Solenoid valve device with self-retaining plunger

Abstract

To fix (hold) a plunger at two points with a combination of a solenoidal coil and a permanent magnet.SOLUTION: An electromagnetic valve device includes: a solenoidal coil 2; a plunger 1 which is made of a magnetic body and slides back and forth via a bearing 15 arranged in the solenoidal coil 2; a fixed iron core 5 which is arranged on the same axis as that of the plunger 1, is formed in a hollow shape, and has a one stopper part composed of a flange part 55 on its one end side; a connection member 11 connected to the plunger 1 and arranged so as to slide in the hollow part formed in the fixed iron core 5; and a permanent magnet 3 integrally arranged at one end side of the connecting member 11, the permanent magnet 3 operating so that a plunger head 15 is alternately adsorbed onto the flange part (stopper part) 55 of the fixed iron core 5 forming the stopper part or onto another stopper part 95 made of a magnetic body which is formed at one end side of a case 9 made of a cylindrical body.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a solenoid plunger and solenoid valve that reciprocates its shaft (iron core) by the action of electromagnetic force generated by passing a predetermined current through a coil, and in particular to a solenoid valve device having a self-retaining plunger that fixes the shaft (solenoid plunger) in a predetermined position during the reciprocating motion (stroke motion) to perform opening and closing functions of related devices, such as in a vacuum circuit. [Background technology]

[0002] A typical solenoid valve, such as that described in JP 8-250327 (Patent No. 3337180), operates by combining the force of an electromagnet (electromagnetic force) and the force of a coil spring. A movable core (shaft) located inside the solenoid valve is moved by turning a predetermined current on and off to a solenoid mechanism that forms the solenoid valve. To hold the movable core (plunger) in a predetermined position, a predetermined current (holding current) must be continuously applied to the solenoid. Furthermore, a two-way holding type in which the plunger moves in two linear directions and is held in a specific position in each of these two directions requires two solenoid coils C, as shown in Figure 4. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-250327 (Patent No. 3337180) Summary of the Invention [Problem to be solved by the invention]

[0004] In a typical self-holding solenoid valve device, a permanent magnet is provided at a predetermined position, allowing the armature to be held in a predetermined position (predetermined state) without the need for a holding current. However, in this conventional device, the electromagnet and the permanent magnet share the same magnetic circuit, causing 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. Therefore, when attempting to fix the armature in a predetermined position, it is difficult to obtain a sufficient holding force (fixing force). To address this problem, the present invention aims to provide a solenoid valve device having a self-holding plunger that is formed by one permanent magnet and one electromagnet, but in which the magnetic circuits formed by the electromagnet and the permanent magnet are separated, allowing the attractive force generated by the permanent magnet to be fully utilized. [Means for solving the problem]

[0005] In the first invention, which is the invention described in claim 1, a solenoid valve device having a self-retaining plunger is configured to include one solenoidal coil formed by winding a predetermined conductor wire into a cylindrical shape and forming an electromagnet when current is applied, one permanent magnet provided in series with the one solenoidal coil, magnetic shielding means provided between the two magnets and formed so that the magnetic circuits formed by the two magnets exist independently and do not interfere with each other, a plunger provided within the solenoidal coil and made of a magnetic body that moves linearly in the axial direction of the solenoidal coil, one end of which or a head portion consisting of a protruding portion formed integrally with the one end portion is 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.

[0006] 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 so as to constantly press the output shaft in the axial direction. [Effects of the Invention]

[0007] 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), and by further 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 started 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 plunger, which is made of a magnetic material, 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, and after the predetermined distance, the upper plunger is attracted to a predetermined location specified in two directions on a straight line by the magnetic force of the permanent magnet, which is generated separately and independently from the magnetic force of the electromagnet generated by the solenoid coil, and is securely fixed there. In other words, position retention is possible. In other words, in the present invention, one permanent magnet and one electromagnet are arranged in series, and the magnetic forces of these two magnets are generated independently, so the magnetic force of the permanent magnet can be fully utilized. Also, the plunger can be operated by simply energizing the solenoid coil momentarily, and no power is required to hold the plunger in the specified position, resulting in overall energy savings.

[0008] Next, in the second invention, which is an invention of claim 2, basically the same as the first invention, the plunger made of the movable iron core can be reliably fixed (held) by the attraction to the magnetic body formed by the permanent magnet. Specifically, the series of operations described above is performed by energizing a solenoid coil for a fixed time (instantaneous), exciting the coil, i.e., operating it as an electromagnet, thereby moving the plunger made of the movable iron core in a fixed direction. Then, when the plunger made of the movable iron core has moved a predetermined distance, the plunger head formed integrally with the plunger is attracted and fixed to a stopper made of a magnetic body by the magnetic force of the permanent magnet, and the plunger can be held (fixed) in a predetermined position, i.e., the plunger can be held (fixed) at the other stopper. In this way, by simply passing electricity momentarily through the electromagnet formed by the solenoidal 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) at two locations, which can be used, for example, as a plunger-based switching mechanism in various devices. [Brief explanation of the drawings]

[0009] [Figure 1] 3A to 3C are diagrams illustrating the first embodiment of the present invention, showing the plunger in each position. [Figure 2] FIG. 10 is a view illustrating a state in which the movable core is in one fixed (retained) position according to a second embodiment of the present invention. [Figure 3] 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. [Figure 4] 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. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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 a device with 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, when current is ON to the electromagnet formed by the solenoid coil 2, the stable position is the center position of the electromagnet formed by the solenoid coil 2, as shown in FIG. 1(B). In contrast, the stable position of the permanent magnet 3 is the position where the movable iron core of the permanent magnet 3 abuts against 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), and when the attractive force of the electromagnet is lost after the momentary current is applied, the plunger 1 moves to the state shown in Figure 1(C). Also, when a momentary current is applied to the solenoid coil 2 in the state shown in Figure 1(C), the plunger 1 passes through the state shown in Figure 1(B) in the same manner as above, and then transitions to the stable state shown in Figure 1(A). In this way, the plunger 1 functions as a solenoid valve, consuming power only during the opening and closing operations, and after the opening and closing operations are performed, the attractive force of the permanent magnet 3 is used to maintain the open and closed positions, so no power is consumed for maintaining the position.

[0011] As shown in FIG. 1, the solenoid valve device in the first embodiment comprises a case 9 made of a magnetic material, a solenoid coil 2, a plunger 1, a fixed iron core 5 which is arranged coaxially with the plunger 1 and has a hollow shape, and which has a flange portion on one end thereof and a stopper portion (first stopper portion) 55 which serves as a stopper for the operation of the plunger 1, and a permanent magnet 3 which is arranged at the first stopper portion 55 and has an N pole or an S pole formed at each of both terminal portions.

[0012] 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 FIGS. 2 and 3. This mechanism may be used, for example, in a valve mechanism installed in an introduction path for guiding an electron beam generated in an ultra-high vacuum chamber to an electron microscope chamber under normal vacuum. Specifically, as shown in FIG. 2, this mechanism is installed in 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. The valve mechanism 8 switches between open and closed states between the two chambers 82 and 83, and the solenoid mechanism controls its opening and closing operation. Next, the solenoid mechanism responsible for operating the valve shaft 81 and other components of the valve mechanism 8 will be described. As shown in FIGS. 2 and 3, this mechanism is basically composed of a solenoid coil 2 and a movable iron core (plunger) 1 that moves linearly when excited by the solenoid coil 2. As described above, the first embodiment and the second embodiment 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), 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.

[0013] Furthermore, in such a configuration, a head portion made of a magnetic material and consisting of a predetermined protrusion, i.e., plunger head 15, is provided on one end of the plunger 1 via a connecting member 11, and an output shaft 7 for transmitting 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 provided on one end of a cylindrical cover 91 made of a magnetic material and provided on an extension of one end of the cylindrical case 9.

[0014] In this configuration, one end of the output shaft 7 is supported by a bearing 77 provided at one end of the case 9. A spring (coil spring) 71 is provided at 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 FIGS. 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 first stopper 55 by the magnetic force of the permanent magnet 3, i.e., maintained in the position shown in FIG. 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 fixed core 5. The valve shaft 81 connected to the output shaft 7 also presses against an 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.

[0015] 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, moves away 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, where it is stopped. This causes the valve shaft 81 connected to the output shaft 71 to return, opening (communicating) the passage 85 provided 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 provided on one end side of the connecting member 11 comes into contact with the second stopper portion 95 provided on the end of the cover 91, which is also made of a cylindrical body and is made of a magnetic material and is formed on one end side of the cylindrical case 9, and is attracted thereto by the action of the magnetic force of the permanent magnet 3.

[0016] As a result, the plunger 1 is fixed (held) there. At this time, the magnetic circuit formed by the magnetic field lines forms a closed loop circuit as shown by the arrows in FIG. 2, and the plunger head 15 is fixed there. As a result, the valve mechanism 8, including the output shaft 7 and the valve shaft 81, is held (fixed) 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. Thus, the electromagnet formed by the solenoid coil 2 is excited simply by momentarily passing electricity through the electromagnet. Meanwhile, the plunger 1 is fixed (held) at each stopper portion 55, 95, i.e., the plunger head 15 is fixed, by the magnetic attraction of the permanent magnet 3. In this way, the plunger 1 can be reliably fixed (held) at two locations, which can serve as, for example, a switching mechanism in the valve mechanism 8.

[0017] 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 solenoid valve device of this 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: "Force of permanent magnet < Force of coil spring < Force of permanent magnet + Force of 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 construct 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 that 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. [Explanation of symbols]

[0018] 1 plunger 11 Connecting member 15 plunger head 2 solenoid coils 21 Changeover switch 25 bobbins 3. Permanent magnets 33 Guide section 4. Support 5 Fixed iron core 55 Flange portion (first stopper portion) 7 Output shaft 71 Coil spring 77 Bearings 8 Valve mechanism 81 Valve shaft 82 Ultra-high vacuum chamber 83 Normal vacuum chamber 85 Passage 88 O-ring 9 Case (non-magnetic) 91 Cover 95 Second stopper part 99 Magnetic shielding means

Claims

1. 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. 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.

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