Patent Application
20060086830
This application is based upon and claims the benefit of priority of Japanese Patent Applications No. 2004-310931 filed on Oct. 26, 2004 and No. 2005-275268 filed on Sep. 22, 2005, the contents of which are incorporated herein by reference.
The present invention relates to a fluid injection valve suitable for injecting fuel into cylinders of an internal combustion engine (hereinafter referred to just as “engine”).
In fuel injection valves for engines, it is important to atomize the fuel injection spray sufficiently from viewpoints of toxic substance reduction in emission gas, fuel consumption performance improvement and so on. U.S. Pat. No. 6,405,946-B1, U.S. Pat. No. 6,616,072-B2, US-2004-0124279-A1 and their counterpart JP-2001-46919-A disclose fluid injection nozzles for promoting an atomization of the fuel injection spray.
In the fluid injection nozzles disclosed in the above publications, a flat disc-shaped fuel chamber is formed between a valve seat and injection ports. By the fuel chamber provided between the valve seat and the injection ports, fuel, which has flown on an inner circumferential surface of the valve body, passes through an opening portion of the valve body, then forms a spread flow in the fuel chamber. Thus, at the outflow side of the injection ports, it is possible to decrease collisions among fuel spray columns that are injected out of the injection ports.
However, by forming the fuel chamber between the valve seat and the injection ports, a dead volume in the fluid injection nozzle increases. When the dead volume is large, a relatively large amount of fuel is left in the fuel chamber without being injected out of the injection ports. For example, in a case that a fuel injection valve is installed in an intake pipe of an engine, the fuel left in the fuel chamber is sucked by intake air that flows through the intake pipe at a large speed. Thus, a fuel ratio in the intake air increases, and it becomes difficult to control the fuel injection amount with high accuracy.
The present invention, in view of the above-described issue, has an object to provide a fluid injection valve that can promote an atomization of fluid injection spray and decrease a volume of its fluid chamber.
The fluid injection valve has: a valve body that is provided with an opening portion at one axial end thereof and is for starting and stopping a supply of a fluid out of the opening portion; and an injection port plate having a plurality of injection ports that penetrate therethrough, the injection port plate being fixed on the one axial end of the valve body to form a fluid chamber between itself and the valve body to accumulate the fluid therein and to which at least a part of the injection ports opens. A circumferential surface of the fluid chamber recedes toward the injection ports so as to decrease a cross-sectional area of the fluid chamber that is taken along a radial direction of the injection port plate and to reserve a predetermined length of distance between itself and the injection ports.
Features and advantages of embodiments will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings:
The injector 10 has a casing 11, a magnetic pipe 12, a fixed core 13 and a driving portion 30. The casing 11 is a resinous mold that covers the magnetic pipe 12, the fixed core 13, the driving portion 30 and so on. At one end portion of the magnetic pipe 12 is installed a nozzle 20. Between the magnetic pipe 12 and the fixed core 13 is installed a nonmagnetic pipe 14 against a magnetic short circuit. The fixed core 13 and the nonmagnetic pipe 14, and the nonmagnetic pipe 14 and the magnetic pipe 12 are respectively connected with each other by laser welding and the like. One axial end portion of the fixed core 13 is formed a fuel inflow port 15. Fuel is supplied from a fuel pump (not shown) to the fuel inflow port 15 of the injector 10. The fuel supplied to the fuel inflow port 15 flows via a fuel filter 16 into an inner space of the fixed core 13. The fuel filter 16 is for removing foreign matters contained in the fuel.
The valve body 21 is installed on one end of the magnetic pipe 12 opposite from the fixed core 13. The valve body 21 is connected with the magnetic pipe 12 by laser welding and the like. As shown in
The needle (valve member) 25 is installed on the inner circumferential side of the magnetic pipe 12 and the valve body 21 to be slidable in its axial direction. The needle 25 is aligned approximately coaxial to the valve body 21. One axial end of the needle 25, which is opposite from the fuel inflow port 15, is provided with a seal portion 26. The seal portion 26 is for coming in contact with a valve seat 24 formed in the valve body 21. The needle 25 and the valve body 21 form a fuel passage 27 therebetween.
As shown in
The movable core 34 is installed inside the fixed core 13 to be slidable in its axial direction. The movable core 34 is cylinder-shaped and made of magnetic material such as steel. One end of the movable core 34 opposite from the fixed core 13 is integrally connected to the needle 25. Another end of the movable core 34 at the side of the fixed core 13 is in contact with a spring (elastic member) 17. The spring 17 is in contact with the movable core 34 at one end and with an adjusting pipe 18 at another end. The adjusting pipe 18 is press-fitted in the fixed core 13.
The spring 17 has a restitutive force to extend in the axial direction. Thus, the spring 17 pushes the movable core 34 and the needle 25 toward the valve body 21. The load that the spring 17 applies to the movable core 34 and the needle 25 can be modified by adjusting a press-fitting amount of the adjusting pipe 18 press-fitted into the fixed core 17. When the coil 32 is not energized, the spring 17 pushes the movable core 34 and the needle 25 toward the valve seat 24, and the seal portion 26 is seated on the valve seat 24. In the present embodiment, a coil spring is shown as an example of the spring 17. Alternatively, the spring 17 may be realized by other elastic members such as a leaf spring, an air damper, a fluid damper and so on.
The injector 10 in the proximity to the injection port plate 40 is described in detail in the following.
The injection port plate 40 is disposed on the leading end of the valve body 21. As shown in
As described above, the inner circumferential surface 50a of the spacer 50 forms a perimeter of the fuel chamber 52. Thus, a shape of the fuel chamber opening 51 and the inner circumferential face 50a of the spacer 50 determine a cross-sectional shape of the fuel chamber 51. In the first embodiment, the injection ports 41 formed on the injection port plate 40 are aligned on two coaxially disposed fictive circle lines as shown in
The inner circumferential surface 50a of the spacer 50, which forms the fuel chamber 52, is at a specific distance from fuel inflow side openings of the outer injection ports 412a-412h. Here, the fuel inflow side openings of the outer injection ports 412a-412h are ends of them at the side of the fuel chamber 52. As shown in
The SMD is a value to indicate an average diameter of a fuel injection spray, and the SMD variation ratio, which is shown in
The distances between the outer injection ports 412a-412h and the inner circumferential surface 50a of the spacer 50 are set as described above. Thus, as shown in
By the inner circumferential surface 50a of the spacer 50 that juts radially inward, an entire volume of the fuel chamber 52 decreases, and a dead volume in the fuel chamber 52 decreases. If the inner circumferential surface 50a of the spacer 50 does not juts radially inward, d2/d1 is excessively large at the intervals between the outer injection ports 412a-412h. As shown in
An operation of the injector 10 having the above-described construction is described in the following.
When the coil 32 is not energized, the fixed core 13 and movable core 34 generate no electromagnetic attraction force therebetween. Thus, the restitutive force of the spring 17 pushes the movable core 34 and the needle 25 away from the fixed core 13. Accordingly, when the coil 32 is not energized, the seal portion 26 of the needle 25 is seated on the valve seat 24 and no fuel is injected out of the injection ports 41.
When the coil 32 is energized, a magnetic field generated by the coil 32 forms a magnetic circuit in the plate housing 33, the magnetic pipe 12, the movable core 34 and the fixed core 13. Thus, the fixed core 13 and the movable core 34 generate electromagnetic attraction force therebetween. When the electromagnetic attraction force generated between the fixed core 13 and the movable core 34 exceeds the restitutive force of the spring 17, an integrated body of the movable core 34 and the needle 25 moves toward the fixed core 13. Accordingly, the seal portion 26 of the needle 25 lifts off the valve seat 24.
As shown in
When the power supply to the coil 32 is interrupted again, the electromagnetic attraction force between the fixed core 13 and movable core 34 vanishes. Thus, the restitutive force of the spring 17 pushes the integrated body of the movable core 34 and the needle 25 away from the fixed core 13. Accordingly, the seal portion 26 of the needle 25 is seated on the valve seat 24 again to interrupt the fuel flow between the fuel passage 27 and the fuel chamber 52, and the fuel injection stops.
In the first embodiment, the inner circumferential surface 50a of the spacer 50 juts radially inward, that is, toward the inner injection ports 411a-411d, so that a dead volume of the fuel chamber 52 at the periphery of the outer injection ports 412a-412h decreases. Thus, after the injection of a regulated amount of fuel, the fuel amount left in the fuel chamber 52 is decreased. As a result, the fuel amount sucked into the intake air decreases, and an air-fuel ratio variation of the intake air is limited. Further, by keeping the relation of d2/d1≧1, the spiral flow inertia of the fuel flowing into the outer injection ports 412a-412h is kept. Accordingly, it is possible to secure a fuel atomization performance and to decrease the dead volume in the combustion chamber 52.
Further, in the first embodiment, the shape of the fuel chamber opening 51 can be changed by replacing the spacer 50 with another one. Thus, fuel atomization property of the fuel injected out of the injection ports 41 can be adjusted by replacing the spacer 50.
In the first embodiment is disclosed an example in which the spacer 50 having the fuel chamber opening 51 is disposed between the valve body 21 and the injection port plate 40 to provide the fuel chamber 52 between the valve body 21 and the injection port plate 40.
Correspondingly, as shown in
In the third embodiment, a recess 71 is formed on the injection port plate 70 in contrast to the second embodiment in which the recess 28 is formed on the valve body 21. The recess 71 of the injection port plate 70 and the valve body 21 provides a fuel chamber 72 therebetween. As shown in
In the third embodiment, the outer injection ports 732a-732h are communicated with the fuel chamber 72 at their fuel inflow side openings. A distance from the outer injection ports 732a-732h to the outer and inner circumferential wall surfaces 71a, 71b of the recess 71 of the injection port plate 70 satisfies the relation of d2/d1≧1, in which d1 denotes inner diameters of the fuel inflow side openings of the outer injection ports 732a-732h, and d2 denotes a distance from the fuel inflow side openings of the outer injection ports 732a-732h to the outer or inner circumferential wall surfaces 71a, 71b. Thus, the fuel that has passed through the opening portion 22 of the valve body 21 forms a highly turbulent flow, then flows into each of the outer injection ports 732a-732h.
The spiral fuel flow along a cone-shaped inner circumferential surface 23 of the valve body 21, which has the opening portion 22 at its leading end, directly flows into the inner injection ports 731a-731d. A distance from the fuel inflow side openings of the inner injection ports 731a-731d to the inner circumferential wall 23 of the valve body 21, which provides the opening portion 22 is enough to flow highly turbulent fuel into the inner injection ports 731a-731d.
In the third embodiment, the outer injection ports 732a-732h and the outer and inner circumferential wall surfaces 71a, 71b of the recess 71 of the injection port plate 70 satisfies the relation of d2/d1≧1 as described above. Thus, highly turbulent fuel flows into each of the outer injection ports 732a-732h. Accordingly, an enough fuel atomization performance is secured.
Further, in the third embodiment, fuel inflow side openings of the inner injection ports 731a-731d open on the surface of the injection port plate 70 directly to the opening portion 22 of the valve body 21. That is, the inner injection ports 731a-731d are not adjacent to the fuel chamber 72. The fuel chamber 72 is formed only at the periphery of the outer injection ports 732a-732h, so that a dead volume in the injector 10 decreases, and the fuel left in the fuel chamber 72 also decreases.
Modified examples of the third embodiment are described in the following. In these modified examples, components that are substantially equivalent to those in the third embodiment are assigned reference numerals in common with each other not especially described.
In a first modified example of the third embodiment shown in
In a second modified example of the third embodiment shown in
In a third modified example of the third embodiment shown in
In a fourth modified example of the third embodiment shown in
In the fourth embodiment, recesses 71 (71a-71d) are formed on the injection port plate 70 to provide fuel chambers 72 (72a-72d) in an analogous way to the third embodiment. As shown in
In the fourth embodiment, the injection port plate 70 has four recesses 71 (71a-71d). The fuel inflow side openings of the outer injection ports 732a-732h open to the recesses 71 of the injection port plate 70 to be communicated with the fuel chambers 72. Every two of the eight outer injection ports 732a-732h constitute one injection port group. Specifically, the outer injection ports 732a, 732h constitute an injection port group 74A, the outer injection ports 732b, 732c constitute an injection port group 74B, the outer injection ports 732d, 732e constitute an injection port group 74C, and the outer injection ports 732f, 732g constitutes an injection port group 74D. Thus, the eight outer injection ports 732a-732h constitute four injection port groups 74A-74D.
The injection port plate 70 has four recesses 71a-71d that respectively correspond to the four injection port groups 74A-74D. That is, the outer injection ports 732a, 732h open to the recess 71a, the outer injection ports 732b, 732c open to the recess 71b, the outer injection ports 732d, 732e open to the recess 71c, and the outer injection ports 732f, 732g open to the recess 71d. Accordingly, four fuel chambers 72a-72d are formed between the injection port plate 70 and the valve body 21. As a result, the fuel chambers 72a-72d are provided respectively to the injection port groups 74A-74D that are composed of a plurality of the outer injection ports (732a, 732h), (732b, 732c), (732d, 732e), (732f, 732g).
Inner circumferential wall surfaces 75a-75d of the injection port plate 70 define the peripheries of the fuel chambers 72a-72d. The correspondence between the outer injection ports 732a-732h and the inner circumferential wall surfaces 75a-75d are as described above. Distances from the outer injection ports 732a-732h to the inner circumferential wall surfaces 75a-75d of the recesses 71a-71d of the injection port plate 70 satisfies the relation of d2/d1≧1, in which d1 denotes inner diameters of the fuel inflow side openings of the outer injection ports 732a-732h communicated with the fuel chambers 72a-72d, and d2 denotes distances from the fuel inflow side openings of the outer injection ports 732a-732h to the inner circumferential wall surfaces 75a-75d.
In the fourth embodiment, each of the injection port groups 74A-74D is provided with the fuel chamber 72a-72d, and no fuel chamber is formed at the intervals between the injection port groups 74A-74D. Thus, a dead volume formed at the intervals between every adjacent two of the injection port groups 74A-74D. Accordingly, it is possible to decrease a fuel amount left in the fuel chambers 72a-72d.
Modified examples of the fourth embodiment are described in the following. In these modified examples, components that are substantially equivalent to those in the fourth embodiment are assigned reference numerals in common with each other not especially described.
In a first modified example of the fourth embodiment shown in
In a second modified example of the fourth embodiment shown in FIGS. 15A and 15B, the injection port plate 70 is composed of a first injection port plate 710 and a second injection port plate 720. The first injection port plate 710 has four opening portions 710a-710d respectively in accordance with the fuel chambers 72a-72d. By fixing the second injection port plate 720 on a surface of the first injection port plate 710 opposite from the valve body 21, the recesses 71 (71A-71D) are formed between the valve body 21, the first injection port plate 70 and the second injection port plate 720. In the second modified embodiment shown in FIGS, the projection 700 is provided with no injection port (the inner injection port). Correspondingly, in the third modified example of the fourth embodiment shown in
In the fifth embodiment, recesses 81 (81a-81d) are formed on the injection port plate 80 to provide fuel chambers 82 (82a-82d) in an analogous way to the third embodiment. The injection port plate 70 has a plurality of injection ports 83. Specifically, the injection ports 893 include inner injection ports 831a-831d and outer injection ports 832a-832h, which are aligned on two coaxially disposed fictive circle lines as shown in
In the fifth embodiment, the injection port plate 80 has four recesses 81 (81a-81d). Three injection ports including one of the four inner injection ports 831a-831d and two of the eight outer injection ports 832a-832h constitute one injection port group. Specifically, the inner injection port 831a and the outer injection ports 832a, 832h constitute an injection port group 84A, the inner injection port 831b and the outer injection ports 832b, 832c constitute an injection port group 84B, the inner injection port 831c and the outer injection ports 832d, 832e constitute an injection port group 84C, and the inner injection port 831d and the outer injection ports 832f, 832g constitute an injection port group 84D. Thus, the four inner injection ports 831a-831d and the eight outer injection ports 832a-832h constitute four injection port groups 84A-84D.
The injection port plate 80 has four recesses 81a-81d that respectively correspond to the four injection port groups 84A-84D. That is, the inner injection port 831a and the outer injection ports 832a, 832h open to the recess 81a, the inner injection port 831b and the outer injection ports 832b, 832c open to the recess 81b, the inner injection port 831c and the outer injection ports 832d, 832e open to the recess 81c, and the inner injection port 831d and the outer injection ports 832f, 832g open to the recess 81d. Accordingly, four fuel chambers 82a-82d are formed between the injection port plate 80 and the valve body 21. As a result, the fuel chambers 82a-82d are provided respectively to the injection port groups 84A-84D that are composed of a plurality of the inner and outer injection ports (831a, 832a, 832h), (831b, 832b, 832c), (831c, 832d, 832e), (831d, 832f, 832g).
The correspondence between the inner and outer injection ports 831a-831d, 832a-832h and the inner circumferential wall surfaces 85a-85d, which define the peripheries of the fuel chambers 82a-82d, are as described above. Distances from the inner and outer injection ports 831a-831d, 832a-832h to the inner circumferential wall surfaces 85a-85d of the recesses 81a-81d of the injection port plate 80 satisfies the relation of d2/d1≧1, in which d1 denotes inner diameters of the fuel inflow side openings of the inner and outer injection ports 831a-831d, 832a-832h communicated with the fuel chambers 82a-82d, and d2 denotes distances from the fuel inflow side openings of the inner and outer injection ports 831a-831d, 832a-832h to the inner circumferential wall surfaces 85a-85d.
In the fifth embodiment, each of the injection port groups 84A-84D is provided with the fuel chamber 82a-82d, and no fuel chamber is formed at the intervals between the injection port groups 84A-84D, which include not only the outer injection ports 832a-832h but also the inner injection ports 831a-831d. Thus, a dead volume formed at the intervals between every adjacent two of the injection port groups 84A-84D. Accordingly, it is possible to decrease a fuel amount left in the fuel chambers 82a-82d.
In the sixth embodiment, recesses 91 (91a-91d) are formed on the injection port plate 90 to provide fuel chambers 92 (92a-92d) in an analogous way to the third embodiment. As shown in
In the sixth embodiment, the injection port plate 90 has four recesses 91a-91d that respectively correspond to the four injection ports 93a-93d. That is, the injection port 93a opens to the recess 91a, the injection port 93b opens to the recess 91b, the injection port 93c opens to the recess 91c, and the injection port 93d opens to the recess 91d. Accordingly, four fuel chambers 92a-92d are formed between the injection port plate 90 and the valve body 21. As a result, the fuel chambers 92a-92d are provided respectively to the injection ports 93a-93d. The correspondence between the injection ports 93a-93d and the inner circumferential wall surfaces 95a-95d, which define the peripheries of the fuel chambers 92a-92d, are as described above. Distances from the injection ports 93a-93d to the inner circumferential wall surfaces 95a-95d of the recesses 91a-91d of the injection port plate 90 satisfies the relation of d2/d1≧1, in which d1 denotes inner diameters of the fuel inflow side openings of the injection ports 93a-93d communicated with the fuel chambers 92a-92d, and d2 denotes distances from the fuel inflow side openings of the injection ports 93a-93d to the inner circumferential wall surfaces 95a-95d.
In the sixth embodiment, each of the injection ports 93a-93d is provided with the fuel chamber 92a-92d, and no fuel chamber is formed at the intervals between the injection ports 93a-93d. Thus, a dead volume formed at the intervals between every adjacent two injection ports 93a-93d. Thus, a dead volume formed at the intervals between every adjacent two injection ports 93a-93d. Accordingly, it is possible to decrease a fuel amount left in the fuel chambers 92a-92d.
In the above-described embodiments are described constructions in which any one of flat plate-shaped spacer 50 and an injection port plate 40, 70, 80, 90 is attached on the leading end of the valve body 21. Alternatively, as shown in
This description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-310931 | Oct 2004 | JP | national |
| 2005-275268 | Sep 2005 | JP | national |
