Flow control device

Abstract

A flow control device comprising a first component (140) and a second component (107) having an opposing surface facing a surface of the first component, comprising: an abutment surface (609) which establishes mutual contact between one surface of the first component and the opposite surface of the second component; and a welding region (403) formed along the abutting surface on the abutting surface of the first component and the second component, wherein an air gap is formed by the welding area, the first component and the second component, and a tip end portion of the welding portion (403) in the welding direction is located on a welding direction side with respect to the tip end portion of the abutting surface (609) in the welding direction, characterized in that an angle (508) formed by a tangent to a portion forming the air gap from the butt welding portion and a tangent to a surface forming the air gap with the butt welding portion of the first component is set to 45 degrees or more.

Description

Technical area

[0001] The present invention relates to a flow control device. State of the art

[0002] As an example of the prior art, it is disclosed in JP H11-193762 A that an electromagnetic fuel injection valve device is composed of a welded joint structure in which a movable valve is composed of an electromagnetic core and a movable needle portion each having a different material composition, wherein in the movable valve manufactured by welding and joining the electromagnetic core and the movable needle portion, an end surface of the electromagnetic core and the movable needle portion are butt-welded, a flange is formed on the movable needle portion and an abutting surface of the flange and the end surface of the electromagnetic core, and a molten portion is formed such that a welding depth is greater than a length of the abutting surface (see, for example, Fig. 2 of JP H11-193762 A).

[0003] By butt-joining at least a part of the movable needle portion and the electromagnetic core and applying a YAG laser light to the butt-joined portion to perform welding over a distance longer than the butt surface, it is possible to mass-produce and provide a fuel injection valve with excellent durability. List of reference literaturePatent literature

[0004] Document JP H11-193762 A discloses a flow control device according to the preamble of claim 1.

[0005] Further prior art is disclosed in documents JP 2006-29259 A, JP 2012-188977 A and JP 2007-218205 A. Brief description of the inventionTechnical problem

[0006] In the fuel injection valve of the embodiment described in Patent Literature 1, it is described that a weld penetration depth is made larger than the butt-welded portion's abutment length. However, there is no description of the invention regarding the shape and melting of the angle and corner portion of a butt-welded portion and the shape of a metal after resolidification.

[0007] Newer emissions regulations require the reduction of particulate matter in exhaust gases. Even with a gasoline fuel injector, it's possible that the maximum fuel pressure could rise to approximately 35 MPa. For example, if the normal maximum fuel pressure is 35 MPa, the fuel injector must withstand a fuel pressure of up to 55 MPa.

[0008] Then, due to the fuel pressure, greater stress is generated in the welding area than in the prior art, and there is a possibility that the strength margin will decrease.

[0009] An object of the present invention is to reduce the manufacturing cost of a fuel injection device that ensures the strength of a weld portion that can withstand a high fuel pressure, and to provide the fuel injection device at low cost. Solution to the problem

[0010] To achieve the above object, the present invention provides a flow control device having the features of claim 1, comprising a first component and a second component having an opposing surface facing a surface of the first component, comprising: an abutting surface that makes mutual contact between one surface of the first component and the opposing surface of the second component; and a welding portion formed along the abutting surface on the abutting surface of the first component and the second component, wherein an air gap is formed by the welding portion, the first component, and the second component, and a tip end portion of the welding portion in a welding direction is located on a welding direction side with respect to a tip end portion of the abutting surface in the welding direction. Advantageous effects of the invention

[0011] According to the present invention, it is possible to provide a low-cost fuel injection device by ensuring weld strength capable of withstanding high fuel pressure through the minimum amount of welding required. Problems, configurations, and effects other than those described above will become apparent from the description of the following embodiments. Short description of the drawings Fig. 1A is a cross-sectional view of a portion of a fuel injector and fuel rail according to an embodiment of the present invention. Fig. 1B is another cross-sectional view of a portion of a fuel injector and fuel rail according to an embodiment of the present invention. Fig. 2 is a graph showing a relationship between fuel pressure inside a fuel injection valve and a load applied in an axial direction of the injection valve. Fig. 3A is an overall cross-sectional view of the fuel injection device according to a comparative example. Fig. 3B is an enlarged cross-sectional view of a welding portion of the fuel injection device according to the comparative example. Fig. 4A is a cross-sectional view of a component of the fuel injector according to the embodiment of the present invention. Fig. 4B is an enlarged cross-sectional view of the welding portion of the fuel injection device according to the embodiment of the present invention. Fig. 4C is an enlarged cross-sectional view of the welding portion of the fuel injector according to the embodiment of the present invention. Fig. 4D is an enlarged cross-sectional view of the welding portion of the fuel injector according to the comparative example. Fig. 5A is an enlarged cross-sectional view of the welding portion of the fuel injection device according to the embodiment of the present invention. Fig. 5B is an enlarged cross-sectional view of the welding portion of the fuel injection device according to the embodiment of the present invention. Fig. 6A is an enlarged cross-sectional view of the welding portion of the fuel injection device according to the comparative example. Fig. 6B is an enlarged sectional view of the welding portion of the fuel injection device according to the comparative example. Description of embodiments

[0012] Hereinafter, a specific mode for carrying out the present invention will be described with reference to the drawings. Embodiment

[0013] Embodiments of a flow control device of the present invention, particularly their configuration and effects, will be described in detail below with reference to the drawings. In the present embodiment, a fuel injection valve (fuel injection device) is described as an example of a flow control device, but the present invention is not limited thereto. For example, the present invention is also applicable to two components joined together at the welded portion in a high-pressure fuel pump in which there is a possibility that the strength of the welded portion cannot be maintained due to large stress in the welded portion caused by high fuel pressure.In the drawings, the size of a component and the size of a gap may be exaggerated from actual proportions to make the function easy to understand, and unnecessary components may be omitted for the sake of clarity. In the respective embodiments, the same components are assigned the same reference numerals, and repetitive explanations are omitted.

[0014] First, the configuration of the fuel injection valve according to the present embodiment will be described with reference to Fig. 1A and Fig. 1B is described in broad terms. Fig. 1A and Fig. 1B are longitudinal sectional views of the fuel injection valve according to the present embodiment.

[0015] An internal combustion engine is provided with a fuel injection control device (not shown) which converts a suitable fuel quantity into an injection timing of the fuel injection valve according to an operating condition and controls the fuel injection valve which supplies the fuel.

[0016] As in Fig. 1A, in the fuel injection valve, for example, a movable portion 114 is configured to include a cylindrical movable element 102 and a needle valve 114A (valve body) disposed at the center of the mover 102. A gap is provided between an end surface of a fixed core 107 (stator), which has a fuel introduction port for supplying fuel to a central portion, and an end surface of the mover 102. An electromagnetic coil 105 (magnetic coil) is provided that supplies magnetic flux to a line of force path including the gap. In other words, the fixed core 107 (stator) is disposed opposite the mover 102, as shown in Fig. 1A.

[0017] The mover 102 is driven by attracting the mover 102 toward the fixed core 107 side by a magnetic attraction force generated between the end surface of the mover 102 and the end surface of the fixed core 107 by a magnetic flux through the gap, and the needle valve 114A is pulled away from a valve seat portion 39 (valve seat) to open a fuel passage provided in the valve seat portion 39. In other words, the mover 102 drives the needle valve 114A (valve body).

[0018] The amount of fuel to be injected is mainly determined by a pressure difference between the pressure of a fuel and the atmospheric pressure of an injection port of the fuel injection valve and a time during which the fuel is injected and the needle valve 114A is kept in an open state.

[0019] When the energization of the electromagnetic coil 105 is stopped, the magnetic attraction force acting on the mover 102 is released, the needle valve 114A and the mover 102 are moved in the closing direction by the force of an elastic member for urging the needle valve 114A in a closing direction and by a pressure drop caused by a flow velocity between the needle valve 114A and the fixed core 107, and the needle valve 114A is seated on the valve seat portion 39, thereby closing the fuel passage. The fuel is sealed by the seating between the needle valve 114A and the valve seat portion 39 to prevent fuel from accidentally leaking from the fuel injection valve.

[0020] In recent years, with a view to reducing fuel consumption, attempts have been made to reduce the amount of fuel consumed in a vehicle by reducing the displacement of an internal combustion engine in combination with a supercharger and using a high-thermal-efficiency operating range. Combining this with a direct-injection internal combustion engine is effective, as fuel vaporization improves intake air capacity and knock resistance.

[0021] Since a significant reduction in fuel consumption is required for a wide variety of vehicles, the demand for direct-injection internal combustion engines has increased. On the other hand, there is a need to install a device in a vehicle that is effective in reducing fuel consumption, for example, by recovering renewable energy. Furthermore, from the perspective of reducing overall costs, a reduction in the cost of various devices is required, and the need to reduce the cost of the fuel injector used for direct injection has also increased.

[0022] On the other hand, it is also necessary to further reduce the exhaust components contained in the exhaust gas of internal combustion engines, and particularly with a view to reducing the amount of particulate matter, an attempt has been made to increase the fuel injection pressure from the conventional 20 MPa to, for example, about 35 MPa in order to reduce the droplet size of an injected fuel and promote its evaporation.

[0023] As the fuel pressure increases, a load applied in the axial direction also increases relative to a fuel passage cross-sectional area of ​​a fuel line 211 and the fuel injection valve. Therefore, to obtain a fuel injection valve that can withstand high fuel pressure, it is necessary to reduce a diameter of the fuel passage at the connecting portion with the fuel line 211 to reduce the axial load.

[0024] As fuel pressure increases, the stress generated in a member that holds the internal fuel pressure against the exterior of the fuel injector also increases accordingly. To provide a strength margin against the stress generated at high fuel pressure, it is necessary to increase the thickness to ensure rigidity or to use a high-strength material.

[0025] However, as described above, in order to reduce the load applied in the axial direction, it is necessary to reduce the load in the axial direction by reducing the diameter of the fuel passage at a connecting portion with the fuel line 211, while simultaneously ensuring the inner diameter for accommodating the needle valve 114A, a spring 110, and an adjuster 54 inside the fuel injection valve. Therefore, it is difficult to increase the wall thickness. It is effective to use a material with high yield strength and tensile strength to maintain a strength margin even under high stress.

[0026] Since the fixed core 107 of the fuel injection valve is part of an electromagnetic solenoid, a material with excellent magnetic properties is used. This material with excellent magnetic properties has low yield strength and tensile strength, making it unsuitable for use as a connecting portion to the fuel line 211, which requires a small wall thickness and high rigidity as described above.

[0027] Therefore, to withstand high fuel pressure, the fuel injection valve is constructed in two parts, consisting of the fixed core 107 and the adapter 140. A material with higher yield strength and tensile strength than the fixed core 107 is used for the adapter 140, and a material with excellent magnetic properties is used for the fixed core 107. After the two parts are press-fitted in the radial direction, both parts can be fixed at 403a by full-circumference welding.

[0028] Therefore, in view of an increase in fuel pressure, it is possible to manufacture a fuel injection valve that does not deteriorate the magnetic properties of the fixed core 107 while reducing a fuel passage diameter with the fuel line 211 to reduce the load in the axial direction and suppress a cost increase at the same time.

[0029] For the same reason, the fixed core 107 and a nozzle holder 23 are divided into two components. A material with higher yield strength and tensile strength than the fixed core 107 is used for the nozzle holder 23, and a material with excellent magnetic properties is used for the fixed core 107. After the two parts are press-fitted in the radial direction, both parts can be secured at 403b by full-circumference welding.

[0030] In the upper part of Fig. Figure 1A schematically illustrates the load applied by fuel pressure in the axial direction of the fuel injection valve. Since the fuel injection valve is connected to the fuel line 211 and the fuel is sealed by the O-ring 212, the interior 213 of the fuel line and the interior of the fuel injection valve are filled with high-pressure fuel. A cross-sectional area of ​​the fuel line is determined by an inner diameter ϕR of the fuel line, and the product of the cross-sectional area of ​​the fuel line and a fuel pressure is defined as the fuel pressure load.

[0031] Since the fuel line 211 is attached to an internal combustion engine (not shown), the fuel injection valve receives a fuel pressure load in the direction of an arrow 214. Since the fuel injection valve is in contact with the internal combustion engine (not shown), for example, through a tapered surface 215 of a housing 103, the above-described fuel pressure load is transmitted via the adapter 140, the fixed core 107, an injection hole cup support 101, and a housing 103, which constitute the injection valve.

[0032] In the fuel injection valve, which is Fig. 1B, the fuel injector is suspended and positioned on the fuel line 211 via a plate 251.

[0033] Fig. Figure 2 is a graph plotting a calculated load in the axial direction of the injector versus a fuel pressure applied to the inside of the fuel injection valve. Conventionally, the maximum fuel pressure is 20 MPa, for example, and the load applied in the axial direction of the fuel injection valve is 1800 N. When the fuel pressure is set to 35 MPa, the fuel pressure load is increased by 1.5 times to 3200 N. Furthermore, in a system with a fuel pressure of 35 MPa, taking into account the safety margin, it is necessary to maintain structural strength up to a fuel pressure of 55 MPa, for example, and in this case, the axial load reaches approximately 7700 N.Since the axial load caused by fuel pressure is transmitted to the components of the fuel injector as described above, the stress generated in each component increases with increasing fuel pressure. If the shape, material, and welding method of the components that make up the fuel injector are not changed from conventional ones, the strength margin decreases. On the other hand, the use of high-strength materials and a complicated welding process results in increased costs.

[0034] In both cases, the two components in the fuel injector are secured by full-circumference welding after being press-fitted in the radial direction. Since the stress applied to the weld attachment gate increases with fuel pressure, it is necessary to provide a cost-effective fuel injector by ensuring weld strength capable of withstanding the high fuel pressure by keeping the weld to the minimum necessary. [Configuration details]

[0035] Next, the configuration of the fuel injection valve according to the embodiment of the present invention will be described with reference to Fig. 1A to 6B are described in detail.

[0036] First, referring to Fig. 1A describes the operation of the fuel injection valve.

[0037] The injection hole cup support 101 is provided with a small-diameter cylindrical portion 22 and a large-diameter cylindrical portion 23. An injection hole cup 116 (fuel injection hole forming member) having a guide portion 115 and a fuel injection hole 117 is inserted or press-fitted into the tip end portion of the small-diameter cylindrical portion 22, and the entire outer periphery of the tip end surface of the injection hole cup 116 is welded. This fixes the injection hole cup 116 to the small-diameter cylindrical portion 22. The guide portion 115 functions to guide the outer periphery when the valve body tip end portion 114B, provided at a tip end of the needle valve 114A constituting the movable portion 114, moves up and down in the axial direction of the fuel injection valve.

[0038] A conical valve seat portion 39 is formed in the injection hole cup 116 on the downstream side of the guide portion 115. The valve body tip end portion 114B, provided at the tip end of the needle valve 114A, abuts against or separates from the valve seat portion 39, thereby interrupting or permitting the flow of fuel to a fuel injection hole. A groove is formed on the outer periphery of the injection hole cup support 101, and a combustion gas sealing member, represented by a chip seal 131 made of a plastic material, is fitted into this groove.

[0039] On the inner circumference of the lower end portion of the fixed core 107, a needle valve guide portion 113 (guide member) is provided for guiding the needle valve 114A belonging to the mover. The needle valve 114A is provided with a guide portion 127, and although not shown, the guide portion 127 partially has a chamfered portion to form a fuel passage. The radial position of the elongated needle valve 114A is defined by the needle valve guide portion 113, and it is guided to reciprocate linearly in the axial direction. Note that a valve opening direction is upward in the axial direction of the valve, and a valve closing direction is downward in the axial direction of the valve.

[0040] A head 114C having a stepped portion 129 whose outer diameter is larger than the diameter of the needle valve 114A is provided at an end portion opposite to an end portion of the needle valve 114A where the valve body tip end portion 114B is provided. A seat surface of the spring 110 for urging the needle valve 114A in the valve closing direction is provided on an upper end surface of the stepped portion 129 and holds the spring 110 together with the head 114C.

[0041] The movable portion 114 includes the mover 102 having a through-hole 128 at its center through which the needle valve 114A passes. A zero spring 112, which urges the mover 102 in the valve-opening direction, is held between the mover 102 and the needle valve guide portion 113.

[0042] Since the diameter of the through hole 128 is smaller than the diameter of the stepped portion 129 of the head 114C, under the action of a force of the spring 110 pressing the needle valve 114A against the valve seat of the injection hole cups 116 or gravity, an upper side surface of the mover 102 held by the zero spring 112 abuts against a lower end surface of the stepped portion 129 of the needle valve 114A, so that the upper side surface and the lower end surface are engaged with each other.

[0043] As a result, both cooperate to move upward with the mover 102 against the force of the zero spring 112 or gravity, or to move downward with the needle valve 114A along the force of the zero spring 112 or gravity. Independent of the force of the zero spring 112 or gravity, the upper side surface and the lower end surface can move in different directions if a force for upward movement of the needle valve 114A and a force for downward movement of the mover 102 act independently on the upper side surface and the lower end surface.

[0044] A fixed core 107 is press-fitted into the inner circumference of the large-diameter cylindrical portion 23 of the injection-hole cup support 101 and welded and joined at a press-fit contact position. This welded joint hermetically seals a gap between the inside of the large-diameter cylindrical portion 23 of the injection-hole cup support 101 and the outside air. A through hole 107D with a diameter φCn is provided at the center of the fixed core 107 as a fuel introduction passage.

[0045] In other words, the bottom side (downstream side) of the adapter 140 (pipe) and the top side (upstream side) of the fixed core 107 are in direct contact with each other, whereby the adapter 140 and the fixed core 107 are fixed by press fitting.

[0046] Electroplating can be performed on a lower end surface of the fixed core 107 and an upper end surface and an impact end surface of the mover 102 to increase durability. Even if relatively soft magnetic stainless steel is used for the mover 102, durability and reliability can be ensured by hard chrome plating or electroless nickel plating.

[0047] A lower end of the bias spring 110 abuts against a spring receiving surface formed on the upper end surface of the stepped portion 129 on the head 114C of the needle valve 114A, and the other end of the spring 110 is received by the adjuster 54. Thus, the spring 110 is held between the head 114C and the adjuster 54. By adjusting the mounting position of the adjuster 54, it is possible to adjust a preload with which the spring 110 presses the needle valve 114A against the valve seat portion 39.

[0048] The cup-shaped housing 103 is fixed to the outer periphery of the large-diameter cylindrical portion 23 of the injection-hole cup support 101. The through-hole is provided at the center of the bottom of the housing 103, and the large-diameter cylindrical portion 23 of the injection-hole cup support 101 is inserted through the through-hole. An outer circumferential wall portion of the housing 103 forms an outer circumferential yoke portion, which opposes an outer circumferential surface of the large-diameter cylindrical portion 23 of the injection-hole cup support 101.

[0049] The annularly wound electromagnetic coil 105 is arranged in a cylindrical space formed by the housing 103. The electromagnetic coil 105 consists of an annular coil body 104 having a U-shaped groove with a radially outwardly open cross-section and a copper wire wound in the groove. A rigid conductor 109 is attached to a starting portion and an end portion of the winding of the electromagnetic coil 105 and is drawn out of a through hole in the fixed core 107.

[0050] The outer periphery of the conductor 109 and the large-diameter cylindrical portion 23 of the fixed core 107 and the injection hole cup holder 101 are molded by injecting insulating resin from the upper end opening of the casing 103 and covered by the resin molding 121. Thus, an annular magnetic path is formed around the electromagnetic coil (104, 105).

[0051] A connector for supplying power from a high-voltage power supply and a battery power supply is connected to the connector 43A formed at the tip end of the conductor 109, and the excitation and de-excitation are controlled by a controller (not shown). While the electromagnetic coil 105 is energized, a magnetic attraction force is generated in the magnetic attraction gap between the mover 102 of the movable portion 114 and the fixed core 107 by a magnetic flux passing through the magnetic circuit 140M, and the mover 102 moves upward by suction with a force exceeding the set load of the spring 110.

[0052] At this time, the mover 102 engages with the head 114C of the needle valve and moves upward together with the needle valve 114A until the upper end surface of the mover 102 collides with the lower end surface of the fixed core 107. As a result, the valve body tip end portion 114B of the tip end of the needle valve 114A separates from the valve seat portion 39, the fuel flows through the fuel passage, and is injected into the combustion chamber of the internal combustion engine from the fuel injection hole 117 provided at the tip end of the injection hole cup 116.

[0053] While the valve body tip end portion 114B at the tip end of the needle valve 114A is detached from the valve seat portion 39 and pulled upward, the elongated needle valve 114A is guided to rectilinearly return along the valve axis direction at two locations of the needle valve guide portion 113 and the guide portion 115 of the injection hole cup 116.

[0054] When the electromagnetic coil 105 is de-energized, the magnetic flux disappears, and the magnetic attraction force in the magnetic attraction gap also disappears. In this state, a spring force of the bias spring 110, which pushes the head 114C of the needle valve 114A in the opposite direction, overcomes a force of the neutral spring 112, so that the spring force of the bias spring 110 acts on the entire movable portion 114 (the mover 102 and the needle valve 114A). As a result, the mover 102 is pushed back by the spring force of the spring 110 to a valve-closing position in which the valve body tip end portion 114B is in contact with the valve seat portion 39.

[0055] While the valve body tip end portion 114B at the tip end of the needle valve 114A comes into contact with the valve seat portion 39 and is in the closed position, the elongated needle valve 114A is guided only by the needle valve guide portion 113 and is not in contact with the guide portion 115 of the injection hole cup 116.

[0056] At this time, the stepped portion 129 of the head 114C abuts the top of the mover 102 to overcome the force of the neutral spring 112 and move the mover 102 toward the needle valve guide portion 113 side. When the valve body tip end portion 114B collides with the valve seat portion 39, the movement toward the needle valve guide portion 113 continues due to inertia because the mover 102 is separated from the needle valve 114A. At this time, fluid friction occurs between an outer periphery of the needle valve 114A and an inner periphery of the mover 102, and the energy of the needle valve 114A rebounding from the valve seat portion 39 in the valve-opening direction is absorbed.

[0057] Since the mover 102, which has a large inertial mass, is separated from the needle valve 114A, the rebound energy itself is also reduced. Furthermore, the inertial force of the mover 102, which has absorbed the rebound energy of the needle valve 114A, decreases accordingly, and a repulsion force received after the compression of the neutral spring 112 also decreases. Therefore, a phenomenon in which the needle valve 114A moves back in the valve-opening direction due to the rebound of the movable member 102 hardly occurs. This minimizes the rebound of the needle valve 114A, and the valve is opened after the de-energization of the electromagnetic coil 105, thus suppressing a so-called secondary injection phenomenon in which fuel is injected randomly.

[0058] Fig. 3A shows a cross-sectional view of the fuel injection device according to a comparative example. After a fixed core 407 is press-fitted into the nozzle holder 23, the fixed core 407 is joined by lap welding.

[0059] Fig. 3B is an enlarged view of a neighborhood 460 of an overlap weld area of ​​the Fig. 3. Although the nozzle holder 23 receives a downward load 305 in an outer diameter direction and in the axial direction of the fuel injection valve due to the fuel pressure, the fixed core 407 is fixed in the axial direction; therefore, the nozzle holder 23 receives a downward load mainly acting on the lap weld portion 301 in the axial direction of the fuel injection valve due to the fuel pressure.

[0060] When 302 is an interface between the fixed core 407 and the nozzle holder 23 during lap welding, a shear stress is generated at the interface 302. Due to the shear stress, a high stress is generated at an upper end 303 of the interface 302. Even if the length of the interface 302 increases during lap welding, the stress is concentrated at the upper end 303 when a downward load in the axial direction of the fuel injection valve acts on the nozzle holder 23.

[0061] At a fuel pressure of 20 MPa, as in Fig. 2, the stress generated at the upper end 303 of the interface 302 is relatively small because the axial load is small, and sufficient strength can be ensured.

[0062] On the other hand, if the fuel pressure is higher than the conventional one, for example at a fuel pressure of 35 MPa, the axial load increases as in Fig. 2. Since the loading direction and the base metal boundary are parallel to each other in lap welding, the stress generated by the shear force in a base metal and weld boundary area also increases, and there is a possibility that sufficient strength cannot be ensured.

[0063] Fig. 4A is a cross-sectional view of only the adapter 140 and the fixed core 107 constituting the fuel injection valve according to the embodiment of the present invention. Since the thickness of an O-ring mounting portion 250 of the adapter 140 is small, a material with high strength is selected. Since the material is selected with strength in mind, the material can withstand a stress generated at a fuel pressure of 35 MPa. Since the fixed core 107 forms a magnetic circuit, there is no thin portion. Therefore, a magnetically excellent material is selected for the fixed core 107. Even if a material with low strength is selected, the material can withstand a stress generated at a fuel pressure of 35 MPa due to its large wall thickness.

[0064] In other words, a saturation magnetic flux density of the fixed core 107 (stator) is greater than a saturation magnetic flux density of the adapter 140 (lead), which consists of a member separate from the fixed core 107 and directly attached to the fixed core 107 by press fitting. This can, for example, reduce the manufacturing cost of the adapter 140 while ensuring the magnetic properties of the fixed core 107.

[0065] Here, a tensile strength of the fixed core 107 (stator) is smaller than a tensile strength of the adapter 140 (lead), which is directly connected to the fixed core 107 by press fitting. Even if the shape of the fixed core 107 is complicated, machining can be easily performed because the strength of the adapter 140 is ensured.

[0066] The butt joint section consists of a component A and a component B and must withstand a high pressure fuel with which the interior 601 of the fuel injector is filled.

[0067] A mounting portion 401 of the adapter 140 of the fuel injection valve and a mounting portion 402 of the fixed core 107 are in contact with each other in the radial direction, press-fitted, and subjected to full-circumference butt welding at a butt welding portion 403 to seal the fuel. Since the mounting portion 401 of the adapter 140 and the mounting portion 402 of the fixed core 107 are press-fitted before welding, it is possible to suppress tipping of the adapter 140 due to deformation occurring during welding.

[0068] In other words, the fixed core 107 (stator) has the fastening portion 402 (stator-side fastening portion) on the upstream side, and the adapter 140 (lead) has the fastening portion 401 (lead-side fastening portion) on the downstream side. The fastening portion 402 and the fastening portion 401 are in direct contact with each other and press-fitted in the radial direction. This makes it possible to easily manufacture the fastening portion 402 and the fastening portion 401, and press-fitting can be performed with the fastening portion 402 and the fastening portion 401.

[0069] Furthermore, a downstream tip end portion 401a of the fixing portion 401 (line-side fixing portion) comes into contact with an upper surface (upstream surface) of the fixing portion 402 (stator-side fixing portion), and butt welding is performed at this contact portion. That is, the fixing portion 401 (line-side fixing portion) is located farther on the outer peripheral side than the fixing portion 402 (stator-side fixing portion), the downstream tip end portion 401a of the fixing portion 401 comes into contact with the fixed core 107 in the axial direction, and butt welding is performed at this contact portion.

[0070] This makes it possible to perform butt welding of the fastening portion 402 and the fastening portion 401, as well as to manufacture and fix the fastening portion 402 and the fastening portion 401 at low cost. Since the strength of the material used for the adapter 140 is greater than that of the fixed core 107, it is appropriate to arrange the adapter 140 on the outer peripheral side, where stress is high. Furthermore, a high-strength material can be made thinner and is easy to weld.

[0071] Here, the fixed core 107 (stator) is provided with a protruding portion 107a (flange) that protrudes further toward the outer peripheral side on the downstream side than the fixing portion 402 (stator-side fixing portion), and the protruding portion 107a and the fixed core 107 are integrally formed. The fixed core 107 is formed by cold forging. This makes it possible to reduce material waste even when the protruding portion 107a is present and achieve low-cost manufacturing.

[0072] If a harder material that cannot be cold forged is selected for the fixed core 107, it is necessary to machine the fixed core 107, which includes the protruding portion 107a (flange). In this case, a large amount of material is wasted, which adversely affects costs. It is also conceivable to weld the protruding portion 107a separately, but this would result in positioning difficulties and an increase in production costs due to welding.

[0073] In addition, the projecting portion 107a (flange) forms a force path well between the projecting portion 107a and an end portion (upper end) of the housing 103 opposite the projecting portion 107a, whereby it is possible to connect the magnetic circuit 140M (see Fig. 1A) to be produced reliably.

[0074] As in Fig. 1B, when the fuel injector is connected to the fuel line 211 via a plate 251, the fixed core 107 is pulled toward the downstream side of the adapter 140 by the fuel pressure load due to the fuel pressure inside the fuel injector.

[0075] Fig. 4B shows an enlarged cross-sectional view of a butt weld area when the adapter 140 of the fuel injector and the stationary core 107 are subjected to butt weld welding. The shape of the metal melted and resolidified by welding is indicated by 403. A butt surface 609 of the adapter 140 and the stationary core 107 is perpendicular to a principal stress direction 510. Since the stress 510 is absorbed substantially uniformly by the butt surface 609, the maximum stress occurring is smaller than that in Fig. Overlap welding shown in Figure 3B.

[0076] That is, the fuel injection valve of this embodiment includes the attachment portion 401 (first component) of the adapter 140 and the attachment portion 402 (second component) of the fixed core 107, which has an opposing surface (upstream surface) facing one surface (downstream surface) of the first component. Furthermore, an abutting surface is obtained that establishes mutual contact between one surface (downstream surface) of the first component and the opposing surface (upstream surface) of the second component, and the butt welding portion 403 is formed along this abutting surface.In addition, an air gap is formed by the butt welding portion 403 and the first component and the second component, and a tip end of the butt welding portion 403 in the welding direction is shaped to be inclined relative to the tip end of the butt surface in the welding direction on a welding direction side (right direction in . Fig. 4B).

[0077] On the upper side of the air gap, a press-fit portion is formed, in which the fastening portion 401 (first component) of the adapter 140 and the fastening portion 402 (second component) of the fixed core 107 are press-fitted in the radial direction. That is, the fastening portion 401 (first component) of the adapter 140 and the fastening portion 402 (second component) of the fixed core 107 are fastened by the butt welding portion 403 described above in addition to this press-fit portion. Fig. According to the method shown in Figure 3B, there is a risk that the strength of the fastening will be insufficient due to the stress concentration in the welded area. By using the method of Fig. 4B, however, the strength of the fastening can be increased.

[0078] As a result, the butt weld area 403 is welded to a strength sufficient to withstand fuel pressure loading. With butt welding, the weld factor is higher than with lap welding, which is conventionally used for fuel injectors, and the strength is increased with the same penetration depth.

[0079] Fig. Figure 4C shows the shape of the melting and re-solidification of the butt joint section caused by welding in a more magnified manner. In the butt joint of two components, a gap 605 is formed by excavating a corner side of an element B, as shown in Fig. 4C, or a corner portion of a member A (not shown) is chamfered so that the butt surface 609 is in close contact. When welding the butt joint portion, laser welding is performed in a form as shown in 606 to completely fill the above gap 605 with molten metal. The reason why the gap 605 is filled with molten metal is that the stress increases depending on the shape of a gap portion when a load in the direction of the arrow in Fig. 4C is applied, and there is a possibility that the strength of the weld area will be reduced. That is, even in butt welding, the shape of the weld area that protrudes into a joint gap can cause stress concentration.

[0080] On the other hand, as in the butt welding areas 606, 607 and 608 of Fig. 4, opposite to the press-fitting portion in which the fastening portion 401 (first component) of the adapter 140 and the fastening portion 402 (second component) of the fixed core 107 are press-fitted, the butt welding portions 606, 607 and 608 are further positioned on a welding direction side (right direction in Fig. 4C). The weld areas 606, 607, and 608 are shaped so that all gaps formed between the first component 401 and the second component 402 are filled before welding. This can suppress stress increases due to the shape of the gap section and the risk of a decrease in the strength of the weld area.

[0081] A weld penetration depth 610 of the weld exhibits deviations from a target value in the production process. Even if welding is performed with the weld penetration shape 606 as the target value, a smaller weld penetration shape 611 is actually obtained, and there is a possibility that a gap remains after welding. To fill each gap 605 in Fig. 4C with the molten metal, a welding shape 607 is therefore desired which is such that the welding shape 606 corresponds even if a deviation occurs and the welding depth becomes smaller.

[0082] On the other hand, since coaxial precision is required for the fuel injection valve, there is a requirement to keep the heat input during welding as low as possible. Fig. 4C, even if a weld-in shape 607 is desired, taking the above deviation into account, it is conceivable that a weld-in shape 608 with a large penetration depth can be obtained. However, in a case where more than two-thirds of the thickness 612 of part B is melted, there is a possibility that the degree of deformation during welding will be large and the coaxial accuracy of the fuel injection valve will be impaired.

[0083] Fig. 4D shows a weld area shape when a weld penetration depth in butt welding is set to 614 to suppress coaxial deterioration. It is obvious that an end portion 615 of a weld area shape 615 causes stress concentration relative to a load direction 600 when the weld penetration depth is smaller than the butt surface length. Therefore, even in butt welding, there is a possibility that it may not be possible to ensure sufficiently high rigidity and strength against the load due to high fuel pressure if a weld penetration shape is made shorter than a butt welding length.

[0084] Fig. 5A illustrates a component forming a fuel boundary and its welding shape according to an embodiment of the fuel injection device of the present invention. A boundary between a high-pressure fuel and an atmosphere comprises two or more components A and B. The components are placed and press-fitted on the small-diameter outer diameter side of the component provided with the stepped portion and on the inner diameter side of the other component, brought into contact with the abutting surface, and positioned. A tip end portion in the welding direction in Fig. 4, which is component A, corresponds to the attachment portion 401 (first component) of the adapter 140. Component B corresponds to the attachment portion 402 (second component) of the fixed core 107. Butt welding is performed from a direction nearly parallel to an abutting surface between the first component A and the second component B to form a butt welding portion 509.

[0085] In the first component A, which is assembled or fitted on the inner diameter side, a chamfer 501 is provided in which the inner diameter-side corner portion of the abutting surface is long in a direction perpendicular to the abutting surface. The butt welding portion 509 is formed such that a weld joint length 503 is longer than a butt surface length 502 between the first component A and the second component B. That is, a tip end in the welding direction of the butt welding portion 509 is located on a welding direction side (right direction in Fig. 5A).

[0086] A weld penetration depth 505 of the butt welding portion 509 is set to a press-fit depth 504 or more. The press-fit depth refers to the length of the butt welding portion 509 in the press-fit direction. A weld penetration center 506 is located on the side of the component that is placed and press-fitted on the outer diameter side of a butt surface 507. That is, a central portion 506 in a direction orthogonal to the welding direction (right direction in Fig. 5A) of the butt welding area 509 (vertical direction in Fig. 5A) is further on the impact direction side (lower direction in Fig. 5A) as the abutment surface 507.

[0087] The butt weld portion 509 represents a shape that has melted and resolidified during welding. At a location where the melted and resolidified butt weld portion 509 intersects the first component A, that is, at an end portion of the weld joint length 503 of the portion of the butt weld portion 509 that is fixed to the first component A by welding, an angle formed by a tangent to a portion forming the air gap from the melted and resolidified butt weld portion 509 and a tangent to a surface 501 forming the air gap with the butt weld portion 509 of the first component A is set to 508. As described above, in this embodiment, the surface 501 forming an air gap with the butt weld portion 509 of the first component A is formed by chamfering.

[0088] Furthermore, the first component A and the second component B are fixed by press fitting on a side surface which is substantially orthogonal to an opposite surface (butting surface 507), and an air gap is formed on a press fitting side (lower direction in Fig. 5A) with respect to a press-fitting surface (press-fitting portion) which secures the second component B and the first component A. As shown in Fig. 5A, the chamfered portion 501 is formed at an end portion in the press-fitting direction of the first component A in a direction away from the press-fitting surface (press-fitting portion) to the press-fitting direction (downward in Fig. 5A). The chamfered portion 501 is also shaped such that a length in a press-fitting direction is longer than a length in a direction orthogonal to the press-fitting direction (horizontal direction in Fig. 5A). Furthermore, it is desirable that the air gap is shaped so that a length in the thrust direction (the lower direction in Fig. 5A) is longer than a length in a direction orthogonal to the direction of impact (horizontal direction in Fig. 5A).

[0089] Compared to the comparative example shown in Fig. As shown in Figure 4D, the angle 508 formed by the loading direction 510 with respect to the end portion of the weld portion shape is large, thereby reducing stress increase due to stress concentration, so that the strength of the weld portion can be maintained. The angle 508 is preferably close to 180 degrees, and when the angle 508 is 45 degrees or more, a desired fastening strength can be maintained in the fuel injector.

[0090] On Fig. Referring to FIG. 5B, the details of the chamfered portion 501 and the shape of the melted and resolidified butt weld portion 509 will be described. As described above, when the length of the weld joint 503 is the same, the stress concentration can be relaxed because the angle 508 formed by the butt weld portion 509 and the chamfered portion 501 is larger. An angle 513 between a top surface 512 of the butt weld portion 509 and the abutment surface 507 is selected so that the angle is at most parallel in view of laser welding characteristics. Therefore, in order to make the angle 508 between the top surface 512 of the butt weld portion 509 and the chamfer 501 as large as possible, it is preferable that an angle 511 formed by the chamfer 501 of the first component A is small.However, if the angle is too small, the interference fit distance between component A and component B cannot be ensured, so the angle is set to about 30 degrees (20 degrees ≤ angle 511 ≤ 40 degrees), for example.

[0091] As described above, in the fuel injection device of the present embodiment, a boundary between a high-pressure fuel and an atmosphere includes two or more components. The components are fitted and press-fitted on the small-diameter outer diameter side of the component provided with the stepped portion and on the inner diameter side of the other component, and are brought into contact and positioned with the abutting surface. Butt welding is performed from a direction almost parallel to the abutting surface. In addition, the first component A fitted and fitted on the inner diameter side has a chamfer 501 in which the inner-diameter-side corner portion of the abutting surface is long in a direction perpendicular to the abutting surface.Furthermore, the welding depth is greater than or equal to the thickness of the press-fitting portion of the first component A which is placed and press-fitted on the inner diameter side, and the center of the weld in the press-fitting direction is on the side of the second component B which is placed and press-fitted on the outer diameter side of the butt surface.

[0092] Referring to Fig. 6A and Fig. 6B, it is described by way of a counterexample that this embodiment can ensure strength capable of withstanding high fuel pressure in various cases. Fig. 6A shows a case where a welding center position for a target position to the side of the first component A in Fig. 6A. A small gap 702 remains in the butt weld portion 509, which is the molten metal resolidified after welding, and at the corner portion of the second component B. In this gap shape, since an angle 701 formed by the end portion of the weld portion shape to the direction of the axial load 600 caused by the fuel pressure is small, stress concentration occurs and the stress increases, thereby reducing the strength of the weld portion. As described above, it is necessary to dispose a weld center 506 on the side of the component that is placed and press-fitted on the outer diameter side of the butt surface 507.

[0093] Fig. 6B shows a case where the weld penetration depth 505 is smaller than the interference fit depth 504. In such a weld shape, there is a possibility that a part 704 of the metal 509, after melting and resolidifying, locally bulges and protrudes into a gap 705 between the first component A and the second component B. Since an angle 703 formed by the end portion of the weld portion shape to the direction of the axial load 600 caused by the fuel pressure is small, stress concentration occurs and the stress increases, thus reducing the strength of the weld portion. As described above, it is necessary to make the weld penetration depth 505 deeper than the interference fit depth 504.

[0094] Fig. 5 illustrates a case where a welding center position for a target position deviates toward the second component B side. Since the angle 508 formed by the end portion of the welding area shape to the loading direction 600 is large, a stress increase due to stress concentration is reduced, whereby the strength of the welding area can be kept to the necessary minimum.

[0095] Furthermore, the welding form of the Fig. 5, the present invention does not require a complicated shape of the first component A and the second component B, and therefore has the advantage of not increasing the manufacturing cost of the component. Furthermore, there is no need to change the position or angle of the welding center 506 during laser welding, and therefore has the advantage of not increasing the cost of the welding equipment. Since the position and angle of the welding center 506 are not changed during laser welding, the time required for welding is not increased, thereby suppressing an increase in the cost of the welding equipment.

[0096] The Fig.According to the embodiment of the present invention shown in Fig. 5, it is possible to realize a welding structure that minimizes the penetration depth of the butt welding portion and suppresses temporary stress concentrations under load, while reducing welding time and equipment costs.

[0097] It should be noted that the present invention is not limited to the embodiments described above, but includes various modifications. For example, the above embodiments may have been described in detail to facilitate understanding of the present invention, but are not necessarily limited to those having all the described configurations. In addition, a part of a configuration of a certain embodiment may be replaced with a configuration of another embodiment, and the configuration of another embodiment may be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations with respect to a part of the configuration of each embodiment. List of reference symbols 22 small diameter cylindrical section of the injection hole cup holder 23 large diameter tubular section of the injection hole cup holder 39 Valve seat section (seat section of the seat element) 43A connector 101 Injection hole cup holder 102 movers 103 housings 104 coil bodies 105 electromagnetic coil (magnetic coil) 107, 407 fixed core (stator) 107D Stator through hole (fuel channel) 109 ladders 110 spring 112 zero spring 113 Needle valve guide (shoulder) 114 movable section 114A Needle valve 114B Valve body tip end section 114C Needle valve head (spring guide projection) 115 Guide Section 116 injection hole cup 117 Fuel injection hole 121 resin molded bodies 126 Fuel channel 127 Guide Section 128 through hole 136 gap 140 adapters (cable) 201 guided part of the valve body tip end 202 Guide part of the injection hole cup 203 Valve element seat section at the valve body tip end 215 bevelled housing surface 251 plate 301 Overlap welding area 302 Interface in lap welding 303 upper end of the interface 302 304 lower end of the interface 302 305, 510 Load direction 401 Mounting section of the adapter 140 402 Fixing section of the fixed core 107 403 Butt welding area 501 chamfer 502 joint length 503 Welded joint length 504 Press fit depth 505 welding depth 506 Welding center 507 impact surface 508, 701, 703 angles 509 molten, resolidified metal (butt weld area) 601 Fuel Injector Interior 605, 702, 705 gap 606, 607, 608, 611, 613 welding form 609 Impact surface 610, 614 welding depth 612 Thickness of component B 615 End section with the shape of the welding area 704 Metal part after melting and resolidification

Claims

[1] A flow control device comprising a first component (140) and a second component (107) having an opposing surface facing a surface of the first component, comprising: an abutment surface (609) which establishes mutual contact between one surface of the first component and the opposite surface of the second component; and a welding region (403) formed along the abutting surface on the abutting surface of the first component and the second component, wherein an air gap is formed by the welding area, the first component and the second component, and a tip end portion of the welding area (403) in the welding direction is located on a welding direction side with respect to the tip end portion of the abutting surface (609) in the welding direction, characterized bythat an angle (508) formed by a tangent to a portion forming the air gap from the butt welding area and a tangent to a surface forming the air gap with the butt welding area of ​​the first component is set to 45 degrees or more. [2] The flow control device according to claim 1, wherein the tip end portion of the welding area in the welding direction is located on a welding direction side with respect to a tip end portion of the air gap in the welding direction. [3] The flow control device according to claim 1, wherein a central portion of the welding area is located on a butt direction side in a direction orthogonal to a welding direction with respect to the butt surface. [4] Flow control device according to claim 1, comprising a press-fit portion securing the first component and the second component on a side surface of the second component, the side surface being substantially orthogonal to the opposing surface with the first component, wherein the air gap is formed with respect to a press-fitting portion of the second component and the first component on a press-fitting direction side. [5] Flow control device according to claim 1, comprising a press-fit portion securing the first component and the second component on a side surface of the second component, the side surface being substantially orthogonal to the opposing surface with the first component, wherein a chamfered portion in a direction away from the press-fitting portion toward a press-fitting direction is formed at an end portion of the first component in a press-fitting direction. [6] Flow control device according to claim 1, comprising a press-fit portion securing the first component and the second component on a side surface of the second component, the side surface being substantially orthogonal to the opposing surface with the first component, wherein a chamfered portion in a direction away from the press-fitting portion to a press-fitting direction is formed at an end portion of the first component in a press-fitting direction, and the chamfered portion is shaped such that a length in a press-fitting direction is longer than a length in a direction orthogonal to the press-fitting direction. [7] The flow control device according to claim 1, wherein the air gap is shaped such that a length in a thrust direction is longer than a length in a direction orthogonal to the thrust direction. [8] Flow control device according to claim 1, comprising a press-fit portion securing the first component and the second component on a side surface of the second component, the side surface being substantially orthogonal to the opposing surface with the first component, wherein a chamfered portion formed in a direction away from the press-fitting portion toward a press-fitting direction is formed at an end portion in a press-fitting direction of the first component, and the chamfered portion is shaped such that a length in a press-fitting direction is longer than a length in a direction orthogonal to the press-fitting direction, and that the angle formed by the press-fitting portion and the chamfered portion is greater than or equal to 20 degrees and less than or equal to 40 degrees. [9] Flow control device according to claim 1, comprising a valve body that opens and closes a flow path, wherein the second element is a magnetic core that generates a magnetic attraction force, and the first element is a fastening element to which the magnetic core is fixed while being in abutment in a direction of movement of the valve body.

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