Contactless switch with shielded vane

A switch includes a switch housing, a button, a circuit board having at least one magnet sensor, and a magnet holder, including at least one magnet, movably mounted to the housing to move responsive to an actuation of the button. A vane interrupter in the switch includes a passage structure positioned proximate to each magnet sensor such that a respective magnet is movable at least partially within a passage defined by the passage structure, and a flange structure having a first flange and a second flange positioned on opposing ends of the passage structure, with the first flange positioned adjacent a portion of the magnet holder holding the magnet and with the second flange positioned adjacent a surface of the circuit board opposite a surface on which the at least one magnet sensor is positioned, such that the circuit board is positioned between the magnet holder and the second flange.

BACKGROUND OF THE INVENTION

The present invention relates generally to control switches and, more particularly, to a contactless control switch that includes a shielded vane therein to provide magnetic shielding to a magnetic sensor of the switch.

Electrical switches are used as control switches for a variety of applications in various industries, with one such example being in specialty vehicle markets—such as heavy trucks, agricultural equipment, and construction equipment, for example—where the switches are employed to control the motor vehicle lighting, the windshield wipers, the rear windshield heating, the cruise control functions, the internal central locking and other functions on and off. Often the control switches are in the form of rocker switches that may be pushed by an operator to rotate/tilt from a neutral position (i.e., switched-off state) to one or more activated positions (i.e., a switched-on state) that control operation of an associated system/component, although control switches may also be constructed as pushbutton switches or toggle switches as other examples.

One type of common control switch is a contactless switch that operates by moving a magnet past a fixed magnetic sensor, such as a Hall effect IC or a magnetoresistive sensor, in order to control and determine the functions/modes provided by the switch. With respect to contactless control switches that are utilized for one of various applications, it is recognized that existing designs of such switches can limit the performance thereof. For example, existing contactless control switches constructions may suffer from issues regarding the ability of the magnetic sensors to detect the magnetic field with sufficient strength, such that discerning a distinct switching position may be difficult. This problem of correctly discerning a distinct switching position may be further compounded if the switch is not constructed in a fashion that provides the magnetic sensors with sufficient protection from external magnetic fields, as the presence of such external magnetic fields interferes with the ability of the magnetic sensors to attribute a sensed magnetic field to the switch magnets.

To provide protection from external magnetic fields, some prior art contactless control switches implement a shielding housing that completely surrounds the switch in order to block the external magnetic fields from the magnetic sensors therein. While such shielding housings may be effective in providing magnetic shielding, it is recognized that the housing can be bulky and increase the size of the switch. Such shielding housings can also increase the overall cost of the switch, as they necessitate the addition of an entirely separate/additional component to the switch.

It would therefore be desirable to provide a contactless control switch that is resistant to the influence from external magnetic fields. It would further be desirable for such a contactless control switch to be provided with such external magnetic field shielding without requiring the addition of a dedicated/separate shielding housing.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one aspect of the invention, a switch includes a switch housing, a button moveably mounted to the housing, a circuit board mounted to the housing and including at least one magnet sensor and a magnet holder, including at least one magnet, movably mounted to the housing so as to move responsive to an actuation of the button by a user, such that the at least one magnet is selectively movable to positions distal to and proximate to the magnet sensor. The switch also includes a vane interrupter having a passage structure positioned proximate to each magnet sensor of the at least one magnet sensor such that a respective magnet of the at least one magnet is movable at least partially within a passage defined by the passage structure and a flange structure positioned adjacent each passage structure, the flange structure comprising a first flange and a second flange positioned on opposing ends of the passage structure, with the first flange positioned adjacent a portion of the magnet holder holding the magnet and with the second flange positioned adjacent a surface of the circuit board opposite a surface on which the at least one magnet sensor is positioned, such that the circuit board is positioned between the magnet holder and the second flange.

In accordance with another aspect of the invention, a switch includes a switch housing, an operating member mounted to the switch housing and movable between a plurality of positions responsive to physical actuation thereof by an operator, one or more magnet sensors secured relative to the housing, and a magnet holder mounted to the housing to position one or more magnets included thereon adjacent the one or more magnet sensors, the magnet holder moving responsive to an actuation of the operating member by a user so as to provide for positioning of the one or more magnets. The switch also includes a vane interrupter configured to provide selective magnetic shielding about the one or more magnets and to the one or more magnet sensors, the vane interrupter comprising a C-shaped frame that includes a lengthwise member oriented generally parallel to a direction of movement of the one or more magnets to form a passage sized to accommodate positioning of a respective magnet of the one or magnets therein and a pair of flanges formed on or attached to opposing ends of the lengthwise member and oriented generally perpendicular thereto. A respective magnet sensor of the one or more magnet sensors and a respective magnet of the one or more magnets are positioned between the pair of flanges of the C-shaped frame, such that the pair of flanges provide shielding to the respective magnet sensor from external magnetic fields.

In accordance with yet another aspect of the invention, a rocker switch includes a switch housing, a rocker button mounted to the switch housing and actuatable between a neutral position, a first position, and a second position, a magnet holder including therein a first magnet and a second magnet and being mounted to the housing so as to be rotatable relative thereto, a first Hall effect sensor and a second Hall effect sensor positioned adjacent the first magnet and the second magnet, respectively, and a vane interrupter comprising a C-shaped frame on each of opposing sides thereof such that a first C-shaped frame is positioned adjacent the first magnet sensor and the first magnet and a second C-shaped frame is positioned adjacent the second magnet sensor and the second magnet. Each of the C-shaped frames further includes a passage structure positioned proximate to a respective magnet sensor such that a respective magnet is movable at least partially within a passage defined by the passage structure and a flange structure positioned adjacent the passage structure and including a first flange and a second flange positioned on opposing ends of the passage structure, with the flange structure positioned to shield its respective Hall effect sensor from external magnetic fields.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a contactless control switch that is resistant to the influence from external magnetic fields. The contactless control switch is constructed to have one or more moveable magnets that provide two or three distinct switching positions, with the magnets generating a magnetic field sensed by one or more magnetic sensors in the switch such that a distinct switching position of the control switch may be easily discerned. A shielded vane interrupter incorporated in the switch provides shielding to the one or more magnetic sensors from external magnetic fields, so as to improve the functionality of the contactless control switch and provide for better discernment of the distinct switching positions for the switch.

While contactless control switches are described here below as being employed as vehicle control switches, it is recognized that the switches could be used in applications outside of vehicle control switches. Accordingly, embodiments of the invention are not limited to use as vehicle control switches and it is understood that the scope of the invention extends to contactless control switches for various other applications.

Referring toFIG. 1, a switch module10is illustrated according to an embodiment of the present invention. The switch module10includes a number of control switches12therein. The switch module10includes communication ports and a power receptacle (not shown) formed on a back surface thereof to enable powering of the module and communication to/from the module, such as via mating of the module10with a communication interface feature that enables the switch modules to communicate with a communication bus, such as a CAN or LIN bus, for example. It is recognized that a greater or smaller number of switches12could be included in the switch module10, and that the arrangement of switches12in the module10could differ, such as the switches being arranged in a single row or in two rows, for example. Thus, the switch module10illustrated inFIG. 1is meant to be an example only and is not meant to limit the scope of the invention in any regard.

According to one embodiment, the switch module10may be incorporated as part of the dashboard in a motor vehicle, such as a heavy truck, goods vehicle, agricultural equipment, or construction equipment, for example. An operator of the vehicle uses the control switches12to operate various functions in the vehicle, such as for switching the motor vehicle lighting, the windshield wipers, the diesel fuel heating, or controlling other specialized equipment on the vehicle—such as a power take-off (PTO) or “safety” related vehicle feature.

As shown inFIG. 1, according to an exemplary embodiment, the control switches12are constructed as rocker switches that include an operating member14—in the form of a rocker button—that is moveably mounted to a switch housing16. The rocker button14is actuated/pushed by an operator to control operation of the respective switch, with the rocker button14being movable between a neutral/off position and one or two activated positions. That is, if the operator pushes one side of the rocker button14, the button is moved to a first activated switch position, and if the operator pushes the other side of the rocker button14, the button is moved to a second activated switch position.

Referring now toFIGS. 2 and 3, partially exploded and fully exploded views of the switch module10ofFIG. 1are illustrated. As shownFIGS. 2 and 3, switch12includes a switch profile member18disposed on an underside of rocker button14. Switch profile member18has a profile contour20that is disposed on the underside of button14and interacts with a plunger22that is biased toward profile contour20by a spring24, with the plunger22and spring24being surrounded by a seal25. The contact made by the end26of biased plunger22against profile contour20dictates the tactile response of rocker button14felt by the user. The illustrated example shows but one example contour20, and other contours may be implemented according to embodiments of the invention. Several forms of switching action may be provided by selecting a corresponding profile contour20. Such switching action can include, for example, momentary, sustained, two position or three position.

As shown inFIG. 3, the switch module10also includes a frame28, magnet holder30, magnets34,36, a printed circuit board (“PCB”) assembly38and a back cover40. The PCB assembly38includes a pair of electromagnetic sensors42,44thereon—a first sensor42and a second sensor44—that, according to one embodiment, are Hall Effect sensors configured to detect magnets34,36, but may instead be magnetoresistive (MR) sensors, for example. Hall Effect sensors42,44act as transducers responsive to the magnetic field of magnets34,36, which can be permanent magnets according to one aspect of the present teachings. According to one aspect of the present teachings, back cover40and frame28together form the switch housing16, with the PCB assembly38being mounted therein. In one embodiment, a top surface of the frame28will be generally flush with a system in which the switch module10is utilized, such as a vehicle dashboard, for example. In one embodiment, when housing16is assembled, PCB assembly38is mounted within housing16, so as to be sealed therein such that it is protected from dirt, water, etc. in the ambient environment, although in other embodiments no seal may be provided about PCB assembly38. Sensors42,44are mounted on PCB38within housing16so as to be disposed beneath magnets34,36, with the frame28separating the sensors42,44from the magnets34,36and magnet holder30. Other electromagnetic sensors may be implemented in lieu of Hall Effect sensors, such as any sensor that can detect electromagnetic field strength. In other aspects, the sensors42,44may be electromagnetic field sensors that act as transducers generating a signal proportional to one or more aspects of the electromagnetic fields generated by magnets. According to other aspects of the present teachings, housing16may be formed of a single piece, or more than two pieces. In addition, the PCB assembly38may be mounted to the housing16in different ways and in different orientations. In one non-limiting example, PCB assembly38can be mounted underneath the housing16.

The PCB assembly38also includes light emitting diodes (LEDs)46affixed thereto to provide illumination of the rocker button14(i.e., graphic icons on the rocker buttons), so as enable identifying of the switch function and provide a visual indication of the switch state to a user. The LEDs46may emit light through rocker button14by passing the light through light pipes (not shown) constructed from a transparent material that directs the emitted light toward button14. Light pipes can be molded directly into frame28or can be a separate discrete component. The brightness of the LEDs46can be controlled, for example, via LIN or CAN messages received by the switches12.

According to one embodiment, the circuit board38may still further include control circuitry (e.g., controller or microprocessor) thereon, generally indicated at50, that is in operable communication with the sensors42,44. The control circuitry50is operative to read the outputs of the sensors42,44of each switch12and, in response, generate output signals that control operation of devices controlled by the switches. The control circuitry50may function as a multiplex communication device (using a CAN or LIN protocol, for example) to interface with other devices or a controller (not shown), or it can output signals directly to an external controller (not shown).

Referring still toFIG. 3, the switch12further includes a vane interrupter52therein that is attached to the housing16so as to be in a fixed position relative thereto. The vane interrupter52is formed from sheet metal, such as from iron or another ferrous material, or may be formed of any magnetic material, including but not limited to magnetic stainless steel. The vane interrupter52functions to selectively attenuate the magnetic field generated by each of magnets34,36based on a position of the magnets relative to the vane interrupter52and also provides shielding to the magnetic sensors42,44from external magnetic fields. Accordingly, the vane interrupter52functions to allows the switch sensors42,44to deactivate when the switch is in the center/neutral position (i.e., when the magnets are centered within the vane interrupter52) by deflecting the field of the permanent magnets34,36away from the respective sensors42,44, with the vane interrupter52also providing for better discernment of the distinct switching positions for the switch12.

As can be seen inFIG. 3and in greater detail inFIG. 4, in an exemplary embodiment, the vane interrupter52is formed as a single, integral component that includes a cross-member54with a C-shaped frame56positioned on each end thereof that is oriented perpendicular to the cross-member. The C-shaped frame56includes a passage structure58and a flange structure60that collectively provide for the attenuation of the magnetic field generated by each of magnets34,36and the magnetic shielding to the magnetic sensors42,44from external magnetic fields. While the vane interrupter52is described above and shown inFIGS. 3 and 4is a single, integral component, it is recognized that the vane interrupter52could be formed/provided as a multi-piece component. More specifically, it is recognized that the C-shaped frame56could be formed as a multi-piece component, with the flange structure60provided as a separate piece or pieces that are affixed to the C-shaped frame56of vane interrupter52in a securable fashion.

The passage structure58is formed from a plurality of walls62—e.g. a first wall, second wall, third wall and fourth wall—that collectively define a passage64therein, with the passage structure58being formed on a lengthwise member65of the C-shaped frame56at a central location thereon such that openings are provided on opposing ends thereof. While the illustrated passage structure58is shown as forming a passage having a rectangular cross-sectional shape, other passage shapes may be implemented, such as circular cross sections, triangular cross-sections, and several other possible cross-sectional shapes. The passage64defined by the passage structure58is sized so as to accommodate positioning of a member of the magnet holder (and a magnet34,36) therein and allow for translation/movement of the magnet holder30therethrough, such that positioning of the respective magnet34,36relative to the passage structure58can be varied responsive to an actuation of the operating member14of switch12. Accordingly, when a magnet34,36is positioned within passage64, the passage structure58almost completely surrounds the magnet, although it is recognize that the passage structure58of vane interrupter52need not completely surround the magnet to have the desired effect and that the passage structure58could instead only partially surround the magnet. When positioned within the passage64, the magnetic field of the magnet34,36is attenuated by the passage structure58of vane interrupter52, such that the magnetic field detected by a respective sensor42,44is caused to drop much more rapidly than without the vane interrupter.

The flange structure60of the C-shaped frame56is composed of a first flange66and a second flange68located at opposing ends of the lengthwise member, with the first and second flanges66,68being formed on lengthwise member65(or attached thereto) so as to generally be perpendicular to the lengthwise member65. It is recognized, however, that the first flange66may, for example, be formed/attached at a slight angle off of perpendicular to accommodate movement of the magnet holder30relative thereto (i.e., matching a profile/slope of the magnet holder). The first and second flanges66,68are formed/attached on the lengthwise member65so as to be spaced apart from the passage structure58by a gap70. The gap70between the first flange66and the passage structure58allows for positioning of the magnet holder30therebetween and provides for adequate movement of the magnet holder30, while the gap70between the second flange68and the passage structure58allows for positioning of a magnetic sensor42,44therebetween. Accordingly, the first flange66is positioned adjacent (i.e., above) a portion of the magnet holder30holding the magnet34,36and the second flange68is positioned adjacent a surface72of the circuit board38opposite a surface74on which the magnetic sensors42,44are positioned (i.e., the second flange68is positioned on a bottom surface of circuit board38), such that the circuit board38is positioned between the magnet holder30and the second flange68.

Based on the positioning and shaping of the passage structure58and first and second flanges66,68of flange structure60, the C-shaped frames56of the vane interrupter thus provide an “open” magnetic shielding structure for their respective magnetic sensor42,44that form a continuous path to deflect the external magnetic fields around the magnetic sensors42,44. That is, while gaps70are formed between the first and second flanges66,68and passage structure58such that the C-shaped frame56is an “open” structure, the positioning of the flanges66,68below the magnetic sensors42,44and above the passage structure58provide a continuous shielding path that acts to deflect an external magnetic field around the magnetic sensors42,44.

Referring now toFIG. 5, a switch12of switch module10is shown in its center, or neutral position. Magnetic sensors42,44are mounted on PCB assembly38, which in turn is mounted to housing16. Magnetic sensors42,44are mounted underneath frame28, which separates sensors42,44from permanent magnets34,36in holder30. Magnets34,36are disposed inside passages64of the ferrous vane interrupter52when the switch12is in its center/neutral position. When magnets34,36are disposed within passages64, vane interrupter52attenuates the magnetic field of permanent magnets34,36at Hall-effect sensors42,44to a value lower than would otherwise be felt without the presence of vane interrupter52. In the illustrated position, sensors42,44and the connected electronics on PCB assembly38detect that the switch12is not in an activated position.

Referring now toFIG. 6, as rocker button14is rotated clockwise from the center position, the button14pushes magnet holder30causing it to rotate. Magnet34has moved closer to Hall-effect sensor42and closer to an opening of passage structure58. As magnets34,36move closer to openings of passage structure58, the attenuating effect of vane interrupter52diminishes. As a result of the change in position, the intensity of the magnetic field at sensor42rises more rapidly than would otherwise occur without vane interrupter52, such that sensor42is able to detect an activation of switch12before switch12is fully rotated in the clockwise direction. Upon a full actuation of switch12, the switch12is at its terminal position at the end of its travel in the clockwise direction. In this position, vane interrupter52has little effect on the magnetic field surrounding magnet34, and the magnetic field at sensor42is at its highest intensity. In the illustrated position, the magnetic field at sensor44is at its lowest intensity as magnet36is at its furthest position distal to sensor44.

As shown inFIG. 7, switch12can also be rotated in the opposite direction—i.e., in the counterclockwise direction. When the rocker button14is actuated/depressed to cause the switch12to move in the counterclockwise direction from its center/neutral position, the magnet36is caused to be moved sufficiently close to sensor44to detect actuation. Like the clockwise rotation of switch12, the counterclockwise rotation can result in sensor44detecting the magnetic field of magnet36before magnet36reaches a terminal position closest to sensor44. As with the end of travel in the clockwise position, when the switch12reaches the end of travel in the counterclockwise direction, magnet34is at its furthest position from sensor42when magnet36is at its terminal position closest to sensor44. According to an aspect of the present teachings, no contact between Hall-effect sensors42,44and magnets34,36is necessary for switch12to function. Further, none of magnets34,36or holder30must penetrate the switch housing in order to effectuate switching.

Referring now toFIGS. 8-10, a dual pushbutton switch76is illustrated according to another embodiment of the invention. The dual pushbutton switch76includes a pair of pushbuttons78that are actuated/pushed by an operator to control operation of various functions, such as functions in a vehicle. The dual pushbutton switch76also includes a switch housing80that is configured to receive the pair of pushbuttons78therein. As can be seen inFIGS. 9 and 10, the underside of each pushbutton78includes protrusions or flanges82that interact with a magnet holder84of the switch76in order to cause movement of the magnet holder84when the button78is depressed, as well as a magnet86secured on the magnet holder84. As shown inFIG. 9, the switch76also includes a printed circuit board (“PCB”) assembly38having an electromagnetic sensor42thereon that, according to one embodiment, is a Hall Effect sensor configured to detect a magnetic field generated by magnet86. Sensor42is mounted on PCB38within housing80so as to be disposed above magnet86.

Referring still toFIGS. 9 and 10and additionally toFIG. 11, the switch12further includes a vane interrupter88therein that is attached to the housing80so as to be in a fixed position relative thereto. Similar to the vane interrupter52ofFIG. 4, vane interrupter88is formed from a ferrous material or any magnetic material, including but not limited to magnetic stainless steel. The vane interrupter88functions to selectively attenuate the magnetic field generated by magnet86based on a position of the magnet relative to the vane interrupter and also provides shielding to the magnetic sensor42from external magnetic fields.

As can best be seen inFIG. 11, in an exemplary embodiment, the vane interrupter88is formed as a C-shaped frame that includes a passage structure90and a flange structure92that collectively provide for the attenuation of the magnetic field generated by magnet86and provide magnetic shielding to the magnetic sensor42from external magnetic fields. The passage structure90is formed from a plurality of walls94that collectively define a passage96therein, with the passage structure90being formed on a lengthwise member98of the vane interrupter88. The passage96defined by the passage structure90is sized so as to accommodate positioning of a member of the magnet holder84(FIGS. 9 and 10) and magnet86therein and allow for translation/movement of the magnet holder84therethrough, such that positioning of the magnet86relative to the passage structure90can be varied responsive to an actuation of the pushbutton78of switch76. Accordingly, when magnet86is positioned within passage96, the passage structure90almost completely surrounds the magnet. When positioned within the passage96, the magnetic field of the magnet86is attenuated by the passage structure90of vane interrupter88, such that the magnetic field detected by the sensor42is caused to drop much more rapidly than without the vane interrupter.

The flange structure92of the vane interrupter88is composed of a first flange100and a second flange102located at opposing ends of the lengthwise member98, with the first and second flanges100,102being formed so as to generally be perpendicular to the lengthwise member98. The first and second flanges100,102are formed on the lengthwise member98so as to be spaced apart from the passage structure90by a gap104. The gap104between the first flange100and the passage structure90allows for positioning of the magnetic sensor42therebetween, with the first flange100being positioned adjacent a surface106of the circuit board38opposite a surface108on which the magnetic sensor42is positioned (i.e., the first flange100is positioned on a top surface106of circuit board38), such that the circuit board38is positioned between the magnet86and the first flange100.

Based on the positioning and shaping of the passage structure90and first and second flanges100,102of flange structure92, the C-shaped vane interrupter88thus provides an “open” magnetic shielding structure for the Hall effect sensor42that forms a continuous shielding path to deflect the external magnetic fields around the Hall effect sensor42. That is, while gaps104are formed between the first and second flanges100,102and passage structure90such that the C-shaped vane interrupter88is an “open” structure, the positioning of the flanges100,102above and below the magnetic sensor42provide a continuous shielding path that acts to deflect an external magnetic field around the magnetic sensor.

Beneficially, embodiments of the invention thus provide a contactless control switch constructed such that shielding from external magnetic fields is provided to the magnetic sensor(s) therein via a shielding vane interrupter. The shielding provided to the magnetic sensor(s) is provided via an existing component—a vane interrupter—to which an additional flange structure is added to provide improved magnetic shielding. While the shielding vane interrupter is not formed as an enclosure that surrounds the magnetic sensor(s) (i.e., it is an “open” shielding structure), the vane interrupter provides a continuous shielding path to deflect an external magnetic field around the magnetic sensor(s).

Therefore, according to one embodiment of the present invention, a switch includes a switch housing, a button moveably mounted to the housing, a circuit board mounted to the housing and including at least one magnet sensor and a magnet holder, including at least one magnet, movably mounted to the housing so as to move responsive to an actuation of the button by a user, such that the at least one magnet is selectively movable to positions distal to and proximate to the magnet sensor. The switch also includes a vane interrupter having a passage structure positioned proximate to each magnet sensor of the at least one magnet sensor such that a respective magnet of the at least one magnet is movable at least partially within a passage defined by the passage structure and a flange structure positioned adjacent each passage structure, the flange structure comprising a first flange and a second flange positioned on opposing ends of the passage structure, with the first flange positioned adjacent a portion of the magnet holder holding the magnet and with the second flange positioned adjacent a surface of the circuit board opposite a surface on which the at least one magnet sensor is positioned, such that the circuit board is positioned between the magnet holder and the second flange.

According to another embodiment of the present invention, a switch includes a switch housing, an operating member mounted to the switch housing and movable between a plurality of positions responsive to physical actuation thereof by an operator, one or more magnet sensors secured relative to the housing, and a magnet holder mounted to the housing to position one or more magnets included thereon adjacent the one or more magnet sensors, the magnet holder moving responsive to an actuation of the operating member by a user so as to provide for positioning of the one or more magnets. The switch also includes a vane interrupter configured to provide selective magnetic shielding about the one or more magnets and to the one or more magnet sensors, the vane interrupter comprising a C-shaped frame that includes a lengthwise member oriented generally parallel to a direction of movement of the one or more magnets to form a passage sized to accommodate positioning of a respective magnet of the one or magnets therein and a pair of flanges formed on or attached to opposing ends of the lengthwise member and oriented generally perpendicular thereto. A respective magnet sensor of the one or more magnet sensors and a respective magnet of the one or more magnets are positioned between the pair of flanges of the C-shaped frame, such that the pair of flanges provide shielding to the respective magnet sensor from external magnetic fields.

According to yet another embodiment of the present invention, a rocker switch includes a switch housing, a rocker button mounted to the switch housing and actuatable between a neutral position, a first position, and a second position, a magnet holder including therein a first magnet and a second magnet and being mounted to the housing so as to be rotatable relative thereto, a first Hall effect sensor and a second Hall effect sensor positioned adjacent the first magnet and the second magnet, respectively, and a vane interrupter comprising a C-shaped frame on each of opposing sides thereof such that a first C-shaped frame is positioned adjacent the first magnet sensor and the first magnet and a second C-shaped frame is positioned adjacent the second magnet sensor and the second magnet. Each of the C-shaped frames further includes a passage structure positioned proximate to a respective magnet sensor such that a respective magnet is movable at least partially within a passage defined by the passage structure and a flange structure positioned adjacent the passage structure and including a first flange and a second flange positioned on opposing ends of the passage structure, with the flange structure positioned to shield its respective Hall effect sensor from external magnetic fields.