illustrative embodiments and are not intended to limit the scope of the disclosure. The disclosure may be more completely understood in consideration of the following description of various illustrative embodiments in connection with the accompanying drawings, in which:

Figure 1 is a schematic view of an inner block of an illustrative plunger switch;

Figure 2 is a schematic partially-exploded view of the illustrative inner block of Figure 1; Figure 3 is a schematic view of an illustrative movable contact assembly of the inner block of Figures 1 and 2;

Figure 4 is a schematic view showing a portion of an illustrative Dual Normally Closed (NC) plunger switch embodiment;

Figure 5 is a schematic view showing a portion of an illustrative Dual Normally Open (NO) plunger switch embodiment;

Figure 6 is a schematic partially-exploded view of an illustrative plunger switch that includes the inner block of Figure 1 , an outer housing, and an actuation ball; and

Figure 7 is a schematic view of the illustrative plunger switch of Figure 6 when fully assembled.

Description

The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected illustrative embodiments and are not intended to limit the scope of the disclosure. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.

Figure 1 is a schematic view of an inner block 100 of an illustrative plunger switch. Contact ends 102 of a first fixed pair of conductors 104 and contact ends 106 of a second fixed pair of conductors 108 may be mechanically and conductively accessible from the exterior of inner block 100. These contact ends 102 and 106 may be electrically connected to an external electrical circuit that the plunger switch helps control. While the illustrative inner block 100 of Figure 1 includes two pairs of conductors, other configurations are contemplated. For example, an inner block may include a single pair of fixed conductors, or may include more than two pairs of fixed conductors, as desired.

The illustrative inner block 100 may include a housing 109, which may include a first cover 110, a second cover 112, and a base bracket 114. First and second covers 110, 112 and base bracket 114 may be secured relative to each other during assembly of the plunger switch. In some instances, two or more of the housing portions may be snap-fit together for simple assembly. The fixed pairs of conductors 104, 108 may be secured to the housing 109. In the illustrative embodiment of Figure 1, the fixed pairs of conductors 104, 108 pass through and may be secured to the base bracket 114 and/or one or more of the first and second covers 110, 112. Other housing configurations are contemplated. For example, first and second covers 110, 112 may alternatively be provided as a single piece, or greater than two pieces. Also, the housing 109 may feature a less enclosed, more open design than that depicted in the illustrative embodiment of Figure 1. The housing 109 may be manufactured from any suitable material or materials, such as plastics, ceramics, glass, etc.

During use, the plunger switch may be actuated by a mechanical force applied to an end 116 of a plunger 127 of the inner block 100, in the direction of arrow 118. Arrow 118 may correspond generally to the direction of an actuation axis 119 of the plunger switch. Force applied to the end 116 of the plunger 127 may result in a substantial displacement of the plunger 127 relative to the housing 109 of the inner block 100.

In some instances, inner block 100 may include a flexible boot 120 that may sealingly protect the interior of the inner block 100 from the surrounding environment. Some features of flexible boot 120 may be appreciated from examination of Figure 2, which is a schematic view of the inner block of Figure 1 in which the first and second covers 110, 112 and the flexible boot have been separated from the remainder of the inner block. Flexible boot 120 may have a first end 122 sealingly fixed to the plunger 127. In some cases, the plunger 127 may include a rod 124 fixed to a cage 126, although other plunger configurations are contemplated. The rod 124 (which in the illustrative embodiment is a component of the plunger 127) may include a groove 128 extending along a circumference of the rod 124. The first end 122 of the flexible boot 120 may include an aperture (not visible in Figure 2) defined by an aperture wall, and the aperture wall of the flexible boot may extend into the groove of the plunger or rod 124, as when assembled in, for example, Figure 1. Flexible boot 120 may have a second end 130 sealingly fixed to the housing 109. The housing 109 may include a groove 132 extending along a circumference to receive an aperture wall of the second end 130 of the flexible boot 120, which may extend into the groove 132.

As illustrated in Figures 1 and 2, the first end 122 of the flexible boot 120 may be offset along the actuation axis 119 relative to the second end 130. When the plunger 127 is moved toward the actuated position (e.g., in the direction of arrow 118), the first end 122 may move toward the second end 130. In the illustrative embodiment, flexible boot 120 of Figures 1 and 2 may be regarded as being dome shaped, with a crown (first end 122) extending above a base (second end 130). When the plunger 127 is moved toward the actuated position, the crown 122 may be pulled down toward the base or second end 130 of dome shaped flexible boot 120. While flexible boot 120 of the illustrative embodiment of Figures 1 and 2 may have a dome shape, other shapes are contemplated. Also, it is contemplated that flexible boot 120 may be manufactured from any suitable material or materials, such as rubbers or plastics. Flexible boot 120 may be composed of an elastic material or materials. When moved between actuated and unactuated positions of the plunger 127, the flexible boot 120 may transition between different elastic potential energy states. The flexible boot may be constructed such that it is in a lower energy state when the plunger 127 is in the unactuated position than when the plunger 127 is in the actuated position, or vice-versa, as desired.

The operational principals of an illustrative plunger switch, such as shown in Figure 1 , may be appreciated by further examination of Figures 2 and 3. Figure 3 is a schematic view of an illustrative movable contact assembly 134 of the inner block 100. The illustrative movable contact assembly 134 is also shown in place with respect to other elements of the inner block in Figure 2. The movable contact assembly 134 includes the plunger 127, which may include rod 124 fixed to cage 126. The first and second covers 110 and 112 of the inner block may constrain movement of the rod 124 and cage 126 along the actuation axis 119. Such constraint may be affected at least in part, for example, by the fit of the rod relative to an aperture 138 formed by the housing 109.

The illustrative movable contact assembly 134 may include a first shorting bar 140 and a second shorting bar 142, both moveable with respect to the cage 126 of the plunger 127 along the actuation axis 119, but also at least partially constrained by the cage 126 of the plunger 127. The cage 126 may define an aperture 144 that extends perpendicular to the actuation axis 119. The shorting bars 140, 142 may pass or extend through the aperture 144 of the cage 126. Further, either or both shorting bars 140, 142 may include one or more portions that extend laterally beyond a perimeter of the cage, as shown. The housing 109 may define an aperture that accommodates the portion(s) of the shorting bar(s) that extend laterally beyond the perimeter of the cage 126. The first shorting bar 140 may have contact ends 146 that are in line with internal contact ends 148 of the first fixed pair of conductors 104. Similarly, the second shorting bar 142 may have contact ends 150 that are in line with internal contact ends 152 of the second fixed pair of conductors 108. One or more of the contact ends 146, 150 of the shorting bars 140, 142 may correspond to those portions that extend laterally beyond the perimeter of the cage 126, but this is not required.

Any of conductors 104, 108, shorting bars 140, 142, contacts 146, 148, 150, 152 may be constructed and configured to support currents of 15A or greater, but this is not required. All or some of contacts 146, 148, 150, 152 may have contact areas of at least 1, 2, 3, 3.5, 5, 7, or 10 mm ² , or any other suitable area. In some instances, plunger switches of the present disclosure may support high voltage, high current applications, as may be applicable in starting conditions for internal combustion engines.

The movable contact assembly 134 may be movable with respect to the housing 109 and the first and second fixed pairs of conductors 104, 108. The plunger 127 may be movable along the actuation axis 119 between an unactuated position and an actuated position. Relative to the page on which Figure 2 is displayed, the plunger 127 may be relatively disposed toward the top of the page in the unactuated position, and toward the bottom of the page in the actuated position (or vice versa in other embodiments). The first shorting bar 140 may conductively connect the first pair of conductors 104 via the contact ends 146 of the first shorting bar in only one of the unactuated position or the actuated position. Similarly, the second shorting bar 142 may conductively connect the second pair of conductors 108 via the contact ends 150 of the second shorting bar in only one of the unactuated position or the actuated position. In Figure 2, the inner block 100 is illustrated with the plunger 127 relatively disposed toward the top of the page such that the first shorting bar 140 conductively connects the first pair of conductors 104, and the second shorting bar 142 does not conductively connect the second pair of conductors 108. This may arbitrarily be considered the unactuated position of the switch (but it could just as arbitrarily be considered the actuated position). As such, with the illustrated configuration designated as unactuated, the switch may be described as normally closed (NC) for the first pair of conductors 104, and normally open (NO) for the second pair of conductors 108.

The plunger switch of Figures 1 and 2 may include a return spring 154 positioned between the housing 109 and the plunger 127 (in Figure 2, the return spring is located between the base bracket 114 and cage 126). The return spring 154 may bias the plunger 127 toward the unactuated position, which may be toward the top of the page in Figure 2. In some illustrative embodiments, a return spring like return spring 1 4 could bias the plunger 127 downward in Figure 2. Return spring 154 may be a coil spring, which may be substantially co-axial with the actuation axis 119 of the movable contact assembly 134, but this is not required.

Movable contact assembly 134 may also include a retention spring 156 situated in the cage 126 of the plunger 127 for biasing the first shorting bar 140 toward the first fixed pair of conductors 104. The retention spring 156 may be situated in the cage 126 of the plunger 127 between the first shorting bar 140 and the second shorting bar 142. In this illustrative configuration, the retention spring 156 may bias the second shorting bar 142 toward the second fixed pair of conductors 108. One or more insulators may be placed between the retention spring 156 and shorting bars 140, 142, if desired. Retention spring 156 may be a coil spring, which may be substantially co-axial with the actuation axis 119 of the movable contact assembly 134, but again, this is not required.

Retention spring 156 may be part of a switching mechanism that affords an amount of positional flexibility when moving between unactuated and actuated positions or modes of the switch, which may be useful when interfacing a plunger switch of the present disclosure into a system. One or more components of a system external to the switch may actuate the switch via forces applied to the plunger mechanism to move it between unactuated and actuated positions. The aforementioned flexibility may allow wider tolerances to exist in the interface between the external parts of the system and the switch compared to other switch designs. For example over- travel of the plunger 127 may be effectively accommodated by the return spring 1 4 and/or retention spring 156.

In the illustrative plunger switch shown in Figures 1 and 2, the movable contact assembly 134 may move over a range of motion along the actuation axis 119. The range of motion may have upper and lower ends, upper and lower being relative to, for example, the page in Figure 2. The switch may be configured such that the first shorting bar 140 may conductively connect the first pair of conductors 104 via the contact ends 146 of the first shorting bar before the movable contact assembly 134 reaches the upper end of the range of motion of the movable contact assembly. Movement of the movable contact assembly 134 beyond when the first shorting bar 140 conductively connects the first pair of conductors 104 via the contact ends 146 of the first shorting bar may be considered over-travel of the movable contact assembly. During over-travel of the movable contact assembly 134, the retention spring 156 may compress. Similarly, the switch may be configured such that the second shorting bar 142 may conductively connect the second pair of conductors 108 via the contact ends 150 of the second shorting bar before the movable contact assembly 134 reaches the lower end of the range of motion of the movable contact assembly. The retention spring 156 may compress during over-travel of the movable contact assembly 134 in the downward direction as well.

The range of motion of the movable contact assembly 134 may be between about 0.5, 1, 2, 3.5, 5, 7, 10, or 15 mm, or any other suitable range. Spacing or gaps between corresponding contacts of shorting bars and fixed conductors when the switch is open may be about 0.3, 0.5, 0.8, 1, 1.2, 1.5, 2, or 4 mm, or any other suitable values as desired.

The illustrative plunger switch of Figure 2 may be considered a 1 NO / 1 NC switch, in which one (1) pair of fixed conductors is normally open, and the other one (1) pair of fixed conductors is normally closed. Other configurations are contemplated, such as 2 NC, of which a portion of an illustrative embodiment is depicted in Figure 4, and 2 NO, of which a portion of an illustrative embodiment is depicted in Figure 5. The illustrative 2 NC mechanism shown in Figure 4 may be configured such that the lower shorting bar is biased toward its corresponding fixed conductors by the action of the return spring on the cage, and the upper shorting bar is biased toward its corresponding fixed conductors by the retention spring. The 2 NO mechanism of Figure 5 may be configured with a cage having two apertures, with a shorting bar extending through each of the two cage apertures, or similarly with a two cage construction, with each cage having an aperture with a shorting bar extending therethrough. In this configuration, each shorting bar may have its own corresponding retention spring for biasing it toward its corresponding fixed conductors. The illustrative 2NC mechanism of Figure 4 may also be configured with a cage having two apertures, as may, for example, an alternative embodiment of a 1 NO / 1 NC switch (not shown). The configurations of Figures 4 and 5 are merely exemplary, and should not be considered limiting. Ordinarily-skilled artisans, after reading the present disclosure, would readily appreciate how to incorporate the design principles disclosed herein to create configurations such as those of Figures 4 and 5, and other configurations.

A plunger switch of the present disclosure may include additional components external to an inner block. Figures 6 and 7 are schematic views of a partially-disassembled and assembled switch assembly that includes an outer housing 160 surrounding at least part of the housing 109 of the inner block 100, and an actuation ball 162. Multiple pieces of the outer housing 160 may be assembled via crimping, threads, adhesive, solder, or any other suitable assembly technique as desired. The outer housing 160 may allow conductive access to the external contact ends 102, 106 of the fixed pairs of conductors. Such conductive access may be provided through any suitable way, such as one or more apertures 164 in the outer housing 160 that allow physical access to the external contact ends 102, 106 and/or conductive pathways through the outer housing 160. In some cases, the switch may support conductive connection via pin, socket terminal, or wire output, meeting IP67 or IP68 code. In some instances, spaces between the inner block 100 and outer housing 160 may be partially or fully filled with an epoxy potting compound or any other suitable material, which in some cases, may help insulate and/or otherwise protect the internal components and/or external contact ends 102, 106.

In some instances, outer housing 160 may include a nipple 166 that provides access to the end 116 of the rod 124 of the plunger 127 of the movable contact assembly 134. In some cases, an actuation ball 162 may be retained by the nipple 166 of the outer housing 160 at the end 116 of the rod 124 along the actuation axis 119. In an installation, the nipple 166 may be affixed via threads 167 to an external mechanism (such as an automobile transmission) where force may be applied to the actuation ball 162, and via the actuation ball, to the movable contact assembly 134.

Switches of the present disclosure may be used in a wide variety of applications. In some cases, such switches may be used for surface transportation vehicle applications, such as for reverse, neutral, high/low switches, and the like. Many other applications will be apparent to persons having ordinary skill in the art. Features of the switches disclosed herein may contribute to longevity and resistance to common failure modes, such as contact welding during use.

The disclosure should not be considered limited to the particular examples described above. Various modifications, equivalent processes, as well as numerous structures to which the disclosure can be applicable will be readily apparent to those of skill in the art upon review of the instant specification. Other steps may be provided, or steps may be eliminated, from the described methods, and other components may be added to, or removed from, the described devices.