JPH0610440B2 - Rotational speed control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine controller, and more particularly to an engine speed controller.

[Prior art]

A conventional engine control device is configured to increase the intake air amount of the engine when the engine speed is reduced in order to maintain the engine speed in an idle state at a predetermined value (JP-A-55). -148937). However, increasing the intake air amount to the engine causes a temporary lean air-fuel ratio condition, resulting in a temporary decrease in engine output torque. Therefore, stable engine speed control cannot be obtained. The above phenomenon will be described in more detail.

Since the throttle valve opening state is kept constant during idling operation, when the engine speed decreases, the intake pipe pressure downstream of the throttle valve increases and the cylinder intake air amount of each cylinder increases. On the other hand, there is a response delay in increasing the amount of fuel by the fuel supply device. During the response delay time, the air-fuel ratio of the in-cylinder air-fuel mixture increases (becomes leaner), and conversely the torque decreases.
This enhances the reduction in engine speed.

This phenomenon will be described with reference to FIG. This figure shows the relationship between the engine speed N and the engine generated torque TP and friction torque T ^f . In the idle operation state, the friction torque ^Tf increases as the engine speed N increases.

Since the throttle valve opening is constant when the engine is idle, the intake air amount QA is considered to be substantially constant. The cylinder filling air amount L is expressed by the following equation.

As can be seen from this equation, the cylinder filling air amount L is the cylinder filling air amount QA / N (QA is the intake air amount) is QA
= Constant, that is, when the throttle valve opening is constant, it decreases as the engine speed N increases. When the air-fuel ratio is 1 or more,
The generated torque TP is proportional to the cylinder filling air amount QA / N.
Therefore, when the engine speed N decreases, the generated torque TP
, And conversely, as the rotational speed increases, it decreases.

The engine rotation speed converges to the engine rotation speed n0 at the point where the generated torque TP and the friction torque T ^f are balanced, and is stabilized.
This is the case when the engine speed changes gently. However, when it changes abruptly, there is a delay in the response of the fuel, and the generated torque decreases. The cause of the response delay may be a detection delay, a control circuit operation delay, a fuel supply timing delay, or the like, but the cause varies depending on the engine.

FIG. 2 shows a change in the generated torque TP when the engine rotation speed rapidly decreases from the idle rotation speed n0 to n1.

Due to the rapid decrease in the rotation speed, the cylinder charging air amount QA / N rapidly increases for the same reason as described above. On the other hand, the fuel supply increases with a delay, and the cylinder filling fuel amount Q ^f / N does not immediately increase. The air-fuel ratio sharply increases, and the generated torque TP decreases. Therefore, at the rotation speed n1, it becomes smaller than the friction torque T ^f . Therefore, the engine rotation speed further decreases toward the rotation speed n2, which is a friction torque that approximately balances the generated torque TP at the rotation speed n1.

The reason why the engine speed drops sharply during idling operation is considered to be a sudden increase in engine load such as the turning on of the car cooler or the combustion in the previous cycle being delayed for some reason.

[Object of the Invention]

An object of the present invention is to provide an engine rotation speed control device that can stably control the engine rotation speed during idling operation.

[Outline of Invention]

A feature of the present invention is that when the engine speed decreases during idle operation of the engine, at least the delay time until the fuel supply amount increases, the intake air amount QA decreases, and the increase of the air-fuel ratio is prevented. Is.

Example of Invention

FIG. 3 is a diagram showing an embodiment of the present invention, in which the engine 5
An intake pipe 506 is connected to 02 via a branch portion 504. The intake pipe 506 is provided with a bypass 512 having a throttle valve 508 and an air flow meter 510. Further, a bypass 518 having an electromagnetic valve 516 having a bypass throttle valve is provided so as to connect the upstream and downstream sides of the bypass 512. Control device 5 for controlling this engine
Reference numeral 20 denotes a signal from an air flow meter 510, a water temperature sensor 511, a throttle sensor 522 interlocked with a throttle valve and an idle switch 523, a crank angle sensor provided in a distributor 524, an exhaust gas sensor 526, and a starter switch 528. The optimum ignition timing, the fuel injection amount bypass air flow rate, and the exhaust gas recirculation amount are calculated, and the ignition circuit 530, the fuel injection valve 532, and the solenoid valve 516 are calculated.
And the EGR valve not shown is driven.

FIG. 4 is a detailed circuit diagram of the control device 520. Central processing unit (hereinafter referred to as CPU) in the figure
600 and read only memory (hereinafter referred to as ROM) 6
02 and random access memory (hereinafter referred to as RAM)
604, an input / output circuit 606, and a bus line 608.

A water temperature sensor 511, a throttle sensor 522, and an exhaust gas sensor 5 are used as sensors for detecting the operating state of the engine.
26 and these outputs are applied to the analog digital converter 612 via the multiplexer 610. Upon completion of the digital conversion operation, the analog digital converter (hereinafter referred to as ADC) 612 registers the value until the next conversion request (hereinafter, R).
It is written as EG. ) 614 and the CPU 600 can load that value via bus line 608.

An air flow meter 510 is further provided as a sensor for detecting the operating state of the engine, and its output is input to another analog digital converter 616 (hereinafter referred to as ADC 616), and its digital value is held in a register 618 and passed through a bus line 608. Is loaded into the CPU 600.
POS pulse and R sent from the crank angle sensor 620 arranged in the distributor 524 of FIG.
The EF pulse is applied to the angle signal processing circuit 622. The function of this circuit is an engine speed detecting function, which counts POS pulses input within a fixed time and holds them in an internal register. The CPU 600 uses this count value as the engine speed N
Is loaded via the bus line 608.

Outputs of the idle switch 523 (hereinafter referred to as idle SW) that closes the fully closed state of the throttle valve, the switch 528 (hereinafter referred to as starter SW) that is closed when the starter motor is energized, and the cooler switch 624 are 1 Bit unit information is the discrete input / output circuit 6
25 (hereinafter referred to as DIO).

The data representing the fuel supply time TI calculated by the CPU 600 generates the pulse INJ and is set to the pulse generation circuit 626. RE of crank angle sensor 620
A pulse INJ having a length indicated by the fuel supply time TI starting from the F output pulse is generated by the pulse generation circuit 626, and AND
Apply to the injector 532 via gate 628.

Digital data representing the ignition angle ADV ^θ and the ignition energy charging start angle DWL ^θ calculated by the CPU 600 are set to the pulse generation circuit 630 via the bus line 608. The pulse generation circuit 630 generates a pulse IGN that starts based on the value of DWL ^θ and ends based on the value of ADV ^θ .
It is applied to the ignition device 530 through the AND gate 632.

The data indicating the exhaust gas recirculation amount calculated by the CPU 600 is set in the pulse generation circuit 634, and the AND gate 6
The EGR valve (not shown) is repeatedly driven via 36.

A signal representing the opening of the solenoid valve 516 in the bypass passage 518 calculated by the CPU 600 is set in the pulse generation circuit 638 to drive the solenoid valve 516 via the AND gate 640.

The register 642 is a register (hereinafter referred to as MOD) that holds an instruction to instruct various states inside the input / output circuit 606.
AND gates 628, 632, 636, and 640, for example, by setting an instruction in this register.
Turn all on and off.
By thus setting the command in the MOD register 642, the fuel injection valve 532, the ignition circuit 530, the EG
It is possible to control the stop and start of the operation of the R valve and the solenoid valve 516.

FIG. 5 is a flow of the operation processing program of the bypass throttle valve when the engine is started by the CPU 600. When it is judged that the start switch of the step 700 is in the ON state, the solenoid valve 516 is closed in the step 702, and the step 7
At 04, the starter flag is set. When it is determined that the starter switch is OFF at step 700 and the starter flag is set at step 706, step 708 is performed.
At step 710, the engine speed N is taken in, the reference speed NS is compared, and when the taken speed is higher than the reference speed NS, it is judged that the engine has reached the complete explosion state. At step 712, the starter flag is reset. , The start process ends. When the engine rotation speed N is lower than the reference rotation speed NS, it is determined that the engine has stalled, the stall task is started in step 714, and the control circuit is returned to the startable state again.

When the start processing is completed, the CPU 600 executes the warm-up operation bypass control by the idle processing routine shown in FIG.

In step 800, it is determined whether or not it is in the idle state. If it is in the idle state, step 802 to step 818
Idle control up to. At step 802, the engine speed N and the water temperature TW are fetched, and at step 804, it is judged whether or not the engine is warmed up. This determination is made based on the magnitude relationship between the water temperature TW and the predetermined water temperature value TWO. When the water temperature is lower than the predetermined value TWO, the warm-up state is determined, and when the water temperature is higher than the predetermined value TWO, the normal idle rotation state is determined.

In the normal idle rotation state, the difference ΔN between the engine rotation speed N and the idle rotation speed NI is obtained in step 806, and the pulse duty correction value θ _B for driving the solenoid valve according to ΔN is read from map 1 in step 808.

In the warm-up operation state, the difference ΔN between the engine speed N and the warm-up speed ND is determined in step 810, and the step 8
At 12, the correction value θ _B corresponding to ΔN is read from the map 2.

The correction value θ _B is stored in the map 1 and the map 2 so as to take a positive value under the condition of ΔN> 0 and a negative value under the condition of ΔN <0.

In step 814, the pulse duty (DU) for driving the solenoid valve determined according to the engine speed, the water temperature, etc.
BI) is read from the map 3. Then, in the next step 815, it is determined whether or not the time t after the engine speed has decreased reaches the fuel supply delay time t ₀ .
When the engine speed decreases, the control proceeds in the direction of increasing the supplied fuel amount, but there is a time delay until the increased fuel amount is supplied to the engine combustion chamber due to the shape and capacity of the intake pipe. Therefore, if the intake air amount is increased immediately when the engine speed decreases (as described above, the cylinder filling air amount increases due to the decrease in the rotation speed even if the throttle valve opening is kept constant. ), The air-fuel mixture supplied to the combustion chamber becomes thin. Therefore, in this embodiment, the correction value θ _B is added to DUBI in step 816 in order to reduce the intake air amount by the time delay t ₀ determined by the shape and capacity of the intake pipe. If it is determined in step 815 that the fuel supply delay time t ₀ has elapsed, the process proceeds to step 817, and the value to which the correction value θ _B is not added is set as DUBI as it is, and the process proceeds to step 818.
In step 818, the DUBI set in step 816 or 817 is stored in the pulse generation circuit 638. The solenoid valve 516 is based on the DUBI of the pulse generation circuit 638,
The throttle valve opening is determined.

FIG. 7 shows a fuel injection amount control routine.

In step 900, it is determined whether or not it is in the idle state. If not in the idle state, normal acceleration / deceleration correction is performed in step 902 to determine the acceleration correction coefficient KACC deceleration correction coefficient KDEC. This determining method is described in Japanese Patent Application No. 56-70801 filed by the present applicant. In step 904, the idle increase correction coefficient KIDLEI and the idle decrease correction coefficient KIDLED are set to zero, and in step 938 the fuel injection amount is determined.

If it is determined in step 900 that the vehicle is in the idle state, step 906 enters the idle correction routine in step 936. At steps 906 and 908, the rotational speed N, the intake air amount QA and the water temperature TW are fetched. At step 910, it is determined whether or not the engine is warmed up by comparing the water temperature TW with the set value TWO. In the warm-up state, it is determined in step 912 whether the engine speed N is higher or lower than the set speed ND in the warm-up. When N> ND, in step 914 the difference Δ between the engine rotation speed N and the set rotation speed ND
Then, in step 915, the idle reduction correction coefficient KIDLED corresponding to ΔN is obtained from map 4 in step 915. When N ≦ ND, the difference ΔN is obtained in step 918, and the idle increase correction coefficient KIDL corresponding to ΔN is obtained.
Obtain EI from Map 5.

When it is determined in step 910 that the engine is in the normal idle state, in step 922, the engine speed N and the idle speed NI are compared. Step 9 when N> NI
At 24, the difference ΔN between the engine rotation speed N and the idle rotation speed NI is obtained, and at Step 926, the idle reduction correction coefficient KIDLED corresponding to ΔN is obtained from the map 6 by the map 6. When N ≦ NI, the difference ΔN is obtained in step 928, and the idle increase correction coefficient KIDLEI is obtained from map 7 in step 930.

Idle increase correction coefficient at step 920 or 930
If KIDLEI is determined, in step 932 the idle reduction correction number KIDLED is set to zero. If the idle reduction correction coefficient KIDLED is determined in step 915 or 926, the idle increase correction coefficient KIDL is determined in step 934.
Set EI to zero.

After the acceleration correction coefficient KACC and the deceleration correction coefficient are set to zero at step 936, the fuel injection amount Q ^f is determined at step 938 based on the second equation shown below.

KW is a correction coefficient based on the cooling water temperature, and KS is another correction coefficient.

8 to 9 are experimental data showing the effect of the embodiment of the present invention. In FIG. 8, idle rotation speed n = 6
Ignition timing and fuel flow rate Q ^f at 00 rpm and A / F = 14.5
It is a comparison of the relationship. Ignition timing 0 degree (top dead center)
When ignited by, the combustion is delayed and the combustion occurs when the piston starts to fall, so that the explosive force due to the combustion does not effectively act on the piston, the output of the engine becomes small, and a large amount of fuel is required. When the ignition timing is advanced, the pressure rise due to combustion also becomes faster, so the ignition timing when the piston reaches the top dead center has the highest output, and the fuel flow rate also decreases. On the other hand, when the fuel supplied to the engine is seen to change in each cycle, the air-fuel mixture supplied near the spark plug changes, so that the ignition timing and the extent of combustion change even at the same ignition timing. Therefore, the engine output changes every cycle and the idle rotation speed also changes. Therefore, the air-fuel ratio supplied to the engine also changes. The factors of such rotational fluctuations are increased by advancing the ignition timing by increasing the difference between the output when igniting and burning in an ideal state and the output when igniting and burning in a bad state. . In the conventional device, the fluctuation factor becomes larger than that near 10 degrees BTDC of the point burning timing, so the effect of advancing the ignition timing becomes smaller, and the effect of advancing the ignition timing near 17 degrees BTDC is offset. And the fuel flow rate increases. On the other hand, in the present invention, since the fluctuation of the air-fuel ratio due to the fluctuation of the rotation speed can be reduced, the effect of advancing the ignition timing is 20 degrees BHDC.
The ignition timing is 32 degree BTDC, which linearly increases to the near and reaches the minimum fuel flow rate. Therefore, the fuel efficiency is improved by about 20% at the time of idling as compared with the conventional device.

FIG. 9 shows the relationship between the idle rotation speed and the fuel flow rate. When comparing the idle fuel consumption, it is more realistic to compare the minimum fuel consumption. Therefore, the ignition timing MB
T (Minimum advance Best Torque) was used, and A / F was also set to the air-fuel ratio that provides the minimum fuel flow rate. In FIG. 9, according to the present invention, the idle rotation speed can be reduced and the fuel flow rate is 0.52
/ H, which is a decrease of about 17%.

According to the present embodiment, it is possible to prevent the cylinder air amount from increasing by decreasing the opening degree of the bypass valve even if the engine speed rapidly decreases, and to prevent the air-fuel ratio from increasing due to the delay in the fuel increase. As a result, the engine rotation becomes stable and the set level of engine rotation can be lowered. This can improve the fuel ratio.

Further, according to the present embodiment, since the bypass passage 518 is provided bypassing the air flow meter 510, the change in the bypass air flow rate does not affect the measurement of the air flow rate QA.

〔The invention's effect〕

As described above, according to the present invention, since the air flow rate is reduced when the engine rotation speed is reduced, the fluctuation of the air-fuel ratio at the time of idling can be prevented, and the engine rotation speed can be stably controlled in the idle operation state of the engine. be able to.

[Brief description of drawings]

1 and 2 show the engine speed and the generated torque T.
FIG. 3 is a diagram showing the relationship between P and the friction torque T ^f , and the relationship between the engine speed and the cylinder filling air amount L and the cylinder filling fuel amount Q ^f / N. FIG. 3 is a diagram showing an embodiment of the present invention,
FIG. 4 is a block diagram showing the control device of this embodiment, FIG. 5 is a diagram showing a processing flow at the time of engine start, FIG. 6 is a diagram showing control of the bypass throttle valve at idling, and FIG.
FIG. 8 is a diagram showing the control of the fuel injection amount, and FIGS. 8 to 9 are diagrams showing the effect of this embodiment. 502 ... Engine, 516 ... Bypass throttle valve, 518 ... Bypass passage, 520 ... Control device, 600 ... Central processing unit, 606 ... Input / output circuit.

Claims (1)

[Claims] 1. A first detection means for detecting a rotation speed of an engine, a second detection means for detecting a parameter other than the rotation speed of the engine, and a detection value of the first and second detection means. The intake air amount is provided in an electronic circuit that generates an intake air amount control signal and a fuel supply amount control signal, and in a bypass passage that connects the upstream side of an air flow sensor provided upstream of the throttle valve of the intake pipe and the downstream side of the throttle valve. In a rotational speed control device for an internal combustion engine, which comprises a flow rate control means for controlling a bypass air amount by a control signal and a fuel control means for controlling a fuel supply amount to the engine by the fuel supply control signal, during idle operation. The amount of air supplied to the internal combustion engine by controlling the flow rate control means when the internal combustion engine rotational speed decreases, at least during a period in which an increase response delay of the supplied fuel amount with respect to the rotational speed decrease is applied Rotation speed control device of the function of determining the intake air amount control signal so as to reduce the internal combustion engine, characterized in that it comprises said electronic circuit.