Solenoid Device

Abstract

To provide a solenoid device capable of ensuring operability required for the solenoid device while reducing the amount of energization to a coil required for moving a movable core to the side of a fixed core.SOLUTION: A solenoid device 1 includes a solenoid case 6, a coil 2 housed inside the solenoid case 6, a fixed core 4, and a movable iron core 30 that is arranged so as to be able to reciprocate in the axial direction and is moved at least toward the side of the fixed core 4 in the axial direction by electromagnetic force generated by energization of the coil 2, and a permanent magnet 7 is fixed to the movable core 30 on the side of the fixed core 4, and the movable core 30 includes a convex portion 32 extending in a direction from the back side to the front side along the side surface 71 of the permanent magnet 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a solenoid device that operates various devices using a movable iron core. [Background technology]

[0002] Solenoid devices are used in various industrial fields as a means for operating various devices such as valves and machines. A solenoid device operates various devices by electromagnetically moving a movable iron core that is arranged so as to be capable of reciprocating when electricity is passed through a coil.

[0003] Generally, a solenoid device comprises a solenoid case made of a magnetic material, a coil housed inside the solenoid case, a fixed core, and a movable core, and when electricity is applied to the coil, a magnetic force is generated between the fixed core and the movable core, causing the movable core to move axially toward the fixed core, and a rod that abuts or is connected to various devices extends from one axial end of the movable core. There are many different structures for such solenoid devices, but some have a separate permanent magnet that attracts the movable core toward the fixed core (see, for example, Patent Document 1).

[0004] The solenoid device shown in Patent Document 1 has a permanent magnet embedded in the movable core, and the movable core is attracted to the fixed core by the magnetic force of the permanent magnet. By using the magnetic force of the permanent magnet, it is possible to reduce the amount of current flowing through the coil required to hold the position of the movable core on the fixed core side. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP-A-1-302707 (page 2, figure 3) Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, in a solenoid device such as that disclosed in Patent Document 1, by using a permanent magnet that constantly generates magnetic force, it is possible to reduce the magnetic force required for the electromagnet that generates magnetic force when current is applied. However, although the magnetic force of the permanent magnet decreases as the distance between the permanent magnet and the fixed iron core, which is the object to be attracted, increases, the magnetic force of the permanent magnet extends to the fixed iron core over a wide area in the axial direction, and this creates resistance when separating the movable iron core from the fixed iron core, which may reduce the operability of the movable iron core.

[0007] The present invention has been made in response to these problems, and aims to provide a solenoid device that can reduce the amount of current required to pass through the coil to move the movable core toward the fixed core while ensuring the operability required for the solenoid device. [Means for solving the problem]

[0008] In order to solve the above problems, the solenoid device of the present invention comprises: A solenoid device comprising: a solenoid case; a coil housed inside the solenoid case; a fixed core; and a movable core arranged to be capable of reciprocating in an axial direction and moved at least toward the fixed core in the axial direction by an electromagnetic force generated by energizing the coil, A permanent magnet is fixed to the movable core on the fixed core side, The movable core has a protrusion extending from the rear side toward the front side along a side surface of the permanent magnet. According to this, the magnetic field lines of the permanent magnet are concentrated between the fixed iron core side of the permanent magnet and the convex portion, and a large attractive force can be obtained, and the amount of current required to pass through the coil to move the movable iron core toward the fixed iron core side can be reduced. Also, since the magnetic field lines of the permanent magnet are concentrated between the fixed iron core side of the permanent magnet and the convex portion, the axial area affected by the magnetic force of the permanent magnet is narrowed, so that when the fixed iron core is separated from the movable iron core, the attractive force acting on the fixed iron core is rapidly attenuated. As a result, the operability required for the solenoid device can be ensured.

[0009] The protrusion may extend so as to cover a side surface of the permanent magnet in the front-rear direction. With this, the front surface of the permanent magnet and the convex portion are close to each other on the axial side of the fixed core, and a large attractive force to the fixed core can be obtained.

[0010] There may be a movement restriction means for preventing the permanent magnet from coming into contact with the fixed core. This makes it possible to prevent collision between the permanent magnet and the fixed core.

[0011] The protrusion may be endless in the circumferential direction. This allows for uniform suction force in the circumferential direction.

[0012] The convex portion may be formed on an outer diameter side of the permanent magnet. This allows the projections to have a large area.

[0013] The protrusion may be insertable into a recess formed on an outer diameter side or an inner diameter side of the fixed core. This allows the opposing surfaces of the permanent magnet and the fixed core to be brought close to each other.

[0014] The permanent magnet may be annular. This makes it possible to easily obtain a uniform suction force in the circumferential direction.

[0015] The permanent magnet may be sandwiched between fixing means made of a non-magnetic material arranged on the fixed core side and a surface of the movable core facing the fixed core. This allows the permanent magnet and the movable core to move together as a unit. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing a state in which a movable core is separated from a fixed core and at rest in a solenoid device according to a first embodiment of the present invention. [Diagram 2]2 is a cross-sectional view showing a state in which a movable core is stationary close to a fixed core in the solenoid device of the first embodiment. FIG. [Diagram 3] 3 is a schematic diagram showing magnetic field lines caused by a permanent magnet in the first embodiment. FIG. [Figure 4] 2 is a schematic diagram showing magnetic field lines caused by a permanent magnet embedded in a magnetic body. FIG. [Diagram 5] 4 is a diagram for explaining a state in which the movable core moves from a stationary state separated from the fixed core to a state in which the movable core moves close to the fixed core and stops in the first embodiment. FIG. [Figure 6] 4 is a diagram for explaining a state in which the movable core moves from a position where it is close to the fixed core and stationary to a position where it is separated from the fixed core and stationary in the first embodiment. FIG. [Figure 7] FIG. 6 is a cross-sectional view of a solenoid device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A solenoid device according to the present invention will be described below with reference to the accompanying drawings. EXAMPLES

[0018] A solenoid device according to a first embodiment will be described with reference to Fig. 1 to Fig. 6. In the following description, the left and right sides indicated with the arrows in Fig. 1 will be referred to as the left and right sides of the solenoid device. In addition, in the present invention, with the permanent magnet as the base, the fixed iron core side of the permanent magnet, i.e., the left side, will be referred to as the front side, and the opposite side, i.e., the right side, will be referred to as the rear side.

[0019] As shown in Figures 1 and 2, the solenoid device 1 is a self-retaining solenoid mainly composed of a coil 2, a plunger 3 having a movable core 30, a center post 4 as a fixed core, a return spring 5, a solenoid case 6, a self-retaining permanent magnet 7, and a ring-shaped holder 8.

[0020] The coil 2 is mainly composed of a bobbin 20 having a generally cylindrical shape with a flange formed from an insulating material, and a conductor 21 wound a predetermined number of times around the outer periphery of the bobbin 20. An end of the conductor 21 is connected to a lead wire 22, and when power is supplied from a power source (not shown), the coil 2 generates a magnetic flux.

[0021] Further, a holder 8 is disposed on the axial right side of the coil 2, and the inner diameter of the coil 2 and the inner diameter of the holder 8 are configured to be substantially the same.

[0022] The plunger 3 has an approximately cylindrical movable core 30 made of a magnetic material such as iron, and a rod 31 serving as a shaft portion made of a non-magnetic material such as an aluminum alloy and protruding in the axial direction of the plunger 3 (hereinafter simply referred to as the "axial direction").

[0023] Furthermore, the plunger 3 is disposed on the inner diameter side of the coil 2 and the holder 8. Note that the outer peripheral surface of the movable core 30 and the inner peripheral surfaces of the bobbin 20 of the coil 2 and the holder 8 are slightly spaced apart in the radial direction to form a minute gap, allowing the movable core 30 to move smoothly relative to the coil 2 and the holder 8 in the axial direction.

[0024] Further, the movable core 30 is provided with a through hole 30a penetrating in the axial direction at the radial center. A base 31b of the rod 31 is inserted into the through hole 30a and fixed integrally by welding, press fitting, etc. In other words, the movable core 30 and the rod 31 are movable together in the axial direction.

[0025] The movable core 30 is provided with a flat surface 30b as an opposing surface facing the center post 4, which extends radially from the outer diameter side of the through hole 30a of the movable core 30. The flat surface 30b is perpendicular to the axial direction.

[0026] The left end of the movable core 30 in the axial direction is formed with an annular suction portion 32 as a convex portion extending from the outer diameter side of the flat surface 30b toward the left in the axial direction. The suction portion 32 includes, from the left in the axial direction, an annular flat surface 32a extending radially, and a tapered surface 32b that is linear in cross section and extends from the inner diameter side of the flat surface 32a toward the right in the axial direction with a gradually smaller diameter. The right end in the axial direction of the tapered surface 32b is continuous with the flat surface 30b of the movable core 30.

[0027] The rod 31 has a small-diameter mounting portion 31a formed at its left axial end, and a base portion 31b having a larger diameter than the mounting portion 31a, and a disk-shaped retainer 33 is press-fitted and fixed to the mounting portion 31a. The right axial end of the rod 31 is connected to a load such as an on-off valve (not shown).

[0028] The base portion 31b of the rod 31 is formed with an annular groove 31c recessed in the inner diameter direction on the outer periphery of the left end portion in the axial direction.

[0029] The permanent magnet 7 is annular and thin, with a through hole 70 formed to be slightly larger or the same diameter as the inner diameter of the through hole 30a of the movable core 30 of the plunger 3, and with the rod 31 inserted into the through hole 70, the right axial end face of the permanent magnet 7 is magnetically attached to the flat surface 30b of the movable core 30. Note that the left axial side of the permanent magnet 7 is the north pole and the right axial side is the south pole, but the left axial side may be the south pole and the right axial side may be the north pole.

[0030] In addition, on the axial left side of the permanent magnet 7, an annular, thin-plate-shaped retaining ring 9 serving as a fixing means and made of stainless steel or the like is fitted and fixed into the annular groove 31c of the rod 31 via a through hole 90 that passes axially through the radial center portion, and the axial right end face of the retaining ring 9 abuts against the axial left end face of the permanent magnet 7.

[0031] The retaining ring 9 is fitted and fixed into the annular groove 31c by utilizing thermal expansion, but a C-shaped retaining ring may also be crimped and fixed to the rod 31, and the shape and fixing method of the retaining ring may be changed as appropriate.

[0032] As shown in Figures 1 and 2, in this embodiment, the permanent magnet 7 is arranged along the outer peripheral surface 71 (the side surface) of the permanent magnet 7, with no magnetic material other than the center post 4 being arranged on the front side of the permanent magnet 7, and is arranged on the inner diameter side of the attraction portion 32 of the movable core 30 which extends forward of the permanent magnet 7, i.e., toward the center post 4.

[0033] As shown in Figure 3, most of the magnetic field lines from the permanent magnet 7 are guided to the tapered surface 32b of the attraction portion 32, which is the end face of the magnetic body located close to the left axial end face, as indicated by the solid arrows, and each magnetic field line MF is concentrated in a narrow area of ​​the tapered surface 32b from the front side of the permanent magnet 7.

[0034] Here, the magnetic field lines of the permanent magnet 7A embedded inside the movable core 30A, which is a magnetic body, will be described as shown in Fig. 4, which is used for comparison with this embodiment. As shown by the solid arrows, the magnetic field lines of the permanent magnet 7A are elliptical magnetic field lines MFA that are long in the axial direction and spread out in a ripple shape.

[0035] In this way, in the solenoid device 1 of the present embodiment, a high magnetic flux density acts in a narrow area in the axial direction, so that the attractive force F M can act strongly in a small area.

[0036] That is, it can be said that the area in the axial direction affected by the magnetic force of the permanent magnet 7 in the embodiment of FIG. 3 is narrower than that in the embodiment of FIG.

[0037] In addition, since the suction portion 32 is annular, the suction force F is uniformly distributed in the circumferential direction. M You can get.

[0038] In addition, since the suction portion 32 is formed on the outer diameter side, it is easier to ensure a large surface area of ​​the flat surface 32a and the tapered surface 32b that induce the magnetic force of the permanent magnet 7, compared to a configuration in which the suction portion 32 is formed on the inner diameter side.

[0039] In addition, since the permanent magnet 7 is annular, it is possible to easily generate a uniform attractive force F in the circumferential direction, compared to arranging a plurality of permanent magnets at equal intervals. M can be applied to the suction portion 32.

[0040] In addition, since the permanent magnet 7 is annular and the magnetic flux strength on the outer diameter side is stronger than the magnetic flux strength on the inner diameter side, the magnetic force is efficiently induced in the attraction portion 32 located on the outer diameter side of the permanent magnet 7.

[0041] Returning to Figures 1 and 2, the center post 4 is formed from a magnetic material such as iron, and has a cylindrical portion 40, a flange portion 41 extending radially outward from the left axial end of the cylindrical portion 40, and a conical suction portion 42 whose inner diameter side on the right axial side of the cylindrical portion 40 protrudes toward the right axial direction.

[0042] Furthermore, the center post 4 is inserted into the inner periphery of the coil 2 from the axial left side. At this time, the axial right side surface of the flange portion 41 abuts against the axial left end of the coil 2. In other words, the progress of insertion of the center post 4 into the coil 2 can be determined by the abutment with the flange portion 41. Therefore, the solenoid device 1 is easy to assemble.

[0043] The suction portion 42 is formed of a flat surface 42a extending radially from the outer diameter side of the axial hole 4a, a tapered surface 42b extending at an angle from the outer diameter side of the flat surface 42a toward the left axial direction so that the diameter gradually increases, and a flat surface 42c extending radially from the outer diameter side of the tapered surface 42b.

[0044] Between the suction portion 42 and the bobbin 20, a ring-shaped recess 10 that is open to the right in the axial direction is defined by the tapered surface 42b of the suction portion 42, the flat surface 42c, and the inner peripheral surface of the bobbin 20.

[0045] The center post 4 is provided with a shaft hole 4a and a spring hole 4b that penetrate in the axial direction at the radial center. The shaft hole 4a and the spring hole 4b are in communication with each other, and the diameter of the shaft hole 4a is smaller than the diameter of the spring hole 4b.

[0046] A rod 31 is inserted into the shaft hole 4a, and is journalled by a bearing 43 provided on the inner periphery of the shaft hole 4a.

[0047] In the spring hole 4b, there are disposed an attachment portion 31a of the rod 31 inserted into the shaft hole 4a and a retainer 33. In addition, in the spring hole 4b, a spring 5 is inserted from the left side in the axial direction.

[0048] The spring 5 is a compression spring, and its right axial end abuts against the left axial end face of the retainer 33, and its left axial end abuts against the right axial end face of the bottom cap 60 that constitutes the solenoid case 6.

[0049] The solenoid case 6 is composed of a bottom cap 60 made of a magnetic material such as iron, a top cap 61 made of a non-magnetic material, and a substantially cylindrical case body 62 made of a magnetic material such as iron.

[0050] The bottom cap 60 has a recess 60a on its axially right end face into which the flange portion 41 of the center post 4 can be inserted.

[0051] The top cap 61 has a recess 61a on its left axial end face into which the movable core 30 of the plunger 3 can be inserted. The top cap 61 also has a shaft hole 61b penetrating in the axial direction at the radial center. The rod 31 is inserted into the shaft hole 61b and is journaled by a bearing 63 provided on the inner periphery of the shaft hole 61b.

[0052] The case body 62 has a U-shaped cross section with a hole, and a step 62a is provided on the inner diameter side of the left end in the axial direction.

[0053] Here, an example of the procedure for assembling the solenoid device 1 will be described. First, the top cap 61, holder 8, and coil 2 are inserted into the case body 62 from the axial left side in that order. Next, the plunger 3, center post 4, and spring 5 are inserted in an assembled state into the coil 2 from the axial left side. Finally, the flange portion 41 of the center post 4 is inserted into the recess 60a of the bottom cap 60, and the left axial end of the case body 62 is crimped and fixed to the chamfered portion of the outer periphery of the bottom cap 60. At this time, the step portion 62a of the case body 62 functions as a load receiving portion that receives the axial load when crimped and fixed.

[0054] Next, the operation of the solenoid device 1 will be described.

[0055] The solenoid device 1 can be switched between a state in which the plunger 3 moves to a first position on the right side in the axial direction when in a non-energized state (see Figure 1), and a state in which the plunger 3 moves to a second position on the left side in the axial direction as a specific relative position when in a powered state (see Figure 2).

[0056] First, a state in which the plunger 3 is in the first position and in a non-energized state will be described with reference to Fig. 5(a). The solenoid device 1 is configured such that the plunger 3 is biased by the biasing force (F sp ) is pressed axially to the right, so that the axially right end face of the movable core 30 of the plunger 3 abuts against the bottom face of the recess 61a of the top cap 61, and the stopped state is maintained in the first position.

[0057] At this time, the plunger 3 is subjected to a biasing force (F sp In addition, the attraction portion 32 of the plunger 3 is in the state of being farthest from the attraction portion 42 of the center post 4, and as described above, the axial region affected by the magnetic force of the permanent magnet 7 is narrowed, so that the attraction force (F M ) is hardly or not acting at all on the attraction portion 42 of the center post 4. Therefore, the force F acting on the plunger 3 is positive in the axial right direction. plu1 =F sp-F M is in effect (however, F sp >>F M ≧0).

[0058] As shown in FIG. 1 and FIG. 5(a), when the movable iron core 30 of the plunger 3 is separated from the center post 4, the solenoid device 1 is energized and a current is applied to the coil 2, which generates an electromagnetic force (F sol1 ) is generated. This electromagnetic force (F sol1 ) and the magnetic force due to a permanent magnet (F M1 ) is the force of spring 5 (F sp ) exceeds (F sol1 +F M1 >F sp ), the plunger 3 is attracted toward the center post 4. That is, the plunger 3 starts to move axially to the left.

[0059] When the plunger 3 moves towards the center post 4 and approaches the center post 4, the magnetic field lines MF (see FIG. 4) of the permanent magnet 7 concentrated in a narrow area suddenly start to attract the center post 4.

[0060] At this time, a high attractive force (F M ) is applied, resulting in electromagnetic force (F sol1 ), the plunger 3 can be reliably and quickly moved to the second position in a state where the plunger 3 approaches the center post 4, and the amount of current flow can be reduced.

[0061] Eventually, the flat surface 32a of the suction portion 32 of the plunger 3 moves until it abuts the flat surface 42c of the suction portion 42 of the center post 4, the tip of the suction portion 32 is inserted into the recess 10, and the plunger 3 moves to the second position as shown in Figure 5(b).

[0062] In addition, when the plunger 3 is in the second position, the magnetic force (F M2 ) is the biasing force of spring 5 (Fsp ) is set larger than (F sp <F M2 ).

[0063] Therefore, even if the current supply to the coil 2 is stopped and the coil is in a non-energized state, the magnetic force (F M2 ), the state where the attraction portion 32 of the plunger 3 is attracted to the attraction portion 42 of the center post 4 is maintained, that is, the plunger 3 is self-retained. At this time, the force F plu2 =F sp -F M2 is at work.

[0064] Further, the axial left end face of the permanent magnet 7 disposed opposite to it and the flat surface 42a of the attraction portion 42 of the center post 4 are adjacent to each other.

[0065] Furthermore, since the axial dimension L1 between the flat surface 32a of the attraction portion 32 of the plunger 3 and the axial left end face of the retaining ring 9 is longer than the axial dimension L2 between the flat surface 42a and the flat surface 42c of the attraction portion 42 of the center post 4 (L1>L2), when the plunger 3 is moved to the second position, the flat surface 42a and tapered surface 42b of the attraction portion 42 are slightly separated from the retaining ring 9, the permanent magnet 7, and the flat surface 30b and tapered surface 32b of the movable core 30.

[0066] In this manner, the attraction portion 32 of the plunger 3 and the center post 4 constitute a movement restriction means for preventing contact between the permanent magnet 7 and the center post 4, thereby preventing collision between the permanent magnet 7 and the center post 4.

[0067] In addition, since the permanent magnet 7 is sandwiched between the retaining ring 9 and the flat surface 30b of the movable core 30, the permanent magnet 7 does not move relative to the attraction portion 32 of the plunger 3 due to the impact when the attraction portion 32 of the plunger 3 comes into contact with the attraction portion 42 of the center post 4, thereby preventing collision between the permanent magnet 7 and the center post 4.

[0068] When the self-holding function of the solenoid device 1 is released, a reverse current is applied to the coil 2, and an electromagnetic force (F sol2 ) is generated. This electromagnetic force (F sol2 ) and the biasing force of spring 5 (F sp ) is the magnetic force F generated by the permanent magnet 7. M2 Exceeds (F sol2 +F sp >F M2 ), the plunger 3 moves away from the center post 4.

[0069] Thereafter, when the plunger 3 separates from the center post 4, the attractive force (F M ) is rapidly attenuated and is less likely to act as a resistance when the plunger 3 is moved away from the center post 4, so that the plunger 3 can be moved reliably and quickly to the original first position.

[0070] Finally, the biasing force of the spring 5 (F sp ) moves the plunger 3 to the right in the axial direction and returns it to the first position (see FIG. 6(b)). Note that, during the movement from the second position to the first position, the biasing force (F sp ), as well as electromagnetic force (F sol2 ) may be used in combination.

[0071] As described above, the solenoid device 1 of this embodiment can reliably and quickly move the plunger 3 from the first position to the second position and from the second position to the first position, thereby smoothly operating the solenoid device 1. In other words, the necessary operability of the solenoid device 1 can be ensured.

[0072] Furthermore, as in the configuration shown in FIG. 4 in which the permanent magnet 7A is embedded inside the movable core 30A, there is no need to increase the amount of current or the number of coil turns to increase the electromagnetic force in order to reliably and quickly move the plunger 3 from the first position to the second position or from the second position to the first position, so it is possible to reduce the amount of current and make the solenoid device 1 smaller and lighter.

[0073] Furthermore, since the permanent magnet 7 is sandwiched between the retaining ring 9 and the flat surface 30b of the movable core 30, tilting is prevented even if an external force such as an electromagnetic force or vibration acting on the solenoid device 1 is applied, and the permanent magnet 7 and the plunger 3 can move together.

[0074] Therefore, the distance between the permanent magnet 7 and the movable core 30 does not change even with reciprocating motion, and a stable magnetic force acts from the permanent magnet 7 to the movable core 30, so that the movement of the plunger 3 is smooth.

[0075] As described above, the attraction portion 32 of the plunger 3 has an attraction force (F M ) is evenly distributed in the circumferential direction, so that the suction force is unlikely to be biased to one side in the circumferential direction and the suction force is unlikely to tilt relative to the center post 4, and therefore the movement is smooth.

[0076] Furthermore, since the permanent magnet 7 and the retaining ring 9 are thin plate-shaped, the difference between the axial dimension L1 between the flat surface 32a of the attraction portion 32 of the plunger 3 and the axial left end face of the retaining ring 9, and the axial dimension L2 between the flat surface 42a and the flat surface 42c of the attraction portion 42 of the center post 4 can be reduced, thereby shortening the axial dimension of the solenoid device 1.

[0077] Although the embodiment in which the rod 31 penetrates and is fixed to the movable core 30 has been described, the present invention is not limited thereto, and for example, a rod may penetrate the movable core 30 and be arranged so as to be relatively movable in the axial direction. Even with this configuration, when a current is applied, the movable core 30 moves toward the center post 4, causing the rod to move in the same direction together with the retaining ring 9, and when the self-retention is released, the biasing force of the spring 5 causes the movable core 30 to move away from the center post 4 together with the rod and retaining ring. EXAMPLES

[0078] A solenoid device according to a second embodiment will be described with reference to Fig. 7. Note that a description of the same configuration as in the first embodiment will be omitted.

[0079] As shown in Figure 7, in this embodiment, the solenoid device 100 is configured so that the tip of the conical cylindrical attraction portion 132 of the movable iron core 130 of the plunger 103 can be inserted into the inner recess 110 of the tapered surface 142b of the annular attraction portion 142 of the center post 104.

[0080] The suction portion 132 has, from the left in the axial direction, a flat surface 132a, a tapered surface 132b, a groove 132c that is continuous with the axial right end of the tapered surface 132b and is recessed toward the inner diameter side, and a step portion 132d that is continuous with the axial right end of the groove 132c.

[0081] An annular buffer member 109 serving as a fixing means and made of a non-magnetic elastic body such as rubber is inserted into the groove 132c of the attraction part 132, and an annular permanent magnet 107 is disposed on the outer diameter side of the outer circumferential surface of the step part 132d of the attraction part 132. As a result, the permanent magnet 107 is sandwiched between the buffer member 109 and the bottom part of the step part 132d.

[0082] Even with this configuration, the magnetic field lines from the permanent magnet 107 are induced to the tapered surface 132b of the attraction portion 132 of the plunger 103, and each magnetic field line is concentrated in a narrow region of the tapered surface 132b from the front side of the permanent magnet 107. This makes it possible to ensure the necessary operability of the solenoid device 100 while reducing the amount of current flowing through the coil 2 required to move the plunger 103 toward the center post 104, as in the first embodiment.

[0083] In addition, when current is applied to the solenoid device 1 and the plunger 103 is moved from the first position to the second position, causing the tip of the suction portion 132 to be inserted into the inner recess 110 of the center post 104, the buffer member 109 comes into contact with the flat surface 142a of the suction portion 142 of the center post 104, although direct illustration is omitted.

[0084] In this way, the buffer member 109 is a movement restriction means that prevents contact between the permanent magnet 107 and the center post 4, and prevents a direct collision between the permanent magnet 107 and the center post 104. The buffer member 109 can also absorb the impact when the permanent magnet 107 comes into contact with the flat surface 142a of the suction portion 142 of the center post 104.

[0085] Although the permanent magnet 107 and the buffer member 109 have been described as being fixed individually to the attraction portion 132 of the movable core 130, this is not limiting, and the permanent magnet 107 may be covered with a non-magnetic elastic body such as rubber. With such a configuration, the permanent magnet 107 can be fixed integrally to the fixed core, making fixing easy.

[0086] In addition, the buffer member 109 has been described as serving both as a movement restricting means and a fixing means, but this is not limited thereto. By providing a separate movement restricting means, such as utilizing the dimensional difference between the movable core 30 and the center post 4 in the first embodiment, the buffer member 109 may function only as a fixing means, or by providing a separate fixing means such as the retaining ring 9 in the first embodiment, the buffer member 109 may function only as a movement restricting means.

[0087] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0088] For example, in the first and second embodiments, the movable core is moved in a direction away from the fixed core by a coil spring, but the present invention is not limited to this, and the movable core may be moved in a direction away from the fixed core by another means. For example, the movable core may be moved in a direction away from the fixed core by a tension spring provided on the movable core on the opposite side to the fixed core.

[0089] In addition, in the first and second embodiments, a configuration in which a reverse current is applied to a coil is described as a drive source for releasing the self-holding function of the solenoid device, but this is not limiting, and a coil for moving the movable core toward the fixed core and a coil for moving the movable core away from the fixed core may be separately arranged. In addition, various cylinders or the like may be used as a drive source for releasing the self-holding function, or it may be manual, and the drive source for releasing the self-holding function may be changed as appropriate.

[0090] In addition, in the first and second embodiments, the movable core is self-held at the second position by the magnetic force of the permanent magnet, but the present invention is not limited to this, and may be configured to use both the magnetic force of the permanent magnet and the electromagnetic force of the coil to stop and hold the movable core at the second position. Even with such a configuration, the amount of current required is reduced compared to a configuration that does not use a permanent magnet.

[0091] In addition, in the above-mentioned first and second embodiments, the solenoid device has been described as having a configuration in which the suction portion of the plunger as a convex portion is annular or conical, i.e., endless, but this is not limited to the above, and a single convex portion with ends may be formed, or multiple convex portions with ends may be evenly or non-evenly arranged.

[0092] In addition, in the above-mentioned first and second embodiments, the attraction portion of the plunger is described as extending forward of the permanent magnet, but this is not limited thereto, and the attraction portion may form approximately the same surface as the front surface of the permanent magnet. In other words, as long as it covers at least the side surface, the magnetic field lines of the permanent magnet can be concentrated on the axial center post side.

[0093] In addition, in the above-mentioned first and second embodiments, the permanent magnets are described as being annular, but this is not limited thereto, and multiple permanent magnets may be equally arranged, or the permanent magnets may be flat, such as round or rectangular, and the shape and arrangement may be changed as appropriate.

[0094] In addition, in the above-mentioned first and second embodiments, the permanent magnet is sandwiched between a fixing means made of a non-magnetic material arranged on the fixed core side and the surface of the movable core facing the fixed core, and examples have been given of a configuration in which the permanent magnet is sandwiched between a retaining ring and the flat surface of the movable core of the plunger, or a configuration in which the permanent magnet is sandwiched between a buffer member and the bottom surface of the stepped portion of the movable core of the plunger. However, this is not limiting, and a separate magnetic or non-magnetic material may be interposed between the permanent magnet and the plunger side.

[0095] In addition, in the above-mentioned first and second embodiments, the fixing means is described as a retaining ring or a cushioning member, but this is not limited thereto, and the permanent magnet may be fixed to the plunger by welding, adhesive, etc., without using a retaining ring or cushioning member, etc.

[0096] In addition, in the first and second embodiments, the holder is a separate member from the solenoid case, but the present invention is not limited to this and the holder may be integrated with the solenoid case.

[0097] In the first and second embodiments, the holder is made of a magnetic material, but it may be made of a non-magnetic material. In this case, it is preferable to form a magnetic circuit by making the top cap of a magnetic material.

[0098] In addition, in the above embodiment, the retainer against which the axial right end of the spring abuts and the rod are described as being constructed separately, but this is not limited thereto, and the spring support portion against which the axial right end of the spring abuts may be constructed integrally with the rod.

[0099] Furthermore, the attraction portion of the center post and the plunger is not limited to having a tapered surface, and may be freely configured in any shape. [Explanation of symbols]

[0100] 1 Solenoid device 2 Coil 4 Center post (fixed core) 6 Solenoid case 7. Permanent Magnets 9 Retaining ring (fixing means) 10 Recess 30 Movable core 32 Suction portion (protrusion, movement restriction means) 42 Suction part (movement regulating means) 71 Outer surface (side surface of permanent magnet) 100 Solenoid device 104 Center post (fixed core) 107 Permanent Magnets 109 Cushioning member (fixing means, movement restriction means) 110 Recess 130 Movable core 132 Suction part (convex part) L1 Axial dimension L2 Axial dimension

Claims

1. A solenoid device comprising: a solenoid case; a coil housed inside the solenoid case; a fixed core; and a movable core arranged to be capable of reciprocating in an axial direction and moved at least toward the fixed core in the axial direction by an electromagnetic force generated by energizing the coil, A permanent magnet is fixed to the movable core on the fixed core side, the movable core has a protrusion extending from a rear side to a front side along a side surface of the permanent magnet, the protrusion is endless in the circumferential direction on the outer diameter side of the permanent magnet and can be inserted into an annular recess formed on the outer diameter side of the fixed core, A solenoid device in which, when the convex portion is inserted into the concave portion and the tip of the convex portion abuts against the bottom surface of the concave portion, the permanent magnet and the fixed iron core are separated, and the peripheral surface of the convex portion is separated from the peripheral surface of the concave portion that faces the peripheral surface of the convex portion.

2. The solenoid device according to claim 1 , wherein the protrusion extends so as to cover a side surface of the permanent magnet in the front-rear direction.

3. 3. The solenoid device according to claim 1, wherein the permanent magnet is annular.

4. 4. The solenoid device according to claim 1, wherein the permanent magnet is sandwiched between fixing means made of a non-magnetic material arranged on the fixed core side and a surface of the movable core facing the fixed core.

Images