JPH0468463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a fuel injection valve drive device using combustion pressure of an internal combustion engine.

<Prior Art> Conventionally, in internal combustion engines for automobiles, as is well known, combustion pressure of the engine is converted into reciprocating motion of a piston, and then this reciprocating motion is changed to rotational motion by a crankshaft. Rotational energy is used to drive a vehicle, drive equipment such as a compressor, and operate loads such as servo brakes and fuel injection valves.

However, although the combustion pressure of an internal combustion engine is temporarily higher than the required combustion pressure, this surplus pressure has not been effectively utilized.

For example, in a diesel engine fuel injection valve, after converting combustion pressure into rotational energy, for example, a fuel pump is mechanically driven to increase the fuel pressure and supply it to the fuel injection valve. Since the engine is operated to open the valve, there are many energy conversion steps and the energy conversion efficiency decreases, resulting in a large energy loss in combustion pressure. Further, in order to obtain a predetermined combustion pressure, the fuel pump had to be made large.

<Objective of the invention> To drive a fuel injection valve by effectively using combustion energy without reducing energy conversion efficiency, to downsize a fuel pump, etc., and to promote atomization and vaporization of fuel. With the goal.

<Configuration of the Invention> For this reason, the present invention includes a pressure take-off passage communicating with the combustion chamber of an internal combustion engine, a check valve that is interposed in the pressure take-off passage and opens at a predetermined pressure or higher, and a check valve that opens at a predetermined pressure or higher. a fuel injection valve whose valve body is stroked to open the valve and inject fuel from the nozzle hole; and a valve opening assisting device for auxiliary urging the valve body in the valve opening direction. a pressure introduction part for
An opening opening toward the fuel injected from the nozzle hole is formed, and combustion pressure is introduced from the pressure extraction passage into the opening and the valve opening assisting pressure introduction part. This makes it possible to use the combustion pressure to assist in opening the fuel injection valve, and to use the combustion pressure to promote atomization and vaporization of the fuel.

<Example> The present invention will be described below based on an example shown in FIGS. 1 and 2.

In FIG. 1, a cylinder head 1 is formed with a gas introduction hole 3 that communicates with a combustion chamber 2, and a communication hole 4 that communicates the gas introduction hole 3 with the outside of the cylinder head 1. This communication hole 4
A check valve 5 is installed in the combustion chamber 2, which opens when the pressure of the combustion gas in the combustion chamber 2 exceeds a predetermined value, and allows the combustion gas to flow into the communication hole 4 downstream thereof.

A flow control valve 6 is installed in the communication hole 4 to control the flow rate of combustion gas flowing out from the check valve 5 to a constant value. Further, a pressure extraction passage 7 is installed at the outlet of the communication hole 4 , and a downstream end of this pressure extraction passage 7 is connected to an inlet of the accumulator 8 . Branch passages 9A, 9B, and 9C are connected to the outlet of this accumulator 8, and pressure control valves 10A and 1 are connected to these branch passages 9A, 9B, and 9C, respectively, to keep the combustion pressure flowing downstream constant.
0B and 10C are connected. A load drive unit such as a fuel injection valve 11 and a servo brake (not shown) is connected to the downstream ends of these branch passages 9A, 9B, and 9C, respectively. Here, the gas outlet hole 3, the communication hole 4, the pressure extraction passage 7, and the branch passage 9
A constitutes a pressure extraction passage.

In addition, 12 is a piston, 13 is a cylinder block, 14A, 14B are intake/exhaust valves, and 15 is a blind plug.

Next, a fuel injection valve used in a diesel engine or the like will be explained based on FIG. 2 as an example.

First, to explain the fuel injection valve 11, the needle valve 16
Nozzle body 17 and nozzle holder 18 fitted with
are joined via a contact piece 19 and connected by a nut 20. The peripheral wall of the main body of the needle valve 16 is slidably inserted into a hole 17a formed in the nozzle body 17, and a projection 21 formed at the top thereof is in contact with a spring seat 22.
The spring seat 22 is slidably inserted into a hole 18a formed in the nozzle holder 18, and is pressed by the biasing force of a spring 23 provided in a hole 18b formed in the nozzle holder 18, so that the needle valve 16 is pressed against the valve seat surface in which the nozzle hole 24 of the nozzle body 17 is opened.

Further, a high-pressure fuel passage 26 is formed in the nozzle body 17, the contact piece 19, and the nozzle holder 18 in communication with a fuel reservoir 25 formed between the inner wall of the nozzle body 17 and the needle valve 16, and the inlet thereof is connected to a connector (not shown). It is connected to a fuel outlet of a fuel pump (not shown) via a fuel supply pipe (not shown) connected thereto.

The fuel pumped under pressure from the fuel pump is introduced into the high-pressure fuel passage 26 from the connector via the fuel supply pipe, and when the fuel discharge pressure reaches the set load of the spring 23 or higher, the spring 23 is compressed and the needle valve is opened. 16 to the right in FIG. 2, fuel is injected into the combustion chamber 2 from the opened nozzle hole 24. Furthermore, fuel leaking from the gap between the needle valve 16 and the hole 17a is returned to the fuel tank through the hole 22a formed in the spring seat 22 and the hole 18b. Therefore, here, the differential pressure between the fuel pressure and the biasing force of the spring 23 corresponds to the predetermined operating pressure in the claims.

In the structure of the conventional fuel injection valve 11, the following improvements have been made in this embodiment. That is, an annular groove 27 is formed approximately at the center of the needle valve 16, and a first pressure passage 28 communicating with the annular groove 27 and facing the combustion chamber from the tip of the needle valve 16 is formed. Here, a portion of the first pressure passage 28 facing the combustion chamber constitutes an opening. A second pressure passage 29 is formed in the nozzle body 17, the contact piece 19, and the nozzle holder 18, and the open end of the second pressure passage 29 on the nozzle holder 18 side opens into the hole 17a of the nozzle body 17, and the needle When the valve 16 strokes to the right in FIG. 2 and opens, it aligns with the annular groove 27. Also, the second
A passage 30 branching from the pressure passage 29 is formed in the nozzle holder 18, and this passage 30 faces a chamber 31 as a pressure introduction part for assisting valve opening formed by the outer wall of the spring seat 22 and the inner wall of the hole 18b. Further, the inlet of the second pressure passage 29 is connected to the branch passage 9A.

Next, the effect will be explained.

When the engine is started, the amount of high-pressure combustion gas led out from the combustion chamber 2 via the check valve 5 and the flow rate control valve 6 is small, so the internal pressure of the accumulator 8 does not increase, so the fuel is transferred via the branch passage 9A. The pressure introduced into the second pressure passage 29 of the injection valve 11 also does not increase, and the fuel injection 11 is performed by balancing the pressure of fuel pumped from a fuel pump (not shown) and the biasing force of the spring 23. That is, when the pressure of the fuel introduced into the fuel reservoir 25 overcomes the biasing force of the spring 23, the needle valve 16
Then, the spring seat 22 is stroked to the right in FIG. 2, and the fuel in the fuel reservoir 25 is injected into the combustion chamber 2 through the injection hole 24.

When a predetermined period of time has elapsed after the engine is started, the amount of combustion gas led out from the combustion chamber 2 and stored in the accumulator 8 increases, and its pressure becomes high, and this high-pressure gas flows through the branch passage 9A to the second pressure passage 29. will be introduced in The high pressure gas is introduced from the second pressure passage 29 through the passage 30 into the chamber 31 formed between the outer wall of the spring seat 22 and the inner wall of the hole 18b. As a result, the pressure of the high-pressure gas introduced into the chamber 31 opposes the biasing force of the spring 23 via the spring seat 22, and this pressure adds to the fuel pressure, causing the needle valve 16 to move against the spring 23.
The fuel pressure required to stroke against the urging force No. 3 decreases. Therefore, even if the pressure of the fuel pumped from the fuel pump is lower than the fuel pressure at the time of starting the engine, the needle valve 16 strokes against the biasing force of the spring 23, and the fuel is injected into the nozzle hole. 2
4 into the combustion chamber 2. Therefore, the pressure of the fuel pumped from the fuel pump can be reduced to a greater extent than in the past, so the capacity of the fuel pump can be reduced, the size of the fuel pump can be reduced, and the noise of the pump nozzle generated during pumping can be reduced. Furthermore, since the fuel injection valve 11 is directly operated by the high pressure energy in the combustion chamber 2, energy loss is also reduced.

Further, when the needle valve 16 strokes and opens, the second pressure passage 29 and the annular groove 27 match, so that the second pressure passage 29 and the first pressure passage 28
The high pressure gas in the second pressure passage 29 is injected from the tip of the needle valve 16 via the first pressure passage 28 . At this time, since fuel is also injected from the nozzle hole 24, atomization of this fuel is promoted by the high pressure gas.

<Effects of the Invention> As explained above, the present invention derives a combustion pressure of a predetermined level or more from the combustion chamber of an engine, and then guides the fuel to the fuel injection valve to supplementally bias the valve body in the valve opening direction and inject the fuel. Since the fuel is injected toward the fuel, the combustion energy can be used effectively, the driving energy of the fuel injection valve can be reduced, and the atomization and vaporization of the fuel can be promoted. Accordingly, when driving the fuel injection valve, the fuel supply pressure of the fuel pump that pumps fuel to the fuel injection valve can be lowered, so that the fuel pump can be made smaller and the nozzle noise of the fuel pump can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure is a sectional view of a fuel injection valve applied to the embodiment shown in FIG. 1, 2... Combustion chamber, 4... Communication hole, 5... Check valve,
6...Flow rate control valve, 7...Pressure extraction passage, 8...
... Accumulator, 9A, 9B, 9C... Branch passage, 11... Fuel injection valve, 26... High pressure fuel passage, 27... Annular groove, 28... First pressure passage,
29...Second pressure passage.

Claims (1)

[Claims] 1. A pressure take-off passage that communicates with the combustion chamber of an internal combustion engine, a check valve that is interposed in the pressure take-off passage and opens at a predetermined pressure or higher, and a valve body that is stroked by a predetermined operating pressure to open the nozzle hole. a fuel injection valve that injects fuel from the nozzle hole, and a valve-opening auxiliary pressure introducing part for auxiliary urging the valve body in the valve-opening direction; an opening opening toward the fuel to be
A fuel injection valve drive device using combustion pressure of an internal combustion engine, characterized in that combustion pressure is introduced into the opening and the valve opening assisting pressure introduction part from the pressure extraction passage.