JP6571898B2 - Electromagnetic drive unit - Google Patents

Description

  The present invention relates to an electromagnetic drive unit suitably used for, for example, an electromagnetic proportional hydraulic control valve constituting a hydraulic circuit of a construction machine.

  In recent years, construction machines represented by hydraulic excavators have often adopted electronic control devices 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 operated by an operating 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 (feeding current value) of a control signal supplied from a controller or the like. . In this electromagnetic drive unit, a stator (fixed iron core) and a plunger (movable iron core) are coaxially arranged. By performing power feeding control on a solenoid coil arranged so as to surround the stator and the plunger, The amount of excitation is variably controlled. Since a suction force according to the amount of excitation of the stator acts between the stator and the plunger, a driving object such as a valve body can be driven using this suction force as a driving force.

  Here, in a hydraulic control valve using an electromagnetic drive unit, the elastic force and oil pressure of the spring acting on the valve body are balanced with the drive force of the electromagnetic drive unit, and the valve body is adjusted according to the balance load. It is the structure which adjusts the opening amount of an oil path by displacing. Therefore, in order to perform more accurate hydraulic control, the driving force output from the electromagnetic drive unit, that is, the attraction force acting between the stator and the plunger is the power supply current value supplied to the electromagnetic drive unit. It is desirable to rely only on it. That is, it is desirable that the suction force acting between the stator and the plunger is 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 made of a concave portion having a tapered surface that gradually increases in diameter toward the plunger is provided at an end portion of the stator that faces the plunger, and is more cylindrical on the plunger side than the first suction portion. There has been proposed an electromagnetic drive unit provided with a second suction part, and formed so that the inner peripheral surface of the second suction part is continuous with the recess of the first suction part (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 taper surface formed in the outer periphery of the end portion on the stator side of the plunger faces the taper surface formed in the recess of the first suction portion of the stator, the suction force is mainly the first force 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, the 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. To do. Therefore, the electromagnetic drive unit according to Patent Document 1 can suppress a decrease in attraction force even in a state where the gap between the stator and the plunger is large, and the space between the stator and the plunger is independent of the position of the plunger with respect to the stator. The suction force acting on the can be kept almost constant.

JP 2000-277327 A

  However, in the electromagnetic drive unit according to Patent Document 1, when the plunger is attracted to the stator and the gap between them is further reduced, the attracting force generated between the plunger and the stator increases rapidly. For this reason, for example, in a region where the gap between the plunger and the stator is close to the minimum value, even if the power supply current value supplied to the electromagnetic drive unit is constant, the attractive force between the plunger and the stator is constant. There is a problem that it is difficult to maintain a state or a state close to constant.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to suppress a sudden increase in suction force acting on the plunger in a region where the gap between the stator and the plunger becomes small. It is an object of the present invention to provide an electromagnetic drive unit that can widen a region in which a plunger can be displaced while a suction force acting on is constant or nearly constant.

  In order to solve the above-described problems, the present invention provides a stator made of a magnetic material, a plunger made of a magnetic material, arranged coaxially with respect to the stator, and made of a magnetic material. Arranged on the same axis and having a sliding hole for slidably guiding the plunger, and arranged so as to surround the stator, the plunger and the yoke, and energizing or demagnetizing the stator by power supply control. The present invention is applied to an electromagnetic drive unit including a coil that moves a plunger toward or away from the stator.

A feature of the present invention is that the plunger is provided at an end of the plunger on the stator side, receives a magnetic force from the excited stator, and is provided at an end of the plunger opposite to the stator, the yoke A sliding contact portion that slides in contact with the sliding hole of the magnetic pole portion and transfers magnetism, a first edge provided on an outer peripheral edge of the magnetic pole portion on the stator side, and provided on the stator, facing a stator side end surface of the plunger A cylindrical magnetic control portion formed as a bottomed hole having an opening end on the plunger side, and provided on an outer peripheral surface of the cylindrical magnetic control portion, and gradually becomes smaller in diameter toward the plunger side. and a tapered portion, at a site from said stator from said first edge spaced opposite side of the outer peripheral surface of the pole portion, the tube when entering the blind hole of the cylindrical magnetic control unit Type And second edge is provided for receiving a magnetic force in a direction away from said stator between said open end of the air control unit, regulating the axial minimum distance between them between the said stator plunger The axial length of the cylindrical magnetic control unit is (L1), the distance between the stator side end surface of the plunger and the second edge is (L2), and the spacer When the minimum axial distance between the restricted stator and the plunger is (L3), the sum of the distances (L2 + L3) is smaller than the length (L1) of the cylindrical magnetic control unit. is there.

  According to the present invention, when the magnetic pole part of the plunger receives a magnetic force (attraction force) from the stator, the magnetic pole part of the plunger moves (approaches) in the cylindrical magnetic control part of the stator toward the stator side. And if the 2nd edge provided in the outer peripheral surface of a magnetic pole part penetrate | invades inside a cylindrical magnetic control part, a 2nd edge will be in the direction away from a stator between the opening ends of a cylindrical magnetic control part. Receives magnetic force (attraction force). As a result, in the region where the gap between the stator and the plunger approaches the minimum distance, the attractive force in the direction approaching the stator acting on the first edge of the magnetic pole portion is applied 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 becomes small, it is possible to suppress a sudden increase in the suction force acting on the plunger. Accordingly, it is possible to widen the region in which the plunger can be displaced while the suction force acting on the plunger is constant or nearly constant.

It is sectional drawing shown in the state which integrated the electromagnetic drive unit by 1st Embodiment in the solenoid valve. It is an expanded sectional view which expands and shows principal parts, such as a stator in FIG. 1, a plunger, a spacer. It is explanatory drawing which shows the attraction 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 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 the stator. It is explanatory drawing which shows the 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 the displacement of a plunger, and the attraction | suction force which acts on a plunger. It is an expanded sectional view showing the stator, plunger, spacer, etc. by the 1st comparative example. It is an expanded sectional view showing the stator, plunger, spacer, etc. by the 2nd comparative example. It is sectional drawing shown in the state which integrated the electromagnetic drive unit by 2nd Embodiment in the solenoid valve. It is an expanded sectional view which expands and shows principal parts, such as a stator in FIG. 9, a plunger, a spacer. It is an expanded sectional view of the same position as Drawing 10 showing the plunger by the 1st modification. It is an expanded sectional view of the same position as Drawing 2 showing the stator (taper part) by the 2nd modification.

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

  1 to 6 show a first embodiment of the present invention. In FIG. 1, an electromagnetic valve 1 includes an electromagnetic drive unit 2 according to the first embodiment and a control valve unit 24, which will be described later, which is a driven device. The solenoid valve 1 is a three-port two-position pressure control valve that is switched by an electromagnetic drive unit 2. For example, the tilt angle control of a variable displacement hydraulic pump / hydraulic motor, the control valve spool / throttle valve control, etc. It is used suitably for etc.

  First, the electromagnetic 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 described later. The stator 4, the yoke 8 and the ring 9 are arranged coaxially with the axis OO of the stator 4. A solenoid assembly 14 which will be described later is provided on the outer peripheral side of the inner housing 3, and power to a coil 16 which will be described later constituting the solenoid assembly 14 is supplied with power, whereby the plunger 5 which will be described later is guided to the yoke 8 while being guided by the yoke 8. It is the structure which moves to the 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) in accordance with power supply control for the coil 16. The stator 4 has a disk-shaped flange portion 4A, a columnar shape having a smaller diameter than the flange portion 4A, a fixed core 4B protruding from the flange portion 4A toward the plunger 5, and a fixed core portion sandwiching the flange portion 4A. 4C includes a cylindrical mounting cylinder portion 4C protruding to the opposite side (control valve unit 24 side) to 4B. A male screw 4D is formed on the outer peripheral surface of the mounting cylinder portion 4C, and this male screw 4D is screwed to a valve casing 25 described later of the control valve unit 24. A pin insertion hole 4E penetrating in the axial direction is formed at the axial center position of the flange portion 4A and the fixed iron core portion 4B. A small-diameter outer peripheral surface 4F having a smaller diameter than the outer peripheral surface of the fixed iron core portion 4B is formed on the outer peripheral surface of the fixed iron core portion 4B on the plunger 5 side (counter flange portion 4A side). The one end 9A of the ring 9 described later is fitted.

  The cylindrical magnetic control unit 4G is provided at the 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 having an opening end 4H on the plunger 5 side, and the bottomed hole 4J has a bottom portion 4J1. A magnetic pole portion 5A described later enters the bottomed hole 4J when the plunger 5 moves to the stator 4 side. A spacer mounting hole 4K having a slightly larger 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 taper portion 4L is provided on the outer peripheral surface of the cylindrical magnetic control portion 4G on the opening end 4H side. The tapered portion 4L is formed in a range from the opening end 4H to the axial length L1 ′. The outer peripheral surface of the taper portion 4 </ b> L gradually decreases in diameter toward the plunger 5. On the other hand, in the outer peripheral surface of the cylindrical magnetic control unit 4G, the range from the bottom 4J1 to the axial length L1 ″ has a uniform radial thickness (wall thickness), and the small-diameter outer peripheral surface of the fixed iron core portion 4B. The cylindrical portion 4M has an outer diameter 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 arranged coaxially with the axis OO of the stator 4. The plunger 5 approaches or separates from the stator 4 when the stator 4 is excited or demagnetized. The plunger 5 has a magnetic pole part 5A and a sliding contact part 5C, which will be described later, and the outer diameter dimension of the magnetic pole part 5A is set larger than the outer diameter dimension of the sliding contact part 5C.

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

  The slidable contact portion 5C is provided on the opposite side (yoke 8 side) of the plunger 5 from the stator 4. The sliding contact portion 5C is formed as a cylindrical body having a smaller outer diameter than the magnetic pole portion 5A. Here, the boundary portion between the magnetic pole portion 5A and the sliding contact portion 5C is a tapered surface 5D having a gradually decreasing diameter from the outer peripheral surface of the magnetic pole portion 5A toward the outer peripheral surface of the sliding contact portion 5C. The slidable contact portion 5C is slidably inserted into a sliding hole 8D of the yoke 8 to be described later, and exchanges magnetism with the yoke 8 while slidably contacting the sliding hole 8D.

  A yoke-side end surface 5E located on the yoke 8 side of the sliding contact portion 5C faces a tip of a shaft-side male screw 10E of the screw 10 described later with a gap, and a sub-spring 13 described later contacts. The outer peripheral surface of the plunger 5 is covered with a uniform thickness by a resin layer 5F made of a nonmagnetic material such as a fluorine-based resin. 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. A central hole 5G penetrating in the axial direction is formed at the axial center position of the plunger 5. A through hole 5H penetrating in the axial direction is formed in a portion of the plunger 5 that is displaced (eccentric) from the center hole 5G in the radial direction.

  As shown in FIG. 2, the first edge 5J of the plunger 5 is an outer peripheral edge on the stator 4 side of the outer peripheral surface of the magnetic pole portion 5A, that is, a corner portion where the outer peripheral surface of the magnetic pole portion 5A and the stator side end surface 5B intersect. Is provided. The first edge 5J receives a magnetic force (attraction 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 part of the outer peripheral surface of the magnetic pole part 5A that is spaced away from the first edge 5J, that is, at the corner where the outer peripheral surface of the magnetic pole part 5A and the tapered surface 5D intersect. ing. When the second edge 5K enters the bottomed hole 4J of the excited stator 4, a magnetic force (attraction force) in a direction away from the stator 4 with the opening end 4H of the cylindrical magnetic control unit 4G. (See FIG. 5).

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

  The spacer 7 is provided between the stator 4 and the plunger 5. The spacer 7 regulates the minimum axial 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 having a larger diameter than the cylindrical portion 7A, and a pin 6 is inserted on 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 portion 4J1 of the bottomed hole 4J of the stator 4. The flange portion 7B of the spacer 7 is sandwiched between the bottom portion 4J1 of the bottomed hole 4J and the stator side end surface 5B of the plunger 5. Thereby, the plunger 5 does not directly contact the bottom 4J1 of the bottomed hole 4J, and the minimum axial distance between the two when the stator side end surface 5B of the plunger 5 is closest to the bottom 4J1 of the bottomed hole 4J. The (interval) is regulated by the thickness dimension of the flange portion 7B of the spacer 7 in the axial direction.

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

  The distance L2 is set so as to satisfy the relationship of the following formula 2 with respect to the length L1.

Further, the distance L3 is set so as to satisfy the relationship of the following formula 3 with respect to the length L1.

  Next, the configuration of the yoke 8, the ring 9, the screw 10, the subspring 13 and the like will be described. First, the yoke 8 is arranged 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 portion 8A serving as a magnetic path, a cylindrical long tube portion 8B extending in the axial direction from the outer peripheral side of the bottom portion 8A toward the stator 4, and a long tube portion 8B across the bottom portion 8A. The mounting cylinder part 8C which protruded on the opposite side is included. An 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 into the sliding hole 8D. That is, the sliding hole 8D includes the sliding contact portion 5C of the plunger 5 so as to be cantilevered and guides the plunger 5 so as to be slidable in the axial direction.

  A small-diameter outer peripheral surface 8E that is one step smaller in diameter than the outer peripheral surface of the long cylindrical portion 8B is formed at the end portion on the stator 4 side of the outer peripheral surface of the long cylindrical portion 8B of the yoke 8. 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 cylinder portion 8C of the yoke 8, and a nut 21 described later is screwed to 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 iron core 4 </ b> B of the stator 4 and the long cylindrical portion 8 </ b> B of the yoke 8. The ring 9 is formed in a cylindrical shape using a magnetic material. One end 9 </ b> A that is one side in the axial direction of the ring 9 (the stator 4 side) is fitted and fixed to the small-diameter outer peripheral surface 4 </ b> F of the stator 4. The other end 9 </ b> B which is the other axial side (the yoke 8 side) of the ring 9 is fitted and fixed to the small-diameter outer peripheral surface 8 </ b> E of the yoke 8. Thereby, the 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 columnar shape, and this screw 10 has a head portion 10A and a shaft portion 10B having a smaller diameter than the head portion 10A. The shaft portion 10B is provided with two flange portions 10C and 10D which are separated from each other in the axial direction. A shaft-side male screw 10E is formed on the outer peripheral surface of the shaft portion 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 loosened by screwing a lock nut 11 onto the head-side male screw 10F. An O-ring 12 that seals oil in the inner housing 3 is provided between the flange portion 10C and the flange portion 10D.

  The subspring 13 is disposed in a compressed state between the tip of the shaft-side male screw 10E of the screw 10 and the yoke-side end surface 5E of the plunger 5. The subspring 13 presses the yoke-side end surface 5E of the plunger 5 toward 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 screwing amount into the yoke 8. That is, the screw 10 finely adjusts the driving force applied to 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 including 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 includes a cylindrical bobbin main body 15A fitted to the outer peripheral surface of the inner housing 3, and a pair of flange members 15B and 15C projecting radially outward from both axial ends of the bobbin main body 15A. . One flange member 15B is provided with a protrusion 15D protruding in a direction away from the other flange member 15C, and the flange member 15C is provided with a protrusion 15E protruding in a direction away from the flange 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 moves the plunger 5 toward or away from the stator 4.

  The exterior mold 18 is provided so as to cover the coil 16 wound around the bobbin 15 and the flange members 15B and 15C of the bobbin 15 from the outer peripheral side. In this case, the exterior mold 18 covers the projection 15D of the one collar member 15B and the projection 15E of the other collar member 15C. As a result, the outer mold 18 wraps the entire bobbin 15 from the outside, and one side (the stator 4 side) in the axial direction of the outer mold 18 is concavo-convexly fitted into the protrusion 15D of the flange member 15B without gaps. The other side in the axial direction (the yoke 8 side) is unevenly fitted to the protrusion 15E of the flange member 15C without any gap.

  A socket 19 bent in an L shape is integrally formed on one side of the outer mold 18 in the axial direction. An insertion port 19A for inserting a plug (not shown) is formed on the distal end side of the socket 19, and the distal end of the terminal 17 electrically connected to the coil 16 is disposed in the insertion port 19A. Has been. Accordingly, power is supplied to the coil 16 from the outside via the terminal 17 by inserting a plug (not shown) into the insertion port 19 </ b> A of the socket 19.

  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 portion 20B projecting radially inward from the other axial side (yoke 8 side) of the casing main body 20A. One side of the casing body 20 </ b> A in the axial direction (stator 4 side) is an open end 20 </ b> C, and the open end 20 </ b> C is fitted to the outer peripheral surface of the flange portion 4 </ b> A 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 into the yoke fitting hole 20D. In this state, the mounting cylinder portion 8C of the yoke 8 protrudes outside the lid portion 20B through the yoke fitting hole 20D. The solenoid casing 20 is fixed to the inner housing 3 by screwing a nut 21 onto a male screw 8F formed on the mounting cylinder portion 8C.

  The O-ring 22 is provided between the fixed iron core 4 </ b> B of the stator 4, the flange member 15 </ b> B of the bobbin 15, and the exterior mold 18. The O-ring 23 is provided between the bottom 8 </ b> A of the yoke 8, the flange member 15 </ b> 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 seal the boundary surface between the flange members 15B and 15C of the bobbin 15 and the exterior mold 18 from the boundary surface. This prevents moisture from entering the 16 side.

  Next, the control valve unit 24 that 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 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 located between the small-diameter cylindrical portion 25A located on one side in the axial direction, the large-diameter cylindrical portion 25B located on the other axial side, and the small-diameter cylindrical portion 25A and the large-diameter cylindrical portion 25B. And an intermediate cylinder portion 25C. The small diameter cylinder 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). 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. Yes. 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 portion 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 that are separately connected to the three ports 25D, 25E, and 25F. The housing is a male screw 25J of the intermediate cylinder portion 25C. It is configured to be screwed on. The flow paths provided in the housing are isolated by O-rings 26 and 27 that are externally fitted to the small-diameter cylindrical portion 25A with the output port 25E interposed therebetween. An O-ring 28 that seals 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 provided on the inner peripheral side of the valve casing 25 so as to be movable in the axial direction. The spool 29 is a long rod-like body, and extends on the inner peripheral side of the valve casing 25 in the axial direction. A bottomed axial flow path 29 </ b> A extending in the axial direction is formed at the axial center position of the spool 29. An annular spring receiving plate 30 is attached to the outer peripheral surface of the spool 29 and at the boundary position between the intermediate cylindrical portion 25C and the large diameter cylindrical portion 25B of the valve casing 25. The spring receiving plate 30 faces the spring receiving portion 25L formed on the inner peripheral side of the intermediate cylindrical portion 25C of the valve casing 25 in the axial direction. A return spring 31 is provided between the spring receiving plate 30 of the spool 29 and the spring receiving portion 25 </ b> L of the valve casing 25. Therefore, the spool 29 is always pressed against the stator 4 side by the urging force of the return spring 31, and the end surface of the spool 29 on the stator 4 side is in contact with the pin 6.

  Four lands 29 </ b> B, 29 </ b> C, 29 </ b> D, and 29 </ b> E are provided on the outer peripheral surface of the spool 29 so as to be separated from each other 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 is set to have a larger diameter than the land 29D. When the land 29C is in contact with the seal surface 25G of the valve casing 25, the supply port 25D and the output port 25E are blocked. When the spool 29 moves in the axial direction and the land 29C is separated from the seal surface 25G, the supply port 25D and the output port 25E communicate with each other. As a result, the pressure oil supplied from the hydraulic pump (not shown) to the supply port 25D is guided to the hydraulic actuator (not shown) through the output port 25E.

  On the other hand, when the land 29D is in contact with the seal surface 25H of the valve casing 25, the output port 25E and the drain port 25F are blocked. When the spool 29 moves in the axial direction and the land 29D is separated from the seal surface 25H, the output port 25E and the drain port 25F communicate with each other. Thereby, 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 end surface in the axial direction of the small diameter cylindrical portion 25A of the valve casing 25. The plate 32 is always pressed against the axial end surface of the small-diameter cylindrical portion 25A by a wave washer 33 provided between a wall surface (not shown) of a housing to which the valve casing 25 is attached. Thus, a damping chamber 34 is formed between the end surface on one side in the axial direction of the spool 29 and the plate 32. An orifice 35 is provided at one end in the axial direction of the spool 29, and the axial flow path 29 </ b> A of the spool 29 communicates with the damping chamber 34 via the orifice 35.

  In the spool 29, radial flow paths 29F and 29G penetrating in the radial direction are provided so as to be separated in the axial direction. Each of these radial flow paths 29F and 29G communicates with the axial flow path 29A. Thereby, the hydraulic oil in the tank (not shown) is guided from the drain port 25F to the inner peripheral side of the valve casing 25 through the radial flow path 29F, the axial flow path 29A, and the radial flow path 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 on the yoke 8 through the through hole 5H of the plunger 5. It is introduced into the hole 8D. As described above, the hydraulic oil in the tank is filled into 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 that seals 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 mounting cylindrical portion 4C of the stator 4.

Next, a method for 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 portion 4J1 of the bottomed hole 4J. Next, one end 9 </ b> A of the ring 9 is press-fitted into the small-diameter outer peripheral surface 4 </ b> F of the stator 4. In this state, the pin 6 press-fitted into the central 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-fitted into the other end 9B of the ring 9 while the sliding contact portion 5C of the plunger 5 is inserted 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 housed in 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, the butted portion of the axial end surface (stepped portion) of the small-diameter outer peripheral surface 8E of the yoke 8 and the axial end surface of the other end 9B of the ring 9 with the inclination of the ring 9 with respect to the yoke 8 corrected. 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 this third step, the inclination 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 between the small-diameter outer peripheral surface 4F of the stator 4 and the one end 9A side of the ring 9, thereby firmly joining 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 side than the bottom 4J1 of the bottomed hole 4J of the stator 4. It is formed at a spaced position.

Then, after the inner housing 3 is assembled, for example, the bobbin 15 around which the coil 16 is wound is assembled to the outer peripheral side of the inner housing 3. The coil 16 wound around the bobbin 15 and the flange members 15B and 15C of the bobbin 15 are covered from the outer peripheral side by the exterior mold 18. Next, the exterior mold 18 is covered from the outer peripheral side by the solenoid casing 20. Further, the open end 20C of the solenoid casing 20 (casing body 20A) is fitted to the outer peripheral surface of the flange portion 4A of the stator 4, and the yoke fitting hole 20D of the lid portion 20B is fitted to the outer peripheral surface of the bottom portion 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 cylinder portion 8C) protruding outside the lid portion 20B. Next, the inner peripheral side of the subspring 13 is inserted into the end portion of the pin 6 protruding into the through hole 8G of the yoke 8, and the O-ring 12 is attached between the flange portions 10 </ b> C and 10 </ b> D of the screw 10. In this state, the shaft side male screw 10E of the screw 10 is screwed onto the female screw 8H of the yoke 8 (through hole 8G). Then, the screw 10 is engaged with the yoke 8 by screwing the lock nut 11 into the head-side male screw 10F of the screw 10 in a state where the end of the shaft-side male screw 10E is in contact with the end of the pin 6. Fix it. In this way, the electromagnetic drive unit 2 can be assembled.

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

First, the 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.

In a state where 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. For this reason, the output port 25E and the drain port 25F of the valve casing 25 communicate with each other, and the output port 25E and the supply port 25D are held in a blocked state (initial state).

When power is supplied from the power supply device to the coil 16 via the terminal 17, a magnetic field (excitation force) is generated by the coil 16, and the plunger 5 has an attractive force corresponding to the current value supplied to the coil 16. It is sucked into the fixed iron core 4B. At this time, the sliding contact portion 5 </ b> C of the plunger 5 moves to the stator 4 side while slidingly contacting the inner peripheral surface of the sliding hole 8 </ b> D of the long cylindrical portion 8 </ b> B of the yoke 8. The plunger 5 stops at a position where the hydraulic 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 iron core 4B are balanced.

The displacement of the plunger 5 is transmitted to the spool 29 via the pin 6, so that the spool 29 moves in the valve casing 25. As a result, the supply port 25D and the output port 25E of the valve casing 25 are communicated or cut off, and the output port 25E and the drain port 25F are communicated or cut off. Supply / discharge of pressure oil from the hydraulic pump to the hydraulic actuator is performed. Is controlled. When the power supply to the coil 16 is stopped, the magnetic field by 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 and the drain port 25F of the valve casing 25 communicate with each other, and the output port 25E and the supply port 25D are blocked.

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

First, when power is supplied from the power supply device to the coil 16 via the terminal 17, a magnetic field is generated by the coil 16. At this time, magnetic flux is generated inside the stator 4, plunger 5, yoke 8, and solenoid casing 20 constituting the magnetic path. In this case, the cylindrical magnetic control unit 4G of the stator 4 constituting the magnetic path has a smaller volume than the other magnetic path constituting 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 path of other portions. As a result, an attractive force (magnetic force) is generated between the fixed core part 4B of the stator 4 including the cylindrical magnetic control part 4G and the plunger 5 according to Coulomb's law regarding magnetism. This 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 attractive 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 shown 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 in the same position as the opening 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. 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 unit 4G. Extend. For this reason, the attractive force F <b> 1 acting on the plunger 5 extends in a direction inclined with respect to the axial direction along the direction of the magnetic flux lines 37. The plunger 5 is displaced in a direction approaching the stator 4 by an axial suction force Fx1 that is an axial component of the suction 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 by the stator 4, the plunger 5 enters the intermediate position shown in FIG. 4, that is, the first edge 5 J of the magnetic pole part 5 A enters the cylindrical magnetic control part 4 G (in the bottomed hole 4 J). Displace to position. At the intermediate position in FIG. 4, the magnetized region of the cylindrical magnetic control unit 4 </ b> G increases in the radial direction as the outer peripheral surface of the tapered portion 4 </ b> L increases in diameter. Accordingly, the direction of the magnetic flux lines 37 shown in FIG. 4 is inclined in the radial direction as compared with the initial position shown in FIG. 3, and the inclination of the attractive force F2 acting on the plunger 5 with respect to the axial direction is the attractive force at the initial position. It becomes larger than the inclination of F1. On the other hand, when the magnetized region of the cylindrical magnetic control unit 4G increases, the attractive force F2 becomes larger than the attractive force F1 at the initial position. As a result, the axial suction force Fx2 that is the axial component of the suction force F2 is equal to or close to the same value as 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 restriction position shown in FIG. 5, that is, the position where the stator side end surface 5 </ b> B of the plunger 5 contacts the flange portion 7 </ b> B 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 part 5A is displaced from the tapered part 4L of the cylindrical magnetic control part 4G to the inner peripheral side of the cylindrical part 4M, a region in which the cylindrical magnetic control part 4G is magnetized is provided. 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 as compared with the intermediate position shown in FIG. 4, and the inclination of the attractive force F3 acting on the plunger 5 with respect to the axial direction is the suction at the intermediate position. It becomes larger than the inclination of the force F2. On the other hand, since the plunger 5 is 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 portion 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. Accordingly, the second edge 5K of the magnetic pole part 5A enters the cylindrical magnetic control part 4G (in the bottomed hole 4J) of the stator 4 while the plunger 5 is displaced toward the restriction position.

In this state, a magnetic flux is generated in an oblique direction 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, the suction force F4 toward the opening end 4H acts on the second edge 5K while being inclined 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 in which the plunger 5 is separated from the spacer 7, and is opposite to the axial suction force Fx3, which is the axial component of the suction force F3. It becomes the direction. Therefore, a part of the axial suction force Fx3 acting in the direction in which the plunger 5 approaches the stator 4 is canceled out by the axial suction force Fx4 acting in the direction in which the plunger 5 is separated from the stator 4. As a result, in the region where the plunger 5 approaches the restriction position, the axial suction force (Fx3-Fx4) acting on the plunger 5 is changed to the axial suction force Fx1 at the initial position and the axial suction force Fx2 at the intermediate position. It can be set to an equivalent value or a value close to an equivalent value (Fx3-Fx4≈Fx2).

Therefore, when the feeding current fed to the coil 16 is set to a constant value, as shown by the characteristic line 38 in FIG. 6, the plunger 5 has an initial position P1 shown in FIG. 3, an intermediate position P2 shown in FIG. During the displacement to the restricting 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, it is possible to suppress a sudden increase in the axial suction force Fx acting on the plunger 5. it can. Therefore, it is possible to secure a large area where the plunger 5 can be displaced while the axial suction force Fx acting on the plunger 5 is constant or nearly constant, that is, the area A from P1 to P3 in FIG.

Here, the distance L2 from the stator side end surface 5B of the plunger 5 to the second edge 5K is 0.5L1 ≦ with respect to the axial length L1 of the cylindrical magnetic control unit 4G (bottomed hole 4J) of the stator 4. The range is set to L2 ≦ 0.7L1. Accordingly, 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. The thickness 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 in a stage before the stator side end surface 5B of the plunger 5 approaches the stator 4. It enters into the bottomed hole 4J. Therefore, the axial suction force Fx for separating the plunger 5 from the stator 4 acts on the plunger 5 before the axial suction force Fx for causing the plunger 5 to approach the stator 4 increases. As a result, 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 becomes narrow.

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 is bottomed until just before the stator side end surface 5B of the plunger 5 contacts 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 while the axial suction force Fx acting on the plunger 5 is constant or nearly constant becomes narrow. For this reason, it is desirable to set the distance L2 in a 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 the comparative example 1, the taper surface 101C is formed at the boundary between the magnetic pole part 101A and the sliding contact part 101B, and the angle at which the outer peripheral surface of the magnetic pole part 101A and the stator side end face 101D intersect. The part becomes the first edge 101E, and the corner where the outer peripheral surface of the magnetic pole part 101A and the taper surface 101C intersect becomes the second edge 101F. In this case, the second edge 101 </ b> F is positioned outside the bottomed hole 4 </ b> J at the restriction position where the stator side end surface 101 </ b> D of the plunger 101 contacts the flange 7 </ b> B of the spacer 7 in the bottomed hole 4 </ b> J of the stator 4. It has become. For this reason, the plunger 101 according to the first comparative example has the plunger 101 between the second edge 101F and the opening end 4H of the cylindrical magnetic control unit 4G even when the stator side end surface 101D is close to the restriction position. The suction force in the direction of moving away from is not applied.

As shown in FIG. 8, the plunger 102 according to the comparative example 2 is formed in a columnar shape in which the magnetic pole part 102A and the sliding contact part 102B have the same outer dimensions. Accordingly, in the plunger 102 according to the comparative example 2, the corner portion where the outer peripheral surface of the magnetic pole portion 102A and the stator side end surface 102C intersect is the first edge 102D, but the portion corresponding to the second edge 5K according to the first embodiment. Is not provided. For this reason, the plunger 102 according to the comparative example 2 has a suction force in the direction of moving away from the stator 4 with respect to the plunger 102 even in a state where the stator side end face 102C approaches the restriction position where the stator end face 102B comes into contact with the flange portion 7B of the spacer 7. Does not work.

Therefore, in the electromagnetic drive unit using the plunger 101 according to the 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 is moved to the stator. The axial suction force Fx acting in the direction of approaching 4 is constant or close to constant. However, while the plunger 101 is displaced from the intermediate position P2 to the restricting position P3, the axial suction force Fx acting in the direction in which the plunger 101 approaches the spacer 7 suddenly increases. As a result, a 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 Comparative Example 2, as in Comparative Example 1, the relationship between the displacement of the plunger 102 and the axial suction force Fx acting on the plunger 102 is shown in FIG. As indicated by the characteristic line 39.

As described above, in the electromagnetic drive unit 2 according to the first embodiment, the area in which the plunger 5 can be displaced while the axial suction force Fx acting on the plunger 5 is constant or close to constant is enlarged. A change in suction force due to the displacement of the plunger 5 is reduced. For this reason, in the solenoid valve 1 having the electromagnetic drive unit 2, the suction force to the plunger 5 required for balancing the hydraulic pressure acting on the spool 29 and the spring force of the return spring 31 and the subspring 13 is applied to the coil 16. It can be controlled with high accuracy by power supply control. Accordingly, when the solenoid valve 1 having the electromagnetic drive unit 2 is used in a hydraulic system that performs control of the tilt angle of a variable displacement hydraulic pump / hydraulic motor, control of a spool / throttle valve of a control valve, and the like. Can improve the control accuracy of the hydraulic system.

Moreover, in the solenoid valve 1 provided with the electromagnetic drive unit 2, the control valve unit can be expanded by enlarging 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, and the supply port 25D and the output port 25E can be set. The flow rate of the pressure oil flowing through the drain port 25F can be increased. As a result, the response of the oil pressure by the electromagnetic valve 1 can be increased, and the response of the hydraulic system including the electromagnetic valve 1 can be increased.

Next, FIG. 9 and FIG. 10 show a second embodiment of the present invention. The feature of the second embodiment is that the magnetic pole part of the plunger and the sliding contact part have the same outer diameter, and the outer peripheral surface of the plunger is provided with a constriction part that separates the magnetic pole part and the sliding contact part in the axial direction. There is in being. In the second embodiment, the same constituent elements as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In the figure, the electromagnetic drive unit 41 constitutes an electromagnetic 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, a pin 6, a spacer 7, a yoke 8, a ring 9, a bobbin 15, a coil 16, The 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 arranged coaxially with the stator 4. The plunger 42 has the same outer diameter size (same diameter) as that of a magnetic pole portion 42A, which will be described later, and the outer diameter surface of the sliding contact portion 42C, and a constricted portion 42G, which will be described later, is provided on the outer peripheral surface of the plunger 42.

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

The slidable contact portion 42C is provided at the end of the plunger 42 opposite to the stator 4 (on the yoke 8 side). The sliding contact portion 42C is slidably inserted into the sliding hole 8D of the yoke 8 and performs magnetic transfer with the yoke 8 while being in sliding contact with 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 therewith. A central hole 42E penetrating in the axial direction is formed at the axial center position of the plunger 42, and the pin 6 is press-fitted into the central hole 42E. A through hole 42F penetrating in the axial direction is formed in a portion of the plunger 42 that is eccentric in the radial direction from the center hole 42E.

The constricted part 42G is formed in a concave groove shape on the entire outer peripheral surface of the plunger 42, and separates the magnetic pole part 42A and the sliding contact part 42C in the axial direction. In the plunger 42, the stator 4 side is a magnetic pole part 42A and the yoke 8 side is a sliding contact part 42C across the constricted part 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 (attraction 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 part of the outer peripheral surface of the magnetic pole part 42A that is spaced away from the first edge 42H, that is, at the corner where the outer peripheral surface of the magnetic pole part 42A and the constricted part 42G intersect. ing. When the second edge 42J enters the bottomed hole 4J of the excited stator 4, the second edge 42J receives a magnetic force (attraction force) in a direction away from the stator 4 from the cylindrical magnetic control unit 4G.

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

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

Here, after the first edge 42H of the plunger 42 enters the bottomed hole 4J of the stator 4, the first embodiment is performed until the second edge 42J of the plunger 42 enters the bottomed hole 4J. Similar to the embodiment, an axial suction force in the direction approaching the stator 4 acts on the plunger 42. When the second edge 42J of the plunger 42 enters the bottomed hole 4J, a magnetic force (attraction force) is generated between the second edge 42J and the opening end 4H of the cylindrical magnetic control unit 4G, and the plunger 42 is moved. An axial suction force in a direction away from the stator 4 acts. As a result, a part of the axial suction force that causes the plunger 42 to approach the stator 4 can be canceled out. 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 a sudden increase in the axial suction force acting on the plunger 42. . Therefore, as in the first embodiment, the region in which the plunger 42 can be displaced can be enlarged while the axial suction force acting on the plunger 42 is constant or nearly constant.

In the second embodiment, a constricted portion 42G is formed on the outer peripheral surface of the plunger 42 made of a magnetic material, and the magnetic pole portion 42A and the sliding contact portion 42C are separated in the axial direction by the constricted portion 42G. ing. However, the present invention is not limited to this, and has a uniform outer diameter by embedding an annular member 43 made of a nonmagnetic material in the constricted portion 42G, for example, as in the first modification shown in FIG. You may form as plunger 42 '.

Further, in the embodiment, the case where the taper portion 4L linearly extending while reducing the diameter toward the opening end 4H is excited on the outer peripheral surface of the cylindrical magnetic control portion 4G of the stator 4 is excited. However, the present invention is not limited to this. For example, as in the second modification shown in FIG. 12, a tapered portion 4L ′ that extends in a curved 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 ends 4L, 4L 'Taper portions 5, 42 Plungers 5A, 42A Magnetic pole portions 5B, 42B Stator side end surfaces 5C, 42C Sliding contact portions 5J, 42H First Edge 5K, 42J Second edge 7 Spacer 8 Yoke 8D Sliding hole 16 Coil 42G Constriction

Claims (4)

A stator made of a magnetic material;
A plunger made of a magnetic material and arranged coaxially with respect to the stator;
A yoke made of a magnetic material, arranged coaxially with respect to the stator and having a sliding hole for slidably guiding the plunger;
An electromagnetic drive unit that is disposed so as to surround the stator, the plunger, and the yoke, and includes a coil that energizes or demagnetizes the stator by power supply control and moves the plunger toward or away from the stator.
A magnetic 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 that is provided at an end of the plunger opposite to the stator, and that is in sliding contact with the 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 portion provided as a bottomed hole provided on the stator and having a bottom portion facing the stator side end surface of the plunger and having the plunger side as an open end;
Provided on the outer peripheral surface of the cylindrical magnetic control unit, and a tapered portion which becomes gradually smaller in diameter toward the plunger side,
Wherein the portion spaced apart on the side opposite to the stator from the first edge of the outer circumferential face of the pole portion, the said tubular magnetic control unit when entering the blind hole of the cylindrical magnetic control unit A second edge that receives a magnetic force in a direction away from the stator between the opening ends is provided,
Between the stator and the plunger is provided a spacer for regulating the minimum axial distance between the two,
The axial length of the cylindrical magnetic control unit is (L1), the distance between the stator side end surface of the plunger and the second edge is (L2), and the stator regulated by the spacer When the minimum axial distance from the plunger is (L3), the sum (L2 + L3) of the distances is smaller than the length (L1) of the cylindrical magnetic control unit. unit. The distance (L2) between the stator side end surface 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. Set,
The electromagnetic drive unit according to claim 1 , wherein a minimum axial distance (L3) between the stator and the plunger regulated by the spacer is set to L3 = 0.2L1. The electromagnetic drive unit according to claim 1, wherein an outer diameter of the magnetic pole portion is larger than an outer diameter of the sliding contact portion.   The outer diameter of the magnetic pole part and the sliding contact part is the same diameter, and a constricted part that separates the magnetic pole part and the sliding contact part in the axial direction is provided on the outer peripheral surface of the plunger. The electromagnetic drive unit according to claim 1.

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