Electromagnetic fuel injection valve

Abstract

Provided is an electromagnetic fuel injection valve (1) that prevents biting of foreign matter between a fixed core (4) and a movable core (7), and has stable flow volume characteristics. An annular protruding part (23) protruding in the direction of the movable core (7) is formed on a suction operating surface (21) of the fixed core (4). A contact end surface (24) of the fixed core (4) that contacts the movable core (7) constitutes an upper end surface of the annular protruding part (23). Both sides radially of each recessed part (25) of the contact end surface (24) are open toward the radially outer side and inner side on the radially outer and inner side surfaces of the annular protruding part (23).

Description

Technical Field

[0005]

[0001] The present invention relates to an electromagnetic fuel injection valve in which a valve body cooperates with a valve seat in conjunction with a movable core facing a fixed core.

Background Art

[0002] Conventionally, there is known an electromagnetic fuel injection valve including a valve casing having a valve seat at one end, a hollow fixed core connected to the other end of the valve casing, a coil disposed on the outer periphery of the fixed core and capable of generating a magnetic attraction force on the fixed core, a movable core facing the end face of the fixed core, and a valve member having a valve body that cooperates with the valve seat in conjunction with the movable core (see, for example, Patent Document 1).

[0003] In the electromagnetic fuel injection valve of Patent Document 1, the movable core includes a stopper surface that abuts against the end face of the fixed core. The stopper surface is annularly disposed closer to the radially inner end of the attracted surface of the movable core with respect to the fixed core. A plurality of recesses are formed radially at intervals in the circumferential direction at a portion of the end face of the fixed core that abuts against the stopper surface of the movable core.

[0004] These plurality of recesses reduce the circumferential contact range between the end face of the fixed core and the stopper surface of the movable core, suppress an increase in the contact area due to wear of the contact portion, and suppress sticking between the end face and the stopper surface due to an increase in the contact area.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, according to the electromagnetic fuel injection valve of Patent Document 1, foreign matter contained in the fuel tends to accumulate at the portion of the end face of the fixed core that is in direct contact with the stopper surface of the movable core. As a result, this foreign matter may become trapped between the end face and the stopper surface, potentially causing the fuel flow characteristics to become unstable.

[0007] In view of the problems of the prior art, the object of the present invention is to provide an electromagnetic fuel injection valve that prevents foreign matter from getting stuck and has more stable flow characteristics. [Means for solving the problem]

[0008] The electromagnetic fuel injection valve of the present invention is A valve casing having a valve seat at its tip, A hollow fixed core connected to the rear end of the valve casing, A coil provided on the outer circumference of the fixed core, capable of generating a magnetic attractive force on the fixed core, The valve member comprises a movable core facing the fixed core, and a valve body that works in conjunction with the movable core and cooperates with the valve seat. The fixed core is provided with an suction surface facing the movable core, The movable core is an electromagnetic fuel injection valve having a surface to be attracted opposite to the suction surface, On either the suction surface or the surface being suctioned, there is a projection toward the movable core or the fixed core. and having a predetermined height h An annular projection is formed, The annular projection has a tapered or curved side surface on its outer circumference that rises in the direction from which the annular projection protrudes from the suction surface or the surface to be suctioned, and whose diameter decreases in that direction. Furthermore, the annular projection has multiple contact surfaces on the side in the direction in which the annular projection protrudes, and Having a predetermined depth d It has a contact end surface with multiple recesses arranged alternately in the circumferential direction, The radial sides of each recess of the aforementioned contact end face are open toward the radially outward and radially inward, respectively, on the tapered or curved side surface and the radially inward side surface of the annular projection. The other of the suction surface or the surface to be suctioned is provided with an annular stopper surface whose cross-section is a curved shape that curves convexly toward the contact end surface, and which contacts the contact surface of the corresponding end surface. The depth d of each recess is smaller than the height h of the annular projection. It is characterized by the following:

[0009] According to the present invention, when the fixed core and the movable core repeatedly come into contact, a flow of fuel is generated between them, but there is not much difference in flow velocity between the portion where the contact end face and the stopper surface are in direct contact and the portion of the contact end face that is recessed. The reason for this is that the contact end face constitutes the upper end face of the annular projection, and each recess is open radially outward and inward on the radially outward and inward sides of the annular projection, so the flow path through the recess is not narrowed by the stopper surface and the flow velocity does not increase.

[0010] Therefore, the flow passing through the recessed portion of the contact end face is prevented from circling around and creating vortices in the area where the contact end face and the stopper surface directly contact. This prevents the accumulation of foreign matter in the fuel in the area of ​​direct contact. Consequently, it is possible to prevent foreign matter from getting stuck between the fixed core and the movable core, and to provide an electromagnetic fuel injection valve with more stable flow characteristics.

[0011] In the present invention, the contact end face is positioned closer to the radially inner end of the suction surface or the surface to be suctioned, and the cross-section of the portion of the contact end face other than the recess may be composed of a curve that curves convexly toward the movable core or the fixed core. This further suppresses the accumulation and jamming of foreign matter and further stabilizes the flow characteristics.

[0012] The plurality of recesses may be arranged at equal intervals in the circumferential direction. This makes it possible to equalize the fuel flow between the fixed core and the movable core when they come into contact, throughout the entire circumferential region, and further improve the effect of suppressing the accumulation and jamming of foreign matter.

[0013] In the present invention, it is preferable that the depth of the recess is within the range of 20% to 60% of the height of the annular protrusion. Even in the case of 20%, which is the minimum value within this depth range, the effect of suppressing the accumulation and biting-in of foreign matter can be exhibited. Considering the manufacturing variation in the depth of the recess, it is optimal to set the depth of the recess to be within the range of 20% to 60% of the height of the annular protrusion.

Brief Description of the Drawings

[0014] [Figure 1] It is a cross-sectional view showing an electromagnetic fuel injection valve according to an embodiment of the present invention. [Figure 2] It is a perspective view showing the front end portion of the fixed core in the electromagnetic fuel injection valve of FIG. 1. [Figure 3] It is a plan view showing the suction action surface of the fixed core in the electromagnetic fuel injection valve of FIG. 1. [Figure 4] It is a cross-sectional view showing the state when the movable core abuts against the fixed core in the electromagnetic fuel injection valve of FIG. 1. [Figure 5] It is a cross-sectional view according to another example showing the state when the movable core abuts against the fixed core in the electromagnetic fuel injection valve of FIG. 1. [Figure 6A] It is a perspective view showing the front end portion of the fixed core in the electromagnetic fuel injection valve according to the conventional example. [Figure 6B] It is a cross-sectional view showing the fuel flow when the movable core abuts against the fixed core in the electromagnetic fuel injection valve according to the conventional example. [Figure 6C] It is an explanatory view showing the fuel flow when the movable core abuts against the fixed core in the electromagnetic fuel injection valve according to the conventional example. [Figure 7A] It is a cross-sectional view showing the fuel flow when the movable core abuts against the fixed core in the electromagnetic fuel injection valve of FIG. 1. [Figure 7B] It is an explanatory view showing the fuel flow when the movable core abuts against the fixed core in the electromagnetic fuel injection valve of FIG. 1.

Embodiments for Carrying Out the Invention

[0015] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows an electromagnetic fuel injection valve according to one embodiment of the present invention. As shown in Figure 1, this electromagnetic fuel injection valve 1 comprises a valve casing 3 having a valve seat 2 at its tip, a hollow fixed core 4 connected to the rear end of the valve casing 3, a coil 5 provided on the outer circumference of the fixed core 4 and capable of generating a magnetic attractive force on the fixed core 4, and a valve member 6 disposed inside the valve casing 3.

[0016] The valve member 6 has a movable core 7 facing the front end of the fixed core 4, and a valve body 8 that is interlocked with the movable core 7 and cooperates with the valve seat 2. A cylindrical valve seat member 9 is provided at the tip of the valve casing 3. The aforementioned valve seat 2 is provided at the tip of the valve seat member 9. A fuel inlet cylinder 10 is connected to the rear end of the fixed core 4.

[0017] The cylindrical body of the fuel filter 11 is fixed (for example, press-fitted) into the opening at the rear end of the fuel inlet cylinder 10. The front end of the fixing core 4 has a smaller diameter section, and the rear end of the non-magnetic cylindrical body 12 is liquid-tightly fitted into this smaller diameter section. The rear end surface of the magnetic cylindrical body 13 is liquid-tightly connected to the front end surface of the non-magnetic cylindrical body 12.

[0018] The movable core 7 is connected to the valve body 8 by a rod 14. The movable core 7 is slidably guided by the front end of the non-magnetic cylindrical body 12 and the rear end of the magnetic cylindrical body 13, and is driven in the front-rear direction together with the rod 14 and the valve body 8. A steel plate injector plate 16 having a valve hole 15 that is closed by the valve body 8 and a plurality of fuel injection holes communicating thereto is liquid-tightly welded to the valve seat member 9.

[0019] The valve casing 3 is composed of a valve seat member 9, a magnetic cylindrical body 13, and a non-magnetic cylindrical body 12. The valve casing 3 houses a valve member 6 consisting of a valve body 8, a rod 14, and a movable core 7. The valve housing 17 is composed of the valve casing 3, a fixed core 4, and a fuel inlet pipe 10.

[0020] The fixed core 4 has a vertical hole 18 that connects to the hollow portion of the fuel inlet cylinder 10 and extends to the front end face. The vertical hole 18 has a smaller diameter than the hollow portion of the fuel inlet cylinder 10 and communicates with a vertical hole inside the movable core 7. This vertical hole in the movable core 7 connects to the inside of the valve casing 3 on the outside of the rod portion 14 via an internal passage of the rod portion 14. Multiple flat surfaces are formed around the valve body 8 to allow the passage of fuel.

[0021] Within the valve housing 17, a fuel passage is formed that sequentially passes through the fuel inlet cylinder 10, the vertical hole 18 of the fixed core 4, the vertical hole of the movable core 7, the internal passage of the rod 14, the space between the valve casing 3 and the rod 14, the space between the valve seat member 9 and the rod 14, and the flat surface around the valve body 8.

[0022] A slotted pipe-shaped retainer 19 is press-fitted into the vertical hole 18 of the fixed core 4, and a valve spring 20 is compressed between the retainer 19 and the movable core 7 to bias the movable core 7 toward the closed side of the valve body 8. The set load of the valve spring 20 is adjusted by the fitting depth of the retainer 19 into the vertical hole 18.

[0023] Figure 2 shows the front end of the fixed core 4. As shown in Figure 2, the fixed core 4 has an suction surface 21 facing the rear end surface of the movable core 7. The suction surface 21 comprises an outer annular flat surface 22 and an annular projection 23 that protrudes toward the movable core 7, located radially inward from the surface.

[0024] The upper end surface of the annular projection 23 facing the movable core 7 is a contact end surface 24 that abuts against the movable core 7 when the valve is open. That is, the contact end surface 24 is positioned closer to the radially inner end of the suction surface 21. The contact end surface 24 is provided with a plurality of recesses 25 that are formed radially at intervals in the circumferential direction. The portion of the contact end surface 24 other than the recesses 25, i.e., the space between each adjacent recess 25, is a contact surface 26 that directly abuts against the movable core 7. The annular flat surface 22, the bottom surface of the recesses 25, and the contact surface 26 are all perpendicular to the central axis of the fixed core 4.

[0025] Figure 3 shows the suction surface 21 of the fixed core 4 as viewed in a direction parallel to the central axis of the fixed core 4. As shown in Figure 3, the recesses 25 on the contact end surface 24 of the annular projection 23 are evenly distributed in the circumferential direction. Both radial sides of each recess 25 are open toward the radially outer and inward sides of the radially outer and inner surfaces of the annular projection 23. Therefore, each recess 25 communicates the outer and inner sides of the annular projection 23.

[0026] Each contact surface 26 has the same shape and is symmetrical with respect to the plane containing the central axis of the fixed core 4. Therefore, the recesses 25 between each contact surface 26 also have the same and symmetrical shape. Each recess 25 has inner walls on both sides in the circumferential direction that are parallel to the plane of symmetry.

[0027] Figure 4 schematically shows the situation when the movable core 7 contacts the fixed core 4, in a cross-section including the central axis A. As shown in Figure 4, the cross-section of the contact surface 26, which is the part of the contact end face 24 other than the recess 25, is perpendicular to the central axis. As shown in Figure 5, the cross-section of the contact surface 26 may be composed of a curve 27 that curves convexly toward the movable core 7.

[0028] Furthermore, the depth d of the recess 25 is preferably within the range of 20-60% of the height h of the annular projection 23. Even at the minimum value of this depth range, 20%, the effect of suppressing the accumulation and jamming of foreign matter, as described later, can be achieved. Moreover, considering manufacturing variations in the depth of the recess 25, setting the depth of the recess 25 to 20-60% of the height of the annular projection 23 is optimal.

[0029] The movable core 7 comprises a suction surface 28 facing the suction surface 21 of the fixed core 4, and an annular stopper surface 29 provided on the suction surface 28 that contacts the contact surface 26 of the contact end surface 24 of the fixed core 4 when the valve is open. The cross-section of the stopper surface 29 is composed of a curve that is convex toward the fixed core 4.

[0030] In this configuration, when the coil 5 is not energized, the electromagnetic fuel injector 1 has its valve member 6 pressed toward the tip by the valve spring 20, and the valve body 8 at the tip of the valve member 6 is seated on the valve seat 2, resulting in a closed valve state. In this state, when fuel is pumped from a fuel pump (not shown) through the fuel distribution pipe to the fuel inlet cylinder 10, the fuel is filtered by the fuel filter 11, filling the inside of the fuel passage in the fuel inlet cylinder 10, the fixed core 4, and the valve casing 3, and further applying fluid pressure to the valve body 8.

[0031] In this state, when the coil 5 is energized by current flowing through the coupler 30, the resulting magnetic flux passes through the valve housing 17, the movable core 7, and the fixed core 4, generating a magnetic attractive force between the movable core 7 and the fixed core 4. As a result, the movable core 7 is attracted to the fixed core 4 against the set load of the valve spring 20, and the stopper surface 29 of the movable core 7 comes into contact with the contact end surface 24 of the fixed core 4.

[0032] In this way, when the movable core 7 comes into contact with the fixed core 4, the valve body 8 separates from the valve seat 2, and the electromagnetic fuel injection valve 1 opens. In response, the high-pressure fuel in the valve casing 3 is sprayed in a mist through the valve hole 15 and from the fuel nozzle of the injector plate 16 into the intake manifold of the internal combustion engine. When the power supply to the coil 5 is cut off, the valve body 8 at the tip of the valve member 6 returns to the closed state, seated on the valve seat 2.

[0033] Therefore, by controlling the energization of the coil 5, the electromagnetic fuel injector 1 can repeatedly switch between a closed and open state, thereby supplying appropriate fuel to the internal combustion engine to which the electromagnetic fuel injector 1 is installed.

[0034] During this time, as the fixed core 4 and the movable core 7 repeatedly come into contact, fuel flows in and out between the suction surface 21 of the fixed core 4 and the suctioned surface 28 of the movable core 7, creating a fuel flow. This fuel flow does not differ significantly from the conventional technology described in Patent Document 1, in that it passes through the contact surface 26 portion of the contact end surface 24 of the fixed core 4 that directly contacts the stopper surface 29 of the movable core 7, and through the recess 25.

[0035] This point is illustrated in Figures 6A-C and 7A,B. Figure 6A is a perspective view showing the end of the fixed core 4b in the conventional electromagnetic fuel injector described above. Figure 6B is a cross-sectional view showing the flow of fuel that passes through the recess 25b of the fixed core 4b, which occurs between the suction surface 21b of the fixed core 4b and the suctioned surface 28b of the movable core 7b when the fixed core 4b and the movable core 7b come into contact in this conventional electromagnetic fuel injector.

[0036] Figure 6C shows the results of a fluid analysis of the fuel flow at the suction surface 21b of the fixed core 4b at this time. Figures 7A and 7B in the figure are diagrams of this embodiment that correspond to Figures 6B and 6C of the conventional technology described above.

[0037] As shown in Figure 6A, in a conventional electromagnetic fuel injection valve, the contact end face 24b of the fixed core 4b is located on the inner side of the suction surface 21b, and the contact end face 24b has a plurality of contact surfaces 26b and recesses 25b provided between each adjacent contact surface 26b, similar to the present embodiment. However, unlike the present embodiment, the contact surfaces 26b are on the same plane as the outer side of the suction surface 21b. Therefore, the recesses 25b are recessed toward the fixed core 4b side of this same plane.

[0038] Therefore, in conventional electromagnetic fuel injectors, in the portion of the fuel flow generated between the suction surface 21b of the fixed core 4b and the suctioned surface 28b of the movable core 7b, the flow path is narrowed and deflected by the radially outer corner of the recess 25b and the stopper surface 29b, as shown by the arrow in Figure 6B, thus increasing the flow velocity.

[0039] As a result, when the fixed core 4b and the movable core 7b come into contact, and the fuel flows radially outward between the suction surface 21b and the surface to be suctioned 28b, as shown in Figure 6C, a high-speed portion of the flow that passes through the recess 25b of the fixed core 4b and a low-speed portion of the flow that is outside the contact surface 26b of the fixed core 4b are created, resulting in a large difference in flow velocity.

[0040] Therefore, as shown by the arrows in Figure 6C, the high-speed portion 31, where the flow is fast, passing through the recess 25b, wraps around to the slow-flowing portion 32 outside the contact surface 26b, creating a vortex. As a result, foreign matter in the fuel tends to accumulate in the slow-flowing portion 32.

[0041] In contrast, in this embodiment, when the stopper surface 29 of the movable core 7 contacts the contact end surface 24 of the fixed core 4, the fuel flow path passing between the recess 25 of the fixed core 4 and the stopper surface 29 of the movable core 7 is not constricted between the recess 25 and the stopper surface 29, as shown by the arrow in Figure 7A. Therefore, the flow velocity of the radially outward flow does not decrease significantly, and the fuel flows straight out of the recess 25.

[0042] As a result, as shown in Figure 7B, there is not much difference in flow velocity between the radially outer portion of the contact surface 26 and the portion passing through the recess 25. Therefore, the flow in the portion passing through the recess 25 does not wrap around to the radially outer portion of the contact surface 26 and create vortices, so the fuel flow as a whole is uniform and travels in a straight line radially, as indicated by the arrows in the figure. As a result, the accumulation of foreign matter in the fuel in the low-speed portion 32, as in the conventional technology, is suppressed.

[0043] As described above, according to this embodiment, an annular projection 23 is provided on the suction surface 21 of the fixed core 4, and the contact end surface 24 and recess 25 are formed on the annular projection 23. Since both radial sides of the recess 25 are open toward the radially outer and inward sides of the radially outer and inner sides of the annular projection 23, it is possible to suppress the accumulation of foreign matter in the fuel on the contact surface 26 of the contact end surface 24. This prevents foreign matter from getting stuck between the fixed core 4 and the movable core 7 and stabilizes the flow characteristics.

[0044] Furthermore, if the contact end surface 24 is positioned closer to the radially inner end of the suction surface 21, and the cross-section of the contact surface 26, which is the part other than the recess 25, is composed of a curve that is convex toward the movable core 7, then the accumulation and jamming of foreign matter can be further suppressed, and the flow characteristics can be further stabilized.

[0045] Furthermore, since the multiple recesses 25 are arranged at equal intervals in the circumferential direction, the fuel flow between the suction surface 21 of the fixed core 4 and the suction surface 28 of the movable core 7 can be made uniform throughout the entire circumferential region, further improving the effect of suppressing the accumulation and jamming of foreign matter.

[0046] Furthermore, if the depth d of the recess 25 is within the range of 20-60% of the height h of the annular projection 23, even at the minimum value of 20% within this depth range, it is possible to suppress the accumulation and jamming of foreign matter, and the depth of the recess 25 can be optimally set when considering manufacturing variations.

[0047] Although embodiments of the present invention have been described above, the present invention is not limited thereto. For example, the annular projection 23 on which the contact end surface 24 is provided may be provided on the suction surface 28 of the movable core 7, and the stopper surface 29 may be provided on the suction surface 21 of the fixed core 4. In this case as well, the contact end surface 24 and the stopper surface 29 can suppress the jamming of foreign objects. [Explanation of Symbols]

[0048] 1...Electromagnetic fuel injector, 2...Valve seat, 3...Valve casing, 4, 4b...Fixed core, 5...Coil, 6...Valve member, 7, 7b...Movable core, 8...Valve body, 9...Valve seat member, 10...Fuel inlet pipe, 11...Fuel filter, 12...Non-magnetic cylindrical body, 13...Magnetic cylindrical body, 14...Rod, 15...Valve hole, 16...Injector plate, 17...Valve housing, 18...Vertical hole, 19...Retainer, 20...Valve spring, 21, 21b...Suction surface, 22...Annular flat surface, 23...Annular projection, 24, 24b...Contact end surface, 25, 25b...Recess, 26, 26b...Contact surface, 27...Curve, 28, 28b...Surface to be attracted, 29, 29b...Stopper surface, 30...Coupler, 31...High-speed section, 32...Low-speed section.

Claims

1. A valve casing having a valve seat at its tip, A hollow fixed core connected to the rear end of the valve casing, A coil provided on the outer circumference of the fixed core, capable of generating a magnetic attractive force on the fixed core, The valve member comprises a movable core facing the fixed core, and a valve body that works in conjunction with the movable core and cooperates with the valve seat. The fixed core is provided with an suction surface facing the movable core, The movable core is an electromagnetic fuel injection valve having a surface to be attracted opposite to the suction surface, An annular projection is formed on either the suction surface or the surface to be suctioned, projecting toward the movable core or the fixed core and having a predetermined height from the suction surface or the surface to be suctioned. The annular projection has a tapered or curved side surface on its outer circumference that rises in the direction from which the annular projection protrudes from the suction surface or the surface to be suctioned, and whose diameter decreases in that direction. Furthermore, the annular projection has a contact end surface on the side in which the annular projection protrudes, in which a plurality of contact surfaces and a plurality of recesses having a predetermined depth are alternately arranged in the circumferential direction. The radial sides of each recess of the aforementioned contact end face are open toward the radially outward and radially inward, respectively, on the tapered or curved side surface and the radially inward side surface of the annular projection. The other of the suction surface or the surface to be suctioned is provided with an annular stopper surface whose cross-section is a curved shape that curves convexly toward the contact end surface, and which contacts the contact surface of the corresponding end surface. An electromagnetic fuel injection valve characterized in that the depth of each recess is smaller than the height of the annular projection.

2. The electromagnetic fuel injection valve according to claim 1, characterized in that the contact end surface is positioned towards the radially inner end of the suction surface or the surface to be suctioned, and the cross-section of the portion of the contact end surface other than the recess is composed of a curve that curves convexly toward the movable core or the fixed core.

3. The electromagnetic fuel injection valve according to claim 1, characterized in that the plurality of recesses are arranged at equal intervals in the circumferential direction.

4. The electromagnetic fuel injection valve according to claim 1, characterized in that the depth of the recess is within the range of 20 to 60% of the height of the annular projection.

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