Fuel supply pump

Abstract

To suppress deterioration of compression efficiency of fuel of a fuel supply pump and suppress mutual movement between fuel and lubrication oil.SOLUTION: A fuel supply pump (10) includes an oil cover (80) that has one end in the axial direction abutting on a first portion (61d) on a plunger barrel (61) side and the other end abutting on a second portion (65a) on a tappet (69) side, that extends / contracts in the axial direction through advancing / retracting movement of the tappet (69) and a plunger (57) and that covers the plunger (57) projecting from a plunger sliding hole (61a) to the tappet (69) side.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fuel supply pump.

Background Art

[0002] As a fuel injection system for injecting fuel into an internal combustion engine, a common rail fuel injection system (also referred to as a common rail system) that supplies fuel to a plurality of fuel injection valves via a common rail (accumulator) that accumulates pressurized fuel is known. In a common rail system, a low-pressure pump sends the fuel in the fuel tank to the fuel supply pump, and the fuel supply pump pressurizes the fuel and pumps it to the common rail.

[0003] The fuel supply pump has a plurality of contact portions and sliding portions, and a lubricant is supplied to the contact portions and the sliding portions in order to prevent seizure at the contact portions and the sliding portions. For example, as shown in Patent Document 1, there is a fuel supply pump configured to have a fuel lubrication region that uses fuel as a lubricant and an oil lubrication region that uses lubricating oil as a lubricant.

[0004] FIG. 4 shows a configuration example of a conventional fuel supply pump. The conventional fuel supply pump 110 includes a pump housing 151, a plunger barrel 161, an inlet / outlet valve 163, a plunger 157, a spring seat 165, a tappet spring 167, and a tappet 169. The pump housing 151 has a cam chamber 152 in which a cam 159 is rotatably disposed, and a cylinder 153 provided in communication with the cam chamber 152. Since the illustrated fuel supply pump includes two pump units having the same configuration, the configuration of one pump unit will be briefly described below.

[0005] The plunger barrel 161 is attached to the cylinder 153. The plunger barrel 161 has a plunger sliding hole 161a that slidably supports the plunger 157, and a valve insertion hole 161b that is provided continuously with the plunger sliding hole 161a and to which the inlet / outlet valve 163 is attached. The tappet 169 is interposed between the plunger 157 and the cam 159 and is slidably provided within the cylinder 153. The tappet spring 167 is provided between the tappet 169 and the plunger barrel 161 and biases the tappet 169 downward.

[0006] The end of the plunger 157 on the side opposite to the inlet / outlet valve 163 side among both ends of the plunger 157 abuts against the upper surface of the tappet 169. A spring seat 165 that moves forward and backward integrally with the tappet 169 is locked to the end of the plunger 157 and moves forward and backward together with the tappet 169. Among the plunger sliding hole 161a, a pressurizing chamber 177 is partitioned by the upper surface of the plunger 157 and the inlet / outlet valve 163.

[0007] As the cam 159 rotates, when the tappet 169 and the plunger 157 move downward due to the biasing force of the tappet spring 167, the volume of the pressurizing chamber 177 expands, and fuel is inhaled into the pressurizing chamber 177 through the inlet / outlet valve 163. Also, as the cam 159 rotates, when the tappet 169 and the plunger 157 move upward against the biasing force of the tappet spring 167, the volume of the pressurizing chamber 177 shrinks, the fuel in the pressurizing chamber 177 is pressurized, and high-pressure fuel is discharged through the inlet / outlet valve 163.

[0008] In the conventional fuel supply pump 110, the contact portion between the valve body and the valve seat portion of the inlet valve 163a, the contact portion between the valve body and the valve seat portion of the outlet valve 163b, and the sliding portion between the outer peripheral surface of the plunger 157 and the inner peripheral surface of the plunger sliding hole 161a are included in the fuel lubrication region 181 that uses fuel as lubricating oil. Further, the sliding portion between the outer peripheral surface of the tappet 169 and the inner peripheral surface of the cylinder 153, the sliding portion between the roller pin 173 and the roller 175, the contact portion between the roller 175 and the cam 159, and the bearing portion of the camshaft (not shown) are included in the oil lubrication region 183 that uses lubricating oil as lubricating oil.

[0009] At the lower end of the plunger barrel 161 located at the boundary between the fuel lubrication region 181 and the oil lubrication region 183, an oil seal 180 into which the plunger 157 is slidably inserted is provided. The oil seal 180 has a function of partitioning the fuel lubrication region 181 and the oil lubrication region 183 and suppressing the mutual flow of fuel and lubricating oil.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] Here, although the oil seal 180 illustrated in FIG. 4 suppresses the mutual flow of fuel and lubricating oil, it is necessary to secure a space for assembling the oil seal 180. For this reason, when the size of the entire fuel supply pump is the same, the lengths (also referred to as supported lengths) L1 and L2 of the plunger 157 supported in the plunger barrel 161 are shortened by an amount corresponding to the length of the oil seal 180. The supported length L1 is the supported length when the plunger 157 is located at the uppermost point, and the supported length L2 is the supported length when the plunger 157 is located at the lowermost point. When the supported lengths L1 and L2 of the plunger 157 on the plunger barrel 161 are shortened, the leakage of high-pressure fuel from the fuel lubrication region 181 to the oil lubrication region 183 increases, and there is a risk that the compression efficiency of the fuel in the pressure chamber 177 decreases.

[0012] The present invention has been made in view of the above problems, and provides a fuel supply pump capable of suppressing a decrease in fuel compression efficiency and suppressing the flow of fuel and lubricating oil.

Means for Solving the Problems

[0013] In order to solve the above problems, according to one aspect of the present invention, there is provided a fuel supply pump including: a pump housing having a cam chamber and at least one cylinder communicating with the cam chamber; a plunger barrel having a plunger sliding hole and attached to the cylinder; a plunger slidably provided in the plunger sliding hole; a tappet slidably provided in the cylinder on the cam chamber side with respect to the plunger barrel; a tappet spring supported between the plunger barrel and the tappet; and a pressurizing chamber formed on the opposite side of both ends of the plunger from the tappet side. As the cam provided in the cam chamber rotates, when the tappet and the plunger move toward the tappet side, fuel is inhaled into the pressurizing chamber, and when the tappet and the plunger move toward the pressurizing chamber side, the fuel in the pressurizing chamber is pressurized to discharge high-pressure fuel. The fuel supply pump further includes an oil cover whose one axial end abuts against a first portion on the plunger barrel side, the other end abuts against a second portion on the tappet side, and which expands and contracts in the axial direction by the reciprocating movement of the tappet and the plunger to cover the plunger protruding from the plunger sliding hole toward the tappet side.

Advantages of the Invention

[0014] As described above, according to the present invention, it is possible to suppress a decrease in the compression efficiency of the fuel of the fuel supply pump and to suppress the exchange of fuel and lubricating oil.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0017] <1. Fuel injection system> First, an example of a fuel injection system for an internal combustion engine to which a fuel supply pump according to an embodiment of the present disclosure can be applied will be described.

[0018] FIG. 1 shows a configuration example of a fuel injection system 1 of a diesel engine including a fuel supply pump according to this embodiment. The fuel injection system 1 is configured as a common rail system including a accumulator (common rail) 19. In this embodiment, the internal combustion engine is a diesel engine, but the type of the internal combustion engine is not particularly limited.

[0019] The fuel injection system 1 includes a fuel tank 3, a feed pump (low-pressure pump) 5 that discharges fuel from the fuel tank 3, a fuel supply pump (high-pressure pump) 10 that pressurizes and pumps the fuel, a common rail 19 that accumulates the fuel pumped from the fuel supply pump 10, and a fuel injection valve (injector) 30 that injects the fuel distributed by the common rail 19 into the cylinders of the internal combustion engine.

[0020] The feed pump 5 has a function of discharging the fuel (diesel oil) in the fuel tank 3 and supplying it to the fuel supply pump 10 via the low-pressure passage 7. The feed pump 5 may be an electric pump or a gear pump that is rotationally driven by the power of the internal combustion engine. The low-pressure passage 7 is provided with a filter 9 between the feed pump 5 and the fuel supply pump 10.

[0021] The fuel supplied from the feed pump 5 has its flow rate controlled by the proportional control valve 13 and is supplied to the pressurizing chamber of the fuel supply pump 10. The surplus fuel is discharged through an overflow valve (not shown) provided in parallel with the proportional control valve 13 into the return passage 25 and refluxed to the fuel tank 3. The fuel supply pump 10 is rotationally driven by the power of the internal combustion engine, pressurizes the fuel supplied to the pressurizing chamber, and pumps it under pressure through the high-pressure fuel passage 15 toward the common rail 19.

[0022] The common rail 19 accumulates the fuel pumped from the fuel supply pump 10, brings it to a high-pressure state, and then distributes it to each fuel injection valve 30 at a uniform pressure. The common rail 19 is provided with a pressure sensor 21 for detecting the pressure in the common rail 19 (also referred to as "rail pressure") and a pressure regulating valve 23 for regulating the rail pressure. The control device 17 controls the driving of the proportional control valve 13 to control the flow rate of the high-pressure fuel supplied to the common rail 19, and controls the driving of the pressure regulating valve 23 so that the rail pressure detected by the pressure sensor 21 becomes the desired pressure. The fuel discharged through the pressure regulating valve 23 is refluxed to the fuel tank 3 through the return passage 29.

[0023] The high-pressure fuel distributed from the common rail 19 to each fuel injection valve 30 flows into a pressure control chamber (not shown) of the fuel injection valve 30. The high-pressure fuel flowing into the pressure control chamber biases the valve body in the direction of closing the injection holes. By discharging a part of the high-pressure fuel in the pressure control chamber, the biasing force of the valve body is weakened, and fuel is injected from the injection holes into the cylinder of the internal combustion engine. The control device 17 controls the driving of the fuel injection valve 30 based on the rail pressure and the target injection amount. At this time, the fuel discharged from the pressure control chamber is refluxed to the fuel tank 3 through a return passage (return pipe) 27 connected to the fuel injection valve 30.

[0024] <2. Fuel Supply Pump> Subsequently, a configuration example of the fuel supply pump according to the present embodiment will be described.

[0025] Figure 2 is a cross-sectional view showing the main part of the fuel supply pump 10. In the following description, when referring to the up, down, left, and right directions, the up, down, left, and right directions shown in the drawing are indicated, and they do not indicate the vertical and horizontal directions in the operating state of the fuel supply pump.

[0026] In the illustrated fuel supply pump 10, pump units 55a and 55b (hereinafter referred to as pump unit 55 when no particular distinction is required) are respectively assembled in two cylinders 53a and 53b (hereinafter referred to as cylinder 53 when no particular distinction is required) formed in the pump housing 51. The two pump units 55a and 55b have the same configuration. However, the two pump units 55a and 55b are assembled such that the directions in which the plungers 57 move forward and backward are opposite to each other, and they discharge fuel alternately.

[0027] The pump housing 51 has a cam chamber 52 in which cams 59a and 59b (hereinafter referred to as cam 59 when no particular distinction is required) are rotatably arranged, and cylinders 53a and 53b provided in communication with the cam chamber 52. The two cylinders 53a and 53b are respectively formed to extend in a direction orthogonal to the rotation axes of the cams 59a and 59b. The two cams 59a and 59b are respectively located below the two cylinders 53a and 53b.

[0028] The pump unit 55 includes a plunger barrel 61, an inlet / outlet valve 63, a plunger 57, a spring seat 65, a tappet spring 67, a tappet 69, and an oil cover 80, respectively.

[0029] The plunger barrel 61 is attached to the cylinder 53. The plunger barrel 61 has a plunger sliding hole 61a that slidably supports the plunger 57, and a valve insertion hole 61b that is continuously provided from the plunger sliding hole 61a and to which the inlet / outlet valve 63 is attached. The lower end of the plunger 57 abuts against the upper surface of the tappet 69.

[0030] The spring seat 65 has a locking portion 65a and a seat portion 65b. The locking portion 65a is located at the central portion of the spring seat 65 and is locked to the lower end portion of the plunger 57. The seat portion 65b is located around the locking portion 65a. The tappet spring 67 is provided sandwiched between the plunger barrel 61 and the spring seat 65 and biases the plunger 57 downward. The upper end of the tappet spring 67 is fitted and positioned in a column portion 61c provided at the lower end portion of the plunger barrel 61. The lower end of the tappet spring 67 abuts against the outer edge portion of the spring seat 65

[0031] The tappet 69 is interposed between the plunger 57 and the cam 59 and is provided slidably in the cylinder 53. The tappet 69 includes a tappet body 71, a roller pin 73, and a roller 75. The spring seat 65 is disposed in contact with the upper surface of the tappet body 71. The roller 75 is rotatably held by a roller pin 73 provided at the lower portion of the tappet body 71. The tappet 69 pushes up the plunger 57 against the biasing force of the tappet spring 67 as the cam 59 rotates.

[0032] The inlet / outlet valve 63 attached to the valve insertion hole 61b of the plunger barrel 61 is composed of an inlet valve 63a and an outlet valve 63b assembled together. A pressure chamber 77 is formed by partitioning a part of the plunger sliding hole 61a by the upper surface of the plunger 57 and the lower surface of the inlet / outlet valve 63.

[0033] As the cam 59 rotates and the tappet spring 67 biases the tappet 69 and the plunger 57 downward, the volume of the pressure chamber 77 increases. At this time, the outlet valve 63b is closed while the inlet valve 63a is opened, and fuel is inhaled into the pressure chamber 77. Also, as the cam 59 rotates and the tappet 69 and the plunger 57 move upward against the biasing force of the tappet spring 67, the volume of the pressure chamber 77 decreases, and the fuel in the pressure chamber 77 is pressurized. At this time, the inlet valve 63a is closed while the outlet valve 63b is opened, and the high-pressure fuel is pumped toward the common rail 19.

[0034] The oil cover 80 has an upper end in the axial direction abutting against the lower end surface 61d (first part) of the upright column part 61c provided at the lower end of the plunger barrel 61, and a lower end in the axial direction abutting against the locking part 65a (second part) of the spring seat 65. The oil cover 80 expands and contracts in the axial direction due to the vertical movement of the tappet 69 and the plunger 57. The oil cover 80 is a member having elasticity that can expand and contract in the axial direction, and is provided so as to cover the plunger 57 protruding from the plunger sliding hole 61a toward the tappet 69 side.

[0035] The fuel supply pump 10 according to the present embodiment has a configuration that combines oil lubrication using the lubricating oil stored in the cam chamber 52 and fuel lubrication using fuel as the lubricating oil. For example, the contact portions between the valve bodies and the valve seat portions of the inlet valve 63a and the outlet valve 63b, respectively, and the sliding portion between the outer peripheral surface of the plunger 57 and the inner peripheral surface of the plunger sliding hole 61a are included in the fuel lubrication region 81 that uses fuel as the lubricating oil. Among these, a part of the fuel in the pressure chamber 77 enters the sliding portion between the outer peripheral surface of the plunger 57 and the inner peripheral surface of the plunger sliding hole 61a, and the leaked fuel functions as the lubricating oil. The leaked fuel is discharged to the return passage through a leak recovery passage (not shown).

[0036] Further, the sliding portion between the outer peripheral surface of the tappet 69 and the inner peripheral surface of the cylinder 53, the sliding portion between the roller pin 73 and the roller 75, the contact portion between the roller 75 and the cam 59, and the bearing portion of the camshaft (not shown) are included in the oil lubrication region 83. In the oil lubrication region, the lubricating oil stored in the cam chamber 52 is scraped up by the rotation of the cam 59 and the roller 75, and enters the sliding portion between the roller pin 73 and the roller 75, and the contact portion between the roller 75 and the cam 59. Further, due to the vertical movement of the tappet 69, the lubricating oil enters the sliding portion between the outer peripheral surface of the tappet 69 and the inner peripheral surface of the cylinder 53.

[0037] The fuel supply pump 10, in which the fuel lubrication region 81 and the oil lubrication region 83 are partitioned above and downstream of the pump unit 55, is mounted on the vehicle such that the cam chamber 52 side is located on the lower side. Note that the mode in which the cam chamber 52 is located on the lower side does not limit that the cylinder 53 extends along the vertical direction.

[0038] The oil cover 80 partitions the fuel lubrication region 81 and the oil lubrication region 83 and has a function of suppressing the mutual flow of fuel and lubricating oil. The oil cover 80 is made of an elastic material, and is elastically supported so that even in the state where the oil cover 80 is most extended, the oil cover 80 is pressed against the lower end surface 61d of the column portion 61c and the locking portion 65a of the spring seat 65, whereby the liquid tightness of the portion in contact with the column portion 61c and the spring seat 65 can be obtained.

[0039] The oil cover 80 may be, for example, a bellows made of an elastic resin (including synthetic rubber), but is not limited thereto. However, if it is a bellows made of an elastic resin, it can be manufactured relatively inexpensively and the resistance to expansion and contraction can be reduced.

[0040] FIG. 3 is an explanatory diagram showing an enlarged view of the periphery of the oil cover 80. In the present embodiment, a recess 61e into which the upper end of the oil cover 80 is fitted is provided on the lower end surface 61d of the column portion 61c of the plunger barrel 61. The step formed by the recess 61e functions as a positioning step 79 for the oil cover 80. Further, when the upper end of the oil cover 80 is fitted into the recess 61e, the liquid tightness between the oil cover 80 and the plunger barrel 61 is further enhanced.

[0041] The positioning step 79 is not limited to being formed by the recess 61e. For example, the positioning step 79 may be a step formed by a ring-shaped groove portion, or may be a step formed by a convex portion protruding from the central portion of the lower end surface 61d of the column portion 61c or a ring-shaped protruding convex portion.

[0042] In addition, in the configuration of the fuel supply pump 10 according to the present embodiment, a partial gap 89 is formed between the lower end of the oil cover 80 and the spring seat 65. However, even if lubricating oil enters the inside of the oil cover 80 from the gap 89, the lubricating oil flows downward due to its own weight, so that the entry of the lubricating oil into the gap between the outer peripheral surface of the plunger 57 and the inner peripheral surface of the plunger sliding hole 61a can be prevented.

[0043] <3. Effects> Subsequently, the effects of the fuel supply pump 10 according to the present embodiment will be described.

[0044] The fuel supply pump 10 according to this embodiment includes a pump housing 51 having a cam chamber 52 and at least one cylinder 53a, 53b communicating with the cam chamber 52, a plunger barrel 61 having a plunger sliding hole 61a and attached to the cylinders 53a, 53b, a plunger 57 slidably provided in the plunger sliding hole 61a, a tappet 69 slidably provided in the cylinders 53a, 53b on the cam chamber 52 side of the plunger barrel 61, a tappet spring 67 supported between the plunger barrel 61 and the tappet 69, and a pressurizing chamber 77 formed on the side opposite to the tappet 69 side at both ends of the plunger 57. Further, as the cams 59a, 59b provided in the cam chamber 52 rotate, fuel is sucked into the pressurizing chamber 77 when the tappet 69 and the plunger 57 move toward the tappet 69 side, and the fuel in the pressurizing chamber 77 is pressurized to discharge high-pressure fuel when the tappet 69 and the plunger 57 move toward the pressurizing chamber 77 side. And the fuel supply pump 10 includes an oil cover 80 whose one end in the axial direction abuts against the first portion (lower end surface 61d) on the plunger barrel 61 side, the other end abuts against the second portion (locking portion 65a) on the tappet 69 side, and expands and contracts in the axial direction by the forward and backward movement of the tappet 69 and the plunger 57 to cover the plunger 57 protruding from the plunger sliding hole 61a toward the tappet 69 side.

[0045] Therefore, as shown in FIG. 2, the support length L1 when the plunger 57 is at the uppermost point and the support length L2 when the plunger 157 is at the lowermost point can be made longer by the length L3 corresponding to the height of the column portion 61c as compared with the configuration using the conventional oil seal 180 shown in FIG. 4. Thereby, the leakage of high-pressure fuel from the fuel lubrication region 81 to the oil lubrication region 83 is suppressed, and the decrease in the compression efficiency of the fuel in the pressurizing chamber 77 can be suppressed.

[0046] Also, the entry of lubricating oil into the gap between the outer peripheral surface of the plunger 57 and the inner peripheral surface of the plunger sliding hole 61a can be prevented, and it can be prevented that the lubricating oil is discharged into the return passage together with the fuel and the accuracy of the fuel decreases.

[0047] Further, in the fuel supply pump 10 according to the present embodiment, the oil cover 80 is preferably a resin bellows. Since the oil cover 80 is a resin bellows, the sealing components can be manufactured at a relatively low cost. Further, the resistance against the expansion and contraction of the oil cover 80 can be reduced, and a decrease in the efficiency of the fuel supply pump 10 can be suppressed.

[0048] Further, in the fuel supply pump 10 according to the present embodiment, one end of the oil cover 80 is preferably fitted into a positioning step 79 formed on the end face of the plunger barrel 61. By fitting one end of the oil cover 80 into the positioning step 79, the assembly of the oil cover 80 becomes easy, the liquid tightness on the plunger barrel 61 side is enhanced, and the effect of preventing the lubricating oil from entering the gap between the outer peripheral surface of the plunger 57 and the inner peripheral surface of the plunger sliding hole 61a can be enhanced.

[0049] As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those having ordinary knowledge in the technical field to which the present invention pertains can conceive various modification examples or correction examples within the scope of the technical idea described in the claims, and it is naturally understood that these also belong to the technical scope of the present invention.

[0050] For example, in the above embodiment, the upper end of the oil cover 80 abuts against the lower end face 61d of the column portion 61c of the plunger barrel 61, and the lower end of the oil cover 80 abuts against the locking portion 65a of the spring seat 65. However, the present disclosure is not limited to this example. The oil cover may be sandwiched between any surface on the plunger barrel 61 side and any surface on the tappet 69 side. For example, in the case of a tappet having a configuration without a spring seat as an independent member, the lower end of the oil cover may abut against the upper surface of the tappet.

[0051] Moreover, the configuration of the fuel supply pump described in the above embodiment is merely an example, and the configurations of the inlet valve and the outlet valve, the configuration of the tappet, the layout of each component, etc. are not limited to the above examples, and the present disclosure can be applied to various fuel supply pumps.

Explanation of Signs

[0052] 1: Fuel injection system 10: Fuel supply pump 51: Pump housing 52: Cam chamber 53a·53b: Cylinder 55a·55b: Pump unit 57: Plunger 59a·59b: Cam 61: Plunger barrel 61a: Plunger sliding hole 61b: Valve insertion hole 61c: Column part 61d: Lower end face 61e: Recess 63: Inlet / outlet valve 65: Spring seat 67: Tappet spring 69: Tappet 77: Pressurizing chamber 79: Positioning step 80: Oil cover 81: Fuel lubrication area 83: Oil lubrication area

Claims

1. A pump housing (51) having a cam chamber (52) and at least one cylinder (53a, 53b) communicating with the cam chamber (52), A plunger barrel (61) having a plunger sliding hole (61a) and attached to the cylinder (53a, 53b), A plunger (57) slidably provided in the plunger sliding hole (61a), A tappet (69) slidably provided in the cylinder (53a, 53b) on the cam chamber (52) side rather than the plunger barrel (61), A tappet spring (67) supported between the plunger barrel (61) and the tappet (69), A pressure chamber (77) formed on the side opposite to the tappet (69) side at both ends of the plunger (57), and comprising, With the rotation of the cams (59a, 59b) provided in the cam chamber (52), when the tappet (69) and the plunger (57) move to the tappet (69) side, fuel is inhaled into the pressure chamber (77), and when the tappet (69) and the plunger (57) move to the pressure chamber (77) side, the fuel in the pressure chamber (77) is pressurized to discharge high-pressure fuel. In a fuel supply pump (10), A fuel supply pump comprising an oil cover (80) whose one end in the axial direction abuts against a first portion (61d) on the plunger barrel (61) side, the other end abuts against a second portion (65a) on the tappet (69) side, and which expands and contracts in the axial direction by the forward and backward movement of the tappet (69) and the plunger (57) to cover the plunger (57) protruding from the plunger sliding hole (61a) to the tappet (69) side.

2. The fuel supply pump according to claim 1, wherein the oil cover (80) is a resin bellows.

3. The fuel supply pump according to claim 1, wherein the one end of the oil cover (80) is fitted into a positioning step (81) formed on the end face of the plunger barrel (61).

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