JPH0517786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a permanent magnet machine, and particularly to a structure of a field magnet suitable for a linear actuator. The same technology as this type of actuator includes those called linear step motors and linear pulse motors, and the permanent magnet machine of the present invention is similarly applicable to these motors.

[Conventional technology]

Linear pulse motors are generally
It is constructed as described in the publication No. 74080, and the stator 11 in the publication is composed of a base 12 and a permanent magnet 13 bonded and fixed to the upper surface of the base 12 as shown in FIG. . Further, this permanent magnet 13 has a large number of N poles and S poles alternately magnetized along the moving direction of the movable element 14.

Also, although it is not a field magnet, there are plastic magnets that are magnetized alternately with N and S poles at fine pitches. A floppy disk drive device described in Japanese Unexamined Patent Application Publication No. 60-226083 is known as a device in which magnetic encoder magnetic poles are formed by magnetizing the floppy disk (or S pole).

[Problem that the invention seeks to solve]

However, in the conventional field magnets for actuators and motors, a single magnetic member is magnetized to obtain a large number of micropitch magnetic poles.
The problem is that a large magnetomotive force cannot be obtained.

Therefore, when used as a permanent magnet machine such as an actuator, its thrust is small and cannot handle a large load, which is a factor that limits the applications of this type of motor and actuator.

Focusing on the above points, the present invention eliminates the demagnetizing effect due to magnetization, has a large magnetomotive force, can make the pitch as small as possible, improves the moving pitch accuracy,
The object of the present invention is to provide a permanent magnet machine that can realize a linear actuator with high torque and low vibration by increasing the magnetomotive force and reducing the variation in the magnetomotive force.

[Means for solving problems]

The present invention has been made with attention to the above, and includes a field magnet in which a large number of magnetic poles N and S are arranged alternately in the longitudinal direction, and a field magnet for imparting an electromagnetic propulsive force to the field magnet. In a permanent magnet machine comprising an A-phase magnetic pole and a B-phase magnetic pole arranged close to each other, the field magnet is formed with holding holes or holding grooves penetrating in the thickness direction at a predetermined pitch, and is magnetized in the thickness direction. and a permanent magnet that is magnetized in a direction different from the magnetization direction of the magnet base and has the same thickness as the magnet base, and the latter permanent magnet is inserted into the holding hole or groove of the former magnet base. It is constructed by inserting and combining.

[Effect]

As mentioned above, since the pre-magnetized magnet substrate and the permanent magnet are combined, there is no demagnetization effect due to magnetization, and the magnetization of the field magnet is increased.

〔Example〕

The configuration of an embodiment of the present invention will be described below.

As described above, the present invention is applied to permanent magnet machines such as linear actuators and linear step motors, so first, the basic structure of the linear actuator will be explained. In Fig. 3, 1 is a permanent magnet;
2 is the A-phase magnetic pole wrapped around the coil 4, 3 is the coil 5
This is a B-phase magnetic pole wrapped with . Reference numeral 6 denotes a movable element, which supports the permanent magnet 1, which is minutely magnetized alternately with N poles and S poles at the same pitch as the stator magnetic pole teeth. The stator A-phase magnetic pole 2 has magnetic pole parts 21 and 22, and the phase relationship between the two magnetic pole parts is such that when the tooth protrusion of the magnetic pole part 21 coincides with the N pole of the permanent magnet 1, the tooth of the magnetic pole part 22 The protrusion is configured to coincide with the S pole of the permanent magnet 1. Therefore, the magnetic flux Φ _A interlinks with the coil 4 as shown in the figure. Further, the stator B total magnetic pole 3 also has magnetic poles 31 and 32, and these two magnetic pole portions also have a similar phase relationship. Furthermore, the phase relationship between the stator A-phase magnetic pole 2 and the stator B-phase magnetic pole 3 is as shown in the figure.
, the center of the tooth protrusion of the stator B-phase magnetic pole 3 coincides with the switching point of the minute magnetic pole of the permanent magnet 1.

Therefore, when the permanent magnet 1 is located at the position shown in FIG. 3, the magnetic flux Φ _A interlinks with the coil 4, but no magnetic flux interlinks with the coil 5. In addition, if the movable element 6 moves and the magnetism of the minute magnetic poles of the permanent magnet 1 facing the protrusions of the teeth of the magnetic pole parts 21 and 22 of the magnetic pole part 2 of the stator A-phase magnetic pole 2 is reversed, the coil The direction is opposite to the magnetic flux Φ _A that interlinks with 5.

Further, if the positional relationship between the stator A-phase magnetic poles and the permanent magnets 1 is similar to the positional relationship between the stator B-phase magnetic poles 3 and the permanent magnets 1 in FIG. 3, the magnetic flux does not interlink with the coil 4. In this way, the direction and magnitude of the magnetic flux linkage of the coil 4 change depending on the position of the movable element 6. Similarly, in the coil 5, the interlinkage flux changes depending on the position of the movable element 6, and the phase thereof is 90 degrees in electrical angle.

What has been explained here is a two-phase example, but three-phase
The same is true for the number of phases greater than the number of phases; in that case, only the phase difference between each phase differs depending on the number of phases.

Further, although a permanent magnet is used as a mover, there is no essential difference if a permanent magnet is used as a stator.

The thrust of this actuator is proportional to the amount of change in the interlinkage magnetic flux of the coil with respect to the above-mentioned change in the position of the mover. In order to achieve high thrust with this linear step actuator, the pitch of the steps, i.e.
It is necessary to miniaturize the pitch of the teeth of the inductor and the pitch of the magnetic poles of the permanent magnet, and to increase the rate of change in magnetic flux linkage with respect to the positional displacement of the movable element of the coil of the inductor pole.

Therefore, miniaturization of the magnetization pitch of the permanent magnet is an essential technology for increasing the thrust of the linear step actuator.

As shown in FIG. 2, the conventional permanent magnet provided in the mover was simply magnetized with N and S poles alternately. If the magnetization pitch is made minute with the structure as it is, the following problems will occur.

FIG. 4 shows the basic structure of a magnetizing device for forming the magnet shown in FIG. 2. The area of the tip end 9 of the core facing the magnetic medium (permanent magnet) 7 of this magnetizing device is made minute to match the desired magnetization width, and magnetization is performed.
Since the magnetic flux passes through the permanent magnet while diverging in the direction of the arrow in FIG. 4, the magnetic force of the permanent magnet 7 becomes weaker as it becomes deeper. In addition, in order to polarize multiple poles at minute pitches, the core of the magnetizing device is shifted by the pitch to reverse the magnetic flux and perform magnetization. The situation is shown in FIG. As is clear from the figure, when adjacent magnetic poles are magnetized, magnetic flux in the opposite direction passes through the already magnetized portion, and the magnetic force is significantly weakened.

Therefore, with the method of magnetizing permanent magnets in minute pitches on an integrated magnetic medium, a decrease in magnetic force is unavoidable.
Sufficient magnetomotive force cannot be obtained.

Therefore, a method has been considered in which a permanent magnet is divided into minute rectangular bodies for each magnetic pole pitch, which are magnetized and then bonded together to form a single minute magnetized permanent magnet as shown in FIG. With this method, a magnetomotive force can be obtained, but the manufacturing precision and adhesion precision of the minute permanent magnet rectangular bodies are low, and when a large number of them are combined, variations occur in the magnetization pitch of the permanent magnets and the height of the permanent magnets. For this reason, when used in an actuator, speed variations and torque pulsations become large, making it impossible to obtain sufficient performance.

That is, with the above method, it is not possible to arrange high magnetomotive force magnets (magnetic poles) in minute pitches with high precision.

The present invention aims to obtain a field magnet that can obtain sufficient magnetomotive force even in minute pitches and has high dimensional accuracy. FIG. 1 is a perspective view of a field magnet showing an example of the present invention, and FIG. 6 is a developed view showing the manufacturing procedure.

In FIG. 6, reference numeral 11 denotes a magnet base having a length and width necessary for a field magnet of a linear actuator. The entire surface of the magnet base 11 is magnetized to the south pole, and the entire bottom surface is magnetized to the north pole. That is,
This magnet base 11 is magnetized in the thickness direction. Reference numeral 12 denotes a grid with a movement dimension T, and between the grids 12 there is also a movement direction dimension T and a width direction dimension l.
A holding hole 13 is formed. Reference numeral 14 denotes a magnetized permanent magnet which is inserted into the holding hole 13 and has a dimension in the moving direction of T and a dimension in the width direction of l, and is easily fitted into the holding hole 13. This permanent magnet 14
The magnets are magnetized with N and S poles on the top and bottom so as to have opposite polarities to the magnet base 11, and are inserted and held one by one in each holding hole 13. FIG. 1 shows a state in which all the permanent magnets 14 are fitted into the magnet base 11, and a field magnet in which the magnetic poles N and S of the pitch T are alternately arranged is obtained. The dimensional accuracy of this field magnet is determined by the manufacturing accuracy of the magnet base 11, and since the magnet base 11 can be manufactured from a plastic magnet, a highly accurate one can be obtained.
The permanent magnet 14 is also made of plastic magnet.

Further, even if the permanent magnet 14 is placed slightly offset in the holding hole 13, the error remains within the holding hole 13, so the error does not accumulate and extremely high pitch accuracy can be obtained.

In addition, since the magnets with opposite magnetic poles are arranged vertically, the attraction force between the surfaces of the permanent magnet 14 and the magnet base 11 does not act at the initial stage of insertion, allowing smooth insertion, and after more than half of the insertion, the attraction force acts. This makes the insertion process easier. Further, after the insertion is completed, since a suction force is applied between the two, there is no risk that the two will separate. Integration can be achieved with just this suction force, but for reliable integration, it is desirable to use adhesive to fix the components together.

The pitch T mentioned above is about 1 mm to several mm, and each magnet is very small as a single unit, but since each magnet is magnetized first, the magnetomotive force maintains the magnetized state. This allows a large magnetic force to be obtained. According to experiments, compared to the alternate magnetization method in which one magnetic medium 7 is alternately magnetized with N and S magnetizers as shown in FIG.
It was confirmed that the magnetomotive force was ~3 times higher. Furthermore, if the formation accuracy of the magnet base 11 and the permanent magnet 14 and the accuracy of the assembly machine are improved, the pitch T can be further reduced, and the resolution can be improved without reducing the magnetomotive force.

Next, based on FIG. 9, a schematic configuration of an assembly machine for fitting the permanent magnet 14 into the magnet base 11 will be described. 21 indicates the floor or the entire base;
A slide bed 22 movable in the direction of the arrow is supported on the top surface of the bed. This slide bed 22
is driven by a drive device (not shown) to move the index by pitches 2T in the direction of the arrow. Reference numeral 11 designates the aforementioned magnet base fixed on the slide bed 22 with a pair of clamps 23. 24 is fixed to the base 21, and the magnet base 11
It is a holder installed vertically above. 25 is a guide hole formed perpendicularly to the holder 24, and the permanent magnet 1
4 is inserted and held, and its lower end opening is aligned with the holding hole 13 of the magnet base 11. A cylinder 26 is provided at the upper end of the holder 24, and the tip of the rod 27 applies a predetermined downward force to the permanent magnet 14 inserted into the guide hole 25 of the holder 24. If the holder 24 is made of iron, the permanent magnet 14 will be attracted to the holder 24, but this force may be greater than this attractive force. If the holder 24 is made of a non-magnetic material such as aluminum or synthetic resin, this adsorption force will not be generated, so the force applied to the cylinder 26 may be small.

Then, the magnet base 11 is supported on the slide bed 22, and the permanent magnet 14 located at the lowest position in the guide hole 25 is inserted into the first holding hole 13 into the cylinder 26.
Push it in. Next, when the slide bed 22 is advanced by 2T in the direction of the arrow, the next holding hole 13 is located at the lower end opening of the guide hole 25. If the cylinder 26 is actuated at this time, the next permanent magnet 14 is pushed into this holding hole 13 and is inserted and held. In this way, the permanent magnets can be inserted and held in the holding holes one after another in the same way as a Daruma drop.

In addition, in this insertion process, as mentioned above, when the magnetic poles are initially inserted, their magnetism is the same and they repel each other, so they do not stick to each other, and can be inserted smoothly up to the middle. is inserted more than half of the way, so it won't shift.
If force is applied to this with the cylinder 26, the insertion operation can be performed reliably.

In the above embodiment, each permanent magnet 24 is inserted and held in the holding hole 13 of the magnet base 11, but the holding hole provided in the magnet base 11 is not a complete hole but may be a groove, so to speak. Any holding part that has the function of holding a permanent magnet may be used. Note that the shape and depth of this holding portion can be changed arbitrarily.

In FIG. 8, the entire magnet base 11A has a comb-teeth shape with holding holes and holding grooves 13A, and the magnetic pole directionality, combination direction, etc. are the same as those described above. In this case, compared to FIG. 6, one root side of the comb-like shape is not required, which has the effect of reducing the size. Naturally, both can be combined with the insertion device shown in FIG.

In the method described above, each permanent magnet 14 is an independent unit, and this is inserted and held in each holding hole 13 or holding groove 13A, so the permanent magnets are separate and the insertion work takes time. There is a problem that it takes

A mechanism for solving this problem is shown in FIG. In FIG. 7, the magnet base 11B and the permanent magnet 14B each have a comb-like shape with a pitch T, and the comb-teeth of each are inserted into the holding grooves 13B of the other, and the two are combined and connected. The insertion and combination method at this time may be performed from the side or from above, but
In that the repulsive force is applied first and then the attractive force is applied, it is preferable to perform the latter from above.

This figure 7 has the advantage that the combination can be completed in one combination operation. The polarity shown in FIG. 7 is the same as described above. Moreover, the magnetomotive force is exactly the same as that shown in FIG.

In addition, when the required dimensions for the field magnet are long,
It is sufficient to prepare several unit comb teeth, arrange them in a line of required values, and fix them to a substrate (not shown).

Although the field magnet is used as a component of the mover, it goes without saying that it can also be used as a field magnet device for the stator.

〔Effect of the invention〕

As described above, according to the present invention, a field magnet in which a large number of magnetic poles N and S are arranged alternately in the longitudinal direction;
In a permanent magnet machine comprising an A-phase magnetic pole and a B-phase magnetic pole disposed close to the field magnet in order to impart an electromagnetic propulsive force to the field magnet, the field magnet is arranged at a predetermined pitch in the thickness direction. A magnet base having a penetrating holding hole or holding groove formed therein and magnetized in the thickness direction, and a permanent magnet magnetized in a direction different from the magnetization direction of the magnet base and having the same thickness as the magnet base. Since the permanent magnet of the latter is inserted and combined into the holding hole or holding groove of the former magnet base, there is no demagnetizing effect due to magnetization, and the magnetomotive force can be made as small as possible at large pitches. It has been possible to provide a permanent magnet machine that can realize a linear actuator with high torque and low vibration because it has improved movement pitch accuracy, large magnetomotive force, and small variation in magnetomotive force.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a field magnet used in the present invention, Figure 2 is a perspective view of a conventional field magnet, and Figure 3 is the principle of a linear actuator that is an example of the permanent magnet machine of the present invention. Figures 4 and 5 are diagrams showing a conventional method of magnetizing a field magnet, Figure 6 is an exploded view showing the assembly procedure of the field magnet shown in Figure 1, and Figures 7 and 8 are diagrams showing a conventional method of magnetizing a field magnet. 9 is a perspective view showing another embodiment of the present invention, and FIG. 9 is a sectional view showing an assembly machine for constructing the field magnet shown in FIGS. 1 and 8. 11... Magnet base, 12... Grid, 13... Holding hole, 14... Permanent magnet.

Claims (1)

[Scope of Claims] 1. A field magnet in which a large number of magnetic poles N and S are arranged alternately in the longitudinal direction, and an A-phase magnetic pole arranged close to this field magnet in order to impart an electromagnetic propulsive force to this field magnet. and a B-phase magnetic pole, wherein the field magnet has a magnet base body formed with holding holes or holding grooves penetrating in the thickness direction at a predetermined pitch and magnetized in the thickness direction; A permanent magnet that is magnetized in a direction different from the magnetization direction of the base body and has the same thickness as the magnet base body, and is constructed by inserting and combining the latter permanent magnet into a holding hole or a holding groove of the former magnet base body. A permanent magnet machine featuring: 2. The permanent magnet machine according to claim 1, wherein the permanent magnets are independent and separated from each other. 3. The permanent magnet machine according to claim 1, wherein the permanent magnet has a comb-like shape in which the ends thereof are integrally connected with the same material as the permanent magnet. 4. The permanent magnet machine according to claim 1, wherein the magnet base and the permanent magnet are both made of plastic magnets.