JP3693080B2 - Linear solenoid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear solenoid having an improved magnetic circuit configuration.
[0002]
[Prior art]
Conventionally, a linear solenoid has been used as a drive source of, for example, a hydraulic control valve as disclosed in Japanese Patent Laid-Open No. 5-126275. As shown in FIG. 5, a cylindrical coil 71 resin-molded is arranged in a cylindrical yoke 70 that also serves as a housing, and a cylindrical fixed iron core 72 is arranged on the inner periphery of the coil. A shaft 74 is inserted into and supported by the inner periphery of the fixed iron core 72 through a bearing 73 so as to be slidable in the axial direction. One end of the shaft 74 is in contact with the end of the spool 75 of the hydraulic control valve 69, and the other end of the shaft 74 is fitted with a movable iron core 76 that is attracted to the fixed iron core 72. The outer peripheral surface is opposed to the inner peripheral surface of the yoke 70 through a minute gap. As a result, a magnetic circuit is constituted by a path of the yoke 70 → the movable iron core 76 → the fixed iron core 72 → the yoke 70.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, since an air gap exists between both the yoke 70 and the movable iron core 76 and between the movable iron core 76 and the fixed iron core 72, the magnetic resistance of the magnetic circuit is considerably increased. If the facing area of the air gap portion is not increased, a necessary electromagnetic attractive force (magnetic flux passage amount) cannot be ensured, and there is a disadvantage that the linear solenoid is enlarged.
[0004]
In recent years, as shown in FIG. 6, in order to increase the facing area of the air gap portion between the yoke 77 and the movable iron core 78, a cylindrical portion 77 a extending on the inner peripheral side of the coil 79 is provided on the yoke 77. A configuration is considered in which the outer peripheral surface of the movable iron core 78 is opposed to the inner peripheral surface of the cylindrical portion 77a of the yoke 77 through a minute gap. In this device, a magnetic circuit is constituted by a path of yoke 77 → cylindrical portion 77a → movable iron core 78 → fixed iron core 82 → yoke 77.
[0005]
However, in this configuration, in order to increase the facing area of the air gap portion between the yoke 77 and the movable iron core 78, it is necessary to increase the axial dimension of the movable iron core 78, and the cylindrical portion 77a is interposed. Therefore, it is necessary to increase the diameter of the linear solenoid, and there is a drawback that the linear solenoid is increased in size.
[0006]
The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to provide a linear solenoid capable of achieving both reduction in magnetic resistance (increase in electromagnetic attraction force) and reduction in size of a magnetic circuit. There is.
[0007]
[Means for Solving the Problems]
[0012]
In the present invention, a coil is arranged inside a cylindrical yoke, a fixed iron core is arranged inside the coil, a movable iron core is opposed to an axial end surface of the fixed iron core, and an outer peripheral surface of the movable iron core is arranged. In the linear solenoid configured to face the inner peripheral end face of the yoke through a minute gap, a magnetic cover formed of a magnetic material is attached to the opening of the side end face of the yoke, and both the magnetic cover and the movable iron core face each other. In this position, a magnetic spring member made of a magnetic material is interposed so as to be in magnetic contact with the magnetic cover and the movable iron core. In this configuration, the first magnetic circuit via the yoke → air gap → movable iron core and the second magnetic circuit via the yoke → magnetic cover → magnetic spring member → movable iron core are provided in parallel. . In this case, since the first magnetic circuit has an air gap between the yoke and the movable iron core, the magnetic resistance is relatively large. However, the second magnetic circuit on the magnetic spring member side includes the magnetic cover and the magnetic spring. Since the member and the movable iron core are in magnetic contact with each other and there is no air gap, the magnetic resistance is extremely small. For this reason, in the region where the current flowing through the coil is relatively small (low current region), the magnetic flux mainly flows through the second magnetic circuit having no air gap and having a small magnetic resistance. Thereby, the electromagnetic attraction force in the low current region can be easily increased without increasing the size of the linear solenoid itself, and an ideal attraction force characteristic close to the linear can be obtained in the low current region.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment in which the present invention is applied to a spool valve type hydraulic control valve will be described with reference to FIGS. First, the configuration of the entire linear solenoid 11 serving as a drive source for the spool valve type hydraulic control valve will be described with reference to FIG. A yoke 12 that also serves as a housing of the linear solenoid 11 is formed in a cylindrical shape by a magnetic material, and a cylindrical fixed iron core 13 is concentrically disposed on the inside thereof, and is integrally formed at the left end portion of the fixed iron core 13. A flange-like flange portion 13 a is caulked to the left end portion of the yoke 12. A coil 15 molded in a cylindrical shape with a resin 14 is fitted and mounted on the outer periphery of the fixed core 13, and the length of the fixed core 13 is formed to fit over the left half of the coil 15. Has been.
[0014]
A cylindrical block-shaped movable iron core 16 is accommodated in the right side portion of the inner diameter cavity of the coil 15 so as to be slidable in the axial direction so as to face the fixed iron core 13. It faces the inner peripheral surface of the mold resin 14 through a minute gap. A plurality of oil grooves (not shown) extending in the axial direction are formed simultaneously on the inner peripheral surface of the mold resin 14 at the time of molding, and the oil filled in the linear solenoid 11 is moved when the movable iron core 16 slides. Each oil groove can flow freely.
[0015]
The outer peripheral surface of the outer peripheral surface of the movable iron core 16 that protrudes to the right from the mold resin 14 is the inner periphery of the thick annular ring-shaped side gap forming portion 17 integrally formed on the inner periphery of the right end of the yoke 12. It faces the end face through a minute gap. As a result, a first magnetic circuit is formed between the yoke 12 and the movable iron core 16 by a path of the yoke 12 → the side gap forming portion 17 → the air gap → the movable iron core 16.
[0016]
A stepped columnar boss 16a is integrally formed at the center of the right end surface of the movable iron core 16, and the boss 16a is a magnetic leaf spring 18 formed of an elastic magnetic material (for example, SUS420). It is fixed at the center. As shown in FIG. 2, the leaf spring 18 is formed by punching a plurality of openings 18b around a center portion 18a, thereby connecting the outer ring portion 18c and the center portion 18a with a plurality of spring pieces 18d. The mounting hole 18e is punched and formed in the center portion 18a. At the time of assembly, a washer 16b (FIG. 1) made of a magnetic material is fitted to the tip small diameter portion of the boss portion 16a in a state where the tip small diameter portion of the boss portion 16a of the movable iron core 16 is fitted in the mounting hole 18e of the leaf spring 18. The boss portion 16a of the movable iron core 16 is fixed to the center of the magnetic leaf spring 18 by fitting the reference portion) and caulking the small diameter portion of the boss portion 16a.
[0017]
The outer peripheral annular portion 18c of the magnetic leaf spring 18 is a right end portion of the yoke 12 in a state of being sandwiched between a right end edge of the yoke 12 and a cover 19 formed of a nonmagnetic material (for example, SUS304). It is fixed by caulking. As a result, a second magnetic circuit is formed between the yoke 12 and the movable iron core 16 by a path of the yoke 12 → the magnetic leaf spring 18 → the movable iron core 16, and this second magnetic circuit is the first magnetic circuit described above. The magnetic circuit (yoke 12 → side gap forming part 17 → air gap → movable iron core 16) is provided in parallel.
[0018]
On the other hand, a shaft 21 formed of a non-magnetic material (for example, SUS304) is press-fitted and fixed in a hole 20 formed in the central portion of the left side surface of the movable iron core 16. The shaft 21 is slidably inserted in the axial direction (left-right direction) through the bearing member 22, and the tip of the shaft 21 protrudes from the fixed iron core 13 to the left by a small amount.
[0019]
Next, the shape of the suction surfaces of the fixed iron core 13 and the movable iron core 16 will be described. A circular recess 23 is formed concentrically on the end surface of the fixed core 13 on the movable core 16 side, and an annular suction surface 24 is formed on the end surface of the annular projection surrounding the recess 23. The annular suction surface 24 is formed with the same width on the entire outer periphery of the end surface of the fixed iron core 13.
[0020]
Correspondingly, a tapered suction surface 25 that can enter and exit the recess 23 is formed concentrically with the recess 23 at a portion of the movable iron core 16 on the fixed core 13 side. A stepped surface 26 is formed at the position of the maximum diameter of the tapered suction surface 25 on the outer peripheral portion of the movable iron core 16, and the stepped surface 26 faces the annular suction surface 24. The step surface 26 is formed with the same width on the entire outer periphery of the movable iron core 16. Further, a nonmagnetic spacer 27 made of a nonmagnetic material such as brass is fixed to the end surface of the movable iron core 16 on the fixed iron core 13 side.
[0021]
In this case, the gap between the annular suction surface 24 and the step surface 26 is set to be larger than the gap between the nonmagnetic spacer 27 and the bottom surface of the recess 23. Thereby, the nonmagnetic spacer 27 functions as a stopper for restricting the leftward movement of the movable iron core 16, and the stepped surface 26 and the taper suction surface 25 of the movable iron core 16 abut against the annular suction surface 24 at the time of maximum suction. This also prevents the movable iron core 16 from being adsorbed and held by the fixed iron core 13.
[0022]
Note that a connector housing 29 is integrally formed with the mold resin 14 of the coil 15, and a terminal 28 insert-molded into the connector housing 29 and the coil 15 are electrically connected.
[0023]
A spool valve 30 is assembled to the left end surface of the linear solenoid 11 configured as described above. Hereinafter, the configuration of the spool valve 30 will be described. The spool valve 30 is configured by slidably storing a spool 32 in a sleeve 31 formed into a cylindrical shape by aluminum die casting. The right end of the sleeve 31 is caulked to the left end of the yoke 12 of the linear solenoid 11, and the right end of the spool 32 is in contact with the left end of the shaft 21 of the linear solenoid 11. In the sleeve 31, a drain port 34, an output port 35, an input port 36, and a feedback port 37 are formed in order from the right side.
[0024]
On the other hand, the spool 32 is formed with first and second large diameter portions 38, 39, and a minute annular gap (clearance) is formed between the outer peripheral surface of each large diameter portion 38, 39 and the inner peripheral surface of the sleeve 31. ) Is formed. When the spool 32 moves in the axial direction, the length of the annular gap where hydraulic oil supplied from the hydraulic source flows from the input port 36 to the output port 35 and the length of the annular gap where the hydraulic fluid supplied from the output port 35 flows to the drain port 34. As a result, the output pressure of the hydraulic oil flowing out from the output port 35 changes.
[0025]
On the other hand, a spring storage chamber 43 for storing the return spring 44 is formed at the left end portion of the sleeve 31 so as to open the left end surface, and an adjustment screw 45 is screwed into the opening portion of the spring storage chamber 43. The opening of the left end surface of the spring storage chamber 43 is sealed. A return spring 44 is mounted between the adjusting screw 45 and the spool 32, and the spool 32 is biased toward the linear solenoid 11 (right side) by the elastic force of the return spring 44. The right end is held in contact with the left end of the shaft 21.
[0026]
In the first embodiment described above, the leaf spring 18 that urges the movable iron core 16 and the shaft 21 toward the spool valve 30 is formed of a magnetic material, and the movable iron core 16 is attached to the magnetic leaf spring 18. The magnetic circuit between the yoke 12 and the movable iron core 16 includes a first magnetic circuit that passes through the yoke 12 → the side gap forming portion 17 → the air gap → the movable iron core 16, and the yoke 12 → the magnetic leaf spring 18 → the movable iron core. The second magnetic circuit via 16 is provided in parallel. In this case, in the first magnetic circuit, since an air gap exists between the side gap forming portion 17 of the yoke 12 and the movable iron core 16 as in the prior art, the magnetic resistance is relatively large. In the second magnetic circuit on the side, the yoke 12, the magnetic leaf spring 18 and the movable iron core 16 are in contact with each other, and there is no air gap, so the magnetic resistance is extremely small. For this reason, in a region where the current flowing through the coil 15 is relatively small (low current region), the magnetic flux flows through the second magnetic circuit on the magnetic leaf spring 18 side. Accordingly, in the low current region, the magnetic flux in the path of the second magnetic circuit (yoke 12 → magnetic leaf spring 18 → movable iron core 16) → fixed iron core 16 → flange portion 13a → yoke 12 flows and flows. An electromagnetic attractive force corresponding to the amount of magnetic flux passing acts between 16 and the fixed iron core 16.
[0027]
By the way, even in the conventional configuration (FIGS. 5 and 6), if the diameter and axial dimensions of the fixed iron core and the movable iron core are increased to increase the facing area of the air gap portion, as shown in FIG. The electromagnetic attractive force can be increased. However, in this case, there is a drawback that the linear solenoid becomes larger. In addition, the linearity (linearity) of the electromagnetic attractive force characteristic in the low current region required when performing fine adjustment of the electromagnetic attractive force is insufficient, and the control characteristic cannot be improved.
[0028]
On the other hand, in the present embodiment, in the low current region, the magnetic flux is added by the second magnetic circuit on the leaf spring 18 side without the air gap. Can do. Thereby, without increasing the size of the linear solenoid 11 itself, the electromagnetic attractive force in the low current region can be easily increased, and an ideal linear attractive force characteristic can be obtained in the low current region. It is possible to achieve both improvement in characteristics and miniaturization of the linear solenoid 11.
[0029]
On the other hand, in the conventional configuration shown in FIG. 6, a space for interposing the tubular portion 77a of the yoke between the coil 79 and the movable iron core 78 is required, which causes an increase in the diameter of the linear solenoid. In order to avoid this, when the diameter of the movable iron core 78 is reduced to secure the space of the cylindrical portion 77a, the facing area of the air gap portion between the movable iron core 78 and the fixed iron core 82 is reduced, and the magnetism of the air gap portion is reduced. The resistance increases and the electromagnetic attractive force decreases.
[0030]
On the other hand, in this embodiment, since the second magnetic circuit on the leaf spring 18 side exists, the first magnetic circuit (yoke 12 → side gap forming portion 17 → air gap → movable iron core 16) is correspondingly provided. Less magnetic flux to pass through. Therefore, there is no need to interpose part of the yoke 12 between the coil 15 and the movable iron core 16, and the outer circumferential surface of the movable iron core 16 is minutely placed on the inner circumferential surface of the mold resin 14 of the coil 15 as shown in FIG. It can be made to oppose through a clearance gap. Thus, the facing area of the air gap portion between the movable iron core 16 and the fixed iron core 13 can be increased without increasing the diameter of the linear solenoid 11, and the magnetic resistance of the air gap portion can be reduced. Will also lead to an increase in electromagnetic attraction.
[0031]
On the other hand, in the second embodiment of the present invention shown in FIG. 4, the leaf spring 60 that supports the movable iron core 16 is formed of a nonmagnetic material (for example, SUS304), and instead, the cover 61 is formed of a magnetic material (for example, SUS420). and forming a like), the position where both are opposed between the boss portion 16a of the magnetic cover 61 and the movable core 16, the magnetic spring member 62 magnetic cover 61 and the movable core 16, such as a spring formed of a magnetic material The magnetic cover 61 and the movable iron core 16 are magnetically short-circuited by a magnetic spring member 62. The method for fixing the movable iron core 16 and the leaf spring 60 and the method for fixing the leaf spring 60 and the magnetic cover 61 to the yoke 12 are the same as in the first embodiment described above. Other configurations are also the same as those of the first embodiment described above, and the same reference numerals are given and description thereof is omitted.
[0032]
In the second embodiment, the magnetic cover 61 and the magnetic spring member 62 play the same magnetic role as the magnetic leaf spring 18 of the first embodiment described above, and the second magnetic circuit is replaced by the yoke 12 → magnetic. It is constituted by a path of the cover 61 → the magnetic spring member 62 → the movable iron core 16. As a result, the magnetic flux also flows through the second magnetic circuit on the magnetic cover 61 side without the air gap, and the same operation and effect as the first embodiment described above can be obtained.
[0033]
In this case, the magnetic spring member 62 and the boss portion 16a of the movable iron core 16 may be in magnetic contact. Here, the magnetic contact means that the magnetic spring member 62 is brought into contact with the magnetic washer 16b that is caulked to the boss portion 16a of the movable iron core 16 in addition to the case where both are in direct contact with each other. 62 and the movable iron core 16 may be magnetically short-circuited by a magnetic washer 16b.
[0034]
The linear solenoid of the present invention is not limited to use as a drive source for a hydraulic control valve, and can be used as a drive source for various devices that require fine adjustment of the axial position.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view of a spool valve type hydraulic control valve showing a first embodiment of the present invention. FIG. 2 is a front view of a magnetic leaf spring. FIG. 3 is a characteristic showing a relationship between electromagnetic attraction force and current. FIG. 4 is an enlarged vertical front view of the main part showing a second embodiment of the present invention. FIG. 5 is a vertical front view of a conventional spool valve type hydraulic control valve. Vertical view of valve-type hydraulic control valve [Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Linear solenoid, 12 ... York, 13 ... Fixed iron core, 13a ... Flange part, 14 ... Mold resin, 15 ... Coil, 16 ... Movable iron core, 16a ... Boss part, 17 ... Side gap formation part, 18 ... Magnetic board Spring, 21 ... Shaft, 23 ... Recess, 24 ... Annular suction surface, 25 ... Tapered suction surface, 26 ... Stepped surface, 27 ... Non-magnetic spacer, 30 ... Spool valve, 31 ... Sleeve, 32 ... Spool, 60 ... Non-magnetic Leaf spring, 61 ... magnetic cover, 62 ... magnetic spring member.

Claims (1)

A coil is arranged inside the cylindrical yoke, a fixed iron core is arranged inside the coil, the movable iron core is opposed to the axial end surface of the fixed iron core, and the outer peripheral surface of the movable iron core is arranged inside the yoke. In a linear solenoid that is opposed to the peripheral end face through a minute gap,
The side end face opening is attached a magnetic cover which is formed of a magnetic material of the yoke, at a position where both are opposed between the magnetic cover and the movable iron core, the movable spring member formed of a magnetic material and the magnetic cover A linear solenoid characterized by being interposed so as to be in magnetic contact with an iron core .

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