JPH0245022B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an engine control device and method suitable for feedback control of bypass air amount. [Prior Art] Generally, an engine includes a bypass passage that communicates between upstream and downstream of a throttle valve. Also, when the throttle valve is closed in the idle state, the
The actual rotational speed of the engine is maintained at the target rotational speed by controlling the amount of air taken in. In this way, in order to maintain the actual rotational speed at the target rotational speed, the amount of bypass air is feedback-controlled.
That is, first, the deviation between the actual rotation speed and the target rotation speed is determined, and then a correction amount is determined according to this deviation. Next, the amount of air taken into the engine is controlled to increase or decrease based on the correction amount so that the actual rotation speed approaches the target rotation speed. The above correction amount is set to zero if the deviation between the actual rotation speed and the target rotation speed is within a predetermined range, and is set to zero if the deviation between the actual rotation speed and the target rotation speed is outside the predetermined range. If it is a constant value. Alternatively, the above correction amount may be, for example,
As described in Japanese Patent No. 72319, it is set to zero when the deviation is zero, and is increased linearly from zero according to the deviation. [Problem to be Solved by the Invention] However, in the former technique, since the correction amount increases in stages,
The amount of air supplied via the bypass passage changes in stages, and the actual rotational speed does not become smooth.
Furthermore, the amount of correction becomes too large, and the amount of air supplied becomes too large (or too small), causing overshoot and hunting. Further, if the above correction amount is set to a small value, the amount of air supplied changes slowly, but it takes too long for the actual rotation speed to reach the target rotation speed. In other words, a disadvantage arises in that control responsiveness deteriorates. On the other hand, in the latter case, when the actual rotation speed is around the target rotation speed, if the target rotation speed is exceeded,
Correct the amount of air supplied so that the actual rotation speed changes immediately on the opposite side. Therefore, hunting occurs. Furthermore, when the deviation between the actual rotation speed and the target rotation speed is considerably large, the amount of correction becomes too large. Therefore, the amount of air supplied changes too much, greatly exceeding the target rotational speed, and overshoot occurs. An object of the present invention is to provide an engine control device and method that can appropriately maintain the actual rotation speed at the target rotation speed without hunting or overshoot when the engine is in an idling state. [Means for Solving the Problems] In order to achieve the above object, in the present invention, the actual rotation speed and the target rotation speed are determined, and when the deviation is smaller than the first constant, the correction amount is set to zero, and the deviation is is the first
When the deviation is larger than the second constant and smaller than the second constant, the correction amount is set to increase from zero as the deviation increases, and when the deviation is larger than the second constant, the correction amount is set to a constant value. It was configured as follows. [Function] According to the above configuration, when the deviation is large, the correction amount is set to a predetermined value, and when the deviation becomes smaller than this, the correction amount is made smaller as it approaches the target rotation speed, and furthermore, the correction amount is set to a predetermined value. The correction amount is set to almost zero near the rotational speed. Since it operates in this way, the closer the actual rotation speed is to the target rotation speed, the smaller the correction amount becomes, and the correction amount becomes zero when the actual rotation speed is slightly away from the target rotation speed. For this reason, excessive correction of the supplied air can be eliminated, and overshoot and hunting around the target rotation speed can be prevented. [Example] An example of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a vaporizer applied to the present invention. 1 is a carburetor main body, and air purified by an air cleaner (not shown) is introduced into an engine (not shown) through a main nozzle 6, a throttle valve 2, and an intake pipe 17. The air flow rate is controlled by opening and closing the throttle valve 2 in conjunction with the operation of an accelerator pedal (not shown). On the other hand, fuel is supplied from the fuel chamber 3 through the main jet 7 and air bleed 8 to the main nozzle 6 into the carburetor. Fuel is also supplied from a passage that passes through the main solenoid valve 5 and bypasses the main jet 7, and its flow rate is controlled by the solenoid valve 5. Fuel is further supplied from the slow hole 10 through the slow air bleed 9, and the amount of fuel supplied is determined by the amount of air introduced by controlling the opening and closing of the slow solenoid valve 4. The two solenoid valves 4 and 5 described above both have their fuel supply controlled by valve opening control (on-duty control), and also control the air-fuel ratio of the internal combustion engine. Further, these valves are controlled based on control signals from the control device 18. Next, the configuration related to the warm-up operation will be explained. Fuel solenoid valve 11 is connected to conduit 12
It is provided in the middle of the throttle valve 2 to control the amount of fuel supplied to the fuel supply port 13 which opens downstream of the throttle valve 2. This fuel is transferred from the fuel chamber 3 to a conduit 14 through a pipe (not shown), and the fuel solenoid valve 11 controls the fuel supplied during warm-up operation. 16 is a bypass passage, and the bypass passage 1
Reference numeral 6 communicates between the upstream and downstream sides of the throttle valve 2, and an air solenoid valve 15 is installed in the middle of the passage. Since the throttle valve 2 is closed during warm-up operation, the air solenoid valve 15 bypasses intake air and controls the amount of air according to the amount of fuel by the fuel solenoid valve 11 described above. Of course, this amount of air is controlled to a predetermined air-fuel ratio necessary for warm-up operation. Further, the two solenoid valves 11 and 15 are both controlled to open, and a control signal thereof is outputted from the control device 18. 19 is an idle switch, which emits a signal (ON or OFF signal) when the throttle valve 2 is operated from fully closed to open.
The signal is introduced into the control device 18. This signal is used to switch the control mode when the vehicle is started during warm-up operation, as will be described later. 20 is an engine cooling water temperature sensor;
Reference numeral 1 denotes an engine rotation speed sensor, and both of them are signals necessary for warming up the engine, and both are connected to the control device 18. FIG. 2 is a block diagram of the control device 18 shown in FIG. 1. In the figure, this configuration consists of a central processor 22 (hereinafter referred to as CPU), a read-only memory 23 (hereinafter referred to as ROM), a random access memory 24 (hereinafter referred to as RAM), and an input/output control device 25. ing. Above CPU2
2 issues commands for selectively importing a large amount of external information necessary for various operation controls into the CPU 22, and also includes a ROM 23 in which the contents of the system control style programming and various data are stored. Arithmetic processing is performed according to the stored contents from the readable and writable RAM 24. The input/output control circuit 25 includes an analog switch 27 (for example, a multiplexer) that switches a large amount of information input from the outside in response to a selection command from the CPU, and an analog switch 27 that converts the selected analog information into digital information. D converter 28, 29
This information is loaded into the CPU and pre-processed.
It consists of a control logic circuit 31 that performs calculations according to the contents stored in the ROM and issues control signals to an external control device. Next, the control targets controlled by the calculation results of the CPU include the air-fuel ratio control device 32, the warm-up operation control device 33, the ignition control device 34, the fuel pump 43, etc. In addition to the above, there is also an exhaust recirculation control device, etc. Illustration is omitted. The air-fuel ratio control device 32 operates according to the flow shown in FIG. 1 and the two main solenoid valves 4 and 5.
Similarly, the warm-up operation control device 33 includes two solenoid valves 11 for fuel and air,
It starts from 15. The opening ratio of each of these solenoid valves is controlled based on a control signal from a control device. For example, the warm-up operation control method according to the method of this embodiment makes the air-fuel mixture richer than the stoichiometric air-fuel ratio by controlling the opening ratio of the air and fuel solenoid, and the temperature of the cooling water is increased. The parameters are used to sequentially control the air-fuel mixture to the stoichiometric air-fuel ratio. Engine control according to this embodiment is controlled based on input information described below. That is, 20,
21 is a cooling water temperature sensor and an engine rotation speed sensor. In particular, the former sensor is a major parameter during warm-up operation, which will be described later.It is determined in advance the air-fuel ratio value corresponding to each cooling water temperature (a value richer than the theoretical air-fuel ratio), depending on the engine specifications. ) is stored in the ROM, and the signal from the rotation speed sensor 21 is introduced as a feedback signal and used as a control element during warm-up operation. The idle switch 19 is the switch explained in FIG. 1, and the details will be described later. In addition, as other input information, battery voltage 3
5. The oxygen concentration sensor 36 and the suction negative pressure sensor 37 are described, but their explanation will be omitted. Such a control device activates and controls tasks according to a predetermined priority order by a timer interrupt (hereinafter referred to as INTVIRQ) issued to the CPU. Furthermore, the above
INTVIRO is basically issued by comparing the register that sets the interrupt period with the count number of the counter to which CLOCK is input. This interrupt cycle is shortened (10ms in this example) for calculations such as taking in external information that changes depending on the state of the car and converting it into information necessary to control the engine, and is less than 20ms. , 40ms...etc.
A speed cycle is set according to the control content. Such INTVIRO activates each task according to the flowchart shown in FIG. 3, and prioritizes each task. That is, when the CPU receives an interrupt request, in step 50 it performs an interrupt factor analysis to determine whether or not the interrupt is a timer interrupt.
If so, issue a start request to the task of that timer period. Among these startup requests, in descending order of priority:
One of the level-divided task groups 52 to 55 is selected by the task scheduler 51, and the task is executed. When the execution of the selected task is completed (step 56), the task scheduler again selects the next level task with the next activation request. On the other hand, if the interrupt is an engine stall interrupt, turn off the fuel pump.
At the same time as turning off, the ignition system is reset (step 57), and all input/output control devices are NO-GO (stopped).
(Step 58). Note that Table 1 is a table showing the specific contents of each task divided into levels shown in FIG.

【table】

〔Effect of the invention〕

As explained above, in the present invention, the closer the actual rotational speed is to the target rotational speed, the smaller the correction amount becomes, and the correction amount becomes zero when the actual rotational speed becomes slightly distant from the target rotational speed. This has the effect of eliminating excessive correction of the amount of air supplied and preventing overshoot and hunting near the target rotation speed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a vaporizer used in the present invention,
Fig. 2 is a block diagram of a control device for realizing the control method of the present invention, Fig. 3 is a flowchart explaining timer interrupts and task activation, and Figs. 4 to 7 are the control method of the present invention. FIG. 8 is a flowchart of the present invention, and FIG. 9 is a diagram showing the relationship between the correction amount and the engine speed. 22...CPU, 23...ROM, 24...RAM, 2
5... Input/output control device, 28, 29... A/D converter.

Claims (1)

[Claims] 1. Detect the engine rotational speed, and based on the previous bypass air control amount and correction amount, control the current bypass air amount control amount so that the actual engine rotational speed approaches the target rotational speed. A method for controlling an engine that performs feedback control of bypass air amount by determining the engine speed, the engine control method comprising the following steps: determining a deviation between the actual rotation speed and the target rotation speed, the deviation being less than a first constant; If the deviation is greater than or equal to a first constant and less than a second constant which is greater than or equal to the first constant, the deviation is greatly reduced from the first constant. a step of setting the correction amount to increase from approximately zero according to the deviation; when the deviation is greater than or equal to the second constant, setting the correction value to a substantially constant value regardless of the magnitude of the deviation; Step to set. 2. A sensor that detects the state of the engine, an analog-digital converter that digitally converts the output of the sensor, a calculation means that performs calculation based on the output of the analog-digital converter, and a calculation unit that performs calculation based on the output of the calculation unit. The calculation means calculates the current bypass air amount based on the previous bypass air control amount and correction amount so that the actual engine rotation speed approaches the target rotation speed. further comprising: means for determining a deviation between the actual rotation speed and the target rotation speed; means for zeroing the correction amount when the deviation is less than a first constant; and less than a second constant that is greater than or equal to the first constant, the correction amount is set to increase from approximately zero as the deviation increases from the first constant. An engine control device comprising: means for setting the correction value to a predetermined fixed value when the deviation is greater than or equal to the second constant. 3. In claim 2, the engine is characterized by comprising a storage means for storing a target rotation speed according to the engine temperature, and the target rotation speed is determined by reading from the storage means. engine control device. 4. The engine control device according to claim 3, wherein the storage means stores a characteristic such that the target rotational speed becomes smaller as the engine temperature becomes higher. 5. In claim 4, a second storage means for storing an air-fuel ratio coefficient according to engine temperature;
An engine control device characterized by comprising means for calculating a fuel supply amount to match the air-fuel ratio coefficient read from the second storage means. 6. According to claim 5, a third storage means is provided for storing the amount of bypass air according to the engine temperature, and the control amount of the bypass air amount is stored from the third storage means under a predetermined condition. An engine control device configured to take the read value.