JP7755151B2 - solenoid - Google Patents

Description

The present invention relates to a solenoid having a latching magnet that holds a movable iron core.

As an example, a solenoid has a fixed iron core and a movable iron core, which are arranged facing each other. When current is applied to the drive coil, the movable iron core moves due to attractive force, and when current is not applied, the movable iron core moves to a stable position (e.g., the initial position) due to the biasing force of the return spring.

In such solenoids, when the movable iron core moves toward the fixed iron core and then collides with it, a collision noise (operating noise) is generated. It has been known for some time that by placing an elastic member such as rubber supported on the fixed iron core between the movable iron core and the fixed iron core, the elastic member can absorb the impact when the movable iron core collides with the fixed iron core, thereby reducing the operating noise.

However, if an elastic member is placed between the fixed iron core and the movable iron core, the elastic member will take up most of the surface area where the movable iron core adheres to the fixed iron core due to its attractive force, and a gap will be required between the fixed iron core and the movable iron core. This reduces the axial attractive force of the movable iron core.

Patent Document 1 describes a shock absorption mechanism for a solenoid. This mechanism includes a fixed iron core, a movable iron core that contacts the fixed iron core when the coil is excited, a ring-shaped guide tube, a round shaft-shaped stopper member, and an elastic material.

In Patent Document 1, the fixed core has an attachment hole that opens toward the movable core. The guide tube is made of a magnetic material and is attached coaxially to the attachment hole of the fixed core. The stop member is made of a magnetic material and is slidably incorporated into and supported by the guide tube. The stop member has a stop surface against which the movable core collides and a back surface opposite the stop surface. An elastic material is provided in the attachment hole of the fixed core, facing the back surface of the stop surface, and is in compressed contact with the back surface of the stop surface.

Patent Document 1 states that when the movable iron core moves toward the fixed iron core due to excitation of the coil, the movable iron core collides with the contact surface of the contact member, which pushes the contact member and further compresses the elastic material beyond its original compressed state, thereby absorbing the impact. Furthermore, Patent Document 1 states that after absorbing the impact, the movable iron core is maintained in contact with the contact member by a small holding current.

In other words, Patent Document 1 reduces the operating noise when the movable iron core collides with the fixed iron core, while also magnetically connecting the movable iron core and fixed iron core via the contact member and guide tube, both of which are magnetic materials, which is expected to improve magnetic efficiency.

Patent No. 2769467

However, in the shock absorption mechanism of the solenoid in Patent Document 1, the stop member and guide tube are made of magnetic materials, so it is thought that most of the magnetic flux passing from the movable iron core through the stop member leaks radially and passes from the guide tube to the fixed iron core. When magnetic flux leaks radially in this way, lateral forces are generated in the stop member. This causes the stop member to slide eccentrically against the guide tube, rubbing and wearing out the sliding area. Furthermore, when the stop member wears out, foreign matter such as iron powder is generated, and this wear powder can get into the gap between the movable iron core and the fixed iron core, creating a gap and potentially reducing the axial attractive force.

If the clearance between the stop member and the guide tube were reduced, the eccentricity of the stop member would be suppressed and magnetic efficiency would improve, but the radial attractive force would increase, resulting in greater lateral force and greater wear on the stop member. On the other hand, if the clearance between the stop member and the guide tube were increased, the lateral force would decrease, but the stop member would become more likely to become eccentric, resulting in reduced magnetic efficiency.

In light of these issues, the present invention aims to provide a solenoid that can increase magnetic efficiency while preventing wear on a specific part even if the movable iron core moves toward the fixed iron core and collides with that part.

To solve the above problems, a typical configuration of a solenoid according to the present invention is characterized by comprising a movable iron core, a fixed iron core, a receiving part that is swingably incorporated into the fixed iron core and against which the movable iron core collides when the movable iron core moves toward the fixed iron core, an elastic member arranged on the receiving part opposite the movable iron core, a first tapered surface formed on the side of the receiving part and inclined so that its diameter increases toward the elastic member, a flange that protrudes from the fixed iron core toward the side of the receiving part and positions the receiving part, a second tapered surface formed on the flange and facing the first tapered surface, and a latch magnet that is arranged closer to the movable iron core than the flange and forms a magnetic path that passes through the first tapered surface, the second tapered surface, and the movable iron core.

In the above configuration, when the movable iron core collides with the receiving part as it moves toward the fixed iron core, the elastic member located on the opposite side of the receiving part from the movable iron core is crushed, absorbing the impact and reducing operating noise during the collision.

In addition, a first tapered surface is formed on the side of the receiving part, with the diameter increasing on the elastic member side, and a second tapered surface facing the first tapered surface is formed on the flange that extends from the fixed iron core toward the side of the receiving part. As a result, when the movable iron core collides with the receiving part and crushes the elastic member, the first tapered surface moves away from the second tapered surface, preventing the two from sliding together. Furthermore, the clearance between the two increases, reducing lateral force and preventing the receiving part from becoming eccentric. As a result, the first tapered surface and the second tapered surface do not rub against each other, preventing wear on the receiving part. This prevents the receiving part from wearing out and generating foreign matter such as iron powder, thereby preventing a decrease in performance.

Furthermore, after the movable iron core and receiving part collide, when the crushed elastic member returns to its original position, the first tapered surface of the receiving part comes into contact with and follows the second tapered surface of the flange of the fixed iron core, automatically aligning itself, and the first tapered surface and the second tapered surface come into close contact. Because the receiving part is aligned, the side of the receiving part and the inner surface of the flange do not slide, so there is no wear. Furthermore, the magnetic flux of the magnetic path formed by the latch magnet passes through the closely-fitted first and second tapered surfaces, generating an attractive force between the receiving part and the flange of the fixed iron core. This allows the receiving part to be stably fixed to the flange, ensuring reliable positioning and further increasing magnetic efficiency.

In addition, because the magnetic flux passing through the first tapered surface of the receiving part and the second tapered surface of the flange is perpendicular to the first tapered surface, an attractive force can be generated between the receiving part and the flange. Therefore, even if the elastic member is crushed by a collision between the movable iron core and the receiving part, the attractive force ensures that the receiving part can return to its original position, improving the stroke accuracy of the movable iron core.

This invention provides a solenoid that can increase magnetic efficiency while preventing wear on a specific part even if the movable iron core moves toward the fixed iron core and collides with it.

1 is a diagram showing a schematic configuration of a solenoid according to an embodiment of the present invention; 2 is a diagram showing a state in which the movable iron core collides with the fixed iron core in the solenoid of FIG. 1;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values shown in these embodiments are merely examples intended to facilitate understanding of the invention and, unless otherwise specified, do not limit the present invention. Furthermore, in this specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

Figure 1 is a diagram showing the general configuration of a solenoid 100 according to an embodiment of the present invention. The diagram shows the movable iron core 102 of the solenoid 100 in its initial position. The solenoid 100 comprises the movable iron core 102, a fixed iron core 104, a coil 106, and a receiving part 108. A shaft 103 is inserted through the center of the movable iron core 102, and the shaft 103 moves as the movable iron core 102 moves.

The fixed core 104 has a bottom 110 and a side 112, with the bottom 110 facing the end 114 of the movable core 102. The coil 106 generates an attractive force when excited. The direction of movement of the movable core 102 is changed depending on the excitation direction (direction of current) of the coil 106. After the movement is complete, the current to the coil 106 is cut off, and the movable core 102 is held in place by a latch magnet (magnet 128) described below. The coil 106 is formed, for example, by winding a wire around a bobbin 115 made of resin.

The receiving part 108 is a part that is swingably mounted on the fixed core 104, and has a receiving surface 116 that faces the end 114 of the movable core 102, a side surface 118 that faces the side 112 of the fixed core 104, and a bottom surface 120 that faces the bottom 110 of the fixed core 104.

When the coil 106 is energized and the movable core 102 moves toward the fixed core 104, the end 114 of the movable core 102 collides with and receives the receiving surface 116 of the receiving part 108. A first tapered surface 122 is formed on the side surface 118 of the receiving part 108. The first tapered surface 122 is inclined so that its diameter increases as it approaches the bottom surface 110 of the receiving part 108.

The solenoid 100 further includes a flange 124, an elastic member 126, and a latching magnet (magnet 128). The flange 124 protrudes from the side portion 112 of the fixed core 104 toward the side surface 118 of the receiving part 108, and positions the receiving part 108. The flange 124 also has a second tapered surface 130 formed thereon. The second tapered surface 130 is formed to face the first tapered surface 122 of the receiving part 108.

The figure shows representative radius dimensions La and Lb at the same height of the first tapered surface 122 of the receiving part 108 and the second tapered surface 130 of the flange 124. As shown, dimension Lb is larger than dimension La, so the radius of the second tapered surface 130 is larger than the radius of the first tapered surface 122 at the same height for the first tapered surface 122 and the second tapered surface 130.

The elastic member 126 is positioned on the bottom surface 120 of the receiving part 108, i.e., the side opposite the movable iron core 102, and is attached to the bottom surface 120 by vulcanization bonding or the like. The magnet 128 is positioned closer to the movable iron core 102 than the flange 124 formed on the side portion 112 of the fixed iron core 104, and forms a magnetic path R.

As shown, magnetic path R takes a path in which magnetic flux from magnet 128 passes through side 112 of fixed core 104, through movable core 102, and then through first tapered surface 122 of receiving part 108 and second taper 130 of flange 124, returning to magnet 128. When coil 106 is not energized, the movable core 102 is latched by the attractive force of magnet 128 (magnetic flux passing through magnetic path R).

Next, we will explain the operation of the solenoid 100 when the current to the energized and excited coil 106 is turned off and de-energized. Figure 2 shows the state in which the movable iron core 102 of the solenoid 100 in Figure 1 has collided with the fixed iron core 104.

In the solenoid 100, when the coil 106 is energized, the movable core 102 moves toward the fixed core 104 as shown in Figure 2(a), and the end 114 of the movable core 102 collides with the receiving surface 116 of the receiving part 108 (see arrow B).

When the end 114 of the movable iron core 102 collides with the receiving surface 116 of the receiving part 108, the elastic member 126, which is located on the opposite side of the receiving part 108 from the movable iron core 102, is crushed. This allows the solenoid 100 to absorb the impact of the collision, thereby reducing operating noise during the collision.

In addition, in the solenoid 100, a first tapered surface 122 is formed on the side surface 118 of the receiving part 108, with the diameter increasing on the elastic member 126 side, and a second tapered surface 130 facing the first tapered surface 122 is formed on the flange 124 that protrudes from the side portion 112 of the fixed core 104 toward the side surface 118 of the receiving part 108.

As a result, as shown in Figure 2(a), when the movable iron core 102 collides with the receiving part 108 and the elastic member 126 is crushed, the first tapered surface 122 separates from the second tapered surface 130. As a result, the first tapered surface 122 and the second tapered surface 130 do not slide against each other, and the clearance between them increases, reducing lateral force and preventing the receiving part 108 from becoming eccentric.

This prevents the first tapered surface 122 and the second tapered surface 130 from rubbing against each other, preventing wear on the receiving part 108. Therefore, the solenoid 100 can avoid the receiving part 108 from wearing out and generating foreign matter such as iron powder, thereby maintaining the effect of reducing operating noise.

Furthermore, as shown in Figure 2(b), after the collision between the movable iron core 102 and the receiving part 108, when the coil 106 is de-energized and the crushed elastic member 126 returns to its original position (see arrow C), the first tapered surface 122 of the receiving part 108 comes into contact with the second tapered surface 130 of the flange 124 of the fixed iron core 104 and follows this, generating a centripetal force (see arrow D). This automatically aligns the receiving part 108, and further brings the first tapered surface 122 and the second tapered surface 130 into close contact. Furthermore, because the receiving part 108 is aligned, the side surface 118 of the receiving part 104 and the inner surface of the flange 124 on which the second tapered surface 130 is formed do not slide and therefore do not wear out.

When the coil 106 is de-energized, the magnetic flux of the magnetic path R formed by the magnet 128 passes through the closely spaced first tapered surface 122 and second tapered surface 130, generating an attractive force between the receiving part 108 and the flange 124 of the fixed core 104. This allows the solenoid 100 to stably fix the receiving part 108 to the flange 124, ensuring reliable positioning and further increasing magnetic efficiency.

Furthermore, the magnetic flux R (caused by the magnet 128) passing through the first tapered surface 122 of the receiving part 108 and the second tapered surface 130 of the flange 124 is perpendicular to the first tapered surface 122, and therefore generates an attractive force between the receiving part 108 and the flange 124 due to the magnet 128. Therefore, in the solenoid 100, even if the elastic member 126 is crushed by a collision between the movable iron core 102 and the receiving part 108, the attractive force of the magnet 128 can reliably return the receiving part 108 to its original position, thereby improving the stroke accuracy of the movable iron core 102.

Furthermore, in the solenoid 100, even after the receiving part 108 returns to its original position due to the attractive force of the magnet 128, the magnetic flux of the magnetic path R formed by the magnet 128 passes through the closely spaced first tapered surface 122 and second tapered surface 130, as shown in Figure 1. This ensures that the movable core 102 is securely held with its end 114 in contact with the receiving surface 116 of the receiving part 108, maintaining it in its initial position.

Note that while the elastic member 126 has been described as being attached to the bottom surface 120 of the receiving part 108 by vulcanization bonding or the like, this is not limited to this. As an example, the elastic member 126 may be a rubber stopper that is vulcanization bonded not only to the bottom surface 120 of the receiving part 108 but also to the bottom 110 of the fixed iron core 104. In this way, the receiving part 108 is indirectly fixed to the bottom 110 of the fixed iron core 104 via the elastic member 126, thereby making it possible to more stabilize the position of the receiving part 108.

While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art could conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

The present invention can be used as a solenoid having a latching magnet that holds a movable iron core.

100...Solenoid, 102...Armature core, 103...Shaft, 104...Fixed core, 106...Coil, 108...Receiving part, 110...Bottom of the fixed core, 112...Side of the fixed core, 114...End of the movable core, 115...Bobbin, 116...Receiving surface of the receiving part, 118...Side of the receiving part, 120...Bottom surface of the receiving part, 122...First tapered surface, 124...Flange, 126...Elastic member, 128...Latching magnet, 130...Second tapered surface, R...Magnetic path

Claims (1)

A movable iron core;
A fixed core;
a receiving part that is swingably incorporated into the fixed iron core and that the movable iron core collides with when the movable iron core moves toward the fixed iron core;
an elastic member disposed on the opposite side of the receiving part from the movable iron core;
a first tapered surface formed on a side surface of the receiving part and inclined so that the diameter increases toward the elastic member;
a flange that projects from the fixed iron core toward a side surface of the receiving part and positions the receiving part;
a second tapered surface formed on the flange and facing the first tapered surface;
a latch magnet that is disposed closer to the movable core than the flange and forms a magnetic path that passes through the first tapered surface, the second tapered surface, and the movable core.