JPS59188068A - Method of fuel injection in diesel engine and its equipment - Google Patents

Abstract

PURPOSE:To simplify construction of a fuel injection valve by pushing up a needle valve by means of the fuel oil supplied to a fuel injection valve nozzle chamber and applying the working oil to the upper surface of a piston that controls the needle valve movement. CONSTITUTION:Fuel oil ''a'' that is kept at the designated injection pressure is constantly supplied to a nozzle chamber 34 of a fuel injection valve 13 so that a needle valve 35 is pushed up by the pressure applied to a tapered surface 35a of the needle valve 35. With this, fuel is injected from a plurality of injection holes via a seat part 36. When fuel injection is to be stopped, high pressure working oil b is applied via a direction control vavle 14 to the upper surface of a piston 37, which is connected to the needle valve 35, thereby lowering the piston 37 so that the needle valve 35 sits on the seat part 36.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection method and apparatus for a diesel engine.

In conventional fuel injection devices for diesel engines, it has been difficult to arbitrarily change fuel injection conditions (conditions such as fuel injection pressure, fuel injection start timing and period). However, in recent years, fuel injection control systems using electronic circuits that have been put into practical use allow the fuel injection conditions to be changed freely, so it is possible to realize engine operation that is most suitable for fuel oil properties, engine loads, etc. I can do it. The most important problem with this injection control system is whether or not the fuel valve control can be operated at high speed as desired. These control commands can be carried out using electronic circuits such as computers, but there is an urgent need to develop actuators, such as fuel valves, to carry out these commands.

For example, the West German WΔ company 'DIESEL & GAS TUR
BINWORLDWIDE, JULY-AUGUST
The control system announced in 1980' will be explained using FIG. 1 showing the electronic control block diaphragm and FIG. 2 showing details of the fuel valve. In the figure, the fuel oil is brought to high pressure by the fuel pump (1) and the accumulator (2)
and input the signal from the electronic control unit (3) to the flow rate control servo valve (5) attached to the fuel valve (4),
The servo valve (5) is operated to control the hydraulic oil flowing therethrough, and this hydraulic oil is connected to the control piston in the fuel valve (4), the pilot valve (6), the pilot valve (7) and the pressure piston (8).

It operates the control piston injection valve (9) to control injection. Figure 2 shows the state during injection.

In this control system, high pressure fuel oil from the accumulator (2) is always applied to the valve inlet σq, and when the control piston pilot valve (6) moves to the left, the pilot valve (7) opens and the high pressure fuel oil flows out. It works to push up the needle valve, and the hydraulic oil from the port (c) of the flow rate control servo valve (5) flows into the control piston injection valve (9).
is pushed up and fuel oil is injected.

When the valve is closed, the opposite movement occurs. In other words, the servo valve (
Due to the action of 5), hydraulic oil enters from port (B), moves the control piston pilot valve (6) to the right, and closes the pilot valve (7) to prevent fuel oil from going toward the needle valve. do. On the other hand, the pressure of the fuel oil is applied to the upper part of the pressure piston (8) of the control piston injection valve (
9), and the hydraulic oil pressure applied to the lower surface of the control piston injection valve (9) is reduced by switching the servo valve (5). As a result, the needle valve moves down and stops fuel oil injection.

Therefore, in this type of fuel valve, (a) the control piston pilot valve, pilot valve, control piston injection valve, etc. have a complicated shape, and (b) the fuel oil and hydraulic oil tend to mix, so the hydraulic oil (c) Because the movement of the needle valve is not understood,
There are problems such as the inability to strictly control the injection period and injection start timing.

An object of the present invention is to provide a fuel injection method for a diesel engine and an apparatus therefor that can solve the above-mentioned problems.

The present invention allows the fuel oil supplied to the nozzle chamber to act in the direction of pushing up the needle valve, causes the hydraulic oil to act only on the upper surface of the piston, and switches the direction of the hydraulic oil pressure to control the fuel valve as desired. It operates at high speed, and the shape of the injection valve can be simplified.

An embodiment of the present invention will be described below based on the drawings. 8th
The figure is a block diagram of the electronic fuel injection according to the present invention, and FIG. 4 is a sectional view showing the structure of the fuel valve.

In Figure 3, (B) is the crankshaft, (A is the piston, α frame is the fuel valve, a→ is the directional control valve added to the fuel valve (2), and (C) is the built-in fuel valve @. Needle valve opening/closing sensor, CLQ is an encoder for detecting the crank position, a is an electronic control unit, σ is a camshaft linked to the crankshaft αη, α is a fuel pump mounted on the camshaft a, (E) is the fuel pump controller, G!υ is the fuel tank,
(4) is the fuel accumulator, the threat is the fuel stop valve for emergency stop, (c) is the solenoid valve, (c) is the spring type safety valve, (c)
is a pressure detector for fuel oil, (A) is a hydraulic oil tank, (Foundation) is a hydraulic oil pump, the mortar is an electronically controlled pressure regulating valve, the ring is a detection detector for hydraulic oil, and the 0 core is a pressure regulating valve. , ni) (to) is a calmness meter. Here, the solid line is fuel oil, the broken line is hydraulic oil,
The dash-dotted lines each indicate an electrical signal.

The signal from the crank position detection encoder σ6 is input to the electronic control unit α force, and the engine speed and crank position are determined. Based on this determined crank position, the fuel injection start crank angle and fuel injection period are set by the electronic control unit a, and the directional control valve σ→
The fuel valve 0 is controlled by this signal.

High-pressure fuel oil for injection is pumped by a fuel pump O1 mounted on the camshaft σ of the engine, and is stored in an accumulator (A). The pressure of the high-pressure fuel oil to be accumulated is set in the electronic control unit α as the desired injection pressure or optimum injection pressure, and the pressure detector (a) is activated based on the command from the electronic control unit αη so that the set pressure is reached. and the fuel pump controller (a) operates. If the pressure inside the accumulator (a) rises abnormally, it will be automatically lowered by the safety valve, or the pressure signal from the pressure detector for the fuel section (a) will be judged by the electronic control unit α force, and the solenoid valve will be activated. It is lowered by opening the valve in (c).

On the other hand, the hydraulic oil is controlled by the fuel pump (l) and the fuel valve α.
It is used to control the seedlings, and is pumped by a hydraulic oil pump (incorporated) and controlled by a pressure regulating valve-0 to maintain the required pressure for each.

Next, the fuel valve will be explained with reference to FIG. High-pressure fuel oil (a) from the accumulator (2) is constantly filled in the nozzle chamber (b), and the tapered surface (i) of the needle valve (g) is constantly filled with the nozzle chamber (b).
35a) to the needle valve) to open the seat end and inject fuel oil. To stop the injection, apply high pressure hydraulic oil (b) to the upper surface of the piston (b) connected to the needle valve (to) via the directional control valve a,
Push down the piston (b) to prevent the needle valve from rising. In addition, the pressure of fuel oil in the nozzle chamber < 4 f□
・The hydraulic pressure f2 is 51f1+fg<52f2...(
Injection stops due to the relationship 1), sl fl + f g > S2 fz
-・Inject with (2). Here, sl = pressure-receiving area of the needle valve (nozzle chamber) S2 - area of the piston (b) (place where the operating extraction pressure acts) fg - injection hole surface pressure due to the cylinder internal gas pressure x cylinder internal force ゛nu pressure be.

S, s2 is the value determined when manufacturing the fuel valve, and fuel oil pressure f1 is set during engine operation.
It changes depending on the engine load condition, the fuel oil used, etc., and the pressure and direction of the hydraulic oil pressure f2 are different during injection and non-injection. In other words, f2 becomes almost atmospheric pressure during injection, and when not injected, f2 is at the electronically controlled pressure regulating valve (third
The pressure will be adjusted as shown in the figure). In this way, the hydraulic pressure is υ,! The reason for adjusting the adjustment is that if the right side in equation (1) is much larger than the left side, a very strong force will be applied to the seat part (36), which will have an adverse effect such as damage to the seat part (36). This is to avoid this and obtain the optimum oil pressure. In the example, in order to automatically adjust the pressure,
Although an electronically controlled pressure regulating valve is provided, a manual regulating valve may also be used.

In addition, in the conventional fuel valve structure shown in FIG. 2, fuel oil and hydraulic oil tend to mix, so in the present invention, the fuel oil leakage reservoir and hydraulic oil as shown in FIG. Leakage reservoirs are provided, including a fuel oil leakage reservoir (38) and a hydraulic oil leakage reservoir (39).
) are at atmospheric pressure through the fuel oil leakage hole 140) and the hydraulic oil leakage hole 01), respectively. Therefore, fuel oil and hydraulic oil leakage oil (at and (bJ) can be collected separately. Therefore, deterioration of the hydraulic oil can be particularly prevented.

In addition, in order to improve fuel injection control, the movement of the needle valve is measured using a sensor (displacement meter) (15) installed inside the fuel valve, and the lift measurement signal is sent to the electronic control unit σ force as a feedback signal. Optimum injection can be carried out by returning it.Here, (4z is the signal line of the lift measurement signal).

As described above, according to the present invention, the fuel oil acts in the direction of pushing up the needle valve, and the hydraulic oil acts only on the upper surface of the pinneton, so the structure of the fuel valve can be simplified and it can be operated at high speed as desired. . It also has the advantage that fuel oil and hydraulic oil can be easily separated.

[Brief explanation of drawings]

Figure 1 shows a conventional electronic control block diaphragm,
The figure is a sectional view showing details of the fuel valve, FIG. 3 is a block diagram showing an example of the present invention, and FIG. 4 is a sectional view showing details of the fuel valve. O"b...Fuel valve, 04)...Directional switching valve, αη・
...Electronic control unit, θ pump...Fuel pump, (a)
···accumulator. 4...electronically controlled pressure regulating valve, ←e...nozzle chamber,
2)...Needle valve, 2)...Seat, piston, cA...Fuel leakage reservoir, (G)...Hydraulic oil leakage reservoir 2 wheels...Fuel oil leakage Modo: hole, +11)...
・Hydraulic oil leakage hole agent Yoshihiro Morimoto Figure 4-461-

Claims (1)

[Scope of Claims] 1. In a fuel injection control system for a diesel engine using an electronic circuit, when the needle valve operation of a fuel valve is controlled by a maleta histone connected to the needle valve and incorporated in the fuel valve, a nozzle is provided. A fuel injection method for a diesel engine, characterized in that fuel oil supplied to a chamber acts in a direction to push up a needle valve, causes hydraulic oil to act on an upper surface of a piston, and switches the direction of hydraulic oil pressure. 2. Let the hydraulic oil pressure be a function of the injection pressure (fuel oil pressure),
3. The fuel injection method for a diesel engine according to claim 1, wherein the pressing force on the seat portion of the needle valve is adjusted. 3. The fuel injection method for a diesel engine according to claim 1, characterized in that the movement of the needle valve is measured and the injection is controlled using this measurement signal. 4. In a diesel engine fuel injection device that uses an electronic circuit and controls a needle valve operation of a fuel valve by a piston incorporated in the fuel valve by connecting the needle valve operation to the needle valve, the nozzle chamber to which fuel oil is supplied is provided. A fuel injection device for a diesel engine, characterized in that a tapered surface is formed at the tip of the needle valve, and a direction switching valve is provided for switching the direction of the pressure of hydraulic oil applied to the upper surface of the piston. 5. The fuel valve is characterized in that leakage oil return holes are provided in the cylinder chambers on the piston side and the needle valve side, respectively, to prevent mixing of hydraulic oil and fuel oil. Fuel injection device for diesel engines.