JP4191760B2 - 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.

2. Description of the Related Art In-cylinder direct injection internal combustion engines have recently been aimed at fuel injection control that approaches an ideal air-fuel ratio in all driving situations, and for this purpose, fuel injection valves with a wide injection range are required.
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 turning strength 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, the cavity ratio in the fuel injection hole 32a increases, and the injection amount decreases (see Patent Document 1).

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

It is desirable that the fuel injection amount and the injection angle of the fuel injection valve can be as wide as possible in accordance with the required specifications of the internal combustion engine and the operation status (load status).
In the variable fuel pressure control, a low fuel pressure is used when a small amount of injection such as idle is required, and a high fuel pressure is used when a large amount of injection is required such as at high load. In this fuel injection valve, the cross-sectional area of the swirling groove is constant, and since there is no mechanism for controlling the strength of swirling, the control range of the cavity ratio in the injection hole and the injection amount is limited.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a fuel injection valve capable of expanding the fuel injectable range when performing variable fuel pressure control.

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 downstream side of the fuel swirl passage is narrowed. In addition, when the pressure of the fuel supplied to the fuel injection valve rises , the cross-sectional area of the fuel swirl passage increases and the pressure is increased. The cross-sectional area becomes smaller when descending 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 the elastic thin plate member is disposed in the fuel swirl passage so that the downstream side of the fuel swirl passage narrows in the direction perpendicular to the side surface of the groove. At the same time, when the pressure of the fuel supplied to the fuel injection valve increases, the cross-sectional area of the fuel swirl passage increases and the pressure decreases. Since the cross-sectional area is configured to be small , the swirler fuel swirl passage has a large cross-sectional area at high fuel pressure, and the swirl strength is reduced. Injection is possible. On the contrary, when the pressure is low, the passage cross-sectional area of the fuel swirl passage is reduced and the swirl strength is increased, so that the cavity ratio in the injection hole is increased and a smaller amount of injection is possible. Therefore, it is possible to easily obtain a fuel injection valve having an expanded fuel injection range 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 central 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. As shown in the drawing, the cross section of the fuel swirl passage 13g 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.

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.
The straight part toward the center is a part that becomes the virtual wall 15a. 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 cross-sectional area of the passage toward the fuel flow direction of the fuel swirl passage 13g, that is, toward the downstream side (center hole 13a side). Is arranged to be small.
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, when the fuel pressure rises, as shown in FIG. 3B, the amount of deflection due to elastic deformation of the virtual wall 15a increases, so that the passage cross-sectional area of the fuel swirl passage 13g increases at high pressure. As a result, the strength of the swirl is reduced, so that the cavity ratio in the injection hole 11a (the ratio of the cavity cross-sectional area formed at the center when the fuel passes through the injection hole occupies the cross-sectional area of the injection hole) is reduced. Fuel injection becomes possible. Further, when the pressure is low, the passage cross-sectional area of the fuel swirl passage 13g becomes small as shown in (a), and the swirl strength increases. For this reason, since the cavity ratio in the injection hole 11a increases, a smaller amount of injection becomes possible.

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 fuel swirl passage 13g has been described. Next, another example will be described. explain.
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 perpendicular to the side surface of the fuel swirl passage 13g and in conformity with the bottom surface of the passage to become a virtual wall 17a. For example, a thin steel plate having a spring property. When combined with the swirler 13, the virtual wall 17a is bent at the center so that the cross-sectional area of the fuel swirl passage 13g decreases toward the downstream side.
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 swirl passage 13g, if the fuel pressure is high, the amount of deflection due to the elastic deformation of the virtual wall 17a increases, so the cross-sectional area of the fuel swirl passage 13g increases, thereby reducing the strength of the swirl. Therefore, the cavity ratio in the injection hole 11a is reduced, and a larger amount of fuel can be injected. Further, since the cross-sectional area of the fuel swirl passage 13g becomes smaller and the swirl strength increases at low pressure, the cavity ratio in the injection hole 13a increases, and a smaller amount of fuel can be injected.

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 downstream 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 increases as it is placed in the swirl passage and held in the swirler by a holding part that is integrally formed to fit the outer periphery of the swirler. Since the cross-sectional area is reduced when the pressure decreases, the cross-sectional area of the swirler fuel swirl passage increases at high fuel pressure and the swirl strength decreases, so the cavity ratio in the injection hole decreases. From this, a larger amount of injection becomes possible. Conversely, when the pressure is low, the cross-sectional area of the fuel swirl passage is reduced and the swirl strength is increased, so that the cavity ratio in the injection hole is increased and a smaller amount of injection is possible. Therefore, it is possible to easily realize a fuel injection valve having an expanded fuel injection range with a simple configuration .

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 downstream 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 increases, and when the pressure drops, the holding part integrally formed to fit with the outer periphery holds the swirler. A fuel injection valve configured to have a small cross-sectional area.

Images