Solenoid

Abstract

To provide a solenoid that can reduce collision noise caused by movement of a movable iron core during excitation of a coil while suppressing wear of the movable iron core and preventing increase in size of an apparatus.SOLUTION: A typical configuration of a solenoid 100 of the present invention includes: a casing 110; a fixed iron core 120 stored in the casing 110; a coil 130 arranged between the casing 110 and the fixed iron core 120; a movable iron core 140 movable inside the fixed iron core 120; a shaft 150 fixed at the center of the movable iron core 140; a recess 142 formed at an end of the movable iron core 140 on a side facing the fixed iron core 120 in an axial direction of the shaft 150; and a protrusion 122 formed in the fixed iron core 120 and engaged with the recess 142 when the movable iron core 140 moves to a stroke end during excitation of the coil 130.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a solenoid having a damping function. [Background technology]

[0002] Solenoids are known as devices that operate shafts, which are components of industrial equipment. Conventionally, a problem with solenoids has been how to reduce the impact noise (operating noise) that occurs when a moving iron core collides with a fixed iron core as it moves. For example, Patent Document 1 discloses an electromagnetic solenoid with a buffer function.

[0003] In the electromagnetic solenoid of Patent Document 1, "the casing has an operating space that houses the movable magnetic material, and a communication passage is formed on the inner peripheral wall surface of the operating space, which communicates with chambers formed on both sides of the movable magnetic material." Such a communication passage "has a predetermined height from the inner peripheral wall surface in the radial direction of the operating space, and the end of the communication passage in the approaching and separating direction has a predetermined length in the approaching and separating direction, and the end is formed so that the predetermined height gradually decreases from the center side toward the end of the communication passage in the approaching and separating direction." Patent Document 1 states that "an air cushion effect can be obtained at the end of the operating stroke of the movable iron core without sacrificing the moving speed."

[0004] Also, Patent Document 2 discloses a shock absorber for a solenoid. The shock absorber for a solenoid in Patent Document 2 is characterized by "arranging a fluid shock absorber on the path of movement of the drive shaft of a solenoid disposed inside a casing or a shaft member connected to this drive shaft, and using this shock absorber to absorb the impact force of the drive shaft or the shaft member connected to this drive shaft." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4724960 [Patent Document 2] Japanese Patent Application Publication No. 53-147965 Summary of the Invention [Problem to be solved by the invention]

[0006] In the electromagnetic solenoid of Patent Document 1, the cross-sectional area of ​​the communication passage is gradually reduced toward both ends, thereby gradually reducing the moving speed of the movable core. However, with this configuration, the magnetic gap becomes smaller (magnetic flux becomes larger) at the points where the cross-sectional area of ​​the communication passage is reduced. For this reason, the lateral force between the casing and the movable core becomes large when the coil is energized, causing them to come into contact and slide due to adhesion, which makes the sliding points more likely to wear out.

[0007] The solenoid shock absorber of Patent Document 2 is provided outside the solenoid, on the opposite side of the shaft member from the solenoid. Therefore, although the configuration of Patent Document 2 can absorb impact forces, the device becomes large in size.

[0008] In view of these problems, the present invention aims to provide a solenoid that can suppress wear on the movable core, prevent the device from becoming larger, and reduce the collision noise caused by the movement of the movable core when current is applied to the coil. [Means for solving the problem]

[0009] In order to solve the above problems, a typical configuration of a solenoid according to the present invention is characterized in that it comprises a casing, a fixed core housed inside the casing, a coil arranged between the casing and the fixed core, a movable core movable inside the fixed core, a shaft fixed to the center of the movable core, a recess formed on the end of the movable core facing the fixed core in the axial direction of the shaft, and a convex portion formed on the fixed core that engages with the recess when the movable core moves to the stroke end when current is applied to the coil.

[0010] In order to solve the above problems, another configuration of the solenoid of the present invention is characterized in that it comprises a casing, a fixed iron core housed inside the casing, a coil arranged between the casing and the fixed iron core, a movable iron core that can move inside the fixed iron core, a shaft fixed to the center of the movable iron core, a recess formed on the end of the movable iron core facing the fixed iron core in the axial direction of the shaft, and a convex member that engages with the recess when the movable iron core moves to the stroke end when current is applied to the coil. Effect of the Invention

[0011] According to the present invention, it is possible to provide a solenoid that can suppress wear on the movable core, prevent the device from becoming large, and reduce collision noise caused by movement of the movable core when current is applied to the coil. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram illustrating a solenoid according to the present embodiment. [Diagram 2] 11A and 11B are diagrams illustrating magnetic flux when retracting from a protruding state. [Diagram 3] 11A and 11B are diagrams illustrating magnetic flux when protruding from a retracted state. [Figure 4] FIG. 2 is an enlarged view of a main part of FIG. [Diagram 5] 11A and 11B are diagrams illustrating magnetic fluxes generated at recesses and protrusions in a fitted state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values ​​shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.

[0014] FIG. 1 is a diagram for explaining a solenoid 100 according to this embodiment. FIG. 1 illustrates the solenoid 100 in a state in which a shaft 150 protrudes. As shown in FIG. 1, the solenoid 100 of this embodiment accommodates a fixed core 120 inside a casing 110. A cup-shaped plunger chamber 112 filled with a liquid such as oil is disposed inside the casing 110. In the following description, the space in the plunger chamber 112 in the direction in which the movable core 140 is attracted to the fixed core 120 by the magnetic flux of the coil 130 and moves (hereinafter referred to as the "operation direction") is called a front chamber 112a, the space on the return side is called a rear chamber 112b, and a damper chamber described later is called 112c.

[0015] A coil 130 is disposed between the casing 110 and the fixed core 120. A movable core 140 is disposed movably inside the fixed core 120, and a shaft 150 is fixed to the center of the movable core 140. With this configuration, when the coil 130 to which a current is supplied is energized and excited, the movable core 140 is attracted to the fixed core 120. As a result, the movable core 140 moves inside the fixed core 120 to the right in the figure, and the shaft 150 fixed to the movable core 140 operates.

[0016] In this embodiment, the movable core 140 is configured to be held by a magnet when the shaft 150 is on the protruding side, and not held by a magnet when the shaft 150 is on the retracted side. Then, the protruding and retracting operations are performed depending on the direction of the current flowing through the coil 130.

[0017] 2 is a diagram illustrating the magnetic flux when shaft 150 is retracted from an extended state. Moving core 140 is composed of magnetic body 140a, magnet 140b, magnetic body 140c, magnet 140d, and magnetic body 140e from the shaft tip side (the "magnetic bodies" allow magnetic flux to pass through but are not permanent magnets).

[0018] 2(a) shows a state in which the shaft 150 is held in a protruding state. At this time, magnetic flux M11 emitted from magnet 140b flows to fixed core 120 through magnetic body 140c, and returns to 120b through magnetic body 140a. Magnetic flux M12 emitted from magnet 140d flows to fixed core 120 through magnetic body 140c, flows around the outer periphery of coil 130, and returns to magnet 140d through magnetic body 140e. Magnetic fluxes M11 and M12 form a loop passing through movable core 140 and fixed core 120, and movable core 140 is attracted to fixed core 120, so shaft 150 is held in a protruding state.

[0019] Then, current is passed through coil 130 as shown in Fig. 2(b). The arrowhead symbol above coil 130 indicates the direction in which current flows from the back of the page to the front, and the arrow feather symbol indicates the direction in which current flows from the front of the page to the back. A strong magnetic flux M13 emitted from coil 130 flows through magnetic body 140a, magnet 140b, and magnetic body 140c via fixed iron core 120, and flows so as to surround coil 130 through fixed iron core 126. Then, an attractive force is generated between magnetic body 140c and fixed iron core 126, and shaft 150 moves in the retracting direction.

[0020] At this time, magnetic flux M14 emanating from magnet 140d is overwhelmed by magnetic flux M13 from coil 130 and is unable to circle the outer periphery of coil 130. For this reason, magnetic flux M14 flows through magnetic body 140c to fixed core 126, and makes a small turn to return to magnet 140d from magnetic body 140e.

[0021] 3A and 3B are diagrams for explaining the magnetic flux when the magnets 140 are extended from the retracted state. When the magnets 140 are in the retracted state as shown in FIG. 3A, the shaft 150 is not held by the magnetic flux of the magnets 140b and 140d.

[0022] Magnetic flux M21 leaving magnet 140b passes through magnetic body 140c, flows around the outer periphery of coil 130, and returns to magnet 140b through magnetic body 140a. Magnetic flux M22 leaving magnet 140d flows through magnetic body 140c to fixed core 126, and returns to magnet 140d from magnetic body 140e. Both magnetic fluxes M21 and M22 are perpendicular to the direction of movement of shaft 150, so their attractive forces do not have a component in the direction of movement.

[0023] 3(b), a current is passed through the coil 130. A strong magnetic flux M23 emitted from the coil 130 flows through the fixed iron core 126, the magnetic body 140e, the magnet 140d, and the magnetic body 140c, and then flows so as to surround the coil 130 through the fixed iron core 120. Then, an attractive force is generated between the magnetic body 140c and the fixed iron core 120, and the shaft 150 moves in the protruding direction.

[0024] At this time, magnetic flux M24 emanating from magnet 140b is overwhelmed by magnetic flux M23 from coil 130 and is unable to rotate around the outer periphery of coil 130. For this reason, magnetic flux M24 flows through magnetic body 140c to fixed core 120, and makes a small turn so as to return from magnetic body 140a to magnet 140b. M24 also generates an attractive force between magnetic body 140c and fixed core 120, generating a force on shaft 150 in the protruding direction.

[0025] A feature of the solenoid 100 of this embodiment is that a recess 142 is formed in the movable core 140, and a protrusion 122 is formed in the fixed core 120. The recess 142 is formed in an end 144 (the end in the operating direction of the fixed core 120) of the movable core 140 that faces the fixed core 120 in the axial direction of the shaft 150. The protrusion 122 is formed in a surface 124 of the fixed core 120 that faces the end in the operating direction of the movable core 140 in the axial direction of the shaft 150, and fits into the recess 142 when the movable core 140 moves to the stroke end when the coil 130 is energized.

[0026] Fig. 4 is an enlarged view of the main part of Fig. 1. Fig. 4(a) is a diagram illustrating an example of a state when the movable core 140 starts to move. Fig. 4(b) is a diagram illustrating an example of a state during the movement of the movable core 140. Fig. 4(c) is a diagram illustrating an example of a state when the movable core 140 has completed its movement.

[0027] Of the plunger chamber 112 (the space in which the movable core 140 moves), the space in front of the movable core 140 (the space in the operating direction) is referred to as a front chamber 112a. However, the space inside the recess 142 is particularly referred to as a damper chamber 112c.

[0028] 4(a), when the coil 130 is energized, the movable core 140 starts to move in a direction (direction D1) approaching the fixed core 120. A gap CL1 is formed between the outer peripheral surface 141 of the movable core 140 and the inner peripheral surface 120b of the fixed core 120. Therefore, the liquid (hereinafter referred to as liquid) that has been retained in the front chamber 112a and the damper chamber 112c is pushed out toward the rear chamber 112b through the gap CL1.

[0029] Since the clearance of the gap CL1 is relatively wide, the liquid can flow smoothly. Also, since the recessed portion 142 has not yet reached the protruding portion 122, the gap between them is large. Therefore, the movement of the movable core 140 is not hindered, and good responsiveness can be maintained.

[0030] 4(b), when the movable core 140 moves further in the direction approaching the fixed core 120, the recess 142 and the protrusion 122 start to fit together. At this time, a gap CL2 having a narrower clearance than the gap CL1 is formed between the inner circumferential surface 142b of the recess 142 and the outer circumferential surface 122a of the protrusion 122. Therefore, when the liquid flows from the damper chamber 112c to the front chamber 112a, the flow resistance increases, and the moving speed of the movable core 140 decreases.

[0031] As shown in FIG. 4(c), the movable core 140 approaches the fixed core 120 further, and when the movable core 140 reaches the stroke end and completes its movement, the engagement between the recessed portion 142 and the protruding portion 122 is also completed.

[0032] As described above, in the solenoid 100 of this embodiment, when the coil 130 is energized, the movable core 140 moves toward the stroke end and the recessed portion 142 and the protruding portion 122 fit together. Before the recessed portion 142 and the protruding portion 122 start to fit together, the liquid in the front chamber 112a and the damper chamber 112c moves smoothly to the rear chamber 112b. This ensures favorable responsiveness of the solenoid 100.

[0033] When the recess 142 and the protrusion 122 start to fit together (begin to overlap), the liquid in the damper chamber 112c passes through the gap CL2 when it flows into the front chamber 112a, and the moving speed of the movable iron core 140 decreases. This provides a damper effect, making it possible to reduce the collision noise between the movable iron core 140 and the fixed iron core 120. In addition, since the solenoid 100 of this embodiment has a damper structure inside, it is possible to prevent the device from becoming large in size.

[0034] In the present embodiment, the configuration in which the convex portion 122 is formed on the fixed core 120 has been exemplified, but the present invention is not limited to this. For example, the same effect as above can be obtained by fixing a convex member (a member having a convex shape) separate from the fixed core 120 to the fixed core 120.

[0035] 5 is a diagram illustrating the magnetic flux generated in the recess 142 and the protrusion 122 in the fitted state. As shown in FIG. 5, the "cross-sectional area A1 of the protrusion 122" disposed between the shaft 150 and the recess 142 is set to be significantly smaller than the "cross-sectional area A2 of the fixed core 120" through which the magnetic flux flows from the movable core 140.

[0036] According to the above configuration, magnetic saturation occurs with a small amount of magnetic flux in the protruding portion 122. Therefore, most of the magnetic flux flowing from the movable core 140 to the fixed core 120 passes through the gap CL1, not through the gap CL2. This makes it possible to suppress the attraction force (lateral force) between the protruding portion 122 and the recessed portion 142 in the vicinity of the gap CL2, and makes it possible to preferably prevent the outer peripheral surface 122a of the protruding portion and the inner peripheral surface 142b of the recessed portion from sliding against each other and wearing away from each other.

[0037] In addition, since the clearance of gap CL2 is large, there is no risk of sliding between inner peripheral surface 120b of fixed core and outer peripheral surface 141 of movable core 140. Therefore, even though the adhesive force (lateral force) in gap CL1 is strong, it is possible to effectively prevent wear caused by the adhesive force.

[0038] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an example. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that such examples also naturally belong to the technical scope of the present invention. [Industrial Applicability]

[0039] The present invention can be used as a solenoid having a damper function. [Explanation of symbols]

[0040] CL1: gap, CL2: gap, 100: solenoid, 110: casing, 112: plunger chamber, 112a: front chamber, 112b: rear chamber, 112c: damper chamber, 120: fixed core, 120b: inner circumferential surface, 122: convex portion, 122a: outer circumferential surface, 124: surface, 130: coil, 140: movable core, 141: outer circumferential surface, 142: concave portion, 142b: inner circumferential surface, 144: end, 150: shaft, S: space

Claims

1. A casing; A fixed core accommodated inside the casing; a coil disposed between the casing and the fixed core; a movable core movable inside the fixed core; A shaft fixed to the center of the movable core; a recess formed at an end of the movable core on a side facing the fixed core in the axial direction of the shaft; a protrusion formed on the fixed core and adapted to fit into the recess when the movable core moves to a stroke end when the coil is energized; A solenoid comprising:

2. A casing; A fixed core accommodated inside the casing; a coil disposed between the casing and the fixed core; a movable core movable inside the fixed core; A shaft fixed to the center of the movable core; a recess formed at an end of the movable core on a side facing the fixed core in the axial direction of the shaft; a protruding member that fits into the recessed portion when the movable core moves to a stroke end when the coil is energized; A solenoid comprising:

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