JP2008208713A - Fuel jet pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel jet pump reduced in surface pressure generated between a tappet and the surface of a housing on which the tappet slides. <P>SOLUTION: This fuel jet pump 100 is provided with the tappet 10 causing forward and backward movement with respect to a pressurization chamber 54 and the housing 53 supporting the tappet 10 in an advanceable/retractable manner toward the pressurization chamber 54. The tappet 10 has a support part 12 which rotatably supports a roller member 13 and to which a plunger 51 is connected, and a peripheral wall part 11 covering the periphery of the support part 12. The support part 12 includes a top plate part 14 to which the plunger 51 is connected and which is connected to the peripheral wall 11, and a sidewall part extending from the top plate part toward a cam member 30 and supporting the roller member 13. The portion of the top plate part, positioned around a portion where the plunger 51 is connected, includes a fragile part having lower stiffness than that of a portion where the plunger 51 is mounted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection pump, and more particularly to a fuel injection pump that supplies fuel to an engine.

  Conventionally, various fuel injection pumps for supplying fuel to an engine have been proposed. In general, a fuel injection pump includes a pressurizing chamber, a plunger that pressurizes fuel sucked into the pressurizing chamber, a housing that forms the pressurizing chamber, and a cam that is driven by a drive source. Furthermore, the conventional fuel injection pump includes a roller that comes into contact with the cam and a tappet that supports the roller. The tappet is movably disposed in a through hole formed in the housing, and transmits the reciprocating motion of the roller member to the plunger. As the plunger reciprocates, the fuel is sucked into the pressurizing chamber and pressurized (Patent Documents 1 to 8).

For example, a roller tappet described in Japanese Patent Application Laid-Open No. 5-288015 is composed of two members: a cup-type case member and a yoke member that supports the roller member. A yoke member is coupled and integrated on the lower surface of the case member by spot welding.
JP 2001-317430 A JP 2003-184699 A JP 2001-221131 A JP-A-5-332222 JP-A-5-60032 Special Table 2001-2001281 JP-A-6-159193 JP 2006-105090 A JP-A-5-288015

  Here, in the conventional fuel ejection pump and tappet, the tappet may be inclined by the pressing force received from the cam via the roller. As described above, when the tappet is inclined, the surface pressure generated between the surface of the tappet and the wall surface of the through hole of the housing is increased, which may cause adverse effects such as seizure.

  In particular, in the tappet described in Japanese Patent Application Laid-Open No. 5-288015, the case member formed in a cup shape is provided on the upper surface of the yoke portion, so that the upper end portion of the case member and the roller member are The distance between them is getting bigger. For this reason, the moment applied to the upper end of the case member is increased by the pressing force applied to the roller member. Along with this, the surface pressure generated between the upper end of the case member and the surface of the housing becomes very large, and adverse effects such as seizure tend to occur.

  Furthermore, in the fuel injection pump described in the above-mentioned Patent Documents 1 to 8, the tappet is integrally formed. For this reason, the material of the tappet cannot be changed in accordance with the exposed environment. For this reason, for example, the surface of the tappet is easily worn, rigidity for supporting the roller member cannot be ensured, and various problems have occurred.

  The present invention has been made in view of the above-described problems, and a first object of the present invention is to reduce the surface pressure generated between the tappet and the surface of the housing on which the tappet slides. It is to provide an ejection pump. The second object is to provide a fuel injection pump whose material can be changed according to the request depending on the position of the tappet.

  In one aspect, a fuel injection pump according to the present invention includes a pressurization chamber capable of pressurizing supplied fuel, a fuel supply unit capable of supplying fuel to the pressurization chamber, and fuel supplied to the pressurization chamber. A plunger that pressurizes the fuel, a fuel discharge portion that can discharge pressurized fuel from the pressurizing chamber to the outside, and a cylinder portion that can support the plunger so as to be able to advance and retreat toward the pressurizing chamber. The fuel injection pump further includes a cam member that is rotatably provided, a roller member that follows the cam member, a roller member that is rotatably supported, and a plunger that is connected to adjust the movement of the roller member. A tappet that moves the plunger forward and backward with respect to the pressurizing chamber, and a housing that can support the tappet so as to advance and retract toward the pressurizing chamber.

  The tappet rotatably supports the roller member, and has a support portion to which the plunger is connected, and a peripheral wall portion that covers the periphery of the support portion. The support portion is connected to the plunger and attached to the peripheral wall portion. It includes a connected top plate portion and a side wall portion that extends from the top plate portion toward the cam member and supports the roller member. And the part located in the circumference | surroundings of the part to which the plunger was connected among the said top-plate parts contains a weak part with a rigidity lower than the part to which the plunger was mounted | worn among top-plate parts.

  Preferably, the thickness of the portion where the fragile portion is located in the top plate portion is made thinner than the thickness of the portion of the top plate portion where the plunger is mounted.

  Preferably, the top plate portion includes a notch portion that is formed at a peripheral edge portion of the top plate portion and is separated from the peripheral wall portion.

  Preferably, the rigidity of the top plate portion when the top plate portion is deformed so that the roller member is displaced along the axis of the shaft portion of the roller member is displaced in a direction in which the roller member intersects the axis of the shaft portion. Thus, it is made larger than the rigidity of a top-plate part when a top-plate part deform | transforms.

  Preferably, the peripheral wall portion extends from the pressure chamber side to the cam member side with respect to the top plate portion, and a length of a portion of the peripheral wall portion located on the cam member side with respect to the top plate portion is The length of the top plate portion is longer than the length of the portion located on the pressure chamber side.

Preferably, the peripheral wall portion is thinned toward the axial direction of the plunger.
In another aspect, the fuel injection pump according to the present invention includes a pressurizing chamber capable of pressurizing the supplied fuel, a fuel supply unit capable of supplying fuel to the pressurizing chamber, and a fuel supplied to the pressurizing chamber. A plunger that pressurizes the fuel, a fuel discharge portion that can discharge pressurized fuel from the pressurizing chamber to the outside, and a cylinder portion that can support the plunger so as to be able to advance and retreat toward the pressurizing chamber.

  Further, the fuel ejection pump includes a cam member that is rotatably provided, a roller member that follows the cam member, a roller member that is rotatably supported, and a plunger that is connected to the pressure chamber. And a support member that moves forward and backward. Furthermore, the support member is separated from the support member, and is attached to the front support member so as to cover the outer periphery of the support member. The peripheral wall member extends to the periphery of the roller member, and the peripheral wall member can be advanced and retracted toward the pressurizing chamber. And a supporting housing.

  Preferably, the support member includes a top surface portion to which a plunger is connected and the peripheral wall member is mounted, and a peripheral wall portion having a hole portion extending from the top surface portion toward the cam member and capable of supporting the shaft portion of the roller member. Including. The peripheral wall member hangs down from the top plate portion toward the cam member so as to reach at least the hole portion from the hole portion. Preferably, the strength of the peripheral wall member is higher than the strength of the support member.

  Preferably, the linear thermal expansion coefficient of the peripheral wall member is matched with the linear thermal expansion coefficient of the housing. Preferably, the peripheral wall member is thinned toward the end portion in the axial direction.

  According to the fuel injection pump according to the present invention, it is possible to reduce the surface pressure generated on the surfaces of the tappet and the housing. Further, according to the fuel injection pump according to the present invention, the material can be changed in accordance with the conditions required by the position of the tappet, and the surface pressure generated on the surfaces of the housing and the tappet can be reduced. .

  A fuel injection pump 100 according to the present embodiment will be described with reference to FIGS. In addition, about the same or an equivalent structure, the same code | symbol is attached | subjected and the description is abbreviate | omitted. FIG. 1 is a cross-sectional view of a fuel injection pump 100 according to the present embodiment, and FIG. 2 is a schematic diagram showing a schematic configuration of the fuel injection pump 100 shown in FIG. The fuel injection pump 100 shown in FIGS. 1 and 2 can be applied to a high-pressure fuel injection pump such as an in-cylinder injection engine, for example.

  The fuel injection pump 100 includes a pressurizing chamber 54 that can pressurize the supplied fuel, and a cylinder chamber 53a that slidably supports a shaft (plunger) 51 that pressurizes the fuel supplied into the pressurizing chamber 54. And a cylinder body 53 that defines

  Further, the fuel ejection pump 100 communicates with the pressurizing chamber 54, and discharges the fuel pressurized in the pressurizing chamber 54 to the outside, and a fuel supply pipe 60 capable of supplying fuel to the pressurizing chamber 54. And a fuel discharge pipe 58.

  A fuel reservoir 90 is provided between the pressurizing chamber 54 and the fuel supply pipe 60, and the fuel reservoir 90 and the pressurizing chamber 54 are connected via a communication portion 91. In the pressurizing chamber 54, an electromagnetic spill valve 55 that opens and closes the communication portion 91 is provided. The electromagnetic spill valve 55 is a normally open type electromagnetic valve that is urged so as to close the communicating portion 91 by an elastic member 61 such as a spring.

  Further, the pressurizing chamber 54 and the fuel discharge pipe 58 are connected via a communication portion 92, and an open / close valve 56 capable of opening and closing the communication portion 92 is provided in the fuel discharge pipe 58. The on-off valve 56 is also urged so as to close the communicating portion 92 by an elastic member 62 such as a spring.

  In FIG. 1, a fuel injection pump 100 includes, for example, a camshaft 31 that is rotationally driven by a driving force from a driving source such as a car engine, a cam member 30 fixed to the outer periphery of the camshaft 31, and a cam member. And a roller member 13 that follows 30.

  The fuel ejection pump 100 includes the tappet 10 that supports the roller member 13 and is connected to the shaft 51.

  The fuel ejection pump 100 further includes a housing 50 that defines a tappet chamber 50a that can slidably support the tappet 10, and the tappet 10 is movably provided along the inner wall surface of the tappet chamber 50a. Yes.

  When the cam member 30 is rotated by the rotation of the cam shaft 31, the roller member 13 is displaced according to the shape of the peripheral surface of the cam member 30. When the roller member 13 is displaced, the tappet 10 is also displaced, and the shaft 51 connected to the tappet 10 advances toward the pressurizing chamber 54 or retracts from the pressurizing chamber 54.

  For example, when the shaft 51 is displaced so as to increase the volume of the pressurizing chamber 54, the internal pressure in the pressurizing chamber 54 decreases, and the electromagnetic spill valve 55 opens the communication portion 91 and passes through the fuel supply pipe 60. The fuel is supplied into the pressurizing chamber 54.

  Thereafter, when the shaft 51 is displaced so as to reduce the volume in the pressurizing chamber 54, the internal pressure in the pressurizing chamber 54 increases and the internal pressure in the pressurizing chamber 54 increases. As a result, the electromagnetic spill valve 55 closes the communication portion 91 and the on-off valve 56 opens the communication portion 92. As a result, the fuel in the pressurizing chamber 54 is ejected to the outside.

  The fuel ejected from the fuel ejection pump 100 is distributed to injectors provided in each cylinder of the engine (internal combustion engine). From these injectors, a predetermined amount of fuel is ejected into the combustion chamber of each cylinder of the engine.

  In the fuel injection pump 100 according to the present embodiment, a solenoid coil 57 is provided so that the displacement of the electromagnetic spill valve 55 can be adjusted. Thereby, when the shaft 51 is displaced so as to reduce the volume of the pressurizing chamber 54 and the pressure in the pressurizing chamber 54 is increased, the electromagnetic spill valve 55 is prevented from immediately closing the communication portion 91. And the state which the communication part 91 open | released can be maintained. As a result, part of the fuel in the pressurizing chamber 54 can escape to the fuel reservoir 90 and the amount of fuel discharged can be adjusted.

  Here, as shown in FIG. 1, the tappet 10 includes a roller support member 12 that supports the roller member 13, and a cylindrical peripheral wall that is provided on the outer peripheral side of the roller support member 12 and is fixed to the roller support member 12. And a member 11.

  FIG. 3 is an enlarged perspective view of the roller support member 12. As shown in FIG. 3, the roller support member 12 includes a top surface portion 14 and a pair of side wall portions 15, 15 depending from the peripheral edge portion of the top surface portion 14. Each side wall portion 15 is formed with a hole portion that rotatably supports the shaft portion 27 of the roller member 13, and the roller member 13 is rotatably supported between the side wall portions 15.

  And the thickness of the part located above the roller member 13 among the top | upper surface parts 14 is made into the thick part 19 made thick. Further, in the top surface portion 14, the portion other than the thick portion 19 is thinner than the thick portion 19, and the weak portion 17 having a smaller rigidity than the thick portion 19 is formed.

  The thick portion 19 is located at the center of the top surface portion 14, and the shaft 51 shown in FIG. 1 is connected to the center of the thick portion 19. Thus, the shaft 51 is connected to the thick portion 19 having high rigidity in the top surface portion 14, and the shaft 51 is favorably supported.

  4 is a plan view of the tappet 10, and FIG. 5 is a cross-sectional view taken along the line VV of FIG. 6 is a cross-sectional view taken along line VI-VI in FIG.

  As shown in FIGS. 4 and 5, the peripheral wall member 11 mounted so as to cover the outer periphery of the roller support member 12 is formed in a cylindrical shape. The thick wall portion 19 has a quadrangular shape when viewed in plan, and is formed so that the arcuate or semicircular fragile portion 17 protrudes from a pair of opposing side portions of the thick wall portion 19. Has been.

  The roller support member 12 and the peripheral wall member 11 are fixed by caulking or welding the outer peripheral edge portion of the fragile portion 17 and the peripheral wall member 11 formed in a cylindrical shape. Here, a portion other than the fragile portion 17 in the peripheral portion of the top surface portion 14 is a notch portion 16 formed so as to be separated from the peripheral wall member 11. Thereby, as shown in FIG. 6, portions of the roller support member 12 other than the fragile portion 17 are separated from the peripheral wall member 11.

  Here, in FIGS. 1 and 5, the peripheral wall member 11 extends from the pressurizing chamber 54 side with respect to the top surface portion 14 to the cam member 30 side with respect to the top surface portion 14.

  For this reason, the concave portion 18 is defined by the surface of the top surface portion 14 on the pressure chamber 54 side and the inner peripheral surface of the peripheral wall member 11.

  As shown in FIG. 1, an elastic member 52 such as a spring that biases the tappet 10 toward the cam member 30 is attached to the recess 18. For this reason, the roller member 13 is pressed against the circumferential surface of the cam member 30 via the tappet 10.

  FIG. 7 is a cross-sectional view when the tappet 10 is displaced along the shape of the outer peripheral surface of the cam member 30.

  In FIG. 7, when the camshaft 31 rotates, the cam member 30 also rotates. Thereby, the roller member 13 is displaced so as to follow the shape of the outer peripheral surface of the cam member 30. The tappet 10 having the roller support member 12 and the peripheral wall member 11 also moves in accordance with the displacement of the roller member 13.

  Thus, in the process in which the tappet 10 is displaced, the roller member 13 may receive a large pressing force in a direction that intersects the sliding direction of the tappet 10. When such a pressing force is applied to the roller member 13, the fragile portion 17 of the roller support member 12 is deformed to allow the roller member 13 to be displaced in a direction intersecting the sliding direction of the tappet 10. .

  In particular, as shown in FIGS. 4 and 7, the weakened portions 17 are arranged along an axis O <b> 2 extending in a direction orthogonal to the axis O <b> 1 of the shaft portion 27 of the roller member 13. For this reason, when this weak part 17 deform | transforms, when it planarly views, the roller member 13 can be displaced along the axis line O2. As shown in FIG. 7, when the roller member 13 receives a large pressing force from the cam member 30 in the direction orthogonal to the shaft portion 27, the roller member 13 can be displaced in the direction orthogonal to the shaft portion 27. Thus, the pressing force applied to the peripheral wall member 11 can be reduced.

  Furthermore, since the top surface portion 14 is formed with a notch 16 that is separated from the inner peripheral surface of the peripheral wall member 11, the rigidity of the top surface portion 14 is reduced, and the top surface portion 14 can be easily deformed. ing.

  Thereby, the pressing force applied from the cam member 30 to the roller member 13 is reduced. Thus, since the pressing force applied to the roller member 13 can be reduced, the surface pressure generated between the outer peripheral surface of the peripheral wall member 11 of the tappet 10 and the inner peripheral surface of the housing 50 defining the tappet chamber 50a. Can be suppressed.

  Accordingly, when the tappet 10 slides in the tappet chamber 50a, the occurrence of seizure between the outer peripheral surface of the peripheral wall member 11 and the tappet chamber 50a of the housing 50 that defines the tappet chamber 50a can be suppressed. Furthermore, it is possible to suppress the occurrence of a hitting sound.

  In addition, as shown in FIG. 4 etc., when forming the weak part 17 in the top | upper surface part 14, the notch part 16 is not an essential structure. FIG. 8 is a plan view showing a first modification of the top surface portion 14. As shown in FIG. 8, the notch portion 16 is not provided, and the entire peripheral edge portion of the top surface portion 14 and the inner peripheral surface of the peripheral wall member 11 may be connected.

  When the top surface portion 14 is formed in this way, the thickness of the portion of the top surface portion 14 adjacent to the thick portion 19 in the direction along the axis O <b> 2 is thinner than that of the thick portion 19. preferable. Furthermore, it is good also as a weak part by making the thickness of the part located in the circumference | surroundings of the part to which the shaft 51 was connected thinner than the thickness of the part to which the shaft 51 is connected among the thick parts 19.

  Further, FIG. 9 is a plan view showing a second modification of the top surface portion 14. As shown in FIG. 9, a slit (through hole) 17 a is formed in the top surface portion 14 so that a part of the top surface portion 14 may be a fragile portion 17.

  10 is a cross-sectional view showing a process in which the roller member 13 and the tappet 10 are displaced along the peripheral surface of the cam member 30, and is a cross-sectional view in a direction different from that in FIG.

  As shown in FIG. 10, for example, the camshaft 31 may be slightly inclined with respect to a predetermined position due to a dimensional error or the like.

  In such a case, the roller member 13 receives a pressing force from the cam member 30. For example, in the example shown in FIG. 10, the shaft portion 27 receives a pressing force that is inclined downward or upward from one end portion of the shaft portion 27 toward the other end portion.

  Even when such a pressing force is received, the fragile portion 17 shown in FIG. 4 is deformed, so that the pressing force that the roller member 13 receives from the cam member 30 can be reduced.

  Thereby, even if the dimensional error has arisen in the cam member 30, the surface thickness produced between the surrounding surface of the surrounding wall member 11 and the wall surface of the tappet chamber 50a can be reduced.

  Here, in general, the dimensional error of the cam member 30 is small. For this reason, as shown in FIG. 10, in order to reduce the pressing force applied to the roller member 13 due to the dimensional error caused by the cam member 30, the displacement amount allowed for the roller member 13 is shown in FIG. Thus, in order to reduce the pressing force applied to the roller member 13 in the process of rotating the cam member 30 arranged at a predetermined position, it is necessary to take a larger displacement amount to the roller member 13.

  Therefore, in FIG. 4, the rigidity in the direction in which the roller member 13 is displaced in the direction along the axis O2 out of the rigidity of the top surface portion 14 is lower than the rigidity in the direction in which the roller member 13 is displaced along the axis O1.

  And the length of the part located in the pressurizing chamber 54 side shown in FIG. 1 with respect to the top surface part 14 among the surrounding wall members 11 is longer than the length of the part located on the cam member 30 side with respect to the top surface part 14. Is also formed long. Thereby, it is suppressed that the edge part by the side of the pressurization chamber 54 and the press position where the cam member 30 presses the roller member 13 are largely separated with respect to the top surface part 14 in the peripheral wall member 11.

  For this reason, when a pressing force is applied to the roller member 13, the moment applied to the end of the peripheral wall member 11 on the pressurizing chamber 54 side can be reduced. Occurrence can be suppressed.

  On the other hand, the portion of the peripheral wall member 11 that is located on the cam member 30 side with respect to the top surface portion 14 is close to the contact point between the roller member 13 and the cam member 30. Due to the pressing force applied, the moment generated in the portion is small.

  Therefore, in FIG. 5, the length of the portion located on the pressurizing chamber 54 side shown in FIG. 1 with respect to the top surface portion 14 is longer than the length of the portion located on the cam member 30 side with respect to the top surface portion 14. By forming, the contact area between the tappet chamber 50a and the contact area of the peripheral wall member 11 can be secured, and the moment generated in the peripheral wall member 11 can be reduced. In particular, the end portion of the peripheral wall member 11 that is located closer to the cam member 30 than the top surface portion 14 reaches at least the shaft portion 27 of the roller member 13, preferably the lower end portion of the roller member 13, It is possible to reduce the moment generated in the peripheral wall member 11 and the friction generated between the inner surface of the housing 50 defining the tappet chamber 50a.

  FIG. 11 is a cross-sectional view showing a modification of the peripheral wall member 11 of the tappet 10. As shown in FIG. 11, the peripheral wall member 11 is formed so that the thickness of the peripheral wall member 11 decreases from the portion of the peripheral wall member 11 to which the top surface portion 14 is fixed toward the end in the axial direction.

  That is, the rigidity of the end portion side of the peripheral wall member 11 is made lower than the rigidity of the portion of the peripheral wall member 11 that is connected to the top surface portion 14. Thus, even when the peripheral wall member 11 is inclined when a large pressing force is applied from the roller support member 12, the end portion of the peripheral wall member 11 is deformed, and the contact between the peripheral wall member 11 and the wall surface of the tappet chamber 50a. The area can be secured, and the frictional force generated between the peripheral wall member 11 and the inner wall surface of the tappet chamber 50a can be reduced.

  Here, the tappet 10 can be easily manufactured because the roller support member 12 and the peripheral wall member 11 are separated from each other, and the peripheral wall member 11 has a cylindrical shape.

  FIG. 12 is a plan view in which the roller support member 12 is developed. As shown in FIG. 12, the roller support member 12 can be manufactured by bending a flat plate member, and can be manufactured at a very low cost. Furthermore, the peripheral wall member 11 is cylindrical, has a very simple shape, and can be easily manufactured. For this reason, for example, the tappet 10 according to the present embodiment can be manufactured at a very low cost as compared with the tappet 10 in which the roller support member 12 and the peripheral wall member 11 are integrally formed by forging or the like. it can.

  Furthermore, since the tappet 10 is composed of the peripheral wall member 11 and the roller support member 12 which is a member different from the peripheral wall member 11, the material can be selected for each member, and the conditions required for each member. A metal that satisfies the requirements can be selected.

  In particular, the peripheral wall member 11 in contact with the inner wall surface of the tappet chamber 50a is made of a metal having higher hardness than the roller support member 12, so that the wear resistance of the peripheral wall member 11 can be ensured. For example, the peripheral wall member 11 may be made of iron that has been heat-treated, and the roller support member 12 may be made of iron that has not been heat-treated. By selecting such a material, the material cost can be reduced. Preferably, the roller support member 12 is higher in rigidity than the peripheral wall member 11 so that the roller support member 12 is not easily deformed by the pressing force from the roller member 13.

  Moreover, it forms so that the linear thermal expansion coefficient of the surrounding wall member 11 and the linear thermal expansion coefficient of the housing 50 which prescribes | regulates the tappet chamber 50a may correspond. Thereby, even if the temperature of the housing 50 and the peripheral wall member 11 fluctuates, a gap occurs between the peripheral surface of the peripheral wall member 11 and the inner peripheral surface of the housing 50 that defines the tappet chamber 50a, or the peripheral wall member 11 It can be suppressed that the frictional force generated between the surface and the inner surface of the tappet chamber 50a becomes excessive. For example, the housing 50 and the peripheral wall member 11 may be made of the same metal such as aluminum.

  13 is a plan view showing a third modification of the top surface portion 14, and FIG. 14 is a cross-sectional view taken along the line XIV-XIV in FIG. FIG. 15 is a plan view showing a fourth modification of the top surface portion 14. Here, as shown in FIGS. 13 and 15, the rigidity of the top surface portion 14 may be reduced by reducing the joint portion between the top surface portion 14 and the peripheral wall member 11.

  In the example shown in FIG. 13, the top surface portion 14 has a polygonal shape, and each corner portion of the top surface portion 14 and the peripheral surface of the peripheral wall member 11 are bonded with solder or the like. Note that the shape is not limited to such a polygonal shape, and may be any shape such as an elliptical shape in which the outer peripheral edge portion, the center point, and the distance differ depending on the position of the peripheral edge portion.

  In this way, the roller member 13 is easily displaced along the axis O1 by adjusting the ratio between the connection portion between the top surface portion 14 and the peripheral wall member 11 and the separation portion between the top surface portion 14 and the peripheral wall member 11. Alternatively, it is possible to adjust whether or not it is easily displaced along the axis O2.

  As described above, in the fuel ejection pump 100 according to the present embodiment, the friction generated between the tappet 10 and the inner surface of the housing 50 defining the tappet chamber 50a is reduced, and the tappet 10 The shaft 51 can slide in the tappet chamber 50a, and the shaft 51 can slide well in the cylinder chamber 53a.

  Along with this, the fuel can be satisfactorily sucked into the pressurizing chamber 54, and the fuel can be discharged from the fuel discharge pipe 58.

  Although the embodiment of the present invention has been described above, it should be considered that the embodiment disclosed this time is illustrative and not restrictive in all respects. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a fuel injection pump, and is particularly suitable for a fuel injection pump that supplies fuel to an engine.

It is sectional drawing of the fuel injection pump which concerns on this Embodiment. It is a schematic diagram which shows schematic structure of the fuel injection pump shown by FIG. It is an expansion perspective view of a roller support member. It is a top view of a tappet. It is sectional drawing in the VV line of FIG. It is sectional drawing in the VI-VI line of FIG. It is sectional drawing when a tappet displaces along the shape of the outer peripheral surface of a cam member. It is a top view which shows the 1st modification of a top | upper surface part. It is a plane which shows the 2nd modification of a top | upper surface part. It is sectional drawing which shows the process in which a roller member and a tappet displace along the surrounding surface of a cam member. It is sectional drawing which shows the modification of the surrounding wall member of a tappet. It is the top view which expand | deployed the roller support member. It is a top view which shows the 3rd modification of a top | upper surface part. It is sectional drawing in the XIV-XIV line | wire of FIG. It is a top view which shows the 4th modification of a top | upper surface part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Tappet, 11 Perimeter wall member, 12 Roller support member, 13 Roller member, 14 Top surface part, 15 Side wall part, 16 Notch part, 17 Fragile part, 18 Recessed part, 19 Thick part, 27 Shaft part, 30 Cam member, 31 Cam Shaft, 50a Tappet chamber, 50 Housing, 51 Shaft, 52 Elastic member, 53 Cylinder body, 53a Cylinder chamber, 54 Pressurizing chamber, 55 Electromagnetic spill valve, 56 On-off valve, 57 Solenoid coil, 58 Fuel discharge pipe, 60 Fuel supply tube.

Claims (11)

A pressurizing chamber capable of pressurizing the supplied fuel; and
A fuel supply unit capable of supplying the fuel to the pressurizing chamber;
A plunger for pressurizing the fuel supplied to the pressurizing chamber;
A fuel discharge section capable of discharging the pressurized fuel from the pressurizing chamber to the outside;
A cylinder portion capable of supporting the plunger so as to advance and retract toward the pressurizing chamber;
A cam member provided rotatably;
A roller member that follows the cam member;
A tappet that rotatably supports the roller member and is connected to the plunger, and moves the plunger forward and backward relative to the pressurizing chamber in accordance with the movement of the roller member;
A housing capable of supporting the tappet so as to be able to advance and retract toward the pressurizing chamber;
With
The tappet rotatably supports the roller member, and has a support part to which the plunger is connected, and a peripheral wall part that covers the periphery of the support part,
The support portion includes a top plate portion connected to the peripheral wall portion, to which the plunger is connected, and a side wall portion that extends from the top plate portion toward the cam member and supports the roller member,
The part located in the circumference | surroundings of the part to which the said plunger was connected among the said top-plate parts is a fuel ejection pump containing a weak part with rigidity lower than the part to which the said plunger was mounted | worn.   2. The fuel ejection pump according to claim 1, wherein a thickness of a portion of the top plate portion where the fragile portion is located is made thinner than a thickness of a portion of the top plate portion to which the plunger is attached.   3. The fuel injection pump according to claim 1, wherein the top plate portion includes a cutout portion formed at a peripheral portion of the top plate portion and spaced from the peripheral wall portion.   The rigidity of the top plate when the top plate is deformed so that the roller member is displaced along the axis of the shaft of the roller member is such that the roller member intersects the axis of the shaft. The fuel ejection pump according to any one of claims 1 to 3, wherein the fuel ejection pump is larger than a rigidity of the top plate portion when the top plate portion is deformed so as to be displaced.   The peripheral wall portion extends from the pressure chamber side to the cam member side with respect to the top plate portion, and a portion of the peripheral wall portion located on the cam member side with respect to the top plate portion. The fuel ejection pump according to any one of claims 1 to 4, wherein a length is longer than a length of a portion located on the pressure chamber side with respect to the top plate portion.   The fuel jet pump according to any one of claims 1 to 5, wherein the peripheral wall portion is thinned toward an axial direction of the plunger. A pressurizing chamber capable of pressurizing the supplied fuel; and
A fuel supply unit capable of supplying the fuel to the pressurizing chamber;
A plunger for pressurizing the fuel supplied to the pressurizing chamber;
A fuel discharge section capable of discharging the pressurized fuel from the pressurizing chamber to the outside;
A cylinder portion capable of supporting the plunger so as to advance and retract toward the pressurizing chamber;
A cam member provided rotatably;
A roller member that follows the cam member;
A support member that rotatably supports the roller member and is connected to the plunger, and moves the plunger forward and backward with respect to the pressurizing chamber;
A peripheral wall member that is separate from the support member, is attached to the support member so as to cover the outer periphery of the support member, and extends to the periphery of the roller member;
A housing that supports the peripheral wall member so as to advance and retract toward the pressurizing chamber;
A fuel jet pump with The support member has a top surface portion to which the plunger is connected and the peripheral wall member is mounted, and a peripheral wall portion having a hole portion that extends from the top surface portion toward the cam member and can support the shaft portion of the roller member. Including
The fuel injection pump according to claim 7, wherein the tubular member hangs down toward the cam member so as to reach from the top plate portion to at least the hole portion from the hole portion.   The fuel injection pump according to claim 7 or 8, wherein the strength of the cylindrical member is higher than the strength of the support member.   The fuel injection pump according to any one of claims 7 to 9, wherein a linear thermal expansion coefficient of the tubular member is matched with a linear thermal expansion coefficient of the housing.   The fuel injection pump according to any one of claims 7 to 10, wherein the cylindrical member is thinned toward an end portion in an axial direction.

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