WO2000022295A1

WO2000022295A1 - Fuel injection valve for diesel engine

Info

Publication number: WO2000022295A1
Application number: PCT/JP1998/004566
Authority: WO
Inventors: Jun Arimoto
Original assignee: Jun Arimoto
Priority date: 1998-10-09
Filing date: 1998-10-09
Publication date: 2000-04-20
Also published as: JP4223193B2; EP1041274B1; DE69841890D1; EP1041274A1; EP1041274A4

Abstract

A fuel direct injection valve for diesel engines, in which a needle valve is rotated by first and second serrations formed in an edge portion of an opening of a nozzle body and in a base portion of the needle valve and by third and fourth serrations formed on the axially opposite side to the first and second serrations, and in which as the needle valve rotates, the area of the portion where a first nozzle hole formed in the nozzle body overlaps with second nozzle hole formed in a rotary valve increases. In the low load operation region, the area is small. In the high load operation, the area increases with the fuel injection pressure, so that the complete penetration force of the fuel injection can be large and constant, and the fuel effectively contacts and strikes squished air and satisfactory mixes with the air. This minimizes the delay of ignition and enhances the combustion, low-noise, and exhaust emission performances.

Description

m Itoda

Diesel engine fuel injection valve

The present invention relates to a fuel injection valve for a diesel engine.

The general structure of a fuel injection valve for a diesel engine, especially for a direct injection engine, is as follows: a dollar valve is inserted into a nozzle body having a plurality of injection holes so that it can be freely lifted in the axial direction, and fuel is introduced into the nozzle body. When fuel is introduced from the passage, the fuel pressure causes the dollar valve to lift, and the fuel passes through the gap between the peripheral wall of the needle valve and the inner wall of the nozzle body from the plurality of injection holes into the combustion chamber (piston cavity). Injected to.

In the conventional diesel fuel injection valve, since the opening area of the injection hole is constant, a sufficiently large penetration force can be obtained when the fuel pressure is high and the load is high, but the penetration is performed when the fuel pressure is low and the load is low. Since the power is weak, the fuel is not sufficiently atomized and atomized, and the fuel is not sufficiently mixed with air and burns. As a result, ignition delay is increased, resulting in an increase in combustion noise and exhaust gas. Mission performance (especially smoke) was degraded.

In addition, by rotating a rotary valve using a pulse motor or the like that forms a fuel passage so that the amount of throttle between the nozzle hole of the nozzle body and the nozzle hole changes with rotation, the area of the nozzle hole can be reduced in a low-load area. However, the provision of such a pulse motor increases the size and cost of the fuel injection valve, as well as complicates the structure and secures reliability. Difficult to do. The present invention has been made in view of such a conventional problem. From the low load region to the high load region, the fuel spray quickly and sufficiently mixes with the air in the combustion chamber to obtain good flammability, The objective is to obtain exhaust emission performance, which can greatly contribute to performance improvement especially at idle and in low load areas.

In addition, fuel pressure was used without providing a separate drive device such as a pulse motor. An object of the present invention is to provide a fuel injection valve having a simple structure that does not involve an increase in size simply by forming an automatic mechanical rotation mechanism, and that the above performance can be obtained. In addition, by efficiently using the penetration force and squish of the spray to mix fuel and air, it is possible to promote the reduction of the piston height of the piston cavity and reduce the height of the engine. Aim.

In order to achieve the above object, the fuel injection valve of the diesel engine according to the present invention is configured such that when fuel is introduced into a nozzle holder and a fuel introduction passage formed inside the nozzle body, the fuel is injected into the nozzle body by fuel pressure. The inserted diesel valve lifts in the axial direction, and fuel passes through the gap between the needle valve and the nozzle body to inject fuel into the combustion chamber from an injection hole formed in the nozzle body. A fuel injection valve,

A first serration that is inclined with respect to the axial direction is provided at the edge of the end face opening that engages with the nozzle holder of the nozzle body, and

A second serration is formed on the outer peripheral surface of the base end portion of the needle valve, the second serration engaging with the first selection, and rotating the needle valve around the axis in accordance with the axial movement of the needle valve. ,

A tip portion of the needle valve on the injection hole side is formed with a gap between the tip end of the nozzle body and an inner surface of the tip portion on the injection hole side, and a bag-shaped rotary valve fitted to the tip portion of the needle valve is provided. Arrange,

The tip outer peripheral surface of the needle valve and the inner peripheral surface of the rotary valve are engaged with each other with a space therebetween, and are axially aligned with the first selection and the second selection. Forming a third selection and a fourth serration, each of which slopes to the opposite side,

And, with respect to the plurality of first injection holes formed in the nozzle body, the overlapping area increases in accordance with the rotation amount of the rotary valve that increases as the axial lift amount of the needle valve increases. It is configured to have two holes. According to this configuration, when fuel is introduced into the fuel introduction passage formed inside the nozzle holder and the nozzle body, when the needle valve fitted into the nozzle body is lifted in the axial direction by the fuel pressure, the first The rotation of the needle valve in one direction around the axis by the engagement of the second selection and the second selection, and the rotary valve whose lift is regulated by the fuel pressure are the third serration and the fourth serration. The engagement with the serration causes the needle valve to rotate relative to the needle valve about the axis in the same direction as the rotation direction of the needle valve.

In other words, the rotary valve rotates around its axis by the amount of rotation obtained by adding the amount of rotation caused by the engagement of the first and second serrations and the amount of rotation caused by the engagement of the third and fourth serrations. The amount of rotation is small in the low load region where the fuel injection amount is small, because the fuel pressure is low and the lift amount of the needle valve is small. The fuel pressure increases due to the increase in load, and the lift amount of the needle valve increases. It increases with the increase of.

Then, as the amount of rotation of the rotary valve increases, the overlapping area between the first injection hole and the second injection hole increases.

After passing through the gap between the needle valve and the nozzle body, the fuel passes through the gap between the third selection and the fourth selection and reaches the inside of the rotary valve. The fuel is injected into the combustion chamber from a portion where the second injection hole and the first hole of the nozzle body overlap.

Here, in the low-load region where the fuel pressure is low, by reducing the overlapping area between the injection holes, the penetration force of the fuel increases, atomization and atomization are promoted, and the amount of air that comes into contact increases. It is quickly mixed and burned. As a result, ignition delay can be reduced, good combustion properties can be obtained, and quietness and exhaust emission (especially smoke) performance are also improved.

In addition, as the load increases and the fuel injection amount increases, the overlapping area between the injection holes increases continuously, so the injection zone is expanded while maintaining the penetration force, and the injection amount is increased according to the injection amount. Since it mixes with air, optimal fuel spray is obtained over the entire area, fuel and air are mixed well, and good combustibility and exhaust emission performance are obtained. Can be

The improvement in performance was achieved with a simple structure without increasing the size by simply forming an automatic mechanical rotation mechanism using fuel pressure without providing a separate drive device such as a pulse motor. can do.

Even if the maximum lift amount of the needle valve is limited to a relatively small value, the rotary valve can rotate the engagement amount between the first and second serrations, the third serration and the fourth serration. It can be rotated with a large amount of rotation, including the amount of rotation due to engagement with one part, so that the dynamic range of the overlapping area between the injection holes can be sufficiently large, and the optimal overlapping area can be adjusted according to the load. Obtainable.

Further, the second injection hole is elongated and opened in the rotating direction of the rotary valve, and the first injection hole is opened in a substantially circular shape having a diameter larger than the width of the second injection hole on the short side. Is also good.

With this configuration, the fuel spray from the first injection hole is formed to spread flat in the circumferential direction, and efficiently collides with the squish generated in the combustion chamber in the compression stroke, so that the fuel and the air are more effectively used. The flammability, quietness, exhaust emission performance, etc. can be enhanced as much as possible.

In addition, the amount of fuel spray that spreads in the circumferential direction increases with an increase in the amount of fuel injection. You can get the status.

In addition, since this method mainly uses the strong penetration force and squish of the spray to enhance the mixability of fuel and air, it can promote a shallower cavity, which in turn results in higher piston height and engine height. Can be reduced.

Further, the first serration is formed on an inner peripheral surface of a guide ring which is engaged with a groove formed on an opening edge of the nozzle body in a direction around an axis so as to prevent rotation.

In this way, it is possible to add directly to the edge of the first serration, but it is difficult to increase the machining accuracy and the cost is increased. On the other hand, the guide ring, which has the first selection formed on the inner peripheral surface of the guide ring, can be manufactured at a low cost simply by engaging the groove that can be easily machined into the opening edge of the nozzle body. It can be implemented at low cost with a simple configuration, and accuracy can be easily secured.

In addition, the first serration is formed on an inner peripheral surface of a guide ring that freely engages with a groove formed in an opening edge of the nozzle body in a direction around an axis by a predetermined angle.

A guide ring spring for biasing the guide ring in a direction opposite to the rotation direction of the needle valve during the axial lift;

In addition, a slit is provided in the peripheral wall of the needle valve, the depth of which increases in the rotation direction when the needle valve is lifted in the axial direction, and the rotation force in the rotation direction acts on the needle valve by the received fuel pressure. It may be configured.

According to this configuration, the rotational force in the rotational direction at the time of the axial lift acting on the needle valve increases in accordance with the increase in the fuel pressure received by the slit formed in the peripheral wall of the needle valve, and the guide ring is moved. The guide ring spring rotates in the same direction as the rotation direction against the urging force of the guide ring spring, and rotates the dollar valve in the same direction integrally with the guide ring.

As a result, even if the lift amount of the needle valve cannot be made large, the rotation amount can be made sufficiently large compared to the fuel pressure, and at the same time, the fuel injection valve with low fuel pressure is closed by the action of the guide ring spring. At the time of valve opening, the guide ring, the needle valve, and the rotary valve can be surely kept in the closed position.

Also, a cone taper that is in close contact with the needle valve at the base end side of the third selection forming portion and the base end side of the nozzle body 內 peripheral surface with respect to the rotary valve mounting portion when the needle valve is not lifted. A surface may be formed. In this way, when the fuel injection valve is closed, the needle valve and the cone taper surface formed on the nozzle body are in close contact with each other, and the conduction of fuel to the injection hole is cut off. Can be closed.

FIG. 1 is a longitudinal sectional view of a main part showing a state when a fuel injection valve of a diesel engine according to an embodiment of the present invention is closed.

FIG. 2 shows a state where the fuel injection valve is opened, in which (A) is a longitudinal sectional view of a main part and (B) is a partial plan view.

Fig. 3 shows a sectional view taken along the line AA, a view taken in the direction of the arrow B and a fuel spray state of the combustion chamber in Fig. 1 or Fig. 2 at each operating position of the fuel injection valve. (B) shows the state at low load such as when the injection hole is slightly open, such as at idle, (C) shows the state at medium load when the injection hole is half open, and (D) shows the state at full load when the injection hole is fully open. FIG.

FIG. 4 shows a fuel injection valve of a diesel engine according to a second embodiment of the present invention. (A) is a longitudinal sectional view of a main part, (B) is a partial plan view, and (C) is a partial cross section. FIG. FIG. 5 is a partial plan view of a fuel injection valve of a diesel engine according to a modification of the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIGS. 1 (when the valve is closed) and FIG. 2 (when the valve is open) showing the tip structure of the fuel injection valve of the diesel engine according to the present invention, the nozzle body 1 is axially detented by a nozzle holder (not shown). And are fastened via bolts and nuts arranged outside.

A fuel introduction passage 11 is formed inside the nozzle body 1 so as to overlap with a fuel passage formed inside the nozzle holder, and a downstream end of the fuel introduction passage 11 is formed in a fuel reservoir 12 formed on an inner peripheral surface of an intermediate portion of the nozzle body 1. Reach. In addition, a plurality of injection holes (first injection holes) 13 are formed at the tip of the nozzle body 1 at intervals in the circumferential direction.

A groove 14 is formed at the opening edge on the base end side of the nozzle body 1 formed in the same manner as in the related art, and a first selection 15a inclined on the inner peripheral surface with respect to the axial direction is formed. The guide ring 15 is locked in the groove 14 by turning it around the axis as shown in the figure. Combine.

On the other hand, the outer peripheral surface of the proximal end of the needle valve 2 fitted into the nozzle body 1 is engaged with the first selection 15a of the guide ring 15, and the axial direction of the needle valve 2 is A second serration 21 for rotating the needle valve 2 about an axis in accordance with the movement is formed.

On the other hand, the tip of the injection valve side of the needle valve 2 is formed with a gap between the tip end of the nozzle body 1 and the surface of the injection port side of the nozzle body 1, and the bag is fitted to the tip of the needle valve 2. A rotary valve 3 is installed.

The tip outer peripheral surface of the needle valve 2 and the inner peripheral surface of the rotary valve 3 are engaged with each other with a gap therebetween, so that the first serration 15a and the second serration 21 are axially engaged with each other. A third serration 22 and a fourth serration 31 are formed, respectively, which are inclined to the opposite sides with respect to. Here, the gap between the third serration 22 and the fourth serration 31 is formed along the longitudinal direction of the serration only between the peaks of the projections and the valleys of the grooves, so that fuel can pass through this gap. At the same time, there should be almost no gap in the circumferential direction so that there is no backlash in rotation. Further, a plurality of injection holes 13 (first injection holes) formed in the nozzle body 1 are located on the injection hole side of the fourth serration 31 of the rotary valve 3 in the axial direction of the needle valve 2. A configuration in which a plurality of injection holes 32 (second injection holes) whose overlapping area increases according to the rotation amount of the rotary valve 3 that increases as the amount increases.

Here, the injection holes 32 (second holes) formed in the rotary valve 3 open in an elongated ellipse (only both ends are circular) in the rotation direction of the rotary valve 3, and the nozzle body 1 The injection hole 13 (first injection hole) formed in the opening is formed in a circular shape having a diameter larger than the width of the short side of the injection hole 32 (second injection hole).

In addition, the needle valve 2 is located on the base end side from the portion where the third selection 22 is formed, and on the inner peripheral surface of the nozzle body 1 on the base end side with respect to the rotary valve 3 mounting portion when the needle valve is not lifted. Cone taper surfaces 23 and 16 are formed in close contact with the surface. Next, the operation of the fuel injection valve thus configured according to the present invention will be described. When the fuel injection valve is closed, that is, when the fuel supply pressure to the fuel introduction passage 11 is low enough not to cause fuel injection, the return valve (not shown) urges the needle valve 2 toward the injection hole side by a return spring. The cone taper surface 23 of the needle valve 2 and the cone taper surface 16 of the nozzle body 1 are in pressure contact with each other, and completely shut off the fuel introduction passage 11 from the injection hole side.

On the other hand, in the valve-closed state, as shown in FIG. 3 (A), the injection hole 13 (first injection hole) and the injection hole 32 (second injection hole) are rotated so as not to overlap at all. Rotation position of valve 3 is set. As a result, it is possible to reliably maintain the valve-closed state, and it is also possible to prevent the fuel from being left behind.

When fuel is supplied to the fuel introduction passage 11 at a pressure equal to or higher than a predetermined pressure, the fuel pressure is applied to the stepped pressure receiving surface of the needle valve 2 in the fuel reservoir 12, thereby reducing the urging force of a return spring (not shown). In response, needle valve 2 lifts in the axial direction.

When the needle valve 2 is lifted, the needle valve 2 rotates in one direction around the axis by the engagement between the first serration 15a and the second serration 21. In addition, as will be described later, the single tally valve 3 whose lift is regulated by receiving the fuel pressure, rotates the needle valve 2 by engagement of the third serration 22 and the fourth selection 31. In the same direction as the direction, relative rotation about the axis with respect to the dollar valve 2. That is, the rotary valve is rotated by adding a rotation amount due to the engagement between the first serration and the second selection and a rotation amount due to the engagement between the third serration and the fourth selection. Rotate around the axis by the amount.

When the single tally valve 3 rotates around the axis in this manner, the injection hole 32 and the injection hole 13 overlap, and the overlap area increases the lift amount of the needle valve 2 due to an increase in fuel pressure. Increase according to In other words, the overlap area is controlled to be small when the fuel pressure is low at idle or in a low load region, and the overlap area is controlled to increase as the fuel pressure increases as the load increases.

On the other hand, the lift of the needle valve 2 causes the conical taper surfaces 23 and 16 to mutually reciprocate. The fuel is guided to the injection hole side through the gap between the needle valve 2 and the nozzle body 1 as it separates, and is further passed through the gap between the third serration 22 and the fourth selection 31 to form a tally valve. The fuel reaches the inner space of 3 and is injected into the combustion chamber from the overlapping portion of the injection holes 32 and 13.

Here, when the fuel pressure is low at idle or in a low load region, as shown in Fig. 3 (B), by reducing the overlapping area between the injection holes, the penetration force of the fuel increases, resulting in atomization and atomization. This promotes gasification and increases the amount of air that comes in contact with it. In particular, in the present embodiment, the inner hole 32 is elongated in the rotation direction of the rotary valve 3, and the outer hole 13 is open in a circular shape having a diameter larger than the width of the shorter side of the hole 32. Therefore, the fuel spray is formed to spread flat in the circumferential direction, and efficiently collides with the squish generated in the combustion chamber in the compression stroke, so that the fuel and the air can be more effectively mixed.

As a result, the ignition delay can be sufficiently reduced, good combustion properties can be obtained, and quietness and exhaust emission (especially, smoke) performance are also improved. In addition, as the load increases and the fuel injection amount increases, the overlapping area between the injection holes increases continuously, so the injection zone is expanded while maintaining the penetration force, and the injection amount is increased according to the injection amount. Since it mixes in contact with air, the optimum fuel spray is obtained over the entire area, and the fuel and air mix well, resulting in good combustion performance and exhaust emission performance. FIG. 3 (C) shows a state in which the degree of polymerization between the pores is about 50%, and FIG. 3 (D) shows a state in which 100% of the polymerization has been performed at full load.

In addition, the design of the fuel injection valve of the conventional type only requires additional processing of four types of serrations, grooves 14, etc., and a design change that only installs the guide ring 15, the guide ring spring 33, and the single valve 3 Therefore, there is no need to provide a separate drive device such as a pulse motor, and it can be implemented at low cost without increasing the size, and has excellent reliability.

In addition, as described above, squish is mainly used to enhance the mixability between fuel and air, and the spray position is farther away, so the maximum amount of intake air is secured without considering intake swirl By using the intake port to It is possible to promote a shallower dish, which in turn reduces the height of the piston and engine, and increases the specific output by increasing the amount of fuel injected by holding more air in the combustion chamber. Becomes

Next, a second embodiment of the present invention will be described with reference to FIG. In the figure, the same components as those of the first embodiment are denoted by the same reference numerals.

In the present embodiment, a groove 41 for engaging the guide ring 15 formed on the opening edge on the base end side of the nozzle body 1 is engaged with the guide ring 15 so as to rotate freely by a predetermined angle around the axis. The guide ring 15 is formed so that the engagement portion with the protrusion 15b is larger in the circumferential direction than the circumferential width of the protrusion 15b, and the guide ring 15 has an axial direction for accommodating a guide ring spring 16 described later. The depth has been increased.

One end engages with the guide ring 15 in the groove 41 below the guide ring 15, and the other end positions and engages with the groove 41. When the guide ring 15 is lifted in the axial direction of the needle valve 2, The guide ring spring 42 consisting of a torsion coil panel is urged in the opposite direction (clockwise as viewed from above).

Further, a plurality of slits 43 having a windmill-like cross section whose depth increases in the rotation direction during the axial lift of the needle valve 2 are formed on the peripheral wall of the needle valve 2 at equal intervals in the circumferential direction. . The windmill-shaped slit 43 causes the needle valve 2 to exert a rotational force in the rotational direction (counterclockwise as viewed from above) on the needle valve 2 by the fuel pressure received through the fuel reservoir 12. Other configurations are the same as those of the first embodiment. With such a configuration, as the fuel pressure received by the slit 43 of the twenty-one valve 2 via the fuel reservoir 12 increases, the rotational force in the rotational direction at the time of the axial lift acting on the needle valve 2 as the fuel pressure increases. The guide ring 15 rotates in the same direction as the above-mentioned rotation direction by staking the urging force of the guide ring spring 42, and rotates the needle valve 2 in the same direction as the guide ring 15 integrally.

As a result, even when the lift amount of the needle valve 2 cannot be increased, the rotation amount can be sufficiently increased compared to the fuel pressure, and at the same time, the fuel injection valve having a low fuel pressure can be provided by the action of the guiding spring 42. Guide ring 15 when valve is closed Thus, the needle valve 2 and the rotary valve 3 can be reliably rotated and held at the valve closing position.

FIG. 5 shows a modification of the second embodiment, in which a groove 51 for engaging a guide ring 15 is provided at an opening edge of the nozzle body 1, and the guide ring 15 is rotated by a predetermined angle around an axis. The engagement portion of the guide ring 15 with the protrusion 15b is formed to be larger in the circumferential direction than the circumferential width of the protrusion 15b so that the guide ring 15 can be freely engaged. The guide ring spring 52 that urges in the direction opposite to the rotation direction of the guide ring is attached to a portion of the groove 51 that engages the protrusion 15 b of the guide ring 15. And a leaf spring or the like.

As described above, the present invention can be applied as a fuel injection valve of a direct injection type diesel engine for an automobile or the like, and can be applied to a pipeline type fuel injection device or a recent common rail type fuel injection device or a unit type fuel injection device. Applicable as a fuel injection valve.

Claims

Scope of word blue

(1) When fuel is introduced into the fuel introduction passage formed inside the nozzle holder and the nozzle body, the fuel pressure causes the 21 dollar valve inserted into the nozzle body to be lifted in the axial direction, and the fuel A diesel fuel injection valve having a structure in which fuel is injected into a combustion chamber from an injection hole formed in a nozzle body through a gap between a needle valve and a nozzle body,

A second engagement portion that engages with the first selection on an outer peripheral surface of a base end portion of the needle valve, and rotates the needle valve around an axis in accordance with the axial movement of the needle valve;

Form two serrations,

A tip portion on the injection hole side of the needle valve is formed so as to have a gap between the inner surface of the tip portion on the injection hole side of the nozzle body, and a bag-shaped rotary valve fitted to the tip portion of the needle valve is provided. Set up

The tip outer peripheral surface of the needle valve and the inner peripheral surface of the rotary valve are engaged with each other with a gap therebetween, and are opposite to the first and second serrations with respect to the axial direction. Forming a third selection and a fourth selection, respectively,

In addition, for a plurality of first injection holes formed in the nose body, a polymerization area increases according to a rotation amount of a single tally valve which increases as an axial lift amount of the needle valve increases. A fuel injection valve for a diesel engine, wherein a second injection hole is provided.

(2) The second injection hole is elongated in the rotation direction of the rotary valve, and the first injection hole is opened in a substantially circular shape having a diameter larger than the width of the short side of the second injection hole. 2. The fuel injection valve according to claim 1, wherein the fuel injection valve is a fuel injection valve.

(3) The first selection is formed on an inner peripheral surface of a guide ring which is engaged with a groove formed in an opening edge of the nozzle body in a direction around an axis so as to prevent rotation. 3. The fuel injection valve for a diesel engine according to claim 1 or claim 2.

(4) The first serration is formed on an inner peripheral surface of a guide ring which freely engages with a groove formed on an opening edge of the nozzle body in a direction around an axis by a predetermined angle.

A guide ring spring for biasing the guide ring in a direction opposite to a rotation direction of the needle valve during an axial lift;

And a slit on the peripheral wall of the needle valve, the depth of which increases in the rotation direction when the needle valve is lifted in the axial direction, and which applies a rotational force in the rotational direction to the needle valve by the received fuel pressure. The fuel injection valve for a diesel engine according to claim 1 or 2, wherein the fuel injection valve is provided.

(5) At the base end side of the third serration forming part of the needle valve, and at the base end side of the inner surface of the nozzle body with respect to the rotary valve mounting part, the needle valve is in close contact with each other when the needle valve is not lifted. The fuel injection valve for a diesel engine according to any one of claims 1 to 4, wherein a single tapered surface is formed.