Patent Publication Number: US-10309393-B2

Title: High-pressure pump and production method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is the U.S. national phase of International Application No. PCT/JP2015/006377 filed Dec. 22, 2015, which designated the U.S. and claims priority to Japanese Patent Application No. 2015-8335 filed on Jan. 20, 2015, the entire contents of each of which are hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a high-pressure pump for an internal combustion engine, and to a production method of the high-pressure pump. 
     BACKGROUND ART 
     A high-pressure pump provided in a fuel supply system has been known. The high-pressure pump pressurizes fuel in the system to supply the pressurized fuel to an internal combustion engine. 
     The high-pressure pump pressurizes the fuel by varying a volume of a pressure chamber formed in a deep portion of a cylinder in accordance with reciprocating movement of a plunger provided inside the cylinder. The fuel pressurized by the pressure chamber is discharged from a discharge path communicating with the pressure chamber. 
     According to an example of a high-pressure pump described in Patent Literature 1, a ring-shaped member fits to a radially outer portion of a plunger on the side exposed to a pressure chamber. This high-pressure pump prevents separation of the plunger from a cylinder by engagement between the ring-shaped member and a step portion formed between the pressure chamber and the cylinder in a state before attachment to an internal combustion engine. 
     According to another example of the high-pressure pump described in Patent Literature 1, the outside diameter of the plunger at a portion protruding from the cylinder toward the side opposite to the pressure chamber is smaller than the outside diameter of the plunger at a portion inside the cylinder. The plunger therefore has a step at the portion corresponding to the change of the outside diameter of the plunger. This high-pressure pump similarly prevents separation of the plunger from the cylinder by engagement between the step of the plunger and a step portion of a pump body in a state before attachment to an internal combustion engine. 
     According to the high-pressure pump described in Patent Literature 1, a suction valve unit that controls supply of fuel to the pressure chamber is provided on the pressure chamber on the side opposite to the plunger. The suction valve unit is detachably attached to the pump body. This configuration of the high-pressure pump allows insertion of the plunger from the pressure chamber into the cylinder before assembly of the suction unit to the pump body. 
     According to the high-pressure pump described in Patent Literature 1, however, the size of the high-pressure pump in the axial direction of the cylinder increases by the presence of the suction valve unit described above. When the position of the suction valve unit of the high-pressure pump described in Patent Literature 1 is switched to a position in the radial direction of the cylinder, and the pressure chamber on the side opposite to the plunger is closed by the pump body, for example, assembly of the plunger to the cylinder from an opening of the cylinder on the side opposite to the pressure chamber is difficult in any of the examples described above. 
     PRIOR ART LITERATURE 
     Patent Literature 
     PATENT LITERATURE 1: JP 2003-65175 A 
     SUMMARY OF INVENTION 
     It is an object of the present disclosure to provide a high-pressure pump capable of preventing separation of a plunger regardless of an assembly direction of the plunger to a cylinder, and to provide a production method of this high-pressure pump. 
     A high-pressure pump includes a cylinder, a pump body, a plunger, and a large-diameter portion. 
     The pump body includes a pressure chamber having an inside diameter larger than an inside diameter of the cylinder, and disposed in a deep portion of the cylinder. The pump body closes the pressure chamber on a side opposite to the plunger. The plunger reciprocates within the cylinder to vary a volume of the pressure chamber. The large-diameter portion provided at an end of the plunger on a side protruding to the pressure chamber has an outside diameter larger than the inside diameter of the cylinder and smaller than the inside diameter of the pressure chamber. 
     According to this structure, the large-diameter portion is engaged with a step portion between the cylinder and the pressure chamber in a state before attachment of the high-pressure pump to an internal combustion engine. Accordingly, separation of the plunger from the cylinder can be prevented. 
     A production method of a high-pressure pump includes a temperature control process and an insertion process. In the temperature control process, at least either “heating the cylinder” or “cooling the large-diameter portion” is performed to allow the inside diameter of the cylinder to become larger than the outside diameter of the large-diameter portion. The insertion process inserts the plunger into the cylinder. 
     Accordingly, the large-diameter portion provided at the end of the plunger is insertable into the pressure chamber even when the high-pressure pump is configured such that the pressure chamber on the side opposite to the plunger is closed by the pump body. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. 
         FIG. 1  is a cross-sectional view of a high-pressure pump according to a first embodiment of the present disclosure. 
         FIG. 2  is an enlarged view of a part II in  FIG. 1 . 
         FIG. 3  is a flowchart showing a production process of the high-pressure pump according to the first embodiment. 
         FIG. 4  is a cross-sectional view illustrating a state of the high-pressure pump during production. 
         FIG. 5  is a partial cross-sectional view of the high-pressure pump in a state for attachment to an internal combustion engine. 
         FIG. 6  is an enlarged view of a part VI in  FIG. 5 . 
         FIG. 7  is a cross-sectional view of a high-pressure pump of a first comparative example in a state for attachment to an internal combustion engine. 
         FIG. 8  is a cross-sectional view of a high-pressure pump of a second comparative example in a state for attachment to an internal combustion engine. 
         FIG. 9  is a partial cross-sectional view of a high-pressure pump according to a second embodiment of the present disclosure. 
         FIG. 10  is a cross-sectional view of a high-pressure pump according to a third embodiment of the present disclosure. 
         FIG. 11  is a cross-sectional view of a high-pressure pump according to a fourth embodiment of the present disclosure. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT INVENTION 
     A plurality of embodiments according to the present disclosure are hereinafter described with reference to the drawings. Note that substantially identical configurations in the plurality of embodiments have been given identical reference numbers. The same explanation is not repeated for the identical configurations. 
     First Embodiment 
     A first embodiment of the present disclosure is hereinafter described with reference to  FIGS. 1 to 6 . A high-pressure pump  1  according to the present embodiment is attached to an engine block  2  of an internal combustion engine, pressurizes fuel drawn from a fuel tank, and pumps the fuel to a delivery pipe. The fuel accumulated in the delivery pipe is injected and supplied from an injector to respective cylinders of the internal combustion engine. 
     The high-pressure pump  1  includes a cylinder  10 , a pump body  11 , a plunger  40 , a large-diameter portion  41 , and others as illustrated in  FIG. 1 . 
     In  FIG. 1 , a conceptual boundary between the cylinder  10  and the pump body  11  is indicated by a broken line  110 . However, the cylinder  10  and the pump body  11  in the present embodiment are formed integrally. 
     The pump body  11  includes a fitting portion  12  having a cylindrical shape and capable of fitting to a bore  3  formed in the engine block  2  of the internal combustion engine. The pump body  11  is fixed to the engine block  2  by a bolt (not shown) provided at a position indicated by a chain line  13  in  FIG. 1 . In this condition, a contact surface  14  provided outside the fitting portion  12  contacts the engine block  2 . 
     The pump body  11  includes a pressure chamber  15  formed in a deep portion the cylinder  10 . The pressure chamber  15  on the side opposite to the plunger  40  is closed by the pump body  11 . 
     As illustrated in  FIG. 2 , an inside diameter D 1  of the pressure chamber  15  is slightly larger than an inside diameter D 2  of the cylinder  10 . Accordingly, a step portion  36  having a tapered-shape is formed at a connection portion between the pressure chamber  15  and an inner wall of the cylinder  10 . 
     The plunger  40  is accommodated inside the cylinder  10  formed into a cylindrical shape so as to reciprocate in the axial direction. The plunger  40  moves toward the damper chamber  16  to decrease the volume of the pressure chamber  15  and pressurize fuel. The plunger  40  also moves toward the side opposite to the damper chamber  16  to increase the volume of the pressure chamber  15  and suction the fuel from a supply path  18  into the pressure chamber  15 . 
     The large-diameter portion  41  is provided at an end of the plunger  40  on the side protruding to the pressure chamber  15 . According to the present embodiment, the large-diameter portion  41  and the plunger  40  are formed integrally. 
     An outside diameter D 3  of the large-diameter portion  41  is slightly larger than an outside diameter D 4  of the plunger  40  at normal temperature. In addition, the outside diameter D 3  of the large-diameter portion  41  is larger than the inside diameter D 2  of the cylinder  10 , and smaller than the inside diameter D 1  of the pressure chamber  15 . 
     Accordingly, a relationship D 1 &gt;D 3 &gt;D 2 &gt;D 4  holds between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  at a normal temperature. A difference between the outside diameter D 3  of the large-diameter portion  41  and the inside diameter D 2  of the cylinder  10  (D 3 −D 2 ) is set around several micrometers. 
     A relationship between the large-diameter portion  41  and the cylinder  10  in the present invention is hereinafter described. 
     The relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  according to the present embodiment switches to D 1 &gt;D 2 &gt;D 3 &gt;D 4  when any of following operations (A), (B), and (C) is performed. (A) The pump body  11  and the cylinder  10  are heated, while the large-diameter portion  41  and the plunger  40  are cooled. (B) The pump body  11  and the cylinder  10  are heated. (C) The large-diameter portion  41  and the plunger  40  are cooled. 
     In this case, the difference between the outside diameter D 3  of the large-diameter portion  41  and the inside diameter D 2  of the cylinder  10  (D 3 −D 2 ) is set to such a size as to realize the foregoing relationship. Accordingly, insertion of the large-diameter portion  41  into the pressure chamber  15  is allowed from an opening of the cylinder  10  on the side opposite to the pressure chamber  15 . 
     After any one of the operations (A), (B), and (C) is completed, the temperatures of the cylinder  10  and the large-diameter portion  41  are returned to the temperatures before the operation. As a result, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  becomes D 1 &gt;D 3 &gt;D 2 &gt;D 4 . The large diameter portion  41  is therefore engaged with the step portion  36  connecting the cylinder  10  and the pressure chamber  15  in a state before attachment of the high-pressure pump  1  to the inner combustion engine. Accordingly, prevention of separation of the plunger  40  from the cylinder  10 , and retention of a compressed state of a plunger spring  43  described below are both achievable. 
     As illustrated in  FIG. 1 , a damper chamber  16  is formed in the pump body  11  on the pressure chamber  15  side opposite to the cylinder  10  side. The damper chamber  16  includes a pulsation damper  17 . The pulsation damper  17  contains gas having a predetermined pressure and sealed between two metal diaphragms, and reduces fuel pressure pulsation of the damper chamber  16  by elastic deformation of the two metal diaphragms in accordance with a pressure change of the damper chamber  16 . 
     The pump body  11  includes the supply path  18  and a discharge path  19  each of which extends in a radial direction of the cylinder  10  from the pressure chamber  15 . 
     A suction valve unit  20  is provided in the supply path  18 . The suction valve unit  20  connects or separates the pressure chamber  15  and the supply path  18  by separating or connecting a suction valve  22  from and to a valve seat  21  formed in the supply path  18 . Driving of the suction valve  22  is controlled by an electromagnetic driving unit. The electromagnetic driving unit is configured by a fixed core  23 , a coil  24 , a movable core  25 , a shaft  26 , a spring  27 , and others. The suction valve  22  in the present embodiment is a normally open type. When power is supplied from a connector terminal  28  to the coil  24 , magnetic force thus generated attracts the movable core  25  toward the fixed core  23  while resisting urging force of the spring  27 , thereby achieving cancellation of urging force of the shaft  26  urging the suction valve  22  in a valve opening direction. 
     A discharge valve unit  29  is provided in the discharge path  19 . The discharge valve unit  29  connects or separates the pressure chamber  15  and the discharge path  19  by separating or connecting a discharge valve  31  from and to a valve seat  30  formed in the discharge path  19 . The discharge valve  31  is separated from the valve seat  30  when force applied to the discharge valve  31  from fuel on the pressure chamber  15  side exceeds the sum of force applied to the discharge valve  31  from fuel on the downstream side of the valve seat  30  and elastic force of the spring  32 . As a result, fuel in the pressure chamber  15  passes through the discharge path  19  to the outside from a fuel outlet  33 . 
     A spring seat  42  is fixed to an end of the plunger  40  on the side opposite to the pressure chamber  15 . The plunger spring  43  is provided between the spring seat  42  and a holder  52  fixed to the pump body  11 . The plunger spring  43  and the spring seat  42  urge the plunger  40  to the side opposite to the pressure chamber  15 . The spring seat  42  is fitted to a lifter  4  inserted into a bore  3  of the internal combustion engine. 
     The lifter  4  includes a cylindrical portion  5  having a cylindrical shape, a partitioning plate  6  disposed at an axially intermediate portion of the cylindrical portion  5 , and a roller  7  disposed on the side opposite to the spring seat  42  with the partitioning plate  6  interposed between the spring seat  42  and the roller  7 . An outer wall of the cylindrical portion  5  is in sliding contact with an inner wall of the bore  3  of the internal combustion engine. The roller  7  comes in sliding contact with a cam  8  provided in a deep portion of the bore  3  of the internal combustion engine. The cam  8  rotates with a cam shaft or a crank shaft provided to drive a suction valve or a discharge valve of the internal combustion engine. Rotation of the cam  8  reciprocates the lifter  4  inside the bore  3 , thereby reciprocating the plunger  40  in the cylinder  10  in the axial direction by contact between the plunger  40  and the partitioning plate  6  of the lifter  4 . 
     A spacer  50  having an annular shape is provided at an end of the cylinder  10  on the side opposite to the pressure chamber  15 . A fuel seal  51  is provided on the spacer  50  on the side opposite to the pressure chamber  15 . The fuel seal  51  regulates a thickness of a fuel film around the plunger  40  to reduce leak of fuel toward the internal combustion engine caused by sliding of the plunger  40 . 
     A holder  52  is provided on the fuel seal  51  on the side opposite to the pressure chamber  15 . The holder  52  is extended toward the pump body  11 , and fixed to a recess portion  34  formed in the pump body  11  around the cylinder  10 . 
     An oil seal  53  is attached to an end of the holder  52  on the side opposite to the pressure chamber  15 . The oil seal  53  regulates a thickness of an oil film around the plunger  40  to reduce entrance of oil from the internal combustion engine caused by sliding of the plunger  40 . 
     A production method of the high-pressure pump  1  is now described with reference to  FIGS. 3 to 6 . 
     In an initial temperature control process of  51 , both “heating the pump body  11  and the cylinder  10 ”, and “cooling the large-diameter portion  41  and the plunger  40 ” are performed. This process is continued until the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  becomes D 1 &gt;D 2 &gt;D 3 &gt;D 4 . 
     Note that the process performed in the temperature control process may be only either “heating the pump body  11  and the cylinder  10 ” or “cooling the large-diameter portion  41  and the plunger  40 ” as long as the foregoing relationship D 1 &gt;D 2 &gt;D 3 &gt;D 4  is realizable. 
     In a subsequent insertion process of S 2 , the plunger  40  is inserted into the cylinder  10  as indicated by an arrow in  FIG. 4 . In this case, the large-diameter portion  41  passes through the inside of the cylinder  10 , and comes into a state accommodated within the pressure chamber  15 . 
     In a subsequent normal temperature control process of S 3 , the temperatures of the cylinder  10  and the large-diameter portion  41  approach the temperatures before the temperature control process. This process may be achieved by leaving the high-pressure pump  1  at normal temperature after insertion of the plunger  40  into the cylinder  10  and insertion of the large-diameter portion  41  into the pressure chamber  15 . Alternatively, processes for cooling the cylinder  10 , and heating the plunger  40  may be performed to return the temperature of the high-pressure pump  1  to normal temperature. 
     Thereafter, the high-pressure pump  1  is attached to the bore  3  formed in the engine block  2  of the internal combustion engine as illustrated in  FIGS. 5 and 6 .  FIGS. 5 and 6  illustrate a state of the pump body  11  before fastened to the engine block  2  via a bolt  13 . In this state, the large-diameter portion  41  is engaged with the step portion  36  between the pressure chamber  15  and the cylinder  10 , whereby the plunger spring  43  is compressed by a predetermined amount. The fitting portion  12  of the pump body  11  is therefore fitted into the bore  3  of the engine block  2 . In this case, the compression amount of the plunger spring  43  necessary for fastening by the bolt decreases. Accordingly, the pump body  11  is fastened to the engine block  2  by the bolt more easily. 
     Following advantageous effects are offered in the first embodiment. 
     (1) According to the high-pressure pump  1  of the first embodiment, the pump body  11  closes the pressure chamber  15  on the side opposite to the plunger  40 . The large-diameter portion  41  is provided at the end of the plunger  40  on the side protruding to the pressure chamber  15 . The large-diameter portion  41  has the outside diameter larger than the inside diameter of the cylinder  10  and smaller than the inside diameter of the pressure chamber  15 . 
     In this case, the large-diameter portion  41  is engaged with the step portion  36  between the cylinder  10  and the pressure chamber  15  in a state before attachment of the high-pressure pump  1  to the internal combustion engine. Accordingly, separation of the plunger  40  from the cylinder  10  is avoidable. Assembly to the pump body  11  is therefore allowed in a state that the plunger spring  43  is compressed by a predetermined amount according to the high-pressure pump  1 . In this case, the compression length of the plunger spring  43  necessary for fastening the high-pressure pump  1  to the internal combustion engine by the bolt decreases, and therefore work efficiency increases. 
     In addition, the pump body  11  of the high-pressure pump  1  closes the pressure chamber  15  on the side opposite to the plunger  40 . The suction valve unit  20  for supplying fuel to the pressure chamber  15  therefore is not located in the pressure chamber  15  on the side opposite to the plunger  40 . Accordingly, the axial size of the cylinder  10  of the high-pressure pump  1  decreases. 
     (2) According to the high-pressure pump  1  of the first embodiment, the cylinder  10  and the pump body  11  are formed integrally. Moreover, the large-diameter portion  41  and the plunger  40  are formed integrally. When the high-pressure pump  1  performs at least either “heating the pump body  11  and the cylinder  10 ” or “cooling the large-diameter portion  41  and the plunger  40 ”, the inside diameter of the cylinder  10  becomes larger than the outside diameter of the large-diameter portion  41 . 
     Accordingly, the large-diameter portion  41  provided at the end of the plunger  40  is insertable into the pressure chamber  15  even when the high-pressure pump  1  is configured such that the pressure chamber  15  on the side opposite to the plunger  40  is closed by the pump body  11 . 
     In addition, the number of parts of the high-pressure pump  1  decreases by forming the cylinder  10  and the pump body  11  integrally with each other. The number of parts of the high-pressure pump  1  similarly decreases by forming the large-diameter portion  41  and the plunger  40  integrally with each other. 
     (3) According to the production method of the high-pressure pump  1  of the first embodiment, at least either “heating the pump body  11  and the cylinder  10 ” or “cooling the large-diameter portion  41  and the plunger  40 ” is performed to allow the inside diameter of the cylinder  10  becomes larger than the outside diameter of the large-diameter portion  41  in the temperature control process. 
     Accordingly, the large-diameter portion  41  provided at the end of the plunger  40  is insertable into the pressure chamber  15  even when the high-pressure pump  1  is configured such that the pressure chamber  15  on the side opposite to the plunger  40  is closed by the pump body  11 . 
     First Comparative Example 
     A first comparative example is described with reference to  FIG. 7 . A plunger  400  of a high-pressure pump  101  according to the first comparative example includes a large column portion  401  having a large diameter, and a small column portion  402  having an outside diameter smaller than an outside diameter of the large column portion  401 . The large column portion  401  is inserted into the cylinder  10 . The small column portion  402  protrudes to the side of the cylinder  10  opposite to the pressure chamber  15 . The plunger  400  includes a step  403  at a connection portion between the large column portion  401  and the small column portion  402 . 
     The spacer  50  having an annular shape and provided at the end of the cylinder  10  on the side opposite to the pressure chamber  15  has an inside diameter corresponding to an inside diameter of the small column portion  402  of the plunger  400 . According to the high-pressure pump  101  of the first comparative example, therefore, the step  403  of the plunger  400  is engaged with the spacer  50  in a state before attached to the internal combustion engine. Accordingly, separation of the plunger  400  from the cylinder  10  is avoidable. 
     In general, the plunger  400  of the high-pressure pump  101  is pressed in a rotation direction of the cam  8  during reciprocation of the plunger  400  within the cylinder  10  by rotation of the cam  8 . Accordingly, the plunger is inclined within the cylinder during reciprocation. The high-pressure pump  101  of the first comparative example includes the step  403  at the connection portion between the large column portion  401  and the small column portion  402 , and a corner of the step comes into contact with the inner wall of the cylinder. In this case, reaction force acting on the contact portion increases in accordance with a rise of the plunger even when pressing force of the cam is constant. On the other hand, the plunger  40  according to the first embodiment contacts the inner wall of the cylinder at a corner of the cylinder end. In this case, reaction force acting on the contact portion decreases in accordance with a rise of the plunger when pressing force of the cam is constant. Accordingly, seize resistance of the plunger  400  included in the high-pressure pump  101  of the first comparison example may deteriorate in comparison with the plunger  40  of the first embodiment. 
     Second Comparison Example 
     A second comparative example is now described with reference to  FIG. 8 . The plunger  40  of a high-pressure pump  102  according to the second comparative example is configured by a so-called straight plunger  404  having a constant outside diameter in the axial direction. However, the high-pressure pump  102  of the second comparative example does not have a configuration for preventing separation of the straight plunger  404 . In this case, the plunger spring  43  extends to a free length at the time of attachment of the high-pressure pump  102  to the bore  3  of the internal combustion engine, and thus fastening of the pump body  11  by the bolt is initiated from a state that the fitting portion  12  of the pump body  11  is not fitted to the bore  3 . The high-pressure pump  102  therefore simultaneously requires an operation for compressing the plunger spring  43  and fitting the fitting portion  12  of the pump body  11  into the bore  3 , and an operation for fastening the pump body  11  to the engine block  2  by the bolt. Accordingly, work efficiency may deteriorate. 
     Second Embodiment 
     A second embodiment of the present disclosure is hereinafter described with reference to  FIG. 9 . According to the second embodiment, the plunger  40  and a large-diameter portion  44  are configured by different components. 
     A protrusion portion  45  having a cylindrical shape is formed at an end of the plunger  40  on the pressure chamber  15  side. The large-diameter portion  44  has an annular shape. A radial inner wall of the large-diameter portion  44  is press-fitted and fixed to a radial outer wall of the protrusion portion  45  of the plunger  40 . A press-fit load of the large-diameter portion  44  is larger than urging force of the plunger spring  43 . 
     The plunger  40  and the large-diameter portion  44  may be fixed to each other by screwing or welding, for example, rather than press-fit. 
     The plunger  40  and the large-diameter portion  44  are made of different materials. The linear expansion coefficient of the large-diameter portion  44  is larger than the linear expansion coefficient of the plunger  40 . In other words, the large-diameter portion  44  is made of material more easily contractable by cooling than the material of the plunger  40 . 
     For example, the plunger  40  is made of martensitic stainless steel. The linear expansion coefficient of martensitic stainless steel is approximately 10×10 −6 /° C. 
     On the other hand, the large-diameter portion  44  is made of austenitic stainless steel. The linear expansion coefficient of austenitic stainless steel is approximately 17×10 −6 /° C. 
     The materials of the plunger  40  and the large-diameter portion  44  are not limited to these examples, but may be selected from various other materials such as two-phase stainless steel. 
     According to the second embodiment, a relationship D 1 &gt;D 3 &gt;D 2 &gt;D 4  holds between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  44 , and the outside diameter D 4  of the plunger  40  at normal temperature similarly to the first embodiment described above. 
     According to the second embodiment, however, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  44 , and the outside diameter D 4  of the plunger  40  switches to D 1 &gt;D 2 &gt;D 3  D 4  when any of following operations (D), (E), and (F) is performed. (D) The pump body  11  and the cylinder  10  are heated, while the large-diameter portion  44  is cooled. (E) The pump body  11  and the cylinder  10  are heated. (F) The large-diameter portion  44  is cooled. 
     Accordingly, insertion of the large-diameter portion  44  into the pressure chamber  15  is allowed from an opening of the cylinder  10  on the side opposite to the pressure chamber  15 . 
     After any one of the operations (D), (E), and (F) is completed, the temperatures of the cylinder  10  and the large-diameter portion  44  are returned to the temperatures before the operation. As a result, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  44 , and the outside diameter D 4  of the plunger  40  becomes D 1 &gt;D 3 &gt;D 2 &gt;D 4 . The large diameter portion  44  is therefore engaged with the step portion  36  connecting the cylinder  10  and the pressure chamber  15  in a state before attachment of the high-pressure pump  1  to the inner combustion engine. Accordingly, prevention of separation of the plunger  40  from the cylinder  10 , and retention of a compressed state of the plunger spring  43  are both achievable. 
     A production method of the high-pressure pump  1  according to the second embodiment is substantially similar to the production method described in the first embodiment. However, in the temperature control process of S 1  according to the second embodiment, both “heating the pump body  11  and the cylinder  10 ”, and “cooling the large-diameter portion  44 ” are performed. 
     Note that the process performed in the temperature control process may be only either “heating the pump body  11  and the cylinder  10 ” or “cooling the large-diameter portion  44 ” as long as the foregoing relationship D 1 &gt;D 2 &gt;D 3  D 4  is realizable. 
     Following advantageous effects are offered in the second embodiment. 
     (1) According to the high-pressure pump  1  of the second embodiment, the plunger  40  and the large-diameter portion  44  are configured by different components. 
     When at least either “heating the pump body  11  and the cylinder  10 ” or “cooling the large-diameter portion  44 ” is performed, the cylinder  10  and the large-diameter portion  44  has a relationship such that the inside diameter D 2  of the cylinder  10  becomes larger than the outside diameter D 3  of the large-diameter portion  44 . 
     In this case, cooling the large-diameter portion  44  is only needed at the time of insertion of the large-diameter portion  44  into the pressure chamber  15  without the necessity for cooling the plunger  40 . Accordingly, energy necessary for cooling decreases. 
     (2) According to the high-pressure pump  1  of the second embodiment, the large-diameter portion  44  and the plunger  40  are made of different materials. The linear expansion coefficient of the large-diameter portion  44  is larger than the linear expansion coefficient of the plunger  40 . 
     Accordingly, energy necessary for cooling the large-diameter portion  44  further decreases. 
     Third Embodiment 
     A third embodiment of the present disclosure is hereinafter described with reference to  FIG. 10 . According to the third embodiment, the cylinder  10  and the pump body  11  are configured by different components. On the other hand, the large-diameter portion  41  and the plunger  40  are formed integrally. 
     According to the third embodiment, a relationship D 1 &gt;D 3 &gt;D 2 &gt;D 4  holds between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  at normal temperature similarly to the first and second embodiments described above. 
     According to the third embodiment, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  switches to D 1 &gt;D 2 &gt;D 3 &gt;D 4  when any of following operations (G), (H), and (I) is performed. (G) The cylinder  10  is heated, while the large-diameter portion  41  and the plunger  40  are cooled. (H) The cylinder  10  is heated. (I) The large-diameter portion  41  and the plunger  40  are cooled. 
     Accordingly, insertion of the large-diameter portion  41  into the pressure chamber  15  is allowed from an opening of the cylinder  10  on the side opposite to the pressure chamber  15 . 
     After any one of the operations (G), (H), and (I) is completed, the temperatures of the cylinder  10  and the large-diameter portion  41  are returned to the temperatures before the operation. As a result, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  41 , and the outside diameter D 4  of the plunger  40  becomes D 1 &gt;D 3 &gt;D 2 &gt;D 4 . 
     A production method of the high-pressure pump  1  according to the third embodiment is substantially similar to the production methods described in the first and second embodiments. However, in the temperature control process of S 1  according to the third embodiment, both “heating the cylinder  10 ”, and “cooling the large-diameter portion  41  and the plunger  40 ” are performed. 
     Note that the process performed in the temperature control process may be only either “heating the cylinder  10 ” or “cooling the large-diameter portion  41  and the plunger  40 ” as long as the foregoing relationship D 1 &gt;D 2 &gt;D 3 &gt;D 4  is realizable. 
     According to the high-pressure pump  1  of the third embodiment, the cylinder  10  and the pump body  11  are configured by different components. 
     In this case, heating the cylinder  10  is only needed at the time of insertion of the large-diameter portion  41  into the pressure chamber  15  without the necessity for heating the pump body  11 . Accordingly, energy necessary for cooling decreases. 
     Fourth Embodiment 
     A fourth embodiment of the present disclosure is hereinafter described with reference to  FIG. 11 . According to the fourth embodiment, the cylinder  10  and the pump body  11  are configured by different components. Moreover, the large-diameter portion  44  and the plunger  40  are configured by different components. 
     According to the fourth embodiment, a relationship D 1 &gt;D 3 &gt;D 2 &gt;D 4  holds between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  44 , and the outside diameter D 4  of the plunger  40  at normal temperature similarly to the first to third embodiments described above. 
     According to the fourth embodiment, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  44 , and the outside diameter D 4  of the plunger  40  switches to D 1 &gt;D 2 &gt;D 3  D 4  when any of following operations (J), (K), and (L) is performed. (J) The cylinder  10  is heated, while the large-diameter portion  44  is cooled. (K) The cylinder  10  is heated. (L) The large-diameter portion  44  is cooled. 
     Accordingly, insertion of the large-diameter portion  44  into the pressure chamber  15  is allowed from an opening of the cylinder  10  on the side opposite to the pressure chamber  15 . 
     After any one of the operations (G), (H), and (I) is completed, the temperatures of the cylinder  10  and the large-diameter portion  44  are returned to the temperatures before the operation. As a result, the relationship between the inside diameter D 1  of the pressure chamber  15 , the inside diameter D 2  of the cylinder  10 , the outside diameter D 3  of the large-diameter portion  44 , and the outside diameter D 4  of the plunger  40  becomes D 1 &gt;D 3 &gt;D 2 &gt;D 4 . 
     A production method of the high-pressure pump  1  according to the fourth embodiment is substantially similar to the production methods described in the first to third embodiments. However, in the temperature control process of S 1  according to the fourth embodiment, both “heating the cylinder  10 ”, and “cooling the large-diameter portion  44 ” are performed. Note that the process performed in the temperature control process may be only either “heating the cylinder  10 ” or “cooling the large-diameter portion  44 ” as long as the foregoing relationship D 1 &gt;D 2 &gt;D 3  D 4  is realizable. 
     According to the high-pressure pump  1  of the fourth embodiment, the cylinder  10  and the pump body  11  are configured by different components. Moreover, the large-diameter portion  44  and the plunger  40  are configured by different components. 
     In this case, only temperature control of the cylinder  10  and the large-diameter portion  44  is needed at the time of insertion of the large-diameter portion  44  into the pressure chamber  15 . Accordingly, energy necessary for temperature control decreases. 
     OTHER EMBODIMENTS 
     (1) According to the high-pressure pump  1  described in the plurality of embodiments, the pressure chamber  15  on the side opposite to the plunger  40  is closed by the pump body  11 . However, the suction valve unit  20 , the discharge valve unit  29  or the like of the high-pressure pump  1  in another embodiment may be detachably attached to the pressure chamber  15  on the side opposite to the plunger  40 . 
     Accordingly, the present disclosure is not limited to the embodiments described herein, but may be practiced in various other modes without departing from the scope of the invention, as well as combinations of the plurality of embodiments described herein.