JP7620190B2 - Bidirectional Actuator - Google Patents

Description

The present invention relates to a bidirectional actuator that can actively move a shaft in both directions.

An example of a typical actuator using a coil and a movable core is the linear actuator disclosed in Patent Document 1. The linear actuator in Patent Document 1 has a fixed body with a coil wound in a ring shape, a first movable body yoke whose circumferential surface faces the coil on the inside or outside of the coil, and a movable body with a pair of magnets stacked on both sides of the first movable body yoke in the axial direction with the same poles facing the first movable body yoke.

In the linear actuator of Patent Document 1, the movable body is driven in the axial direction by passing electricity through the coil. According to the configuration of Patent Document 1, the magnet only needs to be magnetized in the axial direction, which means that magnetization is easy even when the product is miniaturized, unlike magnets magnetized in the radial direction, making it suitable for mass production.

JP 2006-158135 A

In a bidirectional actuator, it is necessary to control the stroke width of the movable body when it is in operation. In Patent Document 1, a bearing plate (bearing member) is fixed to the openings on both sides of the fixed body in the axial direction. This allows the bearing plate (bearing member) to regulate the stroke width of the movable body when it is in operation. However, with the configuration of Patent Document 1, it is not possible to hold the movable body when it is not in operation. As a result, it is not possible to regulate the position of the movable body when it is not in operation, and its behavior when it is not in operation becomes unstable.

The present invention aims to provide a bidirectional actuator that can regulate the stroke width of the moving element when in operation and can hold the moving element when not in operation.

To solve the above problems, a typical configuration of a bidirectional actuator according to the present invention includes a cylindrically wound coil, a fixed yoke that covers the coil, and a movable element that moves in both directions inside the fixed yoke in the axial direction of the coil, the inner surface of the fixed yoke having circumferential slits formed therein, the movable element having two magnets with opposing magnetic poles arranged in the axial direction, a movable yoke that protrudes like a flange arranged between the two magnets, and the movable yoke arranged between the slits of the fixed yoke.

According to the above configuration, the movable yoke, which protrudes like a flange between two magnets, is placed between the slits of the fixed yoke. As a result, when the bidirectional actuator is in operation, the movable element moves within the range of the slits of the fixed yoke. This makes it possible to appropriately regulate the stroke width of the movable element when in operation. And when not in operation, the movable body is attracted to and held at one of the two ends of the slits of the fixed yoke. This makes it possible to stabilize the behavior when not in operation.

It is preferable to further provide a second movable yoke on the outside of each of the two magnets, with the flange-shaped protruding movable yoke at the center. With this configuration, it is possible to reduce the air gap in the magnetic path. Therefore, it is possible to enhance the above-mentioned effects.

The present invention provides a bidirectional actuator that can regulate the stroke width of the moving element when in operation and hold the moving element when not in operation.

1 is an overall configuration diagram of a bidirectional actuator according to an embodiment of the present invention; FIG. 2 is a diagram illustrating an actuator in an excited state (during operation). 11A and 11B are diagrams illustrating another example of the bidirectional actuator of the present embodiment. 11A and 11B are diagrams illustrating another example of the bidirectional actuator of the present embodiment.

The preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific values shown in the embodiment are merely examples to facilitate understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements that have substantially the same function and configuration are given the same reference numerals to avoid duplicated explanations, and elements that are not directly related to the present invention are not illustrated.

Figure 1 is an overall configuration diagram of a bidirectional actuator according to this embodiment (hereinafter referred to as actuator 100), showing the state in which both coils 110 are not excited, i.e., the actuator 100 is not in operation. There is no distinction between up, down, left, and right in the actuator 100 according to this embodiment, and the terms "up, down, left, and right" used below simply refer to up, down, left, and right on the drawing.

The actuator 100 shown in FIG. 1 has a coil 110 wound in a cylindrical shape. The coil 110 is covered by a fixed yoke 120. The fixed yoke 120 is made of a magnetic material and forms a magnetic circuit.

A mover 130 that moves in both directions along the axial direction of the coil 110 is disposed inside the fixed yoke 120. The mover 130 has two magnets (hereinafter referred to as upper magnet 132a and lower magnet 132b) with opposing magnetic poles disposed in the axial direction, and a movable yoke 134 that protrudes like a flange is disposed between the two magnets. In this embodiment, the opposing magnetic poles of the upper magnet 132a and lower magnet 132b are exemplified as N poles, and the opposite magnetic pole as S poles.

A circumferential slit 122 is formed on the inner peripheral surface of the fixed yoke 120 near the center of the coil 110. The flange portion 136 of the movable yoke 134 is arranged so as to be inserted between the slits 122 of the fixed yoke. The flange portion 136 of the movable yoke 134 is also sandwiched between the north poles of the upper magnet 132a and the lower magnet 132b, making it the north pole.

Figure 1 illustrates an example of a non-excited state (non-operating state) in which the flange portion 136 of the movable yoke 134 is attracted to and held by the fixed yoke 120 at the top of the slit 122. In the actuator 100 in the non-excited state shown in Figure 1, the magnetic flux M1 of the upper magnet 132a flows from the north pole through the movable yoke 134 and a part of the fixed yoke 120 to the south pole of the upper magnet 132a. The magnetic flux M2 of the lower magnet 132b flows from the north pole to the south pole of the lower magnet 132b, making a large circle around the flange portion 136 and the fixed yoke 120.

Figure 2 is a diagram illustrating the actuator 100 in an excited state (operating). Figure 2(a) is a diagram illustrating the actuator 100 in a state where a current is flowing (excited state). Figure 2(b) shows the actuator 100 in a state where a current is flowing in the opposite direction to that in Figure 2(a) (excited state).

When a current is applied to the coil 110 shown in FIG. 2(a), the magnetic flux M1 of the upper magnet 132a and the magnetic flux M2 of the lower magnet 132b flow in the same direction as in FIG. 1. When a current flows, the coil 110 becomes excited, and a magnetic flux M0 flows through the fixed yoke 120. At this time, the upper end 124 of the slit 122 of the fixed yoke 120 becomes an S pole, and the lower end 126 of the slit becomes an N pole. Then, the flange portion 136 of the mover 130 repels the lower end 126 of the slit 122 and is attracted to the upper end 124 of the slit 122. Then, when the current is stopped in the state shown in FIG. 2(a), the mover 130 is attracted to the fixed yoke 120 at the end 124 and held there.

On the other hand, when a current is passed through the coil 110 in the opposite direction as shown in FIG. 2(b), the coil 110 is excited in the opposite direction, and the magnetic flux M0 flowing through the fixed yoke 120 is reversed. At this time, the upper end 124 of the slit 122 of the fixed yoke 120 becomes the north pole, and the lower end 126 of the slit 122 becomes the south pole. Then, the flange portion 136 of the mover 130 repels the upper end 124 of the slit 122, and an attractive force is generated between the flange portion 136 and the lower end 126 of the slit 122, causing the mover 130 to move downward.

When the mover 130 moves downward, the magnetic flux M1 of the upper magnet 132a flows from the north pole, around the flange portion 136 and the fixed yoke 120, to the south pole of the upper magnet 132a. The magnetic flux M2 of the lower magnet 132b flows from the north pole, through the moveable yoke 134 and part of the fixed yoke 120, to the south pole of the lower magnet 132b. Then, when the current is stopped in the state shown in FIG. 2(b), the mover 130 is attracted to the fixed yoke 120 at the end 126 and held there.

As described above, in the actuator 100 of this embodiment, the flange portion 136 of the movable yoke 134 is disposed between the slits 122 of the fixed yoke 120, so that the movable member 130 moves within the range of the slits 122 of the fixed yoke 120. Therefore, it is possible to appropriately regulate the stroke width of the movable member 130 during operation.

As described above, when the coil 110 is de-energized, the mover 130 is attracted to and held by the fixed yoke 120 at the end of the fixed yoke 120 that was closer when the coil 110 was energized. Therefore, it is possible to maintain the position of the mover 130 even when the coil 110 is not in operation.

Figure 3 is a diagram illustrating another example of the bidirectional actuator of this embodiment. The bidirectional actuator shown in Figure 3 (hereinafter referred to as actuator 200) has inclined surfaces 224 above and below the slit 122 of the fixed yoke 220. On the other hand, the movable member 230 has inclined surfaces 238 above and below the flange portion 136.

As shown in FIG. 1, when the end faces of the slit 122 are flat and the upper and lower faces of the flange portion 136 of the movable member 130 are also flat, the suction force increases steeply inversely proportional to the square of the distance (spacing) between them.

However, by opposing the inclined surfaces 224, 238 as shown in FIG. 3, the gap (distance) between the movable member 230 and the fixed yoke 220 can be reduced from a position where the movable member 230 is far from the top dead center or bottom dead center. In other words, the magnetic attraction force between the movable member 230 and the fixed yoke 220 can be gradually strengthened. This allows the desired attraction force to be generated within the stroke range of the movable member 230, stabilizing its behavior. In addition, because the magnetic force can be suppressed, the impact and noise generated when the flange portion 136 hits the fixed yoke 220 can be mitigated.

Figure 4 is a diagram illustrating another example of the bidirectional actuator of this embodiment. The bidirectional actuator shown in Figure 3 (hereinafter referred to as actuator 300) has two second movable yokes 302a and 302b arranged adjacent to the surface of two magnets (upper magnet 132a and lower magnet 132b) opposite the surface facing the movable yoke 134. This configuration makes it possible to reduce the air gap in the magnetic path and enhance the above-mentioned effects.

Although the preferred embodiment of the present invention has been described above with reference to the attached 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 come up with various modified or revised examples 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 an actuator that can actively move a shaft in both directions.

M0...magnetic flux, M1...magnetic flux, M2...magnetic flux, 100...actuator, 110...coil, 120...fixed yoke, 122...slit, 124...end, 126...end, 130...movable element, 132a...upper magnet, 132b...lower magnet, 134...movable yoke, 136...flange portion, 200...actuator, 220...fixed yoke, 224...inclined surface, 230...movable element, 238...inclined surface, 300...actuator, 302a, 302b...second movable yoke

Claims (1)

A cylindrically wound coil;
A fixed yoke that covers the coil;
a mover that moves in both directions in the axial direction of the coil inside the fixed yoke,
The fixed yoke has an inner peripheral surface formed with a circumferential slit,
The mover is
Two magnets with opposing poles are arranged in the axial direction.
A movable yoke having a flange portion protruding in a flange shape is disposed between the two magnets,
The flange portion of the movable yoke is disposed so as to be inserted between the slits of the fixed yoke ,
A bidirectional actuator, characterized in that, when the coil is in a non-excited state, a flange portion of the movable yoke is attracted to and held by the fixed yoke at an upper or lower portion of a slit.

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