JP6807827B2 - Fuel injection valve - Google Patents

Description

The present invention relates to a fuel injection valve that injects fuel.

As a background technique in this technical field, a fuel injection valve described in Japanese Patent Application Laid-Open No. 2001-173804 (Patent Document 1) is known. In this fuel injection valve, the nozzle body and the valve needle are assembled, and when the valve seat and the abutting portion are in contact with each other in the closed state, the abutting portion side in the axial direction from the anti-contact portion side of the valve needle. A load is applied to the valve seat and the contact portion is bitten into the valve seat portion to deform the valve seat portion and the contact portion. A groove is formed in the valve seat due to the deformation of the valve seat and the contact portion, and the contact portion has an external shape corresponding to the shape of the groove. As a result, the shape of the groove portion and the external shape of the abutting portion are smoothed, no gap is generated between the valve seat portion and the abutting portion, and the valve seat portion and the abutting portion are sealed when the valve is closed. The degree improves (see summary).

Japanese Unexamined Patent Publication No. 2001-173804

In a fuel injection valve, a structure in which a valve body is a spherical surface and a valve seat surface is a conical surface (side surface of a truncated cone) is generally known. In such a structure, the contact state between the valve body and the valve seat approaches line contact, and the sticking force between the valve body and the valve seat due to the fuel oil film can be reduced. As a result, when the valve is opened, the valve body can be quickly started to move away from the valve seat. On the other hand, when the contact state between the valve body and the valve seat is line contact, the contact length (contact width) between the valve body and the valve seat in the direction in which the fuel flows becomes short, so that the oiltightness performance is improved. There is a problem in.

In the fuel injection valve of Patent Document 1, the shape of the groove on the valve seat surface and the external shape of the contact portion of the valve body are smoothed, and no gap is generated between the valve seat portion and the contact portion. It is easy to improve the density performance. On the other hand, the contact length (contact width) between the valve body and the valve seat becomes long, the contact state between the valve body and the valve seat becomes surface contact, and the sticking force between the valve body and the valve seat due to the fuel oil film is large. Become. As a result, it becomes difficult to quickly start the operation of the valve body moving away from the valve seat when the valve is opened.

An object of the present invention is to provide a fuel injection valve capable of improving oiltightness at a contact portion between a valve body and a valve seat and reducing the sticking force between the valve body and the valve seat due to a fuel oil film. To do.

In order to achieve the above object, the fuel injection valve of the present invention is
The valve seat surface , which has a truncated cone shape and a valve seat,
A valve body having a spherical portion having a radius R1 at a portion that comes into contact with the valve seat when the valve is closed.
Is formed, leaving the valve seat surface of the truncated cone shape during and between said downstream end of said upstream end in the middle of the upstream and downstream ends of the valve seat surface formed by a spherical surface portion having a radius R2 Circular groove and
With
The downstream side edge located on the downstream side of the annular groove is connected to the valve seat surface having a truncated cone shape.
The radius R2 is larger than the radius R1
The valve seat is provided on the downstream edge of the annular groove,
When the valve is closed, there is a gap formed between the valve body and the groove surface of the annular groove.

According to the present invention, there is provided a fuel injection valve capable of improving the oiltightness performance at the contact portion between the valve body and the valve seat and reducing the sticking force between the valve body and the valve seat due to the fuel oil film. can do.

It is sectional drawing which shows the cross section which is parallel to the central axis 1x, and includes the central axis 1x, about one Example of the fuel injection valve 1 which concerns on this invention. FIG. 5 is an enlarged cross-sectional view showing the vicinity of the mover 27 shown in FIG. FIG. 5 is an enlarged cross-sectional view showing the vicinity of the nozzle portion 8 shown in FIG. About one Example of the fuel injection valve 1 which concerns on this invention, it is a conceptual diagram which shows the cross section which is parallel to the central axis 1x, and includes the central axis 1x, in the vicinity of the contact part between a valve body 27c and a valve seat 15b. It is sectional drawing which shows the vicinity of the contact part between a valve body 27c and a valve seat 15b'in Comparative Example 1 with this invention. It is sectional drawing which shows the vicinity of the contact part of the valve body 27c and the valve seat 15b in the comparative example 2 with this invention. It is sectional drawing which shows the vicinity of the contact part of the valve body 27c and the valve seat 15b in the comparative example 3 with this invention. In the cross section shown in FIG. 4, it is a conceptual diagram explaining the relationship of the contact force between a valve body 27c and a valve seat 15b. It is sectional drawing of the internal combustion engine which mounted the fuel injection valve 1 which concerns on this invention.

Examples of the present invention will be described with reference to FIGS. 1 to 3.

The overall configuration of the fuel injection valve 1 will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a cross section of an embodiment of the fuel injection valve 1 according to the present invention, which is parallel to the central axis 1x and includes the central axis 1x. Reference numeral 1x indicates a central axis of the fuel injection valve 1. The axial center (valve axis) 27x of the mover 27 is arranged so as to coincide with the central axis 1x, and coincides with the central axis of the tubular body 5 and the valve seat member 15.

In FIG. 1, the upper end portion (upper end side) of the fuel injection valve 1 may be referred to as a base end portion (base end side), and the lower end portion (lower end side) may be referred to as a tip end portion (tip end side). The terms base end portion (base end side) and tip end portion (tip end side) are based on the fuel flow direction or the attachment structure of the fuel injection valve 1 to the fuel pipe. Further, the vertical relationship described in the present specification is based on FIG. 1, and has nothing to do with the vertical direction in the mounted state in which the fuel injection valve 1 is mounted on the internal combustion engine.

The fuel injection valve 1 is configured by a tubular body (cylindrical member) 5 made of a metal material so that a fuel flow path (fuel passage) 3 is substantially along the central axis 1x inside the tubular body (cylindrical member) 5. The tubular body 5 is made of a magnetic metal material such as stainless steel, and is formed in a stepped shape in the direction along the central axis 1x by press working such as deep drawing. As a result, the diameter of the one end side 5a of the tubular body 5 is larger than the diameter of the other end side 5b.

A fuel supply port 2 is provided at the base end portion of the tubular body 5, and a fuel filter 13 for removing foreign matter mixed in the fuel is attached to the fuel supply port 2.

The base end portion of the tubular body 5 is formed with a collar portion (diameter expansion portion) 5d bent so as to expand in the radial direction, and the collar portion 5d and the base end side end portion 47a of the cover 47 are formed. The O-ring 11 is arranged in the annular recess (annular groove portion) 4 formed by.

At the tip of the tubular body 5, a valve portion 7 including a valve body 27c and a valve seat member 15 is configured. The valve seat member 15 is press-fitted into the inner peripheral side of the tip end portion of the tubular body 5, and is fixed to the tubular body 5 by laser welding 19. The laser welding 19 is carried out from the outer peripheral side of the tubular body 5 to the entire circumference.

A nozzle plate 21n is fixed to the valve seat member 15, and the valve seat member 15 and the nozzle plate 21n form a nozzle portion 8. The valve seat member 15 and the nozzle plate 21n are assembled to the tip end side of the tubular body 5 by inserting and fixing the valve seat member 15 into the inner peripheral surface 5g (see FIG. 3) of the tubular body 5. There is.

The tubular body 5 of this embodiment is composed of one member from the portion where the fuel supply port 2 is provided to the portion where the valve seat member 15 and the nozzle plate 21n are fixed. The tip end side portion of the tubular body 5 constitutes a nozzle holder that holds the nozzle portion 8. In this embodiment, the nozzle holder is composed of one member together with the proximal end side portion of the tubular body 5.

A driving unit 9 for driving the valve body 27c is arranged in the middle portion of the tubular body 5. The drive unit 9 is composed of an electromagnetic actuator (electromagnetic drive unit).

Specifically, the drive unit 9 has a fixed iron core (fixed core) 25 fixed to the inside (inner peripheral side) of the tubular body 5 and a tip side to the fixed iron core 25 inside the tubular body 5. An arranged mover (movable member) 27, an electromagnetic coil 29 extrapolated on the outer peripheral side of the tubular body 5, and a yoke 33 covering the electromagnetic coil 29 on the outer peripheral side of the electromagnetic coil 29 are provided.

The mover 27 is configured by integrally providing a valve body 27c, a rod portion (connection portion) 27b, and a movable iron core 27a. The mover 27 has a movable iron core (movable core) 27a facing the fixed iron core 25 on the base end side, and is assembled so as to be movable in the direction along the central axis 1x. Further, the electromagnetic coil 29 is arranged on the outer peripheral side (outward in the radial direction) at a position where the fixed iron core 25 and the movable iron core 27a face each other via the minute gap δ1. As a result, the movable iron core 27a and the fixed iron core 25 drive the valve body 27c by exerting an electromagnetic force between them.

A mover 27 and a fixed iron core 25 are housed inside the tubular body 5, and the tubular body 5 abuts on the fixed iron core 25 and faces the outer peripheral surface of the movable iron core 27a to face the movable iron core 27a and the fixed iron core 27a. It constitutes a housing that surrounds 25. That is, the tubular body 5 includes a movable iron core 27a and a fixed iron core 25.

The movable iron core 27a, the fixed iron core 25, and the yoke 33 form a closed magnetic path through which the magnetic flux generated by energizing the electromagnetic coil 29 flows. The magnetic flux passes through the minute gap δ1, but in order to reduce the leakage flux flowing through the tubular body 5 at the minute gap δ1, a non-magnetic part or a tubular body is located at a position corresponding to the minute gap δ1 of the tubular body 5. A weak magnetic part 5c that is weaker than the other parts of 5 is provided. Hereinafter, the non-magnetic portion or the weak magnetic portion 5c will be referred to simply as the non-magnetic portion 5c for description.

The electromagnetic coil 29 is wound around a bobbin 31 formed of a resin material in a tubular shape, and is extrapolated to the outer peripheral side of the tubular body 5. The electromagnetic coil 29 is electrically connected to the terminal 43 provided on the connector 41. An external drive circuit (not shown) is connected to the connector 41, and a drive current is applied to the electromagnetic coil 29 via the terminal 43.

The fixed iron core 25 is made of a magnetic metal material. The fixed iron core 25 is formed in a tubular shape and has a through hole 25a penetrating the central portion in the direction along the central axis 1x. The through hole 25a constitutes a fuel passage (upstream fuel passage) 3 on the upstream side of the movable iron core 27a. The fixed iron core 25 is press-fitted and fixed to the base end side of the small diameter portion 5b of the tubular body 5, and is located at the intermediate portion of the tubular body 5. Since the large diameter portion 5a is provided on the base end side of the small diameter portion 5b, the fixed iron core 25 can be easily assembled. The fixed iron core 25 may be fixed to the tubular body 5 by welding, or may be fixed to the tubular body 5 by using welding and press fitting together.

The movable iron core 27a is an annular member. The valve body 27c is a member that comes into contact with the valve seat 15b (see FIG. 3). The valve seat 15b and the valve body 27c cooperate to open and close the fuel passage on the upstream side of the fuel injection hole 51. The rod portion 27b has an elongated cylindrical shape, and is a connecting portion that connects the movable iron core 27a and the valve body 27c. The movable iron core 27a is a member connected to the valve body 27c and for driving the valve body 27c in the on-off valve direction by a magnetic attraction force acting between the movable iron core 27a and the fixed iron core 25.

In this embodiment, the movable iron core 27a and the rod portion 27b are fixed, but the movable iron core 27a and the rod portion 27b may be connected so as to be relatively displaceable.

In this embodiment, the rod portion 27b and the valve body 27c are made of separate members, and the valve body 27c is fixed to the rod portion 27b. The rod portion 27b and the valve body 27c are fixed by press fitting or welding. The rod portion 27b and the valve body 27c may be integrated by one member.

The rod portion 27b has a cylindrical shape, and the upper end of the rod portion 27b opens to the lower end portion of the movable iron core 27a and has a hole 27ba extending in the axial direction. The rod portion 27b is formed with a communication hole (opening) 27bo that communicates the inside (inner circumference side) and the outside (outer circumference side). A fuel chamber 37 is formed between the outer peripheral surface of the rod portion 27b and the inner peripheral surface of the tubular body 5.

A spring member 39 is provided in the through hole 25a of the fixed iron core 25. In this embodiment, the spring member 39 is composed of a coil spring. Hereinafter, it will be referred to as a coil spring 39 and will be described.

One end of the coil spring 39 is in contact with a spring seat 27ag provided inside the movable iron core 27a. The other end of the coil spring 39 is in contact with the adjuster 35 arranged inside the through hole 25a of the fixed iron core 25. The coil spring 39 is arranged in a compressed state between the spring seat 27ag provided on the movable iron core 27a and the lower end (tip side end face) of the adjuster (adjuster) 35.

The coil spring 39 functions as an urging member that urges the mover 27 in the direction in which the valve body 27c abuts on the valve seat 15b (valve closing direction). By adjusting the position of the adjuster 35 in the direction along the central axis 1x in the through hole 25a, the urging force of the mover 27 (that is, the valve body 27c) by the coil spring 39 is adjusted.

The adjuster 35 has a fuel flow path 3 that penetrates the central portion in a direction along the central axis 1x. The fuel supplied from the fuel supply port 2 flows through the fuel flow path 3 of the adjuster 35, then flows into the fuel flow path 3 at the tip end side of the through hole 25a of the fixed iron core 25, and is configured in the mover 27. It flows into the fuel flow path 3.

The yoke 33 is made of a magnetic metal material and also serves as a housing for the fuel injection valve 1. The yoke 33 is formed in a stepped tubular shape having a large diameter portion 33a and a small diameter portion 33b. The large diameter portion 33a covers the outer periphery of the electromagnetic coil 29 and has a cylindrical shape, and a small diameter portion 33b having a diameter smaller than that of the large diameter portion 33a is formed on the tip end side of the large diameter portion 33a. The small diameter portion 33b is press-fitted or inserted into the outer periphery of the small diameter portion 5b of the tubular body 5. As a result, the inner peripheral surface of the small diameter portion 33b is in close contact with the outer peripheral surface of the tubular body 5. At this time, at least a part of the inner peripheral surface of the small diameter portion 33b faces the outer peripheral surface of the movable iron core 27a via the tubular body 5, and the magnetic resistance of the magnetic path formed in the facing portion is reduced. ing.

An annular recess 33c is formed along the circumferential direction on the outer peripheral surface of the distal end portion of the yoke 33. In the thin-walled portion formed on the bottom surface of the annular recess 33c, the yoke 33 and the tubular body 5 are joined by laser welding 24 over the entire circumference.

A cylindrical protector 49 having a flange portion 49a is extrapolated to the tip end portion of the tubular body 5, and the tip end portion of the tubular body 5 is protected by the protector 49. The protector 49 covers the laser welded portion 24 of the yoke 33.

An annular groove 34 is formed by the flange portion 49a of the protector 49, the small diameter portion 33b of the yoke 33, and the stepped surface between the large diameter portion 33a and the small diameter portion 33b of the yoke 33, and the O-ring 46 is extrapolated to the annular groove 34. Has been done. When the fuel injection valve 1 is attached to the internal combustion engine, the O-ring 46 is liquid-tight and airtight between the inner peripheral surface of the insertion port formed on the internal combustion engine side and the outer peripheral surface of the small diameter portion 33b of the yoke 33. Functions as a seal to secure.

The resin cover 47 is molded in the range from the intermediate portion of the fuel injection valve 1 to the vicinity of the proximal end side end portion. The tip end side of the resin cover 47 covers a part of the base end side of the large diameter portion 33a of the yoke 33. Further, the connector 41 is integrally formed of the resin forming the resin cover 47.

The configuration in the vicinity of the mover 27 will be described in detail with reference to FIG. FIG. 2 is an enlarged cross-sectional view showing the vicinity of the mover 27 shown in FIG.

In this embodiment, the movable iron core 27a and the rod portion 27b are integrally formed by one member. A recess 27aa recessed toward the lower end is formed in the central portion of the upper end surface (upper end portion) 27ab of the movable iron core 27a. A spring seat is formed in the bottom portion 27ag of the recess 27aa, and one end (tip side end portion) of the coil spring 39 is supported by the bottom portion 27ag. Further, an opening 27af communicating with the inside of the hole 27ba of the rod portion 27b is formed in the bottom portion 27ag of the recess 27aa. The opening 27af constitutes a fuel passage through which the fuel that has flowed into the space 27ai in the recess 27aa from the through hole 25a of the fixed iron core 25 flows into the space 27bi inside the hole 27ba of the rod portion 27b.

In this embodiment, the rod portion 27b and the movable iron core 27a are composed of one member, but those composed of separate members may be integrally assembled.

The upper end surface (base end side end surface) 27ab of the movable iron core 27a is an end surface located on the fixed iron core 25 side, and faces the lower end surface (tip end side end surface) 25b of the fixed iron core 25. The end surface 27ak of the movable iron core 27a on the opposite side of the upper end surface 27ab is an end surface located on the tip end side (nozzle side) of the fuel injection valve 1, and is hereinafter referred to as a lower end surface (lower end portion).

The upper end surface 27ab of the movable iron core 27a and the lower end surface 25b of the fixed iron core 25 form a magnetic attraction surface on which a magnetic attraction force acts on each other.

A non-magnetic portion 5c is provided on the outer peripheral side of the magnetic attraction surface. In this embodiment, the non-magnetic portion 5c is composed of an annular recess 5h formed on the outer peripheral surface of the tubular body 5. The annular recess 5h constitutes the thin portion 5i by thinning the portion corresponding to the non-magnetic portion 5c. That is, the annular recess 5h forms a thin thin portion 5i in the circumferential direction at a portion of the tubular body 5 located on the outer peripheral portion of the facing portion where the movable iron core 27a and the fixed iron core 25 face each other. The thin portion 5i has a thinner wall thickness (thickness dimension) than the other portions of the tubular body 5, and increases the magnetic reluctance of the magnetic flux passing therethrough, making it difficult for the magnetic flux to flow. The non-magnetic portion 5c may be configured by making the wall thickness of the tubular body 5 the same as that of other portions and performing a demagnetization treatment.

A sliding portion that slides on the inner peripheral surface 5e of the tubular body 5 is formed on the outer peripheral surface 27ac of the movable iron core 27a. As the sliding portion, a convex portion 27al that projects outward in the radial direction is provided on the outer peripheral surface 27ac. The inner peripheral surface 5e constitutes an upstream guide portion 50B to which the convex portion 27al of the movable iron core 27a is in sliding contact.

On the other hand, the valve seat member 15 is configured with a guide surface 15c (see FIG. 3) with which the spherical surface 27cc of the valve body 27c is in sliding contact, and the guide portion in which the guide surface 15c guides the spherical surface 27cc constitutes the downstream guide portion 50A. .. As a result, the mover 27 is guided by two points, the upstream side guide portion 50B and the downstream side guide portion 50A, and reciprocates in the direction along the central axis 1x (opening / closing valve direction).

The rod portion 27b is formed with an opening (communication hole) 27bo that communicates the inside (hole 27ba) and the outside (fuel chamber 37). The communication hole 27bo constitutes a fuel passage that communicates the inside and the outside of the rod portion 27b. As a result, the fuel in the through hole 25a of the fixed iron core 25 flows into the fuel chamber 37 through the hole 27ba and the communication hole 27bo.

Next, the configuration of the nozzle portion 8 will be described in detail with reference to FIG. FIG. 3 is an enlarged cross-sectional view showing the vicinity of the nozzle portion 8 shown in FIG.

The valve seat member 15 is formed with through holes 15d, 15c, 15v, 15e penetrating in the direction along the central axis 1x.

In the middle of the through holes 15d, 15c, 15v, 15e, a conical surface (side surface of the truncated cone) 15v whose diameter is reduced toward the downstream side is formed. A valve seat 15b is formed on the conical surface 15v, and the valve body 27c is brought into contact with the valve seat 15b to open and close the fuel passage. The conical surface 15v on which the valve seat 15b is formed may be referred to as a valve seat surface.

The abutting portion where the valve seat 15b and the valve body 27c are in contact with each other constitutes a sealing portion that seals the fuel when the valve is closed. The contact portion on the valve seat 15b side may be referred to as a valve seat side (fixed valve side) seat portion, and the contact portion on the valve body 27c side may be referred to as a valve body side (movable valve side) seat portion.

The hole portions 15d, 15c, 15v above the conical surface 15v in the through holes 15d, 15c, 15v, 15e form a valve body accommodating hole for accommodating the valve body 27c. Guide surfaces 15c are formed on the inner peripheral surfaces of the valve body accommodating holes 15d, 15c, and 15v to guide the valve body 27c in the direction along the central axis 1x. The guide surface 15c constitutes the downstream guide surface 50A located on the downstream side of the two guide surfaces that guide the mover 27.

On the upstream side of the guide surface 15c, a diameter-expanded portion 15d that expands in diameter toward the upstream side is formed. The enlarged diameter portion 15d is located at the upper end portion of the through holes 15d, 15c, 15v, 15e, and constitutes a proximal end side opening that opens toward the fuel chamber 37. The enlarged diameter portion 15d is configured as a tapered surface whose diameter is reduced from the proximal end side toward the distal end side. The inclination angle of the tapered surface 15d is steeper than the inclination angle of the valve seat surface 15v described later.

The lower ends of the valve body accommodating holes 15d, 15c, 15v are connected to the fuel introduction holes 15e, and the lower end surface of the fuel introduction holes 15e opens to the tip surface 15t of the valve seat member 15. That is, the fuel introduction hole 15e constitutes a tip-side opening of the through holes 15d, 15c, 15v, 15e.

A nozzle plate 21n is attached to the tip surface 15t of the valve seat member 15. The nozzle plate 21n is fixed to the valve seat member 15 by laser welding 23. The laser welded portion 23 goes around the injection hole forming region in which the fuel injection hole 51 is formed so as to surround the injection hole forming region.

Further, the nozzle plate 21n is made of a plate-shaped member (flat plate) having a uniform plate thickness, and a protruding portion 21na is formed in the central portion so as to protrude outward. The projecting portion 21na is formed of a curved surface (for example, a spherical surface). A fuel chamber 21a is formed inside the protruding portion 21na. The fuel chamber 21a communicates with the fuel introduction hole 15e formed in the valve seat member 15, and fuel is supplied to the fuel chamber 21a through the fuel introduction hole 15e.

A plurality of fuel injection holes 51 are formed in the projecting portion 21na. The form of the fuel injection hole 51 is not particularly limited. A swivel chamber that applies a swivel force to the fuel may be provided on the upstream side of the fuel injection hole 51. The central axis 51a of the fuel injection hole may be parallel to the central axis 1x of the fuel injection valve or may be inclined. Further, the configuration may be such that there is no protruding portion 21na.

The fuel injection unit 21 that determines the form of fuel spray is composed of a nozzle plate 21n. The valve seat member 15 and the fuel injection unit 21 form a nozzle unit 8 for injecting fuel. The valve body 27c may be regarded as a part of the components constituting the nozzle portion 8.

Further, in this embodiment, the valve body 27c uses a ball valve forming a spherical shape. For this reason, a plurality of notched surfaces 27ca are provided at portions of the valve body 27c facing the guide surface 15c at intervals in the circumferential direction, and the notched surfaces 27ca provide a fuel passage for supplying fuel to the seat portion. It is configured. The valve body 27c can also be composed of a valve body other than the ball valve. For example, a needle valve may be used.

The valve seat member 15 is press-fitted into the inner peripheral surface 5g of the tip end portion of the tubular body 5, and then welded to and fixed to the tubular body 5 by the welded portion 19.

Next, the configuration of the press-fitting portion of the valve seat member 15 will be described with reference to FIG. FIG. 4 is a concept showing a cross section of an embodiment of the fuel injection valve 1 according to the present invention, which is parallel to the central axis 1x and includes the central axis 1x in the vicinity of the contact portion between the valve body 27c and the valve seat 15b. It is a figure.

In FIG. 4, the valve body 27c shown by the solid line is a valve body in a closed state (when the valve is closed). O27c1 is the central position of the valve body 27c when the valve is closed. St is the position of the contact portion (seat portion) between the valve body 27c and the valve seat surface 15v when the valve is closed. The alternate long and short dash line indicates the valve body 27c in the opened state (when the valve is opened). O27c2 is the central position of the valve body 27c when the valve is opened. The broken line drawn in the portion of the groove 15g along the valve seat surface 15v indicates the conical surface (side surface of the truncated cone) of the valve seat surface 15v when the groove 15g is not provided.

Further, in FIG. 4, when the groove 15g is not provided, the valve body 27c in contact with the conical surface of the valve seat surface 15v is shown by a dotted line. When the groove 15g is not provided, the valve body 27c shown by the dotted line is in contact with the conical surface shown by the broken line at the contact portion (seat portion) St', and the valve is closed. The valve body 27c shown by the dotted line has its center at the position indicated by O27c3.

In this embodiment, a groove 15g is formed on the valve seat surface 15v. The groove 15g constitutes an annular groove formed in an annular shape in the circumferential direction centered on the central axis 1x. On the cross section shown in FIG. 4, the annular groove 15g forms an arc surface (valve seat side arc surface). The arc surface on the valve seat side is composed of a part of a spherical surface having a radius R2 centered on O15 g. That is, the annular groove 15g is composed of a spherical portion having a radius R2 formed on the valve seat surface 15v.

The portion of the valve body 27c that comes into contact with the valve seat 15b is formed in a spherical shape. That is, the valve body 27c has a spherical portion having a radius R1 at a portion that comes into contact with the valve seat 15b when the valve is closed. Therefore, on the cross section shown in FIG. 4, the valve body 27c has an arc surface (arc surface on the valve body side) formed at a portion that comes into contact with the valve seat 15b. The arc surface on the valve body side is composed of a spherical surface having a radius R1. In other words, the valve body 27c has a curved portion at a portion that comes into contact with the valve seat 15b, and the radius of curvature of the circle of curvature formed by this curved portion is R1. Since the valve body 27c is formed of a sphere in this embodiment, the valve body 27c is drawn as a circle having a constant radius of curvature R1 on the outer circumference in the cross section shown in FIG.

In this embodiment, the radius R2 of the arc surface on the valve seat side is larger than the radius R1 of the arc surface on the valve body side, and there is a relationship of R2> R1. The valve seat 15b is formed at the downstream edge of the annular groove 15g in the direction in which fuel flows. That is, the valve seat 15b is formed at the edge where the valve seat surface 15v and the groove surface of the annular groove 15g intersect. In this embodiment, in the seat portion St where the valve body 27c abuts on the valve seat 15b, the contact state between the valve body 27c and the valve seat 15b is theoretically a linear contact.

The gap Gp between the surface of the valve body 27c and the groove surface of the annular groove 15g has a minute size over the range of W15g. The range W15g in which the minute gap Gp is formed is upstream of the seat portion St in the direction in which the fuel flows. The oiltightness can be improved by providing the minute gap region W15g on the upstream side of the sheet portion St.

In reality, the seat portion St in which the valve body 27c and the valve seat 15b come into contact with each other has a minute contact length (contact width) in the direction in which the fuel flows. For example, the first surface on which the valve body side seat portion is formed and the second surface on which the valve seat side seat portion is formed are slightly deformed due to repeated collisions accompanying the on-off valve operation, and the valve body 27c and the valve body 27c The contact width with the valve seat 15b may increase. Further, due to the limit of processing accuracy, the contact width between the valve body 27c and the valve seat 15b may be larger than that in the case of theoretical line contact. However, in this embodiment, unlike Patent Document 1, a particularly large load is applied to the valve body 27c to deform the contact portions of the valve seat surface 15v and the valve body 27c.

That is, the deformation of the contact portion that occurs in this embodiment is caused by the urging force (load) of the spring 39. Therefore, the amount of deformation caused by the limit of processing accuracy and aging is small, and the contact state between the valve body 27c and the valve seat 15b is substantially maintained in the line contact state. The groove width W15g is preferably set so that the contact width generated by the limit of processing accuracy or aging is 30% or less of the groove width W15g, and more preferably 10% or less.

For the above reasons, in the present specification and the claims, the contact state between the first surface constituting the valve body side seat portion and the second surface constituting the valve seat side seat portion is theoretically determined. It will be described as line contact based on the contact state described.

In this embodiment, a gap Gp is formed between the surface (first surface) of the valve body 27c and the groove surface (second surface) of the annular groove 15g on the upstream side of the seat portion St when the valve is closed. Will be done. In the gap Gp, the distance (gap dimension) between the valve body 27c and the annular groove 15g facing each other becomes a minute size over the range of W15g.

In the gap Gp, the gap size at the time of valve closing gradually increases from the downstream side edge portion of the annular groove 15g toward the upstream side edge portion. The gap dimension of the gap Gp (distance between the first surface and the second surface) is the rate of change when moving away from the seat portion St toward the upstream side along the generatrix direction of the conical surface constituting the valve seat surface 15v. (Expansion rate) is smaller than the rate of change when there is no annular groove 15 g (distance between the valve body shown by the dotted line and the valve seat surface shown by the broken line). That is, in this embodiment, the rate of increase in the dimension of the gap Gp when separated from the seat portion St along the generatrix direction of the conical surface is suppressed to be smaller than that in the case where the annular groove 15 g is not provided. Therefore, the minute gap Gp can be provided in a long range W15g along the generatrix direction of the conical surface 15v.

In this embodiment, the radius R2 of the arc surface on the valve seat side is larger than the radius R1 of the arc surface on the valve body side. In this case, in R2 and R1, when the valve is closed, the valve body 27c and the valve seat surface 15v (valve seat 15b) are in contact with each other at the seat portion St, and a gap Gp is formed on the upstream side of the seat portion St. In addition, it has a substantial magnitude relationship.

In this embodiment, as shown in FIG. 4, the center O15g of the spherical surface constituting the annular groove 15g is located on the proximal end side of the center position O27c1 of the valve body 27c at the time of valve closing, and the valve body at the time of valve opening. It is located on the tip side of the center position O27c2 of 27c. Further, the center O15g is located closer to the base end side than the center position O27c3 of the valve body 27c (indicated by the dotted line) in the state of being in contact with the conical surface (indicated by the broken line) when the groove 15g is not provided. By setting R2 so as to satisfy such a positional relationship, a line contact state between the valve body 27c and the valve seat 15b can be realized.

Next, a comparative example with the present invention will be described with reference to FIGS. 5 to 7. The same reference numerals are given to the same configurations as those of the examples according to the present invention, and the description thereof will be omitted.

FIG. 5 is a cross-sectional view showing the vicinity of the contact portion between the valve body 27c and the valve seat 15b'in Comparative Example 1 with the present invention.

FIG. 5 shows a state in which the valve body 27c is closed. O27c1'indicates the position of the center of the valve body 27c when the valve is closed. O27c1'corresponds to O27c3 in FIG.

In Comparative Example 1, the valve body 17c is a spherical surface, and the valve seat surface 15v'is a simple conical surface (side surface of a truncated cone). That is, in Comparative Example 1, the groove 15g according to the present invention is not provided on the valve seat surface 15v'. In such a structure, the contact state between the valve body 27c and the valve seat 15b'is theoretically linear contact, and the sticking force between the valve body 27c and the valve seat 15b' due to the fuel oil film can be reduced. As a result, when the valve is opened, the valve body can be quickly started to move away from the valve seat. On the other hand, in the seat portion St (corresponding to St'in FIG. 4), the contact length (contact width) between the valve body 17c and the valve seat 15b'in the direction in which the fuel flows is shortened, so that the oiltightness is improved. There is a problem in improvement.

FIG. 6 is a cross-sectional view showing the vicinity of the contact portion between the valve body 27c and the valve seat 15b in Comparative Example 2 with the present invention.

FIG. 6 shows a state in which the valve body 27c is closed. O27c1 ″ indicates the position of the center of the valve body 27c when the valve is closed.

In Comparative Example 2, a groove 15g'is provided in the valve seat surface 15v ″, and the valve body 27c and the valve seat surface 15v ″ are in contact with each other within a range of length L15b in the generatrix direction of the conical surface. That is, the valve seat 15b ″ has a spherical shape, and the seat portion St is configured in the range of the length L15b.

In Comparative Example 2, the contact length between the valve body 27c and the valve seat surface 15v ″ is long (the width of the seat portion is wide), and the oiltightness performance can be improved. On the other hand, the sticking force between the valve body 27c and the valve seat 15b'due to the fuel oil film increases.

When the entire surface of the groove 15g'is brought into contact with the valve body 27c, the radius of curvature R2'of the groove surface needs to be slightly larger than the radius R1 of the valve body 27c. However, since the entire surface of the groove 15g'is brought into contact with the valve body 27c, the radius of curvature R2'of the groove 15g'and the radius R1 of the valve body 27c can be regarded as substantially equal.

The groove 15g'in Comparative Example 2 can be formed by applying a load larger than the load applied by the spring 39 to the valve body 27c.

FIG. 7 is a cross-sectional view showing the vicinity of the contact portion between the valve body 27c and the valve seat 15b in Comparative Example 3 with the present invention.

In Comparative Example 3, the valve body 27c'has a tapered surface 27c'1 that abuts on the valve seat surface 15v' formed of a conical surface (side surface of a truncated cone). The tapered surface 27c'1 abuts on the valve seat surface 15v'within a range of length L15b in the generatrix direction of the conical surface. That is, the valve seat 15b "" is tapered, and the seat portion St is configured in the range of the length L15b.

In Comparative Example 3, similarly to Comparative Example 2, the contact length between the valve body 27c'and the valve seat surface 15v' is long (the width of the seat portion is wide), and the oiltightness performance can be improved. On the other hand, the sticking force between the valve body 27c and the valve seat 15b ″ by the fuel oil film increases.

Next, the action and effect of the examples according to the present invention will be described.

In this embodiment, in the seat portion St, the contact state between the valve body 27c and the valve seat 15b is linear contact. Therefore, as compared with Comparative Examples 2 and 3, the sticking force due to the fuel oil film generated between the valve body 27c and the valve seat 15b can be suppressed. As a result, the delay in the valve opening operation of the valve body 27c is suppressed, and the fuel injection accuracy is improved. Further, the time interval at which the valve body 27c opens and closes can be shortened, and a small amount of fuel can be injected.

Further, the distance (gap size) between the valve body 27c and the annular groove 15g facing each other over the range of W15g is smaller than that in the case of Comparative Example 1. The oil-tightness performance can be improved by the minute gap Gp.

Further, in this embodiment, the seat portion St in which the valve body 27c abuts on the valve seat surface 15v is formed at the edge portion where the valve seat surface 15v and the groove surface of the annular groove 15g intersect. That is, the valve seat 15b with which the valve body 27c abuts is formed at a corner portion formed on the valve seat surface 15v by the annular groove 15g. Therefore, the valve body 27c is seated at the corner of the valve seat surface 15v, and the surface pressure when the valve body 27c comes into contact with the valve seat surface 15v increases. As a result, the oiltightness of the seat portion St is improved.

Next, with reference to FIG. 8, the contact force (surface pressure) between the valve body 27c and the valve seat 15b will be described in more detail. FIG. 8 is a conceptual diagram illustrating the relationship of the contact force between the valve body 27c and the valve seat 15b in the cross section shown in FIG.

The valve body 27c is urged by the load of P1 in the direction along the central axis 1x by the urging force of the spring 39 and the urging force of the fuel pressure. In this case, the valve body 27c is pressed at the edge of the annular groove 15g in the direction perpendicular to the arc C of the annular groove 15g by the load (surface pressure) of P2.

When there is no annular groove 15g and the valve body 27c abuts on the conical surface of the valve seat surface 15v (in the case of Comparative Example 1), the valve body 27c has P2'in the direction perpendicular to the conical surface of the valve seat surface 15v. It is pressed by a load (surface pressure).

A relationship of P2> P2'establishes between P2 and P2'. Therefore, in this embodiment, when the valve body 27c is urged with a constant urging force, the valve body 27c can be pressed in the direction perpendicular to the valve seat 15b with a larger load. As a result, the surface pressure of the valve body 27c can be increased and the oiltightness can be improved.

In this embodiment, the valve seat 15b (seat portion St) is located on the downstream side with respect to the virtual position where the valve seat (seat portion) St'is formed when there is no annular groove 15g. Therefore, the length of the seat portion St in the circumferential direction can be shortened, and if a sufficient fuel flow rate can be secured, it is advantageous for improving the oiltightness performance.

In this embodiment, the surface of the valve body 27c and the annular groove 15 have an arc shape in the cross section shown in FIG. That is, both are composed of a sphere or a part of the sphere. If the seat portion St and the gap Gp described above can be configured, the surface of the valve body 27c and the annular groove 15 may have a shape other than the arc shape. For example, a shape such as an ellipse can be applied. However, in this embodiment, it is preferable to have an arc shape in order to reliably form the seat portion St and the gap Gp.

An internal combustion engine equipped with a fuel injection valve according to the present invention will be described with reference to FIG. FIG. 9 is a cross-sectional view of an internal combustion engine equipped with a fuel injection valve 1.

A cylinder 102 is formed in the engine block 101 of the internal combustion engine 100, and an intake port 103 and an exhaust port 104 are provided at the top of the cylinder 102. The intake port 103 is provided with an intake valve 105 for opening and closing the intake port 103, and the exhaust port 104 is provided with an exhaust valve 106 for opening and closing the exhaust port 104. An intake pipe 108 is connected to an inlet side end 107a of an intake flow path 107 formed in the engine block 101 and communicating with the intake port 103.

A fuel pipe 110 is connected to the fuel supply port 2 (see FIG. 1) of the fuel injection valve 1.

A mounting portion 109 of the fuel injection valve 1 is formed in the intake pipe 108, and an insertion port 109a into which the fuel injection valve 1 is inserted is formed in the mounting portion 109. The insertion port 109a penetrates to the inner wall surface (intake flow path) of the intake pipe 108, and the fuel injected from the fuel injection valve 1 inserted into the insertion port 109a is injected into the intake flow path. In the case of two-way spraying, each fuel spray is directed toward each intake port 103 (intake valve 105) for an internal combustion engine in which two intake ports 103 are provided in the engine block 101.

The present invention is not limited to the above-described embodiment, and some configurations can be deleted or other configurations not described can be added.

1 ... Fuel injection valve, 1x ... Central axis, 15 ... Valve seat member, 15b ... Valve seat, 15g ... Groove (annular groove), 27c ... Valve body, 27x ... Axial direction of mover 27, O27c1 ... When valve is closed Center position of valve body 27c, O27c2 ... Center position of valve body 27c at the time of valve opening, O27c3 ... Center position of valve body 27c in contact with conical surface of valve seat surface 15v when groove 15g is not provided, O15g ... The center of the spherical surface constituting the annular groove 15g, R1 ... the radius of the valve body 27c, R2 ... the radius of the annular groove 15g, St ... the seat portion.

Claims (7)

The valve seat surface , which has a truncated cone shape and a valve seat,
A valve body having a spherical portion having a radius R1 at a portion that comes into contact with the valve seat when the valve is closed.
Is formed, leaving the valve seat surface of the truncated cone shape during and between said downstream end of said upstream end in the middle of the upstream and downstream ends of the valve seat surface formed by a spherical surface portion having a radius R2 Circular groove and
With
The downstream side edge located on the downstream side of the annular groove is connected to the valve seat surface having a truncated cone shape.
The radius R2 is larger than the radius R1
The valve seat is provided on the downstream edge of the annular groove,
A fuel injection valve having a gap formed between the valve body and the groove surface of the annular groove when the valve is closed. In the fuel injection valve according to claim 1 ,
Before SL gap, the fuel injection valve provided on the upstream side with respect to the downstream edge where the valve seat is provided. In the fuel injection valve according to claim 2,
The gap is a fuel injection valve in which the size of the gap when the valve is closed gradually increases from the downstream side edge portion of the annular groove toward the upstream side edge portion. In the fuel injection valve according to claim 3,
The center of the spherical portion forming the annular groove is a fuel injection valve located on the base end side of the fuel injection valve with respect to the center position of the spherical portion of the valve body when the valve is closed. In the fuel injection valve according to claim 4,
The center of the spherical portion forming the annular groove is a fuel injection valve located on the tip end side of the fuel injection valve with respect to the center position of the spherical portion of the valve body when the valve is opened. In the fuel injection valve according to claim 5,
The valve seat surface is composed of a conical surface.
The size of the gap is a fuel injection valve in which the rate of increase when moving upstream from the valve seat along the generatrix of the conical surface is smaller than the rate of increase when there is no annular groove. In the fuel injection valve according to claim 6,
The valve seat is a fuel injection valve located on the downstream side of a virtual position where the valve seat is formed when there is no annular groove.

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