JPH0361017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine idle rotation control device.

In general, an automobile's idle speed control device uses feedback control to suppress the engine speed during idling to a low speed of around 600 to 700 rpm, thereby stabilizing the combustion performance of the engine and improving fuel efficiency. The conventional control method for this type of device is to install an actuator in the throttle valve that automatically opens and closes it, and first sets the target idle speed according to engine operating conditions such as water temperature and presence or absence of cooler load. However, by determining the difference between this and the actual idle rotation speed and controlling the drive of the actuator according to this difference, the actual idle rotation speed is controlled so as to become the target idle rotation speed. Ta.

When performing feedback control as described above, it is desirable to increase the responsiveness of the control in order to prevent engine stalling due to the engine load of the cooler operating during idling, but it is desirable to increase the control response. Increasing responsiveness
This time, problems occur such as overshooting, hunting, and unstable engine speed fluctuations.

In view of the above-mentioned circumstances, as shown in Japanese Patent Application Laid-open No. 54-113725, for example, when an engine load such as a cooler is activated during idling, the amount of intake air supplied to the engine has been reduced to a certain level. An idle rotation control device that employs so-called anticipatory control is also being considered, which increases the amount by a fixed amount, thereby making it possible to quickly follow the engine load operation while keeping the feedback control gain set small.

When performing prospective control as described above, the amount of intake air is increased to match the size of each engine load such as the cooler, various electrical loads, power steering, etc., so that there is no excess or deficiency. It is inevitable that even engines of the same model will have performance differences due to individual manufacturing differences, aging, etc. Therefore, it is necessary to use such prospective control to precisely set the idle speed to a predetermined value. This was difficult, and fluctuations in idle speed were likely to occur when the engine was operating under load.

Therefore, as shown in Japanese Patent Application Laid-open No. 55-107034, for example, it is detected whether or not the amount of increase in the amount of intake air due to the above-mentioned prospective control is appropriate, and if it is inappropriate, that is, excessive or insufficient, the above-mentioned An idle rotation control method has been proposed in which stored correction information is updated to a more appropriate value in order to determine the amount of increase.

However, in this conventional method, when the integral value of the difference between the target idle speed and the actual idle speed exceeds a predetermined value, the correction information (i.e., intake air amount increase amount) is updated. Therefore, there is a risk that the correction of this intake air amount increase amount may be performed without properly responding to the excessive or insufficient amount of increase. In other words, the difference between the target idle speed and the actual idle speed can also be caused by disturbances other than the increase in intake air volume due to predictive control, such as temporary disturbances in the air-fuel ratio immediately after the start of engine load operation and fluctuations in intake air temperature. Therefore, the above-mentioned integral value does not always accurately reflect an excess or deficiency in the intake air amount increase. Therefore, based on the above integral value, for example, even though the amount of increase in the amount of intake air is too large, it is naturally possible that control is performed to further increase this amount of increase.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an engine idle rotation control device that can always accurately maintain the idle rotation speed at a predetermined value in response to variations and changes in engine performance. This is the purpose.

The engine idle rotation control device of the present invention includes:
In a feedback type idle speed control device that employs prospective control as described above, when the engine load is applied, the amount of intake air is increased by a predetermined amount based on a correction value in the storage means, and the correction value is applied when the engine load is not applied. Based on the fluctuation in the engine speed when the operating state shifts from the operating state to the engine load operating state, the final correction value is determined by further correcting the actual idle speed during engine load operation so that the fluctuation is smaller with respect to the target value. and rewrites the correction value in the storage means to the final correction value, and increases the intake air amount based on the final correction value at the next engine load operation. .

If the above-mentioned control device is used, the amount of increase in intake air amount is checked every time the engine load is activated during engine idling and prospective control is performed, and the increase in intake air amount is adjusted to a more favorable value. The idle speed at the time is always stably set to a predetermined value.

Since the above-mentioned increase amount is checked based on the engine speed fluctuation when the engine load changes from the non-operating state to the operating state, it is possible to check whether the increase amount is excessive or insufficient. It will now be checked correctly. Therefore, the increase in the amount of intake air is always corrected in the correct direction, and the idle speed is controlled to a predetermined value extremely accurately.

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

FIG. 1 shows the configuration of an engine idle rotation control device according to an embodiment of the present invention, in which 1 is an engine, 2 is a piston, 3 is an intake passage, and 4 is a piston.
is an exhaust passage, 3a is an intake valve, 4a is an exhaust valve, 5 is an air cleaner that supplies clean air to the intake passage 3, 6 is a carburetor provided in the intake passage 3 below the air cleaner 5, and 6a is this vaporizer. vessel 6
a fuel nozzle provided in the intake passage 3 and opening into the intake passage 3;
7 is provided slightly below the carburetor 6, and is connected to the engine 1.
8 is a stopper that engages with this throttle valve 7 and drives it to open and close; 9 is a diaphragm device that sucks this stopper; 10 is a negative pressure of this diaphragm device 9; 11 is a negative pressure side passage that communicates the negative pressure chamber 9a with the negative pressure downstream of the throttle valve 7 of the intake passage 3; The atmospheric side solenoid valve 13 opens and closes the atmospheric side passage 10, and 13 is a negative pressure side solenoid valve that opens and closes the negative pressure side passage 11. 8 to 13 above constitute an actuator 14 that drives the throttle valve 7 to open and close. .

Further, 15 is a water temperature sensor that detects the temperature of the cooling water 16 of the engine 1, 17 is an A/D converter that converts the output of the water temperature sensor 15 into A/D, and a is a water temperature signal that is the output of the A/D converter 17. , 18 is a distributor with a built-in engine rotation speed detector (electromagnetic pickup device) in this device, b
19 is a throttle opening sensor that detects the opening of the throttle valve 7; c
20 is the cooler switch, and d is the output of the cooler load detection signal.

Further, reference numeral 22 receives the various detection signals a, b, c, and d mentioned above, and compares the target idle rotation speed set according to the operating state of the engine with the actual idle rotation speed detected by the rotation speed detector. The target throttle opening is set according to the difference, the target throttle opening is compared with the actual throttle opening, and the actuator 14 is driven and controlled according to the difference so that the actual idle rotation speed becomes the target idle rotation speed. This is a microcomputer as an actuator control device, which has an interface 22a, a memory 22b, and a CPU (central processing unit) 22c.

Figures 2A and 2B show the above microcomputer 2.
2 shows a flowchart of signal processing in step 2. Hereinafter, signal processing by the microcomputer 22 will be explained with reference to FIGS. 2A and 2B.

First, in step S1, the CPU 22c calculates the first correction term T ₂ (described in detail later) for the target throttle opening.
Initial setting T ₂ = 0 and the second correction term T ₃ for the target throttle opening stored in the ROM.
(described in detail later) to RAM. Next step
In S2, it is determined from the throttle opening signal c and the rotational speed signal b whether or not the throttle valve 7 is in the idle position and the engine rotational speed is below a predetermined rotational speed.
If so, return to step S2 again and repeatedly judge whether or not it is in the idle state.
When the result is YES, that is, when the state becomes idle, the process proceeds to steps S3 and subsequent steps. Then, in step S3, the operating state of the engine, that is, in this case, the temperature of the engine coolant and the presence or absence of a cooler load, is detected from the water temperature signal a and the cooler load detection signal d, and then in step S4, the temperature of the engine coolant and the presence or absence of a cooler load are detected. Accordingly, the target idle rotation speed N _SET is calculated based on the characteristics shown in FIG. The reason why the target idle speed is set high when the water temperature is low is because engine combustibility is poor when the water temperature is low, such as during a cold start, so stable idling is not possible unless the engine speed is above a certain level. This is because when the water temperature is high, the target idle speed is set higher when the cooler is turned on than when it is turned off. This is to prevent vehicle body vibration due to increased load.

Then, in step S5, the provisional target throttle opening _T1 corresponding to the target idle speed _NSET is determined from the characteristics shown in FIG. 4, and in step S6, the actual engine speed is determined from the speed signal b.
_Nrpn is detected, and in step S7, the difference between the target idle rotational speed _NSET and the actual idle rotational speed _Nrpn is multiplied by a constant k to obtain a first correction term for the target throttle opening _T2 = k ( _NSET - N _rpn ), and if this is the second _or more _time that the entire flowchart _{in FIG .} Perform the calculation.
Then, in step S8, it is determined whether or not the cooler is in the ON state. If the cooler is in the ON state, in step S9, T ₃ is loaded from the tape made of the RAM described above, and in step S11, T ₁ ,
Add T ₂ and T ₃ to get the target throttle opening T _SET
Calculate. When the cooler is in the OFF state, T ₃ = 0 is set in step 10, and the step
11, only T ₁ and T ₂ are added as T _SET . In other words, by adding the second correction term T ₃ above, the target throttle opening is adjusted when the cooler is ON.
T _SET is increased.

Next, in step S12, the actual throttle opening T ₀ is detected from the throttle opening signal c, and in step S13, the target throttle opening T _SET is determined.
The difference between this and the actual throttle opening T ₀ is detected, and a pulse signal with a duty ratio determined by the characteristics shown in FIG. 5 is output as a drive signal for the solenoid valves 12 and 13 according to the difference. These solenoid valves 1
2 and 13 actuate the throttle valve 7 via the diaphragm device 9, thereby controlling the amount of intake air.

As described above, the throttle opening, that is, the idle rotation speed, is feedback-controlled, and when the cooler is ON, prospective control is performed to increase the throttle opening by the second correction term _T3 .
Fluctuations in idle speed when the cooler is turned on are now suppressed. Furthermore, in the apparatus of this embodiment, the second correction term _T3 is automatically corrected to a more preferable value through the process shown in FIG. 2B. This point will be explained in detail below.

The CPU 22c of this device repeatedly performs the process shown in the flowchart in Fig. 2A at a speed of about 30 msec per round, but it can be seen that the cooler is switched from the OFF state to the ON state by the cooler load detection signal d. When detected, the routine of FIG. 2B interrupts the flow of FIG. 2A and performs interrupt processing. In this interrupt routine, first, in steps S21, 22, 23, and 24, steps S9, 11, and
The same processing as in steps 12 and 13 is performed, and drive signals for the solenoid valves 12 and 13 are output (note that
The values of T ₁ and T ₂ used previously are used). Before controlling the solenoid valves 12 and 13,
The rotational speed signal b carrying the subsequent idle rotational speed _Nrpn is input to the microcomputer 22, and in step 25, the solenoid valve 1
Idle rotation speed before and after driving 2 and 13
It is determined whether or not there has been a fluctuation of _Nrpn (this determination is specifically performed by calculating the differential (dN/dt) of the rotational speed). As mentioned above, in this device,
When the engine load is a cooler, the target idle speed N _SET is increased as shown in Figure 3, but other factors such as lamps, etc.
Target idle speed even if activated during idling
There are engine loads that do not require changing N _SET . For such engine loads, N ₃ values are stored in the table that compensate for the increase in load and keep the idle speed N _SET constant.
If such an engine load operates during idling and the idle speed _Nrpn does not change even if the solenoid valves 12 and 13 are driven, the above
It can be said that the _N3 value is extremely reasonable. Therefore, in that case, the interrupt processing is terminated, and the processing from step S2 onward in FIG. 2A is repeated again.

On the other hand, if there is a fluctuation in the idle rotation speed _Nrpn , it is determined in step S26 whether the fluctuation is an increase in speed or a deceleration. In the case of deceleration as shown in FIG. 6c, the setting of the second correction term _T3 is too small, so the second correction term _T3 is increased by the constant ΔT in step S27. In addition, the fluctuation of the idle rotation speed _Nrpn is due to speed increase as shown in Fig. 6d, and the target idle rotation speed
If N _SET is exceeded (this determination is made in step S28), the setting of the second correction term T ₃ is too large, and therefore the second correction term T ₃ is decreased by the constant ΔT in step S29.

By increasing or decreasing the _T3 value as described above, the idle speed N _rpn will be increased at the next estimated correction.
is not necessarily set exactly to the target idle rotation speed N _SET , but at least the accuracy of the estimated correction is improved. This modified T ₃ value is therefore stored in step S30 in place of the value previously stored in the RAM. By sequentially rewriting the value of the second correction term T ₃ in this way, the most appropriate T ₃ value for each engine load will eventually be stored in the table.
Furthermore, even if engine performance changes over time, it is possible to follow those changes and set the most appropriate _T3 value.

In this case, it is preferable that the memory (RAM) in which the _T3 value to be rewritten and corrected is stored is a non-volatile memory so that the correction will be reflected in the next operation even if the key switch is turned off.

Even if the idle speed N _rpn changes in the direction of speed increase,
The idle rotation speed N _rpn is the target idle rotation speed
If it does not exceed _NSET , as shown in Figure 6e, the idle speed _Nrpn follows the setting change of the target idle speed _NSET , and predictive control is being performed well. The _T3 value at that time will be maintained as it is. Therefore, step S28
If the target idle rotation speed is set and changed when the engine load is ON, the N _SET value in is the value when the engine load is ON (that is, 750 rpm in the case of the cooler exemplified above).

When the interrupt processing explained above is completed, the second
The process from step S2 in Figure A is repeated, but
Thereafter, the T ₃ value more preferably modified by the above-mentioned interrupt processing is used for calculation processing.

The above explanation has only cited the cooler as an example of engine load, but there are many engine loads that can be activated during idling, such as automatic transmissions and power steering, and the values of the second correction term T ₃ mentioned above are each independently tabled. The _T3 values are stored in the table and used by being called from the table according to the operation of each engine load, and each T3 value is independently corrected by the interrupt processing shown in Figure 2B mentioned above. It is something.

Further, in the idle rotation control device of the above embodiment, while the engine load is on, the second
Although the correction term T ₃ is provided, the present invention can also be applied to an idle rotation control device that provides the second correction term T ₃ only immediately after the engine load is switched from the OFF state to the ON state.

Furthermore, in the above embodiment, the idle speed is controlled by controlling the throttle valve 7, but the idle speed control device includes a throttle bypass valve that opens and closes a throttle bypass valve provided in a bypass passage that bypasses the throttle valve. There is also a device that controls the idle speed by controlling the idle speed, and the present invention can of course be applied to a device that performs such throttle bypass valve control. Further, the present invention can of course be applied to a control device that feeds back only the engine speed, in addition to a control device that feeds back both the engine speed and the control valve displacement position as in the above embodiment.

Further, as the actuator for driving the control valve, in addition to the actuator using the diaphragm device 9 in the embodiment described above, for example, an electric type may be appropriately selected and used.

As explained in detail above, the engine idle speed control device of the present invention automatically corrects the increased intake air amount during prospective control to a more preferable value. For example, even if there is a change in engine performance, it is possible to always stably maintain a constant idle speed without causing hunting or stalling during engine load operation.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an engine idle rotation control device according to an embodiment of the present invention, and FIG. 2A and 2B are
The figure is a flowchart of arithmetic processing by the CPU in the embodiment shown in Fig. 1, Fig. 3 is a characteristic diagram of the target idle speed in the above embodiment, and Fig. 4 is a temporary target throttle opening for the target idle speed in the above embodiment. Fig. 5 is a characteristic diagram of the duty ratio of the solenoid valve drive signal with respect to the difference between the target throttle opening and the actual throttle opening, and Fig. 6 is an explanatory diagram showing the state of idle rotation control in the above embodiment. It is. 1...Engine, 7...Throttle valve, 14...
...Actuator, 15...Water temperature sensor, 18...
...Distributor with built-in rotation speed detector, 19...
...throttle opening sensor, 20...cooler switch, 22...actuator control device (microcomputer).

Claims (1)

[Claims] 1. A rotation speed detector that detects the engine rotation speed,
an operating state detector that detects the operating state of the engine, a load operation detector that detects the operation of the engine load that is activated during idling, and an intake air adjustment means that adjusts the amount of intake air supplied to the engine;
a storage means for storing a correction value for increasing the amount of intake air by a predetermined amount when the engine load is activated; and a storage means that receives the outputs of the respective detectors and adjusts the actual idle rotation speed to a target idle rotation speed corresponding to the operating state. The intake air adjustment means is controlled so that the amount of intake air is converged, while the amount of intake air is increased by a predetermined amount based on the correction value in the storage means when the engine load is operating, and the correction value is used when the engine load is not operating. Based on the engine speed fluctuation when the engine load operating state changes from , the actual idle speed during engine load operation is further corrected so that the fluctuation is smaller with respect to the target value, and a final correction value is obtained. and a control device that rewrites the correction value in the storage means to the final correction value and increases the amount of intake air based on the final correction value when the engine is operated under load next time. Control device.