JP2012067665A - Injection valve for gaseous fuel, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection valve for gaseous fuel by which the gaseous fuel can smoothly pass through the inside of a valve plunger, a pressure loss is reduced and a desired fuel injection flow rate can be obtained.SOLUTION: In the injection valve for the gaseous fuel where vertical fuel holes 30 and 31 starting from the rear end surface of the valve plunger and finishing this side of a front end surface communicating with the inner part of a fuel inlet cylinder and having bottoms and a plurality of horizontal fuel holes 32 opening the vertical fuel holes 30 and 31 in a valve housing are provided in the valve plunger 10, conical rectifying protrusions 33 guiding the branched flow of the gaseous fuel going from the vertical fuel holes 30 and 31 toward the plurality of horizontal fuel holes 32 are formed at bottom surfaces of the vertical fuel holes 30 and 31 of the valve plunger 10.

Description

  The present invention relates to a gas fuel injection valve that supplies natural gas such as CNG and LPG to an internal combustion engine as fuel, and in particular, a nozzle member having a valve seat and a nozzle hole penetrating through the central portion of the valve seat, and the nozzle member A cylindrical valve housing made of a magnetic material connected to the rear end, a fixed core disposed behind the valve housing, and a valve body made of a fuel inlet tube connected to the rear end of the fixed core A valve plunger that is slidably fitted on a sliding guide surface on the inner periphery of the valve housing, and that opens and closes a nozzle hole in cooperation with the valve seat on one end surface between the fixed core and the valve plunger. A return spring that is compressed and biases the valve plunger toward the valve seat, and is arranged so as to surround the fixed core, and when energized, the valve plunger is attracted to the fixed core by the generated magnetic force, and the valve Let go of the seat The valve plunger has a bottomed vertical fuel hole that starts from the rear end surface and ends before the front end surface, and has a bottomed vertical fuel hole communicating with the inside of the fuel inlet cylinder, and the vertical fuel hole is provided in the valve housing. The present invention relates to a gas fuel injection valve provided with a plurality of lateral fuel holes that are open to each other and a method for manufacturing the same.

  Such a gas fuel injection valve is already known as disclosed in Patent Document 1 below.

JP 2007-40245 A

  In such a conventional fuel injection valve for gas fuel, as a gas fuel passage in the valve plunger, a bottomed vertical fuel hole starting from the rear end surface of the valve piston and ending before the front end surface, and this vertical fuel hole is provided in the valve housing. In the case of gas fuel, when the flow direction of the gas fuel changes from the vertical fuel hole to the horizontal fuel hole at a right angle, a relatively large pressure loss due to eddy current occurs in the gas fuel. The desired fuel injection flow rate may not be obtained.

  The present invention has been made in view of such circumstances, and allows gas fuel to pass smoothly through the valve plunger, reducing its pressure loss and obtaining a desired fuel injection flow rate. It aims at providing the injection valve for gas fuels.

  In order to achieve the above object, the present invention provides a cylindrical member made of a magnetic material, which is connected to a rear end of a nozzle member having a valve seat and a nozzle hole penetrating through the central portion of the valve seat. A valve body comprising a valve housing, a fixed core disposed behind the valve housing, and a fuel inlet cylinder connected to the rear end of the fixed core, and a sliding guide surface on the inner periphery of the valve housing. And a valve plunger that opens and closes a nozzle hole in cooperation with the valve seat on one end surface, and is compressed between the fixed core and the valve plunger to urge the valve plunger toward the valve seat side. A return spring, and a coil disposed so as to surround the fixed core, and when energized, the coil that causes the valve plunger to be attracted to the fixed core by a generated magnetic force and separated from the valve seat. From the rear edge Gas fuel injection having a bottomed vertical fuel hole communicating with the inside of the fuel inlet cylinder and a plurality of horizontal fuel holes for opening the vertical fuel hole into the valve housing, ending before the front end face In the valve, a first feature is that a conical rectifying protrusion for inducing a diversion of gas fuel from the vertical fuel hole toward the plurality of horizontal fuel holes is formed on the bottom surface of the vertical fuel hole of the valve plunger. . The vertical fuel holes correspond to a large diameter vertical fuel hole 30 and a small diameter vertical fuel hole 31 in an embodiment of the present invention described later.

  In addition to the first feature, the present invention also includes a first journal portion that is slidably fitted to the sliding guide surface with a short shaft portion from the front end side and a diameter larger than the short shaft portion. A long shaft portion having a diameter smaller than that of the journal portion and a longer shaft portion, and a second journal portion having a diameter larger than that of the long shaft portion and slidably fitted to the sliding guide surface are sequentially connected integrally in a coaxial manner. A second feature is that a plunger is formed and the valve plunger is made of metal injection molding.

  Further, in the present invention, in addition to the second feature, a plurality of ribs for integrally connecting the first and second journal portions to the outer peripheral surface of the long shaft portion are integrally projected. It is characterized by.

  Furthermore, the present invention provides a first step in which the valve plunger is formed by metal injection molding using a magnetic metal as a raw material in manufacturing the gas fuel injection valve according to the second or third feature, and after the first step. , A second step of baking a seating member and a cushion member made of rubber on the front end surface and the rear end surface of the valve plunger, and after the second step, a coating of a fluororesin is coated on the outer peripheral surface of the valve plunger. The fourth feature is to execute 3 or so.

  According to the first feature of the present invention, in the valve plunger, when the gas fuel is directed from the bottom surface of the vertical fuel hole to the plurality of horizontal fuel holes, the gas fuel is rectified radially by the conical rectification protrusion on the bottom surface. , Dispersed and can pass through a plurality of lateral fuel holes smoothly. Therefore, the pressure loss of the gas fuel can be kept small in the valve plunger, and the desired gas fuel injection amount can be obtained. In addition, the rectification of the gas fuel by the rectification protrusion can prevent the oil mixed with the gas fuel from adhering to and accumulating on the bottom surface of the vertical fuel hole.

  According to the second aspect of the present invention, the valve plunger is provided with a relatively complicated shape including a vertical fuel hole and a plurality of horizontal fuel holes inside, and first and second journal parts on the outside. First, it can be obtained easily and inexpensively by using metal injection molding.

  According to the third feature of the present invention, the long shaft portion is effectively reinforced by having a plurality of ribs connecting the first and second journal portions on the outer periphery thereof. It can contribute to improving the valve plunger's open / close response by reducing the thickness and reducing the weight of the valve plunger.

  According to the fourth aspect of the present invention, the valve plunger can be manufactured with high yield and precision, and the generation of burrs can be suppressed, and therefore post-processing is not required, which can contribute to cost reduction. . Further, the seating member and the cushion member are baked on the front end surface and the rear end surface of the valve plunger having a relatively rough surface roughness, so that the peel strength of the seating member and the cushion member can be increased and the durability can be improved. Furthermore, the outer surface of the valve plunger can be coated with a fluorine resin coating with good adhesion, and this coating prevents sticking of the valve plunger to the sliding guide surface and ensures smooth operation of the valve plunger. Can do.

The longitudinal cross-sectional view of the injection valve for gas fuels concerning this invention. FIG. 2 is an enlarged view of part 2 of FIG. 1. The perspective view of the valve plunger in the injection valve for gas fuels. Manufacturing process explanatory drawing of the said valve plunger.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, in FIG. 1, a gas fuel injection valve I according to the present invention has a front end portion mounted in a mounting hole Ea provided in a pipe wall of an engine intake pipe E, and gas fuel is supplied to the intake pipe E during the intake stroke of the engine. Inject into. The valve body 1 of the injection valve I is a hollow body made of a magnetic material in which a front end portion is coupled and welded to an outer peripheral surface of a cylindrical nozzle member 2 and a flange portion 2a at the rear end of the nozzle member 2. A cylindrical valve housing 3, a hollow cylindrical fixed core 5 integrally connected to a rear end of the valve housing 3 via a nonmagnetic cylindrical body 4, and a rear end of the fixed core 5 are integrally formed. A hollow cylindrical fuel inlet tube 6 is provided. The fixed core 5 is formed so that the inner diameter thereof is smaller than the inner diameter of the valve housing 3, and the suction surface 5 b at the front end is opposed to a later-described valve plunger 10 of the valve housing 3.

  The nozzle member 2 has a flat valve seat 7 facing the inside of the valve housing 3 and a nozzle hole 8 that passes through the central portion and opens at the front end surface of the nozzle member 2. An annular shim 9 to be adjusted is interposed between the nozzle member 2 and the valve housing 3.

  An inner peripheral surface of the valve housing 3 is a sliding guide surface 3a, and a valve plunger 10 made of a magnetic material is slidably fitted on the sliding guide surface 3a.

  As shown in FIGS. 2 and 3, the valve plunger 10 includes a short shaft portion 11 from the front end side, a first shaft that is larger in diameter than the short shaft portion 11 and is slidably fitted to the sliding guide surface 3a. A journal 13, a long shaft 12 that is smaller in diameter than the short shaft 11 and longer than the short shaft 11, and a second journal 14 that is larger in diameter than the long shaft 12 and is slidably fitted to the sliding guide surface 3 a A rubber seating member 17 that can be seated on the valve seat 7 is attached to the front end surface of the short shaft portion 11 by baking. Further, a rubber-made annular cushion member 18 facing the suction surface 5 b of the fixed core 5 is attached to the rear end surface of the second journal portion 14 by baking, and between the cushion member 18 and the opposed surface of the fixed core 5 is provided. When the seating member 17 is seated on the valve seat 7, a predetermined gap corresponding to the valve opening stroke of the valve plunger 10 is set.

  The second journal portion 14 is formed such that its axial width is larger than the axial width of the first journal portion 13, and the outer peripheral surface of the second journal portion 14 is on the fixed core 5 side on the valve housing 3 side. A first sliding surface 14a slidably fitted to the sliding guide surface 3a, a second sliding surface 14b slidably fitted to the sliding guide surface 3a on the long shaft portion 12 side, and An annular groove 14c that separates the first and second sliding surfaces 14a and 14b is formed. At that time, the annular groove 14c is formed shallow enough to allow the magnetic flux to transfer from the groove bottom to the sliding guide surface 3a of the valve housing 3. The outer peripheral surface of the valve plunger 10 is coated with a fluororesin film 19.

  In addition, when the diameter of the outer peripheral surface of the first journal portion 13 is D1, the diameter of the first sliding surface 14a is D2, and the diameter of the second sliding surface 14b is D3, One journal portion 13 and first and second sliding surfaces 14a and 14b are formed.

D1 ≦ D2 ≧ D3
A coil assembly 20 is disposed from the region where the second journal portion 14 of the valve housing 3 is fitted to the fixed core 5 and surrounding them. The coil assembly 20 includes a valve housing 3, a bobbin 21 fitted to the outer periphery of the nonmagnetic cylindrical body 4 and the fixed core 5, and a coil 22 wound around the outer periphery of the bobbin 21. A magnetic coil housing 23 is disposed on the outer periphery of the solid 20 to cover it. The front end of the coil housing 23 has an annular end wall 23a that receives the front end surface of the coil assembly 20 and fits to the outer periphery of the valve housing 3. A rear yoke flange 25 is integrally fixed on the outer peripheral surface of the valve housing 3 and is fitted to the inner peripheral surface of the rear end of the coil housing 23 while being in contact with the rear end surface of the coil assembly 20. The outer peripheral surface of the core 5 is integrally projected. Thus, the coil assembly 20 and the coil housing 23 are attached to the valve body 1. A resin mold layer 26 is formed on the outer peripheral surfaces of the front yoke flange 24, the coil housing 23, and the fuel inlet cylinder 6 so as to continuously cover them. A coupler 28 that protrudes and holds an energization terminal 27 that is continuous with the coil 22 is integrally formed.

  The valve plunger 10 has a large-diameter vertical fuel hole 30 starting from the rear end surface and ending before the front end surface of the first journal portion 13, and starting from the bottom surface of the large-diameter vertical fuel hole 30 and before the front end surface of the short shaft portion 11. A bottomed small-diameter vertical fuel hole 31 and a plurality of horizontal fuel holes 32, 32... That open the small-diameter vertical fuel hole 31 into the outer peripheral surface of the short shaft portion 11, that is, the valve housing 3, are provided. A conical rectification projection 33 is formed at the center of the bottom surface of the fuel hole 31 to guide the diversion of the gas fuel from the small diameter vertical fuel hole 31 to the plurality of horizontal fuel holes 32, 32. A plurality of ribs 12 a, 12 a... Are formed on the outer peripheral surface of the long shaft portion 12 so as to extend in the axial direction and integrally connect the first and second journal portions 13, 14. Since the long shaft portion 12 is effectively reinforced by the ribs 12a, 12a, etc., the long shaft portion 12 is thinned, and thus the valve plunger 10 is lightened, and the open / close response of the valve plunger 10 is improved. Can contribute.

  The large diameter vertical fuel hole 30 communicates with the hollow portion 5 a of the fixed core 5, and the rearward annular step formed between the large diameter vertical fuel hole 30 and the small diameter vertical fuel hole 31 is a spring seat 34. Thus, the spring seat 34 is disposed in front of the first sliding surface 14a.

  On the other hand, a hollow retainer 37 made of a spring pin is mounted on the inner peripheral surface of the hollow portion 5 a of the fixed core 5, and the valve plunger 10 is attached to the valve seat 7 side between the retainer 37 and the spring seat 34. The return spring 35 is biased. A fuel filter 38 is attached to the inlet of the hollow portion 6 a of the fuel inlet cylinder 6 that is continuous with the hollow portion 5 a of the fixed core 5.

  A pair of front and rear synthetic resin ring members 41 and 42 defining an annular front seal groove 40 are fitted on the outer periphery of the nozzle member 2, and the nozzle member 2 is inserted into the front seal groove 40 of the engine. When inserted into the mounting hole Ea of the intake pipe E, a front O-ring 43 that is in close contact with the inner peripheral surface thereof is mounted.

  An annular rear seal groove 45 is defined on the outer periphery of the rear end portion of the fuel inlet tube 6 by a flange 46 formed at the rear end of the fuel inlet tube 6 and the rear end surface of the resin mold layer 26. When the fuel distribution pipe D is fitted to the outer periphery of the fuel inlet cylinder 6, a rear O-ring 47 that is in close contact with the inner peripheral surface is attached to the seal groove 45.

  Next, the operation of this embodiment will be described.

  In the demagnetized state of the coil 22, the valve plunger 10 is pressed forward by the set load of the return spring 35 to seat the seating member 17 on the valve seat 7.

  When the coil 22 is excited by energization, the magnetic flux generated by the coil 22 sequentially travels through the coil housing 23, the valve housing 3, the second journal portion 14, the fixed core 5, the rear yoke flange 25, and the coil housing 23. The valve plunger 10 is attracted to the fixed core 5 against the set load of the return spring 35 by the magnetic force generated therebetween, the seat member 17 is separated from the valve seat 7 and the nozzle hole 8 is opened. At this time, when the rubber cushion member 18 of the valve plunger 10 abuts against the front end surface of the fixed core 5, the valve opening limit of the valve plunger 10 is regulated.

  When the nozzle hole 8 is opened, the gas fuel sent from the gas fuel tank (not shown) to the fuel distribution pipe D flows into the fuel inlet cylinder 6 and is filtered by the fuel filter 38, and the large size of the hollow retainer 37 and the valve plunger 10 is large. It passes through the diameter vertical fuel hole 30, the small diameter vertical fuel hole 31, and the horizontal fuel holes 32, 32... Into the valve housing 3 and is injected from the nozzle hole 8 into the intake pipe E of the engine.

  By the way, in the valve plunger 10, the conical rectifying protrusion 33 is formed at the center of the bottom surface of the small diameter vertical fuel hole 31. When flowing to the hole 31 and reaching the bottom surface of the small-diameter vertical fuel hole 31, the gas fuel is rectified and dispersed radially by the rectifying protrusions 33 and can smoothly pass through the plurality of horizontal fuel holes 32. Therefore, the pressure loss of the gas fuel can be kept small in the valve plunger 10, and the desired gas fuel injection amount can be obtained. In addition, the gas fuel rectification by the rectifying protrusion 33 can prevent the oil mixed in the gas fuel from adhering to and accumulating on the bottom surface of the small diameter vertical fuel hole 31.

  Further, in the valve plunger 10, the second journal portion 14 is formed so that the axial width thereof is larger than the axial width of the first journal portion 13, and the outer peripheral surface of the second journal portion 14 has a fixed core 5. The first sliding surface 14a slidably fitted to the sliding guide surface 3a of the valve housing 3 on the side, and the second sliding slidably fitted to the sliding guide surface 3a on the long shaft portion 12 side. Since the moving surface 14b and the annular groove 14c that separates the first and second sliding surfaces 14a and 14b are formed, a large amount of magnetic flux is generated when the magnetic flux flows from the valve housing 3 to the first journal portion 13. Is transferred from the sliding guide surface 3a of the valve housing 3 to the first and second sliding surfaces 14a, 14b of the second journal portion 14 in contact therewith, and between the sliding surfaces 14a, 14b. The groove bottom of the annular groove 14c that is separated from the long shaft portion 1 Extremely shallower than the outer circumferential surface of the so formed a small gap between the sliding guide face 3a, part of the magnetic flux is passed through the minute gap between the valve housing 3 to the second journal portion 14. Thus, a relatively large magnetic path area can be ensured between the valve housing 3 and the second journal portion 14, and the valve opening response of the valve plunger 10 is improved.

  Moreover, although the axial width of the second journal portion 14 is larger than that of the first journal portion 13, the first and second sliding surfaces of the second journal portion 14 separated by the annular groove 14c. Since 14a and 14b have the comparatively narrow axial direction width | variety similar to the 1st journal part 13, the oil mixed with the gas fuel introduced in the valve housing 3 is the 1st journal part 13 and the 1st journal part. Even if the oil film is formed by entering between each of the second sliding surfaces 14a, 14b and the sliding guide surface 3a, the oil film is easily sheared by the valve opening force due to the magnetic force of the valve plunger 10, The sticking of the plunger 10 to the sliding guide surface 3a is eliminated. A fluororesin film 19 coated on the outer peripheral surface of the valve plunger 10 promotes shearing of the oil film.

  Thus, the second journal portion 14 can satisfy the conflicting requirements of securing the necessary magnetic path area and preventing sticking by the oil film, and can improve the valve opening response of the valve plunger 10.

  Further, when the valve plunger 10 is opened and closed, the first journal portion 13 and the first and second sliding surfaces 14a and 14b of the second journal portion 14 slide on the sliding guide surface 3a of the valve housing 3. Therefore, you can always maintain a stable posture.

  In particular, when the diameter of the outer peripheral surface of the first journal portion 13 is D1, the diameter of the first sliding surface 14a is D2, and the diameter of the second sliding surface 14b is D3, D1 ≦ D2 ≧ D3. Thus, the sliding gap between the first sliding surface 14a and the sliding guide surface 3a is the sliding distance between the first journal portion 13 and the second sliding surface 14b and the sliding guide surface 3a. The spring seat 34 that supports the movable end of the return spring 35 is disposed at a position in front of the first sliding surface 14 a in the second journal portion 14. Therefore, the aligning action acts on the valve plunger 10 from the return spring 35, and the posture of the valve plunger 10 can be further stabilized.

  Next, a method for manufacturing the valve plunger 10 including the fluororesin coating 19 and the seating member 17 and the cushion member 18 as described above will be described with reference to FIG.

  First, as shown in FIG. 4A, the valve plunger 10 having the above-described structure is manufactured by metal injection molding using a magnetic metal as a material. According to this, the valve plunger 10 can be manufactured with high yield and precision, and the generation of burrs can be suppressed. Therefore, post-processing is not required, which can contribute to cost reduction.

  Next, as shown in FIG. 4B, a seating member 17 and a cushion member 18 made of rubber are baked on the front end surface and the rear end surface of the valve plunger 10. According to this, the seating member 17 and the cushion member 18 are baked on the front end surface and the rear end surface of the valve plunger 10 having a relatively rough surface roughness, and the peel strength of the seating member 17 and the cushion member 18 is increased. Durability can be improved.

  Finally, as shown in FIG. 4C, the outer peripheral surface of the valve plunger 10 is coated with a fluorine resin film 19. According to this, the adhesiveness of the fluororesin coating 19 to the outer peripheral surface of the valve plunger 10 made of metal injection molding can be enhanced.

  The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention.

I ... Gas fuel injection valve 1 ... Valve body 2 ... Nozzle member 3 ... Valve housing 3a ... Sliding guide surface 5 ... Fixed core 7 ... Valve seat 8 ... Nozzle hole 10 ... Valve plunger 11 ... Short shaft part 12 ... Long shaft part 13 ... First journal part 14 .... second journal part 22 .... coil 30,31 ... vertical fuel hole (large diameter vertical fuel hole, small diameter vertical fuel hole)
32... Horizontal fuel hole 33...

Claims (4)

A nozzle member (2) having a valve seat (7) and a nozzle hole (8) penetrating through the central portion of the valve seat (7), and a magnetic body connected to the rear end of the nozzle member (2) It comprises a cylindrical valve housing (3), a fixed core (5) disposed behind the valve housing (3), and a fuel inlet cylinder (6) connected to the rear end of the fixed core (5). A valve body (1) and a sliding guide surface (3a) on the inner periphery of the valve housing (3) are slidably fitted, and one end surface cooperates with the valve seat to open and close the nozzle hole (8). A valve plunger (10), a return spring (35) that is contracted between the fixed core and the valve plunger (10) and biases the valve plunger (10) toward the valve seat (7), It is arranged so as to surround the fixed core (5). A coil (22) that is attracted to the fixed core (5) and separated from the valve seat (7), and the valve plunger (10) starts from the rear end surface and ends before the front end surface; A bottomed vertical fuel hole (30, 31) communicating with the inside of the fuel inlet cylinder (6), and a plurality of horizontal fuel holes (32) for opening the vertical fuel hole (30, 31) into the valve housing; In the gas fuel injection valve provided with
On the bottom surface of the vertical fuel hole (30, 31) of the valve plunger (10), a conical shape for inducing a diversion of gas fuel from the vertical fuel hole (30, 31) toward the plurality of horizontal fuel holes (32). A gas fuel injection valve, characterized in that a flow regulating projection (33) is formed. The gas fuel injection valve according to claim 1,
A short shaft portion (11) from the front end side, a first journal portion (13) having a larger diameter than the short shaft portion (11) and slidably fitted to the sliding guide surface (3a), the first journal A long shaft portion (12) having a diameter smaller than that of the portion (13) and longer than that, and a second journal portion having a diameter larger than that of the long shaft portion (12) and slidably fitted to the sliding guide surface (3a) A gas fuel injection valve characterized in that the valve plunger (10) is constructed by sequentially connecting (14) coaxially and integrally, and the valve plunger (10) is made of metal injection molding. The gas fuel injection valve according to claim 2,
A gas characterized by integrally projecting a plurality of ribs (12a) integrally connecting the first and second journal parts (13, 14) on the outer peripheral surface of the long shaft part (12). Fuel injection valve. In producing the gas fuel injection valve according to claim 2 or 3,
A first step of forming the valve plunger (10) by metal injection molding using a magnetic metal as a raw material, and a seating made of rubber on the front end surface and the rear end surface of the valve plunger (10) after the first step. A second step of baking the member (17) and the cushion (18) and a third step of coating the outer peripheral surface of the valve plunger (10) with a fluororesin coating (19) after the second step are performed. The manufacturing method of the injection valve for gaseous fuel characterized by the above-mentioned.

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