JPH0318010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the control of the intake air amount of an automobile engine, particularly to the control of the intake air amount during idling operation, and more specifically to a supercharging compressor and a throttle valve of a turbocharged engine. This invention relates to a device for electronically controlling an on/off type electromagnetic air control valve (idle speed control valve) installed in an idle air bypass passage that bypasses the air.

Electronically controlled fuel injection (EFI) can control the air-fuel ratio of the combustion air-fuel mixture according to various requirements, so it is now used as a fuel supply system for automobile engines from the viewpoint of purifying exhaust gas and improving fuel economy. It is often used in place of a vaporizer. In the EFI device called the L-dietronic method, the device's microcomputer calculates the fuel injection amount according to the intake air amount measured by an air flow meter installed in the intake system, and the fuel injection amount is calculated by the device's microcomputer. is injected into intake air by an injector to form a combustion mixture. The amount of intake air is controlled by a throttle valve linked to the vehicle's accelerator pedal. The idle speed of the engine is determined by the amount of intake air that flows through the gap between the throttle valve and the throttle body when the throttle valve is fully closed. As the engine operates for a long period of time, dust adheres to this gap, so the amount of intake air during idling decreases over time, and as a result, the idle speed of the engine decreases. Furthermore, the idle speed may change over time as the engine internal resistance decreases after the new engine has finished its break-in. Furthermore, in vehicles equipped with air conditioners, torque converters, power steering, etc., the amount of air at idle must be increased when these devices are activated. Therefore, conventional EFI
In an engine equipped with a device, an idle air bypass passage is provided to bypass the throttle valve, and an air control valve is provided in this bypass passage, and by controlling the operation of this air control valve, The intake air volume is adjusted to control the idle speed to the target value. In this specification, such an idle air bypass passage is referred to as an "idle speed control passage",
This air control valve will be referred to as the "idle speed control valve" or simply "ISCV." Conventionally used ISCVs include negative pressure operated type, step motor type type,
There are three types: an on/off type with a linear solenoid. The present invention relates to the latter type of linear solenoid type ISCV, and this type of ISCV is turned on/off by being supplied with a pulsed drive current from an electronic control unit (ECU) mounted on an automobile. The flow rate of idle air through the bypass is proportional to the "duty ratio," which is the percentage of time that pulsed current is actually supplied within a unit time. Therefore, if the duty ratio is calculated to an appropriate value by the microprocessor of the electronic control unit (ECU), the idle speed can be controlled to the target value. The determined duty ratio is transferred to the output register of the microprocessor,
As a pulse signal with a predetermined duty ratio
Output to ISCV.

In the conventional control device, the ISCV is subjected to feedback control according to engine operating conditions when the feedback condition is satisfied, and is subjected to learning control when the feedback condition is not satisfied. Therefore, during feedback control, the duty ratio of the pulse signal output to the ISCV is determined by setting the target idle speed according to external load conditions such as the air conditioner, and adjusting the duty ratio of the pulse signal output to the ISCV by setting the target idle speed according to the external load conditions such as the air conditioner. Set the integral term and proportional term of the duty ratio according to the difference between
It is obtained by adding the integral term and the proportional term. The sum of this integral term and proportional term during feedback is stored in memory as a learning value.
Used for learning control during open loop control.

In engines equipped with a turbocharger,
When the engine is operated at high speed and under high load for a certain period of time, the turbocharger becomes insufficiently lubricated as the lubricating oil temperature rises, impairing the durability of the turbocharger.
Therefore, as described in Japanese Patent Application No. 57-27897, the engine is operated for a certain period of time (for example, 20
minutes) After high-speed, high-load operation, the idle speed is increased for a predetermined period of time (for example, 10 minutes) to prevent insufficient lubrication. Therefore, during this fast idle, the target idle rotation speed is first set to a large value. By doing so, the difference between the actual rotation speed and the target rotation speed increases, so as feedback control continues, the integral term of the duty ratio gradually increases, until the rotation speed reaches the high target idle speed. You can get close. However, since the integral term during the feedback control is gradually increased in this way, the duty ratio at that time cannot be recorded as a learned value during the first idle. Therefore, if high-speed/high-load operating conditions continue and fast idle operation is always performed during idle to prevent insufficient lubrication, the learned value of the duty ratio may not be updated for a long time. happens. As a result, the old learned value was used during open loop control, resulting in inaccurate control of the intake air amount during idling.

The present invention was devised in view of the above-mentioned problems of the prior art, and it is possible to update the duty ratio even during first idle to prevent lubricant shortage after high-speed, high-load operation. It is therefore an object of the present invention to provide a control device for the intake air amount during idling that can expand the learning conditions for the duty ratio.

Therefore, in the present invention, at the time of the first idle, predictive control is performed to increase the idle rotation speed by the expected amount of the duty ratio.
The idea is to make it possible to record the sum of an integral term and a proportional term in memory as a learning value.

According to the present invention, the idling intake air amount control device is provided in a bypass that bypasses a turbocharger compressor and a throttle valve of an internal combustion engine with a turbocharger, and controls the idling intake air amount flowing through the bypass using a pulse signal. An ON/OFF actuated electromagnetic air control valve that adjusts according to the duty ratio, and a feedback system that determines the success or failure of the air control valve's feedback control conditions based on the starter, engine cooling water temperature, vehicle speed, throttle valve opening, etc. means for determining whether the condition is satisfied; target idle speed setting means for setting a target idle speed according to the external load of the engine when the feedback condition is satisfied; and turbocharger lubrication after the engine has been operated at high speed and high load for a certain period of time. Fast idle necessity determining means for determining whether or not it is necessary to operate the engine at fast idle for a predetermined period of time in order to prevent shortage; a comparison means for comparing, a target idle speed correction means for correcting the target idle speed to the set value when the target idle speed is less than or equal to the set value, and a target idle speed correction means for correcting the target idle speed to the set value, and a current engine speed NE of the engine and the corrected target idle speed. The integral term D _I , the proportional term D _P , and the prospective term of the duty ratio of the pulse signal are determined according to the difference from the number NF.
Means for setting D _T and said integral term D _I and proportional term D _P
means for adding and recording the sum as a learned value D _G of the duty ratio, and the integral term D _I and the proportional term D _P.
means for calculating a final duty ratio D by adding the expected term _DT ; and output means for outputting a pulse signal having the final duty ratio D to the air control valve.
It consists of: In this way, in the device of the present invention,
During the first idle, the idle rotation speed is increased using the prospective term D _T , and the integral term D _I is not gradually increased as in the conventional case.
During this time, it becomes possible to update the sum of the integral term D _I and the proportional term D _P as a learning value.

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

FIG. 1 is a schematic diagram of an electronically controlled fuel injection engine equipped with a control device of the present invention. The intake system of the engine includes an air flow meter housing 10 connected to an air cleaner (not shown), a first intake pipe 12, and a compressor housing 1 of the turbocharger 14.
6, second intake pipe 18, throttle body 20,
It consists of a surge tank 22, an intake manifold 24, and an intake port 26, and an injector 28 is installed in the intake manifold 24 for each cylinder. The injector 28 is connected to a pressurized fuel supply system (not shown), and is connected to an electronic control unit (ECU).
The valve is opened in response to a pulse signal outputted by 30, and a predetermined amount of fuel can be injected into intake air to form a combustion mixture.

The throttle body 20 is provided with a throttle valve 32 that is linked to the accelerator pedal of the vehicle, and a throttle position sensor 3 having a plurality of contact points is connected to the shaft of the throttle valve 32.
4 are linked together so that a signal corresponding to the throttle opening can be output to an electronic control unit (ECU) 30.

The air flow meter housing 10 is provided with a measuring plate 36 for measuring the intake air flow rate, and the latter is connected to a potentiometer type intake air flow rate sensor 38, which outputs a signal according to the intake air flow rate to the ECU 30. I'm starting to get it.

A turbine housing 42 of the turbocharger 14 is installed downstream of the exhaust manifold 40, and as the exhaust turbine 44 rotates, a compression turbine 46 rotates to pressurize intake air and supercharge the engine. The space within the center housing 14a that houses the bearings of the turbine shaft is filled with lubricating oil pumped from the engine's oil pump, and the bearings are immersed in the oil to be lubricated.

An idle speed control passage 48 is provided between the first intake pipe 12 and the surge tank 22, so that the air necessary for idling the engine bypasses the throttle valve 32 even when the throttle valve 32 is fully closed. It is designed to be supplied to the engine. This idle speed control passage 48 is provided with a linear solenoid type on/off air control valve, that is, an idle speed control valve (ISCV) 50.
As is well known, the ISCV 50 is closed and opened by a pulsed drive current output from the ECU 30.

The distributor 52 is provided with a known rotation angle sensor 54, which sends a signal corresponding to the angular position and rotation speed of the engine crankshaft to the ECU 3.
It is designed so that it can be output to 0. Furthermore, a rotating permanent magnet 58 with a protrusion is attached to the speed cable 56 of the vehicle so as to be able to rotate integrally therewith, and a reed switch 60 that cooperates with the magnet 58 is opened and closed by the rotation of this magnet 58. This magnet 58 and reed switch 60 constitute a vehicle speed sensor 62, which outputs a signal according to the vehicle speed to the ECU 30.

Figure 2 shows the electronic control unit (ECU) shown in Figure 1.
30, the ECU 30 is a program-controlled microcomputer. The electronic control unit (ECU) 30 is an ISCV described later.
A microprocessor (MPU) 70 that performs various arithmetic processing including calculation of the duty ratio of It consists of a random access memory (RAM) 74 consisting of a storage section, and a clock 76 that generates various clock signals. MPU7
0, ROM 72, and RAM 74 are connected to each other by a common bus 78, and the clock 76 is
It is connected to the MPU 70 and sends a clock signal directly to the MPU 70.

The analog signal from the air flow meter 38 is input to an A/D converter 84 via a buffer 80 and a multiplexer 82, converted to a digital signal, and read into the MPU 70 via an input/output port 86 and a common bus 78.

The signal from the throttle position sensor 34 is read into the MPU 70 via the input port 88.
Signals from vehicle speed sensor 62 and rotation angle sensor 54 are routed through shaping circuit 90 and input port 88.
Each is read into the MPU 70.

The MPU70 reads data from each of the sensors mentioned above.
Based on the data stored in RAM74, ROM
The duty ratio of the ISCV is calculated by performing arithmetic processing, which will be described later, according to a program stored in the CPU 72.
The calculated duty ratio is the same as in the conventional method.
The clock 76 is moved to a register in the MPU 70.
A pulse signal with a desired duty ratio is sent to the drive circuit 92 via the output port 90, where it is amplified and output to the ISCV in the form of a drive current.
50.

Figure 3 is a flowchart of a program to determine whether or not fast idle is necessary after the engine has been operated at high speed and high load for a certain period of time.The determination result is calculated by the duty ratio shown in Figure 4. It is used in routines. This routine is executed every 1/2 second, for example.

In the flowchart of Figure 3, step 1
At step 01, it is determined whether the intake air amount (Q/N) per engine revolution is 0.7 l/rev or more.
The data for the determination is obtained by reading signal data from the rotation angle sensor 54 and the air flow meter 38 from the RAM that is constantly stored.
Calculated.

When Q/N is 0.7l/rev or more, it indicates that the engine is under high load.

If Q/N≧0.7l/rev, the process moves to step 103, and if Q/N<0.7l/rev, the process moves to step 102.

In step 102, the engine rotation speed (NE)
Determine whether or not the speed is 2500rpm or more. NE is
If it is 2500 rpm or more, it means that the engine is rotating at high speed. If NE≧2500rpm, proceed to step 103, and if NE<2500rpm
If so, proceed to step 107.

In step 103, a soft counter _C1 for the duration of high load and high speed rotation of the engine is incremented.

Step 104 represents a step for determining whether the high load and high speed rotation time of the engine continues for 20 minutes or more. In step 104, it is determined whether the time has exceeded 20 minutes based on the value of the soft counter _C1 .

If C ₁ ≧20 minutes, proceed to step 105;
If C ₁ <20 minutes, the process moves to step 106.

In step 105, the first idle flag is set to "1".

In step 106, a value corresponding to 10 minutes is entered into the soft counter _C2 for the duration of low load and low speed rotation of the engine.

In step 107, the soft counter _C2 , which was filled with the value corresponding to 10 minutes in step 106, is decremented.

In step 108, it is determined whether the value of the soft counter _C2 is less than or equal to 0.

If C ₂ ≦0, the process moves to step 109 and C ₂
If >0, this routine ends. In step 109, counters C ₁ and C ₂ are cleared, and in step 110, the first idle flag is set down.

By repeating the above determination routine every 1/2 second, the first idle flag is set to "1" if the engine continues to operate at high speed and high load for 20 minutes or more. This means that the idle speed of the engine must be increased to prevent poor lubrication of the turbocharger.
Furthermore, the first idle flag is set down when 10 minutes or more have passed since the engine operating conditions ceased to be high speed and high load. This means that low speed and low load operation is 10
This means that the danger of poor lubrication has been eliminated because it lasted for more than a minute.

FIG. 4 is a flowchart of a routine for calculating the duty ratio of the ISCV. This duty ratio calculation routine is an interrupt routine started by a signal from the rotation angle sensor 54, and is executed every revolution of the crankshaft. It is something that In step 201, RAM7 was set in the previous routine.
The duty ratio learning value D _G recorded in the non-volatile RAM of 4 is read and transferred to the volatile RAM. Step 202 is a step for determining whether or not the engine is under conditions that allow feedback control of the ISCV 50. For example, the starter switch, engine coolant temperature, vehicle speed, and throttle opening are determined and the starter switch is activated. OFF, the cooling water temperature is above the set value, the vehicle speed is zero, and the throttle valve is fully closed, proceed to step 203 and below.
Performs feedback control of ISCV50. If the starter is operating, if the coolant temperature is below the set value, if the vehicle speed is high, or if the throttle valve is open, ISCV5 will be activated in steps 301 and below.
0 is open loop controlled.

If the feedback conditions are met,
In step 203, a target idle speed NF of the engine is selected depending on the operating state of accessory devices such as an air conditioner and a torque converter. In other words, if the compressor of the air conditioner is being driven or the torque converter is in the drive range, the engine load at idle will change, so the target idle speed will be different.
NF is selected.

In step 204, whether or not fast idle is necessary is determined by determining whether or not the first idle flag processed in the routine shown in FIG. 3 is "1". If the flag is "0", there is no need for fast idle, so the process proceeds to step 216 and subsequent steps, and normal feedback control is performed as described later. If the flag is "1", the process proceeds to step 206 and subsequent steps to perform feedback control using predictive control according to the present invention.

In step 205, the target idle speed NF set in step 203 is changed to a set value, e.g.
Determine whether it is smaller than 700 rpm. NF≧700
In this case, lubrication of the turbocharger can be ensured without increasing the idle speed any further, so the process proceeds to step 216.

If NF<700rpm, NF is corrected to 700rpm, which is considered the minimum necessary to prevent poor lubrication.

In step 207, the current engine speed NE
The difference |NE−NF| between the target rotation speed NF and the target rotation speed NF is calculated. In order to feedback-control the ISCV 50 by proportional-integral operation based on |NE-NF| obtained in this way, steps 208 to 214 perform a procedure for calculating the following equation.

D=D _I +D _P +D _T ...(1) Here, D is the final duty ratio of the pulse current applied to ISCV50, D _I is the integral term of the duty ratio, D _P is the proportional term, and D _T is the expected It is a term. The reason for using the integral term D _I is to take the duty ratio of the previous routine (the routine in Figure 4 is executed every revolution of the crankshaft as described above) and use it as a starting point to correct the duty ratio. The reason why the proportional term D _P is used is to quickly recover when the control target rotational speed is greatly overshot or undershot. Expected item
D _T is used according to the present invention, and NF is detected in step 205 due to the first idle.
This is to prevent the integral term D _I from gradually increasing when the speed is corrected to 700 rpm.

That is, in step 208, the correction amount ΔD _I of the integral term D _I is read from the ROM 72 based on |NE-NF| obtained in step 207. For this reason,
A map as shown in FIG. 5a is stored in advance in the ROM 72 in the form of a table.
When NE is 690 (rpm) and NF is 700 (rpm), therefore |NE−NF|=10 (rpm), ΔD _I is 0.02
(%).

In step 209, the integral term of the previous routine is
Add the correction amount ΔD _I to D _I to get the current D _I (D _I ← D _I
+ _ΔDI ).

Next, in step 210, the proportional term D _P is calculated in the ROM7 based on |NE−NF| obtained in step 207.
Read from 2. Therefore, the map shown in FIG. 5b is stored in the ROM 72 in the form of a table in advance. For example, this map is |NE−NF|
D _P can be set to 0.5 (%) when = 100 (rpm). As is clear from comparing the maps in Figures 5a and 5b, the D _P shown in Figure 5b
The map has a linear portion over the range |NE-NF|, which is larger than the map ΔD _I shown in FIG. 5a. Therefore, ΔD _I is suitable for slightly correcting D _I , and D _P is suitable for quickly adjusting the duty ratio when the deviation between the current rotation speed and the target rotation speed (i.e. |NE−NF|) is large. Suitable for correcting.

In step 211, for example, 4% is set as the expected term _DT .

In step 212, D _I +D _P is calculated, and the sum is set as the learned value D _G of the duty ratio. (D _G ←D _I +
_DP ). Then, in step 213, this learned value D _G
is stored in a predetermined area of the nonvolatile RAM of the RAM 74, and _DG of the previous routine is updated. The learning value D _G stored in the non-volatile RAM in this manner is used during open loop control, which will be described later.

Next, in step 214, the calculation of equation (1) is executed, and the determined final duty ratio D is calculated in step 215.
It is then moved to the register of the MPU 70.

If the first idle flag is not set to "1" in step 204, or if NE≧700 in step 205, step 2 is executed.
16 to 219, and the integral term of the duty ratio D
Find D _I and the proportional term D _P. These steps 21
Steps 6 to 219 correspond to steps 207 to 210 described above, and a learning value D _G is calculated in step 212 based on the obtained D _I and D _P.
The value of D _G is replaced with the old learned value in step 213.

Next, the calculation program for open loop control will be described. When it is determined in step 202 that the feedback condition is not satisfied, the process proceeds to step 301 as in the conventional case. Step 301
is used to determine whether the engine is under such a load that the turbocharger exerts a supercharging effect.For example, if the intake air amount Q/N per engine revolution is 0.55l/rev or more, Proceeding to step 302, the duty ratio is set to zero. This means that the idle air bypass 48 is closed to prevent charge air from flowing back through the bypass upstream of the turbocharger compressor.

If Q/N<0.55l/rev, it is assumed that the engine is operating under conditions where no backflow of supercharged air occurs, and learning control of the duty ratio is performed. That is,
Proceed to step 303, and set the learning value D _G recorded in step 213 as the final duty ratio D (D
←D _G ). In this way, learning control can be performed during open loop. The value of duty ratio D stored in the register of MPU 70 in the final step 215 of the duty ratio calculation routine described above is then used to form a pulse signal. That is, a clock signal is output from the clock 76 to the register every unit time, which is formed by dividing the pulse width of one cycle of the pulse signal output by the register into a large number of units, and the value of the duty ratio stored in the register is equal to the one unit. Counts down every hour. During this time, as long as the value in the register exists, the register outputs an ON pulse, and when the register becomes zero, the ON pulse ends and one cycle of the pulse signal ends. This pulse signal is input to the drive circuit 92 via the output port 90, and the drive circuit amplifies the pulse signal and converts it into a driving pulse current to the ISCV50.
to open and close ISCV. Therefore, since the driving pulse current has the duty ratio calculated in the routine of FIG. 4, the ISCV is also controlled ON/OFF with the desired duty ratio.

As is clear from the above, according to the control device of the present invention, when the target idle speed is corrected to a high value during first idle operation after high-speed, high-load operation (step 206 of the flowchart in FIG. corresponds to this.), the duty ratio is calculated by adding the expected term D _T (steps 211 to 214), so that the integral term D _I is not gradually overcorrected. Therefore, it is possible to update the sum of the integral term D _I and the proportional term D _P as the learned value D _G even during the first idle (step 212).
~213), which has the effect of expanding the learning area.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a turbocharged engine equipped with the intake air amount control device at idle according to the present invention, Figure 2 is a block diagram of the electronic control unit (ECU), and Figure 3 is whether or not fast idle is necessary. Flowchart of the routine for determining the 4th
The figure is a flowchart of the duty ratio calculation routine, and Figure 5 shows the correction part ΔD _I of the integral term D _I and the proportional term.
This shows an example of a _DP map. 14... Turbo charger, 14a... Center housing, 30... Electronic control unit (ECU), 32... Throttle valve, 48...
Idle speed control passage (idle bypass), 50...Idle speed control valve (air control valve).

Claims (1)

[Claims] 1 ON/OFF actuated electromagnetic air that is installed in a bypass that bypasses the turbocharger compressor and throttle valve of an internal combustion engine with a turbocharger, and adjusts the amount of intake air at idle that flows through the bypass according to the duty ratio of a pulse signal. A control valve, a feedback condition determination means for determining whether the feedback control condition of the air control valve is satisfied based on the starter, engine cooling water temperature, vehicle speed, throttle valve opening, etc. A target idle speed setting means for setting a target idle speed according to the engine speed and a need for fast idle operation of the engine for a predetermined period of time to prevent insufficient lubrication of the turbocharger after the engine has been operated at high speed and high load for a certain period of time. a first idle necessity determination means for determining whether or not the first idle operation is necessary; a comparison means for comparing the target idle rotation speed with a set value when the first idle operation is required; a target idle rotation speed correction means for correcting the target idle rotation speed to the set value in the following cases; means for setting an integral term D _I , a proportional term D _P , and a prospective term D _T ; a means for adding the integral term D _I and the proportional term D _P and recording the sum as a learned value D _G of the data ratio; means for calculating a final duty ratio D by adding the integral term D _I , the proportional term D _P , and the expected term D _T ; and an output means for outputting a pulse signal having the final duty ratio D to the air control valve. A control device for intake air amount during idling operation of an internal combustion engine, comprising: