JPS6046803B2 - Switchable permanent magnet holding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switchable permanent magnet holding device for holding or being held by a magnetic body.

One of the conventional permanent magnet holding devices of this type includes a magnetic circuit consisting of a pair of magnetic pole members 12 and a non-magnetic plate 14 disposed between the magnetic pole members, as shown in FIG. A block 16 and a cylindrical permanent magnet 18 rotatably disposed within a circular cavity formed in the magnetic circuit block.
Equipped with.

The permanent magnet 18 is magnetized in its diametrical direction, and as shown in FIG. is a magnetically active surface 20 provided on the magnetic pole member 12.
The magnetic circuit block 16 forms a closed loop within the magnetic circuit block 16. Therefore, the magnetically active surface 20 is not excited, and the permanent magnet holding device 10 is kept in a demagnetized state. By rotating the permanent magnet 18 approximately 90 degrees counterclockwise from the non-excited rotational position shown in FIG. Since the magnetic circuit block 16 is in a magnetic equilibrium state at the above-mentioned non-excited rotational position and the excitation rotational position that is perpendicular to the non-excitation rotational position, the permanent magnet 18 is not subjected to magnetic rotational force. do not have.

However, as shown in the graph of FIG. 2, between the excitation rotational position and the non-excitation rotational position of the permanent magnet 18,
Since the magnetic equilibrium state of the magnetic circuit block 16 is disrupted, the permanent magnet 18 is subjected to magnetic rotational force. The horizontal axis of the graph represents the rotation angle (θ) of the permanent magnet 18 from the non-excitation rotational position shown in FIG. 1, and the vertical axis represents the magnetic rotational force (θ) that the permanent magnet 18 receives. T
), and this graph shows the change in the magnetic rotational force when a magnetic substance to be attracted is applied to the magnetically acting surface 20. As is clear from the above graph, the permanent magnet 18 at the energized rotational position with a rotation angle of 90 degrees has a magnetic rotational force toward each non-excitation rotational position where the rotation angle is 0 degrees or 180 degrees in an inverse relationship thereto. However, when the permanent magnet 18 in the energized rotational position (90 degrees) generates a slight rotational force, the permanent magnet 18 moves to one of the non-excitation rotational positions (zero or 180 degrees) is subjected to a strong magnetic rotational force. Therefore, in the conventional permanent magnet holding device 10, when an impact or the like acts on the device, the permanent magnet 18 in the energized rotational position is displaced, and the permanent magnet is moved to the non-excited rotational position by the magnetic rotational force. As a result, the permanent magnet holding device may be unexpectedly demagnetized, causing an unexpected accident.

In particular, in order to reduce the rotational operating force of the permanent magnet 18, the sliding surfaces of the magnetic circuit block 16 and the permanent magnet 18 are made smooth! Therefore, in the permanent magnet holding device 10 in which the mechanical friction force between the two is reduced, the permanent magnet 18 in the excitation rotation position may be displaced even by external forces such as weak vibrations and shocks applied to the device. It has three drawbacks: it is easy to use, and therefore it is easy to cause unexpected demagnetization as described above.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a switchable permanent magnet holding device that does not easily switch from an excitation state to a demagnetization state due to external forces such as vibrations or shocks.

4. In the present invention, when a permanent magnet rotatably arranged in a magnetic circuit block is rotated in one direction from a first non-excited rotational position, the permanent magnet rotates until the rotation angle reaches 90 degrees. When subjected to a negative magnetic rotational force that tends to prevent rotation, on the other hand, when the rotation angle exceeds 90 degrees, the permanent magnet is
Focusing on the fact that the permanent magnet receives a positive magnetic rotational force that attempts to rotate it toward the second non-excited rotational position that has a positional relationship of 0 degrees, when the rotation angle of the permanent magnet exceeds 90 degrees. Means for preventing the permanent magnet from continuing to rotate due to the action of the positive magnetic rotational force is provided on each of the permanent magnet side and the magnetic circuit block side, and both rotation preventing means work together to move the permanent magnet to the exciting rotational position. It is characterized by being held at. The present invention provides a magnetic circuit block comprising a pair of magnetic pole members having magnetically active surfaces and a non-magnetic plate disposed between the magnetic pole members, and in which a cavity extending along the non-magnetic plate and having a circular cross section is formed. , a permanent magnet disposed within the portal cavity so as to be rotatable about the central axis of the cavity, and a rotation angle of the permanent magnet when the magnetically active surface is rotated to switch from a non-excited state to an energized state. When the angle exceeds 90 degrees, means are provided on each of the permanent magnet side and the magnetic circuit block side to cooperate with each other to prevent the permanent magnet from rotating against the magnetically active surface that rotates the permanent magnet. A switchable permanent magnet holding device is provided, characterized in that the magnetically active surface is kept in an energized state.The features of the present invention will become clearer from the following description of the illustrated embodiment. Become.

As shown in FIG. 3, the permanent magnet holding device 30 according to the present invention includes a pair of magnetic pole members 32 and a non-magnetic plate 34 disposed between the magnetic pole members and integrally coupled therewith.
It includes a magnetic circuit block 36 and a permanent magnet 38.

The magnetic circuit block 36 is formed with a conventional cavity 40 for accommodating a permanent magnet 38.

Cavity 40 has a circular cross-section, extends along non-magnetic plate 34 to divide it, and opens at one end of magnetic circuit block 36 . Each magnetic pole member 32 is a magnetic material (not shown)
It has a flat magnetically active surface 42 similar to the conventional one for adsorption of. The permanent magnet 38 is made of a cylindrical permanent magnet as a whole, and is magnetized in the diametrical direction.

Flat surfaces 44 are formed by chamfering on both sides of the permanent magnet 38 in a direction perpendicular to the magnetization direction. Further, at one end of the permanent magnet 38, there is a protrusion 46 that protrudes from the end face and extends in the radial direction in accordance with the magnetization direction.
is formed. This protrusion is provided on the permanent magnet side to resist the magnetic force that rotates the permanent magnet 38 and prevent the permanent magnet from rotating. It constitutes a rotation prevention means. The permanent magnet 38 is housed in the cavity 40 with its protrusion 46 corresponding to the open end of the cavity 40, and is rotatable about the central axis of the cavity 40.

An operation knob 48 for rotating the permanent magnet 38 is fitted into the tip of the protrusion 46 . The rotational position of the permanent magnet 38 shown in FIG. 3 is such that the magnetization direction of the permanent magnet is along the non-magnetic plate 34, and the magnetically active surface 42 is in a non-magnetic position, as described in FIG. This is the non-energized rotational position in the energized state.

Therefore, when the operating knob is rotated counterclockwise when viewed from the operating knob side, the permanent magnet 38 rotated integrally with the operating knob 48 rotates as shown in FIG. 2 according to the rotation angle from the non-excited rotational position. It is subjected to a magnetic rotational force similar to that of In order to regulate the rotation angle of the permanent magnet 38, a through hole 50 is formed in one of the magnetic pole members 32 and opens to the circumferential surface of the cavity 40, and a pin 52 is inserted into the through hole.

The pin 52 is fixed to the magnetic pole member 32, and its tip protrudes into the cavity 40 so as to be able to come into contact with one side of the protrusion 46. As shown in FIG. 4, the tip of the pin 52, that is, the protruding portion, has its end surface abutting one side of the protruding portion 46 of the permanent magnet 38 in the non-excited rotational position, and rotates the permanent magnet clockwise. prevent rotation. Further, when the operating knob 48 is rotated in the counterclockwise direction, the pin 52 is rotated so that the side portion of the protruding portion is connected to the protruding portion 48.
By contacting the side surface of the permanent magnet 38, rotation of the permanent magnet 38 beyond the angle α is prevented. The rotation of the permanent magnet 38 is resisted by the magnetic force that causes the permanent magnet 38 to rotate.
As shown in FIG. 2, the angle α, which is regulated by the protruding portion of the pin 52, which constitutes the rotation prevention means on the magnetic circuit flock side and prevents the magnetic circuit from exceeding 90 degrees, as shown in FIG. The angle is set to be close to 90 degrees and at which the magnetic rotational force is large, for example, 102 degrees.

In the holding device 30 according to the present invention, when the permanent magnet 38 in the non-excited rotational position is rotated in the counterclockwise direction by manual operation of the operating knob 48, the rotation angle is 90°. Until the rotation angle is reached, a magnetic rotational force, that is, a negative magnetic rotational force, acts to prevent the rotation as shown in FIG. 2, as in the conventional case.

When the permanent magnet 38 is rotated beyond 90 degrees by overcoming this magnetic rotational force, a positive magnetic rotational force that assists the rotation acts on the permanent magnet as shown in FIG. .
The permanent magnet 38 attempts to further rotate counterclockwise due to this positive magnetic rotational force, but since the rotation of the permanent magnet 38 is restricted to an angle α by the stopper, as shown in FIG. The permanent magnet 38 is locked at an angle α, as shown by the dashed line in FIG. The permanent magnet 38 at this angle α is at a rotational position slightly larger than the proper excitation rotational position (90 degrees), but since the magnetic flux of the permanent magnet 38 crosses the magnetically active surface 42, the magnetic field The active surface is energized, so that the holding device 30 exerts almost the same magnetic force as in the prior art.

Furthermore, since the above-mentioned positive magnetic rotational force acts on the permanent magnet 38 at the angle α as a biasing force toward the stopper, the permanent magnet 38 is easily moved toward the stopper by vibration or external force. There is no rotation to a non-energized rotational position, and the holding device 30 is not unexpectedly demagnetized as in the prior art. In the demagnetizing device 30, the operating knob 48 is rotated clockwise to overcome the positive magnetic rotational force, thereby returning the permanent magnet 38 to the non-excited rotational position, thereby demagnetizing the permanent magnet 38. I can do it.

In the above description, an example was shown in which a single cylindrical magnet was used as the permanent magnet, but a magnet assembly having a pair of magnetic pole pieces may be used as the five permanent magnets.

Further, instead of the pin, the stopper for regulating the rotation of the permanent magnet may be formed of a protrusion that integrally projects into the cavity from the magnetic pole member. O According to the present invention, as described above, at the excitation rotational position of the permanent magnet that keeps the magnetically active surface of the magnetic circuit block in an excited state, the permanent magnet exerts a magnetic rotational force toward the stopper that restricts this rotation. As a result, the permanent magnet can be reliably held at its excitation rotational position, thereby preventing unexpected demagnetization as in the conventional case.

[Brief explanation of the drawing]

Figure 1 is a side view showing a conventional permanent magnet holding device.
FIG. 2 is a graph showing the rotational characteristics of the permanent magnet holding device according to the present invention, FIG. 3 is an exploded perspective view of the permanent magnet holding device according to the present invention, and FIG. A cross-sectional view taken along the line ■1■ shown in the figure. 32: Magnetic pole member, 34: Non-magnetic plate, 36: Magnetic circuit block, 38: Permanent magnet, 40: Cavity, 42: Magnetic action surface,
46: protrusion, 48: operation knob, 50: through hole, 52:
Stotspa.

Claims (1)

[Scope of Claims] 1. A magnetic device comprising a pair of magnetic pole members each having a magnetically active surface and a non-magnetic plate disposed between the magnetic pole members, in which a cavity extending along the non-magnetic plate and having a circular cross section is formed. a circuit block; a permanent magnet disposed within the cavity so as to be rotatable about the central axis of the cavity; When the rotation angle exceeds 90 degrees, means are provided on the permanent magnet side and the magnetic circuit block side, respectively, for resisting the magnetic acting force that rotates the permanent magnet and blocking the rotation, and the means A switchable permanent magnet holding device, characterized in that the magnetically active surface is held in an excited state by a switchable permanent magnet holding device. 2. The rotation prevention means on the permanent magnet side is a protrusion provided at one end of the permanent magnet and extends in the radial direction, and the rotation prevention means on the magnetic circuit block side is provided on the magnetic circuit block. , a stop extending into the cavity and capable of abutting a side surface of the protrusion of the permanent magnet.