JPS6017248A - Control device of idle speed in diesel engine - Google Patents

Abstract

PURPOSE:To decrease the amount of undershoot when an engine is decelerated so as to operate the engine in stable drivability, by first setting the minimum value of a fuel injection amount a little larger and moving a control sleeve position in accordance with the condition of feedback control so as to correct a reference injection amount. CONSTITUTION:A microcomputer 11, to which the detected value of an engine condition is input, outputs a preset target position signal of a control sleeve 2 to an arithmetic circuit 13 and inputs a position signal of the sleeve 2 detected by a sleeve position detecting circuit 18 on the basis of the signal of a sleeve position sensor 17 in a fuel injection pump 16. In this way, feedback control is performed so that an actual sleeve position may be approximated to the target sleeve position by comparing the actual sleeve position with the target sleeve position to be calculated so as to output a driving pulse from a driver circuit 15 to the coil of a solenoid actuator 3. As a result, an engine is prevented from its operative disorder and generation of an engine stop by decreasing the amount of undershoot when the engine is decelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to idle speed control (ISI device) for a diesel engine equipped with an electronically controlled fuel injection pump.

<Background Art> Some diesel engines are equipped with an electronically controlled distribution type fuel injection pump as shown in FIG. In this device, a control sleeve 2 is slidably inserted into a plunger 1 that reciprocates as it rotates to distribute and force fuel to each cylinder, and an electromagnetic actuator 3 is driven based on a signal from a control circuit (not shown). To change the timing when the cut-off port 1a formed in the flange 1 is removed from the edge of the control sleeve 2 and opens into the suction space 5 in the pump housing 4 to become a fuel injection path. The amount of fuel injection is controlled accordingly. Further, the injection timing is electronically controlled by driving a timer mechanism (not shown).

A method for controlling the injection amount during idling of a diesel engine equipped with such an electronically controlled distribution type fuel injection pump will be explained with reference to FIG. When the ignition switch is turned on, the injection amount control routine starts, and first the target value QSE of the fuel injection amount is set based on the engine speed and the accelerator opening.
Read T from the map stored in memory (Sl). Next, read the engine's target rotation speed of 1'98FIT according to the cooling water temperature (hereinafter referred to as water temperature) under the conditions of performing idle speed control (ISC) (JIS 2), and check the actual engine rotation speed N! Compare with 1138R (S3). And when N8 BT<NMB8 R, I
Decrease the fuel injection amount correction amount Qisc by a minute amount during SC S4), N8 ET) Increase Qisc by a minute amount when NMFi 8 R S5), N5BT2IJM
In the case of E8R, Qisc is maintained at the current value (initial value 20) (S6), and the value obtained by adding this Qisc and Q SET is set as the new QSF! T is set (S7).

Next, the target position of the control sleeve in the fuel injection pump (hereinafter referred to as target sleeve position) is read from the map based on the Q81T and the engine speed, and a signal thereof is output (S8).

In this way, the electromagnetic actuator 3 is driven based on the target sleeve position signal output from the microcomputer and the signal from the sensor that detects the control sleeve position installed in the fuel injection pump, and the control sleeve position is feedback-controlled to fuel the fuel injection pump. Controls the injection amount.

However, in such conventional idle speed control devices, the target value of the fuel injection amount is set to a fairly small value in consideration of the roughness of the pump and system, aging, etc. Since the correction value provided by the torque control is sufficient, undershoot may occur when decelerating from high rotation, and in extreme cases, the engine may stall.

<Object of the Invention> The present invention has been made in view of the above conventional problems, and provides an idle speed control for a diesel engine that eliminates the above problems by correcting the basic injection amount of fuel injection. The purpose is to provide equipment.

<Summary of the Invention> For this reason, the present invention provides a basic injection amount setting means for setting the basic injection amount in the idling operating range, as shown in FIG. an injection amount correction amount setting means for setting a correction amount of the injection amount by integral control; a basic injection amount correction means for reducing the basic injection amount when the correction amount becomes 0; and a basic injection amount and correction amount. and a means for setting the control position of the injection amount control member of the fuel injection pump corresponding to the set value of the injection amount added by the addition means. shall be.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Fourth
The figure shows the configuration of one embodiment. Detected values such as engine speed, accelerator opening, and cooling water temperature are input to the microcomputer 11, which is composed of Ilo, CPU, memory, etc.
1 sets the target position of the control sleeve of the fuel injection pump corresponding to the fuel injection amount according to a flowchart to be described later, and outputs a signal thereof.

This digital signal is converted into an analog signal by the D/A converter 12 and output to the arithmetic circuit 13.

The calculation circuit 13 includes a sleeve position detection circuit 18 based on the target sleeve position signal and other signals from a sleeve position sensor 17 provided in the electronically controlled fuel injection pump 16.
A signal of the control sleeve position detected by the control sleeve is input. The arithmetic circuit 13 compares and calculates the target sleeve position and the actual sleeve position, and the pulse converter 14 receives the result and converts it into a drive pulse of a constant frequency according to the input signal voltage, and converts the drive pulse into a drive pulse in the drive circuit. 15 to the coil of the electromagnetic actuator 3, feedback control is performed to bring the actual sleeve position closer to the target sleeve position.

Next, a method of setting the target sleeve position during idling according to the present invention by the microcomputer 11 will be explained with reference to the flowchart shown in FIG. Sll determines whether the I80 condition (accelerator fully open position and neutral or vehicle speed is below a predetermined value) is met, and if it is other than the SC condition, Qisc = 0 (S23), ISC condition. In this case, the target rotation speed 1' according to the water temperature at ISO is set in S12.
Read JsET. Next, in S13, ISO
The basic injection amount Qis of fuel for the engine speed N at
Read the map υ stored in the cMN-1 microcomputer 11. However, the basic injection amount QiscMN is initially the same as the conventional IS
It is set to a value larger than the target value at O time. and,
When the value of C counted in S14 is 1 or more as described later, the value obtained by subtracting C from QiscMN is set as Qi.
Reset to scMN.

Next, compare the target rotation speed N8BT read at 812 with the rotation speed NMBSR actually measured by the crank angle sensor, etc. (815). If Ns E T > NME8R, increase the correction amount by feedback control (HNTis by a minute amount). 816), and sets the sum of Q18cMN and QiNTiS as QiSC (821).

Next, the target position of the control sleeve in the fuel injection pump is read from the map based on the Qi8C and the engine speed, and a signal thereof is output (S22).
. Also, when l'J8ET: NMESlt, QiN T
i 8 '1-Keep the current status and proceed to S21 Qis
Set c. N'S ET (When NME 8H, QiNTiS is decreased by a minute amount (818), and it is determined whether this value is O. If QiNTiS is O, proceed directly to S21 and select Qi 8C. Nanatsutoshi, QiN
When Ti is 820, C is incremented by 1 in S20, and then the process proceeds to S21 to set Qisc.

In such a configuration, since the engine speed when ISO is started is set lower than that of N8BT, S15
Depending on the determination of υ, the process initially proceeds to S16. Correction amount QiN
By increasing the amount of TiS, the rotational speed increases and once N
The result is 5ET2NMESR, but due to the overneat, N5ET<NME 8R and the correction amount QiNT
IS is reduced and the rotational speed decreases, and after repeating this increase and decrease in the rotational speed several times, it settles at NSET=NME8R.

In this case, under normal control, QiNTiS is kept at a positive value because the amount of undershoot in the engine speed is larger than the amount of overshoot, but due to changes over time and system variations, the set value may vary. If the same amount of injection is supplied, QiNTiS may become zero. At this time, although QiNTiS was 20, N8BT
Since <NMPi8R, it is no longer possible to set N8ET:l'JMB8R by correction by feedback control, but by counting C in S20, the value of Q i scMN is decreased in 814 in the next flow, The fuel injection amount set as Qisc=QiscMN decreases, resulting in N8ET2NMBSR.

In this way, changes over time and variations can be dealt with by correcting QiscMN according to the state of feedback control, so it is possible to initially set Qi8CMN large, and this makes it possible to reduce deceleration. By reducing the amount of undershoot caused by the engine, it is possible to prevent malfunctions and even stalling of the engine.

<Effects of the Invention> As explained above, according to the present invention, the reference fuel injection amount can be corrected according to the state of feedback control, so it is possible to initially set the minimum set value to a large value. As a result, the under/neat amount during deceleration is reduced, drivability is stabilized, and engine stalling can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view showing an example of an electronically controlled fuel injection pump, Fig. 2 is a flow chart showing the control process in a conventional idle speed control device, and Fig. 3 is a block diagram showing the configuration of the present invention. 1 and 4 are block diagrams showing one embodiment of the present invention, and FIG. 5 is a flowchart showing the control process of the same embodiment. 11... Microcomputer 12... D/A converter 13...
- Arithmetic circuit 14... Pulse converter 15... Drive circuit 16... Electronically controlled fuel injection pump 1T...
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Claims (1)

[Claims] In a diesel engine equipped with an electronically controlled fuel injection pump in which the position of the injection amount control member is electronically controlled according to the engine operating conditions, basic injection is used to set the basic injection amount according to the operating state in the idle operating region. an injection amount setting means, an injection amount correction type setting means for setting a correction amount of the injection amount by integral control by comparing a target value and an actual value of the engine rotation speed; A basic injection amount correction means that reduces the basic injection amount when the set correction amount becomes 0, an addition means that adds the basic injection amount and the correction amount to set a new injection amount, and the addition means 1. An idle speed control device for a diesel engine, comprising: means for setting a control position of an injection amount control member of a fuel injection pump corresponding to a set value of an injection amount added by the injection amount.