JP7741541B2 - Solenoid valve device with self-retaining plunger - Google Patents

Description

The present invention relates to a solenoid plunger and solenoid valve that reciprocates its shaft (iron core) due to the action of electromagnetic force generated by passing a predetermined current through a coil. In particular, the present invention relates to a solenoid valve device with a self-retaining plunger that fixes the shaft (solenoid plunger) in a predetermined position during the reciprocating motion (stroke motion), thereby performing opening and closing functions of related devices, such as a vacuum circuit.

General solenoid valves, such as those described in JP 8-250327 (Patent No. 3337180), operate by combining the force of an electromagnet (electromagnetic force) and the force of a coil spring. The movable core (shaft) located inside the solenoid valve is moved by turning a predetermined current on and off to the solenoid mechanism that forms the solenoid valve. To hold this movable core (plunger) in a predetermined position, a predetermined current (holding current) must be continuously applied to the solenoid. Furthermore, in a two-way holding type where the plunger moves in two linear directions and is held in a specific position in these two directions, two coils (solenoid coils) C are required, as shown in Figure 4.

Japanese Unexamined Patent Publication No. 8-250327 (Patent No. 3337180)

In typical self-holding solenoid valve devices, a permanent magnet is installed in a predetermined position, allowing the movable core to be held in a predetermined position (predetermined state) without the need for a holding current. However, in these conventional devices, the electromagnet and the permanent magnet form the same magnetic circuit, which causes interference between the electromagnetic force generated by the electromagnet and the magnetic force generated by the permanent magnet, preventing the electromagnetic force and the permanent magnetic force from being fully exerted. This poses the problem of making it difficult to obtain sufficient holding (fixing) force when attempting to fix the movable core in a predetermined position. To address this problem, the present invention aims to provide a solenoid valve device with a self-holding plunger formed by one permanent magnet and one electromagnet, where the magnetic circuit formed by the electromagnet and the magnetic circuit formed by the permanent magnet are separated, allowing the attractive force generated by the permanent magnet to be fully utilized.

The first invention, which is the invention described in claim 1, relates to a solenoid valve device having a self-retaining plunger, and is configured to include a solenoid coil formed by winding a predetermined conductor wire into a cylindrical shape and forming an electromagnet when current is applied; a permanent magnet connected in series to the solenoid coil; a magnetic shielding means connected between the two magnets so that the magnetic circuits formed by the two magnets exist independently and do not interfere with each other; a plunger connected within the solenoid coil and made of a magnetic body that moves linearly in the axial direction of the solenoid coil, with one end or a head portion consisting of a protruding portion formed integrally with the one end being held in a predetermined position by the magnetic force of the permanent magnet; and an output shaft connected to the other end of the plunger to transmit the movement of the plunger.

In addition, in the second invention, which is the invention described in claim 2, the solenoid valve device having the self-retaining plunger described in claim 1 is configured so that a coil spring is provided at the output shaft, which operates to constantly press the output shaft in the axial direction.

By adopting this configuration, the first invention, which is the invention described in claim 1, is based on one permanent magnet and one electromagnet (solenoid coil). Furthermore, by arranging these two magnets in series and ensuring that the magnetic forces generated by the two magnets do not interfere with each other, the device can be activated by simply passing current through the solenoid coil that forms the electromagnet, which moves the movable iron core (plunger) on the solenoid side. After the plunger has moved a predetermined distance, the magnetic plunger can be attracted and fixed to the permanent magnet. In this way, the plunger can be driven by simply passing current through the solenoid coil. After the predetermined distance, the upper plunger is attracted to a predetermined location in two directions on a straight line by the magnetic force of the permanent magnet, which is formed separately and independently from the magnetic force of the electromagnet formed by the solenoid coil, and is securely fixed there. In other words, it is possible to maintain its position. In other words, the present invention uses one permanent magnet and one electromagnet in series, with the magnetic forces of these two magnets being independent, allowing for full and effective use of the magnetic force of the permanent magnet. Furthermore, the plunger can be operated simply by momentarily energizing the solenoid coil, and no power is required to hold the plunger in a specified position, resulting in overall energy savings.

Next, in the second invention, as described in claim 2, the plunger formed by the movable iron core can be reliably fixed (held) by the attraction to a magnetic body formed by a permanent magnet, similar to the first invention. Specifically, the series of operations described above involves energizing a solenoid coil for a fixed period of time (instantaneously), exciting the coil, i.e., operating it as an electromagnet, thereby moving the plunger formed by the movable iron core in a fixed direction. Then, when the plunger formed by the movable iron core has moved a predetermined distance, the plunger head formed integrally with the plunger is attracted and fixed to a stopper portion formed by a magnetic body by the magnetic force of the permanent magnet, thereby holding (fixing) the plunger in a predetermined position, i.e., the plunger at the other stopper portion. In this way, simply by passing electricity momentarily through the electromagnet formed by the solenoid coil, the electromagnet is activated (excited), while the plunger is fixed (held) at each stopper portion by the magnetic force of the permanent magnet. In this way, the plunger can be reliably fixed (held) in two places, making it possible to use it as a plunger-based switching mechanism in various devices, for example.

3A to 3C are diagrams illustrating the first embodiment of the present invention, showing the plunger in each position. FIG. 10 is a view illustrating a state in which the movable core is in one fixed (retained) position according to the second embodiment of the present invention. FIG. 10 is a view showing the second embodiment of the present invention, in which the movable core is in the other fixed (retained) position. FIG. 1 is a longitudinal sectional view of a conventional electromagnetic valve device of a two-coil type in which the plunger is fixed (held) at two positions.

A first embodiment of the present invention will be described with reference to FIG. 1. This first embodiment basically comprises one permanent magnet 3 and an electromagnet formed by one solenoid coil 2. The magnetic forces generated by these magnets are prevented from interfering with each other by a magnetic shielding means 99 provided between the magnetic circuits of the two magnets. In this configuration, a typical self-retaining plunger is driven by the movement of the plunger 1 in the electromagnet formed by the solenoid coil 2 shown in FIG. 1. Specifically, the stable position when current is ON to the electromagnet formed by the solenoid coil 2 is the center position of the electromagnet formed by the solenoid coil 2, as shown in FIG. 1(B). In contrast, the stable position for the permanent magnet 3 is the position where the movable iron core of the permanent magnet 3 abuts the stopper, as shown in FIG. 1(A) and (C). In the state shown in Figure 1, when a momentary current is applied to the solenoid coil 2, the plunger 1 moves to the state shown in Figure 1(b). After the momentary current is applied, the plunger 1 moves to the state shown in Figure 1(c) when the magnetic attraction force of the electromagnet is lost. Furthermore, when a momentary current is applied to the solenoid coil 2 in the state shown in Figure 1(c), the plunger 1 transitions through the state shown in Figure 1(b) and then to the stable state shown in Figure 1(a), as described above. In this way, the plunger 1 functions as a solenoid valve, consuming power only during the open and close operations. After the open and close operations are performed, the magnetic attraction force of the permanent magnet 3 is used to maintain the open and closed positions, so no power is consumed for maintenance.

As shown in Figure 1, the solenoid valve device in this first embodiment comprises a case 9 made of a magnetic material, a solenoid coil 2, a plunger 1, a hollow fixed iron core 5 arranged coaxially with the plunger 1, which has a flange on one end and a stopper portion (first stopper portion) 55 that acts as a stopper for the operation of the plunger 1, and a permanent magnet 3 arranged at the first stopper portion 55, with a north pole or south pole formed at each of the terminal ends.

Next, a second embodiment of the solenoid valve mechanism, based on a modified version of the first embodiment, in which the plunger is replaced with a two-piece type, will be described with reference to Figures 2 and 3. This mechanism may be used, for example, in a valve mechanism installed in an introduction path for guiding an electron beam excited in an ultra-high vacuum chamber to an electron microscope chamber under normal vacuum conditions. Specifically, as shown in Figure 2, this mechanism is installed in the middle of a passage 85 that sends an electron beam generated in an ultra-high vacuum chamber 82 to an electron microscope chamber installed in a normal vacuum chamber 83. It relates to a valve mechanism 8 that switches between open and closed states between the two chambers 82 and 83, and a solenoid mechanism that controls its opening and closing operation. Next, we will describe the solenoid mechanism that operates the valve shaft 81 and other components in the valve mechanism 8. This mechanism is basically composed of a solenoid-wound coil 2 and a movable iron core (plunger) 1 that moves linearly when excited by the solenoid coil 2, as shown in Figures 2 and 3. As described above, the first and second embodiments differ in the shape of the movable iron core (plunger) 1 that moves linearly around the electromagnet. In the first embodiment (see FIG. 1), current is applied only when the movable iron core (plunger) 1 moves. In contrast, in the second embodiment (see FIGS. 2 and 3), current is applied to the electromagnet to power the valve opening and closing, and the magnetic force of the electromagnet is used to hold the valve open. This is because the function of the solenoid valve in this embodiment is to quickly close the valve when the power is turned off (in the event of a power outage), and so the electromagnetic force is used to hold the valve open. For this reason, the movable iron core (plunger) in the first embodiment (see FIG. 1) is shaped so that the magnetic circuit does not close, while the magnetic circuit in the second embodiment (see FIGS. 2 and 3) is shaped so that the magnetic circuit closes when current is applied.

Furthermore, in this configuration, a head portion, i.e., plunger head 15, made of a magnetic material and consisting of a predetermined protrusion is provided on one end of the plunger 1 via a connecting member 11, and an output shaft 7 that transmits the movement of the plunger 1 is provided on the other end. The connecting member 11 is connected to the plunger 1 and slides within a hollow portion formed in the fixed iron core 5. Therefore, as the plunger 1 is operated, the plunger head 15 is alternately attracted to the one stopper portion (first stopper portion) 55 and the other stopper portion (second stopper portion) 95, made of a lid-like body and located on one end of a cylindrical cover 91, also made of a magnetic material and located on an extension of one end of the cylindrical case 9.

In this configuration, one end of the output shaft 7 is supported by a bearing 77 located at one end of the case 9. A spring (coil spring) 71 is provided on the bearing 77, which constantly guides the valve shaft 81 connected to the output shaft 7 toward the closed position of the valve mechanism 8. This spring 71 instantly maintains the valve mechanism 8 (see Figures 2 and 3) in a closed position, even when the device is powered off due to a power outage. In this state, the plunger head 15 integrally formed with the plunger 1 is attracted to the one stopper portion (first stopper portion) 55 by the magnetic force of the permanent magnet 3, i.e., is maintained in the position shown in Figure 2 by the action of magnetic field lines. As a result, the output shaft 7 and the connected plunger 1 are constantly pressed away from the opposing fixed iron core 5. The valve shaft 81 connected to the output shaft 7 also presses against the O-ring 88 that forms the valve mechanism 8. As a result, the passage 85 connecting the ultra-high vacuum chamber 82 and the normal vacuum chamber 83 is blocked. In this way, the entire solenoid valve device, including the valve mechanism 8, is held (fixed) in a predetermined state, preventing any rattle or looseness in the entire device. As a result, the valve mechanism 8 connected to this solenoid valve device is always held in a constant state, and unnecessary operation is prevented.

Next, an instantaneous current is passed through the solenoid coil 2 to excite it. This moves the plunger 1 in a predetermined direction. Specifically, as shown in FIG. 3, the plunger 1 is moved in the direction of the arrow in FIG. 3. As a result, the plunger head 15, which is coaxially attached to the plunger 1 via the connecting member 11 and supported by the support 4, disengages from the first fixed location (first stopper portion) 55 against the spring reaction force of the spring 71. This causes the plunger 1 to move in the direction of the arrow in FIG. 3 and come into contact with the fixed iron core 5, stopping its movement. This causes the valve shaft 81 connected to the output shaft 71 to return, opening (communicating) the passage 85 between the ultra-high vacuum chamber 82 and the normal vacuum chamber 83 formed on the electron microscope side. At this time, the plunger head 15 attached to one end of the connecting member 11 comes into contact with the second stopper portion 95 attached to the end of the cover 91, which is also made of a cylindrical body and magnetic material and is formed on one end of the cylindrical case 9, and is attracted there by the magnetic force of the permanent magnet 3.

This fixes (holds) the plunger 1 in place. At this time, the magnetic circuit formed by the magnetic field lines forms a closed loop as indicated by the arrows in Figure 2, and the plunger head 15 is fixed in place. As a result, the valve mechanism 8, including the output shaft 7 and valve shaft 81, is held in a stable state. Therefore, the passage 85 connecting the ultra-high vacuum chamber 82 and the normal vacuum chamber 83 is maintained in a connected state. In this way, the electromagnet formed by the solenoid coil 2 is excited simply by momentarily passing electricity through it. Meanwhile, the fixation (holding) of the plunger 1 at each stopper portion 55, 95, i.e., the fixation of the plunger head 15, can be achieved by the magnetic attraction of the permanent magnet 3. In this way, the plunger 1 can be reliably fixed in two locations, which can serve, for example, as a switching mechanism in the valve mechanism 8.

In a typical solenoid valve device, the open state is maintained by maintaining the valve in an energized state, and it is required to instantly close the valve when the power is turned off. To achieve this function, the spring force of a coil spring is used as the closing force. Therefore, in a conventional solenoid valve device, the electromagnetic force for maintaining the open state must be a holding force greater than the spring force of the coil spring. In contrast, in the solenoid valve device of this embodiment, the holding force is the resultant force of the magnetic force of the permanent magnet 3 and the magnetic force of the electromagnet (solenoid wound coil) 2. That is, in the present embodiment, the relationship between the spring force of the coil spring 71 acting to close the valve mechanism 8, the force of the permanent magnet 3 acting as a force to maintain the valve open, and the force of the electromagnet 2 is adjusted as follows:
"The force of a permanent magnet < the force of a coil spring < the force of a permanent magnet + the force of an electromagnet"
The holding force of the permanent magnet 3 can be easily adjusted by inserting a thin spacer between the contact point of the fixed magnetic pole and the movable iron core (plunger) to create a gap. In other words, by adjusting the force of the permanent magnet 3 to be slightly smaller than the spring force of the coil spring 71, the "open" position can be maintained by the slight magnetic force of the electromagnet (solenoid coil) 2, due to the relationship "spring force of the coil spring - magnetic force of the permanent magnet < magnetic force of the electromagnet (solenoid coil)." This makes it possible to configure a solenoid valve device that can maintain an open position with extremely little power. Furthermore, in this embodiment, the driving force when the valve begins to close comes solely from the spring force of the coil spring 71, but the valve pressing force when the valve is closed comes from the spring force of the coil spring 71 and the magnetic force of the permanent magnet 3. The magnetic force of a rare-earth permanent magnet can be generated with a strong force without consuming power by using an independent magnetic circuit. Therefore, the spring force of the coil spring 71 only needs to provide the driving force when the valve begins to close, and a weak spring force is generally sufficient. By using the magnetic force of a rare earth magnet, it is possible to obtain a force five times greater than the spring force of a conventional coil spring, and a self-holding electromagnetic valve device such as that of this embodiment can perform the same function as a valve that was previously opened and closed by compressed air pressure.

REFERENCE SIGNS LIST 1 plunger 11 connecting member 15 plunger head 2 solenoid coil 21 changeover switch 25 bobbin 3 permanent magnet 33 guide portion 4 support 5 fixed iron core 55 flange portion (first stopper portion)
7 Output shaft 71 Coil spring 77 Bearing 8 Valve mechanism 81 Valve shaft 82 Ultra-high vacuum chamber 83 Normal vacuum chamber 85 Passage 88 O-ring 9 Case (non-magnetic material)
91 Cover 95 Second stopper portion 99 Magnetic shielding means

Claims (2)

a solenoid coil formed by winding a predetermined conductor wire into a cylindrical shape and forming an electromagnet when energized;
one permanent magnet provided in series with the one solenoidal winding coil;
a first magnetic circuit formed by the solenoid coil, a second magnetic circuit formed by the permanent magnet, and magnetic shielding means disposed between the first magnetic circuit and the second magnetic circuit so as not to interfere with each other;
a plunger provided within the solenoid coil and made of a magnetic material that moves linearly in the axial direction of the solenoid coil , the plunger having a head portion made of a protruding portion integrally formed on one end side thereof that is held in a predetermined position by the magnetic force of the permanent magnet;
an output shaft connected to the other end of the plunger to transmit the movement of the plunger;
a first stopper portion that contacts and attracts and holds one surface of the head portion by the magnetic force of the permanent magnet, and a second stopper portion that contacts and holds the other surface of the head portion;
By momentarily energizing the solenoid coil to excite it, the head portion moves and is attracted alternately to the first stopper portion and the second stopper portion.
Electromagnetic valve device having a self-retaining plunger characterized by the above. 2. The solenoid valve device having a self-retaining plunger according to claim 1,
A coil spring is provided at the output shaft to constantly press the output shaft in the axial direction.
Electromagnetic valve device having a self-retaining plunger characterized by the above.