JP2001132584A - Fuel injection valve - Google Patents

Abstract

(57) [Problem] To provide a fuel injection valve for obtaining swirl fuel upstream of a valve seat,
Giving a large swirl energy to the fuel flow to promote an increase in the injection angle and atomization of the fuel. A nozzle body having a seat surface formed upstream of an orifice, a valve body driven to be in contact with or separated from the seat surface, and a nozzle body positioned upstream of the seat surface. And a fuel swirling element 37 for applying a swirling force to the fuel.
Has a radial groove 49 eccentric from the axial center of the valve body 6 in order to generate a swirling flow in the fuel, and is machined such that the ratio between the groove height and the groove width of the radial groove 49 is 1 or more. I do. Alternatively, processing is performed such that the cross-sectional shape of the radial groove 49 is asymmetric with respect to the center of the cross-section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve,
In particular, the present invention relates to a fuel injection valve for in-cylinder injection of a type in which swirling means gives swirling energy to a fuel flow to inject fuel from a fuel injection hole.

[0002]

2. Description of the Related Art Among internal combustion engines, a gasoline engine is
2. Description of the Related Art Conventionally, engines that inject fuel into an intake port using an electromagnetic fuel injection valve have become widespread. The intake air and fuel are mixed in the intake port, and the mixture is ignited and burned in the combustion chamber to generate power. On the other hand, among internal combustion engines, in a diesel engine mainly using light oil or the like as fuel, fuel is directly injected into a combustion chamber, and the fuel is spontaneously ignited by compressed air in the combustion chamber to obtain power. By the way, in the above-mentioned gasoline engine, an in-cylinder combustion type has been proposed in which fuel is directly injected into a combustion chamber to improve the responsiveness of the internal combustion engine.

In such a direct injection type gasoline engine, there have been proposed several types of fuel injection valves which inject high-pressure fuel efficiently by giving swirling energy to the fuel flow and injecting the fuel from fuel injection holes. Have been. The general structure of these fuel injection valves is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-2606.
No. 2 and JP-A-10-47208, a fuel injection valve body having a valve body (needle valve, ball valve, etc.) and a valve seat, and a fuel swirl for giving swirling energy to a fuel flow And an element.

[0004] The fuel swirling element is formed with an axial groove and a radial groove for applying a swirling force to the fuel. The fuel that has passed through the axial groove in a vertically downward direction changes its flow direction by 90 ° at the radial groove inlet portion, and flows horizontally in the radial groove. The four or six radial grooves are formed at positions eccentric from the center without passing through the axial center of the valve body. As a result, a turning force is applied to the fuel in the radial groove, and the fuel spreads to the atmosphere while turning from the injection valve outlet. Assuming that the distance from the axis center of the valve body to the outermost wall of the radial groove is R and the width of the radial groove is W, the strength of the swirling energy imparted to the fuel is from the axial center of the valve body to the radial groove. Is proportional to the amount of eccentricity L = R−W / 2 defined by the distance to the center. That is, in order to obtain a larger turning energy, it is preferable to install the radial groove as far away from the axial center of the valve body as possible and to reduce the groove width W.

[0005]

However, in the conventional fuel injection valve, the ratio of the height H to the width W of the radial groove is smaller than 1, that is, the groove width W is larger than the groove height H. When the distance R from the axis center of the valve body to the outermost wall of the radial groove is determined, the amount of eccentricity L of the radial groove is given by:
RW / 2 tended to be reduced. Therefore, the fuel flow is not always given a large swirling energy.

Further, in the conventional fuel injection valve, the cross-sectional shapes of the radial grooves are rectangular and circular, and are symmetric with respect to the center of the groove cross section. Therefore, the fuel flow in the radial groove is deflected toward the outermost wall of the groove and flows more, and the amount of eccentricity L of the radial groove cannot be increased. for that reason,
It did not always give large swirl energy to the fuel flow.

The present invention has been made in order to solve the above-mentioned problems in the prior art, and relates to a fuel injection valve that obtains swirling fuel upstream of a valve seat. It is intended to promote the increase and atomization of the fuel.

[0008]

According to the present invention, there is provided a nozzle body having a fuel injection hole and a valve seat formed upstream of the fuel injection hole. In a fuel injection valve including a valve element driven to be in contact with or away from the valve, and a fuel swirling element positioned upstream of the valve seat to apply a swirling force to fuel, the fuel swirling element includes a fuel swirling element. A swirl groove at a position eccentric from the axial center of the valve body in order to generate a swirl flow, wherein the ratio between the groove height and the groove width of the swirl groove is 1 or more. Construct an injection valve.

According to another aspect of the present invention, there is provided a nozzle body having a fuel injection hole and a valve seat formed upstream of the fuel injection hole, the nozzle body being in contact with or separated from the valve seat. And a fuel swirl element positioned upstream of the valve seat and for imparting swirl force to the fuel, wherein the fuel swirl element generates a swirl flow in the fuel. The fuel injection valve has a swirl groove at a position eccentric from the axial center of the valve body, and the cross-sectional shape of the swirl groove is asymmetric with respect to the center of the cross section.

According to another aspect of the present invention, there is provided a fuel injection valve according to the second aspect, wherein the cross-sectional shape of the swirl groove is trapezoidal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve showing one embodiment of the present invention. FIG. 2 is an enlarged sectional view showing a fuel swivel element and valve guide assembly structure of the fuel injection valve of FIG.
FIG. 3 is a perspective view of a flow path from the radial groove of the fuel swirl element to the orifice.

The fuel injection valve 1 shown in FIG. 1 includes an electromagnetic coil assembly 16, a magnetic yoke 3 surrounding the electromagnetic coil 15, and a core 2 located at the center of the electromagnetic coil 15 and having one end in contact with the yoke 3. A ball valve 4A which is a mover that lifts by a predetermined amount when the electromagnetic coil 15 is excited;
A, a seat surface 9 relating to a valve seat which is normally closed and is opened when the ball valve 4A is lifted, an orifice 8 relating to a fuel injection hole, and a fuel swirling element 3 which applies a swirling force to fuel.
And a valve guide 7 having a nozzle body 7. The ball valve 4A according to the mover has at least a magnetic plunger 4, a rod 5, and a ball 6 as a ball-shaped valve element integrally formed.

The fuel injection valve 1 of this embodiment is for a single-point fuel injection device, and will be described in detail below. The fuel injection valve 1 injects fuel by opening and closing the seat in response to a duty ON-OFF signal calculated by a control unit (not shown). The magnetic circuit includes a core 2 including a bottomed cylindrical yoke 3, a plug 2 a that closes an open end of the yoke 3, and a column 2 b extending to the center of the yoke 3, and a plunger facing the core 2 with a gap therebetween. And 4. At the center of the columnar portion 2b of the core 2, a ball valve 4A is
A hole for inserting and holding a spring 10 as an elastic member that presses against the seat surface 9 of the orifice 8 formed in the above is formed.

The upper end of the spring 10 is in contact with the lower end of a spring adjuster 11 inserted into the center of the core 2 for adjusting the set load. An O-ring 12 is provided between the core 2 and the spring adjuster 11 in order to prevent fuel from flowing out from the gap between the two. Further, between the core 2 and the yoke 3, O is provided to prevent fuel from flowing out from the gap between the core 2 and the yoke 3 to the outside.
A ring 13 is interposed.

An electromagnetic coil 15 for exciting the magnetic circuit is wound around the bobbin 14, and the outside thereof is molded with a plastic material. The terminal 18 of the electromagnetic coil assembly 16 composed of these is inserted into the hole 17 provided in the flange of the core 2,
An O-ring 19 is interposed between the terminal 18 and the core 2. A collar 20 for covering a mold resin (hereinafter referred to as a yoke mold) 19a outside the fuel injection valve 1 from entering the inside of the fuel injection valve 1 at the time of molding is placed over the entrance of the hole 17.

As a passage for the fuel or the fuel vapor, a gap 21 with the core 2, an upper passage 22, and a lower passage 23 are provided. An annular groove 25 is formed on the outer periphery of the yoke 3,
An O-ring 24 for preventing fuel from flowing out of a gap between the fuel injection valve 1 and a socket (not shown) as a housing.
Is held there. Around the yoke 3, an inflow passage 26 into which the fuel flows and an outflow passage 27 for allowing excess fuel including bubbles accumulated in the fuel injection valve 1 to flow out are opened.

A ball valve 4 is provided at the bottom of the yoke 3.
A plunger receiving portion 28 for receiving A is opened.
Furthermore, a stopper 29 having a diameter larger than the diameter of the plunger receiving portion 28 and a valve guide receiving portion 30 for receiving the valve guide 7 are penetrated to the tip of the yoke 3.
Further, the fuel flows from the inflow passage 26 to the outer periphery of the yoke 3,
An annular filter 31 is provided to prevent dust and foreign matter in the piping from entering the valve seat. A terminal 32 for transmitting a signal from the control unit to the coil 15 is joined to the terminal 18. These terminals 32 are molded at the upper end of the solenoid valve assembly with a molding resin to form a molded connector 33.

The ball valve 4A is a plunger 4 made of a magnetic material.
A rod 5 having one end joined to the plunger 4, a ball 6 joined to the other end of the rod 5, and a guide ring 3 made of a non-magnetic material fixed to an upper end opening of the plunger 4.
And 4. The guide ring 34 is attached to the core 2
And the ball 6 is guided by an inner wall surface 38 of a cylindrical fuel swirl element 37 inserted into the hollow inner wall surface 36 of the valve guide 7, respectively. I have.

The valve guide 7 has a cylindrical fuel swirl element 37 for guiding the ball 6, followed by the ball 6.
Is formed, and the sheet surface 9 is formed.
An orifice 8 (fuel injection hole) is formed in the center of the hole. Further, the valve guide 7 has a tapered surface inclined at a desired inclination angle on the seat surface 9 side except for a part of the flat portion on the outlet side of the orifice 8. An O-ring 39 for sealing the fuel is interposed between a socket (not shown) and the outer peripheral surface of the valve guide 7. In this embodiment, an O-ring receiving portion 40 is formed as an annular groove on the outer periphery of the valve guide 7.

Next, the method of assembling the fuel injection valve and the structure of the fuel swirl element 37 will be described. First, a method of assembling the assembly of the electromagnet units will be described. Electromagnetic coil assembly 16
After the O-ring 19 is attached to the terminal 18 of the core 2, the terminal 18 is inserted into the hole 17 of the flange of the core 2. Next, the collar 20 is inserted from above the terminal 18. Thereafter, an O-ring 13 is attached to the lower part of the outer periphery of the plug body of the core 2 and fitted into the yoke 3. In this state, the core contact surface 4 at the upper end edge of the inner periphery of the yoke 3
1 is pressed in the axial direction, the material of the yoke 3 is radially poured into the groove 42 provided on the outer periphery of the plug body portion of the core 2 by plastic flow, and is fixed by the tightening force. Joining by a so-called metal flow is performed.

The ball valve 4A guides the ball 6 on the inner wall surface 38 of the fuel swirling element 37 and guides the guide ring 34 of a non-magnetic material on the inner wall surface 35 at the tip end of the core 2. Eventually, it will be guided at two places and will advance and retreat in the axial direction. For this reason, it is necessary to accurately obtain the coaxiality between the inner diameter of the receiving portion of the valve guide 7 of the yoke 3 and the inner wall surface 35 of the core 2. Therefore, the receiving portion 30 of the valve guide 7
The metal flow is performed in a state where the inner diameter of the core 2 and the inner wall surface 35 of the core 2 are accurately supported. Then, the terminal 3 is connected to the terminal 18.
2 is fixed by caulking, soldering, welding, or the like, and then molded with resin.

Next, the assembly of the valve guide assembly will be described. The valve guide assembly includes the ball valve 4A, the fuel swirling element 37, and the valve guide 7. The ball valve 4A welds the ball 6 and the rod 5 made of quenched and hardened stainless steel by resistance welding, laser welding, or the like. Next, the inner wall of the plunger 4 is fixed to the other end of the rod 5, the plunger 4, and the groove 43 provided on the outer periphery of the rod 5 by fluid pressure bonding of the inner wall with a metal flow. The coupling between the guide ring 34 and the plunger 4 is as follows.
By receiving the surface 44 of the plunger 4 on the ball valve side, the guide ring contact portion 45 at the inner peripheral edge of the plunger 4 is pressed in the axial direction to apply a radial tightening force to the guide ring 7 so that the metal flow is prevented. Can be combined.

The fuel swirling element 37 is formed into a cylindrical shape using a sintered alloy, and is fixed to the inner wall surface 36 of the valve guide 7 by pressure bonding. That is, the outer peripheral surface 46 of the fuel swirl element 37
(4 places) are flow bonded to the groove 47 of the valve guide 7 by metal flow (see FIG. 2).

As shown in FIG. 2, the fuel swirling element 37 has an axial groove 48 and a radial groove 49 for applying a swirling force to the fuel. The fuel that has passed through the axial groove 48 vertically downward flows in the radial groove 49 horizontally by changing the flow direction by 90 ° at the entrance of the radial groove 49.

FIG. 3 is a perspective view of the flow path from the radial groove 49 of the fuel swirl element 37 to the orifice 8 in the fuel injection valve according to the first embodiment of the present invention. The radial groove 49 is
It is formed at a position eccentric from the center without passing through the axial center of the valve body. As a result, a turning force is applied to the fuel in the radial groove, and the fuel spreads into the atmosphere while turning from the orifice 8. The radial groove 49 has a groove height H and a groove width W.
Processed to be larger than FIG. 4 shows the relationship between the groove height H and the groove width W of the radial groove 49. (A) is an example of a conventional groove shape, and shows a case where W / H = 2, that is, W> H. On the other hand,
(B) is an example of the groove shape of the present invention, W / H = 0.5
, That is, W <H. Assuming that the distance from the axial center of the valve body to the outermost wall 56 of the radial groove 49 is R (see FIG. 5), the swirling energy imparted to the fuel is equal to the radial groove eccentricity L = R−W / 2. Proportional. Thus, in order to give a large swirling energy to the fuel flow under a constant R, the groove width W is reduced and the height H is increased accordingly. The sectional area WH of the groove is the same as that of the conventional fuel injection valve.

The valve guide assembly provided with the fuel swirling element 37 as described above is inserted into the valve guide receiving portion 30 of the yoke 3 of the electromagnet assembly together with the stopper 29 shown in FIG. The two are fixed by allowing the inner peripheral wall of the tip of the yoke 3 to flow into the groove 53 provided on the outer periphery of the valve guide 7 by plastic flow with a metal flow. At that time, the stopper 29 prevents the tip of the plunger 4 from directly contacting the tip of the core 2 when the movable portion is sucked.
The thickness is set so as to have a predetermined gap (referred to as an air gap).

Next, an adjuster 11 having a spring 10 at its tip and an O-ring 12 mounted on its outer periphery is inserted into a hole provided at the center of the core 2 of the electromagnet assembly from a direction opposite to the valve guide 7. At about the same time, a filter 31 and an O-ring 24 are attached to the outer periphery of the yoke 3 and are temporarily stored in an unillustrated employment where the injection flow rate test is started.

Next, the injection flow rate test will be described. First, measurement is performed in a state where the movable part is at full stroke, and it is confirmed that the injection flow rate at that time becomes a specified injection amount. Thereafter, the responsiveness of the movable portion is determined by changing the load of the spring 10 so that the injection flow rate at a constant cycle and a constant valve opening time becomes a specified injection flow rate. Thereafter, the outer periphery of the upper projecting portion 54 of the core 2 is pressed in the radial direction from the hole of the mold resin, and the inner wall of the core 2 is fixed to the groove 55 of the adjuster 11 by being incorporated therein. The assembly of the electromagnetic fuel injection valve of the present embodiment is completed by the above procedure.

Next, FIGS. 5 and 6 show the results of fluid analysis of the internal flow path of the electromagnetic fuel injection valve of this embodiment in comparison with the conventional fuel injection valve. FIG. 5 shows a radial groove 49 of the fuel swirl element.
FIG. 3 shows a plan view of a flow path from the flow path to the orifice 8 and a flow state. (A) is an example of a conventional groove shape, and shows a case where W / H = 2, that is, W> H. On the other hand, (b) is an example of the groove shape of the present invention, and when W / H = 0.5, that is, W <
H is shown. It can be seen from the velocity vector in the figure that the fuel injection valve (b) shown in the present embodiment has a larger swirling energy of the fuel flow from the radial groove 49 to the orifice 8. FIG. 6 shows the turning speed of the fuel flow at the outlet of the orifice 8.
The horizontal axis represents the radial distance from the wall of the orifice 8 to the center, and the vertical axis represents the turning speed. The solid line in the figure shows the result of the fuel injection valve (b) shown in the present embodiment, and the broken line shows the result of the conventional fuel injection valve (a).

As is clear from FIGS. 5 and 6, the radial grooves 4
The electromagnetic fuel injection valve of the present embodiment in which the height H of the fuel injection valve 9 is larger than the width W can give a larger swirling energy to the fuel flow than the conventional fuel injection valve. This allows
The injection angle of the fuel injected from the orifice 8 can be increased, and the atomization of the fuel can be promoted.

Although the radial cross section of the radial groove 49 is rectangular in this embodiment, it may be other than rectangular, for example, an elliptical shape as shown in FIG. In this case, it is assumed that the major axis of the ellipse is the height H and the minor axis is the width W.

FIG. 8 is a view showing the shape of the radial groove of the fuel swirling element according to the second embodiment in the fuel injection valve of the present invention. Since the same electromagnetic fuel injection valve as in the first embodiment is used, the description of the components will be omitted.

As shown in FIG. 8, in this embodiment, the fuel swirling element is machined so that the cross-sectional shape of the radial groove is asymmetric with respect to the center of the cross-section. (A) shows a groove having a rectangular shape and being symmetrical with respect to the center of the groove cross section. In this case, the distance between the groove cross-sectional center P and the outermost wall 56 of the groove is W / 2, which is half the groove width W. (B) is an example of the groove shape of the present invention, and the shape of the groove is asymmetric with respect to the center of the groove cross section. The groove of the embodiment is formed by a combination of a rectangle and a quarter of a circle, and has a cross-sectional area of WH equal to (a). In this case, the distance between the groove cross-sectional center P and the outermost wall 56 of the groove is W which is half the groove width W.
/ 2. (A) and (b) have the same groove width W, but in the present invention of (b), the groove cross-sectional center P is closer to the outermost wall 56. That is, the eccentricity L of the groove is larger in FIG.

With the above configuration, the electromagnetic fuel injection valve of the present embodiment can give a larger swirling energy to the fuel flow than the fuel injection valve having a rectangular groove in cross section. Thus, the injection angle of the fuel injected from the orifice 8 can be increased, and the atomization of the fuel can be promoted.

FIG. 9 is a view showing the shape of the radial groove of the fuel swirl element according to the third embodiment in the fuel injection valve of the present invention. Since the same electromagnetic fuel injection valve as in the first embodiment is used, the description of the components will be omitted. As shown in FIG. 9, in the third embodiment, the cross-sectional shape of the radial groove of the fuel swirling element is processed so as to be trapezoidal with respect to the center of the cross-section. In this embodiment, the height H ′ of the radial groove on the outermost wall 56 side, the height of the innermost wall side opposite thereto is H (H ′> H), and the groove width is W
And In this case, the groove cross-sectional center P and the outermost wall 56 of the groove
Is smaller than W / 2, and the eccentricity L of the groove is larger than that of the conventional groove (see FIG. 4A).

With the above configuration, the electromagnetic fuel injection valve of the present embodiment can give a larger swirling energy to the fuel flow than the conventional fuel injection valve. Thus, the injection angle of the fuel injected from the orifice 8 can be increased, and the atomization of the fuel can be promoted.

In the first to third embodiments, the electromagnetic fuel injection valve for a single-point fuel injection device has been described. However, the present invention is not limited to this, and the same operation and effects as those of the present embodiment can be obtained. Is generally applied to a fuel injection valve as long as the following is obtained. Further, in the above embodiment, the example of the ball valve is described as the valve body, but the valve body of the present invention is not limited to the ball valve.

[0039]

As described above, according to the present invention, a fuel injection valve for obtaining swirl fuel upstream of a valve seat can impart a large swirl energy to a fuel flow. In addition, the injection angle of the fuel injected from the orifice can be increased, and the atomization of the fuel can be promoted. Further, if the present fuel injection valve is applied to an engine, the practical effect will be extremely high.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electromagnetic fuel injection valve showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a fuel swivel element and a valve guide assembly structure of the fuel injection valve of FIG. 1;

FIG. 3 is a perspective view of a flow path from a radial groove to an orifice of the fuel swirl element of the first embodiment in the fuel injection valve of the present invention.

FIG. 4 is a diagram showing a relationship between a groove height and a groove width of a radial groove.

FIG. 5 is a plan view of a flow path from a radial groove of the fuel swirling element to an orifice and a view showing a flow state.

FIG. 6 is a view showing a swirl speed distribution at the orifice outlet of the fuel swirl element of the first embodiment in the fuel injection valve of the present invention in comparison with a conventional fuel injector.

FIG. 7 shows a case where the radial cross section of the fuel swirl element according to the first embodiment of the fuel injection valve of the present invention is elliptical.

FIG. 8 is a view showing a shape of a radial groove of a fuel swirling element according to a second embodiment in the fuel injection valve of the present invention.

FIG. 9 is a view showing a shape of a radial groove of a fuel swirling element according to a third embodiment in the fuel injection valve of the present invention.

[Description of Signs] 2 ... core, 3 ... yoke, 4 ... plunger, 4A ... ball valve, 5 ... rod, 6 ... ball, 7 ... valve guide, 8 ...
Orifice, 9 ... Seat surface, 15 ... Electromagnetic coil, 16 ...
Electromagnetic coil assembly, 34 guide ring, 37 fuel swivel element, 38 inner wall surface, 48 axial groove, 49 radial groove, 49 outermost wall of radial groove.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ayumu Miyajima 502, Kandatecho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. Inside the Machinery Research Laboratory (72) Inventor Toru Ishikawa 2520 Odaiba, Hitachinaka-shi, Ibaraki F-term within the Hitachi, Ltd. Automotive Equipment Group (reference) 3G066 AA02 AB02 AD12 BA03 CC06U CC14 CC15 CC43 CC48 CD14 CD19 CD30 CE22

Claims (3)

[Claims] A nozzle body having a fuel injection hole and a valve seat formed upstream of the fuel injection hole; a valve body driven to be in contact with or apart from the valve seat; A fuel swirl element located upstream of the seat and providing a swirl force to the fuel, wherein the fuel swirl element is eccentric from the axial center of the valve body to generate a swirl flow in the fuel. A fuel injection valve having a swirl groove at a predetermined position, wherein a ratio between a groove height and a groove width of the swirl groove is 1 or more. 2. A nozzle body having a fuel injection hole and a valve seat formed upstream of the fuel injection hole, a valve body driven to be in contact with or apart from the valve seat, and the valve A fuel swirl element located upstream of the seat and providing a swirl force to the fuel, wherein the fuel swirl element is eccentric from the axial center of the valve body to generate a swirl flow in the fuel. A fuel injection valve having a swirl groove at a predetermined position, and wherein the cross-sectional shape of the swirl groove is asymmetric with respect to the center of the cross section. 3. A fuel injection valve according to claim 2, wherein said swirl groove has a trapezoidal cross section.