JPH04159435A - Fuel injection controller of two-cycle diesel engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection control device for a two-stroke diesel engine.

[Conventional technology]

BACKGROUND OF THE INVENTION Conventionally, in diesel engines, the amount of fuel injection has been electronically controlled in accordance with engine speed, engine load, such as throttle opening, etc.

For example, in the method described in Japanese Patent Application Laid-open No. 63-18252, when correcting the maximum fuel injection amount so that it decreases as the intake air temperature increases, the ratio of correction of the maximum injection amount is varied depending on the engine speed. , which prevents smoke from occurring when the intake temperature rises.

[Problem to be solved by the invention]

However, in a two-stroke engine, air exists in the atrium, and the strength of the air flow due to scavenging air in the combustion chamber changes. This changes the mixing of fuel and air and changes the level of smoke. Conventional equipment determines the maximum fuel injection amount based on engine speed, throttle opening, and intake temperature.
Since the fuel injection amount is limited, there is a problem in that if it is directly applied to a 2-stroke diesel engine, smoke will occur.

The present invention was developed in view of the above points, and the present invention suppresses the occurrence of smoke by determining the maximum fuel injection amount from the intake air amount, intake efficiency, and mixing efficiency determined by the operating condition and regulating the actual fuel injection amount. An object of the present invention is to provide a fuel injection control device for a two-stroke diesel engine that prevents the above.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention. In the figure, detection means M2
detects the operating state of the two-stroke diesel engine Ml.

The injection amount calculation means M3 calculates the basic fuel injection amount according to the detection signal of the detection means M2.

The maximum injection amount calculating means M4 calculates the intake air amount of the engine, the intake efficiency in which the intake air remains in the fuel chamber, and the mixing efficiency of the intake air and fuel in accordance with the detection signal of the detection means M2, and calculates the intake air amount and the mixing efficiency of the intake air and fuel. The maximum fuel injection amount is calculated from the intake efficiency and mixing efficiency.

Regulation means M5 uses the smaller of the basic fuel injection amount and the maximum fuel injection amount as the actual fuel injection amount supplied to the engine Ml, and regulates the actual fuel injection amount by the maximum injection amount.

[Effect]

In the present invention, the intake air amount, intake efficiency, and mixing efficiency of a 2-stroke diesel engine are determined from the engine operating conditions, and by these calculations, the maximum fuel injection amount without smoke generation is obtained for the 2-stroke diesel engine. Sometimes, when the basic fuel injection amount used as the actual fuel injection amount exceeds the maximum fuel injection amount, the actual fuel injection amount is regulated by the maximum fuel injection amount.

〔Example〕

FIG. 2 shows a configuration diagram of a two-stroke diesel engine to which the device of the present invention is applied.

In the figure, 1 is the engine body, 2 is the piston, 3 is the cylinder head, 4 is the main combustion chamber, 5 is the fuel injection valve, 6 is the pre-combustion chamber, 7 is the intake valve, and 8 is the intake port. Main fuel chamber 4
and the pre-combustion chamber 6 are communicated through an injection port 9.

The air supply boat 8 is connected to a surge tank 12 via an air supply branch pipe 11.
connected to. The surge tank 12 is connected to an air cleaner 22 via an intake passage 21, and a throttle valve 23 is disposed within the intake passage 21. An engine-driven mechanical supercharger 20 is disposed within the intake passage 21, and this mechanical supercharger 2
A bypass passage 24 is provided that connects the upstream and downstream intake passages 21 of 0 to each other, and the bypass passage 24
A bypass control valve 2 for controlling the opening and closing of the bypass passage 24 inside the
6 is provided.

The electronic control unit 40 includes ROM (read-on memory) 42. which are interconnected by four bidirectional buses. R.A.
M (random access memory) 43, CPU (microprocessor) 44. Backup RAM45. It has an input port 46 and an output port 47. Throttle valve 2
3 is connected to a throttle sensor 35 that generates an output voltage proportional to the opening of the throttle valve, and the output voltage of this throttle sensor 35 is input to the input port 46 via the AD converter 53. Further, the output voltage of the intake air temperature sensor 32 is inputted to the input port 46 via the AD converter 52.

Further, the input port 46 is connected to a rotation speed sensor 55 that generates an output signal representing the engine rotation speed NE, and a crank angle sensor 56 that generates an output pulse every time a crankshaft (not shown) rotates by a certain angle. . - the force output port 47 is connected to the fuel injection valve 5 via a drive circuit 58;

FIG. 3 shows a flowchart of one embodiment of the fuel injection control process. This process is part of the main routine, and several meters
Executed every 5ec.

In the same figure, in step 61, a basic fuel injection amount map is referred to from the rotation speed NE and the throttle opening TA to calculate the basic fuel injection amount Qac, which is a function of the rotation speed NE and the throttle opening TA.
Find cp (TA, NE).

Next, in step 62, the rotation speed NE and the throttle opening TA are
and the intake air amount Q, which is a function of the intake air temperature THA, (N
E, TA, THA). Here Q, (NE, T
A, THA)=QA' (NE, TA)XF (TH
A) It is determined by multiplying the function QA' (NE, TA) of the rotational speed NE and throttle opening TA expressed by the function F (THA) of the intake air temperature THA. Function QA' (
NE, TA) are determined by referring to the characteristic map shown in Fig. 4, which shows the throttle opening TA as a parameter, and the function F (
THA) is determined by referring to the characteristic map shown in FIG.

The intake air amount Q is equal to the throttle opening TA when the rotation speed is low.
The influence becomes greater as the rotational speed NE increases. Furthermore, on the high rotation side with the throttle fully open (WOT), it decreases due to the intake resistance of the engine. In addition to influencing the air density, the intake air temperature THA also affects the mechanical supercharger 20.
The characteristics shown in FIG. 5 are used because the efficiency changes due to temperature are also affected.

Since this embodiment has a bypass control valve 26, the intake air amount Q is determined according to the opening and closing of this bypass control valve 26. Furthermore, when a sub-throttle is provided, the intake air amount Q is similarly determined according to the opening degree of the sub-throttle.

In step 63, the intake efficiency TR, which is a function of the rotational speed NE, which represents the yield rate at which the inflowing air remains in the fuel chamber 4, and the intake air temperature TA, (NE, TA) is determined by referring to the characteristic map shown in FIG. I ask.

The intake efficiency TR becomes shorter as the opening time of the intake and exhaust valves increases as the rotation speed increases, so basically the intake efficiency TR approaches 1.0 as the rotation speed increases.

Further, as the throttle opening becomes smaller, the pressure difference before and after the mechanical supercharger 20 becomes larger, the temperature downstream of the supercharger increases, and the intake efficiency decreases.

In step 64, the mixing efficiency Fm i x (NE) is a function of the rotational speed NE and the intake air temperature TA.

TA) is determined by referring to the characteristic map shown in FIG.

Mixing efficiency Fm1x decreases because the in-cylinder scavenging air flow is weak at low rotation speeds or low throttle openings, and tends to increase as the rotation speeds or throttle openings increase, and the mixing time becomes shorter at high rotations. Therefore, there is a tendency for it to decline somewhat.

In step 65, the intake air amount Q, , (
NE, TA, THA) Intake efficiency T□, (NE, TA),
Using the mixing efficiency Fm1x (NE, TA), the maximum fuel injection amount Qmax is determined by the following formula.

Qmax=Q, XTR, XFm1x After this, in step 66, the basic fuel injection amount Qaccp and the maximum fuel injection amount Qmax are compared,
ccp is less than the maximum fuel injection amount QmaX, step 67 changes the basic fuel injection amount Qaccp to the actual fuel injection amount Q.
If the basic fuel injection amount Qaccp exceeds the maximum injection amount Qmax, the maximum fuel injection amount Qamx is set to the actual fuel injection amount Qf in step 68.

Thereafter, in step 69, injection control corresponding to the actual fuel injection amount Qf is executed. For example, move the spill position to a position equivalent to injection. Alternatively, change the opening timing of the spill valve to correspond to the injection amount.

In this way, from the engine operating condition, the intake air amount Qll+ of the 2-cycle diesel engine, the intake efficiency TR,
The mixing efficiency Fm1x is calculated, and by these calculations, the maximum fuel injection amount Qmax without smoke generation is obtained in a 2-stroke diesel engine, and the basic fuel injection amount Qaccp, which is used as the actual fuel injection amount Qf in normal times, is the maximum fuel injection amount above. When Qmax is exceeded, the actual fuel injection amount Qf is regulated by the maximum fuel injection amount Qmax. For this reason, air exists in the atrium, and in a two-stroke diesel engine where the strength of the flow due to scavenging air changes, the actual fuel injection amount will not be excessive, and smoke can be prevented from occurring.

〔Effect of the invention〕

As described above, the fuel injection control device for a two-stroke diesel engine according to the present invention can prevent the occurrence of smoke in a two-stroke diesel engine, and is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a configuration diagram of an embodiment of an engine to which the device of the present invention is applied, Fig. 3 is a flowchart of fuel injection control processing, and Figs. It is a characteristic diagram of the map referred to in the processing of the figure. 4... Main fuel chamber, 5... Fuel injection valve, 6... Pre-combustion chamber, 32... Intake temperature sensor, 35... Throttle sensor, 55... Rotation speed sensor, 56... - Franch angle sensor, 61-69...step, Ml...2-cycle diesel engine, M2...detection means, M3
. . . injection amount calculation means, M4 . . . maximum injection amount calculation means, M5 . . . regulation means. Patent Applicant Toyota Motor Corporation Figure 1 Figure 2 Figure 4 NE Figure 5 20'CTl-IA Figure 6 NE Figure 7

Claims (1)

[Scope of Claims] Detection means for detecting the operating state of a two-stroke diesel engine; injection amount calculation means for calculating a basic fuel injection amount according to a detection signal of the detection means; The maximum injection method calculates the maximum fuel injection amount from the intake air amount, intake efficiency, and mixing efficiency by determining the intake air amount of the engine, the intake efficiency in which the intake air stays in the fuel chamber, and the mixing efficiency of the intake air and fuel. a quantity calculating means; and a regulating means for regulating the actual fuel injection quantity by the maximum injection quantity, using the smaller of the basic fuel injection quantity and the maximum fuel injection quantity as the actual fuel injection quantity supplied to the engine. A fuel injection control device for a two-stroke diesel engine, characterized in that it has the following features: