Patent Publication Number: US-2022221080-A1

Title: Solenoid valve

Description:
TECHNICAL FIELD 
     The present invention relates to, for example, a solenoid valve used for hydraulic control of a hydraulic circuit. 
     BACKGROUND ART 
     A solenoid valve for hydraulic control in the related art includes a spool valve unit that includes a spool having a columnar shape and accommodated in a sleeve, and a solenoid unit that includes a solenoid case accommodating a solenoid molded body in which a stator, a plunger, and a coil are covered with resin, and drives the spool in an axial direction, and can be disposed between a pressure source such as a pump or an accumulator and a supply destination to drive the spool, thus to supply a fluid, of which the pressure or flow rate is regulated, to the supply destination. 
     For example, in a solenoid valve disclosed in Patent Citation 1, a recessed portion extending in an axial direction is formed in a spool side end portion of a plunger, and an end portion of a rod is fitted and connected to the recessed portion. When a coil is energized and excited, the plunger and the rod can be attracted to a stator to cause a spool to move in the axial direction, thus to switch communication states of various ports formed in a sleeve. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Citation 1: JP 2009-203991 A (page 6 and FIG. 1) 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the solenoid valve of Patent Citation 1, the size can be reduced by increasing the volume of the plunger itself to cause magnetic fluxes to act efficiently, but when the end portion of the rod is fitted into the recessed portion of the plunger, air remains inside the recessed portion in a compressed state. Accordingly, not only there is a problem that due to a rise in temperature, the compressed air inside the recessed portion expands to cause the rod to move from the recessed portion in a pullout direction, but also there is a problem that when used in liquid, buoyancy is generated by the air remaining inside the recessed portion, so that a desired accuracy of the solenoid valve cannot be obtained. 
     The present invention has been made in light of such problems, and an object of the present invention is to provide a solenoid valve that is small in size and is highly accurate. 
     Solution to Problem 
     In order to solve the foregoing problems, according to the present invention, there is provided a solenoid valve in which a rod is moved by a plunger that is driven to come into contact with and separate from a stator by electromagnetic force, to cause a valve body, which opens and closes a valve, to reciprocate. A recessed portion is formed in the plunger, and an end portion of the rod disposed between the plunger and the valve body is fitted into the recessed portion. A communication path through which a space inside the recessed portion and a space outside the plunger communicate with each other is formed between the rod and the recessed portion. According to the aforesaid feature of the present invention, since the space inside the recessed portion communicates with the space outside the plunger through the communication path, a fluid of an assembly atmosphere can be avoided from remaining between the recessed portion and the rod, and the accuracy of operation of the plunger can be improved while the size is reduced. 
     It may be preferable that the communication path is partitioned off by cutouts of the rod. According to this preferable configuration, an effective region of magnetic fluxes in the plunger can be formed in a well-balanced manner. 
     It may be preferable that the cutouts of the rod are be disposed at equal intervals in a circumferential direction. According to this preferable configuration, the fluid easily flows in and out from the recessed portion, and the fluid of the assembly atmosphere is unlikely to remain inside the recessed portion. 
     It may be preferable that a fitting side end portion of the rod is formed in a tapered shape. According to this preferable configuration, the rod is easily fitted into the recessed portion, and the fluid can smoothly move between the space between the recessed portion and the rod and the space outside the plunger. 
     It may be preferable that the rod has a flange portion which comes into contact with the plunger. According to this preferable configuration, when the large diameter portion comes into contact with an end surface of the plunger, the depth of fitting of the rod into the recessed portion can be determined. 
     It may be preferable that an edge portion of the recessed portion has a tapered surface inclined toward a center of the recessed portion. According to this preferable configuration, the rod is easily fitted into the recessed portion along the tapered surface. 
     It may be preferable that the communication path is partitioned off by the tapered surface of the recessed portion and a cutout of the rod. According to this preferable configuration, since the communication path is partitioned off by the cutout of the rod and the tapered surface of the plunger, the sizes of the cutout and the tapered surface can be reduced, and the strength of the rod and the plunger can be secured. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a solenoid valve according to a first embodiment of the present invention. 
         FIG. 2  is cross-sectional view illustrating the solenoid valve according to the first embodiment. Incidentally, for convenience of explanation, a spool and a rod are illustrated in a side view. 
         FIG. 3A  is a side view illustrating the structure of the rod in the first embodiment, and  FIG. 3B  is a view of a protruding portion of the rod as seen in an axial direction. 
         FIG. 4  is a view illustrating a modification example of the rod in the first embodiment. 
         FIG. 5  is a cross-sectional view illustrating a solenoid valve according to a second embodiment of the present invention. Incidentally, for convenience of explanation, a spool and a rod are illustrated in a side view. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Modes for implementing a solenoid valve according to the present invention will be described below based on embodiments. 
     First Embodiment 
     A solenoid valve according to a first embodiment of the present invention will be described with reference to  FIGS. 1 to 3 . Hereinafter, a description will be given based on the assumption that the right side of the drawing sheet of  FIG. 2  is one end side in an axial direction of the solenoid valve and the left side of the drawing sheet of  FIG. 2  is the other end side in the axial direction of the solenoid valve. 
     As illustrated in  FIG. 1 , a solenoid valve  1  of the present embodiment is a spool type solenoid valve, and is used in, for example, a hydraulically controlled apparatus such as an automatic transmission of a vehicle. Incidentally, the solenoid valve  1  is used as a so-called oil-immersed solenoid valve that is attached to a mounting hole of a valve housing on an apparatus side in a horizontal direction, and is immersed in a hydraulic oil which is a liquid in the valve housing. 
     As illustrated in  FIGS. 1 and 2 , the solenoid valve  1  is configured such that a valve unit  2  which regulates the flow rate of a fluid, namely, a control fluid such as a hydraulic oil is integrally attached to a solenoid unit  3 . Incidentally,  FIG. 2  illustrates an off state of the solenoid valve  1 , in which a coil  34  of a solenoid molded body  31  is not energized. 
     First, the structure of the valve unit  2  will be described. As illustrated in  FIGS. 1 and 2 , the valve unit  2  includes a sleeve  21  provided with openings of various ports such as an input port  24 , an output port  25 , a discharge port  26 , a drain port  27 , and a feedback port  28  that are connected to flow paths provided in the mounting hole of the valve housing, a spool  22  as a valve body that is liquid-tightly accommodated in a through-hole  21   a  formed in the axial direction on an inner diameter side of the sleeve  21 , a spring  29  that has a coil shape and biases the spool  22  to the other side in the axial direction, and a retainer  23  that holds the spring  29 . 
     In the sleeve  21 , the discharge port  26 , the output port  25 , the input port  24 , the feedback port  28 , and the drain port  27  are formed in order from the one end side in the axial direction toward the other end side in the axial direction. The spool  22  is reciprocatable in the axial direction, and the spool  22  is reciprocated in the axial direction, so that communication states of the various ports are changed to control the pressure or flow rate of the hydraulic oil. Incidentally, the sleeve  21 , the spool  22 , and the retainer  23  are made of a material such as aluminum, iron, stainless steel, or resin. 
     Next, the structure of the solenoid unit  3  will be described. As illustrated in  FIG. 2 , the solenoid unit  3  mainly includes a solenoid case  30  made of a metallic material such as iron having magnetic properties, the solenoid molded body  31  accommodated in the solenoid case  30 , a stator  32  disposed inside the solenoid molded body  31 , and a plunger  4  disposed so as to be movable in the axial direction to the other side in the axial direction of the stator  32 . 
     The solenoid molded body  31  is formed by molding the coil  34  with a resin  35 , and control current is supplied to the coil  34  from a connector of a connector portion  35   a  that extends to the outside from an opening portion  30   j  provided on an outer diameter side of the solenoid case  30 . The solenoid molded body  31  is integrally formed on an outer diameter side of the stator  32 . In addition, an opening is provided at the other end in the axial direction of the solenoid case  30 , and a lid member  10  is fixed by caulking, so that the opening is closed. 
     The stator  32  is a tubular body having a through-hole  32   a  in a central portion thereof, the through-hole  32   a  penetrating therethrough in the axial direction, and is made of a metallic material such as iron having magnetic properties. A recessed portion  32   b  which is recessed to the one end side in the axial direction is formed at the other end in the axial direction of the stator  32 , and the recessed portion  32   b  communicates with the through-hole  32   a . In addition, the other end portion in the axial direction of the spool  22  is in contact with an end surface of the stator  32  on the one end side in the axial direction, so that the movement of the spool  22  to the other side in the axial direction is restricted. 
     In addition, a first tubular body  7  made of a non-magnetic material is provided on the other end side in the axial direction of the stator  32 , a second tubular body  8  made of a magnetic material is provided on the other end side in the axial direction of the first tubular body  7 , and a third tubular body  9  made of a magnetic material is provided over the first tubular body  7  and the second tubular body  8  inside the first tubular body  7  and the second tubular body  8 . An inner peripheral surface of the third tubular body  9  is processed into a low frictional surface, and has high slidability with respect to the plunger  4 . 
     The plunger  4  is made of a metallic material such as iron having magnetic properties to have a columnar shape, and is disposed so as to be slidable on the inner peripheral surface of the third tubular body  9 . An outer peripheral surface of the plunger  4  and the inner peripheral surface of the third tubular body  9  are slightly separated from each other, and almost no fluid passes through the gap. 
     A space S 1  as a space outside the plunger  4  is formed on one side in the axial direction of the plunger  4 , and a space S 2  is formed on the other side in the axial direction of the plunger  4 . Specifically, the space S 1  is partitioned off by the plunger  4 , the through-hole  32   a  of the stator  32 , the recessed portion  32   b , and the spool  22 , and the space S 2  is partitioned off by the plunger  4 , the second tubular body  8 , and the lid member  10 . 
     A recessed portion  4   a  which is recessed to the other end side in the axial direction is formed at one end in the axial direction of the plunger  4 , and a protruding portion  53  as an end portion of a rod  5  on the other end side in the axial direction is fitted and fixed to the recessed portion  4   a , the rod  5  being inserted into the through-hole  32   a  of the stator  32 . A tapered surface  4   b  which is inclined toward a central portion of the recessed portion  4   a  is formed in an edge portion of the recessed portion  4   a . In addition, a tip of the rod  5  on the one end side in the axial direction is in contact with an end surface of the spool  22  on the other end side in the axial direction. Namely, the rod  5  is disposed in the space S 1 . Incidentally, the tip of the rod  5  on the one end side in the axial direction may be fixed to the end surface of the spool  22  on the other end side in the axial direction. Further incidentally, the tip of the rod  5  on the one end side in the axial direction may not be in contact with the end surface of the spool  22  on the other end side in the axial direction. 
     Next, the structure of the rod  5  will be described. As illustrated in  FIGS. 2 and 3 , the rod  5  is provided with a base portion  51  that has a columnar shape, is made of a non-magnetic material such as resin or rubber, and is inserted into the through-hole  32   a  of the stator  32 , a flange portion  52  as a large diameter portion that projects from the other end portion in the axial direction of the base portion  51  to the outer diameter side, and the protruding portion  53  that has a small diameter and protrudes from an inner diameter portion of an end surface of the base portion  51  to the other side in the axial direction, the end surface being on the other end side in the axial direction. 
     A fitting side end portion  53   b  having a tapered surface inclined toward a central axis of the protruding portion  53  is formed in the other end portion in the axial direction of the protruding portion  53 , so that the other end portion in the axial direction has a tapered shape. In addition, two cutouts  53   c  extending linearly in the axial direction are disposed at equal intervals on an outer periphery of the protruding portion  53  in a circumferential direction. Incidentally, in the cutout  53   c , a bottom surface is formed in a flat surface shape, an end portion on the one end side in the axial direction is formed in an outer peripheral surface  53   a  of the protruding portion  53  at a position that is separated from an end surface of the flange portion  52  on the other end side in the axial direction to the other end side in the axial direction, and the other end portion in the axial direction is formed to cut out a part of the fitting side end portion  53   b . In addition, both sides of a circular plate, which correspond to the cutouts  53   c  and  53   c , are cut out, so that side surfaces  52   a  and  52   a  (refer to  FIG. 3 ) having a linear shape are formed in the flange portion  52 . 
     As illustrated in  FIG. 2 , the protruding portion  53  of the rod  5  is fitted and fixed to the recessed portion  4   a  of the plunger  4 . Namely, the outer peripheral surface  53   a  of the protruding portion  53  and an inner peripheral surface of the recessed portion  4   a  of the plunger  4  are in press contact with each other. Since the other end portion in the axial direction of the protruding portion  53  is tapered due to the fitting side end portion  53   b  being formed, when the protruding portion  53  is fitted into the recessed portion  4   a , the tapered surface of the fitting side end portion  53   b  is guided by the edge portion of the recessed portion  4   a  of the plunger  4 , so that the protruding portion  53  is easily fitted into the recessed portion  4   a.    
     In addition, when the protruding portion  53  is fitted into the recessed portion  4   a  by a predetermined length, the end surface of the flange portion  52 , which has projected to the outer diameter side from the protruding portion  53 , on the other end side in the axial direction comes into contact with an end surface of the plunger  4  on the one end side in the axial direction (particularly, refer to  FIG. 2 ). As described above, since the end surface of the flange portion  52  on the other end side in the axial direction is in contact with the end surface of the plunger  4  on the one end side in the axial direction, the fitting of the rod  5  is restricted. Therefore, the depth of fitting of the rod  5  into the plunger  4  can be determined, and the rod  5  can be accurately fixed to the plunger  4 . In addition, during production of the rod  5 , since a rounded portion (not illustrated) which is formed in a continuous portion between the end surface of the flange portion  52  on the other end side in the axial direction and one end portion in the axial direction of the outer peripheral surface  53   a  of the protruding portion  53  is accommodated on the inner diameter side of the tapered surface  4   b  of the plunger  4 , the end surface of the flange portion  52  on the other end side in the axial direction can be reliably in contact with the end surface of the plunger  4  on the one end side in the axial direction, and the rod  5  can be more accurately fixed to the plunger  4 . 
     In addition, when the coil  34  is energized to generate magnetic force between the stator  32  and the plunger  4 , thus to cause the plunger  4  and the rod  5  to move to the one end side in the axial direction toward the stator  32 , an end surface of the flange portion  52  of the rod  5  made of a non-magnetic material comes into contact with a bottom surface of the recessed portion  32   b  of the stator  32 , the end surface being on the one end side in the axial direction, so that the plunger  4  is prevented from adhering to the stator  32 . 
     As illustrated in an enlarged portion of  FIG. 2 , in a state where the protruding portion  53  of the rod  5  is fitted into the recessed portion  4   a  of the plunger  4 , a space S 3  is formed between a bottom portion of the recessed portion  4   a  and an end surface of the protruding portion  53  on the other end side in the axial direction. 
     Accordingly, in a state where the protruding portion  53  of the rod  5  is fitted into the recessed portion  4   a  of the plunger  4 , the space S 3  inside the recessed portion  4   a  of the plunger  4  and the space S 1  outside the plunger  4  are allowed to communicate with each other by a communication path P 1  that is partitioned off by the cutouts  53   c  of the rod  5 , a communication path P 2  that is partitioned off between the tapered surface  4   b  formed in the edge portion of the recessed portion  4   a  of the plunger  4  and the outer peripheral surface  53   a  of the protruding portion  53  of the rod  5 , and a communication path P 3  formed by a gap between the end surface of the flange portion  52  on the other end side in the axial direction and the end surface of the plunger  4  on the one end side in the axial direction. Therefore, a fluid (for example, the atmosphere) of an assembly atmosphere can be avoided from remaining in the space S 3  between the recessed portion  4   a  and the protruding portion  53  of the rod  5 , and the accuracy of operation of the plunger  4  and the rod  5  can be improved. In addition, since both the communication path P 1  and the communication path P 2  are provided, the size of each of the cutout  53   c  of the rod  5  and the tapered surface  4   b  of the plunger  4  can be reduced, and the strength of the rod  5  and the plunger  4  can be secured. 
     In addition, since the communication path P 1  is partitioned off by the cutouts  53   c  of the rod  5 , the plunger  4  can be formed in a uniform shape to reduce the size while forming an effective region of magnetic fluxes in the plunger  4  in a well-balanced manner. Further, since the two cutouts  53   c  are disposed at equal intervals in the circumferential direction, when the solenoid valve is immersed in the hydraulic oil in the valve housing, the hydraulic oil easily flows into the space S 3  inside the recessed portion  4   a  through one cutout  53   c , and the hydraulic oil easily flows out through the other cutout  53   c , so that the fluid of the assembly atmosphere is unlikely to remain in the space S 3  inside the recessed portion  4   a.    
     In addition, since the protruding portion  53  of the rod  5  has a tapered shape due to the fitting side end portion  53   b  having a tapered surface being formed in the other end portion in the axial direction, the hydraulic oil or the fluid of the assembly atmosphere can smoothly move between the space S 3  inside the recessed portion  4   a  and the space S 1  outside the plunger  4 . 
     In addition, since the flange portion  52  is provided with the side surfaces  52   a  and  52   a  formed by cutting out both the sides of the circular plate, which correspond to the cutouts  53   c  and  53   c , the distance in the radial direction from the cutouts  53   c  and  53   c  to the space S 1  outside the plunger  4  can be reduced. Therefore, the hydraulic oil or the fluid of the assembly atmosphere can smoothly move to and from the space S 1  outside the plunger  4  through the communication path P 3  (refer to  FIG. 2 ) formed by the gap between the end surface of the flange portion  52  on the other end side in the axial direction and the end surface of the plunger  4  on the one end side in the axial direction. 
     Incidentally, as a modification example of the rod  5 , as illustrated in  FIG. 4 , a communication path P 4  which is partitioned off by grooves  52   b  and  52   b  extending from the side surfaces  52   a  and  52   a  to the vicinity of the outer peripheral surface  53   a  of the protruding portion  53  may be formed in the end surface of the flange portion  52  on the other end side in the axial direction to correspond to the cutouts  53   c  and  53   c . Accordingly, the cross-sectional area of the flow path can be expanded by the communication path P 4  partitioned off by the grooves  52   b  and  52   b , in addition to the communication path P 3  formed by the gap between the end surface of the flange portion  52  on the other end side in the axial direction and the end surface of the plunger  4  on the one end side in the axial direction. Therefore, the hydraulic oil or the fluid of the assembly atmosphere can more smoothly move to and from the space S 1  outside the plunger  4 . 
     Second Embodiment 
     Next, a solenoid valve according to a second embodiment of the present invention will be described with reference to  FIG. 5 . Incidentally, the description of the same configurations and duplicated configurations as those of the first embodiment will be omitted. 
     In a solenoid valve  101  of the second embodiment, as illustrated in  FIG. 5 , an edge portion of a recessed portion  104   a  of a plunger  104  is formed at a right angle with respect to an end surface of the plunger  104  on the one end side in the axial direction. In addition, in a cutout  153   c  formed in a protruding portion  153  as an end portion of a rod  105 , one end portion in the axial direction is formed in an outer peripheral surface  153   a  of the protruding portion  153  to extend to the position of an end surface of a flange portion  152  as a large diameter portion, the end surface being on the other end side in the axial direction, and the other end portion in the axial direction is formed to cut out a part of a tapered surface forming a fitting side end portion  153   b.    
     Accordingly, in a state where the protruding portion  153  of the rod  105  is fitted into the recessed portion  104   a  of the plunger  104 , the space S 3  inside the recessed portion  104   a  of the plunger  104  and the space S 1  outside the plunger  104  are allowed to communicate with each other by a communication path P 5  that is partitioned off by the cutout  153   c  of the rod  105 , and the communication path P 3  formed by a gap between the end surface of the flange portion  152  on the other end side in the axial direction and the end surface of the plunger  104  on the one end side in the axial direction. Therefore, the fluid of the assembly atmosphere can be avoided from remaining in the space S 3  between the recessed portion  104   a  and the protruding portion  153  of the rod  105 , and the accuracy of operation of the plunger  104  and the rod  105  can be improved. 
     Incidentally, the grooves  52   b  and  52   b  (refer to  FIG. 4 ) may be formed in the flange portion  152  of the rod  105  as in the modification example of the first embodiment. 
     The embodiments of the present invention have been described above with reference to the drawings; however, the specific configuration is not limited to the embodiments, and the present invention also includes changes or additions that are made without departing from the concept of the present invention. 
     For example, in the embodiments, the configuration where a part of the communication path is partitioned off by the cutouts formed in the protruding portion of the rod has been described; however, the present invention is not limited thereto, and a part of the communication path may be partitioned off by a groove formed in the inner peripheral surface of the recessed portion of the plunger. 
     In addition, a case where two cutouts formed in the protruding portion of the rod are disposed at equal intervals in the circumferential direction has been described; however, the number of the cutouts formed in the protruding portion may be freely set, and the cutouts may not be disposed at equal intervals in the circumferential direction. In addition, the bottom surface of the cutout is not limited to a flat surface shape, and may have, for example, a V shape, a round shape, or the like. 
     In addition, the other end portion in the axial direction of the rod may be formed in a linear shape without a tapered surface. 
     In addition, the shape of the flange portion as a large diameter portion of the rod may be freely configured. 
     In addition, the flange portion as a large diameter portion may not be formed in the rod, and in this case, for example, it is preferable that a damper member having a ring shape and made of a non-magnetic material such as resin or rubber is provided in a bottom portion of the recessed portion  32   b  of the stator  32 . 
     In addition, the spaces S 1  and S 2  before and after the plunger may communicate with each other through communication means such as a through-hole penetrating through the plunger in the axial direction. 
     In addition, in the embodiments, the spool type solenoid valve using the spool in the valve body has been described; however, the present invention is not limited thereto, and may be applied to a solenoid valve using a globe valve, a gate valve, or the like. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Solenoid valve 
               2  Valve unit 
               3  Solenoid unit 
               4  Plunger 
               4   a  Recessed portion 
               4   b  Tapered surface 
               5  Rod 
               7  First tubular body 
               8  Second tubular body 
               9  Third tubular body 
               10  Lid member 
               21  Sleeve 
               22  Spool (valve body) 
               32  Stator 
               51  Base portion 
               52  Flange portion 
               52   a  Side surface 
               52   b  Groove 
               53  Protruding portion (end portion) 
               53   a  Outer peripheral surface 
               53   b  Fitting side end portion 
               53   c  Cutout 
               101  Solenoid valve 
               104  Plunger 
               104   a  Recessed portion 
               105  Rod 
               152  Flange portion 
               153  Protruding portion (end portion) 
               153   a  Outer peripheral surface 
               153   b  Fitting side end portion 
               153   c  Cutout 
             S 1  to S 3  Space 
             P 1  to P 5  Communication path