JPS6217342A - Fuel injection control system - Google Patents

Abstract

PURPOSE:To reduce vibration due to a torque fluctuation, by increasing or decreasing the quantity of injected fuel for each cylinder to minimize the difference between the average torque of all the cylinders and the torque of each cylinder, which corresponds to the injection of the fuel. CONSTITUTION:The torque of each cylinder, which is generated from the injection through a corresponding fuel injection valve 6a-6d to the next injection there through is detected by a torque sensor 3 provided at the crankshaft of an engine 5. The average torque of all the cylinders and the torque of each cylinder are compared with each other to turn on or off the switching element of an actuator drive circuit 8 so that the quantity of injected fuel through the corresponding injection valve is gradually reduced when the torque of the cylinder is higher than the average torque of all the cylinders and that the quantity of injected fuel is gradually augmented when the torque of the cylinder is lower than the average torque of all the cylinders. The torques of all the cylinders are thus controlled to be equal to each other.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection control system, and in particular, a system in which a torque sensor for measuring output torque is provided on the crankshaft of a diesel engine, and fluctuations in the output torque are controlled based on the detected value. The present invention relates to a fuel injection control method that controls the fuel injection amount so as to minimize it.

[Problems to be solved by conventional technology and invention]

Conventionally, methods for controlling the output torque of a diesel engine have been proposed. For example, detection signals from a crank angle sensor, water temperature sensor, accelerator opening sensor, engine speed, etc. are input into a computer, compared with a preset reference value, and the actuator operation of the fuel injection valve is controlled based on the comparison result. This controls the engine output torque. In this case, the fuel injection valves of each cylinder are controlled simultaneously by control signals from the computer.

However, even if the electric actuators used in the fuel injection valves of each cylinder are controlled using exactly the same control signal, slight variations in the amount of expansion and contraction of each electrostrictive actuator, mechanical variations, etc. will cause the fuel injection amount to vary between each cylinder. Variations may occur.

Such non-uniformity in injection amount may cause fluctuations in engine torque and worsen vibration or noise. Further, even if the control state is good in the initial operation, the unevenness of the fuel injection amount as described above may increase due to changes in the injection characteristics of the injector over time, which may have an adverse effect.

[Means for solving problems]

The present invention is a fuel injection control system for a diesel engine that solves the above problems. Basically, a torque sensor is provided on the crankshaft to accurately detect fluctuations in the output torque of the diesel engine, and the fuel injection control method for each cylinder is Find the average value of the output torque corresponding to According to the present invention, there is provided a fuel injection control method that controls fuel injection of an engine based on detection signals of a crank angle sensor, a water temperature sensor, and an accelerator opening sensor. A torque sensor for detecting the output torque of the engine is provided at a predetermined location, and fuel injection is performed in each cylinder based on the detection signals of the crank angle sensor, water temperature sensor, and accelerator opening sensor, and the detection signal of the torque sensor. The average value of output torque corresponding to It is characterized by the following.

〔Example〕

FIG. 1 shows 4 in which the fuel injection control method according to the present invention is implemented.
1 is a schematic configuration diagram of a cylinder diesel engine and its peripheral devices. In FIG. 1, 1 is an electronic control unit (EC
U) is configured by a microcomputer and outputs signals for controlling the drive circuit based on detection signals from various sensors.

2 is an accelerator opening sensor that detects the amount of depression of the accelerator pedal, and 3 is a torque sensor installed on the crankshaft to detect the engine output torque (
For example, strain gauge or magnetostrictive element), 4A, 4
B is a crank angle sensor, 4A outputs a 720°C eight signal, and B outputs a 180'CA signal. 5 is a diesel engine main body, 6a to 6d are fuel injection valves provided for each cylinder, 7 is a reservoir tank that supplies fuel to each fuel injection valve, 8 is a drive circuit that drives the electric actuator of each fuel injection valve, 9 10 is a water temperature sensor that detects the engine cooling water temperature, and 10 is a fuel tank.

In such a configuration, an accelerator opening sensor 2, a torque sensor 3, and crank angle sensors 4A and 4B.

Detection signals from the water temperature sensor 9 are input to the electronic control unit 1, and based on these signals, switching elements (not shown) of the actuator drive circuit 8 are controlled to turn on and off, thereby controlling the actuator of each fuel injection valve. The operation of the engine is controlled, and thereby the fuel injection amount is controlled. This control will be explained in more detail below.

FIG. 2 is a block diagram illustrating the electronic control system in more detail. The electronic control unit 1 includes a central processing unit (CP).
U) 11, memory lla, A/D converter 12, free run timer 13, timer conveyor register (14 to 17,
It is composed of output sofa registers 14a to 17a.

In such a configuration, the reference angular position for fuel injection is detected by the 720' CA multiplied signal and the 180° CA multiplied signal from the crank angle sensors 4A and 4B, and the corresponding arithmetic processing is performed in the processing routine described later. It is executed as shown, and mainly controls the output of the injection start timing. In this case, in order to reduce vibrations due to engine torque fluctuations, the fuel injection amount of each of the fuel injection valves 6a to 6d of each cylinder is adjusted so that the torque output between approximately 180' CA from injection to the next injection amount is It is detected by the torque sensor 3 shown in Fig. 1, and compared with the average value of the torque of all cylinders detected in the same way, and if the torque of a particular cylinder is larger than the average torque of all cylinders, the injection of the corresponding injector is Gradually reduce the amount,
In addition, when the torque is small, the output torque is gradually increased so that the output torque of all cylinders is output evenly. In this case, the basic injection angle and injection time corresponding to the engine condition are determined by the water temperature sensor 9.
, the accelerator opening sensor 2 and the crank angle sensors 4A and 4B are constantly calculated within the electronic control unit 1 and stored in its internal memory lla. Further, since the detection signal from the torque sensor 3 provided on the crankshaft is an analog signal, it is converted into a digital value by the analog-to-digital converter 12. Further, timer conveyor registers 14 to 17 and output pump registers 143 to 17a as output control boats are provided corresponding to the fuel injection valves 68 to 6d of each cylinder.

FIGS. 3A to 3D are flowcharts showing processing routines of the fuel injection control method according to the present invention, and these processing routines can reduce vibrations caused by engine torque fluctuations.

FIG. 3(a) shows the main processing routine, in which basic processing includes calculating the required injection amount for each cylinder and determining whether the engine is in a steady state.

First, in steps 1.2 and 3, calculation of the basic injection timing and basic injection time is performed at an injection start angle θ5.
, N, and the previous injection time BTINJ. Here, N is the engine speed, θ? +1 is the throttle opening and T)+111 is the water temperature.

Next, in step 4, the injection time correction calculation for each cylinder is
Injection time T for each cylinder of the cylinder engine. .

- Executed based on TINJ3. here 0~3
is a correction count for each cylinder. In step 5, a calculation of the variation ΔTINJ between the current and previous injection amounts is executed. Finally, in steps 6.7 and 8, it is determined whether the steady state is present. Here 1 is a positive constant, F C0N5
T is a flag that determines whether or not it is in a steady state, and is ``0''
indicates no change.

FIG. 3(b) shows a 180' CA double signal interrupt processing routine, in which detection of angular position and setting of injection output time are executed as basic processing. First, step 1.
2 and 3, the basic angular position is detected based on the crank angle counter (every 180'), and in step 4, the injection start angle θ8. The time TSt until then is calculated. Finally, in steps 5, 6, 7 and 8, the injection start time and output level are stored in the timer conveyor registers 14 to I7 for injection output control. Here, TcU, , is C
The free run timer value in the PU, TCMP, is a register for comparison with the free run timer, and if it fails, it outputs the buffer output value to the output port and requests a conveyor match interrupt. Further, 0UT(CA) is an output data temporary storage register prepared for each CA=0 to 3.

FIG. 3 (C1 is the conveyor timer one-defeat interrupt processing routine, and the basic processing is the 7th, 18th, 18
Calculation of the output torque average value during CA 0'' and correction of the injection amount correction coefficient, etc. are executed.In steps 1 to 5, it is checked whether or not injection has started, and if it has started, the injection stop time is set. The timer conveyor registers 14 to 17 are set, and the stop output is sent to the output boats 14a to 17a.In step 6, it is checked whether or not it is in a steady state.In steps 7 to 11, the average torque between 1806CA and the torque value are calculated. It is stored in the RAM for the corresponding cylinder. In step 12, the difference between the average torque during 720' CA and the current value is calculated. In steps 13 to 16, if the output torque from the corresponding cylinder is too large, the injection coefficient is reduced (xo , 99), if it is too small, increase it (X 1
．． 01). Here, 2 is a positive constant. Finally, in step 17, the working RAM for torque integration is cleared.

FIG. 3 (dl is an interrupt processing routine for A/D conversion.

This routine inputs the torque data value after A/D conversion in step 1, counts up the number of measurements in step 2, calculates the torque data in step 3, and finally starts A/D conversion of the next torque. . Here, 5TRQ is the integration of the A/D converted value of torque, CT is the number counter for integrating the A/D converted value of torque, and ΔTRQ is the difference between the specific cylinder torque and the average torque for four cylinders.

FIGS. 4(a) to 4(h) are angular signal tanning charts, which represent the above-mentioned explanation.

(a) is a 7206 signal, (b) is a 180' signal, (C
) is 180' interrupt processing, (dl is timer match interrupt processing, (Ql is timer conveyor register value, (fl is C, P
[J free run timer, (g) is for each fuel injection valve 68-6
d is the injection output, and (h) is the output of the torque sensor 3 provided on the crankshaft. Here, the horizontal axis of these timing charts is time T.

〔Effect of the invention〕

According to the present invention, a torque sensor is provided on the crankshaft of a diesel engine to directly detect engine torque fluctuations, and this is fed back to control the injection amount, so that the optimal fuel injection amount can always be obtained and the engine Vibrations caused by torque fluctuations can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an engine implementing the fuel injection method according to the present invention and its peripheral equipment, FIG. 2 is a block diagram of the electronic control unit shown in FIG. 1, and FIG. The main processing routine, FIG. 3(b), is the 180' CA signal interrupt processing routine, FIG.
1 is a conveyor timer match interrupt processing routine, FIG. 3(d) is an A/D conversion interrupt processing routine, and FIG. 4 is a timing chart of each signal. (Explanation of symbols) 1... Electronic control unit, 2... Accelerator angle sensor, 3... Torque sensor, 4A, 4B... Crank angle sensor, 5... Engine, 6A to 6d... Fuel injection valve, 7... Reservoir tank, 8... Drive circuit, 9... Water temperature sensor, 10... Fuel tank, 11... Central processing unit, 12... A/D converter, 13... Free run timer, 14-17... Timer conveyor register, 14a-1
7a...Output buffer register. Schematic configuration diagram of the engine and its peripheral devices 1st Figure 3...Torque sensors 60 to 6d...Fuel injection valve 9...Water temperature sensor 10...Fuel tank electronic control unit block 2nd Figure Main processing routine 3 Figure (Q) 180°CA signal interrupt processing routine Figure 3 (b) A/D conversion interrupt processing routine Figure 3 (d) Each signal timing chart Figure 4

Claims (1)

[Claims] 1. In a fuel injection control method that controls engine fuel injection based on detection signals from a crank angle sensor, a water temperature sensor, and an accelerator opening sensor, a torque sensor that detects the output torque of the engine is provided at a predetermined location, and the crank angle Based on the detection signals of the sensor, water temperature sensor, and accelerator opening sensor, and the detection signal of the torque sensor, the average value of the output torque corresponding to the fuel injection of each cylinder is determined, and the average value is calculated as the average output torque of all cylinders. A fuel injection method characterized in that the fuel injection amount for each cylinder is controlled so that the difference between the two is minimized based on the comparison result.