JPH10131826A - Fuel injection valve for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection valve which has high accuracy of responsiveness when closed, and by which combustion is improved by mounting the fuel injection valve on an intercylinder direct injection type gasoline engine or a diesel engine, requiring accuracy of fuel injection finishing time. SOLUTION: In a fuel injection valve in which a needle 2 is vertically moved in response to fuel pressure forcibly fed from a fuel forcibly feeding pump and control pressure increased and decreased by an actuator so that fuel injection from an injection hole 12 is started and finished, a pressure transmission groove 7 being symmetrical around the center shaft of the needle 2, is arranged on at least one of the top surface 4 of the needle 2 and the contact surface 5 of a control pressure chamber, which is brought into contact with the top surface 4. Fuel inflow from the pressure transmission groove 7 is also joined toward an interval between the top surface 4 of the needle 2 and the contact surface 5 of the control pressure chamber, and time that pressure change is transmitted to the whole top surface 4 of the needle 2 is shortened. Therefore, pressure change transmission time can be shortened, and the responsiveness of the operation of the needle 2 is improved against the change of the inner pressure of the control pressure chamber by the actuator.

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 for an internal combustion engine used for a direct injection diesel engine, a direct injection gasoline engine, or the like.

[0002]

2. Description of the Related Art As a known fuel injection valve for fuel injection in a direct injection diesel engine, a direct injection gasoline engine, or the like, for example, a fuel injection valve as shown in FIG. 5 disclosed in Japanese Patent Publication No. 4-54065 is disclosed. is there. In FIG. 5, a pressure accumulator 101 is provided in the middle of the flow path, and the needle 2 is controlled according to the fuel pressure fed from the fuel pump 100 and the control pressure for increasing and decreasing the pressure by the actuator 200 formed by a piezo element. Moves up and down, starts fuel injection from the injection hole 12,
A configuration of a fuel injection valve for an internal combustion engine that terminates is disclosed.

FIG. 6 is a longitudinal sectional view taken along a central axis of a needle 2 which is a main part of these known general fuel injection valves. In FIG. 6, the needle 2 that slides with a clearance that can move up and down with respect to the nozzle body 3 comes into contact with the nozzle body 3 at the seat portion 11 and cuts off the communication between the oil sump 14 and the injection hole 12 and the sack 15. I do. The needle 2 is urged from above by a spring 6 having an upper end at the end surface 16 of the spring storage chamber 10 and a lower end at the needle top surface 4. Above the needle 2, there is a lift stroke portion corresponding to the vertical movement width of the needle 2 and a spring storage chamber 10, which communicates with a transformer chamber below the actuator through a communication hole 9.

The lift stroke portion, the pressure of which changes by the operation of the actuator, the spring storage chamber 10 and the communication hole 9
And the variable pressure chamber are generally referred to as a control pressure chamber.

[0005]

When the fuel injection nozzle of this type moves up and down, the needle rises, that is, when the valve is opened, the internal pressure of the control pressure chamber is applied to the entire top surface 4 of the needle 2. Respond promptly to But,
When the needle 2 is raised and stationary, that is, when the top surface 4 of the needle 2 is in contact with the control pressure chamber contact surface 5,
The control pressure chamber pressure is applied only to an area corresponding to the diameter of the spring storage chamber 10. The portion where the needle top surface 4 and the control pressure chamber surface are in contact with each other is usually smoothed in order to reduce the leak of the control pressure chamber pressure generated through the clearance between the needle 2 and the nozzle body 3. When the fuel cells adhere to each other, it is difficult for fuel to flow between them.

Therefore, in order for the change in the control pressure chamber pressure by the actuator to be transmitted to the entire needle top surface 4, the fuel must flow between the two closely contacted portions due to the change in the internal pressure, which causes a delay in response. There was a problem. The present invention provides a fuel injection valve for an internal combustion engine in which combustion is improved by being mounted on a direct injection gasoline engine or a diesel engine, which has a high response accuracy at the time of closing the valve and requires an accuracy of the injection end time. The purpose is to:

[0007]

The present invention employs the structure described in claim 1 to achieve the above object. According to this configuration, in the fuel injection state in which the needle top surface and the control pressure chamber contact surface are in contact with each other, the internal pressure of the control pressure chamber corresponds to the surface corresponding to the spring storage chamber and the opening area of the pressure transmission groove of the present invention. Surface and are loaded on. When the internal pressure of the control pressure chamber is increased by the actuator, the change in the pressure is transmitted to the needle from both surfaces. The fuel inflow between the needle top surface and the control pressure chamber contact surface is more rapid than in the past because there is a circumferential flow from the pressure transmission groove in addition to the conventional radial flow. Therefore, the time during which the pressure change is transmitted to the entire needle top surface is reduced. For this reason, the increase of the pressure receiving area with respect to the control pressure chamber pressure and the reduction of the pressure change transmission time speed up the transmission of the load to the needle with respect to the change of the control pressure chamber pressure by the actuator, and improve the operation responsiveness. This has the effect.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The overall system configuration of an embodiment of a fuel injection valve for an internal combustion engine according to the present invention is the same as the conventional fuel injection valve shown in FIG. The needle 2 moves up and down according to the fuel pressure pumped from the pump 100 and the control pressure to be pressurized and depressurized by the actuator 200, and starts fuel injection from the injection hole 12.
It is the same in terminating.

FIGS. 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a longitudinal sectional view of a main part, and FIG. 1B is a view showing a needle 2 within a depth of a pressure transmission groove 7 in FIG. FIG.
In FIG. 1, a needle top surface 4 of a needle 2 housed slidably in a vertical direction with an appropriate clearance between the nozzle body 3 and a nozzle body 3 tightly fixed to an injector body 1. There is a pressure transmission groove 7 of an appropriate depth. The needle top surface 4 and the control pressure chamber contact surface 5 in the injector body 1 have smoothness so that they can be in close contact with each other.

The spring 6 has a spring storage chamber 1 at the upper end.
The lower end is in contact with the end surface 16 of the needle 0 while the lower end thereof is compressed with the needle top surface 4, and the needle 2 is urged downward. Communication hole 9
Communicates between the spring storage chamber 10 and a transformation chamber below the actuator (not shown). The portion 17 corresponding to the stroke of the needle top surface 4, the spring storage chamber 10, and the communication hole 9
And the variable pressure chamber are generally referred to as a control pressure chamber.

The seat 11, the nozzle body 3, the injection hole 12, the oil reservoir 14, the fuel passage 13 and the like below the needle 2 are the same as those of the conventional fuel injection valve. The operation in the first embodiment will be described. The oil sump 14 is filled with fuel pumped at a required pressure from a high-pressure pump (not shown). The control pressure chamber is also filled with fuel, and the pressure is increased through the clearance of the sliding portion of the needle 2. When the pressure in the control pressure chamber and the pressure in the oil sump 14 are equal, the needle 2 is seated on the nozzle body 3 at the seat portion 11 by the load of the spring 6.

The internal pressure of the control pressure chamber is reduced by the operation of the actuator, and the combined force of the force of the control pressure chamber holding down the needle 2 downward and the force of the spring 6 is combined with the force of the fuel pressure pushing the needle 2 upward. When the combined force with the force due to the combustion chamber cylinder pressure becomes smaller, the needle 2 starts to rise, and fuel is injected from the injection hole 12.
After the needle 2 rises until it comes into contact with the control pressure chamber contact surface 5, the two closely contact each other, the lift amount of the needle 2 becomes constant, and the injection is stably maintained.

Thereafter, when the internal pressure of the control pressure chamber rises due to the operation of the actuator, the pressure changes to a circular portion corresponding to the spring storage chamber 10 in the needle top surface 4 and an area corresponding to the opening of the pressure transmission groove 7. Load changes occur instantaneously. At the same time, high pressure fuel flows between the needle top surface 4 and the control pressure chamber surface from the outer peripheral portion of the spring storage chamber 10 and the outer peripheral portion of the opening of the pressure transmission groove 7 due to the pressurization.

Accordingly, a change in the internal pressure of the control pressure chamber is instantaneously transmitted to the needle top surface 4 as a load change, and the needle 2 starts to descend. When the needle 2 is seated on the nozzle body 3 at the seat portion 11, the injection is stopped. FIG. 2 relates to a modification of the first embodiment of the present invention, and shows plan sectional views of the needle 2 within the depth of the pressure transmission groove 7 for various modifications of the pressure transmission groove 7, respectively.

With respect to the opening portion of the pressure transmitting groove 7 in the first embodiment of FIG. 1, (a) shows the case where the number of pressure transmitting grooves 7 is increased (or may be reduced), and (b) shows the pressure transmitting groove 7 The one in which the length of the pressure transmission groove 7 is changed within a range where the groove 7 and the spring storage chamber 10 communicate with each other, (c) is a wedge-shaped one, and (d) is a case where the pressure transmission groove 7 reaches the outer periphery of the needle top surface 4. The other configuration is the same as that of the first embodiment.

The operation of the above modification is the same as that of the first embodiment. When the above embodiments are combined,
For example, by increasing the number of pressure transmission grooves 7 and
The same operation can be performed when the length is changed. 3A and 3B show a second embodiment of the present invention, wherein FIG. 3A is a longitudinal sectional view of a main part, and FIG. 3B is a plan view of the injector body 1 within the depth of the pressure transmission groove 7 of FIG. It is sectional drawing.

In this embodiment, the needle top surface 4 is a uniform smooth surface, and has a pressure transmission groove 7 on the control pressure chamber contact surface 5. Other configurations are the same as in the first embodiment. The operation of the present embodiment is the same as that of the first embodiment. FIG. 4 relates to a modified example of the second embodiment of the present invention, and shows plan sectional views of the injector body 1 within the depth of the pressure transmitting groove 7 for various modified examples of the pressure transmitting groove 7, respectively.

In the present embodiment, with respect to the pressure transmission grooves 7 in the second embodiment of FIG. 3, (a) shows the case where the number of the pressure transmission grooves 7 is increased (or may be decreased), and (b).
FIG. 3C shows the shape of the opening of the pressure transmitting groove 7 enlarged as the distance from the center increases, FIG. 4C shows the shape of the opening reduced as the distance from the center increases, and FIG. The other configuration is the same as that of the second embodiment.

The operation of this embodiment is the same as that of the first embodiment. In the case where the pressure transmission groove 7 is a combination of the features of the above-described embodiment, the same applies to the case where, for example, the number of the pressure transmission groove 7 is increased and the opening shape of the pressure transmission groove 7 is enlarged as the distance from the center increases. Can operate.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention,
(A) is a longitudinal sectional view of a main part, and (b) is a pressure transmission groove 7 of (a).
FIG. 4 is a plan sectional view of the needle 2 within the depth of FIG.

FIGS. 2A and 2B relate to modifications of the first embodiment of the present invention, and show plan sectional views of the needle 2 within the depth of the pressure transmission groove 7 for various modifications of the pressure transmission groove 7, respectively.

FIG. 3 shows a second embodiment of the present invention,
(A) is a longitudinal sectional view of a main part, and (b) is a pressure transmission groove 7 of (a).
FIG. 3 is a plan sectional view of the injector body 1 within a depth of FIG.

FIG. 4 relates to a modification of the second embodiment of the present invention, and shows plan sectional views of the injector body 1 within the depth of the pressure transmission groove 7 for various modifications of the pressure transmission groove 7, respectively. .

FIG. 5 is a known fuel injection valve disclosed in Japanese Patent Publication No. 4-54065.

FIG. 6 is a longitudinal sectional view along a central axis of a needle 2 which is a main part of a known general fuel injection valve.

[Explanation of symbols]

 2 Needle 4 Needle top surface 5 Control pressure chamber contact surface 7 Pressure transmission groove 12 Injection hole 100 Fuel pressure pump 200 Actuator

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 61/10 F02M 61/10 M

Claims (1)

[Claims] 1. A fuel for an internal combustion engine in which a needle moves up and down in response to a fuel pressure fed from a fuel pressure pump and a control pressure increased / decreased by an actuator to start and end fuel injection from an injection hole. In the injection valve, at least one of a top surface of the needle and a control pressure chamber contact surface that is in contact with the top surface of the needle, has a pressure transmission groove symmetrical with respect to a center axis of the needle. A fuel injection valve for an internal combustion engine.