JP2011208530A - Electromagnetic fuel injection valve and method of manufacturing the same - Google Patents

Abstract

Provided is an electromagnetic fuel injection valve in which the length of a magnetic path from a movable core to the front end of a coil housing is shortened to reduce magnetic path resistance and the responsiveness of a valve assembly is good.
A valve housing comprising a valve seat member, a magnetic cylindrical body, a non-magnetic cylindrical body, a stationary core, and a fuel inlet cylinder, and a coil disposed on the outer periphery thereof, And a coil housing 31 whose front end is welded to the outer periphery of the magnetic cylindrical body 4, and an inner peripheral surface 4a of the magnetic cylindrical body 4, and is slidably fitted to the suction surface 5a of the fixed core 5. In the fuel injection valve including the valve assembly V having the movable core 12, the magnetic cylinder 4 and the nonmagnetic cylinder 6 are arranged so that the boundary surface B between them protrudes forward from the front end surface of the coil 30. At the same time, the movable core 12 is formed with a journal portion 12a that is slidably supported on the inner peripheral surface of the magnetic cylindrical body 4 at the radially inner position of the front end portion 31c of the coil housing 31.
[Selection] Figure 2

Description

  The present invention relates to an electromagnetic fuel injection valve mainly used for a fuel supply system of an internal combustion engine, and in particular, a valve seat member having a valve hole from the front end to the rear end of the fuel injection valve, a magnetic cylinder, and a nonmagnetic A cylinder housing, a fixed core, and a fuel inlet cylinder are sequentially connected to each other, a valve housing having a fuel flow path inside, a coil disposed on the outer periphery of the valve housing, and the coil is accommodated, and the front end is welded. A coil housing fixed to the outer periphery of the magnetic cylinder and magnetically connecting the magnetic cylinder and the fixed core; and a front end of the fixed core slidably fitted to the inner peripheral surface of the magnetic cylinder And a valve assembly that opens and closes the valve hole when the fixed core is demagnetized and excited, and includes a fixed core, a movable core, a magnetic cylinder, and a coil housing. , Through the coil When, an improvement of an electromagnetic fuel injection valve and its manufacturing method for forming a magnetic path for exciting the fixed core.

  Such an electromagnetic fuel injection valve is already known as disclosed in Patent Document 1 below.

JP 2006-83808 A

  In general, the inner peripheral surface of the magnetic cylinder of such an electromagnetic fuel injection valve slidably supports the movable core of the valve assembly. In the conventional electromagnetic fuel injection valve, the front end of the coil housing is In order to avoid the occurrence of distortion on the inner peripheral surface of the magnetic cylinder due to the welding heat during welding to the outer peripheral surface of the magnetic cylinder, the connecting end surface between the non-magnetic cylinder and the magnetic cylinder is connected to the front end of the coil. The sliding part of the movable core on the inner circumferential surface of the magnetic cylinder is arranged rearward from the surface so as to be moved backward from the welded part at the front end of the coil housing.

  However, in such a conventional one, the length of the magnetic path in the section from the front end of the coil housing to the fixed core through the movable core is increased, which increases the magnetic path resistance, thereby reducing the responsiveness of the valve assembly. There was found.

  The present invention has been made in view of such circumstances, and the length of the magnetic path from the movable core to the front end of the coil housing is shortened, the magnetic path resistance is reduced, and the responsiveness of the valve assembly is good. An object of the present invention is to provide an electromagnetic fuel injection valve and a method for manufacturing the same.

  In order to achieve the above object, the present invention provides a valve seat member having a valve hole, a magnetic cylinder, a nonmagnetic cylinder, a fixed core, and a fuel inlet cylinder from the front end to the rear end of the electromagnetic fuel injection valve. A valve housing that is successively connected and has an internal fuel flow path, a coil that is disposed on the outer periphery of the valve housing, and that accommodates the coil, and the front end is fixed to the outer periphery of the magnetic cylindrical body by welding. A coil housing that magnetically connects between the magnetic cylinder and the fixed core; and a movable core that is slidably fitted to the inner peripheral surface of the magnetic cylinder and is opposed to the suction surface at the front end of the fixed core. And a valve assembly that opens and closes the valve hole in accordance with demagnetization and excitation of the fixed core, and the fixed core, the movable core, the magnetic cylindrical body, and the coil housing, when the coil is energized, Magnetic path for exciting In the electromagnetic fuel injection valve to be formed, the magnetic cylinder body and the non-magnetic cylinder body are arranged so that a boundary surface between the magnetic cylinder body and the non-magnetic cylinder body protrudes forward from the coil, and a radially inward portion of the front end portion of the coil housing is disposed. A first feature is that the movable core is formed with a journal portion slidably supported on the inner circumferential surface of the magnetic cylindrical body at a position.

  In addition to the first feature, the second feature of the present invention is that the fixed core is arranged so that the suction surface at the front end thereof protrudes forward from the coil.

  Furthermore, the present invention provides the electromagnetic fuel injection valve according to the first or second feature, wherein the front end of the coil housing is fixed to the outer peripheral surface of the magnetic cylindrical body by welding, A third feature is that the peripheral surface and the suction surface of the fixed core are finished by cutting.

  According to the first feature of the present invention, the boundary surface between the magnetic cylindrical body and the nonmagnetic cylindrical body is disposed in front of the coil, and the magnetic cylindrical body is located at a radially inward position of the front end portion of the coil housing. By forming the journal portion slidably supported on the inner peripheral surface of the movable core, the magnetic path length in the section from the front end of the coil housing to the fixed core via the journal portion of the movable core is reduced. As a result, the magnetic path resistance in the above section decreases, and as a result, when the coil is energized, the magnetic flux quickly runs between both cores, and the rising angle of the attractive force becomes steep. The response of the solid V, particularly the valve opening response can be improved.

  According to the second feature of the present invention, since the suction surface at the front end of the fixed core is disposed in front of the front end surface of the coil, the magnetic field in the section from the front end of the coil housing to the fixed core through the movable core is arranged. The path length is further shortened and the magnetic path resistance is further reduced to improve the valve opening responsiveness of the valve assembly. When the coil is de-energized, the residual magnetism of the movable core is quickly lost. The three-dimensional valve closing response can also be improved. In addition, since the suction surface at the front end of the fixed core comes forward from the front end surface of the coil, the axial length of the valve assembly is reduced and its weight is reduced. Can be reduced.

  According to the third aspect of the present invention, the front end of the coil housing is fixed to the outer peripheral surface of the magnetic cylinder by welding, and then the inner peripheral surface of the magnetic cylinder and the suction surface of the fixed core are finished by cutting. As a result, according to the configuration of the first or second feature, the fixed portion by welding between the front end portion of the coil housing and the magnetic cylindrical body approaches the circumferential surface of the magnetic cylindrical body or the attracting surface of the fixed core, thereby Even if distortion occurs on the peripheral surface of the cylindrical body and the suction surface of the fixed core due to welding heat, the distortion can be removed by the above-described cutting process, thus ensuring accurate operation of the valve assembly and high performance electromagnetic A fuel injection valve can be obtained.

The longitudinal cross-sectional view of the electromagnetic fuel injection valve which concerns on this invention. FIG. 2 is an enlarged view of part 2 of FIG. 1. Cutting process explanatory drawing in the manufacturing process of an electromagnetic fuel injection valve.

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

  In FIG. 1, a valve housing 2 of an electromagnetic fuel injection valve (hereinafter simply referred to as a fuel injection valve) I for an engine is fitted to a cylindrical valve seat member 3 and a rear end portion of the valve seat member 3. A magnetic cylinder 4 that is liquid-tightly welded, a non-magnetic cylinder 6 that is abutted against the rear end of the magnetic cylinder 4 and is liquid-tightly welded, and an inner peripheral surface of the non-magnetic cylinder 6 A cylindrical fixed core 5 fitted with a front end portion and welded in a liquid-tight manner, and a fuel inlet cylinder 9 integrally connected to the rear end of the fixed core 5 with the same material.

  As shown in FIG. 2, the valve seat member 3 includes a valve hole 7 opened at the front end surface thereof, a conical valve seat 8 connected to the inner end of the valve hole 7, and a large diameter portion of the valve seat 8. And a cylindrical large-diameter hole 17 having a diameter larger than that of the valve-body guide 15 and connected to the rear end of the valve-body guide 15 via a tapered hole 16.

  A steel plate injector plate 10 having a plurality of fuel injection holes 11 communicating with the valve hole 7 is welded to the front end surface of the valve seat member 3 in a liquid-tight manner.

  A portion that does not fit with the fixed core 5 remains at the front end portion of the nonmagnetic cylindrical body 6, and the valve assembly V is accommodated in the valve housing 2 that extends from the portion to the valve seat member 3.

  The valve assembly V is welded to the movable core 12 opposed to the suction surface 5a at the front end of the fixed core 5, the valve rod 13 protruding integrally with the front end of the movable core 12, and the valve rod 13. On the outer peripheral surface of the movable core 12, the basic shape slidably supported by the guide 15 so as to open and close the valve hole 7 in cooperation with the valve seat 8 is composed of a spherical valve body 14. An annular journal portion 12 a that is slidably supported on the inner peripheral surface 4 a of the magnetic cylindrical body 4 is formed. Therefore, the valve assembly V is slidably supported on the valve housing 2 at two points of the valve body 14 and the journal portion 12a that are largely separated from each other, so that the opening / closing posture of the valve assembly V is stabilized. Around the spherical valve body 14, a plurality of flat flow path portions 18, 18... Permitting the passage of fuel are formed at equal intervals.

  The fixed core 5 is provided with a first vertical hole 19 connected to the hollow portion of the fuel inlet cylinder 9. The valve assembly V has a second vertical hole 20 that starts from the rear end surface of the movable core 12 and ends at the middle portion of the valve shaft 13, and the second vertical hole 20 is opened to the large-diameter hole 17 of the valve seat member 3. Lateral holes 21 are provided.

  As shown in FIGS. 1 and 2, an annular spring seat 24 facing the fixed core 5 is formed in the middle of the second vertical hole 20. A slotted pipe retainer 23 is press-fitted into the first vertical hole 19 of the fixed core 5, and the movable core 12 is urged toward the valve closing side of the valve body 14 between the retainer 23 and the spring seat 24. The valve spring 22 is contracted. At that time, the set load of the valve spring 22 is adjusted by the fitting depth of the retainer 23 into the first vertical hole 19.

  A ring-shaped stopper member 27 made of a non-magnetic material that protrudes slightly from the rear end surface of the movable core 12 and faces the suction surface 5a of the fixed core 5 is embedded. The stopper member 27 has a predetermined gap between the opposed end surfaces of the fixed core 5 and the movable core 12 by the stopper member 27 coming into contact with the suction surface 5a of the fixed core 5 when the fixed and movable cores 5 and 12 are attracted to each other. Is to remain.

  A coil assembly 28 is fitted to the outer periphery of the valve housing 2 so as to correspond to the fixed core 5 and the movable core 12. The coil assembly 28 includes a bobbin 29 fitted to the outer peripheral surface from the rear end portion of the magnetic cylindrical body 4 to the fixed core 5, and a coil 30 wound around the bobbin 29. At the rear end portion, a base end portion of the coupler terminal 33 protruding to one side is held, and the terminal of the coil 30 is connected to the coupler terminal 33. A synthetic resin primary coating layer 34 covering the outer periphery of the coil assembly 28 is molded so as to embed the coil 30. At this time, a coupler 35 that accommodates and holds the coupler terminal 33 and protrudes to one side of the coil assembly 28 is integrally formed with the primary coating layer 34.

  A magnetic coil housing 31 that houses and holds the coil assembly 28 is attached to the valve housing 2. The coil housing 31 includes a body portion 31a that surrounds the coil assembly 28, and a pair of front and rear end walls 31b that bend radially inward from both ends of the body portion 31a to support both front and rear end surfaces of the coil assembly 28. , 31b 'and a pair of front and rear connecting cylindrical portions 31c, 31c' which protrude axially outward from both end walls 31b, 31b 'and fit to the outer peripheral surfaces of the magnetic cylindrical body 4 and the fixed core 5. The distal end portions of the connecting tube portions 31c and 31c ′ are cut off at the outer periphery into thin portions 31d. These thin portions 31d are fixed to the outer peripheral surfaces of the magnetic cylindrical body 4 and the fixed core 5 by laser welding 32. The laser welding at the thin wall portion 31d requires relatively little heat input, and the thermal distortion of the magnetic cylindrical body 4 and the fixed core 5 can be kept small.

  After the thin-walled portion 31d is fixed by the welding 32, as shown in FIG. 3, when the valve body 14 and the inner peripheral surface 4a of the magnetic cylindrical body 4 that slidably supports the fixed core 5 are opened, the movable core is opened. The suction surface 5a of the fixed core 5 with which the 12 stopper members 27 abut and the annular relief groove 38 of the nonmagnetic cylindrical body 6 that receives the rear end edge of the movable core 12 are precisely finished by cutting. As described above, since the thermal distortion of the magnetic cylindrical body 4 and the fixed core 5 is small, the machining allowance can be reduced.

  Thus, the coil housing 31, the magnetic cylindrical body 4, the movable core 12 and the fixed core 5 form a magnetic path 39 for exciting the fixed core 5 when the coil 30 is energized. At that time, the magnetic cylinder 4 and the non-magnetic cylinder 6 are arranged such that the boundary surface B between them 4 and 6 comes out of the coil 30 by a distance S1, and the fixed core 5 is attracted to the front end thereof. The surface 5a is disposed so as to protrude a distance S2 ahead of the coil 30. In addition, the journal portion 12a on the outer periphery of the movable core 12 that is slidably supported on the inner peripheral surface of the magnetic cylindrical body 4 is disposed at the front end portion of the coil housing 31, that is, the radially inner position of the connecting cylinder portion 31c. Is done.

  Referring again to FIG. 1, the outer periphery of the magnetic cylinder 4 extends from the rear half of the magnetic cylinder 4 to the rear end of the fixed core 5 and is made of a synthetic resin that embeds the roots of the coil assembly 28, the coil housing 31, and the coupler 35. The secondary coating layer 36 is formed by molding.

  An annular seal groove 41 for mounting a seal member 40 such as an O-ring is formed on the outer periphery of the rear end portion of the fuel inlet tube 9. The front end wall of the seal groove 41 is constituted by a flange 42 a at the rear end of a collar 42 made of synthetic resin that is press-fitted into the front outer peripheral surface of the fuel inlet cylinder 9, and the rear end wall is the inlet of the fuel inlet cylinder 9. It is comprised by the attachment flange 43a of the fuel filter 43 press-fit in. Therefore, when the seal member 40 is mounted, the collar 42 is press-fitted into the front outer peripheral surface of the fuel inlet tube 9 and then the seal member 40 is fitted to the rear outer peripheral surface of the fuel inlet tube 9. The mounting flange 43 a is press-fitted into the inlet of the fuel inlet cylinder 9. By doing so, it is possible to mount the seal member 40 in the seal groove 41 without forcibly expanding the seal member 40. A seal member 44 that is in close contact with the front end surface of the secondary coating layer 36 is attached to the outer periphery of the magnetic cylindrical body 4.

  Next, the operation of this embodiment will be described.

  High-pressure fuel pumped from a fuel pump (not shown) to the fuel inlet cylinder 9 is filtered by the fuel filter 43, and then the inside of the valve housing 2, that is, the hollow portion of the fuel inlet cylinder 9, the first vertical hole 19 of the fixed core 5, The second vertical hole 20 and the horizontal hole 21 of the valve assembly V, the large-diameter hole 17, the tapered hole 16 and the valve body guide hole 15 of the valve seat member 3 are filled. When the coil 30 is demagnetized, the valve assembly V is pressed forward by the urging force of the valve spring 22, and the valve body 14 is seated on the valve seat 8.

  When the coil 30 is energized by energization, the magnetic flux generated by the coil 30 sequentially runs on the magnetic path 39, that is, the coil housing 31, the magnetic cylindrical body 4, the movable core 12 and the fixed core 5, and is generated by the magnetic force generated between the cores 5 and 12. The movable core 12 is attracted to the fixed core 5 against the set load of the valve spring 22 by the suction force, and the valve body 14 is separated from the valve seat 8, so that the valve hole 7 is opened and the valve seat member 3 High-pressure fuel exits the valve hole 7 and is injected from the fuel injection hole 11 of the injector plate 10 into a throttle body (not shown) equipped with the fuel injection valve I or an intake passage of the engine.

  Incidentally, as described above, the magnetic cylindrical body 4 and the nonmagnetic cylindrical body 6 are arranged so that the boundary surface B between the both 4 and 6 protrudes forward from the coil 30. In addition, the magnetic cylindrical body 4 Since the journal portion 12a on the outer periphery of the movable core 12 that is slidably supported on the inner peripheral surface of the coil housing 31 is disposed at the radially inward position of the connecting cylinder portion 31c at the front end portion of the coil housing 31, the front end of the coil housing 31 is provided. The length of the magnetic path in the section extending from the journal portion 12a of the movable core 12 to the fixed core 5 is shorter than the conventional one, and accordingly the magnetic path resistance in the section is reduced. As a result, when the coil 30 is energized, the magnetic flux quickly runs between both the cores 5 and 12 and the rising angle of the attractive force becomes steep, thereby improving the responsiveness of the valve assembly V, particularly the valve opening responsiveness. be able to.

  Further, as described above, the fixed core 5 has the front end attracting surface 5 a disposed in front of the coil 30, so that the magnetic path length in the section from the front end of the coil housing 31 to the fixed core 5 through the movable core 12. Not only improves the valve opening response of the valve assembly V by further reducing the magnetic path resistance, but also the loss of the residual magnetism of the movable core 12 is accelerated when the coil 30 is energized. The valve closing response of the assembly V can also be improved. In addition, since the suction surface 5a at the front end of the fixed core 5 protrudes ahead of the coil 30, the axial length of the valve assembly V is reduced from the conventional one, and the weight thereof is reduced. Is less seated on the valve seat 8, and the operating noise generated due to the stopper member 27 of the movable core 12 abutting against the suction surface 5a of the fixed core 5 is reduced from the conventional one.

  In manufacturing the fuel injection valve I, the front end of the coil housing 31 is fixed to the outer peripheral surface of the magnetic cylindrical body 4 by welding 32, and then the inner peripheral surface 4a of the magnetic cylindrical body 4 and the suction surface of the fixed core 5 are used. Since 5a is finished by cutting, according to the above-described configuration, the fixed portion by welding 32 between the front end portion of the coil housing 31 and the magnetic cylindrical body 4 is the inner peripheral surface 4a of the magnetic cylindrical body 4 and the suction surface of the fixed core 5. By approaching 5a, even if distortion occurs on the inner peripheral surface 4a of the magnetic cylindrical body 4 and the suction surface 5a of the fixed core 5 due to welding heat, the distortion can be removed by the cutting process. After the cutting process, the valve assembly V is inserted into the magnetic cylinder 4, and the valve seat member 3 is fitted to the front end of the magnetic cylinder 4 and welded. Thus, accurate operation of the valve assembly V can be ensured, and a high-performance fuel injection valve I can be obtained.

  Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various design changes can be made without departing from the scope of the present invention.

B ... Interface between magnetic cylinder and non-magnetic cylinder I ... Electromagnetic fuel injection valve V ... Valve assembly 2 ... Valve housing 3 ... ..Valve seat member 4... Magnetic cylinder 4a... Inner circumferential surface 5 of magnetic cylinder .. Fixed core 5a. Non-magnetic cylindrical body 7 ... valve hole 12 ... movable core 12a ... journal part 30 ... coil 31 ... coil housing 31c ... front end of coil housing (connecting cylinder) Part)
32 ... Welding 39 ... Magnetic path

Claims (3)

From the front end to the rear end of the electromagnetic fuel injection valve (I), a valve seat member (3) having a valve hole (7), a magnetic cylindrical body (4), a nonmagnetic cylindrical body (6), a fixed core (5 ) And the fuel inlet cylinder (9) are sequentially connected to each other, the valve housing (2) having a fuel flow path therein, a coil (30) disposed on the outer periphery of the valve housing (2), and the coil (30 ) And the front end (31c) is fixed to the outer periphery of the magnetic cylindrical body (4) by welding (32) to magnetically connect the magnetic cylindrical body (4) and the fixed core (5). A movable core that is slidably fitted to the coil housing (31) and the inner peripheral surface (4a) of the magnetic cylindrical body (4) and is opposed to the suction surface (5a) of the front end of the fixed core (5) And a valve assembly that opens and closes the valve hole (7) when the fixed core (5) is demagnetized and excited. (V), and the fixed core (5), the movable core (12), the magnetic cylindrical body (4) and the coil housing (31) are used to connect the fixed core (5) to the coil (30) when energized. In an electromagnetic fuel injection valve that forms a magnetic path (39) for excitation,
The magnetic cylindrical body (4) and the non-magnetic cylindrical body (6) are arranged so that the boundary surface (B) between them comes out from the front end surface of the coil (30) and the coil housing (31). ) That the journal (12a) is slidably supported on the inner peripheral surface of the magnetic cylindrical body (4) at the radially inner position of the front end (31c) of the movable core (12). A featured electromagnetic fuel injection valve. The electromagnetic fuel injection valve according to claim 1,
The electromagnetic fuel injection valve, wherein the fixed core (5) is arranged so that a suction surface (5a) at a front end thereof protrudes forward from the coil (30). In manufacturing the electromagnetic fuel injection valve according to claim 1 or 2,
After fixing the front end of the coil housing (31) to the outer peripheral surface of the magnetic cylinder (4) by welding (32), the inner peripheral surface (4a) of the magnetic cylinder (4) and the fixed core (5) ) Suction surface (5a) is finished by cutting, a method for manufacturing an electromagnetic fuel injection valve.

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