JPS6119948A - Method of controlling idling speed of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent drop of engine rotational speed or stall at transition of an increase in load, by increasing a target air amount for a predetermined time according to the engine rotational speed when racing is stopped and load is added under an idling condition with light load. CONSTITUTION:Under the condition that engine rotational speed NE is high with racing at N range, when the racing is stopped to select D range, the rotational speed NE is lowered. Compensation control of air amount by an increased opening angle PND is started according to the rotational speed NE at the selecting operation, and an output opening angle POUT of an ISC valve 16 is set to (Po+ Pe+PND) after the time of T0, where P0 is a fundamental opening angle for feed- back control of the ISC valve 16; Pe is an estimated opening angle for feed- forward control; and P0+Pe is a target opening angle P. The output opening angle POUT is decreased to the target opening angle P after the retention time of T, and is shifted to be controlled at a stationary state. Then, the rotational speed NE smoothly reaches a target rotational speed at the D range.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for controlling the idling speed of an internal combustion engine, and in particular to controlling the amount of air flowing into a bypass passage provided to bypass a throttle valve. The present invention relates to an idling rotation speed control method for controlling the engine rotation speed to a target rotation speed.

[Background of the invention]

In recent internal combustion engines, there is a trend to reduce the weight of the engine and to set the idle speed low in order to improve fuel efficiency.

For this reason, even a slight increase in load caused by turning on the no-hi beam, driving an electric fan, or operating the shift lever in engines equipped with an automatic transmission during idling will cause a drop in the engine speed, causing the engine to stop when idling. The engine speed may become unstable.

For this reason, a bypass passage is provided to bypass the throttle valve, and when the throttle valve is fully closed and the vehicle speed is below a predetermined value (for example, 0 to zsb/h), that is, when the engine is idling, air flows through this bypass passage. A method is known in which the engine speed is feedback-controlled to a target speed by controlling the amount. This bypass passage is equipped with an idle rotation speed control valve (ISO pulp) whose opening degree is controlled by a stepping motor or solenoid, and which controls the amount of air flowing into the bypass passage. By controlling the rotation speed, feedback control is performed to maintain the rotation speed close to the target rotation speed determined according to the engine load and shift position pressure. Note that when feedback control is not performed, the ISC pulp is maintained at a predetermined opening degree at t6.

However, even if such feedback control controls the amount of air flowing into the bypass passage according to fluctuations in engine speed,
K takes time for this control to be reflected in the engine speed, and especially when the load suddenly decreases and the engine speed suddenly decreases, the engine speed may drop significantly before the feedback control is reflected. There is a problem with the model name when the engine stops.

In order to eliminate the response delay of feedback control, a target air volume is determined in advance according to the degree of load, and ISO pulp is set so that the corresponding target air volume flows into the bypass path when the load increases. Feedforward control may be considered. However, the dynamic characteristics of an internal combustion engine generally have poor step response, and during a transient period from when the load increases until reaching a steady state, the load usually has a significantly negative value compared to the steady state. For example, in an internal combustion engine equipped with an automatic transmission, the shift lever is moved to the neutral range (N range).
Drive range (D range) -? Immediately after shifting to the IJ berth range (N range), the fluid resistance force of the torque converter is large, so the load may become transiently large.

Therefore, if the feedforward target air amount is set according to the steady state from the viewpoint of improving fuel efficiency as described above, the air amount may be insufficient during the above transient, causing the engine speed to drop, and eventually causing the engine to stall. There is a problem with this.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for controlling the idling speed of an internal combustion engine, which prevents the engine speed from dropping or stalling during a transient increase in load.

[Summary of the invention]

In order to achieve the above object, the present invention increases the amount of air flowing through one bypass path when a load is applied in an idling state from the target air amount when a load is applied, and then The purpose is to reduce the amount of air flowing through the engine to this target amount of air, thereby preventing a drop in engine speed and stalling during a transient increase in load.

In addition, even with the above configuration, if the engine is racing during idling under a light load and a load is applied before the increased engine speed has sufficiently decreased, for example, the engine speed will change from N range to D range. Furthermore, when the engine is shifted to the ViR range, the load becomes higher than the preset transient load, which causes problems such as a drop in engine speed and a stall.

Therefore, this problem is solved by increasing the target air amount for a predetermined period of time in accordance with the engine speed when a load is applied.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on examples.

First, an example of an internal combustion engine to which the present invention is applicable will be explained with reference to FIG.

This engine is equipped with an automatic transmission and is controlled by an electronic control circuit such as a microcomputer, and is equipped with an air flow meter 2 downstream of an air cleaner (not shown) for detecting the amount of intake air. The air flow meter 2 includes a retardation compensation plate that is rotatably provided in the damping chamber, a gear lift plate connected to the convention plate, and a potentiometer 4 that detects the opening degree of the convention plate. Therefore, the intake air amount is determined from the intake air amount signal output from the potentiometer as a voltage value. Further, an intake temperature sensor 6 is provided near the air flow meter 2 to detect the intake air temperature and output an intake temperature signal.

A throttle valve 8 is arranged downstream of the air flow meter 2, and the throttle valve 8 is in a fully closed state (
An idle switch 10 that is turned on at the idle position is installed, and a 111K surge tank 12 is installed downstream of the throttle valve 8. In addition, a surge tank 12 is installed that bypasses the throttle valve 8 and is installed on the upstream side of the throttle valve and the downstream side of the throttle valve. A bypass passage 14 is provided to communicate with the intake manifold 12. An ISC pulp 16 whose opening degree is adjusted by an l stepping motor is attached to this bypass passage 14. The combustion chamber of the engine 20 is connected to the trap via the intake boat 22.Furthermore, a fuel injection valve 2 is installed for each air amount so as to protrude into the intake manifold 18.
4 is installed.

The combustion chamber of the engine 20 is connected via an exhaust boat 26 and an exhaust manifold 28 to a catalytic converter (not shown) filled with a three-way catalyst. An 02 sensor 30 is attached to the exhaust manifold 28 to detect the residual oxygen concentration in the exhaust gas and output an air-fuel ratio signal. An engine coolant temperature sensor 34 is attached to the engine/engine block 32 so as to penetrate through the block 32 and protrude into the water jacket. This coolant temperature sensor 34Vi detects the engine coolant temperature.
and output the water temperature signal.

A trap spark plug 38 is attached to each cylinder so as to penetrate the cylinder head 36 of the engine 20 and protrude into the combustion chamber. The spark plug 38 is connected via a distributor 40 and an igniter 42 to an electronic control circuit 44 composed of a microcomputer or the like. A cylinder discrimination sensor 46 and a crank angle sensor 48 are installed inside the distributor 40, each of which includes a signal rotor fixed to the distributor shaft and a pickup fixed to the distributor housing. In the case of a six-cylinder engine, the cylinder discrimination sensor 46 outputs an air volume discrimination signal every 720'CA, for example, and the crank angle sensor 48 outputs an engine rotation speed signal every 30°CA, for example.

Further, the electronic control circuit 44 includes a key switch 50, a Neutraxis 9-switch 52, and an air conditioner switch 54.
, a vehicle speed sensor 56, and a battery 58 are connected. The key switch 50f'i outputs a starter signal when the engine is started, the neutral start switch 52 outputs a neutral signal only when the transmission is in the neutral position, and the air conditioner switch 54 outputs an air conditioner signal when the near conditioner is activated. Output. The vehicle speed sensor 56Vi is composed of a magnet fixed to the speedometer cable, a reed switch, and a magnetically sensitive element, and outputs a vehicle speed signal in accordance with the rotation of the speedometer cable.

As shown in Figure 3, there are 44 electronic control circuits.
(CPU) 60, read-only memory (ROM) 6
2. Ramdam access memory (RAM) 64, backup RAM (BU-RAM) 66, input/output capotro 8
, an analog-to-digital converter (ADC) 70, and buses such as a 7'-J bus and a control bus for connecting these. In the entry and exit capotro 8,
A vehicle speed signal, a cylinder discrimination signal, an engine speed signal, a fully closed throttle signal from the idle switch 10, an air-fuel ratio signal, a starter signal, a neutral signal, and an air conditioner signal are input. In addition, the input/output capotro 8 is a drive circuit that transmits an ISO pulp control signal for controlling the opening degree of the SC valve, a fuel injection signal for opening and closing the fuel injection valve, and an ignition signal for turning the ignition on and off. The drive circuit controls the ISO valve, fuel injection valve, and igniter according to these signals. In addition, the ADC70 has
An intake air amount signal, an intake air temperature signal, a battery voltage, and a water temperature signal are input, and these signals are sequentially converted into digital signals according to instructions from the ADCVi CPU. ROM62
The target rotation speed determined according to the engine cooling water temperature, intake temperature, load condition, shift lever range position, etc., estimated factors for performing feedforward control when a load is applied, and the amount of air during transient times. The amount of increase and other control programs are stored in advance.

Next, an embodiment in which the present invention is applied to the gas engine as described above will be described in detail. In the following, an example will be described in which the shift lever of the automatic transmission/sumitsution is shifted from the N range to the D/lfR range.

FIG. 4 shows the middle of the main routine which is the basis of the control procedure of the first embodiment of the present invention. In step 100 of the figure, the engine load condition is determined based on the presence or absence of the air conditioner signal and the neutral signal, and the ISO valve 16 is adjusted in accordance with the target rotation speed NF corresponding to this load and the expected air amount to be increased or decreased according to this load. Estimated opening Pe
is set in a predetermined area of RAM. Next step 102
Then, it is determined whether or not the idle speed control (ISO) control timing has arrived. This control timing is set to a constant period (for example, 0.5 to 2 seconds). If the ISO control timing is different, an average value NE of the engine speed is calculated based on the engine speed signal in step 104, and it is determined in step 106 whether the feedback control condition is satisfied. This feedback control condition is, for example, that the throttle valve is fully closed, the vehicle speed is below a predetermined value (for example, 2.57 m/h), and the engine cooling water temperature is above a predetermined temperature (for example, 70° C.).

If the feedback control conditions are satisfied, in step 110, a basic ISO opening degree Po for feedback control of the average value of the engine speed to the target rotation speed is calculated, and when a load is applied, feedforward control is performed. Add the expected opening degree Pe to the basic opening degree Po to find the corresponding target opening degree P with the target air amount (.

In the next step 112, it is determined whether the learning control condition is satisfied, and if it is, learning control is performed in step 114, and then in step 116, the target opening degree P is set in the register as the output opening degree Pout. do. An example of this learning control is as follows. One is that after a predetermined period of time has elapsed after the feedback control, the average value NE of engine rotation speeds has reached a predetermined value (for example, 25 r
, p, m, ), and the deviation between the output opening degree Pout and the learned value stored in Bu-RAM is greater than or equal to a predetermined value, the learned value is gradually increased or decreased. Po
This is a method to bring utK closer. Another method is to constantly compare the average value NE of the engine rotational speed with the target rotational speed, and increase or decrease the learned value based on the magnitude relationship in order to bring the learned value closer to Pout.

Further, when it is determined in step 106 that the feedback control condition is not satisfied, step-no-loop control is performed, and in step 116, this target opening degree P is set as the output opening degree Pout.

The output opening degree Pou set in the register in this way
The opening degree of the mechanical SC valve 16 is controlled based on t.

Here, the opening degree P (including Po, Pe.

The specific value of Pout) is ■SC valve 16 (7)
The signal is a value representing the step position of the stepping motor corresponding to the opening degree. In addition, in the case of a method in which the ISO valve is opened and closed by a solenoid and the air amount is controlled by the opening time rate, the opening degree P may be determined by the duty ratio of the pulse signal that drives the solenoid.

μFAs explained above, when the feedback control condition is satisfied, the basic opening degree Po is changed so that the average value of the engine rotational speed becomes the target rotational speed, and the expected opening degree Pe
If there is, the opening degree of the ISO pulp is controlled by the added value.

Note that during open loop control, the target opening degree P becomes a predetermined value, so the SC valve opening degree is kept constant.

Next, the control procedure according to the characteristic configuration of the present invention will be explained along with the subroutine shown in FIG. This subroutine executes the target opening P obtained in step 108 and step 110.
The increased opening PND to compensate for the lack of air volume during load increase transients is added to the output opening Pout, and the result is reflected in the output opening Pout, and is executed at predetermined intervals by an interrupt signal. . First, in step 120, it is determined whether the shift position is in the N range or not based on the presence or absence of a neutral signal, and when it is in the N range, a 7-lag FN is set in step 122. If it is not the N range, that is, if it is the D range or N range, the flag FN is set in step 124.
Determine whether or not is set. If the flag FN is set, that is, if the gear is shifted from N7 to another range, in step 126, a predetermined time To (usually 0 to isee) has elapsed from the time of the shift until the torque converter is activated. It is determined whether or not the predetermined time To has elapsed, the process moves to step 128.

In step 128, it is determined whether or not the engine speed NE at the time of shifting exceeds a predetermined value α, and if the determination is affirmative, the increased opening degree PND is set to a predetermined value βl in step 130. When the determination is made, the increased opening degree PND is similarly set to the set value β2 in step 132. Note that the predetermined value α is the target idling rotation speed 11, for example, the target idling rotation speed NEn of the D range (for example, 50
0 to 700 rpm), specifically Id 1000 rpm to 2000 rpm
mlc is set.

The installation value β2 is set according to the transient load when the rotation speed at the time of shifting is below the vicinity of NED, and the set value β1 is set according to the transient load partial pressure at the rotation speed exceeding NEa.
Stellar 7'a of the stepping motor is selected to have 10 to 30 steps, and β2 is selected to be approximately 4 to 10 steps. Still, the method of determining the increased opening degree PND is still described in step 128,
Instead of the procedure consisting of steps 130 and 132, it may be given as a function that increases as the engine speed/parameter.

In this way, after setting the increased opening PND, step 1
34, the flag FN is reset, and further, in step 142, the increased opening PND is added to the previous target opening P to set the current target opening P, and the flag FN is reset to T1, which will be described later.
Start counting time.

On the other hand, after the flag FN is set in step 122, and when it is determined in step 124 that the flag FN has been reset, that is, if a state other than N/J continues, then step 136 is performed to increase the flag FN. Then, it is determined whether PND is 0 or not. When the increased opening degree PND is 00, the process directly proceeds to step 142, and when it is other than 0, the process proceeds to step 138 to determine whether the set time T1, which is defined as a period for performing compensation by the increased opening degree PND, has elapsed. to judge. If this judgment is negative, step 14
The process proceeds to step 2, where the compensation by PND is maintained, and when the answer is affirmative, the PND is set to 0 in step 140, and the compensation control is ended. Note that the above 71 hours is a constant value or a function value of the engine rotation speed NE.

FIG. 5 shows changes over time in the output opening degree Pout and the engine speed NE when the control is performed according to the blue routine shown in FIG. 1 described above. As shown in the figure, when racing is stopped from a state in which the engine speed NE is raised by racing in the N range, the idle switch turns from off to on and at the same time, the engine speed NEH solid line L1
decreases as shown in . When the shift position is changed to D/J during this lowering process, as mentioned above, the N
Compensation control of the air amount by increasing the opening PND K according to E is started, and after the elapse of time To, the output opening Pout becomes (P o
-1-Pe-)-PNo). After this value is held for T + time, Pout (Po-1
-Pe) and transition to steady-state feedback control. As a result, the engine rotational speed NE smoothly reaches the idling target rotational speed N E o VC of the D range as indicated by the solid line °g. On the other hand, if PND compensation is not performed, the change will be accompanied by undershoot, as shown by the dashed-dotted line L2 in the figure.
When this was severe, there was a problem that the engine would stall.

In addition, in the above embodiment, as shown in FIG. 5, control was explained in which the PND is turned to O immediately after the elapse of the T1 time.
As shown by the two-dot chain line in the same figure, K may be gradually decreased at a constant rate after 1.1 lapse.

In this way, the change in engine speed NE can be made even smoother. The subroutine in this case is
Step 144 in FIG. 6 replaces step 140 in FIG.
, 146, 148.

In addition, although the above embodiment has been described as an example in which the load is increased when the BN range is switched to the D range, the present invention is also applicable to the case where the load is increased when the N range is shifted to the N range, or when an electrical load (such as a brake light) It can also be applied to the installation of increased loads such as air conditioners and cooler compressors. In this case, the application of an electrical load is detected by fluctuations in the battery voltage, and the operation of the cooler compressor is detected by the air conditioner switch. Furthermore, the present invention can also be applied to an engine equipped with a manual transmission.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent a drop in the engine rotational speed or a stall during a transient period due to an increase in load under any conditions during idling.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the main control procedure of an embodiment of the present invention, FIG. 2 is a schematic diagram of an example of an engine to which the present invention can be applied, and FIG. 3 is a block diagram of the electronic control circuit of FIG. 2. 4 is a flowchart of the main routine related to the flowchart of FIG. 1, FIG. 5 is a time chart for explaining the operation of an embodiment of the present invention, and FIG. 6 is a flowchart of another embodiment of the present invention. 3 is a flowchart showing main control procedures.

Claims (1)

[Claims] (1) In an internal combustion engine idling speed control method that controls the idling speed of the engine to the target speed by controlling the amount of air flowing through the bypass path of the throttle valve to a target air amount corresponding to the load, the load increases. 1. A method for controlling an idling speed of an internal combustion engine, the method comprising: increasing a target air amount corresponding to the increased load by a predetermined amount and for a predetermined time in accordance with the engine speed at the time of the load increase.