Electromagnetic fuel injection valve

Abstract

In an electromagnetic fuel injection valve (I), when a fuel filter (20) and an orifice member (21) are pressed into the inner peripheral surface of a fuel inlet cylinder portion (7), interference of respective press-in interference amounts is prevented, and respective press-in is firmly fixed. A first press-in cylindrical surface (23) for press-in of the fuel filter (20) and a second press-in cylindrical surface (24) for press-in of the orifice member (21) are formed on the inner peripheral surface of the fuel inlet cylinder portion (7), the second press-in cylindrical surface (24) being connected to the outer end of the first press-in cylindrical surface (23) via a step portion (25) and having a larger diameter than the first press-in cylindrical surface (23).

Description

Technical Field

[0001] This invention relates to an electromagnetic fuel injection valve used in an engine fuel supply system, and particularly to an improvement of the electromagnetic fuel injection valve in which a fuel distribution cap branching from a fuel rail is fitted onto the outer periphery of the fuel inlet cylinder of the valve housing via a sealing member; furthermore, on the inner circumferential surface of the fuel inlet cylinder, a fuel filter and a throttling orifice member, which are axially adjacent to each other, are sequentially pressed into each other from the inlet side; an annular sealing groove for mounting the sealing member is provided on the outer circumferential surface of the fuel inlet cylinder; and the throttling orifice member has a throttling orifice communicating with its interior and exterior. Background Technology

[0002] Such electromagnetic fuel injection valves are known, as disclosed in Patent Document 1 below.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-285283 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The throttle orifice of the throttle orifice attenuates the fuel pressure pulsations in the fuel rail caused by the intermittent operation of the fuel pump and the intermittent fuel injection from multiple fuel injection valves during engine operation, and suppresses the changes in fuel injection quantity of the fuel injection valves caused by the pulsations. In addition, the fuel filter filters the fuel introduced into the fuel injection valves.

[0008] However, in the structure described in Patent Document 1, the inner circumferential surfaces of the fuel inlet cylinder, into which the fuel filter and the orifice component are pressed adjacently, are set to have the same diameter. In such a structure, the pressing interference of the fuel filter and the orifice component interferes with each other, making it difficult to maintain an appropriate pressing interference for each. For example, if the orifice component is pressed into the inner circumferential surface of the fuel inlet cylinder with a larger pressing interference after the fuel filter is pressed into it, the deformation of the inner circumferential surface of the fuel inlet cylinder as the orifice component is pressed into it will affect the pressing part of the fuel filter, reducing its pressing interference and creating a gap at the pressing part of the fuel filter, thus reducing the function of the fuel filter.

[0009] The present invention was made in view of the above circumstances, and its object is to provide an electromagnetic fuel injection valve that, when the fuel filter and the throttle orifice component are pressed into the inner circumferential surface of the fuel inlet cylinder, prevents interference of their respective press-in interference and ensures that their press-in is secure.

[0010] Methods for solving problems

[0011] To achieve the above objectives, a first feature of the present invention is an electromagnetic fuel injection valve in which a fuel distribution cap branching from a fuel rail pipe is fitted onto the outer periphery of the fuel inlet cylinder of the valve housing via a sealing member. Furthermore, on the inner circumferential surface of the fuel inlet cylinder, a fuel filter and a throttling orifice member, axially adjacent to each other, are sequentially pressed into each other from the inlet side. An annular sealing groove for mounting the sealing member is provided on the outer circumferential surface of the fuel inlet cylinder. The throttling orifice member has a throttling orifice communicating with its interior and exterior. The inner circumferential surface of the fuel inlet cylinder forms: a first pressing cylindrical surface for the fuel filter to be pressed into; and a second pressing cylindrical surface connected to the outer end of the first pressing cylindrical surface via a stepped portion, and having a diameter larger than that of the first pressing cylindrical surface, for the throttling orifice member to be pressed into.

[0012] In addition, the sealing component corresponds to the O-ring 13 in the embodiments described later.

[0013] Furthermore, a second feature of the present invention is that, based on the first feature, the throttling orifice component comprises: a circular orifice body portion having a wall thickness greater than the length of the throttling orifice and being pressed into the second pressing cylindrical surface; and a pressing guide portion protruding cylindrically from the outer periphery of one end face of the throttling orifice body portion, having an outer diameter smaller than the outer diameter of the throttling orifice body portion, and being fitted (including lightly pressed into) the second pressing cylindrical surface before the throttling orifice body portion, wherein the flange-shaped outer end wall of the sealing groove is integrally formed with the fuel inlet cylinder portion in a manner surrounding the throttling orifice body portion.

[0014] Furthermore, a third feature of the present invention is that, based on the second feature, the outer end wall has a wall thickness greater than that of the main body of the throttling orifice.

[0015] Furthermore, a fourth feature of the present invention is that, based on the third feature, the inner surface of the throttling orifice body and the inner circumferential surface of the press-in guide cylinder are connected via a curved surface.

[0016] Furthermore, a fifth feature of the present invention is that, based on any of the first to fourth features, the fuel filter and the throttle orifice component are respectively pressed into the first pressing cylindrical surface and the second pressing cylindrical surface in a state where their opposite end faces abut against each other.

[0017] Invention Effects

[0018] According to a first feature of the invention, even if the first and second press-in cylindrical surfaces deform due to the pressing of the fuel filter into the first press-in cylindrical surface and the pressing of the throttling orifice component into the second press-in cylindrical surface, these deformations are blocked by the step portion between the first and second press-in cylindrical surfaces and do not interfere with each other. Therefore, the fuel filter and the throttling orifice component can be reliably pressed into the inner circumferential surface of the fuel inlet cylinder with appropriate press-in interference fits.

[0019] According to a second feature of the invention, when pressing the throttling orifice component into the second pressing cylindrical surface, the smaller diameter pressing guide portion is first fitted into the second pressing cylindrical surface, and then the larger diameter throttling orifice body portion is pressed into the second pressing cylindrical surface. Therefore, the pressing posture of the throttling orifice body portion into the second pressing cylindrical surface can be maintained in a proper, non-tilting position. Furthermore, the wall thickness of the throttling orifice body portion is set to be greater than the length of the throttling orifice, thus ensuring the rigidity of the throttling orifice body portion and preventing deformation of the throttling orifice during the pressing process. In addition, the flange-shaped outer end wall of the sealing groove is integrally formed with the fuel inlet cylinder portion in a manner surrounding the throttling orifice body portion in its pressed-in state into the second pressing cylindrical surface. Therefore, the rigidity of the second pressing cylindrical surface can be improved by utilizing the outer end wall, thereby significantly increasing the pressing fixing force of the throttling orifice body portion and the second pressing cylindrical surface.

[0020] According to a third feature of the invention, the outer end wall of the sealing groove has a wall thickness greater than that of the throttling orifice body, and the outer end wall surrounds the throttling orifice body in the state of being pressed into the second pressing cylindrical surface. These features combined can prevent the deformation of the second pressing cylindrical surface caused by the pressing of the throttling orifice body from affecting the bottom of the sealing groove, and can ensure a good sealing state between the sealing component and the sealing groove.

[0021] According to a fourth feature of the present invention, the inner surface of the throttling orifice body and the inner circumferential surface of the pressed-in guide cylinder are connected by a concave curved surface, thereby improving the fatigue strength of the root of the throttling orifice body and maintaining the pulsation attenuation function for a long time.

[0022] According to the fifth feature of the present invention, even if burrs or other foreign objects are generated in the second pressing cylinder surface as the throttle orifice component is pressed into the second pressing cylinder surface, the foreign objects can be blocked by the contact portion between the fuel filter and the throttle orifice component, preventing the foreign objects from entering the fuel filter and avoiding clogging of the fuel filter. Attached Figure Description

[0023] Figure 1 This is a longitudinal sectional view of the electromagnetic fuel injection valve for internal combustion engines of the present invention, shown in its installed state on an engine.

[0024] Figure 2 yes Figure 1 An enlarged cross-sectional view of the portion indicated by arrow 2.

[0025] Figure 3 yes Figure 2 Exploded longitudinal section view of the fuel inlet cylinder and throttle orifice components. Detailed Implementation

[0026] For reference Figures 1 to 3 The embodiments of the present invention will be described.

[0027] First of all, Figure 1 In this multi-cylinder engine E, multiple fuel injection valves I (only one shown in the figure) capable of injecting fuel into the combustion chambers Ec of multiple cylinders are mounted on the cylinder head Eh, along with a fuel rail pipe 2 disposed above these fuel injection valves I. A fuel pump 3, which pressurizes and delivers fuel to the fuel rail pipe 2, is connected to one end of the fuel rail pipe 2. Furthermore, multiple fuel distribution caps 4 (only one shown in the figure) branch off from the fuel rail pipe 2.

[0028] Each fuel injection valve I has a cylindrical valve housing 5 extending along its axis. The front end of the valve housing 5 is a fuel nozzle cylinder 6, the rear end is a fuel inlet cylinder 7, and the middle part is an electromagnetic coil 8. A fuel distribution cover 4 is fitted around the outer periphery of the fuel inlet cylinder 7 via an O-ring 13. High-pressure fuel in the fuel rail tube 2 is supplied to the fuel inlet cylinder 7 through the fuel distribution cover 4.

[0029] The electromagnetic coil section 8 has a power supply coupler 9 protruding to one side. When the electromagnetic coil section 8 is energized through the power supply coupler 9, the valve inside the fuel nozzle cylinder section 6 opens, and the high-pressure fuel introduced from the fuel distribution cover 4 into the fuel inlet cylinder section 7 is injected into the combustion chamber Ec.

[0030] An annular sealing and buffering member 10 is installed on the outer periphery of the fuel nozzle cylinder 6, and the sealing and buffering member 10 is in close contact with the front end face of the electromagnetic coil section 8. In addition, an annular sealing groove 12 is formed on the outer peripheral surface of the fuel inlet cylinder 7 near its inlet, and the O-ring 13 and the support ring 14 supporting its front end face are installed in the sealing groove 12.

[0031] On the other hand, the cylinder head Eh is provided with an injection valve mounting hole 15 with its inner end opening to the top surface of each combustion chamber Ec, and an annular recess 16 surrounding its outer opening end. The fuel nozzle cylinder 6 of the fuel injection valve I is embedded in the injection valve mounting hole 15, and the sealing and buffering component 10 is housed in the recess 16.

[0032] On the outer peripheral surface of the fuel inlet cylinder 7, an annular groove 17 is provided adjacent to the electromagnetic coil section 8. The annular groove 17 faces the front end face of the fuel distribution cover 4. An elastic support member 18 is installed in the annular groove 17 to elastically press the front end face of the fuel distribution cover 4. As a result, the fuel injection valve I is elastically clamped between the cylinder head Eh and the fuel distribution cover 4.

[0033] exist Figure 2 In this configuration, on the inner circumferential surface of the fuel inlet cylinder 7, the fuel filter 20 and the throttle orifice component 21 are sequentially fixed by pressing inwards from the inlet. Thus, the fuel filter 20 and the throttle orifice component 21 are arranged adjacent to each other in the axial direction.

[0034] Next, refer to Figure 2 and Figure 3 The structure in which the fuel filter 20 and the throttle orifice component 21 are pressed into the inner circumferential surface of the fuel inlet cylinder 7 will be described.

[0035] A first pressing cylindrical surface 23 and a second pressing cylindrical surface 24 are formed on the inner circumferential surface of the fuel inlet cylinder 7. The second pressing cylindrical surface 24 is coaxially connected to the outer end of the first pressing cylindrical surface 23 via a step portion 25 and has a larger diameter than the first pressing cylindrical surface 23. The second pressing cylindrical surface 24 opens at the rear end face of the fuel inlet cylinder 7, i.e., the inlet end face, via a chamfer 28.

[0036] On the other hand, the fuel filter 20 is composed of a slender filter cage 20a and a metal mounting ring 20b connected to the open end of the filter cage 20a. The filter cage 20a can filter the fuel introduced into the fuel inlet cylinder 7.

[0037] The throttling orifice component 21 comprises the following components: a circular orifice body 21a, which has a throttling orifice 26 through its center, connecting its interior and exterior; and a press-in guide tube 21b, which protrudes cylindrically from the outer periphery of one end face of the throttling orifice body 21a. The outer diameter D2 of the press-in guide tube 21b is set to be slightly smaller than the outer diameter D1 of the throttling orifice body 21a (e.g., 0.1 mm smaller), and their outer peripheral surfaces are connected via a tapered step 22. Furthermore, a chamfer 29 is applied to the outer periphery of the front end of the press-in guide tube 21b. Further, the inner surface of the throttling orifice body 21a and the inner peripheral surface of the press-in guide tube 21b are continuously connected via a concave curved surface 30.

[0038] The main body 21a of the throttling orifice is configured such that its wall thickness S2 is greater than the axial length S1 of the throttling orifice 26. For this reason, a pair of tapered holes 27 are connected to both ends of the throttling orifice 26, and the major diameter of the pair of tapered holes 27 are respectively opened on the two end faces of the main body 21a of the throttling orifice.

[0039] Furthermore, when assembling the fuel filter 20 and the orifice component 21 into the fuel inlet cylinder 7, firstly, the filter cage 20a of the fuel filter 20 is inserted into the fuel inlet cylinder 7, and its mounting ring 20b is positioned at the inlet of the first press-in cylindrical surface 23. Next, while pressing the orifice component 21 into the second press-in cylindrical surface 24, the mounting ring 20b is pressed into the first press-in cylindrical surface 23 with a predetermined press-in interference fit while the opposite end faces of the orifice component 21 and the fuel filter 20 are in contact.

[0040] Furthermore, when pressing the throttling orifice component 21 into the second press-in cylindrical surface 24, firstly, the press-in guide cylinder portion 21b is fitted into or lightly pressed into the second press-in cylindrical surface 24 to ensure the coaxiality of the second press-in cylindrical surface 24 and the throttling orifice component 21. Next, the throttling orifice body portion 21a is pressed into the second press-in cylindrical surface 24 with a predetermined press-in interference amount larger than that of the mounting ring 20b.

[0041] Therefore, the main body 21a of the throttling orifice can be properly pressed into the second pressing cylindrical surface 24 with a predetermined pressing interference without tilting. At this time, the pressing guide cylinder 21b is not allowed to abut against the step portion 25, so as to prevent the pressing load of the throttling orifice component 21 from being applied to the step portion 25 between the first pressing cylindrical surface 23 and the second pressing cylindrical surface 24.

[0042] Furthermore, the step portion 25 exists between the first press-in cylindrical surface 23 and the second press-in cylindrical surface 24, which has a larger diameter. Therefore, the deformation occurring on the first press-in cylindrical surface 23 and the second press-in cylindrical surface 24 due to the pressing of the mounting ring 20b and the throttle orifice component 21 is blocked by the step portion 25 and does not interfere with each other. Thus, the predetermined press-in interference of the mounting ring 20b relative to the first press-in cylindrical surface 23 and the predetermined press-in interference of the throttle orifice body portion 21a relative to the second press-in cylindrical surface 24 can be appropriately maintained without interference. In particular, even if a large deformation occurs on the second press-in cylindrical surface 24 as the throttle orifice body portion 21a is pressed into the second press-in cylindrical surface 24 with a large press-in interference, the press-in interference of the mounting ring 20b, which was previously pressed into the first press-in cylindrical surface 23, will not be affected, and the fuel filter 20 can be reliably and continuously fixed to the inner circumferential surface of the fuel inlet cylinder portion 7.

[0043] Furthermore, the flange-shaped outer end wall 12a of the sealing groove 12 is integrally formed with the fuel inlet cylinder 7, facing the rear end face of the fuel inlet cylinder 7, and is arranged to occupy a position concentric with the throttling orifice main body 21a when it is pressed into the second pressing cylindrical surface 24, i.e., to surround the throttling orifice main body 21a. The wall thickness S3 of the outer end wall 12a is set to be thicker than the wall thickness S2 of the throttling orifice main body 21a. Therefore, the rigidity of the portion of the second pressing cylindrical surface 24 into which the throttling orifice main body 21a is pressed can be effectively strengthened using the outer end wall 12a. Thus, the throttling orifice main body 21a can be reliably pressed into the second pressing cylindrical surface 24 with a predetermined pressing interference.

[0044] Furthermore, the outer end wall 12a is arranged around the throttling orifice body 21a in the state of being pressed into the second pressing cylindrical surface 24, and the wall thickness S3 of the outer end wall 12a is set to be thicker than the wall thickness S2 of the throttling orifice body 21a. This means that the throttling orifice body 21a is axially offset from the bottom of the sealing groove 12. Therefore, the deformation of the second pressing cylindrical surface 24 caused by the pressing of the throttling orifice body 21a will not affect the sealing groove 12, thus maintaining a good seal between the sealing groove 12 and the O-ring 13.

[0045] Furthermore, the fuel filter 20 and the throttle orifice component 21 are pressed into the first pressing cylindrical surface 23 and the second pressing cylindrical surface 24 respectively with their opposite end faces abutting. Thus, even if burrs or other foreign objects are generated in the second pressing cylindrical surface 24 as the throttle orifice component 21 is pressed into it, the abutting portion between the fuel filter 20 and the throttle orifice component 21 can block the foreign objects, preventing them from entering the fuel filter 20 and avoiding clogging of the filter cage 20a.

[0046] During the operation of engine E, when the pulsation of fuel pressure generated in fuel rail pipe 2 propagates to fuel inlet cylinder 7, the pulsation is attenuated by the throttling effect of throttling orifice 26 of throttling orifice component 21, which can prevent the amount of fuel injected from fuel nozzle cylinder 6 to combustion chamber Ec from changing due to the pulsation.

[0047] In addition, the throttling orifice body 21a with the above-mentioned throttling orifice 26 in the center has a wall thickness S2 that is larger than the axial length S1 of the throttling orifice 26 and has high rigidity. Therefore, even if the throttling orifice body 21a is pressed into the second pressing cylindrical surface 24, the throttling orifice 26 will not deform, and its pulsation attenuation function can be stabilized.

[0048] Furthermore, when the orifice 26 performs its pulsation attenuation function, the pulsating high-pressure wave and low-pressure wave alternately act on the orifice body 21a, causing it to alternately and repeatedly bear pressing load and pulling load. As a result, there is a tendency for stress concentration to occur at the connection between the orifice body 21a and the press-in guide cylinder 21b when it is fixed to the fuel inlet cylinder 7. However, the inner surface of the orifice body 21a and the inner circumferential surface of the press-in guide cylinder 21b are continuously connected via the concave curved surface 30. Therefore, the concentrated stress is dispersed at a portion of the concave curved surface 30, which can improve the durability of the orifice component 21.

[0049] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention as described in the claims.

[0050] Symbol Explanation

[0051] I: Electromagnetic fuel injection valve;

[0052] D1: Outer diameter of the main body of the throttling orifice;

[0053] D2: Outer diameter of the pressed-in guide tube section;

[0054] S1: Length of the throttling orifice;

[0055] S2: Wall thickness of the main body of the throttling orifice;

[0056] S3: Wall thickness of the outer end wall of the sealing groove;

[0057] 2: Fuel rail pipe;

[0058] 3: Fuel pump;

[0059] 4: Fuel dispenser cover;

[0060] 5: Valve housing;

[0061] 6: Fuel nozzle cylinder section;

[0062] 7: Fuel inlet cylinder;

[0063] 12: Sealing groove;

[0064] 13: Sealing components (O-rings);

[0065] 20: Fuel filter;

[0066] 21: Throttling orifice component;

[0067] 21a: The main body of the throttling orifice;

[0068] 21b: Press-in guide tube section;

[0069] 23: First pressing into the cylindrical surface;

[0070] 24: Second pressing into the cylindrical surface;

[0071] 25: Step section;

[0072] 26: Throttling orifice;

[0073] 30: Concave surface.

Claims

1. An electromagnetic fuel injection valve, A fuel distribution cap (4) branching from the fuel rail pipe (2) is fitted onto the outer periphery of the fuel inlet cylinder (7) of the valve housing (5) via a sealing member (13). Furthermore, on the inner circumferential surface of the fuel inlet cylinder (7), a fuel filter (20) and a throttling orifice member (21) adjacent to each other in the axial direction are sequentially pressed in from its inlet side. An annular sealing groove (12) for mounting the sealing member (13) is provided on the outer circumferential surface of the fuel inlet cylinder (7). The throttling orifice member (21) has a throttling orifice (26) communicating with its interior and exterior. The characteristic feature is that… The inner circumferential surface of the fuel inlet cylinder (7) is formed with: a first press-in cylindrical surface (23) for the fuel filter (20) to be pressed in; and a second press-in cylindrical surface (24) connected to the outer end of the first press-in cylindrical surface (23) via a step portion (25), and having a larger diameter than the first press-in cylindrical surface (23) for the throttling orifice component (21) to be pressed in. The throttling orifice component (21) is composed of the following components: a circular plate-shaped throttling orifice body (21a) having a wall thickness greater than the length (S1) of the throttling orifice (26) and being pressed into the second pressing cylindrical surface (24); and a pressing guide cylinder (21b) protruding cylindrically from the outer periphery of one end face of the throttling orifice body (21a), having an outer diameter (D2) smaller than the outer diameter (D1) of the throttling orifice body (21a), and fitting into the second pressing cylindrical surface (24) before the throttling orifice body (21a), wherein the flange-shaped outer end wall (12a) of the sealing groove (12) is integrally formed with the fuel inlet cylinder (7) in a manner surrounding the throttling orifice body (21a).

2. The electromagnetic fuel injection valve according to claim 1, characterized in that, The outer end wall (12a) has a wall thickness (S3) that is greater than the wall thickness (S2) of the throttling orifice body (21a).

3. The electromagnetic fuel injection valve according to claim 1, characterized in that, The inner side of the throttle orifice body (21a) is connected to the inner circumferential surface of the press-in guide tube (21b) via a concave curved surface (30).

4. The electromagnetic fuel injection valve according to claim 1, characterized in that, The fuel filter (20) and the throttling orifice component (21) are pressed into the first pressing cylindrical surface (23) and the second pressing cylindrical surface (24) respectively, with their opposite end faces abutting.

Images