Patent Application
20090261927
The present invention relates to relays. More specifically, the present invention relates to coupled electromechanical relays and to methods of operating and formulating electromechanical relays.
Relays are electromechanical switches operated by a flow of electricity in one circuit and controlling the flow of electricity in another circuit. A typical relay includes an electromagnet with a soft iron bar, called an armature, held close to it. A movable contact is connected to the armature in such a way that the contact is held in its normal position by a spring. When the electromagnet is energized, it exerts a force on the armature that overcomes the pull of the spring and moves the contact so as to either complete or break a circuit. When the electromagnet is de-energized, the contact returns to its original position.
Latching relays are the types of relays which can maintain closed and open contact positions without energizing an electromagnet. Short current pulses are used to temporally energize the electromagnet and switch the relay from one contact position to the other. An important advantage of latching relays is that they do not consume power (actually they do not need a power supply) in the quiescent state.
Conventional electromechanical relays have traditionally been fabricated one at a time, by either manual or automated processes. The individual relays produced by such an “assembly-line” type process generally have relatively complicated structures and exhibit high unit-to-unit variability and high unit cost. Conventional electromechanical relays are also relatively large when compared to other electronic components. Size becomes an increasing concern as the packaging density of electronic devices continues to increase.
Two forms of conventional latching relays are described in the Engineers' Relay Handbook (Page 3-24, Ref. [1]). A permanent magnet supplies flux to either of two permeable paths that can be completed by an armature. To transfer the armature and its associated contacts from one position to the other requires energizing current through the electromagnetic coil using the correct polarity. One drawback of these traditional latching relay designs is that they require the coil to generate a relatively large reversing magnetic field in order to transfer the armature from one position to the other. This requirement mandates a large number of wire windings for the coil, making the coil size large and impossible or very difficult to fabricate other than using conventional winding methods.
U.S. Pat. No. 5,818,316 issued to Shen et al. described a switch having two magnetizable conductors in which the first conductor is permanently magnetized and the second conductor is switchable in response to a magnetic field applied thereto.
U.S. Pat. No. 6,469,602 B2 issued to Ruan et al. described a relay operated by providing a cantilever sensitive to magnetic fields such that the cantilever exhibits a first state corresponding to the open state of the relay and a second state corresponding to the closed state of the relay.
U.S. Pat. No. 6,124,650 issued to Bishop et al. disclosed a relay employing square-loop latchable magnetic material having a magnetization direction capable of being changed in response to exposure to an external magnetic field. The magnetic field is created by a conductor assembly. The attractive or repulsive force between the magnetic poles keeps the switch in the closed or open state.
Each of the aforementioned relays, though providing a unique approach to make latching electromechanical relays, has drawbacks and limitations. Some of them may require large current for switching, and some may require precise relative placement of individual components. These drawbacks and limitations can make manufacturing difficult and costly, and hinder their value in practical applications.
Accordingly, it would be highly desirable to provide an easily switchable electromechanical relay which is also simple and easy to manufacture and use.
It is a purpose of the present invention to provide a new and improved electromechanical relay which can be easily configured as latching or non-latching types.
It is another purpose of the present invention to provide a new and improved multi-pole multi-throw electromechanical relay.
The above problems and others are at least partially solved and the above purposes and others are realized in a relay comprising a movable first magnet and a nearby third electromagnet (e.g., a coil or solenoid). The movable first magnet is permanently magnetized, including but not limited to being magnetized primarily along its long (horizontal) axis, and has at least a first end. The third electromagnet, when energized, produces a third magnetic field which is primarily perpendicular to the magnetization direction of the first movable magnet and exerts a magnetic torque on the first magnet to force the first magnet to rotate and closes an electrical conduction path at the first end. Changing the direction of the electrical current in the third electromagnet changes the direction of the third magnetic field and thus the direction of the magnetic torque on the first magnet, and causes the first magnet to rotate in an opposite direction and opens the electrical conduction path at the first end. Multiple magnets can be stacked together to form multi-pole-multi-throw relays. Latching and non-latching types of relays can be formed by appropriately using soft and permanent magnets as various components.
The above and other features and advantages of the present invention are hereinafter described in the following detailed description of illustrative embodiments to be read in conjunction with the accompanying figures, wherein like reference numerals are used to identify the same or similar parts in the similar views, and:
It should be appreciated that the particular implementations shown and described herein are examples of the invention and are not intended to otherwise limit the scope of the present invention in any way. Indeed, for the sake of brevity, conventional electronics, manufacturing, and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail herein. Furthermore, for purposes of brevity, the invention is frequently described herein as pertaining to an electromagnetic relay for use in electrical or electronic systems. It should be appreciated that many other manufacturing techniques could be used to create the relays described herein, and that the techniques described herein could be used in mechanical relays, optical switches, fluidic control systems, or any other switching devices. Further, the techniques would be suitable for application in electrical systems, optical systems, consumer electronics, industrial electronics, wireless systems, space applications, fluidic control systems, medical systems, or any other application. Moreover, it should be understood that the spatial descriptions made herein are for purposes of illustration only, and that practical latching relays may be spatially arranged in any orientation or manner. Arrays of these relays can also be formed by connecting them in appropriate ways and with appropriate devices.
Movable cantilever 10 comprises a permanent (hard) magnetic layer 11 (first magnet), flexure spring and support 12, a pivot 15, and electrical contacts 13 and 14. Magnetic layer 11 is permanently magnetized (with a magnetic moment m) primarily along its long axis (e.g., predominantly along the positive x-axis when it lies leveled). Other magnetization orientation of magnetic layer 11 is also possible as long as it achieves the function and purpose of this invention. Cantilever 10 has a first (right) end associated with the first (right) end of first magnet 11 and contact 13, and has a second (left) end associated with the second (left) end of first magnet 11 and contact 14. Magnetic layer 11 can be any type of hard magnetic material that can retain a remnant magnetization in the absence of an external magnetic field and its remnant magnetization cannot be easily demagnetized. In an exemplary embodiment, magnetic layer 11 is a thin SmCo permanent magnet with an approximate remnant magnetization (Br=μ0M) of about 1 T through its thickness (predominantly along the x-axis). Other possible hard magnetic materials are, for example, NdFeB, AlNiCo, Ceramic magnets (made of Barium and Strontium Ferrite), CoPtP alloy, and others, that can maintain a remnant magnetization (Br=μ0M) from about 0.001 T (10 Gauss) to above 1 T (104 Gauss), with coercivity (Hc) from about 7.96×102 A/m (10 Oe) to above 7.96×105 A/m (104 Oe). Flexure spring and support 12 can be any flexible material that on one hand supports cantilever 10 and on the other allows cantilever 10 to be able to move and rotate. Flexure spring and support can be made of metal layers (such as Beryllium Copper, Ni, stainless steel, etc.), or non-metal layers (such as polyimide, Si, Si3Ni4, etc.). The flexibility of the flexure spring can be adjusted by its thickness, width, length, shape, and elasticity, etc. Pivot 15 further supports the cantilever to maintain a gap between cantilever 11 and soft magnetic layer 31. Pivot 15 can be placed on the top of cantilever 11 to maintain a gap between cantilever 11 and soft magnetic layer 32. Electrical contacts 13 and 14 can be any electrically conducting layer such as Au, Ag, Rh, Ru, Pd, AgCdO, Tungsten, etc., or suitable alloys. Electrical contacts 13 and 14 can be formed onto the tips (ends) of the cantilever by electroplating, deposition, welding, lamination, or any other suitable means. Flexure spring and support 12 and electrical contacts 13 and 14 can be formed by either using one process and the same material, or by using multiple processes, multiple layers, and different materials. When cantilever 10 rotates and its two ends move up or down, electrical contact 13 or 14 either makes or breaks the electrical connection with the bottom contact 41 or 42. Optional insulating layers (not shown) can be placed between the conducting layers to isolate electrical signals in some cases.
Coil 20 (third electromagnet) is formed by having multiple windings of conducting wires around cantilever 10. The conducting wires can be any conducting materials such as Cu, Al, Au, or others. The windings can be formed by either winding the conducting wires around a bobbin, or by electroplating, deposition, etching, laser forming, or other means used in electronics industry (e.g., semiconductor integrated circuits, printed circuit boards, etc.). One purpose of coil 20 in relay 100, when energized, can be to provide a third vertical (y-axis) magnetic field (Hs) so that a magnetic torque (τ=μ0m×Hs) can be created on cantilever 10. Because magnetic moment m is fixed, the direction and magnitude of the torque depends on the direction and magnitude of the current in coil 20. This arrangement provides a means for external electronic control of the relay switching between different states, as to be explained in detail below.
Soft magnetic layers 31 (second magnet) and 32 can be any magnetic material which has high permeability (e.g., from about 100 to above 105) and can easily be magnetized by the influence of an external magnetic field. Examples of these soft magnetic materials include permalloy (NiFe alloys), Iron, Silicon Steels, FeCo alloys, soft ferrites, etc. Soft magnetic layers 31 and 32 can form a closed magnetic circuit and enhance the coil-induced magnetic flux density (third vertical magnetic field Hs) in the cantilever region. Soft magnetic layers 31 and 32 can also cause an attractive force between the pole of hard magnetic layer 11 and the induced local opposite magnetic pole of the soft magnetic layer so that a stable contact force can be maintained between electrical contact 13 (or 14) and electrical contact 41 (or 42) when the latching feature is desired. Soft magnetic layers 31 and 32 scan be used to confine the magnetic field inside the cavity enclosed by soft magnetic layers 31 and 32 so that the magnetic interference between adjacent devices can be eliminated or reduced. Openings 36 can be suitably formed in soft magnetic layers 31 and 31 to reduce the attractive force between the magnetic poles of magnet 11 and the soft magnetic layers 31 and 32.
Electrical contacts 41 and 42 can be any electrically conducting layer such as Au, Ag, Rh, Ru, Pd, AgCdO, Tungsten, etc., or suitable alloys. Electrical contacts 41 and 42 can be formed on a substrate 33 by electroplating, deposition, welding, lamination, or any other suitable means. Optional insulating layers (not shown) can be placed between the conducting layers to isolate electrical signals in some cases. Transmission-line types of contacts and metal traces can also be suitably designed and formed for high performance radio-frequency applications.
An electromagnet 20, when energized, produces a third magnetic field which can be primarily perpendicular to the magnetization direction of first movable magnet 11 and exerts a magnetic torque on first magnet 11 to force first magnet 11 and cantilever 10 to rotate and close an electrical conduction path at one end (e.g., first end) of cantilever 10. Changing the direction of the electrical current in third electromagnet 20 changes the direction of the third magnetic field and thus the direction of the magnetic torque on first magnet 11, and causes first magnet 11 and cantilever 10 to rotate in an opposite direction and opens the electrical conduction path at one end (e.g., first end) of cantilever 10 and closes the electrical conduction path at the other end (e.g., second end).
With continued reference to
Some of the aforementioned advantages of the disclosed invention can be evidenced by the following examples.
The first magnet having the following characteristics: length=4 mm (along long axis), width=4 mm, thickness=0.2 mm, volume V=length×width×thickness, remnant magnetization Br=μ0M=1 T, the magnetic moment μ0m=μ0M×V=3.2×10−9 T·m3. For a coil-induced magnetic field μ0Hs=0.05 T (Hs=500 Oe), the induced magnetic torque about the length center is τ=μ0m×Hs=1.27×10−4 m·N (m is perpendicular to Hs) which corresponds to a force of Fm=τ/(length/2)=6.4×10−2 N at the end of the first magnet. The above exemplary parameters show that for a relatively small coil-induced magnetic field (Hs=500 Oe), a significantly large torque and force can be generated. The torque and force can continue to increase with larger Hs (correspondingly larger coil current). When the angle between m and Hs changes from perfectly perpendicular (90°) to 80°, the change in the magnitude of the torque (and force) is only 1.5%=1−98.5%=1−sin(80°), which gives a larger tolerance in production variations, simplifies the production process, and reduces costs.
With continued reference to
Coil 20 (third electromagnet) can be formed by having multiple windings of conducting wires around cantilever 10. The conducting wires can be any conducting materials such as Cu, Al, Au, or others. The windings can be formed by either winding the conducting wires around a bobbin, or by electroplating, deposition, etching, laser forming, or other means used in electronics industry (e.g., semiconductor integrated circuits, printed circuit boards, etc.). Coil 20 in relay 200, when energized, provides a third horizontal (x-axis) magnetic field (Hs) so that a magnetic torque (τ=μ0m×Hs) can be created on cantilever 10. Because magnetic moment m is fixed, the direction and magnitude of the torque depends on the direction and magnitude of the current in coil 20.
Soft magnetic layers 31 (second magnet) and 32 can be any magnetic material which has high permeability (e.g., from about 100 to above 105) and can easily be magnetized by the influence of an external magnetic field. Examples of these soft magnetic materials include permalloy (NiFe alloys), Iron, Silicon Steels, FeCo alloys, soft ferrites, etc. Soft magnetic layers 31 and 32 forms a closed magnetic circuit and enhances the coil-induced magnetic flux density (third vertical magnetic field) in the cantilever region. Soft magnetic layers 31 and 32 can cause an attractive force between the pole of hard magnetic layer 11 and the induced local opposite magnetic pole of the soft magnetic layer so that a stable contact force can be maintained between electrical contact 13 (or 14) and electrical contact 41 (or 42). Soft magnetic layers 31 and 32 can also confine the magnetic field inside the cavity enclosed by soft magnetic layers 31 and 32 so that the magnetic interference between adjacent devices can be eliminated or reduced. Openings 36, which effectively increase the distance between soft magnetic layer 31 (and/or 32) and the ends of first magnet 11, can be suitably formed as recessed contours in soft magnetic layers 31 (and/or 32) to reduce the attractive force between the magnetic poles of magnet 11 and the soft magnetic layers 31 and 32.
Electrical contacts 41 and 42 can be any electrically conducting layer such as Au, Ag, Rh, Ru, Pd, AgCdO, Tungsten, etc., or suitable alloys. Electrical contacts 41 and 42 can be formed on a substrate 33 by electroplating, deposition, welding, lamination, or any other suitable means. Optional insulating layers (not shown) can be placed between the conducting layers to isolate electrical signals in some cases. Transmission-line types of contacts and metal traces can also be suitably designed and formed for high performance radio-frequency applications.
Energizing (passing a current in) electromagnet 20 produces a third magnetic field which can be primarily perpendicular to the magnetization direction of first movable magnet 11 and exerts a magnetic torque on first magnet 11 to force first magnet 11 and cantilever 10 to rotate and close an electrical conduction path at one end (e.g., first end) of cantilever 10. In the illustration shown in
With continued reference to
In the exemplary embodiment shown in
With continued reference to
It is understood that a variety of methods can be used to fabricate the electromechanical relay. These methods include, but not limited to, semiconductor integrated circuit fabrication methods, printed circuit board fabrication methods, micro-machining methods, and so on. The methods include processes such as photo lithography for pattern definition, deposition, plating, screen printing, etching, lamination, molding, welding, adhering, bonding, and so on. The detailed descriptions of various possible fabrication methods are omitted here for brevity.
It will be understood that many other embodiments and combinations of different choices of materials and arrangements could be formulated without departing from the scope of the invention. Similarly, various topographies and geometries of relay 100 could be formulated by varying the layout of the various components.
The corresponding structures, materials, acts and equivalents of all elements in the claims below are intended to include any structure, material or acts for performing the functions in combination with other claimed elements as specifically claimed. Moreover, the steps recited in any method claims may be executed in any order. The scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given above.
This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/046,894, filed on Apr. 22, 2008. This patent application is related to U.S. application Ser. No. 12/268,936, filed on Nov. 11, 2008, which is a divisional of U.S. Pat. No. 7,482,899 B2, issued on Jan. 27, 2009.
| Number | Date | Country | |
|---|---|---|---|
| 61046894 | Apr 2008 | US |
