Rotary solenoid with magnetic return

Abstract

A rotary solenoid can include a shaft, a rotor, a case, a coil, at least one first protuberance, at least one second protuberance, and at least one permanent magnet. The shaft can have a central longitudinal axis. The rotor can be mounted on the shaft and can have at least one lobe. The protuberances can be spaced apart and define a gap therebetween substantially the same size as the lobe. The lobe can be rotated into the gap by a magnetic field generated by the coil. The permanent magnet can be disposed in the case, have north and south poles that are spaced from one another along the axis, and generate a magnetic field whereby the lobe can be rotated out of the gap when the coil is de-energized.

Description

ROTARY SOLENOID WITH MAGNETIC RETURNBACKGROUND1. Field

[0001] The present disclosure relates to rotary solenoids.2. Description of Related Prior Art

[0002] U.S. Pat. No. 4135138 discloses a Rotary Solenoid. The rotary solenoid comprises a housing, a rotor rotatably mounted in the housing, the rotor and the housing being comprised of a magnetically permeable material, and a solenoid coil mounted in the housing about the longitudinal axis thereof. The housing has at least a first pole piece portion therein with the rotor further comprising at least a first permanent magnet means mounted therein for simultaneous rotation therewith. The first permanent magnet means has first and second null positions with respect to the first pole piece and is mounted in the plane of the first pole piece for rotation about the longitudinal axis and provides a reverse magnetic flux in the housing and rotor magnetically permeable material. The solenoid coil has an energized state and a deenergized state with the rotor rotating a predetermined angular amount about the longitudinal axis from an initial position in response to a predetermined potential applied to the coil in the energized state. The first permanent magnet means has a pair of opposed sides substantially normal to the pole piece when adjacent thereto with one of the sides having an associated flux concentration which may differ from an associated flux concentration at the other opposed side of the permanent magnet means whereby the return torque curve of the solenoid may be varied.

[0003] U.S. Pat. No. 5038063 discloses a Rotary Actuator With Limited Angular Movement. The homopol ar actuator has a permanent magnet disk element rotatably positioned between a pair of toothed pole pieces with mutually offset teeth, an electromagnetic coil and pole elements coupling the coil flux to the pole pieces. The pole pieces may themselves be rotatable or stationary. The permanent magnet circuit attempts to center the disk element relative to the pole pieces, and the electromagnetic circuit, depending on the direction of current in the coil, either reinforces the centering action or overcomes the centering force to displace the elements from center position. The device is used as a two or three position actuator or as an actuator or magnetic spring operating against an external force and seeking a position as a function of current.

[0004] U.S. Pat. No. 5337030 discloses a Permanent Magnet Brushless Torque Actuator. The permanent magnet brushless torque actuator is comprised of an electromagnetic core capable ofgenerating an elongated toroidally shaped magnet flux field when energized. Outside the generally cylindrical coil is an outer housing with upper and lower end plates at each end. Mounted to the end plates and extending towards each other are stator pole pieces separated from its opposing pole piece by an air gap. A permanent magnet rotor is disposed in the air gap and mounted on a shaft which in turn is rotatably mounted in each of the end plates. The permanent magnet rotor comprises at least two permanent magnets, each covering an arcuate portion of the rotor and having opposite polarities. Energization of the coil with current in one direction magnetizes the pole pieces such that each of the two pole pieces attracts one of the magnets of the rotor and repels the other magnet of the rotor resulting in a torque generated by the output shaft. Reversal of the current flow results in a reversal of the torque and rotation of the rotor in the opposite direction. Preferred embodiments are disclosed having multiple cells, i.e. a plurality of stator rotor stator combinations and / or cells in which there are a plurality of pole pieces at each stator pole plane.

[0005] U.S. Pat. No. 6269838 discloses a Rotary Servovalve and Control System. The rotary servovalve system employs a rotary magnetic solenoid having an armature that includes at least one permanent magnet. The armature is rotatable relative to a stator formed as an electromagnet which is energizable to create alternative electromagnetic fields having opposite polarities from each other. When deenergized, the stator allows the armature to return to a neutral, null position from positions of extreme rotation in opposite angular directions due to the magnetic force of the permanent magnet of the armature. The armature is coupled to carry a movable valve element in angular rotation therewith, so that flow through the servovalve of the system can occur in alternative directions. Also, the valve element is biased toward a position in which all of the valve ports are closed when power is removed from the rotary solenoid. The control circuit employed in the rotary servovalve system expands the bandwidth of response of the solenoid actuator by compensating for frequency variations in the input command signal and in the feedback signal. This compensation is achieved utilizing a combined proportional, integral, and differential amplification circuit. Also, imbalance of fluid forces within the servovalve mechanism can be avoided by utilizing a pair of inlet orifices, a pair of outlet orifices, a pair of first fluid control orifices, and a pair of second fluid control orifices. The orifices within each pair are located on opposite sides of the valve housing from each other.

[0006] U.S. Pub. No. 20030006729A1 discloses a Rotary Servovalve With Precision Controller. The rotary servovalve system employs a rotary magnetic solenoid having an armature that includes at least one permanent magnet. The armature is rotatable relative to a stator formed as an electromagnet which is energizable to create alternative electromagnetic fields having opposite polarities from each other. When deenergized, the stator allows the armature to return to a neutral,null position from positions of extreme rotation in opposite angular directions due to the magnetic force of the permanent magnet of the armature. The armature is coupled to carry a movable valve element in angular rotation therewith, so that flow through the servovalve of the system can occur in alternative directions. Also, the valve element is biased toward a position in which all of the valve ports are closed when power is removed from the rotary solenoid. The control circuit employed in the rotary servovalve system expands the bandwidth of response of the solenoid actuator by compensating for frequency variations in the input command signal and in the feedback signal. This compensation is achieved utilizing a combined proportional, integral, and differential amplification circuit. Also, imbalance of fluid forces within the servovalve mechanism can be avoided by utilizing a pair of inlet orifices, a pair of outlet orifices, a pair of first fluid control orifices, and a pair of second fluid control orifices. The orifices within each pair are located on opposite sides of the valve housing from each other.

[0007] U.S. Reissued Pat. No. RE40503 discloses a Hybrid Rotary Actuator. The rotary actuator includes a rotor which is disposed in a housing between first and second pole pieces of a stator. The rotor is rotatable relative to the stator between an unactuated position and an actuated position. During rotation of the rotor, the axial extent of a first working air gap between the rotor and the first pole piece of the stator remains constant. However, the axial extent of the working air gap between the rotor and the second pole piece of the stator decreases as the rotor moves from the unactuated position to the actuated position. In a preferred embodiment, the rotor lobes are made so that the net axial force of all of the rotor lobes is substantially zero thereby reducing stress on the rotor shaft support bearings.

[0008] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0009] This section provides a simplified summary in order to provide a basic understanding of some aspects described herein. This summary is not an extensive overview and is not intended to identify “key” or “critical” elements of the present disclosure or to delineate the scope of the various aspects described herein. The purpose of this portion of the document is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0010] A rotary solenoid can include a shaft, a rotor, a case, a coil, at least one first protuberance, at least one second protuberance, and at least one permanent magnet. The shaft can have a central longitudinal axis. The rotor can be mounted on the shaft and can have at least one lobe. The rotor can be fixed to the shaft for concurrent rotation with the shaft. The at least one lobe can project radially away from the central longitudinal axis. The at least one lobe can define a first thickness along the central longitudinal axis. The case can define an interior and can extend between a first end and a second end. At least part of the shaft and the rotor can be disposed in the interior and can be concurrently rotatable relative to the case about the central longitudinal axis. The coil can be at least partially disposed in the case. The at least one first protuberance can be disposed in the interior of the case. The at least one second protuberance can be disposed in the interior of the case and can be spaced from the at least one first protuberance along the central longitudinal axis. At least one gap can be defined along the central longitudinal axis between the at least one first protuberance and the at least one second protuberance. The at least one gap can be substantially the same size as the first thickness of the at least one lobe. The at least one lobe can rotate in a first rotational direction into the at least one gap by a first magnetic field generated by the coil when the coil is energized. The at least one permanent magnet can be disposed in the interior of the case and can have north and south poles that are spaced from one another along the central longitudinal axis and that can generate a second magnetic field whereby the at least one lobe can rotate in a second rotational direction about the central longitudinal axis, opposite the first rotational direction, out of the at least one gap when the coil is de-energized.

[0011] According to other features, the at least one lobe can be rotated, about the central longitudinal axis, out of the at least one gap, by the second magnetic field generated by the at least one permanent magnet, when the coil is de-energized. The at least one lobe can be rotated into a static position at least partially overlapping the at least one permanent magnet along the central longitudinal axis. The at least one permanent magnet can be fully overlapped by the at least one lobe when the at least one lobe is in the static position.

[0012] In other features, the at least one lobe can be rotated out of the at least one gap by the second magnetic field generated by the at least one permanent magnet when the coil is de-energized and can be rotated into a static position wherein the at least one lobe is aligned with the at least one permanent magnet along a second axis that can be parallel to and spaced from the central longitudinal axis.

[0013] According to additional features, the at least one permanent magnet can be spaced from the at least one gap within the case at least one of axially and radially relative to the centrallongitudinal axis. The at least one permanent magnet can be spaced from the at least one gap within the case both axially and radially relative to the central longitudinal axis.

[0014] According to other features, the shaft can be rotatable between a first end limit of travel and a second end limit of travel. The at least one lobe can be in an active position, within the at least one gap, when the shaft is at the first end limit of travel and can be in a static position when the shaft is at the second end limit of travel. The second magnetic field generated by the at least one permanent magnet can produce a substantially constant level of torque on the at least one lobe throughout movement from the active position to the static position.

[0015] In other features, the at least one first protuberance can extend over a first arcuate range about the central longitudinal axis. The at least one second protuberance can extend a second arcuate range about the central longitudinal axis. The at least one gap can be defined along a portion of overlap between the first arcuate range and the second arcuate range. The first arcuate range can be greater than, equal to, or less than the second arcuate range. The shaft can be rotatable between a first end limit of travel and a second end limit of travel. The at least one lobe can be in a active position within the at least one gap when the shaft is at the first end limit of travel and in a static position when the shaft is at the second end limit of travel. At least part of the at least one lobe can pass out of the first arcuate range during movement from the active position to the static position.

[0016] According to additional features, the at least one lobe as well as at least one of the at least one first protuberance and the at least one second protuberance can define a step profile.

[0017] According to other features, the at least one permanent magnet can extend an arcuate range about the central longitudinal axis between a first end that can be closer to the at least one gap and a second end that can be further from the at least one gap. The at least one permanent magnet can define respective radial depths at each position along its arcuate range. Each of the radial depths can be defined along a respective depth axis that can be normal to the central longitudinal axis. Each of the radial depths can extend between a radially-innermost edge of the at least one permanent magnet and a radially-outermost edge of the at least one permanent magnet along the respective depth axis. A first portion of the arcuate range extending in a direction from the first end towards the second end can be of declining radial depth and a second portion of the arcuate range in a direction from the second end towards the first end can be of declining radial depth.

[0018] In other features, a first gradient of declining radial depth of at least part of the first portion can be the substantially the same as a second gradient of declining radial depth of at least part of the second portion. Alternatively, a first gradient of declining radial depth of at least part of the first portion can be different than a second gradient of declining radial depth of at least part of thesecond portion. A gradient of at least part of at least one of the first portion and the second portion can be constant. A reduction of the radial depth of at least part of at least one of the first portion and the second portion can be instantaneous.

[0019] According to additional features, the rotary solenoid can also include a top base and a bottom base. The top base can substantially close the first end of case. The at least one first protuberance can be fixed to the top base and can be disposed in the interior of the case. The bottom base can substantially close the second end of case. The at least one second protuberance can be fixed to the bottom base and can be disposed in the interior of the case. One of the top base and the bottom base can include at least one first pocket and the permanent magnet can be positioned in the at least one first pocket. Another of the top base and the bottom base can include at least one second pocket confronting the at least one first pocket across the interior of the case.

[0020] A method of arranging components for operation as a rotary solenoid can include positioning a rotor with at least one lobe on a shaft for rotation about a central longitudinal axis. The method can also include defining at least one gap with and between first and second protuberances that are on opposite sides of the at least one lobe along the central longitudinal axis and that are radially spaced from the central longitudinal axis. The method can also include positioning a coil around the rotor and the first and second protuberances whereby, upon the energization of the coil, the at least one lobe moves into the at least one gap, to a first end limit of travel, to complete a first magnetic circuit that passes through the first and second protuberances and the at least one lobe. The method can also include disposing a at least one permanent magnet at a position that can be spaced from the at least one gap whereby, upon the de-energization of the coil, the at least one lobe moves out of the at least one gap, to a second end limit of travel, to complete a second magnetic circuit that passes through the at least one permanent magnet and the at least one lobe. The method can also include spacing the at least one permanent magnet from the at least one lobe along the central longitudinal axis.

[0021] According to other features, the method can also include shaping at least one of the at least one lobe and the at least one permanent magnet such that a substantially constant level of torque is generated on the at least one lobe throughout movement of the at least one lobe from the first end limit of travel to the second end limit of travel. The shaping can be further defined as shaping the at least one permanent magnet by reducing a radial depth of the at least one permanent magnet along a mid-section of the at least one permanent magnet between its opposite arcuate ends, wherein the at least one permanent magnet extends an arcuate range about the central longitudinal axis between a first end that can be closer to the at least one gap and a second end that can be further from the at leastone gap, wherein the at least one permanent magnet defines respective radial depths at each position along its arcuate range, wherein each of said radial depths is defined along a respective depth axis that can be normal to the central longitudinal axis, wherein each of said radial depths extends between a radially-innermost edge of the at least one permanent magnet and a radially-outermost edge of the at least one permanent magnet along the respective depth axis.

[0022] In other features, the method can also include defining a three-dimensional space that can be adjacent, along the central longitudinal axis, to a first surface of the at least one permanent magnet to be open when the at least one lobe is in the at least one gap and at the first end limit of travel, wherein the first surface extends in plane normal to the central longitudinal axis, and whereby the three-dimensional space is occupied by the at least one lobe when the at least one lobe is at the second end limit of travel.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The detailed description set forth below references the following drawings:

[0024] Figure l is a perspective view of a rotary solenoid, with portions cut-away, according to an exemplary embodiment of the present disclosure;

[0025] Figure 2 is a perspective view of a rotor of the rotary solenoid shown in Figure 1 ;

[0026] Figure 3 is a permanent magnet of the rotary solenoid shown in Figure 1;

[0027] Figure 4 is a partial cross-sectional view taken in plane shown by section lines 4 - 4 in Figure 1, the plane normal to a central longitudinal axis of the exemplary rotary solenoid;

[0028] Figure 5 is a first perspective view of components of another embodiment of the present disclosure;

[0029] Figure 6 is a second perspective view of the components shown in Figure 5 wherein one of the components has moved;

[0030] Figures 7A and 7B are, respectively, left-side and top views of a first exemplary permanent magnet that can be a component of a rotary solenoid according to an exemplary embodiment of the present disclosure;

[0031] Figures 8A and 8B are, respectively, left-side and top views of a second exemplary permanent magnet that can be a component of a rotary solenoid according to an exemplary embodiment of the present disclosure;

[0032] Figures 9A and 9B are, respectively, left-side and top views of a third exemplary permanent magnet that can be a component of a rotary solenoid according to an exemplary embodiment of the present disclosure;

[0033] Figures 10A and 10B are, respectively, left-side and top views of a fourth exemplary permanent magnet that can be a component of a rotary solenoid according to an exemplary embodiment of the present disclosure;

[0034] Figures 11A and 11B are, respectively, left-side and top views of a fifth exemplary permanent magnet that can be a component of a rotary solenoid according to an exemplary embodiment of the present disclosure; and

[0035] Figures 12A and 12B are, respectively, left-side and top views of a sixth exemplary permanent magnet that can be a component of a rotary solenoid according to an exemplary embodiment of the present disclosure.DETAILED DESCRIPTION

[0036] A plurality of different embodiments of the present disclosure is shown in the Figures of the application. Similar features are shown in the various embodiments of the present disclosure. Similar features across different embodiments have been numbered with a common reference numeral and have been differentiated by an alphabetic suffix. Also, to enhance consistency, the structures in any particular drawing share the same alphabetic suffix even if a particular feature is shown in less than all embodiments. Similar features are structured similarly, operate similarly, and / or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment or can supplement other embodiments unless otherwise indicated by the drawings or this specification.

[0037] The present disclosure, as demonstrated by the exemplary embodiments described below, provides a rotary solenoid. Referring now to Figures 1 - 4, an exemplary rotary solenoid 10 includes a shaft 12 having a central longitudinal axis 14. The exemplary shaft 12 is the output shaft of the rotary solenoid 10.

[0038] The exemplary rotary solenoid 10 also includes a rotor 16 mounted on the exemplary shaft 12. The exemplary rotor 16 includes two lobes 18 and 20 that are identically shaped. Neither of the exemplary lobes 18, 20 is permanently magnetized and no permanent magnets are mounted on either of the exemplary lobes 18, 20. The lobes 18, 20 extend away from the central longitudinal axis 14 in opposite directions. The exemplary rotor 16 is fixed to the exemplary shaft 12 for concurrent rotation with the shaft 12. Each of the exemplary lobes 18, 20 project perpendicularly away from the central longitudinal axis 14. Each lobe 18, 20 defines a first thickness along the central longitudinal axis 14. As used herein, a thickness of a structure is defined along the central longitudinal axis 14, an arcuate width of a structure that can rotate or an arcuate range of a structure that does not rotate ora range of an empty space will be defined around the central longitudinal axis 14, and a depth will be defined radially along an axis that is normal to the central longitudinal axis 14. The exemplary lobe 18 defines a step profile and thus has more than one thickness. The thickness of the exemplary lobe 18 includes a portion of first thickness referenced at 22 in Figure 2 and a portion of second thickness referenced at 24. The exemplary lobe 18 defines an arcuate width between a first edge 100 and a second edge 102. In one or more embodiments of the present disclosure, the lobe can be tapered, axially along the central longitudinal axis 14 and / or radially towards and / or away from the central longitudinal axis 14, while still permitting a substantially constant torque when energized by the coil.

[0039] The exemplary rotary solenoid 10 also includes a case 26. The exemplary case 26 defines an interior 28. The exemplary case 26 extends between a first end 30 and a second end 32. As shown in Figure 1, at least part of the shaft 12 and the rotor 16 are disposed in the interior 28 and concurrently rotatable relative to the case 26 about the central longitudinal axis 14. The exemplary case 26 is centered on the central longitudinal axis 14.

[0040] The exemplary rotary solenoid 10 also includes a top base 34. The exemplary top base 34 substantially closes the first end 30 of case 26. The exemplary rotary solenoid 10 also includes a bottom base 36. The exemplary bottom base 36 substantially closes the second end 32 of case 26. The exemplary bottom base 36 includes at least one first pocket 38 and the exemplary top base 34 includes at least one second pocket 40 confronting the first pocket 38 across the interior 28 of the case 26. It is noted that the words “top” and “bottom” are used merely to differentiate structures like the bases from one other. Such terms are not binding on embodiments of the present disclosure. The “top” base 34 need not be above the “bottom” base 36 during assembly or operation of the rotary solenoid 10.

[0041] The exemplary rotary solenoid 10 also includes a bobbin assembly 42. The exemplary bobbin assembly 42 is at least partially disposed in the case 26. The exemplary bobbin assembly 42 includes a bobbin 44 and a coil 46 wound around the bobbin 44. The exemplary bobbin assembly 42 also includes leads for the coil 46, which are not shown in the Figures so that other structures of the rotary solenoid 10 can be better seen.

[0042] The exemplary rotary solenoid 10 also includes at least one first protuberance 48 disposed in the interior 28 of the case 26. The exemplary first protuberance 48 is integrally-formed with the exemplary top base 34. Integrally-formed refers to the fact that in the exemplary embodiment the first protuberance 48 and the top base 34 are formed together rather than being formed separately and then subsequently joined. The term defines a structural feature since structures that are integrally- formed are structurally different than structures that are comprised of subcomponents formedseparately and then subsequently joined. “Integral” means consisting or composed of parts that together constitute a whole and thus encompasses structures of more than one part wherein the parts are either integrally-formed or formed separately and then subsequently joined. In other embodiments of the present disclosure, the first protuberance 48 can be fixed to the top base 34 through fasteners or adhesive. The interconnection between the first protuberance 48 and the top base 34 fixes the first protuberance 48 axially and radially relative to the central longitudinal axis 14 within the interior 28.

[0043] The exemplary rotary solenoid 10 also includes at least one second protuberance 50. The exemplary second protuberance 50 is disposed in the interior 28 of the case 26. The exemplary second protuberance 50 is integrally-formed with the exemplary bottom base 36. In other embodiments of the present disclosure, the second protuberance 50 can be fixed to the bottom base 36 through fasteners or adhesive. The interconnection between the second protuberance 50 and the bottom base 36 fixes the second protuberance 50 axially and radially relative to the central longitudinal axis 14 within the interior 28.

[0044] The exemplary second protuberance 50 is spaced from the exemplary first protuberance 48 along the central longitudinal axis 14, wherein a gap 52 is defined along the central longitudinal axis 14 between the first protuberance 48 and the second protuberance 50. The exemplary gap 52 is substantially the same size as the thickness of the lobe 18 and the same shape as the lobe 18. For example, because the lobe 18 has a stepped profile, the first protuberance 48 and the second protuberance 50 each have corresponding stepped profiles, as shown in Figure 1.

[0045] In the exemplary embodiment, both protuberances 48 and 50 define a step profile and both top and bottom sides of the lobe 18 define respective step profiles. In one or more embodiments of the present disclosure, only an upper protuberance and the top side of a lobe may have a complementary step profile and a lower protuberance and a bottom side of the lobe may not have a step profile. In other embodiments of the present disclosure, only the lower protuberance and the bottom side of the lobe may have a complementary step profile and the upper protuberance and the top side of the lobe may not have a step profile. It is noted that in one or more embodiments of the present disclosure, all of the protuberances can be identically-shaped and the all of the lobes can be identically-shaped to permit installation of the rotor in any orientation relative to the protuberances. It has been found by the inventors that such an arrangement produces slightly more torque since all rotor / lobe faces are overlapped with protuberance faces and thus producing torque.

[0046] The exemplary gap 52 has a range about the central longitudinal axis 14 starting at a “leading” or first edge 54 that is defined by both of the first protuberance 48 and the second protuberance 50. The arcuate range of the exemplary gap 52 extends from the first edge 54 to a“trailing” or second edge 56. The exemplary second edge 56 is defined only by the second protuberance 50. The range of the exemplary gap 52 is thus referenced at 58 in Figure 4. The range 58 of the gap 52 is thus the same as the arcuate range of the exemplary second protuberance 50. The exemplary first protuberance 48 extends around the central longitudinal axis 14 further than the exemplary second protuberance 50 and beyond the exemplary gap 52, to a second edge 98. The arcuate range of the exemplary first protuberance 48 is thus greater than the arcuate range of the exemplary second protuberance 50.

[0047] When the exemplary rotary solenoid 10 is activated, electrical current is supplied to and passes through the coil 46, which generates a magnetic field. The magnetic field prefers the lowest reluctance path to complete a magnetic flux loop extending through a center of the coil 46 and around the cylindrical outer side of the coil 46. In the exemplary rotary solenoid 10, the energized coil 46 will generate magnetic forces that urge the lobe 18 into the gap 52, into axial alignment with the protuberances 48, 50, to thus create a substantially continuous flux path with minimized reluctance, through the top base 34, the first protuberance 48, the lobe 18, the second protuberance 50, and the bottom base 36. The exemplary lobe 18 is thus rotated in a first rotational direction into the gap 52 by the magnetic field generated by the bobbin assembly 42 when the coil 46 of the bobbin assembly 42 is energized.

[0048] As set forth above, the exemplary gap 52 is substantially the same size as the thickness of the exemplary lobe 18 along the central longitudinal axis 14 over the entire exemplary range 58. Substantially the same size indicates that the exemplary lobe 18 can be received between the first and second protuberances 48, 50 but spacing between the exemplary lobe 18 and the first and second protuberances 48, 50 is minimized to enhance the flow of magnetic flux and inhibit reluctance.

[0049] The exemplary rotary solenoid 10 also includes a permanent magnet 60. Various embodiments of the present disclosure can include any number of permanent magnets similar to the exemplary permanent magnet 60 as described herein. The exemplary permanent magnet 60 is disposed in the interior 28 of the case 26. The exemplary permanent magnet 60 is positioned in the first pocket 38 of the bottom base 36. The exemplary permanent magnet 60 is spaced from the exemplary gap 52 within the case 26 both axially (along) and radially (about) relative to the central longitudinal axis 14. The exemplary permanent magnet 60 includes a surface 62 directed toward the longitudinal center of the interior 28.

[0050] As best seen in Figure 4, the exemplary permanent magnet 60 extends an arcuate range 64 about the central longitudinal axis 14 between a first end 66 that is closer to the gap 52 and a second end 68 that is further from the gap 52. The exemplary permanent magnet 60 defines respectiveradial depths at each position along the arcuate range 64. Each of the radial depths is defined along a respective depth axis that is normal to the central longitudinal axis 14. Each radial depth extends between a radially innermost edge 74 of the exemplary permanent magnet 60 and a radially outermost edge 76 of the exemplary permanent magnet 60 along the respective depth axis.

[0051] For example, a first radial depth is referenced at 70. The exemplary first radial depth 70 is defined along an exemplary depth axis 72 that is normal to the central longitudinal axis 14. The exemplary first radial depth 70 extends between the radially innermost edge 74 of the exemplary permanent magnet 60 and the radially outermost edge 76 of the exemplary permanent magnet 60 along the exemplary depth axis 72. Similarly, an exemplary second radial depth 78 is defined along an exemplary depth axis 80 that is normal to the central longitudinal axis 14, between the radially innermost edge 74 and the radially outermost edge 76. Similarly, an exemplary third radial depth 82 is defined along an exemplary depth axis 84 that is normal to the central longitudinal axis 14, between the radially innermost edge 74 and the radially outermost edge 76. It is noted that the exemplary second radial depth 78 is the minimal radial depth of the exemplary permanent magnet 60.

[0052] As also shown in Figure 4, a first portion 86 of the arcuate range 64, in a direction from the first end 66 towards the second end 68, is of declining radial depth and a second portion 88 of the arcuate range 64, in a direction from the second end 68 towards the first end 66, is also of declining radial depth.

[0053] The exemplary permanent magnet 60 has north and south poles that are spaced from one another along the central longitudinal axis 14. The north pole may be proximate to the surface 62 or the south pole may be proximate to the surface 62 in various embodiments of the present disclosure. The exemplary permanent magnet 60 generates a second magnetic field whereby the exemplary lobe 18 is rotated in a second rotational direction about the central longitudinal axis 14, opposite the first rotational direction, and out of the gap 52 when the coil 46 of the bobbin assembly 42 is de-energized.

[0054] It is noted that reference line 90 in Figure 4 corresponds to the plane in which the steps of the exemplary lobe 18 and the exemplary protuberances 48, 50 would be defined. Reference line 92 in Figure 4 corresponds to the arcuate range of the first protuberance 48. Reference line 94 in Figure 4 corresponds to a plane in which an edge of another second protuberance would be defined. Reference line 96 in Figure 4 corresponds to a plane to which the second end 68 of the exemplary permanent magnet 60 extends about the central longitudinal axis 14.

[0055] The exemplary shaft 12 is rotatable between a first end limit of travel and a second end limit of travel. When the exemplary shaft 12 is at the first end limit of travel, the coil 46 isenergized, the exemplary lobe 18 is positioned within the exemplary gap 52 and is designated herein as being in the “active” position. When the exemplary gap 52 is in the active position, the exemplary edges 54 and 100 are aligned about the central longitudinal axis 14 and the exemplary edges 98 and 102 are aligned about the central longitudinal axis 14. In one or more embodiments of the present disclosure, there can be structural stops that create the first and second ends of travel. This can be desirable to prevent the lobe stops from touching (impacting), but would result in increased wear and potentially residual magnetism which might inhibit the magnet return torque.

[0056] In addition, when the exemplary lobe 18 is in the active position, the portion of the exemplary interior 28 that is between the surface 62 of the exemplary permanent magnet 60 and the exemplary pocket 40 in the top base 34 is substantially empty. The various components of the exemplary rotary solenoid 10 thus cooperate to define a substantially empty three-dimensional space that is adjacent to the surface 62 along the central longitudinal axis 14.

[0057] When the exemplary shaft 12 is at the second end limit of travel, the coil 46 is deenergized and the exemplary lobe 18 moves out of the exemplary gap 52 to what is designated herein as its “static” position. When the exemplary lobe 18 is in the static position, the exemplary edges 54 and 100 are no longer aligned about the central longitudinal axis 14 and the exemplary edges 98 and 102 are no longer aligned about the central longitudinal axis 14. The three dimensional space above the surface 62 is occupied by the exemplary lobe 18 when the exemplary shaft 12 is at the second end limit of travel and the exemplary lobe 18 is in the static position. It is noted that reference arrow 104 in Figure 4 corresponds to the direction of rotational movement of the exemplary lobe 18 from the active position to the static position.

[0058] The exemplary lobe 18 can be rotated in the direction 104 out of the exemplary gap 52, out of the active position, by the second magnetic field that is generated by the exemplary permanent magnet 60 when the exemplary bobbin assembly 42 is de-energized. In the static position, the exemplary lobe 18 at least partially overlaps the exemplary permanent magnet 60 along the central longitudinal axis 14. The exemplary lobe 18 can at least partially overlap the exemplary permanent magnet 60 along the central longitudinal axis 14 such that the exemplary surface 62 of the permanent magnet 60 is covered by the exemplary lobe 18 and not exposed to the top base 34. For example, in an overlapped portion of the permanent magnet 60, an axis extending parallel to the central longitudinal axis 14 does not extend between the exemplary surface 62 of the exemplary permanent magnet 60 and an opposing facing surface of the top base 34 without passing through the exemplary lobe 18. The exemplary lobe 18 can fully overlap the exemplary permanent magnet 60 along thecentral longitudinal axis 14 when the exemplary lobe 18 is in the static position in one or more embodiments of the present disclosure.

[0059] When the exemplary bobbin assembly 42 is de-energized and the exemplary lobe 18 is rotated into the static position, the exemplary lobe 18 can be aligned with the exemplary permanent magnet 60. The exemplary lobe 18 can be aligned with the exemplary permanent magnet 60 along a second axis that is parallel to and spaced from the central longitudinal axis 14. The exemplary lobe 18 and the exemplary permanent magnet 60 are aligned, for example, when the exemplary trailing edge 102 of the exemplary lobe 18 is in the plane 96. Alignment can also be realized when most of the cross-sectional area of a surface 106 (referenced in Figure 2) of the exemplary lobe 18 directly confronts the surface 62 of the exemplary permanent magnet 60. In other words, the exemplary lobe 18 and the exemplary permanent magnet 60 are aligned when stacked on top of one another along the central longitudinal axis 14.

[0060] In the exemplary embodiment, the second magnetic field generated by the exemplary permanent magnet 60 results in a substantially constant level of torque on the exemplary lobe 18 throughout movement of the exemplary lobe 18 from the active position to the static position. The exemplary permanent magnet 60 is shaped such that the radial depth is reduced along a mid-section of the exemplary permanent magnet 60 between its opposite ends 66, 68.

[0061] If a permanent magnet of constant radial depth replaced the exemplary permanent magnet 60 in the exemplary embodiment of the present disclosure, the level of torque acting upon the exemplary lobe 18, to induce movement to the static position, would initially be relatively low. After movement to, generally, a midpoint between the active and static positions, the level of torque acting upon the exemplary lobe 18 would increase to a relatively high level. Upon further movement from the midpoint to the static position, the level of torque acting upon the exemplary lobe 18 from the magnetic field generated by the permanent magnet of constant radial depth would steadily decrease to a relatively low level of torque near the static position.

[0062] The level of torque generated on the exemplary lobe 18, as a result of the magnetic field produced by the exemplary permanent magnet 60, is dependent on the extent of the surface 62 that is exposed and not overlapped by the exemplary lobe 18. The exposed area of the surface 62 can be considered in sections. A section is designated as the area of the surface 62 that (i) extends radially away from the central longitudinal axis 14 between the radially innermost edge 74 and the radially outermost edge 76 (the radial depth) and (ii) extends angularly about the central longitudinal axis 14 between two radial depth axes.

[0063] Generally, increasing the radial depth of a section increases the area of that section, the magnetic flux attributable to that area, and thus the contribution of torque acting on the lobe that can be attributed to that area. Similarly, again generally, decreasing the radial depth of a section decreases the area of that section, the magnetic flux attributable to that area, and thus the contribution of torque acting on the lobe that can be attributed to that area. However, increasing or decreasing the area of a section is not merely a localized change. Changing the area of a particular section affects the overall magnetic field and thus affects the net torque arising at all the positions along the lobe’s path of movement that precede the position of the section at which the area is changed. For example, increasing the area at a section near the end of the stroke will not only increase the torque at the end of the stroke, but also increase the torque arising at mid-stroke and even slightly increase the torque at the beginning of the stroke. As set forth above and as shown in Figure 4, the second magnetic field generated by the exemplary permanent magnet 60 produces a substantially constant level of torque on the exemplary lobe 18 throughout movement from the active position to the static position through the inclusion of the first portion 86 of declining radial depth and the inclusion of the second portion 88 of increasing radial depth.

[0064] Various alternative embodiments of permanent magnets are shown in the other Figures of the application. Figures 5 and 6 show less than all of the components of a rotary solenoid according to another embodiment of the present disclosure. An exemplary lobe 18a rotates in a direction 104a about a central longitudinal axis 14a after a coil is de-energized toward a static position. The exemplary lobe 18a rotates away from a gap defined in part by a second protuberance 50a that is fixed to a bottom base 36a. A permanent magnet 60a is positioned in a pocket 38a and has a surface 62a. Figure 5 shows the components in respective positions when movement starts and Figure 6 shows the components in respective positions after movement has started but prior to the completion of movement.

[0065] Figure 5 also shows another aspect of an arrangement that can affect the shape chosen for a permanent magnet. Specifically, as shown in Figure 5, an edge of a second lobe 20a is nearly aligned with the second end 68a of the exemplary permanent magnet 60a. The proximity of the second lobe 20a to the second end 68a will tend to induce movement of the second lobe 20a in a direction opposite to the direction 104a. This will have the effect of inhibiting the application of the magnetic field generated by the exemplary permanent magnet 60a to the lobe 18a to induce movement to the static position. The radial depth of the exemplary permanent magnet 60a at the second end 68a can therefore be reduced to reduce the undesired impact of the proximity between the second lobe 20a and the second end 68a.

[0066] A permanent magnet according to another embodiment of the present disclosure is shown at 60b in Figures 7A and 7B, with reference to a possible position of a central longitudinal axis 14b. In this exemplary embodiment, the gradients of at least part of the first portion 86b and of at least part of the second portion 88b, referenced respectively at 108b and 110b, are constant.

[0067] A permanent magnet according to another embodiment of the present disclosure is shown at 60c in Figures 8A and 8B, with reference to a possible position of a central longitudinal axis 14c. In this exemplary embodiment, a first gradient of declining radial depth of at least part of the first portion 86c is different than a second gradient of declining radial depth of at least part of the second portion 88c. The first gradient of declining radial depth of the part 108c of the first portion 86c is generally twice that of the second gradient of the part 110c of the second portion 88c.

[0068] A permanent magnet according to another embodiment of the present disclosure is shown at 60d in Figures 9A and 9B, with reference to a possible position of a central longitudinal axis 14d. In this exemplary embodiment, a first gradient of declining radial depth of a part 108d of a first portion 86d is substantially the same as a second gradient of declining radial depth of a part 1 lOd of a second portion 88d. The parts 108d and 1 lOd are thus mirrored with respect to one another.

[0069] A permanent magnet according to another embodiment of the present disclosure is shown at 60e in Figures 10A and 10B, with reference to a possible position of a central longitudinal axis 14e. In this exemplary embodiment, the gradients of respective parts of the first portion 86e and the second portion 88e, referenced respectively at 108e and 1 lOe, are constant.

[0070] A permanent magnet according to another embodiment of the present disclosure is shown at 60f in Figures 11 A and 1 IB, with reference to a possible position of a central longitudinal axis 14f In this exemplary embodiment, the gradients of parts of the first portion 86f and the second portion 88f, referenced respectively at 108f and 1 lOf, are constant.

[0071] A permanent magnet according to another embodiment of the present disclosure is shown at 60g in Figures 12A and 12B, with reference to a possible position of a central longitudinal axis 14g. In this exemplary embodiment, the reduction of the radial depth of part 110g of the second portion 88g is instantaneous. In other words, the reduction in radial depth occurs in a plane that is normal to the axis 14g.

[0072] It is noted that aligning / overlapping the permanent magnet and the lobe along the central longitudinal axis allows for a more compact footprint for the rotary solenoid 10. It also allows for a higher level of flexibility as the same parts can be used and the performance can be changed by adding more magnets as the pockets for the magnets likely already exist or can be easily added. The exemplary embodiment shown in Figures 1 - 4 has twice as many locations for permanent magnetssince it has top and bottom gaps whereas devices of the prior art only have a gap between the inner and outer diameters.

[0073] It is further noted that the exemplary embodiment shown in Figures 1 - 4 is not polarity sensitive as are the devices of the prior art. Whether a positive or negative voltage is applied to the design, the exemplary lobe 18 will move to the energized position. In the prior art designs, the rotor will only rotate to the energized position if the electrical current is applied such that the magnetic flux opposes the permanent magnet.

[0074] It is further noted that the stepped feature or raised portion 112 referenced in Figure 2 of the exemplary lobe 18 allows the exemplary lobe 18 to partially overlap the permanent magnet 60 when in the active position without latching because it is axially further away from the exemplary permanent magnet 60 than the lower portion 114 of the exemplary lobe 18, which will produce the higher torque which will in turn cause the exemplary lobe 18 to return to the static position when electrical power is removed. While a similar construction can be constructed in a rotary version, each step will cause a lower torque because the radius has to be reduced to obtain a step. With the axial flux design, the radius does not change therefore each exemplary lobe 18 will produce an equal amount of torque.

[0075] It is noted that the rotary solenoid 10 can further include protuberances cooperating and interacting with the lobe 20 as the lobe 18 and protuberances 48, 50 interact as described above. The present disclosure is not limited to any number of lobes or to any number of protuberances.

[0076] As best shown in Figure 3, the exemplary permanent magnet 60 defines a thickness along the central longitudinal axis 14 between the surface 62 and an opposite surface 63. The thickness is referenced at 65 in Figure 3. The exemplary permanent magnet 60 has a constant thickness. However, in other embodiments of the present disclosure, the thickness of a permanent magnet corresponding to the exemplary permanent magnet 60 can be variable. Dictating the shape of the return torque of the rotor / lobe is accomplished in the exemplary embodiment by changing the radial depth of the exemplary permanent magnet 60. Dictating the shape of the return torque of the rotor / lobe can also be accomplished by changing the axial thickness of the permanent magnet or a combination of varying both the axial thickness and the radial depth. An advantage of having the N pole and the S pole on parallel planes is a convenience for manufacturing magnets. Magnets can be made by pressing material and pressing with parallel plates is the easiest approach and being able to use parallel plates to magnetize is also easiest. However, having an uneven surface in the pressing direction is possible and if a lower grade of magnetic material (e.g. bonded) is used, it could be molded into any desirable shape.

[0077] What has been described above includes examples of the subject innovation. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the disclosed subject matter, but many further combinations and permutations of the subject innovation are possible. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to be illustrative and does not pose a limitation on the scope of any innovation disclosed herein unless otherwise claimed. The word “exemplary” is used to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the word “exemplary” is intended to present concepts in a concrete fashion. Further, any statements set forth within the Detailed Description of this document and addressing a prior art device(s) are the observations of the inventors and such statements themselves are not prior art or admissions as to what is prior art. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to be illustrative and does not pose a limitation on the scope of any invention disclosed herein unless otherwise claimed.

[0078] As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Unless indicated otherwise by context, the term “or” is to be understood as an inclusive “or.” Terms such as “first”, “second”, “third”, etc. when used to describe multiple devices or elements, are so used only to convey the relative actions, positioning and / or functions of the separate devices, and do not necessitate either a specific order for such devices or elements, or any specific quantity or ranking of such devices or elements. Use of the terms “about” or “approximately” are intended to describe values above and / or below a stated value or range, as would be understood by one having ordinary skill in the art in the respective context. In some instances, this may encompass values in a range of approx. + / -10%; in other instances there may be encompassed values in a range of approx. + / -5%; in yet other instances values in a range of approx. + / -2% may be encompassed; and in yet further instances, this may encompass values in a range of approx. + / -!%.

[0079] It will be understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof, unless indicated herein or otherwise clearly contradicted by context. Recitations of a value range herein, unless indicated otherwise, serves as a shorthand for referring individually to each separate value falling within the stated range, including the endpoints of the range, each separate value within the range, and all intermediate rangessubsumed by the overall range, with each incorporated into the specification as if individually recited herein. Unless indicated otherwise, or clearly contradicted by context, methods described herein can be performed with the individual steps executed in any suitable order, including: the precise order disclosed, without any intermediate steps or with one or more further steps interposed between the disclosed steps; with the disclosed steps performed in an order other than the exact order disclosed; with one or more steps performed simultaneously; and with one or more disclosed steps omitted.

[0080] While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to a particular embodiment disclosed herein as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will be viewed as covering any embodiment falling within the scope of the appended claims. Also, the right to claim a particular sub-feature, sub-component, or sub-element of any disclosed embodiment, singularly or in one or more sub-combinations with any other subfeature^), sub-component(s), or sub-element(s), is hereby unconditionally reserved by the Applicant. Also, particular sub-feature(s), sub-component(s), and sub-element(s) of one embodiment that is disclosed herein can replace particular sub-features, sub-components, and sub-elements in another embodiment disclosed herein or can supplement and be added to other embodiments unless otherwise indicated by the drawings or this specification. The inventors also assert that any of the claims set forth after this detailed description can be combined with any other claim or claims regardless of whether or not there is a direct line of dependency, unless there is an express indication in this text or the drawings unambiguously indicating that such a combination is not possible. The order of the claims and the lines of dependency are irrelevant to the various ways that the features, elements, subelements, components, sub-components, etc. of the present disclosure can be combined and thus claimed. Further, the doctrine of claim differentiation is to be applied in construing and applying the appended claims. Further, the use of the word “can” in this document is not an assertion that the subject preceding the word is unimportant or unnecessary or “not critical” relative to anything else in this document. The word “can” is used herein in a positive and affirming sense and no other motive should be presumed. More than one “invention” may be disclosed in the present disclosure; an “invention” is defined by the content of a patent claim and not by the content of a detailed description of an embodiment of an invention.

Claims

CLAIMSWhat is claimed is:

1. A rotary solenoid comprising: a shaft having a central longitudinal axis; a rotor mounted on said shaft and having at least one lobe, said rotor fixed to said shaft for concurrent rotation with said shaft, wherein said at least one lobe projects radially away from said central longitudinal axis, and wherein said at least one lobe defines a first thickness along said central longitudinal axis; a case defining an interior and extending between a first end and a second end, wherein at least part of said shaft and said rotor are disposed in said interior and concurrently rotatable relative to said case about said central longitudinal axis; a coil at least partially disposed in said case; at least one first protuberance disposed in said interior of said case; at least one second protuberance disposed in said interior of said case and spaced from said at least one first protuberance along said central longitudinal axis, wherein at least one gap is defined along said central longitudinal axis between said at least one first protuberance and said at least one second protuberance, wherein said at least one gap is substantially the same size as said first thickness of said at least one lobe, and wherein said at least one lobe is rotated in a first rotational direction into said at least one gap by a first magnetic field generated by said coil when said coil is energized; and at least one permanent magnet disposed in said interior of said case and having north and south poles spaced from one another along said central longitudinal axis and generating a second magnetic field whereby said at least one lobe is rotated in a second rotational direction about said central longitudinal axis, opposite the first rotational direction, out of said at least one gap when said coil is de-energized.

2. The rotary solenoid of claim 1 wherein said at least one lobe is rotated, about said central longitudinal axis, out of said at least one gap, by the second magnetic field generated by said at least one permanent magnet, when said coil is de-energized, said at least one lobe rotated into a static position at least partially overlapping said at least one permanent magnet along said central longitudinal axis.

3. The rotary solenoid of claim 2 wherein said at least one permanent magnet is fully overlapped by said at least one lobe when said at least one lobe is in the static position.

4. The rotary solenoid of claim 1 wherein said at least one lobe is rotated out of said at least one gap by the second magnetic field generated by said at least one permanent magnet when said coil is de-energized and rotated into a static position wherein said at least one lobe is aligned with said at least one permanent magnet along a second axis that is parallel to and spaced from said central longitudinal axis.

5. The rotary solenoid of claim 1 wherein said at least one permanent magnet is further defined as spaced from said at least one gap within said case at least one of axially and radially relative to said central longitudinal axis.

6. The rotary solenoid of claim 4 wherein said at least one permanent magnet is further defined as spaced from said at least one gap within said case both axially and radially relative to said central longitudinal axis.

7. The rotary solenoid of claim 1 wherein said shaft is rotatable between a first end limit of travel and a second end limit of travel, wherein said at least one lobe is an active position within said at least one gap when said shaft is at said first end limit of travel and in a static position when said shaft is at said second end limit of travel, and wherein the second magnetic field generated by said at least one permanent magnet produces a substantially constant level of torque on said at least one lobe throughout movement from said active position to said static position.

8. The rotary solenoid of claim 1 wherein said at least one first protuberance extends over a first arcuate range about said central longitudinal axis, wherein said at least one second protuberance extends a second arcuate range about said central longitudinal axis, wherein said at least one gap is defined along a portion of overlap between said first arcuate range and said second arcuate range, and wherein said first arcuate range is greater than, less than, or equal to said second arcuate range.

9. The rotary solenoid of claim 8 wherein said shaft is rotatable between a first end limit of travel and a second end limit of travel, wherein said at least one lobe is in a active position within said at least one gap when said shaft is at said first end limit of travel and in a static position when said shaft is at said second end limit of travel, wherein at least part of said at least one lobe passes out of said first arcuate range during movement from said active position to said static position.

10. The rotary solenoid of claim 1 wherein said at least one lobe as well as at least one of said at least one first protuberance and said at least one second protuberance define a step profile.

11. The rotary solenoid of claim 1 wherein said at least one permanent magnet extends an arcuate range about said central longitudinal axis between a first end that is closer to said at least one gap and a second end that is further from said at least one gap, wherein said at least one permanent magnet defines respective radial depths at each position along said arcuate range, wherein each of said radial depths is defined along a respective depth axis that is normal to said central longitudinal axis, wherein each of said radial depths extends between a radially-innermost edge of said at least one permanent magnet and a radially-outermost edge of said at least one permanent magnet along said respective depth axis, and wherein a first portion of said arcuate range extending in a direction from said first end towards said second end is of declining radial depth and a second portion of said arcuate range extending in a direction from said second end towards said first end is of declining radial depth.

12. The rotary solenoid of claim 11 wherein a first gradient of declining radial depth of at least part of said first portion is substantially the same as a second gradient of declining radial depth of at least part of said second portion.

13. The rotary solenoid of claim 11 wherein a first gradient of declining radial depth of at least part of said first portion is different than a second gradient of declining radial depth of at least part of said second portion.

14. The rotary solenoid of claim 11 wherein a gradient of at least part of at least one of said first portion and said second portion is constant.

15. The rotary solenoid of claim 11 wherein a reduction of the radial depth of at least part of at least one of said first portion and said second portion is instantaneous.

16. The rotary solenoid of claim 1 further comprising: a top base substantially closing said first end of case, wherein said at least one first protuberance is fixed to said top base and disposed in said interior of said case; a bottom base substantially closing said second end of case; wherein said at least one second protuberance is fixed to said bottom base and disposed in said interior of said case; wherein one of said top base and said bottom base includes at least one first pocket and said permanent magnet is positioned in said at least one first pocket; and wherein another of said top base and said bottom base includes at least one second pocket confronting said at least one first pocket across said interior of said case.

17. The rotary solenoid of claim 1 wherein said at least one permanent magnet defines a thickness along said central longitudinal axis and said thickness is a constant.

18. A method of arranging components for operation as a rotary solenoid comprising: positioning a rotor with at least one lobe on a shaft for rotation about a central longitudinal axis; defining at least one gap with and between first and second protuberances that are on opposite sides of the at least one lobe along the central longitudinal axis and that are radially spaced from the central longitudinal axis; positioning a coil around the rotor and the first and second protuberances whereby, upon the energization of the coil, the at least one lobe moves into the at least one gap, to a first end limit oftravel, to complete a first magnetic circuit that passes through the first and second protuberances and the at least one lobe; disposing a at least one permanent magnet at a position that is spaced from the at least one gap whereby, upon the de-energization of the coil, the at least one lobe moves out of the at least one gap, to a second end limit of travel, to complete a second magnetic circuit that passes through the at least one permanent magnet and the at least one lobe; and spacing the at least one permanent magnet from the at least one lobe along the central longitudinal axis.

19. The method of claim 18 further comprising: shaping at least one of the at least one lobe and the at least one permanent magnet such that a substantially constant level of torque is generated on the at least one lobe throughout movement of the at least one lobe from the first end limit of travel to the second end limit of travel.

20. The method of claim 19 wherein said shaping is further defined as: shaping the at least one permanent magnet by reducing a radial depth of the at least one permanent magnet along a mid-section of the at least one permanent magnet between its opposite arcuate ends, wherein the at least one permanent magnet extends an arcuate range about the central longitudinal axis between a first end that is closer to the at least one gap and a second end that is further from the at least one gap, wherein the at least one permanent magnet defines respective radial depths at each position along the arcuate range, wherein each of said radial depths is defined along a respective depth axis that is normal to the central longitudinal axis, wherein the radial depth extends between a radially-innermost edge of the at least one permanent magnet and a radially- outermost edge of the at least one permanent magnet along the respective depth axis.

21. The method of claim 18 further comprising: defining a three-dimensional space that is adjacent, along the central longitudinal axis, to a first surface of the at least one permanent magnet to be open when the at least one lobe is in the at least one gap and at the first end limit of travel, wherein the first surface extends in plane normal to the central longitudinal axis, and whereby the three-dimensional space is occupied by the at least one lobe when the at least one lobe is at the second end limit of travel.

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