Solenoid device and method

Abstract

The solenoid includes a stator having first stator teeth and second stator teeth, and an armature having first armature teeth and second armature teeth. The armature is movable relative to the stator within a predetermined stroke. A coil is associated with one of the stator and the armature for conducting current and generating magnetic flux guided by the stator and the armature. The stator or the armature acts as the ferromagnetic core of the coil. A first air gap of a first length is formed between the first stator teeth and the first armature teeth, and a second air gap of a second length is formed between the second stator teeth and the second armature teeth. The first and second lengths are constant within a predetermined margin within a predetermined formation when the first and second armature teeth overlap with the first and second stator teeth, respectively.

Description

Technical Field

[0001] This application relates to a solenoid device that can be configured as either or both of an electromagnetic actuator and a position sensor, and a method of operating the same. Background Technology

[0002] A simple form of so-called variable-gap solenoid comprises a stator, an armature, and a coil. As used herein, the armature may also be interchangeably referred to as a plunger. An electromagnet is formed. When current is passed through the coil, the electromagnet attracts the armature towards the stator. The armature is attracted towards the stator to reduce the magnetic reluctance of the electromagnet's flux lines. As the armature moves toward the stator, the air gap length between the armature and the stator decreases. The result of a variable-length air gap is that the force exerted on the armature by the electromagnet is highly nonlinear over the entire stroke of the armature. This nonlinear force acting on the armature makes it difficult to control the armature's position, and these types of solenoids typically operate between two extreme positions. For example, when using a variable-gap solenoid to move the plunger of a solenoid valve, the plunger moves between the valve's closed and open positions. Attempting to control the plunger position to one or more intermediate positions between the closed and open positions requires expensive and bulky electronic control and position sensing devices that provide only moderate accuracy in detecting and controlling the plunger's position, velocity, and acceleration.

[0003] Traditional proportional solenoids exhibit relatively linear inductive and force characteristics. However, their restrictive geometry hinders their use in many applications. For example, proportional solenoids have an inherent end stop because the plunger rests against the stator when driven to the end of its stroke. This end stop makes it difficult to stack proportional solenoids into multiple stages to generate greater forces. Furthermore, achieving linear characteristics requires a very sensitive plunger taper design. The geometry of linear switched reluctance motors (LSRMs) results in highly nonlinear force and inductive characteristics.

[0004] Existing technologies lack the ability to improve the control and / or sensing of plunger position in actuators. This research and method provide improved actuators and / or sensors, as well as techniques for improving the control and / or sensing of plunger position in actuators. Summary of the Invention

[0005] The improved solenoid includes a stator having first stator teeth and second stator teeth, and an armature having first armature teeth and second armature teeth. The armature is movable relative to the stator within a predetermined stroke. A coil is associated with one of the stator and the armature to conduct current and generate magnetic flux guided by the stator and the armature. The stator or the armature acts as the ferromagnetic core of the coil. A first air gap of a first length is formed between the first stator teeth and the first armature teeth, and a second air gap of a second length is formed between the second stator teeth and the second armature teeth. The first and second lengths are constant within a predetermined margin when the first and second armature teeth overlap with the first and second stator teeth, respectively, during the predetermined stroke.

[0006] The armature can move linearly or translate along the axis, or the armature can rotate about the axis. In an exemplary embodiment, the first length of the first air gap and the second length of the second air gap are equal within a predetermined margin. Preferably, the widths of the first and second stator teeth are equal to the widths of the first and second armature teeth, respectively. The stator can surround the armature. Alternatively, the stator can be adjacent only to one side of the armature. In some embodiments, the stator can have a cuboid or cylindrical shape. Over a predetermined stroke, an armature guide associated with the armature can guide the armature along the longitudinal axis within a predetermined tolerance.

[0007] Each of the first and second stator teeth includes a stator tooth surface, and each of the first and second armature teeth includes an armature tooth surface, wherein each of the first and second armature teeth overlaps with the first and second stator teeth respectively when any perpendicular projection from the armature tooth surface intersects the corresponding stator tooth surface. A first position of the armature is defined as the position where the first and second stator teeth have the minimum overlap with the first and second armature teeth respectively, and a second position of the armature is defined as the position where the first and second stator teeth have the maximum overlap with the first and second armature teeth respectively. Within a predetermined stroke between the first and second positions, the force of the solenoid is constant within a first predetermined tolerance, and the inductance of the solenoid is linearly proportional to the overlap between the first and second stator teeth and the first and second armature teeth within a second predetermined tolerance. The overlap between the first and second stator teeth and the first and second armature teeth is linearly proportional to the armature position within the predetermined stroke.

[0008] In an exemplary embodiment, the solenoid further includes a third stator tooth and a fourth stator tooth associated with the stator, and a third armature tooth and a fourth armature tooth associated with the armature. A third air gap of a third length exists between the third stator tooth and the third armature tooth, and a fourth air gap of a fourth length exists between the fourth stator tooth and the fourth armature tooth. The third and fourth lengths are constant within a predetermined margin when the third and fourth armature teeth overlap with the third and fourth stator teeth, respectively, within a predetermined stroke. Preferably, the distance between the first stator tooth and the third stator tooth is greater than at least one of the widths of the first and third armature teeth. Also preferably, the distance between the first and third armature teeth is greater than at least one of the widths of the first and third stator teeth. The armature may include a connecting member connecting the first and second armature teeth to the third and fourth armature teeth, and this connecting member may be made of a non-ferromagnetic material. In an exemplary embodiment, a first magnetic flux path including the first and second air gaps and a second magnetic flux path including the third and fourth air gaps are present, wherein the first magnetic flux path and the second magnetic flux path are connected in parallel. There may also be a third magnetic flux passage including the fifth and sixth air gaps and a fourth magnetic flux passage including the seventh and eighth air gaps, wherein the first magnetic flux passage is connected in series with the third magnetic flux passage, the second magnetic flux passage is connected in series with the fourth magnetic flux passage, and the combination of the first magnetic flux passage and the third magnetic flux passage is connected in parallel with the combination of the second magnetic flux passage and the fourth magnetic flux passage.

[0009] In another exemplary embodiment, a first magnetic flux path including first and second air gaps and a second magnetic flux path including third and fourth air gaps are provided, wherein the first magnetic flux path and the second magnetic flux path are connected in series. The stator may include a first portion and a second portion, wherein the coil is a first coil associated with the first portion of the stator. A second coil associated with the second portion of the stator may also be provided. A third magnetic flux path including fifth and sixth air gaps and a fourth magnetic flux path including seventh and eighth air gaps may also be provided, wherein the third magnetic flux path and the fourth magnetic flux path are connected in parallel, and the combination of the first and second magnetic flux paths is connected in series with the combination of the third and fourth magnetic flux paths.

[0010] In yet another exemplary embodiment, the solenoid is a first solenoid, and further includes a second solenoid having the same features as the first solenoid, and a common armature having a connecting member connecting the armature of the first solenoid to the armature of the second solenoid. Adjacent plunger teeth are defined as those teeth that are adjacent to each other, selected on the one hand from the first, second, third, and fourth armature teeth of the first armature, and on the other hand from the first, second, third, and fourth armature teeth of the second armature. Preferably, the distance between adjacent plunger teeth is at least equal to the width of at least one of the adjacent plunger teeth. The first solenoid may be configured relative to the second armature such that when the coils of the first and second solenoids are energized, they apply a pulling or rotating force or torque to the common armature in opposite directions. The spatial configuration of the first armature teeth and second armature teeth of the first solenoid relative to the first stator teeth and second stator teeth of the first solenoid differs from the spatial configuration of the first armature teeth and second armature teeth of the second solenoid relative to the first stator teeth and second stator teeth of the first solenoid. More specifically, compared to the first and second armature teeth of the second solenoid extending along or about the longitudinal axis of the armature relative to the first and second stator teeth of the second solenoid, respectively, the first and second armature teeth of the first solenoid extend in opposite directions relative to the first and second stator teeth of the first solenoid. The coil of the first solenoid includes windings, and the coil of the second solenoid also includes windings, wherein the coils of the first and second solenoids may include an equal number of corresponding windings such that when the coils of the first and second solenoids are energized with the same current, the force or torque they apply has a common magnitude within tolerance. The coil of the first solenoid can be energized independently and separately from the coil of the second solenoid. The coils of the first and second solenoids are electrically connected.

[0011] The improved driver is configured to generate a primary control signal and a ripple signal, and includes an adder to superimpose the ripple signal onto the primary control signal, thereby providing an output signal (or drive signal) supplied to the solenoid to actuate it. The primary control signal may include a bias voltage and may be a DC voltage. The frequency of the ripple signal is preferably higher than a predetermined value so that aliasing does not occur between the ripple signal and the primary control signal or the back electromotive force generated by applying the output signal to the solenoid.

[0012] The improved electronic controller is programmed to measure the voltage across the coil; measure the current through the coil; estimate the position of the armature by employing an inductance-based algorithm that provides a first independent position estimate and a flux linkage-based algorithm or a back electromotive force (BEMF)-based algorithm that provides a second independent position estimate; and determine a combined position estimate of the armature by employing a meta-estimation algorithm that combines the first and second independent positions to provide a combined position estimate.

[0013] The split-core includes a split-core armature having a first core, a second core, and a connecting member connecting the first core and the second core. The connecting member may be made of a non-ferromagnetic material. The split-core armature is configured to move along a longitudinal axis. A first coreless electromagnet includes a first coil extending about the longitudinal axis. The first core and the coil form a first actuator, wherein when the first coil is energized, the first core has a north pole and a south pole. A second coreless electromagnet includes a second coil extending about the longitudinal axis. The second core and the second coil form a second actuator, wherein when the second coil is energized, the second core has a north pole and a south pole. A first air gap and a second air gap are present. The first and second coils are configured in one of the following ways: 1) a first air gap extends between the north and south poles of the first iron core, and a second air gap extends between the north and south poles of the second iron core, such that when the first and second coils are energized, magnetic flux leaving the north pole of the first iron core enters the south pole of the first iron core, and magnetic flux leaving the north pole of the second iron core enters the south pole of the second iron core; and 2) a first air gap extends between the north pole of the first iron core and the south pole of the second iron core, and a second air gap extends between the north pole of the second iron core and the south pole of the first iron core, such that when the first and second coils are energized, magnetic flux leaving the north pole of the first iron core enters the south pole of the second iron core, and magnetic flux leaving the north pole of the second iron core enters the south pole of the first iron core. The first and second coils are spaced apart along the longitudinal axis. A first iron core is configured relative to a first coil, and a second iron core is configured relative to a second coil, such that when the first and second coils are energized, a first actuator applies a first force that pulls the split iron core armature in a direction opposite to a second force applied to the split iron core armature by a second actuator. The first coil has a first winding, and the second coil has a second winding, wherein the first number of turns of the first winding is equal to the second number of turns of the second winding. The first coil is electrically connected to the second coil.

[0014] A method for estimating the armature position in a solenoid including a coil includes: measuring a voltage across the coil of the solenoid and providing a measured voltage signal; measuring a current through the coil of the solenoid and providing a measured current signal; determining a first position estimate of the armature using a first position estimation algorithm, the first position estimation algorithm taking the measured voltage signal and the measured current signal as inputs; determining a second position estimate of the armature using a second position estimation algorithm, the second position estimation algorithm taking the measured voltage signal and the measured current signal as inputs; and determining a third position estimate of the armature using a meta-estimation algorithm, the meta-estimation algorithm taking the first position estimate and the second position estimate as inputs. The first position estimation algorithm may be an inductance-based algorithm, and the second position estimation algorithm may be a flux linkage-based algorithm or a BEMF-based algorithm. The meta-estimation algorithm may include a complementary filter or a Kalman filter.

[0015] The first position estimate can be determined in the first position estimation algorithm according to the following equation:

[0016]

[0017] in:

[0018] U rms滤波 It is the root mean square value of the voltage signal obtained after the measured voltage signal is bandpass filtered;

[0019] I rms滤波 It is the root mean square value of the current signal obtained after the measured current signal is bandpass filtered;

[0020] R is the resistance of the coil;

[0021] f is the ripple frequency of the voltage signal being measured;

[0022] C1 is a constant representing the slope of the graph showing the relationship between the solenoid's inductance and the armature position; and

[0023] C2 is a constant representing the y-intercept of the graph showing the relationship between the solenoid's inductance and the armature's position.

[0024] The second position estimate can be determined in the second position estimation algorithm according to the following equation:

[0025]

[0026] in:

[0027] U is the voltage signal at which the voltage is broken;

[0028] I is the measured current signal;

[0029] It is the derivative of the measured current signal;

[0030] R is the resistance of the coil;

[0031] C1 is a constant representing the slope of the graph showing the relationship between the solenoid's inductance and the armature position; and

[0032] C2 is a constant representing the y-intercept of the graph showing the relationship between the solenoid's inductance and the armature's position.

[0033] The second position estimate can be determined in the second position estimation algorithm according to the following equation:

[0034]

[0035] in:

[0036] U is the voltage signal being measured;

[0037] I is the measured current signal;

[0038] R is the resistance of the coil;

[0039] C1 is a constant representing the slope of the graph showing the relationship between the solenoid's inductance and the armature position; and

[0040] C2 is a constant representing the y-intercept of the graph showing the relationship between the solenoid's inductance and the armature's position.

[0041] The solenoid includes a first actuator and a second actuator that apply forces to the armature in opposite directions, wherein a coil and a first position estimate, a second position estimate, and a third position estimate correspond to the first actuator, and wherein the second actuator has a second coil. The method may further include: determining fourth, fifth, and sixth position estimates of the armature for the second actuator in a manner that determines the first, second, and third position estimates, respectively; and determining differential position estimates according to the following formula:

[0042]

[0043] in:

[0044] y1 is one of the first position estimate, the second position estimate, or the third position estimate;

[0045] y2 is one of the fourth, fifth, or sixth position estimates; and

[0046] S is the total stroke length of the armature of the solenoid. Attached Figure Description

[0047] Figure 1 This is a schematic cross-sectional view of the solenoid according to an embodiment.

[0048] Figure 2 This is a cross-sectional view of a solenoid employing a parallel stator air gap according to another embodiment.

[0049] Figure 3 This is a cross-sectional view of a solenoid employing a series stator air gap according to another embodiment.

[0050] Figure 4 This is a cross-sectional view of a solenoid employing an asymmetric stator according to another embodiment.

[0051] Figure 5 This is a cross-sectional view of a solenoid employing a coil associated with an armature, according to another embodiment.

[0052] Figure 6 yes Figure 1 A graphical view of the force characteristics of the solenoid relative to the stator-plunger tooth overlap. This graph illustrates the quasi-constant force generated near the midpoint of its total stroke. The force characteristics are shown relative to the amount of overlap between the plunger and solenoid teeth.

[0053] Figure 7 yes Figure 1 A graph showing the inductance of a solenoid relative to the stator-plunger tooth overlap characteristic. This graph illustrates the quasi-linear change in inductance of the solenoid over its total stroke. The inductance characteristics are shown relative to the amount of overlap between the plunger and stator teeth.

[0054] Figure 8 This is a cross-sectional view of a solenoid comprising two stacked solenoids in the form of two stators according to another embodiment, the two stators being connected by a common plunger and capable of pulling the common plunger in a single direction.

[0055] Figure 9 This is a cross-sectional view of a solenoid comprising a stack of a first actuator and a second actuator in the form of two stators, according to another embodiment. The two stators are connected by a plunger shared by the first and second actuators. The solenoid can be used as a bidirectional actuator, wherein the plunger can be pulled in two directions by selectively and separately actuating the first and second actuators individually and separately. Alternatively, the solenoid can be used as a position sensor, wherein the first and second actuators can be actuated to obtain differential position measurements without substantially affecting the position of the plunger.

[0056] Figure 10aThis is a side view of a solenoid according to another embodiment, including a first rotary actuator and a second rotary actuator connected via a rotor shared by the first and second rotary actuators. The solenoid can be used as a bidirectional rotary actuator, wherein the rotor can be rotated in two directions by selectively and separately actuating the first and second solenoids individually and separately. Alternatively, the solenoid can be used as a position sensor, wherein the first and second rotary actuators can be actuated to obtain differential position measurements without substantially affecting the position of the rotor.

[0057] Figure 10b It is a section taken along line 10b-10b'. Figure 10a A cross-sectional view of the first rotary actuator of the solenoid.

[0058] Figure 10c It is a section taken along line 10c-10c'. Figure 10a A cross-sectional view of the second rotary actuator of the solenoid.

[0059] Figure 11a This is a schematic diagram of a linear variable differential transformer in the prior art.

[0060] Figure 11b This is a schematic diagram of a differential variable reluctance transducer in the prior art.

[0061] Figure 11c It means Figure 9 Figure 10 and Figure 16 A schematic diagram of a solenoid. (And respectively) Figure 11a and Figure 11b Compared to LVDT and DVRT, this solenoid employs a unique split core design, which allows for... Figure 9 Figure 10 and Figure 16 It has a unique position estimation algorithm that is exclusive to solenoids.

[0062] Figure 12 yes Figure 9 The force characteristics of the first and second actuators on the piston displacement and when Figure 9 A graph showing the net force versus plunger displacement characteristics when the solenoid is used as a position sensor. This graph illustrates that the net force acting on the plunger of the position sensor is negligible when the first and second actuators are substantially overlapped.

[0063] Figure 13 yes Figure 9 The inductance of the first and second actuators affects the plunger displacement characteristics and when Figure 9 A graph showing the net inductance versus plunger displacement characteristics when the solenoid is used as a position sensor. This graph illustrates that the net force on the position sensor plunger is negligible when the first and second actuators are substantially overlapped. Similar graphs exist for the solenoids in Figures 10 and 16.

[0064] Figure 14 It is used to make Figure 1 , 2 Schematic diagrams and graphs illustrating the output characteristics of drivers for solenoids 1, 2, 3, 4, 5, 8, 9, 10a, and 16, which operate simultaneously as actuators and sensors. The driver superimposes a ripple signal onto a primary control signal (also known as a bias signal) to generate the current characteristics used to operate the solenoid.

[0065] Figure 15 This is a flowchart of position estimation algorithms, including inductance-based algorithms and magnetic flux-based or BEMF-based algorithms. Independent estimates from inductance-based and magnetic flux-based or BEMF-based algorithms can be used independently, alone, or in combination with meta-estimation algorithms (also known as sensor fusion techniques).

[0066] Figure 16 This is a schematic diagram of a position sensor employing a split-core plunger and a coreless electromagnet in the form of a coil for each core of the split-core plunger. Each electromagnet is configured without a ferromagnetic core to guide the magnetic flux. Each core of the split-core plunger overlaps with its respective coil throughout its entire stroke. Detailed Implementation

[0067] This invention relates to a novel solenoid, which is interchangeably referred to herein as a constant air gap solenoid (CAS). In one embodiment, the CAS can operate as an electromagnetic actuator, and can also be used to simultaneously measure the position of the armature in the solenoid. As used herein, an armature refers to one or more cores of a moving solenoid. More specifically, when linear motion of the armature is employed, the armature refers to the plunger, and when rotational motion of the armature is employed, the armature refers to the rotor. The term armature is used interchangeably herein with plunger and rotor. Through careful design of the armature and stator, the CAS can exhibit significantly improved linear operation (in both linear and rotational motion solenoids) compared to previous solenoids, including proportional inductance changes relative to position and a fundamentally constant force against the supply current over its limited stroke length. The linear inductance and force characteristics of the CAS provide the basis for not only driving armature movement but also sensing its position.

[0068] Unlike other electromagnetic actuators, different position detection algorithms can be used to generate two simultaneous position estimates for the armature of the CAS. These position estimates can then be used for position feedback to control the movement and position of the armature. To generate simultaneous position estimates, only information from a single voltage and current sensor is used. The presence of the voltage and current sensor allows the CAS to employ a variety of position sensing algorithms already published for LSRMs, reluctance motors, conventional solenoids, differential variable reluctance sensors (DVRTs), linear variable differential transformers (LVDTs), and other inductance-based sensors. However, the CAS's unique linear behavior allows it to employ additional novel methods to estimate position.

[0069] Now refer to the attached diagram, and first refer to... Figure 1The image illustrates a solenoid 10, also referred to as CAS, according to one embodiment. The solenoid 10 includes a coil 20, a stator 30, and a plunger 40. The coil 20 includes wires forming a winding for conducting current. The stator 30 includes teeth 50 (two in this embodiment), and the plunger 40 includes teeth 60 (also two in this embodiment). Each stator tooth 50 is associated with a corresponding plunger tooth 60, forming a stator-plunger-tooth pair. Both the stator 30 and the plunger 40 are made of a ferromagnetic material to guide and direct the magnetic flux generated when the coil 20 is energized. As used herein, the term "magnetic flux" is used interchangeably with the term "flux." An air gap 70 exists between each stator tooth 50 and its corresponding plunger tooth 60. The length 80 of each air gap 70 remains substantially constant, and preferably constant, as the plunger tooth 60 moves relative to its corresponding stator tooth 50. In an exemplary embodiment, the stator teeth 50 and plunger teeth 60 remain overlapping throughout their relative motion with respect to each other, and in this case, the maximum translation of the plunger 40 is defined by the dimensions of the stator teeth 50 and the plunger teeth 60. This overlap constraint can be satisfied by additional end stops or position control. Unlike a scaled-face solenoid, the exemplary embodiment does not include any inherent end stops. Each stator tooth 50 has a stator tooth surface 50f, and each plunger tooth 60 has a plunger tooth surface 60f. In the exemplary embodiment, surfaces 50f and 60f are flat and parallel. As used herein, a plunger tooth 60 is defined to overlap with its corresponding stator tooth 50 when at least one vertical projection emanating from the plunger tooth surface 60f intersects any portion of the stator tooth surface 50f (and similarly to all other enumerated plunger teeth and stator teeth). Similarly, a plunger tooth 60 does not overlap with a stator tooth 50 when all vertical projections emanating from the plunger tooth surface 60f do not intersect any portion of the stator tooth surface 50f. For example, due to inherent tolerances in manufacturing, it is difficult to manufacture solenoid 10 and all solenoids disclosed herein so that surfaces 50f and 60f are perfectly parallel. In this respect, the length 80 of the air gap 70 is typically equal to the shortest length between the overlapping portions of stator tooth surface 50f and plunger tooth surface 60f.

[0070] When current is supplied to coil 20, a force is applied to plunger 40 to pull it into the position where plunger teeth 60 and stator teeth 50 have maximum overlap (defined as the magnetic reluctance of the magnetic circuit defining stator 30, plunger 40, and air gap 70 is at or near its minimum). The magnitude of the supplied current determines the force applied to plunger 40. The polarity of the current has no effect on the direction of the applied force. An external force must be provided by means of a device such as, but not limited to, a mechanical spring, to return plunger 40 to a position with less overlap compared to the maximum overlap position.

[0071] In an exemplary embodiment, Figure 1The solenoid 10 shown has a cuboid shape. The stator 30 and plunger 40 are each preferably made of ferromagnetic laminations or sintered ferromagnetic powder cores. Alternatively, one or both of the stator 30 and plunger 40 may be made of solid ferromagnetic material, but in this case, it may be necessary to mitigate higher-order magnetic effects, such as eddy currents.

[0072] like Figure 1 The plunger 40 shown illustrates an exemplary embodiment of the plunger teeth 60, which are positioned between the stator teeth 50 such that the lengths 80 of the air gaps 70 on both sides of the plunger are equal. When the coil 20 is energized, this position of the plunger 40 results in a net horizontal force acting on the plunger (relative to...). Figure 1 The orientation of the air gap 70 on both sides of the plunger 40 is zero. When the lengths 80 of the air gaps 70 on both sides of the plunger 40 are not equal, when the coil 20 is energized, the plunger 40 is subjected to a horizontal force that pulls the plunger 40 toward one of the stator teeth 50 so that the difference between the lengths 80 is reduced to zero. Manufacturing a solenoid 10 in which the air gaps 70 have exactly and precisely equal lengths 80 is challenging and costly. Therefore, the exemplary embodiment employs an external plunger guide 440 to restrict the movement of the plunger 40 to its intended axis of motion 90, although the plunger guide 440 is not necessary. Alternatively, in other embodiments (here and elsewhere), it is also possible for the stator 30 to move instead of the plunger 40 (although by definition the stator is usually fixed in place while the plunger moves), in which case the stator 30 may or may not move with the coil 20, and an external stator guide (not shown) may be used.

[0073] The required peak plunger force and the desired linearity of solenoid operation influence the selection of the length 80 of each air gap 70. The maximum longitudinal plunger force (along axis 90) is proportional to the length 80 of the air gap 70, because the larger the air gap 70, the greater the maximum longitudinal force that can be applied to the plunger 40 before magnetic circuit saturation. As the length 80 of the air gap 70 increases, the linearity of solenoid operation decreases because the flux edges around the stator teeth 50 and plunger teeth 60 become more pronounced. Therefore, the length 80 of the air gap 70 is application-specific in terms of force, size, and linearity requirements. Typically, the difference between the lengths 80 of the air gaps 70 on both sides of the plunger 40 is reduced and preferably minimized, but the difference is fundamentally limited by the acceptable deflection of the plunger 40 caused by the horizontal force experienced when the coil 20 is energized.

[0074] Now for reference Figure 2This diagram illustrates a solenoid 12 according to another embodiment of a constant air gap solenoid, wherein components identical to those in the previous embodiments and all other embodiments herein have the same reference numerals and may not be described in detail again, with only differences discussed. In addition to stator teeth 50, the stator 32 includes a set of parallel stator teeth 52, and in addition to plunger teeth 60, the plunger 42 includes a set of corresponding parallel plunger teeth 62. An air gap 72 extends between the corresponding stator teeth 52 and plunger teeth 62. A first flux path is formed by the stator teeth 50, air gap 70, and plunger teeth 60, and is connected in parallel with a second flux path formed by the stator teeth 52, air gap 72, and plunger teeth 62. The parallel air gaps 70 and 72 split the magnetic flux within the stator 32 between the first and second flux paths. Figure 1 Compared to the solenoid 10 shown, this change in the magnetic flux path produces different force and inductive behavior. Component 100 connects the plunger teeth 60 and 62 and can be made of a single piece of material shared with the plunger teeth, or from a separate piece of material, and can be a ferromagnetic or non-magnetic material.

[0075] Now for reference Figure 3 A solenoid 13 according to another embodiment of a constant air gap solenoid is shown, which is similar to Figure 1 and Figure 2 In one embodiment, a first magnetic flux path (defined by stator teeth 50, air gap 70, and plunger teeth 60) is connected in series with a second magnetic flux path (defined by stator teeth 52, air gap 72, and plunger teeth 62). The stator 33 is divided into two parts, 33a and 33b, each having corresponding coils 20a and 20b. Coils 20a and 20b are connected in series and generate constructive magnetomotive forces; therefore, coils 20a and 20b can be considered equivalent to... Figure 1 and Figure 2 A single coil 20 is shown. Alternatively, only one of coils 20a or 20b may be used. When there is an imbalance between coils 20a and 20b, such as different numbers of turns, the connecting member 100 is made of a non-magnetic material to ensure that magnetic flux passes through both stator portions 33a and 33b, and not through the connecting member 100. Figure 1 and Figure 2 Compared to the solenoids 10 and 12 shown, the air gaps 70 and 72 when connected in series cause solenoid 13 to exhibit different force and inductance characteristics.

[0076] Now for reference Figure 4The diagram illustrates a solenoid 14 according to another embodiment of a constant air gap solenoid, wherein the stator 34 and the plunger 44 are in an asymmetrical spatial relationship, such that the plunger 44 is not surrounded by the stator 34, but rather the stator 34 is adjacent to only one side of the plunger 44. The geometry of solenoid 14 is more compact than that of solenoids 10, 12, and 13. However, the geometry of solenoid 14 generates a strong magnetic force that pulls the stator teeth 50 and the plunger teeth 60 together (i.e., causes the air gap 70 to collapse). Solenoid 14 is encapsulated such that the movement of the plunger 44 or the stator 34 is constrained to a designated axis of motion 90, thereby preferably keeping the length 80 of the air gap 70 constant.

[0077] Now for reference Figure 5 It shows that according to similar Figure 3 Another embodiment of the constant air gap solenoid 13 in the solenoid 15 is a solenoid 15, except that there is a single coil instead of a pair of coils and the coil 20 is wound around the connecting member 105 of the plunger 45. Therefore, the connecting member 105 is made of a ferromagnetic material. When the coil 20 is energized, the magnetic flux is guided through the connecting member 105 (which is different from the coil 20) before splitting between the stator portions 33a and 33b. Figure 2 and Figure 3 (Solenoids 12 and 13). The unique feature of this embodiment compared to the previous embodiments is that solenoid 15 can be made into a cuboid shape or a cylindrical shape.

[0078] The operation of solenoids 10, 12, 13, 14, and 15 will now be described in more detail. Reference is made to solenoid 13 in the following description of operation (see...). Figure 3 It should be understood that the same description applies to other solenoids 10, 12, 14, and 15, as well as other embodiments of general constant air gap solenoids. Reference Figure 6When operating as an actuator, solenoid 13 exhibits the force-tooth overlap relationship shown by characteristic 110. Position 120 indicates that the plunger tooth 60 and stator tooth 50 are in a non-overlapping position (or more precisely, at a threshold between the non-overlapping and overlapping positions), position 121 indicates that the plunger tooth 60 and stator tooth 50 are in a half-overlapping position, and position 122 indicates that the plunger tooth 60 and stator tooth 50 are in a fully overlapped position. Position 120 can also be defined as the minimum overlap between the corresponding plunger tooth 60 and stator tooth 50, and position 122 can also be defined as the maximum overlap between the corresponding plunger tooth 60 and stator tooth 50. When the plunger tooth 60 and stator tooth 50 are near half-overlap (position 121), the output force of solenoid 13 can be considered a quasi-constant. The output force is defined as the force applied to the plunger or stator when coil 20 is energized. When operated as an actuator, solenoid 13 operates well under both toothless overlap (position 120) and full tooth overlap (position 122) conditions, exhibiting constant force behavior. The constant force behavior of solenoid 13 in positions 120 and 122 means that it will generate a back electromotive force (BEMF) proportional to the velocity of plunger 42. This phenomenon provides the basis for a BEMF-based position estimation algorithm, which will be described in more detail below.

[0079] Solenoid 13 exhibits relative to Figure 7 Characteristic 115 illustrates the proportional inductance change of tooth overlap. Solenoid 13 exhibits a linear inductance change, which can be modeled as a first-order polynomial within an acceptable error margin, provided that the plunger tooth 60 and stator tooth 50 are less than a first predetermined margin of complete overlap (position 122) and more than a second predetermined margin of non-overlap (position 120). The first and second predetermined margins can be determined empirically (preferably) or analytically. This linear behavior provides the basis for position estimation algorithms described below, referred to as inductance-based, flux linkage-based, and BEMF-based algorithms. Exemplary embodiments of solenoids 10, 12, 13, 14, and 15 reduce and preferably minimize offset 130, and increase and preferably maximize the slope 135 of the inductance with respect to tooth overlap characteristic 115.

[0080] Now for reference Figure 8The diagram illustrates a solenoid 16 according to another embodiment of a constant air gap solenoid, wherein two actuators (also referred to as solenoids) similar to solenoid 13 are stacked and connected by a common plunger 46. The plunger teeth 60, 62 and stator teeth 50, 52 of the first actuator 13a and the second actuator 13b are configured such that all plunger teeth 60, 62 bear a force pulling the plunger 46 in the same direction when coils 20a, 20b are energized. The connecting member 106 of the plunger 46 between the first actuator 13a and the second actuator 13b is preferably made of a non-ferromagnetic material so that the magnetic flux circulating in the first actuator 13a does not interfere with or mix with the magnetic flux circulating in the second actuator 13b, and vice versa. This configuration allows the output force of the solenoid 16 to increase with each stack of actuators, similar to an increasing number of solenoids 13. It is important to note that the stator portions 33a of the first and second actuators 13a and 13b (and similarly for stator portion 33b) can be physically separated as shown, or made of a single piece of magnetic material. In other embodiments, multiple coils 20a, 20b, series stator-plunger air gaps, parallel stator-plunger air gaps, or any combination thereof can be used. The solenoid 16 can also be stacked with other types of actuators (e.g., voice coils) to give them mixed performance characteristics.

[0081] Now for reference Figure 9 It shows that according to similar Figure 8 Another embodiment of the constant air gap solenoid 16 in the solenoid 17 has a solenoid 17, but the first force applied to the plunger 47 by the first actuator 13a is opposite to the second force applied to the plunger 47 by the second actuator 13b. That is, the first force pulls the plunger 47 in the opposite direction to the second force because the orientation of the plunger teeth 60, 62 and the stator teeth 50, 52 of the first actuator 13a is different from that of the plunger teeth 60, 62 and the stator teeth 50, 52 of the second actuator 13b. This orientation of the stator teeth and the plunger teeth allows the first actuator 13a to operate independently of the second actuator 13b, forming a bidirectional actuator that does not require a reset mechanism (e.g., a mechanical spring). The magnitude of the first force relative to the magnitude of the second force depends on the magnetic flux flowing through the air gaps of the respective actuators 13a and 13b, which in turn depends on the number of turns in the coils 20a and 20b of the two actuators 13a and 13b and the current used to energize the coils 20a and 20b of the two actuators 13a and 13b.

[0082] The solenoid 17 can also operate as a sensor capable of performing differential position measurements. In the sensor configuration, all coils 20a, 20b of the first and second actuators 13a and 13b are wound in series and share the same number of turns. Therefore, when current is supplied to the windings, the first actuator 13a and the second actuator 13b apply equal forces to the plunger 47, but in opposite directions. In the illustrated embodiment, the plunger 47 is configured relative to the stator 33 of the first and second actuators 13a, 13b such that the plunger experiences a compressive electromagnetic force when the coils 20a, 20b are energized. In other embodiments, the plunger 47 may be configured relative to the stator 33 of the first and second actuators 13a, 13b such that the plunger experiences a stretching electromagnetic force when the coils 20a, 20b are energized. (Reference) Figure 9 As can be seen, as the plunger 47 moves downward, the overlap of the plunger teeth 60, 62 and stator teeth 50, 52 of the first actuator 13a increases, while the overlap of the plunger teeth 60, 62 and stator teeth 50, 52 of the second actuator 13b decreases proportionally. This inverse relationship of overlapping teeth provides a basis for differential measurements using information from the two connected first and second actuators 13a and 13b. Furthermore, since information can be provided independently from each of the first and second actuators 13a and 13b, the solenoid 17 has inherent sensor redundancy when operating as a differential position sensor, which is well-suited for critical operational applications such as, but not limited to, throttle position sensors. The solenoid 17 is also magnetically self-shielded because the stator 33 of the actuators 13a and 13b inherently guides magnetic flux through a defined path (unlike LVDT or DVRT).

[0083] Figure 1-5 , Figure 8 and Figure 9 The solenoids 10, 12, 13, 14, 15, 16, and 17 shown are exemplary embodiments in which the stator tooth width 140 and the plunger tooth width 142 are equal. In other embodiments, the plunger tooth width and the stator tooth width may be different. (See reference...) Figure 2 (Similarly, this applies to other embodiments.) The distance 144 between stator teeth 50 and 52 is greater than the plunger tooth width 142 to maintain advantageous characteristics (e.g., proximity to constant force and proximity to proportional inductance). The exemplary embodiment increases the distance 144 between stator teeth 50 and 52 by an additional two times the length 80 of the air gap 70 to reduce the likelihood of magnetic flux forming edges on adjacent plunger teeth 62 and 60, respectively. Similarly, the distance 146 between plunger teeth 60 and 62 is greater than the stator tooth width 140.

[0084] In an exemplary embodiment, the distance 146 between the plunger teeth 60 and 62 increases the length 80 of the air gap 70 by an additional two times to reduce the likelihood of magnetic flux forming edges on adjacent stator teeth 52 and 50, respectively. (See reference) Figure 8In the solenoid 16, the distance 148 between the plunger teeth 60 and 62 of the first and second actuators 13a and 13b is at least equal to the plunger tooth width 142.

[0085] In an exemplary embodiment, the distance 148 increases the length 80 of the air gap 70 by an additional two times to reduce the likelihood of magnetic flux forming an edge between the first and second actuators 13a and 13b. (See reference...) Figure 9 In the solenoid 17, the distance 148 between the plunger teeth 60 and 62 of the first and second actuators 13a and 13b is at least twice the plunger tooth width 142. In an exemplary embodiment, the distance 148 is at least three times the plunger tooth width 142 to reduce the possibility of mutual coupling due to magnetic edge effects between the first and second actuators 13a and 13b.

[0086] Referring now to FIG. 10, a solenoid 18 according to another embodiment of a constant air gap solenoid in the form of a rotating solenoid is shown. Solenoid 18 includes a first rotary actuator 18a and a second rotary actuator 18b connected to a common rotor 48. The first and second rotary actuators 18a and 18b each include a stator 38 having radially inwardly extending stator teeth 58, rotor teeth 68 connected to and extending radially outwardly from the common rotor 48, and coils 28a and 28b. An air gap 78 extends between the stator teeth 58 and the corresponding rotor teeth 68. The first rotary actuator 18a is configured to produce counterclockwise rotation when its corresponding coils 28a and 28b are energized. The second rotary actuator 18b is configured to produce clockwise rotation when its corresponding coils 28a and 28b are energized. Note that in other embodiments, the first and second actuators 18a and 18b may each employ only one of coils 28a and 28b. Rotor 48 allows solenoid 18 to rotate bidirectionally without the need for an external reset mechanism such as a torsion spring. Rotor 48 operates above the overlapping areas of the stator teeth 58 and rotor teeth 68 of the first and second rotary actuators 18a and 18b, respectively. In other embodiments, additional rotor teeth may be present on rotor 48, corresponding to additional stator teeth added to stator 38. In other embodiments, an external drive (not shown) may be added to solenoid 18 to achieve large rotational displacements. In other embodiments, coils 28a and 28b may extend relative to each other around the inner circumference of stator 38, thus becoming a single coil with continuously electrically connected windings in a manner that this single coil does not interfere with rotor 48 and rotor teeth 68.

[0087] Solenoid 18 can also operate as a sensor capable of performing differential position measurements. In this configuration, the coils 28a and 28b of the first and second rotary actuators 18a and 18b are wound in series with each other, and each pair of coils 28a and 28b of both the first and second rotary actuators shares the same number of turns in the winding. Therefore, when current is supplied to the windings of the coil pairs 28a and 28b, the first rotary actuator 18a and the second actuator 18b apply equal but opposite torques to the common rotor 48. These opposite torques produce zero net torque on the common rotor 48. When operating as a differential position sensor, solenoid 18 has the same characteristics as when solenoid 17 operates as a differential position sensor (e.g., Figure 9 Similar capabilities (as shown), except that solenoid 18 is used to measure rotational displacement rather than linear displacement.

[0088] Now for reference Figure 11a , 11b Figures 11c and 11c show schematic diagrams illustrating the winding and core configurations of an LVDT 150 (prior art), a DVRT 160 (prior art), and a solenoid 17 (configured as a position displacement sensor). The LVDT 150 includes an upper winding 152, a lower winding 154, a core 156, and a primary winding 158. The DVRT includes an upper winding 162, a lower winding 164, a core 166, and a center tap 169. The solenoid 17 includes an upper winding 172, a lower winding 174, a split core with cores 176a and 176b, and a center tap 179. The upper winding 172 of the solenoid 17 corresponds to coils 20a and 20b in the first actuator 13a, while the lower winding 174 corresponds to coils 20a and 20b in the second actuator 13b (see Figure 11c). Figure 9Cores 176a and 176b correspond to the plunger teeth 60 and 62 of the first and second actuators 13a and 13b, respectively. Unlike the LVDT 150, solenoid 17 does not require a primary winding. Furthermore, solenoid 17 can have its upper winding 172 wound in the same direction as its lower winding 174, similar to the DVRT 160, or more preferably wound in the opposite direction to its lower winding 174, similar to the LVDT 150. The main difference between solenoid 17 and the LVDT 150 or DVRT 160 is that the cores 176a and 176b of solenoid 17 are separated by a connecting rod 177, which does not affect the mutual inductive coupling between the upper winding 172 and the lower winding 174. The split core 176 is unique compared to the single cores 156 and 166 used in the LVDT 150 and DVRT 160, respectively. The split core 176 allows bias current to pass through windings 172 and 174 without generating net force or damping on the split core, which is impossible with LVDT 150 and DVRT 160. To maintain zero net force on the split core 176, solenoid 17 is not used in half the configuration of the Wheatstone bridge as is typically done with DVRT 160. The ability to add bias current without consequences enables both flux linkage-based and BEMF-based algorithms for position estimation and is unique to solenoid 17. Similar to the center tap 169 in DVRT 160, center tap 179 can be used in solenoid 17 to obtain voltage measurements of the upper winding 172 and lower winding 174 for these position estimation algorithms.

[0089] Now for reference Figure 12 The force versus plunger displacement characteristics 180, 182, and 184 of solenoid 17 within the stroke of plunger 47, solenoid 17 configured and operated as a differential position sensor (see [reference]). Figure 9 Characteristic 180 represents the force versus piston displacement curve of the first actuator 13a (see...). Figure 9 Characteristic 182 represents the force versus piston displacement curve of the second actuator 13b, and characteristic 184 represents the net force versus piston displacement curve of the solenoid 17. Characteristic 184 is the sum of characteristics 180 and 182. Figure 12In the illustrated embodiment, the positive pull of characteristic 180 is quasi-constant (i.e., nearly constant within a third predetermined margin) over a portion of the stroke of plunger 47 in region 186, defined as between plunger displacements D1 and D2. Similarly, the negative pull of characteristic 182 is quasi-constant (i.e., nearly constant within a fourth predetermined margin) over a portion of the stroke of plunger 47 in region 186. Region 186 is approximately the middle region between characteristics 180 and 182. It is important to note that characteristics 180 and 182 are obtained by actuating the first and second actuators 13a and 13b independently and separately (i.e., one at a time). In region 186, the positive pull is substantially equal to the negative pull but in opposite directions. The sum of the positive and negative pulls, represented as characteristic 184, is almost zero above region 186 within a fifth predetermined margin. Thus, this allows solenoid 17 to simultaneously actuate the first and second actuators 13a and 13b (see Figure 9 When the solenoid 17 exerts a negligible net force on the plunger 47, this is preferred for a dedicated position sensor. This also requires that the solenoid 17 does not add any substantial damping to the system it senses, and preferably does not add any damping.

[0090] refer to Figure 13 This shows the solenoid 17 within the stroke of plunger 47 (see...). Figure 9 The inductance of the actuator 13a is related to the plunger displacement characteristics 190, 192, and 194. Characteristic 190 represents the first actuator 13a (see...). Figure 9 The inductance-to-piston displacement curves are shown in Figure 190 and 192. Characteristic 192 represents the inductance-to-piston displacement curve of the second actuator 13b, and characteristic 194 represents the net inductance-to-piston displacement curve of the solenoid 17. Characteristic 194 is the sum of characteristics 190 and 192. Figure 13 In the figure, the positive traction inductance of characteristic 190 increases proportionally with plunger displacement and is substantially linear within region 186, while the negative traction inductance of characteristic 192 decreases proportionally with plunger displacement and is also substantially linear within region 186. This inverse relationship between characteristics 190 and 192 can be used in differential measurements to estimate the position of plunger 47. (Reference) Figure 13 The total inductance from characteristic 194, derived from the positive and negative traction inductors, is approximately constant within a sixth predetermined margin in region 186. The total inductance of characteristic 194 corresponds to... Figure 11cThe terminal inductances of the upper winding 172 and lower winding 174 (connected in series) are measured between terminals 171 and 173. As shown in FIG11, the positive traction inductance of characteristic 190 corresponds to the inductance measured from terminal 171 to center tap 179, and the negative traction inductance of characteristic 192 corresponds to the inductance measured from terminal 173 to center tap 179. In an exemplary embodiment, characteristics 190 and 192 of the first and second actuators 13a and 13b decrease and preferably minimize offset 130, and increase and preferably maximize slope 135, respectively. Although characteristics 190 and 192 are shown to have the same offset 130 and slope 135, in other embodiments, their respective offsets and slopes may vary, although they are preferably equal.

[0091] Return to reference Figure 3 The maximum stroke length of the plunger 42 in solenoid 13 (similarly applicable to other embodiments herein) is determined by the smaller of the stator tooth width 140 and the plunger tooth width 142. Reference Figure 6 and Figure 7 It is evident that nonlinear effects accumulate in the vicinity of the toothless overlap position 120 and the full tooth overlap position 122. The exemplary embodiment further includes the plunger 42 (see...). Figure 3 The plunger in the other embodiments herein is limited to operating only within a maximum of 60% of its maximum stroke length. This additional constraint allows solenoid 13 and other solenoids herein to have quasi-constant force and linear inductance variation within their limited stroke.

[0092] Now for reference Figure 14This illustration shows an actuator 200 for actuating solenoid 210 and other embodiments of a constant air gap solenoid, which can be any of the solenoids 10, 12, 13, 14, 15, 16, 17, 18, and 19 disclosed herein. The actuator 200 is an electronic signal driver that may include analog and / or digital components and / or circuitry. For example, the actuator 200 may include an electronic controller, such as a microcontroller, programmed with software to generate digital signal waveforms and having a digital-to-analog converter to convert these digital signal waveforms into analog signal waveforms. When the solenoid 210 is used as an actuator to move a plunger or rotor, it can also be used to simultaneously sense the position of the plunger or rotor. This can be referred to as single-mode operation. Alternatively, when the solenoid 210 is configured to operate as a differential position sensor, it does not significantly affect (and preferably not all) the position of the plunger or rotor. This can be referred to as differential-mode operation. The actuator 200 can be used in conjunction with the solenoid 210 for both single-mode and differential-mode operation. Driver 200 generates a primary control signal 220 and a ripple signal 230, and adds signals 220 and 230 together using adder 240 to generate an output signal 250. Output signal 250 is applied to solenoid 210, thereby inducing a current signal 260 to flow through the solenoid's coil. When solenoid 210 is configured for differential mode operation (e.g., in...),... Figure 9 Figure 10 and Figure 16 (Solts 17, 18, and 19 shown) The primary control signal 220 is purely a DC voltage and has no AC voltage component. The primary control signal 220 includes a continuous voltage bias 270 to avoid division-by-zero errors in the position estimation algorithm. The continuous voltage bias 270 results in a continuous current bias 280 in the current signal 260. The amplitude of the continuous voltage bias 270 is selected to meet the low-speed measurement requirements of flux linkage-based or BEMF-based algorithms (described in more detail below), minimize power usage, and ensure that zero crossing never occurs in the current signal 260. Techniques for generating the ripple signal 230 include separate function generation circuitry or superimposed filter networks, and in other embodiments, other techniques may be employed, such as linear amplifiers or inherent voltage ripple generated by switch-mode power electronics circuitry (e.g., as with H-bridges). The frequency of the ripple signal 230 is set high enough to ensure that aliasing does not occur in the primary control signal 220 or any BEMF generated. When solenoid 210 is configured for single-mode operation (e.g., separately in...), Figure 1-5 , Figure 8 In solenoids 10, 12, 13, 14, 15, and 16 shown, the frequency of the ripple signal 230 is set high enough to ensure it is sufficiently large compared to the mechanical resonant frequency of solenoid 210. The amplitude of the ripple signal 230 is selected based on the signal-to-noise ratio requirements of the inductor-based algorithm (described in more detail below) and power usage.

[0093] Now for reference Figure 15 The diagram illustrates a position estimation algorithm 300, comprising an inductance-based algorithm 340 and a flux linkage-based or BEMF-based algorithm 350, for detecting the plunger or rotor position of the solenoids 10, 12, 13, 14, 15, 16, 17, and 18 disclosed herein. Algorithm 300 is preferably executed by a driver 200, in which case the driver 200 includes an electronic controller programmable with algorithm 300. Alternatively, algorithm 300 may be executed by another computer processor. Algorithms 340 and 350 may be executed simultaneously, independently, and separately from each other, or one may be executed instead of the other. Each algorithm 340 and 350 has voltage and current measurements from voltage and current sensors in step 310 as inputs. For solenoids configured for single-mode operation, the terminal voltages across all coils and the series current through all coils are measured. For solenoids configured for differential-mode operation, it is recommended to use two voltage sensors to measure the voltages across the upper winding 172 and the lower winding 174 (see [link to documentation]). Figure 11c A current sensor measures the series current flowing through the two windings 172 and 174. Measuring winding voltage and current in this way provides good linearity and allows for independent measurements from each actuator within the solenoid. These independent measurements can then be used to perform redundancy checks to determine whether the sensor is functioning correctly or is damaged. When using a device... Figure 13 The constant terminal inductance shown in characteristic 194, in applications where reduced linearity and internal sensor redundancy are permitted, allows for the removal of one of the three sensors. When the electrical parameters of the coil are characterized, the series current can be calculated using the terminal voltage measurement, and vice versa. When measuring center tap 179 (see...) Figure 11c When the voltage of the solenoid is known, the voltage and current characteristics of each actuator inside the solenoid can be inferred.

[0094] Refer again Figure 15 This illustrates that after voltage and current measurements are performed in step 310, algorithm 300 splits into two parallel paths in subsequent steps: an inductance-based algorithm 340 and a flux linkage-based or BEMF-based algorithm 350. For inductance-based algorithm 340, in step 320, the measured voltage of output signal 250 and the measured current of current signal 260 are bandpass filtered. Figure 14(As can be seen in the image) Filtering is performed to isolate the measured components of the voltage corresponding to the ripple signal 230 and the current ripple signal induced in the solenoid, referred herein as the measured voltage ripple signal and the measured current ripple signal. Depending on the application and surrounding hardware, the bandpass filter in step 320 may have its quality factor adjusted accordingly, or a higher-order filter may be made. This filtering can be done digitally or using analog circuitry. Next, the measured voltage ripple signal and the measured current ripple signal are passed through an RMS filter in step 330, which calculates the root mean square (RMS) values ​​of these signals, referred herein as the RMS voltage and RMS current. The RMS filter in step 330 can be analog circuitry or a digital program. The RMS voltage and RMS current are then input to an inductor-based algorithm 340.

[0095] The inductance-based algorithm 340 determines the solenoid impedance by applying Ohm's law to the RMS voltage and RMS current. The resistive portion of the impedance can then be found through periodic measurements, assumed to be constant or negligible depending on the operating environment. The inductive portion of the impedance can then be found by utilizing the orthogonal properties of resistance and inductance. The inductance-based algorithm 340 can be summarized by the following Equation 1, where y is the plunger position, U... rms滤波 It is the RMS voltage, I rms滤波 Here, R is the RMS current, R is the winding resistance, f is the specified ripple frequency, C1 is a constant considering the solenoid's geometry and material parameters, and C2 is a constant that compensates for the minimum inductance of the solenoid. To determine C1 and C2, the solenoid inductance is first measured (e.g., using an inductance-based algorithm 340) over the expected plunger stroke. This measurement produces... Figure 7 The graph shown is shaped as described. Next, a linear regression is fitted within the expected range. C1 is the slope of the regression. C2 is a function of the y-intercept of the regression and C1.

[0096]

[0097] In an exemplary embodiment, C1 is empirically measured as Figure 7The slope 135 of the inductance with respect to the tooth overlap characteristic 115 shown, C2, can be found by linearizing the first-order relationship that can be created using C1. Alternatively, C1 can also be determined through analytical modeling or FEA analysis. When the ripple frequency is high, the resistance of the solenoid can be ignored, assumed to be constant, or measured using Ohm's law when the plunger or rotor is stationary. The CAS sensor can also find the resistance by isolating the DC bias signal using an analog or digital low-pass filter and continuously using Ohm's law. The output of the inductance-based algorithm 340 can be used as an independent estimate 370; alternatively or additionally, the independent estimate 370 can be forwarded to a meta-estimation algorithm 360, also known as sensor fusion technology, as described in more detail below.

[0098] It is worth noting that the inductance-based algorithm 340 is well-suited for measuring low-speed piston motion. Similar to other previously published and patented methods that use AC ripple to identify inductance, at high speeds, the estimates are prone to phase lag errors. The independent estimate 370 is well-suited for obtaining absolute position with slow transient motion. When using the inductance-based independent estimate 370 to estimate high-speed motion, phase errors and aliasing can occur. These can be compensated for by using a larger drive frequency. However, the exemplary embodiment instead uses information from the flux-based or BEMF-based algorithm 350, which will be described in more detail below.

[0099] When using a BEMF-based method, algorithm 350 utilizes the BEMF generated by the moving plunger. Unlike existing techniques that require a ripple signal, the proposed algorithm does not have this requirement and can be based on the output signal 250 (see [link to algorithm]) with or without the superimposed ripple signal 230. Figure 14 The operation is performed using voltage and current measurements. Directly measured values ​​are taken from... Figure 15 The voltage and current sensor 310 is shown. The direct measurements are then applied to Equation 2 below. Based on Faraday's law and Ohm's law, the BEMF-based method of Algorithm 350 can be expressed by Equation 2, where U is the original voltage measurement, I is the original current measurement, and... It is the derivative of the measured current value.

[0100]

[0101] It is important to note that Equation 2 requires integration to obtain the relative position estimate. Therefore, the algorithm is prone to accumulating errors due to drift. The accumulated error becomes large over long measurement periods, but small over short periods. Furthermore, the measurement exhibits a better signal-to-noise ratio at high speeds. Therefore, this measurement is well-suited for measuring high-speed plunger displacement. Finally, it is crucial that the current signal 260 never crosses zero to ensure algorithm stability. This imposes a constraint that the primary control signal 220 must have a sufficiently large voltage bias 270 to produce a current bias 280 that is always greater than zero.

[0102] When examining the BEMF-based methods of inductor-based algorithms 340 and 350, it becomes clear that they complement each other. This is because the position estimates from the inductor-based algorithm 340 are well-suited for low-speed measurements, while the position estimates from the BEMF-based algorithm 350 are well-suited for high-speed measurements. Furthermore, since the two algorithms can operate simultaneously, a meta-estimation algorithm 360 (e.g., a complementary filter) can be used to combine the measurements. The meta-estimation algorithm 360 combines the measurements and allows for a wide-bandwidth, low-noise measurement that far exceeds the capabilities of a single algorithm. The meta-estimation algorithm 360 is described in more detail below.

[0103] When using the meta-estimation algorithm 360, the BEMF-based method in algorithm 350 can be replaced by a more robust flux linkage-based method. The flux linkage-based method in algorithm 350 is merely a restatement of the BEMF-based algorithm; however, its actual implementation can lead to different performance characteristics. The flux linkage-based method in algorithm 350 is defined according to Equation 3 as follows:

[0104]

[0105] The independent estimate 380 based on the magnetic flux linkage algorithm 350 can be used to directly infer the relative plunger displacement using the following equation 4:

[0106]

[0107] However, it is important to note that initializing the integral of Equation 4 (in the flux linkage-based method of Algorithm 350) is more challenging than initializing the integral of Equation 2 (in the BEMF-based method of Algorithm 350). Therefore, as an independent measurement, Algorithm 350 based on BEMF may be preferred. However, when using the meta-estimation algorithm 360, the initialization of the integral is no longer important, so the flux linkage-based measurement is superior because it does not introduce a time step delay or require the numerical derivative of the measured current, which can easily amplify sensor noise.

[0108] The output of the flux-based or BEMF-based algorithm 350 can be used as an independent estimate 380; alternatively, or additionally, the independent estimate can be passed to the meta-estimation algorithm 360, such as... Figure 15 As shown. Independent estimate 380 is preferably applied to situations requiring high-speed estimates and relative positions. At low speeds, integration accumulates errors and causes position estimates to drift. Errors can be reset periodically, but the exemplary embodiment will utilize meta-estimation algorithm 360 to compensate for the drift. As an independent measurement, the BEMF-based method of algorithm 350 is superior to the flux linkage-based method of algorithm 350 because its integral is easier to initialize. However, when used with meta-estimation algorithm 360, the flux linkage-based method of algorithm 350 is preferred because it does not require prior position knowledge and does not require calculating derivatives from current.

[0109] Figure 15 The illustration shows that the meta-estimation algorithm 360 can be used to simultaneously combine algorithms 340 and 350 into a single estimate 390. The meta-estimation algorithm 360 can include a complementary filter or a Kalman filter. With proper tuning, the estimate 390, considered a broadband estimate, will be free of drift and phase hysteresis errors. Only aliasing and higher-order magnetic effects limit the upper bandwidth of the measurement. In almost all cases, it will be advantageous to use the estimate 390 from the meta-estimation algorithm 360 instead of the independent estimates 370 and 380. The term d(LI) / dt from Equation 3 can be directly used as a high-speed input to the meta-estimation algorithm 360. The output of the meta-estimation algorithm 360 can then be divided by the current and converted into a position estimate based on the inductance-position relationship.

[0110] It is important to note that various combinations of the previously disclosed algorithms can be used, in addition to or besides algorithms 340 and 350, to estimate the position of the solenoid disclosed herein. To increase the usefulness of the solenoid, position estimates employ algorithms with complementary ideal bandwidth ranges, such as flux linkage-based and inductance-based algorithms. It is also preferable to ensure that the algorithms are compatible so that independent, simultaneous measurements can be generated and combined with the meta-estimation algorithm 360.

[0111] The simple design of constant air gap solenoids allows them to be easily stacked into larger structures while moving a common plunger. This stacking can occur inside the stator, adding extra teeth and coils to the design. Stacking can also occur by adding separate stators, with one common plunger spanning all stators. In its most basic form, all stators are pulled in one direction, and the output force can increase proportionally with each additional stage. Winding all stators together in series allows the above algorithm to be applied without any modification, as the overall structure can be considered as a single CAS. However, it is also possible to wind two stators together in series but align them so that they pull the plunger in opposite directions. This configuration allows for bidirectional plunger movement without a reset mechanism. In this case, each solenoid requires its own voltage and current sensors. However, in this pull-pull configuration, a very robust position sensor is generated if the coils are driven by a series current.

[0112] The CAS sensor operates by having two identical CAS actuators pull against each other to provide current. Since they are identical, the two actuators will produce equal but opposite forces. This is important because an ideal sensor would not exert a force on the system it is measuring. Furthermore, it is important to note that in this configuration, as the stator-plunger overlap of one CAS increases, the stator-plunger overlap of the other stage decreases. This means that each CAS operates in opposite directions, thus allowing for differential measurements of the plunger positions according to Equation 5, where S is the total stroke length of the plunger (e.g., ...). Figure 9 As shown, plunger 47), y1 is an actuator (e.g., Figure 9 The position estimate of the first actuator 13a) shown, and y ２ It is another actuator (e.g., Figure 9 The position estimate of the second actuator 13b) shown:

[0113]

[0114] It is important to note that the inputs y1 and y2 in Equation 5 can be independent estimates 370 and 380 from inductance-based algorithm 340 and flux linkage-based or BEMF-based algorithm 350, respectively, or a meta-estimate 390 from meta-estimation algorithm 360. Differential measurements significantly improve the signal-to-noise ratio of the position estimate because the measurements gain immunity to noise from temperature and current sensors. Differential measurements can be performed using two voltage sensors and one current sensor, or two voltage sensors or one voltage sensor and one current sensor. In a three-sensor configuration, each CAS can be monitored independently, allowing internal sensor redundancy, which is important for critical operational sensors. In a two-sensor configuration, internal redundancy and some linearity are lost; however, the implementation cost is reduced because the lost measurements can be computed from the remaining two sensors.

[0115] Figure 15 Any one of the estimates, 370, 380, and 390, can be used by the CAS actuator for position feedback in the controller loop. This allows the CAS actuator to maintain the desired plunger position or move along a predetermined trajectory without a dedicated position sensor. While this concept is possible in other actuator types, the CAS actuator has the novel ability to accomplish this task without a lookup table while fusing two simultaneous internal estimates.

[0116] For CAS sensors Figure 15 The algorithm 300 shown is applied to Figure 11c The upper winding 172 and lower winding 174 in the solenoid 17 are shown. The output from algorithm 300 can then be combined into differential measurements using Equation 5 above. A key advantage of differential measurements is common-mode interference suppression. With a three-sensor approach, common-mode interference suppression makes the algorithm virtually unaffected by resistance in its linear region. By eliminating resistance dependence, CAS achieves a high degree of temperature immunity. Furthermore, common-mode material variations caused by factors such as temperature will also be rejected.

[0117] It is important to note that the inductor-based algorithm 340 for the CAS sensor can be replaced by other previously disclosed DVRT voltage-only algorithms. The DVRT algorithm can then be combined with a novel flux-based or BEMF-based algorithm 350 via the meta-estimation algorithm 360. However, it is important to note that the reverse is not possible because DVRT does not use a current sensor and cannot integrate the flux-based or BEMF-based algorithm 350, as the bias current will... Figure 11b A resultant force is generated on the core 166 of the DVRT 160 shown. Due to the unique capability achieved by adding a bias current, the CAS sensor is able to estimate position over a wider bandwidth than LVDT or DVRT.

[0118] Now for reference Figure 16 The diagram illustrates a solenoid 19 according to another embodiment of a constant air gap solenoid, which does not employ a ferromagnetic stator to guide magnetic flux. Solenoid 19 includes a first actuator 19a and a second actuator 19b and has a common plunger 49. The plunger 49 corresponds to... Figure 11c The split iron core 176 is shown in the diagram. The first actuator 19a includes an iron core 176a and a corresponding coil 20, and the second actuator 19b includes an iron core 176b and a corresponding coil 20. The iron cores 176a and 176b are connected by a connecting member 109 made of a non-ferromagnetic material. Each iron core 176a and 176b includes effective plunger teeth 60 corresponding to the north and south poles of the iron core. Magnetic flux lines 400 and 410 represent how magnetic flux flows through the iron core 176a when the coil 20 is energized in the actuator 19a, and it can be understood that more such flux lines exist. Magnetic flux lines 420 and 430 represent how magnetic flux flows through the iron core 176b when the coil 20 is energized in the actuator 19b, and it can be understood that more such flux lines exist. In the illustrated embodiment, when coil 20 is energized, the north poles of iron cores 176a and 176b face each other, such that magnetic flux lines 400 and 410 are repelled by magnetic flux lines 420 and 430 (i.e., the magnetic flux generated by coil 20 of actuator 19a drives the magnetic flux generated by coil 20 of actuator 19b), thereby creating the magnetic flux loop shown. In other embodiments, when coil 20 is energized, the south poles of iron cores 176a and 176b face each other, such that magnetic flux lines 400 and 410 are also repelled by magnetic flux lines 420 and 430, but the magnetic flux along magnetic flux lines 400, 410, 420, and 430 respectively interacts with... Figure 16The flow is in the opposite direction as shown. In a further embodiment, the north pole of core 176a may face the south pole of core 176b, or the south pole of core 176a may face the north pole of core 176b; in both embodiments, the magnetic flux generated by the coils 20 of actuators 19a and 19b is constructively additive, such that a common magnetic flux line will flow through cores 176a and 176b and coil 20. Instead of the air gap between the ferromagnetic stator and the plunger / rotor (such as air gaps 70, 72, 78 selectively found in solenoids 10, 11, 12, 13, 14, 15, 16, 17, and 18 as disclosed above), a first air gap exists between the north and south poles of core 176a, and a second air gap exists between the north and south poles of core 176b. The lengths of flux lines 400 and 420 (or 410 and 420) represent the average flux path lengths of all flux lines in actuators 19a and 19b, respectively. The coils 20 of the first and second actuators 19a and 19b extend about axis 90 and are longitudinally spaced along axis 90, and are fixed in place so that they do not move relative to plunger 49. The coil 20 from actuator 19a corresponds to the upper winding 172, and the coil 20 from actuator 19b corresponds to the lower winding 174. No ferromagnetic stator guides the magnetic flux generated by windings 172 and 174, respectively. Figure 11a and 11b The LVDT 150 and DVRT 160 shown have similar features. However, the solenoid 19 still includes the split core 176 and therefore continues to be produced. Figure 12 The force properties seen in 180, 182 and 184 and Figure 13 The inductance characteristics shown are 190, 192, and 194. The lack of a ferromagnetic stator to guide the magnetic flux generated when coil 20 is energized allows solenoid 19 to be, for example, more magnetically driven than... Figure 9 The solenoid 17 shown is configured to be much more compact when operating as a differential position sensor. However, the lack of a guiding magnetic flux path provided by the ferromagnetic stator increases the net force variation in region 186 of characteristic 184 (see [link to relevant documentation]). Figure 12 This reduces the linearity of both the positive traction inductance of characteristic 190 and the negative traction inductance of characteristic 192 (see...). Figure 13 The lack of a ferromagnetic stator also eliminated Figure 1-5 , Figure 8-1 The geometries of solenoids 10, 12, 13, 14, 15, 16, 17, and 18, shown in Figure 0, exhibit magnetic self-shielding properties, respectively. However, additional external magnetic shielding can be included. Figure 16 The geometry of the solenoid 19 is designed to protect it from the adverse effects of stray magnetic fields or nearby ferromagnetic materials.

[0119] Mutual inductance of solenoid 19 and Figure 9 The flux decoupling geometry of the solenoid 17 shown is different and cannot be ignored. Similar to... Figure 11b The DVRT 160 shown has a solenoid 19 with quasi-constant mutual inductance over its travel. However, unlike the DVRT 160, the windings of the coils 20 of actuator 19a and actuator 19b are wound in the same direction to add the magnetic flux, or wound in opposite directions to subtract the magnetic flux. An exemplary embodiment has windings wound in opposite directions so that the mutual inductance is subtracted from the positive and negative traction inductances. This reduces the inductance offset 130 (see...). Figure 13 This improves the inductor-based algorithm 340 (see [link to algorithm 340]) while keeping the inductor slope 135 unaffected. Figure 15 () sensitivity.

[0120] While specific elements, embodiments, and applications of the invention have been shown and described, it should be understood that the invention is not limited thereto, as modifications can be made by those skilled in the art without departing from the scope of this disclosure, particularly in accordance with the foregoing teachings.

Claims

1. A solenoid, comprising: The stator includes a first stator tooth and a second stator tooth; An armature, comprising a first armature tooth and a second armature tooth, the armature being linearly movable relative to the stator within a predetermined stroke; and a coil associated with at least one of the stator and the armature, the coil being used to conduct current and generate current by the armature. The magnetic flux guided by the stator and the armature, at least one of the stator and the armature serving as the ferromagnetic core of the coil; A first air gap, the first air gap being located between the first stator tooth and the first armature tooth and having a first length; The second air gap is located between the second stator tooth and the second armature tooth and has a second length; Wherein, during the predetermined stroke, when the first armature tooth and the second armature tooth overlap with the first stator tooth and the second stator tooth respectively, the first length and the second length are constant within a predetermined margin; The inductance of the solenoid changes linearly within a predetermined stroke.

2. The solenoid according to claim 1, wherein the first length and the second length are equal within the predetermined margin.

3. The solenoid of claim 1, wherein the stator surrounds the armature.

4. The solenoid of claim 1, wherein the stator is only on one side adjacent to the armature.

5. The solenoid according to claim 1, wherein the stator comprises a cuboid shape or a cylindrical shape.

6. The solenoid of claim 1, further comprising an armature guide associated with the armature, the armature guide being configured to guide the armature along the longitudinal axis within a predetermined tolerance.

7. The solenoid of claim 1, wherein each of the first stator tooth and the second stator tooth includes a stator tooth surface, and each of the first armature tooth and the second armature tooth includes an armature tooth surface, wherein each of the first armature tooth and the second armature tooth overlaps with the first stator tooth and the second stator tooth, respectively, when any vertical projection from the armature tooth surface intersects with the corresponding stator tooth surface.

8. The solenoid according to claim 1, wherein the widths of the first stator tooth and the second stator tooth are respectively equal to the widths of the first armature tooth and the second armature tooth.

9. The solenoid of claim 1, wherein the first position of the armature is defined as the position where the first stator tooth and the second stator tooth have the minimum overlap with the first armature tooth and the second armature tooth, respectively, and the second position of the armature is defined as the position where the first stator tooth and the second stator tooth have the maximum overlap with the first armature tooth and the second armature tooth, respectively, wherein the predetermined stroke is within the range between the first position and the second position.

10. The solenoid of claim 9, wherein the force of the solenoid is constant within a first predetermined tolerance over the predetermined stroke; and the inductance of the solenoid over the predetermined stroke is linearly proportional to the amount of overlap between the first stator tooth and the second stator tooth and the first armature tooth and the second armature tooth, respectively, within a second predetermined tolerance.

11. The solenoid according to claim 9, wherein the amount of overlap between the first stator tooth and the second stator tooth and the first armature tooth and the second armature tooth is linearly proportional to the armature position on the predetermined stroke.

12. The solenoid according to claim 1, further comprising: The third stator tooth and the fourth stator tooth associated with the stator; the third armature tooth and the fourth armature tooth associated with the armature; A third air gap is located between the third stator tooth and the third armature tooth, and the third air gap has a third length; A fourth air gap is located between the fourth stator tooth and the fourth armature tooth, the fourth air gap having a fourth length; When the third armature tooth and the fourth armature tooth overlap with the third stator tooth and the fourth stator tooth respectively during the predetermined stroke, the third length and the fourth length are constant within a predetermined margin.

13. The solenoid of claim 12, wherein the distance between the first stator tooth and the third stator tooth is greater than at least one of the width of the first armature tooth and the width of the third armature tooth.

14. The solenoid of claim 12, wherein the distance between the first armature tooth and the third armature tooth is greater than at least one of the width of the first stator tooth and the width of the third stator tooth.

15. The solenoid of claim 12, wherein the armature further comprises a connecting member that connects the first armature tooth and the second armature tooth to the third armature tooth and the fourth armature tooth.

16. The solenoid of claim 15, wherein the connecting member is made of a non-ferromagnetic material.

17. The solenoid according to claim 12, further comprising: A first magnetic flux path, the first magnetic flux path including the first air gap and the second air gap; as well as The second magnetic flux path includes the third air gap and the fourth air gap; The first magnetic flux path and the second magnetic flux path are connected in parallel.

18. The solenoid according to claim 17, further comprising a third magnetic flux passage and a fourth magnetic flux passage, the third magnetic flux passage comprising a fifth air gap and a sixth air gap, the fourth magnetic flux passage comprising a seventh air gap and an eighth air gap; wherein the first magnetic flux passage is connected in series with the third magnetic flux passage, the second magnetic flux passage is connected in series with the fourth magnetic flux passage, and the combination of the first magnetic flux passage and the third magnetic flux passage is connected in parallel with the combination of the second magnetic flux passage and the fourth magnetic flux passage.

19. The solenoid according to claim 12, further comprising: A first magnetic flux path, the first magnetic flux path including the first air gap and the second air gap; as well as The second magnetic flux path includes the third air gap and the fourth air gap; The first magnetic flux path is connected in series with the second magnetic flux path.

20. The solenoid according to claim 19 further includes a third magnetic flux passage and a fourth magnetic flux passage, the third magnetic flux passage including a fifth air gap and a sixth air gap, and the fourth magnetic flux passage including a seventh air gap and an eighth air gap; wherein the third magnetic flux passage and the fourth magnetic flux passage are connected in parallel, and the combination of the first magnetic flux passage and the second magnetic flux passage is connected in series with the combination of the third magnetic flux passage and the fourth magnetic flux passage.

21. The solenoid of claim 19, wherein the stator comprises a first portion and a second portion, and the coil is a first coil associated with the first portion of the stator.

22. The solenoid of claim 21, further comprising a second coil associated with a second portion of the stator.

23. The solenoid of claim 19, wherein the solenoid is a first solenoid, further comprising a second solenoid having the same characteristics as the first solenoid, and further comprising a common armature, the common armature including a connecting member connecting the armature of the first solenoid to the armature of the second solenoid.

24. The solenoid of claim 23, wherein adjacent plunger teeth are defined, on the one hand, as those teeth selected from the first armature teeth, second armature teeth, third armature teeth and fourth armature teeth of the first solenoid, and on the other hand, as those teeth selected from the first armature teeth, second armature teeth, third armature teeth and fourth armature teeth of the second solenoid, wherein the distance between adjacent plunger teeth is at least equal to the width of at least one of the adjacent plunger teeth.

25. The solenoid of claim 23, wherein the first solenoid is configured relative to the second solenoid such that when the coils of the first solenoid and the second solenoid are energized, they exert forces that pull the common armature in opposite directions, respectively.

26. The solenoid of claim 25, wherein the arrangement of the first armature teeth and the second armature teeth of the first solenoid relative to the first stator teeth and the second stator teeth of the first solenoid is spatially different from the arrangement of the first armature teeth and the second armature teeth of the second solenoid relative to the first stator teeth and the second stator teeth of the first solenoid.

27. The solenoid of claim 25, wherein, compared to the manner in which the first armature teeth and the second armature teeth of the second solenoid extend along or about the longitudinal axis of the first stator teeth and the second stator teeth of the second solenoid, respectively, they extend in opposite directions relative to the first stator teeth and the second stator teeth of the first solenoid.

28. The solenoid of claim 25, wherein the coil of the first solenoid includes a winding and the coil of the second solenoid includes a winding, wherein the coils of the first solenoid and the second solenoid include an equal number of corresponding windings such that when the coils of the first solenoid and the second solenoid are energized with equal currents, they exert a force of common magnitude within tolerance.

29. The solenoid of claim 25, wherein the coil of the first solenoid is energized independently and separately from the coil of the second solenoid.

30. The solenoid of claim 25, wherein the coils of the first solenoid and the second solenoid are electrically connected.

31. The solenoid of claim 1, further comprising a driver configured to generate a primary control signal and a ripple signal, and including an adder to superimpose the ripple signal onto the primary control signal to provide an output signal, wherein the output signal is supplied to the solenoid.

32. The solenoid of claim 31, wherein the primary control signal includes a bias voltage.

33. The solenoid of claim 31, wherein the frequency of the ripple signal is higher than a predetermined value such that the ripple signal does not alias with the primary control signal or the back electromotive force generated by applying the output signal to the solenoid.

34. The solenoid according to claim 31, wherein the primary control signal is a DC voltage.

35. The solenoid according to claim 1, further comprising an electronic controller, the electronic controller being programmed to: Measure the voltage across the coil; Measure the current passing through the coil; The position of the armature is estimated by employing an inductance-based algorithm that provides a first independent position estimate and a flux linkage-based or back electromotive force (BEMF)-based algorithm that provides a second independent position estimate; and The combined position estimate of the armature is determined by employing a meta-estimation algorithm, which combines the first independent position estimate and the second independent position estimate to provide a combined position estimate.

36. A solenoid, comprising: A split-core armature, the split-core armature comprising a first core, a second core, and a connecting member connecting the first core and the second core, the connecting member being made of a non-ferromagnetic material, the split-core armature being configured to move along a longitudinal axis; a first coreless electromagnet, the first coreless electromagnet comprising a first coil extending about the longitudinal axis, the first core and the first coil forming a first actuator, the first core having a north pole and a south pole when the first coil is energized; The second coreless electromagnet, the second coreless electromagnet comprising a coreless electromagnet surrounding the coreless electromagnet. A second coil extending along the longitudinal axis, the second iron core and the second coil forming a second actuator, the second iron core having a north pole and a south pole when the second coil is energized; a first air gap and a second air gap; The first coil and the second coil are configured in one of the following ways: 1) The first air gap extends between the north and south poles of the first iron core, and the second air gap extends between the north and south poles of the second iron core, such that when the first coil and the second coil are energized, magnetic flux leaving the north pole of the first iron core enters the south pole of the first iron core, and magnetic flux leaving the north pole of the second iron core enters the south pole of the second iron core; and 2) The first air gap extends between the north pole of the first iron core and the south pole of the second iron core, and the second air gap extends between the north pole of the second iron core and the south pole of the first iron core, so that when the first coil and the second coil are energized, the magnetic flux leaving the north pole of the first iron core enters the south pole of the second iron core, and the magnetic flux leaving the north pole of the second iron core enters the south pole of the first iron core. The first coil and the second coil are spaced apart along the longitudinal axis, and the first core is configured relative to the first coil and the second core is configured relative to the second coil, such that when the first coil and the second coil are energized, the first actuator applies a first force that pulls the split core armature in a direction opposite to a second force applied to the split core armature by the second actuator; and the inductance of the solenoid changes linearly within a predetermined stroke.

37. The solenoid of claim 36, wherein the first coil has a first winding and the second coil has a second winding, wherein the first number of turns of the first winding is equal to the second number of turns of the second winding.

38. The solenoid of claim 36, wherein the first coil is electrically connected to the second coil.

39. A method for estimating the armature position in a solenoid comprising at least one coil, comprising: The solenoid as described in claim 1 or 36 is used; Measure the voltage across at least one of the coils of the solenoid and provide the measured voltage signal; Measure the current through at least one of the coils of the solenoid and provide the measured current signal; The first position estimate of the armature is determined using a first position estimation algorithm, wherein the first position estimation algorithm uses the measured voltage signal and the measured current signal as input; The second position estimate of the armature is determined using a second position estimation algorithm, wherein the measured voltage signal and the measured current signal are used as inputs. as well as The third position estimate of the armature is determined using a meta-estimation algorithm, which takes the first position estimate and the second position estimate as input.

40. The method of claim 39, wherein the first position estimate is determined in the first position estimation algorithm according to the following formula: in: Urms filtering is the root mean square value of the voltage signal obtained after the measured voltage signal is bandpass filtered; Irms filtering is the root mean square value of the current signal obtained after the measured current signal is bandpass filtered. R is the resistance of at least one of the coils; f is the ripple frequency of the measured voltage signal; C1 is a constant representing the slope of the graph showing the relationship between the inductance and armature position of the solenoid; and C2 is a constant representing the y-intercept of the graph showing the relationship between the inductance and armature position of the solenoid.

41. The method of claim 39, wherein the second position estimate is determined in the second position estimation algorithm according to the following formula: in: U is the measured voltage signal; I is the measured current signal; R is the derivative of the measured current signal; R is the resistance of at least one of the coils; C1 is a constant representing the slope of the graph showing the relationship between the inductance and armature position of the solenoid; and C2 is a constant representing the y-intercept of the graph showing the relationship between the inductance and armature position of the solenoid.

42. The method of claim 39, wherein the second position estimate is determined in the second position estimation algorithm according to the following formula: in: U is the measured voltage signal; I is the measured current signal; R is the resistance of at least one of the coils; C1 is a constant representing the slope of the graph showing the relationship between the inductance and armature position of the solenoid; and C2 is a constant representing the y-intercept of the graph showing the relationship between the inductance and armature position of the solenoid.

43. The method of claim 39, wherein the meta-estimation algorithm comprises a complementary filter or a Kalman filter.

44. The method according to claim 39, wherein the first position estimation algorithm is an inductance-based algorithm, and the second position estimation algorithm is a flux linkage-based algorithm or a back electromotive force (BEMF)-based algorithm.

45. A method for estimating the armature position in a solenoid, wherein, The solenoid includes a first coil and a second coil, and the method includes: employing the solenoid as described in claim 36; Measure the voltage across at least one of the coils of the solenoid and provide the measured voltage signal; Measure the current through at least one of the coils of the solenoid and provide the measured current signal; The first position estimate of the armature is determined using a first position estimation algorithm, wherein the first position estimation algorithm uses the measured voltage signal and the measured current signal as input; A second position estimate of the armature is determined using a second position estimation algorithm, wherein the measured voltage signal and the measured current signal are used as inputs; and The third position estimate of the armature is determined using a meta-estimation algorithm, which takes the first position estimate and the second position estimate as input. Wherein, the coil and the first position estimate, the second position estimate and the third position estimate correspond to the first actuator. The fourth, fifth, and sixth position estimates of the armature are determined for the second actuator in a manner that determines the first, second, and third position estimates, respectively. The difference location estimate is determined using the following equation: in: y1 is one of the first position estimate, the second position estimate, or the third position estimate; y2 is one of the fourth position estimate, the fifth position estimate, or the sixth position estimate; and S is the total stroke length of the armature of the solenoid.

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