Injector

Abstract

To prevent application of an excessive tensile stress to a specific location of an a nozzle body 91 of an injector 17.SOLUTION: An injector 17 is for injecting fuel into a combustion chamber of an engine, and the injector 17 includes an injector body 52, a nozzle body 91, and a nozzle nut 92. The injector body 52 has a nozzle body contact surface 52b that comes into contact with the nozzle body 91, and the nozzle body 91 has an injection hole 66 for injecting fuel on one end side and an injector body contact surface 91e on the other end side, which comes into contact with the nozzle body contact surface 52b. The nut 92 is screwed to the injector body 52 and the nozzle body 91 to fix the nozzle body 91 to the injector body 52. One of the screwed portion between the injector body 52 and the nozzle nut 92 and the screw portion between the nozzle body 91 and the nozzle nut 92 is configured as a normal screw, and the other is configured as a reverse screw.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 the closing direction of 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 the 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 disengaging 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 3 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 4 is an enlarged view of the area around the nozzle 180 in the injector 170 shown in Figure 3. Figure 5 is an enlarged view of the part indicated by A in Figure 4. 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 5; 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 4 and 5, 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 5) 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 in section B will be explained below with reference to Figures 3 to 6. As mentioned above, the tensile stress in 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 5). 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 3, 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 5). 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 5). 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 6 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 5). This load also increases the tensile stress in section B.

[0019] A fourth factor that causes tensile stress in part 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 part B, the fuel pressure in the fuel reservoir chamber 640 also increases the tensile stress in part B (see reference numeral 114 in FIG. 5). Further, when the injection pressure of the accumulator-type fuel injection control device is increased to a high pressure, the tensile stress in part B caused by the fuel pressure in the fuel reservoir chamber 640 further increases.

[0020] The present invention has been made against the background of the above problems, and an object thereof is to obtain an injector in which the tensile stress acting intensively on a part of the fuel injection nozzle is reduced.

Means for Solving the Problems

[0021] According to the present invention, there is provided an injector for injecting fuel into a combustion chamber of an engine, the injector including an injector body, a nozzle body, and a nozzle nut, the injector body including a nozzle body abutting surface that abuts against the nozzle body, the nozzle body including a nozzle hole for injecting fuel on one end side and an injector body abutting surface that abuts against the nozzle body abutting surface on the other end side, the nozzle nut fixing the nozzle body to the injector body by screwing with the injector body and the nozzle body, and the screwing portion between the injector body and the nozzle nut and the screwing portion between the nozzle body and the nozzle nut being configured such that one is a right-hand thread and the other is a left-hand thread.

Effects of the Invention

[0022] According to the injector of the present invention, it is possible to prevent excessive tensile stress from being applied to a specific location.

Brief Description of the Drawings

[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 present invention. [Figure 3] It is a cross-sectional view of a conventional injector. [Figure 4] It is a partial cross-sectional view of a conventional injector. [Figure 5] It is a partial cross-sectional view of a conventional injector. [Figure 6] 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, the same reference numerals indicate the same elements, and the description is appropriately omitted. Further, in each figure, the illustration of detailed portions is appropriately simplified or omitted. Also, duplicate descriptions are appropriately simplified or omitted.

[0025] FIG. 1 shows the overall configuration of a fuel injection control device according to the present embodiment. The fuel injection control device according to the present 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 a cylinder of an internal combustion engine (not shown) mounted on a vehicle, and includes 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, an electronic control unit 40 (ECU), etc. as main elements.

[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. Further, return passages 37, 38, and 39 for returning surplus fuel that is not injected from the injector 17 to the fuel tank 1 are connected to the high-pressure pump 13, the common rail 15, and the injector 17, respectively.

[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 this embodiment. 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 facing 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.

[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 area around the nozzle body 91 according to an embodiment of the present invention will be described. As shown in Figure 2, 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 nozzle hole 66. The nozzle body 91 is provided with a nozzle hole side plane 91d which is a plane facing the nozzle hole 66 side and connects the large-diameter portion 91a and the medium-diameter portion 91b. On the outer circumferential surface of the large-diameter portion 91a of the nozzle body 91, a nozzle body side male screw 91h is formed over a predetermined range below the injector body contact surface 91e.

[0051] A nozzle body contact surface 52b is formed on the lower end surface of the injector body 52, which contacts the injector body contact surface 91e of the nozzle body 91. On the outer circumferential surface of the injector body 52, an injector body side male thread 52c is formed over a predetermined range above the nozzle body contact surface 52b.

[0052] The nozzle body 91 is fixed to the injector body 52 by a nozzle nut 92. The nozzle nut 92 is substantially cylindrical, and an injector body-side female thread 92a is formed on the inner circumferential surface of the upper part of the nozzle nut 92 for screwing into the injector body-side male thread 52c of the injector body 52. ​​On the other hand, a nozzle body-side female thread 92b is formed on the inner circumferential surface of the lower part of the nozzle nut 92 for screwing into the nozzle body-side male thread 91h of the nozzle body 91. In addition, a tightening portion 92c is formed near the center of the nozzle nut 92 in the vertical direction, extending for a predetermined length. The tightening portion 92c has a hexagonal cross-section in the axial direction and is used for tightening with a tool. However, the tightening portion 92c does not need to have a hexagonal cross-section in the axial direction as long as it can be tightened with a tool.

[0053] Here, the threaded portion between the male thread 52c on the injector body and the female thread 92a on the injector body, and the threaded portion between the male thread 91h on the nozzle body and the female thread 92b on the nozzle body, are configured such that one is a standard thread (right-hand thread) and the other is a reverse thread (left-hand thread). In other words, the threaded portion between the male thread 52c on the injector body and the female thread 92a on the injector body, and the threaded portion between the male thread 91h on the nozzle body and the female thread 92b on the nozzle body, are configured such that one is a standard thread and the other is a left-hand thread. In this case, it is sufficient for one threaded portion to be standard thread and the other to be a reverse thread; it does not matter which side is standard thread.

[0054] Various methods can be used to fix the nozzle body 91 to the injector body 52 using the nozzle nut 92, but for example, the following method can be used. First, after the assembly of the parts on the injector body 52 side is completed, the injector body 52 side is fixed to the jig so that the top and bottom are reversed, in other words, so that the nozzle body contact surface 52b is facing upward. At that time, the circumferential phase is also aligned to a predetermined position.

[0055] Next, the female thread 92a on the injector body side of the nozzle nut 92 is screwed onto the male thread 52c on the injector body side of the injector body 52 over a predetermined length.

[0056] Next, the nozzle 18 is positioned such that the injector body contact surface 91e of the nozzle body 91 faces the nozzle body contact surface 52b of the injector body 52. ​​At this time, the nozzle needle 54 separates from the seat portion 91f, but the axial dimensions of the nozzle body 91 and nozzle nut 92 are set so that the nozzle needle 54 does not fall out of the nozzle body 91.

[0057] Next, the nozzle body-side male thread 91h of the nozzle body 91 is screwed onto the nozzle body-side female thread 92b of the nozzle nut 92 over a predetermined length.

[0058] Next, the circumferential phase of the nozzle holes 66 of the nozzle body 91 is aligned to a predetermined position, and the rotational direction is fixed using a jig. Various methods can be used to fix the rotational direction of the nozzle body 91, but for example, a double-sided portion can be provided on the middle diameter portion 91b of the nozzle body 91, and the rotational movement can be fixed while axial movement is allowed by clamping the double-sided portion with a jig.

[0059] Next, the nozzle body 91 is fixed to the injector body 52 by tightening the fastening portion 92c. As described above, the threaded portion between the male thread 52c on the injector body side and the female thread 92a on the injector body side, and the threaded portion between the male thread 91h on the nozzle body side and the female thread 92b on the nozzle body side are formed such that one is a standard thread (right-hand thread) and the other is a reverse thread (left-hand thread). Therefore, by tightening the nozzle nut 92, the injector body contact surface 91e of the nozzle body 91 and the nozzle body contact surface 52b of the injector body 52 approach each other and come into contact. Subsequently, the tightening force of the nozzle nut 92 can apply a predetermined pressing force to the injector body contact surface 91e and the nozzle body contact surface 52b.

[0060] Furthermore, a spacer 93 can be placed below the nozzle hole-side plane 91d of the nozzle body 91. This is because, when the nozzle nut 92 according to the present invention is used, and the injector 17 is assembled to a cylinder head (not shown), the gap between the nozzle hole-side plane 91d of the nozzle body 91 and the cylinder head of the engine (not shown) is only the thickness of the gasket, causing the entire injector 17 to shift towards the combustion chamber compared to the conventional method. By placing a spacer 93 below the nozzle hole-side plane 91d, the position of the injector 17 can be kept the same as in the conventional method.

[0061] In other words, by using the spacer 93, when applying the present invention to a conventional injector 17, it becomes unnecessary to adjust the axial length of the injector 17.

[0062] In addition, various methods can be used to position the spacer 93. For example, a guide portion 93c can be formed on the outer circumference of the contact surface 93a of the spacer 93 with respect to the nozzle side plane 91d, and the lower end of the large diameter portion 91a of the nozzle body 91 can be pressed into the guide portion 93c to fix the spacer 93 to the nozzle body 91.

[0063] As described above, according to the present invention, the nozzle body 91 is fixed to the injector body 52 by a cylindrical nozzle nut 92. Therefore, it is possible to eliminate the pressing force applied to the nozzle hole side surface 91d of the nozzle body 91, which is caused by the tightening force of conventional nozzle nuts. With this configuration, the tensile stress applied to the boundary between the nozzle hole side surface 91d and the middle diameter portion 91b can be reduced. [Explanation of symbols]

[0064] 10: Accumulator-type fuel injection control device, 17: Injector, 18: Nozzle, 52: Injector body, 52b Nozzle body contact surface, 66: Injection hole, 91 Nozzle body, 91a: Large diameter section, 91b: Medium diameter section, 91c: Small diameter section, 91d: Injection hole side surface, 91e: Injector body contact surface, 92: Nozzle nut, 93: Spacer, 93c: Guide section

Claims

1. An injector (17) that injects fuel into the combustion chamber of an engine, The injector (17) comprises an injector body (52), a nozzle body (91), and a nozzle nut (92). The injector body (52) is provided with a nozzle body contact surface (52b) that contacts the nozzle body (91), The nozzle body (91) has a fuel injection hole (66) on one end and an injector body contact surface (91e) on the other end that contacts the nozzle body contact surface (52b), The nozzle nut (92) is screwed into the injector body (52) and the nozzle body (91), thereby fixing the nozzle body (91) to the injector body (52). The threaded portion between the injector body (52) and the nozzle nut (92), and the threaded portion between the nozzle body (91) and the nozzle nut (92) are configured such that one is a standard thread and the other is a reverse thread. The nozzle body (91) comprises a large-diameter portion (91a) including the injector body contact surface (91e), a medium-diameter portion (91b) having a smaller diameter than the large-diameter portion (91a) and located below the large-diameter portion (91a), and a nozzle-side plane (91d) connecting the large-diameter portion (91a) and the medium-diameter portion (91b). The injector (17) has a spacer (93) that adjusts the distance between the cylinder head on which the injector (17) is mounted and the nozzle side plane (91d).

2. The spacer (93) is provided with a cylindrical guide portion (93c) that is erected from the outer circumference of the surface that contacts the nozzle side plane (91d), The injector (17) according to claim 1, wherein the spacer (93) is fixed to the nozzle body (91) by press-fitting the large-diameter portion (91a) of the nozzle body (91) into the guide portion (93c).

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