JPS59203848A - Feedback controlling method for idling speed of internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent abrupt drop of the engine speed and its stall, by opening a control valve for controlling the flow rate of auxiliary air to its full opening at the time of starting the engine, and controlling the control valve according to the load when a prescribed time is passed from starting of the engine. CONSTITUTION:An intake passage 3 and an exhaust passage 4 are connected to an engine 1. An air cleaner 7 is attached to one end of an air passage 8 where it is opened to the atmosphere, and an auxiliary-air control valve 6 is provided at an intermediate porltion of the air passage 8. At the time of starting the engine, the control valve 6 is opened to its full opening for a prescribed while after completion of cranking. After passing of a prescribed while, the load of a generator 20 is detected and the control valve 6 is controlled to obtain a required flow rate of auxiliary air. With such an arrangement, it is enabled to prevent occurrence of engine stall or abrupt drop of the engine speed when the mode of controlling the flow rate of auxiliary air is changed from complete- combustion mode to feedback mode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an idle rotation speed foot bank control method for an internal combustion engine, and more particularly to an idle rotation speed feedback control method that ensures stable idle operation immediately after engine startup.

In an internal combustion engine, when the engine is subjected to electric loads such as headlights, air conditioners, mechanical loads, etc., the load on the engine increases, the idle speed decreases, and engine stall occurs. For this reason, conventionally, a target idle speed is set according to the engine load condition, the difference between this target idle speed and the actual engine speed is detected, and the size of the difference is adjusted so that this difference becomes zero. An idle speed feedback control method is known that controls the engine speed to be maintained at a target idle speed by supplying auxiliary air to the engine according to the engine speed.

In this method, when starting the engine, especially when the engine temperature is low, such as when the engine is cold, the lubricating resistance of the piston and other sliding parts is large, and it is difficult to ensure complete combustion of the air-fuel mixture, so it is difficult to ensure complete combustion of the air-fuel mixture. The engine speed tends to become unstable. Furthermore, since the battery consumed by the starter operation during cranking immediately after starting the engine is charged by the generator, the operation of the generator places a load on the engine, which tends to cause the engine speed at idle to become unstable. . In order to avoid instability of the engine speed during idling, for example, during engine startup or from when the engine speed exceeds the cranking speed,
In order to fully open the auxiliary air flow control valve (hereinafter referred to as "address mode 1~no"), the engine is operated at a higher rotation speed than the target idle rotation speed to ensure complete combustion and reduce the battery voltage. The present applicant has proposed a method of shifting to feedback control in which the engine speed is controlled to the target idle speed after recovery, etc.
No. 077250).

However, even if the auxiliary air amount control is performed in the complete explosion mode for the predetermined time t + u, the battery voltage Vs may be reduced to the predetermined voltage V B E due to deterioration of the battery, for example.
a may not be able to recover sufficiently (first
Sp) in Figure (c), in such a case, when the auxiliary air amount control is transferred from the above-mentioned complete explosion mode to the feedback mode (dotted line in Figure 1 (b)), the load generated by the generator's power generation is lower than the engine. As the engine speed continues to increase, the engine speed rapidly decreases (as shown by the broken line in FIG. 1(a)), causing discomfort to the driver. Furthermore, during the transition, the amount of auxiliary air is increased by feedback control only when the engine speed drops across the target idle speed, so the increase in the amount of auxiliary air is delayed, and depending on the size of the engine load at the time of the transition, the amount of auxiliary air is increased. There is a risk of engine stall.

The present invention has been made in view of the above-mentioned points, and is an internal combustion engine equipped with an electric device and a generator and a battery for supplying electric power to both. In an idle speed feedback control method in which a control valve that adjusts the amount of auxiliary air supplied to the engine via a passage is controlled according to the difference between the actual engine speed at idle and the target idle speed, when the engine is started, After the engine exits the cranking state, the control valve is fully opened for a predetermined period of time, and after the predetermined period of time has elapsed, the load condition of the generator on the engine is detected, and the detected load condition is equal to or higher than the predetermined load. The control valve is controlled so that the auxiliary air amount remains at a predetermined amount over a period of time, and when the auxiliary air amount control shifts from the complete explosion mode to the feedback mode, the engine speed suddenly decreases or engine stall occurs. It is an object of the present invention to provide an idle rotation speed feedback control method that avoids this situation.

Embodiments of the control method of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram schematically showing the entire idle speed feedback control device for an internal combustion engine to which the method of the present invention is applied. Reference numeral 1 indicates, for example, an 11-cylinder internal combustion engine, and the engine 1 includes: An intake passage 3 having an air cleaner 2 attached to its open end is connected to an exhaust passage 4. A throttle valve 5 is arranged in the middle of the intake passage 3, and an air passage 8 opens downstream of the throttle jt5 of the intake passage 3 and communicates with the atmosphere.
or is arranged. An air cleaner 7 is attached to the popular side σjJC1 end of the air passage 8, and an auxiliary air amount control valve (hereinafter simply referred to as "control valve") is installed in the middle of the air passage 8.
6 is placed. This control valve 6 is a normally-closed solenoid valve, and is composed of a solenoid 6a and a valve 6b that opens the air passage 8 when the solenoid 6a is activated.
a is electrically connected to an electronic control unit (hereinafter referred to as IEI: tJJ) 9.

The engine 1 of the intake passage 3 and the airway'! @8 opening 8
A fuel injection valve 10 is provided between the fuel injection valves 8 and 8, and this fuel injection valve 10 is connected to a fuel pump (not shown) and is electrically connected to the ECU 9.

The throttle valve 5 is equipped with a throttle valve opening sensor 17 or an intake passage 3.
An intake road absolute pressure sensor 12 communicating with the intake passage 3 via a pipe 11 is installed downstream of the opening 88 of the air passage 8, and an engine cooling water temperature sensor 13 and a rotation angle position sensor 14 are installed in the engine 1 body. Each sensor is electrically connected to the ECU 9. Electric devices such as headlights and heater fans] 5 and the input terminals of the starter 18 are connected to the battery 23 via a switch 16.19 and a connection point 23a, respectively, and the on-off signal of the switch 16.19 is transmitted to the ECU 9. is being supplied to. The other input side of the electric device 15 and the starter 18 are grounded. A connection point 23a of the battery 23 is connected to the alternator 20 and the regulator 21 provided in parallel with the alternator 20.
The regulator 21 controls the field current of the generator 20 according to the output voltage value of the battery 23.

The generator 20 is mechanically connected to the output shaft of the internal combustion engine 1 (not shown), and the engine 1 generates il! be moved. A voltage detector 22 is connected in parallel with the battery 23 between the connection point 23a of the battery 23 and the ground, and this voltage detector 22 is electrically connected to E C1 and 19, and sends the detected battery voltage value signal to E C19. supply

When starting the engine, switch 19 of starter 18
When closed (turned on), the starter 18 is transferred from the battery 23.
Power is supplied to the Since the operation of the starter requires a large amount of electric power, the electric power consumed by the battery 23 when the engine is started is large, and the output voltage value of the battery 23 decreases. Therefore, after the engine starts, the battery 23
In order to recover the consumed power, the generator 20 continues to operate and the output voltage value Va of the battery 23 is set to a predetermined value V'8EG.
Do not charge the battery until it recovers. The operation of the generator 20 applies a mechanical load to the engine 1, and the magnitude of the load on the engine is detected by the battery voltage value Vo detected by the voltage detector 22, as will be described later.

The engine operating state parameter signals from the throttle valve opening sensor 17, absolute pressure sensor 12, water temperature sensor 13, engine rotation angle position sensor 14, and starter switch 19, as well as the battery voltage value signal from the detector 22, are sent to the ECU.
9, the ECU 9 determines the engine operating state and engine load state based on the values of these signals and the electrical load state signal from the electrical device 15, and controls the fuel supply to the engine 1 according to these determined states. The amount, that is, the opening time of the fuel injection valve 10, and the amount of auxiliary air, that is, the opening time of the control valve 6, are respectively calculated, and the fuel injection valve 10 is adjusted according to each calculated value.
and a control signal for operating the control valve 6, respectively.

The solenoid 6a of the control valve 6 is energized for a valve opening time corresponding to the calculated value, opens the valve 6h, and opens the air passage 8, so that a predetermined amount of air corresponding to the valve opening time is supplied to the air passage 8 and the intake air. It is supplied to the engine 1 via the passage 3.

The fuel injection valve 10 injects fuel into the intake passage 3 by opening the valve for a valve opening time corresponding to the above-mentioned calculated value, and the injected fuel is mixed with the intake air to maintain a predetermined air-fuel ratio (for example, stoichiometric air-fuel ratio). The air-fuel mixture is supplied to the engine.

When the amount of auxiliary air is increased by lengthening the opening time of the control valve 6, the amount of air-fuel mixture supplied to the engine 1 increases, the engine output increases, and the engine speed increases. Conversely, if the opening time of the control valve 6 is shortened, the amount of air-fuel mixture supplied will decrease and the engine speed will drop. .

The engine speed can be controlled by controlling the amount of auxiliary air in this manner, that is, the opening time of the control valve 6.

FIG. 3 is a diagram showing the circuit configuration inside ECU 9 of FIG.
After the C signal is waveform-shaped by a waveform shaping circuit 901, it is supplied to a central processing unit (hereinafter referred to as rcPUJ) 903 and also to a Me counter 902.

Me counter 902 is the engine rotation angle position sensor 1
It counts the time interval from when the previous TDC signal was input to when the current TDC signal was input, and the old value Me
is proportional to the reciprocal of the engine speed Ne. The M picture counter 902 supplies this discussion value Me to the CP LJ 903 via the data bus 910.

The respective output signals from various sensors such as the throttle valve opening sensor 17, intake road absolute pressure sensor 12, engine cooling water temperature sensor 13, etc. and the output signal of the voltage detector 22 shown in FIG. After being fixed to the level,
The multiplexer 905 sequentially converts the A/D converter 90
6. The A/D converter 90G sequentially converts the output signals from the aforementioned sensors into digital signals and supplies the digital signals to the CPU 903 via the data bus 910.

The ON-A signal from the switch 16 of the electrical device 15 and the starter switch 19 in FIG. Sa'shi data bus 9]
0 Wosuke L ”'CCP 'U 903 Ni (JLi
8.

The CPU 903 is further connected via a data bus 910 to a read-only memory (rROMJ) 907 and a dumb access memory (referred to as "R1'\Niji1") 9.
The RAM 908 is connected to the drive circuits 909 and 911, and the RAM 908 temporarily stores the calculation results of the CPU 903, and the ROM 907 stores the control proger 13 etc. to be executed by the CPU 903. ing.・CP
According to the control program stored in ItOM907, U903 determines the engine operating state and engine load state at the time of startup according to the various engine parameters (No. The duty ratio Dour is calculated and a control signal corresponding to this performance value is supplied to the drive circuit!
A control signal based on the calculated τ:°C value is supplied to the drive circuit 909 via the data bus 910.

The drive circuit 909 operates the fuel injection valve 10 according to the control signal.
The drive circuit 911 supplies the injection valve 10 with a drive signal to open the valve, and the drive circuit 911 supplies the control valve 6 with a drive signal to turn the control valve 6 on and off based on the control signal.

FIG. 4(a) is a flowchart showing a control procedure for the control valve 6 executed within the ECU 9, and the above-mentioned control procedure will be explained below with reference to FIG.

This engine control program is shown in Figure 2, and the ECU
9, after the ignition switch (not shown in FIG. 2) is turned on and the ECU 9 is initialized (step 1 in FIG. 4(a)), the process is executed every time the TDC signal is generated. TD from the rotation angle position sensor 14 in FIG.
When the C signal is input to the ECU 9 (step 2), it is first determined whether the engine is in a cranking state (step 3). This determination is made, for example, when the engine rotational speed is a predetermined cranking rotational speed N e e R (for example, 4
00 r p +n ) or less and starter switch 19
This is done by determining whether or not it is on. If the determination result in step 3 is affirmative (YES), that is, engine rotation 3Q
If it is determined that cranking is in progress when the starter switch 19 is in the ON state (Sm in Figures 1(a) and (d)) lower than Nc or NecR, the process proceeds to step 4 in order to facilitate starting and quickly reach the idle speed. In order to fully open the control valve 6 and supply more air-fuel mixture to the engine 1, the valve opening duty ratio D o u T of the control valve 6 is set to 100% (Sm in FIG. 1(b)). If the determination result in step 3 is negative (No) for the first time after starting, that is, whether the engine speed NC becomes equal to or higher than the cranking speed N e CR for the first time (Sm in Fig. 1(a)) or if the starter switch 19 is When it is turned off, in step 5 it is determined whether or not the engine was in a cranking state in the previous loop using the same method as in step 3 above, and if the determination result in step 5 is YES, that is, in the previous loop. If the engine is in the cranking state and is not in the cranking state during the current loop, the process proceeds to step 6 and determines a period t+u for continuing to supply the auxiliary air amount in the complete explosion mode even after the end of cranking. Next, it is determined whether a predetermined time L+u has elapsed after the end of cranking (Step 7), and the valve opening duty ratio DouT of the control valve 6 is continuously set to 100% in the complete explosion mode until the predetermined time tau has elapsed. Set (Step 4).

As mentioned above, this predetermined time tau is for ensuring complete combustion of the engine, etc., and is calculated based on a predetermined calculation formula based on the water temperature signal from the engine cooling water temperature sensor 13 at the time of engine startup, and is used to cool the engine. It is set to become longer as the water temperature decreases.

When a predetermined time t+u has passed immediately after cranking, the process proceeds to step 8, and the previous loop (Fig. 1 (a) (b)
It is determined whether Sp-+) is a complete detonator or not, and if the determination result is affirmative (YES), the process proceeds to step 9, where the average value of the battery voltage V u x or a predetermined value V n
E It is determined whether it is larger than 6 or not. This average value V u x is calculated each time the TlDC signal is generated, for example, in the VBX calculation subroutine shown in FIG. 4 (( )). That is, the output voltage VB of the battery 23 is detected by the voltage detector 22 (step 21), and then, in step 22, the average value of the battery voltage Ilx is calculated based on the detected value VB. This calculation is performed, for example, using the following equation.

Here, X is a constant value of 1-255, and Vr8xn-
1 is the average value obtained during the previous loop, and ■1111 is the current detected value of the battery voltage.

The reason why the average value V II
This is because the charging voltage VB of the battery by the AC generator 20 pulsates and furthermore, due to noise etc., accurate dispersion voltage value VB cannot be detected. It is set based on Further, the predetermined value V o t-r; is a predetermined value that is used as a criterion for determining whether or not the operation of the generator 20 can apply a high load to the engine, as described above.

If the determination result in step 9 in FIG.
If E has not recovered to G (Sp
), the generator 20 that charges the battery 23 is in a full power generation state, and the generator 20 in this full power generation state is connected to the engine.
It is determined that a load of The complete explosion mode is repeatedly executed until V s x recovers to the predetermined value v8εG.

If the determination result in step 9 is affirmative (YES).

That is, if it is determined that the average value V B

In step 10, a value M H corresponding to the reciprocal of the target idle rotation speed N H is set. This value MH is set, for example, in accordance with the water temperature signal from the cooling water temperature sensor 13 and the magnitude of the engine load on the air conditioner, etc., so that the exhaust gas characteristics, fuel efficiency characteristics, etc. are optimized.

Next, the process proceeds to step 11, where it is determined whether a value Me proportional to the reciprocal of the engine rotation speed Nc is larger than a value M+4 corresponding to the reciprocal of the target idle rotation speed N++. If this determination result is negative (NO), that is, if the engine speed Ne is larger than the target idle speed N11 (first
Sg) in Figure (a), the process proceeds to step 12, where it is determined whether or not the previous loop was in the feedback mode, which will be described later.If the result of this determination is negative (No), the valve opening duty ratio D o u T of the control valve 6 is determined. is performed in the deceleration mode (step 13, Sg in FIG. 1(b)). The deceleration mode was established to prevent control delays when shifting control of auxiliary air from complete explosion mode to feedback mode 1-.
Valve opening Tee-Tee ratio D o u in this deceleration mode
The calculation of r can be obtained, for example, as the sum of the deceleration modes D x and the electrical load term DE. The deceleration modes Dx are
For example, when there is no electrical load such as the electrical device 15 and the engine is in an idling state where the water temperature is higher than a predetermined value (for example, 70°C), the engine speed Ne is set to the target idle speed N.
It is set to a constant value corresponding to the amount of auxiliary air required to maintain the air pressure at 0. Further, the electric load term DE is a predetermined value that is set according to an on-off signal of an electric device 15 such as a hendride. If the engine speed Ne decreases and falls below the target idle speed NH, the determination result in step 11 is affirmative (
YES), the valve opening duty ratio D o u ・+ is calculated in the refi 1 back mode (Step 1
4. S g + + ) in Fig. 1 (a) and (b), once the feedback mode is entered, Me≧MH, that is, Ne≦N
Even if +1 does not hold (S g +2 in Fig. 1(b)
) Since the determination result in step 12 is affirmative (YES), the calculation of the valve opening duty ratio DouT by the feedback mode continues. During this period, the duty ratio Dou] is, for example, the 5-field puncture mode term Dp+n
1j is obtained as the sum of the electric load term DE mentioned above, and the back motor term Dρl n is calculated by converting the actual engine speed Ne to the target idle speed N + (depending on which difference, this difference becomes zero. In other words, the engine rotation speed Ne is set to the target idle rotation speed N o.In this way, when the complete explosion mode is transferred to the feedback mode, the valve opening duty ratio of the control valve 6 D o II T decreases stepwise (from Sg-1 to Sg in FIG. 1(b)), but at that time, the battery 23 has been charged, so the load on the generator 2Q on the engine has already been released. Therefore, the engine rotation speed Ne is the target rotation speed NH
It is possible to smoothly transition to feedbank control without significantly lowering the control.

In addition, according to step 9 of the above embodiment, the average value V e
When x does not reach the predetermined value V If E a, the valve opening duty ratio I) Ou 'r (
= 100%), but the present invention is not limited to this, and the generator 2Q is still in a full power generation state after the engine is driven for a predetermined time t + u in the complete explosion mode, and the generator 20 Even if the engine continues to be subjected to a load of It suffices if the valve opener needy ratio supplies a predetermined amount larger than the maximum amount of air, that is, the engine speed Ne can be restored to the previous value without the engine speed Ne decreasing sharply after the engine is started, and the battery voltage can be restored. It is sufficient that the valve opening duty ratio is a predetermined valve opening duty ratio that corresponds to a sufficient amount of auxiliary air to maintain the engine speed at a speed that can be achieved.In addition, in the above embodiment, the load condition of the generator on the engine is detected by the output voltage of the battery. However, characteristic parameters representing the power generation state of the generator, such as excitation voltage and field current, may also be detected.

As described above, according to the idle speed fee 1-bank control method of the present invention, the control valve is kept fully open for a predetermined period of time after the engine exits the cranking state at the time of starting the engine. After a predetermined time has elapsed, a negative nη state with respect to the engine of the generator is detected, and the control valve is controlled so that the amount of auxiliary air is a predetermined amount while the detected load state is equal to or higher than the predetermined load. As a result, it is possible to avoid a large sudden decrease in the engine speed when transitioning to idle speed feedback control operation after the engine has started, and to prevent driver discomfort, engine failure, etc. due to this. .

[Brief explanation of the drawing]

Fig. 1 is a timing chart of the idle speed feedback control method of the present invention at the time of engine starting, in which (a) shows the engine revolutions at the time of starting, and (b) shows the auxiliary air amount control valve. Valve opening tute ratio D o 11 T
The figure (C1) shows the change in the battery voltage, and the figure (d) shows the state of the starter switch. I is an overall configuration diagram of an internal combustion engine control device to which the control method of the present invention is applied, FIG. 3 is an electric circuit diagram in the electric control unit (ECU) shown in FIG. 2, and FIG. 4(a) is the program brochure 1-1 1a (showing the control procedure of the auxiliary air control valve shown in FIG. 2).
b) is a flowchart of a subroutine for calculating the average value of battery voltage. ■... Internal combustion engine, 3... Intake passage, 5... Throttle valve, 6... Auxiliary air control valve, 8... Airway yIS,
9.Electronic control unit 1~. +5... Electrical device, 20... Generator, 22... Battery voltage detector, N
e: Actual engine speed, NH: Target idle speed, V e E a: Predetermined value, Va: Detected value,
V a x...Average value, Dour...Valve opening duty ratio of the control valve, t, +u...Predetermined time. Applicant IJ Giken Kogyo Co., Ltd. Agent Patent Attorney Toshihiko Watanabe Figure 4 (a) Figure 4 (b)

Claims (1)

[Claims] 1. Supply power to the engine via an air passage that opens downstream of the throttle valve in the intake passage of an internal combustion engine that is equipped with an electric device, a generator that supplies power to both, and a battery and that communicates with the atmosphere. In the idle speed feedback control method, which controls the control valve that adjusts the amount of auxiliary air that is generated depending on the difference between the actual engine speed at idle and the target idle speed, the engine is in a cranking state when the engine is started. After the release, the control valve is fully opened for a predetermined period of time, and after the predetermined period of time has elapsed, the load condition of the engine of the generator is detected, and while the detected load condition is equal to or equal to a predetermined load device. An idle rotation speed feedback control method comprising controlling the control valve so that the amount of auxiliary air becomes a predetermined amount. 2. The predetermined amount of the auxiliary air is larger than the average value of the amount of auxiliary air supplied to the engine by the engine rotation speed feedback control. Idle speed feedback control method. 3. The first aspect of the present invention is characterized in that the output voltage value of the battery is detected, and when the output voltage value is less than or equal to a predetermined voltage value, it is determined that the load state of the generator is greater than or equal to the predetermined load. The idle speed feedback control method described in Section 1. 4. The aisle rotation speed feedback control method according to claim 3, wherein the battery output voltage value used for the determination is performed using an average value of the detected output voltage values.