Solenoid

Abstract

In the present invention, when a coil is not energized, a magnetic circuit is formed by a magnetic force of a permanent magnet, and a mover is held at a first position or a second position. In the first position, a magnetic circuit is formed by a first stator and the mover. In the second position, a magnetic circuit is formed by the first stator, a second stator, a yoke, and the mover. In a state where the mover is in the first position, the coil is energized in the forward direction. In this case, a magnetic attraction force is generated in a magnetic gap between the mover and the second stator, and the mover is displaced to the second position. In a state where the mover is in the second position, the coil is energized in the reverse direction. In this case, the magnetic force of the permanent magnet between the mover and the second stator is canceled out by a magnetic force of the coil. In this case, a magnetic attraction force is generated in a gap between the mover and the first stator, and the mover is displaced to the first position.

Description

solenoid CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-92928 filed in Japan on June 7, 2024, Patent Application No. 2024-195983 filed in Japan on November 8, 2024, and Patent Application No. 2025-8589 filed in Japan on January 21, 2025, and the contents of the basic applications are incorporated by reference in their entirety.

[0002] The present disclosure relates to a solenoid, and the solenoid of the present disclosure is useful, for example, for driving a clutch that switches between transmitting and not transmitting power in a vehicle.

[0003] Japanese Patent Application Laid-Open No. 2003-144999 discloses a technique in which a permanent magnet is disposed in a mover of a solenoid, and the mover is held in a non-energized position while the coil is not energized.

[0004] Japanese Patent Application Laid-Open No. 2021-89923

[0005] In the solenoid disclosed in Patent Document 1, the magnetic force of the permanent magnet can only hold one position, the de-energized position. To hold the solenoid in another position, it is necessary to energize the coil and hold it in the energized position. In other words, the solenoid disclosed in Patent Document 1 can only hold a single position using the magnetic force of the permanent magnet, and to hold it in another position, it is necessary to energize the coil.

[0006] In view of the above, an object of the present disclosure is to make it possible to hold two positions, a first position and a second position, using the magnetic force of a permanent magnet.

[0007] The solenoid of the present disclosure comprises a cylindrical coil that is excited when energized, a first stator that is disposed on the inner periphery of the coil and forms a magnetic circuit when the coil is energized, a second stator that is disposed on the inner periphery of the coil opposite the first stator and forms a magnetic circuit together with the first stator when the coil is energized, a yoke that is disposed on the outer periphery of the coil and forms a magnetic circuit when the coil is energized, and a mover that is disposed on the inner periphery of the first stator on the inner periphery of the coil so as to be able to slide on the inner periphery of the first stator, and is disposed with a magnetic gap between it and the second stator, and is displaceable between a first position where the magnetic gap is maximum and a second position where the magnetic gap is minimum.

[0008] The mover of the solenoid of the present disclosure is provided with a permanent magnet, and a magnetic circuit is formed by the first stator and the mover at the first position due to the magnetic force of the permanent magnet, and a magnetic circuit is formed by the first stator, the second stator, the yoke, and the mover at the second position due to the magnetic force of the permanent magnet, and the mover is held at the second position. Furthermore, when the mover is held at the first position and the second position, the coil is not energized.

[0009] In the solenoid of the present disclosure, when the mover is in a first position, current is passed through the coil to generate a magnetic attraction force in the magnetic gap between the mover and the second stator, thereby displacing the mover to the second position. Also, when the mover is in the second position, reverse current is passed through the coil to generate a magnetic force in the opposite direction to the magnetic flux of the permanent magnet, thereby canceling out the magnetic force of the coil due to the permanent magnet between the mover and the second stator, and displacing the mover to the first position with the magnetic attraction force generated in the air gap between the mover and the first stator.

[0010] The solenoid of the present disclosure can maintain the position of the mover in two positions, a first position and a second position, by the magnetic flux of the permanent magnet. For example, when the solenoid of the present disclosure is used to switch between transmission and non-transmission of a clutch, both the transmission position and the non-transmission position can be maintained by the magnetic flux of the permanent magnet. This eliminates the need to energize the coil to maintain the position, thereby reducing power consumption.

[0011] 1 is a cross-sectional view of an embodiment of a solenoid according to the present disclosure; FIG. 1 is a cross-sectional view showing a magnetic circuit when the solenoid shown in FIG. 1 is in a first position and the coil is not energized; FIG. 1 is a cross-sectional view showing a magnetic circuit when the solenoid shown in FIG. 1 is in the first position and the coil is energized in a forward direction; FIG. 1 is a cross-sectional view showing a magnetic circuit when the solenoid shown in FIG. 1 is in a second position and the coil is not energized; FIG. 1 is a cross-sectional view showing a magnetic circuit when the solenoid shown in FIG. 1 is in the second position and the coil is energized in a reverse direction; FIG. 2 is a diagram illustrating the relationship between the stroke of a solenoid and attractive force; FIG. 2 is a cross-sectional view showing the clutch in an off state in an example of use of the solenoid shown in FIG. 1; FIG. 2 is a cross-sectional view showing the clutch in an on state in an example of use of the solenoid shown in FIG. 1; FIG. 3 is a cross-sectional view of another embodiment of a solenoid according to the present disclosure; FIG. 4 is a cross-sectional view showing the clutch in an off state in an example of use of the solenoid shown in FIG. 9;

[0012] First, the configuration of the solenoid 100 will be described with reference to Figure 1. The coil 102 is formed by winding a conducting wire many times around the outer periphery of a bobbin 101 made of an electrically insulating resin material such as polypropylene. The bobbin 101 is cylindrical with an inner diameter of approximately 30 millimeters, and therefore the coil 102 is also cylindrical. The outer diameter of the coil 102 is approximately 40 millimeters. If the direction along the axis of the cylindrical shape is defined as the axial direction, the axial length of the coil 102 is approximately 60 millimeters.

[0013] A yoke 110 made of an iron-based magnetic material is disposed around the coil 102. The yoke 110 is cylindrical and covers the coil 102, with a wall thickness of approximately 2 millimeters. In FIG. 1 , the upper axial side of the coil 102 is designated as a first direction A, and the lower axial side is designated as a second direction B. A first stator 120 is disposed from the end of the coil 102 in the first direction A to the inner periphery. That is, the first stator 120 includes a first end plate 121 that forms the end face in the first direction A and a first cylindrical portion 122 that is disposed around the inner periphery of the coil 102. The first stator 120 is also made of the same iron-based magnetic material as the yoke 110. However, the wall thickness of the first cylindrical portion 122 is relatively thin to adjust the magnetic flux density. This is because the wall thickness of the first cylindrical portion 122 also affects the magnetic circuit of the permanent magnet 141. The effect of this magnetic circuit will be discussed later.

[0014] A second stator 130 is disposed in the second direction B of the coil 102, extending from the axial end to the inner periphery. That is, the second stator 130 is disposed opposite the first stator 120. The second stator 130 is also made of an iron-based magnetic material, like the yoke 110 and the first stator 120. The second stator 130 also includes a second end plate 131 that covers the end in the second direction B and a second cylindrical portion 132 that is disposed on the inner periphery of the coil 102. The thickness of the second cylindrical portion 132 is sufficiently greater than the thickness of the first cylindrical portion 122. When the coil 102 is energized and excited, magnetic flux can flow efficiently within the second cylindrical portion 132.

[0015] A cylindrical mover 140 is disposed on the inner periphery of the first cylindrical portion 122 of the first stator 120. The outer diameter of the mover 140 is approximately 25 millimeters, which is slightly smaller than the inner diameter of the first cylindrical portion 122 of the first stator 120. Therefore, the mover 140 is slidably held on the first stator 120. A permanent magnet 141 is disposed in the center of the mover 140, and a first magnetic member 142 is disposed in a first direction A of the permanent magnet. The first magnetic member 142 is disposed on the opposite side of the permanent magnet 141 from the second stator 130 in relation to the second stator 130. A second magnetic member 143 is disposed in a second direction B of the permanent magnet 141. In relation to the second stator 130, the second magnetic member 143 is disposed on the second stator 130 side of the permanent magnet 141.

[0016] The permanent magnet 141 is a neodymium magnet, and the first magnetic member 142 and the second magnetic member 143 are made of the same iron-based magnetic material as the yoke 110 and the like. The permanent magnet 141, the first magnetic member 142, and the second magnetic member 143 are cylindrical and have approximately the same outer diameter, but the outer diameter of the permanent magnet 141 is slightly smaller than the outer diameters of the first magnetic member 142 and the second magnetic member 143. This is to prevent the outer periphery of the permanent magnet 141 from directly contacting the first cylindrical portion 122 of the first stator 120. Therefore, microscopically, the mover 140 slides on the inner periphery of the first cylindrical portion 122 of the first stator 120 via the first magnetic member 142 and the second magnetic member 143. The axial length of the mover 140 is approximately 40 millimeters, of which the axial length of the permanent magnet 141 is approximately 5 millimeters. The axial lengths of the first magnetic member 142 and the second magnetic member 143 are the same. The axial length of the permanent magnet 141 is indicated by h2-h1 in FIG. 1, and the symbols h, h1, and h2 in FIG. 1 will be explained later.

[0017] A plunger 144 is disposed at the central axis of the mover 140. The plunger 144 is made of a non-magnetic material such as stainless steel. As shown in FIG. 7 , the permanent magnet 141, the first magnetic member 142, and the second magnetic member 143 are fixed by crimping using the plunger 144. The tip of the non-magnetic plunger 144 in the first direction A is exposed to the first direction A of the mover 140. FIG. 1 shows the first position in which the mover 140 is displaced to the maximum in the first direction A. At this first position, the magnetic gap between the mover 140 and the second stator 130 is maximized. When the mover 140 is in the first position, the tip of the plunger 144 in the first direction A abuts the first end plate 121 of the first stator 120. This restricts displacement of the mover 140 in the first direction A when the mover 140 is in the first position. That is, the mover 140 is held by the first stator 120 so as not to be displaced in the first direction A.

[0018] The state shown in FIG. 4 is the second position, where the mover 140 is displaced to the maximum in the second direction B. This second position is also the position where the magnetic gap between the mover 140 and the second stator 130 is smallest. In this example, the mover 140 abuts against the second stator 130, preventing a magnetic gap from being generated. That is, when the mover 140 is in the second position, the mover 140 abuts against the second stator 130, restricting the mover 140 from displacing in the second direction B. In other words, when the mover 140 is in the second position, the mover 140 is held by the first stator 120 and the second stator 130 so as not to displace in the second direction B. The mover 140 is displaceable between a first position where the magnetic gap is largest and a second position where the magnetic gap is smallest. Regarding the relationship between the first position and the second position, the direction from the first position toward the second position is the second direction. Conversely, the direction from the second position to the first position is the first direction.

[0019] 7 and 8, a spring member 150 that applies a biasing force to the mover 140 is disposed on the inner periphery of the second cylindrical portion 132 of the second stator 130. The spring member 150 is a compression spring, and the direction of the biasing force is the first direction A. That is, this is also the direction in which the mover 140 moves from the second position in the second direction B toward the first position. This is also the direction in which the magnetic gap between the mover 140 and the second stator 130 widens.

[0020] Next, an example of use of the solenoid 100 will be described with reference to FIG. 7 . In this example, the solenoid 100 is used in a clutch 200 that switches between transmitting and not transmitting the vehicle's propulsion driving force to an axle 202. Reference numeral 201 denotes an input shaft, and in the case of an electric vehicle, the input shaft 201 is connected to a drive motor. Note that in the case of an electric vehicle, the drive motor may be a motor generator that is also capable of generating electricity. The drive motor is not limited to an electric vehicle, and may be engine-driven. More specifically, the drive motor's propulsion force is transmitted to left and right axles 202. FIG. 7 shows only one of the axles 202. Therefore, a differential gear that adjusts the difference in rotational speed between the left and right axles 202 is disposed between the drive motor and the input shaft 201. Although the differential gear is not shown in FIG. 7 , the input shaft 201 rotates at a rotational speed adjusted by the differential gear.

[0021] 7, when the clutch 200 is in the off state, the driving force from the input shaft 201 is not transmitted to the axle 202. The clutch 200 is used to switch between a 4WD state in which the driving force of the drive motor is transmitted to all four wheels (front, rear, left, and right), and a 2WD state in which the driving force of the drive motor is transmitted only to the left and right rear wheels. That is, when the clutch 200 is in the on state, the driving force of the drive motor is transmitted to the front wheels as well, resulting in a 4WD state. When the clutch 200 is in the off state, the driving force of the drive motor is not transmitted to the front wheels, resulting in a 2WD state.

[0022] The axle 202 is fitted into the clutch output portion 203 and fixed by a fixing ring 204. Therefore, the axle 202 and the clutch output portion 203 rotate together. The rotation of the axle 202 and the clutch output portion 203 is supported by an output side bearing 205 and an input side bearing 206. The output side bearing 205 is interposed between the clutch housing 207 and the clutch output portion 203. The input side bearing 206 is interposed between the input shaft 201 and the clutch output portion 203.

[0023] A clutch input portion 208 is disposed on the outer periphery of the input shaft 201. The input shaft 201 and the clutch input portion 208 are spline-connected, and the rotation of the input shaft 201 is transmitted to the clutch input portion 208. The clutch input portion 208 is displaceable in the axial direction of the input shaft 201. The displacement of the clutch input portion 208 in the axial direction is performed by a clutch lever 209. That is, the clutch lever 209 is rotatable about a rotation center 210, and rotates in response to the displacement of the plunger 144 of the solenoid 100.

[0024] The clutch input portion 208 and the clutch output portion 203 form a dog clutch. That is, an input gear portion 211 is formed in the clutch input portion 208, and an output gear portion 212 is formed in the clutch output portion 203. When the clutch 200 is in the on state, the splines of the input gear portion 211 and the splines of the output gear portion 212 mesh with each other. As a result, when the clutch 200 is in the on state, the rotation of the input shaft 201 is efficiently transmitted to the axle 202.

[0025] The clutch housing 207, clutch input portion 208, clutch output portion 203, and clutch lever 209 are all made of iron-based materials. The clutch housing 207 is fixed to the opening of the drive motor. An oil seal 213 is disposed between the clutch housing 207 and the axle 202 to prevent lubricating oil from the drive motor from leaking to the outside. A diaphragm 214 is also disposed between the clutch housing 207 and the solenoid 100 to prevent foreign matter from the drive motor from entering the solenoid 100. Specifically, the inner periphery of the diaphragm 214 is held by the plunger retaining groove 145 of the plunger 144. The outer periphery of the diaphragm 214 is held by the clutch retaining groove 215 of the clutch housing 207.

[0026] Next, we will explain the situation in which the solenoid 100 configured as described above holds the first and second positions, displaces from the first position to the second position, and displaces from the second position to the first position. As described above, FIG. 1 shows the state in which the first position is held. The magnetic flux generated by the permanent magnet 141 in this state is shown in FIG. 2 . In this state, the entire axial length of the permanent magnet 141 and at least a portion of the axial lengths of the first magnetic member 142 and the second magnetic member 143 face the first cylindrical portion 122 of the first stator 120. Therefore, the first loop K of magnetic flux generated by the permanent magnet 141 enters the second magnetic member 143 from the end face of the permanent magnet 141 in the second direction B and then enters the first cylindrical portion 122 of the first stator 120. The magnetic flux that flows through the first cylindrical portion 122 then enters the first magnetic member 142 and returns to the end face of the permanent magnet 141 in the first direction A.

[0027] This first loop K has a small air gap in the magnetic circuit and rotates only slightly near the permanent magnet 141, so the magnetic force of the permanent magnet 141 can be efficiently utilized. As described above, the tip of the plunger 144 in the first direction A abuts against the first end plate 121 of the first stator 120, so the mover 140 can reliably hold the first position. However, as described above, the first cylindrical portion 122 is set to have a relatively thin wall thickness. Therefore, the magnetic circuit is constricted by the first cylindrical portion 122, and the holding force due to the magnetic flux density of the first loop K of the permanent magnet 141 is approximately 20 Newtons.

[0028] When the mover 140 is held in the first position, a second loop L, shown by a dashed line in FIG. 2 , may also be considered. In the second loop L, magnetic flux from the second-direction B end of the permanent magnet 141 flows from the second magnetic member 143 through the magnetic gap to the second cylindrical portion 132 of the second stator 130 and enters the yoke 110 from the second end plate 131. The magnetic flux then returns from the first stator 120 to the first-direction A end of the permanent magnet 141 via the first magnetic member 142. This second loop L acts in a direction that moves the mover 140 in the second direction B. However, the second loop L does not significantly contribute to reducing the force holding the first position. This is because a large magnetic gap exists between the mover 140 and the second stator 130 in the second loop L. As a result, the magnetic gap acts as resistance in the magnetic circuit, preventing the magnetic flux density from generating a large magnetic force.

[0029] In this example, a spring member 150 is used. The spring member 150 applies a biasing force to the mover 140 in the same direction as the first loop K. That is, the biasing force presses the mover 140 in the first direction A. The biasing force of this spring member 150 is, for example, about 40 Newtons, which, combined with the holding force of the permanent magnet 141 of 20 Newtons, holds the first position with a force of about 60 Newtons.

[0030] Next, a situation in which the rotor is displaced from the first position to the second position will be described. In this case, as shown in FIG. 3 , a positive potential is applied to the coil 102 to generate a third loop M. The third loop M has the same direction as the second loop L described above. That is, the current applied to the coil 102 is a positive current that generates a magnetic force in the same direction as the magnetic flux of the permanent magnet 141. The third loop M formed by the coil 102 forms a magnetic circuit around the coil 102, including the yoke 110, the first stator 120, the mover 140, and the second stator 130. The third loop M has a large magnetic flux density and generates a large attractive force in the magnetic gap between the mover 140 and the second stator 130. The magnetic attractive force of the coil 102 is much greater than the magnetic holding force of the first loop K formed by the permanent magnet 141. Therefore, the mover 140 is displaced in a direction that narrows the magnetic gap due to the magnetic attractive force of the coil 102. The direction of this displacement is the direction in which the mover 140 moves toward the second stator 130, and is also the direction B. In addition, it is also the direction opposite to the biasing force of the spring member 150.

[0031] The state shown in FIG. 4 is the state in which the current supply to the coil 102 is stopped in the displaced state. As shown in FIG. 4 , at the second position, at least a portion of the permanent magnet 141 in the axial direction and the entire axial length of the second magnetic member 143 do not face the first cylindrical portion 122 of the first stator 120. More specifically, the permanent magnet 141 hardly faces the first cylindrical portion 122 of the first stator 120. Therefore, a large air gap is generated between the end of the permanent magnet 141 in the second direction B and the first cylindrical portion 122, causing the fourth loop N to act in the direction from the second position to the first position, i.e., in the first direction A, due to the presence of the air gap. However, due to the large air gap, the magnetic attractive force of the fourth loop N is small. In addition, as described above, the thickness of the first cylindrical portion 122 is thin, and the magnetic attractive force of the fourth loop N is also small due to the influence of the first cylindrical portion 122.

[0032] In contrast, there is almost no air gap in the fifth loop O. In the fifth loop O, magnetic flux from the second direction B end of the permanent magnet 141 flows from the second magnetic member 143 to the second stator 130 and toward the second direction B end of the yoke 110. The magnetic flux that flows axially through the yoke 110 then flows from the first direction A end of the yoke 110 to the first stator 120. It then flows to the first direction A end of the permanent magnet 141 via the first magnetic member 142. Therefore, the magnetic attraction force of the fifth loop O has a greater magnetic flux density than that of the fourth loop N.

[0033] Like the third loop M, the fifth loop O forms a magnetic circuit around the coil 102, including the yoke 110, the first stator 120, the mover 140, and the second stator 130. Although the fifth loop O is long, there are no intervening portions that constrict the magnetic flux. That is, there are no thin portions within the magnetic circuit, such as the first cylindrical portion 122 in the first loop K. Therefore, the fifth loop O is configured to most effectively exert the magnetic force of the permanent magnet 141. Therefore, the fifth loop O has a greater magnetic flux density than the first loop K. If the magnetic attractive force that holds the first loop K in the first position is approximately 20 Newtons, the magnetic attractive force that holds the fifth loop O in the second position is approximately 100 Newtons. The biasing force of the spring member 150 acts in the opposite direction to the magnetic attractive force of the permanent magnet 141 in the fifth loop O. However, the magnetic attractive force of the permanent magnet 141 in the fifth loop O is about 100 Newtons, which exceeds the biasing force of the spring member 150, which is about 40 Newtons. Moreover, the second position is stable because the mover 140 abuts against the second stator 130 without a magnetic gap.

[0034] Next, we will explain the situation when the rotor is displaced from the second position to the first position. In this case, as shown in FIG. 5 , reverse current is applied to the coil 102 to generate a sixth loop P. The sixth loop P forms a magnetic circuit around the coil 102, including the first stator 120, the mover 140, the second stator 130, and the yoke 110. Reverse current is applied by applying a potential to the coil 102 so that a magnetic force is generated in the coil 102 in the opposite direction to the magnetic flux of the permanent magnet 141. When current is applied to the coil 102, a magnetic attraction force is generated in a direction that narrows the magnetic gap, regardless of whether the coil 102 is energized forward or backward. However, since the mover 140 is already in contact with the second stator 130 at the second position, no magnetic gap exists. Therefore, the sixth loop P is not intended to generate a magnetic attraction force in the magnetic gap. The sixth loop P excites the coil 102 in a direction that cancels out the magnetic flux of the fifth loop O of the permanent magnet 141. That is, as described above, the fifth loop O forms a magnetic circuit around the coil 102, including the yoke 110, the first stator 120, the mover 140, and the second stator 130. However, the magnetic circuit orientations of the fifth loop O and the sixth loop are opposite. Therefore, by applying reverse current to the coil 102, the magnetic force of the permanent magnet 141 between the mover 140 and the second stator 130 is canceled out by the magnetic force of the coil 102. This causes the mover 140 to be displaced to the first position by the magnetic attraction force of the fourth loop N. More specifically, the magnetic attraction force of the fourth loop N is generated in the air gap between the second magnetic member 143 of the mover 140 and the first cylindrical portion 122 of the first stator 120. The magnetic forces that generate the magnetic attraction force in this air gap include the magnetic force of the permanent magnet 141 and the excitation force of the sixth loop P due to the reverse current application to the coil 102.

[0035] As described above, the sixth loop P formed by the coil 102 is intended to cancel out the magnetic flux of the fifth loop O of the permanent magnet 141 and to generate a magnetic attraction force in the air gap between the mover 140 of the fourth loop and the first stator 120. Therefore, the excitation force of the coil 102 must also be controlled to correspond to the magnetic flux density of the fifth loop O of the permanent magnet 141. In this example, the magnitude of the excitation force of the coil 102 is varied by duty ratio control. Duty ratio control involves switching between energized and de-energized states at, for example, 100 Hz, and the longer the energization time, the greater the excitation force. A duty ratio of 100% represents the maximum excitation force, and a duty ratio of 0% means that the coil 102 is not excited. In this example, for example, the duty ratio of the coil 102 is 100% when displacing from the first position to the second position, and the duty ratio of the coil 102 is 20% when displacing from the second position to the first position. This 20% is an example, and the excitation force of the sixth loop P by the coil 102 is matched to the magnetic flux density of the fifth loop O of the permanent magnet 141 by duty ratio control.

[0036] The sixth loop P cancels out the magnetic circuit of the fifth loop O of the permanent magnet 141. As a result, the magnetic attraction force generated in the air gap between the mover 140 and the first stator 120 of the fourth loop N is relatively large due to the magnetic force of the permanent magnet 141 and the excitation force of the coil 102. As a result, the magnetic attraction force acts in a direction that narrows the air gap between the second direction B end face (second magnetic member 143) of the permanent magnet 141 and the first cylindrical portion 122 of the first stator 120. The magnetic flux of this fourth loop N displaces the mover 140 in the first direction A, moving it from the second position to the first position. The biasing force of the spring member 150 also contributes to this movement in the first direction from the second position to the first position. For example, assume that it takes 0.5 seconds for the mover 140 to be displaced from the second position to the first position by the magnetic flux of the permanent magnet 141 alone, without the spring member 150. In this case, by adding the spring member 150, the time required for the mover 140 to move from the second position to the first position can be reduced to 0.1 seconds.

[0037] The relationship between the magnetic attractive force of the permanent magnet 141 and the magnetic attractive force due to forward and reverse energization of the coil 102 will be explained again with reference to FIG. 6 . The horizontal axis in FIG. 6 represents the stroke (ST_LG) of the mover 140. A stroke toward the left in FIG. 6 is a stroke toward the first direction A, and at the first position, which is the leftmost position (first direction A), the magnetic gap between the mover 140 and the second stator 130 is maximum. A stroke toward the right is the opposite, moving toward the second direction B. Therefore, at the second position, which is the rightmost position (second direction B), the magnetic gap between the mover 140 and the second stator 130 is minimum.

[0038] The vertical axis in Figure 6 is the magnetic attractive force (MG_AF). The magnetic attractive force increases as the absolute value increases from 0, whether on the positive or negative side. The positive direction corresponds to forward current flow, which coincides with the magnetic flux of the permanent magnet 141. The opposite negative direction corresponds to reverse current flow, which generates a magnetic force in the opposite direction to the magnetic flux of the permanent magnet 141. The reason why the attractive force differs between forward current flow and reverse current flow is because the duty ratio is different, as described above.

[0039] 6, line X indicates the state in which no current is flowing through the coil 102. Therefore, line X represents the magnetic attraction force due to the magnetic flux of the permanent magnet 141. Line Y represents the magnetic attraction force when current is flowing in the forward direction through the coil 102, and line Z represents the magnetic attraction force when current is flowing in the reverse direction through the coil 102.

[0040] The state shown in FIG. 2 where the first position is maintained solely by the permanent magnet 141 is indicated by point X1 in FIG. 6. As described above, the magnetic attractive force at the first position (point X1) is approximately 20 Newtons. This is mainly due to the negative attractive force of the first loop K, and the positive attractive force of the second loop L has almost no effect. Therefore, the first position is maintained by the negative magnetic attractive force of the first loop K. Although the biasing force of the spring member 150 is not shown in FIG. 6, as described above, the biasing force of the spring member 150 is applied in the negative direction to supplement the magnetic attractive force of the first loop K.

[0041] The forward current to the coil 102 shown in FIG. 3 is at point Y1 in FIG. 6. Forward current generates a large magnetic attraction force. Because it is forward current, the magnetic attraction force is also shown in the positive direction. The magnetic attraction force of the third loop M shown in FIG. 3 is approximately 100 Newtons, which is greater than the magnetic attraction force of the permanent magnet 141 in the first loop K plus the biasing force of the spring member 150. Therefore, the mover 140 moves in the second direction B. As the mover 140 moves in the second direction B, the magnetic gap between the mover 140 and the second stator 130 narrows, and the magnetic attraction force increases accordingly. The second position, where the magnetic attraction force is at its maximum, is at point Y2 in FIG. 6.

[0042] The state at point X2 in Figure 6 occurs when the mover 140 moves in the second direction B, the magnetic gap becomes minimum, and then the power supply to the coil 102 is stopped. This is also the state shown in Figure 4, in which a force of approximately 100 Newtons is applied by the fifth loop O of the permanent magnet 141. The fifth loop O exerts an attractive force in the positive direction, the same as the third loop M of the coil 102. At this time, the attractive force of the fourth loop N acts in the opposite direction (negative direction), but as described above, this attractive force of the fourth loop N has almost no effect. Even if the biasing force of the spring member 150 is approximately 40 Newtons in the negative direction, the second position is achieved.

[0043] The sixth loop P caused by the reverse current flowing through the coil 102 shown in FIG. 5 is indicated by point Z1 in FIG. 6. Because the current is flowing in the reverse direction, the magnetic attractive force is negative, and the absolute value of the magnetic attractive force is approximately 70 Newtons. This acts in a direction that cancels out the attractive force of the fifth loop O, which is positive due to the permanent magnet 141. In this embodiment, the biasing force of the spring member 150 is applied, so the attractive force of the fourth loop N is greater, and the mover 140 moves in the first direction A. As described above, the attractive force of the fourth loop N is a magnetic attractive force generated in the air gap between the mover 140 and the first stator 120, and the attractive force is generated by the magnetic force of the permanent magnet 141 and the excitation force of the coil 102.

[0044] When the mover 140 moves in the first direction A and reaches the first position, it enters the state shown in FIG. 2. In FIG. 2, no reverse current is flowing through the coil 102, but if reverse current is flowing when the mover 140 moves, the magnetic attraction force shown at point Z2 in FIG. 6 is generated by the coil 102. The absolute value of this force is approximately 40 Newtons in the negative direction. In this state, the attraction force due to the first loop K of the permanent magnet 141, the biasing force of the spring member 150, and the attraction force due to reverse current flowing through the coil 102 all act in the negative direction.

[0045] Next, we will provide additional explanations of the holding force of the permanent magnet 141 in the holding state at the first position shown in FIG. 2 and the holding force of the permanent magnet 141 in the holding state at the second position shown in FIG. In the above explanation, the first loop K in the first position has a small air gap in the magnetic circuit and rotates only slightly near the permanent magnet 141, allowing for efficient use of the magnetic force of the permanent magnet 141. Furthermore, we have explained that the fourth loop N in the second position shown in FIG. 4 acts in the first direction A due to the presence of the air gap, but its magnetic attractive force is small. Furthermore, we have explained that the magnetic attractive force of the fifth loop O in the second position has a greater magnetic flux density than the fourth loop N. The size of the air gap is relevant to the first loop K, fourth loop N, and fifth loop O caused by the permanent magnet 141.

[0046] The stator magnetic distance h (shown in FIG. 1 ) is the distance in the axial direction of the inner periphery of the first stator 120 where one end in the first direction A coincides with the end face of the first end plate 121 in the first direction and the other end in the second direction B coincides with the end face of the first cylindrical portion 122 in the second direction. The permanent magnet first surface distance h1 (shown in FIG. 1 ) is the distance in the axial direction of the mover 140 where one end in the first direction A coincides with the end face of the first end plate 121 in the first direction and the other end in the second direction B coincides with the end face of the permanent magnet 141 in the first direction. The permanent magnet second surface distance h2 (shown in FIG. 1 ) is the distance in the axial direction of the mover 140 where one end in the first direction A coincides with the end face of the first end plate 121 in the first direction and the other end in the second direction B coincides with the end face of the permanent magnet 141 in the second direction. The stator magnetic distance h, the permanent magnet first surface distance h1, and the permanent magnet second surface distance h2 are all related to the size of the air gap.

[0047] The horizontal axis of Figure 12 represents the first magnetic ratio, which is the ratio (h1 / h) of the first permanent magnet surface distance h1 to the stator magnetic distance h, and the vertical axis represents the second magnetic ratio, which is the ratio (h2 / h) of the second permanent magnet surface distance h2 to the stator magnetic distance h. Within the range indicated by the dark lines in Figure 12, the mover 140 can be held at the first and second positions by the magnetic force of the permanent magnet 141. In other words, within the lightly shaded range in Figure 12, the magnetic force of the permanent magnet 141 cannot be effectively utilized, and the mover 140 cannot be held at the first and second positions. The content of Figure 12 shows the range in which the magnetic force of the permanent magnet 141 is large enough to hold the mover 140 at the first and second positions; the considerations in Figure 12 do not include the biasing force of the spring member 150.

[0048] The dark area in FIG. 12 corresponds to the first magnetic ratio h1 / h shown on the horizontal axis, which is between 48% and 91%. The dark area corresponds to the second magnetic ratio h2 / h shown on the vertical axis, which is between 82% and 110%. Setting the permanent magnet first surface distance h1 and the permanent magnet second surface distance h2 so that they fall within this range allows for effective utilization of the magnetic force of the permanent magnet 141. The permanent magnet second surface distance h2 is longer than the permanent magnet first surface distance h1 by the thickness of the permanent magnet. Therefore, the second magnetic ratio (h2 / h) is greater than the first magnetic ratio (h1 / h). Therefore, when the second magnetic ratio (h2 / h) is 82% of its minimum value, the first magnetic ratio (h1 / h) is physically smaller than 82%. Similarly, when the first magnetic ratio (h1 / h) is 91% of its maximum value, the second magnetic ratio (h2 / h) is physically greater than 91%.

[0049] In the example shown in FIG. 1, the thickness (h2-h1) of the permanent magnet 141 is approximately 5 millimeters, and the axial length of the mover 140 is approximately 40 millimeters. With these dimensions, the permanent magnet second surface distance h2 is approximately 23 millimeters, and the stator magnetic distance h is approximately 25 millimeters. In this case, the permanent magnet first surface distance h1 is approximately 18 millimeters, the first magnetic ratio is 72%, and the second magnetic ratio is 92%. As shown by point D in FIG. 12, this point is within the dark region, and it can be confirmed that both the first position and the second position can be maintained by the magnetic force of the permanent magnet 141.

[0050] The thickness (h2-h1) of the permanent magnet 141 cannot be determined in a generalized manner because the manufacturability of the permanent magnet 141 changes depending on the size of the solenoid 100. In the example described above, the stator magnetic distance h was approximately 25 millimeters, and the ratio of the thickness (h2-h1) of the permanent magnet 141, which was approximately 5 millimeters (hereinafter referred to as the "thickness ratio"), to that was 20%. This thickness ratio also varies depending on the size of the solenoid 100, so it cannot be determined in a generalized manner. However, once the stator magnetic distance h, the permanent magnet first surface distance h1, and the permanent magnet second surface distance h2 are determined, the thickness ratio can also be determined. In Figure 12, the dashed line E indicates a thickness ratio of 35%, and the dashed line F indicates a thickness ratio of 15%. Regardless of the thickness ratio, the magnetic force of the permanent magnet 141 can maintain the first and second positions as long as it is within the dark region.

[0051] FIG. 12 shows an analysis of the range in which the magnetic force of the permanent magnet 141 is greater than or equal to the force required to hold the permanent magnet 141 in the first and second positions. The dark regions represent the range in which the magnetic force of the permanent magnet 141 cannot hold the permanent magnet 141 in the magnetic circuit unless the dark regions are within this range. Qualitative analysis of the analysis results reveals that the upper limit of the second magnetic ratio (h2 / h), 110%, is a constant value that defines the range in which the magnetic force of the permanent magnet 141 reaches the first cylindrical portion 122 at the first position. Similarly, the lower limit of the first magnetic ratio (h1 / h), 48%, is a constant value that defines the range in which the magnetic force of the permanent magnet 141 reaches the first cylindrical portion 122 at the second position. Both values ​​are related to the size of the air gap.

[0052] Next, the on / off switching of the clutch 200 using the solenoid 100 will be described. FIG. 7 shows the clutch 200 in its off state, with the solenoid 100 in the first position. As described above, in the first position, the magnetic attractive force of the permanent magnet 141 is generated by the first loop K. In this state, the magnetic attractive force is approximately 20 Newtons. However, the spring member 150 exerts a biasing force of approximately 40 Newtons, which reliably maintains the first position. In the example shown in FIG. 7, the plunger 144 is displaced to the maximum in the first direction A in the first position. This displacement of the plunger 144 is transmitted to the clutch input portion 208 via the clutch lever 209. As the clutch lever 209 rotates around the rotation center 210, the clutch input portion 208 is displaced in the second direction B. As a result, the input gear portion 211 of the clutch input portion 208 disengages from the output gear portion 212 of the clutch output portion 203. As a result, the input shaft 201 rotates freely, and no rotational force is transmitted to the axle 202 .

[0053] As described above, the on state of the clutch 200 is maintained by the fifth loop O of the permanent magnet 141. In this state, the mover 140 is in the second position, as shown in FIG. 8 . The clutch lever 209 rotates around the rotation center 210, displacing the clutch input portion 208 in the first direction. This causes the input gear portion 211 of the clutch input portion 208 to mesh with the output gear portion 212 of the clutch output portion 203. As a result, the output of the input shaft 201 is reliably transmitted to the axle 202.

[0054] As described above, the clutch 200 is switched on and off by energizing the coil 102. When the clutch 200 is in the off state in FIG. 7 and the solenoid 100 is in the first position, forward current is applied to the coil 102, generating a magnetic attraction force between the magnetic gap between the armature 140 and the second stator 130. This corresponds to point Y1 in FIG. 6 . This places the solenoid 100 in the second position and turns the clutch 200 on. Conversely, when the clutch 200 is in the on state in FIG. 8 and the solenoid 100 is in the second position, reverse current is applied to the coil 102. This corresponds to point Z1 in FIG. 6 . The fifth loop O of the permanent magnet 141 is canceled by the sixth loop P of the magnetic circuit of the coil 102. This also generates a magnetic attraction force in the air gap between the armature 140 and the first stator 120, displacing the solenoid 100 to the first position. According to this example, the coil 102 is energized only when the clutch 200 is switched on and off. Since the coil 102 is energized for an extremely short time, the power consumed by the coil 102 can be minimized.

[0055] Next, another embodiment will be described with reference to Figure 9. In the above-described embodiment, the second stator 130 is formed integrally with the second end plate 131 and the second cylindrical portion 132. This is a desirable embodiment because it can reliably hold the second stator 130. However, when the mover 140 is displaced from the first position to the second position in the second direction B, the mover 140 collides with the second stator 130, and the impact is directly applied to the second stator 130.

[0056] In other embodiments, a laminated plate 1311 is used instead of the second end plate 131. In the example of FIG. 9, five laminated plates 1311 made of spring steel, which is a magnetic material, are stacked. Each of the five laminated plates 1311 has the same ring shape. Furthermore, the five laminated plates 1311 are simply stacked and are not connected to each other. However, the number of laminated plates 1311 is not limited to five. Any ring shape that can support the second cylindrical portion 132 may be used.

[0057] The yoke 110 has a yoke bottom 112 in addition to a yoke cylindrical portion 111 so as to hold the lamination plate 1311. The yoke cylindrical portion 111 covers the outer periphery of the coil 102, and the yoke bottom 112 is formed to cover the lamination plate 1311 in the second direction B. A holding step 115 that holds the lamination plate 1311 in the second direction B is formed at the boundary between the yoke cylindrical portion 111 and the yoke bottom 112. The lamination plate 1311 in the first direction A contacts the bobbin 101.

[0058] The outer peripheral surface of the lamination plate 1311 is in direct contact with the yoke cylindrical portion 111. The inner and outer peripheral portions of the surface of the lamination plate 1311 facing in the second direction B are in direct contact with the retaining step 115. This direct contact magnetically connects the lamination plate 1311 to the yoke 110. The outer peripheral surface of the lamination plate 1311 contacts the yoke cylindrical portion 111 through a fitting engagement. Alternatively, the outer peripheral surface of the lamination plate 1311 may be fixed to the yoke cylindrical portion 111. A space 113 is formed between the lamination plate 1311 in the second direction B and the yoke bottom 112, allowing the lamination plate 1311 to move in the second direction B. As described above, the lamination plate 1311 is in contact with the bobbin 101 in the first direction A, and therefore, in the state shown in FIG. 9 , the lamination plate 1311 cannot move in the first direction A.

[0059] Similar to the above-described embodiments, the second cylindrical portion 132 is disposed on the inner circumferential side of the coil 102 and is disposed opposite the mover 140 across a magnetic gap. In the embodiment shown in Fig. 9, the second cylindrical portion 132 is disposed on the inner circumferential side of the coil 102 so as to be displaceable in the first direction A and the second direction B. A holding protrusion 1321 is formed on the central axis side of the second cylindrical portion 132 in the second direction B.

[0060] The inner periphery of the ring-shaped lamination plate 1311 faces the outer periphery of the holding protrusion 1321. The inner periphery of the lamination plate 1311 is in direct contact with the outer periphery of the holding protrusion 1321. The inner periphery of the lamination plate 1311, facing the first direction A, is in direct contact with the second cylindrical portion 132. This direct contact magnetically connects the inner periphery of the lamination plate 1311 to the second cylindrical portion 132. The lamination plate 1311 holds the second cylindrical portion 132 on the inner periphery of the coil 102, allowing it to move in the first direction A and the second direction B. The inner periphery of the lamination plate 1311 and the outer periphery of the holding protrusion 1321 are in contact by fitting. However, the inner periphery of the lamination plate 1311 may be fixed to the outer periphery of the holding protrusion 1321. The magnetic circuit connection to the second cylindrical portion 132 is ensured by the inner peripheral surface of the laminated plate 1311 and the inner peripheral portion of the surface facing the first direction A.

[0061] 9, the stacking plate 1311 is sandwiched between the holding step 115 and the bobbin 101. In this state, the stacking plate 1311 is in its natural state. That is, in the state shown in FIG. 9, no displacement force of the stacking plate 1311 itself is generated on either the bobbin 101 side or the space 113 side. Therefore, the displacement force of the stacking plate 1311 in the first direction A is not applied to the second cylindrical portion 132.

[0062] In the state shown in Fig. 9 , when the coil 102 is energized to generate the third loop M, a large magnetic attraction force is generated in the magnetic gap between the mover 140 and the second stator 130. This magnetic attraction force displaces the mover 140 from the first position to the second position. That is, the mover 140 moves in the second direction B and collides with the second cylindrical portion 132 of the second stator 130. This collision applies a force to the second cylindrical portion 132 in the second direction B. In the embodiment shown in Fig. 9 , the displacement of the second cylindrical portion 132 in the second direction B due to this collision is mitigated by the bending of the laminated plate 1311.

[0063] As described above, in the state shown in FIG. 9 in which the lamination plate 1311 is in contact with the bobbin 101, the displacement force of the lamination plate 1311 in the first direction A is not applied to the second cylindrical portion 132. However, when the second cylindrical portion 132 is displaced in the second direction B due to a collision with the mover 140, the lamination plate 1311 separates from the bobbin 101. As a result, the lamination plate 1311 bends, and a displacement force that attempts to restore the lamination plate 1311 is generated. The second cylindrical portion 132 is supported by the displacement force of the lamination plate 1311 in the first direction A. The lamination plate 1311 holding the second cylindrical portion 132 on the inner circumferential side of the coil 102 so that it can be displaced in the first direction A and the second direction B refers to the state after the lamination plate 1311 is displaced. In other words, the second cylindrical portion 132 is allowed to be displaced in the second direction B from the state shown in FIG. 9 , and its return to the first direction A from the displaced state is described as being displaceable in the first direction A and the second direction B.

[0064] The displacement force of the laminated plate 1311 in the first direction A is a force generated by the collision of the mover 140, and therefore corresponds to the collision force of the mover 140, and the collision force of the mover 140 can be alleviated by this displacement force of the laminated plate 1311 in the first direction A. The alleviation of the collision force of the mover 140 also leads to quieter operation of the solenoid 100. Furthermore, it also leads to improved durability of the mover 140 and the second stator 130.

[0065] The embodiment shown in Figure 10 is yet another embodiment that is a modification of the embodiment shown in Figure 9. In the embodiment of Figure 10, a buffer material 114 is disposed in the space 113 between the yoke bottom 112 and the laminated plate 1311. A resilient rubber material is preferably used for the buffer material 114. For example, fluororubber is used. In addition to stress relief due to deformation of the laminated plate 1311, stress relief due to deformation of the buffer material 114 can also be utilized. This further improves the quietness of the solenoid 100. Furthermore, the durability of the mover 140 and the second stator 130 is also improved.

[0066] In the example of Fig. 10, the buffer material 114 is disposed in the space 113, but the buffer material 114 may also be disposed in other locations. For example, the buffer material 114 may be disposed in the magnetic gap between the mover 140 and the second stator 130. Furthermore, although it is effective to use the buffer material 114 together with the laminated plate 1311, it is also possible to dispose the buffer material 114 in the magnetic gap of the solenoid 100 that does not use the laminated plate 1311, as in the example shown in Fig. 1.

[0067] FIG. 11 shows an example in which the solenoid 100 of the embodiment shown in FIG. 9 is used to switch the clutch 200 on and off. In this example, the yoke bottom 112 of the yoke 110 is interposed between the space 113 and the diaphragm 214. As a result, the yoke bottom 112 forms the space 113 that allows the laminated plate 1311 to flex, while also providing a seating surface on which the diaphragm 214 sits. Compared to the embodiment shown in FIG. 7, this example is quieter because the laminated plate 1311 is used as a countermeasure against operating noise. However, the use of the laminated plate 1311 requires the space 113 that allows the laminated plate 1311 to flex. As a result, the seating surface of the diaphragm 214 moves.

[0068] In the above-described embodiment, the spring member 150 is used to supplement the magnetic attractive force of the permanent magnet 141. At the second position where the magnetic attractive force of the permanent magnet 141 is strong, the spring member 150 biases in a direction that weakens the magnetic attractive force. Conversely, at the first position where the magnetic attractive force of the permanent magnet 141 is weak, the spring member 150 biases in a direction that reinforces the magnetic attractive force. This is a desirable method because it can shorten the time required for displacement from the second position to the first position. However, it is possible to eliminate the spring member 150 if necessary. This can contribute to size reduction and cost reduction by reducing the number of parts.

[0069] In the above-described embodiment, the permanent magnet 141 is disposed in the middle of the mover 140, and the axial lengths of the first magnetic member 142 and the second magnetic member 143 are the same. This is an arrangement that achieves a good balance in the axial direction of the mover 140. However, the axial position of the permanent magnet 141 on the mover 140 can be changed as appropriate. The axial position of the permanent magnet 141 is changed particularly depending on the positional relationship between the permanent magnet 141 and the first cylindrical portion 122 of the first stator 120 at the first position and the second position.

[0070] Furthermore, in the above-described embodiment, the mover 140 is in direct contact with the second stator 130 at the second position. This is a desirable example because it allows the magnetic gap between the mover 140 and the second stator 130 to be zero at the second position. However, it is possible to interpose a buffer material between the mover 140 and the second stator 130 at the second position. As the buffer material, a flexible material may be attached to the mover 140 or the second stator 130. It is also possible to plate a buffer material on at least one of the contact surfaces between the mover 140 and the second stator 130. Furthermore, while the above-described dimensions and materials are desirable examples, the size and material can be changed depending on the application.

[0071] In the above example, the coil 102 is energized in the forward direction to switch from the first position to the second position. This is a desirable mode because the direction of the magnetic flux from the coil 102 coincides with the direction of the magnetic flux from the permanent magnet 141. However, when a magnetic gap exists between the mover 140 and the second stator 130, a magnetic attraction force is generated in the magnetic gap whether the coil 102 is energized in the forward direction or in the reverse direction. Therefore, it is possible to energize the coil 102 in the reverse direction to switch from the first position to the second position.

[0072] Furthermore, in the above example, when switching from the second position to the first position, the magnetic force of the permanent magnet 141 is cancelled out by reversely energizing the coil 102. Here, the cancellation in the present disclosure is not limited to an example in which the excitation force of the coil 102 and the magnetic force of the permanent magnet 141 are exactly the same. Rather, it is difficult to control the excitation force of the coil 102 and the magnetic force of the permanent magnet 141 to be equal. Therefore, cancellation in the present disclosure means that the excitation force of the coil 102 acts in a direction that cancels out the magnetic force of the permanent magnet 141.

[0073] Furthermore, the above is a preferred example of use of the present disclosure, and the solenoid 100 of the present disclosure is suitable for use in a vehicle to switch between power transmission and non-transmission of the clutch 200. However, the use of the solenoid 100 of the present disclosure is not limited to the clutch 200. As long as the first position and the second position can be maintained by the magnetic force of the permanent magnet 141, the solenoid 100 can be used in a wide range of applications.

[0074] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, in which the subsequent clause alternatively refers to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, in which the subsequent clause refers to another multiple dependent clause. The clauses described in these multiple dependent forms define multiple technical ideas.

[0075] (Technical Idea 1) A rotor (102) comprising: a cylindrical coil (102) that is excited when energized; a first stator (120) that is arranged on the inner periphery of the coil and that forms a magnetic circuit when energized; a second stator (130) that is arranged on the inner periphery of the coil facing the first stator and that forms a magnetic circuit together with the first stator when energized; a yoke (110) that is arranged on the outer periphery of the coil and that forms a magnetic circuit when energized; and a mover (140) that is arranged on the inner periphery of the coil and on the inner periphery of the first stator so as to be slidable on the inner periphery of the first stator, and that is arranged across a magnetic gap from the second stator, and that is displaceable between a first position where the magnetic gap is maximum and a second position where the magnetic gap is minimum, The mover is provided with a permanent magnet (141), and at the first position, a magnetic circuit is formed by the first stator and the mover due to the magnetic force of the permanent magnet, and at the second position, a magnetic circuit is formed by the first stator, the second stator, the yoke, and the mover, and the mover is held at the second position due to the magnetic force of the permanent magnet, and when the mover is held at the first position and the second position, the coil is not energized, and when the mover is at the first position, energizing the coil generates a magnetic attraction force in the magnetic gap between the mover and the second stator, and displaces the mover to the second position, When the movable member is in the second position, a reverse current is applied to the coil, generating a magnetic force in the opposite direction to the magnetic flux of the permanent magnet. This causes the magnetic force of the permanent magnet between the movable member and the second stator to be canceled out by the magnetic force of the coil, and the magnetic attraction force generated in the air gap between the movable member and the first stator displaces the movable member to the first position. (100)

[0076] (Technical Idea 2) A solenoid according to Technical Idea 1, wherein the permanent magnet is disposed midway in the axial direction of the mover, a first magnetic member (142) is disposed on the opposite side of the permanent magnet from the second stator, and a second magnetic member (143) is disposed closer to the second stator than the permanent magnet, and when the mover is in the first position, the entire axial length of the permanent magnet and at least a portion of the axial length of the first magnetic member and the second magnetic member face the first stator, and when the mover is in the second position, at least a portion of the axial length of the permanent magnet and the entire axial length of the second magnetic member do not face the first stator.

[0077] (Technical Idea 3) A solenoid according to Technical Idea 1 or Technical Idea 2, in which the current applied to the coil when the mover is displaced from the first position to the second position is a positive current that generates a magnetic force in the same direction as the magnetic flux of the permanent magnet.

[0078] (Technical Idea 4) A solenoid according to any one of Technical Ideas 1 to 3, wherein when the direction from the second position toward the first position is defined as a first direction, the movable element is held so as not to be displaced in the first direction when the movable element is in the first position.

[0079] (Technical Idea 5) A solenoid according to Technical Idea 4, in which a plunger (144) made of a non-magnetic material is formed on the movable element and exposed in the first direction of the movable element, and when the movable element is in the first position, the plunger abuts against the first stator to restrict displacement of the movable element in the first direction.

[0080] (Technical Idea 6) A solenoid according to any one of Technical Ideas 1 to 5, wherein when the direction from the first position to the second position is defined as a second direction, the movable element is held so as not to be displaced in the second direction when the movable element is in the second position.

[0081] (Technical Idea 7) The solenoid according to Technical Idea 6, wherein when the mover is in the second position, the mover abuts against the second stator to restrict displacement of the mover in the second direction.

[0082] (Technical Idea 8) A solenoid according to any one of Technical Ideas 1 to 7, comprising a spring member (150) that applies a biasing force to the movable element in a first direction, when the direction from the second position toward the first position is defined as a first direction.

[0083] (Technical Idea 9) A solenoid according to any one of Technical Ideas 1 to 8, wherein the second stator includes a second cylindrical portion (132) and a laminated plate (1311), the second cylindrical portion is disposed on the inner periphery of the coil, facing the mover across a magnetic gap, and capable of being displaced in a first direction and a second direction, the laminated plate is formed by laminating a plurality of ring-shaped plates, and the inner periphery is magnetically connected to the second cylindrical portion and the outer periphery is magnetically connected to the yoke, thereby holding the second cylindrical portion on the inner periphery of the coil so that it can be displaced in the first direction and the second direction, when the mover is displaced from the first position to the second position, the laminated plate bends and the second cylindrical portion is displaced in the second direction.

[0084] (Technical Idea 10) The solenoid according to Technical Idea 9, wherein the yoke includes a cylindrical yoke portion (111) that covers the outer periphery of the coil and a yoke bottom portion (112) that covers the second direction of the laminated plates of the second stator, and a space (113) is provided between the second stator and the yoke bottom portion so that the laminated plates can be displaced in the second direction.

[0085] (Technical Idea 11) The solenoid according to Technical Idea 10, wherein a buffer material (114) that buffers displacement of the laminated plate in the second direction is disposed in the space between the second stator and the yoke bottom.

[0086] (Technical Idea 12) When the direction from the second position toward the first position is defined as a first direction and the direction from the first position toward the second position is defined as a second direction, the first stator (120) comprises a first end plate (121) disposed in the first direction of the coil and a first cylindrical portion (122) disposed on the inner peripheral side of the coil, the axial distance of the inner peripheral side of the first stator (120) at which one end in the first direction coincides with the end face of the first end plate in the first direction and the other end in the second direction coincides with the end face of the first cylindrical portion in the second direction is defined as a stator magnetic distance (h), and the axial distance of the mover (140) at which one end in the first direction coincides with the end face of the first end plate in the first direction and the other end in the second direction coincides with the end face of the permanent magnet in the second direction is defined as a permanent magnet second surface distance (h2), A solenoid according to any one of Technical Ideas 1 to 10, wherein the axial distance of the mover (140) at which one end in the first direction coincides with the end face of the first end plate in the first direction and the other end in the second direction coincides with the end face of the permanent magnet in the first direction is defined as a permanent magnet first surface distance (h1), the permanent magnet second surface distance (h2) is longer than the permanent magnet first surface distance (h1) by the thickness of the permanent magnet, the permanent magnet second surface distance (h2) is 82% or more and 110% or less of the stator magnetic distance (h), and the permanent magnet first surface distance (h1) is 48% or more and 91% or less of the stator magnetic distance (h).

Claims

1. A cylindrical coil (102) that is excited when energized; a first stator (120) that is arranged on the inner periphery of the coil and forms a magnetic circuit when the coil is energized; a second stator (130) that is arranged on the inner periphery of the coil facing the first stator and forms a magnetic circuit together with the first stator when the coil is energized; a yoke (110) that is arranged on the outer periphery of the coil and forms a magnetic circuit when the coil is energized; and a mover (140) that is arranged on the inner periphery of the coil and on the inner periphery of the first stator so as to be slidable on the inner periphery of the first stator, and is arranged with a magnetic gap between it and the second stator, and is displaceable between a first position where the magnetic gap is maximum and a second position where the magnetic gap is minimum. The mover is provided with a permanent magnet (141), and at the first position, a magnetic circuit is formed by the first stator and the mover due to the magnetic force of the permanent magnet, and at the second position, a magnetic circuit is formed by the first stator, the second stator, the yoke, and the mover, and the mover is held at the second position due to the magnetic force of the permanent magnet, and when the mover is held at the first position and the second position, the coil is not energized, and when the mover is at the first position, energizing the coil generates a magnetic attraction force in the magnetic gap between the mover and the second stator, and displaces the mover to the second position, When the movable member is in the second position, a reverse current is applied to the coil, generating a magnetic force in the opposite direction to the magnetic flux of the permanent magnet. This causes the magnetic force of the permanent magnet between the movable member and the second stator to be canceled out by the magnetic force of the coil, and the magnetic attraction force generated in the air gap between the movable member and the first stator displaces the movable member to the first position. (100) 2. The solenoid according to claim 1, wherein the permanent magnet is disposed midway in the axial direction of the mover, a first magnetic member (142) is disposed on the opposite side of the permanent magnet from the second stator, and a second magnetic member (143) is disposed on the second stator side from the permanent magnet, and when the mover is in the first position, the entire axial length of the permanent magnet and at least a portion of the axial length of the first magnetic member and the second magnetic member face the first stator, and when the mover is in the second position, at least a portion of the axial length of the permanent magnet and the entire axial length of the second magnetic member do not face the first stator.

3. A solenoid as described in claim 1, wherein the current applied to the coil when the mover is displaced from the first position to the second position is a positive current that generates a magnetic force in the same direction as the magnetic flux of the permanent magnet.

4. A solenoid as described in claim 1, wherein when the direction from the second position toward the first position is defined as a first direction, the movable element is held so as not to be displaced in the first direction when the movable element is in the first position.

5. A solenoid as described in claim 4, wherein a plunger (144) made of a non-magnetic material is formed on the movable element so as to be exposed in the first direction of the movable element, and when the movable element is in the first position, the plunger abuts against the first stator to restrict displacement of the movable element in the first direction.

6. A solenoid as described in claim 1, wherein when the direction from the first position toward the second position is defined as a second direction, the movable element is held so as not to be displaced in the second direction when the movable element is in the second position.

7. The solenoid according to claim 6, wherein when said movable element is in said second position, said movable element abuts against said second stator, restricting displacement of said movable element in said second direction.

8. The solenoid according to claim 1, further comprising a spring member (150) that applies a biasing force to the movable element in a first direction, where the direction from the second position toward the first position is defined as a first direction.

9. The solenoid of claim 1, wherein the second stator includes a second cylindrical portion (132) and a laminated plate (1311), the second cylindrical portion is disposed on the inner periphery of the coil, facing the mover across a magnetic gap, and capable of being displaced in a first direction and a second direction, the laminated plate is formed by laminating a plurality of ring-shaped plates, and the inner periphery is connected to the second cylindrical portion in a magnetic circuit manner and the outer periphery is connected to the yoke in a magnetic circuit manner, thereby holding the second cylindrical portion on the inner periphery of the coil so that it can be displaced in the first direction and the second direction, and when the mover is displaced from the first position to the second position, the laminated plate bends and the second cylindrical portion is displaced in the second direction.

10. A solenoid as described in claim 9, wherein the yoke includes a cylindrical yoke portion (111) that covers the outer periphery of the coil and a yoke bottom portion (112) that covers the second direction of the laminated plates of the second stator, and a space (113) is provided between the second stator and the yoke bottom portion, allowing the laminated plates to be displaced in the second direction.

11. The solenoid according to claim 10, wherein a buffer material (114) is disposed in the space between the second stator and the bottom of the yoke to cushion displacement of the laminated plate in the second direction.

12. When the direction from the second position toward the first position is defined as a first direction and the direction from the first position toward the second position is defined as a second direction, the first stator (120) comprises a first end plate (121) arranged in the first direction of the coil and a first cylindrical portion (122) arranged on the inner circumferential side of the coil, the axial distance on the inner circumferential side of the first stator (120) at which one end in the first direction coincides with the end face of the first end plate in the first direction and the other end in the second direction coincides with the end face of the first cylindrical portion in the second direction is defined as the stator magnetic distance (h), and the axial distance of the mover (140) at which one end in the first direction coincides with the end face of the first end plate in the first direction and the other end in the second direction coincides with the end face of the permanent magnet in the second direction is defined as the permanent magnet second surface distance (h2), The solenoid of claim 1, wherein the axial distance of the mover (140) at which one end in the first direction coincides with the end face of the first end plate in the first direction and the other end in the second direction coincides with the end face of the permanent magnet in the first direction is defined as a permanent magnet first surface distance (h1), the permanent magnet second surface distance (h2) is longer than the permanent magnet first surface distance (h1) by an amount equal to the thickness of the permanent magnet, the permanent magnet second surface distance (h2) is 82% or more and 110% or less of the stator magnetic distance (h), and the permanent magnet first surface distance (h1) is 48% or more and 91% or less of the stator magnetic distance (h).

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