阅读说明：本技术 燃料喷射阀 (Fuel injection valve ) 是由 久芳茂生 山崎昭宏 斋藤贵博 长冈正树 于 2018-03-26 设计创作，主要内容包括：具备驱动阀芯的可动铁芯(27a)和固定铁芯(25)、以及内部包含可动铁芯(27a)和固定铁芯(25)的筒状体(5)。筒状体(5)具有环状槽部(5h),该环状槽部(5h)在可动铁芯(27a)与固定铁芯(25)的相对部的外周侧沿周向形成壁厚较薄的薄壁部(5i)。薄壁部(5i)具有曲线部(5x),在与燃料喷射阀的中心轴线(1x)平行且包含中心轴线(1x)的截面中,该曲线部(5x)在沿着中心轴线(1x)的方向的两端部通过曲线将环状槽部(5h)的侧缘(5h1,5h2)与底部(与最薄壁部(5i0)对应的部分)连接。该曲线部(5x)在沿着中心轴线(1x)的方向上从侧缘(5h1,5h2)以比环状槽部(5h)的槽深尺寸(d)大的尺寸(l)范围设置。(The device is provided with a movable iron core (27a) and a fixed iron core (25) for driving a valve element, and a cylindrical body (5) which internally contains the movable iron core (27a) and the fixed iron core (25). The cylindrical body (5) has an annular groove (5h), and the annular groove (5h) forms a thin-walled portion (5i) having a small wall thickness in the circumferential direction on the outer peripheral side of the facing portion of the movable iron core (27a) and the fixed iron core (25). The thin portion (5i) has a curved portion (5x), and the curved portion (5x) connects the side edges (5h1,5h2) of the annular groove portion (5h) to the bottom portion (the portion corresponding to the thinnest portion (5i 0)) via curves at both end portions in the direction along the central axis (1x) in a cross section parallel to the central axis (1x) of the fuel injection valve and including the central axis (1 x). The curved portion (5x) is provided in a range of a dimension (l) greater than a groove depth dimension (d) of the annular groove portion (5h) from the side edges (5h1,5h2) in a direction along the center axis (1 x).)

1, A fuel injection valve, comprising:

a valve seat and a valve element which cooperate to open and close the fuel passage;

a movable iron core and a fixed iron core which mutually act to drive the valve core by electromagnetic force;

a cylindrical body including the movable iron core and the fixed iron core therein;

the cylindrical body has an annular groove portion formed with a thin wall portion having a small thickness in a circumferential direction on an outer peripheral side of a facing portion where the movable iron core and the fixed iron core face each other,

the thin portion has a curved portion that connects a side edge and a bottom portion of the annular groove portion by a curve at both end portions in a direction along a central axis of the fuel injection valve in a cross section parallel to and including the central axis,

the curved portion is provided from the side edge in a direction along the center axis within a size range larger than a groove depth of the annular groove portion.

2. The fuel injection valve according to claim 1,

the thin portion connects the -side edge of the annular groove portion and the -side edge of the annular groove portion in the direction along the central axis by a curve in the cross section.

3. The fuel injection valve according to claim 2,

the curve of the thin-walled portion is constituted by an arc constituting a circumference of an ellipse.

4. The fuel injection valve according to claim 2,

the thin portion has th and second thin portions separately arranged in a direction along the center axis, the th thin portion is formed by a th annular recess, and the second thin portion is formed by a second annular recess.

5. The fuel injection valve according to claim 4,

a thick portion having a greater thickness than the th and second thin portions is provided between the th thin portion and the second thin portion,

at least one side of the outer peripheral surface of the movable iron core opposite to the inner peripheral surface of the thick part and the outer peripheral surface of the fixed iron core opposite to the inner peripheral surface of the thick part is provided with a gap enlarging part for enlarging the gap with the inner peripheral surface of the thick part.

Technical Field

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

Background

As a background art in this field, a fuel injection valve described in japanese patent application laid-open No. 2008-215362 (patent document 1) is known, in which a magnetic cylinder is formed by a metal pipe or the like , and a thin portion (refer to abstract) magnetically disconnecting a valve body housing portion and a core member insertion portion is provided in a midway portion thereof.

Disclosure of Invention

Technical problem to be solved by the invention

In the fuel injection valve of patent document 1, by providing the thin-walled portion magnetically cutting off the valve element housing portion and the core member (fixed core) insertion portion of the magnetic cylindrical body (cylindrical body), it is possible to stably conduct magnetic force between the attraction portion (movable core) of the valve element and the core cylinder (fixed core), and to improve the magnetic attraction force acting between the movable core and the fixed core.

The invention provides fuel injection valves capable of reducing the thickness of a thin wall part of a cylindrical body and improving the magnetic attraction force of a movable iron core.

Technical solution for solving technical problem

In order to achieve the above object, a fuel injection valve according to the present invention includes:

a valve seat and a valve element which cooperate to open and close the fuel passage;

a movable iron core and a fixed iron core which mutually act to drive the valve core by electromagnetic force;

a cylindrical body including the movable iron core and the fixed iron core therein;

the cylindrical body has an annular groove portion formed with a thin wall portion having a small thickness in a circumferential direction on an outer peripheral side of a facing portion where the movable iron core and the fixed iron core face each other,

the thin portion has a curved portion that connects a side edge and a bottom portion of the annular groove portion by a curve at both end portions in a direction along a central axis of the fuel injection valve in a cross section parallel to and including the central axis,

the curved portion is provided from the side edge in a direction along the center axis within a size range larger than a groove depth of the annular groove portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the thickness of the thin wall portion of the cylindrical body can be reduced, and the magnetic attraction force acting on the movable core can be increased. This can increase the installation load of the spring member that biases the valve body, and can reduce the minimum fuel injection amount of the fuel injection valve.

Drawings

Fig. 1 is a cross-sectional view showing a cross-section along a valve axial center (central axis) of embodiments of the fuel injection valve of the present invention.

Fig. 2 is an enlarged cross-sectional view of the vicinity of the mover 27 shown in fig. 1.

Fig. 3 is an enlarged cross-sectional view of the nozzle portion 8 shown in fig. 2.

Fig. 4 is a cross-sectional view showing the configuration of embodiments of the thin portion 5i of the present invention, and is a cross-sectional view showing the vicinity of the thin portion 5i in an enlarged manner.

Fig. 5 is a cross-sectional view illustrating a difference in operational effects between the thin portion 5i of fig. 4 and the thin portion 5 i' of the comparative example.

Fig. 6 is a diagram illustrating a difference in valve body displacement (valve body lift) between the thin portion 5i of fig. 4 and the thin portion 5 i' of the comparative example.

Fig. 7 is a sectional view showing the structure of a modification ( th modification) of the thin portion 5i of the present invention, and is an enlarged sectional view showing the vicinity of the thin portion 5 i.

Fig. 8 is a sectional view showing a structure of a modification (second modification) of the thin portion 5i of the present invention, and is an enlarged sectional view showing the vicinity of the thin portion 5 i.

Fig. 9 is a sectional view of an internal combustion engine equipped with the fuel injection valve 1.

Detailed Description

An embodiment of the present invention will be described with reference to fig. 1 to 3.

Fig. 1 is a cross-sectional view showing a cross section along a valve axial center (central axis line) of embodiments of the fuel injection valve of the present invention, and it should be noted that central axes 1x and of a valve body 27c, a rod portion (connecting portion) 27b, and a movable core 27a are integrally provided, and the central axis 27x of the movable core 27 corresponds to the central axis line of the cylindrical body 5 and the valve seat member 15.

In fig. 1, an 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 a lower end portion (lower end side) may be referred to as a tip end portion (tip end side). The designations of the base end portion (base end side) and the tip end portion (tip end side) are based on the flow direction of the fuel or the mounting structure of the fuel injection valve 1 to the fuel pipe. The vertical relationship described in the present specification is based on fig. 1, and is not related to the vertical direction in the actual mounting state of the fuel injection valve 1 on the internal combustion engine.

In the fuel injection valve 1, a cylindrical body (cylindrical member) 5 made of a metal material forms a fuel flow path (fuel passage) 3 on the inner side thereof so as to substantially follow a central axis 1 x. the cylindrical body 5 is formed in a stepped shape along the central axis 1x by press working such as deep drawing using a metal material such as magnetic stainless steel, whereby the diameter of the end side (large diameter portion 5a side) of the cylindrical body 5 is increased relative to the diameter of the other end side (small diameter portion 5b side).

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

A flange portion (diameter-enlarged portion) 5d bent so as to be radially outwardly enlarged in diameter is formed at the base end portion of the cylindrical body 5, and an O-ring 11 is disposed in an annular recess portion (annular groove portion) 4 formed by the flange portion 5d and the base end side end portion 47a of the cover 47.

A valve portion 7 including a valve body 27c and a valve seat member 15 is formed at the front end portion of the cylindrical body 5. The valve seat member 15 is inserted into the front end side of the tubular body 5 and fixed to the tubular body 5 by laser welding. The laser welding is performed from the outer peripheral side of the cylindrical body 5 over the entire circumference. In this case, valve seat member 15 may be pressed into the inside of the distal end side of tubular body 5, and then valve seat member 15 may be fixed to tubular body 5 by laser welding.

A nozzle plate 21n is fixed to the seat member 15, and the seat member 15 and the nozzle plate 21n constitute a nozzle portion 8. The valve seat member 15 and the nozzle plate 21n are assembled to the distal end side of the cylindrical body 5 by inserting and fixing the valve seat member 15 into the inner peripheral surface of the cylindrical body 5.

The tubular body 5 of the present embodiment is constituted by members 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 front end side portion of the tubular body 5 constitutes a nozzle seat that holds the nozzle portion 8, and in the present embodiment, the nozzle seat is constituted by members from the base end side portion of the tubular body 5.

A driving portion 9 for driving the spool 27c is disposed in the middle portion of the cylindrical body 5. The drive unit 9 is constituted by an electromagnetic actuator (electromagnetic drive unit).

Specifically, the driving unit 9 includes a fixed core (fixed core) 25 fixed inside (on the inner circumferential side) the tubular body 5, a movable element (movable member) 27 disposed on the front end side with respect to the fixed core 25 inside the tubular body 5, an electromagnetic coil 29 externally inserted on the outer circumferential side of the tubular body 5, and a yoke 33 covering the electromagnetic coil 29 on the outer circumferential side of the electromagnetic coil 29. The movable element 27 has a movable core (movable core) 27a facing the fixed core 25 on the base end side, and is assembled to be movable in the direction along the central axis 1 x. The electromagnetic coil 29 is disposed on the outer peripheral side (radially outward) of the position where the fixed core 25 and the movable core 27a face each other with the small gap δ 1 interposed therebetween. This causes the movable iron core 27a and the fixed iron core 25 to interact with each other by an electromagnetic force to drive the valve element 27 c.

The rotor 27 and the fixed core 25 are housed inside the cylindrical body 5, and the cylindrical body 5 abuts against the fixed core 25 and forms a housing that surrounds the movable core 27a and the fixed core 25 while facing the outer peripheral surface of the movable core 27 a. That is, the cylindrical body 5 includes the movable iron core 27a and the fixed iron core 25 therein.

The movable iron core 27a, the fixed iron core 25, and the yoke 33 constitute a closed magnetic circuit through which magnetic flux generated by the passage of current to the electromagnetic coil 29 flows. The magnetic flux passes through the small gap δ 1, but in order to reduce the leakage magnetic flux flowing through the cylindrical body 5 at the portion passing through the small gap δ 1, a non-magnetic portion or a weak-magnetic portion having a weaker magnetic property than other portions of the cylindrical body 5 is provided at a position corresponding to the small gap δ 1 of the cylindrical body 5. Hereinafter, the non-magnetic portion or the weak magnetic portion will be simply referred to as the non-magnetic portion 5 c.

In the present embodiment, the nonmagnetic section 5c is constituted by an annular recess 5h formed in the outer peripheral surface of the cylindrical body 5. The annular recess 5h is formed to have a thin portion 5i by thinning a portion corresponding to the nonmagnetic portion 5 c. That is, the annular recess 5h is formed with a thin portion 5i having a small thickness in the circumferential direction at a portion of the cylindrical body 5 located at the outer peripheral portion of the facing portion of the movable core 27a facing the fixed core 25. The thin portion 5i is thinner (thickness dimension) than the other portions of the cylindrical body 5, and increases the magnetic resistance of the magnetic flux passing therethrough, making the magnetic flux difficult to flow. The thin portion 5i will be described in detail later.

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

The fixed iron core 25 is made of a magnetic metal material. The fixed core 25 is formed in a cylindrical shape and has a through hole 25a penetrating through the center portion in a direction along the center axis 1 x. The through-hole 25a constitutes a fuel passage (upstream-side fuel passage) 3 on the upstream side of the movable core 27 a. The fixed core 25 is press-fitted and fixed to the base end side of the small diameter portion 5b of the cylindrical body 5 and is positioned at the intermediate portion of the cylindrical body 5. By providing the large diameter portion 5a on the base end side of the small diameter portion 5b, the assembly of the fixed core 25 becomes easy. The fixed core 25 may be fixed to the cylindrical body 5 by welding, or may be fixed to the cylindrical body 5 by welding and press-fitting together.

The movable element 27 is constituted by a movable iron core 27a, a rod portion (connection portion) 27b, and a valve body 27 c. The movable iron core 27a is an annular member. The valve body 27c is a member that abuts against the valve seat 15b (see fig. 3). The valve seat 15b and the valve body 27c cooperate to open and close the fuel passage. The lever portion 27b has an elongated cylindrical shape and is a connecting portion for connecting the movable iron core 27a and the valve body 27 c.

The movable iron core 27a is coupled to the valve body 27c and drives the valve body 27c in the opening/closing direction by a magnetic attraction force acting between the movable iron core and the fixed iron core 25.

Although the movable core 27a and the lever portion 27b are fixed in the present embodiment, the movable core 27a and the lever portion 27b may be connected to each other so as to be displaceable relative to each other.

In the present embodiment, the stem portion 27b and the valve body 27c are formed by separate members, the valve body 27c is fixed to the stem portion 27b, the stem portion 27b and the valve body 27c are fixed by press fitting or welding, and the stem portion 27b and the valve body 27c can be formed by bodies of members.

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

A spring member is provided in the through hole 25a of the fixed core 25. In the present embodiment, the spring member is constituted by a coil spring 39. Hereinafter, the explanation will be made with reference to the coil spring 39.

The end of the coil spring 39 abuts against a spring seat 27ag provided inside the movable iron core 27a, the other end of the coil spring 39 abuts against a regulator (adjuster) 35 provided inside the through hole 25a of the fixed iron core 25, and the coil spring 39 is disposed in a compressed state between the spring seat 27ag provided on the movable iron core 27a and the lower end (front end side end face) of the regulator (adjuster) 35.

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

The regulator 35 has a fuel flow path 3 penetrating the center portion in a direction along the central axis 1 x.

The fuel supplied from the fuel supply port 2 flows through the fuel flow path 3 of the regulator 35, then flows through the fuel flow path 3 at the tip end side of the through hole 25a of the fixed core 25, and flows through the fuel flow path 3 formed in the mover 27.

The yoke 33 is formed of a magnetic metal material and serves as a housing of the fuel injection valve 1, the yoke 33 is formed in a stepped cylindrical shape having a large diameter portion 33a and a small diameter portion 33b, the large diameter portion 33a is formed in a cylindrical shape so as to cover the outer periphery of the electromagnetic coil 29, the small diameter portion 33b having a smaller diameter than the large diameter portion 33a is formed on the front end side of the large diameter portion 33a, and the small diameter portion 33b is press-fitted into or inserted into the outer periphery of the small diameter portion 5b of the cylindrical body 5, whereby the inner peripheral surface of the small diameter portion 33b is brought into close contact with the outer peripheral surface of the cylindrical body 5, at least portion of the inner peripheral surface of the small diameter portion 33b faces the outer peripheral surface of the movable core 27a through the cylindrical body 5, and the magnetic.

An annular recess 33c is formed in the outer peripheral surface of the distal end of the yoke 33 in the circumferential direction. The yoke 33 and the cylindrical body 5 are joined to each other over the entire circumference by laser welding at a thin portion formed on the bottom surface of the annular recess 33 c.

A cylindrical protector 49 having a flange portion 49a is externally fitted to the front end portion of the cylindrical body 5, and the front end portion of the cylindrical body 5 is protected by the protector 49. The protector 49 covers the laser welding portion 24 of the yoke 33.

The flange 49a of the protector 49, the small diameter portion 33b of the yoke 33, and the stepped surfaces of the large diameter portion 33a and the small diameter portion 33b of the yoke 33 form an annular groove 34, and the O-ring 46 is inserted into the annular groove 34. When the fuel injection valve 1 is mounted in an internal combustion engine, the O-ring 46 functions as a seal for ensuring liquid-tightness and air-tightness between the inner peripheral surface of the insertion opening formed on the internal combustion engine side and the outer peripheral surface of the small diameter portion 33b of the yoke 33.

The resin cover 47 is molded over a range from the middle portion of the fuel injection valve 1 to the vicinity of the proximal end side end portion, the distal end side end portion of the resin cover 47 covers the portion on the proximal end side of the large diameter portion 33a of the yoke 33, and the connector 41 is integrally formed by the resin forming the resin cover 47.

The structure in the vicinity of the mover 27 will be described in detail with reference to fig. 2. Fig. 2 is an enlarged cross-sectional view of the vicinity of the mover 27 shown in fig. 1.

In the present embodiment, the movable iron core 27a and the lever portion 27b are integrally formed by pieces .

A recess 27aa recessed toward the lower end side is formed in the center of the upper end surface (upper end portion) 27ab of the movable iron core 27a, a spring seat 27ag is formed at the bottom of the recess 27aa, the end (tip end side end portion) of the coil spring 39 is supported by the spring seat 27 ag., and an opening 27 af. opening 27af communicating with the inside of the hole 27ba of the rod portion 27b is formed in the spring seat 27ag of the recess 27aa, constituting a fuel passage for allowing the fuel flowing from the through hole 25a of the fixed iron core 25 into the space 27ai in the recess 27aa to flow into the space 27bi inside the hole 27ba of the rod portion 27 b.

In the present embodiment, the lever portion 27b and the movable iron core 27a are constituted by parts, but the lever portion 27b and the movable iron core 27a constituted by separate parts may be integrally assembled.

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

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

In the present embodiment, the outer peripheral surface 27ac of the movable iron core 27a constitutes a sliding portion that slides along the inner peripheral surface 5e of the cylindrical body 5. As the sliding portion, a convex portion 27al protruding radially outward is provided on the outer peripheral surface 27 ac. The inner peripheral surface 5e constitutes an upstream side guide portion 50B on which the convex portion 27al of the movable iron core 27a slides.

In addition, , the valve seat member 15 is provided with a guide surface 15c (see fig. 3) on which the spherical surface 27cb of the valve body 27c slides, and the guide portion that guides the spherical surface 27cb by the guide surface 15c is provided with a downstream side guide portion 50A, whereby the movable element 27 is guided at two points, i.e., the upstream side guide portion 50B and the downstream side guide portion 50A, and reciprocates in a direction (opening/closing valve direction) along the center axis 1 x.

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

Next, the structure of the nozzle section 8 will be described in detail with reference to fig. 3. Fig. 3 is an enlarged cross-sectional view of the nozzle portion 8 shown in fig. 2.

The valve seat member 15 is formed with a through hole (an enlarged diameter portion 15d, a guide surface 15c, a conical surface 15v, and a fuel introduction hole 15e) penetrating in a direction along the center axis 1 x. A conical surface (conical surface) 15v having a diameter reduced toward the downstream side is formed in the middle of the through hole. The conical surface 15v forms a valve seat 15b, and the valve element 27c is separated from and brought into contact with the valve seat 15b to open and close the fuel passage. The conical surface 15v forming the valve seat 15b may be referred to as a valve seat surface.

The abutting portion between the valve seat 15b and the valve body 27c constitutes a seal portion for sealing fuel when the valve is closed.

The hole portions (the enlarged diameter portion 15d, the guide surface 15c, the conical surface 15v, and the conical surface 15v) on the upper side from the conical surface 15v in the through hole (the enlarged diameter portion 15d, the guide surface 15c, and the fuel introduction hole 15e) constitute a valve body accommodation hole that accommodates the valve body 27 c. A guide surface 15c that guides the valve body 27c in a direction along the central axis 1x is formed on the inner peripheral surface of the valve body accommodating hole (the enlarged diameter portion 15d, the guide surface 15c, and the conical surface 15 v). The guide surface 15c constitutes a downstream side guide portion (downstream side guide surface) 50A located on the downstream side of the two guide surfaces that guide the movable element 27.

An enlarged diameter portion 15d having an enlarged diameter toward the upstream side is formed on the upstream side of the guide surface 15 c.

The lower end portion of the valve body accommodation hole (the enlarged diameter portion 15d, the guide surface 15c, and the conical surface 15v) is connected to the fuel introduction hole 15e, and the lower end surface of the fuel introduction hole 15e is opened at the front end surface 15t of the valve seat member 15.

The nozzle plate 21n is attached to the front end surface 15t of the valve seat member 15, the nozzle plate 21n is fixed to the valve seat member 15 by laser welding, and the laser welded portion 23 surrounds the periphery of the injection hole forming region in which the fuel injection holes 51 are formed so as to surround the injection hole forming region.

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

A plurality of fuel injection holes 51 are formed in the projecting portion 21 na. The form of the fuel injection hole 51 is not particularly required. A rotation chamber that applies a rotational 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 or inclined with respect to the central axis 1x of the fuel injection valve. Further, the projection 21na may be omitted.

The fuel injection portion 21 for determining the form of fuel spray is constituted by the nozzle plate 21n, the valve seat member 15 and the fuel injection portion 21 constitute the nozzle portion 8 for performing fuel injection, and the valve body 27c may be regarded as the portion constituting the constituent element of the nozzle portion 8.

In the present embodiment, a ball valve having a spherical shape is used as the valve body 27 c. Therefore, a plurality of notch surfaces 27ca are provided at circumferentially spaced intervals in a portion of the valve body 27c facing the guide surface 15c, and a fuel passage for supplying fuel to the thin plate portion is formed by the notch surfaces 27 ca. The valve body 27c can be formed of a valve body other than a 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 front end portion of the tubular body 5 and then welded and fixed to the tubular body 5 by a welded portion 19.

Next, the structure of the thin portion 5i will be described with reference to fig. 4, fig. 4 is a cross-sectional view showing the structure of embodiments of the thin portion 5i of the present invention, and is a cross-sectional view showing the vicinity of the thin portion 5i in an enlarged manner.

In the present embodiment, the thin-walled portion 5i is formed by forming an annular recessed portion (annular groove portion) 5h so as to circumferentially surround the outer peripheral surface of the cylindrical body 5, that is, the annular recessed portion 5h is formed with a thin-walled portion 5i having a small wall thickness in the circumferential direction at a portion of the cylindrical body 5 located in an outer peripheral portion of a facing portion where the movable core 27a faces the fixed core 25 (a portion where an upper end surface (base end side end surface) 27ab of the movable core 27a and a lower end surface (front end side end surface) 25b of the fixed core 25) facing each other.

The annular recess 5h is formed by a curved portion 5x that is curved as a whole and includes a cross-sectional shape (hereinafter simply referred to as a cross-sectional shape) of the central axis 1x parallel to the central axis 1x, and particularly in the present embodiment, the curved portion 5x is formed in a shape of an arc (a circumferential portion) that constitutes the circumference of an ellipse, and thereby, a bent shape portion such that, for example, a straight portion and a straight portion intersect is not present in the cross-sectional shape of the annular recess 5h, the thin portion 5i is formed in the entire annular recess 5h1 from the upper end side edge (base end side end portion) 5h1 to the lower end side edge (tip end side end portion) 5h2 of the annular recess 5h, and the thinnest portion 5h0 of the annular recess 5h corresponding to the thinnest portion 5i0 is regarded as the bottom of the annular recess 5h at the thinnest portion 5i0 near the portion where the fixed core 25 and the movable core 27a face.

In the present embodiment, the thinnest portion 5i0 is located at the center (center) in the width direction (direction along the central axis 1x) of the annular recessed portion 5 h. A length dimension l between the side edge 5h1 and the thinnest portion 5i0 in the direction along the central axis 1x is larger than a depth dimension d of the annular recess 5 h. A length dimension l between the side edge 5h2 and the thinnest portion (bottom portion of the annular recess 5h) 5i0 in the direction along the central axis 1x is larger than a depth dimension d of the annular recess 5 h. That is, the curved portion provided between 5h1 and 5i0 is provided at a dimension (dimension range) l larger than the groove depth dimension d of the annular recessed portion 5h from the side edge 5h1 in the direction along the central axis 1 x. The curved portion provided between 5h2 and 5i0 is provided at a dimension (dimension range) l larger than the groove depth dimension d of the annular recessed portion 5h from the side edge 5h2 in the direction along the center axis 1 x.

The fixed core 25 is press-fitted into the cylindrical body 5 from the base end side, and the valve seat member 15 is press-fitted into the cylindrical body 5 from the tip end side. Therefore, the cylindrical body 5 needs to have strength to withstand the compressive stress generated by press-fitting. In particular, the thin portion 5i in which the annular recess 5h is formed is a portion having a reduced strength, and the thin portion 5i needs to have a strength to withstand a compression stress generated by press-fitting.

In the present embodiment, the groove surface (the surface of the thin portion 5i) between the upper end and the lower end of the annular recessed portion 5h and the thinnest portion 5i0 is formed into a smoothly curved surface shape (curved portion 5x) having a concave shape (concave surface) when viewed from the outer peripheral side.

That is, the groove surface (the surface of the thin portion 5i) between the upper end and the lower end of the annular recessed portion 5h is formed into a smooth curved surface shape having a concave shape (concave surface) when viewed from the outer peripheral side. This can increase the maximum compression load that the annular recessed portion 5h can withstand, thereby increasing the strength of the cylindrical body 5.

Next, the operation and effect of the thin portion 5i of the present embodiment will be described with reference to fig. 5 and 6.

Fig. 5 is a cross-sectional view illustrating a difference in operational effects between the thin portion 5i of fig. 4 and the thin portion 5 i' of the comparative example.

In fig. 5, an annular recessed portion (annular groove portion) 5 h' of a comparative example is shown by a broken line with respect to the annular recessed portion 5h of the present example. The annular recess 5h 'of the comparative example has a bottom portion 5h 0' at a central portion between the upper end and the lower end, and inclined portions (tapered portions) 5h3 'are formed at the upper end portion and the lower end portion of the bottom portion 5h 0', respectively. Thus, in the present embodiment, the annular recessed portion 5h ' is formed, and the wall thickness (thickness dimension) of the cylindrical body 5 in the bottom portion 5h0 ' of the thin portion 5i ' is constant, and the wall thickness increases from the upper end portion and the lower end portion of the bottom portion 5h0 ' toward the side edge (upper end) 5h1 and the side edge (lower end) 5h2 of the annular recessed portion 5h '.

In the thin portion 5i ' of the comparative example, a wall thickness sharply varied portion 5h4 ' in which the outer peripheral surface is bent to sharply vary the wall thickness is formed at a portion where the bottom portion 5h0 ' of the annular recessed portion 5h ' intersects with the inclined portion 5h3 '. The maximum compressive load that the rapid wall thickness-changing portion 5h4 'can withstand is reduced, and the rapid wall thickness-changing portion 5h 4' is easily broken when the iron core 25 or the valve seat member 15 is pressed in.

In the present embodiment, the maximum compressive load that the thin portion 5i can withstand can be increased by making the cross-sectional shape of the annular recess 5h (the outer peripheral surface of the thin portion 5i) a curved shape from the upper end to the lower end. This can improve the strength of the cylindrical body 5. This means that the minimum thickness T1 of the thin-walled portion 5i can be made smaller than the thickness T1' of the comparative example, as long as the strength of the cylindrical body 5 is maintained to the same degree as in the conventional art.

Fig. 6 is a diagram illustrating a difference in valve body displacement (valve body lift) between the thin portion 5i of fig. 4 and the thin portion 5 i' of the comparative example.

In the present embodiment, the minimum thickness T1 of the thin portion 5i can be made smaller than the conventional thickness T1', and therefore the magnetic resistance of the thin portion 5i can be increased, and the leakage magnetic flux passing through the tubular body 5 can be reduced at the facing portion between the fixed core 25 and the movable core 27 a. This can increase the magnetic attraction force acting between the fixed iron core 25 and the movable iron core 27 a. When the magnetic attraction force increases, the valve opening operation of the valve body 27c can be started at a timing of lifting up, and the valve opening speed can be increased, so that the valve opening operation can be performed quickly.

When the magnetic attraction force increases, the installation load (urging force) of the coil spring 39 can be increased, the timing of starting the valve closing operation of the valve body 27c can be advanced, the valve closing speed can be increased, and the valve closing operation can be performed quickly. The valve closing operation will be described.

Fig. 6 shows a case where fuel injection is performed by an injection pulse having a pulse width (on time) Ti. There is a delay period a from when the injection pulse is on until the valve body 27c starts the valve opening operation. This is because it takes time for the magnetic attraction force acting between the fixed iron core 25 and the movable iron core 27a to become larger than the installation load of the coil spring 39 or the fuel pressure. The valve body 27c transits from the closed valve state to the open valve state during the period B. The time from when the injection pulse is on to when the valve body 27c is switched to the open valve state is Ta.

In the present embodiment, the amount of magnetic attraction force can be increased by increasing the installation load of the coil spring 39, and the balance between the magnetic attraction force and the installation load of the coil spring 39 is set to the same condition as that of the comparative example. Therefore, the valve opening time Ta including the delay period a until the valve body 27c starts the valve opening operation and the transition period B during which the valve body 27c transits from the valve closed state to the valve opened state is the same in the present embodiment and the comparative example.

When the injection pulse is turned off after the on-time Ti of the injection pulse has elapsed, the magnetic attraction acting between the fixed iron core 25 and the movable iron core 27a decreases, which takes time, and in the case of the present embodiment, the valve closing operation is started by the installation load of the coil spring 39 after the valve body 27C has elapsed the delay period C, and in addition, , in the case of the comparative example, the installation load of the coil spring 39 is set to be smaller than that of the present embodiment, and therefore, the valve closing operation is started after a period longer than the delay period C of the present embodiment has elapsed.

In the present embodiment, since the installation load of the coil spring 39 is set to be larger than that of the comparative example, the valve closing speed of the valve body 27c is also higher than that of the comparative example, and the valve is changed from the open state to the closed state in a period D shorter than that of the comparative example. Therefore, in the present embodiment, the time for transition from the valve-opened state to the valve-closed state can be shortened as compared with the comparative example.

As described above, in the present embodiment, the valve closing time Tb including the delay period C until the valve element 27C starts the valve closing operation and the transition period D during which the valve element 27C transitions from the open valve state to the closed valve state can be made shorter than the valve closing time Tb' of the comparative example.

In the present embodiment, the valve closing time Tb can be shortened, so the controllable minimum fuel injection amount (qmin) can be reduced, and qmin performance can be improved. The inventors confirmed through simulation experiments that by using the thin-walled portion 5i of the present embodiment, the minimum thickness of the thin-walled portion 5i can be reduced in a state where the strength of the tubular body 5 is set to be the same as that of the comparative example, the magnetic attraction force can be made larger than that of the comparative example, and the qmin performance can be improved by 10% as compared with that of the comparative example.

Next, a modification of the thin portion 5i will be described with reference to fig. 7 and 8.

Fig. 7 is a sectional view showing the structure of a modification ( th modification) of the thin portion 5i of the present invention, and is an enlarged sectional view showing the vicinity of the thin portion 5 i.

In the present modification, the annular recessed portion 5h is constituted by a groove portion 5h7 formed so that a portion between the position indicated by 5h5 and the position indicated by 5h6 has a depth dimension d (constant). The groove surfaces (the surfaces of the thin portions 5i) of the portion between the side edges (upper ends) 5h1 and 5h5 in the direction (width direction) along the central axis 1x of the annular recessed portion 5h and the portion between the side edges (lower ends) 5h2 and 5h6 in the width direction of the annular recessed portion 5h are formed into a smoothly curved surface shape having a concave shape (concave surface) when viewed from the outer peripheral side. That is, the sectional shape of the groove surface 5h8 between 5h1 and 5h5 is a curved portion (curve) 5x passing through 5h1 and 5h5, and the sectional shape of the groove surface 5h9 between 5h2 and 5h6 is a curved portion (curve) 5x passing through 5h2 and 5h 6. Particularly in the present embodiment, the groove surface 5h8 between 5h1 and 5h5 is formed in such a manner that its sectional shape becomes an arc passing through 5h1 and 5h5, and the groove surface 5h9 between 5h2 and 5h6 is formed in such a manner that its sectional shape becomes an arc passing through 5h2 and 5h 6.

A length dimension l between 5h1 and 5h5 in the direction along the central axis 1x is larger than a depth dimension d of the annular recess 5 h. That is, the curved portion 5x provided between 5h1 and 5h5 and the curved portion 5x provided between 5h2 and 5h6 are provided from the side edges 5h1,5h2 in the direction along the central axis 1x by a dimension (dimension range) l larger than the groove depth dimension d of the annular recessed portion 5 h.

In the present embodiment, the length dimension between 5h2 and 5h6 in the direction along the central axis 1x is equal to the length dimension l between 5h1 and 5h5, but may be different from the length dimension l between 5h1 and 5h5 as long as it is larger than the depth dimension d of the annular recess 5 h.

When the cross-sectional shapes of the groove surface 5h8 and the groove surface 5h9 are circular arcs, the radius r of the circular arc is larger than the depth d of the annular recess 5 h.

In the present modification, the same effects as in the above embodiment can be obtained by setting the groove depth d of the annular recessed portion 5h and the installation load of the coil spring 39 as in the above embodiment. However, in the present modification, the maximum compressive load that the thin portion 5i can withstand is smaller than in the above-described embodiment, but can be larger than in the comparative example.

Fig. 8 is a sectional view showing a structure of a modification (second modification) of the thin portion 5i of the present invention, and is a sectional view showing a vicinity of the thin portion 5i in an enlarged manner.

In this modification, the th annular recessed portion ( annular groove portion) 5hA and the second annular recessed portion (second annular groove portion) 5hB are disposed so as to be separated from each other in the direction along the central axis 1x, in the case where the th annular recessed portion 5hA forms the th thin portion 5iA on the cylindrical body 5 and the second annular recessed portion 5hB forms the second thin portion 5 iB. on the cylindrical body 5, the portion 5j having a large wall thickness is formed between the th annular recessed portion 5hA and the second annular recessed portion 5 hB.

In the present embodiment, the thinnest portion 5iA0 of the thin-walled portion 5iA is located at the center (center) in the width direction (direction along the central axis 1x) of the annular recessed portion 5hA and the thinnest portion 5iB0 of the second thin-walled portion 5iB is located at the center (center) in the width direction (direction along the central axis 1x) of the second annular recessed portion 5 hB.

The th annular recessed portion 5hA is deepest in the thinnest portion 5iA0 of the thin portion 5iA, the deepest portion 5hA0 of the th annular recessed portion 5hA corresponding to the thinnest portion 5iA0 is regarded as the bottom of the th annular recessed portion 5hA, the second annular recessed portion 5hB is deepest in the thinnest portion 5iB0 of the second thin portion 5iB, and the deepest portion 5hB0 of the second annular recessed portion 5hB corresponding to the thinnest portion 5iB0 is regarded as the bottom of the second annular recessed portion 5 hB.

The length dimension l between the side edge 5hA1 of the -th annular recess 5hA and the thinnest portion 5iA0 in the direction along the central axis 1x is larger than the depth dimension d of the -th annular recess 5hA and the length dimension l between the side edge 5hA2 of the -th annular recess 5hA and the thinnest portion 5iA0 in the direction along the central axis 1x is larger than the depth dimension d of the -th annular recess 5hA, that is, the curved portion 5xA provided between the 5hA1 and the 5iA0 is provided in a dimension (dimension range) l larger than the groove depth dimension d of the -th annular recess 5hA in the direction along the central axis 1x from the side edge 5hA1 of the -th annular recess 5hA in the direction along the central axis 1x and the curved portion 5xA provided between the 5hA2 and the 5iA0 is provided in a deformed form the curved portion 0 of the circular-shaped recess 5hA 595 a with the curved portion 595 xA provided between the central axis 6348-th annular recess 5hA 6348 hA and the curved portion 595 xA in the dimension of the circular recess 595 a 599.

The length dimension l between the side edge 5hB1 of the second annular recess 5hB and the thinnest part 5iB0 in the direction along the central axis 1x is larger than the depth dimension d of the second annular recess 5hB, and the length dimension l between the side edge 5hB2 of the second annular recess 5hB and the thinnest part 5iB0 in the direction along the central axis 1x is larger than the depth dimension d of the second annular recess 5hB, that is, the curved part 5xB provided between 5hB1 and 5iB0 is provided in the direction along the central axis 1x at a dimension (dimension range) l larger than the groove depth dimension d of the second annular recess 5hB from the side edge 5hB1 of the second annular recess 5hB in the direction along the central axis 1x, and the curved part 5xB provided between 5hB2 and 5iB0 is provided in the direction along the central axis 1x between the side edge 5hB2 of the second annular recess 5hB at a dimension (dimension range) larger than the groove depth dimension d of the second annular recess 5hB, and the curved part 5xB is provided in the direction along the central axis 1x, and the curved part 5hB2, the curved part 5xB is constituted by the curved part 385 hB 7342.

Since the thick portion 5j is located on the outer peripheral side of the facing portion between the fixed core 25 and the movable core 27a, portions of the magnetic flux (leakage flux) passing through the lower end face 25b of the fixed core 25 and the upper end face 27ab of the movable core 27a should flow from the side face of the fixed core 25 to the side face of the movable core 27a (or vice versa) through the thick portion 5j, in order to reduce the leakage flux, a gap enlarging portion for enlarging the gap with the inner peripheral face of the thick portion 5j is provided on at least either side of the side face (outer peripheral face) of the movable core 27a facing the inner peripheral face of the thick portion 5j and the side face (outer peripheral face) of the fixed core 25 facing the inner peripheral face of the thick portion 5 j.

In the present modification, gap-enlarging portions 25d for enlarging the gap with the inner peripheral surface of the tubular body 5 are provided at both the side surface portion of the fixed core 25 and the side surface portion of the movable core 27a facing the thick-walled portion 5j, and 27 am. can increase the magnetic resistance against the leakage magnetic flux flowing from the side surface of the fixed core 25 to the side surface (or the opposite direction) of the movable core 27a through the thick-walled portion 5j by providing either of the gap-enlarging portions 25d or the gap-enlarging portions 27am, and can make the magnetic resistance against the leakage magnetic flux larger by providing both the gap-enlarging portions 25d and the gap-enlarging portions 27 am.

In the present modification, the gap enlarging portions 25d,27am are formed by tapered surfaces. That is, the cross-sectional shapes of the expanded gap portions 25d,27am are formed in a linear shape inclined with respect to the central axis 1 x. The straight line is closer to the central axis 1x (the distance from the inner circumferential surface of the cylindrical body 5 is increased) on the side of the fixed core 25 facing the movable core 27a, and is further away from the central axis 1x (the distance from the inner circumferential surface of the cylindrical body 5 is decreased) on the base end side or the tip end side. That is, the gap enlarging portions 25d,27am are formed so that the diameters of the fixed iron core 25 and the movable iron core 27a become smaller as they approach the opposite portion where the fixed iron core 25 and the movable iron core 27a face each other.

The proximal end 25d1 of the expanded gap portion 25d is located on the proximal end side of the side edge (distal end) 5hA2 of the annular recessed portion 5hA in the direction along the central axis 1x, and the distal end 25am1 of the expanded gap portion 27am is located on the distal end side of the side edge (proximal end) 5hB1 of the second annular recessed portion 5hB in the direction along the central axis 1 x.

In the present modification, the same effects as in the above embodiment can be obtained by setting the groove depth d of the th annular recessed portion 5hA and the second annular recessed portion 5hB and the installation load of the coil spring 39 as in the above embodiment.

The number of annular recesses may be three or more.

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

A cylinder 102 is formed in an 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. An intake valve 105 for opening and closing the intake port 103 is provided in the intake port 103, and an exhaust valve 106 for opening and closing the exhaust port 104 is provided in the exhaust port 104. An intake pipe 108 is connected to an inlet side end 107a of an intake passage 107 formed in the engine block 101 and communicating with the intake port 103.

A fuel pipe 110 is connected to a 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 opening 109a into which the fuel injection valve 1 is inserted is formed in the mounting portion 109. The insertion opening 109a penetrates an inner wall surface (intake passage) of the intake pipe 108, and the fuel injected from the fuel injection valve 1 inserted into the insertion opening 109a is injected into the intake passage. In the case of the two-way spray, each fuel spray is injected 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.

In the fuel injection valve 1 of the present invention, the thickness of the thin portion 5i of the tubular body 5 can be reduced (reduced in thickness), and the leakage magnetic flux that passes through the thin portion 5i without passing through the opposing surface of the fixed iron core 25 and the movable iron core 27a can be reduced. Therefore, the magnetic attraction force acting on the movable iron core 27a can be increased.

The installation load of the coil spring (spring member) 39 can be increased by the amount of the magnetic attraction force increase, the valve closing operation start timing of the valve body 27c can be advanced, the valve opening speed can be increased, and the valve closing operation of the valve body 27c can be performed quickly.

In the present embodiment, the time required for the valve closing operation of the valve body 27c can be shortened, and thus the controllable minimum fuel injection amount (qmin) can be reduced, and qmin performance can be improved. As a result, the fuel efficiency performance of the internal combustion engine can be improved.

The tubular body 5 including the thin-walled portion 5i of the present embodiment is effective in securing strength capable of withstanding press-fitting of the fixed core 25 and the valve seat member 15, but even if the structure is such that both the fixed core 25 and the valve seat member 15 or any are not press-fitted, the strength can be improved, and the reliability of the fuel injection valve 1 can be improved.

The annular recess (annular groove) 5h for forming the thin portion 5i is preferably formed in a continuous shape circumferentially around the outer peripheral surface of the cylindrical body 5, however, the effect of reducing the leakage magnetic flux by the cylindrical body 5 is reduced, but the annular recess 5h may be formed in a discontinuous shape by dividing into a plurality of annular recess portions.

The present invention is not limited to the above-described embodiments, and a configuration of the portion may be deleted or another configuration not described may be added.

As the fuel injection valve according to the embodiment described above, for example, the following configuration can be considered.

The fuel injection valve includes aspects, each of which includes a valve seat and a valve element that cooperate to open and close a fuel passage, a movable iron core and a fixed iron core that drive the valve element by an electromagnetic force acting therebetween, and a tubular body that contains the movable iron core and the fixed iron core, wherein the tubular body has an annular groove portion that forms a thin portion having a small wall thickness in a circumferential direction on an outer peripheral side of a facing portion where the movable iron core and the fixed iron core face each other, the thin portion has a curved portion that connects a side edge and a bottom portion of the annular groove portion by a curve at both end portions in a direction along a central axis of the fuel injection valve in a cross section parallel to the central axis and including the central axis, and the curved portion is provided in a size range larger than a groove depth dimension of the annular groove portion from the side edge in the direction along the central axis.

In a preferred aspect of the fuel injection valve, the thin portion connects an -side edge of the annular groove portion and an other -side edge of the annular groove portion in the direction along the center axis by a curved line in the cross section.

In another preferred embodiment of , the curve of the thin-walled portion is formed by an arc of a circumference forming an ellipse in addition to the aspect of the fuel injection valve.

In another preferred embodiment of , the thin portion is any of forms of the fuel injection valve, and the thin portion includes a th thin portion and a second thin portion that are separately arranged in a direction along the central axis, the th thin portion is formed by a th annular recess, and the second thin portion is formed by a second annular recess.

In another preferred embodiment of , in addition to any of the embodiments of the fuel injection valve, a thick portion having a larger wall thickness than the thin portions and the thin portions is provided between the th thin portion and the second thin portion, and a gap enlarging portion for enlarging a gap with an inner peripheral surface of the thick portion is provided on at least any of sides of an outer peripheral surface of the movable core facing an inner peripheral surface of the thick portion and an outer peripheral surface of the fixed core facing an inner peripheral surface of the thick portion.