JPS59185866A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To have accurate injection of the fuel in a required amount through the use of a low pressure accumulator by furnishing a control device to control a one-way selector valve, a pressure regulator valve and a flow control valve in accordance with the operating condition of internal-combustion engine. CONSTITUTION:When a command signal is given from No.1 drive circuit 25 to a direction selector valve 64 so as to change over from (a) into (b), the outlet from a flow control valve 35 is put in communication with No.2 working oil inlet/outlet 60 to allow the working oil adjusted to Pressure P1 by a pressure regulator valve 33 to be fed into a pressurization cylinder chamber 62, and meantime the working oil in a decompression cylinder chamber 61 returns to oil tank 34. A piston 55 shafts now downward to compress the fuel oil in a pressure boosting chamber 58, and thus the fuel is injected. When the direction selector valve 64 is then changed over from (a) into (c), the working oil in said pressurization cylinder chamber 62 is released to the il tank 34, and meantime the working oil at Pressure P1 is fed to the decompression cylinder chamber 61 to actuate upward motion of pistons 54, 55.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device for an electronically controlled internal combustion engine.

An electronically controlled internal combustion engine is one that uses an electronic computer to achieve optimal operation control of a diesel engine, for example, and specifically controls the diesel engine's crank angle, rotational speed, torque, pressure and temperature of various parts of the engine, etc. The composition of exhaust gas, etc. is detected, and this operating data is processed by a computer according to a predetermined program to determine optimal operating control conditions, and the determined conditions are used as control command information to control the starting valve of the diesel engine. , the air supply valve, exhaust valve, fuel injection valve, etc. are opened and closed according to the crank angle.

FIG. 1 shows the overall configuration of this electronically controlled internal combustion engine. A diesel engine usually has a plurality of first to Nth cylinders (1), and each cylinder (1) has a starting valve (2), an intake valve (3), and an exhaust valve ( 4)
, a fuel injection valve (5) is equipped. (6)-(9)
is an actuator that operates these parts (2) to (5). Fuel oil is supplied from the fuel injection valve (May) by the fuel pump (B) from the fuel tank 0@. 0■ is the fuel pressure accumulator, (C) is the fuel cutoff valve, and Q41 is the check valve.

-4. The rotation angle of the crankshaft (g) is detected by the encoder oQ, and the input port aη and the data bus (to)
The detection output of encoder 0Q is input to the central processing unit (hereinafter referred to as CPU) (11) through the diesel engine control circuit and the frequency/voltage converter (j).
) is also sent as crank angle information. The signal converted into a voltage signal according to the rotational speed by the frequency/pressure converter 0υ is input to c p Ua* via the analog/digital converter (a) and the data bus (g). Also, the pressure and temperature of each part of the diesel engine.

The exhaust gas composition is detected by sensors (Sl) to (S6), and the data is sent to an analog/digital converter (
After being digitally converted by (a), it is input to CPU Ql.

The CPUQ field reads the operation command input from the setting manual/display device), and based on this operation command, analog/
Crank angle 2 rotation speed input from digital converter (A) etc., @Each part (D-EE-force and temperature).

Using data representing the operating state of the engine, such as exhaust gas composition, calculation of control variables and manipulated variables for optimal control of the engine is executed according to a predetermined program. and,
A control command for the fuel pump 0) is created from this calculation result, and the fuel pump (6) is controlled via a digital/analog converter. Furthermore, the CPU H creates joint control commands for the starting valve (2), intake valve (3), exhaust valve (4), and fuel injection valve (5) from the calculation results, and sends the control command to the diesel engine control circuit (4). ).

The diesel engine control circuit reads control commands from the CPU α and sends control information corresponding to the crank angle information obtained from the encoder Qη to the first and second drive circuits. The first drive circuit (c) is a control valve (a) that controls the actuation timing of the actuator (9).
to operate the fuel injection valve (5).

actuators (6) (7) (in the second drive circuit)
8) Control valves (4) that control the operating timing of each
@(g) is controlled to operate the start valve (2), the air supply valve (3), and the exhaust valve (4), and also control the operation of the fuel cutoff valve (to). In addition, in this example, actuators (6) to (
As a power source for driving 9), a working hydraulic pump (31) is used.
A pressure accumulator (3) for preventing pulsation is installed on the outlet side of the hydraulic pump (31). (Found) is a pressure regulating valve, (Found) is an oil tank, and (35) is a flow rate regulating valve.

However, the m84 of such an electronically controlled internal combustion engine
A conventional and common injection valve (5) is used.
In order to reliably inject the required amount of fuel oil, a high-pressure accumulator is required as a fuel pressure accumulation (fir 'J'), which has the disadvantage of resulting in an expensive system.

An object of the present invention is to provide a fuel injection control device that can reliably inject a required amount of fuel oil even when a low pressure accumulator is used as a fuel pressure accumulator.

The fuel injection control device of the present invention switches the direction of the fluid sent to the actuator to control the three operations of the fuel injection valve. A pressure increasing cylinder chamber is provided, a piston interlocked with the actuator is provided in the pressure increasing cylinder chamber,
A pressure regulating valve and a meteor control valve are provided in a flow path for supplying fluid to a directional switching valve that changes the direction of fluid sent to the actuator, and a pressure regulating valve and a meteor control valve are provided to supply fuel oil to the pressure increasing cylinder chamber, and the directional switching valve and pressure The present invention is characterized in that a control device is provided to control the regulating valve and the flow rate control valve according to the operating state of the internal combustion engine, and the fuel oil supplied to the pressure increasing cylinder chamber is injected after the pressure is increased.

Specifically, the control of the control device is to control the amount of fuel injected by time control of the directional switching valve, and to control the pressure (al?). The fuel injection pressure is controlled by the pressure control of the iI valve, and the fuel injection rate is controlled by the flow rate control of the flow rate control valve.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 2 and 3. Components having the same functions as those in FIG. 1 will be given the same reference numerals and their explanations will be given.

The actuator is a fuel injection device that functions as the fuel injection valve (5) and actuator (9) in FIG. The nut (4υ) has a male threaded part (4o) that is screwed into the male threaded part (e) of the nut.

(A) is a sealing material. The injection valve body (three of them are formed with the 141 manhole (44) of the needle valve (48), the needle valve chamber (the hole), and the injection hole (46) that communicates with this needle valve chamber (4). The needle valve is connected to the spring through the metal fittings.
The seat portion (19) of the needle valve chamber is urged by a predetermined urging force to close the nozzle hole (C).The actuator body (38) includes a communication passage (5Φ
1), a first cylinder chamber (5) for fuel oil pressure increase, which communicates with the needle valve chamber (2) through the needle valve chamber (1);
) for the actuator, which communicates with the second cylinder chamber (i
53) & is formed, and the 1st. Second cylinder chamber (
5 pistons (5 pistons and (2)
) are connected within the second cylinder chamber. (
56) is a relief hole formed in the piston, and when the piston (54) reaches the bottom dead center, the actuator body (
The intensifying chamber (5) communicates with the relief hole (57) formed in the
8) is configured to release the fuel oil to the outside of the actuator body (38).

(59) and (60) are the actuator body (G) respectively.
The first cylinder chamber (61) communicates with the pressurized cylinder chamber (6) and the outside of the actuator body (2). This is the second hydraulic oil inlet and outlet. Incidentally, fuel oil is supplied to the pressure increasing chamber at the lower part of the first cylinder chamber (52) via the check valve α→. (Foundation) is a center bypass type directional control valve as a control valve (B), and this directional control valve (Foundation), pressure regulation valve (3), and flow rate control valve (35) are controlled by the first drive circuit). has been done. (65) is a hydraulic oil flow path to the control valve (g) (401).

With this configuration, fuel oil is injected from the nozzle hole (46) in the following manner. Before fuel injection, the pressure of the fuel oil in the first cylinder chamber (5) is P, and the urging force of the needle valve by the spring (48) is 8, and the pressure of the needle valve is 8 as shown in Fig. The diameter is d, the diameter of the seat part el?) is d,
The opening diameter in the nozzle hole (4Φ seat part (49) is dnN
Assuming that the gas pressure in the cylinder of the internal combustion engine is Pg, the following equation 1 holds true just before the valve opens due to force balance.

Therefore, the pressure P of fuel oil when the valve is opened. is given by.

Now, when a command signal is given to the directional control valve (64) from the first drive circuit to switch it from the neutral position (A) to the forward position ° (B) as shown in Figure 2, the flow control valve (8 The outlet communicates with the second hydraulic oil inlet/outlet (7), and the hydraulic oil is supplied to the pressurized cylinder chamber (62) whose pressure is regulated to P1 by the pressure regulating valve (3), and the pressure-reducing cylinder chamber (61). The hydraulic oil returns to the oil tank (■) through the first hydraulic oil inlet/outlet (59).

When hydraulic oil force 5 with a pressure P1 is supplied to the pressurized cylinder chamber (6), the piston (A) [area Sl] moves downward to the piston Pl.
・The power of Sl is given. Therefore, piston (goods) [
The pressure Pf of the fuel oil in the pressure boosting chamber (58) is determined by the area S2).
1 will be injected. For example, p1 = 21oCkgf/cA
:) , -g-5, then P(= 210
5 = 10105o (lC/an). When the piston reaches the bottom dead center, the relief hole (5
6) and (5't) communicate with each other, allowing some of the residual oil in the pressure intensification chamber (58) to escape through the relief holes (56) and (57).
) pressure Pf<P. (This completes fuel injection.

On the other hand, at this time, the directional control valve (54)
When it reaches bottom dead center, it returns to the neutral position (A) and comes to rest.

Next, when the six directional control valves (6) are moved from the neutral position (A) to the reverse position (1) by the command signal from the first drive circuit (A), the hydraulic oil in the pressurized cylinder chamber φ■ It is opened to the tank ■, hydraulic oil at the pressure P1 is supplied to the decompression cylinder chamber (61), the piston moves upward, and new field oil is supplied to the pressure increase chamber. It is supplied via the fuel cutoff valve side and the check valve α→.Then, after the preset time required for the fuel oil to be supplied to the pressure boosting chamber (2), the directional control valve is moved to the reverse position. (1) to the neutral position (A). As a result, the piston (5 → (5) stops and prepares for the next injection.

Moreover, the pressure of the fuel oil after the injection hole (46) is opened is
The diameter of the piston is dl, its speed is vp, the diameter of the end nozzle hole is d, and the number of nozzle holes is 2. If the flow rate coefficient of the nozzle hole is α and the specific weight of the fuel is r (, then it is given by , and the fuel injection amount per unit time Qt (c
c/sec) C, given by. The amount of fuel injected per unit time, that is, the fuel injection rate, is an important factor that affects the performance of the engine. The nozzle hole diameter d, diameter d, etc. are specifications determined at the design stage, and in the end, the diameter of the cylinder 4. From the fifth equation, the coefficient by which the fuel injection rate can be changed is the piston speed V2. Therefore, in Fig. 2, the flow rate control valve (3) is controlled by the command signal of the first drive circuit @ to control the amount of hydraulic oil supplied to the pressurized cylinder chamber (6).
(,j/min) to determine the fuel injection rate appropriately.

Note that the pressure control valve (F) is also controlled by a command signal from the first drive circuit (G), thereby appropriately determining the fuel injection pressure.

In addition, in the present invention, since the actuator body is driven by hydraulic oil instead of fuel oil, the fuel pump is 0) compared to the conventional one in which the actuator for the injection valve is driven by fuel oil. It only needs to be small.

As explained above, according to the fuel injection control device of the present invention, fuel oil supplied at low pressure can be reliably increased in pressure and injected to the required amount. The fuel pressure accumulator in the fuel holding system only needs to be of low pressure, and the safety is also improved because high pressure fuel oil is supplied to the fuel injection valve only at the fuel injection timing.

Furthermore, since it uses a pressure-increasing piston system, the operating hydraulic pressure can be realized at low cost by combining commercially available hydraulic pumps, actuator control valves, pressure regulating valves, and the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electronically controlled diesel engine, FIG. 2 is a block diagram of the main parts of an embodiment of the present invention, and FIG. 3 is an enlarged view of the main parts of FIG. Qυ...Fuel pump, (A)...Fuel pressure accumulator, α unit...Fuel cutoff valve, a<...Check valve, (81)...
Operating hydraulic pump, (32)...Pressure accumulator, (33)...
・Pressure adjustment valve, (g)...Flow rate adjustment valve, (36)...
・Fuel injection device, (37)...-injection valve body, (38)
... Actuator body, (Foundation) ... Needle valve, (45
)・−・Needle valve chamber, (4... nozzle holes, (5Φ(5υ・・
・Communication hole, (5@(53)...1st and 2nd cylinder chambers, (goods))...Piston, (56) (5'i')
−・Relief hole, φ8) −・Pressure chamber, (59) (a) °“
. 1st. Second hydraulic oil inlet/outlet, (6υ...-reducing cylinder chamber, (6)...pressurizing cylinder chamber, (Foundation)--one-way switching valve. Fig. 2 25 Fig. 3

Claims (1)

[Claims] 1. In a fuel injection device that controls the operation of a fuel injection valve by switching the direction of fluid sent to an actuator, a pressure increasing cylinder chamber communicating with a needle valve chamber of the fuel injection valve is provided, and the pressure increasing cylinder chamber is connected to the actuator. 1) A pressure regulating valve and a flow rate control valve are provided in a flow path that supplies fluid to a direction switching valve that switches the direction of fluid sent to the actuator u, and fuel oil is supplied to the pressure increasing cylinder chamber. A fuel injection control device further comprising a control device that controls the directional switching valve, the pressure regulating valve, and the flow control valve according to the operating state of the internal combustion engine.