Injector

Abstract

We provide an injector with improved nozzle body durability. [Solution] The injector comprises a nozzle body (4) fixed to the lower end of the housing by a nozzle nut (7). The nozzle body (4) is supported by the nozzle nut (7) by the downward-facing shoulder end face (46) contacting the upward-facing support surface (70) of the nozzle nut (7). The contact point (CT) between the shoulder end face (46) and the support surface (70) is closer to the second shoulder end (49) than to the first shoulder end (48), or closer to the second support end (75) than to the first support end (74). The first shoulder end (48) is the radially outer end of the shoulder end face (46), and the second shoulder end (49) is the radially inner end of the shoulder end face (46). The first support end (74) is the radially outer end of the support surface (70), and the second support end (75) is the radially inner end of the support surface (70).

Description

Technical Field

[0001] The present invention relates to an injector for injecting a fluid.

Background Art

[0002] Conventionally, injectors for various applications are known. For example, in the technical field of automobiles, an injector for injecting fuel from a common rail into an internal combustion engine is known (see, for example, Patent Document 1). The injector includes a nozzle body that defines a flow path for a fluid to be injected, such as fuel, and a housing that constitutes the outer shell of the injector. The nozzle body is fastened to the housing by a nozzle nut.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, there is a portion of the nozzle body where high stress acts due to fastening to the housing by the nozzle nut. Furthermore, depending on the environment in which the injector is installed and the material of the nozzle body, corrosion of the nozzle body may occur. Specifically, the nozzle body of an injector that injects fuel into an internal combustion engine is arranged such that one end having an injection hole faces the inside of the combustion chamber of the internal combustion engine. When the combustion of fuel in the internal combustion engine is insufficient, after the operation of the internal combustion engine ends, the inside of the combustion chamber may have high humidity, that is, the gaseous fuel may be dense in the combustion chamber. Also, the fuel may contain components that cause corrosion of the nozzle body. When the nozzle body is exposed to such an environment where the gaseous fuel is dense, deterioration of the portion where stress is concentrated particularly easily progresses, and as a result, damage to the nozzle body may occur.

[0005] This invention was made to solve the above problems and aims to provide an injector with improved nozzle body durability. [Means for solving the problem]

[0006] An injector (1) according to one aspect of the present invention is an injector (1) for injecting a fluid to be injected, comprising: a housing (2) constituting an outer shell; a nozzle body (4) located below the housing (2) and having an injection hole (40) formed at its lower end which is an opening for injecting the fluid from the internal space of the housing (2) to the outside; and a nozzle nut (7) for fixing the nozzle body (4) to the lower end of the housing (2), wherein the nozzle body (4) comprises a cylindrical first body (44) and a cylindrical part located above the first body (44), The injector (1) includes a first body (44) and a second body (45) having an outer diameter larger than the outer diameter of the first body (44), the central axis of the first body (44) and the central axis of the second body (45) being equal to the central axis of the injector (1), the upper end surface of the first body (44) and a part of the lower end surface of the second body (45) being connected, the nozzle nut (7) having a first nut portion (71) whose inner circumferential surface is facing the outer circumferential surface of the first body (44), and a second nut portion (71) located above the first nut portion (71) having an inner diameter larger than the inner diameter of the first nut portion (71) and whose inner circumferential surface is facing the second body (45) The second nut portion (72) is located opposite the outer circumferential surface of the first nut portion (71), and the central axis of the first nut portion (71) and the central axis of the second nut portion (72) are equal to the central axis of the injector (1). A part of the upper end surface of the first nut portion (71) and the lower end surface of the second nut portion (72) are connected. The shoulder end surface (46), which is the lower end surface of the second body (45) and not connected to the upper end surface of the first body (44), is connected to the support surface (70), which is the upper end surface of the first nut portion (71) and not connected to the lower end surface of the second nut portion (72). The contact point (CT) between the shoulder end face (46) and the support surface (70) is located at least one of the following positions: closer to the second shoulder end (49) than the first shoulder end (48), and closer to the second support end (75) than the first support end (74). The first shoulder end (48) is the radially outer end of the shoulder end face (46), the second shoulder end (49) is the radially inner end of the shoulder end face (46), and the first support end (74) is the radially outer end of the support surface (70).The second support end (75) is the inner end in the radial direction of the support surface (70). [Effects of the Invention]

[0007] According to the injector of the present invention, the contact point between the shoulder end face of the nozzle body and the support surface of the nozzle nut is located at at least one of the following positions: closer to the second shoulder end than the first shoulder end, and closer to the second support end than the first support end. This shortens the distance between the contact point and the central axis. Therefore, the bending moment caused by the force from the nozzle nut acting on the nozzle body can be reduced. This reduces the stress in the parts of the nozzle body where stress is concentrated. Therefore, the durability of the nozzle body 4 can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram illustrating a cross-section of an injector according to an embodiment. [Figure 2] This is a diagram illustrating the forces acting on the nozzle body in the embodiment. [Figure 3] This diagram illustrates the tensile stress that occurs at the base of the shoulder portion. [Figure 4] This diagram schematically shows the shoulder and support sections in the comparative example. [Figure 5] This diagram schematically shows the force acting on the base portion in the comparative example. [Figure 6] This diagram schematically shows the shoulder portion and support portion in the embodiment. [Figure 7] This diagram schematically illustrates the force acting on the base portion in the embodiment. [Figure 8] This is a schematic diagram showing another example of the configuration of the first nut portion in the embodiment. [Modes for carrying out the invention]

[0009] The injector according to the embodiment will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and can be modified in various ways without departing from the spirit of the invention. Furthermore, the present invention includes all possible combinations of the configurations shown in the following embodiments. Also, the injector shown in the drawings is illustrative of the injector of the present invention, and the present invention is not limited by the drawings. In each figure, components with the same reference numerals are the same or corresponding to each other, and this is common throughout the entire specification. Note that the relative sizes of the components in each figure are not limited to those shown in the figures.

[0010] Figure 1 is a diagram illustrating a cross-section of an injector 1 according to an embodiment. This cross-section is a cross-section along the central axis of the injector 1 and passes through the central axis. The injector 1 according to the embodiment is, for example, a fuel injection valve that injects fuel into the combustion chamber of an internal combustion engine such as a diesel engine. In the following, the up, down, left, and right directions when the injector 1 is installed will be described as the up, down, left, and right directions. That is, the end on the side where the injection hole 40, which will be described later, is formed will be described as the lower end, and the end opposite to the end on the side of the injection hole 40 will be described as the upper end. However, even if the injector 1 is not installed with the injection hole 40 on the lower side, the side on which the injection hole 40 is provided will be described as the lower side, and the side opposite to the side on which the injection hole 40 is provided will be described as the upper side.

[0011] As shown in Figure 1, the injector 1 comprises a housing 2, an inlet section 3, a nozzle body 4, a nozzle needle 5, a nozzle spring 6, a nozzle nut 7, a valve 8, and a pressure control section 9, etc. The housing 2 constitutes the outer shell of the injector 1. In detail, the housing 2 is provided with a first hole 20 extending in a direction along the central axis of the injector 1, and components such as the valve 8 are housed inside the first hole 20. The central axis of the first hole 20 and the central axis of the housing 2 coincide with each other, and also coincides with the central axis of the injector 1. Hereafter, the direction of the central axis of the injector 1 may also be referred to as the axial direction. In Figure 1, a portion of the central axis is shown by a dashed line.

[0012] The housing 2 is provided with an inlet section 3. The inlet section 3 has a first flow path 30 formed therein for guiding a fluid, such as fuel from a common rail, into the housing 2. The housing 2 also has a second flow path 21 formed therein. The second flow path 21 communicates with the first flow path 30 and circulates the fluid from the first flow path 30 into the housing 2.

[0013] The nozzle body 4 is fixed to the lower end of the housing 2 by a nozzle nut 7. The central axes of the nozzle body 4 and the nozzle nut 7 coincide with the central axis of the injector 1. The housing 2 is formed in a male thread shape and screws into the nozzle nut 7. The nozzle nut 7 supports the nozzle body 4 from below by a support part 73, which will be described later. In this way, the nozzle body 4 is fixed to the lower end of the housing 2.

[0014] The nozzle body 4 defines a fluid flow path. A second hole 43 serving as the flow path is formed along the central axis of the injector 1, and a nozzle needle 5 is accommodated inside the second hole 43. The central axis of the second hole 43 and the central axis of the nozzle body 4 coincide with each other and also coincide with the central axis of the injector 1. An injection hole 40 is formed at the lower end portion of the nozzle body 4. A seat portion 41 is provided on the side of the internal space of the nozzle body 4, at the periphery of the injection hole 40 and at portions connected to the periphery. The seat portion 41 is for seating the lower end portion of the nozzle needle 5.

[0015] The injection hole 40 is closed when the lower end portion of the nozzle needle 5 seats on the seat portion 41, and is opened when the lower end portion of the nozzle needle 5 separates from the seat portion 41. When the injection hole 40 is opened, the fluid is injected to the outside of the injector 1, and when the injection hole 40 is closed, the injection of the fluid stops.

[0016] A spring chamber 22 is formed inside the housing 2, and a nozzle spring 6 is disposed in the spring chamber 22. The nozzle spring 6 biases the nozzle needle 5 toward the seat portion 41.

[0017] A reservoir chamber 42 is formed inside the nozzle body 4, and the reservoir chamber 42 communicates with the second hole 43 that accommodates the nozzle needle 5. The housing 2 and the nozzle body 4 are formed with a third flow path 23 that communicates with the first flow path 30 of the inlet portion 3 and allows the fluid from the inlet portion 3 to flow into the reservoir chamber 42.

[0018] A pressure receiving portion 50 is formed at the portion of the nozzle needle 5 located inside the reservoir chamber 42. An upward pressure by the fluid in the reservoir chamber 42 acts on the pressure receiving portion 50.

[0019] The valve 8 has a valve body 80 and a valve piston 81. The valve body 80 is accommodated in the housing 2, and a pressure introduction chamber 24 is formed between the valve body 80 and the housing 2. The pressure introduction chamber 24 is formed annularly in the circumferential direction of the valve body 80 and communicates with the second flow path 21.

[0020] The valve piston 81 is disposed above the nozzle needle 5. The upper end portion of the valve piston 81, including the piston upper end 83 which is the upper end of the valve piston 81, is slidably disposed in a piston chamber 82 formed in the valve body 80.

[0021] A control pressure chamber 84 is formed by the piston upper end 83 and the wall portion of the valve body 80 that forms the piston chamber 82. The control pressure chamber 84 communicates with an introduction side orifice passage 85 formed in the valve body 80. The introduction side orifice passage 85 communicates with the second flow path 21 via the pressure introduction chamber 24. Thus, the fluid from a common rail or the like flows in the order of the first flow path 30, the second flow path 21, the pressure introduction chamber 24, and the introduction side orifice passage 85 and flows into the control pressure chamber 84.

[0022] Also, the control pressure chamber 84 is also connected to an opening / closing orifice passage 86 formed in the valve body 80. The opening / closing orifice passage 86 can be opened and closed by the pressure control unit 9.

[0023] The pressure control unit 9 is, for example, a solenoid valve that opens and closes the opening / closing orifice passage 86. The pressure control unit 9 in the embodiment includes an electromagnet 90, an armature plate 91, an armature bolt 92, an armature guide 93, a spring 94, etc.

[0024] The pressure control unit 9 includes a holder 95 in which a reflux path 95a for refluxing the fluid to a tank (not shown) is formed. The holder 95 and the electromagnet 90 are integrated by an electromagnet housing 96. The electromagnet housing 96 is fastened to the housing 2 by a housing nut 97.

[0025] When the electromagnet 90 receives a drive current from a control circuit (not shown), it generates an electromagnetic force that attracts the armature plate 91.

[0026] The armature bolt 92 has a shaft portion 92a and a head portion 92b. The shaft portion 92a is inserted through the armature guide 93. The head portion 92b is provided at the upper end of the shaft portion 92a and engages with the armature plate 91. A control valve body 98 is provided at the lower end of the shaft portion 92a. The control valve body 98 opens and closes the opening and closing orifice passage 86.

[0027] The spring 94 applies a downward biasing force to the head portion 92b.

[0028] The following describes the flow of fluid within the injector 1 according to this embodiment. The fluid that flows from the first flow path 30 to the third flow path 23 of the inlet section 3 flows into the accumulation chamber 42. The fluid in the accumulation chamber 42 applies pressure to the pressure receiving section 50 of the nozzle needle 5. The fluid that flows from the first flow path 30 to the second flow path 21 flows into the control pressure chamber 84 via the pressure introduction chamber 24 and the introduction side orifice passage 85. The fluid in the control pressure chamber 84 exerts downward pressure on the upper piston end 83 of the valve piston 81.

[0029] In this state, when no drive current is supplied to the electromagnet 90, the opening / closing orifice passage 86 is closed by the control valve body 98. In this case, the pressure of the fluid in the control pressure chamber 84 acts on the nozzle needle 5 via the valve piston 81, as well as the biasing force of the nozzle spring 6. As a result, the nozzle needle 5 seats on the seat portion 41 of the nozzle body 4, closing the injection hole 40.

[0030] On the other hand, when a drive current is supplied to the electromagnet 90, the armature plate 91 is attracted to the electromagnet 90, causing the armature bolt 92 to move upward. As the armature bolt 92 moves upward, the upward pressure of the fluid in the control pressure chamber 84 causes the control valve body 98 to open the opening / closing orifice passage 86. As a result, the fluid in the control pressure chamber 84 flows to the pressure control unit 9 through the opening / closing orifice passage 86. Then, the pressure acting on the upper end 83 of the piston in the control pressure chamber 84 decreases, and the nozzle needle 5 separates from the seat portion 41 against the biasing force of the nozzle spring 6 due to the pressure acting on the pressure receiving portion 50. Thus, the injection hole 40 is opened, and the fluid is injected to the outside of the injector 1.

[0031] When the current to the electromagnet 90 is cut off, the force from the electromagnet 90 no longer acts on the armature plate 91. The armature bolt 92 is then returned to the opening / closing orifice passage 86 by the spring 94, and the control valve body 98 closes the opening / closing orifice passage 86. When the opening / closing orifice passage 86 is closed, a downward pressure of fluid is again applied to the upper end 83 of the piston. This pressure on the upper end 83 is transmitted to the nozzle needle 5 via the valve piston 81, and together with the biasing force of the nozzle spring 6, acts to seat the nozzle needle 5 in the seat portion 41. As a result, the injection hole 40 is closed, and the injection of fluid stops.

[0032] Here, if the injector 1 is a fuel injection valve that injects fuel into the combustion chamber of an internal combustion engine as described above, the nozzle body 4 is positioned so that the lower end portion with the injection hole 40 faces the inside of the combustion chamber. If the combustion of fuel in the internal combustion engine is insufficient, the combustion chamber may become highly humid after the engine has finished operating, that is, the gaseous fuel in the combustion chamber may become dense. In addition, the fuel may contain components that cause corrosion of the nozzle body 4. When the nozzle body 4 is exposed to such an environment with high density of gaseous fuel, the parts of the nozzle body 4 that are subjected to stress are particularly prone to deterioration, which can result in damage to the nozzle body 4. The following describes in detail the stress concentration points in the nozzle body 4 that are particularly prone to deterioration.

[0033] Figure 2 is a diagram illustrating the forces acting on the nozzle body 4 in the embodiment. Figure 2 schematically shows a cross-section of the lower part of the injector 1, including the nozzle body 4. This cross-section is along the central axis of the injector 1 and passes through that central axis.

[0034] The nozzle body 4 includes two cylindrical first bodies 44 and second bodies 45. The term "cylindrical" includes shapes in which a cavity, such as a third flow path 23, is provided inside the wall of the cylinder. Furthermore, the term "cylindrical" also includes shapes in which the inner or outer diameter changes. The central axes of the first body 44 and the second body 45 are equal to the central axis of the injector 1. The first body 44 is located below and adjacent to the second body 45, and has an outer diameter smaller than the outer diameter of the second body 45. The inner diameter of the first body 44 is approximately the same as the inner diameter of the second body 45.

[0035] Since the outer diameter of the second body 45 is larger than the outer diameter of the first body 44, the outer circumferential surface of the second body 45 is located radially outward, that is, on the side that is further from the central axis, than the outer circumferential surface of the first body 44. The shoulder end face 46 of the lower end surface of the second body 45, which is not connected to the upper end surface of the first body 44, is in contact with the support surface 70 of the nozzle nut 7, which will be described later. As a result, the nozzle body 4 is supported from below by the nozzle nut 7 via the support surface 70. In the following, the portion of the lower end of the second body 45 that is located radially outward from the first body 44 and includes the shoulder end face 46 may be referred to as the shoulder portion 47.

[0036] The nozzle nut 7 includes two first nut portions 71 and a second nut portion 72. The central axes of the first nut portion 71 and the second nut portion 72 coincide with the central axis of the injector 1. The first nut portion 71 is located below and adjacent to the second nut portion 72, and has an inner diameter smaller than the inner diameter of the second nut portion 72. The outer diameter of the first nut portion 71 is approximately the same as the outer diameter of the second nut portion 72. The inner circumferential surface of the first nut portion 71 faces the outer circumferential surface of the first body 44, and the inner circumferential surface of the second nut portion 72 faces the outer circumferential surface of the second body 45.

[0037] Since the inner diameter of the first nut portion 71 is smaller than the inner diameter of the second nut portion 72, the inner circumferential surface of the first nut portion 71 is located radially inward, i.e., on the side with a smaller distance from the central axis, compared to the inner circumferential surface of the second nut portion 72. The support surface 70, which is the upper end surface of the first nut portion 71 that is not connected to the lower end surface of the second nut portion 72, is in contact with the shoulder end surface 46. The support surface 70 is in contact with the shoulder end surface 46 from below. In the following, the portion of the upper end of the first nut portion 71 that is located radially inward from the second nut portion 72 and includes the support surface 70 may be referred to as the support portion 73. An upward force acts on the shoulder portion 47 from the support portion 73. In the following, the upward force from the support portion 73 to the shoulder portion 47 may be referred to as the first force F1.

[0038] Here, since the housing 2 is screwed onto the nozzle nut 7, a downward force due to the torque T from the nozzle nut 7 acts on it. In the following, the downward force due to the torque T from the nozzle nut 7 acting on the housing 2 may be referred to as the second force F2.

[0039] Since the nozzle body 4 is fixed to the lower end of the housing 2 by the nozzle nut 7, a downward force acts on the nozzle body 4 from the housing 2, including the second force F2 described above. Hereafter, the downward force from the housing 2 acting on the nozzle body 4 may also be referred to as the third force F3.

[0040] An upward first force F1 acting from the support portion 73 to the shoulder portion 47 balances a downward third force F3 from above. Here, the third force F3 acts on the entire nozzle body 4 and is distributed throughout the entire nozzle body 4, while the first force F1 acts concentrated on the shoulder portion 47. As a result, a large tensile stress may be generated at the base of the shoulder portion 47. Here, the base of the shoulder portion 47 is the portion at the lower end of the second body 45 that includes the connection portion between the first body 44 and the shoulder portion 47. The base of the shoulder portion 47 may also include the radially outer portion of the upper end of the first body 44, that is, the portion close to the shoulder portion 47.

[0041] Figure 3 is a diagram illustrating the tensile stress σ generated at the base portion RT of the shoulder portion 47. In Figure 3, a schematic cross-section of a portion in the axial direction and a portion in the radial direction of the nozzle body 4 and nozzle nut 7 is shown. This cross-section is along the central axis of the injector 1 and passes through that central axis. In Figure 3, the base portion RT of the shoulder portion 47 is shown by a hatched area inside a dashed circle. As described above, a tensile stress σ is generated at the base portion RT of the shoulder portion 47 due to a first force F1 acting concentrated on the shoulder portion 47.

[0042] Here, as described above, if the injector 1 is a fuel injection valve that injects fuel into the combustion chamber of the internal combustion engine, the lower end portion of the nozzle body 4 is positioned facing the combustion chamber. If combustion in the combustion chamber is insufficient and gaseous fuel remains in the combustion chamber, this gaseous fuel can flow into the gap between the first nut portion 71 and the first body 44 through an opening provided in the internal combustion engine to position the lower end portion of the nozzle body 4 facing the combustion chamber. This gaseous fuel can then reach the base portion RT through the flow path FL shown in Figure 3. As a result, the base portion RT will be exposed to the corrosive gaseous fuel. In particular, if the combustion chamber is humid, that is, if the gaseous fuel in the combustion chamber is dense, the amount of gaseous fuel flowing to the base portion RT through the flow path FL will increase, and condensation may occur on the surface of the base portion RT. As a result, corrosion progresses in the base portion RT, and the tensile stress σ acting on the corroded base portion RT causes a crack CR to occur in the base portion RT, potentially damaging the injector 1.

[0043] To prevent such cracks (CR), conventional methods sometimes involved surface treatment such as short peening on the base portion (RT). However, short peening can lead to increased costs. The injector 1 of this embodiment aims to improve durability while keeping costs down.

[0044] The configuration of the injector 1 according to the embodiment will be described in more detail below, with the configuration of the conventional injector 1 as a comparative example. Figure 4 is a schematic diagram showing the shoulder portion 47 and support portion 73 in the comparative example. In Figure 4, a portion of the nozzle body 4 and nozzle nut 7 in the axial direction and a portion in the radial direction are shown in cross-section. This cross-section is a cross-section along the central axis of the injector 1 and passes through the central axis. In Figure 4, hatching of the area showing the cross-section of the nozzle body 4 is omitted for ease of understanding. As shown in Figure 4, in the comparative example, the outer portion of the shoulder end face 46 is located lower in the radial direction. That is, the shoulder end face 46 of the comparative example is inclined downward along the radial direction. On the other hand, in the comparative example, the outer portion of the support surface 70 is located higher in the radial direction. That is, the support surface 70 of the comparative example is inclined upward along the radial direction. As a result, the contact point CT between the shoulder end face 46 and the support surface 70 is closer to the first shoulder end 48 than to the second shoulder end 49. Furthermore, the contact point CT is closer to the first support end 74 than to the second support end 75. The first shoulder end 48 is the radially outer end of the shoulder end face 46, and the second shoulder end 49 is the radially inner end of the shoulder end face 46. The first support end 74 is the radially outer end of the support surface 70, and the second support end 75 is the radially inner end of the support surface 70. More specifically, there are multiple contact points CT between the shoulder end face 46 and the support surface 70, arranged continuously along the circumferential direction.

[0045] Figure 5 schematically shows the force acting on the base portion RT in the comparative example. Note that Figure 5 shows a portion of the axial cross-section of the nozzle body 4 and the first nut portion 71. This cross-section is along the central axis of the injector 1 and passes through that central axis. For ease of understanding, Figure 5 omits the second nut portion 72 and the hatching in the area showing the cross-section of the nozzle body 4.

[0046] As shown in Figure 5, a third downward force F3 acts on the nozzle body 4 from the housing 2. This third force F3 acts on the entire nozzle body 4. Meanwhile, a first force F1, equal in magnitude to the third force F3, acts on the shoulder portion 47. The downward third force F3 acting on the entire nozzle body 4 and the upward first force F1 acting on the shoulder portion 47 generate a bending moment M in the nozzle body 4. In addition, a tensile stress σ corresponding to this bending moment M is generated in the base portion RT. Note that the larger the bending moment M, the larger the tensile stress σ.

[0047] Here, the value of the bending moment M corresponds to the product of the value of the first force F1 and the distance R from the central axis of the point on which the first force F1 acts. The point on which the first force F1 acts is equal to the contact point CT. Therefore, the further the contact point CT is from the second shoulder end 49 and closer to the first shoulder end 48, the larger the bending moment M is. In the comparative example, as shown in Figure 5, the contact point CT is far from the second shoulder end 49 and close to the first shoulder end 48, so the bending moment M is large and the tensile stress σ is also large. As a result, in the comparative example, the load at the base portion RT is large and cracks CR are likely to occur. On the other hand, the configurations of the nozzle body 4 and nozzle nut 7 in the embodiment reduce the tensile stress σ and suppress the occurrence of cracks CR at the base portion RT. The configurations of the nozzle body 4 and nozzle nut 7 in the embodiment will be described below with reference to Figure 6.

[0048] Figure 6 is a schematic diagram showing the shoulder portion 47 and support portion 73 in the embodiment. In Figure 6, a portion of the nozzle body 4 and nozzle nut 7 in the axial direction and a portion in the radial direction is shown in cross-section. This cross-section is along the central axis of the injector 1 and passes through the central axis. In Figure 6, hatching of the area showing the cross-section of the nozzle body 4 is omitted for ease of understanding. As shown in Figure 6, in the embodiment, the outer portion of the shoulder end face 46 in the radial direction is located higher. That is, in the embodiment, the shoulder end face 46 is inclined upward along the radial direction. On the other hand, in the embodiment, the outer portion of the support surface 70 in the radial direction is located lower. That is, in the embodiment, the support surface 70 is inclined downward along the radial direction. As a result, the contact CT is closer to the second shoulder end 49 than to the first shoulder end 48. Also, the contact CT is closer to the second support end 75 than to the first support end 74.

[0049] Figure 7 is a schematic diagram illustrating the force acting on the base portion RT in the embodiment. Note that Figure 7 shows a portion of the axial cross-section of the nozzle body 4 and the first nut portion 71. This cross-section is along the central axis of the injector 1 and passes through that central axis. For ease of understanding, Figure 7 omits the second nut portion 72 and the hatching in the area showing the cross-section of the nozzle body 4.

[0050] As shown in Figure 7, a third downward force F3 from the housing 2 acts on the entire nozzle body 4, and a first force F1 equal in magnitude to the third force F3 acts on the shoulder portion 47. The third downward force F3 acting on the entire nozzle body 4 and the first upward force F1 acting on the shoulder portion 47 generate a bending moment M in the nozzle body 4, and a tensile stress σ corresponding to the bending moment M is generated in the base portion RT.

[0051] As described above, the value of the bending moment M corresponds to the product of the value of the first force F1 and the distance R of the contact point CT from the central axis. Furthermore, the tensile stress σ generated at the base portion RT is greater the larger the bending moment M is. In this embodiment, the contact point CT is closer to the second shoulder end 49 than to the first shoulder end 48, and closer to the second support end 75 than to the first support end 74, so the distance R is smaller than in the comparative example. Therefore, in this embodiment, the bending moment M is smaller and the tensile stress σ is smaller than in the comparative example. As a result, in this embodiment, it is possible to reduce the load at the base portion RT and suppress the occurrence of cracks CR. In addition, in this embodiment, costs can be reduced compared to when short peening treatment is performed as in the conventional method.

[0052] In Figure 6, an example is shown where the shoulder end face 46 is inclined upward along the radial direction and the support surface 70 is inclined downward along the radial direction. However, the inclinations of the shoulder end face 46 and the support surface 70 in this embodiment are not limited to this example. For example, the shoulder end face 46 may not be inclined, and the support surface 70 may be inclined downward along the radial direction. That is, the axial position of each point on the shoulder end face 46 in the radial direction may be constant, and the support surface 70 may be inclined downward along the radial direction. Alternatively, the shoulder end face 46 may be inclined downward along the radial direction, and the support surface 70 may be inclined downward along the radial direction. In this case, the inclination ratio of the support surface 70 is greater than the inclination ratio of the shoulder end face 46. That is, the degree of change in the axial position with respect to the change in the radial position on the support surface 70 is greater than the degree of change in the axial position with respect to the change in the radial position on the shoulder end face 46.

[0053] Furthermore, in this embodiment, the shoulder end face 46 may be inclined upward along the radial direction, and the support surface 70 may not be inclined. That is, the position in the axial direction of each point on the support surface 70 in the radial direction may be constant, and the shoulder end face 46 may be inclined upward along the radial direction. Alternatively, the shoulder end face 46 may be inclined upward along the radial direction, and the support surface 70 may be inclined upward along the radial direction. In this case, the inclination ratio of the shoulder end face 46 is greater than the inclination ratio of the support surface 70. That is, the degree of change in the axial position with respect to the change in the radial position on the shoulder end face 46 is greater than the degree of change in the axial position with respect to the change in the radial position on the support surface 70.

[0054] In the above embodiment, the case in which the contact CT is closer to the second shoulder end 49 than the first shoulder end 48 and closer to the second support end 75 than the first support end 74 was given as an example. However, the contact CT only needs to be located at at least one of the following positions: closer to the second shoulder end 49 than the first shoulder end 48, and closer to the second support end 75 than the first support end 74.

[0055] In the above embodiment, the support portion 73 of the first nut portion 71 is made of the same material as the other parts of the first nut portion 71 and is integrated with the other parts of the first nut portion 71. However, the support portion 73 may be made of a different material than the other parts of the first nut portion 71, or it may be a separate part from the other parts of the first nut portion 71. Hereinafter, with reference to Figure 8, an example in which the support portion 73 is a separate part from the other parts of the first nut portion 71 will be described in detail.

[0056] Figure 8 is a schematic diagram showing another configuration example of the first nut portion 71 in the embodiment. In Figure 8, a portion of the nozzle body 4 and nozzle nut 7 in the axial direction and a portion in the radial direction is shown in cross-section. This cross-section is along the central axis of the injector 1 and passes through the central axis. In Figure 8, hatching of the area showing the cross-section of the nozzle body 4 is omitted for ease of understanding. As shown in Figure 8, the first nut portion 71 has a support portion 73 as a separate part. The upper end surface of the support portion 73 is the support surface 70.

[0057] As shown in Figure 8, the shape of the first nut portion 71 without the support portion 73 corresponds to the shape of the first nut portion 71 in the comparative example shown in Figure 4. That is, when the support portion 73 is omitted, the portion of the upper end surface of the first nut portion 71 that is not connected to the lower end surface of the second nut portion 72 has a radially inward portion that is located lower. Hereinafter, the portion of the upper end surface of the first nut portion 71 that is not connected to the lower end surface of the second nut portion 72 when the support portion 73 is omitted may be referred to as the mounting surface 76. In the example shown in Figure 8, the support portion 73 is placed on the mounting surface 76. The support surface 70 of the support portion 73 placed on the mounting surface 76 has a radially inward portion that is located higher. As a result, by simply placing the support portion 73 on the mounting surface 76 of the conventional nozzle nut 7, the bending moment M and tensile stress σ mentioned above can be reduced, and the durability of the nozzle body 4 can be improved. Therefore, the durability of the nozzle body 4 can be improved by utilizing the existing nozzle nut 7 without discarding it, and by performing only minimal processing, such as placing the support part 73 on the mounting surface 76.

[0058] The following describes the effects of the injector 1 according to the embodiment. The injector 1 according to the embodiment injects a fluid to be injected. The injector 1 comprises a housing 2, a nozzle body 4, and a nozzle nut 7. The housing 2 constitutes the outer shell of the injector 1. The nozzle body 4 is located on the lower side of the housing 2, and an injection hole 40, which is an opening for injecting fluid from the internal space of the housing 2 to the outside, is formed at its lower end. The nozzle nut 7 fixes the nozzle body 4 to the lower end of the housing 2. The nozzle body 4 includes a first body 44 and a second body 45. The first body 44 is cylindrical. The second body 45 is located on the upper side of the first body 44, is cylindrical, and has an outer diameter larger than the outer diameter of the first body 44. The central axes of the first body 44 and the second body 45 are equal to the central axis of the injector 1. The upper end surface of the first body 44 and a part of the lower end surface of the second body 45 are connected. The nozzle nut 7 includes a first nut portion 71 and a second nut portion 72. The inner circumferential surface of the first nut portion 71 faces the outer circumferential surface of the first body 44. The second nut portion 72 is located above the first nut portion 71, has an inner diameter larger than the inner diameter of the first nut portion 71, and its inner circumferential surface faces the outer circumferential surface of the second body 45. The central axes of the first nut portion 71 and the second nut portion 72 are equal to the central axis of the injector 1. A portion of the upper end surface of the first nut portion 71 and the lower end surface of the second nut portion 72 are connected. The shoulder end surface 46 of the lower end surface of the second body 45, which is not connected to the upper end surface of the first body 44, is in contact with the support surface 70 of the upper end surface of the first nut portion 71, which is not connected to the lower end surface of the second nut portion 72. The contact point CT between the shoulder end face 46 and the support surface 70 is located at at least one of the following positions: closer to the second shoulder end 49 than the first shoulder end 48, and closer to the second support end 75 than the first support end 74. The first shoulder end 48 is the radially outer end of the shoulder end face 46, and the second shoulder end 49 is the radially inner end of the shoulder end face 46. The first support end 74 is the radially outer end of the support surface 70, and the second support end 75 is the radially inner end of the support surface 70.

[0059] According to the above configuration, the distance R between the contact point CT and the central axis is shortened, and the magnitude of the bending moment M generated in the nozzle body 4 due to the first force F1 acting from the support portion 73 to the shoulder portion 47 at the contact point CT can be reduced. As a result, the magnitude of the tensile stress σ acting on the base portion RT of the shoulder portion 47 can be reduced, and cracks CR in the base portion RT that may be generated by the tensile stress σ can be suppressed. Therefore, the durability of the nozzle body 4 can be improved while keeping costs down.

[0060] In this embodiment, the support surface 70 is inclined downward along the radial direction of the injector 1. As a result, by simply inclining the support surface 70, the distance R between it and the central axis of the contact point CT can be shortened, thereby reducing the bending moment M and tensile stress σ. Thus, the durability of the nozzle body 4 can be improved.

[0061] In this embodiment, the shoulder end face 46 is inclined upward along the radial direction of the injector 1. This allows the distance R between the shoulder end face 46 and the central axis of the contact point CT to be shortened by simply inclining the shoulder end face 46, thereby reducing the bending moment M and tensile stress σ. Thus, the durability of the nozzle body 4 can be improved.

[0062] In this embodiment, the first nut portion 71 includes a support portion 73 having a support surface 70. The support portion 73 is the upper end portion of the first nut portion 71 located radially inward from the second nut portion 72. Furthermore, the support portion 73 is separate from the other parts of the first nut portion 71. This makes it possible to improve the durability of the nozzle body 4 with minimal modification, by utilizing the existing nozzle nut 7 and adding the support portion 73 to the existing nozzle nut 7. [Explanation of Symbols]

[0063] 1 Injector, 2 Housing, 3 Inlet section, 4 Nozzle body, 5 Nozzle needle, 6 Nozzle spring, 7 Nozzle nut, 8 Valve, 9 Pressure control section, 20 First hole, 21 Second flow path, 22 Spring chamber, 23 Third flow path, 24 Pressure introduction chamber, 30 First flow path, 40 Injection hole, 41 Seat section, 42 Accumulation chamber, 43 Second hole, 44 First body, 45 Second body, 46 Shoulder end face, 47 Shoulder section, 48 First shoulder end, 49 Second shoulder end, 50 Pressure receiving section, 70 Support surface, 71 First nut section, 72 Second nut section, 73 Support section, 74 First support end, 75 Second support end, 76 Mounting surface, 80 Valve body, 81 Valve piston, 82 Piston chamber, 83 Upper end of piston, 84 Control pressure chamber, 85 Inlet side orifice passage, 86 90 Opening / closing orifice passage, 91 Electromagnet, 92 Armature plate, 92 Armature bolt, 92a Shaft section, 92b Head section, 93 Armature guide, 94 Spring, 95 Holder, 95a Recirculation passage, 96 Electromagnet housing, 97 Housing nut, 98 Control valve body, CR Crack, CT Contact, F1 First force, F2 Second force, F3 Third force, FL Flow path, M Bending moment, R Distance, RT Base section, T Torque, σ Tensile stress.

Claims

1. An injector (1) that injects the fluid to be injected, The outer shell consists of a housing (2) and A nozzle body (4) is located below the housing (2) and has an injection hole (40) formed at its lower end, which is an opening for injecting the fluid from the internal space of the housing (2) to the outside, A nozzle nut (7) that secures the nozzle body (4) to the lower end of the housing (2), Equipped with, The nozzle body (4) is A cylindrical first body (44), A second body (45) is located above the first body (44), is cylindrical, and has an outer diameter larger than the outer diameter of the first body (44), Includes, The central axis of the first body (44) and the central axis of the second body (45) are equal to the central axis of the injector (1), The upper end surface of the first body (44) and a part of the lower end surface of the second body (45) are connected. The nozzle nut (7) is The first nut portion (71) has an inner circumferential surface that faces the outer circumferential surface of the first body (44), A second nut portion (72) is located above the first nut portion (71), has an inner diameter larger than the inner diameter of the first nut portion (71), and its inner circumferential surface faces the outer circumferential surface of the second body (45), Includes, The central axis of the first nut portion (71) and the central axis of the second nut portion (72) are equal to the central axis of the injector (1), A portion of the upper end surface of the first nut portion (71) and the lower end surface of the second nut portion (72) are connected. The shoulder end face (46), which is the lower end surface of the second body (45) and is not connected to the upper end surface of the first body (44), is in contact with the support surface (70), which is the upper end surface of the first nut portion (71) and is not connected to the lower end surface of the second nut portion (72). The contact point (CT) between the shoulder end face (46) and the support surface (70) is It is located at at least one of the following positions: a position closer to the second shoulder end (49) than the first shoulder end (48), and a position closer to the second support end (75) than the first support end (74). The first shoulder end (48) is the radially outer end of the shoulder end face (46), The second shoulder end (49) is the radially inner end of the shoulder end face (46), The first support end (74) is the radially outer end of the support surface (70), The second support end (75) is the inner end in the radial direction of the support surface (70). Injector (1).

2. The injector (1) according to claim 1, wherein the support surface (70) is inclined downward along the radial direction.

3. The injector (1) according to claim 1 or 2, wherein the shoulder end face (46) is inclined upward along the radial direction.

4. The first nut portion (71) is The support portion (73) having the support surface (70) is provided, The support portion (73) is The injector (1) according to claim 1 or 2, wherein the upper end portion of the first nut portion (71) is located radially inward from the second nut portion (72) and is separate from the portion of the first nut portion (71) other than the support portion (73).

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