JP6834669B2 - Actuator and actuator drive method and magnetic circuit and magnetic circuit control method - Google Patents

Description

The present invention relates to an actuator that operates by utilizing the magnetic force of an electromagnet and a permanent magnet, and a magnetic circuit that can be used for the actuator.

Actuators that use the magnetic force of electromagnets and permanent magnets to attract and release armatures to the yoke are known. The following Patent Document 1 shows a yoke (13) and an armature (31) that is attracted to and released from the yoke (13). The armature (31) is maintained in an attracted state by the magnetic force of the first and second permanent magnets (16, 17). When the armature (31) is in the attracting state, the magnetism of the second permanent magnet (17) is reversed by the pulsed energization of the coil (11), and the force for attracting the armature (31) is lost. Then, the armature (31) is released from the yoke (13) by the release spring (32). The reference numerals in parentheses are the reference numerals used in Patent Document 1 below, and are not related to the reference numerals used in the description of the embodiments of the present application.

Japanese Unexamined Patent Publication No. 1-35331

In order to generate a magnetic flux that reverses the magnetism of a permanent magnet, it is necessary to pass a large current through the coil.

An object of the present invention is to reduce the electric power when releasing the armature.

The actuator according to the present invention has a magnetic flux in a magnetic circuit including a yoke, an armature that can be attracted to and released from the yoke, a first permanent magnet that attracts the armature to the yoke by magnetic force, and a yoke, an armature, and a first permanent magnet. The first permanent magnet has a coil that causes the armature to release the armature and a release spring that urges the armature to release the armature from the yoke, and the magnetic flux density of the first permanent magnet irreversibly decreases when the armature is released from the yoke. An actuator that maintains the released state of the armature.

With the armature attracted to the yoke, the coil generates a magnetic flux in the direction opposite to the magnetic flux of the first permanent magnet, canceling at least a part of the magnetic flux of the first permanent magnet, and the urging force of the release spring is increased. Try to win. When the armature is released from the yoke, the magnetic flux density of the first permanent magnet is irreversibly reduced, and the released state of the armature is maintained by the urging force of the release spring. Since it is not necessary to invert the magnetic flux of the first permanent magnet by the magnetic flux generated by the coil, the current flowing through the coil can be reduced.

In the actuator, the operating point of the first permanent magnet can be made to exceed the knick point by releasing the armature from the yoke.

Further, in the above-mentioned actuator, when the armature is attracted to the yoke, the coil has a magnetic flux in the direction opposite to the magnetic flux of the first permanent magnet within a range in which the operating point of the first permanent magnet does not exceed the knick point. Can be generated in the magnetic circuit so that the release spring releases the armature from the yoke.

Further, in the actuator, the second permanent magnet can be provided in the magnetic circuit including the yoke, the armature and the first permanent magnet. The second permanent magnet is in parallel with the first permanent magnet when the armature is attracted to the yoke, and the armature is attracted to the yoke by magnetic force together with the first permanent magnet. When the armature is released from the yoke, the second permanent magnet reverses the polarity of the first permanent magnet by its magnetic flux, the first permanent magnet and the second permanent magnet are in series, and the magnetic force does not act on the armature.

In another aspect of the magnetic circuit according to the present invention, the magnetic flux density is irreversible by attracting the armature to the yoke by the yoke, the armature that can be attracted to and released from the yoke, and the armature being released from the yoke by magnetic force. It is a magnetic circuit having a first permanent magnet which is lowered to.

In the above magnetic circuit, the operating point of the first permanent magnet can be made to exceed the knick point by releasing the armature from the yoke.

Further, in the above magnetic circuit, when the armature is attracted to the yoke, the magnetic flux in the direction opposite to the magnetic flux of the first permanent magnet within the range where the operating point of the first permanent magnet does not exceed the knick point is the said. When generated in a magnetic circuit, the armature can be released from the yoke by a pre-applied urging force.

Further, the magnetic circuit may further have a second permanent magnet, and the second permanent magnet is in parallel with the first permanent magnet when the armature is attracted to the yoke, together with the first permanent magnet. The armature is attracted to the yoke by magnetic force. When the armature is released from the yoke, the second permanent magnet reverses the polarity of the first permanent magnet by its magnetic flux and becomes in series with the first permanent magnet, and the magnetic force does not act on the armature.

According to the present invention, when the armature is released from the yoke, it is not necessary to reverse the magnetism of the first permanent magnet, and the current flowing through the coil can be reduced.

It is a schematic diagram which shows the structure of the actuator of this embodiment. It is explanatory drawing of the BH curve. It is explanatory drawing of the BH curve of the permanent magnet of a different holding force. And movement of the armature is a diagram showing a relationship between magnetic force (F _Ma, F _Mb) and the armature requires a driving force (F _R). It is a schematic diagram which shows the structure of the actuator of another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the configuration of the actuator 10 of the present embodiment. (A) shows a state in which the armature 14 is attracted to the yoke 12 and is joined (hereinafter, referred to as "adsorption state"), and (b) is a state in which the armature 14 is released from the yoke 12 and separated from the yoke 12. Indicates the state (hereinafter referred to as "released state").

The yoke 12 and the permanent magnets 16 arranged therein form a substantially U-shaped magnetic path. The permanent magnet 16 is a magnet having a small holding force and whose polarity can be easily reversed. Hereinafter, the permanent magnet 16 will be referred to as a variable permanent magnet 16. The variable permanent magnet 16 can be, for example, an alnico magnet. The armature 14 can be adsorbed and released with respect to the yoke 12. The armature 14 is urged by the release spring 18 in a direction away from the yoke 12. This urging force is referred to as " _FE ". When the armature 14 is attracted to and joined to the yoke 12, it is joined to both ends of the U-shape of the yoke 12, and a magnetic path closed by the yoke 12, the armature 14, and the variable permanent magnet 16 is formed. A coil 20 is arranged so as to penetrate the inside of the closed magnetic path, and the coil 20 can generate a magnetic flux in a magnetic circuit formed by a yoke 12, an armature 14, and a variable permanent magnet 16.

When the armature 14 is in the attracted state, the magnetic path is closed, so that the variable permanent magnet 16 holds the magnetic force. The magnetic force acting to adsorb the armature 14 to the yoke 12 referred to as "F _M". The magnetic force F _M overcomes the biasing force F _E of the release spring 18, the armature 14 is maintained in the suction state. The magnetic flux generated by the variable permanent magnet 16 when the armature 14 is in the attracted state is indicated by “Φ”. When the armature 14 is in the attracted state, a current that generates a magnetic flux in the direction opposite to the magnetic flux Φ by the variable permanent magnet 16 is passed through the coil 20 to cancel at least a part of the magnetic flux Φ. That is, in FIG. 1, a current is passed through the coil 20 in the direction of penetrating the paper surface from the back side to the front side to generate a magnetic flux in the magnetic path formed by the yoke 12 and the armature 14, and the magnetic flux Φ due to the variable permanent magnet 16 is reduced. .. By the magnetic flux Φ decreases, the biasing force F _E of the release spring 18 exceeds the magnetic force F _M, the armature 14 is released from the yoke 12. When the armature 14 is released, the magnetic path is opened, the magnetic flux Φ is reduced, and the variable permanent magnet 16 is self-demagnetized. That is, the variable permanent magnet 16 is a magnet having a property of self-demagnetizing when the magnetic path is opened.

When the armature 14 is in the released state or the magnetic force F _M is small, or zero, a state won biasing force F _E of the release spring 18. At this time, the released state of the armature 14 is maintained even if the energization of the coil 20 is stopped. Further, the armature 14 is also in close proximity to the yoke 12 by an external force such as vibration, because the magnetic force F _M is small, adsorption to the yoke 12 of the armature 14 is suppressed. Further, it is possible to suppress the adhesion of foreign matter such as iron powder to the yoke 12.

To attract the armature 14, the coil 20 is energized. The current flowing through the coil 20, the yoke 12, a magnetic flux is generated in the magnetic circuit formed by the armature 14 and the variable permanent magnet 16, the biasing force F _E is greater than the armature 14 of the magnetic force F _M caused by magnetic flux releases spring 18 It is attracted to the yoke 12. Further, the variable permanent magnet 16 is magnetized again by the magnetic flux generated by passing an electric current through the coil 20. When the armature 14 is attracted to the yoke 12, the magnetic flux is maintained, so that the variable permanent magnet 16 does not self-demagnetize and the magnetic force is maintained.

The actuator 10 operates if a current is passed through the coil 20 when the armature 14 is attracted and released, and it is not necessary to pass a current through the coil 20 in order to maintain the attracted state and the released state. Further, when the armature 14 is released, it is not necessary to reverse the magnetism of the variable permanent magnet 16, and the current flowing through the coil 20 to release the armature 14 can be suppressed.

FIG. 2 is a diagram showing a magnetization curve (BH curve). The vertical axis is the magnetic flux density of the permanent magnet, and the horizontal axis is the magnetic field acting on the permanent magnet.

Since a demagnetizing field that weakens its own magnetic field acts on the permanent magnet, the operating point of the permanent magnet at that time is located in the region of H <0 even if the surrounding magnetic field is 0. ing. The operating point at this time is indicated by point p. When an external magnetic field opposite to the magnetic flux of the permanent magnet is applied, the operating point moves in the negative direction of the horizontal axis (H axis) according to the magnetic force. At this time, since the magnetic flux density is also reduced by the external magnetic field, the operating point also moves in the negative direction with respect to the vertical axis (B axis). That is, as the external magnetic field in the opposite direction is increased, the operating point moves on a line that gradually descends toward the lower left. Within the range up to the point q in FIG. 2, if the external magnetic field is removed, the operating point returns on the original line and returns to the original point p. The range up to this point q is called the reversible demagnetization region. When an external magnetic field exceeding the point q acts, the magnetic flux density drops sharply. For example, when the operating point moves to the point r and the external magnetic field in the opposite direction is reduced (positive direction on the H axis), the operating point does not return on the line reaching the point r and is a point. It moves along the alternate long and short dash line in the figure, which is almost parallel to the line between p and point q. The operating point does not return to the point p even when the external magnetic field becomes 0, but reaches the point p'that intersects the _{line G 1 connecting the point p and the origin.} The region beyond the point q is called the irreversible demagnetization region, and the point p, that is, the boundary between the reversible demagnetization region and the irreversible demagnetization region is called a knick point.

The operating point also moves by increasing the magnetoresistance of the magnetic circuit instead of applying an external magnetic field. By increasing the magnetic resistance, the magnetic flux density of the permanent magnet decreases, and the operating point moves from the point p to the point q and further to the point r. For example, it is possible to increase the magnetic resistance by increasing the gap in the magnetic circuit, a large gap in the magnetic circuit from the state of the dashed lines G _1, the operating point moves toward the point p to the point q. If the gap is restored before the operating point reaches the point q (knick point), the operating point returns to the point p. When the gap is increased beyond the point q (for example, line G ₂ ) and the operating point enters the irreversible region (for example, point r), the operating point returns to point p even if _{the gap is returned to the original (line G 1).} Instead, it becomes a point p'.

FIG. 3 is a diagram showing BH curves of the permanent magnets a and the permanent magnets b having different holding forces. The permanent magnet a has a smaller holding force than the permanent magnet b. The permanent magnet b having a large holding force has a wide reversible demagnetization region. For example, the gap in the magnetic circuit is widened _{from the state of G 1 to} the state of G ₂ , and the operating point moves from the point b _{1 to the point b 2.} However, since the knick point q _b is not exceeded, if the gap is _{returned to the original state (G 1} ), the operating point returns to the _{point b 1.} On the other hand, when the gap is widened, the permanent magnet a having a small holding force returns _{to the original point a 1} if the operating point is within the range up to the _{point a 2} (knick point q _a). However, the operating point exceeds the point a _2, for example, reaches a point b ₂ and the point a ₃ became equal gap state, the operating point to revert gap a point a _4.

4, in the actuator 10, shown as force to move the armature 14 against the biasing force F _E release spring 18 (hereinafter referred to as "armature required driving force F _R."), The relationship between the magnetic force F _M Figure Is. Armature required driving force F _R is the ideal state without friction, a biasing force F _E and the magnitude is the same orientation opposing force of the release spring _{18 (F R = -F E)} . In order to simplify the explanation, the case where there is no friction or the like will be described below.

4, the armature demanded drive force F _R is indicated by a dashed line. The magnetic force F _Ma of the variable permanent magnet 16 is shown by a solid line, and the broken line shows _{the magnetic force F M b} when a permanent magnet having a large holding force is provided instead of the variable permanent magnet 16. In addition, points a _{1 to} a ₄ and points b _{1 to} b ₂ shown in FIG. _{4 correspond to points a 1 to} a 4 and points b _{1 to} b ₂ in FIG.

In the case of a permanent magnet b (for example, a neodymium magnet) having a large holding force, even if the armature 14 is released and the magnetic resistance of the magnetic circuit increases, the operating point is in the reversible demagnetization region, so that the armature 14 is attracted again. the force F _Mb is returned to b ₁ original point. Therefore, when the armature 14 is moved by a disturbance such as vibration and approaches the yoke 12, the armature 14 may be in a suction state in a situation different from the original intention. On the other hand, in the permanent magnet a having a small holding force, the magnetic force F _Ma when the once released armature 14 is brought close to the yoke 12 and joined is as small as the point a ₄ , so even if the armature 14 approaches the yoke 12. , The armature 14 is unlikely to be in a suction state. Further, as shown in FIG. 4, when the point a ₄ is less than the required driving force F _{R of the armature, the urging force F E} of the release spring exceeds the magnetic force F _Ma , so that the armature 14 is prevented from being unintentionally attracted to the yoke 12. can do. In other words, the dissociated state of the armature 14 can be reliably maintained. Further, in the permanent magnet a having a small holding force, the magnetic force F _{Ma sharply decreases when the knick point q a} (point a ₂ ) is exceeded, so that the magnetic force F _Ma (point a ₃ ) in the released state also becomes small. As a result, it is possible to prevent foreign matter from adhering to the yoke 12 while the armature 14 is open.

To release the armature 14 from the yoke 12 may be energized to the coil 20 to the magnetic force F _Ma falls below the armature required driving force F _R. Thereafter, the armature 14 is driven by the biasing force F _E of the release spring 18. In the permanent magnet a having a small holding force, even if the magnetic force in the attracted state is the same as the magnetic force of the permanent magnet having a large holding force (a ₁ = b ₁ ), the magnetic force after passing the knick point q _a (point a _2). Since F _Ma drops sharply, the energization time of the coil 20 can be shortened as compared with the permanent magnet b having a large holding force. Therefore, the armature 14 can be released with a small amount of electric power.

Further, in FIG. 4, by a point a ₂ or less armature required driving force F _R, the operating point stops the energization of the coil 20 while not exceeding knick point, ie the operating point does not exceed the knick point It is possible to energize the coil within a range. Due to the subsequent increase in magnetoresistance, the magnetic force of the variable permanent magnet 16 decreases, and the armature 14 is released.

FIG. 5 is a diagram showing a schematic configuration of the actuator 30 of another embodiment. The same components as those of the actuator 10 will be designated by the same reference numerals, and the description thereof will be omitted. Similar to FIG. 1, (a) shows a state in which the armature 14 is adsorbed on the yoke 12, and (b) shows a state in which the armature 14 is released from the yoke 12.

The actuator 30 is newly provided with a permanent magnet 32. The permanent magnet 32 is a magnet having a large holding force and a fixed polarity in the operation of the actuator 30, and will be hereinafter referred to as a fixed permanent magnet 32. The fixed permanent magnet 32 is, for example, a neodymium magnet.

When the armature 14 is in the attracted state, the magnetic flux Φ ₁ of the variable permanent magnet 16 passes through the armature 14 from one side of the yoke 12 and further passes through the other side of the yoke 12 to return to the variable permanent magnet 16. The magnetic path is closed and the magnetic force of the variable permanent magnet 16 is maintained. _{The magnetic flux Φ 2} of the fixed permanent magnet 32 also passes through the armature 14 from one side of the yoke 12, and then returns to the fixed permanent magnet 32 through the other side of the yoke 12. _{The magnetic flux Φ 1} of the variable permanent magnet 16 and the magnetic flux Φ ₂ of the fixed permanent magnet 32 are in parallel, and the variable permanent magnet 16 and the fixed permanent magnet 32 are connected in parallel.

When the armature 14 is in the attracted state, a current that generates a magnetic flux in the direction opposite to the magnetic _{flux Φ 1} by the variable permanent magnet 16 is passed through the coil 20 to reduce _{the magnetic flux Φ 1 of the variable permanent magnet 16.} As the magnetic force at this time is lower than the biasing force F _E of the release spring 18, by previously defining a magnetic characteristic of the variable permanent magnets 16 and the fixed permanent magnet 32, armature 14 by the biasing force F _E is released from the yoke 12 The magnet. When the armature 14 is released, the magnetic path is opened, the magnetic flux Φ ₁ is reduced, and the variable permanent magnet 16 is self-demagnetized.

Further, when the armature 14 is released from the yoke 12, _{the magnetic resistance of the magnetic path (the magnetic path along the magnetic flux Φ 2} ) passing through the armature 14 of the fixed permanent magnet 32 increases, and the magnetic flux of the fixed permanent magnet becomes FIG. It flows like the _{magnetic flux Φ 3} shown in (b). The characteristics of the magnetic circuit such as the gap between the armature 14 and the yoke 12, the variable permanent magnet 16 and the fixed permanent magnet 32 are defined so that the magnetic flux flows in this way. The magnetic flux of the fixed permanent magnet 32 acts on the variable permanent magnet 16, so that the polarity of the variable permanent magnet 16 is reversed. As a result, the yoke 12, the variable permanent magnet 16 and the fixed permanent magnet 32 form one closed magnetic path, and the magnetic flux Φ ₃ is formed by these two permanent magnets 16 and 32, and the variable permanent magnet 16 and the fixed permanent magnet are formed. 32 is in a state of being connected in series.

In a state where the armature 14 is released, the magnetic flux [Phi ₃ does not act between the armature 14, in a state in which the urging force F _E won release spring 18, the released state of the armature 14 is also stopped energization of the coil 20 Be maintained. Even if the armature 14 approaches the yoke 12 due to disturbance, it is not attracted to the yoke 12 because no magnetic force is applied. Further, since the magnetic flux that goes out of the yoke 12 is small, it is possible to suppress the adsorption of foreign matter on the magnetic material.

To adsorb the armature 14, flow direction of the current magnetic flux in the opposite direction is generated between the magnetic flux [Phi ₃ the coil 20. When the magnetic flux due to the coil 20 _{exceeds the magnetic flux Φ 3} due to the two magnets, the magnetic flux exits the yoke 12 and passes through the armature 14, and a magnetic force acts on the armature 14. When this force exceeds the biasing force F _E of the release spring 18 the armature 14 is attracted to the yoke 12. Further, the magnetic flux generated by the coil 20 is opposite to the direction of the magnetic flux of the variable permanent magnet 16, and the magnetism of the variable permanent magnet 16 is reversed. When the armature 14 is adsorbed, the state shown in (a) is obtained.

The actuator 30 operates if a current is passed through the coil 20 when the armature 14 is attracted and released, and it is not necessary to pass a current through the coil 20 in order to maintain the attracted state and the released state. Further, when the armature 14 is released, it is not necessary to reverse the magnetism of the variable permanent magnet 16, and the current flowing through the coil 20 when the armature 14 is released can be suppressed.

In the two embodiments described above, the variable permanent magnet 16 is arranged in the yoke 12, but may be arranged in the armature 14. The fixed permanent magnet 32 is arranged in the same component (yoke or armature) as the variable permanent magnet 16. Further, the operating point of the variable permanent magnet 16 in the state where the armature 14 is attracted may be in the irreversible demagnetization region.

10 actuator, 12 a yoke, 14 armature, 16 variable permanent magnet (first permanent magnet) 18 released the spring 20 coils, 30 actuator, 32 fixed permanent magnet (second permanent magnet), with F _E force, F _R armature necessary the driving force, F _M magnetic force, Φ the magnetic flux.

Claims (8)

With York
An armature that can be sucked and released against the yoke,
The first permanent magnet that attracts the armature to the yoke by magnetic force,
A coil that creates magnetic flux in a magnetic circuit that includes a yoke, armature, and first permanent magnet,
A release spring that urges the armature to release it from the yoke,
An actuator driving method of have a,
A method of driving an actuator in which the operating point of the first permanent magnet exceeds the knick point by releasing the armature from the yoke. The method for driving an actuator according to claim 1, wherein when the armature is released from the yoke, the operating point of the first permanent magnet is opposite to the magnetic flux of the first permanent magnet within a range not exceeding the knick point by the coil. A method of driving an actuator in which magnetic flux is generated in a magnetic circuit, the magnetic force generated by the first permanent magnet is reduced, and the armature is released from the yoke by a release spring. The method for driving an actuator according to claim 1 or 2.
The actuator is
Further having a second permanent magnet included in a magnetic circuit including a yoke, armature and first permanent magnet
In the state where the armature is attracted to the yoke, the first permanent magnet and the second permanent magnet are in a parallel state, and the armature is attracted to the yoke by magnetic force.
When the armature is released from the yoke, the polarity of the first permanent magnet is reversed by the magnetic flux of the second permanent magnet, the first permanent magnet and the second permanent magnet are in series, and the magnetic force does not act on the armature.
Actuator,
Actuator drive method. With York
An armature that can be sucked and released against the yoke,
The first permanent magnet that attracts the armature to the yoke by magnetic force,
A coil that creates magnetic flux in a magnetic circuit that includes a yoke, armature, and first permanent magnet,
A release spring that urges the armature to release it from the yoke,
The second permanent magnet included in the magnetic circuit including the yoke, armature and first permanent magnet,
Have,
In the state where the armature is attracted to the yoke, the first permanent magnet and the second permanent magnet are in a parallel state, and the armature is attracted to the yoke by magnetic force.
When the armature is released from the yoke, the polarity of the first permanent magnet is reversed by the magnetic flux of the second permanent magnet, the first permanent magnet and the second permanent magnet are in series, and the magnetic force does not act on the armature.
Actuator. With York
An armature that can be sucked and released against the yoke,
The first permanent magnet that attracts the armature to the yoke by magnetic force,
It is a control method of a magnetic circuit having
A method of controlling a magnetic circuit in which the operating point of the first permanent magnet exceeds the knick point by releasing the armature from the yoke. The magnetic circuit control method according to claim 5, wherein when the armature is released from the yoke, the magnetic flux in the direction opposite to the magnetic flux of the first permanent magnet within the range where the operating point of the first permanent magnet does not exceed the knick point. Is generated in the magnetic circuit, the magnetic force due to the first permanent magnet is reduced, and the armature is released from the yoke by the urging force applied in advance, which is a control method of the magnetic circuit. The method for controlling a magnetic circuit according to claim 5 or 6.
The magnetic circuit
It also has a second permanent magnet
When the armature is attracted to the yoke, the first permanent magnet and the second permanent magnet are in a parallel state, and the armature is attracted to the yoke by magnetic force.
When the armature is released from the yoke, the polarity of the first permanent magnet is reversed by the magnetic flux of the second permanent magnet, the first permanent magnet and the second permanent magnet are in series, and the magnetic force does not act on the armature.
It is a magnetic circuit,
How to control a magnetic circuit . With York
An armature that can be sucked and released against the yoke,
The first permanent magnet that attracts the armature to the yoke by magnetic force,
With the second permanent magnet
Have,
When the armature is attracted to the yoke, the first permanent magnet and the second permanent magnet are in a parallel state, and the armature is attracted to the yoke by magnetic force.
When the armature is released from the yoke, the polarity of the first permanent magnet is reversed by the magnetic flux of the second permanent magnet, the first permanent magnet and the second permanent magnet are in series, and the magnetic force does not act on the armature.
Magnetic circuit.

Images