JP4191761B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve for in-cylinder injection that is mainly used in a fuel supply system of an internal combustion engine and injects fuel directly into a combustion chamber.

In recent years, in-cylinder direct injection internal combustion engines have been aiming at fuel injection control that approaches the ideal air-fuel ratio in all driving situations, and it is necessary to meet the operating conditions so that stable combustion can be achieved from low load to high load. There is a demand for a fuel injection valve capable of obtaining a spray shape.
The electromagnetic fuel injection valve adjusts the fuel injection amount according to the energization time of the solenoid device. However, due to the fact that sufficient energization time cannot be secured in the high speed range and the sliding response of the valve body is limited, in recent years, variable fuel pressure control that changes the fuel pressure (fuel pressure) is used in combination, and the injection range The method of enlarging is becoming common.

  An example of a conventional fuel injection valve for in-cylinder injection is shown in FIG. The figure shows the tip part of the valve device of the fuel injection valve, where (a) is a side cross-sectional view and (b) is a cross-sectional view of (a) as viewed from the arrow bb. As shown in the figure, the fuel injection valve 30 includes a fuel injection valve main body 31, a valve seat 32 provided at the tip thereof and having a fuel injection hole 32 a at the center, and a solenoid seat (not shown) driven by a solenoid device (not shown). A needle valve 33 that opens and closes the fuel injection hole 32a in contact with the nozzle 32; and a swirl groove 34a that guides the needle valve 33 and imparts a swirl motion to the fuel that is about to flow radially inward into the fuel injection hole 32a. And a revolving body 34.

Fuel from a high-pressure pump (not shown) passes through the center of the fuel injection valve body 31 and is guided to the tip, and as shown by the arrow, from the fuel introduction path 34b formed on the side surface of the swivel body 34, the swirl groove 34a and is injected from the fuel injection hole 32a into a combustion chamber (not shown) of the internal combustion engine.
Since the fuel is swirled by the swirling groove 34a, a cavity is generated in the fuel injection hole 32a, and the spray is injected in a hollow holographic cone shape.
Since the strength of turning is determined by the passage sectional area of the turning groove 34a and the offset amount (see FIG. 5B), the turning strength becomes smaller as the passage sectional area of the turning groove 34a becomes smaller and the offset amount becomes larger. Increases, and the spray angle of the fuel injected from the fuel injection holes 32a increases (see Patent Document 1).

Japanese Patent Laid-Open No. 10-47208 (page 4-5, FIG. 4)

In a cylinder injection internal combustion engine, one of the factors that determine the characteristics of fuel spray is the spray angle when fuel is sprayed into the combustion chamber. When the fuel spray angle is large, the air-fuel mixture tends to diffuse, and when it is small, the air-fuel mixture tends to aggregate.
In an internal combustion engine, the optimum spray angle in the cylinder varies depending on the operating conditions. For example, when it is desired to suppress the excessive increase of smoke due to excessive concentration of fuel at high load, it is desirable that the spray angle be large, and also when the load is low, less fuel diffuses in the cylinder and ignitability deteriorates. When it is desired to suppress this, it is desirable that the spray angle is small.
The conventional fuel injection valve shown in Patent Document 1 realizes an optimal spray form by defining the shapes of the swivel body, the valve seat, and the fuel injection hole, but the shape and cross-sectional area of the swirl groove are constant. Since there is no mechanism for controlling the strength of turning, the spray angle is uniquely determined. Therefore, it is difficult to variably control the spray angle according to the operating conditions.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a fuel injection valve capable of changing the spray angle of fuel to be injected when performing variable fuel pressure control. To do.

A fuel injection valve according to the present invention includes a hollow valve body, a valve seat provided at one end of the valve body and having an injection hole at the center thereof, and moves within the valve body so as to be in contact with and separated from the valve seat, thereby opening and closing the injection hole. And a swirler that is disposed in the valve body and slidably supports the valve body and has a plurality of fuel swirl passages that swirl the fuel flowing toward the injection holes. In a fuel injection valve that directly injects fuel into the fuel swirl passage , the fuel swirl passage has a groove shape, and an elastic thin plate member is directed vertically to the side surface of the groove so that the upstream side of the fuel swirl passage is narrowed. When the pressure of the fuel supplied to the fuel injection valve rises , the cross-sectional area of the fuel swirl passage becomes smaller, and the pressure is increased by the holding part integrally formed so as to be fitted to the inner periphery of the swirler. The cross-sectional area increases when It is those that you have configured.

According to the fuel injection valve of the present invention, the fuel swirl passage has a groove shape, and an elastic thin plate member is disposed in the fuel swirl passage so that the upstream side of the fuel swirl passage is narrowed in a direction perpendicular to the side surface of the groove. while, held in the swirler with holding portions formed integrally to an inner periphery and mating swirler, the pressure of fuel supplied to the fuel injection valve increases the cross-sectional area of the fuel swirl passages decreases, the pressure Since the cross-sectional area is increased when the fuel is lowered, the cross-sectional area of the swirler fuel swirl path is reduced and the swirl strength is increased at high fuel pressure, and the spray angle is increased. Conversely, when the fuel pressure is low, the cross-sectional area of the fuel swirl passage increases and the swirl strength decreases, so the spray angle decreases. Therefore, a fuel injection valve that can change the spray angle using variable fuel pressure control can be easily obtained with a simple configuration .

Embodiment 1 FIG.
1 is a longitudinal sectional view showing a fuel injection valve according to Embodiment 1 of the present invention. 2A and 2B are perspective views of a swirler portion used at the tip of the valve device of the fuel injection valve of FIG. 1, wherein FIG. 2A is an exploded view and FIG. 2B is an assembly view. FIG. 3 is a partial cross-sectional view of the distal end portion of the valve device viewed from the III-III cross section of FIG.

First, the whole fuel injection valve will be described with reference to FIG.
In the figure, the fuel injection valve 1 is provided with a solenoid device 2, which is a housing 3 that is a yoke portion of a magnetic circuit, and a core 4 that is a fixed core portion of the magnetic circuit and that has a fuel passage at the center. A coil 5 on the outside of the core 4 and wound around a bobbin, an armature 6 that is a movable core portion of a magnetic circuit, and a spring 7 that energizes a needle valve 12 to be described later joined to the armature 6; A holder 8 that is integrated with the housing 3 and fixes the valve device 9 is provided. The solenoid device 2 is an operating device that opens and closes the valve device 9.

  The valve device 9 includes a hollow valve body 10 that is housed on the front end side of the housing 3 and is fixed by a holder 8, a valve seat 11 that is provided at one end of the valve body 10 and that has an injection hole 11a at the center, and a valve body. The needle valve 12 is a valve body that moves in the axial direction in the direction 10 and moves to and away from the valve seat 11 to open and close the injection hole 11a, and the needle valve 12 that is disposed in the valve body 10 and slidably supports the injection hole. A swirler 13 that gives a swirling motion to the fuel that flows toward 11a and a stopper 14 that restricts the movement of the needle valve 12 are provided. Details of the swirler 13 will be described later.

The operation of the fuel injection valve 1 configured as described above is as follows.
When an operation signal is sent from the outside to the terminal of the solenoid device 2 and a current is passed through the coil 5, a magnetic flux is generated in the magnetic circuit composed of the core 4, the armature 6 and the housing 3. The needle valve 12 that is integral with the armature 6 is separated from the valve seat 11 and the injection hole 11a is opened. As a result, high-pressure fuel supplied from a fuel supply pipe (not shown) passes through the hollow portion 4a of the core 4 and from the fuel passage formed in the inner periphery of the armature 6 and the outer periphery of the needle valve 12 to the fuel passage (details) of the swirler 13 Is given a turning motion in the course of passing through (described later), and is injected into the cylinder of the internal combustion engine (not shown) from the injection hole 11a of the valve seat 11. When the power supply to the coil 5 is cut off, the urging force of the spring 7 moves the needle valve 12 toward the valve seat 11 to close the injection hole 11a.

Next, details of the swirler 13 portion, which is a characteristic portion of the present invention, will be described with reference to FIG.
As shown in FIG. 2 (a), the swirler 13 has a hollow cylindrical shape having a center hole 13a in which the needle valve 12 is slidable at the axial center thereof. A first end surface 13b in contact with the seat 11, a second end surface 13c opposite to the valve seat 11, and a peripheral surface 13d constituting the outer periphery are provided. The peripheral surface 13d is composed of a plurality of outer peripheral surface portions that abut the inner peripheral surface of the valve body 10 to define the position with respect to the valve body 10, and a flat surface provided between the outer peripheral surface portions. A gap formed between the valve body 10 and the inner peripheral surface of the valve body 10 serves as a fuel axial flow path 16 (see FIG. 3).
A passage groove 13e extending in the radial direction is formed in the second end surface 13c, and fuel flows from the inner peripheral portion to the outer peripheral portion.

  An inner peripheral annular groove 13f having a predetermined width is formed on the inner periphery adjacent to the center hole 13a on the first end face 13b. And it has the fuel turning channel | path 13g which one end was connected to the flat surface of the surrounding surface 13d, extended from there almost in the radial direction, and the other end was connected to the tangential direction of the inner periphery annular groove 13f. The fuel swirl passage 13g has a groove shape, and its cross section is formed in a U shape with a bottom surface perpendicular to the axial direction of the swirler 13 and a side surface parallel to the axial direction, as shown in the figure.

The thin plate member 15 constituting the virtual wall of the fuel swirl passage 13g is formed by being bent along the peripheral surface 13d of the swirler 13 and the side surface of the fuel swirl passage 13g. The thin plate member 15 is made of a material having a spring property.
When this thin plate member 15 is combined with the first end face 13b side of the swirler 13, the result is as shown in FIG.
The portion that becomes the virtual wall 15a after the combination is perpendicular to the bottom surface of the fuel swirl passage 13g, and the upstream side of the fuel swirl passage 13g (the side connected to the flat surface of the peripheral surface 13d) is the break of the passage. It arrange | positions so that an area may become small. On the upstream side, a slight gap is formed between the imaginary wall 15a and the side surface of the groove of the fuel swirl passage 13g, and is fixed in close contact with the downstream side. That is, the upstream side is free and the downstream side is fixed.
In the combined state as shown in FIG. 2B, the first end face 13b is assembled and fixed to the distal end portion of the valve body 10 so as to be on the valve seat 11 side.

The operation of the fuel swirl passage 13g of the swirler 13 configured as described above will be described with reference to FIG.
The fuel that has flowed into the fuel injection valve 1 under pressure is introduced into the fuel swirl passage 13g from the axial flow passage 16 formed on the peripheral surface of the swirler 13, and the swirl motion is given to the fuel. Into the swirl flow and sprayed from the injection hole 11a of the valve seat 11 to the outside.

  At this time, the fuel also enters the gap between the virtual wall 15a and the side surface of the fuel turning passage 13g. Therefore, when the fuel pressure rises, as shown in FIG. 3 (b), the virtual wall 15a is elastically deformed by the fuel entering the gap, and the amount of deflection becomes large. The passage sectional area of the passage 13g is reduced. As a result, the flow velocity is increased and the strength of turning is increased, so that the spray angle of the fuel injected from the injection hole 11a is increased. Conversely, at the time of low pressure, the virtual wall 15a returns to the state shown in (a), the passage cross-sectional area of the fuel turning passage 13g becomes larger, the flow velocity becomes slower, and the turning strength decreases. For this reason, the spray angle of the fuel injected from the injection hole 11a becomes small. In this way, the spray angle can be made variable using variable fuel pressure control.

2 and 3, the case where the thin plate member 15 constituting the virtual wall 15a of the fuel swirl passage 13g is provided so as to be perpendicular to the bottom surface of the groove of the fuel swirl passage 13g has been described. An example will be described.
FIG. 4 is a perspective view showing another example of the swirler 13 portion used at the tip of the valve device 9, wherein (a) is an exploded view and (b) is an assembly view.

The same parts as those in FIG. The swirler 13 is equivalent to FIG. As shown in FIG. 4 (a), the thin plate member 17 is formed in a direction that is perpendicular to the side surface of the groove of the fuel swirl passage 13g and that matches the groove bottom surface of the groove and becomes the virtual wall 17a. And a holding portion 17b for holding it on the swirler 13, and is made of, for example, a thin steel plate having a spring property. In a state where it is combined with the swirler 13, the virtual wall 17a is bent in a direction in which a gap is formed with the bottom surface toward the upstream side of the groove so that the cross-sectional area of the fuel swirl passage 13g becomes smaller on the upstream side. The upstream side is free and the downstream side is fixed.
The thin plate member 17 is used by being combined with the swirler 13 as shown in FIG. 4B, and is assembled with the valve body 10 so that the first end face 13b side is the valve seat 11 side.

The operation of the fuel swirl passage 13g of the swirler 13 configured as described above will be described.
When the fuel flows through the fuel turning passage 13g, the fuel also enters the gap between the virtual wall 17a and the bottom surface of the fuel turning passage 13g. When the fuel pressure is high, the imaginary wall 17a is elastically deformed so that the gap is widened and the amount of deflection is increased, and as a result, the cross-sectional area of the fuel swirl passage 13g is reduced. As a result, the flow velocity increases and the turning strength increases, so the spray angle of the fuel injected from the injection hole 11a also increases. Further, when the pressure is low, the deflection of the virtual wall 17a is reduced, the cross-sectional area of the fuel swirl passage 13g is increased, and the strength of the swirl is reduced, so the spray angle of the fuel injected from the injection holes 13a is decreased.

The number of fuel swirl passages 13g formed in the swirler 13 is not limited to six, and may be four or eight, for example. Further, the offset amount of the fuel turning passage 13g (see FIG. 5B) is not limited to the figure, and may be set as appropriate.
Furthermore, the virtual wall made of a thin plate member is provided as a mechanism for changing the cross-sectional area of the fuel swirl passage 13g. However, the present invention is not limited to this, and the cross-sectional area is changed in accordance with a change in fuel pressure. Other structures may be used as long as they exist.

As described above, according to the invention of the present embodiment, the fuel swirl passage has a groove shape, and the thin plate member having elasticity is directed vertically to the side surface of the groove so that the upstream side of the fuel swirl passage is narrowed. When the pressure of the fuel supplied to the fuel injection valve rises, the cross-sectional area of the fuel swirl passage is reduced when the fuel is supplied to the fuel injection valve by holding the swirler integrally with the swirler so as to be fitted with the inner periphery of the swirler. Since the cross-sectional area increases as the pressure decreases , the fuel cross-sectional area of the swirler fuel swirl passage decreases and the swirl strength increases at high fuel pressure. The corner becomes larger. Conversely, when the fuel pressure is low, the cross-sectional area of the fuel swirl passage increases and the swirl strength decreases, so the spray angle of the fuel injected from the injection holes decreases. Therefore, a fuel injection valve that can change the spray angle according to the fuel pressure can be easily realized with a simple configuration .
For this reason, for example, since the spray angle becomes large at high loads with high fuel pressure, it is possible to suppress the excessive increase of smoke due to excessive concentration of fuel, and the spray angle becomes small at low loads with low fuel pressure. Further, it is possible to suppress the deterioration of the ignitability of the spark plug due to the diffusion of the fuel, and it is possible to provide a spray angle suitable for the operating condition of the internal combustion engine.

It is a longitudinal cross-sectional view of the fuel injection valve in Embodiment 1 of this invention. It is a perspective view which shows the swirler part used for the valve apparatus front-end | tip part of the fuel injection valve of FIG. 1, (a) is an exploded view, (b) is an assembly drawing. It is the fragmentary sectional view of the valve device tip part seen from the III-III section of Drawing 1. It is a perspective view which shows the other example of the swirler part used for the valve apparatus front-end | tip part of the fuel injection valve of FIG. 1, (a) is an exploded view, (b) is an assembly drawing. It is a fragmentary sectional view of the valve device tip of a conventional fuel injection valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Solenoid apparatus 3 Housing 4 Core 4a Hollow part 5 Coil 6 Amateur 7 Spring 8 Holder 9 Valve apparatus 10 Valve body 11 Valve seat 11a Injection hole 12 Needle valve (valve body)
13 swirler 13a center hole 13b first end surface 13c second end surface 13d peripheral surface 13e passage groove 13f inner peripheral annular groove 13g fuel swirl passage 14 stopper 15 thin plate member 15a virtual wall 16 axial flow path 17 thin plate member 17a virtual wall 17b holding portion .

Claims (1)

A hollow valve body, a valve seat provided at one end of the valve body and having an injection hole at the center thereof, a valve body that moves within the valve body, contacts and closes the valve seat, and opens and closes the injection hole; And a swirler having a plurality of fuel swirling passages disposed in the valve body to slidably support the valve body and to swirl the fuel flowing toward the injection hole, and into the cylinder of the internal combustion engine In a fuel injection valve that directly injects
The fuel swirl passage has a groove shape, and an elastic thin plate member is disposed in the fuel swirl passage in a direction perpendicular to the side surface of the groove so that the upstream side of the fuel swirl passage is narrowed. When the pressure of the fuel supplied to the fuel injection valve rises , the cross-sectional area of the fuel swirl passage decreases, and the pressure drops. A fuel injection valve configured to increase the cross-sectional area.

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