fuel pump

Abstract

To reduce the size of the entire device with reduction in diameter of a plunger barrel, in a fuel pump.SOLUTION: A fuel pump comprises: a pump head; a plunger barrel provided with a support hole, and having one axial end side of the support hole screwed to the pump head; a plunger supported in the support hole so as to be movable along an axial direction; a pressurization chamber defined by one end of the support hole and one end of the plunger; a fuel discharge passage, one end of which communicates with the pressurization chamber; and a fuel suction passage, one end of which communicates with the pressurization chamber.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a fuel pump applied to an internal combustion engine. [Background technology]

[0002] For example, a common rail fuel injection device applied to a diesel engine includes a fuel pump, a common rail, and a fuel injection valve. The fuel pump draws in fuel from a fuel tank, pressurizes it, and supplies it to the common rail as high-pressure fuel. The common rail maintains the high-pressure fuel supplied from the fuel pump at a predetermined pressure. The fuel injection valve injects the high-pressure fuel from the common rail into the combustion chamber of the diesel engine by opening and closing an injection valve. The fuel pump includes a plunger barrel, a plunger, an intake valve, and a discharge valve. The plunger moves in one direction inside the plunger barrel, opening the intake valve and drawing fuel into the pressurization chamber. The plunger moves in the other direction inside the plunger barrel, pressurizing the fuel in the pressurization chamber and opening the discharge valve to discharge the high-pressure fuel. An example of such a fuel pump is described in Patent Document 1 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-229898 Summary of the Invention [Problem to be solved by the invention]

[0004] A fuel pump draws low-pressure fuel into a pressurization chamber by reciprocating the plunger, and discharges pressurized high-pressure fuel. The plunger is movably supported in a support hole provided in the plunger barrel, and the pressurization chamber is provided at the end of the support hole. Since the pressurization chamber holds high-pressure fuel, a high-precision clearance is required between the plunger and the support hole. In addition, the plunger moves through the support hole at high speed and Under high pressure conditionsSince the image moves at high speed, high reliability against burn-in is also required.

[0005] Conventionally, the plunger barrel is fastened to the pump body with bolts. In this case, multiple bolts penetrate the pump body and thread into the contact portions of the plunger barrel with the pump body to fasten the plunger barrel to the pump body. This structure requires multiple bolts to be arranged on the pump body side, and the multiple bolts must be positioned so as not to interfere with other fixing bolts. This requires space on the barrel side to fasten the multiple bolts, which increases the outer diameter of the plunger barrel and leads to an increase in the size of the fuel pump. Furthermore, uneven fastening force of the multiple bolts can cause elastic deformation of the plunger barrel, potentially reducing the roundness of the support hole.

[0006] The present disclosure is devised to solve the above-mentioned problems, and aims to provide a fuel pump that allows for a reduction in the size of the entire device by reducing the diameter of the plunger barrel. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the fuel pump of the present disclosure includes a pump head, a plunger barrel having a support hole formed therein and one axial end of the support hole screwed to the pump head, a plunger supported in the support hole so as to be movable axially, a pressurized chamber defined by one end of the support hole and one end of the plunger, a fuel discharge passage having one end communicating with the pressurized chamber, and a fuel intake passage having one end communicating with the pressurized chamber. [Effects of the Invention]

[0008] According to the fuel pump of the present disclosure, the diameter of the plunger barrel can be reduced, thereby making it possible to reduce the size of the entire device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a fuel injection device according to this embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing the fuel pump of this embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, showing a vertical section of the fuel pump. [Figure 4] FIG. 4 is an enlarged view showing the mounting structure of the plunger barrel. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0011] <Fuel injection device> FIG. 1 is a schematic diagram showing the configuration of a fuel injection device according to this embodiment.

[0012] 1, the fuel injection device 10 is mounted on a diesel engine (internal combustion engine). The fuel injection device 10 includes a fuel pump 11, a common rail 12, and a plurality of fuel injection valves 13.

[0013] The fuel pump 11 is connected to a fuel tank 14 via a fuel line L11. The fuel pump 11 draws fuel stored in the fuel tank 14 through the fuel line L11 and pressurizes it to generate high-pressure fuel. The fuel pump 11 is connected to a common rail 12 via a high-pressure fuel line L12. The common rail 12 maintains the high-pressure fuel supplied from the fuel pump 11 at a predetermined pressure. The common rail 12 is connected to fuel injection valves 13 via multiple (four in this embodiment) fuel supply lines L13. The fuel injection valves 13 inject the high-pressure fuel from the common rail 12 into each cylinder (combustion chamber) of the diesel engine by opening and closing their injection valves.

[0014] <Fuel pump> Fig. 2 is a longitudinal cross-sectional view of the fuel pump of this embodiment, and Fig. 3 is a longitudinal cross-sectional view of the fuel pump taken along line III-III in Fig. 2. Note that the fuel pump described below is of a type in which three plungers are arranged, but the number of plungers is not limited thereto.

[0015] Figures 2 and 3 As shown in FIG. 1, the fuel pump 11 has a housing formed by bolting together a retainer 21, a pump case 22, and a pump head 23. A camshaft 24 is disposed inside the pump case 22. Each axial end of the camshaft 24 is rotatably supported by the retainer 21 via bearings 25 and 26. One axial end of the camshaft 24 protrudes outside the retainer 21, and a driving force is input from the diesel engine. The camshaft 24 is provided with a plurality of cams 27, 28, and 29 (three in this embodiment) spaced apart in the axial direction. The cams 27, 28, and 29 are each out of phase with one another in the circumferential direction.

[0016] The retainer 21 is fastened to the pump case 22 by a plurality of bolts 30. The plurality of bolts 30 pass through the retainer 21 and have their tips screwed into the pump case 22. The pump head 23 is fastened to the pump case 22 by a plurality of bolts 31. The plurality of bolts 31 pass through the pump head 23 and screwed into the pump case 22.

[0017] Three plunger barrels 32, 33, and 34 are disposed inside the pump case 22 and the pump head 23. Each plunger barrel 32, 33, and 34 has the same configuration. The pump case 22 and the pump head 23 are provided with three housing holes 35, 36, and 37 along a direction perpendicular to the axial direction of the camshaft 24. The housing holes 35, 36, and 37 are formed across the pump case 22 and the pump head 23. Each plunger barrel 32, 33, and 34 is disposed in the corresponding housing hole 35, 36, and 37. That is, each plunger barrel 32, 33, and 34 has, in the axial direction, a first shaft portion 32a, 33a, and 34a, a second shaft portion 32b, 33b, and 34b, a third shaft portion 32c, 33c, and 34c, and a fourth shaft portion 32d, 33d, and 34d. The outer diameters of the plunger barrels 32, 33, and 34 decrease in the order of second shanks 32b, 33b, and 34b, third shanks 32c, 33c, and 34c, first shanks 32a, 33a, and 34a, and fourth shanks 32d, 33d, and 34d. The accommodating holes 35, 36, and 37 have first holes 35a, 36a, and 37a and second holes 35b, 36b, and 37b. The plunger barrels 32, 33, and 34 have first shanks 32a, 33a, and 34a supported by the first holes 35a, 36a, and 37a of the accommodating holes 35, 36, and 37, respectively, and second shanks 32b, 33b, and 34b supported by the second holes 35b, 36b, and 37b.

[0018] Axial support holes 38, 39, 40 are formed inside each plunger barrel 32, 33, 34. The support holes 38, 39, 40 axially penetrate each plunger barrel 32, 33, 34. Plungers 41, 42, 43 are disposed in the support holes 38, 39, 40 of the plunger barrels 32, 33, 34. The plungers 41, 42, 43 are supported in the support holes 38, 39, 40 of the plunger barrels 32, 33, 34, respectively, so as to be movably supported along the axial direction.

[0019] Tappets 44, 45, 46 and rollers 47, 48, 49 are disposed between the plungers 41, 42, 43 and the cams 27, 28, 29, respectively. The rollers 47, 48, 49 are rotatably supported on the tappets 44, 45, 46 by support shafts 50, 51, 52. Spring seats 41a, 42a, 43a are disposed at the axial lower ends of the plungers 41, 42, 43. Compression coil springs 53, 54, 55 are disposed between the plunger barrels 32, 33, 34 and the spring seats 41a, 42a, 43a. The compression coil springs 53, 54, 55 press the plungers 41, 42, 43 against the tappets 44, 45, 46 by the biasing force acting on the spring seats 41a, 42a, 43a, and press the rollers 47, 48, 49 against the cams 27, 28, 29 via the tappets 44, 45, 46. The outer circumferential surfaces of the rollers 47, 48, 49 contact the outer circumferential surfaces of the cams 27, 28, 29.

[0020] In the plunger barrels 32, 33, 34, pressurization chambers 56, 57, 58 are formed at one axial end of the support holes 38, 39, 40. The pressurization chambers 56, 57, 58 are defined by inner circumferential surfaces of the support holes 38, 39, 40, end faces of the plungers 41, 42, 43 at one axial end, and end faces of discharge valves 64, 65, 66 and suction valves 61, 62, 63, which will be described later. The plungers 41, 42, 43 move toward one axial end of the support holes 38, 39, 40, thereby pressurizing the fuel drawn into the pressurization chambers 56, 57, 58.

[0021] Pump head 23 is provided with suction valves 61, 62, and 63 and discharge valves 64, 65, and 66. Pump head 23 is provided with fuel passages 67, 68, and 69 that communicate with support holes 38, 39, and 40 of plunger barrels 32, 33, and 34, respectively. Fuel passages 67, 68, and 69 are aligned in a straight line with support holes 38, 39, and 40. One end of each of fuel passages 67, 68, and 69 communicates with support holes 38, 39, and 40, and a middle portion of each fuel passage communicates with one end of suction passages (fuel suction passages) 70, 71, and 72. The other end of each fuel passage communicates with one end of discharge passages (fuel discharge passages) 73, 74, and 75. Suction passages 70, 71, and 72 are provided in a direction perpendicular to fuel passages 67, 68, and 69. The fuel passages 67, 68, 69 are used as both a fuel intake passage and a part of a fuel discharge passage.

[0022] Suction valves 61, 62, and 63 are disposed in suction passages 70, 71, and 72. The suction valves 61, 62, and 63 are biased by compression coil springs 76, 77, and 78 in a direction to open the suction passages 70, 71, and 72, and are operated by actuators 79, 80, and 81 to close the suction passages 70, 71, and 72. Discharge valves 64, 65, and 66 are disposed in discharge passages 73, 74, and 75. The discharge valves 64, 65, and 66 are biased by compression coil springs 82, 83, and 84 in a direction to close the discharge passages 73, 74, and 75, and are operated by fuel pressure to open the discharge passages 73, 74, and 75. In this case, the pressurization chambers 56, 57, and 58 communicate the fuel passages 67, 68, and 69 with the suction passages 70, 71, and 72.

[0023] The three suction passages 70, 71, and 72 communicate with each other via a communication passage 85. A fuel line L11 (see FIG. 1 for all of these) extending from the fuel tank 14 is connected to the communication passage 85. The discharge passages 73 and 75 are closed by plugs 86 and 87 attached to the other end thereof. A connector 88 is attached to the other end of the discharge passage 74. The three discharge passages 73, 74, and 75 communicate with each other via a communication passage 89. The connector 88 is connected to the common rail 12 (see FIG. 1 for all of these) via a high-pressure fuel line L12. The communication passage 89 communicates the discharge passages 73, 74, and 75 with each other. The communication passage 89 may be disposed in a straight line that intersects with the discharge passages 73, 74, and 75 to directly communicate with them, or may be disposed offset from the discharge passages 73, 74, and 75 in a direction perpendicular to the plane of FIG. 2 to indirectly communicate with them.

[0024] Therefore, when the camshaft 24 rotates, the rotational force is converted by the cams 27, 28, 29 into a reciprocating force, which is transmitted to the rollers 47, 48, 49 and the tappets 44, 45, 46. The movement of the rollers 47, 48, 49 and the tappets 44, 45, 46 causes the plungers 41, 42, 43 to reciprocate axially in the support holes 38, 39, 40 of the plunger barrels 32, 33, 34. The suction valves 61, 62, 63 open the suction passages 70, 71, 72, and when the plungers 41, 42, 43 move axially to the other side (downward in FIGS. 2 and 3 ), low-pressure fuel in the communicating passage 85 is drawn into the compression chambers 56, 57, 58 via the suction passages 70, 71, 72 and the fuel passages 67, 68, 69. When the plungers 41, 42, 43 reach bottom dead center and then move toward top dead center, the actuators 79, 80, 81 are actuated, causing the suction valves 61, 62, 63 to move against the biasing forces of the compression coil springs 76, 77, 78 and close the suction passages 70, 71, 72.

[0025] When the plungers 41, 42, 43 move axially to one side (upward in FIGS. 2 and 3 ) with low-pressure fuel being sucked into the pressurization chambers 56, 57, 58, before the actuators 79, 80, 81 are actuated, the low-pressure fuel is returned from the suction passages 70, 71, 72 to the communication passage 85 via the suction valves 61, 62, 63. After the actuators 79, 80, 81 are actuated, the flow of low-pressure fuel is stopped by the suction valves 61, 62, 63, and the volumes of the pressurization chambers 56, 57, 58 are reduced, thereby pressurizing the low-pressure fuel in the pressurization chambers 56, 57, 58. When the low-pressure fuel in the pressurization chambers 56, 57, 58 is pressurized to a predetermined pressure, the discharge valves 64, 65, 66 move against the biasing forces of the compression coil springs 82, 83, 84 and the pressure received from the common rail 12, thereby opening the discharge passages 73, 74, 75. As a result, the high-pressure fuel in the pressurization chambers 56, 57, 58 is discharged from the fuel passages 67, 68, 69 to the discharge passages 73, 74, 75. The high-pressure fuel in the discharge passages 73, 74, 75 then joins together in the communication passage 89 and is discharged from the connector 88 to the high-pressure fuel line L12 (see FIG. 1 ). Thereafter, when the plungers 41, 42, 43 reach top dead center, the discharge of the high-pressure fuel ends and the plungers 41, 42, 43 begin to move axially to the other side. As a result, the volumes of the pressurization chambers 56, 57, 58 expand, causing the pressure in the pressurization chambers 56, 57, 58 to decrease. The discharge valves 64, 65, 66 move due to the biasing forces of the compression coil springs 82, 83, 84 and the pressure received from the common rail 12, and close the discharge passages 73, 74, 75.

[0026] <Plunger barrel mounting structure> 4 is an enlarged view showing the mounting structure of the plunger barrel. Since the plunger barrels 32, 33, and 34 have almost the same configuration, only the plunger barrel 32 will be described.

[0027] As shown in Figure 4, pump case 22 and pump head 23 are provided with accommodation holes 35 therein, and plunger barrel 32 is supported in accommodation hole 35, with one axial end of plunger barrel 32 being threadedly fastened to pump head 23. That is, plunger barrel 32 has a male thread portion 101 formed on the outer periphery of first shank portion (small diameter portion) 32a. Meanwhile, pump head 23 has a female thread portion 102 formed on the inner periphery of first hole 35a. The male thread portion 101 of first shank portion 32a is threadedly engaged with the female thread portion 102 of first hole 35a in pump head 23, thereby threading plunger barrel 32 to pump head 23.

[0028] The plunger barrel 32 has a support hole 38 formed therein, and the plunger 41 is movably supported in the support hole 38. The pump head 23 is provided with a fuel passage 67 which communicates with the support hole 38. The fuel passage 67 communicates with a suction passage 70 and a discharge passage 73. The suction passage 70 is provided with a suction valve 61 (see FIG. 3 ), and the fuel passage 67 and the discharge passage 73 are provided with a discharge valve 64. In this case, the discharge passage 73 is aligned with the support hole 38, and the suction passage 70 is aligned in a direction perpendicular to the fuel passage 67 and the discharge passage 73. The support hole 38, the pressurizing chamber 56, the fuel passage 67, and the discharge passage 73 are communicated with each other, and the suction passage 70 is communicated with the pressurizing chamber 56 via the fuel passage 67.

[0029] The pressurizing chamber 56 is defined by the inner circumferential surface of the support hole 38, the end face 41b of the plunger 41, and the end face 64a of the discharge valve 64. When one end of the plunger barrel 32 is screwed to the pump head 23, the end face 32a1 of the first shaft portion 32a is brought into close contact with the end face 35a1 of the first hole 35a of the pump head 23, forming a seal portion 103 between the end face 32a1 of the first shaft portion 32a and the end face 35a1 of the first hole 35a. At this time, a minute gap is formed between the end face 32b1 of the second shaft portion 32b and the end face 35b1 of the second hole 35b, so that the end face 32a1 of the first shaft portion 32a and the end face 35a1 of the first hole 35a are constantly in pressure contact, ensuring sealing performance.

[0030] Here, the seal portion 103 and the support hole 38 are concentric. The inner diameter of the seal portion 103 is larger than the inner diameter of the support hole 38 (the outer diameter of the plunger 41). The outer diameter of the male thread portion 101 of the plunger barrel 32 is larger than the outer diameter of the seal portion 103 and is set in the range of 1.8 to 2.3 times the inner diameter of the seal portion 103.

[0031] Two O-rings 104, 105 are attached at an axial distance from each other on the outer periphery of the second shaft portion 32b of the plunger barrel 32. The second shaft portion 32b of the plunger barrel 32 is fitted into the second hole 35b2 of the pump head 23 via the O-ring 104, and the second shaft portion 32b is fitted into the second hole 35b3 of the pump case 22 via the O-ring 105.

[0032] The plunger barrel 32 is provided with a locking portion 106 that can lock a fastening tool (not shown) onto the third shaft portion 32c to rotate the plunger barrel 32. For example, when the fastening tool is a hexagonal spanner or hexagonal wrench, the locking portion 106 has a hexagonal column shape. By locking the fastening tool onto the locking portion 106 and rotating the plunger barrel 32, the male thread portion 101 of the plunger barrel 32 can be threaded into the female thread portion 102 of the pump head 23. Note that the locking portion 106 is not limited to a hexagonal column shape and may be appropriately configured depending on the type of fastening tool.

[0033] The compression coil spring 53 is disposed between the plunger barrel 32 and the tappet 44. The compression coil spring 53 biases the plunger 41 toward the cam 27 (see FIGS. 2 and 3) via the tappet 44 by its biasing force. The plunger barrel 32 has a spring receiving portion 32c1 formed on the end face of the third shaft portion 32c on which the locking portion 106 is formed. One axial end of the compression coil spring 53 is fitted to the spring receiving portion 32c1 of the plunger barrel 32. contact will be done.

[0034] 2, the plunger barrels 32, 33, and 34 are arranged at intervals in the pump head 23 and the pump case 22. In this case, the pitch P of the plunger barrels 32, 33, and 34 is set in the range of 5 to 6 times the inner diameter B (see FIG. 4) of the support holes 38, 39, and 40.

[0035] Therefore, by screwing one axial end of the plunger barrel 32 to the pump head 23, multiple bolts are not required to fasten the plunger barrel 32 to the pump head 23, and the outer diameter of the plunger barrel 32 does not become large.

[0036] [Effects of this embodiment] The fuel pump according to the first aspect includes a pump head 23, plunger barrels 32, 33, 34 each having support holes 38, 39, 40 formed therein and one axial end of which is screwed to the pump head 23, plungers 41, 42, 43 supported in the support holes 38, 39, 40 so as to be freely movable along the axial direction, pressurization chambers 56, 57, 58 defined by one end of the support holes 38, 39, 40 and one end of the plungers 41, 42, 43, discharge passages (fuel discharge passages) 73, 74, 75 each having one end communicating with the pressurization chambers 56, 57, 58, and suction passages (fuel suction passages) 70, 71, 72 each having one end communicating with the pressurization chambers 56, 57, 58.

[0037] In the fuel pump according to the first aspect, one axial end of each plunger barrel 32, 33, 34 is threadedly fastened to the pump head 23, eliminating the need for multiple bolts for fastening the plunger barrels 32, 33, 34 to the pump head 23, and these bolts do not interfere with other fixing bolts. As a result, the outer diameter of each plunger barrel 32, 33, 34 does not increase, allowing the plunger barrels 32, 33, 34 to be made smaller, thereby contributing to the miniaturization of the fuel pump 11. Furthermore, the plunger barrel 32 is not deformed due to uneven fastening force of the bolts used to fasten the plunger barrels 32, 33, 34, and reducing the roundness of one end of each support hole 38, 39, 40.

[0038] In the fuel pump according to the second aspect, the suction passages 70, 71, 72 communicate with the pressurization chambers 56, 57, 58 via the fuel passages (fuel discharge passages) 67, 68, 69. As a result, the pressurization chambers 56, 57, 58 communicate only with the fuel passages 67, 68, 69, and the inner diameters of the support holes 38, 39, 40 that define the pressurization chambers 56, 57, 58 can be reduced.

[0039] In the fuel pump according to the third aspect, the discharge passages 73, 74, 75 are arranged in a straight line with the support holes 38, 39, 40, and the suction passages 70, 71, 72 are arranged in a direction perpendicular to the fuel passages 67, 68, 69. This allows the high-pressure fuel to be discharged in a straight line from the compression chambers 56, 57, 58, and the high-pressure fuel can be discharged efficiently.

[0040] In the fuel pump according to the fourth aspect, the plunger barrels 32, 33, 34 are provided with first shaft portions (small diameter portions) 32a, 33a, 34a and second shaft portions (large diameter portions) 32b, 33b, 34b provided on the other end side of the first shaft portions 32a, 33a, 34a in the axial direction, and a male thread portion 101 is formed on the outer periphery of the first shaft portions 32a, 33a, 34a. The pump head 23 is provided with a receiving hole 35, and the first hole A female thread 102 is formed on the inner circumferential surface of each of 35a, 36a, 37a, and the male thread 101 is threadedly engaged with the female thread 102, thereby fastening the plunger barrels 32, 33, 34 to the pump head 23, and a ring-shaped seal 103 is formed between the end face of the first shaft 32a, 33a, 34a and the end face of the accommodation hole 35, 36, 37, and the inner diameter of the seal 103 is larger than the inner diameter of the support hole 38, 39, 40. This ensures high sealing performance in the seal 103.

[0041] In the fuel pump according to the fifth aspect, the seal portion 103 and the support holes 38, 39, 40 are concentrically formed, which allows the seal portion 103 and the support holes 38, 39, 40 to be machined with high precision.

[0042] In the fuel pump according to the sixth aspect, the outer diameter of the male thread portion 101 is larger than the outer diameter of the seal portion 103 and is set in the range of 1.8 to 2.3 times the inner diameter of the seal portion 103. This ensures high sealing performance in the seal portion 103 and also ensures sufficient fastening force of the male thread portion 101 to the plunger barrels 32, 33, 34.

[0043] In the fuel pump according to the seventh aspect, the accommodation hole 35 includes first holes 35a, 36a, 37a having an internal thread portion 102 formed on the inner circumferential surface thereof, and second holes 35b, 36b, 37b having diameters larger than the first holes 35a, 36a, 37a, and the outer circumferential portions of the second shaft portions 32b, 33b, 34b of the plunger barrels 32, 33, 34 are fitted into the inner circumferential surfaces of the second holes 35b, 36b, 37b via an O-ring 104. This makes it possible to suppress fuel leakage from the pressurizing chambers 56, 57, 58.

[0044] In the fuel pump according to the eighth aspect, the other axial end of each plunger barrel 32, 33, 34 is provided with a locking portion 106 that can be locked by a fastening tool to rotate the plunger barrel 32, 33, 34. This makes it possible to easily fasten the plunger barrel 32, 33, 34 to the pump head using an existing tool.

[0045] In the fuel pump according to the ninth aspect, compression coil springs (biasing members) 53, 54, 55 that bias the plungers 41, 42, 43 in a direction that presses them against the cam are disposed radially outside the plunger barrels 32, 33, 34, and spring receiving portions (biasing members) for the compression coil springs 53, 54, 55 are provided on the end faces of the locking portions 106. This allows the compression coil springs 53, 54, 55 to be easily assembled.

[0046] In the fuel pump according to the tenth aspect, the plunger barrels 32, 33, 34 are arranged at intervals in the pump head 23, and the pitch between the plunger barrels 32, 33, 34 is set in the range of five to six times the inner diameter of the support holes 38, 39, 40. This allows the plunger barrels 32, 33, 34 to be arranged at an appropriate pitch.

[0047] In the above-described embodiment, the support holes 38, 39, and 40 have the same diameter in the axial direction, and one end of each hole communicates with the fuel passages 67, 68, and 69. Limited For example, the support holes may be composed of a main body hole having the same diameter as the support holes 38, 39, and 40 and a small diameter portion having a smaller diameter than the support holes 38, 39, and 40, and the small diameter portion may be connected to the fuel passages 67, 68, and 69. In this case, the plungers 41, 42, and 43 are movably supported only by the main body hole.

[0048] The configuration of the fuel injection device 10 and the configuration of the fuel pump 11 are not limited to those in the above-described embodiment. For example, the number of the common rail 12 and the fuel injection valves 13, the connection position of the fuel pump 11, the number of plungers 41, 42, 43, and the number of plunger barrels 32, 33, 34, etc. may be set as appropriate. [Explanation of symbols]

[0049] 10 Fuel injection device 11 Fuel pump 12 Common rail 13 Fuel injection valve 14 Fuel Tank 21 Retainer 22 Pump case 23 Pump head 24 Camshaft 25,26 Bearings 27, 28, 29 Cam 30,31 volts 32, 33, 34 Plunger barrel 35, 36, 37 Receiving holes 38,39,40 Support hole 41, 42, 43 Plunger 44, 45, 46 Tappets 47,48,49 Laura 50,51,52 Support shaft 53, 54, 55 Compression coil spring (biasing member) 61, 62, 63 Intake valve 64, 65, 66 Discharge valve 67,68,69 Fuel passage 70,71,72 Suction passage 73,74,75 Discharge passage 76, 77, 78 Compression coil spring 79, 80, 81 Actuator 82, 83, 84 Compression coil spring 85 Communication path 86,87 Plug 88 Connector 89 Communication path 101 Male thread 102 Female thread 103 Seal part 104,105 O-ring 106 Locking part L11 fuel line L12 fuel high pressure line L13 Fuel supply line

Claims

1. The pump head and a plunger barrel having a support hole formed therein, the plunger barrel having one axial end of the support hole screwed to the pump head; a plunger supported in the support hole so as to be movable along the axial direction; a pressure chamber defined by one end of the support hole and one end of the plunger; a fuel passage disposed in a straight line with the support hole, the fuel passage having one end communicating with the pressurizing chamber; a fuel discharge passage having one end communicating with the other end of the fuel passage and thereby communicating with the pressurizing chamber; a fuel intake passage having one end communicating with the pressurizing chamber in a direction perpendicular to the middle portion of the fuel passage; A fuel pump comprising:

2. the plunger barrel has a small diameter portion and a large diameter portion provided on the other end side of the small diameter portion in the axial direction, and a male thread portion is formed on the outer periphery of the small diameter portion, while the pump head is provided with an accommodation hole and a female thread portion is formed on the inner circumferential surface of the accommodation hole, and the male thread portion is threadedly engaged with the female thread portion, thereby threading the plunger barrel to the pump head, a ring-shaped seal portion is formed between an end surface of the small diameter portion and an end surface of the receiving hole, and an inner diameter of the seal portion is larger than an inner diameter of the support hole; 2. The fuel pump of claim 1.

3. The seal portion and the support hole are concentrically arranged.

3. The fuel pump of claim 2.

4. The outer diameter of the male thread portion is larger than the outer diameter of the seal portion and is set in the range of 1.8 to 2.3 times the inner diameter of the seal portion.

4. A fuel pump according to claim 2 or 3.

5. The accommodating hole has a first hole having the female thread portion formed on an inner peripheral surface thereof, and a second hole having a diameter larger than that of the first hole, and the outer peripheral portion of the large diameter portion of the plunger barrel is fitted into the inner peripheral surface of the second hole via an O-ring. A fuel pump according to any one of claims 2 to 4.

6. The plunger barrel has a locking portion on the other end side in the axial direction, which is capable of locking with a fastening tool to rotate the plunger barrel. A fuel pump according to any one of claims 1 to 5.

7. a biasing member that biases the plunger in a direction to press the plunger against the cam is disposed on the radially outer side of the plunger barrel, and a spring receiving portion of the biasing member is provided on an end surface of the locking portion; 7. The fuel pump of claim 6.

8. a plurality of the plunger barrels are arranged at intervals in the pump head, and a pitch between the plurality of plunger barrels is set in a range of 5 to 6 times the inner diameter of the support hole; A fuel pump according to any one of claims 1 to 7.

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