JPS63156308A - Electromagnetic actuator - Google Patents

Abstract

PURPOSE:To obtain an electromagnetic actuator capable of working with small coil magnetomotive force by providing a coil exciting a self-maintaining magnetic circuit and a movable iron core becoming a parallel magnetic path to the attraction part of a movable plunger for magnetization of a permanent magnet and the coil. CONSTITUTION:When a current is conducted for a moment to a coil 25 in the direction generating magnetization in the same direction with the magnetization of a permanent magnet 16, a movable plunger 18 is is attracted stronger and maintained while a movable iron core 22 is also attracted and maintained up to the position abutting against the stepped parts 20 and 21 while overcoming the reaction force of a spring 27. When the excitation of the coil 25 is released in said condition, magnetic flux of the permanent magnet 16 is shunted to a circuit passing through the attraction part 19 of the movable plunger 18 and to a circuit passing through the movable iron core 22. Consequently, attracting and maintaining force reduces so as to work in a repelling condition by the force of a spring 26. In order to make the movable plunger 18 actuate in a repelling direction, it is sufficient enough to have coil excitation to the extent of reinforcing the magnetization of the permanent magnet so that a small coil current as compared with the case, where excitation is performed in the reverse direction as practiced in the conventional method can be sufficed well.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electromagnetic actuator that can be used to drive valve mechanisms used in gas equipment combustion rate switching and safety devices, and to drive various mechanisms. .

BACKGROUND OF THE INVENTION Conventionally, electromagnetic actuators that use batteries as a power source have often been self-holding type actuators that use permanent magnets in order to reduce battery consumption during operation. In this type of electromagnetic actuator, as shown in Fig. 5, a permanent magnet 2 is arranged at the center bottom of a U-shaped fixed yoke 1, and a fixed iron core 3 is arranged above the permanent magnet 2. A movable plunger 4 is provided which is attracted by contact and is movable in the axial direction. A coil 5 is wound around the outer periphery of the movable plunger 4 and inside the fixed yoke 1, and the upper open part of the fixed yoke 1 is separated from the movable plunger 4 by a yoke plate 6 having a hole with a small gap. Closed.

Further, the movable plunger 4 is provided with a spring 7 biased in a direction opposite to the suction force. The magnetic flux of the permanent magnet 2 passes through a magnetic path consisting of a fixed iron core 3, a movable plunger 4, a yoke plate 6, and a fixed yoke 1, and is held in a self-holding state by the attractive force that overcomes the reaction force of the spring 70. Then, when the coil tv5 is momentarily energized in the direction of reducing the magnetic flux, the attractive force is reduced, and the movable plunger 4 is separated from the fixed iron core 3 by the force of the spring 70, and operates, for example, to move the valve mechanism and close the gas passage. .

Next, another conventional example is shown in FIG. 6, in which a fixed iron core 9 is provided at the center bottom of the U-shaped fixed yoke 8, and a pair of yoke facing each other is provided on the open upper end side. A multilayer yoke plate 11 is arranged inside the permanent magnet 10. A movable plunger 12 that is movable in the vertical direction is provided at a position that contacts the upper end surface of the fixed iron core 9 and penetrates the yoke plate 11, and an annular plunger 12 is provided between the permanent magnet 10 and the bottom of the fixed yoke 8 Carp Iv13 is placed. (For example, Jitsukai 49-1
22424) The magnetic flux of the permanent magnet 10 is fixed yoke 8,
Electrifying the fixed iron core 9, movable plunger 12, and yoke plate 11,
The one point in which the carp/L/13 is separated by instantaneous energization after overcoming the reaction force of the spring 14 and becoming in a self-holding state is similar to the example shown in FIG.

Problems to be Solved by the Invention In the conventional example described above, when the self-holding state is released, the magnetizing force of the coil is applied in the opposite direction to the magnetic circuit including the permanent magnet, so the required magnetomotive force of the coil is required a high value. When using a battery as a power source, it is necessary to prepare a high-capacity battery or expand the coil winding space to take into consideration the deterioration of battery performance and design a design that allows a high magnetomotive force to be obtained with the same battery. These problems have led to higher prices and larger dimensions, which have become inconvenient issues from the standpoint of mounting on equipment.

The present invention aims to solve these conventional problems, and aims to provide an electromagnetic actuator that can operate with a small coil magnetomotive force without causing a decrease in attractive force in a self-holding state.

Means for Solving the Problems In order to solve the above problems, the electromagnetic actuator of the present invention includes: a self-holding circuit comprising a permanent magnet, a movable plunger, and a fixed yoke; a coil for exciting the self-holding magnetic circuit; It is composed of a movable iron core that forms a parallel magnetic path with the attraction part of the movable plunger for the magnetization of the permanent magnet and coil, and is significantly different from the conventional example in that the movable iron core is provided in parallel with the movable plunger. It is a point.

Function: Since the present invention has the above configuration, when the coil is energized in the same direction as the magnetization of the permanent magnet, the amount of magnetic flux passing through the movable iron core increases, so the movable iron core is attracted and forms a magnetic circuit in parallel with the movable plunger. . Therefore, when the coil energization is stopped, the magnetic flux of the permanent magnet is divided into the movable plunger and the movable iron core, so that the movable plunger attracting and holding force is reduced and a separation operation is performed. In addition, by energizing the coil in a direction that causes magnetization in a direction opposite to that of the permanent magnet while the movable plunger is separated, the movable iron core can also be returned to the initial position from which it was separated.

Embodiments Below, embodiments of the present invention will be explained based on the accompanying drawings. Figures 1, 2, and 3 show the operating states of the embodiment in order, and a permanent magnet 16 is closely installed at the center of the bottom of a substantially U-shaped outer yoke 15 with a step formed in the middle. An inner yoke 17 is provided on the upper end surface of the permanent magnet 16, and the center of the upper end thereof is in contact with the lower end attraction portion 19 of the movable plunger 1B.

Further, in the middle part of the inner yoke 17, there is a crotch part 2 of the outer yoke 15.
A step portion 21 is formed which is flush with 0, and these step portions 20 and 21 correspond to a flat movable iron core 22. A movable plunger 1B is located in the center on the open side of the outer yoke 15.
A flat plate-shaped upper yoke 23 having a hole therethrough is attached, and the outer yoke 15, inner yoke 17, and upper yoke 23 constitute a fixed yoke 24. A coil/I/25 is wound around the outer periphery of the permanent magnet 16 and the inner yoke 17 to excite the yoke circuit. Further, 26 is a spring biased in a direction to pull the movable plunger 18 away from the inner yoke 17, and 27 is a spring biased in a direction to pull the movable iron core 22 away from the stepped portions 20 and 21. Furthermore, 28 is a stopper that determines the position of the movable iron core 22 in the separated state. As shown in FIG. 2, the position where the movable plunger 18 stops when it is pulled away is, for example, when the movable plunger 18 is configured as a valve, the valve rubber attached to the movable plunger 18 closes the valve opening formed in the passage. When moving another mechanism, the movable plunger 1B comes into contact with a part of that mechanism and is stopped. Therefore, since it is unnecessary for the electromagnetic actuator itself of the present invention, illustration thereof is omitted.

With the above configuration, in the state shown in FIG. 1, the movable iron core 22
is away from the step parts 2o and 21, most of the magnetic flux of the permanent magnet 16 enters the inner yoke 17 from the adsorption part 19, passes through the movable plunger 1B, passes through the upper yoke 23 and the outer yoke 15, and is transferred to the permanent magnet 16. Flows through a self-retaining magnetic circuit back to spring 2
It overcomes the reaction force of 6 and holds it by suction. Next, as shown in FIG. 4, when the coil/L/25 is momentarily energized in a direction that causes magnetization in the same direction as the magnetization of the permanent magnet 16, the movable plunger 1B is attracted and held even more strongly, and the movable iron core 22 is also It overcomes the reaction force of the spring 27 and is suctioned and held until it comes into contact with the stepped portions 20 and 21. When the excitation of the coil 25 is released in this state, the magnetic flux of the permanent magnet 16 will be divided into a circuit passing through the attraction part 19 of the movable plunger 1B and a circuit passing through the movable iron core 22, so that the state shown in FIG. Compared to the spring 26, the suction and holding force is lower.
The force causes them to move apart as shown in Figure 2. At this time, the force that attracts and holds the movable iron core 22 also decreases, but since there is a gap for sliding between the movable plunger 1B and the upper yoke, if the strength of the two springs 26 and 27 is selected, It is easy to create the state shown in Figure 2. Next, when a current that excites the coil 27 in the opposite direction to the magnetization direction of the permanent magnet 16 is applied for a short time as shown in FIG. 4, the magnetic flux that attracts and holds the movable iron core 22 decreases, so as shown in FIG. The movable iron core 22 also becomes separated. In FIG. 3, the movable plunger 1B is in a position where it is working as an actuator, and when returning to the state shown in FIG. Suitable as a drive source for safety devices that

Incidentally, the two springs 26 and 27 can be omitted if the position of the movable plunger 18 and the movable iron core 22 are used upside down and the weight of the movable plunger 18 and the movable iron core 22 are utilized.

Furthermore, when the movable plunger 18 is pressed and returned from the state shown in FIG.
By dividing the flow into the 8 side and the movable iron core 22 side, the movable iron core 2
It is also possible as a design choice to return to the state shown in FIG. 4 without going through the state shown in FIG. 3 by reducing the adsorption/holding force of No. 2. In this case, since reverse magnetization is not applied to the permanent magnet 16, there is no risk of demagnetization.

Effects of the Invention As described above, the electromagnetic actuator of the present invention has the following effects.

(1) To move the movable plunger away, the coil need only be excited to the extent that it reinforces the magnetization of the permanent magnet, so a smaller coil current is required than when excitation is performed in the opposite direction as in the conventional example. Therefore, the capacity of a power source such as a battery can be reduced.

(2) If the configuration is such that the state shown in FIG. 2 is directly returned to the state shown in FIG. 1, there is no risk of demagnetization of the permanent magnet.

(3) In the conventional method, if the coil excitation time is short, the movable plunger is not sufficiently far from the attraction part, and the permanent magnet attraction force may exceed the spring reaction force, and the coil does not operate even if the coil is energized. In this regard, in the present invention, the coil energization time can be shortened because it is only necessary to energize the movable iron core during the time it takes to approach the position where it can be attracted only by the permanent magnet attraction force. This is also effective in extending battery life.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are longitudinal sectional views showing the operating state of an electromagnetic actuator in an embodiment of the present invention, Figure 4 is a waveform diagram showing the polarity of conduction to the coil, and Figure 5. , FIG. 6 is a longitudinal sectional view of a conventional example. 16...Permanent magnet, 1B...Movable plunger, 19...Adsorption part, 22...Movable iron core, 24...Fixed joint Iron, 25...
coil. Name of agent: Patent attorney Toshio Nakao Haga 1 person No. 4
Figure 5 Figure 6

Claims (1)

[Claims] A self-holding magnetic circuit consisting of a permanent magnet, a movable plunger, and a fixed yoke, a coil that excites the self-holding magnetic circuit, and a magnetic path that forms a parallel magnetic path with the attraction part of the movable plunger with respect to the magnetization of the permanent magnet. An electromagnetic actuator consisting of a movable plunger suction part and a movable iron core that forms a parallel magnetic path.