JPS601814A - Solenoid with built-in permanent magnet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solenoid equipped with a permanent magnet, and more particularly to a solenoid for low power use.

Solenoids equipped with permanent magnets include so-called self-holding solenoids, which hold themselves by the attractive force of the permanent magnet, and when energized to the electromagnetic coil, reduce the attractive force of the permanent magnet and separate the movable iron core. There is a non-self-holding type solenoid that maintains the attracted state by the attraction force caused by energization and the attraction force of a permanent magnet, but the present invention is suitable for any type of solenoid.

Conventional configurations and their problems Since self-holding solenoids do not require electricity to maintain the attracted position, they are suitable for applications where power consumption and coil temperature rise are problematic. In particular, it is advantageous when using a battery power source because a momentary energization is sufficient to release the suction state. However, since the magnetomotive force caused by energization acts in a direction that cancels the magnetic flux of the permanent magnet, there is a risk that the permanent magnet will be demagnetized and the attraction and holding force will be reduced. In particular, when using permanent magnets with low coercive force or permanent magnets that are prone to low-temperature demagnetization,
Also, if a permanent magnet with a thin plate thickness in the magnetization direction is used, there is a high possibility that demagnetization will occur. For this reason, there is a conventional example as shown in FIG. 1 as a structure for reducing energization demagnetization. here,
Reference numeral 101 denotes a U-shaped fixed yoke, with a permanent magnet 102 located at the center of its bottom surface, and an auxiliary yoke 103 having a T-shaped cross section provided above. An electromagnetic coil 104 is located in the space between the fixed yoke 101 and the outer periphery of the auxiliary yoke 103. The leg end face of the fixed yoke 101 and the auxiliary yoke 10
The upper end surfaces of 3 are processed to be the same plane, and correspond to a plate-shaped movable iron core 106 that comes into contact with or separates from these end surfaces. The movement of the movable iron 106 is transmitted by the shaft 106, and the movable iron 106 is always urged in the direction of separation by a spring (not shown). In FIG. 1, (A) shows the attracting and holding state, in which the movable iron core 106 is attracted by the magnetic flux A of the permanent magnet 102. Next, the electromagnetic coil 104
When energized, the bottom outer circumference of the auxiliary yoke 103 and the fixed yoke 10
Since the air gap 107 with the inner surface of the leg 1 is set smaller than the thickness of the permanent magnet 102, the magnetic flux B of the electromagnetic coil 104 and the magnetic flux of the permanent magnet 102 pass through the air gap 107. This is the state shown in FIG. 1(B). Therefore, the magnetic flux on the attracting surface of the movable core 105 is drastically reduced or its direction is reversed, so that the attracting and holding force is reduced at the same time as the current is applied, and the movable core 105 is separated by the force of the spring as shown in FIG. In this way, by making the air gap 107i smaller than the magnetic resistance of the permanent magnet 1o2, magnetic flux in the opposite direction is prevented from passing through the permanent magnet 102 during energization, thereby reducing the demagnetization effect caused by energization.

In this conventional example, there are three suction surfaces: the end surfaces of both legs of the fixed yoke 101 and the center end surface of the auxiliary yoke 103, so it is necessary that the heights of these suction surfaces be on the same plane. If the surface is rough or rough, the adsorption and holding power will decrease. Therefore, it is necessary to polish these suction surfaces after assembly to make them uniform, which increases the cost.

In addition, with the same configuration as in Fig. 1, as shown in Fig. 2 (A), the town moving iron 105 is attracted and held by the magnetic flux A of the permanent magnet 102 with a small magnetic force and the magnetic flux C generated by the minute direct current flowing through the electromagnetic coil 104. However, when the current supply to the electromagnetic coil 104 is stopped, the magnetic flux on the attracting surface of the movable core 105 becomes only the magnetic flux A, so that the attracting and holding force decreases, and the movable core 105 (not shown) is constantly urged in the direction of separation. As shown in the same figure (B), the movable iron core 105 is
In the case of the conventional example in which the solenoid is used as a non-self-holding type solenoid that separates, there are three suction surfaces: the end surfaces of both legs of the fixed yoke 101 and the center end surface of the auxiliary yoke 103, so the height of the suction surfaces is the same plane. If the height is uneven or the surface is rough, the adsorption and holding power will decrease. Therefore, it is necessary to polish these suction surfaces after assembly to make them uniform, which increases the cost.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an inexpensive solenoid with a built-in permanent magnet that functions with low power and does not require polishing.

Structure of the Invention In order to achieve this object, the present invention includes a substantially symmetrical fixed yoke on the outside of the electromagnetic coil, a movable iron core that is slidably provided inside and outside the electromagnetic coil, and a movable iron core provided on the inner surface of the fixed yoke. a permanent magnet located between the iron core and having magnetic poles facing each other and fixed in substantially symmetrical positions with respect to the axis of the movable core, and a movable core located between the permanent magnet and the electromagnetic coil and close to the permanent magnet and the electromagnetic coil. The auxiliary yoke has an auxiliary yoke that is approximately symmetrical around the movable core, fixed yoke, auxiliary yoke, and a magnetic gap in the magnetic path surrounding the movable core. magnet,
By making the dimensions smaller than the magnetic gap in the magnetic path surrounding the movable iron core, the magnetic flux of the electromagnetic coil does not pass directly through the permanent magnet, making it possible to create fixed yoke, auxiliary yoke, movable iron core, etc. with small magnetic gaps. Since it passes through the magnetic path around the fixed yoke,
When used as a self-holding solenoid, it not only prevents the permanent magnet from demagnetizing, but also operates by simply passing a small current through the electromagnetic coil. When used as a non-self-holding solenoid, the magnetic flux of the electromagnetic coil does not pass through the permanent magnet part with a large magnetic gap, but instead passes through the fixed yoke, auxiliary yoke, movable iron core, and fixed joint with a small magnetic gap. Since it passes through the iron path, it acts to attract and hold with low power, and when used as a self-holding type or non-self-holding type solenoid, in the attracting and holding state, the magnetic flux of the permanent magnet is transferred to the auxiliary yoke.
By limiting the suction contact surface to one place by pouring it to the bottom of the movable core/fixed yoke, post-assembly polishing as in the conventional example is no longer necessary.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 3 is a vertical cross-sectional view showing an embodiment of a self-holding solenoid, in which (A) shows the suction self-holding state, (B) shows the state at the moment of energization, and (C) shows the fl separation state. Indicates the condition. Here, a fixed iron core 2 is fixed to the center bottom surface of the bottomed cylindrical Ω fixed yoke 1.

An O-ring 3 is inserted into the outer peripheral surface of the fixed iron core 2, and the O-ring 3 is in close contact with an outer non-magnetic cylinder 4.

Further, an electromagnetic coil 6 wound around a coil bobbin 5 is housed concentrically with the fixed iron core 2 and outside the non-magnetic cylinder 4, and an annular auxiliary yoke is placed immediately above the electromagnetic coil 6 and concentrically with the fixed iron core 2. 7 are inscribed in the inner peripheral surface of the fixed yoke 1, and the non-magnetic injection body 8 is stacked on top of the auxiliary yoke 7.
are stacked on top of the non-magnetic injection body 8 in an annular shape with an inner circumferential surface of N.
A permanent magnet 9 is fixed and magnetized so that the outer peripheral surface becomes the S pole. The movable iron core ICIj is slidably inserted inside the non-magnetic cylinder 4. Here, the magnetic gap between the inner peripheral surface of the auxiliary yoke 7 and the movable iron core 10 is determined by the inner diameter of the auxiliary yoke 7 and the outer diameter of the movable iron core 10, but is more permanent than the magnetic gap in this part. The radial dimension is determined so that the magnetic gap between the inner circumferential surface of the fixed yoke 1 and the i1 moving iron core 10 via the magnet 9 is larger. Therefore, in the adsorption/holding state shown in FIG. 3(A), the magnetic flux A[
The magnetic flux B flows from the movable core 1o, passes through the fixed core 2 and the fixed core 10, and returns to the permanent magnet 9. When the electromagnetic coil 6 is energized as shown in FIG.
- The magnetic flux of the permanent magnet 9 flows through the path of the movable iron core 10, the auxiliary yoke γ, the fixed yoke 1, and the fixed iron core 2 to the attraction surface 11 of the movable iron core 10 in the opposite direction to that of the magnetic flux of the permanent magnet 9. As a result, the suction holding force is drastically reduced, and the force of a separate spring (not shown) acts to cause the movable core ICIj to separate from the fixed core 2 as shown in FIG. 3(c).

Magnetic flux A of the permanent magnet 9 generated when the electromagnetic coil 6 is energized
The magnetic flux B in the direction of canceling does not flow through the permanent magnet 9 itself as shown in FIG. Because of this, it is possible to prevent demagnetization, which is caused by almost all magnetic fields in the demagnetizing direction being applied to the permanent magnet 9. Of course, since the only parts to be attracted are the end face 11 of the movable core 10 and the upper end face 12 of the fixed core 2, there is no need for polishing to achieve flatness after assembly.

Furthermore, by making the permanent magnet 9 circular and inscribing the inner surface of the fixed yoke 1 into the outer peripheral surface of the permanent magnet 9, the magnetic resistance of the magnetic path of the magnetic flux A of the permanent magnet 9 can be reduced as shown in FIG. As a result, it is possible to downsize the permanent magnet for obtaining the necessary self-holding attraction force.

In addition, by making the auxiliary yoke 7 into an annular shape and inscribing the outer peripheral surface of the auxiliary yoke 7 into the inner surface of the fixed yoke 1, it is possible to cancel the magnetic flux A of the permanent magnet 9 as shown in the same figure (B). Electromagnetic coil 6
The magnetic resistance of the magnetic path of the magnetic flux B can be reduced, and as a result, the size of the electromagnetic coil 6 can be reduced.

In addition, an O-ring is inserted into the fixed iron core 2, a non-magnetic cylinder 4 is inserted in close contact with the outer periphery of the O-ring, and an electromagnetic coil 6 is further inserted concentrically, and an auxiliary yoke, a non-magnetic injection body 8, and a permanent magnet are inserted. 9 are stacked, and the fixed yoke 1 is placed concentrically on the outside.As a result, the relative position of each part is determined without any variation, making it easy to assemble, and making custom orders stable and suppressing variations. Mass production can be made easier.

In the embodiment shown in FIG. 3, the fixed yoke 1 has a cylindrical shape with a bottom, but it may also be U-shaped, and the permanent magnet 9 may be divided into a plurality of pieces instead of annular, with the same poles facing each other. good. Further, the fixed iron core 2 may be omitted, and the bottom surface of the fixed yoke 1 may serve as a suction surface, or the bottom surface may be partially protruded by processing.

FIG. 4 shows an embodiment of a non-self-holding solenoid, and FIG. 4 (A) shows an electromagnetic coil 6 energized, and the magnetic flux B of the electromagnetic coil 6 and the magnetic flux A of the permanent magnet 9 generate a spring (not shown). (B) shows a state in which the movable core 10 is attracted and held by the force of the spring, and (B) shows a state in which the electromagnetic coil 6 is de-energized and the movable core 1° is separated by the force of the spring.

The configuration is the same as in FIG. 3, and the only difference is the magnetic force of the permanent magnet 9 and the winding specifications of the electromagnetic coil 6. The same numbers are given to the same parts, and a description of the configuration will be omitted. In this case as well, the third
Similar to the self-holding solenoid shown in the figure, the only parts that are attracted are the end face 11 of the movable core 10 and the upper end face 12 of the fixed core 2, so there is no need for polishing to achieve flatness after assembly.

In addition, the permanent magnet 9 is annular, and the outer circumferential surface of the permanent magnet 9 is in contact with the inner surface of the fixed iron core 1, so that the magnetic resistance of the magnetic path of the magnetic flux A of the permanent magnet 9 is reduced as shown in FIG. 4(A). As a result, the permanent magnet can be made smaller and the entire solenoid can be made smaller.

In addition, the auxiliary yoke 7 is annular, and the outer peripheral surface of the auxiliary yoke 7 is in contact with the inner surface of the fixed yoke 1, so that the magnetic resistance of the magnetic path of the magnetic flux B caused by the electromagnetic coil 6 is reduced as shown in FIG. As a result, the magnetomotive force of the electromagnetic coil 6 for attracting and holding the movable iron core 10 can be small, so that the electromagnetic coil 6 can be made smaller and it is possible to attract and hold the movable iron core 10 with low power supply. The ease of assembly is similar to that of the self-holding solenoid shown in FIG.

In addition, when the solenoid of the embodiment shown in FIGS. 3 and 4 is applied to a solenoid pulp that safely shuts off the gas passage of household gas appliances, a valve is installed on the end surface of the movable core 1o opposite to the suction surface 11. By attaching rubber to a body having a valve seat for closing the gas flow path, a safety shutoff valve can be easily constructed. In this case, in order to prevent gas from leaking out of the gas passage, the inside of the non-magnetic cylinder 4 is airtightly sealed between the fixed iron core 2 and the O-ring 3, so it is configured as a shutoff valve. In this case, simply sealing between the body and the non-magnetic cylinder with a fixed gasket such as a ring allows for a simple, secure and highly reliable sealing structure.

Effects of the Invention As described above, the permanent magnet built-in solenoid of the present invention provides the following effects.

(1) The same magnetic poles of a permanent magnet are fixed facing each other inside a substantially symmetrical fixed yoke outside the electromagnetic coil, and a substantially symmetrical auxiliary yoke is placed closer to the electromagnetic coil than the permanent magnet and centered around the axis of the movable iron core. When the movable iron core is in an attracted state, the magnetic gap between the fixed yoke and the movable iron core via the auxiliary yoke is smaller than the magnetic gap between the fixed yoke and the movable iron core via the auxiliary yoke. Therefore, the magnetic flux of the electromagnetic coil does not pass through the permanent magnet, which has a high magnetic resistance, but through the auxiliary yoke, which has a low magnetic resistance, and passes through the movable core attracting surface at two locations, so that it does not pass through the flat surface as in the conventional example. This makes it possible to provide an inexpensive solenoid with a built-in permanent magnet that does not require post-assembly polishing of the reservoir to ensure accuracy.

(2) Since the magnetic flux of the electromagnetic coil does not directly pass through the permanent magnet, there is no risk of permanent magnet demagnetization even when used as a self-holding solenoid.

(3) The magnetic flux of the electromagnetic coil passes through the auxiliary yoke, which is close to the electromagnetic coil and has a small magnetic gap, and acts on the adsorption surface of the movable core, so the power applied to the electromagnetic coil can be low.

(4) Since the auxiliary yoke is configured to be separated from the permanent magnet, when the movable iron core is attracted and held, there is less magnetic flux leaking to areas other than the attraction surface of the movable iron core, and it acts effectively on the attraction surface, making it possible to reduce the size of the permanent magnet. can be converted into

[Brief explanation of drawings]

Figures 1 (A), (B), and (C) show the adsorption and holding state of a conventional self-holding solenoid with a built-in permanent magnet. FIG. 2(A) is a vertical cross-sectional view showing the energized state and the separated state. (B) shows the adsorption and holding state of the same non-self-holding solenoid. Longitudinal cross-sectional view showing separation state, Fig. 3 (A), (B)
, CG) is a vertical cross-sectional view showing the self-holding solenoid of the permanent magnet built-in solenoid in the adsorption/holding state 1 energized state and separated state in an embodiment of the present invention, FIG. 4(A),
(B) is a longitudinal cross-sectional view showing the non-self-holding solenoid in an adsorption/holding state and a separated state. 1... fixed yoke, 6... electromagnetic coil,
7... Auxiliary yoke, 9... Permanent magnet, 1
o゛°゛°°Movable iron core〇 Name of agent Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 Figure 01 Figure 3 Figure 4

Claims (4)

[Claims] (1) An electromagnetic coil, a substantially symmetrical fixed yoke on the outside of the electromagnetic coil, a movable core slidably provided inside the electromagnetic coil, and a space between the inner surface of the fixed yoke and the movable core. a permanent magnet with the same magnetic poles fixed facing each other in substantially symmetrical positions, and an auxiliary yoke that is substantially symmetrical about the movable iron core and located between the permanent magnet and the electromagnetic coil and closer to the electromagnetic coil than the permanent magnet. In this auxiliary yoke, when the movable iron core is in an attracted state and the electromagnetic coil is energized, the magnetic gap of the magnetic path surrounding the movable iron core, fixed yoke, auxiliary yoke, and movable iron core is A solenoid with a built-in permanent magnet whose dimensions are smaller than the magnetic gap in the magnetic path surrounding the iron, permanent magnet, and movable iron core. (2) The solenoid with a built-in permanent magnet according to claim 1, wherein the permanent magnet is annular, and the inner surface of the fixed yoke is inscribed in the outer peripheral surface of the permanent magnet. (3) The solenoid with a built-in permanent magnet according to claim 2, wherein the auxiliary yoke is annular, and the outer peripheral surface of the auxiliary yoke is inscribed in the inner surface of the fixed yoke. (4) Insert a non-magnetic cylinder inside the electromagnetic coil, have a fixed core and a movable core inside the coaxial part of the non-magnetic cylinder, insert the ○ ring into the ○ ring groove on the outer periphery of the fixed core, and insert the ○ ring into the ○ ring groove on the outer periphery of the fixed core, and A solenoid with a built-in permanent magnet according to claim 1, wherein an electromagnetic coil, an auxiliary yoke, a permanent magnet, and a fixed yoke are provided on a concentric axis.