Patent Publication Number: US-11644029-B2

Title: Fuel injection pump

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on Japanese Patent Application No. 2019-151460 filed on Aug. 21, 2019, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a fuel injection pump. 
     BACKGROUND 
     A fuel injection pump pressurizes and supplies fuel to an injector by rotation of a cam to make a plunger to reciprocate. A tappet is known to convert the rotation of the cam into a reciprocating movement of the plunger. 
     SUMMARY 
     According to an aspect of the present disclosure, a fuel injection pump includes: a tappet that reciprocates by rotation of a cam; a cylinder that supports the tappet reciprocally; and a plunger that reciprocates together with the tappet to discharge the pressurized fuel. The tappet includes a tappet body, a pin, a roller, and a washer. The tappet body is supported by the cylinder so as to be capable of reciprocating. The pin is supported by the tappet body at both sides in the axial direction. The roller is rotatably fitted to the outer peripheral side of the pin, and is rotated by the rotation of the cam to reciprocally move to make the plunger and the tappet body to reciprocate. The washer is installed between at least one axial end surface of the roller and the inner peripheral surface of the tappet body. The washer has at least one protrusion to be in contact with a stopper of the tappet body in one of two rotational directions. The rotation is stopped by the protrusion hitting the stopper. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a sectional view illustrating a fuel injection pump according to a first embodiment. 
         FIG.  2    is a view seen in an arrow direction II in  FIG.  1   . 
         FIG.  3    is a perspective view illustrating a tappet body. 
         FIG.  4    is a view illustrating a washer. 
         FIG.  5    is a sectional view in which the washer is restricted from rotating by the tappet body. 
         FIG.  6    is a view illustrating a washer according to a second embodiment. 
         FIG.  7    is a view illustrating a washer according to a third embodiment. 
         FIG.  8    is a perspective view illustrating a washer according to a fourth embodiment. 
         FIG.  9    is a sectional view in which a washer is restricted from rotating by a tappet body according to a fifth embodiment. 
         FIG.  10    is a side view illustrating a washer according to a sixth embodiment. 
         FIG.  11    is a sectional view illustrating a washer according to a seventh embodiment. 
         FIG.  12    is a sectional view in which a washer is restricted from rotating by a tappet body according to an eighth embodiment. 
         FIG.  13    is a sectional view in which a washer is restricted from rotating by a tappet body according to a ninth embodiment. 
         FIG.  14    is a sectional view illustrating a shape of a washer according to a tenth embodiment. 
         FIG.  15    is a sectional view for explaining an erroneous assembly of a washer. 
         FIG.  16    is a sectional view illustrating a shape of a washer according to an eleventh embodiment. 
         FIG.  17    is a sectional view illustrating a fitted state of a washer and a bush according to a twelfth embodiment. 
         FIG.  18    is a sectional view illustrating a shape of an axial end surface of a roller according to a thirteenth embodiment. 
         FIG.  19    is a sectional view illustrating a shape of a washer according to a fourteenth embodiment. 
         FIG.  20    is a sectional view illustrating a fitted state of a pin and a roller according to a fifteenth embodiment. 
         FIG.  21    is a sectional view illustrating a fitted state of a roller and a washer according to a sixteenth embodiment. 
         FIG.  22    is a sectional view illustrating a fitted state of a pin and a washer according to according to a seventeenth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     To begin with, examples of relevant techniques will be described. 
     A fuel injection pump pressurizes and supplies fuel to an injector by rotation of a cam to make a plunger to reciprocate. A tappet is known to convert the rotation of the cam into a reciprocating movement of the plunger. 
     A tappet includes: a tappet body supported by a cylinder to reciprocate; a roller arranged adjacent to a cam; and a pin that rotatably supports the roller. When the cam rotates, the roller rotates and reciprocates to make the plunger and tappet to reciprocate. 
     Further, a washer is disposed between the inner peripheral surface of the tappet body and the axial end surface of the roller to restrict wear of the inner peripheral surface of the tappet body and the axial end surface of the roller by the rotation of the roller. 
     However, an axial force may be applied to a camshaft due to vibration of the engine, a structure for transmitting the driving force of the engine to the camshaft, or the like. When an axial force is applied to the camshaft, an axial force is also applied to the roller that rotates while contacting the cam, so that the axial end surface of the roller is pressed against the washer. As a result, due to the resistance of the contact surface between the washer and the roller, when the roller rotates, the washer may rotate together while being pressed against the inner peripheral surface of the tappet body. 
     The rotation of the washer is not considered in the relevant techniques. As a result of detailed study by the inventors, it was found that the inner peripheral surface of the tappet body is worn when the washer rotates while being pressed against the inner peripheral surface of the tappet body by the rotation of the roller. 
     The present disclosure provides a fuel injection pump in which a washer arranged between an inner peripheral surface of a tappet body and an axial end surface of a roller is restricted from rotating. 
     According to an aspect of the present disclosure, a fuel injection pump includes: a tappet that reciprocates by rotation of a cam; a cylinder that supports the tappet reciprocally; and a plunger that reciprocates together with the tappet to discharge the pressurized fuel. 
     The tappet includes a tappet body, a pin, a roller, and a washer. 
     The tappet body is supported by the cylinder so as to be capable of reciprocating. The pin is supported by the tappet body at both sides in the axial direction. The roller is rotatably fitted to the outer peripheral side of the pin, and is rotated by the rotation of the cam to reciprocally move to make the plunger and the tappet body to reciprocate. 
     The washer is installed between at least one axial end surface of the roller and the inner peripheral surface of the tappet body. The washer has at least one protrusion to be in contact with a stopper of the tappet body in one of two rotational directions. The rotation is stopped by the protrusion hitting the stopper. 
     According to this structure, even if the washer tries to rotate due to the rotation of the roller, the protrusion of the washer contacts the stopper of the tappet body, so that the rotation of the washer is stopped. As a result, even if the roller rotates, the washer does not rotate with respect to the inner peripheral surface of the tappet body, so that wear of the inner peripheral surface of the tappet body can be suppressed. 
     Hereinafter, embodiments will be described with reference to the drawings. 
     First Embodiment 
     A fuel injection pump  2  shown in  FIG.  1    supplies pressurized fuel to a common rail (not shown). A pump housing of the fuel injection pump  2  includes a housing body  10  and a cylinder head  12 . The housing body  10  bears a camshaft  20 . The cylinder head  12  supports a plunger  30  to be capable of reciprocating. 
     A pressurizing chamber  300  is formed on the opposite side of the plunger  30  opposite to the cam  22 . Fuel is supplied to the pressurizing chamber  300  from a feed pump (not shown). As shown in  FIG.  2   , the camshaft  20  has a cam  22  having a double-edged cam profile defined by a continuous curve. 
     A metering valve  40  and a discharge valve  42  are installed in the cylinder head  12 . The metering valve  40  is a solenoid valve, and controls the flow rate of fuel discharged from the discharge valve  42  by closing at a predetermined timing of the compression stroke by the plunger  30 . The discharge valve  42  opens when the fuel pressure in the pressurizing chamber  300  becomes equal to or higher than a predetermined pressure in the compression stroke, and discharges the fuel in the pressurizing chamber  300  from the fuel injection pump  2 . 
     As shown in  FIG.  1   , a plunger head  30   a  of the plunger  30  is attached to a tappet body  52  of the tappet  50  by a seat member  32 . The tappet  50  receives a load toward the cam  22  due to the load received from a spring  34 . 
     As shown in  FIGS.  1  and  2   , the tappet  50  includes the tappet body  52 , a pin  60 , a C-ring  62 , a bush  64 , a roller  66 , and a washer  70 . 
     As shown in  FIG.  3   , the tappet body  52  includes a cylindrical portion  54  that is reciprocally supported by the cylinder portion  10   a  of the housing body  10 , a support portion  56  that supports both ends of the pin  60  in the axial direction, and a stopper  58  for stopping the rotation of the washer  70 . 
     As shown in  FIGS.  1  and  5   , the cylindrical portion  54  has a fitting hole  54   a  into which a detent pin  36  is fitted. The tappet body  52  is restricted from rotating by the fitting of the detent pin  36  into the fitting hole  54   a  of the cylindrical portion  54 . 
     Both ends of the pin  60  in the axial direction are rotatably supported by the support portion  56  of the tappet body  52 , or the pin  60  is supported by the tappet body  52  by being fixed to the support portion  56  with press-fitting. 
     An annular groove is formed on the outer peripheral surface of one axial end of the pin  60 . An annular groove is also formed on the inner peripheral surface of the support portion  56  of the tappet body  52  so as to be aligned with the annular groove formed on the pin  60  in the axial position. The C-ring  62  is fitted into the annular groove formed on the outer peripheral surface of the pin  60  and the inner peripheral surface of the support portion  56  of the tappet body  52 , whereby the axial movement of the pin  60  is suppressed. 
     The bush  64  is formed in a cylindrical shape, and is fitted on the outer peripheral side of the pin  60 . The roller  66  is formed in a cylindrical shape, and is rotatably supported by the bush  64  by being fitted to the outer peripheral side of the bush  64 . The outer peripheral surface of the roller  66  is in contact with the outer peripheral surface of the cam  22 . With the rotation of the cam  22 , the roller  66  rotating in contact with the outer peripheral surface of the cam  22  reciprocates, so that the tappet  50  and the plunger  30  also reciprocate. 
     The washer  70  is formed in an annular and flat plate shape, and the inner circumference of the washer  70  is supported by the pin  60  by being fitted to the outer periphery of the pin  60 . The washer  70  is provided on both sides of the roller  66  in the axial direction. The washer  70  is located between the inner peripheral surface  52   a  of the tappet body  52  and the axial end surface of the bush  64 , and is located between the inner peripheral surface  52   a  of the tappet body  52  and the axial end surface  66   a  of the roller  66 . 
     As shown in  FIGS.  2  and  5   , both ends of the washer  70  are located at the inner side of the both ends of the tappet body  52  in the radial direction of the tappet body  52 . 
     As shown in  FIG.  4   , the washer  70  has an annular portion  72  having an annular shape and two protrusions  74 . The protrusion  74  protrudes outward in the radial direction from the annular portion  72 , at both sides of the annular portion  72  in the radial direction. The washer  70  has an axis  402  that passes through the center  400  of the washer  70 . The axis  402  is a symmetrical axis that divides the two protrusions  74  to a left side and a right side. That is, the washer  70  has a symmetrical shape between the left side and the right side of the axis  402 . 
     The washer  70  is installed between the inner peripheral surface  52   a  of the tappet body  52  and the axial end surface  66   a  of the roller  66 , so that the axial end surface  66   a  of the roller  66  is restricted from contacting the inner peripheral surface  52   a  of the tappet body  52 . Accordingly, even if the roller  66  rotates due to the rotation of the cam  22 , the inner peripheral surface  52   a  of the tappet body  52  can be restricted from being worn due to the rotation of the roller  66 . 
     When an axial force is applied to the camshaft  20  due to the vibration of the engine, the structure for transmitting the driving force of the engine to the camshaft  20 , or the like, the axial force is also applied to the roller  66  rotating in contact with the cam  22 . At this time, the axial end surface  66   a  of the roller  66  is pressed against the washer  70 . 
     As a result, when the roller  66  is rotated by the rotation of the cam  22 , the washer  70  in contact with the axial end surface  66   a  of the roller  66  receives a force in the rotational direction. In this case, even if the washer  70  receives a force in either of the two rotational directions, as shown in  FIG.  5   , the protrusion  74  of the washer  70  hits the stopper  58  of the tappet body  52  in the rotational direction, so that the rotation of the washer  70  is stopped. 
     In order to restrict the roller  66  and the washer  70  from being worn by the rotation of the roller  66  in  FIG.  1   , at least one of the contact surface of the roller  66  and the contact surface of the washer  70  may have a coating having abrasion resistance property, such as diamond like carbon (DLC) or poly tetra fluoro ethylene (PTFE). 
     The first embodiment described above produces the following effects. 
     ( 1   a ) Since the protrusion  74  of the washer  70  hits the stopper  58  of the tappet body  52  in the rotational direction to stop the rotation of the washer  70 , the inner peripheral surface  52   a  of the tappet body  52  in contact with the washer  70  can be restricted from being worn by the rotation of the washer  70 . 
     ( 1   b ) Since the washer  70  has the protrusion  74  on both sides of the annular portion  72  in the radial direction, the protrusion  74  of the washer  70  hits the stopper  58  of the body  52  when the roller  66  rotates in either of two rotational directions. Accordingly, the rotation of the washer  70  can be stopped even if the roller  66  rotates in either of the two rotational directions. 
     ( 1   c ) Since the both ends of the washer  70  are located at the radially inner side of the both ends of the tappet body  52  in the radial direction of the tappet body  52 , the washer  70  can be restricted from interfering with the cylinder portion  10   a  that supports the tappet body  52 . 
     Second Embodiment 
     The fundamental configuration of the second embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the annular portion  72  of the washer  70  has the fixed diameter. In the second embodiment shown in  FIG.  6   , a notch  82   a  is formed on the annular portion  82  of the washer  80  at a location adjacent to the cam  22  while the annular portion  82  of the washer  80  opposite from the cam  22  is circular. In other words, the diameter of the annular portion  82  of the washer  80  differs between one side adjacent to the cam  22  and the opposite side opposite from the cam  22 . 
     With this configuration, in the second embodiment, the length L 1  from the center  400  of the washer  80  to an end position of the washer  80  adjacent to the cam  22  is shorter than the length L 2  from the center  400  of the washer  80  to the other end position of the washer  80  opposite from the cam  22 . 
     According to the second embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained by replacing the washer  70  with the washer  80  and replacing the annular portion  72  with the annular portion  82 . Moreover, further following effects can be obtained. 
     ( 2   a ) Since the notch  82   a  is formed at the location adjacent to the cam  22 , it is possible to restrict the washer  80  from coming into contact with the cam  22 . 
     Third Embodiment 
     The fundamental configuration of the third embodiment is similar to that of the second embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the second embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the second embodiment, the notch  82   a  is formed on the washer  80  at the location adjacent to the cam  22 , such that the length L 1  from the center  400  of the washer  80  to the end position adjacent to the cam  22  is shorter than the length L 2  from the center  400  of the washer  80  to the other end position opposite from the cam  22 . 
     In the third embodiment shown in  FIG.  7   , since the diameter of the small diameter portion  92   a  of the annular portion  92  of the washer  90  adjacent to the cam  22  is smaller than the diameter of the large diameter portion  92   b  of the annular portion  92  of the washer  90  opposite from the cam  22 , such that the length L 1  from the center  400  of the washer  90  to the end position adjacent to the cam  22  is shorter than the length L 2  from the center  400  of the washer  90  to the other end position opposite from the cam  22 . 
     According to the third embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained in which the washer  70  is replaced with the washer  90  and the annular portion  72  is replaced with the annular portion  92 . Moreover, following further effects can be obtained. 
     ( 3   a ) Since the diameter of the small diameter portion  92   a  of the annular portion  92  adjacent to the cam  22  is smaller than the diameter of the large diameter portion  92   b  at location opposite from the cam  22 , the washer  90  can be suppressed from contacting the cam  22 . 
     Fourth Embodiment 
     The fundamental configuration of the fourth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, both end surfaces of the annular portion  72  of the washer  70  in the thickness direction are formed in flat shape. In the fourth embodiment shown in  FIG.  8   , four grooves  102   a  are formed on a contact surface of the annular portion  102  of the washer  100  in contact with the roller  66 , at 90 degrees intervals. The groove  102   a  extends in the radial direction of the annular portion  102 . 
     According to the fourth embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained by replacing the washer  70  with the washer  100  and replacing the annular portion  72  with the annular portion  102 . Moreover, following further effects can be obtained. 
     ( 4   a ) Since the groove  102   a  is formed along the radial direction of the annular portion  102 , it is easy for lubricating oil to enter while the roller  66  and the washer  100  are in contact with each other. This can restrict the contact surface between the roller  66  and the washer  100  from being worn. 
     Fifth Embodiment 
     The fundamental configuration of the fifth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the protrusion  74  protruding radially outward from the annular portion  72  on both sides in the radial direction of the annular portion  72  of the washer  70  hits the stopper  58  of the tappet body  52  in both rotational directions, whereby the rotation of the washer  70  is stopped. 
     In contrast, in the fifth embodiment shown in  FIG.  9   , a ring portion  114  is formed on the annular portion  112  of the washer  110  adjacent to the cam  22 , and a protrusion  116  is formed on the annular portion  112  at a location opposite from the cam  22 . The protrusion  116  protrudes radially outward, toward the inner peripheral side of the stopper  58  of the tappet body  52 . The protrusion  116  abuts on the inner peripheral surface of the stopper  58  of the tappet body  52  in both rotational directions. 
     According to the fifth embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained in which the washer  70  is replaced with the washer  110 , the annular portion  72  is replaced with the annular portion  112 , and the protrusion  74  is replaced with the protrusion  116 . 
     Sixth Embodiment 
     The fundamental configuration of the sixth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the protrusion  74  protruding radially outward from the annular portion  72  on both sides in the radial direction of the annular portion  72  of the washer  70  hits the stopper  58  of the tappet body  52  in both rotational directions, whereby the rotation of the washer  70  is stopped. 
     In the sixth embodiment shown in  FIG.  10   , a protrusion  122  is formed to protrude from the annular portion  72  of the washer  120  to one side in the thickness direction, at both sides in the radial direction. The protrusion  122  hits a stopper (not shown) of a tappet body in both rotational directions. 
     According to the sixth embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained in which the washer  70  is read as the washer  120 , and the protrusion  74  protruding radially outward from the annular portion  72  is read as the protrusion  122  protruding from the annular portion  72  to one side in the thickness direction. 
     Seventh Embodiment 
     The fundamental configuration of the seventh embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the washer  70  is formed in a flat plate shape. In the seventh embodiment shown in  FIG.  11   , the washer  130  is formed in a disc spring shape. Specifically, the washer  130  has a protrusion (not shown) protruding radially outward from the annular portion  132  on both sides in the radial direction of the annular portion  132 . Since the washer  130  is formed in a disc spring shape, the washer  130  is formed to produce an elastic force in the thickness direction. 
     According to the seventh embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained by replacing the washer  70  with the washer  130  and replacing the annular portion  72  with the annular portion  132 . Moreover, following further effects can be obtained. 
     ( 7   a ) Since the washer  130  is elastic in the thickness direction, even if the washer  130  is pressed onto the inner peripheral surface  52   a  of the tappet body  52  by the roller  66  to deform the washer  130  into a flat plate shape, the washer  130  returns to the disc spring shape due to the elastic force when the force pressing the washer  130  against the peripheral surface  52   a  decreases. 
     Accordingly, the washer  130  and the axial end surface  66   a  of the roller  66  can be restricted from coming into close contact with each other, so that the rotational force of the roller  66  applied to the washer  130  can be reduced. 
     Eighth Embodiment 
     The fundamental configuration of the eighth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the axis  402  of the washer  70  passing through the center  400  serves as a symmetry axis for the two protrusions  74  formed on both, e.g., left and right, sides in the radial direction. The shape of the washer  70  is the same between the both sides in the radial direction. 
     In the eighth embodiment shown in  FIG.  12   , the washer  140  has a protrusion  74  on one side and a protrusion  142  on the other side in the radial direction with respect to the axis  402  corresponding to the washer  70  of the first embodiment. In other words, the shape of the washer  140  is different between the one side and the other side in the radial direction. That is, the outer shape of the washer  140  viewed from the roller  66  is different from the outer shape of the washer  140  viewed from the opposite side of the roller  66 . 
     Specifically, a length L 1  from an axis  404  passing through the center  400  of the washer  140  and orthogonal to the axis  402  to one end in the width direction of the protrusion  74 , a length L 1  from the axis  404  to the other end of the protrusion  74  in the width direction, and a length L 1  from the axis  404  to one end of the protrusion  142  adjacent to the cam  22  in the width direction are the same. A length L 2  from the axis  404  to the other end of the protrusion  142  opposite to the cam  22  in the width direction is shorter than the length L 1 . 
     In accordance with the configuration of the protrusions  74  and  142 , the stopper  152  of the tappet body  150  that stops the movement of the protrusion  142  in the rotational direction extends toward the cam  22  more than the stopper  58  that stops the movement of the protrusion  74  in the rotational direction. 
     According to the eighth embodiment described above, the following further effects can be obtained in addition to the effects ( 1   a ) to ( 1   c ) of the first embodiment, in which the washer  70  is replaced with the washer  140 , the protrusion  74  is replaced with the protrusions  74  and  142 , and the stopper  58  is replaced with the stoppers  58  and  152 . 
     ( 8   a ) The washer  140  has different shapes between one side and the other side in the radial direction, and the outer shape of the washer  140  viewed from the roller  66  and the outer shape of the washer  140  viewed from the opposite side of the roller  66  are different. The extension length of the stopper  152  toward the cam is longer than that of the stopper  58  in accordance with the configuration of the protrusions  74  and  142  formed on the washer  140 . 
     The washer  140  cannot be assembled to the pin  60  when the orientation of the washer  140  is reversed from the state shown in  FIG.  12   . Therefore, for example, when the surface of the washer  140  in contact with the roller  66  is mirror-finished or coated to suppress wear, the unprocessed surface can be restricted from being mistakenly assembled to face the roller  66 . 
     Ninth Embodiment 
     The fundamental configuration of the ninth embodiment is similar to that of the eighth embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the eighth embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the eighth embodiment, the length L 1  from the axis  404  orthogonal to the axis  402  of the washer  140  to both ends of the protrusion  74  in the width direction and the length L 1  from the axis  404  to one end of the protrusion  142  adjacent to the cam  22  in the width direction are set as the same length. The length L 2  from the axis  404  to the side of the protrusion  142  opposite from the cam  22  in the width direction is made shorter than the length L 1 . Thereby, in the eighth embodiment, the outer shape of the washer  140  viewed from the roller  66  and the outer shape of the washer  140  viewed from the opposite side of the roller  66  are different from each other. 
     In the ninth embodiment shown in  FIG.  13   , of the protrusions  74  and  162 , the protrusion  162  is notched at the side adjacent to the cam  22 , so that the outer shape of the washer  160  seen from the roller  66  is different from the outer shape of the washer  160  viewed from the side opposite from the roller  66 . 
     Specifically, the protrusion  162  has a notch  162   a  that is partially cut at location adjacent to the cam  22 . The length L 1  from the axis  404  passing through the center  400  of the washer  160  and orthogonal to the axis  402  to both ends of the protrusion  74  in the width direction, and the length L 1  from the axis  404  to the side of the protrusion  162  opposite from the cam  22  in the width direction are the same length. 
     Therefore, the two stoppers  58  that come into contact with the protrusions  74  and  162  respectively to stop the rotation of the washer  160  have the same distance from the axis  404  on the side facing the cam  22 . That is, the tappet body  52  of the ninth embodiment is substantially the same as the tappet body  52  of the first embodiment, unlike the eighth embodiment. 
     When assembling the pin  60 , the bush  64 , the roller  66 , the washer  160 , and the tappet body  52 , an assembling housing (not shown) is used. As shown in  FIG.  13   , an assembly pin  170  is installed so as to project toward a position corresponding to the notch  162   a  of the protrusion  162  when the washer  160  is assembled normally. 
     When the washer  160  is normally assembled from the normal side such as front side, since the notch  162   a  of the protrusion  162  and the assembly pin  170  do not interfere with each other. Thus, the pin  60 , the bush  64 , the roller  66 , the washer  160 , and the tappet body  52  can be normally assembled. 
     If the washer  160  is erroneously assembled from the back side opposite from the front side such that the protrusion  162  and the protrusion  74  are reversed, the protrusion  74  interferes with the assembly pin  170  as indicated by a double chain line in  FIG.  13   . In case where the bush  64 , the roller  66 , and the washer  160  are assembled to the tappet body  52  so that the washer  160  does not interfere with the assembly pin  170 , the position of the fitting hole of the washer  160  is misaligned relative to the position of the fitting hole of the support portion  56  of the tappet body  52  into which the pin  60  is inserted. 
     As a result, the pin  60  cannot be inserted into the fitting hole of the washer  160  through the fitting hole of the support portion  56  of the tappet body  52 . 
     According to the ninth embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained in which the washer  70  is replaced with the washer  160 , and the protrusion  74  is replaced with the protrusions  74  and  162 . Moreover, the following further effects can be obtained. 
     ( 9   a ) Of the two protrusions  74  and  162  of the washer  160 , the protrusion  162  is notched at location adjacent to the cam  22  compared with the protrusion  74 . Therefore, the outer shape of the washer  160  seen from the roller  66  is different from the outer shape of the washer  160  seen from the side opposite to the roller  66 . 
     Therefore, if the front side and the back side of the washer  160  are reversed in the state shown in  FIG.  13   , the pin  60 , the bush  64 , the roller  66 , the washer  160 , and the tappet body  52  cannot be assembled. Therefore, for example, when a surface of the washer  160  in contact with the roller  66  is mirror-finished or coated to suppress wear, the unprocessed surface can be restricted from being mistakenly assembled to face the roller  66 . 
     ( 9   b ) The length L 1  from the axis  404  to both ends of the protrusion  74  of the washer  160  in the width direction and the length L 1  from the axis  404  to the side of the protrusion  162  opposite to the cam  22  in the width direction are the same length. As a result, the distance from the axis  404  to the stopper  58  facing the cam  22  to stop the rotation of the washer  160  by hitting the protrusions  74  and  162  respectively can be the same, so that the shape of the stopper  58  of the tappet body  52  can be made simple. 
     Tenth Embodiment 
     The fundamental configuration of the tenth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the washer  70  is formed in a flat plate shape with the same thickness. In the tenth embodiment shown in  FIG.  14   , the outer peripheral portion  180   a  of the washer  180  is thicker than the inner peripheral portion  180   b  of the washer  180 . 
     The washer  180  has a flat surface adjacent to the inner peripheral surface  52   a  of the tappet body  52 . A surface of the washer  180  adjacent to the roller  66  has a step  182  due to the difference in the thickness. The axial length of the roller  184  is shorter than the axial length of the bush  64  according to the difference in the thickness of the washer  180 . Due to the difference in the axial length, a step  186  is formed by the roller  184  and the bush  64  corresponding to the step  182  of the washer  180 . 
     The step  182  of the washer  180  is fitted with the step  186  formed by the roller  184  and the bush  64 , such that the bush  64 , the washer  180 , and the roller  184  are assembled on the outer peripheral side of the pin  60 . 
     In this state, the outer peripheral portion  180   a  of the washer  180  is sandwiched between the roller  184  and the tappet body  52 , and the inner peripheral portion  180   b  of the washer  180  is sandwiched between the bush  64  and the tappet body  52 . A part of the outer peripheral portion  180   a  of the washer  180 , which is thicker than the inner peripheral portion  180   b , is located on the outer periphery of the step  186 . 
     In contrast to the assembled state shown in  FIG.  14   , if the front surface of the washer  180  is reversed to the back side, a part of the outer peripheral portion  180   a , which is thicker than the inner peripheral portion  180   b , faces the side opposite to the step  186 . At this time, the step  182  of the washer  180  does not fit with the step  186  formed by the roller  184  and the bush  64 . 
     In this state, a part of the outer peripheral portion  180   a  of the washer  180 , which is thicker than the inner peripheral portion  180   b , is located radially outside the position of the inner peripheral surface  52   a  of the tappet body  52 , so that the washer  180  cannot be attached to the inner peripheral side of the tappet body  52 . 
     According to the tenth embodiment described above, the effects ( 1   a ) to ( 1   c ) of the first embodiment can be obtained by replacing the roller  66  with the roller  184  and replacing the washer  70  with the washer  180 . Moreover, further effects can be obtained as follows. 
     ( 10   a ) In contrast to the assembled state shown in  FIG.  14   , if the washer  180  is reversed as shown in  FIG.  15   , the washer  180  cannot be assembled on the inner peripheral side of the tappet body  52 . As a result, it is possible to restrict the washer  180  from being mistakenly assembled reversely. 
     Eleventh Embodiment 
     The fundamental configuration of the eleventh embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the washer  70  is formed in a flat plate shape. In the eleventh embodiment shown in  FIG.  16   , the washer  190  has a circular cylindrical portion  192  that extends from the inner peripheral edge of the annular portion  72  toward the axial end portion of the pin  60 , in addition to the annular portion  72  and the protrusion  74  (not shown). 
     The cylindrical portion  192  of the washer  190  is sandwiched between the outer peripheral surface of the pin  60  and the inner peripheral surface of the support portion  202  of the tappet body  200 . Since the cylindrical portion  192  is sandwiched between the outer peripheral surface of the pin  60  and the inner peripheral surface of the support portion  202  of the tappet body  200 , the inner diameter of the support portion  202  is larger than that of the support portion  56  of the first embodiment. 
     According to the eleventh embodiment described above, the following further effects can be obtained in addition to the effect obtained by replacing the washer  70  with the washer  190  in the effects ( 1   a ) to ( 1   c ) of the first embodiment. 
     ( 11   a ) Since the cylindrical portion  192  of the washer  190  is sandwiched between the outer peripheral surface of the pin  60  and the inner peripheral surface of the support portion  202  of the tappet body  200 , the outer peripheral surface of the pin  60  and the inner peripheral surface of the support portion  202  of the tappet body  200  can be restricted from abrasion caused by the direct contact. 
     Twelfth Embodiment 
     The fundamental configuration of the twelfth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the washer  70  is fitted on the outer periphery of the pin  60  and is supported by the pin  60 . In the twelfth embodiment shown in  FIG.  17   , the washer  212  is fitted to the outer periphery of the bush  210 , and the inner circumference of the washer  212  is supported by the bush  210 . 
     The axial length of the bush  210  is longer than the bush  64  of the first embodiment, such that the bush  210  supports the washer  212  fitted to the outer circumference of the bush  210 . 
     According to the twelfth embodiment described above, the following further effects can be obtained in addition to the effects ( 1   a ) to ( 1   c ) of the first embodiment obtained by replacing the washer  70  with the washer  212 . 
     ( 12   a ) Since the pin  60  can be inserted and assembled in the inner periphery of the bush  210  while the roller  66  and the washer  212  are fitted to the outer periphery of the bush  210 , the pin  60  can be easily attached to the inner periphery of the bush  210 . 
     Thirteenth Embodiment 
     The fundamental configuration of the thirteenth embodiment is similar to that of the twelfth embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the twelfth embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the twelfth embodiment, the roller  66  and the washer  212  are in flat contact with each other. In the thirteenth embodiment shown in  FIG.  18   , the axial end surface  220   a  of the roller  220  that comes into contact with the washer  212  is tapered so as to move away from the washer  212  from the inner peripheral side toward the outer peripheral side of the washer  212 . Thus, the outer peripheral portion of the axial end surface  220   a  of the roller  220  is farther from the washer  212  than the inner peripheral portion of the axial end surface  220   a . The distance away from the washer  212  to the outer peripheral portion of the axial end surface  220   a  may be, for example, 100 μm or less at the outermost periphery of the axial end surface  220   a.    
     Since the axial end surface  220   a  of the roller  220  is formed in a tapered shape, the inner peripheral side of the axial end surface  220   a  of the roller  220  contacts the washer  212 , but the outer peripheral side of the axial end surface  220   a  is restricted from contacting the washer  212 . 
     According to the thirteenth embodiment described above, the following further effects can be obtained in addition to the effect obtained by replacing the roller  66  with the roller  220  in the twelfth embodiment. 
     ( 13   a ) Since the axial end surface  220   a  of the roller  220  that comes into contact with the washer  212  is tapered away from the washer  212 , from the inner circumference side to the outer circumference side, the contact area between the axial end surface  220   a  of the roller  220  and the washer  212  decreases. 
     As a result, it is possible to suppress the axial end surface  220   a  of the roller  220  and the washer  212  from coming into close contact with each other, so that the rotational force that the washer  212  receives from the roller  220  can be reduced. 
     ( 13   b ) Since it is possible to suppress the outer peripheral edge of the axial end surface  220   a  of the roller  220  from contacting the washer  212  and pressing the washer  212  in the axial direction, it is possible to restrict the outer peripheral sides of the axial end surface  220   a  and the washer  212  from being worn. 
     Fourteenth Embodiment 
     The fundamental configuration of the fourteenth embodiment is similar to that of the twelfth embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the twelfth embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the twelfth embodiment described above, the washer  212  is formed in a flat plate shape with the same thickness. In the fourteenth embodiment shown in  FIG.  19   , the outer peripheral portion  230   a  of the washer  230  is thinner than the inner peripheral portion  230   b.    
     The surface of the washer  230  adjacent to the roller  66  is flat. A step  232  is formed on the other surface of the washer  230  opposite to the roller  66  due to the difference in the thickness. 
     According to the fourteenth embodiment described above, the following further effects can be obtained in addition to the effects obtained by replacing the washer  212  with the washer  230  in the twelfth embodiment. 
     ( 14   a ) Since the outer peripheral portion  230   a  of the washer  230  is thinner than the inner peripheral portion  230   b , the outer peripheral portion  230   a  of the washer  230  is more easily deformed in the axial direction than the inner peripheral portion  230   b  when the roller  66  presses the washer  230  in the axial direction. 
     As a result, the force that the outer peripheral portion  230   a  of the washer  230  receives in the axial direction from the roller  66  can be reduced. Thus, the outer peripheral side of the axial end surface  66   a  of the roller  66  and the outer peripheral portion  230   a  of the washer  230  can be suppressed from wearing. 
     Fifteenth Embodiment 
     The fundamental configuration of the fifteenth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the bush  64  and the roller  66  are separate members. In the fifteenth embodiment shown in  FIG.  20   , the roller  240  also serves as a bush. Therefore, in the fifteenth embodiment, the inner peripheral surface of the roller  240  is in direct contact with the outer peripheral surface of the pin  60 . 
     According to the fifteenth embodiment described above, the following further effects can be obtained in addition to the effects ( 1   a ) to ( 1   c ) of the first embodiment by replacing the roller  66  with the roller  240 . 
     ( 15   a ) Since the roller  240  also functions as a bush, the number of components for forming the tappet can be reduced. 
     Sixteenth Embodiment 
     The fundamental configuration of the sixteenth embodiment is similar to that of the fifteenth embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the fifteenth embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the fifteenth embodiment, the washer  70  is fitted with the outer periphery of the pin  60 . In the sixteenth embodiment shown in  FIG.  21   , the washer  250  is fitted to the outer periphery of the roller  260 . The inner circumference of the washer  250  is supported by the roller  260 . 
     Specifically, the roller  260  has a small diameter portion  262  and a large diameter portion  264  having an outer diameter larger than that of the small diameter portion  262 . The small diameter portion  262  is formed on both sides in the axial direction to support the washer  250 . The large diameter portion  264  is located between the small diameter portions  262 . A step  266  is formed by the difference in diameter between the small diameter portion  262  and the large diameter portion  264 . The roller  260  is fitted to the outer peripheral side of the pin  60  with an axial length including the small diameter portion  262  and the large diameter portion  264 . 
     According to the sixteenth embodiment described above, the following further effects can be obtained in addition to the effect of the fifteenth embodiment obtained by replacing the washer  70  with the washer  250  and replacing the roller  240  with the roller  260 . 
     ( 16   a ) Since the pin  60  can be easily inserted and assembled in the inner circumference of the roller  260  in the state where the washer  250  is fitted with the outer circumference of the small diameter portion  262  of the roller  260 . 
     ( 16   b ) Since the roller  260  is fitted on the outer peripheral side of the pin  60  with the axial length including the small diameter portion  262  and the large diameter portion  264 , the axial contact length becomes longer between the inner peripheral surface of the roller  260  and the outer peripheral surface of the pin  60 . As a result, when the roller  260  rotates while being in contact with the pin  60 , it is possible to suppress seizure between the outer peripheral surface of the pin  60  and the inner peripheral surface of the roller  260 . 
     Seventeenth Embodiment 
     The fundamental configuration of the seventeenth embodiment is similar to that of the first embodiment, so the difference therebetween will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and refer to the preceding descriptions. 
     In the first embodiment, the pin  60  and the bush  64  are separate members. In the seventeenth embodiment shown in  FIG.  22   , the pin  270  also serves as a bush. 
     Specifically, the pin  270  includes a small diameter portion  272  formed on both sides in the axial direction to be supported by the support portion  56  of the tappet body  52 , and a large diameter portion  274  having an outer diameter larger than that of the small diameter portion  272 . A step  276  is formed by the difference in diameter between the small diameter portion  272  and the large diameter portion  274 . The roller  66  is fitted on the outer peripheral side of the large diameter portion  274 . 
     The washer  70  is installed between the inner peripheral surface  52   a  of the tappet body  52  and the axial end surfaces of the roller  66  and the step  276 . The washer  70  is fitted to the outer circumference of the small diameter portion  272  of the pin  270 , and the inner circumference of the washer  70  is supported by the small diameter portion  272 . 
     According to the seventeenth embodiment described above, the following further effects can be obtained in addition to the effects ( 1   a ) to ( 1   c ) of the first embodiment. 
     ( 17   a ) Since the pin  270  also serves as a bush, the number of components for forming the tappet can be reduced. 
     ( 17   b ) Since the washer  70  is installed between the inner peripheral surface  52   a  of the tappet body  52  and the axial end surface of the step  276 , even if the pin  60  receives a force in the axial direction, the step  276  stops the axial movement of the washer  70 . As a result, the C-ring  62  installed to suppress the axial movement of the pin  60  in the first embodiment is unnecessary. 
     OTHER EMBODIMENTS 
     Although the embodiments have been described above, the present disclosure is not limited to the above embodiments, and can be implemented with various modifications. 
     ( 18   a ) In the above embodiments, the washer is installed on both axial sides of the roller and is located between the inner peripheral surface of the tappet body and the roller. Alternatively, the washer may be installed only on one side in the axial direction of the roller. For example, when the roller presses the washer toward the inner peripheral surface of the tappet body only in one direction, the washer may be installed at only one corresponding side where the washer is pressed by the roller toward the inner peripheral surface of the tappet body. 
     ( 18   b ) In the above embodiments, the washer has two protrusions that are stopped by the stopper of the tappet body in the rotational direction. Alternatively, the washer may have one protrusion. For example, when the rotational direction of the roller is one direction, the washer may have one protrusion. 
     ( 18   c ) In the thirteenth embodiment, the axial end surface  220   a  of the roller  220  is tapered away from the washer  212  as extending from the inner peripheral side toward the outer peripheral side, so that the outer peripheral portion of the axial end surface  220   a  is away from the washer  212 . Alternatively, the axial end surface of the washer may be formed in a convex arc shape so that the outer peripheral portion of the axial end surface of the washer is separated from the washer. 
     ( 18   d ) A plurality of functions of one component in the above-described embodiment may be realized by a plurality of component s, or one function of one component may be realized by a plurality of components. Further, a plurality of functions executed by a plurality of components may be realized by one component, or a single function realized by a plurality of components may be realized by a single component. A part of the configuration of the above embodiments may be omitted. At least a part of the configuration of the described above embodiment may be added to or replaced with another configuration of the described above embodiment. 
     ( 18   e ) The present disclosure can be realized in various forms such as a system having the fuel injection pump as a component, in addition to the fuel injection pump described above.