Patent Publication Number: US-7717089-B2

Title: High pressure pump having solenoid actuator

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is based on and incorporates herein by reference Japanese Patent Applications No. 2005-127743 filed on Apr. 26, 2005 and No. 2005-308333 filed on Oct. 24, 2005. 
   FIELD OF THE INVENTION 
   The present invention relates to a high pressure pump having a solenoid actuator, the pump being adapted to pressurizing fuel in a compression chamber. 
   BACKGROUND OF THE INVENTION 
   According to JP-A-2001-295720 and U.S. Pat. No. 6,631,706B1, US2004/0055580A1 (WO00/47888), high pressure fuel pumps are disclosed. In general, a high pressure fuel pump pressurizes fuel drawn into a compression chamber, and discharges the fuel by an axial movement of a plunger. For example, the fuel discharged from the high pressure fuel pump is distributed to an injector provided to each cylinder of an engine via a delivery pipe. The high pressure fuel pump includes a metering valve for controlling an amount of the fuel discharged flowing from the compression chamber, in general. The metering valve is arranged in an inlet of the compression chamber. 
   In the structure of the high pressure fuel pump disclosed in JP-A-2001-295720, a valve body and an electromagnetic driving portion (solenoid actuator) are integrally constructed in the metering valve. The solenoid actuator operates the valve body, which faces the compression chamber. Therefore, when pressure of fuel in the compression chamber increases, pressure of the fuel is applied to the solenoid actuator integrated with the valve body. In this structure, the rigidity of the solenoid actuator needs to be enhanced such that the solenoid actuator is capable of resisting pressure of the fuel repeatedly applied. 
   Furthermore, in the structure of the high pressure fuel pump disclosed in U.S. Pat. No. 6,631,706B1 and US2004/0055580A1, the valve body and the solenoid actuator are separately constructed in the electromagnetic valve (solenoid valve). The valve body separated from the solenoid actuator is interposed between the solenoid actuator and a housing defining the compression chamber. However, hydraulic pressure in the compression chamber is applied to a guide member, which guides the movement of the valve body, provided to the solenoid actuator. Therefore, the hydraulic pressure in the compression chamber is applied to the solenoid actuator via the guide member. As a result, the solenoid actuator needs to be firmly fixed to the housing, and the rigidity of the solenoid actuator needs to be enhanced to prevent deformation when the solenoid actuator is fixed to the housing. 
   In the above structures, the rigidities of both the solenoid valve and the solenoid actuator constructing the solenoid valve need to be enhanced. Therefore, the solenoid valve may become structurally complicated. In addition, the solenoid valve may become jumboized. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing and other problems, it is an object of the present invention to produce a high pressure pump, in which hydraulic pressure applied to the solenoid actuator can be reduced. 
   According to one aspect of the present invention, a pump includes a housing, a valve, a solenoid actuator, and a regulating member. The housing has a compression chamber for pressurizing fluid. The housing further has a fluid passage for guiding fluid into the compression chamber. The valve is located midway through the fluid passage. The valve is adapted to communicating the fluid passage. The valve is adapted to blocking the fluid passage. The solenoid actuator is located on a substantially opposite side of the compression chamber with respect to the valve. The solenoid actuator is adapted to operating the valve. The regulating member is located between the valve and the solenoid actuator for regulating pressure of fluid in the compression chamber from being applied to the solenoid actuator. 
   In this structure, the solenoid actuator can be restricted from being applied with pressure from the compression chamber. Therefore, rigidity of the solenoid actuator need not be enhanced, so that the solenoid actuator can be downsized. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: 
       FIG. 1  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump in accordance with a first embodiment of the present invention; 
       FIG. 2  is a partially cross-sectional side view schematically showing the high pressure fuel pump in accordance with the first embodiment; 
       FIG. 3  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a second embodiment of the present invention; 
       FIG. 4  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a third embodiment of the present invention; 
       FIG. 5  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a fourth embodiment of the present invention; 
       FIG. 6  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a fifth embodiment of the present invention; 
       FIG. 7  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a sixth embodiment of the present invention; 
       FIG. 8A  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, and  FIG. 8B  is a schematic plan view showing an engaging ring of the high pressure fuel pump, in accordance with a seventh embodiment of the present invention; 
       FIG. 9  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with an eighth embodiment of the present invention; 
       FIG. 10  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a ninth embodiment of the present invention; 
       FIG. 11A  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, and  FIG. 11B  is a schematic plan view showing an engaging ring of the high pressure fuel pump, in accordance with a tenth embodiment of the present invention; 
       FIG. 12A  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, and  FIG. 12B  is a schematic plan view showing an engaging ring of the high pressure fuel pump, in accordance with an eleventh embodiment of the present invention; 
       FIG. 13  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a twelfth embodiment of the present invention; 
       FIG. 14  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a thirteenth embodiment of the present invention; 
       FIG. 15  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a fourteenth embodiment of the present invention; 
       FIG. 16A  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, and  FIG. 16B  is a schematic plan view showing a washer of the high pressure fuel pump, in accordance with a fifteenth embodiment of the present invention; and 
       FIG. 17  is a partially cross-sectional side view showing a metering valve of a high pressure fuel pump, in accordance with a sixteenth embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   First Embodiment 
   A high pressure fuel pump  10  of the first embodiment is described in reference to  FIGS. 1 ,  2 . This high pressure fuel pump  10  is a fuel pump for supplying fuel into an injector of a diesel engine and a gasoline engine, for example. 
   The high pressure fuel pump  10  has a housing main body  11 , a cover  12 , a plunger  13 , a metering valve portion  50 , a delivery valve portion  70 , and the like. The housing main body  11  and the cover  12  construct a housing. The housing main body  11  is formed of martensitic stainless steel, or the like. The housing main body  11  has a cylinder  14 , which is in a substantially cylindrical shape. The plunger  13  is movable with respect to a substantially axial direction of the plunger  13  in the cylinder  14  of the housing main body  11 . 
   The housing main body  11  has an introducing passage  21 , an inlet passage  22 , a compression chamber  15 , a delivery passage  23 , and the like. The housing main body  11  has a cylindrical portion  16 . The cylindrical portion  16  internally forms a through hole portion  20  for communicating the introducing passage  21  with the inlet passage  22 . The cylindrical portion  16  is approximately perpendicularly to the cylinder  14 . The cylindrical portion  16  has the inner diameter, which changes midway through the cylindrical portion  16 . The housing main body  11  has a step face  17  in a portion, in which the inner diameter changes in the cylindrical portion  16 . A seat member  30  and a guide member  40  are provided in the cylindrical portion  16 . 
   A fuel chamber  18  is formed between the housing main body  11  and the cover  12 . The introducing passage  21  communicates the fuel chamber  18  with the through hole portion  20 , which is formed inside the inner circumferential periphery of the cylindrical portion  16 . One end portion of the inlet passage  22  communicates with the compression chamber  15 . The other end portion of the inlet passage  22  opens to the inner circumferential side of the step face  17 , and communicates with the through hole portion  20 . As shown in  FIG. 1 , the introducing passage  21  and the inlet passage  22  communicate with each other via a through hole  31  and a groove  41 . The through hole  31  is located in the inner circumferential side of the seat member  30 . The groove  41  is formed in a guide member  40 . In this structure, the fuel chamber  18  and the compression chamber  15  is capable of communicating with each other through the introducing passage  21 , the through hole portion  20  of the housing main body  11 , the through hole  31  of the seat member  30 , the groove  41  of the guide member  40 , and the inlet passage  22 . The introducing passage  21 , the through hole portion  20 , the through hole  31 , the groove  41 , and the inlet passage  22  construct a fuel passage. This fuel passage communicates the fuel chamber  18  with the compression chamber  15 . As referred to  FIG. 2 , the compression chamber  15  communicates with the delivery passage  23  on the opposite side of the inlet passage  22 . 
   The plunger  13  is supported in the cylinder  14  of the housing main body  11  so as to be movable in a substantially axial direction of the plunger  13 . The compression chamber  15  is formed on one end side with respect to a movable direction of the plunger  13 . A head  13   a  formed on the other end side of the plunger  13  is connected with a spring seat  81 . A spring  82  is arranged between the spring seat  81  and the housing main body  11 . The spring seat  81  is pressed against the inner wall of a bottom portion  831  of a tappet  83  by resiliency of the spring  82 . The outer wall of the bottom portion  831  of the tappet  83  makes contact with an unillustrated cam, so that the plunger  13  is reciprocated in a substantially axial direction of the plunger  13 . A movement of the tappet  83  is guided by a tappet guide  84 . The tappet guide  84  is attached to the outer circumferential side of the cylinder  14  of the housing main body  11 . 
   An outer circumferential face of the head  13   a  of the plunger  13  is sealed with respect to an inner circumferential face of the housing main body  11  having the cylinder  14  accommodating the plunger  13  via an oil seal  85 . The oil seal  85  restricts intrusion of oil from the interior of the engine into the compression chamber  15 . The oil seal  85  also restricts leakage of the fuel from the compression chamber  15  to the engine. 
   The delivery valve portion  70  having a fuel outlet is arranged in the delivery passage  23  of the housing main body  11 . The delivery valve portion  70  performs and terminates discharge of the fuel pressurized in the compression chamber  15 . The delivery valve portion  70  has a valve shaft member  71 , a ball member (ball plug)  72 , and a spring  73 . The valve shaft member  71  is fixed to the housing main body  11  having the delivery passage  23 . One end portion of the spring  73  makes contact with the valve shaft member  71 , and the other end portion of the spring  73  makes contact with the ball plug  72 . The ball plug  72  is pressed onto the a valve seat  74  defined on the housing main body  11 , by resiliency of the spring  73 . The ball plug  72  blocks the delivery passage  23  by setting the ball plug  72  to seat on the valve seat  74 , and communicates the delivery passage  23  by lifting the ball plug  72  from the valve seat  74 . When the ball plug  72  is moved to the opposed side of the valve seat  74 , the ball plug  72  makes contact with an end portion of the valve shaft member  71 , so that the lift of the ball plug  72  is limited. When pressure of fuel in the compression chamber  15  increases, force applied to the ball plug  72  from the compression chamber  15  increases. The ball plug  72  is lifted from the valve seat  74  when the force applied to the ball plug  72  from the compression chamber  15  becomes greater than a sum of the resiliency of the spring  73  and the force applied to the ball plug  72  from the downstream of the valve seat  74 . Specifically, the ball plug  72  is applied with force from fuel in a delivery pipe (not shown) in the downstream of the valve seat  74 . By contrast, when pressure of fuel in the compression chamber  15  decreases, the force applied to the ball plug  72  from the compression chamber  15  decreases. The ball plug  72  is seated on the valve seat  74  when the force applied to the ball plug  72  from the compression chamber  15  becomes less than the sum of the resiliency of the spring  73  and the force applied to the ball plug  72  from fuel in the delivery pipe on the downstream side of the valve seat  74 . Thus, the delivery valve portion  70  serves as a check valve for performing and terminating the discharge of fuel from the compression chamber  15 . 
   As referred to  FIG. 1 , the guide member  40  is interposed between the housing main body  11  and the seat member  30 . The guide member  40  has a first seal face  42  in one end portion of this guide member  40  with respect to the axial direction. The first seal face  42  makes contact closely with the step face  17  of the housing main body  11 . The seat member  30  has a male screw portion  32  on the outer circumferential periphery thereof. The male screw portion  32  of the seat member  30  is screwed into a female screw portion  161  formed in the inner circumferential periphery of the cylindrical portion  16 . Thus, the seat member  30  is fixed to the housing main body  11  by this screw connection, and the guide member  40  is interposed and supported between this seat member  30  and the housing main body  11 . The guide member  40  has a second seal face  43  on an end portion thereof on the opposite side of the first seal face  42  with respect to the guide member  40 . The second seal face  43  of the guide member  40  makes contact closely with a seat face  33  formed on an end portion of the seat member  30  by screw-connecting the seat member  30  into the housing main body  11 . 
   The metering valve portion  50  has a valve member (valve)  51 , a spring  52  and an electromagnetic driving portion (solenoid actuator)  60 . The plug  51  is arranged inside the inner circumferential periphery of the guide member  40  so as to be movable in the axial direction of the plug  51 . The plug  51  is formed approximately in an annular shape. The spring  52  is arranged on the opposite side of the seat member  30  with respect to the plug  51 . One end portion of the spring  52  makes contact with a wall face  19  of the housing main body  11 , and the other end portion of the spring  52  makes contact with the plug  51 . The plug  51  is pressed onto the seat member  30  by the spring  52 . The plug  51  has an end portion, which is on the side of the seat member  30 , adapted to be seated on the seat face  33 . The compression chamber  15  and the fuel chamber  18  have a fuel passage therebetween. This fuel passage is blocked by seating the plug  51  on the seat face  33 . The plug  51  has the outer circumferential face that is slidable on a guide face  44  of the guide member  40 . Thus, an axial movement of the plug  51  is guided by the guide face  44  of the guide member  40 . Further, the guide member  40  has the groove  41  in the inner circumferential periphery thereof. Thus, when the plug  51  is lifted from the seat member  30 , fuel in the through hole  31  of the seat member  30  flows into the inlet passage  22  through the groove  41 . 
   The solenoid actuator  60  has a coil  61 , a fixed core  62 , a movable core  63 , a magnetic member  64 , a flange  65 , a spring  66  and a needle  67 . The coil  61  is wound around a resin member  68 , so that a magnetic field is generated by conducting electric current to the coil  61 . The fixed core  62  is formed of a magnetic material. The fixed core  62  is accommodated inside the inner circumferential peripheries of the coil  61  and the magnetic member  64 . The movable core  63  is formed of a magnetic material. The movable core  63  is opposed to the fixed core  62 . The movable core  63  is accommodated inside the inner circumferential periphery of a sleeve member  69  formed of a non-magnetic material. The movable core  63  is movable with respect to the axial direction thereof. The sleeve member  69  accommodates the movable core  63 , thereby restricting a magnetic short circuit between the fixed core  62  and the flange  65 . The spring  66  is arranged between the fixed core  62  and the movable core  63 . The spring  66  presses the movable core  63  to the opposite side of the fixed core  62 . Thus, when electric current is not conducted to the coil  61 , the fixed core  62  and the movable core  63  are separated from each other. 
   The flange  65  is formed of a magnetic material. The flange  65  is attached to the cylindrical portion  16  of the housing main body  11 . Thus, the flange  65  fixes the solenoid actuator  60  to the housing main body  11 , and blocks an end portion of the cylindrical portion  16 . The magnetic member  64  covers the outer circumferential periphery of the coil  61 . The magnetic member  64  is formed of a magnetic material. The magnetic member  64  connects the fixed core  62  magnetically with the flange  65 . The flange  65  has a through hole  651 . In this structure, the inner circumferential side of the flange  65  and the outer circumferential side of the flange  65  are maintained at the same pressure. 
   The movable core  63  is assembled integrally with the needle  67 . The needle  67  has an end portion, which is on the opposite side of the movable core  63 , adapted to making contact with the plug  51 . Resiliency of the spring  66  is greater than resiliency of the spring  52 . Therefore, when electric current is not conducted to the coil  61 , the needle  67  integrated with the movable core  63  is moved to the plug  51  by the resiliency of the spring  66 , so that the plug  51  is lifted from the seat member  30 . 
   The operation of the high pressure fuel pump  10  of the above construction is described as follows. 
   As follows, an intake stroke is described. 
   When the plunger  13  is moved downward in  FIG. 2 , the conduction of the electric current to the coil  61  is terminated. Therefore, the plug  51  is pressed to the compression chamber  15  by the needle  67  integrated with the movable core  63  pressed using the spring  66 . As a result, the plug  51  is lifted from the seat member  30 . Further, when the plunger  13  is moved downward in  FIG. 2 , pressure in the compression chamber  15  decreases. Therefore, force applied to the plug  51  from the through hole  31  becomes greater than force applied to the plug  51  from the compression chamber  15 . Therefore, lifting force is applied to the plug  51  such that the plug  51  is lifted from the seat face  33 , so that the plug  51  is lifted from the seat face  33 . Thus, fuel chamber  18  communicates with the compression chamber  15  through the introducing passage  21 , the through hole portion  20 , the through hole  31 , the groove  41  and the inlet passage  22 . Thus, fuel in fuel chamber  18  is drawn into the compression chamber  15 . 
   As follows, a return stroke is described. 
   When the plunger  13  upwardly moves from the bottom dead center to the top dead center, pressure of fuel in the compression chamber  15  increases, so that force is applied from the compression chamber  15  to the plug  51  such that the plug  51  is seated onto the seat face  33 . However, when electric current is not conducted to the coil  61 , the needle  67  is projected to the compression chamber  15  from the seat face  33  by the resiliency of the spring  66 . Therefore, the movement of the plug  51  with respect to the seat face  33  is regulated by the needle  67 . Consequently, while the electric current conduction to the coil  61  is terminated, the plug  51  maintains a state, in which the plug  51  is lifted from the seat face  33 . Thus, reversely to a condition, in which fuel is drawn from fuel chamber  18  into the compression chamber  15 , fuel in the compression chamber  15  pressurized by upwardly moving the plunger  13  is returned to fuel chamber  18  through the inlet passage  22 , the groove  41 , the through hole  31 , the through hole portion  20  and the introducing passage  21 . 
   As follows, a compression stroke is described. 
   When electric current is conducted through the coil  61  during the return stroke, a magnetic circuit is formed in the fixed core  62 , the magnetic member  64 , the flange  65  and the movable core  63  by a magnetic field generated in the coil  61 . Thus, magnetic attractive force is generated between the fixed core  62  and the movable core  63 , which are separated from each other. When the magnetic attractive force generated between the fixed core  62  and the movable core  63  becomes greater than the resiliency of the spring  66 , the movable core  63  is moved to the fixed core  62 . Therefore, the needle  67  integrated with the movable core  63  is also moved to the fixed core  62 . When the needle  67  is moved to the fixed core  62 , the plug  51  and the needle  67  are separated from each other, so that the plug  51  is released from the force applied from the needle  67 . Consequently, the plug  51  is moved onto the seat face  33  by the resiliency of the spring  52  and force applied from the compression chamber  15 . The spring  52  serves as a bias member. 
   The plug  51  is moved to the seat face  33  and is seated onto the seat face  33 , so that the inlet passage  22  is blocked from the through hole  31 . Thus, the returning fuel from the compression chamber  15  to fuel chamber  18  is terminated. The amount of fuel returned from the compression chamber  15  to fuel chamber  18  is adjusted in the upward movement of the plunger  13  by blocking the compression chamber  15  from fuel chamber  18 . Thus, the amount of fuel pressurized in the compression chamber  15  is controlled. 
   As the plunger  13  upwardly moves further to the top dead center in this blocking state of the compression chamber  15  from fuel chamber  18 , pressure of fuel in the compression chamber  15  increases. When pressure of fuel in the compression chamber  15  becomes a predetermined pressure or greater, the ball plug  72  is lifted from the valve seat  74  against the resiliency of the spring  73  in the delivery valve portion  70  and force applied to the ball plug  72  from the delivery pipe in the downstream of the valve seat  74 . Thus, the delivery valve portion  70  opens, so that fuel pressurized in the compression chamber  15  is discharged from the high pressure fuel pump  10  through the delivery passage  23 . Fuel discharged from the high pressure fuel pump  10  is supplied to the delivery pipe, and is accumulated in a fuel accumulator (not shown), thereby being supplied to an injector (not shown). In this condition, the needle  67  is lifted from the plug  51 . Therefore, even when force is applied from the compression chamber  15  to the plug  51 , this force applied to the plug  51  can be restricted from being transmitted to the needle  67  of the solenoid actuator  60 . 
   The plunger  13  moves downwardly in  FIG. 2  again, after reaching the top dead center, so that pressure of fuel in the compression chamber  15  decreases. In this condition, the electric current conduction to the coil  61  is terminated. Therefore, the plug  51  is lifted from the seat face  33  again, and fuel is drawn from fuel chamber  18  into the compression chamber  15 . The electric current conduction to the coil  61  may be also terminated in a condition where pressure of fuel in the compression chamber  15  increases to predetermined pressure. 
   Force is applied to the plug  51  by fuel in the compression chamber  15  in a seating direction, in which the plug  51  is seated on the seat face  33 . In addition, force is applied to the plug  51  in a lifting direction, in which the plug  51  is lifted from the seat face  33 . As pressure of fuel in the compression chamber  15  increases, force applied to the plug  51  in the seating direction becomes greater than force applied to the plug  51  in the lifting direction. Therefore, even when the electric current conduction to the coil  61  is terminated, the plug  51  maintains the seating state, in which the plug  51  is seated onto the seat face  33  of the seat member  30  by the force applied from the compression chamber  15 . Thus, electric power consumption of the solenoid actuator  60  can be reduced by stopping the electric current conduction to the coil  61  in a predetermined period. The high pressure fuel pump  10  pressurizes the drawn fuel, and discharges the pressurized fuel by repeating the above strokes including the intake stroke to the compression stroke. The discharge amount of fuel is adjusted by controlling the timing and the period, in which electric current is conducted to the coil  61  of the metering valve portion  50 . 
   In this first embodiment, the seat member  30  is screwed into the cylindrical portion  16  of the housing main body  11 , so that the guide member  40  is interposed by the seat member  30  between the seat member  30  and the housing main body  11 . Thus, the first seal face  42  makes contact closely with the step face  17  of the housing main body  11 , and the second seal face  43  of the guide member  40  makes contact closely with the seat face  33  of the seat member  30 . The step face  17  and the first seal face  42  make contact closely with reach other. In addition, the second seal face  43  and the seat face  33  make contact closely with reach other. In this structure, fuel increasing in pressure corresponding to the pressurization in the compression chamber  15  is sealed by the metal seal structure formed between the step face  17  and the first seal face  42 , and the metal seal structure formed between the second seal face  43  and the seat face  33 . Therefore, fuel increasing in pressure in the compression chamber  15  can be restricted from intruding into the solenoid actuator  60  by forming the metal seal structure. Further, when the electric current is conducted through the coil  61 , the needle  67  is lifted from the plug  51 . Consequently, force is not applied to the solenoid actuator  60  from the high pressure fuel in the compression chamber  15 . Accordingly, the rigidity of the solenoid actuator  60  need not be enhanced. In addition, the physical structure of the solenoid actuator  60  can be restricted from being jumboized. 
   In the above structure, the fuel chamber  18  and the compression chamber  15  in the housing main body  11  have a regulating structure constructed of a regulating member. The regulating member regulates pressure of fuel pressurized in the compression chamber  15  from being applied to the side of the solenoid actuator  60 . Thus, hydraulic pressure applied from the compression chamber  15  to the solenoid actuator  60  can be reduced in the simple structure thereof. Therefore, the rigidity of the solenoid actuator  60  need not be enhanced, and the physical structure of the solenoid actuator  60  need not be jumboized. Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced in the simple structure, while restricting the solenoid actuator  60  from being jumboized. 
   In the above structure, the seat member  30  is fixed between the fuel chamber  18  and the compression chamber  15  in the housing main body  11 . The seat member  30  has the seal face  43  making contact closely with the step face  17  of the housing main body  11 . The step face  17  makes contact closely with the seal face  43 , so that fuel in the compression chamber  15  can be restricted from entering the solenoid actuator  60  by the close step face  17  and seal face  43 . Thus, the hydraulic pressure applied from the compression chamber  15  to the solenoid actuator  60  can be reduced without causing complicatedness of the structure. Therefore, the rigidity of the solenoid actuator  60  need not be enhanced, and the physical structure of the solenoid actuator  60  need not be jumboized. Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced by the simple structure, while restricting the solenoid actuator  60  from being jumboized. 
   In the above structure, the guide member  40  for guiding the movement of the plug  51  is arranged between the housing main body  11  and the seat member  30 . The guide member  40  respectively makes contact closely with the step face  17  of the housing main body  11  and the seat face  33  of the seat member  30  with respect to a substantially axial end portion. Therefore, fuel in the compression chamber  15  can be restricted from entering the solenoid actuator  60  by the seal structure between the step face  17  and the first seal face  42 , and the seal structure between the seat face  33  and the second seal face  43  mutually closely making contact with each other. Thus, the hydraulic pressure applied from the compression chamber  15  to the solenoid actuator  60  can be reduced without causing complicatedness of the structure thereof. Consequently, the rigidity of the solenoid actuator  60  need not be enhanced, and the physical structure of the solenoid actuator  60  need not be jumboized. Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced by the simple structure, while restricting the solenoid actuator  60  from being jumboized. 
   In the above structure, the solenoid actuator  60  includes the needle  67  and the coil  61 . The needle  67  presses the plug  51  to the side of the compression chamber  15 . When the fuel is pressurized in the compression chamber  15 , the needle  67  is attracted to the opposite side of the compression chamber  15 , and the plug  51  blocks the fuel passage by pressure of fuel in the compression chamber  15 . Therefore, it is not necessary to set the plug  51  and the needle  67  to come in contact with each other. Thus, even when pressure of the fuel is applied to the plug  51 , pressure of the fuel can be restricted from being applied to the solenoid actuator  60  including the needle  67 , so that the pressure of the fuel can be restricted from being applied to the solenoid actuator  60 . Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced. 
   Second Embodiment 
   In the second embodiment shown in  FIG. 3 , the seat member  30  is press-fitted into the inner circumferential periphery of the cylindrical portion  16 . Namely, the inner diameter of the cylindrical portion  16  is formed to be approximately equal to or slightly less than the outer diameter of the seat member  30 . Thus, the seat member  30  is fixed to the inner circumferential periphery of the cylindrical portion  16 , so that the guide member  40  is interposed between the seat member  30  and the housing main body  11 . 
   In this second embodiment, the seat member  30  is welded to the housing main body  11  in a weld portion  91  formed in an end portion thereof on the opposite side of the guide member  40 . When the seat member  30  is press-fitted into the cylindrical portion  16 , the high pressure fuel pressurized in the compression chamber  15  mat be leaked into the solenoid actuator  60  through the portion between the inner circumferential face of the cylindrical portion  16  and the outer circumferential face of the seat member  30 . In this structure, intrusion of fuel into the solenoid actuator  60  can be reduced by welding the seat member  30  with the housing main body  11  in the weld portion  91 . 
   In this structure of the second embodiment, the seat member  30  is press-fitted into the housing main body  11 . Thus, the seat face  33  of the seat member  30  makes contact closely with the step face  17  of the housing main body  11  by large force. Therefore, fuel in the compression chamber  15  can be restricted from entering the solenoid actuator  60 . Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced. 
   Furthermore, in this structure of the second embodiment, the seat member  30  is welded to the housing main body  11  in the end portion thereof on the side of the fuel chamber  18 , so that the relative movement of the seat member  30  with respect to the housing main body  11  can be further regulated. Therefore, even when pressure of the fuel is repeatedly applied from the compression chamber  15  to the seat member  30 , the seat member  30  is firmly fixed to the housing main body  11 . Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be further reduced. 
   Third and Fourth Embodiments 
   In the third embodiment, as shown in  FIG. 4 , the guide member is omitted from the structures of those in the first and second embodiments. In addition, a guide face  111  is formed in the housing main body  11 . Namely, the housing main body  11  has the guide face  111  for guiding the movement of the plug  51 . The inner circumferential face of the housing main body  11  defining the guide face  111  is slid on the outer circumferential face of the plug  51 , thereby guiding the movement of the plug  51 . The inner diameter of the guide face  111  of the housing main body  11  is less than the inner diameter of the cylindrical portion  16  accommodating the seat member  30 . Therefore, the step face  17  is formed between the guide face  111  and the cylindrical portion  16 . 
   A female screw portion  112  is formed in the inner circumferential periphery of the cylindrical portion  16 . The female screw portion  112  is screwed to the male screw portion  32  of the seat member  30 . The seat face  33  of the seat member  30  makes contact closely with the step face  17  of the housing main body  11  by screwing the seat member  30  into the inner circumferential periphery of the cylindrical portion  16 . Thus, a metal seal structure is formed between the step face  17  of the housing main body  11  and the seat face  33  of the seat member  30 . 
   In the above structure of the third embodiment, the seat member  30  is fixed to the housing main body  11  by the screw connection. Thus, the seat face  33  of the seat member  30  makes contact closely with the step face  17  of the housing main body  11  by large force. Therefore, fuel in the compression chamber  15  can be restricted from entering the solenoid actuator  60 . Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced. 
   In the fourth embodiment, as shown in  FIG. 5 , similarly to the third embodiment, the guide member is omitted. In addition, similarly to the second embodiment, the seat member  30  is press-fitted into the inner circumferential side of the cylindrical portion  16 , and is welded to the housing main body  11  in the weld portion  91  of an end portion on the opposite side of the plug  51 . 
   In the third and fourth embodiments, the guide member is omitted. Therefore, the high pressure fuel can be restricted from intruding from the compression chamber  15  into the solenoid actuator  60 . In addition, the number of components can be reduced. 
   Fifth, Sixth, and Seventh Embodiments 
   In the fifth embodiment, as shown in  FIG. 6 , a valve body  100  is accommodated inside the inner circumferential periphery of the cylindrical portion  16  of the housing main body  11 . A valve body  100  is formed in a substantially cylindrical shape. The valve body  100  has the inner circumferential periphery that defines a through hole  101  for communicating the introducing passage  21  with the inlet passage  22 . A plug  120  is accommodated inside the inner circumferential periphery of the housing main body  11 . The plug  120  is movable in a substantially axial direction thereof. The plug  120  is adapted to seated on a seat face  102  formed on the valve body  100 . When the plug  120  is lifted from the seat face  102 , fuel is permitted to flow between the introducing passage  21  and the inlet passage  22 . By contrast, when the plug  120  is seated on the seat face  102 , the flow of the fuel between the introducing passage  21  and the inlet passage  22  is interrupted. 
   A spring seat  121  is provided in the valve body  100 . The spring seat  121  is held in the valve body  100  by an engaging member  122 . The engaging member  122  is fitted into a groove formed in an inner circumferential wall of the valve body  100 , so that the engaging member  122  is fixed to the valve body  100 . One end of a spring  123 , which serves as a bias member, makes contact with the spring seat  121 . The other end of the spring  123  makes contact with the plug  120 . The spring  123  produces resilient force, such that the sprig  123  extends in the axial direction thereof. Thus, the plug  120  is pressed in a direction, in which the plug  120  is seated on the seat face  102  of the valve body  100 . The plug  120  is guided along a guide face  105  defined by the inner circumferential face of the valve body  100 , thereby being movable with respect to the axial direction thereof. 
   Seal members  130 ,  131  and an engaging ring  140  are arranged between the housing main body  11  and the valve body  100 . The engaging ring  140  serves as an engaging member. The seal members  130 ,  131  are arranged between the inner wall of the housing main body  11  and the outer wall of the valve body  100 , thereby liquid tightly sealing the housing main body  11  and the valve body  100  therebetween. Namely, the seal members  130 ,  131  make contact closely with both the inner wall of the housing main body  11  and the outer wall of the valve body  100 , thereby regulating the intrusion of the fuel from the compression chamber  15  into the solenoid actuator  60 . The engaging ring  140  is formed in a substantially annular shape. The engaging ring  140  is engaged with a groove  24  formed in the inner wall of the housing main body  11  defining the through hole portion  20 , and engaging with a groove  103  formed in the outer wall of the valve body  100 . The valve body  100  is held in the housing main body  11  by engaging the engaging ring  140  with both the housing main body  11  and the valve body  100 . The seal members  130 ,  131  and the engaging ring  140  construct a regulating member. 
   A washer  150 , which serves as a bias member, is arranged between the valve body  100  and the step face  17 . The washer  150  is a spring washer, for example, for pressing the valve body  100  to the side of the solenoid actuator  60  by resilient force. The valve body  100  is pressed to the side of the solenoid actuator  60  by the resilient force of the washer  150 . The valve body  100  is held in the housing main body  11  by the engaging ring  140  engaged with the housing main body  11 . Therefore, the valve body  100  may be slightly moved in the axial direction by a manufacturing error in sizes of the groove  24 , the groove  103 , the engaging ring  140 , and the like, for example. When pressure of fuel in the compression chamber  15  changes as the plunger  13  upwardly and downwardly moves, force applied to the valve body  100  also changes by the fuel pressure. As a result, the valve body  100  may be moved in the axial direction thereof, consequently, ablation may arise in the seal members  130 ,  131  and the engaging ring  140  arranged between the housing main body  11  and the valve body  100 . However, in the above structure, the movement of the valve body  100  can be reduced by pressing the valve body  100  to the solenoid actuator  60  using the washer  150 . Accordingly, the ablation of the seal members  130 ,  131  and the engaging ring  140  can be reduced. 
   In the fifth embodiment, the high pressure fuel in the compression chamber  15  is sealed by the seal members  130 ,  131 , thereby being restricted from entering the solenoid actuator  60 . In the above construction, force from the high pressure fuel in the compression chamber  15  can be escaped to the housing main body  11  through the plug  120 , the valve body  100 , and the engaging ring  140 . Therefore, force applied from the high pressure fuel in the compression chamber  15  can be restricted form being applied to the solenoid actuator  60 . Consequently, the solenoid actuator  60  need not be enhanced in pressure resisting property and rigidity. Accordingly, the physical structure of the solenoid actuator  60  can be downsized. 
   In the above structure of the fifth embodiment, the regulating member  130 ,  131 ,  140  has the engaging ring  140  engaged with the outer wall of the valve body  100  and the inner wall of the housing main body  11 . The regulating member  130 ,  131 ,  140  holds the valve body  100  in the housing main body  11 . The regulating member  130 ,  131 ,  140  further includes the seal member  130 ,  131  for sealing the outer circumferential face of the valve body  100 , which is for guiding the movement of the plug  51 , and the inner circumferential face of the housing main body  11 , which defines the fuel passage, therebetween. Thus, pressure of the fuel pressurized in the compression chamber  15  can be restricted from being applied to the solenoid actuator  60 . Consequently, the hydraulic pressure applied from the compression chamber  15  to the solenoid actuator  60  can be reduced without causing complicatedness of the structure. Therefore, the rigidity of the solenoid actuator  60  need not be enhanced, and the physical structure of the solenoid actuator  60  need not be jumboized. Accordingly, the hydraulic pressure applied to the solenoid actuator  60  can be reduced by the simple structure, while restricting the solenoid actuator  60  from being jumboized. 
   Furthermore, the valve body  100  is held in the housing main body  11  by the engaging ring  140 . In this structure, force generated by pressure of fuel in the compression chamber  15  is applied from the valve body  100  to the housing main body  11  via the engaging ring  140 . Therefore, force generated by pressure of fuel in the compression chamber  15  can be restricted from being transmitted to the solenoid actuator  60 . Accordingly, the rigidity of the solenoid actuator  60  need not be enhanced, and the physical structure of the solenoid actuator  60  need not be jumboized. 
   In the above structure of the fifth embodiment, the washer  150  is arranged between the step face  17  and the valve body  100 . The washer  150  presses the valve body  100  to the side of the solenoid actuator  60 , so that force is regularly applied to the valve body  140  to the side of the solenoid actuator  60 . Therefore, the axial movement of the valve body caused by the change in pressure in the compression chamber  15  can be reduced. Accordingly, ablation arising in the seal member and the engaging member due to the movement of the valve body  100  can be restricted. 
   Furthermore, the washer  150  is arranged between the housing main body  11  and the engaging ring  140 . The washer  150  presses the valve body  100  to the side of the solenoid actuator  60 . Thus, force is regularly applied to the valve body  100  and the engaging ring  140  to the side of the solenoid actuator  60 . Therefore, the axial movement of the valve body caused by the change in pressure in the compression chamber  15  can be reduced. Accordingly, ablation arising in the seal member and the engaging member caused by the movement of the valve body  100  can be reduced. 
   As shown in  FIG. 7 , in the sixth embodiment, an engaging ring  141  has the cross sectional shape, which is in a substantially circular shape. 
   As shown in  FIGS. 8A ,  8 B, in the seventh embodiment, an engaging ring  142  is formed in a substantially arc shape having an opening portion with respect to the circumferential direction. That is, the engaging ring  142  is in an approximately C-shape. 
   The cross sectional shape and the planar shape can be arbitrarily set in the engaging rings  140 ,  141 ,  142 . 
   Eighth, Ninth, Tenth, Eleventh, Twelfth, Thirteenth, Fourteenth, Fifteenth, and Sixteenth Embodiments 
   As shown in  FIG. 9 , in the eighth embodiment, a washer  150  is provided in the groove  24  of the housing main body  11  and the groove  103  of the valve body  100  together with the engaging ring  140 . The washer  150  is arranged on the side of compression chamber  15  with respect to the engaging ring  140 , thereby pressing the engaging ring  140  to the side of the solenoid actuator  60 . Thus, the washer  150  presses the valve body  100  to the side of the solenoid actuator  60  via the engaging ring  140 , thereby reducing a movement of the valve body  100 . 
   As shown in  FIG. 10 , in the ninth embodiment, the washer  150  is arranged in the groove  24  of the housing main body  11  and the groove  103  of the valve body  100  together with the engaging ring  140 . The washer  150  is arranged on the side of the solenoid actuator  60  with respect to the engaging ring  140 , thereby pressing the engaging ring  140  to the side of the compression chamber  15 . Thus, the washer  150  presses the valve body  100  to the side of the step face  17  via the engaging ring  140 , thereby reducing the movement of the valve body  100 . 
   In this structure of the ninth embodiment, the washer  150  is arranged between the housing main body  11  and the engaging ring  140 . The washer  150  presses the valve body  100  to the side of the step face  17 . Thus, force is regularly applied to the valve body  100  and the engaging ring  140  to the side of the step face  17 . Therefore, the axial movement of the valve body  100  caused by pressure change of the compression chamber  15  can be reduced. Accordingly, ablation arising in the seal member and the engaging ring  140  caused by the movement of the valve body  100  can be reduced. 
   As shown in  FIGS. 11A ,  11 B, in the tenth embodiment, an engaging ring  143  produces resilient force for expanding and contracting this engaging ring  143  with respect to the axial direction thereof. Therefore, the engaging ring  143  holds the valve body  100  in the housing main body  11 , thereby pressing the valve body  100  by the resilient force. In the tenth embodiment, the engaging ring  143  is arranged in the groove  24  of the housing main body  11  and the groove  103  of the valve body  100 . In this structure, the engaging ring  143  presses the valve body  100  to the opposite side of the solenoid actuator  60 . Thus, the valve body  100  is pressed against the step face  17  by the engaging ring  143 . 
   As shown in  FIGS. 12A ,  12 B, in the eleventh embodiment, an engaging ring  144  presses the valve body  100  to the side of the solenoid actuator  60  reversely to the tenth embodiment. 
   In the structures of the tenth and eleventh embodiments, the engaging ring  143 ,  144  itself has resilient force. Therefore, the engaging ring  143 ,  144  presses the valve body  100  toward the solenoid actuator  60  or toward the step face  17 . Thus, force is regularly applied from the engaging ring  143 ,  144  to the valve body  100  toward the solenoid actuator  60  or toward the step face  17  side. Consequently, the axial movement of the valve body  100  caused by pressure change of the compression chamber  15  can be reduced. Accordingly, ablation arising in the seal member and the engaging ring  143 ,  144  caused by the movement of the valve body  100  can be reduced. 
   As respectively shown in  FIG. 13 ,  14  or  15 , in the twelfth, thirteenth and fourteenth embodiments, the cross sectional shapes of engaging rings  145 ,  146  and  147  are different from the cross sectional shape of the tenth embodiment. In the structures of the twelfth, thirteenth and fourteenth embodiments, the pressing direction of the valve body  100  is similar to that of the tenth embodiment. Thus, the cross sectional shape of the engaging ring can be arbitrarily selected. 
   In the tenth to fourteenth embodiments, a washer for pressing the valve body  100  can be omitted. Accordingly, the number of components can be reduced. 
   In the fifteenth embodiment, as shown in  FIGS. 16A ,  16 B, a washer  151  has the planar shape, which is different from the planar shapes of the other embodiments. For example, as shown in  FIG. 16B , the washer  151  may have a star shape and a polygonal shape. 
   In the sixteenth embodiment, as shown in  FIG. 17 , a spring seat  121  is press-fitted to the inner circumferential side of the valve body  100 . Thus, an engaging member for fixing the spring seat  121  to the valve body  100  can be omitted. Accordingly, the number of components can be reduced. 
   Other Embodiments 
   In the above first and third embodiments, the construction for fixing the seat member  30  to the housing main body  11  by screw connection has been described. In these structures, an end portion of the seat member  30  on the side of the solenoid actuator  60  may be welded to the housing main body  11 . 
   The fluid pressurized using the high pressure pump is not limited to fuel. 
   The above structures of the embodiments can be combined as appropriate. 
   Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention.