JP2013117313A - Solenoid proportional control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solenoid proportional control valve that can precisely control flow rate of operating fluid in accordance with an excitation current.SOLUTION: The solenoid proportional control valve includes: a first bearing 70 which supports an outer circumferential surface 20a of a shaft 20 to permit the sliding of the outer circumferential surface 20a with respect to a sleeve 30; and a second bearing 75 which supports an outer circumferential surface 60b of a plunger 60 to permit the sliding of the outer circumferential surface 60b with respect to the sleeve 30; wherein the sleeve 30 includes a valve inlet port 18 communicated with the pressure source side, a valve outlet port 16 communicated with the load side and a seat part 29 where the valve outlet port 16 is opened, the first bearing 70 is fixed to a large diameter inner circumferential surface 31b of the sleeve 30, and the valve inlet port 18 is formed to be opened over the small diameter inner circumferential surface 31a and large diameter inner circumferential surface 31b of the sleeve 30.

Description

  The present invention relates to an electromagnetic proportional control valve that controls the flow rate of a working fluid by adjusting the opening area of a variable throttle according to an exciting current.

  In general, an electromagnetic proportional control valve is widely used to control the operation of a power steering device provided in a vehicle (see Patent Document 1).

  Conventionally, this type of electromagnetic proportional control valve includes a cylindrical sleeve and base, and a shaft that is slidably inserted into the sleeve and base.

  In the electromagnetic proportional control valve, the shaft moves to a position where the spring force of the spring acting on the shaft, the solenoid thrust force, the force due to the differential pressure across it, the working fluid force, and the like are balanced. A working fluid having a control flow rate according to the opening area of the electromagnetic proportional control valve and the differential pressure before and after that flows.

JP 2001-180507 A

  However, in such a conventional electromagnetic proportional control valve, when the support rigidity of the shaft is insufficient, the concentricity with respect to the seat portion of the valve body changes due to the pressure of the working fluid received by the valve body during the movement of the shaft. Therefore, there is a problem that the flow rate of the working fluid cannot be accurately controlled according to the excitation current.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electromagnetic proportional control valve capable of accurately controlling the flow rate of a working fluid in accordance with an exciting current.

  The present invention is an electromagnetic proportional control valve in which the valve opening is adjusted according to an exciting current, and includes a cylindrical sleeve constituting a magnetic path, a columnar shaft, and a cylindrical shape fixed to the shaft. A plunger, a first bearing that slidably supports the outer peripheral surface of the shaft with respect to the sleeve, a second bearing that slidably supports the outer peripheral surface of the plunger with respect to the sleeve, and a spring that biases the shaft And a solenoid that drives the plunger by magnetic force, and the sleeve includes a valve inlet port that communicates with the pressure source side, a valve outlet port that communicates with the load side, and a seat portion that opens the valve outlet port. The shaft has a valve body projecting from the first bearing toward the seat portion, and is defined between the valve body and the seat portion as the shaft is displaced in the central axis direction. Variable aperture The sleeve has a configuration in which the opening area of the portion changes, and the sleeve has a cylindrical surface formed by sequentially expanding the diameter, a small-diameter inner peripheral surface, a large-diameter inner peripheral surface, and a small-diameter inner peripheral surface and a large-diameter inner peripheral surface. The first bearing is fixed to the large-diameter inner peripheral surface, and the valve inlet port opens across the small-diameter inner peripheral surface and the large-diameter inner peripheral surface. It is formed in this.

  According to the present invention, the distal end portion of the shaft is supported by the first bearing with respect to the sleeve, and the proximal end portion of the shaft is supported by the second bearing via the plunger, so that the valve moves in the process of moving the shaft. The concentricity of the valve body with respect to the seat portion is prevented from changing by the working fluid force applied to the body, and the inflection point at which the flow rate of the working fluid changes rapidly according to the excitation current can be suppressed.

  The front end of the first bearing abuts against the stepped portion of the sleeve, thereby further restricting the closer to the seat, and the first bearing is prevented from largely closing the opening of the valve inlet port.

It is a fluid pressure circuit diagram of a power steering device showing an embodiment of the present invention. It is a sectional view of an electromagnetic proportional control valve. It is sectional drawing of a sleeve etc. similarly. It is sectional drawing of a sleeve etc. similarly. It is a characteristic view which similarly shows the relationship between the exciting current and flow volume of an electromagnetic proportional control valve.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a fluid pressure circuit diagram of a power steering device provided in a vehicle. This will be described below.

  The power steering device 1 includes a pump 3, an electromagnetic proportional control valve 2, a power steering system 7, a pressure compensation valve 6, a relief valve 5, an orifice 4, and the like.

  The working fluid (working oil) discharged from the pump 3 is supplied to the power steering system 7 via the electromagnetic proportional control valve 2.

  The front-rear differential pressure ΔP (= P1−P2) of the electromagnetic proportional control valve 2 is kept substantially constant by the pressure compensation valve 6.

  When an exciting current flows through the electromagnetic proportional control valve 2, the valve opening is adjusted according to the exciting current, and a working fluid having a control flow rate according to the opening area flows.

  The relief valve 5 determines the maximum pressure of the fluid pressure circuit and functions as a safety valve. The orifice 4 contributes to the response and stability of the fluid pressure circuit.

  When the vehicle is not steered, the opening area of the electromagnetic proportional control valve 2 is kept at the minimum opening, and the working fluid having the minimum flow rate determined by the opening area of the electromagnetic proportional control valve 2 is supplied to the power steering system 7. Most of the working fluid is returned to the tank side via the pressure compensation valve 6 to reduce energy loss.

  When the vehicle is steered, the electromagnetic proportional control valve 2 increases its opening area and the pressure P1 on the upstream side of the electromagnetic proportional control valve 2 is adjusted high. The power steering system 7 is supplied with a working fluid having a flow rate controlled in accordance with the opening area of the electromagnetic proportional control valve 2, and applies a necessary wheel steering force.

  FIG. 2 is a cross-sectional view showing the electromagnetic proportional control valve 2 described above. The electromagnetic proportional control valve 2 is supported by a sleeve (valve body) 30 that defines a flow path of a working fluid, and is slidable in the axial direction with respect to the sleeve 30 via first and second bearings 70 and 75. A shaft 20 that restricts the flow path of the working fluid, a plunger (movable iron core) 60 fixed to the shaft 20, first and second springs 11 and 12 that urge the shaft 20, and a solenoid thrust (magnetic force). A solenoid (electromagnetic coil) 15 for driving 60 is provided.

  The solenoid 15 includes a resin bobbin (core) 50, a coil (winding) 52 wound around the bobbin 50, a coil case 10 that houses the coil 52, and a space between the coil case 10 and the coil 52. A mold resin 54 and the like that are filled and solidified.

  The resin bobbin 50 is formed by molding into a cylindrical shape having a U-shaped cross section. A coil 52 is formed by winding a wire around the bobbin 50.

  The mold resin 54 surrounds the coil 52 and is integrally formed with a connector portion 55 that accommodates the terminal 53 of the coil 52. A lead wire is connected to the terminal 53 via a socket (not shown) inserted into the connector portion 55. An exciting current from a drive circuit (not shown) is guided to the coil 52 via a lead wire and a terminal 53.

  Mold resin 54 is formed by filling molten resin between coil case 10, end ring 9, bobbin 50 and coil 52. Resin having a melting point higher than that of the bobbin 50 is used as the mold resin 54 and is fused at a contact portion with the bobbin 50 at the time of molding. Thus, the mold resin 54 covers the coil 52 without any gap, so that the solenoid 15 can be insulated and waterproof.

  As members constituting the magnetic path of the solenoid 15, a cylindrical sleeve 30 and a cylindrical base 90 arranged in the axial direction with respect to the sleeve 30 are provided inside the solenoid 15.

  A magnetic gap 91 is defined between the sleeve 30 and the base 90. A cylindrical filler ring 19 is interposed so as to surround the magnetic gap 91. The sleeve 30 and the base 90 are fitted to the inner peripheral surface of the filler ring 19 at the outer peripheral surfaces, and the end portions of the filler ring 19 are fixed by the laser welded portions 43 and 44. As a result, the sleeve 30 and the base 90 are coaxially coupled via the filler ring 19.

  As members constituting the magnetic path of the solenoid 15, a cylindrical coil case 10 and a disk-shaped end ring 9 are provided around the solenoid 15. The magnetic flux generated around the solenoid 15 is guided by the coil case 10 made of a magnetic material, the sleeve 30, the plunger 60, the base 90, and the end ring 9.

  The electromagnetic proportional control valve 2 includes a plate 45 that is fitted into a pump body (not shown) provided with a sleeve 30 in the pump 3 and that protrudes like a bowl from the outer peripheral portion of the sleeve 30, and the plate 45 is fastened to the pump body. The

  The sleeve 30 has a sleeve fitting portion 32 fitted and attached to a pump body (not shown). The sleeve fitting portion 32 protrudes in a bowl shape from the central portion of the sleeve 30 and is fitted into a recess of the pump body (not shown). The sleeve fitting part 32 has the outer peripheral surface 32a fitted to a pump body, and the annular groove 32b formed in the outer peripheral surface 32a. A seal ring 49 is interposed in the annular groove 32b, and the seal ring 49 seals between the sleeve 30 and the pump body.

  The sleeve 30 has a sleeve magnetic path portion 33 that constitutes the magnetic path of the solenoid 15. This sleeve magnetic path portion 33 is formed in a stepped cylindrical shape, and is fitted to the inner peripheral surface 33 a surrounding the plunger 60, the large-diameter outer peripheral surface 33 b fitted to the bobbin 50 and the coil case 10, and the filler ring 19. And a small-diameter outer peripheral surface 33c.

  The coil case 10 is formed in a cylindrical shape having an L-shaped cross section, and the inner peripheral surface 10 a at the tip is fitted to the large-diameter outer peripheral surface 33 b of the sleeve 30.

  The end ring 9 has an outer peripheral surface 9 a fitted into the proximal end inner peripheral surface 10 b of the coil case 10, and the inner peripheral surface 9 b is knurled and fixed to the outer peripheral surface 90 b of the base 90.

  The plate 45 is fitted into the large-diameter outer peripheral surface 33 b of the sleeve 30 by light press-fitting, abuts against an annular step 32 c formed on the outer periphery of the sleeve 30, and the annular step 32 c and the tip of the coil case 10. Sandwiched between the surface.

  The shaft 20 and the plunger 60 are supported by the sleeve 30 through first and second bearings 70 and 75 so as to be displaceable in the axial direction.

  The shaft 20 has a right cylindrical surface-like outer peripheral surface 20 a, and the outer peripheral surface 20 a is slidably supported by the first bearing 70.

  The plunger 60 has a right cylindrical surface-like outer peripheral surface 60 b, and the outer peripheral surface 60 b is slidably supported by the second bearing 75.

  Inside the sleeve 30 and the base 90, a plunger front chamber 82 and a plunger back chamber 81 are partitioned by a plunger 60.

  A plunger through hole 60c extending in the axial direction of the shaft 20 is formed in the plunger 60, and the plunger front chamber 82 and the plunger back chamber 81 are communicated with each other through the plunger through hole 60c. As the shaft 20 and the plunger 60 move in the axial direction, the working fluid moves between the valve body accommodating chamber 83, the plunger front chamber 82, and the plunger rear chamber 81 through the plunger through hole 60 c and the outer peripheral groove 71. .

  A first gap washer 41 is interposed inside the sleeve 30. A second gap washer 42 is interposed in the base 90. The first and second gap washers 41 and 42 are formed in a disk shape from a nonmagnetic resin material.

  When the shaft 20 moves in the valve closing direction (left direction in FIG. 2), the shaft 20 eventually comes into contact with the first gap washer 41 and is locked so as not to move further in the valve closing direction.

  When the shaft 20 moves in the valve opening direction (right direction in FIG. 2), the shaft 20 eventually comes into contact with the second gap washer 42 and is locked so as not to move further in the valve opening direction.

  The cylindrical plunger 60 is provided as a movable iron core that is driven by the magnetic force of the solenoid 15. The plunger 60 has an inner peripheral surface 60 a that is fitted and fixed in the middle of the shaft 20.

  The suction direction in which the solenoid 15 drives the plunger 60 by the solenoid thrust is the right direction as shown by the arrow in FIG. As the exciting current flowing through the solenoid 15 increases, the plunger 60 is displaced rightward in FIG. 2 against the spring force of the first and second springs 11 and 12.

  The coiled first spring 11 is interposed between the proximal end portion of the shaft 20 and the adjuster bolt 40 by being compressed. The first spring 11 biases the shaft 20 in the valve closing direction (left direction in FIG. 2).

  The coiled second spring 12 is compressed and interposed between the first bearing 70 and the plunger 60. The second spring 12 biases the shaft 20 in the valve opening direction (right direction in FIG. 2).

  In a state where the distal end portion (valve body 25) of the shaft 20 enters the flow path (valve outlet port 16) through which the working fluid flows in the sleeve 30, the shaft 20 is closed in the valve closing direction (leftward in FIG. 2) by the working fluid pressure. Be energized. Since the spring force of the second spring 12 works against the working fluid pressure in the valve opening direction (rightward in FIG. 2), the solenoid thrust for driving the shaft 20 in the valve opening direction is kept small.

The solenoid thrust Fsol of the solenoid 15 generated when the shaft 20 is displaced from the above state in the valve closing direction by a distance Xs is expressed by the following equation.
Fsol = Ff + (ΔP · As) + (Fk1−Fk2) + (k1 + k2) · Xs (1)
here,
Ff: fluid force ΔP: front-rear differential pressure of the electromagnetic proportional control valve 2 As: cross-sectional area of the cylindrical portion of the shaft 20 Fk1: spring force before displacement of the first spring 11 Fk2: spring force k1 before displacement of the second spring 12 : Spring constant k1 of the first spring 11: Spring constant of the second spring 12

  In the electromagnetic proportional control valve 2, the spring force Fk2 of the second spring 12 and the solenoid thrust Fsol of the solenoid 15 act on the shaft 20 in the valve opening direction, and the force ΔP · As caused by the differential pressure ΔP across the electromagnetic proportional control valve 2 The fluid force Ff acting on the shaft 20 and the spring force Fk1 of the first spring 11 act in the valve closing direction, the shaft 20 moves to a position where these forces are balanced, and the opening area Av and the front-rear differential pressure obtained thereby. A control flow rate Q proportional to ΔP flows.

  By changing the screwing position of the adjuster bolt 40 to the base 90, the spring force of the first and second springs 11 and 12 applied to the shaft 20 is adjusted.

  The adjuster bolt 40 has a threaded portion 40a and a stepped portion 40b formed by expanding the diameter at the proximal end of the threaded portion 40a. The adjuster bolt 40 is screwed into a screw hole 90 a formed on the inner periphery of the base 90.

  The adjuster bolt 40 is inserted into the base 90 from the sleeve 30 side (left side in FIG. 2) with respect to the base 90, the screw portion 40a is screwed into the screw hole 90a of the base 90, and the step portion 40b is the end of the screw hole 90a. By abutting on the part, it is locked that the screwing position of the adjuster bolt 40 further moves to the right in FIG. This prevents the adjuster bolt 40 from falling off the base 90.

  After the screwing position of the adjuster bolt 40 is changed and the spring force of the first and second springs 11 and 12 is adjusted, the sealing material 48 is filled in the portion located behind the adjuster bolt 40 in the screw hole 90a. When the sealing material 48 is solidified, the adjuster bolt 40 is prevented from loosening.

  FIG. 3 is a cross-sectional view of the sleeve 30, the first bearing 70, the second bearing 75, and the like.

  The first bearing 70 is formed in a cylindrical shape and is fixed inside the sleeve 30. The first bearing 70 includes a bearing surface 70a slidably fitted to the outer circumferential surface 20a of the shaft 20, an outer circumferential surface 70b fitted to the sleeve 30, and a plurality of outer circumferential grooves 71 carved in the outer circumferential surface 70b. And have.

  Inside the sleeve 30, the valve body accommodation chamber 83 and the plunger front chamber 82 are partitioned by the first bearing 70. The valve body storage chamber 83 and the plunger front chamber 82 are communicated with each other by an outer peripheral groove 71 of the first bearing 70.

  The second bearing 75 is formed in a thin cylindrical shape by a resin sheet material made of PTFE (polytetrafluoroethylene) or the like as a nonmagnetic resin material, and is fixed to the inner peripheral surface 33 a of the sleeve magnetic path portion 33.

  By forming the second bearing 75 from a non-magnetic resin sheet material, the plunger 60 can be slidably supported on the inner peripheral surface 33a of the sleeve magnetic path portion 33 surrounding the plunger 60.

  The inner peripheral surface 33 a of the sleeve magnetic path portion 33 surrounding the plunger 60 constitutes a plunger support portion that supports the plunger 60 slidably via the second bearing 75.

  The sleeve 30 has a sleeve flow path defining portion 31 that defines a flow path through which the working fluid flows. The sleeve flow path defining portion 31 is provided at the distal end portion of the sleeve 30 accommodated in the pump body, and defines a working fluid flow path.

  FIG. 4 is a cross-sectional view showing the valve outlet port 16 of the sleeve 30, the valve body 25 of the shaft 20, and the like.

  The valve body 25 is formed at the tip of the shaft 20 protruding from the first bearing 70.

  The sleeve flow path defining portion 31 is formed in a stepped cylindrical shape, and a plurality of valve inlet ports 18 communicating with the pump 3 (pressure source side), and the valve inlet ports 18 open to connect the valve body 25 of the shaft 20. The valve body housing chamber 83 is housed, and the valve body housing chamber 83 has a single valve outlet port 16 and an outlet chamber 85 communicating with the power steering system 7 (load side).

  The working fluid discharged from the pump 3 passes through the valve inlet port 18 → the valve body accommodating chamber 83 → the variable throttle portion 84 → the valve outlet port 16 → the outlet chamber 85 in this order, as indicated by an arrow in the figure, and the power steering system 7. Sent to.

  The valve inlet port 18 defines a cylindrical flow path that extends perpendicular to the central axis O of the shaft 20. The shaft 20 is formed with, for example, three pairs (six) of valve inlet ports 18. The valve inlet ports 18 are arranged at equal intervals in the circumferential direction of the shaft 20, and are formed radially with the central axis O of the shaft 20 as the center. The number of valve inlet ports 18 is not limited to this, and may be a plurality other than three pairs (six) or a single number (one).

  The valve body storage chamber 83 is surrounded by a small-diameter inner peripheral surface 31 a centering on the central axis O of the shaft 20, and defines an annular flow path between the valve body 25 and the valve body 25 of the shaft 20. The valve inlet port 18 is opened in the small diameter inner peripheral surface 31a.

  The valve outlet port 16 defines a cylindrical flow path extending in the direction of the central axis O by a cylindrical wall surface centered on the central axis O of the shaft 20.

  The sleeve flow path defining portion 31 has an annular seat portion 29 that faces the valve body 25 of the shaft 20. The seat portion 29 is formed in an edge shape as an opening edge portion of the valve outlet port 16. A variable restricting portion 84 is defined as a passage having an annular cross section between the seat portion 29 and the valve body 25.

  As described above, the valve body storage chamber 83, the valve outlet port 16, the seat portion 29, and the outlet chamber 85 are formed around the central axis O of the shaft 20.

  The valve outlet port 16 of the sleeve 30 is formed in a right cylindrical hole shape having an opening diameter D and extends coaxially with the shaft 20.

  The valve body 25 includes a straight valve body portion 27 protruding in a right circular column shape and a tapered valve body portion 26 protruding in a tapered conical shape from the tip of the straight valve body portion 27.

  The outer diameter d of the columnar straight valve element 27 is formed smaller than the opening diameter D of the valve outlet port 16 by a predetermined value.

A region where the valve body 25 is at an opening degree equal to or smaller than the minimum valve opening degree is defined as a minimum opening area constant region (a minimum stroke region of the shaft 20). In this minimum valve opening constant region, the straight valve body portion 27 of the valve body 25 is inserted into the valve outlet port 16, and the variable throttle portion 84 serves as an annular flow passage between the seat portion 29 and the straight valve body portion 27. Defined. The channel cross-sectional area Av of the variable throttle 84 at the minimum valve opening is calculated by the following equation.
Av = (π / 4) (D ² −d ² ) (2)

  In the region where the minimum opening area is constant, since the straight valve body 27 of the valve body 25 is inserted into the seat portion 29, the opening area Av of the variable throttle portion 84 does not change with the displacement of the valve body 25. As a result, it is possible to prevent the opening area Av of the variable throttle portion 84 from changing due to an error in the minimum valve opening of the valve body 25 (variation in the minimum stroke of the shaft 20).

  A region where the valve body 25 is larger than the minimum valve opening and smaller than the maximum valve opening described later is defined as an opening area variable region. In the opening area variable region, the valve body 25 is inserted from the seat portion 29 into the valve outlet port 16, so that the opening area Av of the variable throttle portion 84 changes with the displacement of the valve body 25.

  In the constant opening area region where the valve opening degree of the electromagnetic proportional control valve 2 is equal to or less than the minimum valve opening degree, the flow rate of the working fluid passing through the variable throttle 84 is maintained at a substantially minimum flow rate.

  In the opening area variable region until the valve opening of the electromagnetic proportional control valve 2 reaches the maximum valve opening from the minimum valve opening, the flow rate of the working fluid that passes through the variable restrictor 84 is linearly proportional to the valve opening. The flow rate of the working fluid passing through the variable restrictor 84 increases from the minimum flow rate to the maximum flow rate.

  The maximum valve opening of the electromagnetic proportional control valve 2 is the valve opening obtained when the plunger 60 moves to the right in FIG. 2 and contacts the second gap washer 42.

  In this way, the electromagnetic proportional control valve 2 increases or decreases the flow rate of the working fluid passing through the variable restrictor 84 whose valve opening degree is controlled according to the stroke of the shaft 20.

  As shown in FIG. 4, when the maximum protrusion amount (length) of the straight valve body portion 27 of the valve body 25 of the shaft 20 protruding from the first bearing 70 is L, this maximum protrusion amount L is the outer diameter of the shaft 20. The concentricity with respect to the seat portion 29 (valve outlet port 16) of the valve body 25 is made substantially constant by the pressure of the working fluid received by the valve body 25 in the process of moving the shaft 20 with respect to d. The configuration is maintained.

  Based on the experiment, the maximum projecting amount L is set within a predetermined value 1.5 d or less with respect to the outer diameter d of the shaft 20, so that the valve body 25 receives the pressure of the working fluid received by the valve body 25 in the process of moving the shaft 20. It has been found that the concentricity of the body 25 with respect to the seat portion 29 is kept substantially constant.

  FIG. 5 is a characteristic diagram showing the relationship between the excitation current I guided to the coil 52 and the flow rate Q. In FIG. 5, the ideal characteristic indicated by a broken line is that of the electromagnetic proportional control valve 2 in which the maximum protrusion amount L is set to a range of a predetermined value 1.5 d or less with respect to the outer diameter d of the shaft 20. This ideal characteristic is that the flow rate Q is kept substantially constant while the excitation current I increases and decreases in the region where the minimum opening area is constant, and the flow rate Q increases and decreases as the excitation current I increases and decreases in the opening area variable region. It gradually increases and the flow rate Q is kept substantially constant while the excitation current I increases and decreases in the constant maximum opening area region.

  In FIG. 5, the characteristic indicated by the solid line is that of the electromagnetic proportional control valve 2 in which the maximum protrusion amount L is set to be greater than the predetermined value 1.5 d with respect to the outer diameter d of the shaft 20. The characteristic indicated by the solid line is an inflection point in which the flow rate Q changes abruptly while the excitation current I increases or decreases at a certain opening of the electromagnetic proportional control valve 2. This inflection point is bent and deformed by the force of the working fluid flow received by the valve body 25 during the movement of the shaft 20, and the concentricity of the valve body 25 with respect to the seat portion 29 (valve outlet port 16) changes. It is thought to occur.

  The first bearing 70 is disposed close to the seat portion 29 so as to partially close the opening of the valve inlet port 18 with respect to the small-diameter inner peripheral surface 31a. As a result, the maximum protrusion amount L of the shaft 20 can be set within a predetermined value of 1.5 d or less with respect to the outer diameter d of the shaft 20.

As shown in FIGS. 3 and 4, the sleeve 30 has a small-diameter inner peripheral surface 31 a and a large-diameter inner peripheral surface 31 b that are formed in a cylindrical surface shape with diameters being increased in order. An annular sleeve step portion 31c is formed between the small diameter inner peripheral surface 31a and the large diameter inner peripheral surface 31b.
The outer peripheral surface 70b of the first bearing 70 is fixed by being press-fitted into the large-diameter inner peripheral surface 31b. As for the 1st bearing 70, when the front-end | tip part 70c contact | abuts to the sleeve level | step-difference part 31c, it is controlled that it approaches the seat part 29 more than that. Thereby, it is avoided that the mounting position of the first bearing 70 is shifted and the first bearing 70 largely blocks the opening of the valve inlet port 18.

  The valve inlet port 18 is formed so as to open over the small-diameter inner peripheral surface 31a and the large-diameter inner peripheral surface 31b.

  A part of the outer peripheral groove 71 of the first bearing 70 is opened to face the valve inlet port 18, and constitutes a flow path that communicates the valve inlet port 18 and the valve body accommodation chamber 83. Accordingly, a part of the working fluid flowing from the valve inlet port 18 into the valve body accommodating chamber 83 passes through the outer peripheral groove 71.

  As described above, in the present embodiment, the electromagnetic proportional control valve 2 whose valve opening is adjusted in accordance with the excitation current, the cylindrical sleeve 30 and the base 90 constituting the magnetic path, and the cylindrical shaft 20, a cylindrical plunger 60 fixed to the shaft 20, a first bearing 70 that slidably supports the outer peripheral surface 20 a of the shaft 20 with respect to the sleeve 30, and an outer periphery of the plunger 60 with respect to the sleeve 30 A second bearing 75 for slidably supporting the surface 60b, spring urging means (first and second springs 11 and 12) for urging the shaft 20, and a solenoid 15 for driving the plunger 60 by magnetic force. The sleeve 30 includes a valve inlet port 18 communicating with the pressure source side, a valve outlet port 16 communicating with the load side, and a seat portion 29 where the valve outlet port 16 opens. The shaft 20 has a valve body 25 protruding from the first bearing 70 toward the seat portion 29, and the valve body 25 and the seat portion are displaced as the shaft 20 is displaced in the central axis O direction. 29, the opening area Av of the variable throttle portion 84 defined by the variable aperture portion 29 is changed, and the maximum protrusion amount L that the valve body 25 protrudes from the first bearing 70 is a predetermined value with respect to the outer diameter d of the shaft 20. The configuration is set to the following range.

  Based on the above configuration, the distal end portion of the shaft 20 is supported by the first bearing 70 with respect to the sleeve 30, and the proximal end portion of the shaft 20 is supported by the second bearing 75 via the plunger 60, whereby the shaft The support rigidity of the valve body 25 provided at the distal end portion of the valve body 20 is sufficiently secured, and the concentricity of the valve body 25 with respect to the seat portion 29 is changed by the force of the working fluid that the valve body 25 receives in the process of moving the shaft 20 It is possible to suppress the occurrence of an inflection point at which the flow rate Q of the working fluid changes rapidly according to the excitation current.

  In the present embodiment, the sleeve 30 has a small-diameter inner peripheral surface 31a and a large-diameter inner peripheral surface 31b that are formed in a cylindrical shape and are sequentially expanded in diameter, and the small-diameter inner peripheral surface 31a and the large-diameter inner peripheral surface 31b. The first bearing 70 is fixed by being press-fitted into the large-diameter inner peripheral surface 31b.

  Based on the above-described configuration, the first bearing 70 is restricted from approaching the seat portion 29 by the tip portion 70c of the first bearing 70 coming into contact with the sleeve step portion 31c.

  In the present embodiment, the sleeve 30 has a configuration in which the valve inlet port 18 is formed so as to open over the small-diameter inner peripheral surface 31a and the large-diameter inner peripheral surface 31b.

  Based on the above-described configuration, the first bearing 70 is restricted from approaching the seat portion 29 when the tip portion 70c abuts on the sleeve step portion 31c, whereby the first bearing 70 is connected to the valve inlet port. Large blockage of the 18 openings is avoided.

  In the present embodiment, the first bearing 70 is arranged close to the seat portion 29 so as to partially close the opening of the valve inlet port 18 with respect to the sleeve 30.

  Based on the above configuration, the first bearing 70 is disposed closer to the seat portion 29 than the opening end of the valve inlet port 18, and the maximum protruding amount L of the shaft 20 is less than a predetermined value with respect to the outer diameter d of the shaft 20. It becomes possible to set the range.

  Not limited to this, the first bearing 70 may be downsized and the first bearing 70 may be disposed away from the opening of the valve inlet port 18 with respect to the sleeve 30. Accordingly, the first bearing 70 does not partially block the opening of the valve inlet port 18 with respect to the sleeve 30, and the opening area of the valve inlet port 18 is increased.

  In the present embodiment, the valve body 25 includes a tapered valve body portion 26 tapered in a conical shape, and a straight valve body portion 27 extending in a columnar shape from a base end (taper shoulder portion) of the tapered valve body portion 26. And the tapered valve body portion 26 of the valve body 25 faces the seat portion 29 in the opening area variable region, and the straight valve body portion 27 of the valve body 25 faces the seat portion 29 in the constant minimum opening area region. It was.

  Based on the above configuration, since the straight valve element 27 of the valve element 25 is inserted into the seat part 29 in the region where the minimum opening area is constant, the opening area Av of the variable restrictor 84 changes as the valve element 25 is displaced. do not do. For this reason, it can suppress that the opening area Av of the variable throttle part 84 changes with the error (variation of the minimum stroke of the shaft 20) of the minimum valve opening degree of the valve body 25.

  As a result, the electromagnetic proportional control valve 2 can set a large dimensional tolerance of each part that determines the minimum valve opening, thereby reducing the cost of the product.

  In the present embodiment, the spring biasing means includes the first spring 11 that biases the shaft 20 in the valve closing direction and the second spring 12 that biases the shaft 20 in the valve opening direction.

  In the present embodiment, the second bearing 75 is formed of a nonmagnetic resin sheet material.

  Based on the above configuration, the plunger 60 can be slidably supported on the inner peripheral surface 33 a of the sleeve 30 surrounding the plunger 60.

  In the present embodiment, the solenoid 15 is filled with a resin bobbin 50, a coil 52 wound around the bobbin 50, a coil case 10 that accommodates the coil 52, and a space between the coil case 10 and the coil 52. The mold resin 54 is formed by molding a resin having a melting point higher than that of the bobbin 50 and is fused to the bobbin 50 at the time of molding.

  Based on the above configuration, the molding resin 54 enters the gap between the bobbin 50 and the coil 52 and the like so as to cover the circumference of the coil 52 without any gap, thereby insulating and waterproofing the solenoid 15.

  In the present embodiment, an adjuster bolt 40 for adjusting the spring force of the first spring 11 is provided. The adjuster bolt 40 is screwed into a screw hole 90a in the base 90 and a base of the screw portion 40a. And a step portion 40b formed with an enlarged diameter at the end, and is configured to be inserted into the base 90 from the sleeve 30 side with respect to the base 90 and screwed into a screw hole 90a in the base 90.

  Based on the above configuration, the adjuster bolt 40 is inserted into the base 90 from the sleeve 30 side with respect to the base 90, the screw portion 40a is screwed into the screw hole 90a of the base 90, and the step portion 40b is the end portion of the screw hole 90a. , The adjuster bolt 40 is prevented from falling off the base 90.

  The present embodiment is a power steering device that applies a steering force to a wheel, and includes an electromagnetic proportional control valve 2 and a pressure compensation valve 6 that keeps the differential pressure ΔP across the electromagnetic proportional control valve 2 substantially constant. The electromagnetic proportional control valve 2 is configured to control the flow rate of the working fluid supplied to the power steering system 7 that generates the steering force of the wheels.

  Based on the above configuration, the flow rate of the working fluid supplied to the power steering system 7 is accurately controlled by the electromagnetic proportional control valve 2.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The electromagnetic proportional control valve of the present invention is not limited to an electromagnetic proportional control valve used in a power steering apparatus, but can be used in an electromagnetic proportional control valve used in industrial machinery and the like.

DESCRIPTION OF SYMBOLS 1 Power steering apparatus 2 Electromagnetic proportional control valve 6 Pressure compensation valve 7 Power steering system 11 1st spring 12 2nd spring 15 Solenoid 16 Valve outlet port 18 Valve inlet port 20 Shaft 20a Shaft outer peripheral surface 25 Valve body 26 Taper valve body part 27 Straight valve body 29 Seat portion 30 Sleeve 31a Small diameter inner peripheral surface 31b Large diameter inner peripheral surface 31c Sleeve stepped portion 40 Adjuster bolt 40a Screw portion 40b Stepped portion 50 Bobbin 52 Coil 54 Mold resin 60 Plunger 60b Plunger outer peripheral surface 70 First bearing 70a Bearing surface 75 Second bearing 90 Base 90a Screw hole

Claims (8)

An electromagnetic proportional control valve whose valve opening is adjusted according to the excitation current,
A cylindrical sleeve constituting the magnetic path;
A cylindrical shaft;
A cylindrical plunger fixed to the shaft;
A first bearing that slidably supports the outer peripheral surface of the shaft with respect to the sleeve;
A second bearing that slidably supports the outer peripheral surface of the plunger with respect to the sleeve;
Spring biasing means for biasing the shaft;
A solenoid that drives the plunger by magnetic force, and
The sleeve is
A valve inlet port communicating with the pressure source side;
A valve outlet port communicating with the load side;
A seat portion where the valve outlet port opens,
The shaft has a valve body protruding from the first bearing toward the seat portion,
As the shaft is displaced in the axial direction, the opening area of the variable throttle portion defined between the valve body and the seat portion is changed,
The sleeve is
A small-diameter inner peripheral surface and a large-diameter inner peripheral surface having a cylindrical surface shape formed by expanding the diameter in order,
An annular sleeve step formed between the small-diameter inner peripheral surface and the large-diameter inner peripheral surface,
The first bearing is fixed to the large-diameter inner peripheral surface;
The electromagnetic proportional control valve, wherein the valve inlet port is formed so as to open over the small diameter inner peripheral surface and the large diameter inner peripheral surface.   2. The electromagnetic proportional control valve according to claim 1, wherein the first bearing is arranged close to the seat portion so as to partially close an opening portion of the valve inlet port with respect to the sleeve.   The electromagnetic proportional control valve according to claim 1 or 2, wherein the first bearing is disposed apart from an opening of the valve inlet port with respect to the sleeve. The valve body is
A tapered valve body portion tapered in a conical shape;
A straight valve body extending in a cylindrical shape from the base end of the taper valve body,
The tapered valve body portion faces the seat portion in the opening area variable region,
The electromagnetic proportional control valve according to any one of claims 1 to 3, wherein the straight valve body portion is opposed to the seat portion in a region where the minimum opening area is constant. The spring biasing means is
A first spring for urging the shaft in the valve closing direction;
The electromagnetic proportional control valve according to claim 1, further comprising a second spring that urges the shaft in a valve opening direction.   The electromagnetic proportional control valve according to any one of claims 1 to 5, wherein the second bearing is formed of a non-magnetic resin sheet material. The solenoid is
A resin bobbin,
A coil wound around this bobbin,
A coil case that houses the coil;
A mold resin filled and solidified between the coil case and the coil,
This mold resin
Formed by molding a resin having a higher melting point than the bobbin,
The electromagnetic proportional control valve according to claim 1, wherein the electromagnetic proportional control valve is fused to the bobbin at the time of molding. An adjuster bolt for adjusting the spring force of the first spring;
This adjuster bolt
A screw portion that is screwed into a screw hole in a cylindrical base constituting the magnetic path;
A stepped portion formed by expanding the diameter at the base end of the screw portion,
The electromagnetic proportional control valve according to claim 1, wherein the electromagnetic proportional control valve is inserted into the base from the sleeve side with respect to the base and is screwed into a screw hole in the base.

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