WO2010011942A1

WO2010011942A1 - A switch and switch actuator

Info

Publication number: WO2010011942A1
Application number: PCT/US2009/051714
Authority: WO
Inventors: Raleigh L. Cox; Christopher E. Cox
Original assignee: Cox Raleigh L; Cox Christopher E
Priority date: 2008-07-25
Filing date: 2009-07-24
Publication date: 2010-01-28

Abstract

A switch and a switch actuator, where the switch has a changeable status, the switch connected to electrical conductors to communicate the switch status. The switch actuator includes a chamber containing a movable member and a frictional means to resist the movement of the moveable member, and the moveable interacts with said switch when at predetermined positions in the chamber to modify the status of the switch.

Description

A Switch and Switch Actuator Chris Cox and Raleigh Cox

Priority claim: This application claims the priority benefit U.S. provisional application number 61/083761, filed July 25, 2008 and entitled "switch actualor." Field of Invention

The invention relates to electrical switches and actuators and more particularly, to a switch actuator having a dampening or friction aid resisting the actuator action, more particularly, to a gravity activated float switch. Background of the Invention

Many working environments use switches that automatically operate in a given condition to activate (or deactivate) a device. These switches have contacts that are moved from one position (e.g. activated or closed, such as make the switch) to a second position (deactivated, such as break or open the switch or switch contacts) by a movable mechanism, the actuator, where electrical current passes through the switch when the switch contacts are made or closed. Many such switches use a gravity activated ball or plug as an activator to operate a switch. For instance, a typical float switch may use a Tollable ball in a shaped chamber to activate the contact in a switch, such as shown in figure 1. As the float rises or falls, the float tilts and a ball 101 or electrically conductive liquid (such as mercury), moves and makes contact directly or indirectly (through a linkage, such as arm 100) to an electrical switch or contacts of some sort, causing the switch to activate or deactivate (i.e., complete an electric circuit or brake a completed electric circuit). In figure 1, as the ball 101 rolls in response to gravity, its weight will cause pivot arm 100 to pivot. As arm 100 pivots, its action can move a movable contact to make or break the switch, or the movable contact member can be within the lever arm 100 itself. If the circuit is completed, the switch contacts are connected (switch closed), providing for electrical current to pass from a control panel through wires to the float and through the completed switch contacts. A common problem with these types of switches are actuator wear or switch breakage and switch flutter. In switch breakage, the gravity activated device (such as a Tollable ball) may move too quickly due to rapid activation, and the resulting contact of the ball, such as on the switch contact, may impart too much inertial load and damage the switch and/or switch contacts. Switch flutter results when the gravity activated device is poised between the "switch activated" position and "switch deactivated" position, and may float between the two positions, resulting in switch flutter (rapid activation/deactivation). To prevent switch flutter, some switches incorporate a time delay circuit to prevent this type switch flutter - e.g., a recently "opened" contact activates the timer, and no change in switch status is "recognized" until the timer completes its cycle. It would be desirable to have a switch with a switch activator that is less prone to damage and to switch flutter.

Summary of the Invention

The invention includes a mechanical switch that uses a movable gravity assisted actuator device.

The movement of the actuator device is restrained by a dampening means that retards or delays movement of the actuator.

Brief Description of the Drawings

Figure 1 is a depiction of a prior art float switch activator.

Figure 2 is an exploded cross sectional view of one embodiment of a float switch using a switch activator that interacts magnetically with a switch Figure 3 is an exploded cross section through one embodiment of a float switch using a switch activator that mechanically interacts with a switch.

Figure 4A and 4B is a cartoon of a switch activator where the movable member extends through the chamber to interact with a switch.

Figure 5 A and 5B is a cross section through one embodiment of a float switch showing a first status (switch not made 5A) and switch contacts about to be made (5B). Figure 6A-6E is a depiction of magnets used as a friction increasing aid, showing relative motion of a magnetic interactive slug in response to float motion.

Figure 7 is a depiction of a shaped chamber used as a damping means.

Figure 8 is a cross section through one float embodiment depicting the flexible paddle and cable connections.

Figure 9 A, B, and C are partially exploded cross sections through float embodiments depicting various switch configurations 9A is a lever operated switch, 9B is a reed switch, and 9C is a reed switch embodiment.

Figure 10 is a depiction of a pumping station. Figure 1 IA is a representation of a switch magnetically coupled to a moveable member throughout the range of motion of moveable member, form position 1 IA to position 1 IB.

Detailed Description of the Invention

Shown in figure 2 is an embodiment of an actuator for use in a switch (or a relay, used interchangeably with a switch), where electric current passes through the switch when contacts are made. Shown is a gravity assisted actuator 1, containing a movable member 3, such as a Tollable ball, or a slidable plug 12 (e.g. bar or cylinder). The movable member 3 travels in the interior of chamber 2 (such as slidable, Tollable, etc). As shown, the chamber 2 is a closed glass or plastic ampoule or vial. The movable member (such as a ball or plug) may be a permanent ferro-magnet, or a magnetically interactive material, such as steel or a steel or iron impregnated plug (for a magnetically interactive switch/switch activator), or may be magnetically inactive, for a mechanical interactive embodiment, later described. Within the chamber 2 is positioned a means for dampening motion of the moveable member 3, such as a friction increasing aid or delaying means, such as a viscous fluid 30, later described.

Switches have a changeable status (e.g. contacts made or broken; current allowed or interrupted, etc), and some switches will have more than two states or statuses (e.g. three way switches, for example). Operation of a switch entails changing the status of the switch from one status (e.g. contacts made) to another status (contacts broken). In figure 2, the switch shown is a lever actuated switch 10 positioned within the interior of a float housing 5 (shown in cross section, in a partially exploded view). The movement of the switch lever 11 makes or brakes switch contact A and thereby changes the status of the switch. The switch 10 is connected to cable 200, which contains electrically conductive wires 90 to communicate the status of the switch to a remote location (such as a pumping station electrical box enclosure). Movement of the lever 11 will be accomplished by interaction with the moveable member 3 of switch actuator 1.

As shown in figure 2, chamber 2 containing the movable member 3 (depicted as a cylinder 12) and a dampening means, (depicted as a viscous fluid. 30) is located near the distal end of the lever 11. As the chamber 2 tilts with motion of the float body 5, the cylinder 12 moves from a position 21 A near the lever 11 (figure 5A), to a position 2 IB remote from the lever 11 (figure 5B). If the lever 11 contains a permanent magnet and cylinder 12 is magnetically interactive, then as the cylinder 12 approaches the lever 11, the lever 11 will be drawn by magnetic forces toward the cylinder 12, thus operating the switch by altering the switch contact points from one state to another (not shown in figure 2).

The location of the magnet is relative, as the switch activation will also occur if the cylinder 12 contains the permanent magnet and the lever 11 is a magnetically active material. Further, the switch 10 may be configured so that switch 11 is normally closed or normally open, providing flexibility in design. Additionally, while the chamber 2 is shown "above' the lever 11 of switch 10, chamber 2 may located under the lever 11 of switch 10, or alongside the switch (see figure 11). An alternative lever actuated magnetic interactive embodiment can have permanent magnets positioned on both the lever 1 1 and the cylinder 12. In this instance, the facing poles between the lever 11 magnet and cylinder 12 magnet may be alike (creating an repulsive force, as depicted in figure 5A) or opposed (creating an attractive force). As used herein, the switch and moveable member are coupled by a weak magnetic interaction, meaning that for a given magnet and slug or moveable structure (or vice versa, where the magnet moves), the magnetic force exerted between the slug or device and magnet is insufficient to overcome the gravitational force acting on the slug, thereby allowing the moveable member 3 to be released at some point in the range of motion (for instance, as the position of the slug approaches vertical, figure 6E. For instance, with a lever operated switch, the magnetic force of the interaction generally must be sufficient to overcome the spring force of the lever switch 10, but not so great that the lever 11 and cylinder 12 are "stuck" together by magnetic interaction throughout the range of motion of the float, preventing motion of the moveable member. For instance, the moveable member and switch may "decouple" at a given orientation - having an orientation of the chamber where the gravitational forces overcome the magnetic forces and the moveable member releases and moves in chamber (the release point can be chosen by modifying the strength of the magnet, the weight of the slug, or the magnetizability of the slug's material). Alternatively, the moveable member 3 and switch may be "coupled" throughout the range of motion of moveable member 3, provided the moveable member moves in response to a change in orientation of chamber 2. For instance, if chamber 2 is located along the side of lever 11 (aligned with the long axis of the float) and slug 12 and lever 11 are magnetically attractively coupled, as slug 12 moves, lever 11 will follow, thus changing the state of switch 10. See figure HA and HB. Finally, the switch and moveable member may be decoupled through the range of motion of moveable member 3 if magnetic repulsion forces are used (e.g. magnets on both the slug 12 and lever 11) In either coupled or decoupled motion, gravitational forces must be sufficient to allow movement of the movable member despite the magnetic interaction, at least at some point of orientation of the chamber 2.

The switch components (housing, chamber, switch components) can be used with other types of switches (rocker type switches, push button type switches, toggle type switches, reed type switches, electronic hall effect switches, etc.) using weak magnetic interaction. For instance, a magnetic slug or cylinder can be used to repel (or attract) a magnetic push button, toggle or rocker, thereby altering the state of the switch (for instance, contacts made). As the moveable member moves away from the switch, the switch preferably is of the type that resets to a prior when the external force applied by the actuator of the invention is removed (for instance, the return to a prior state can be accomplished by using a biasing member to reset the switch contacts once the actuator applied force is removed). This biasing of the switch is not required. For instance, the chamber 2 may be aligned (run parallel ) to a rocker or toggle type switch, and as the moveable member 3 moves from one side of the chamber to the other, the rocker or toggle would follow by magnetic interaction (attraction or repulsion, as the case may be). In this action, the chamber 2 should be somewhat aligned with the expected motion of the float. For instance, in a float embodiment, the chamber is preferably aligned with the long axis of the float 5 (top to bottom), but variations of this preferred alignment are allowable, provided the moveable member 3 moves as the float alters its position in response to fluid levels. Alternatively, a shaped chamber may be employed to provide intermediary switch positions (not just the two ends of the chamber), for instance, in a multiple position proximity switch.. Finally, a reed switch may be used in conjunction with a magnetic moveable member 3 (figure 9B and 9C) where a switch itself has contacts that open or close in response to a magnetic force.

Interaction of the switch and switch actuator may be by magnetic interaction as discussed, or by only mechanical interaction in many different switch configurations (lever, rocker arm, push button, toggle). For instance, a push button embodiment is depicted in figure 3. Shown is push button switch 35, having a push button 32. The push button 32 is located within the closed chamber 2. Indeed, as shown, the switch 35 itself is used as one of the endcaps 40 of the closed chamber 2. As shown, the actuator's movable member is a ball 33. When the ball 33 makes physical contact with the button 32, the button 32 is depressed, changing the state of the switch 35. The switch 35 remains in the new state as long as the button is depressed by the action of the ball 3A. Upon sufficient tilt of the chamber 2, the ball 3A will come off the push button 32, and the push button 32 is restored to its previous position (such as by a spring biasing means), and the switch 35 will revert to its previous state. Instead of a button 32 located within the chamber, the button 32 could be adjacent to the chamber and the chamber end wall could be formed with a flexible membrane (not shown). The flexible membrane allows the ball (or cylinder or other movable member) to extend beyond the terminating sidewall of the chamber (via the flexing of the membrane) in order to make contact with the push button or other mechanical actuator.

Other mechanically interactive embodiments are within the scope of the invention. For instance, shown in figure 4 is a cylinder 12 that include a rod 50 that protrudes through the end wall of the chamber 2, where the rod 50 is slidable through the end wall but preferably is sealed in the end wall. As the cylinder moves toward the pushbutton, the rod portion 50 will make contact with the push button on the pushbutton switch 10. In this embodiment, the sealing end of the chamber may provide sufficient resistance to motion of the rod 50 that other dampening means are not necessary, next described.

It is preferred that the invention include a means to dampen or delay the motion of the movable actuator, such as a friction increasing aid 3 within the interior of chamber 2, to prevent switch flutter. As shown in figure 2, the friction increasing aid is a relatively high viscosity fluid 6 that creates a drag and a resultant hesitation and resistance to the motion of the movable member 3, damping the motion of the moveable member 3. The fluid also cushions the movable member when it strikes the endwall 25 of the chamber. The fluid thus helps prevent damage and wear on the remote actuator, and prevents the movable member 3 from rapidly sliding between positions, thus reducing switch flutter.

A preferred fluid is inert, remains in a fluid state between large temperature ranges (such as between -25 to 70 deg C) and whose viscosity does not appreciably change over an extended temperature range. One such fluid is mineral oil, another is polydimethylsiloxane, available from Clearco Products of Bensalem, PA (350 grade being a preferred type). A viscous fluid is preferred as it adds no additional wear surfaces, and indeed, reduces wear, but other techniques can be used, such as roughening the internal sides of the chamber, adding ridges to the interior of the chamber (such as an annular ridge) to help slow the progress of the movable member and resist a sudden movement of the member, adding compressible fins on the plug, etc. For instance, shown in figure 7 is a chamber 2 having an internal annular ridge 76 that will dampen the motion of a reliable ball actuator 75. The ridge 76 is formed by pinching the chamber's walls inwardly, forming an "hourglass" shaped chamber 2. The ridge 76 will hold the ball 75 until the chamber 2 is sufficiently tilted. The height of the ridge 76 can be formed as desired to provide the desired degree of dampened or delayed motion of the Tollable ball 75 in the chamber 2. The ball should be passable over the annular ridge 76. The hourglass shape annular ridge may be used with or without a fluid disposed in the interior of the chamber 2.

Magnets may also be employed to dampen or delay the motion of the moveable member. For instance, if the actuator weakly magnetically attractively interacts with the switch, the magnetic forces alone may provide the needed damping force to prevent switch flutter. Additional magnets may be used to provide the desired damping or delay of the movable member even if actuator/switch are not magnetically interactive. As a non-limiting example, shown in figure 6A- 6E is a cartoon depicting the movement of a slidable magnetically interactive cylinder or slug (here stainless steel cylinder 80 (sometimes denoted a s 300 series stainless steel having approximately 18% chromium and 8% nickel)) in a chamber 2 or vial and a "horseshoe" magnet positioned in the interior of the float, where the two ends of the horseshoe terminate near the sides or ends of the ampoule. The horseshoe magnet is shown for purposes of illustration and is not preferred (for instance multiple discrete magnets could be employed). As the float moves from position A through position D, rotating "upwardly," the slug "sticks" to the ampoule's walls near the magnet, say near the N pole of the magnet. Before or at position E, the gravitational force overcomes the magnetic force, and the slug decouples and slides downwardly. As the float rotates from position E downwardly (not shown), the slug will again stick to the ampoule's walls near the S pole of the horseshoe magnet. The slug 12 will release when the float returns to a position before or at position A. In use, one or more magnets may be employed, and the location of the magnets can vary. For instance, a single donut style magnet may be positioned around the middle of the chamber; a bar magnet may be positioned near the middle of the chamber; or the movable slug may be the magnet, with weakly magnetic material positioned at each end of the ampoule or chamber.

As seen the switch activator contains a frictional increasing aid, a dampening aid or a delaying aid which resist the motion of the switch movable member - as such are considered a means to resist motion of the movable switch activator member.

One of the preferred embodiments of the switch and switch actuator is for use in a float switch embodiment. One possible float housing design for use with the switch and switch activators is depicted in PCTΛJS07/70122, hereby incorporated by reference in its entirety. Disclosed in this PCT application is an optical switch where the switch is light activated - that is, the status of the switch is changed by interrupting or transmitting a light beam, without using electrical conductors in the float. However, the present invention is directed to switches that are attached directly to electrical conductors at the switch body (such as copper, aluminum, as opposed to connected to non-electrically conductive light guides), such as having the conductors attached to the contact points on the switch.

In a float switch embodiment, the float housing 5 is floatable, and the cable 200 is intended to "tether" the housing 5 to a fixed point in the operating environment (e,g, the cable will be fixed to a location at the operations site away from the housing, see figure 10). The tether action allows the float to rise and fall with the fluid media through a range of elevations. When the float rises or falls a sufficient amount, the status of the switch will change (for instance, from contacts made to contacts broken). For instance, figure 3A shows a float in a horizontal orientation, and figure 3B, shows a float rising from the horizontal orientation in response to a rising fluid level.

As shown in figure 8, the cable 200 is inserted into the interior of the float 5 through on opening 42 in the bottom of the float housing 5. The lowermost portion of the housing interior is isolated from the uppermost portion of the housing interior by an interior shelf 65. The cable 200 is inserted through the shelf 65 via a channel in a nozzle 41 in the shelf 65. The top exterior of the nozzle 41A and bottom exterior 41B of the nozzle 41 are preferably lined with a heat shrink tubing 70, such as polyolefϊn heat shrink tubing containing thermoplastic adhesive. The heat shrink tubing 70 will seal against the nozzle 41 and cable 200, preventing migration of external fluids into the interior of the float through the hollow nozzel 41. Clamps may be used around the heat shrink and nozzles/cable or heatshrink/cable providing a redundant seal. Preferably, the heat shrink tubing 70 at the top exterior 41A of the nozzle extends beyond the outer sheath 81 of the cable, allowing the tubing and adhesive to seal against the cable's internal wires 90, preventing fluids from migrating into the interior of the float through the interior of the cable 200, as may occur if the outer sheath of the cable 200 is compromised anywhere within the fluid environment. Additional sealant, such as epoxy may be added at the top heat shrink to ensure a seal around wires 90. Instead of heat shrink (or in addition to the heat shrink), a compression or mechanical seal (such as a plug) or potting within the bottom cavity containing the bottom nozzle 4 IB (such as a polyurethane adhesive, Loctite U-091V, available from Henkel Loctite Corp, (a particular potting preferably is chosen to be inert in the fluid environment)) may be used to seal the cable in the float and additionally act as a strain relief. This cabling arrangement within the float and sealing methods are useful in both electrical cables and fiber optic cables in floats. A solid cable (such as PVC, polyethylene) with imbedded wires 90 could be used to avoid this problem, and is also useful in both electrical and fiber optic cables, particularly in wet applications or float application. Additionally, the bottom of the float may have an end cap 300 to limit the flexing of the cable interior to the float. As shown in figure 2, the preferred float body or housing 5 is a "light bulb shaped" two piece structure, with an interior cavity or chamber 6A. The two pieces (top and bottom portions) are preferably sealingly joined in a functional float. Positioned in the interior of the cavity 6A is a flexible member, such as a flat paddle shaped member 60, constructed of semi flexible plastic (self- supporting, but able to elastically bend or flex about 5-45 degrees about the joint without fracture). For instance a substantially planar paddle (about 3-4 inches in length), constructed of polypropylene with a thickness of about 1/16 - 1/8 inch thick, has been found suitably flexible for the embodiment shown in figure 7. Mounted on the paddle 60 are the switch components - the switch 10 (such as a reed switch, lever switch) and switch actuator 1 (e.g., chamber and moveable member, such as the actuating magnets). The paddle 60 is inserted in the bottom ¹A of the float housing IA and fixed into position with respect to the housing. The bottom end of the paddle 60 may be fixed into the interior of the float, such as by potting the end of the paddle into the housing, screw mounting the paddle into the interior (see figure 7), snapping the bottom portion of the paddle into a formed recess in the interior of the housing, or other means to fix the paddle within the interior of the housing.

Preferably, only a portion of the paddle 60 (e.g. the bottom portion or bottom edge) is fixed to the housing, allowing the remaining portion of the paddle to flex about the mount location. This freedom of motion for the paddle protects the switch and actuator components (such as the chamber ampoule or vial) positioned on the paddle or flexible member against shock loads. For instance, pumping station operators have been known to "clean" floats by swinging the float by the cable tether and slamming the float into a wall to remove debris form the surface of the float. The flexible mount member 60 mounted to allow the member to flex is considered a means for resisting shock loads, and as such, could be used in any type of float switch.

For a float embodiment, it is preferred that the body of housing 5 of the float be two colors, with the top 62 or a portion of the top of the float housing 5 (opposite the cable) being one color (such as a light color) and the bottom of the float 63 another color (such as a dark color). A "two toned" float allows an operator to tell if the float is facing up or down from visual inspection. A pattern may also be used on the top portion 62, such as a target "bullseye" pattern of alternating colors. Further, a top portion 62 of the float may have light activated luminescent materials (such as phosphorescent materials, or UV responsive materials) or light reflective materials (e.g. foil like) a embedded in the float body or coating portions of the float body to assist in identifying the float

(in a multi-float embodiment) and/or float orientation. Colors or patterns are considered as indicia.

In many applications, more that one float may be required. For instance, in a typical waste water treatment pumping station, four floats are generally used (low level switch, high level switch, pump 1 switch, pump 2 switch). In multi-float applications, it is preferred that each float cable carry an indicia (such as, for instance, a designated color or marking, such as red, black, blue, green cables or color banding) to allow the operator working at the remote cable termination location (e.g. a electrical panel enclosure) to readily identify float function (e.g. high level, low level, pump 1, pump 2) by cable indicia. The invention as described is particularly suitable where the moveable member moves in response to gravitational forces acting on the member in response changes in the spatial orientation of the chamber 2. Although the above description is in terms of selected embodiments, the present invention may include many modifications and variations of the present figures. And although the above description may state or imply advantages to certain embodiments, none of those advantages are necessarily critical to any particular embodiment and other embodiments not having such advantages are intended to fall within the scope of the present invention. All obvious modifications and variations of the embodiments described above are also intended to come within the scope of the following claims.

Claims

ClaimsWe claim:

1. A switch and a switch actuator, said switch having a changeable status, said switch having electrical conductors attached to said switch to communicate said status, said switch actuator comprising a closed chamber containing a movable member and a means to resist motion of the movable member disposed in said chamber, said movable member interacting with said switch when at predetermined positions in said chamber, thereby modifying the status of said switch.

2. A switch and a switch actuator, said switch having a changeable status, said switch having electrical conductors attached to said switch to communicate said status, said switch actuator comprising a chamber containing a movable member and a means to resist motion of the movable member disposed in said chamber, said movable member interacting with said switch when at predetermined positions in said chamber, thereby modifying the status of said switch, wherein said moveable member moves within said chamber in response to gravity.

3. The switch and switch actuator of claim 2, wherein said moveable member magnetically interacts with said switch.

4. The switch and switch actuator of claim 2 wherein said moveable member mechanically interacts with said switch.

5. The switch and switch actuator of claim 2 wherein said non-optic switch is selected from the group consisting of a rocker switch, a reed switch, a lever switch, a pushbutton switch, or a toggle switch.

6. The switch and switch actuator of claim 2 wherein said switch and said switch activator are contained in a floatable housing, said switch electrically communicating its status through a cable attached to said float.

7. The switch and switch actuator of claim 1 wherein said means to resist motion of the movable member is a liquid in said chamber.

8. The switch and switch actuator of claim 1 wherein said means to resist motion of the movable member is a ridge contained in said chamber.

9. The switch and switch actuator of claim 7 wherein said chamber is hourglass shaped.

10. A float switch comprising a floatable housing having an interior, and a switch and a switch activator contained in said housing interior, where said switch activator comprises a chamber containing a movable member and a friction increasing aid opposing the movement of the movable member, said movable member interacting with said switch when at predetermined positions in said chamber to operate said switch, said float switch further having a cable having electrical conductors therein, said cable having distal and proximal ends, said proximal end of said cable connected to said housing, said electrical conductors connected to said switch.

11. The float switch of claim 10 wherein said switch and switch actuator are mounted on a means for resisting shock loads.

12. The float switch of claim 10 wherein said moveable member magnetically interacts with said switch.

13. The float switch of claim 12 wherein said moveable member is a magnet.

14. The switch and switch actuator of claim 10 wherein said moveable member mechanically interacts with said switch.

15. The float switch of claim 10 wherein said switch is selected from the group consisting of a rocker switch, a reed switch, a lever switch, a pushbutton switch, or a toggle switch.

16. The float switch of claim 10 wherein said friction increasing aid is a liquid in said chamber.

17. A float switch comprising a floatable housing having an interior, and a switch and a switch activator contained in said housing interior, said switch having a changeable status, said float switch further having a cable having distal and proximal ends, said proximal end of said cable connected to said housing, said cable having electrical conductors connected to said switch for communicating said switch status, said floatable housing having a top and bottom exterior portion, said top exterior portion having a visibly detectable marking thereon whereby an operator may determine floatable housing orientation by viewing said floatable housing.

18. The float switch of claim 17 wherein said means to resist motion of the movable member is a ridge contained in said chamber.

19. The float switch of claim 17 wherein said chamber is hourglass shaped.