Injector

Abstract

To prevent excessively large tensile stress from being applied to a specific portion of a nozzle body 91 of an injector 17.SOLUTION: An injector 17 includes an injector body 52, a nozzle body 91, and a nozzle nut 94 for fixing the nozzle body 91 to the injector body 52. The nozzle body 91 includes: a large diameter part 91a; an intermediate diameter part 91b formed on a nozzle hole 66 side of the large diameter part 91a; a small diameter part 91c formed on the nozzle hole 66 side of the intermediate diameter part 91b; a first nozzle hole side flat surface 91d that is a flat surface connecting the large diameter part 91a and the intermediate diameter part 91b and faces the nozzle hole 66 side; and a second nozzle hole side flat surface 91g that is a flat surface connecting the intermediate diameter part 91b and the small diameter part 91c and faces the nozzle hole 66 side. The nozzle nut 94 includes: a first step part 94d that presses the first nozzle hole side flat surface 91d against the injector body 52 side; and a second step part 94e that presses the second nozzle hole side flat surface 91g against the injector body 52 side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an injector that injects fuel into a combustion chamber of an internal combustion engine.

Background Art

[0002] Conventionally, a direct-injection type internal combustion engine equipped with an injector that directly injects fuel into a combustion chamber of an internal combustion engine is known. In particular, when the direct-injection type internal combustion engine is a diesel engine, a common rail fuel injection control device is widely used.

[0003] The common rail fuel injection control device includes a low-pressure pump that supplies fuel in a fuel tank to a high-pressure pump, a high-pressure pump that pumps the fuel supplied from the low-pressure pump to a common rail, a common rail that accumulates the high-pressure fuel pumped from the high-pressure pump, an injector that injects the high-pressure fuel supplied from the common rail into a combustion chamber of an internal combustion engine, and a control device that receives outputs of various sensors and controls the common rail fuel injection control device.

[0004] The injector used in the common rail fuel injection control device includes a nozzle having a nozzle hole for injecting fuel, a nozzle needle for opening and closing the nozzle hole, a back pressure control chamber that presses the nozzle needle in a direction to close the nozzle hole, and a back pressure control unit that controls the outflow of fuel in the back pressure control chamber. The back pressure control unit closes an opening / closing orifice provided in the back pressure control chamber, thereby seating the nozzle needle on a seat surface of the nozzle to close the nozzle hole. On the other hand, the back pressure control unit opens the opening / closing orifice to leak a part of the fuel in the back pressure control chamber, thereby separating the nozzle needle from the seat surface of the nozzle and injecting fuel from the nozzle hole. (See Patent Document 1)

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] Figure 6 shows a conventional injector 170 disclosed in Patent Document 1. The injector 170 comprises an injector body 520, a nozzle 180, a nozzle nut 900, and a valve piston 550. The nozzle 180 comprises a nozzle body 530 and a nozzle needle 540. The nozzle body 530 is fixed to the injector body 520 by the nozzle nut 900.

[0007] The nozzle body 530 comprises a large-diameter section 530a, a medium-diameter section 530b, and a small-diameter section 530c, in that order from the injector body 520 side. The nozzle body 530 also includes a nozzle-side plane 530d that connects the large-diameter section 530a and the medium-diameter section 530b and faces the nozzle hole 660 side.

[0008] Figure 7 is an enlarged view of the area around the nozzle 180 in the injector 170 shown in Figure 6. Figure 8 is an enlarged view of the part indicated by A in Figure 7. In the injector 170, tensile stress acts on the boundary portion of the nozzle body 530 between the nozzle-side plane 530d and the middle diameter portion 530b (indicated by B in Figure 8; hereafter referred to as part B).

[0009] The tensile stress in question is based on several factors, including the influence of the fuel pressure inside the injector 170. Specifically, as the fuel pressure inside the injector 170 increases, the tensile stress on section B also increases (details will be provided later). For accumulative fuel injection control devices, increasing fuel injection pressure is a common practice to achieve better fuel combustion; however, this increases the tensile stress in section B.

[0010] Furthermore, as shown in Figures 7 and 8, when the injector 170 is mounted on the cylinder head (not shown) of the internal combustion engine, a gasket 100 is placed between the nozzle end face of the nozzle nut 900 and the cylinder head. The gasket 100 prevents exhaust gas generated during the combustion of fuel in the internal combustion engine from entering between the side of the injector 170 and the cylinder head. On the other hand, this exhaust gas does enter between the middle diameter portion 530b of the nozzle body 530 and the nozzle nut 900. (See the arrow indicated by reference numeral 101 in Figure 8) In other words, the B portion that is subjected to the tensile stress is exposed to the exhaust gas of the internal combustion engine.

[0011] The exhaust from an internal combustion engine is hot and contains water vapor. Therefore, part B is in a corrosive environment. Furthermore, as mentioned above, when the fuel injection pressure is increased, the fuel pressure inside the injector 170 increases, which increases the tensile stress on part B, and consequently, there is a risk of stress corrosion cracking in part B. Therefore, a structure that reduces the tensile stress on part B was desired.

[0012] Here, the details of the tensile stress acting on section B will be explained below with reference to Figures 6 to 9. As mentioned above, the tensile stress acting on section B is due to several factors.

[0013] The first factor causing tensile stress in section B is the load received from the nozzle nut 900 when the nozzle body 530 is fixed to the injector body 520 (see reference numeral 110 in Figure 8). When the nozzle body 530 is fixed to the injector body 520, the nozzle hole-side surface 530d of the nozzle body 530 comes into contact with the stepped portion 900a of the nozzle nut 900. That is, the nozzle hole-side surface 530d receives a load from the stepped portion 900a toward the injector body 520.

[0014] As shown in Figure 6, when the nozzle body 530 is fixed to the injector body 520, the nozzle body contact surface 520b of the injector body 520 facing the nozzle body 530 comes into contact with the injector body contact surface 530e of the nozzle body 530 facing the injector body 520. At this time, in order to prevent fuel passing through the injector body 520 and nozzle body 530 from leaking to the outside, the injector body contact surface 530e of the nozzle body 530 is pressed against the nozzle body contact surface 520b of the injector body 520 with a relatively strong force.

[0015] The pressing force is generated when the nozzle body 530 is fixed to the injector body 520, by the stepped portion 900a of the nozzle nut 900 pressing against the nozzle hole-side surface 530d of the nozzle body 530. On the other hand, the contact surface between the stepped portion 900a and the nozzle hole-side surface 530d only needs to have a pressing force sufficient to prevent exhaust gas from the internal combustion engine from entering the injector body 520, and this can be lower than the pressing force required between the injector body contact surface 530e and the nozzle body contact surface 520b. In other words, the nozzle hole-side surface 530d of the nozzle body 530 is subjected to a load that exceeds the load originally required for this part in order to generate the necessary pressing force between the injector body contact surface 530e and the nozzle body contact surface 520b.

[0016] The second factor that generates tensile stress in section B is the load applied to the nozzle needle 540 in the valve closing direction. The nozzle needle 540 receives a load from the nozzle spring 790 located inside the injector body 520 in the valve closing direction of the nozzle 180, i.e., towards the injection hole 660 (see reference numeral 112 in Figure 8). In addition, the nozzle needle 540 receives a load from the fuel pressure in the back pressure control chamber 690 of the injector 170 via the valve piston 550 towards the injection hole 660 (see reference numeral 113 in Figure 8). These loads on the nozzle needle 540 pull the small diameter portion 530c of the nozzle body 530 towards the injection hole 660, increasing the tensile stress in section B. Furthermore, when the injection pressure of the accumulator-type fuel injection control device is increased, the pressing force applied from the back pressure control chamber 690 to the valve piston 550 increases, further increasing the tensile stress in section B.

[0017] A third factor that generates tensile stress in section B is the clamping force used to fix the injector 170. Figure 9 shows an example of how the injector 170 is fixed to the cylinder head 154. The injector 170 is fixed to the cylinder head 154 by a clamping member 155. More specifically, one end of the clamping member 155 abuts against a stepped portion 158 formed on the outer surface of the injector body 520, and when a bolt 156 inserted through the other end of the clamping member 155 is tightened, the injector 170 is pressed toward the nozzle 180 and fixed to the cylinder head 154.

[0018] At this time, the nozzle body 530's nozzle-side surface 530d receives a load from the cylinder head 154 towards the injector body 520 via the nozzle nut 900 (see reference numeral 111 in Figure 8). This load also increases the tensile stress in section B.

[0019] A fourth factor that causes tensile stress in section B is the fuel pressure in the fuel reservoir chamber 640 inside the nozzle body 530. The fuel reservoir chamber 640 is filled with high-pressure fuel. Since the fuel reservoir chamber 640 is close to section B, the fuel pressure in the fuel reservoir chamber 640 also increases the tensile stress in section B (see reference numeral 114 in Figure 8). Furthermore, when the injection pressure of the accumulator-type fuel injection control device is increased, the tensile stress in section B caused by the fuel pressure in the fuel reservoir chamber 640 increases even further.

[0020] This invention was made against the backdrop of the above-mentioned problems, and aims to provide an injector that reduces the tensile stress acting concentrated on a part of the fuel injection nozzle. [Means for solving the problem]

[0021] According to the present invention, an injector for injecting fuel into the combustion chamber of an internal combustion engine, the injector comprises a nozzle body having a fuel injection hole at one end and an injector body contact surface at the other end that contacts the injector body of the injector, and a nozzle nut for fixing the nozzle body to the injector body, wherein the nozzle body has a large diameter portion having the injector body contact surface and a portion with a smaller diameter than the large diameter portion and formed on the side of the fuel injection hole that is smaller than the large diameter portion An injector is provided, having a medium diameter portion, a small diameter portion having a smaller diameter than the medium diameter portion and formed on the nozzle side of the medium diameter portion, a first nozzle-side plane which is a plane facing the nozzle side and connecting the large diameter portion and the medium diameter portion, and a second nozzle-side plane which is a plane facing the nozzle side and connecting the medium diameter portion and the small diameter portion, and the nozzle nut having a first stage portion which presses the first nozzle-side plane toward the injector body side, and a second stage portion which presses the second nozzle-side plane toward the injector body side. [Effects of the Invention]

[0022] The injector of the present invention makes it possible to prevent excessive tensile stress from being applied to specific locations. [Brief explanation of the drawing]

[0023] [Figure 1] It is a configuration diagram of a system of an accumulator type fuel injection control device according to the present invention. [Figure 2] It is a cross-sectional view of an injector according to the first embodiment of the present invention. [Figure 3] It is a partial cross-sectional view of an injector according to the first embodiment of the present invention [Figure 4] It is a partial cross-sectional view of an injector according to the second and third embodiments of the present invention [Figure 5] It is a partial cross-sectional view of an injector according to the fourth and fifth embodiments of the present invention [Figure 6] It is a cross-sectional view of a conventional injector. [Figure 7] It is a partial cross-sectional view of a conventional injector. [Figure 8] It is a partial cross-sectional view of a conventional injector. [Figure 9] It is a diagram showing a method of fixing an injector to a cylinder head.

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described with appropriate reference to the drawings. Note that the members, arrangements, etc. described below do not limit the present invention, and various modifications can be made within the scope of the gist of the present invention. Also, in each figure, those with the same reference numerals indicate the same elements, and the description is appropriately omitted. Also, in each figure, the illustration of detailed parts is appropriately simplified or omitted. Also, duplicate descriptions are appropriately simplified or omitted.

[0025] (First Embodiment) A first embodiment of the present invention will be described with reference to the drawings as appropriate. Figure 1 shows the overall configuration of the fuel injection control device according to this embodiment. The fuel injection control device according to this embodiment is a pressure accumulator type fuel injection control device 10. The pressure accumulator type fuel injection control device 10 is a device for injecting fuel into the cylinders of an internal combustion engine (not shown) mounted on a vehicle, and mainly comprises a fuel tank 1, a low-pressure pump 11, a fuel filter 12, a high-pressure pump 13, a flow control valve 19, a common rail 15, a pressure control valve 23, an injector 17, and an electronic control unit 40 (ECU).

[0026] The low-pressure pump 11 and the high-pressure pump 13 are connected by a low-pressure fuel passage 31, and the high-pressure pump 13 and the common rail 15, and the common rail 15 and the injector 17 are connected by high-pressure fuel passages 33 and 35, respectively. In addition, the high-pressure pump 13, the common rail 15, and the injector 17 are connected by return passages 37, 38, and 39, respectively, for returning excess fuel that is not injected from the injector 17 back to the fuel tank 1.

[0027] The low-pressure pump 11 draws up fuel from the fuel tank 1, pressurizes it, and supplies fuel to the high-pressure pump 13 via the low-pressure fuel passage 31. This low-pressure pump 11 is an in-tank type electric pump located inside the fuel tank 1 and is operated by current supplied from a battery. However, the low-pressure pump 11 may be located outside the fuel tank 1, or it may be integrated with the high-pressure pump 13.

[0028] The high-pressure pump 13 is equipped with a flow control valve 19 that communicates with the inlet portion of the low-pressure fuel and adjusts the discharge amount of the high-pressure pump. The flow control valve 19 uses an electromagnetic proportional control valve in which the stroke amount of the valve member is variable according to the supply current value, and the area of ​​the fuel passage can be adjusted.

[0029] The high-pressure pump 13 pressurizes the fuel introduced by the low-pressure pump 11 via the flow control valve 19 and pumps it to the common rail 15 via the high-pressure fuel passage 33.

[0030] The common rail 15 stores high-pressure fuel pressurized by the high-pressure pump 13 and supplies fuel to each injector 17 connected via the high-pressure fuel passage 35. A rail pressure sensor 25 and a pressure control valve 23 are attached to the common rail 15.

[0031] The rail pressure sensor 25 detects the fuel pressure (hereinafter also referred to as rail pressure) within the common rail 15. The sensor signal from the rail pressure sensor 25 is sent to the electronic control unit 40.

[0032] The pressure control valve 23 is used to adjust the rail pressure by adjusting the flow rate of high-pressure fuel returned from the common rail 15 to the fuel tank 1. The pressure control valve 23 uses an electromagnetic proportional control valve in which the stroke amount of the valve member for opening and closing the fuel passage is variable according to the supply current value, and the area of ​​the fuel passage can be adjusted. Alternatively, a mechanical safety valve that opens when a predetermined pressure is reached may be used.

[0033] The injector 17 includes a nozzle 18 (see Figure 2). The nozzle 18 comprises a nozzle body 91 with a nozzle hole 66 and a nozzle needle 54 that opens and closes the nozzle hole 66 by moving back and forth. The injector 17 closes the nozzle hole 66 by applying back pressure to the rear end of the nozzle needle 54, while opening the nozzle hole 66 when the applied back pressure is released. As a means of controlling the back pressure of the injector 17, an electrostrictive actuator equipped with a piezoelectric element or an electromagnetic solenoid actuator can be used.

[0034] The electronic control unit 40 is centered around a microcomputer of a known configuration and includes memory elements such as RAM and ROM, as well as a drive circuit for driving the injector 17 and a power supply circuit for supplying power to the flow control valve 19 and the pressure control valve 23. In addition, the electronic control unit 40 receives detection signals from the rail pressure sensor 25, as well as various detection signals such as the rotational speed of the internal combustion engine, accelerator opening, and fuel temperature, which are used for controlling the operation of the internal combustion engine and fuel injection.

[0035] Next, the structure of the injector 17 according to the present invention will be described with reference to Figure 2. Figure 2 is a cross-sectional view of the injector 17 in the first embodiment of the present invention. The back pressure control means of the injector 17 shown in Figure 2 is an electromagnetic solenoid type actuator, but it may also be an electrostrictive type actuator. Furthermore, the armature peripheral part of the electromagnetic solenoid type actuator may also be a known structure other than this.

[0036] The injector 17 mainly comprises an injector body 52, a nozzle 18, a valve piston 55, a valve body 56, a back pressure control unit 57, and an inlet connector 58.

[0037] In this specification, when describing the injector 17, unless otherwise specified, the nozzle 18 side is considered the lower side, and the opposite side, i.e., the back pressure control unit 57 side, is considered the upper side.

[0038] The nozzle 18 comprises a nozzle body 91 and a nozzle needle 54. Multiple injection holes 66 for injecting fuel are drilled near the lower end of the nozzle body 91.

[0039] The injector body 52 has a first fuel passage 63 that sends high-pressure fuel introduced from the inlet connector 58 to the nozzle body 91.

[0040] The nozzle body 91 has a fuel reservoir chamber 64 formed in the portion opposite to the pressure-receiving portion 54a of the nozzle needle 54. The nozzle body 91 also has a second fuel passage 61 that communicates with the first fuel passage 63 of the injector body 52 and guides high-pressure fuel to the fuel reservoir chamber 64 and the injection hole 66. The high-pressure fuel in the fuel reservoir chamber 64 pushes the nozzle needle 54 upward via the pressure-receiving portion 54a of the nozzle needle 54.

[0041] The nozzle needle 54 seats (seats) on a seat portion 91f connected to a plurality of injection holes 66 drilled near the lower end of the nozzle body 91, thereby closing the injection holes 66. On the other hand, during fuel injection, the nozzle needle 54 rises (lifts) from the seat portion 91f, opening the injection holes 66.

[0042] A spring chamber 72 is formed within the injector body 52 connected to the nozzle body 91, with its central axis at its center, and a nozzle spring 79 is provided to bias the nozzle needle 54 toward the seat portion 91f.

[0043] A hole 52a is formed above the spring chamber 72 formed in the injector body 52, and is coaxial with the spring chamber 72. A valve piston 55 is inserted into the hole 52a. The valve piston 55 is slidably inserted into a sliding hole 56a formed in the valve body 56, with its upper end face 55a positioned above the nozzle needle 54. The valve body 56 is fixed to the injector body 52 by a valve nut 84.

[0044] A back pressure control chamber 69 is formed in the valve body 56 at the location where the upper end face 55a of the valve piston 55 is located, and the upper end face 55a of the valve piston 55 is viewed from below. The back pressure control chamber 69 communicates with an inlet-side orifice 70 formed in the valve body 56. This inlet-side orifice 70 communicates with a high-pressure oil passage in the inlet connector 58 via a pressure introduction chamber 71 that is formed annularly around the valve body 56 between the valve body 56 and the injector body 52. ​​As a result, high-pressure fuel from the common rail 15 is supplied to the back pressure control chamber 69.

[0045] The back pressure control chamber 69 is also in communication with the opening / closing orifice 73, which can be opened and closed by the valve ball 74 of the back pressure control unit 57, which will be described later. The pressure-receiving area of ​​the upper end face 55a of the valve piston 55 in the back pressure control chamber 69 is set to be larger than the pressure-receiving area of ​​the pressure-receiving portion 54a of the nozzle needle 54.

[0046] The back pressure control unit 57 mainly comprises a solenoid valve 59, a back pressure control chamber 69, and a valve ball 74, and the solenoid valve 59 mainly comprises a magnet section 75, a valve sleeve 77, a valve spring 76, an armature 80, and an armature guide 82.

[0047] The armature guide 82 has a through hole in its center, which holds the armature 80. The armature guide 82 is fixed to the injector body 52 near its outer circumference and has the function of guiding the armature 80. The armature 80 also has an enlarged diameter portion at its upper end.

[0048] When the solenoid valve 59 is energized, the armature 80 is attracted to the magnet section 75 and rises. As a result, the valve ball 74 opens the opening / closing orifice 73, and the fuel flows out of the back pressure control chamber 69, reducing the pressure in the back pressure control chamber 69. This causes the valve piston 55 and nozzle needle 54 to rise, and fuel injection begins. The fuel that flows out of the back pressure control chamber 69 passes through the inside of the solenoid valve 59, through the fuel return passage 65, and is returned to the fuel tank 1 via the return passage 39.

[0049] When the power supply to the solenoid valve 59 is cut off, the attractive force of the magnet portion 75 on the armature 80 is lost, causing the armature 80 to descend due to the biasing force of the valve spring 76. As a result, the valve ball 74 below the armature 80 is pressed against the valve seat portion 78 above the opening / closing orifice 73, causing the opening / closing orifice 73 to close. Then, the fuel pressure in the back pressure control chamber 69 rises, the valve piston 55 and nozzle needle 54 descend, and fuel injection ends.

[0050] Next, the features of the nozzle body 91 and the nozzle nut 94 for fixing the nozzle body 91 to the injector body 52 according to the first embodiment of the present invention will be described. Figure 3 is an enlarged cross-sectional view of the portion indicated by Y in Figure 2. As shown in Figures 2 and 3, the nozzle body 91 of the injector 17 according to this embodiment includes a large-diameter portion 91a including an injector body contact surface 91e that contacts the injector body 52, a medium-diameter portion 91b which is smaller in diameter than the large-diameter portion 91a and located below the large-diameter portion 91a, and a small-diameter portion 91c which is smaller in diameter than the medium-diameter portion 91b and located below the medium-diameter portion 91b. The small-diameter portion 91c is provided with a spray hole 66. Furthermore, the nozzle body 91 includes a first nozzle-side plane 91d, which is a plane facing the nozzle 66 and connects the large-diameter portion 91a and the medium-diameter portion 91b, and a second nozzle-side plane 91g, which is a plane facing the nozzle 66 and connects the medium-diameter portion 91b and the small-diameter portion 91c.

[0051] The lower end surface of the injector body 52 has a nozzle body contact surface 52b that contacts the injector body contact surface 91e of the nozzle body 91. The injector body 52 also has a male threaded portion 52c that extends upward from the nozzle body contact surface 52b over a predetermined range. The inner circumferential surface of the nozzle nut 94 has a female threaded portion 94a that extends downward from the upper end over a predetermined range. As shown in Figure 3, the nozzle body 91 is fixed to the injector body 52 by screwing the female threaded portion 94a of the nozzle nut 94 into the male threaded portion 52c of the injector body 52 while the injector body contact surface 91e of the nozzle body 91 is in contact with the nozzle body contact surface 52b of the injector body 52.

[0052] A tightening portion 94c is formed on the outer circumferential surface of the nozzle nut 94, extending for a predetermined length from the lower end surface 94b of the nozzle nut 94, with a hexagonal cross-section in the axial direction. When the nozzle body 91 is fixed to the injector body 52, the tightening portion 94c is tightened with a tool. The tightening portion 94c does not need to have a hexagonal cross-section in the axial direction, as long as it can be tightened with a tool.

[0053] A first stage 94d and a second stage 94e are formed on the inner circumference of the nozzle nut 94. The first stage 94d and the second stage 94e are formed as planes facing the injector body 52 when the nozzle body 91 is fixed to the injector body 52. ​​When the nozzle body 91 is fixed to the injector body 52, the first stage 94d presses the first nozzle-side plane 91d of the nozzle body 91 upward, and the second stage 94e presses the second nozzle-side plane 91g of the nozzle body 91 upward. In Figure 3, the pressing force received by the first nozzle-side plane 91d from the first stage 94d is indicated by the arrow labeled 120, and the pressing force received by the second nozzle-side plane 91g from the second stage 94e is indicated by the arrow labeled 121.

[0054] By adopting this embodiment, the nozzle body 91 receives the pressing force from the nozzle nut 94 at two locations: the first nozzle-side plane 91d and the second nozzle-side plane 91g. Therefore, it is possible to avoid the pressing force concentrating at one location. Furthermore, because the second nozzle-side plane 91g is located lower than the first nozzle-side plane 91d, the second nozzle-side plane 91g presses the middle diameter portion 91b upward, thereby reducing the tensile stress experienced at the boundary between the first nozzle-side plane 91d and the middle diameter portion 91b.

[0055] Furthermore, as shown in Figure 3, the second nozzle-side plane 91g is formed at a position further away from the fuel reservoir chamber 64 than the first nozzle-side plane 91d. Therefore, this configuration makes it possible to reduce the tensile stress experienced at the boundary between the first nozzle-side plane 91d and the medium-diameter portion 91b in the nozzle body 91.

[0056] (Second Embodiment) Next, a second embodiment of the present invention will be described. In the second embodiment, only the parts that differ from the first embodiment will be described, and the parts that are the same as those in the first embodiment will not be described.

[0057] Figure 4 shows the area around the nozzle body 91 according to the second and third embodiments of the present invention. The second embodiment differs from the first embodiment in that a first spacer 95 is arranged between the first nozzle side plane 91d of the nozzle body 91 and the first stepped portion 94d of the nozzle nut 94.

[0058] In the second embodiment, the nozzle body 91 and nozzle nut 94 are formed such that a first dimension h1, which is the axial distance between the first nozzle-side plane 91d and the second nozzle-side plane 91g of the nozzle body 91, is longer than a second dimension h2, which is the axial distance between the first stage portion 94d and the second stage portion 94e of the nozzle nut 94. In addition, the first spacer 95 is provided in multiple specifications with different thicknesses.

[0059] In the process of fixing the nozzle body 91 to the injector body 52, first, the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94 are measured for the nozzle body 91 and nozzle nut 94 to be assembled. Then, a first spacer 95 with a thickness corresponding to the difference between the first dimension h1 and the second dimension h2 is selected, and with the first spacer 95 positioned between the first injection hole side plane 91d and the first stage portion 94d, the nozzle body 91 is fixed to the injector body 52 by tightening the nozzle nut 94. Note that the nozzle body 91 has a higher hardness than the nozzle nut 94 because it needs to withstand high-pressure fuel. Therefore, in order to reliably apply pressing force to the first injection hole side plane 91d, the first spacer 95 is made of a metal with a hardness of about the same as, or higher than, the nozzle nut 94.

[0060] In this embodiment, when the nozzle body 91 is fixed to the injector body 52, the first stage portion 94d presses the first nozzle-side surface 91d of the nozzle body 91 upward via the first spacer 95, and the second stage portion 94e presses the second nozzle-side surface 91g of the nozzle body 91 upward. In Figure 4, the pressing force received by the first nozzle-side surface 91d is indicated by the arrow labeled 120, and the pressing force received by the second nozzle-side surface 91g is indicated by the arrow labeled 121.

[0061] Therefore, in this embodiment as well, the nozzle body 91 receives the pressing force from the nozzle nut 94 at two locations: the first nozzle-side plane 91d and the second nozzle-side plane 91g. This prevents the pressing force from concentrating at one location. Furthermore, because the second nozzle-side plane 91g is located lower than the first nozzle-side plane 91d, the second nozzle-side plane 91g presses the middle diameter portion 91b upward, thereby reducing the tensile stress experienced at the boundary between the first nozzle-side plane 91d and the middle diameter portion 91b.

[0062] Furthermore, in this embodiment, since a first spacer 95 having a thickness corresponding to the difference between the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94 can be selected and used, the dimensional tolerances of the first dimension h1 and the second dimension h2 can be made larger than in the first embodiment when manufacturing the nozzle body 91 and the nozzle nut 94, and the burden in the manufacturing process can be reduced compared to the first embodiment.

[0063] Furthermore, in this embodiment as well, the second nozzle-side plane 91g is formed at a position further away from the fuel reservoir chamber 64 than the first nozzle-side plane 91d. Therefore, this configuration makes it possible to reduce the tensile stress experienced at the boundary portion between the first nozzle-side plane 91d and the medium-diameter portion 91b in the nozzle body 91.

[0064] (Third embodiment) Next, a third embodiment of the present invention will be described. In the third embodiment, only the parts that differ from the second embodiment will be described, and the parts that are the same as those in the second embodiment will not be described.

[0065] In the third embodiment, as shown in Figure 4, the first spacer 95 is positioned between the first nozzle-side plane 91d of the nozzle body 91 and the first stepped portion 94d of the nozzle nut 94. In the third embodiment, the first spacer 95 is made of a metal having a lower hardness than the nozzle body 91 and the nozzle nut 94.

[0066] In this embodiment, in the step of fixing the nozzle body 91 to the injector body 52, similar to the second embodiment, the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94 are measured for the nozzle body 91 and nozzle nut 94 to be assembled. A first spacer 95 having a thickness that is a predetermined amount greater than the difference between the first dimension h1 and the second dimension h2 is selected, and with the first spacer 95 positioned between the first nozzle side plane 91d and the first step portion 94d, the nozzle body 91 is fixed to the injector body 52 by tightening the nozzle nut 94.

[0067] In this embodiment, the first spacer 95 has a lower hardness than the nozzle body 91 and the nozzle nut 94. Furthermore, in the state before tightening the nozzle nut 94, the first spacer 95 is selected to be a predetermined thickness greater than the difference between the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94. Therefore, in the process of tightening the nozzle nut 94, the first spacer 95 is compressed by the pressing force received from the nozzle nut 94.

[0068] As a result, in this embodiment as well, when the nozzle body 91 is fixed to the injector body 52, the first stage portion 94d presses the first nozzle-side plane 91d of the nozzle body 91 upward via the first spacer 95, and the second stage portion 94e presses the second nozzle-side plane 91g of the nozzle body 91 upward (see reference numerals 120 and 121 in Figure 4).

[0069] Therefore, in this embodiment as well, the nozzle body 91 receives the pressing force from the nozzle nut 94 at two locations: the first nozzle-side plane 91d and the second nozzle-side plane 91g. This prevents the pressing force from concentrating at one location. Furthermore, because the second nozzle-side plane 91g is located lower than the first nozzle-side plane 91d, the second nozzle-side plane 91g presses the middle diameter portion 91b upward, thereby reducing the tensile stress experienced at the boundary between the first nozzle-side plane 91d and the middle diameter portion 91b.

[0070] Furthermore, in this embodiment as well, when manufacturing the nozzle body 91 and the nozzle nut 94, the dimensional tolerances of the first dimension h1 and the second dimension h2 can be made larger than in the first embodiment, thereby reducing the burden on the manufacturing process compared to the first embodiment.

[0071] In this embodiment, the thickness of the first spacer 95 before tightening the nozzle nut 94 can be determined in advance by testing or simulation, taking into account the pressing force that the nozzle body 91 receives from the nozzle nut 94 during tightening, as well as the hardness and elastic modulus of the first spacer 95.

[0072] Furthermore, in this embodiment as well, the second nozzle-side plane 91g is formed at a position further away from the fuel reservoir chamber 64 than the first nozzle-side plane 91d. Therefore, this configuration makes it possible to reduce the tensile stress experienced at the boundary portion between the first nozzle-side plane 91d and the medium-diameter portion 91b in the nozzle body 91.

[0073] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, only the parts that differ from the first embodiment will be described, and the parts that are the same as those in the first embodiment will not be described.

[0074] Figure 5 shows the area around the nozzle body 91 according to the fourth and fifth embodiments of the present invention. The fourth embodiment differs from the first embodiment in that a second spacer 96 is arranged between the second nozzle side plane 91g of the nozzle body 91 and the second stepped portion 94e of the nozzle nut 94.

[0075] In the fourth embodiment, the nozzle body 91 and nozzle nut 94 are formed such that a first dimension h1, which is the axial distance between the first nozzle-side plane 91d and the second nozzle-side plane 91g of the nozzle body 91, is shorter than a second dimension h2, which is the axial distance between the first stage portion 94d and the second stage portion 94e of the nozzle nut 94. In addition, the second spacer 96 is provided in multiple specifications with different thicknesses.

[0076] In the process of fixing the nozzle body 91 to the injector body 52, first, the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94 are measured for the nozzle body 91 and nozzle nut 94 to be assembled. Then, a second spacer 96 with a thickness corresponding to the difference between the first dimension h1 and the second dimension h2 is selected, and with the second spacer 96 positioned between the second injection hole side plane 91g and the second stage portion 94e, the nozzle body 91 is fixed to the injector body 52 by tightening the nozzle nut 94. Note that the nozzle body 91 has a higher hardness than the nozzle nut 94 because it needs to withstand high-pressure fuel. Therefore, in order to reliably apply pressing force to the second injection hole side plane 91g, the second spacer 96 is made of a metal with a hardness of about the same as, or higher than, the nozzle nut 94.

[0077] In this embodiment, when the nozzle body 91 is fixed to the injector body 52, the first stage portion 94d presses the first nozzle-side surface 91d of the nozzle body 91 upward, and the second stage portion 94e presses the second nozzle-side surface 91g of the nozzle body 91 upward via the second spacer 96. In Figure 5, the pressing force received by the first nozzle-side surface 91d is indicated by the arrow labeled 120, and the pressing force received by the second nozzle-side surface 91g is indicated by the arrow labeled 121.

[0078] Therefore, in this embodiment as well, the nozzle body 91 receives the pressing force from the nozzle nut 94 at two locations: the first nozzle-side plane 91d and the second nozzle-side plane 91g. This prevents the pressing force from concentrating at one location. Furthermore, because the second nozzle-side plane 91g is located lower than the first nozzle-side plane 91d, the second nozzle-side plane 91g presses the middle diameter portion 91b upward, thereby reducing the tensile stress experienced at the boundary between the first nozzle-side plane 91d and the middle diameter portion 91b.

[0079] Furthermore, in this embodiment as well, a second spacer 96 having a thickness corresponding to the difference between the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94 can be selected and used. Therefore, when manufacturing the nozzle body 91 and the nozzle nut 94, the dimensional tolerances of the first dimension h1 and the second dimension h2 can be made larger than in the first embodiment, and the burden on the manufacturing process can be reduced compared to the first embodiment.

[0080] Furthermore, in this embodiment as well, the second nozzle-side plane 91g is formed at a position further away from the fuel reservoir chamber 64 than the first nozzle-side plane 91d. Therefore, this configuration makes it possible to reduce the tensile stress experienced at the boundary portion between the first nozzle-side plane 91d and the medium-diameter portion 91b in the nozzle body 91.

[0081] (Fifth embodiment) Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, only the parts that differ from the fourth embodiment will be described, and the parts that are the same as those of the fourth embodiment will not be described.

[0082] In the fifth embodiment, as shown in Figure 5, a second spacer 96 is positioned between the second nozzle-side plane 91g of the nozzle body 91 and the second stage portion 94e of the nozzle nut 94. In the fifth embodiment, a metal having a lower hardness than the nozzle body 91 and the nozzle nut 94 is used as the second spacer 96.

[0083] In this embodiment, in the step of fixing the nozzle body 91 to the injector body 52, similar to the fourth embodiment, the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94 are measured for the nozzle body 91 and nozzle nut 94 to be assembled. Then, a second spacer 96 having a thickness that is a predetermined amount greater than the difference between the first dimension h1 and the second dimension h2 is selected, and with the second spacer 96 positioned between the second injection hole side plane 91g and the second stage portion 94e, the nozzle body 91 is fixed to the injector body 52 by tightening the nozzle nut 94.

[0084] In this embodiment, the second spacer 96 has a lower hardness than the nozzle body 91 and the nozzle nut 94. Furthermore, in the state before tightening the nozzle nut 94, the second spacer 96 is selected to be a predetermined thickness greater than the difference between the first dimension h1 of the nozzle body 91 and the second dimension h2 of the nozzle nut 94. Therefore, in the process of tightening the nozzle nut 94, the second spacer 96 is compressed by the pressing force received from the nozzle nut 94.

[0085] As a result, in this embodiment as well, when the nozzle body 91 is fixed to the injector body 52, the first stage portion 94d presses the first nozzle-side surface 91d of the nozzle body 91 upward, and the second stage portion 94e presses the second nozzle-side surface 91g of the nozzle body 91 upward via the second spacer 96 (see reference numerals 120 and 121 in Figure 4).

[0086] Therefore, in this embodiment as well, the nozzle body 91 receives the pressing force from the nozzle nut 94 at two locations: the first nozzle-side plane 91d and the second nozzle-side plane 91g. This prevents the pressing force from concentrating at one location. Furthermore, because the second nozzle-side plane 91g is located lower than the first nozzle-side plane 91d, the second nozzle-side plane 91g presses the middle diameter portion 91b upward, thereby reducing the tensile stress experienced at the boundary between the first nozzle-side plane 91d and the middle diameter portion 91b.

[0087] Furthermore, in this embodiment as well, when manufacturing the nozzle body 91 and the nozzle nut 94, the dimensional tolerances of the first dimension h1 and the second dimension h2 can be made larger than in the first embodiment, thereby reducing the burden on the manufacturing process compared to the first embodiment.

[0088] In this embodiment, the thickness of the second spacer 96 before tightening the nozzle nut 94 can be determined in advance by testing or simulation, taking into account the pressing force that the nozzle body 91 receives from the nozzle nut 94 during tightening, as well as the hardness and elastic modulus of the second spacer 96.

[0089] Furthermore, in this embodiment as well, the second nozzle-side plane 91g is formed at a position further away from the fuel reservoir chamber 64 than the first nozzle-side plane 91d. Therefore, this configuration makes it possible to reduce the tensile stress experienced at the boundary portion between the first nozzle-side plane 91d and the medium-diameter portion 91b in the nozzle body 91.

[0090] As described above, according to the present invention, it is possible to prevent excessive tensile stress from being applied to specific parts of the nozzle body 91. [Explanation of Symbols]

[0091] 10: Accumulator-type fuel injection control device, 17: Injector, 18: Nozzle, 52: Injector body, 52b Nozzle body contact surface, 64: Fuel reservoir chamber, 66: Injection hole, 91 Nozzle body, 91a: Large diameter section, 91b: Medium diameter section, 91c: Small diameter section, 91d: First injection hole side surface, 91e: Injector body contact surface, 91g: Second injection hole side surface, 94: Nozzle nut, 94d: First stage section, 94e: Second stage section, 95: First spacer, 96: Second spacer

Claims

1. An injector (17) that injects fuel into the combustion chamber of an internal combustion engine, The injector (17) is A nozzle body (91) having a fuel injection hole (66) at one end and an injector body contact surface (91e) at the other end that contacts the injector body (52) of the injector (17), The nozzle body (91) is fixed to the injector body (52) by a nozzle nut (94), The nozzle body (91) has a large diameter portion (91a) having the injector body contact surface (91e), A medium-diameter portion (91b) is smaller in diameter than the large-diameter portion (91a) and is formed on the side of the injection hole (66) that is closer to the large-diameter portion (91a), A smaller diameter portion (91c) is formed on the side of the injection hole (66) that is smaller in diameter than the medium diameter portion (91b), A first nozzle-side plane (91d) is a plane that connects the large-diameter portion (91a) and the medium-diameter portion (91b) and faces the nozzle (66) side, A second nozzle-side plane (91g) is a plane that connects the medium-diameter portion (91b) and the small-diameter portion (91c) and faces the nozzle (66) side, It has, The nozzle nut (94) is A first step portion (94d) presses the first nozzle-side plane (91d) toward the injector body (52), A second stage portion (94e) presses the second nozzle-side plane (91g) toward the injector body (52), It has, The first step portion (94d) is an injector (17) that presses the first nozzle-side plane (91d) toward the injector body (52) via the first spacer (95).

2. The injector (17) according to claim 1, wherein the first spacer (95) is made of a metal having a lower hardness than the nozzle body (91) and the nozzle nut (94).

3. The injector (17) according to claim 1, wherein the first spacer (95) is made of a metal having a hardness equal to or greater than that of the nozzle nut (94).

4. An injector (17) for injecting fuel into the combustion chamber of an internal combustion engine, The injector (17) is A nozzle body (91) having a fuel injection hole (66) at one end and an injector body contact surface (91e) at the other end that contacts the injector body (52) of the injector (17), The nozzle body (91) is fixed to the injector body (52) by a nozzle nut (94), The nozzle body (91) has a large diameter portion (91a) having the injector body contact surface (91e), A medium-diameter portion (91b) is smaller in diameter than the large-diameter portion (91a) and is formed on the side of the injection hole (66) that is closer to the large-diameter portion (91a), A smaller diameter portion (91c) is formed on the side of the injection hole (66) that is smaller in diameter than the medium diameter portion (91b), A first nozzle-side plane (91d) is a plane that connects the large-diameter portion (91a) and the medium-diameter portion (91b) and faces the nozzle (66) side, A second nozzle-side plane (91g) is a plane that connects the medium-diameter portion (91b) and the small-diameter portion (91c) and faces the nozzle (66) side, It has, The nozzle nut (94) is A first step portion (94d) presses the first nozzle-side plane (91d) toward the injector body (52), A second stage portion (94e) presses the second nozzle-side plane (91g) toward the injector body (52), It has, The second stage portion (94e) is an injector (17) that presses the second nozzle side plane (91g) toward the injector body (52) via the second spacer (96).

5. The injector (17) according to claim 4, wherein the second spacer (96) is made of a metal having lower hardness than the nozzle body (91) and the nozzle nut (94).

6. The injector (17) according to claim 4, wherein the second spacer (96) is made of a metal having a hardness equal to or greater than that of the nozzle nut (94).

7. The injector according to any one of claims 1 to 6, wherein the nozzle body (91) includes a fuel reservoir chamber (64) that presses a nozzle needle (54) for opening and closing the injection hole (66) toward the injector body (52) by fuel pressure, and the second injection hole side plane (91g) is formed at a position further away from the fuel reservoir chamber (64) than the first injection hole side plane (91d).

8. An injector (17) for injecting fuel into the combustion chamber of an internal combustion engine, The injector (17) is A nozzle body (91) having a fuel injection hole (66) at one end and an injector body contact surface (91e) at the other end that contacts the injector body (52) of the injector (17), The nozzle body (91) is fixed to the injector body (52) by a nozzle nut (94), The nozzle body (91) has a large diameter portion (91a) having the injector body contact surface (91e), A medium-diameter portion (91b) is smaller in diameter than the large-diameter portion (91a) and is formed on the side of the injection hole (66) that is closer to the large-diameter portion (91a), A smaller diameter portion (91c) is formed on the side of the injection hole (66) that is smaller in diameter than the medium diameter portion (91b), A first nozzle-side plane (91d) is a plane that connects the large-diameter portion (91a) and the medium-diameter portion (91b) and faces the nozzle (66) side, A second nozzle-side plane (91g) is a plane that connects the medium-diameter portion (91b) and the small-diameter portion (91c) and faces the nozzle (66) side, It has, The nozzle nut (94) is A first step portion (94d) presses the first nozzle-side plane (91d) toward the injector body (52), A second stage portion (94e) presses the second nozzle-side plane (91g) toward the injector body (52), It has, The nozzle body (91) includes a fuel reservoir chamber (64) that presses a nozzle needle (54) for opening and closing the injection hole (66) toward the injector body (52) by fuel pressure, and the second injection hole side plane (91g) is formed at a position further away from the fuel reservoir chamber (64) than the first injection hole side plane (91d), in the injector.

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