Patent Grant
7649701
1. Field of the Invention
The present invention relates generally to a magnetically activated switch assembly, and more particularly, to a magnetically activated switch assembly in a helmet mount for turning night vision goggles on and off.
2. Description of Related Art
A magnetically activated switch assembly in a helmet mount for turning night vision goggles on and off is known in the art. Conventional magnetically activated switch assemblies utilize gravity in order to turn night vision goggles on and off. Such gravity controlled magnetically activated switch assemblies could cause integrated night vision goggles to improperly turn off when the night vision goggle apparatus is turned upside down. A non-gravity controlled magnetically activated switch assembly has been developed and is disclosed in U.S. Patent Publication No. 2006/0290451, which was integrated into a monorail mount disclosed in U.S. Patent Publication No. 2007/0012830, both references of which are herein incorporated by reference.
U.S. Patent Publication No. 2006/0290451 discloses a non-gravity controlled magnetically activated switch assembly for integration into a helmet mount for turning night vision goggles on and off. The disclosed magnetically activated switch assembly includes a magnet with conductive flux members leading to a reed switch. When the conductive flux members line up with the north and south poles of the magnet, the reed switch turns on, which provides a current path to power the night vision goggles.
The disclosed magnetically activated switch assembly also includes several air gaps between conductive flux members. The air gaps increase the reluctance of the magnetic flux path. With a higher reluctance magnetic flux path, the magnetically activated switch assembly is less effective because a more sensitive reed switch must be used. If the reed switch is too sensitive, the night vision goggles could be activated by the Earth's magnetic field or other environmental magnetic fields such as that caused by nearby power lines.
Accordingly, there is a need for an improved magnetically activated switch assembly for use in helmet mounted night vision goggles with a lower reluctance magnetic flux path. Such an improved magnetically activated switch assembly would ensure that the night vision goggles are activated only in particular predetermined positions and are therefore more reliable. Furthermore, there is a need for an improved magnetically activated switch assembly that allows the night vision goggles to remain on in predetermined positions and turns the night visions goggles off in other predetermined positions.
A magnetically activated switch assembly is provided having a magnet and a first magnetic circuit. The magnet has a first magnet end and a second magnet end. The first magnetic circuit includes a magnetically activated switch, a first set of flux conductors, and a second set of flux conductors. The first set of flux conductors have first flux conductor flanges adapted to conduct flux from the first magnet end and the second magnet end. The second set of flux conductors are slidingly positioned relative to the first set of flux conductors and are adapted to conduct flux from the first set of flux conductors to the magnetically activated switch. The first set of flux conductors are adapted to rotate clockwise or counter-clockwise and the first magnetic circuit is adapted to conduct flux to activate the magnetically activated switch only when the first flux conductor flanges are rotationally aligned with the first magnet end and the second magnet end.
In an exemplary embodiment of the present invention, the magnetically activated switch assembly is adapted to tilt between a lower tilt position and an upper tilt position. In addition, the magnet is adapted to remain radially adjacent the first flux conductor flanges as the magnetically activated switch assembly is tilted between the lower tilt position and the upper tilt position. Also, the magnet is adapted to move closer to the first flux conductor flanges as the magnetically activated switch assembly is rotated to a flip-down position. Furthermore, the magnet is adapted to move farther from the first flux conductor flanges as the magnetically activated switch assembly is rotated to a flip-up or stow position.
In an exemplary embodiment of the present invention, the lower tilt position is 5 degrees below a centerline tilt position and the upper tilt position is 13 degrees above the centerline tilt position.
In an exemplary embodiment of the present invention, the first flux conductor flanges are located in a center the first set of flux conductors such that a maximum reluctance of the first magnetic circuit is minimized as the second set of flux conductors are slidingly positioned between ends of the first set of flux conductors.
In an exemplary embodiment of the present invention, a shunt ring is positioned proximate the magnet such that as the magnetically activated switch assembly rotates to a flip-up or stow position, the magnet moves along an axis of the shunt ring to a position inside the shunt ring, and as the magnetically activated switch assembly rotates to a flip-down position, the magnet moves along the axis of the shunt ring to a position outside the shunt ring radially adjacent the first flux conductor flanges.
In an exemplary embodiment of the present invention, the shunt ring is a second magnetic circuit having a high magnetic permeability.
In an exemplary embodiment of the present invention, the magnetically activated circuit assembly further includes a magnet carrier housing the magnet and an actuator shaft attached to the magnet carrier. As the magnetically activated switch assembly rotates to a flip-up position, the actuator shaft and magnet carrier move along the axis of the shunt ring such that the magnet carrier is positioned inside the shunt ring, and as the magnetically activated switch assembly rotates to a flip-down position, the actuator shaft and magnet carrier move along the axis of the shunt ring such that the magnet carrier is positioned outside the shunt ring radially adjacent the first flux conductor flanges.
In an exemplary embodiment of the present invention, the magnet carrier is made out of a low magnetic permeability metal or plastic, such as aluminum, nylon or a polyimide thermoplastic resin, or any other low magnetic permeability material.
In an exemplary embodiment of the present invention, the magnetically activated switch assembly further includes a helmet block having a cam shaped channel and a coil spring coupled to the magnet carrier and to an end of the magnetically activated switch assembly. The actuator shaft has a flat edge at an end for fitting into the channel and the coil spring biases the magnet carrier toward the helmet block.
In an exemplary embodiment of the present invention, the second set of flux conductors include upper transfer conductors and lower transfer conductors. The upper transfer conductors contact or are in close proximity with the lower transfer conductors, and the lower transfer conductors are in close proximity to the magnetically activated switch. The first set of flux conductors include vertical shoes and monorail strip conductors. The first flux conductor flanges extend from a center of the vertical shoes. The vertical shoes are positioned on top of the monorail strip conductors. The monorail strip conductors are T-shaped or dovetail shaped. The upper transfer conductors are adapted to slide along bottom portions of the monorail strip conductors.
In an exemplary embodiment of the present invention, the first set of flux conductors and the second set of flux conductors are formed of Mu-metal, Permalloy, iron-nickel alloy, iron-cobalt alloy, ferritic iron-chrome alloy, iron, ferrite, silicon steel, soft steel, AISI 12L14 carbon steel, nickel, or any other material with a high magnetic permeability.
In an exemplary embodiment of the present invention, the magnetically activated switch assembly is integrated into a helmet mount for night vision goggles such that the magnetically activated switch assembly turns on the night vision goggles only when the night vision goggles are in a flip-down position and the first flux conductor flanges are rotationally aligned with poles of the magnet.
In an exemplary embodiment of the present invention, the magnetically activated switch is a reed switch.
A magnetically activated switch assembly is alternatively provided including a first magnet, a second magnet, and a magnetic circuit. The first magnet has a first magnet north end and a first magnet south end. The second magnet has a second magnet north end and a second magnet south end. The magnetic circuit includes a magnetically activated switch, a first set of flux conductors, and a second set of flux conductors. The first set of flux conductors are adapted to conduct flux from the first magnet north end and the second magnet south end to the second set of flux conductors. The second set of flux conductors are slidingly positioned relative to the first set of flux conductors and are adapted to conduct flux from the first set of flux conductors to the magnetically activated switch. The magnetic circuit is adapted to rotate clockwise or counter-clockwise and to activate the magnetically activated switch only when the first set of flux conductors are rotationally aligned with the first magnet north end and the second magnet south end.
In an exemplary embodiment of an alternative of the present invention, the magnetically activated switch assembly further includes a shunt shaft. The first magnet south end and the second magnet north end contact or are in close proximity to the shunt shaft.
In an exemplary embodiment of an alternative of the present invention, the shunt shaft has a high magnetic permeability.
In an exemplary embodiment of an alternative of the present invention, the magnetically activated switch is a reed switch.
In an exemplary embodiment of an alternative of the present invention, the first set of flux conductors and the second set of flux conductors are formed of Mu-metal, Permalloy, iron-nickel alloy, iron-cobalt alloy, ferritic iron-chrome alloy, iron, ferrite, silicon steel, soft steel, AISI 12L14 carbon steel, nickel, or any other material with a high magnetic permeability.
In an exemplary embodiment of an alternative of the present invention, the magnetic circuit is adapted to tilt between a lower tilt position and an upper tilt position, and the magnetic circuit is adapted to activate the magnetically activated switch only when the magnetic circuit is in a flip-down position and the first set of flux conductors are rotationally aligned with the first magnet north end and the second magnet south end.
In an exemplary embodiment of an alternative of the present invention, the magnetically activated switch assembly further includes a first magnet shoe connected to the first magnet north end, a second magnet shoe connected to the second magnet south end, a first vertical transfer conductor contacting or in close proximity with the first magnet shoe, and a second vertical transfer conductor contacting or in close proximity with the second magnet shoe. The first set of flux conductors are adapted to be in close proximity with the first vertical transfer conductor and the second vertical transfer conductor only when the first set of flux conductors are rotationally aligned with the first vertical transfer conductor and the second vertical transfer conductor, and the magnetic circuit is between the lower tilt position and the upper tilt position. The first magnet shoe and the second magnet shoe are configured to obtain the lower tilt position and the upper tilt position.
In an exemplary embodiment of an alternative of the present invention, the second set of flux conductors include upper transfer conductors and lower transfer conductors. The lower transfer conductors are in close proximity to the magnetically activated switch. The upper transfer conductors contact or are in close proximity to the lower transfer conductors. The first set of flux conductors include monorail strip conductors, vertical shoes, and rotary conductors. The monorail strip conductors contact or are in close proximity to the upper transfer conductors and are T-shaped or dovetail shaped. The upper transfer conductors are adapted to slide along bottom portions of the monorail strip conductors in the second direction. The vertical shoes contact or are in close proximity with a top portion of the monorail strip conductors. The rotary conductors contact or are in close proximity to the vertical shoes. The rotary conductors are in close proximity to the first vertical transfer conductor and the second vertical transfer conductor only when the rotary conductors are rotationally aligned with the first vertical transfer conductor and the second vertical transfer conductor and the magnetic circuit is in a flip-down position.
An additional embodiment is to add a shunt bar such that when the rotary conductors are in a flip-up position, the rotary conductors align with this shunt bar to further decrease the magnetic flux conducted to the magnetic switch.
In an exemplary embodiment of an alternative of the present invention, the magnetically activated switch assembly is integrated into a helmet mount for night vision goggles such that the magnetically activated switch assembly turns on the night vision goggles only when the night vision goggles are in a flip-down position and the rotary conductors are rotationally aligned with the first vertical transfer conductor and the second vertical transfer conductor.
A helmet mount assembly is provided having a magnetically activated switch assembly as disclosed above. The helmet mount assembly includes a helmet block having a cam shaped channel and an axis hole parallel to a first direction. In addition, the helmet mount assembly includes a chassis mounted to the helmet block by a shaft inserted through the axis hole. The chassis has a rotating member that rotates about an axis parallel to a second direction. The second direction is perpendicular to the first direction. Furthermore, the helmet mount assembly includes a monorail assembly connected to the chassis. The monorail assembly includes the magnetically activated switch assembly.
Alternatively, A helmet mount assembly is provided having a magnetically activated switch assembly as disclosed above. The helmet mount assembly includes a helmet block that has an axis hole parallel to a first direction and said helmet block contains magnets with flux conductors conducting the magnetic flux to flux conductors in a chassis mounted to the helmet block by a shaft inserted through the axis hole. The chassis has a rotating member that rotates about an axis parallel to a second direction. The second direction is perpendicular to the first direction. This rotating member contains additional flux conductors. Furthermore, the helmet mount assembly includes a monorail assembly connected to the chassis. The monorail assembly includes flux conductors to conduct the magnetic flux from the magnets in the helmet block to the magnetically activated switch assembly.
The magnet 101, magnet shoes 102, vertical shoes 103, monorail strip conductors 104, upper transfer conductors 105, and lower transfer conductors 106 form a magnetic circuit/flux path between the magnet 101 and the reed switch 107. According to Maxwell's equations, magnetic flux always forms a closed loop. However, the path of the closed loop depends on the reluctance of the materials surrounding the magnet 101. That is, a magnetic circuit/flux path of low reluctance materials may be used to direct magnetic flux in a particular path. The reluctance of a magnetic circuit is proportional to the length of the circuit and is inversely proportional to the magnetic permeability of the material used in the circuit and the cross-sectional area of the circuit.
Accordingly, according to exemplary embodiments of the present invention, the magnet 101 is centrally located along the monorail strip conductor 104 in order to minimize the length of the magnetic circuit/flux path. In addition, the magnet shoes 102, vertical shoes 103, monorail strip conductors 104, upper transfer conductors 105, and lower transfer conductors 106 may be formed of Mu-metal, Permalloy, iron-nickel alloy, iron-cobalt alloy, ferritic iron-chrome alloy, iron, ferrite, silicon steel, soft steel, AISI 12L14 carbon steel, nickel, or any other material with a high magnetic permeability for conducting magnetic flux of the magnet 101.
Mu-metal is nickel-iron alloy annealed in a hydrogen atmosphere for high magnetic permeability. Permalloy is a nickel-iron alloy with high magnetic permeability with a content typically of around 80% nickel and 20% iron. The high magnetic permeability metals for conducting magnetic flux of the magnet 101 should be magnetically “soft” metals such that a magnetic field induced in the metal quickly collapses when the magnet 101 is moved away from or shielded from the magnetic circuit.
Furthermore, according to exemplary embodiments of the present invention, the magnet shoes 102 allow for the minimization of the air gap between the vertical shoes 103 and the north and south poles of the magnet 101. When the magnetic circuit is formed of AISI 12L14 carbon steel, the air gap with the magnet shoes 102 may be around 0.020 inches. However, without the magnet shoes 102, the air gap may be around 0.040 inches. In order to keep the reluctance of the magnetic circuit/flux path to the reed switch low enough for effectiveness, the air gap should be less than 0.060 inches. However, larger air gaps can be used if a stronger magnet 101 is used or lower reluctance materials are used for the magnetic circuit/flux path.
As depicted in
The monorail assembly 117 further includes a carriage 120 connected to a monorail 121. The carriage 120 includes a fore/aft lever 122 biased by springs 123 and held to the carriage 120 by a pin 124 for allowing the monorail 121 to be locked in a particular position within the carriage 120. The carriage 120 also includes a shaft 125 and a release lever 126 for allowing a night vision goggle apparatus with a goggle dovetail assembly 127 to be connected to a bottom portion of the carriage 120. In addition, the carriage 120 includes a lock 128 and a biasing spring 129 for locking a night vision goggle apparatus to the bottom of the carriage 120. The shaft 125 slides through the lock 128, holding the lock 128 in place.
Furthermore, the carriage 120 includes lower and upper transfer conductors 106, 105. The lower transfer conductors 106 are in close proximity to the reed switch 107 of the goggle dovetail assembly 127. The lower transfer conductors 106 contact or are in close proximity to the upper transfer conductors 105. The upper transfer conductors 105 are adapted to slide along a bottom surface of the monorail strip conductors 104. The monorail strip conductors 104 are T-shaped or dovetail shaped and fit within a channel of the monorail 121. Vertical shoes 103 are positioned above a top, edge portion of the monorail strip conductors 104. The monorail 121 is coupled to springs 130. The springs 130 bias plungers 131 into holes 132″ of the bearing face 132. Monorail end cap 113 covers an end of the monorail 121, locked in position by pin 133.
The night vision goggles may be rotated clockwise or counter-clockwise about the axis hole 132′ of the bearing face 132, rotated up about shaft 118, or may be rotated both clockwise/counter-clockwise and up. As the night vision goggles are rotated clockwise or counter-clockwise, the vertical shoes 103 rotate around the magnet 101. The magnet 101 remains stationary because the flat edge 109′ of the actuator shaft 109 keeps the magnet 101 in place. As the vertical shoes 103 rotate around the magnet 101, the vertical shoes 103 move from an aligned position in which the protruding arms 103′ and the magnet shoes 102 are in alignment to an unaligned position in which the protruding arms 103′ and the magnet shoes 102 are out of alignment. Thus, as the protruding arms 103′ of the vertical shoes 103 are rotated from an aligned position, north/south polarization cannot be effectively delivered to the protruding arms 103′ and therefore cannot be effectively delivered to the reed switch 107. Thus, for example, when the first set of conductors is rotated 90° to the magnet, a null position is realized wherein essentially no flux is across the first set of magnetic conductors.
In an exemplary embodiment, when the protruding arms 103′ and the magnet shoes 102 are in alignment, the magnetic circuit delivers about 26 gauss (G) to the reed switch 107. However, when the protruding arms 103′ are rotated about 90 degrees, the magnetic circuit delivers less than 1 G to the reed switch 107. Thus, as the protruding arms 103′ are rotated out of alignment with the north and south poles of the magnet 101, the magnetic flux density at the reed switch 107 drops from about 26 G to less than 1 G, which causes the reed switch 107 to open.
As the night vision goggles are rotated up to a flip-up or stow position about shaft 118, the actuator shaft 109 is biased by the coil spring 112 toward the helmet block 115. Because the helmet block 115 includes a cam shaped channel 115′, as the night vision goggles are rotated up to a flip-up or stow position, the actuator shaft 109 is biased by the coil spring 112 to move along the axis of the shunt ring 110 such that the magnet carrier 108 and magnet 101 are positioned within the shunt ring 110.
While the magnet 101 is within the shunt ring 110, the reluctance of the magnetic circuit/flux path to the reed switch 107 is increased due to the increased air gap between the poles of the magnet 101 and the protruding arms 103′ of the vertical shoes 103. In addition, the reluctance of the magnetic circuit/flux path through the shunt rung 110 is reduced because the magnet shoes 102 are adjacent inner edges of the shunt ring 110. Thus, while the magnet 101 is within the shunt ring 110, the majority of the magnetic flux propagates through the shunt ring 110 rather than through the magnetic circuit leading to the reed switch 107. As a result, the reed switch 107 will open.
The helmet block 115 is also configured such that when the night vision goggles are put into a flip-up or stow position, the night vision goggles are turned off. Hence, the channel 115′ of the helmet block 115 will have a cam shape. That is, when monorail assembly 117 and the chassis 116 are flipped-up, the end 109″ of the actuator shaft 109 moves along the channel 115′ of the helmet block 115 such that the actuator shaft moves toward the helmet block 115, thus moving the magnet 101 out of alignment with the vertical shoes 103, which turns off the night vision goggles.
As depicted in
Furthermore, as depicted in
The first set of flux conductors 205 include transfer pins/rotary conductors 207, vertical shoes 208, and monorail strip conductors 209. The rotary conductors 207 transfer magnetic flux to the vertical shoes 208. The vertical shoes 208 have protruding members extending down a center section extending to the monorail strip conductors 209. The monorail strip conductors 209 contact or are in close proximity to the protruding members of the vertical shoes 208 and extend parallel to the rotary conductors 207. The monorail strip conductors 209 are T-shaped or dovetail shaped. The monorail strip conductors 209 fit into a channel of the monorail 271, allowing the second set of flux conductors 206 to slide along bottom portions of the monorail strip conductors 209.
The second set of flux conductors 206 include upper and lower transfer conductors 210, 211. The upper transfer conductor 210 is adapted to be able to slide along the bottom portions of the monorail strip conductors 209. The upper transfer conductors 210 contact or are in close proximity with the lower transfer conductors 211. The lower transfer conductors 211 are in close proximity with the reed switch 204.
A shunt bar 214 installed in hole 213 aligns with the rotary conductors 207 when the first set of flux conductors 205 and second set of flux conductors 206 are in a flip-up position. This causes a further decrease in the magnetic flux conducted to the magnetic switch 204.
Furthermore, the carriage 270 includes lower and upper transfer conductors 211, 210. The lower transfer conductors 211 are in close proximity to the reed switch 204 of the goggle dovetail assembly 277. The lower transfer conductors 211 contact or are in close proximity to the upper transfer conductors 210. The upper transfer conductors slide along a bottom surface of the monorail strip conductors 209. The monorail strip conductors 209 are T-shaped or dovetail shaped and fit within the channel of the monorail 271. Monorail conductors/vertical shoes 208 contact or are in close proximity to a top surface of the monorail strip conductors 209. Rotary conductors 207 contact or are in close proximity to the vertical shoes 208. Springs 280 fit over an edge portion of the rotary conductors 207. The springs 280 bias plungers 283 through holes 263′ into detents on the face of chassis 253. Monorail end cap 281 covers an end of the monorail 271, locked in position by pin 282.
Accordingly, when the transfer pins/rotary conductors 207 are rotationally aligned with the vertical transfer conductors 203, magnetic flux from the first and second magnets 201 may propagate through the magnet shoes 202, vertical transfer conductors 203, rotary conductors 207, vertical shoes 208, monorail strip conductors 209, upper transfer conductors 210, and lower transfer conductors 211.
Accordingly, during a flip-up condition when the vertical transfer conductors 203 are un-aligned with the magnet shoes 202, the magnetic circuit experiences increased reluctance between vertical transfer conductors 203 and the magnet shoes 202 resulting in a decrease in magnetic flux conducted to the magnetic switch 204.
Furthermore during a flip-up position, a further reduction in magnetic flux conducted to the reed switch 204 may be accomplished by the addition of a shunt bar 214. The shunt bar 214 shorts the magnetic flux in the vicinity of the vertical transfer conductors 203, thus reducing the flux conducted to the magnetic switch 204.
As discussed above, reluctance of a magnetic circuit is proportional to the length of the circuit and is inversely proportion to the magnetic permeability of the materials in the circuit. Accordingly, in order to reduce reluctance of the magnetic circuit/flux path the magnet shoes 202, vertical transfer conductors 203, rotary conductors 207, vertical shoes 208, monorail strip conductors 209, upper transfer conductors 210, and lower transfer conductors 211 may be formed of Mu-metal, Permalloy, iron-nickel alloy, iron-cobalt alloy, ferritic iron-chrome alloy, iron, ferrite, silicon steel, soft steel, AISI 12L14 carbon steel, nickel, or any other material with a high magnetic permeability for conducting magnetic flux of the magnets 201.
The total reluctance of the magnetic circuit of the magnetically activated switch assembly 200 depends on the position of the upper transfer conductors 210 along the monorail strip conductors 209. The reluctance of the magnetic circuit is minimized when the upper transfer conductors 210 are immediately below the contact point for the rotary conductors 207 and the vertical shoes 208. As the upper transfer conductors 210 slide away from the contact point in either direction, the reluctance will increase because the total length of the circuit is also increased. However, even when the upper transfer conductors 210 are positioned at ends of the monorail strip conductors 209 where reluctance of the magnetic circuit is at a maximum, the reluctance is low enough for the magnetic circuit to sufficiently conduct magnetic flux to the reed switch 204.
The magnetically activated switch assembly 200 additionally includes a shunt shaft 212 that contacts or is in close proximity with ends of the first and second magnets 201 opposite the magnet shoes 202. The shunt shaft 212 may be formed of a high magnetic permeability material. The shunt shaft 212 improves the performance of the magnetically activated switch assembly 200 by increasing the effective magnetic flux density delivered by the first and second magnets 201.
The magnetically activated switch assembly 200 is adapted to allow rotation around two different axes in order to turn the reed switch 204 on and off. The first axis is parallel to the first set of flux conductors 205 about axis 253″ of the rotary track 253′ (i.e., about axis 253″ parallel to the rotary conductors 207, vertical shoes 208, and monorail strip conductors 209). Rotation around the first axis 253″ rotates the transfer pins/rotary conductors 207 in and out of alignment with the vertical transfer conductors 203 When the transfer pins/rotary conductors 207 are rotated out of alignment with the vertical transfer conductors 203, the transfer pins/rotary conductors 207 make contact with only one of the vertical transfer conductors 203 (i.e., with the north or south pole, but not both).
The second axis is about the shunt shaft 212. Rotation around the second axis rotates the vertical transfer conductors 203 away from the magnet shoes 202, which thus increases the air gap between the vertical transfer conductors 203 and magnet shoes 202, increasing the total reluctance of the magnetic circuit. The magnet shoes 202 are formed with a curved upper portion such that the vertical transfer conductors 203 continue to be in close proximity with the magnet shoes 202 for a predetermined tilt range. That is, the magnet shoes 202 are configured to maintain close proximity to the vertical transfer conductors 203 while the chassis 258 is tilted by pivot lever 255. According to an exemplary embodiment of the present invention, the tilt range may be 5 degrees below a centerline position and 13 degrees above the centerline position.
When night vision goggles connected to the carriage 270 are put into a flip-up or stow position, the vertical transfer conductors 203 are moved sufficiently away from the magnet shoes 202 such that magnetic flux is broken between the magnet shoes 202 and the vertical transfer conductors 203, which turns the night vision goggles off. If an improved ratio of on/off magnetic flux is desired, then the shunt bar 214 may be added. This will short the magnetic flux during a flip-up operation.
Because the magnetically activated switch assembly 200 includes magnets located farther from the reed switch 204 than the magnetically activated switch assembly 100, the reluctance of the magnetic circuit/flux path of the magnetically activated switch assembly 200 is higher than the magnetic circuit/flux path of the magnetically activated switch assembly 100. Accordingly, in the magnetically activated switch assembly 200, air gaps should be minimized, especially air gaps located away from the magnet or magnets. Therefore, according to an exemplary embodiment of the present invention, when using AISI 12L14 carbon steel for magnetic circuit components, air gaps in the magnetically activated switch assembly 200 should be less than 0.005 inches at any one point. Of course, air gaps may be larger than 0.005 inches when a more powerful magnet or magnets are used or the first and second sets of flux conductors are formed of a higher magnetic permeability material.
As discussed above, the reluctance of a magnetic circuit is proportional to the length of the circuit and is inversely proportional to the magnetic permeability of the material used in the circuit and the cross-sectional area of the circuit. As such, various modifications to the exemplary embodiments of the magnetic circuits may be made in order to decrease the length of the circuit, increase the magnetic permeability of the circuit, or increase the cross-sectional area of the circuit. Furthermore, because weight of the magnetic circuit is also an important consideration, various modifications to the exemplary embodiments of the magnetic circuits may be made in order to both reduce the weight and reduce the reluctance of the magnetic circuit. For example, a heavier material of a higher magnetic permeability may be used for the magnetic circuit, while decreasing a cross-sectional area of the circuit, such that a total weight of the magnetic circuit is reduced while still achieving an overall lower reluctance of the magnetic circuit.
While the invention has been described in terms of exemplary embodiments, it is to be understood that the words which have been used are words of description and not of limitation. As is understood by persons of ordinary skill in the art, a variety of modifications can be made without departing from the scope of the invention defined by the following claims, which should be given their fullest, fair scope.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5331684 | Baril et al. | Jul 1994 | A |
| 5339464 | Dor | Aug 1994 | A |
| 5408086 | Morris et al. | Apr 1995 | A |
| 5506730 | Morley et al. | Apr 1996 | A |
| 5857599 | Palmer | Jan 1999 | A |
| 6472776 | Soto et al. | Oct 2002 | B1 |
| 6862748 | Prendergast | Mar 2005 | B2 |
| 7504918 | Prendergast et al. | Mar 2009 | B2 |
| 20060290451 | Prendergast et al. | Dec 2006 | A1 |
| 20070012830 | Prendergast | Jan 2007 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20080272868 A1 | Nov 2008 | US |
