WO2019026211A1

WO2019026211A1 - Electromagnetic type drive unit

Info

Publication number: WO2019026211A1
Application number: PCT/JP2017/028095
Authority: WO
Inventors: 潤岡村; 滝口　和夫
Original assignee: 日立建機株式会社
Priority date: 2017-08-02
Filing date: 2017-08-02
Publication date: 2019-02-07
Also published as: JP6571898B2; JPWO2019026211A1

Abstract

An electromagnetic type drive unit (2) is provided with a stator (4), a plunger (5), a spacer (7), a yoke (8), and a coil (16). An end portion of the plunger (5) on the stator (4) side is provided with a magnetic pole portion (5A). A first edge (5J) is provided at the outer peripheral edge of the magnetic pole portion (5A) on the stator (4) side thereof. The stator (4) is provided with a tubular magnetic control portion (4G) into which the magnetic pole portion (5A) of the plunger (5) enters. An outer peripheral surface of the tubular magnetic control portion (4G) is provided with a tapered portion (4L) becoming gradually smaller in diameter toward the plunger (5) side. A second edge (5K) is provided in a portion of the outer peripheral surface of the magnetic pole portion (5A) which is spaced apart from the first edge (5J) on the opposite side from the stator (4). The second edge (5K), upon entering a bottomed hole (4J) of the tubular magnetic control portion (4G), is subjected to a magnetic force in a direction away from the stator (4) in a gap between the second edge (5K) and an opening end (4H) of the tubular magnetic control portion (4G).

Description

Electromagnetic drive unit

The present invention relates to an electromagnetic drive unit suitably used, for example, in an electromagnetic proportional hydraulic control valve or the like which constitutes a hydraulic circuit of a construction machine.

BACKGROUND ART In recent years, in construction machines typified by hydraulic shovels, a large number of equipments that perform electronic control have been adopted for the purpose of reducing fuel consumption and improving controllability. For example, a hydraulic actuator mounted on a construction machine is controlled by a control valve, and this control valve is remotely controlled by a hydraulic pressure (pilot pressure) controlled by an electromagnetic proportional hydraulic control valve.

Here, an electromagnetic drive unit is incorporated in the electromagnetic proportional hydraulic control valve in order to control the output value of the hydraulic pressure in proportion to the current value (feed current value) of the control signal supplied from the controller or the like. . In this electromagnetic drive unit, the stator (fixed iron core) and the plunger (movable iron core) are coaxially arranged, and by performing power supply control to these stator and solenoid coil arranged so as to surround the plunger, the stator The amount of excitation is variably controlled. Since a suction force corresponding to the amount of excitation of the stator acts between the stator and the plunger, this suction force can be used as a driving force to drive an object to be driven such as a valve.

Here, in a hydraulic control valve using an electromagnetic drive unit, the elastic force of a spring or the like acting on the valve body and the oil pressure are balanced with the driving force of the electromagnetic drive unit, and the valve body is adjusted according to the balanced load. By displacing, the opening amount of the oil passage is adjusted. Therefore, in order to perform hydraulic control with higher accuracy, the driving force output from the electromagnetic drive unit, that is, the attraction force acting between the stator and the plunger is supplied to the electromagnetic drive unit. It is desirable to rely solely on That is, it is desirable that the suction force acting between the stator and the plunger be constant regardless of the position of the plunger relative to the stator (the distance between the stator and the plunger).

On the other hand, a first suction portion comprising a concave portion having a tapered surface gradually expanding in diameter toward the plunger is provided at an end portion of the stator facing the plunger, and a cylindrical shape is formed closer to the plunger than the first suction portion. An electromagnetic drive unit is proposed in which a second suction unit is provided and the inner circumferential surface of the second suction unit is continuous with the recess of the first suction unit (see Patent Document 1).

In the electromagnetic drive unit according to Patent Document 1, the gap (gap) between the stator and the plunger is small. For this reason, when the tapered surface formed on the outer periphery of the end portion on the stator side of the plunger faces the tapered surface formed in the recess of the first suction portion of the stator, the attraction force is mainly the first of the stator. It occurs between the suction part and the end face on the stator side of the plunger. On the other hand, when the gap between the stator and the plunger is large, a suction force is generated mainly between the inner peripheral surface of the second suction portion of the stator and the tapered surface formed at the end of the plunger on the stator side. Do. Therefore, the electromagnetic drive unit according to Patent Document 1 can suppress the decrease in suction force even in the state where the gap between the stator and the plunger is large, and regardless of the position of the plunger relative to the stator, between the stator and the plunger The suction force acting on can be kept almost constant.

JP 2000-277327 A

However, in the electromagnetic drive unit according to Patent Document 1, when the gap between the plunger and the stator is further reduced by the attraction of the plunger to the stator, the attraction force generated between the plunger and the stator rapidly increases. For this reason, for example, in a region where the gap between the plunger and the stator approaches the minimum value, even if the value of the feeding current supplied to the electromagnetic drive unit is constant, the attraction between the plunger and the stator is constant. There is a problem that it is difficult to keep the state or near constant state.

The present invention has been made in view of the above-described problems of the prior art, and its object is to suppress the rapid increase in the attraction force acting on the plunger in the region where the gap between the stator and the plunger is small. It is an object of the present invention to provide an electromagnetic drive unit in which the region over which the plunger can be displaced can be expanded with a constant or near constant constant suction force.

In order to solve the problems described above, the present invention relates to a stator made of a magnetic material, a plunger made of a magnetic material, and a plunger coaxially arranged with respect to the stator, and a magnetic material, to the stator Is disposed coaxially and has a slide hole for slidably guiding the plunger, the stator, the plunger, and the yoke are disposed so as to surround the stator, and the stator is excited or demagnetized by feed control. The present invention is applied to an electromagnetic drive unit provided with a coil for moving a plunger closer to or away from the stator.

A feature of the present invention is provided at an end of the plunger on the stator side and provided at a magnetic pole part receiving magnetic force from the excited stator and at an end of the plunger opposite to the stator, the yoke A sliding contact portion for sliding contact with a sliding hole of the magnetic pole to deliver magnetism, a first edge provided on the outer peripheral edge of the magnetic pole portion on the stator side, and the stator, the plunger being directed to the stator side A cylindrical magnetic control unit having a bottomed hole whose open end is on the plunger side so that the magnetic pole unit moves inward when moving, and an outer peripheral surface of the cylindrical magnetic control unit are provided on the plunger side The magnetic pole portion is provided at a tapered portion gradually decreasing in diameter, and at a portion of the outer peripheral surface of the magnetic pole portion which is separated from the first edge opposite to the stator, and the magnetic pole portion has the cylindrical magnetic control portion And a second edge which enters the bottomed hole of the cylindrical magnetic control unit while moving the hole toward the stator side, the second edge being in the bottomed hole of the cylindrical magnetic control unit The magnetic sensor is configured to receive a magnetic force in a direction away from the stator with the open end of the cylindrical magnetic control unit when it enters.

According to the present invention, when the magnetic pole portion of the plunger receives the magnetic force (attracting force) from the stator, the magnetic pole portion of the plunger moves (approaches) in the cylindrical magnetic control portion of the stator toward the stator. Then, when the second edge provided on the outer peripheral surface of the magnetic pole part penetrates into the inside of the cylindrical magnetic control unit, the second edge is in a direction away from the stator with the opening end of the cylindrical magnetic control unit. It receives a magnetic force (attractive force). Thereby, in a region where the gap between the stator and the plunger approaches the minimum distance, the attraction force in the direction approaching the stator acting on the first edge of the magnetic pole portion is generated from the stator acting on the second edge of the magnetic pole portion It can be suppressed by the suction force in the direction of leaving. As a result, in the region where the gap between the stator and the plunger is reduced, it is possible to suppress the rapid increase in the attraction force acting on the plunger. Therefore, the region where the plunger can be displaced can be expanded while the suction force acting on the plunger is in a constant or nearly constant characteristic state.

FIG. 2 is a cross-sectional view showing the electromagnetic drive unit according to the first embodiment incorporated in a solenoid valve. It is an expanded sectional view which expands and shows principal parts, such as a stator in Drawing 1, a plunger, and a spacer. It is explanatory drawing which shows the attraction | suction force which acts on a magnetic flux line and a plunger in the state which has a plunger outside the cylindrical magnetic control part of a stator. It is explanatory drawing which shows the attraction | suction force which acts on a magnetic flux line and a plunger in the state which the plunger entered in the cylindrical magnetic control part of a stator. It is explanatory drawing which shows the suction | attraction force which acts on a magnetic flux line and a plunger in the state which the plunger contact | abutted to the spacer. It is a characteristic diagram which shows the relationship between displacement of a plunger, and the suction | attraction force which acts on a plunger. It is an expanded sectional view showing a stator, a plunger, a spacer, etc. by a 1st comparative example. It is an expanded sectional view showing the stator by the 2nd comparative example, a plunger, a spacer, etc. FIG. 7 is a cross-sectional view showing an electromagnetic drive unit according to a second embodiment incorporated in a solenoid valve. It is an expanded sectional view which expands and shows principal parts, such as a stator in FIG. 9, a plunger, and a spacer. FIG. 11 is an enlarged cross-sectional view similar to FIG. 10 showing the plunger according to a first variant; It is an expanded sectional view of the position similar to FIG. 2 which shows the stator (taper part) by a 2nd modification.

Hereinafter, a case where the electromagnetic drive unit according to the embodiment of the present invention is applied to a solenoid valve will be described in detail with reference to the accompanying drawings.

1 to 6 show a first embodiment of the present invention. In FIG. 1, the electromagnetic valve 1 is configured to include the electromagnetic drive unit 2 according to the first embodiment and a control valve unit 24 described later which is a driven device. The solenoid valve 1 is a 3-port 2-position pressure control valve that is switched by the electromagnetic drive unit 2. For example, tilt angle control of a variable displacement hydraulic pump / hydraulic motor, control of a spool of a control valve / throttling valve And the like.

First, the solenoid valve drive unit 2 will be described. The electromagnetic drive unit 2 has an inner housing 3 constituted by a stator 4, a yoke 8 and a ring 9 which will be described later. The stator 4, the yoke 8 and the ring 9 are coaxially arranged with the axial center OO of the stator 4. A solenoid assembly 14 described later is provided on the outer peripheral side of the inner housing 3, and power is supplied to a coil 16 described later constituting the solenoid assembly 14, whereby the plunger 5 described later is guided by the yoke 8 and the stator 4. It is configured to move in a direction (axial direction) along the axial center OO.

Here, the configuration of the stator 4 will be described. That is, the stator 4 is formed in a stepped cylindrical shape as a whole using a large-diameter magnetic material, and is excited or demagnetized (demagnetized) according to the power supply control for the coil 16. The stator 4 has a disk-shaped flange portion 4A, a cylindrical shape having a smaller diameter than the flange portion 4A, and a fixed iron core 4B protruding from the flange portion 4A toward the plunger 5 and a fixed iron core portion sandwiching the flange portion 4A. It includes a cylindrical mounting cylinder 4C that protrudes to the opposite side (the control valve unit 24 side) from 4B. An external thread 4D is formed on the outer peripheral surface of the mounting cylindrical portion 4C, and the external thread 4D is screwed to a valve casing 25 of the control valve unit 24, which will be described later. A pin insertion hole 4E penetrating in the axial direction is formed at an axial center position of the flange portion 4A and the fixed core portion 4B. On the outer peripheral surface of fixed iron core portion 4B on the plunger 5 side (the opposite flange portion 4A side), a small diameter outer peripheral surface 4F having a diameter smaller by one step than the outer peripheral surface of fixed iron core portion 4B is formed. , One end 9A of a ring 9 described later is fitted.

The cylindrical magnetic control unit 4G is provided at an end of the small diameter outer peripheral surface 4F on the plunger 5 side. As shown in FIG. 2, the cylindrical magnetic control unit 4G is formed as a cylindrical bottomed hole 4J in which the plunger 5 side is an open end 4H, and the bottomed hole 4J has a bottom 4J1. When the plunger 5 moves to the stator 4 side, a pole portion 5A described later enters into the bottomed hole 4J. A spacer mounting hole 4K slightly larger in diameter than the pin insertion hole 4E is formed coaxially with the pin insertion hole 4E at the axial center position of the bottom 4J1 of the cylindrical magnetic control unit 4G. Here, the axial length L1 of the cylindrical magnetic control unit 4G is expressed as an axial dimension from the open end 4H to the bottom 4J1 of the bottomed hole 4J.

The tapered portion 4L is provided on the outer peripheral surface on the opening end 4H side of the cylindrical magnetic control unit 4G. The tapered portion 4L is formed in a range from the open end 4H to the axial length L1 '. The outer peripheral surface of the tapered portion 4L gradually decreases in diameter toward the plunger 5. On the other hand, in the range from the bottom 4J1 to the axial length L1 ′ ′ of the outer peripheral surface of the cylindrical magnetic control unit 4G, the thickness (thickness) in the radial direction is uniform, and the small diameter outer peripheral surface of the fixed core portion 4B It is a cylindrical portion 4M having an outer diameter dimension equal to 4F.

Next, the configuration of the plunger 5 will be described. The plunger 5 is formed in a cylindrical shape as a whole using a magnetic material. The plunger 5 is disposed coaxially with the axial center OO of the stator 4. The plunger 5 approaches or separates from the stator 4 as the stator 4 is excited or demagnetized. The plunger 5 has a magnetic pole portion 5A and a sliding contact portion 5C which will be described later, and the outer diameter of the magnetic pole portion 5A is set larger than the outer diameter of the sliding contact portion 5C.

The magnetic pole portion 5A is provided on the side of the cylindrical magnetic control portion 4G on the stator 4 side of the plunger 5 and receives a magnetic force (attracting force) from the excited stator 4. The outer diameter dimension of the magnetic pole portion 5A is formed slightly smaller than the inner diameter dimension of the cylindrical magnetic control unit 4G of the stator 4, and can enter the bottomed hole 4J of the cylindrical magnetic control unit 4G. The stator side end surface 5B located on the stator 4 side of the magnetic pole portion 5A faces the bottom 4J1 of the bottomed hole 4J and abuts on a spacer 7 described later.

The sliding contact portion 5C is provided on the side (yoke 8 side) opposite to the stator 4 of the plunger 5. The sliding contact portion 5C is formed as a cylindrical body having an outer diameter smaller than that of the magnetic pole portion 5A. Here, the boundary between the magnetic pole portion 5A and the sliding contact portion 5C is a tapered surface 5D that gradually decreases in diameter from the outer peripheral surface of the magnetic pole portion 5A toward the outer peripheral surface of the sliding contact portion 5C. The sliding contact portion 5C is slidably fitted in a sliding hole 8D of the yoke 8 described later, and performs magnetic exchange with the yoke 8 while sliding on the sliding hole 8D.

A yoke-side end surface 5E located on the yoke 8 side of the sliding contact portion 5C faces the tip of a shaft-side male screw 10E of a screw 10 described later with a gap, and a sub spring 13 described later abuts. The outer peripheral surface of the plunger 5 is covered with a resin layer 5F made of a nonmagnetic material such as, for example, a fluorine-based resin with a uniform thickness. The thickness of the resin layer 5F is, for example, 0.03 mm to 0 in consideration of the sliding resistance between the inner peripheral surface of the sliding hole 8D of the yoke 8 and the sliding contact portion 5C and the durability of the resin layer 5F itself. It is set in the range of .2 mm. At an axial center position of the plunger 5, a central hole 5G penetrating in the axial direction is formed. Further, in the portion of the plunger 5 that is offset (decentered) in the radial direction from the center hole 5G, a through hole 5H penetrating in the axial direction is formed.

As shown in FIG. 2, the first edge 5J of the plunger 5 is an outer peripheral edge of the magnetic pole portion 5A on the stator 4 side, that is, a corner portion where the outer peripheral surface of the magnetic pole portion 5A and the stator side end surface 5B intersect. It is provided. The first edge 5J receives a magnetic force (attracting force) in a direction approaching the stator 4 from the cylindrical magnetic control unit 4G of the excited stator 4 (see FIGS. 3 to 5).

The second edge 5K of the plunger 5 is provided at a portion of the outer circumferential surface of the magnetic pole portion 5A that is spaced apart from the first edge 5J, that is, at the corner where the outer circumferential surface of the magnetic pole portion 5A intersects the tapered surface 5D. ing. When the second edge 5K intrudes into the bottomed hole 4J of the excited stator 4, the magnetic force (attracting force) in the direction of separating from the stator 4 with the open end 4H of the cylindrical magnetic control unit 4G. (See Figure 5).

Next, the configuration of the pin 6 and the spacer 7 will be described. First, the pin 6 is press-fitted into the center hole 5G of the plunger 5 and provided. The pin 6 is formed of a round bar material extending in the axial direction, and a midway portion thereof is press-fitted into the central hole 5G of the plunger 5. The pin 6 is thereby integrated with the plunger 5. One side (the stator 4 side) of the pin 6 in the axial direction is inserted into the pin insertion hole 4E of the stator 4 and the end thereof is in contact with a spool 29 described later. The other side (yoke 8 side) of the pin 6 in the axial direction extends into a through hole 8G described later of the yoke 8 and abuts on the tip of the shaft-side male screw 10E of the screw 10. The pin 6 axially presses the spool 29 by moving integrally with the plunger 5 in the axial direction.

The spacer 7 is provided between the stator 4 and the plunger 5. The spacer 7 regulates the axial minimum distance of the plunger 5 with respect to the stator 4. As shown in FIG. 2, the spacer 7 has a cylindrical portion 7A and an annular flange portion 7B larger in diameter than the cylindrical portion 7A, and the pin 6 is inserted into the inner peripheral side thereof. The cylindrical portion 7A of the spacer 7 is inserted into the spacer mounting hole 4K of the stator 4, and the flange portion 7B is in contact with the bottom 4J1 of the bottomed hole 4J of the stator 4. The flange portion 7B of the spacer 7 is sandwiched between the bottom 4J1 of the bottomed hole 4J and the stator side end surface 5B of the plunger 5. As a result, the plunger 5 does not directly abut on the bottom 4J1 of the bottomed hole 4J, and the axial minimum distance between the two when the stator side end surface 5B of the plunger 5 approaches the bottom 4J1 of the bottomed hole 4J The (interval) is regulated by the axial thickness dimension of the flange portion 7B of the spacer 7.

Here, as shown in FIG. 2, the axial length of the cylindrical magnetic control unit 4G of the stator 4 (the axial dimension from the open end 4H to the bottom 4J1 of the bottomed hole 4J) is L1. The distance (length in the axial direction) from the stator side end surface 5B to the second edge 5K is L2, and the axial minimum distance (thickness dimension of the flange portion 7B) between the stator 4 and the plunger 5 restricted by the spacer 7 is Assuming that L3, these L1, L2 and L3 are set to satisfy the following equation (1).

Further, the distance L2 is set so as to satisfy the following equation 2 with respect to the length L1.

Furthermore, the distance L3 is set so as to satisfy the following equation 3 with respect to the length L1.

Next, the configuration of the yoke 8, the ring 9, the screw 10, the sub spring 13 and the like will be described. First, the yoke 8 is disposed coaxially with the stator 4. The yoke 8 is formed in a stepped cylindrical shape using a magnetic material. Here, the yoke 8 includes a bottom 8A serving as a magnetic path, a cylindrical long cylindrical portion 8B axially extending from the outer peripheral side of the bottom 8A toward the stator 4, and the long cylindrical portion 8B sandwiching the bottom 8A. And a mounting cylindrical portion 8C projecting to the opposite side. The inner peripheral side of the long cylindrical portion 8B is a sliding hole 8D, and a sliding contact portion 5C of the plunger 5 is slidably fitted in the sliding hole 8D. That is, the slide hole 8D encloses the slide contact portion 5C of the plunger 5 to be cantilevered and guides the plunger 5 slidably in the axial direction.

At the end of the outer peripheral surface of the long cylindrical portion 8B of the yoke 8 on the stator 4 side, a small diameter outer peripheral surface 8E having a diameter smaller by one step than the outer peripheral surface of the long cylindrical portion 8B is formed. The other end 9B of the ring 9 is fitted to the small diameter outer peripheral surface 8E. On the other hand, a male screw 8F is formed on the outer peripheral surface of the mounting cylindrical portion 8C of the yoke 8, and a nut 21 described later is screwed on the male screw 8F. A through hole 8G penetrating in the axial direction is provided at the axial center position of the bottom 8A of the yoke 8 and the mounting cylinder 8C, and a female screw 8H is formed on the inner peripheral surface of the through hole 8G.

The ring 9 is provided between the outer periphery of the fixed core 4 B of the stator 4 and the long cylindrical portion 8 B of the yoke 8. The ring 9 is formed in a cylindrical shape using a magnetic material. One end 9A, which is one side (the stator 4 side) of the ring 9 in the axial direction, is fitted and fixed to the small diameter outer peripheral surface 4F of the stator 4. The other end 9B on the other side (yoke 8 side) of the ring 9 in the axial direction is fitted and fixed to the small diameter outer peripheral surface 8E of the yoke 8. Thus, an inner housing 3 in which the stator 4, the yoke 8 and the ring 9 are integrated is configured.

The screw 10 is provided in the through hole 8G of the yoke 8. The screw 10 is formed in a stepped cylindrical shape, and the screw 10 has a head 10A and a shaft 10B smaller in diameter than the head 10A. The shaft 10B is provided with two

flanges

10C and 10D spaced apart in the axial direction. A shaft-side male screw 10E is formed on the outer peripheral surface of the shaft 10B, and the shaft-side male screw 10E is screwed to the female screw 8H of the yoke 8. On the other hand, a head-side male screw 10F is formed on the outer peripheral surface of the head 10A, and the screw 10 is locked by screwing the lock nut 11 to the head-side male screw 10F. Further, an O-ring 12 for sealing oil in the inner housing 3 is provided between the collar portion 10C and the collar portion 10D.

The sub spring 13 is disposed in a state of being compressed between the tip end of the shaft-side male screw 10 E of the screw 10 and the yoke-side end face 5 E of the plunger 5. The sub spring 13 presses the yoke side end face 5E of the plunger 5 to the stator 4 side. Therefore, the pressing force of the plunger 5 by the sub spring 13 can be adjusted by rotating the screw 10 in the forward and reverse directions to adjust the amount of screwing into the yoke 8. That is, the screw 10 finely adjusts the driving force on the plunger 5 by the electromagnetic drive unit 2.

Next, the configuration of the solenoid assembly 14 will be described. The solenoid assembly 14 is provided so as to surround the inner housing 3 consisting of the stator 4, the yoke 8 and the ring 9 from the outside. The solenoid assembly 14 includes a bobbin 15, a coil 16, a terminal 17, an exterior mold 18, and a solenoid casing 20 which will be described later.

The bobbin 15 is provided on the outer peripheral side of the inner housing 3. The bobbin 15 has a cylindrical bobbin main body 15A fitted to the outer peripheral surface of the inner housing 3 and a pair of

wedge members

15B and 15C extending radially outward from both axial ends of the bobbin main body 15A. . The one wedge member 15B is provided with a projection 15D projecting in the direction away from the other wedge member 15C, and the wedge member 15C is provided with a projection 15E projecting in the direction away from the wedge member 15B.

The coil 16 is wound around the bobbin main body 15A of the bobbin 15 so as to surround the stator 4, the plunger 5 and the yoke 8 from the outside. The coil 16 is electrically connected to the terminal 17, and power is supplied to the coil 16 through the terminal 17. The coil 16 excites or demagnetizes (demagnetizes) the stator 4 by controlling power supply from the outside, and causes the plunger 5 to approach or separate from the stator 4.

The exterior mold 18 is provided to cover the coil 16 wound around the bobbin 15 and the

respective wedge members

15B and 15C of the bobbin 15 from the outer peripheral side. In this case, the exterior mold 18 covers the protrusion 15D of one wedge member 15B and the protrusion 15E of the other wedge member 15C. Thus, the exterior mold 18 envelops the entire bobbin 15 from the outside, and one side (stator 4 side) in the axial direction of the exterior mold 18 is engaged unevenly with the projection 15D of the wedge member 15B without clearance. The other side in the axial direction (yoke 8 side) is engaged with the projections 15E of the wedge member 15C without any gap.

An L-shaped bent socket 19 is integrally formed on one side in the axial direction of the exterior mold 18. A socket 19A is formed on the tip side of the socket 19 for inserting a plug (not shown), and the tip of the terminal 17 electrically connected to the coil 16 is disposed in the socket 19A. It is done. Therefore, by inserting a plug (not shown) into the insertion port 19A of the socket 19, power is supplied to the coil 16 from the outside through the terminal 17.

The solenoid casing 20 covers the exterior mold 18 from the outer peripheral side. The solenoid casing 20 has a cylindrical casing main body 20A extending in the axial direction, and a lid 20B projecting radially inward from the other axial side (yoke 8 side) of the casing main body 20A. One side (the stator 4 side) of the casing main body 20A in the axial direction is an open end 20C, and the open end 20C is fitted to the outer peripheral surface of the flange portion 4A of the stator 4.

On the other hand, a yoke fitting hole 20D penetrating in the axial direction is formed at the center of the lid 20B, and the outer peripheral surface of the bottom 8A of the yoke 8 is fitted in the yoke fitting hole 20D. In this state, the mounting cylindrical portion 8C of the yoke 8 protrudes to the outside of the lid portion 20B through the yoke fitting hole 20D. The solenoid casing 20 is fixed to the inner housing 3 by screwing the nut 21 onto the male screw 8F formed on the mounting cylindrical portion 8C.

The O-ring 22 is provided between the fixed core portion 4 B of the stator 4, the wedge member 15 B of the bobbin 15, and the exterior mold 18. The O-ring 23 is provided between the bottom 8 A of the yoke 8, the wedge member 15 C of the bobbin 15, and the exterior mold 18. These O-

rings

22 and 23 seal the gap between the inner housing 3 and the solenoid assembly 14 and also seal the interface between the

wedge members

15B and 15C of the bobbin 15 and the exterior mold 18, and the coil from the interface It is intended to suppress the infiltration of water to the 16 side.

Next, the control valve unit 24 which is a driven device attached to the electromagnetic drive unit 2 will be described. The control valve unit 24 is coaxially attached to the electromagnetic drive unit 2 and includes a valve casing 25 and a spool 29 which will be described later.

The valve casing 25 is formed in a stepped cylindrical shape (sleeve shape) and extends in the axial direction. The valve casing 25 is positioned between the small diameter cylindrical portion 25A positioned on one side in the axial direction, the large diameter cylindrical portion 25B positioned on the other side in the axial direction, and the small diameter cylindrical portion 25A and the large diameter cylindrical portion 25B. And an intermediate cylindrical portion 25C. The small diameter cylindrical portion 25A includes a supply port 25D connected to a hydraulic pump (not shown), an output port 25E connected to a hydraulic actuator (not shown), and a drain connected to a tank (not shown). A port 25F is provided. A seal surface 25G located between the supply port 25D and the output port 25E and a seal surface 25H located between the output port 25E and the drain port 25F are provided on the inner peripheral surface of the small diameter cylindrical portion 25A. There is. Further, a male screw 25J is formed on the outer peripheral surface of the intermediate cylindrical portion 25C, and a female screw 25K is formed on the inner peripheral surface of the large diameter cylindrical portion 25B. The control valve unit 24 is attached to the electromagnetic drive unit 2 by screwing the male screw 4D of the stator 4 (mounting cylinder 4C) to the female screw 25K of the valve casing 25.

Here, the valve casing 25 is disposed in a housing (not shown) having a plurality of flow paths separately connected to the three

ports

25D, 25E, 25F, and this housing is an external thread 25J of the intermediate cylindrical portion 25C. It is configured to be screwed on. The flow paths provided in the housing are isolated by O-

rings

26 and 27 fitted on the small diameter cylindrical portion 25A with the output port 25E interposed therebetween. Further, an O-ring 28 for sealing oil in the housing is provided at the boundary between the large diameter cylindrical portion 25B and the intermediate cylindrical portion 25C.

The spool 29 is axially movably provided on the inner peripheral side of the valve casing 25. A long rod-like body is used as the spool 29 and axially extends on the inner peripheral side of the valve casing 25. At the axial center position of the spool 29, a bottomed axial flow passage 29A extending in the axial direction is formed. An annular spring support plate 30 is attached to an outer peripheral surface of the spool 29 and at a boundary position between the intermediate cylindrical portion 25C of the valve casing 25 and the large diameter cylindrical portion 25B. The spring receiving plate 30 axially faces the spring receiving portion 25L formed on the inner peripheral side of the intermediate cylindrical portion 25C of the valve casing 25. A return spring 31 is provided between the spring receiving plate 30 of the spool 29 and the spring receiving portion 25L of the valve casing 25. Therefore, the spool 29 is always pressed to the stator 4 side by the biasing force of the return spring 31, and the end face of the spool 29 on the stator 4 side is in contact with the pin 6.

On the outer peripheral surface of the spool 29, four

lands

29B, 29C, 29D, 29E are provided so as to be separated in the axial direction. The

lands

29B and 29C have the same diameter, the

lands

29D and 29E have the same diameter, and the land 29C has a larger diameter than the land 29D. When the land 29C is in contact with the sealing surface 25G of the valve casing 25, the supply port 25D and the output port 25E are shut off. When the spool 29 moves in the axial direction and the land 29C is separated from the sealing surface 25G, the supply port 25D and the output port 25E communicate with each other. Thereby, the pressure oil supplied from the hydraulic pump (not shown) to the supply port 25D is led to the hydraulic actuator (not shown) through the output port 25E.

On the other hand, when the land 29D is in contact with the sealing surface 25H of the valve casing 25, the output port 25E and the drain port 25F are disconnected. When the spool 29 moves in the axial direction and the land 29D is separated from the sealing surface 25H, the output port 25E and the drain port 25F communicate with each other. Thus, the pressure oil supplied to the hydraulic actuator returns from the output port 25E to the tank (not shown) through the drain port 25F.

A plate 32 is disposed on the axial end face of the small diameter cylindrical portion 25A of the valve casing 25. The plate 32 is always pressed against the end face in the axial direction of the small diameter cylindrical portion 25A by a wave washer 33 provided between a wall surface (not shown) of the housing to which the valve casing 25 is attached. Thus, a damping chamber 34 is formed between the end surface of one side of the spool 29 in the axial direction and the plate 32. An orifice 35 is provided at one end of the spool 29 in the axial direction, and the axial flow passage 29 A of the spool 29 communicates with the damping chamber 34 via the orifice 35.

In the spool 29,

radial flow passages

29F and 29G penetrating in the radial direction are provided so as to be separated in the axial direction. The

radial flow passages

29F and 29G communicate with the axial flow passage 29A. Thus, the hydraulic oil in the tank (not shown) is led from the drain port 25F to the inner peripheral side of the valve casing 25 through the radial flow passage 29F, the axial flow passage 29A, and the radial flow passage 29G. The hydraulic oil introduced into the valve casing 25 is introduced into the cylindrical magnetic control unit 4G through the pin insertion hole 4E of the stator 4, and the hydraulic oil slides through the through hole 5H of the plunger 5 and the yoke 8 slides. It is introduced into the hole 8D. As described above, the hydraulic oil in the tank is configured to be filled in the inner housing 3 of the electromagnetic drive unit 2 through the inside of the spool 29 constituting the control valve unit 24. An O-ring 36 for sealing the hydraulic oil in the valve casing 25 is provided at a connection portion between the large diameter cylindrical portion 25B of the valve casing 25 and the attachment cylindrical portion 4C of the stator 4.

Next, a method of manufacturing the inner housing 3 constituting the electromagnetic drive unit 2 will be described.

First, in the first step of assembling the inner housing 3, the cylindrical portion 7A of the spacer 7 is press-fitted into the spacer mounting hole 4K of the stator 4, and the flange portion 7B of the spacer 7 is brought into contact with the bottom 4J1 of the bottomed hole 4J. Next, one end 9A of the ring 9 is press-fit into the small diameter outer peripheral surface 4F of the stator 4. In this state, the pin 6 pressed into the center hole 5G of the plunger 5 is inserted into the pin insertion hole 4E of the stator 4. Next, the small diameter outer peripheral surface 8E of the yoke 8 is press-fit into the other end 9B of the ring 9 while inserting the sliding contact portion 5C of the plunger 5 into the sliding hole 8D of the yoke 8. Thereby, the stator 4, the yoke 8, and the ring 9 are integrated in a state where the plunger 5 is accommodated in the inside of the yoke 8, and the inner housing 3 can be assembled.

Next, in the second step, the small diameter outer peripheral surface 8E of the yoke 8 and the other end 9B of the ring 9 are joined by butt welding. In the second step, in a state in which the inclination of the ring 9 with respect to the yoke 8 is corrected, the butt between the axial end face (step portion) of the small diameter outer peripheral surface 8E of the yoke 8 and the axial end face of the other end 9B of the ring 9 On the other hand, by performing laser welding over the entire circumference, the two are firmly joined.

Next, in the third step, the small diameter outer peripheral surface 4F of the stator 4 and the one end 9A side of the ring 9 are joined by lap welding. In the third step, the inclination or the like of the ring 9 press-fitted into the stator 4 is adjusted, and the inclination of the stator 4 with respect to the yoke 8 is corrected. In this state, laser welding is performed over the entire circumference of the overlapping portion of the small diameter outer peripheral surface 4F of the stator 4 and the one end 9A side of the ring 9 to firmly join the two. In this case, a weld line (not shown) formed at the joint between the small diameter outer peripheral surface 4F of the stator 4 and one end 9A of the ring 9 is closer to the flange 4A than the bottom 4J1 of the bottomed hole 4J of the stator 4 Formed at spaced locations.

Then, after the inner housing 3 is assembled, for example, the bobbin 15 on which the coil 16 is wound is assembled on the outer peripheral side of the inner housing 3. The coil 16 wound around the bobbin 15 and the

respective wedge members

15B and 15C of the bobbin 15 are covered with the exterior mold 18 from the outer peripheral side. Next, the exterior mold 18 is covered with the solenoid casing 20 from the outer peripheral side. Further, the open end 20C of the solenoid casing 20 (casing main body 20A) is fitted to the outer peripheral surface of the flange 4A of the stator 4, and the yoke fitting hole 20D of the lid 20B is fitted to the outer peripheral surface of the bottom 8A of the yoke 8. Match.

In this state, the solenoid casing 20 is fixed to the inner housing 3 by screwing the nut 21 onto the male screw 8F of the yoke 8 (mounting cylindrical portion 8C) protruding to the outside of the lid portion 20B. Next, the inner peripheral side of the sub spring 13 is inserted into the end of the pin 6 protruding into the through hole 8 G of the yoke 8, and the O ring 12 is attached between the

flanges

10 C and 10 D of the screw 10. In this state, the shaft-side male screw 10E of the screw 10 is screwed to the female screw 8H of the yoke 8 (through hole 8G). Then, with the end of the shaft-side male screw 10E in contact with the end of the pin 6, the head-side male screw 10F of the screw 10 is screwed with the lock nut 11 to make the screw 10 with respect to the yoke 8. Fix it. Thus, the electromagnetic drive unit 2 can be assembled.

The electromagnetic drive unit 2 according to the first embodiment has the above-described configuration. Hereinafter, the operation of the electromagnetic drive unit 2 and the control valve unit 24 will be described.

First, a plug (not shown) of the power supply device is connected to the socket 19 of the electromagnetic drive unit 2. In this case, the power supply may be either a DC power supply or an AC power supply, and power is supplied to the coil 16 from the power supply device via the terminal 17.

When power is not supplied to the coil 16, the spool 29 is biased toward the stator 4 by the return spring 31, and the end surface of the spool 29 on the stator 4 side is in contact with the pin 6. Therefore, the output port 25E of the valve casing 25 and the drain port 25F communicate with each other, and the output port 25E and the supply port 25D are maintained in the disconnected state (initial state).

When power is supplied to the coil 16 from the power supply unit through the terminal 17, a magnetic field (excitation force) is generated by the coil 16, and the plunger 5 draws the stator 4 with a suction force corresponding to the current value supplied to the coil 16. It is sucked into the fixed core portion 4B. At this time, the sliding contact portion 5C of the plunger 5 moves toward the stator 4 while being in sliding contact with the inner circumferential surface of the sliding hole 8D of the long cylindrical portion 8B of the yoke 8. Then, the plunger 5 stops at a position where the oil pressure acting on the spool 29, the spring force of the return spring 31 and the sub spring 13, and the suction force acting from the fixed core portion 4B are balanced.

The displacement of the plunger 5 is transmitted to the spool 29 via the pin 6, whereby the spool 29 moves in the valve casing 25. As a result, the supply port 25D of the valve casing 25 and the output port 25E are communicated or disconnected, and the output port 25E and the drain port 25F are communicated or interrupted, so that the supply and discharge of pressure oil from the hydraulic pump to the hydraulic actuator Is controlled. When the power supply to the coil 16 is stopped, the magnetic field due to the coil 16 disappears, and the spool 29 returns to the initial state by the spring force of the return spring 31. As a result, the output port 25E of the valve casing 25 and the drain port 25F communicate with each other, and the output port 25E and the supply port 25D are disconnected.

Here, an operation in which the stator 4 generates a suction force by power feeding to the coil 16 will be described.

First, when power is supplied to the coil 16 from the power supply device via the terminal 17, a magnetic field is generated by the coil 16. At this time, a magnetic flux is generated inside the stator 4, the plunger 5, the yoke 8 and the solenoid casing 20 which constitute a magnetic path. In this case, the cylindrical magnetic control unit 4G of the stator 4 constituting the magnetic path has a smaller volume than other magnetic path constituent members (plunger 5, yoke 8, solenoid casing 20). For this reason, the magnetic flux is concentrated in the cylindrical magnetic control unit 4G to have a high magnetic flux density, and the magnetization is promoted as compared with the magnetic paths of other portions. As a result, an attractive force (magnetic force) is generated between the plunger 5 and the stationary core portion 4B of the stator 4 including the cylindrical magnetic control unit 4G according to Coulomb's law concerning magnetism. The suction force has an axial component, and this axial component acts as an axial suction force that sucks the plunger 5 toward the stator 4 in the axial direction.

Here, the relationship between the position of the plunger 5 with respect to the stator 4 and the suction force acting on the plunger 5 will be described with reference to FIGS. 3 to 5. The stator 4, the plunger 5 and the spacer 7 illustrated in FIGS. 3 to 5 are not hatched to clearly show the magnetic flux lines.

First, when the plunger 5 is at the initial position shown in FIG. 3, that is, when the first edge 5J of the magnetic pole portion 5A is at the same position as the open end 4H of the cylindrical magnetic control portion 4G of the stator 4 in the axial direction, A magnetic flux indicated by a plurality of magnetic flux lines 37 in FIG. 3 is generated for the stator 4. The magnetic flux lines 37 at the initial position are obliquely directed from the outer peripheral surface of the magnetic pole portion 5A, the first edge 5J and the stator side end surface 5B toward the tip of the tapered portion 4L formed on the outer peripheral surface of the cylindrical magnetic control portion 4G. Extend. Therefore, the suction force F1 acting on the plunger 5 extends in the direction inclined with respect to the axial direction along the direction of the magnetic flux lines 37. The plunger 5 is displaced in the direction approaching the stator 4 by an axial attraction force Fx1 which is an axial component of the attraction force F1, and the displacement of the plunger 5 in the axial direction becomes the driving force of the spool 29.

When the plunger 5 is attracted to the stator 4, the plunger 5 is in the middle position shown in FIG. 4, that is, the first edge 5J of the magnetic pole portion 5A enters the inside of the cylindrical magnetic control portion 4G (in the bottomed hole 4J). Displace to position. At the intermediate position in FIG. 4, the area magnetized by the cylindrical magnetic control unit 4G increases in the radial direction as the diameter of the outer peripheral surface of the tapered portion 4L increases. Thereby, the direction of the magnetic flux line 37 shown in FIG. 4 is inclined in the radial direction as compared with the initial position shown in FIG. 3, and the inclination with respect to the axial direction of the suction force F2 acting on the plunger 5 is the suction force at the initial position. It becomes larger than the inclination of F1. On the other hand, the attraction force F2 becomes larger than the attraction force F1 at the initial position due to the increase of the magnetization area of the cylindrical magnetic control unit 4G. As a result, the axial suction force Fx2 which is an axial component of the suction force F2 has a value equivalent to or close to the axial suction force Fx1 at the initial position (Fx2 ≒ Fx1).

When the plunger 5 is further attracted to the stator 4, the plunger 5 is displaced to the restricted position shown in FIG. 5, that is, the position where the stator side end face 5B of the plunger 5 abuts on the flange 7B of the spacer 7. Thereby, the gap between the stator 4 and the plunger 5 becomes the minimum distance regulated by the spacer 7. At this time, since the first edge 5J of the magnetic pole portion 5A is displaced from the tapered portion 4L of the cylindrical magnetic control portion 4G to the inner peripheral side of the cylindrical portion 4M, the region magnetized by the cylindrical magnetic control portion 4G is Further increase in the radial direction. Thereby, the direction of the magnetic flux lines 37 shown in FIG. 5 is further inclined in the radial direction compared to the intermediate position shown in FIG. 4 and the inclination with respect to the axial direction of the suction force F3 acting on the plunger 5 is the suction at the intermediate position. It becomes larger than the inclination of force F2. On the other hand, since the plunger 5 comes closest to the stator 4, the suction force F3 acting on the plunger 5 is larger than the suction force F2 at the intermediate position.

Here, in the present embodiment, the axial length L1 of the cylindrical magnetic control unit 4G of the stator 4, the distance L2 from the stator side end surface 5B of the plunger 5 to the second edge 5K, and the flange portion of the spacer 7 The thickness dimension L3 of 7B is configured to satisfy the relationship of L1 <L2 + L3. Therefore, while the plunger 5 is displaced toward the restricted position, the second edge 5K of the magnetic pole 5A intrudes into the cylindrical magnetic control unit 4G of the stator 4 (in the bottomed hole 4J).

In this state, magnetic flux is generated diagonally from the second edge 5K toward the opening end 4H between the second edge 5K of the magnetic pole portion 5A and the opening end 4H of the cylindrical magnetic control unit 4G. For this reason, a suction force F4 directed toward the opening end 4H acts on the second edge 5K while inclining with respect to the axial direction. The axial suction force Fx4, which is an axial component of the suction force F4, acts in the direction to move the plunger 5 away from the spacer 7, and therefore, it is opposite to the axial suction force Fx3 which is an axial component of the suction force F3. It becomes the direction. Therefore, a part of the axial attraction force Fx3 acting in the direction of causing the plunger 5 to approach the stator 4 is canceled by the axial attraction force Fx4 acting in the direction of separating the plunger 5 from the stator 4. As a result, in a region where the plunger 5 approaches the restricted position, the axial suction force (Fx3-Fx4) acting on the plunger 5 is divided into an axial suction force Fx1 at the initial position and an axial suction force Fx2 at the intermediate position. It is possible to make the same value or a value close to the same value (Fx3-Fx4 ≒ Fx2).

Therefore, when the feed current supplied to the coil 16 is set to a constant value, as shown by the characteristic line 38 in FIG. 6, the plunger 5 is at the initial position P1 shown in FIG. While being displaced to the restricted position P3 shown in FIG. 5, the axial suction force Fx acting on the plunger 5 can be maintained at a substantially constant value. As a result, when the gap between the plunger 5 and the stator 4 approaches the minimum distance regulated by the spacer 7, the axial attraction force Fx acting on the plunger 5 is prevented from rapidly increasing. it can. Therefore, it is possible to secure a large area where the plunger 5 can be displaced, that is, the area A from P1 to P3 in FIG. 6 while the axial suction force Fx acting on the plunger 5 is constant or nearly constant.

Here, the distance L2 from the stator side end face 5B of the plunger 5 to the second edge 5K is 0.5L1 ≦ the axial length L1 of the cylindrical magnetic control unit 4G (bottomed hole 4J) of the stator 4 It is set in the range of L2 ≦ 0.7 L1. Therefore, by adjusting the distance L2 within this range, the size of the region (region A in FIG. 6) in which the plunger 5 can be displaced while the axial suction force Fx acting on the plunger 5 is constant or nearly constant. Can be adjusted appropriately. In this case, when the distance L2 is smaller than 0.5L1 (L2 <0.5L1), the second edge 5K of the magnetic pole portion 5A is at a stage before the stator side end surface 5B of the plunger 5 approaches the stator 4. It will intrude into the bottomed hole 4J. Therefore, before the axial attraction force Fx for causing the plunger 5 to approach the stator 4 increases, the axial attraction force Fx for separating the plunger 5 from the stator 4 acts on the plunger 5. As a result, the region in which the plunger 5 can be displaced is narrowed while the axial suction force Fx acting on the plunger 5 is constant or nearly constant.

On the other hand, when the distance L2 is larger than 0.7L1 (L2> 0.7L1), the second edge 5K of the magnetic pole portion 5A has a bottom until just before the stator side end surface 5B of the plunger 5 abuts the spacer 7 There is no intrusion into the hole 4J. Therefore, the timing at which the axial suction force Fx for separating the plunger 5 from the spacer 7 is generated is delayed. As a result, the region in which the plunger 5 can be displaced is narrowed while the axial suction force Fx acting on the plunger 5 is constant or nearly constant. Therefore, the distance L2 is preferably set in the range of 0.5L1 ≦ L2 ≦ 0.7L1 with respect to the length L1.

Here, the difference between the plunger 5 according to the present embodiment and the plunger according to the comparative example will be described.

As shown in FIG. 7, in the plunger 101 according to Comparative Example 1, a tapered surface 101C is formed at the boundary between the magnetic pole portion 101A and the sliding contact portion 101B, and the angle at which the outer peripheral surface of the magnetic pole portion 101A intersects with the stator side end face 101D. The portion is the first edge 101E, and the corner at which the outer peripheral surface of the magnetic pole portion 101A and the tapered surface 101C intersect is the second edge 101F. In this case, the second edge 101F is positioned outside the bottomed hole 4J in the restricted position where the stator side end face 101D of the plunger 101 is in contact with the flange portion 7B of the spacer 7 in the bottomed hole 4J of the stator 4. It has become. For this reason, the plunger 101 according to Comparative Example 1 has the plunger 101 between the second edge 101F and the open end 4H of the cylindrical magnetic control unit 4G even when the stator side end face 101D approaches the restricted position. Suction does not act in the direction of moving away from

As shown in FIG. 8, in the plunger 102 according to Comparative Example 2, the magnetic pole portion 102A and the sliding contact portion 102B are formed in a cylindrical shape having the same external dimensions. Therefore, although the plunger 102 according to Comparative Example 2 has the first edge 102D at the corner where the outer peripheral surface of the magnetic pole 102A intersects with the stator side end surface 102C, a portion corresponding to the second edge 5K according to the first embodiment Is not provided. For this reason, even in a state in which the stator side end surface 102C approaches the regulated position where the stator side end surface 102C abuts on the flange portion 7B of the spacer 7, the plunger 102 according to Comparative Example 2 has a suction force in the direction of separating the plunger 102 from the stator 4 It does not work.

Therefore, in the electromagnetic drive unit using the plunger 101 according to Comparative Example 1, as shown by the characteristic line 39 in FIG. 6, while the plunger 101 is displaced from the initial position P1 to the intermediate position P2, the plunger 101 The axial suction force Fx acting in the direction to approach 4 is in a state of being constant or nearly constant. However, while the plunger 101 is displaced from the intermediate position P2 to the restricting position P3, the axial attraction force Fx acting in the direction to make the plunger 101 approach the spacer 7 rapidly increases. As a result, the region where the plunger 101 can be displaced while the axial suction force Fx acting on the plunger 101 is constant or nearly constant becomes a narrow region a from P1 to P2 in FIG. On the other hand, also in the electromagnetic drive unit using the plunger 102 according to the comparative example 2, as in the comparative example 1, the relationship between the displacement of the plunger 102 and the axial suction force Fx acting on the plunger 102 is as shown in FIG. It becomes as shown by the characteristic line 39.

Thus, in the electromagnetic drive unit 2 according to the first embodiment, the area where the plunger 5 can be displaced is expanded while the axial suction force Fx acting on the plunger 5 is constant or nearly constant. The change in suction force due to the displacement of the plunger 5 is reduced. Therefore, in the electromagnetic valve 1 provided with the electromagnetic drive unit 2, the suction force for the plunger 5 necessary to balance the oil pressure acting on the spool 29 and the spring force of the return spring 31 and the sub spring 13 is It is possible to control with high accuracy by the feed control. Therefore, when the solenoid valve 1 provided with the solenoid drive unit 2 is used, for example, in a hydraulic system that performs tilt angle control of a variable displacement hydraulic pump / hydraulic motor, control of a spool of a control valve, etc. Can improve the control accuracy of the hydraulic system.

Moreover, in the solenoid valve 1 provided with the solenoid drive unit 2, the control valve unit is expanded by expanding the region in which the plunger 5 can be displaced while the axial suction force Fx acting on the plunger 5 is constant or nearly constant. The stroke of the spool 29 in the 24 valve casings 25 can be increased. Thereby, for example, the maximum opening amount between the supply port 25D and the output port 25E and the maximum opening amount between the output port 25E and the drain port 25F can be set large. The supply port 25D, the output port 25E , And the flow rate of the hydraulic fluid flowing through the drain port 25F can be increased. As a result, the response of the oil pressure by the solenoid valve 1 can be sped up, and the response of the hydraulic system including the solenoid valve 1 can be sped up.

Next, FIGS. 9 and 10 show a second embodiment of the present invention. The second embodiment is characterized in that the outer diameter of the magnetic pole portion of the plunger and the sliding contact portion is the same diameter, and the outer peripheral surface of the plunger is provided with a constricted portion for axially separating the magnetic pole portion and the sliding contact portion. To be In the second embodiment, the same reference symbols are given to the same configuration elements as the first embodiment, and the description thereof is omitted.

In the figure, the electromagnetic drive unit 41 constitutes a solenoid valve together with the control valve unit 24. Similar to the electromagnetic drive unit 2 according to the first embodiment, the electromagnetic drive unit 41 includes a stator 4, a plunger 42 described later, pins 6, spacers 7, yokes 8, rings 9, bobbins 15, coils 16, A solenoid casing 20 and the like are included. However, in the second embodiment, the configuration of the plunger 42 is different from that of the plunger 5 according to the first embodiment.

The plunger 42 is formed in a cylindrical shape as a whole using a magnetic material, and is disposed coaxially with the stator 4. The plunger 42 has the same outer diameter as the outer diameter of the magnetic pole portion 42A, which will be described later, and the outer diameter of the sliding portion 42C, and the outer peripheral surface of the plunger 42 is provided with a narrowed portion 42G, which will be described later.

The magnetic pole portion 42A is provided at an end of the plunger 42 on the stator 4 side. The outer diameter of the magnetic pole portion 42A is formed to be slightly smaller than the inner diameter of the cylindrical magnetic control portion 4G (the bottomed hole 4J) of the stator 4, and the magnetic pole portion 42A enters the inside of the bottomed hole 4J. The stator side end face 42B of the magnetic pole part 42A faces the bottom 4J1 of the bottomed hole 4J and abuts on the flange 7B of the spacer 7.

The sliding contact portion 42C is provided at an end of the plunger 42 on the opposite side (yoke 8 side) to the stator 4. The sliding contact portion 42C is slidably inserted in the sliding hole 8D of the yoke 8, and performs magnetic exchange with the yoke 8 while slidingly contacting the sliding hole 8D. The yoke-side end surface 42D of the sliding contact portion 42C faces the tip of the shaft-side male screw 10E of the screw 10, and the sub-spring 13 is in contact. A central hole 42E penetrating in the axial direction is formed at an axial center position of the plunger 42, and a pin 6 is press-fitted into the central hole 42E. Further, a through hole 42F penetrating in the axial direction is formed in a portion of the plunger 42 which is eccentric in the radial direction from the central hole 42E.

The constricted portion 42G is formed on the outer peripheral surface of the plunger 42 in the form of a recessed groove all around, and axially separates the magnetic pole portion 42A and the sliding contact portion 42C. The plunger 42 has a pole portion 42A on the stator 4 side and a sliding contact portion 42C on the yoke 8 side with respect to the constriction portion 42G. As shown in FIG. 10, the first edge 42H of the plunger 42 is provided at a corner where the outer peripheral surface of the magnetic pole portion 42A and the stator side end surface 42B intersect. The first edge 42H receives a magnetic force (attracting force) in a direction approaching the stator 4 from the cylindrical magnetic control unit 4G of the excited stator 4.

The second edge 42J of the plunger 42 is provided at a portion of the outer circumferential surface of the magnetic pole portion 42A that is separated from the first edge 42H, that is, at the corner where the outer circumferential surface of the magnetic pole portion 42A intersects with the narrowed portion 42G. ing. The second edge 42J receives a magnetic force (attracting force) in a direction away from the stator 4 from the cylindrical magnetic control unit 4G when it enters the bottomed hole 4J of the excited stator 4.

Here, the axial length of the cylindrical magnetic control unit 4G (the bottomed hole 4J) of the stator 4 is L1, and the distance from the stator side end surface 42B of the plunger 42 to the second edge 42J is L2. Assuming that the thickness dimension of the flange portion 7B is L3, these L1, L2 and L3 are the number 1 (L1> L2 + L3), the number 2 (0.5 L1 ≦ L2 ≦ 0.7 L1), the number 3 (L3 = 0) .2L1) is set to satisfy the relationship.

The electromagnetic drive unit 41 according to the second embodiment is provided with the plunger 42 as described above, and by performing power supply control on the coil 16, a suction force acts on the plunger 42 from the stator 4.

Here, after the first edge 42H of the plunger 42 enters the bottomed hole 4J of the stator 4, the first edge of the first embodiment is performed until the second edge 42J of the plunger 42 intrudes into the bottomed hole 4J. Similar to the embodiment, an axial suction force acts on the plunger 42 in a direction approaching the stator 4. When the second edge 42J of the plunger 42 intrudes into the bottomed hole 4J, a magnetic force (attracting force) is generated between the second edge 42J and the open end 4H of the cylindrical magnetic control unit 4G, and the plunger 42 is An axial suction force acts in a direction away from the stator 4. As a result, it is possible to cancel out a part of the axial attraction force that causes the plunger 42 to approach the stator 4. As a result, when the gap between the plunger 42 and the stator 4 approaches the minimum distance regulated by the spacer 7, it is possible to suppress the rapid increase in the axial attraction force acting on the plunger 42. . Therefore, as in the first embodiment, the region in which the plunger 42 can be displaced can be expanded while the axial suction force acting on the plunger 42 is constant or nearly constant.

In the second embodiment, a neck 42G is formed on the outer peripheral surface of the plunger 42 made of a magnetic material, and the pole 42A and the sliding contact 42C are axially separated by the neck 42G. ing. However, the present invention is not limited thereto. For example, as in the first modified example shown in FIG. 11, the annular member 43 made of nonmagnetic material is embedded in the constriction portion 42G to have uniform outer diameter dimension. It may be formed as a plunger 42 '.

Further, in the embodiment, the case where the tapered portion 4L linearly extending while reducing the diameter toward the opening end 4H is provided on the outer peripheral surface of the cylindrical magnetic control unit 4G of the stator 4 is excited. However, the present invention is not limited to this. For example, as in the second modified example shown in FIG. 12, a tapered portion 4L 'extending in a curving manner while reducing the diameter toward the opening end 4H may be provided.

2, 41 electromagnetic drive unit 4 stator 4G cylindrical magnetic control unit 4H

open end

4L, 4L '

taper portion

5, 42

plunger

5A, 42A

magnetic pole portion

5B, 42B stator side end face 5C, 42C sliding

contact portion

5J,

42H Edge

5K, 42J Second Edge 7 Spacer 8 Yoke 8D Sliding Hole 16 Coil 42G Neck Part

Claims

A stator made of a magnetic material,
A plunger made of a magnetic material and coaxially arranged with respect to the stator;
A yoke made of a magnetic material and coaxially arranged with respect to the stator and having a slide hole slidably guiding the plunger;
An electromagnetic drive unit comprising: a stator disposed so as to surround the stator, the plunger, and the yoke, and a coil for exciting or demagnetizing the stator by power supply control to move the plunger toward or away from the stator.
A pole portion provided at an end of the plunger on the stator side and receiving a magnetic force from the excited stator;
A sliding contact portion provided at an end of the plunger opposite to the stator and in sliding contact with a sliding hole of the yoke to transfer magnetism;
A first edge provided on an outer peripheral edge of the magnetic pole portion on the stator side;
A cylindrical magnetic control unit provided in the stator and having a bottomed hole whose open end is the open end so that the magnetic pole portion enters inward when the plunger moves toward the stator;
A tapered portion provided on an outer peripheral surface of the cylindrical magnetic control unit and having a gradually smaller diameter toward the plunger;
The magnetic pole portion is provided on a portion of the outer peripheral surface of the magnetic pole portion that is separated from the first edge on the opposite side to the stator, and the magnetic pole portion moves the bottomed hole of the cylindrical magnetic control portion toward the stator And a second edge which intrudes into the bottomed hole of the cylindrical magnetic control unit,
The second edge is configured to receive a magnetic force in a direction away from the stator with the open end of the cylindrical magnetic control unit when it enters the bottomed hole of the cylindrical magnetic control unit. An electromagnetic drive unit characterized by
A spacer is provided between the stator and the plunger for restricting an axial minimum distance therebetween.
Let the axial length of the cylindrical magnetic control unit be (L1), let the distance between the stator side end face of the plunger facing the stator and the second edge be (L2), and restrict by the spacer The sum of the distances (L2 + L3) is smaller than the length (L1) of the cylindrical magnetic control unit, where (L3) is the axial minimum distance between the stator and the plunger. The electromagnetic drive unit according to claim 1, wherein
The distance (L2) between the stator side end face of the plunger and the second edge is 0.5L1 ≦ L2 ≦ 0.7L1 with respect to the axial length (L1) of the cylindrical magnetic control unit. Is set
The electromagnetic drive unit according to claim 2, wherein a minimum axial distance (L3) between the stator and the plunger, which is regulated by the spacer, is set to L3 = 0.2L1.
The electromagnetic drive unit according to claim 1, wherein the outer diameter of the magnetic pole portion is larger than the outer diameter of the sliding contact portion.
The outer diameters of the magnetic pole portion and the sliding contact portion are the same diameter, and a neck portion separating the magnetic pole portion and the sliding contact portion in the axial direction is provided on the outer peripheral surface of the plunger. The electromagnetic drive unit according to claim 1.