Abstract:
An electromagnetic valve includes a valve body having a passage and a valve seat, a valve member engaging/disengaging from the seat to stop/allow a fluid flow through the passage, an urging member urging the valve member, a movable part reciprocating in axial direction with valve member, a connector made of magnetic material and accommodating movable part to allow its reciprocation, a stator made of magnetic material and constituting a magnetic circuit with the movable part and connector to attract the movable part, a coil generating magnetism attracting movable part to stator when energized, a terminal connected to coil for supplying power, and a resin-formed member including an accommodating member embedding the coil and terminal, and a nonmagnetic member made of nonmagnetic material and located radially inward of coil and between the connector and stator for preventing a short circuit. The accommodating member and nonmagnetic member are formed integrally from resin.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on and incorporates herein by reference Japanese Patent Application No. 2008-142937 filed on May 30, 2008. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to an electromagnetic valve. In particular, the present invention relates to an electromagnetic valve in which a nonmagnetic material that prevents a short circuit of a line of magnetic force is formed from resin. 
         [0004]    2. Description of Related Art 
         [0005]    Conventionally, an electromagnetic valve that prevents a short circuit of a line of magnetic force by using a nonmagnetic member for a part of a magnetic circuit to ensure attraction force is disclosed (see, for example, JP2001-295720A). However, according to the above configuration, the magnetic circuit does not function without at least three members, i.e., a flange made of a magnetic material, an attraction member made of a magnetic material, and an intermediate member made of a nonmagnetic material, in addition to a movable part. Accordingly, there is a problem that the number of components is large. Moreover, because both ends of the nonmagnetic member need to be fixed liquid-tightly to the magnetic member, they have been sealed and fixed by welding or the like. Consequently, there is a problem that the cost of equipment and operating expenses are great. 
         [0006]    An electromagnetic valve which minimizes a short circuit of a line of magnetic force by using a magnetic restrictor to ensure attraction force is disclosed (see, for example, JP60-256550A). In this electromagnetic valve, a magnetic circuit is made up of a single member besides a core. However, a difference occurs in attraction force if the magnetic restrictor part is not precisely formed. Therefore, thickness and length of the magnetic restrictor part need to be precisely formed. Furthermore, there is a problem that it is easy to deform when an injector and the like are attached to an engine or pump sine the magnetic restrictor part has low rigidity. 
         [0007]    An electromagnetic valve using a composite magnetic pipe is disclosed (see, for example, JP7-11397A corresponding to U.S. Pat. No. 6,390,443B1). In the above electromagnetic valve, by using the composite magnetic pipe, a magnetic circuit having “magnetism-nonmagnetism-magnetism” is constituted of a single member in addition to a core. Since magnetic properties of a magnetic part of the composite magnetic material are low compared to a magnetic member used for other methods, there is a problem that attraction force is small when their sizes are the same. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention addresses the above disadvantages. Thus, it is an objective of the present invention to simplify a process of formation of an electromagnetic valve and to provide an electromagnetic valve including a magnetic circuit having good magnetic properties. 
         [0009]    To achieve the objective of the present invention, there is provided an electromagnetic valve including a valve body, a valve member, an urging member, a movable part, a connector, a stator, a coil, a terminal, and a resin-formed member. The valve body has a first fluid passage and a valve seat. The valve member is configured to engage or disengage from the valve seat so as to stop or allow a flow of fluid through the first fluid passage respectively. The urging member is configured to urge the valve member in a direction in which the flow of fluid is stopped or allowed. The movable part is configured to reciprocate in an axial direction thereof together with the valve member. The connector is made of a magnetic material and accommodates the movable part so as to allow reciprocating movement of the movable part. The stator is made of a magnetic material and constitutes a magnetic circuit together with the movable part and the connector so as to attract the movable part. The coil is configured to generate magnetic force upon energization of the coil. The magnetic force attracts the movable part to the stator. The terminal is electrically connected to the coil for supplying a drive current to the coil so as to energize the coil. The resin-formed member includes an accommodating member and a nonmagnetic member. The coil and the terminal are embedded in the accommodating member. The nonmagnetic member is made of a nonmagnetic material and is located radially inward of the coil as well as between the connector and the stator for preventing a magnetic short circuit between the connector and the stator. The accommodating member and the nonmagnetic member are formed integrally from resin. 
         [0010]    To achieve the objective of the present invention, there is also provided a fluid pump including an electromagnetic valve and a pump part. The electromagnetic valve includes a valve body, a valve member, an urging member, a movable part, a connector, a stator, a coil, a terminal, and a resin-formed member. The valve body has a first fluid passage and a valve seat. The valve member is configured to engage or disengage from the valve seat so as to stop or allow a flow of fluid through the first fluid passage respectively. The urging member is configured to urge the valve member in a direction in which the flow of fluid is allowed. The movable part is configured to reciprocate in an axial direction thereof together with the valve member. The connector is made of a magnetic material and accommodates the movable part so as to allow reciprocating movement of the movable part. The stator is made of a magnetic material and constitutes a magnetic circuit together with the movable part and the connector so as to attract the movable part. The coil is configured to generate magnetic force upon energization of the coil. The magnetic force attracts the movable part to the stator. The terminal is electrically connected to the coil for supplying a drive current to the coil so as to energize the coil. The resin-formed member has an accommodating member and a nonmagnetic member. The coil and the terminal are embedded in the accommodating member. The nonmagnetic member is made of a nonmagnetic material and is located radially inward of the coil as well as between the connector and the stator for preventing a magnetic short circuit between the connector and the stator. The accommodating member and the nonmagnetic member are formed integrally from resin. The pump part includes a piston and a cylinder body. The piston is configured to pressurize fluid which flows from the electromagnetic valve. The cylinder body accommodates the piston so as to allow sliding reciprocation of the piston. 
         [0011]    To achieve the objective of the present invention, there is further provided a fluid injection system including an electromagnetic valve. The electromagnetic valve includes a valve body, a valve member, an urging member, a movable part, a connector, a stator, a coil, a terminal, and a resin-formed member. The valve body has a first fluid passage, a valve seat, and a nozzle hole communicating with the first fluid passage. The valve member is configured to engage or disengage from the valve seat so as to stop or allow a flow of fluid through the first fluid passage respectively. The urging member is configured to urge the valve member in a direction in which the flow of fluid is stopped. The movable part is configured to reciprocate in an axial direction thereof together with the valve member. The connector is made of a magnetic material and accommodates the movable part so as to allow reciprocating movement of the movable part. The stator is made of a magnetic material and constitutes a magnetic circuit together with the movable part and the connector so as to attract the movable part. The coil is configured to generate magnetic force upon energization of the coil. The magnetic force attracts the movable part to the stator. The terminal is electrically connected to the coil for supplying a drive current to the coil so as to energize the coil. The resin-formed member has an accommodating member and a nonmagnetic member. The coil and the terminal are embedded in the accommodating member. The nonmagnetic member is made of a nonmagnetic material and is located radially inward of the coil as well as between the connector and the stator for preventing a magnetic short circuit between the connector and the stator. The accommodating member and the nonmagnetic member are formed integrally from resin. The stator has a cylindrical shape and includes a second fluid passage communicating with the first fluid passage inside the stator. 
         [0012]    Moreover, to achieve the objective of the present invention, there is provided a fluid injection system including an electromagnetic valve. The electromagnetic valve includes a valve body, a valve member, an urging member, a movable part, a connector, a stator, a coil, a terminal, a resin-formed member, and a nonmagnetic member. The valve body has a first fluid passage, a valve seat, and a nozzle hole communicating with the first fluid passage. The valve member is configured to engage or disengage from the valve seat so as to stop or allow a flow of fluid through the first fluid passage respectively. The urging member is configured to urge the valve member in a direction in which the flow of fluid is stopped. The movable part is configured to reciprocate in an axial direction thereof together with the valve member. The connector is made of a magnetic material and accommodates the movable part so as to allow reciprocating movement of the movable part. The stator is made of a magnetic material and constitutes a magnetic circuit together with the movable part and the connector so as to attract the movable part. The coil is configured to generate magnetic force upon energization of the coil. The magnetic force attracts the movable part to the stator. The terminal is electrically connected to the coil for supplying a drive current to the coil so as to energize the coil. The resin-formed member has an accommodating member in which the coil and the terminal are embedded. The nonmagnetic member is made of a nonmagnetic material and is located radially inward of the coil as well as between the connector and the stator for preventing a magnetic short circuit between the connector and the stator. The stator has a cylindrical shape and includes a second fluid passage communicating with the first fluid passage inside the stator. The resin-formed member includes a third fluid passage communicating with the second fluid passage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which: 
           [0014]      FIG. 1  is a sectional view illustrating an electromagnetic valve according to a first embodiment of the invention; 
           [0015]      FIG. 2  is a sectional view illustrating a high pressure pump using the electromagnetic valve of the first embodiment; 
           [0016]      FIG. 3A  is a diagram illustrating a method of forming a metal resin complex according to the first embodiment; 
           [0017]      FIG. 3B  is a diagram illustrating the method of forming the metal resin complex according to the first embodiment; 
           [0018]      FIG. 4  is a sectional view illustrating an electromagnetic valve according to a second embodiment of the invention; 
           [0019]      FIG. 5  is a sectional view illustrating an injector according to a third embodiment of the invention; 
           [0020]      FIG. 6  is a sectional view illustrating an injector according to a fourth embodiment of the invention; and 
           [0021]      FIG. 7  is a sectional view illustrating an injector according to a fifth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    Embodiments of the present invention are described below with reference to accompanying drawings. 
       First Embodiment 
       [0023]      FIG. 1  to  FIG. 3B  illustrate an electromagnetic valve  1  according to a first embodiment of the invention. The electromagnetic valve  1  is used as a fuel regulating valve of a high pressure supply pump for, for example, a gasoline cylinder direct-injection engine. The electromagnetic valve  1  includes a driving force generating part  10 , a connector  20 , a housing  30 , a stator  40 , a movable part  50 , a coil spring  55  as an urging member, a valve body  60  as a valve body, a valve member  70 , and a resin forming member  80 . The driving force generating part  10  includes a bobbin  11 , a coil  12 , and a terminal  13 . The bobbin  11  is disposed radially outward of the stator  40  and the movable part  50 . The coil  12  is wound around the bobbin  11 . The terminal  13  is electrically connected to the coil  12 , and electric power from an external power is supplied to the coil  12  via the terminal  13 . 
         [0024]    The connector  20  is made of a magnetic material such as magnetic stainless steel, and includes a passage formation part  21  and a flanged portion  22 . The passage formation part  21  is cylindrically formed, and accommodates the movable part  50  so as to allow its reciprocative movement. The flanged portion  22  is formed in the shape of a plate having a thickness and projecting radially outward of the passage formation part  21 . 
         [0025]    The housing  30  is made of a magnetic material such as magnetic stainless steel, and includes a circular plate part  31  and a leg part  32 . A fixation hole  33  is formed on the circular plate part  31  in a shape of a cylindrical hole, and the stator  40  is press-fitted into the fixation hole  33 . The leg part  32  has an arc-shaped cross section along a part of an outer circumferential edge of the circular plate part  31 , and extends from the circular plate part  31  arranged generally parallel to the flanged portion  22  toward the flanged portion  22 . An extension-side front end surface of the leg  32  is in contact with the flanged portion  22 . 
         [0026]    The stator  40  and the movable part  50  are made of a magnetic material such as magnetic stainless steel, and together with the connector  20  and the housing  30 , constitute a magnetic circuit upon energization of the coil  12 . The stator  40  includes a first minor diameter part  41 , a major diameter portion  42 , and a second minor diameter part  43  in this order from its one end part side toward the other end part side in the axial direction. The columnar first minor diameter part  41  is fit-fixed in the fixation hole  33  of the housing  30 . The second minor diameter part  43  having a cylindrical shape with a bottom portion includes a recess  44  that accommodates one end part of the coil spring  55 . 
         [0027]    The movable part  50  is disposed to be reciprocated radially inward of the passage formation part  21  of the connector  20 . The coil spring  55  is arranged between the stator  40  and the movable parts  50 . Urging force of the coil spring  55  is applied in a direction in which the movable part  50  is separated from the stator  40  and a seat part  71  is disengaged from a valve seat  64 . The movable part  50  is attracted in a direction of the stator  40  against the urging force of the coil spring  55  by magnetic attraction force generated upon energization of the coil  12 . 
         [0028]    The valve body  60  is formed in a cylindrical shape, and is attached coaxially with the passage formation part  21  of the connector  20 . The valve body  60  defines a first communicating hole  62  that communicates between a cylindrical internal passage  61  and a suction passage  94  (see  FIG. 2 ) formed in the outer circumference of the electromagnetic valve  1 , and a second communicating hole  63  that communicates with a fuel hole  76  of a stopper plate  75 . The first communicating hole  62 , the internal passage  61 , and the second communicating hole  63  communicate between the suction passage  94  and a pressurizing chamber  95  through the fuel hole  76 . The valve seat  64 , which the valve member  70  engages or disengages from, is formed between the internal passage  61  and the second communicating holes  63  on the valve body  60 . 
         [0029]    The valve member  70  is formed integrally with the movable part  50  on the opposite side of the movable part  50  from the stator  40 , and is disposed on inner circumferential sides of the passage formation part  21  and the valve body  60  coaxially therewith, so as to reciprocate together with the movable part  50  in the axial direction. The seat part  71  which engages or disengages from the valve seat  64  is formed on the valve member  70 . When the seat part  71  of the valve member  70  disengages from the valve seat  64 , the internal passage  61  and the second communicating hole  63  communicate therebetween. When the seat member  71  engages the valve seat  64 , the communication between the internal passage  61  and the second communicating hole  63  is closed. 
         [0030]    The stopper plate  75  is formed in the shape of a generally circular plate, and has the fuel hole  76 . The stopper plate  75  is held between the valve body  60  and a sleeve  77 , and welded to them. The sleeve  77  is formed in a generally cylindrical shape. The sleeve  77  is inserted in a housing main body  93  of a pump part  90  (see  FIG. 2 ). The first communicating hole  62 , the internal passage  61 , the second communicating hole  63 , and the fuel hole  76  constitute a “first fluid passage” 
         [0031]    A resin formed member  80  includes an accommodating member  81  and a nonmagnetic member  82 , and the accommodating member  81  and the nonmagnetic member  82  are integrally formed from resin. The bobbin  11 , the coil  12 , and the terminal  13  are embedded in the accommodating member  81 . The nonmagnetic portion  82  is located radially inward of the coil  12  as well as between the connector  20  and the stators  40 . The nonmagnetic portion  82  prevents a short circuit of magnetic flux between the connector  20  and the stators  40 . The driving force generating part  10 , the connector  20 , the stator  40 , and the resin formed member  80  are integrally formed as a metal resin complex  83 . A method of forming the metal resin complex  83  is described in greater detail hereinafter with reference to  FIG. 3A  and  FIG. 3B . 
         [0032]    An operation of the electromagnetic valve  1  is described below. When the energization of the coil  12  is stopped, magnetic attraction force is not produced between the stator  40  and the movable part  50 . Accordingly, the valve member  70  is displaced in the opposite direction from the stator  40  together with the movable part  50  by urging force of the coil spring  55 . In other words, when the energization of the coil  12  is stopped, the seat part  71  of the valve member  70  is disengaged from the valve seat  64 . Thus, the internal passage  61  and the second communicating hole  63  communicate with each other with the valve member  70  in engagement with the stopper plate  75 . 
         [0033]    Upon energization of the coil  12 , a magnetic circuit is formed in the stator  40 , the housing  30 , the connector  20  and the movable part  50  by a magnetic field generated in the coil  12 . Meanwhile, the nonmagnetic member  82  prevents the short circuit of magnetic flux between the connector  20  and the stators  40 . Accordingly, magnetic attraction force is generated between the stator  40  and the movable parts  50 . When the magnetic attraction force generated between the stator  40  and the movable parts  50  becomes larger than the urging force of the coil spring  55 , the movable part  50  and the valve member  70  are displaced integrally toward the stator  40  side. As a result, the seat part  71  engages the valve seat  64 . Therefore, the communication between the internal passage  61  and the second communicating hole  63  is closed. Meanwhile, a clearance is formed between the stator  40  and the movable parts  50 , and the stator  40  and the movable part  50  are not in contact with each other. 
         [0034]    When the energization of the coil  12  is stopped, the magnetic attraction force between the stator  40  and the movable part  50  no longer exists. Accordingly, the movable part  50  and the valve member  70  are displaced integrally in the opposite direction from the stator  40  by the urging force of the coil spring  55 . As a result, the seat part  71  disengages from the valve seat  64  again. Thus, the internal passage  61  and the second communicating hole  63  communicate with each other with the valve member  70  in engagement with the stopper plate  75 . 
         [0035]    A high pressure pump using the electromagnetic valve  1  is illustrated in  FIG. 2 . A high pressure pump  2  as a fluid pump includes the electromagnetic valve  1  and the pump part  90  which pressurizes and discharges suctioned fuel. The high pressure pump  2  controls a discharged amount of high pressure fuel through the opening and closing of the electromagnetic valve  1 . A pump housing  91  of the pump part  90  is constituted of a housing cover  92  and a housing main body  93 . The housing cover  92  defines the suction passage  94  on the outer circumferential side of the valve body  60 . Fuel from a fuel tank is supplied to the suction passage  94  by a low pressure pump (not shown). The suction passage  94  communicates with the first communicating hole  62 . 
         [0036]    The housing main body  93  defines a cylinder  97  as a cylinder body that accommodates a plunger  96  as a piston so as to allow its reciprocation movement. The pressurizing chamber  95  is defined by an inner circumferential surface of the housing main body  93  which defines the cylinder  97 , an inner circumferential surface of the sleeve  77 , an end face of the plunger  96  on the electromagnetic valve  1  side, and an end face of the stopper plate  75  on the plunger  96  side. The plunger  96  reciprocates in the axial direction by drive of a cam (not shown). 
         [0037]    A delivery valve  110  is attached to the housing main body  93 . The delivery valve  110  has a casing  111 . The housing main body  93  defines a discharge passage  99  which communicates with the pressurizing chamber  95 . The casing  111  is formed in a cylindrical shape, and has an accommodating part  112 , which accommodates a discharge valve  120  therein, and a fuel passage  113 . 
         [0038]    The discharge valve  120  is accommodated inside the casing  111 , and includes a valve body  121 , a valve member  122 , a passage formation member  123  and a spring  124 . The valve body  121  is formed in a cylindrical shape, and disposed inside the casing  111 . The inner circumferential side of the valve body  121  defines a fuel passage  125  which communicates with the discharge passage  99 . The valve member  122  engages an end portion of the valve body  121  on the passage formation member  123  side. The passage formation member  123  is arranged on the opposite side of the valve body  121  from the housing main body  93 . The valve member  122  is formed in the shape of a circular plate, and reciprocates inside the passage formation member  123  in an axial direction of the passage formation member  123 . The spring  124  urges the valve member  122  in a direction of the valve body  121 . 
         [0039]    When pressure in the fuel passage  125  of the valve body  121 , which communicates with the discharge passage  99 , increases in accordance with the pressurization of fuel in the pressurizing chamber  95 , force that presses the valve member  122  applied by fuel in the fuel passage  125  is increased. When the force applied to the valve member  122  by the fuel in the fuel passage  125  becomes larger than force applied to the valve member  122  by fuel in the fuel passage  113  and the spring  124 , the valve member  122  disengages from the valve body  121 . As a result, the discharge passage  99  and the fuel passage  113  of the casing  111  communicate with each other, and the pressurized fuel is discharged into the outside of the high pressure pump  2 . On the other hand, when the pressure in the fuel passage  113  is higher than the pressure in the discharge passage  99 , the valve member  122  engages the valve body  121  so as to stop a flow of fuel from the fuel passage  113  to the discharge passage  99 . In other words, the discharge valve  120  functions as a check valve which allows only a flow of fuel from the pressurizing chamber  95  to the outside. 
         [0040]    Workings of the high pressure pump  2  employing the electromagnetic valve  1  are explained below. When the plunger  96  is displaced from a top dead center to a bottom dead center by the drive of the cam (not shown), the electromagnetic valve  1  opens, and accordingly a predetermined amount of fuel flows from the suction passage  94  into the pressurizing chamber  95 . When the plunger  96  moves up, the fuel in the pressurizing chamber  95  is discharged into the suction passage  94 . After a predetermined amount of fuel is discharged into the suction passage  94 , the electromagnetic valve is closed. The fuel in the pressurizing chamber  95  is pressurized as a result of the upward movement of the plunger  96 . When the pressure of the fuel in the pressurizing chamber  95  increases, fuel pressure of the discharge passage  99  also increases. When the pressure of the fuel in the discharge passage  99  becomes larger than the pressure in the fuel passage  113 , the discharge valve  120  is opened, and thereby the fuel is discharged into the outside of the high pressure pump  2  from the pressurizing chamber  95 . 
         [0041]    The invention is characterized in that the accommodating member  81  and the nonmagnetic portion  82  are formed integrally from resin. First, a method of forming a nonmagnetic member of an electromagnetic valve according to conventional technology is described below. A first press fitting process (1) of press-fitting the nonmagnetic member, which is cylindrically formed from non-magnetic metal, into a connector; a first laser welding process (2) of laser-welding a projection of the connector and the nonmagnetic member together; and a cutting process (3) of performing cutting operations on their inner diameter parts in order to ensure concentricity between the connector and the nonmagnetic member, are carried out. Furthermore, a second press fitting process (4) of press-fitting a stator into the formed complex of the connector and the nonmagnetic member; and a second laser welding process (5) of laser-welding a joining portion with the nonmagnetic member, are carried out. In total, five processes have been needed. 
         [0042]    Since moisture may enter into among the stator, the connector and the nonmagnetic member which are formed integrally from metal such as stainless steel, a bobbin formed from resin, and a resin part in which the bobbin and a terminal are embedded, a sealing part needs to be provided for the bobbinto limit this problem, and accordingly cost of the bobbin rises. 
         [0043]    Next, the method of forming the nonmagnetic member in the first embodiment is described below.  FIG. 3A  illustrates a preparatory stage for formation of the resin formed member  80  using a metal mold (not shown). The stator  40  is arranged such that a position of an end portion of the major diameter portion  42  of the stator  40  on the opposite side from the connector  20  generally accords with a position of an end portion of an inner circumference of the bobbin  11  on the opposite side from the connector  20 , and the stator  40  is located radially inward of the bobbin  11 . The connector  20  is disposed with a distance L between an end portion  24  of the connector  20  on the stator  40  side and an end portion  45  of the major diameter portion  42  on the connector  20  side. The distance L needs to be set such that a clearance is left between the stator  40  and the movable parts  50  when the movable part  50  is attracted in the direction of the stator  40  against the urging force of the coil spring  55  by the magnetic attraction force generated as a result of the energization of the coil  12 , and thereby the seat part  71  of the valve member  70  engages the valve seat  64 . The distance L may be short to ensure predetermined responsivity, and the connector  20  is arranged by setting the distance L appropriately so as to satisfy such conditions. 
         [0044]    As shown in  FIG. 3B , the resin formed member  80  is insert-molded using the metal mold (not shown) to integrate the driving force generating part  10 , the connector  20 , and the stator  40 , which are arranged appropriately. A joining portion between the resin and metal is integrally processed liquid-tightly by, for example, an NMT (nano molding technology) method. Consequently, the metal resin complex  83 , in which the driving force generating part  10 , the connector  20 , the stator  40  and the resin formed member  80  are integrally formed, is produced. Meanwhile, a region defined among the bobbin  11 , the stator  40  and the connectors  20  is the nonmagnetic member  82 , and has a function of preventing the short circuit of magnetic flux between the connector  20  and the stators  40 . 
         [0045]    The housing  30  is press-fitted and welded on the metal resin complex  83 , in which the driving force generating part  10 , the connector  20 , the stator  40  and the resin formed member  80  are integrally formed by the method shown in  FIG. 3A  and  FIG. 3B . Also, the coil spring  55 , the valve body  60 , the movable part  50 , and the valve member  70  are attached to the metal resin complex  83  by valve assembly welding. Furthermore, the stopper plate  75  and the sleeve  77  are welded onto the valve body  60 , and accordingly, the electromagnetic valve  1  is formed. 
         [0046]    As has been described in detail thus far, the process of forming a nonmagnetic member is conventionally carried out in the five processes including laser welding. According to the electromagnetic valve  1  in the first embodiment, the process of forming a nonmagnetic member is carried out in a single process by performing the insert molding after positioning the driving force generating part  10 , the stator  40 , and the connector  20  at their appropriate positions. Because the laser welding between the connector  20  and the stator  40 , and the nonmagnetic member  82  becomes unnecessary, a projection conventionally provided for the connector  82  does not need to be used. Furthermore, a joining surface between the driving force generating part  10 , the connector  20  and the stator  40 , and the resin formed member  80 , is integrally formed liquid-tightly as the metal resin complex  83 . Therefore, the sealing part conventionally provided for the bobbin  11  becomes unnecessary. Because the forming process is simplified, the number of components is reduced, and the shape of the bobbin  11  or the connector  20  is simplified, the cost is greatly reduced. 
         [0047]    The metal resin complex  83  may be formed, for example, by the NMT method. Metal are resin may be joined by any method as long as metal and resin are integrally processed liquid-tightly. Since resin and metal are liquid-tightly joined as a continuous element, a sealing part which is conventionally provided for the bobbin  11 , for example, becomes unnecessary, and thereby a single piece of the bobbin  11  is provided at a low cost. 
         [0048]    Moreover, the first embodiment is characterized in that the nonmagnetic member  82  is formed integrally with the accommodating member  81  which accommodates the driving force generating part  10 . If positions of the driving force generating part  10 , the stator  40 , and the connector  20  are appropriately determined using a configuration of the first embodiment, the attraction is stabilized without precise formation of thickness and length of the nonmagnetic member  82  as in the conventional technology. In addition, the resin formed member  80  is formed integrally as the metal resin complex  83  with the driving force generating part  10 , the stator  40  and the connector  20 , so that the joint strength improves and rigidity is high. As a result, their deformations in attaching the engine or pump is prevented. Also, because a material having good magnetic properties is selected for the magnetic member, a magnetic circuit having good magnetic properties is configured. 
         [0049]    Because the nonmagnetic member  82  is formed from resin integrally with the accommodating member  81  by insert molding, the number of components is reduced. When the connector  20  and the resin part are liquid-tightly fixed, and the stator  40  and the resin part are liquid-tightly fixed only by insert molding using resin, for instance, the connector  20  and the stator  40  do not need to be welded together. Accordingly, the working process is simplified. If a material having good magnetic properties is selected without respect to weldability for a member which constitutes a magnetic circuit, a magnetic circuit having good magnetic properties is formed. 
         [0050]    The metal resin complex  83  may be formed, for example, by the NMT method. Metal are resin may be joined by any method as long as metal and resin are integrally processed. Consequently, joint strength between metal and resin improves, so that rigidity is increased. Therefore, deformation is not easily caused when the electromagnetic valve is attached to an engine or pump. 
       Second Embodiment 
       [0051]    An electromagnetic valve according to a second embodiment of the invention is illustrated in  FIG. 4 . In the present embodiment, the same numeral as the first embodiment is used for indicating substantially the same component as the first embodiment. In an electromagnetic valve  3  of the second embodiment, a terminal  313  is held by a plate-like terminal holding member  314  made of resin, and a coil  312  is an air-core coil. 
         [0052]    A driving force generating part  310  includes the air-core coil  312  without using a bobbin, the terminal  313  and the terminal holding member  314 . By forming integrally the driving force generating part  310 , a stator  40 , a connector  20  and a resin formed member  80  as a metal resin complex  383 , the electromagnetic valve  3  has a similar effect to the first embodiment. Furthermore, by eliminating a bobbin, the number of components is reduced. 
         [0053]    In the above embodiments, the electromagnetic valve used for a high pressure pump is described. However, the electromagnetic valve by the invention may be applied for various uses. An example in which the electromagnetic valve of the invention is applied to an injector is described as follows. 
       Third Embodiment 
       [0054]    An injector using an electromagnetic valve according to a third embodiment of the invention is illustrated in  FIG. 5 . An injector  4  as a fluid injection system is used, for example, as a fuel injection system which injects fuel into an inlet port of a gasoline engine. The injector  4  includes a driving force generating part  410 , a connector  420 , a housing  430 , a stator  440 , a movable part  450 , a coil spring  455  as an urging member, a valve body  460  as a valve body, a needle  470  as a valve member, and a resin formed member  480 . 
         [0055]    The driving force generating part  410  includes a bobbin  411 , a coil  412 , and a terminal  413 . The bobbin  411  is disposed radially outward of the connector  420  and the stator  440 . The coil  412  is wound around the bobbin  411 . The terminal  413  is electrically connected to the coil  412 , and electric power from an external power is supplied to the coil  412  via the terminal  413 . 
         [0056]    The connector  420  is cylindrically formed from a magnetic material such as magnetic stainless steel, and accommodates the movable part  450  and the needle  470  so as to allow their reciprocation movements. The connector  420  defines a fuel passage  425  therein. The fuel passage  425  communicates with a fuel hole  476  in a spacer  475 . The housing  430  covers an outer circumference of the coil  412 . The housing  430  magnetically connects the connector  420  and the stator  440 . 
         [0057]    The stator  440  and the movable part  450  are made of magnetic materials such as magnetic stainless steel, and constitute a magnetic circuit together with the connector  420  and the housing  430 . The stator  440  is cylindrically formed, and is disposed radially inward of the coil  412 . A fuel inlet  446  is formed at an end portion of the stator  440  on the opposite side from the connector  420 . Fuel is supplied to the fuel inlet  446  from a fuel pump (not shown). The fuel supplied to the fuel inlet  446  flows into a fuel passage  449  as a second fluid passage defined by an inner circumferential surface  448  of the stator  440  through a fuel filter  447 . The fuel passage  449  communicates with a clearance  451  defined between the movable part  450  and the needle  470 . The fuel filter  447  removes foreign substances contained in fuel. 
         [0058]    The movable part  450  is cylindrically formed, and is disposed radially inward of the connector  420  to be reciprocated in the axial direction. An end portion of the movable part  450  on the opposite side from the stator  440  is connected integrally to  470 . The movable part  450  is in contact with the coil spring  455  at its end portion on the stator  440  side. One end portion of the coil spring  455  is in contact with the movable part  450 , and the other end portion of the coil spring  455  is in contact with an adjusting pipe  456 . The adjusting pipe  456  is press-fitted into the stator  440 . By adjusting a press-fitted amount of the adjusting pipe  456 , a load of the coil spring  455  urging the movable part  450  is changed. 
         [0059]    The valve body  460  is provided at an end portion of the connector  420  on the opposite side from the stator  440 . The valve body  460  is cylindrically formed, and includes a nozzle hole  465  at its end portion on the opposite side from the fuel inlet  446  in the axial direction. The valve body  460  has an inner wall  466  having a conical shape, and an inner diameter of the inner wall  466  becomes smaller toward the nozzle hole  465  at a front end of the valve body  460 . The valve body  460  has a valve seat  464  on the inner wall  466  in a conical shape. A sleeve  477  is provided on an outer circumference of the valve body  460  on the nozzle hole  465  side. 
         [0060]    The needle  470  as a valve member is accommodated radially inward of the connector  420  and the valve body  460  so as to be reciprocated in the axial direction. The needle  470  has a seat part  471  at its end portion on the opposite side from the fuel inlet  446 . The seat part  471  engages and disengages from the valve seat  464  of the valve body  460 . The needle  470  and the valve body  460  define a fuel pocket chamber  472 , through which fuel flows, therebetween. The clearance  451  defined between the movable part  450  and the needles  470 , the fuel passage  425 , the fuel hole  476  of the spacer  475 , and the fuel pocket chamber  472  constitute the “first fluid passage”. 
         [0061]    The resin formed member  480  includes an accommodating member  481  and a nonmagnetic member  482 . The accommodating member  481  covers the driving force generating part  410 , the connector  420 , the housing  430  and the stator  440 . The nonmagnetic member  482  is located radially inward of the coil  412  as well as between the connector  420  and the stator  440 , and is formed from resin integrally with the accommodating member  481 . The nonmagnetic member  482  prevents a short circuit of magnetic flux between the connector  420  and the stator  440 . A method of forming the resin formed member  480  is described hereinafter. 
         [0062]    Next, workings of the injector  4  are explained. When energization of the coil  412  is stopped, magnetic attraction force is not generated between the stator  440  and the movable part  450 . Accordingly, the movable part  450  is displaced together with the needle  470  in the opposite direction of the stator  440  by urging force of the coil spring  455 . As a result, when the energization of the coil  412  is stopped, the seat part  471  of the needle  470  engages the valve seat  464 . Therefore, fuel is not injected through the nozzle hole  465 . 
         [0063]    Upon energization of the coil  412 , a magnetic circuit is formed in the housing  430 , the connector  420 , the movable part  450  and the stator  440  by a magnetic field generated in the coil  412 . Meanwhile, the nonmagnetic member  482  prevents the short circuit of magnetic flux between the connector  420  and the stator  440 . Accordingly, magnetic attraction force is generated between the stator  440  and the movable part  450 . When the magnetic attraction force generated between the stator  440  and the movable part  450  becomes larger than the urging force of the coil spring  455 , the movable part  450  and the needle  470  are displaced integrally toward the stator  440  side. As a result, the seat part  471  of the needle  470  disengages from the valve seat  464 . 
         [0064]    Fuel, which has flowed into the injector  4  through the fuel inlet  446 , flows into the fuel pocket chamber  472  via the fuel filter  447 , the fuel passage  449 , the clearance  451  defined between the movable part  450  and the needle  470 , the fuel passage  425 , and the fuel hole  476  in the spacer  475  in this order. The fuel in the fuel pocket chamber  472  flows into the nozzle hole  465  through between the valve seat  464  and the seat parts  471 . As a result, fuel is injected through the nozzle hole  465 . 
         [0065]    When the energization of the coil  412  is stopped, the magnetic attraction force between the stator  440  and the movable part  450  no longer exists. Accordingly, the movable part  450  and the needle  470  are displaced integrally toward the opposite side from the stator  440  by the urging force of the coil spring  455 . As a result, the seat part  471  engages the valve seat  464  again so as to block a flow of fuel between the fuel pocket chamber  472  and the nozzle hole  465 . Thus, the injection of fuel through the nozzle hole  465  is ended. 
         [0066]    The method of forming the nonmagnetic member in the third embodiment is described below. In the third embodiment, the driving force generating part  410 , the connector  420 , the stator  440  are appropriately arranged, and the connector  420  and the stator  440 , and the housing  430  are welded together. Then, the resin formed member  480  is insert-molded using a metal mold (not shown). A joining portion between the resin and metal is integrally processed liquid-tightly by, for example, an NMT (nano molding technology) method. Consequently, a metal resin complex, in which the driving force generating part  410 , the connector  420 , the housing  430 , the stator  440 , and the resin formed member  480  are integrally formed, is formed. Meanwhile, a region defined among the bobbin  411 , the connector  420  and the stator  440  is the nonmagnetic member  482 , and has a function of preventing the short circuit of magnetic flux between the connector  420  and the stator  440 . 
         [0067]    As has been described in detail thus far, according to the injector  4  in the third embodiment, by performing the insert molding after positioning the driving force generating part  410 , the stator  440 , and the connector  420  at their appropriate positions, the working process is simplified. The laser welding between the connector  420  and the stator  440 , and the nonmagnetic member  482  becomes unnecessary. The third embodiment is characterized in that the nonmagnetic member  482  is formed integrally with the accommodating member  481  which accommodates the driving force generating part  410 . If positions of the driving force generating part  410 , the stator  440 , and the connector  420  are appropriately determined using a configuration of the third embodiment, the attraction is stabilized without precise formation of thickness and length of the nonmagnetic member  482  as in the conventional technology. The resin formed member  480  is formed integrally with the driving force generating part  410 , the stator  440  and the connector  420 , so that the joint strength improves and rigidity is high. As a result, their deformations in attaching the engine or pump is prevented. Also, because a material having good magnetic properties is selected for the magnetic member, a magnetic circuit having good magnetic properties is configured. 
       Fourth Embodiment 
       [0068]    An injector according to a fourth embodiment of the invention is illustrated in  FIG. 6 . The same numeral is used for indicating substantially the same component as the third embodiment. In the injector  5  of the fourth embodiment, similar to the third embodiment, a resin formed member  580  is insert-molded from resin integrally with a driving force generating part  410 , a connector  420 , a housing  430  and a stator  540 . A joining portion between the resin and metal is integrally processed liquid-tightly by, for example, an NMT method. 
         [0069]    A fuel inlet  546  is formed at an end portion of the cylindrically-formed resin formed member  580  on the opposite side from the connector  420 . Fuel from a fuel pump (not shown) is supplied to the fuel inlet  546 . The fuel supplied to the fuel inlet  546  flows into a fuel passage  584  as a third fluid passage defined by an inner circumferential surface  585  of the resin formed member  580  through a fuel filter  547 . The fuel filter  547  removes foreign substances contained in fuel. 
         [0070]    The stator  540  is shortened to a necessary length for the formation of a magnetic circuit. A fuel passage  549  as the second fluid passage formed inside the stator  540  communicates with the fuel passage  584 . An end portion  589  of the stator  540  on the fuel inlet  546  side and the resin formed member  580  are integrally formed liquid-tightly by an NMT method. 
         [0071]    As a result, similar effects to the third embodiment are produced, and moreover, by shortening the stator  540 , weight of the injector  5  is reduced. 
         [0072]    The resin formed member  580  has the third fluid passage which communicates with the second fluid passage. Therefore, a part of the fluid passage is defined by the resin formed member  580 , and thereby the stator  540  is shortened to a necessary length for a magnetic circuit. Accordingly, the stator  540  made of metal such as stainless steel becomes short, so that weight of the injector  5  is reduced. 
       Fifth Embodiment 
       [0073]    An injector according to a fifth embodiment of the invention is illustrated in  FIG. 7 . The same numeral is used for indicating substantially the same component as the fourth embodiment. 
         [0074]    In the injector  6  of the fifth embodiment, a nonmagnetic member  682  is formed from metal which is a nonmagnetic material A resin formed member  680  has an accommodating member  681 . A fuel passage  684  as the third fluid passage is defined radially inward of the resin formed member  680 . A stator  640  is shortened to a necessary length for the formation of a magnetic circuit. A fuel passage  649  as the second fluid passage formed inside the stator  640  communicates with the fuel passage  684 . An end portion  589  of the stator  640  on a fuel inlet side and the resin formed member  680  are integrally formed liquid-tightly by an NMT method. Since the stator  640  is shortened, similar to the fourth embodiment, weight of the injector  6  is reduced. 
         [0075]    The resin formed member  680  defines a part of the fluid passage, and thereby the stator  640  is shortened to a necessary length for a magnetic circuit. Thus, the stator  640  formed from metal, such as stainless steel, becomes short, so that weight of the injector  6  is reduced. 
       Other Embodiments 
       [0076]    In the above embodiments, the electromagnetic valve is applied to a fuel regulating valve of a high pressure supply pump for a gasoline cylinder direct-injection engine, and a fuel injection system which injects fuel into an inlet port of a gasoline engine. Alternatively, the electromagnetic valve may be applied to a high pressure pump of a diesel engine, other pumps, various injectors, other electromagnetic valves, or the like. In the above embodiments, the NMT method is used as a method of bonding metal and resin together. Alternatively, in another embodiment, any method may be employed as long as metal and resin are bonded together so that fuel leak, for example, is not caused. PPS (poly phenylene sulfide), PBT (poly buthylene terephthalate), nylon (registered trademark), and the like may be used for the resin. 
         [0077]    The invention is not by any means limited to the above embodiments, and may be embodied in various modes without departing from the scope of the invention. 
         [0078]    Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described.