JP2002112519A - Electromagnetially reciprocating driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct defects of an electromagnetially reciprocating driver in use heretofore, i.e., the need for winding a large amount of thick wire for forming coils, large driver size, and its heavy weight as well, which are pro duced since the power factor is poor and in the extent of 0.3-0.4, though generat ed thrust within its stroke is comparatively flat. SOLUTION: This kind of electromagnetic reciprocating driver, formed by arranging two electromagnetic coils, so that the same poles are generated in opposition to each other, in a yoke whose vertical cross-sectional shape in a plane comprising a shaft is approximately E-shaped, and fitting a movable element which has permanent magnets magnetized in the axial direction and magnetic pole shoes for the movable element adjacent to the permanent magnets, in such a way as to freely reciprocate in the axial direction. The driver has a first peak position of thrust generated by one electromagnetic coil in the front half part near the center of an actuation stroke, and has a second peak position of thrust generated by the other electromagnetic coil in the latter half part near the center of the actuation stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic reciprocating drive using a permanent magnet as a movable element and used for a compression device such as a pump and a compressor, a vibration device, a valve control device and the like.

[0002]

2. Description of the Related Art In the following description, an application to a compression device such as a pump or a compressor will be described as an example. 2. Description of the Related Art Conventionally, an electromagnetic reciprocating drive device used for a compression device such as a pump or a compressor using an electromagnetic reciprocating drive method is roughly classified into a movable coil type, a movable magnet type, and a movable core type. Among them, the moving coil type is most suitable for precise control, but there are problems such as a tendency that the device becomes large and expensive when the capacity is large, and a lack of reliability in a power supply configuration to the moving part. In addition, the movable iron core type has a problem that power consumption is large. On the other hand, various types of movable magnet type using a permanent magnet as a movable element have been proposed as an electromagnetic reciprocating drive device that solves the above-mentioned problem. 6 and 7 show typical conventional examples.

In the device shown in FIG. 6, two electromagnets formed by winding a coil 32 around an E-shaped laminated yoke 31 are opposed to each other with a gap provided therebetween, and two electromagnets are magnetized in opposite directions in parallel in the gap. A movable element 34 composed of a permanent magnet 33 is disposed. Usually, a diaphragm is attached to both sides of the mover 34 and elastically supported so as to be able to reciprocate freely, and is configured as a diaphragm pump. (The diaphragm is not shown.)

On the other hand, the apparatus shown in FIG. 7 is a diaphragm pump using a movable magnet type electromagnetic reciprocating drive device proposed by the present inventors in Japanese Patent Application Laid-Open No. 54-84603. FIG. 7 is a longitudinal sectional view showing the configuration. In FIG.
5, the two coils 6 are formed in the yokes 4 and 5 so that the same polarity is generated in adjacent portions.
Is arranged. Next, the mover 7 is interposed in the yokes 4 and 5 slidably in the axial direction. The mover 7 is formed by mounting magnetic pole pieces 9 on both ends of a permanent magnet 8 magnetized in the axial direction, and is fixed to a shaft 10. Diaphragms 13 are connected to both ends of the shaft 10 and are elastically supported.

[0005]

Although the devices shown in FIGS. 6 and 7 have different constructions, the principle of generation of thrust (force generated in the axial direction) is the same. That is, a thrust is generated by the interaction between the magnetic force of the permanent magnet of the mover and the magnetic force generated by energizing the electromagnetic coil of the stator due to the attraction and repulsion. Therefore, it is possible to reciprocally move the mover by changing the energizing direction. As a compression device,
It is ideal to obtain an electromagnetic reciprocating drive that can obtain the required thrust with the minimum material and the minimum power and is easy to assemble. However, in the apparatus shown in FIG. 6, the generated thrust within the stroke is relatively flat, but the power factor is 0.3 to 0.5.
As a result, it is necessary to wind a large amount of thick wire around the coil, which results in a disadvantage that the device becomes large and heavy. Also, since two permanent magnets must be magnetized in opposite directions, magnetization after assembly is almost impossible, and the magnetized mover must be assembled while balancing the magnetic attraction. There is a disadvantage that.

On the other hand, the device shown in FIG.
It is good at about 0.9, which is suitable for miniaturization and weight reduction, but has a drawback that the generated thrust is concentrated only in the first half of the stroke and the thrust in the second half is small, resulting in a small thrust. However, since a permanent magnet which only needs to be magnetized in a single axial direction is used, there is an advantage that magnetization after assembly is easy and assembly is easy. An object of the present invention is to provide a small and lightweight electromagnetic reciprocating drive device having a good power factor, a large generated thrust, and a small size. In particular, it is an object of the present invention to provide an electromagnetic reciprocating drive having a configuration shown in FIG.

[0007]

The present inventors reviewed the relationship between the thrust and the stroke required for the compression device, and improved the thrust generated by the electromagnetic reciprocating drive having the structure shown in FIG. An electromagnetic reciprocating drive of the present invention has been found. In other words, in the operation process of the compression device, the thrust generated by the electromagnetic reciprocating drive device, the elastic force of the diaphragm or the resonance spring, and the reaction force generated by compression interact with each other. It has been found that the required thrust does not necessarily have to be flat within the stroke, but rather it is effective to concentrate the thrust near the center of the stroke and maximize the total sum of thrust available within the stroke.

Based on this finding, the relationship between the substantially E-shaped yoke pole piece and the mover pole piece of the electromagnetic reciprocating drive having the structure shown in FIG. 7 is reviewed, and the peak position of the generated thrust within the stroke is set optimally. At the same time, the minimum dimension of the permanent magnet length of the mover which can cancel the effect of the detent force (the force of the mover moving to a magnetically stable position in a state where the electromagnetic coil is not energized) is also set. Thrust-stroke characteristics can be designed.

Here, the mutual positional relationship between the substantially E-shaped yoke magnetic pole piece and the mover magnetic pole piece which affects the magnitude of the generated thrust of the electromagnetic reciprocating drive device of the present invention will be described. First, it is natural that the generated thrust is proportional to the amount of magnetic flux of the permanent magnet and the amount of current input to the electromagnetic coil, but the thrust at each position of the operation stroke is equal to the above-described substantially E-shaped yoke magnetic pole piece and the mover. It is also greatly affected by the relative positional relationship with the pole piece. That is, the point where the maximum thrust is obtained at the operation stroke position is where the change of the permeance of the magnetic circuit becomes the maximum position. This position is a position where the corners of the mover pole piece and the substantially E-shaped yoke pole piece face each other with different poles, and it is possible to provide two peak positions within the operation stroke.

[0010] The electromagnetic reciprocating drive device of the present invention is characterized in that
Optimum combination of the peak positions of the generated thrusts at the three places, that is, the first and second peak thrust generation positions, to concentrate the thrust near the center of the stroke described above, and to maximize the sum of the thrusts available within the stroke It is characterized by. That is, the first invention of the present application is to dispose two electromagnetic coils in a yoke having a substantially E-shaped vertical cross section in a plane including a shaft so that the same poles are generated opposite to each other, and In an electromagnetic reciprocating drive device formed by providing a movable element having a permanent magnet magnetized on a magnet and a movable element magnetic pole piece adjacent to the permanent magnet in an axially reciprocable manner, the end of the yoke faces the movable element as an E-shaped magnetic pole piece. Then, the first peak position of the thrust generated by one of the electromagnetic coils is set in the first half near the center of the operation stroke,
An electromagnetic reciprocating drive device characterized in that a second peak position of thrust generated by the other electromagnetic coil is provided in the latter half of the operation stroke near the center.

According to a second aspect of the present invention, two electromagnetic coils are arranged in a yoke having a substantially E-shaped vertical cross section in a plane including a shaft so that the same magnetic poles are generated opposite to each other. In an electromagnetic reciprocating drive device formed by providing a movable element having a permanent magnet magnetized on a magnet and a movable element magnetic pole piece adjacent to the permanent magnet in an axially reciprocable manner, the end of the yoke faces the movable element as an E-shaped magnetic pole piece. The electromagnetic reciprocating drive device is characterized in that the poles of the mover pole piece and the E-shaped pole piece face each other with different poles at two places in the operation stroke.

In the above invention, when the operation stroke is L, the first peak position is set to 0.25 L to 0.5.
L, it is desirable to have the second peak position in the range of 0.5L to 0.75L. Further, the operation stroke is L
In this case, it is desirable that the axial length of the permanent magnet be 0.75 L or more.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of the electromagnetic reciprocating drive device of the present invention. In the figure, two coils 6 and 6 are arranged in a yoke 4 having a vertical cross-sectional shape of substantially E so that the same polarity is generated in adjacent portions. A mover 7 is interposed in the yoke 4 so as to be able to reciprocate in the axial direction. The mover 7 has pole pieces 9 at both ends of a permanent magnet 8 magnetized in the axial direction.
And fixed to the shaft 10. Although not shown, when used in a diaphragm pump as shown in FIG. 7, the mover 7 has a diaphragm coupled to both ends of the shaft 10 and is elastically supported.

FIG. 1 shows a state in which the mover 7 is located at the center position of the stroke. For convenience of explanation, the stroke of the electromagnetic reciprocating drive of this embodiment is 8 mm. In this state, the correlation between the E-shaped pole piece and the mover pole piece has a 1 mm overlap and a 5 mm separation as shown. In this state, the configuration is symmetric with respect to the stroke center line.

FIG. 2 is a diagram for explaining the relationship between the E-shaped pole piece and the mover pole piece at each stroke position with respect to the embodiment shown in FIG. (1) The left end position of the stroke
The mover is at the beginning of the stroke, that is, stroke 0
mm. Here, when the coil is energized so that the E-shaped magnetic pole piece has the illustrated magnetic polarity (N, S, N in order from the left), a thrust that moves rightward in the drawing is generated in the mover. Next, (2) the first peak thrust position is where the E-shaped magnetic pole piece and the mover magnetic pole piece coincide with each other in the illustrated portion a.
That is, the position is at a stroke of 3 mm. Next, (3)
The second peak thrust position is where the illustrated b-portion of the E-shaped magnetic pole piece and the mover magnetic pole piece coincide, that is, the end position of the S-pole magnetic pole piece at the center of the E-shaped magnetic pole piece and the N-pole movable magnetic pole piece. (The position of the stroke 5.5 mm). Finally, (4) the right end position of the stroke is the end of the stroke, that is, the position of the stroke of 8 mm. Since this configuration is symmetrical with respect to the stroke center line, if a magnetic pole opposite to that in FIG. 2 is generated in the E-shaped magnetic pole piece, the position of (4) in FIG. And the stroke has the same positional relationship as described above.

FIG. 3 is a graph showing the thrust-stroke characteristics of the embodiment shown in FIGS. The thrust referred to here is obtained by inputting a direct current and measuring the generated thrust at each position of the stroke. As shown in the graph of FIG.
The dotted line having the peak thrust at the stroke 3 mm position is shown in FIG.
2 is a thrust-stroke characteristic when only the right coil is energized, and a dotted line having a peak thrust at a 5.5 mm stroke position is a thrust-stroke characteristic when only the left coil in FIG. 2 is energized. The graph shown by the solid line is the thrust-stroke characteristic when both coils are energized simultaneously. Here, the solid line graph is a graph obtained by adding two dotted line graphs. This suggests that by setting the first and second peak thrust positions optimally, it is possible to set almost arbitrary thrust-stroke characteristics.

Here, FIGS. 8 and 9 will be described for comparison. FIG. 8 is a diagram showing a relationship between an E-shaped magnetic pole piece and a mover magnetic pole piece of the conventional electromagnetic reciprocating drive device shown in FIG.
As shown (with the mover in the middle of the stroke), it has a 2 mm overlap and a 5 mm separation.
FIG. 9 is a graph of the thrust-stroke characteristic of the electromagnetic reciprocating drive device shown in FIG. 8, similar to that shown in FIG. Here, the first peak thrust is located at the position of the stroke 2 mm, but the second peak thrust is outside the stroke (not shown, but the second peak thrust is actually at the position of the stroke 9 mm). This conventional electromagnetic reciprocating drive does not make good use of the second peak thrust, and as a result, the thrust available within the stroke is insufficient.

When comparing the thrust-stroke characteristics of the electromagnetic reciprocating drive of the embodiment of the present invention shown in FIG. 3 with the thrust-stroke characteristics of the conventional electromagnetic reciprocating drive shown in FIG.
It can be seen that the embodiment of the present invention shown in FIG. 3 has a large thrust distribution in which the vicinity of the center of the stroke is larger than the end of the stroke and has a trapezoidal shape as a whole.

FIG. 4 is a longitudinal sectional view showing another embodiment of the electromagnetic reciprocating drive device of the present invention. The mover is the same as the embodiment shown in FIG. 1, but the configuration of the E-shaped pole piece is different. FIG. 5 is a view for explaining the relationship between the E-shaped magnetic pole piece and the mover magnetic pole piece at each stroke position in the embodiment shown in FIG. The electromagnetic reciprocating drive shown in FIG. 4 and FIG.
The thrust-stroke characteristics almost the same as those of the electromagnetic reciprocating drive device shown in FIG.

[0020]

[Table 1]

Table 1 shows a comparison of the performance between the conventional example shown in FIGS. 6 and 7 and the example of the present invention shown in FIG. 1 of an electromagnetic reciprocating drive device applied to a diaphragm type air pump.
Incidentally, the performance evaluation of this type of electromagnetic reciprocating drive device is not limited to the above-described evaluation of the thrust-stroke characteristic with DC current input, but it is only a measure of the performance. In general, it is incorporated in any applicable device and evaluated by the performance of the device. Therefore, evaluation was made here in the case of application to an air pump.
As shown in Table 1, when the present invention example is compared with the conventional example of FIG. 6, the present invention example is about 60% of the weight and size of the conventional example of FIG.
And the power consumption is about 20 times that of the prior art in FIG.
It is an excellent performance of less by%.

In the embodiment shown in FIG.
m, the first peak thrust position is 3 mm stroke
(Ie, a position of 0.375 × 8 mm), the second peak thrust position is 5.5 mm stroke (ie, 0.6 mm).
87 × 8 mm). This satisfies the condition described in claim 1 that the first peak position is located in the first half of the operation stroke near the center, and the second peak position is located in the second half of the operation stroke.

Further, when the stroke is L as described in claim 3, the first peak position is 0.25L to 0.5.
L, the condition that the second peak position is in the range of 0.5 L to 0.75 L is also satisfied. Here, the configuration of the electromagnetic reciprocating drive device described in claim 3 is the gist of the present invention.
This is the optimum configuration condition that can concentrate the thrust near the center of the stroke and maximize the sum of the thrusts available in the stroke.

In the embodiment shown in FIG. 1, the axial length of the permanent magnet is 8 mm. This is the same length as the stroke of 8 mm. Although it is desired to keep expensive permanent magnet material as small as possible, in reality, a permanent magnet length at least approximately equal to the stroke length is required. This is due to the influence of the detent force described above. However, when the permanent magnet length was 6 mm (that is, 0.75 × 8) in the embodiment of FIG. 1, the power consumption was slightly worse at 67 (w) in the air pump performance shown in Table 1. The performance was confirmed to be sufficient.
The condition that the length of the permanent magnet is 0.75 L or more in claim 4 is a proposal for manufacturing the electromagnetic reciprocating drive device of the present invention at lower cost.

In this embodiment, an example of application to a compression device, particularly a diaphragm type air pump has been described, but it is natural that the same effect can be obtained in applications to other compression devices and vibration devices. . In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the claims.

[0026]

As is clear from the above description, the electromagnetic reciprocating drive of the present invention concentrates the thrust near the center of the stroke and maximizes the total sum of the thrust that can be used within the stroke. This has the effect of reducing the size, weight, and power consumption of an application device such as a compression device that uses the same, and facilitating assembly.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of an electromagnetic reciprocating drive device of the present invention.

FIG. 2 is a diagram illustrating a relationship between an E-shaped magnetic pole piece and a mover magnetic pole piece at each stroke position in the electromagnetic reciprocating drive device of FIG. 1;

FIG. 3 is a thrust-stroke characteristic diagram of the electromagnetic reciprocating drive device of FIGS.

FIG. 4 is a longitudinal sectional view showing another embodiment of the electromagnetic reciprocating drive device of the present invention.

FIG. 5 is a view for explaining the relationship between the E-shaped magnetic pole piece and the mover magnetic pole piece at each stroke position in the electromagnetic reciprocating drive device of FIG. 4;

FIG. 6A is a plan sectional view of a conventional electromagnetic reciprocating drive device. (B) is the same side view.

FIG. 7 is a longitudinal sectional view of a diaphragm type air pump using a conventional electromagnetic reciprocating drive device.

8 is a diagram showing a dimensional relationship between an E-shaped magnetic pole piece and a mover magnetic pole piece of the electromagnetic reciprocating drive device of FIG. 7;

9 is a thrust-stroke characteristic diagram of the electromagnetic reciprocating drive device of FIG.

[Explanation of symbols]

4 E type yoke, 6 coil, 7 mover, 8
Permanent magnet 9 Mover pole piece, 10 axes

Claims (4)

[Claims] 1. A longitudinal sectional shape in a plane including an axis is substantially E
A mover having a permanent magnet magnetized in the axial direction and a mover pole piece adjacent to the permanent magnet is disposed in a yoke formed in such a manner that two electromagnetic coils are arranged so that the same poles are opposed to each other. In an electromagnetic reciprocating drive device formed so as to be reciprocally movable in the axial direction, the end of the yoke faces the mover as an E-shaped magnetic pole piece, and the first peak position of the thrust generated by one of the electromagnetic coils is set at the center of the operation stroke. An electromagnetic reciprocating drive device having a second peak position of the thrust generated by the other electromagnetic coil in a front half of the operation stroke in a rear half of the operation stroke. 2. A longitudinal sectional shape in a plane including an axis is substantially E
A mover having a permanent magnet magnetized in the axial direction and a mover pole piece adjacent to the permanent magnet is disposed in a yoke formed in such a manner that two electromagnetic coils are arranged so that the same poles are opposed to each other. In an electromagnetic reciprocating drive device formed so as to be reciprocally movable in the axial direction, the end of the yoke faces the mover as an E-shaped magnetic pole piece, and the corners of the mover magnetic pole piece and the E-shaped magnetic pole piece are formed at two places in the operation stroke. An electromagnetic reciprocating drive device characterized in that different poles face each other. 3. When the operation stroke is L, the first peak position is in a range of 0.25L to 0.5L, and the second peak position is in a range of 0.5L to 0.75L. An electromagnetic reciprocating drive as described. 4. The electromagnetic reciprocating drive according to claim 1, wherein when the operation stroke is L, the axial length of the permanent magnet is 0.75 L or more.