JPS5963333A - Combustion control device for diesel engine - Google Patents

Abstract

PURPOSE:To aim at preventing generation of black smoke and as well enhancing the startability of a Diesel engine, by providing a map characteristic of decreasing the supply amount of fuel upon running at a low speed, a map characteristic of increasing the supply amount of fuel and the advance of fuel injection, etc., so that a predetermined map is used in accordance with drive conditions. CONSTITUTION:There are provided maps 50, 51, 52, 53, 54, 55, 59 indicating the characteristics of full-load mode fuel injection (QFULL), the characteristics of running mode fuel injection (QAPP), the characteristics of idle mode fuel injection (QIDLE), the characteristics of starting mode supercharge amount (QSTART), the characteristics of burning temperature compensation, the characteristic of overrun prevention and the characteristics of a pump, respectively. In accordance with drive conditions, a predetermined map is used selectively from the above-mentioned maps. The characteristics of starting mode supercharge amount is to set the amount of fuel injection in accordance with a cooling water temperature Tomega. With this arrangement, the prevention of black smoke generation and as well the enhancement of engine startability may be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion control device for a diesel engine that improves the startability of a diesel engine having a combustion chamber with a large opening and reduces the generation of black smoke.

In order to improve the fuel efficiency of a diesel engine, widening the opening of the combustion chamber can reduce NOx, fuel consumption, noise, etc. compared to a combustion chamber with a smaller opening at the same injection timing, but at constant speed, The full load fuel injection amount and injection timing can be freely set to suit the limited low speed rotation range. In addition to not being able to freely set the advance angle, it is also not possible to freely set the engine rotation at which supercharging should be released, so there is a problem that the optimum supercharging amount and advance angle cannot be selected for starting, resulting in poor starting performance. Ta.

On the other hand, in conventional mechanically controlled injection pumps, the degree of freedom in controlling both fuel flow rate and injection timing is limited, and the above-mentioned problems cannot be addressed.

By the way, electronic engine control using a microprocessor has become commonplace in gasoline engines, but in diesel engines, systems that only control injection timing, and special systems such as those in fire engines, are used. Only those for specific applications have been put into practical use, and these are used only for those with narrow combustion chambers that do not have problems such as the generation of black smoke or poor starting performance, and are generally used for It is not intended to control the engine due to the above-mentioned requirements, and it also prevents the generation of black smoke at low speeds as mentioned above.
No countermeasures were taken for the open engine, which has a wide combustion chamber and suffers from problems such as poor startability.

Therefore, the present invention aims to improve engine performance using an electronic control circuit under various conditions for engines with wide open combustion chambers that have problems such as the generation of black smoke and poor startability during low speed rotation. The purpose of the present invention is to provide combustion control equipment for a tea cell engine that solves these problems and further improves NOx, fuel consumption, noise, etc. by controlling the above.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a control system, and in the figure, 1 is a control unit, 10 is a sensor, and includes an accelerator position sensor 11, a fuel injection pump system control sleeve sensor 12, an engine speed sensor 13, a fuel temperature sensor 14, This control system includes a cooling water temperature sensor 15, a vehicle speed sensor 16, etc., and each of the sensors described above is used in this control system. Reference numeral 20 denotes a travel switch, which includes a main switch 21, a cent switch 22, a resume switch 23. Brake, clutch switch 24, air condition switch 25 and start switch 26
etc., and each of the above-mentioned switches is used in this control system. 3o is an actuator unit related to the fuel injection pump, and has an electronic cover +-31 and a timing control valve 32. 40 is the controlled object, tq,
i'+ injection: 'A-41, fuel injection timing 42, auto idle control tachometer 6. Here, the automatic driving control 44 is performed under the indication of the driving lamp 2, self-diagnosis is performed under the indication of the diagnostic lamp 3, and furthermore, the tachometer 6
is directly controlled from the control unit 1. The control unit consists of a microcomputer consisting of a central processing unit (CPU), a read-only memory (ROM), a readable/writeable memory (RAM), an input/output interface, etc., and is controlled by signals from the sensor lO and the switch 20 according to the stored characteristics. The controlled object 40 is controlled by actuating the actuator 30 or without using the actuator.

Figure 2 shows the fuel injection amount control system, and in the figure,
50 is the full load injection characteristic Qpuxi. 5 1 is the running injection characteristic QA, P. 52 is the idle injection characteristic QxoLc, 5
3 is the initial supercharging characteristic QsrAeτ, 54 is the fuel temperature correction characteristic, 5
5 is a map representing overrun prevention characteristics, 59 is a map representing pump characteristics, 56 is a map representing cruise Q, and 57 is a map representing MAX.
ilq selection circuit; 58, MIN selection circuit; 60, self-diagnosis fuel check circuit; 61, PID control circuit; 62;
is the injection amount actuator, 63 is the injection amount sensor, Nt is the engine speed, API) is the accelerator pedal opening, Tw is the cooling water temperature, VhAt is the battery voltage,
A/C is air conditioner switch (25), Vc is vehicle speed, ST
represents the starting switch (26), U=tsoLL represents the target injection amount (voltage), and U-ES represents the actual injection amount (voltage).

Full load injection characteristics (QFLJLL) 5 0 is the rotation speed N
The fuel injection amount can be freely and finely set according to E.

Traveling injection characteristics (QAPP') 5 1 is rotation speed NB
, Ak.

The fuel injection amount can be freely set depending on the cell pedal opening degree APP.

Starting supercharging characteristics (QsrApy) 5 3 is the rotation speed
, the fuel injection amount can be freely set depending on the cooling water temperature Tw. The starting motor with starting supercharging characteristics is NE-
0. ST starts with ON, NE = 900r. p. m or more and ST is off, the starting motor is canceled and 1 normal mode is started.

The idle characteristic 52 performs feedback control of the engine rotation speed during idle to maintain a constant rotation. It also has an idle function that rotates a certain number of revolutions, and the number of revolutions Nε at water temperature Tw.
The relationship is 800r, p, m, below 20°C.
At 50°C or higher, it is 620r, p, m, and from 20'C to 50°C, it changes linearly between the rotational speeds shown in -.

The battery voltage Vsxv decreases from 80Or, p, m to 620r, p, m at 13V, and increases at 11V.

Air conditioner switch A/C is 620r, p, m when off
and 80 Or, p, m when on. In terms of idle characteristics, cooling water temperature Tw, battery voltage VBA,
A 3-mode OR logic circuit is configured with a near cons inch A/C, and either Tw, VeAl, or A/C (7) is 80
When applicable to Or, p, m, a signal is generated to supply the fuel injection amount corresponding to the rotation speed, and T W , V
When all of the 8A and A/C correspond to 60Or, p, and m, a signal is generated to supply the fuel injection amount corresponding to the rotation speed, and VaA and the A/C correspond to 600r, p, and
m iJ, and when Tw is between 20°C and 50°C, a signal is generated to supply a fuel injection amount corresponding to Tw. Pump characteristic 59 converts QsoLt (target injection part) into voltage and obtains target injection amount U30 as voltage.
LL is obtained.

FIG. 3 shows a fuel injection timing control system, and in the figure, reference numeral 64 indicates normal water temperature correction, and the supplementary advance angle, which is a correction value ΔD 1 , is determined according to the rotational speed NE and the cooling water temperature TW.

65 is the starting water temperature correction, and like the normal water temperature correction 64, the correction value is 6 by NE and Tw.

The corrected advance angle is determined. In this case, the starting mode is NE.
= 0kST starts on, NE = 90Or, p, l
When the ST is turned off and A p = 0, the starting mode is canceled and the normal mode is started.

66 is a timing core troll valve (TCV) driving frequency, which converts the rotational speed Nε signal into a frequency for driving the TCV and outputs it to the TCV driving circuit.

Reference numeral 67 is a load timer characteristic, and the tute is obtained by the rotational speed N [11 standard fuel "l't Q4' Rf Qsott".

68 is the fuel temperature correction ΔDF, which is the fuel temperature correction ΔDF at a certain rotation speed Na
If the fuel temperature TF is low, the correction ΔDF will be negative, and if it is high, the correction ΔDF will be positive.

Reference numeral 69 denotes a TCV drive circuit, which controls the TCV drive frequency by duty to operate a fuel injection timing actuator (TCV) 70 at an injection timing proportional to the duty ratio.

FIG. 4 shows a swirl chamber type combustion chamber, in which (A) is a typical combustion chamber, and (B) is a combustion chamber with a wide opening to which the fuel control device of the present invention is applied.

FIG. 5 is a flowchart 1 showing the operation of FIG. 2.

Start the engine, if it is not idling, add the fuel injection amount for idle characteristics and driving characteristics, compare it with the fuel injection amount for cruise, choose whichever is greater, and compare with full load fuel injection M: Qt-utt. and choose the smaller one, Q+io
++s7 o. If this is greater than the maximum rotation speed of 900r, p, m in starting mode, then
The target fuel injection maximum is Q5QLL, and if it is small, Qsw
r becomes Q5otL. A corrected fuel injection amount ΔQpuεL corresponding to the rotational speed is added to this Q50LL. This value is converted into a voltage value and set as the target injection amount (voltage) UILSOLL.

At this time, if there is an abnormality in this UvsoL according to the self-diagnosis, the fuel will be reduced to the lowest speed operation, and if there is no abnormality, the PI
The injection amount actuator is operated by D control.

FIG. 6 is a flowchart showing the operation of FIG. 3. Duty DLOA that starts the engine and corresponds to the rotation speed
Find D. Engine speed 90Or, p',
DLT is obtained by adding respective water temperature corrections based on m as a reference and depending on whether it is the time of starting or not. A correction ΔDf based on the fuel temperature is added to this DLT to obtain DTCV. This duty D dcv is converted to a frequency f in the T'CV drive circuit.
T6. ．． c drive to operate the timing control valve, which is the fuel injection timing actuator.

The generation of black smoke at low speeds in engines with wide-opening combustion chambers is caused by too much fuel being supplied.

Therefore, it is a good idea to reduce the amount of fuel supplied at low speeds. Measures for this purpose are taken in the QF-characteristics in FIG.

By reducing the amount of fuel injected at low speeds in this manner, smoke becomes better, and the injection timing can be advanced until a certain smoke limit is reached, thereby further improving fuel efficiency. If this is done with a mechanical pump, the lowering of QPL at low speeds will also work in other areas, resulting in lower torque and lower output, and there will be no point in using an engine with a wide open combustion chamber. , 800r, p, m The starting time is determined by the starting supercharging amount Q, rA and the starting advance angle TsrA.
Determined by the lock. The optimum injection timing T, determined by this TswT, does not reduce the starting time even if supercharging exceeds a certain amount of supercharging QA.In the case of mechanical injection, the injection timing is determined by N4, A device that can advance the engine angle only at the time of starting has not been put into practical use.On the other hand, in the implementation of the present invention, the advance angle can also be freely set by correcting the water temperature at the time of starting, as shown in FIG.

The starting supercharging amount QA can be set using a mechanical pump, but the engine speed cannot be increased to cancel supercharging. In other words, it is not possible to obtain a supply amount that is inversely proportional to the rotational speed.

For this starting supercharging amount, switching between the starting mode and normal mode shown in Figure 2 can be freely selected, so supercharging at starting is possible, the best QA and TA can be selected, and the starting time or Can be shortened.

In addition, near 1000 r, p, m, mechanical pumps are sluggish due to injection timing characteristics, but in the inventive example, the injection timing is optimized around the relevant rotation speed, and the engine runs well. As explained in detail above, the present invention includes various sensors for detecting accelerator position, rotation, cooling water temperature, etc., various switches for operating the main, starting, etc., and a sensor for operating the fuel injection pump. an actuator for each Ilr+, and a controller for operating the actuator and controlling fuel injection amount, fuel injection timing, etc. in response to signals from each sensor and each swift; A memory is provided to store a map with full-load injection characteristics that sets a small amount of fuel supply at low speeds, and a map that increases the amount of fuel supply and injection advance depending on the cooling water temperature at startup, and increases the number of revolutions. The fuel injection amount and fuel injection timing are controlled by applying predetermined maps based on signals from sensors, cooling water temperature sensors, etc., thereby preventing the generation of black smoke and improving startability of engines with wide-opening combustion chambers. I tried to do this, so -
In an engine with a wide open combustion chamber, NOx,
It has become possible to maintain the combustion chamber in a good condition with respect to fuel consumption and noise, prevent the generation of black smoke, and improve startability.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram of the embodiment of the invention, Fig. 2 is a block diagram of the fuel injection amount control system, Fig. 317 is a block diagram of the fuel injection timing control system, and Fig. 4 is a sectional view showing the shape of the combustion chamber. , FIG. 5 is a flowchart 1 for the one in 21m, and FIG. 6 is a flowchart for the one in FIG. 3. 1. Controller, 10. Sensor, 11.φ Acposition sensor, 13. Engine speed sensor, 15. Cooling water temperature sensor, 20e11 switch,
2nd work...Main switch, 26Φ/Start switch, 30
・・Actuator, 31・・Electronic governor, 32・
Timing control valve, 50-55.64.6
5.67.68...Matpu patent applicant Isuran Jidosha Co., Ltd. Agent Patent attorney Minoru Tsuji (2 others)

Claims (1)

[Claims] (1) Various sensors that detect accelerator position, rotation, cooling water temperature, etc., various switches for main and start operations, actuators for operating the fuel injection pump, and each of the above-mentioned sensors and switches. and a controller that operates the actuator and controls fuel injection amount, fuel injection timing, etc. according to a signal from the controller.
The controller stores a map that corresponds to the rotational speed and has the characteristic of reducing the amount of fuel supplied at low speeds, and a map that has the characteristic of increasing the amount of fuel supplied and the injection advance angle depending on the water temperature at startup. A memory is installed, and the fuel injection amount and fuel injection timing are controlled by applying predetermined maps based on signals from the rotational speed sensor, cooling water temperature sensor, etc. A combustion control device for a diesel engine designed to prevent combustion and improve startability.