JP2014037055A - Fuel injection valve and combination method of two components - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely combine positions of two components in a combination step without affecting precision of a single component.SOLUTION: In a state that mutual portions required for positioning of two components 15 and 17 to be connected are positioned by a mandrel 31, a soft member 17 is sheared by a corner part 15c provided in a hard member 15, and a side face of the corner part 15c is fitted into a sheared face 17c of the soft component 17 during shearing, and subsequently, fitting faces of the two components are combined by plastic combination, press fit, or welding.

Description

  The present invention relates to a method for positioning and joining two parts, and a fuel injection valve using the method.

  A method described in Japanese Patent Publication No. 7-10471 (Patent Document 1) is known as a concentric coupling method for components composed of a plurality of members. In FIG. 1 of Patent Document 1, a taper hole (valve seat) 10 c is formed in the inner bottom of the nozzle body (outer cylindrical part) 10 provided with the orifice 11, and a through hole 12 a is provided in the nozzle body 10. The swirler (inner cylindrical part) 12 is installed while ensuring the clearance, and the punching 16 is used to position the swirler 12 and the nozzle body 10 while the taper hole 10c and the through hole 12a of the swirler 12 are centered by the positioning guide pin 14. The vicinity of the fitting portion (swirler 12 side) was pressed so that local plastic flow was generated, and both parts were plastically connected concentrically by the force of this plastic flow.

  A method described in Japanese Patent No. 3931143 (Patent Document 2) is also known.

  In Patent Document 2, a protrusion 10d is provided on the bottom surface of the nozzle body 10 in addition to Patent Document 1, and the swirler 12 bites into the protrusion 10d to mechanically suppress the radial deviation and prevent the coaxiality from deteriorating. It was something to do.

Japanese Patent Publication No. 7-10471 Japanese Patent No. 3931143

  In Patent Document 1, when the swirler and the nozzle body are concentrically coupled by the force of plastic flow, if the coaxiality of the inner and outer diameters of the swirler is 0 and the coaxiality of the inner diameter of the nozzle body and the tapered hole is 0, the nozzle Clearance between inner diameter and swirler outer diameter is uniform all around. However, if the concentricity of either the nozzle or the swirler is not 0, the clearance between the nozzle inner diameter and the swirler outer diameter will be non-uniform, so the stress generated at the time of coupling will be larger on the side where the clearance is smaller, so The larger side becomes smaller. For this reason, when the guide pin is removed after the coupling, the spring back is generated so that the residual force is uniform over the entire circumference. That is, the swirler moves from the smaller clearance to the larger clearance, and a coaxial shift occurs between the tapered hole and the inner diameter of the swirler. In addition, the amount is influenced by the accuracy of the coaxiality of the parts. When the deviation amount exceeds a specified value, the smooth operation of the movable valve is hindered, and in the worst case, fuel leakage occurs from the seat portion.

  On the other hand, in Patent Document 2, the problem of Japanese Patent Publication No. 7-10471 is improved by biting the swirler 12 into the protrusion 10d. However, when the vicinity of the outer periphery of the upper surface of the swirler 12 is pressed by the protrusion 15a provided at the tip of the punch 15 in FIG. 3 and is plastically coupled, the spring back is exerted on the pressing side of the swirler 12 due to the accuracy of the parts as in Patent Document 1. May occur, the swirler inner diameter portion 12a may be inclined, and the coaxiality may be deteriorated.

  As described above, with the conventional technology, the swirler inner diameter after joining and the coaxiality of the seat surface are affected by the component accuracy, and each component cannot be assembled with high accuracy unless it is processed with high accuracy. There was a problem that fuel leakage from the seat part and the operation of the movable valve were adversely affected.

  It is an object of the present invention to provide a two-part joining method that is not easily affected by the precision of individual parts and that can maintain a high degree of coaxiality after joining, and has excellent oil-tightness using the two parts, and has a high movable valve. An object of the present invention is to provide a fuel injection valve capable of guiding with high accuracy.

  In order to achieve the above object, in the present invention, of the two parts to be joined, the softer members are sheared at the corners provided on the harder member in a state where the parts that need to be positioned are positioned with a jig. While processing and shearing, the side surfaces of the corners and the sheared surfaces of the soft parts are fitted, and then the fitting surfaces of the two parts are joined by plastic bonding, press-fitting, or welding, and the fitting is performed. It is an outer cylindrical part with a bottom that has multiple steps on the inner surface and a hole with a straight portion in the center of the inner bottom, and the softer member penetrates in the center. An inner cylindrical part having a hole, and with the inner cylindrical part placed on a plurality of steps of the outer cylindrical part, positioning guide pins are inserted into the through holes of the inner cylindrical part. Insert until it is guided by the straight part of the hole of the inner cylindrical part and outer cylindrical part Residue generated on the side surface of at least one step of the plurality of steps by performing concentric temporary positioning and pressing the inner cylindrical component so that the plurality of steps of the outer cylindrical component are bitten. The inner cylindrical part and the outer cylindrical part are coupled by the self-tightening force that is stress.

  Further, a gap is provided on the side surface other than the sheared fitting portion so that an external force affecting the accuracy is not applied.

  According to the present invention, the two parts can be fitted in a uniform state (gap 0) with the positioning portion as a reference, and there is no deterioration in accuracy due to springback, gaps, etc. by joining at the fitting surface. The two parts can be combined with high accuracy while maintaining the state. In addition, the assembly accuracy of the two components can be obtained by being coupled without being affected by the component accuracy.

  In the fuel injection valve using the present invention, since the coaxiality between the guide portion and the seat surface is good and the valve body operates smoothly, the fuel can be stably and accurately injected with good responsiveness. Further, fuel leakage from the seat portion related to assembly accuracy can be eliminated.

The longitudinal cross-sectional view of the fuel injection valve which becomes one Example of this invention. The longitudinal cross-sectional view which shows the set state and assembly jig | tool of a nozzle and a guide. The longitudinal cross-sectional view which shows the positioning state of a nozzle and a guide. The longitudinal cross-sectional view which shows the shearing state of a nozzle and a guide. The longitudinal cross-sectional view which shows the combined state of a nozzle and a guide. The flowchart which shows the joint process of a nozzle and a guide. The enlarged view which shows the nozzle and guide part of the fuel injection valve after completion | finish of an assembly. The longitudinal cross-sectional view which shows the combined state of a nozzle and a guide. The longitudinal cross-sectional view which shows the combined state of a nozzle and a guide. The longitudinal cross-sectional view which shows the bearing structure used as one Example of this invention. The longitudinal cross-sectional view which shows the coupling | bonding method of the housing and bearing used as 2nd Example. The longitudinal cross-sectional view which shows the coupling structure (welding) of a housing and a bearing. The longitudinal cross-sectional view which shows the coupling structure (press-fit) of a housing and a bearing. Comparison between the concentricity of the nozzle and the guide in the first embodiment and the concentricity by the conventional method.

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

  FIG. 1 is a longitudinal sectional view showing the overall configuration of a fuel injection valve according to an embodiment of the present invention.

  The fuel injection valve body 1 includes a magnetic circuit including a core 2, a yoke 3, a housing 4, and a mover 5, a coil 6 that excites the magnetic circuit, and a terminal portion 7 that energizes the coil 6. A seal ring 8 is coupled between the core 2 and the housing 4 to prevent fuel from flowing into the coil 6.

  Valve parts are housed inside the housing 4, and a movable element 5, a nozzle 9, and a ring 10 that adjusts the stroke amount of the movable element 5 are arranged. The movable element 5 is obtained by connecting the valve body 11 and the movable core 12 with a joint 13, and suppresses the bounce when the movable element 5 is closed in cooperation with the pipe 18 between the movable core 12 and the joint 13. A plate 14 is provided.

  The housing 4 and the nozzle 9 constituting the outer cover member cover the periphery of the movable element 5, and the nozzle 9 is movable together with the nozzle 15 having a sheet surface 15 a and an orifice 54 at the tip and a cup shape, and the guide plate 16. A guide 17 for holding the child 5 slidably is provided.

  A spring 19 that presses the valve element 11 against the seat surface 15a via the pipe 18 and the plate 14, an adjuster 20 that adjusts the pressing load of the spring 19, and a filter 21 that prevents entry of contamination from the outside are disposed inside the core 2. Has been.

  Next, the operation of the fuel injection valve body 1 will be described in detail.

  When the coil 6 is energized, the mover 5 is attracted in the direction of the core 2 against the urging force of the spring 19, and a gap is formed between the valve seat portion 11a at the tip of the mover 5 and the seat surface 15a (opening). Valve state). The pressurized fuel first enters the nozzle 9 from the core 2, the adjuster 20, and the pipe 18 through the fuel passage 13 a in the mover 5. Next, the fuel is injected from the fuel passage 16a of the guide plate 16 and the passage 9a of the nozzle through the passage 17a of the guide 17 and through the orifice 54 through the gap between the valve seat portion 11a and the seat surface 15a.

  On the other hand, when the current of the coil 6 is interrupted, the valve seat portion 11a of the mover 5 is brought into contact with the seat surface 15a by the force of the spring 19, and the valve is closed.

  Next, a method for connecting the nozzle 15 and the guide 17 will be described with reference to FIGS. 2 is a longitudinal sectional view showing a set state of the nozzle and guide and an assembling jig, FIG. 3 is a longitudinal sectional view showing a positioning state of the nozzle and guide, and FIG. 4 is a longitudinal sectional view showing a shearing state of the nozzle and guide. FIG. 5 is a longitudinal sectional view showing a combined state of the nozzle and the guide, FIG. 6 is a flowchart showing the connecting step of the nozzle and the guide, and FIG. 7 is an enlarged view showing the nozzle and the guide portion of the fuel injection valve after assembly.

  The purpose of the connection between the nozzle 15 and the guide 17 is that the valve body 11 is slidably held in the guide center hole 17b of the guide 17, and the valve seat portion 11a is in close contact with the seat surface 15a to seal the fuel. The center hole 17b and the sheet surface 15a need to be coupled to a concentricity of 10 μm or less, for example. Moreover, the hardness of the nozzle 15 is HRC52 or more, and the hardness of the guide 17 is Hv130-350.

  First, as shown in FIG. 2, the guide 17 is set inside the nozzle 15. This corresponds to the “work insertion” step of FIG.

  In this state, as shown in FIG. 3, the guide portion 31a of the mandrel 31 is inserted into the guide center hole 17b, the spherical portion 31b is brought into contact with the seat surface 15a, and the guide center hole 17b is centered with respect to the seat surface 15a. To do. This corresponds to the “centering positioning” step of FIG. At this time, for example, when there is a misalignment between the outer diameter of the guide 17 and the guide center hole 17b or the nozzle inner diameter 15b and the sheet surface 15a, a difference occurs between the clearance a and the clearance b.

  Next, the punch 32 is lowered and the punch 32 comes into contact with the guide 17. When the punch 32 is further lowered, the end portion of the guide 17 bites into the stepped portion A15c as shown in FIG. 4, and the corner portion of the guide 17 is sheared. At this time, the shearing portion 17c is fitted to the side surface of the stepped portion A15c without a gap. This corresponds to the steps of “pressing”, “shearing”, and “two-part fitting” in FIG. On the other hand, the sheared excess 17d is pushed into the escape portion 15d but does not come into contact with the inner diameter of the nozzle 15.

  When the punch 32 is continuously lowered, as shown in FIG. 5, the corner portion of the guide 17 bites into the step portion B15e, and the shearing portion 17c is in the direction of about 90 ° with respect to the pressing direction, that is, the side surface of the step portion A15c. It is plastically flowed to the side and pressed and bonded by self-tightening force (residual stress). This corresponds to the process of “joining at the fitting surface” in FIG.

  As shown in FIG. 7, after the assembly is finished, the valve body 11 is inserted into the portion where the mandrel 31 is inserted in FIG. 5, and the valve body 11 is guided by the guide 17.

  As described above, in a state where the sheet surface 15a and the guide center hole 17b are centered, the two parts are joined only by the fitting surface while the side surfaces of the shearing portion 17c and the stepped portion A15c are fitted without a gap. Therefore, the residual stress after the coupling becomes uniform over the entire circumference, and even after the mandrel 31 is removed, the guide 17 is not displaced and the coupling can be performed with high accuracy.

  FIG. 14 shows the result of an experiment in which components having an outer diameter of the guide 17 and the guide center hole 17b of 5 to 25 μm are connected. The concentricity of the sheet surface 15a after bonding and the guide center hole 17b is usually 14.1 μm on average in the conventional method as in Patent Document 2, but can be improved to 3 μm on average in this embodiment. The variation was greatly improved.

  In addition, it is desirable to insert the guide portion 31a of the mandrel 31 into the guide center hole 17b without a gap, and it is desirable to press-fit. Further, it is desirable that the outer diameter of the guide 17 and the nozzle inner diameter 15b do not contact each other except for the coupling portion, and the outer diameter of the guide 17 and the nozzle inner diameter 15b have a dimensional relationship for providing a clearance.

  In order to improve the bonding strength between the nozzle and the guide with respect to FIG. 5, a plastic flow portion may be provided on the side surface of the step portion A15c as shown in FIGS.

  In FIG. 8, the undercut portion 15f is provided on the side surface of the step portion A15c, and a plastic flow is generated when the corner portion of the guide 17 bites into the step portion B15e. It is a further improvement.

  The method of coupling is the same as that described in FIGS. 2 to 5, and the concentricity after coupling is also the same.

  In FIG. 9, a coupling groove 15g is provided instead of the undercut portion 15f.

  A plurality of coupling grooves 15g may be provided.

  By providing the undercut portion 15f and the coupling groove 15g, the coupling strength can be improved 2 to 5 times as compared with the coupling by the self-tightening force shown in FIG.

  A bearing structure according to a second embodiment of the present invention is shown in FIG.

  A bearing A52 and a bearing B53 are coaxially fixed in the holder 51, and two shafts 54 are supported.

  As shown in FIG. 11, the bearing structure is assembled by inserting a bearing B53 into an inner diameter portion 51a in a holder 51 to which a bearing A52 is fixed by press fitting or the like, and centering the bearing B53 while positioning the inner diameter of the bearing B53 with a mandrel 54. The part 54a is temporarily assembled on the basis of the inner diameter of the bearing A52.

  Next, the bearing B53 is pressed with the punch 55 in the same manner as in FIGS. 2 to 5, and the corner portion of the bearing B53 is fitted to the side surface while being sheared with the step portion A51b, and then is bitten into the step portion B51c. Then, the bearing B53 is coupled to the side surface of the stepped portion A51b serving as the fitting surface by the plastic flow at that time.

  FIG. 12 shows an example of welding instead of plastic bonding. Similarly to FIG. 11, the corner portion of the bearing B53 is fitted to the holder 51 by a required length while being sheared at the stepped portion A51b and welded at the fitting surface. Like the part 51d, it is joined by laser welding or the like.

  In order to prevent misalignment in the joining by welding, it is necessary to press-fit, but if it is press-fit, the mandrel 54 cannot be centered, so the coaxiality of the parts related to the joining must all be close to zero. .

  FIG. 13 shows an example of press-fitting and coupling. The lower inner diameter 51e (in the direction of the figure) of the step A51b is stepped (small diameter) as much as necessary to obtain the press-fitting strength, and the corner 51 of the bearing B53 is The step A51b is fitted while being subjected to a shearing process, and the bearing B53 is directly pressed into the inner diameter 51e to be press-fitted at the same time. In the case of press-fitting, the inner and outer diameters of the two parts must be precisely machined in order to strictly control the press-fitting allowance, but in this embodiment, it is only necessary to manage the step of the inner diameter of the holder 51. Variations in bond strength can be reduced, and parts processing and dimensional management can be easily and inexpensively performed.

  The assembly method of the bearing structure has been described above with reference to FIGS. 11 to 13. However, in any coupling method, the bearing B is centered on the bearing A with the mandrel and the step B is outside the bearing B. Since the diameter can be sheared and two parts can be fitted without gaps, there is no misalignment after joining regardless of the joining method, and the bearing A and bearing B are highly accurate with good coaxiality without being affected by the precision of the parts. Can be combined.

  As described above, the embodiment of the present invention has been specifically described. However, the present invention is not limited to this, and various modifications can be made within the scope of the inventive idea. For example, although the coaxiality has been described in the present invention, the same effect can be obtained with respect to positional accuracy, and positioning and assembly can be performed with high accuracy. Moreover, the surplus part which generate | occur | produces when carrying out a shearing process can also be removed by pushing in the bearing B deeply.

  Furthermore, in the second embodiment, the step portion is provided in the holder which is a hard part. However, when a bearing is used for the bearing, the holder may be softened to provide a step in the outer diameter of the hard bearing.

  According to the embodiment of the present invention, when two parts are joined with high positional accuracy, there is no influence of the single part precision of the parts, and the accuracy after joining can be maintained with the accuracy of positioning. Further, in the case of assembling with high positional accuracy by welding or press-fitting, there has been only means for improving the accuracy of a single product, but the embodiment according to the present invention can improve the accuracy during assembly. Therefore, it is possible to assemble with high accuracy even with an inexpensive part having low accuracy.

15 Nozzle 15a Sheet surface 15b Nozzle inner diameter 15c Step A
15d Escape part 15e Step B
15f Undercut portion 15g Coupling groove 17 Guide 17b Guide center hole 17c Shear portion 17d Extra thickness 31 Mandrel 31a Guide portion 31b Spherical surface portion 32 Punch

Claims (2)

In the joining method of two parts,
With each part that needs positioning positioned with a jig,
A fitting surface obtained by shearing a soft member at a corner provided on a hard member of the two parts and fitting the two parts between a side surface of the corner and the sheared surface. Have
Combined at the mating surface,
The hard member is an outer cylindrical part with a bottom having a plurality of stepped portions on the inner surface and a hole having a straight portion at the center of the inner bottom, and the inner member having a through hole at the center of the softer member Shaped parts,
In a state where the inner cylindrical part is placed on a plurality of steps of the outer cylindrical part, positioning guide pins are inserted into the through holes of the inner cylindrical part and the straight part of the hole of the outer cylindrical part. Until the inner cylindrical part and the outer cylindrical part are concentrically positioned, and by pressing the inner cylindrical part, a plurality of steps of the outer cylindrical part are inserted. The inner cylindrical part and the outer cylindrical part are coupled by self-tightening force that is a residual stress generated on a side surface of at least one of the plurality of stepped parts. The joining method of two parts. The method of connecting two parts according to claim 1,
An undercut portion is provided on a side surface of at least one step portion of the plurality of step portions of the outer cylindrical part, and the self-tightening force that is a residual stress generated in the undercut portion and the undercut portion are plastically flowed. A method of joining two parts, wherein the inner cylindrical part and the outer cylindrical part are joined by the soft member.