JPH0249951A - Intake air amount control device - Google Patents

Abstract

PURPOSE:To improve the transient characteristic in the time of selecting each control by correcting the basic control value in an open loop control in accordance with conditions of a transmission and a room cooling device, in the case of an engine selectively controlling an intake air amount to feedback and open loop controls. CONSTITUTION:A feedback control means 40, controlling the actual engine speed so as to agree with the target engine speed by controlling an engine intake air amount control means 70, and an open loop control means 50, controlling an intake air amount in accordance with the basic control value determined in accordance with an output of an engine temperature detecting means 51, are provided, and each control means 40, 50 is selectively used by a selecting means 60 being based on an engine operative condition. The basic control value is corrected by an open loop correcting means 80 in a correction value each different in accordance with operative conditions of a transmission and a room cooling device detected in each condition detecting means 90, and a control minimum value of the basic control value in accordance with each condition is set by a minimum value setting means 100.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air amount control device for controlling the intake air amount of an internal combustion engine mainly during idling, and particularly to open loop control when switching between feedback control and open loop control. It is.

Recently, in order to improve the exhaust purification performance and fuel efficiency of automobiles, it has become necessary to precisely control the rotation speed during idling. For this reason, a device has been developed that determines a target rotational speed according to engine operating conditions such as engine temperature, and performs feedback control of the intake air amount so that the actual rotational speed matches the target rotational speed.

In the above devices, it is necessary to stop feedback control and switch to open loop control when the device is not idling, but in conventional devices,
During open-loop control, the control value immediately before feedback control was stopped was fixed at a - constant value, and when feedback was started again, control was started from the fixed value, so the change from open-loop control to feedback control was There was a risk that the engine rotation would become abnormally high or low during switching or vice versa.

For example, during a cold start (when the engine is started when it is cold)
In this case, the target rotation speed for feedback control is set to a high value, and therefore the control value (control duty) is a large value corresponding to a large amount of intake air. If you warm up the engine while it is idling in this state, the target rotation speed will decrease as the engine temperature rises.
The control value also becomes smaller accordingly. However, after a cold start,
If you start driving immediately, and switch to open loop control at the same time as you start driving, the control value during feedback control will be fixed at a large value (fixed to the control value immediately before switching to feedback control). It ends up. If the engine returns to idling after sufficient warm-up while driving, the control value will be a large value even though warm-up has been completed, so the idling speed will temporarily decrease. It becomes a very high value. Of course, when the engine starts idling, it switches to feedback control, and the target rotational speed also decreases to a value corresponding to the engine temperature, so the above-mentioned high idling is a temporary phenomenon. However, when the idling speed becomes abnormal as described above, it gives a sense of anxiety to the occupants and also has a negative effect on the exhaust gas purification performance.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide an intake air amount control device that improves the transient characteristics of open loop control and feedback control, and provides stable operation without excessive control. shall be.

In order to achieve the above object, 1. In the present invention, a control duty that determines the basic intake air amount for open loop control is set with respect to the engine temperature immediately after the engine starts, and this set value is set depending on whether the transmission is manual or automatic. In the case of an automatic transmission, the correction value is corrected with different correction values depending on the shift position between the drive range and the neutral range, and the on/off status of the air conditioner, and used as the basic control value.

The control minimum control duty is configured to be set according to each of the above-mentioned cases.

The present invention will be described in detail below based on the drawings.

FIG. 1 is an embodiment diagram showing the overall configuration of the present invention,
1 shows a case where the present invention is applied to an internal combustion engine equipped with an electronically controlled fuel injection device.

In FIG. 1, reference numeral 1 denotes the main body of the internal combustion engine. Intake air is supplied from an air cleaner 2 to each cylinder through each branch of an intake manifold 5 via an air flow meter 3 and a throttle chamber 4, and fuel is injected by a fuel injector 6. Ru. Here, the flow of intake air is controlled by the throttle valve 7 in the throttle chamber 4 which is linked to the accelerator pedal, and the Scot 1 Hell valve 7 is almost closed during idling. The flow of air during idling passes through the bypass port 8 and is adjusted by the idle adjustment screw 9 installed therein, and also passes through the bypass passage 10 that communicates the upstream and downstream sides of the throttle valve 7 with the Idle control valve 1
1 ensures the appropriate amount of air.

The idle control valve 11 includes a valve body 12 interposed in the bypass passage 10, a diaphragm 13 to which the valve body 12 is connected, and a negative pressure operating chamber 15 equipped with a spring 14 that biases the diaphragm 13. The amount of lift of the valve body 12 by the diaphragm 13 is changed in response to an increase or decrease in the negative pressure introduced into the negative pressure working chamber 15, and its opening degree is decreased or increased. This negative pressure working chamber 15 is connected to the throttle valve 7 via a constant pressure valve (pressure regulator valve) 17 by a negative pressure introduction passage 16.
It communicates with the intake passage downstream, and also communicates with the intake passage upstream of the throttle valve 7 via the pulse electromagnetic valve 19 via the atmosphere introduction passage 18 . Thus, by opening and closing the pulse solenoid valve 19, the degree of opening of the idle control valve 11 is controlled by changing the dilution ratio of the negative pressure introduced into the negative pressure working chamber 15 with the atmosphere.

The pulse solenoid valve 19 is, for example, a microcomputer 20.
controlled by

The microcomputer 20 is mainly a microprocessor (
It consists of a central processing unit) 21, a memory (storage device) 22, and an interface (input/output signal processing circuit) 23. The rotation speed of the internal combustion engine 1 is detected by an electromagnetic pickup type rotation speed sensor 24 and inputted to the interface 23 of the microcomputer 20 as a digital signal (actually, the rotation speed of the internal combustion engine 1 is inputted as a digital signal obtained from the rotation of the crankshaft by the crank angle sensor). pulse and crank reference angle pulse), the engine temperature of the internal combustion engine 1, for example, the cooling water temperature, is detected as an analog signal by a thermistor-type water temperature sensor 25 and input as a digital signal via the A/D converter 26. be done. Also, interface 2
3 includes a throttle valve switch 27 that detects that the throttle valve 7 is in the fully open position, a neutral switch 28 that detects that the transmission is in the neutral position, and a vehicle speed that is less than a predetermined value, for example, 8+++/h. ON and OFF signals are manually input from the vehicle speed switch 29, which detects this. In the drawing, the throttle valve switch 27 is shown to be an analog type sensor using a variable resistor, and its signal is inputted via the A/D converter 30, but it is an on/off type sensor that detects the fully closed position. It can also be a switch.

The memory 22 stores in advance an optimal target rotational speed N5ET (“1 standard rotational speed during idling”) corresponding to engine operating conditions such as engine temperature.

The microprocessor 21 determines the current operating state based on the signal from the water temperature sensor 25, etc., reads out the corresponding target rotation speed NSET, and also outputs the rotation speed sensor 24.
Calculate the actual rotational speed N RPM based on the signal given from
NRPM N5Il! T) is detected.

Next, the microprocessor 21 sets control constants, that is, a proportional constant and an integral constant according to the actual rotational speed N RPM and the deviation ΔN, calculates a control value from these control constants and the deviation ΔN, and calculates the control value. By changing the on/off ratio, that is, the duty, of the pulse signal that drives the pulse solenoid valve 19 in accordance with this, the intake air amount is feedback-controlled so that the actual rotation speed N RPM matches the target rotation speed N5ET.

Furthermore, the microprocessor 21 determines whether or not to perform the feedback control described above depending on the states of the throttle valve switch 27, neutral switch 28, vehicle speed switch 29, etc., and whether or not there is a fuel cutoff, and determines that the feedback control is to be performed. Only when this occurs, feedback control is performed by changing the duty of the pulse signal; otherwise, open loop control is performed.

In open-loop control, the control value, that is, the duty of the pulse signal, is changed in accordance with the cooling water temperature according to the characteristics shown in FIG. 4, for example.

Specifically, control values corresponding to the temperature are stored in advance as a data table in the ROM (read-only memory) in the memory 22 shown in FIG. Read the corresponding control value.

In the present invention, the above-mentioned reference control duty is corrected depending on the type of transmission, on/off of the cooling device A/C, and whether it is drive range D or neutral range N when equipped with an automatic transmission AT, and is adjusted according to each case. Define the open loop control duty as a different value.

Furthermore, at the same time, the minimum value of the control duty is determined for each of the above cases.

Although the correction amount changes in a complicated manner under each operating condition, complication is avoided by representing several types of values that are least inconvenient.

The above-mentioned correction values of the basic output and the minimum value of the open loop control output are shown in the following table.

As shown in the table above, when the cooling system is off and the transmission is in neutral, the values are the same for models with manual transmission and automatic transmission. The others are set to different values in each case to satisfy the idling or immediate power demand. Further, by determining the minimum output value, the minimum value of the control is limited to prevent malfunction or instability of rotation.

A flowchart of the above-mentioned control program is shown in FIG. For example, the control program of the present invention may run once per revolution of the engine.
The calculation part that follows the six basic rotation speed settings that are calculated once every degree or fixed time is designated as Pl, and first, the basic output table determined for the water temperature at P2 is looked up and stored in the A register.

Next, in P3, it is confirmed whether the starting switch is on or off, and if it is on during starting, a flag is set in P8 so that feedback control is performed immediately after starting, and the contents of the A register are transferred to the output register. After this, a separately prepared feedback control program is entered in P9.

If the start switch is off at P3, check whether the engine has a manual transmission MT or automatic transmission AT at the next P4.

In the case of manual transmission MT, check whether the cooling system is on or off in P5. If it is on, P6 sets the basic output A to 10 (
The A register is corrected by adding the minimum output (corresponding to a duty of 5%), and the minimum output 60 (corresponding to a duty of 30%) is stored in the B register. When the cooling system is off, in Pl,
The basic output value is not modified, the minimum output is 50 (duty 2
5%) is stored in the B register.

If the automatic transmission is AT in P4, check whether it is in neutral N or drive D in PLO. p when neutral N
Check whether the air conditioner is on or off with H. If it is off, the basic output A will not be changed and the minimum output will be 50 (25%) stored in the B register. This value is the same as Pl, that is, when cooling is turned off in a manual transmission. If cooling is on at pH, add 18 (9%) to the basic output A using Pl2 to correct the A register, and store the minimum output of 65 (32,5%) in the B register.

When PLO is in drive D position, use Pl4 to check whether the cooling system is on or off. If it is off, use Pl7 to set the basic output to 3.
(1,5%) is added to correct the contents of the A register, and the minimum output is set to 50 (25%) and is stored in the B register. If the air conditioner is on, check the vehicle speed with Pl5 and set it at 4km.
/h or more, the same value is set at Pl7. When the vehicle speed is low, use Pl6 to add 21 (10.5%) to the basic output and modify the contents of the A register, resulting in a minimum output of 68 (34%).
is stored in the B register. When the vehicle speed is high, the engine speed is generally high and there is no need to increase the amount of intake air, which is required in terms of cooling capacity and avoidance of engine stalling, so the system judges the vehicle speed and stops increasing the amount of intake air. Even if this operation is not required, the user will only feel discomfort due to some load fluctuations as the cooling device is turned on and off, and no major problems such as engine stalling will occur.

The results of P6, Pl, Pl2, Pl3, Pl6, and Pl7 described above are as follows: In Plg, the contents of the A register indicating the basic output value are transferred to the output register, and the contents of the B register indicating the lowest output value are transferred to the control duty. Move it to the lower limit value register and use it as a control value. At Pl9, the program moves to the next control program.

FIG. 3 shows a functional block diagram of the present invention. In the third article, 40 is a feedback control means, 50 is an open loop control means, 60 is a means for switching between feedback control and open loop control according to various operating conditions of the engine, and 70 is a means for controlling the amount of intake air. be.

In the device for controlling the intake air amount by switching between feedback control and non-feedback open loop control using the above means, in the present invention, first, the open loop control means 50 receives a signal from the engine temperature detection means 51. A basic control value corresponding to the engine temperature stored in a data table (not shown) is output. and,
This basic control value is corrected by the open loop correction means 80 as follows. That is, the open loop correction means 80 detects whether the vehicle's transmission is manual or automatic, detected by the state detection means 90, and in the case of an automatic transmission, whether the shift position is in the drive range. The basic control value is adjusted with different correction values depending on a plurality of conditions, including at least one of whether the door is in the neutral range and whether the cold door device is on or off. Fix it.

Furthermore, the minimum value setting means 100 sets the control minimum value of the basic control value according to each state detected by the detection means 90 for each state.

As described above, in the present invention, by determining a required value as the initial open-loop basic output value of the control program according to the basic state of the vehicle, subsequent control becomes extremely easy and reliable.

Furthermore, by setting the minimum output value according to the various basic operating conditions mentioned above, if the throttle is suddenly tightened from a high rotation speed, the control duty will be lowered too much through feedback control, causing the engine to stall or malfunction. Never.

Note that the basic output setting of the present invention is independent of the gear position in the case of a manual transmission MT, and is set to a different value in the case of an automatic transmission AT because the resistance acting on the vehicle is different between neutral and drive.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment showing the overall configuration of the present invention, Fig. 2 is a flowchart of a basic output control program, Fig. 3 is a functional block diagram of the present invention, and Fig. 4 is a diagram during open loop control. FIG. 3 is a characteristic diagram of water temperature versus pulse signal duty. <Explanation of symbols> 1. Internal combustion engine 2. Air cleaner 3. Air flow meter 4. Throttle chamber 5. Intake manifold 6. Fuel injector 7. Throttle valve 8. Bypass port 9. Idle adjustment screw 10. Bypass passage 11. Idle control valve 12. Valve body 13. Diaphragm 14. Spring 15. Negative pressure working chamber 16. Negative pressure introduction passage 17. Pressure valve 18...Atmospheric introduction passage 19...Pulse solenoid valve 20...Microcomputer 21...Microprocessor 22...Memory 23/Interface 24...Rotation speed sensor 25...Water temperature sensor 26...A /D converter 27... Throttle valve switch 28... Neutral switch 29... Vehicle speed switch 30... A/D converter

Claims (1)

[Claims] By controlling the intake air amount of the internal combustion engine, control is performed by switching between feedback control, which controls the actual rotation speed to match the target rotation speed, and open loop control, which does not provide feedback, depending on various engine operating conditions. In the intake air amount control device, the open-loop basic control value of the signal that controls the actuator that adjusts the intake air amount is read out from a data table stored in correspondence with the engine temperature, and is determined separately from the set value of the target rotation speed. and a plurality of states including at least one state of the type of the vehicle's transmission, whether the gear position is drive or neutral in the case of an automatic transmission, and whether the air conditioner is on or off. An intake air amount control device comprising: means for correcting the basic control value with different correction values; and means for setting a minimum control value of the basic control value according to each of the conditions.