Systems and methods for multi-stable solenoids

Abstract

To provide a multi-stable solenoid capable of providing stability to the solenoid when an armature is traveling between stable positions by reducing end stop impact force or intermediate position overshoot of the armature.SOLUTION: A multi-stable solenoid 100 includes a first wire coil 118, a second wire coil 120, and a third wire coil 122, and a magnetic damper 138 composed of a first damping ring 140, a second damping ring 142, and a third damping ring 144. The magnetic damper 138 forms a closed conductive path around a center axis 108. As an armature 124 and a permanent magnet 126 move between stable positions, current is induced inside the magnetic damper 138 and opposing magnetic damping force is generated. When the armature 124 is fired to a center magnetic detent position, overshooting is inhibited and prevented. When the armature 124 travels to a first end position or a second end position, impact force can be reduced.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims priority to U.S. Provisional Application No. 62 / 890,300, filed August 22, 2019, the entire contents of which are incorporated herein by reference.

[0002] <Statement Regarding Federally Sponsored Research> Not applicable. [Background technology]

[0003] Generally, a solenoid may include an armature that is movable in response to an electromagnetic field generated by energizing (hereinafter also referred to as activating) a coil of wire.

[0004] This disclosure relates generally to solenoids, and more particularly to multistable solenoids having magnetic damping rings. Typically, the magnetic damping ring provides stability to the solenoid as the armature moves between stable positions by reducing end-stop impact forces or mid-position overshoot of the solenoid's armature. Summary of the Invention

[0005] In one aspect, the present disclosure provides a solenoid including a wire coil and an armature having a permanent magnet. The armature is movable between two or more stable positions upon selective energization of the wire coil. The solenoid further includes one or more magnetic dampers disposed along a path of movement of the armature. The one or more magnetic dampers are configured to generate a magnetic damping force in a direction opposite to the direction of movement of the armature.

[0006] In one aspect, the present disclosure provides a solenoid including one or more wire coils axially spaced apart from one another and an armature having a permanent magnet. The armature is movable between stable positions upon selective energization of at least one of the one or more wire coils. The solenoid further includes one or more magnetic dampers disposed along a path of movement of the armature. The one or more magnetic dampers are configured to generate a magnetic damping force in response to relative movement between the armature and at least one of the one or more magnetic dampers. The direction of the magnetic damping force is configured to be opposite to the direction of movement of the armature.

[0007] These and other aspects and advantages of the present disclosure will become apparent from the following description. The following description is set forth with reference to the accompanying drawings, which form a part hereof, and in which there are shown, for purposes of illustration, preferred configurations of the present disclosure. However, these configurations do not necessarily represent the full scope of the present disclosure, and reference should be made to the claims and this specification in interpreting the scope of the present disclosure.

[0008] The present invention will be better understood, and further aspects and advantages thereof will become apparent, by consideration of the following detailed description, which refers to the following drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a conventional multistable solenoid according to one aspect of the present disclosure. [Figure 2] 2 is a schematic diagram of a portion of the multistable solenoid of FIG. 1, with a graph showing force as a function of stroke for the solenoid of the multistable solenoid when no current is applied to the solenoid. [Figure 3] 2 is a schematic diagram of a portion of the multistable solenoid of FIG. 1, with graphs showing force as a function of stroke for a given coil configuration at various firing conditions. [Figure 4]2 shows force as a function of stroke for a given firing state of the multistable solenoid of FIG. 1. [Figure 5] 1 is a schematic diagram of a multistable solenoid including a magnetic damping component according to one aspect of the present disclosure. [Figure 6] 10 is a graph showing magnetic damping force as a function of stroke with and without a magnetic damping component for various armature speeds. [Figure 7] 7 is a graph showing armature position as a function of time for the solenoid configuration of FIG. 6 with and without a damping component. DETAILED DESCRIPTION OF THE INVENTION

[0010] Before describing aspects of the present disclosure in detail, it is to be understood that the present disclosure is not limited in its application to the details of construction and arrangement of parts set forth in the following description or illustrated in the accompanying drawings. The present disclosure is capable of other forms and of being practiced or carried out in various ways. It is also to be understood that the phraseology and terminology used herein are for the purpose of description and not of limitation. The terms "including," "comprising," or "having" and variations thereof used herein are meant to encompass the previously listed elements, equivalents thereof, and additional elements. Unless otherwise expressly stated or limited, the terms "mounted," "connected," "supported," "coupled," and variations thereof are used broadly and encompass both direct and indirect mounting, connecting, supporting, and coupling. Furthermore, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0011] The following description is presented to enable those skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be apparent to those skilled in the art, and the generic principles described herein may be applied to other embodiments and applications without departing from the scope of the invention. Thus, the embodiments of the invention are not intended to be limited to the embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description should be understood with reference to the drawings, in which like elements in different drawings are designated by like reference numerals. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the embodiments of the invention. Those skilled in the art will recognize that the examples shown herein have many useful alternatives, within the scope of the embodiments of the invention.

[0012] The use of the term "axial" and variations thereof herein refers to a direction generally extending along an axis of symmetry, central axis, or elongation of a particular part or system. For example, an axially extending structure of a part may generally extend along a direction parallel to the axis of symmetry or elongation of the part. Similarly, the use of the term "radial" and variations thereof herein refers to a direction generally perpendicular to the corresponding axial direction. For example, a radially extending structure of a part may generally extend at least partially along a direction perpendicular to the longitudinal axis or central axis of the part. The use of the term "circumferential" and variations thereof herein refers to a direction generally extending around the periphery or edge of an object, or around an axis of symmetry, central axis, or elongation of a particular part or system.

[0013] Typically, a multistable solenoid may include an armature that is movable between one or more stable positions. For example, a multistable solenoid may define two or more stable positions for the armature. Selective movement of the armature between the stable positions (e.g., positions where the armature remains when the wire coil is not energized (also referred to as deactivated)) can facilitate engagement and disengagement of the armature with one or more end positions. For example, the armature may be movable between two end positions and a central position (i.e., a tristable solenoid having three stable positions).

[0014] Conventional multistable solenoids often suffer from overshoot when the armature moves from an end position to a central magnetic detent position. That is, the armature can overshoot and displace past the central position, or even displace past the desired detent position. This overshoot can result in insufficient operation or even render the solenoid inoperable in a given application. In some non-limiting examples, magnetic damping components may be used to slow the armature and / or reduce the impact force of the armature as it reaches an end position.

[0015] The present disclosure provides systems and methods for a multistable solenoid configured to reduce or control the amount of overshoot when moving to a detent position. In some aspects, the present disclosure provides a ring solenoid including one or more magnetic damping components that prevent or inhibit the armature from moving past the detent as the armature moves to the detent position. The magnetic damping components may have a ring shape and be positioned along the path of armature movement. This can, for example, prevent the armature from overshooting past the detent position and engaging an undesired position during operation.

[0016] 1 illustrates a non-limiting example of a conventional multistable solenoid 100. In some non-limiting examples, the multistable solenoid 100 has a ring shape (i.e., extends circumferentially around a central axis 108).

[0017] In the illustrated non-limiting example, the multistable solenoid 100 may include a housing 116. In some non-limiting examples, the housing 116 may be fabricated from a ferromagnetic material. Typically, the multistable solenoid 100 may include a wire coil that selectively generates an electromagnetic force when an electric current is applied thereto. In some non-limiting examples, the multistable solenoid 100 may include a first wire coil 118, a second wire coil 120, a third wire coil 122, and an armature 124. In some non-limiting examples, the first wire coil 118, the second wire coil 120, and the third wire coil 122 may be formed from a single wire coil separated into multiple coil bays that define the first wire coil 118, the second wire coil 120, and the third wire coil 122. In some non-limiting examples, the first wire coil 118, the second wire coil 120, and the third wire coil 122 may be separate individual wire coils. In either case, the first wire coil 118, the second wire coil 120, and the third wire coil 122 may be disposed within the housing 116 and axially separated (i.e., spaced apart in a direction along the central axis 108), with the second wire coil 120 axially disposed between the first wire coil 118 and the third wire coil 122. In some non-limiting examples, the multistable solenoid may include fewer or more than three wire coils or wire coil bays.

[0018] The armature 124 may include a permanent magnet 126 disposed at least partially within the armature 124. In some non-limiting examples, the armature 124 may be comprised of one or more ferromagnetic components in addition to the permanent magnet 126. The armature 124 may be disposed within the housing 116 such that a radial air gap exists between the radial ends of the housing 116 and the ring armature 124 (i.e., the radial air gap is defined between the outer diameter of the armature 124 and the inner diameter of the housing 116). In the illustrated non-limiting example, the permanent magnet 126 may be axially magnetized, i.e., disposed such that the north and south poles of the permanent magnet 126 are aligned along or parallel to the central axis 108.

[0019] 2 , in the illustrated non-limiting example, the armature 124 is movable axially along the shaft 114 between three different stable positions upon selective activation of one or more of the first wire coil 118, the second wire coil 120, and the third wire coil 122. For example, the armature 124 may be movable between a first end position 128, a central magnetic detent position 130, and a second end position 132. The central detent position 130 may be axially disposed between the first end position 128 and the second end position 132. In some non-limiting examples, the multistable solenoid 100 may define two or more (e.g., two, four, five, six, etc.) stable positions for the armature 124.

[0020] As shown in the graph of FIG. 2, magnetic components within the multistable solenoid 100 (e.g., housing 116) may generate a variable force on the armature 124 due to magnetic interaction between the permanent magnet 126 and these magnetic components. The passive force (passive force) versus stroke curve shown in FIG. 2 illustrates the amount of force acting on the armature 124 as a function of position between a first end position 128 and a second end position 132 when the first wire coil 118, the second wire coil 120, and the third wire coil 122 are all deactivated. In the graph of FIG. 2, a positive force is acting to move the armature 124 to the right (in the plane of the page of FIG. 2). For example, the first end position 128 may be 4 millimeters negative on the x-axis of FIG. 2, the center detent position 130 may be at the origin of FIG. 2, and the second end position 132 may be 4 millimeters positive on the x-axis of FIG. 2. In the illustrated non-limiting example, a negative force (i.e., a force biasing the armature 124 to the left in the plane of the page in FIG. 2 ) acts on the armature 124 when the armature 124 is in the first end position 128, and a positive force greater than this original static force is required to move the ring armature 124 toward the center detent position 130.

[0021] Various combinations of the first wire coil 118, the second wire coil 120, and the third wire coil 122 may be selectively activated (i.e., have current flow through them in a desired direction) to smoothly move the armature 124 along a path between the first end position 128 and the second end position 132. For example, one, two, or all of the first wire coil 118, the second wire coil 120, and the third wire coil 122 may be activated at different times to provide a predetermined force in a desired direction on the armature 124 to move the armature 124 to one of the first end position 128, the center detent position 130, and the second end position 132.

[0022] 3 shows two non-limiting examples of force-stroke curves for two firing conditions (the conditions moving the armature 124 between two positions) for a given configuration of the first wire coil 118, the second wire coil 120, and the third wire coil 122. The configuration of the first wire coil 118, the second wire coil 120, and the third wire coil 122 and the currents applied thereto can change the shape of the force-stroke curves and their position on the y-axis.

[0023] In the illustrated non-limiting example, curve 134 (fire ON) is for a configuration that fires from the center detent position 130 to the second end position 132. As shown in FIG. 3, the generated force is always positive, indicating that the armature 124 is biased toward the second end position 132. Curve 136 (fire OFF) is for a configuration that fires from the second end position 132 to the center detent position 130. As shown in FIG. 3, the generated force is always negative all the way to the center detent position 130. The force-stroke characteristics in the fired state from either the first end position 128 or the second end position 132 to the center detent position 130 can result in undesirable overshoot (i.e., the armature moving past the desired position 130).

[0024] Typically, the motion of the ring armature 124 is governed by the conservation of energy. For example, as shown for curve 136 in Figure 4, the amount of work done on the armature 124 in accelerating from the second end position 132 to the central detent position 130 is significantly greater than the work done on the armature 124 in decelerating. Thus, according to the laws of physics, upon reaching the central detent position 130, the armature 124 will have enough momentum to move past the central detent position 130, possibly moving unnecessarily to the next stable position.

[0025] 5 illustrates one non-limiting example of a multi-stable solenoid 100 designed to reduce or substantially prevent overshoot of the armature 124 when firing from one of the first end position 128 and the second end position 132 to the central detent position 130. Typically, the multi-stable solenoid 100 may include one or more magnetic dampers 138 positioned along the path of travel of the armature 124. In the illustrated non-limiting example, the multi-stable solenoid 100 may include a first damping ring 140, a second damping ring 142, and a third damping ring 144. The first damping ring 140, the second damping ring 142, and the third damping ring 144 may be at least partially disposed within the housing 116. In the illustrated non-limiting example, the first damping ring 140, the second damping ring 142, and the third damping ring 144 may be disposed at an end of the housing 116 radially adjacent to the armature 124, and the housing 116 may include radially extending arms or fingers 146 that radially separate the first damping ring 140, the second damping ring 142, and the third damping ring 144. The first wire coil 118 may be surrounded by the housing 116 and the first damping ring 140, the second wire coil 120 may be surrounded by the housing 116 and the second damping ring 142, and the third wire coil 122 may be surrounded by the housing 116 and the third damping ring 144.

[0026] In some non-limiting examples, the first damping ring 140, the second damping ring 142, and the third damping ring 144 may be fabricated from an electrically conductive, non-ferromagnetic material. In some non-limiting examples, the first damping ring 140, the second damping ring 142, and the third damping ring 144 may be circumferentially conductive to form a closed conductive path (e.g., electrically conductive in a closed path extending circumferentially around the central axis 108).

[0027] Typically, a speed- or velocity-dependent magnetic damping force is generated on the ring armature 124 as it moves between the first end position 128, the central detent position 130, and the second end position 132. As the armature 124 and permanent magnet 126 move between stable positions, a magnetic field fluctuation is generated on the one or more magnetic dampers 138. This magnetic field fluctuation generates induced currents within the one or more magnetic dampers 138, creating opposing magnetic damping forces. The addition of the first damping ring 140, the second damping ring 142, and the third damping ring 144 along the path of movement of the armature 124 increases the magnetic damping force generated on the armature 124 (compared to a configuration without the damping rings), and the magnitude and direction of the damping force can reduce or substantially prevent overshooting of the ring armature 124 when it is launched into the central magnetic detent position 130. Additionally, the magnitude and direction of the damping force provided by the combined effect of the first damping ring 140, the second damping ring 142, and the third damping ring 144 can slow down or reduce the impact force as the armature 124 moves to the first end position 128 or the second end position 132.

[0028] As shown in FIG. 6 , the first damping ring 140, the second damping ring 142, and the third damping ring 144 can be used to significantly modify the magnetic damping force characteristics of the multistable solenoid 100. For example, the first damping ring 140, the second damping ring 142, and the third damping ring 144 can modify the damping force to a generally parabolic shape for a given launch condition. For example, when launching from the first end position 128 to the center detent position 130 (i.e., curve 148), the magnetic damping force may initially increase (in absolute value) and then decrease as the ring armature 124 reaches the center detent position 130. As shown in FIG. 6 , the damping force of curve 148 is negative, corresponding to acting in a right-to-left axial direction. As the armature 124 moves from the first end position 128 to the center detent position 130, the armature 124 is displaced axially from left to right. As such, the damping force generated by the one or more damping rings 138 acts in a direction opposite to the direction of movement of the armature 124 .

[0029] Similarly, when firing from the second end position 132 to the central detent position 130 (i.e., curve 150), the magnetic damping force may initially increase (in absolute value) and then decrease as the ring armature 124 reaches the central detent position 130. As shown in FIG. 6 , the damping force in curve 150 is positive, corresponding to acting in an axial direction from left to right. As the armature 124 moves from the second end position 132 to the central detent position 130, the armature 124 is displaced axially from right to left. Again, the damping force generated by the one or more damping rings 138 acts in a direction opposite to the direction of movement of the armature 124. In this manner, for example, magnetic damping forces generated by the first damping ring 140, the second damping ring 142, and the third damping ring 144 may act to limit the momentum of the armature 124 as the armature 124 moves from one of the first end position 128 and the second end position 132 to the center detent position 130. This limits or substantially prevents the armature 124 from overshooting excessively past the center of the magnetic detent position 130, ensuring effective and accurate operation of the multi-stable solenoid 100.

[0030] As described herein, the damping force generated by the one or more damping rings 138 may result from magnetic field variations caused by movement of the armature 124 relative to the one or more damping rings 138. Thus, the generation of the damping force may be caused by movement of the armature 124 relative to at least one of the first damping ring 140, the second damping ring 142, and the third damping ring 144, as reflected in FIG. 6 . For example, the magnitude of the damping force in curve 148 may be zero at the first end position 128, and the damping force may increase (in absolute value) as the armature 124 begins to move toward the center detent position 130. Similarly, the magnitude of the damping force in curve 150 may be zero at the second end position 132, and the damping force may increase (in absolute value) as the armature 124 begins to move toward the center detent position 130. In this manner, the magnitude of the damping force generated by the one or more damping rings 138 may be speed or velocity dependent. That is, when the armature 124 is not moving (e.g., velocity is zero), no damping force is generated. When the armature 124 begins to move (i.e., the absolute value of the velocity becomes greater than zero), one or more damping rings 138 may generate a damping force in a direction opposite to the direction of movement of the armature 124, with a magnitude related to the absolute value of the velocity of the armature 124.

[0031] Figure 7 illustrates a further benefit of one or more magnetic dampers 138. As shown in Figure 7, without one or more magnetic dampers 138 (curve 149), there is more overshoot (i.e., movement past the center detent position 130) and it takes longer for the ring armature 124 to plateau at the center detent position 130. In other words, the inclusion of one or more magnetic dampers 138 (curve 151) reduces the overshoot past the center detent position 130 and plateaus at the center detent position 130 more quickly.

[0032] In addition to the desirable effect on armature 124 overshoot, the use of first damping ring 140, second damping ring 142, and third damping ring 144 provides a solution that is largely independent of magnetic saturation of the housing (i.e., the damping force is not affected by magnetic saturation). Furthermore, no modifications to other ferromagnetic components of multistable solenoid 100 are required to accommodate first damping ring 140, second damping ring 142, and third damping ring 144. For example, housing 116 and other magnetic components within multistable solenoid 100 do not need to change shape or size, and the static magnetic field characteristics remain unchanged. Therefore, the static magnetic field requirements of multistable solenoid 100 for a given application can be decoupled from the mechanical requirements, significantly reducing the complexity of the design process. Furthermore, the use of first damping ring 140, second damping ring 142, and third damping ring 144 allows the efficiency of the magnetic materials in the design to remain unchanged.

[0033] While embodiments have been described herein for clarity and consistency, it will be understood that these embodiments can be combined or separated in various ways without departing from the invention. For example, it will be understood that all preferred features described herein are applicable to all aspects described herein.

[0034] Thus, while the invention has been described in connection with particular embodiments and examples, the invention is not so limited, and numerous other embodiments, examples, uses, and departures from the embodiments, examples, and uses are within the scope of the appended claims. Each patent document and publication cited herein is incorporated by reference in its entirety as if it were individually incorporated by reference herein.

[0035] Various features and advantages of the invention are set forth in the following claims.

Claims

1. A wire coil; an armature including a permanent magnet; one or more magnetic dampers positioned along a path of travel of the armature; Equipped with the armature is movable between two or more stable positions upon selective energization of the wire coil; the one or more magnetic dampers are configured to generate a magnetic damping force in a direction opposite to a direction of movement of the armature to limit overshoot when the armature moves to one of the two or more stable positions; A solenoid, wherein the one or more magnetic dampers are electrically conductive non-ferromagnetic materials.

2. The solenoid of claim 1 further comprising a housing.

3. The solenoid of claim 2 , wherein the wire coil is disposed within the housing.

4. 4. The solenoid of claim 3, wherein the wire coil comprises a single continuous coil divided into one or more wire coil bays axially separated from one another.

5. The solenoid of claim 4 , wherein the housing includes one or more fingers axially separating the one or more wire coil bays.

6. The solenoid of claim 3 , wherein the wire coil comprises one or more separate wire coils axially separated from one another.

7. The solenoid of claim 6 , wherein the housing includes one or more fingers that axially separate the one or more separate wire coils.

8. 3. The solenoid of claim 2, wherein the housing is made from a ferromagnetic material.

9. The solenoid of claim 2 , wherein the one or more magnetic dampers are at least partially disposed within the housing.

10. 2. The solenoid of claim 1, wherein the two or more stable positions include a first end position, a center detent position, and a second end position.

11. 11. The solenoid of claim 10, wherein the armature is stable in at least one of the first end position, the central detent position, and the second end position with the wire coil in an unenergized state.

12. The solenoid of claim 1 , wherein the one or more magnetic dampers are electrically conductive in a circumferential direction to form a closed conductive path.

13. 10. The solenoid of claim 1, wherein the armature is comprised of one or more ferromagnetic components in addition to the permanent magnet.

14. The magnitude of the magnetic damping force is configured to depend on the velocity of the armature.

2. The solenoid of claim 1.

15. A wire coil; an armature including a permanent magnet; two magnetic dampers; the armature is movable between two stable positions upon selective energization of the wire coil; each of the two magnetic dampers is disposed at one of the two stable positions along a path of movement of the armature; the two magnetic dampers are configured to generate a magnetic damping force in response to relative movement between the armature and at least one of the two magnetic dampers; The solenoid, wherein the magnetic damping force is directed opposite to a direction of movement of the armature, and is configured to limit overshoot when the armature moves to one of the two or more stable positions.

16. 16. The solenoid of claim 15, wherein the magnitude of the magnetic damping force is configured to depend on the velocity of the armature.

17. the two stable positions are two of a plurality of stable positions including a first end position, a central detent position, and a second end position; 16. The solenoid of claim 15, wherein the two magnetic dampers are two of a plurality of magnetic dampers.

18. 18. The solenoid of claim 17, wherein the armature is stable in at least one of the first end position, the central detent position, and the second end position with the wire coil in an unenergized state.

19. the two magnetic dampers are made of electrically conductive non-ferromagnetic materials, 16. The solenoid of claim 15, wherein the two magnetic dampers are electrically conductive in the circumferential direction to form a closed conductive path.

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