JP3426161B2 - Linear drive for driven body - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel linear drive device suitable for a flow control valve or the like. 2. Description of the Related Art There is known a so-called electromagnetic linear drive device which supplies a current to a coil to generate a magnetic force and applies the magnetic force to a driven body made of a magnetic material to drive a movable portion. It is used for various purposes, and a typical example is a solenoid (electromagnet). [0003] As shown in FIG.
A coil 54 includes an iron core (yoke) 51, a driven body 52, and a return spring (return spring) 53.
When a DC current is applied to the iron core 51, a magnetic force is generated in the iron core 51, and the driven body made of a magnetic material is driven by the magnetic attractive force. When the DC current of the coil 54 is turned off, the magnetic force of the iron core 51 is lost, and the driven body 52 returns to the original position by the restoring force of the return spring 53. [0005] A driven body of a normal solenoid is made to be stationary at one of two stable positions when current is flowing through the coil and when no current is flowing, and the position of the driven body is continuously changed. Although it cannot be controlled, by balancing the magnetic force generated by the iron core and the restoring force of the return spring,
It is also possible to continuously control the position of the driven body within a limited range. FIG. 7 shows an application example of a solenoid capable of continuously controlling the position. A flow control valve for controlling a flow rate of a passing fluid by changing a gap of a flow path of a valve 55 by increasing or decreasing a current value of a coil. It is. In FIG. 1, when no current is supplied to the coil 54, the valve body 57 of the valve rod 56, which is the driven body, closes the flow path by the force of the disc spring (diaphragm) 58, and the flow rate is zero. However, when an electric current is applied to the coil 54, an upward force acts on the valve body 57 by the attraction force of the solenoid composed of the coil and the iron core 51, the valve body is displaced upward, and the space between the valve seat 59 and the valve body opens. , Fluid flows. The flow rate at this time increases as the displacement of the valve element increases. On the other hand, when the valve element is displaced upward, a downward restoring force is exerted on the valve element by the disc spring 58, and this restoring force increases substantially in proportion to the amount of displacement of the valve element. Therefore, the valve body 57 stops at a position where the suction force of the solenoid and the restoring force of the disc spring balance, and the displacement of the valve body increases as the coil current increases, and the flow rate of the fluid flowing between the valve seat and the valve body also increases. Increases with coil current. Therefore, the flow rate can be controlled by adjusting the coil current. [0009] However, the suction force of the solenoid increases as shown in FIG.
As shown in the figure, the restoring force of the disc spring is proportional to the first power of the displacement, while the restoring force of the disc spring is proportional to the square of the distance from the magnetic body (driven body) to be attracted. Is limited to a narrow range, and it is difficult to realize a flow control valve having a large movable range (stroke) of the valve element. Generally, in a flow control valve having a small stroke, a large pressure loss occurs when a fluid flows between a valve seat and a valve body, and unless the pressure (supply pressure) of the fluid flowing into the flow control valve is sufficiently high. The required flow rate cannot be obtained. Normally, the pressure loss increases in proportion to the square of the flow rate, so that when the pressure loss reaches the supply pressure, it is physically impossible to obtain a higher flow rate. This is particularly problematic when the fluid is less compressible and the supply pressure is less likely to be higher than when the fluid is a gas. Most of the practical examples of the flow control valve using the above-mentioned solenoid are for gas, and there are very few cases in which they are used for liquid. As a typical example of a means for realizing a flow control valve having a large stroke, there is a motor type as shown in FIG. In the figure, the screw shaft 60 is rotated by the motor M to move the female screw body 61 up and down, and the lower end valve body 6 of the valve rod 62 provided integrally with the female screw body is shown.
3 is driven up and down, and is applied to a gate valve for moving a flat plate up and down, and a valve element as shown in FIG. 7 having a conical needle valve. In addition, various types of valves are put into practical use as flow control valves in combination with a motor, for example, a rotary driving device is used for a so-called ball valve that rotates a ball having a through hole. Although the motor type can provide a sufficient stroke, it takes a longer time to change the opening degree of the valve as compared with the above-mentioned solenoid type, so that when used for flow rate control, there is a problem that the response is slow. In general, the structure is complicated, the cost is high, and the service life is relatively short. In addition to these, an air-core coil and magnet type as shown in FIG. 10 is also used for a flow rate control valve for a small flow rate. In this method, a magnet 65 magnetized in the longitudinal direction is provided inside a coil 64 (air-core coil) having no iron core.
Is movably supported in the longitudinal direction, a current is applied to the coil to apply a driving force to the magnet, the valve stem 66 is moved up and down, and the opening of the valve hole 68 is adjusted by the valve body 67. (A) The magnet stroke can be increased by using a coil with a long overall length. (B) The response is fast, the structure is simple and the cost is low. (C) A driving force almost proportional to the current can be obtained. It has many advantages such as easy position control by combination with a spring. However, compared to a solenoid, the current required to obtain the same driving force is extremely large, and there is a demerit that the application is limited to a flow control valve for a small flow rate having a small driving force. Under the above circumstances, particularly for a liquid flow control valve, a large stroke can be obtained as compared with the solenoid type, and the response is faster, the structure is simpler and the cost is lower than that of the motor type. It is desired to realize a linear driving device having a larger driving force than the AND magnet type. An object of the present invention is to provide a large stroke and a large control range as compared with a solenoid type, and a quick response, a simple structure and a low cost as compared with a motor type. It is another object of the present invention to realize a linear drive device having a large driving force and a large control range. According to the present invention, there is provided a linear driving apparatus for a driven body according to the present invention, wherein opposite surfaces of opposite sides are formed inside both ends of a support having a first electromagnet and a second electromagnet at both ends. A first fixed magnet and a second fixed magnet, which are magnetized so that
First and second rods as driven bodies, which are freely inserted into the guide holes at the center of the second electromagnet and the center of the first and second immobile magnets.
A driven magnet, which is magnetized so that a surface facing the first and second immovable magnets has the same polarity as an opposing surface of each immovable magnet, is fixed to a portion between the second immovable magnets . Passing
And when no current is supplied to the second electromagnet,
The magnetic repulsion from the first and second fixed magnets acts on the stone
Thus, the driven magnet is held at the middle position of the movable range .
When a DC current of any polarity and strength is supplied to the second and / or second electromagnets , the first and second
The rod body is moved in the axial direction by a required amount in the forward and reverse directions by the magnetic force from the electromagnet . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a linear drive device according to the present invention will be described with reference to FIGS. As shown in FIG. 1, an air-core yoke (iron core) 3A having longitudinal guide holes 3a, 3b at the center of the upper and lower flanges 1a, 1b of a cylindrical support body 1 having flanges 1a, 1b at both upper and lower ends. A pair of upper and lower first and second electromagnets 4A and 4B having coils 2A and 2B are provided around 3B. Inside the upper and lower ends of the support 1, longitudinal guide holes 5a and 5b corresponding to the longitudinal guide holes 3a and 3b of the air-core yoke are provided at the center, respectively, in the axial direction passing through the longitudinal guide holes. A pair of upper and lower magnetized first and second immobile magnets 5A and 5B are fixed so that the opposite poles face each other. Thus, a rod 6 which is a driven body that can freely move up and down is inserted into the center of the yoke of the upper and lower electromagnets and the center of the upper and lower first and second immovable magnets. The driven magnet 5C is fixed at a location located between the second immobile magnets, and the driven magnet 5C is
The upper and lower first and second immovable magnets are magnetized so that they have the same polarity so as to repel each other, and are fixed to the valve stem. The driven magnet 5C is located between the upper and lower first and second immovable magnets. It is held at a position near the midpoint. By connecting the DC power supplies 7A and 7B capable of switching between normal and reverse directions to each of the coils of the first and second electromagnets of the driving device having the above-described configuration, an appropriate current is supplied to the coils. The following operation can be performed on the rod 6 as a driving body. First, when no current flows at all, the repulsive force from the first and second immobile magnets 5A and 5B acts on the driven magnet 5C, and as shown in FIG. Held in position. Next, the coil 2A of the first electromagnet 4A
When a current generating a magnetic force repelling the driven magnet 5C and a current generating a magnetic force attracting the driven magnet 5C to the coil 2B of the other second electromagnet 4B are simultaneously supplied, a downward force is applied to the driven magnet 5C. In operation, the driven magnet 5C moves below the movable range as shown in FIG. 2 by overcoming the repulsive force of the second immobile magnet 5B. At this time, the repulsive force of the second immobile magnet 5B increases as the driven magnet 5C moves downward.
The amount by which the driven magnet 5C moves downward can be adjusted by adjusting the magnitudes of the currents of the two coils 2A and 2B. Since the above operation is based on the repulsion and attractive force of the magnet, the response speed is as fast as the solenoid. The direction of the current is reversed, and a magnetic force attracting the driven magnet 5C is generated in the coil 2A of the first electromagnet 4A, and a magnetic force repelling the driven magnet 5C is generated in the coil 2B of the second electromagnet 4B. Then, an upward force acts on the driven magnet 5C, and overcomes the repulsive force of the first immobile magnet 5A, so that the driven magnet 5C moves above the movable range as shown in FIG. Also in this case, the amount by which the driven magnet 5C moves upward can be adjusted by adjusting the magnitude of the current. In order to generate the above-mentioned magnetic forces in the first and second electromagnets in opposite directions, it is sufficient to use two power supplies and supply currents to the electromagnets 4A and 4B independently. 4, coils 2A and 2B of electromagnets 4A and 4B
Can be connected in series so that the magnetic forces are opposite to each other, and the above operation can be performed by one power supply 7 having a changeover switch 8. However, in this case, the cost is reduced, but the currents flowing through the two coils are always equal in intensity, and currents having different intensities cannot be passed through each coil. There are many restrictions in performing effective control. The driven magnet 5C and the stationary magnets 5A, 5A, 5A
In order to prevent B from coming into close contact, a stationary magnet that generates a repulsive force greater than this attractive force is used. FIG. 5 shows an example of experimental data of a linear drive device employing the present invention. A driven magnet having a diameter of 40 mm and a thickness of 6 mm was used, and the maximum drive force was 2 kg or more (current 1.5
A), a performance of a stroke of 7 mm or more is obtained. As shown in the experimental data, if the electromagnets 4A and 4B are capable of generating a sufficiently large magnetic force, it is possible to apply a sufficient amount of movement and a large driving force to the driven body in the above operation. Thus, it is possible to realize a linear drive device suitable for a flow control valve or the like, which meets the object of the present invention. As described above, according to the present apparatus, the electromagnets 4A, 4B
By supplying a current of a required strength to one or both of them, the driven body 5C can be moved in the axial direction by a required amount in the forward and reverse directions by the driven magnet 5C. As described above, in the linear drive device of the present invention, the rod as the driven body has a large moving range (stroke).
Therefore, there is an advantage that a high-speed response can be obtained since a large driving force can be obtained and a driving force proportional to the current is generated almost instantaneously.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an example of a driven body linear driving device according to the present invention. FIG. 2 is a longitudinal sectional view showing an example of an operation state of the linear drive device. FIG. 3 is a longitudinal sectional view showing another example of the operating state of the linear drive device. FIG. 4 is a longitudinal sectional view showing another example of the linear drive device. FIG. 5 is a diagram illustrating a relationship between a current supplied to an electromagnet and a driving force and displacement of a driven magnet. FIG. 6 is a longitudinal sectional view showing an example of a conventional linear drive device. FIG. 7 is a vertical sectional view of a conventional flow control valve provided with the linear drive device. FIG. 8 is a diagram showing a relationship between a supply current of an electromagnet and a displacement and a force of a driven body, and a relationship between a displacement of a disc spring and a restoring force. FIG. 9 is a diagram showing a conventional linear drive device for a gate valve. FIG. 10 is a longitudinal sectional view of a conventional flow control valve. [Description of Signs] 1 ... Supports 1a, 1b ... Flanges 2A, 2B ... Coil 3A, 3B ... Air core yoke (iron core) 3a, 3b ... Vertical guide hole 4A ... 1 electromagnet 4B 2nd electromagnet 5A 1st stationary magnet 5B 2nd stationary magnet 5C driven magnet 6 rod 7A, 7B DC power supply 8 switching switch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-177510 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 7/16

Claims (1)

(57) Claims 1. A first magnet which is magnetized inside both ends of a support body having a first electromagnet and a second electromagnet at both ends so that surfaces facing each other have different polarities. immobility magnet and second stationary magnets provided, the first, central portion and the first second electromagnet, the first driven member serving rod inserted through the access into the guide hole of the central portion of the second stationary magnets, the A driven magnet which is magnetized such that a surface facing the first and second immovable magnets has the same polarity as the opposing surface of each immovable magnet is fixed to a portion corresponding to between the two immovable magnets, Previous
When no current is supplied to the first and second electromagnets
Is the magnetic repulsion from the first and second immobile magnets on the driven magnet
Acts to keep the driven magnet in the middle position of the movable range.
But a supply DC current of any polarity and intensity to the first and second electromagnets or one electromagnet, the the driven magnets
1. A linear driving device for a driven body in which a magnetic force from a second electromagnet acts to move the rod body forward and backward in a required amount in the axial direction.