JPS59200039A - Idling speed control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent an idling speed from going to high so extremely, by performing air quantity increment measures first and then suspending the increment measures till the specified time elapses when the detecting idling speed of an engine has come to below the lower limited value specified. CONSTITUTION:The opening area of an air bypass passage 12 bypassing a throttle valve 10 is controlled by an idling speed control valve 13 driven by a step motor or the like, thus an idling speed is controlled. In the case where the idling speed comes down to below the lower limit value and a fixed period of time elapses from the measures of the last time idling speed, namely, air quantity increment, there take place air quantity increment measures and therefore the idling speed is heightened but in that time other than it, the air quantity increment measures are not performed. As a result, even if such a state that engine speed comes down to below the dixed value in time of idling occurs at times in succession within a short time, the idling speed is prevented from going to high so extremely.

Description

[Detailed description of the invention]

[Technical field] The present invention relates to a method for controlling the idle speed of an internal combustion engine (engine), and in particular to a method for controlling the idle speed of an internal combustion engine (engine), in particular, when the engine speed (engine speed) falls below a predetermined lower limit value due to load, etc., the amount of intake air is increased by a certain amount. The present invention relates to an idle rotation speed control method for recovering the idle rotation speed through processing. [Prior art] In conventional idle speed control, that is, ISO control, in order to control the engine speed during idling (idle speed) within a certain range, the engine speed is sequentially detected, and the engine speed is adjusted accordingly. So-called idle speed feedback control is performed in which the intake air amount (hereinafter also simply referred to as air amount) is controlled and the engine speed is feedback-controlled so that the number falls within the above-mentioned certain range. Therefore, if the engine speed during idling changes due to power steering operation or turning on or off the near conditioner, etc., and a decrease in the idling speed is detected, the results are shown in Figure 1 (A), (B), and (C). As shown in Figure 2), the idle speed is restored to a constant value of 1.
This is to prevent an extremely low idle speed or an engine stall due to a drop in the idle speed. However, when performing conventional idle speed increase processing, if the load changes suddenly many times in a short period of time, the engine speed often decreases, and if the air volume is increased each time, the air volume will decrease. The problem was that the idle speed became extremely high when the load was removed. However, without such air amount increasing processing, it is impossible to prevent the idle speed from dropping or from enrinsing, and therefore, it is imperative that the idle speed increase from an extreme point to an end. In addition, in recent years, engines with extremely low friction have been developed with the main purpose of improving fuel efficiency, but in such engines, load fluctuations are greatly reflected in fluctuations in idle speed, resulting in the problems mentioned above. It tends to be encouraged. [Object of the Invention] The present invention provides an engine idle speed control method that controls the increase process associated with the decrease in the engine idle speed as described above, and eliminates the problem of the idle speed becoming extremely high. There is a particular thing. [Configuration of the Invention] The configuration of the present invention for achieving the above object is as follows:
As shown in the flowchart, (Pl) When the internal combustion engine is idling, the idle rotation speed is detected, and if the detected idle rotation speed deviates from a predetermined range, the idle rotation speed is within the predetermined range. In the method for controlling the idle speed of an internal combustion engine by feedback controlling the amount of air supplied to the internal combustion engine so that (P2) the idle speed becomes equal to or less than a predetermined lower limit value, (P3) Performs an air volume increase process to increase the air volume by a predetermined amount, and (P4) does not perform the air W increase process even if the idle rotation speed falls below the lower limit (bubble) until a predetermined period of time has elapsed. The gist of the present invention is a method for controlling the idle speed of an internal combustion engine, which is characterized in that:
First, FIG. 3 is a schematic system diagram showing a four-cycle four-cylinder engine and its peripheral equipment as an embodiment to which the method of the present invention is applied. 1 is an engine, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is provided in the exhaust manifold 4,
Oxygen sensor 6 detects the residual oxygen concentration in exhaust gas; 6 is a fuel injection valve installed for each cylinder to inject fuel; 7 is an intake manifold; 8 is an intake manifold 7
9 is a water temperature sensor that detects the cooling water temperature of the engine, 10 is a throttle valve, 11 is linked to a throttle valve 10, Throttle valve 1
0 opening degree

[Throttle position sensor 1 which outputs a signal in response to this, 12 is a bypass passage which is an air passage that bypasses the throttle valve 10, and 13 is a step motor or electromagnetic which controls the opening area of the bypass passage 120 and controls the idle rotation speed. An idle speed control valve (ISCV) driven by a solenoid or the like (in this embodiment, driven by a step motor), 14 an air flow meter for measuring the amount of intake air, and 15 an air cleaner for purifying the intake air. Further, 16 is an igniter that is equipped with an ignition coil and outputs the high voltage necessary for ignition, and 17 is a disc that is linked to a crankshaft (not shown) and distributes and supplies the high voltage generated by the igniter 16 to the spark plugs 3 of each cylinder. 1~Reviewer, 1
8 is installed in the distributor 17, and rotates 2 times per revolution of the distributor 17, that is, 2 revolutions of the crankshaft.
A rotation angle sensor 19 outputs four pulse signals, a cylinder discrimination sensor 19 outputs one pulse signal per revolution of the distributor 17, and an electronic control circuit 20. Furthermore, 21 indicates a passage through which air flows bypassing the throttle valve when the engine is cold, that is, a fast idle bypass passage. 22 indicates an air valve that controls air passing through the fast idle bypass path 21. The air valve 22 is designed to open the fast idle bypass passage 21 in order to secure the engine speed necessary for warm-up operation when the engine is cold. Next, FIG. 4 shows a block diagram of the electronic control circuit 20. 30 inputs and calculates data output from each sensor according to a control program, and also inputs and calculates data output from each sensor, and also inputs and calculates data output from each sensor.
Central processing unit 1- (hereinafter simply referred to as C
31 is a read-only memory in which data such as the control program and a map for calculating the fuel injection amount is stored; 32 is a read-only memory (hereinafter simply referred to as ROM); 32 is a read-only memory in which data such as the control program and a map for calculating the fuel injection amount is stored; A random access memory (hereinafter simply referred to as RAM) 33 is configured to retain learning value data necessary for subsequent engine operation even when the key switch is turned off. A backup random access memory backed up by a battery (hereinafter simply referred to as backup RAM), 34 is an input port (not shown), a waveform shaping circuit provided as necessary, and an output signal from each sensor can be selectively sent to the CPIJ 30. The input sections each include a multiplexer for outputting an output signal, a Δ/D converter for converting an analog signal into a digital signal, and the like. 3
5 is provided with an output port in addition to an input port (not shown), and other fuel injection valves 6, 15CV13 as required.
An input/output section 36 is provided with a drive circuit etc. to drive the CPLJ30. R
Each element such as OM31, input section 34 people, output section 35
・J-connection This represents the path line through which each piece of data is sent. Control of the fuel injection valve 6 by the electronic control circuit 20 is performed by outputting to the fuel injection valve 6 a pulse signal that remains at a low level for a period of time corresponding to the calculated fuel injection amount. Next, the control program of this embodiment will be explained along the flowchart of FIG. The control program shown in the flowchart in Figure 5 can be used as part of the main routine, or as a
Processing is executed at a predetermined timing stored in M31, for example, every 20 m5ec by a timer. When the processing of this program starts, first step 50
The throttle position sensor 11 detects whether or not the idling state is present, and whether the idle switch provided in the throttle position sensor 11 is on (fully open throttle) or off (between throttles) is detected by the throttle position sensor 11. and the idle switch is off,
That is, if rNOJ is reached, the process of step 110 described later is performed, and if the idle switch is turned on (rYESJ), the process moves to the next step 60. In step 60, the engine rotation speed N calculated based on the signal from the rotation angle sensor or the cylinder discrimination sensor is set to a lower limit value NL of a predetermined range of the idle rotation speed.
It is compared and determined. If it is determined that the engine speed N is greater than the lower limit value Nu, the process moves to step 110, which will be described later.On the other hand, if it is determined that the engine speed N is less than or equal to the lower limit value NL, the process moves to the next step 7o. Move to processing. In step 70, it is determined whether the value of the timer counter is greater than or equal to a predetermined value A. The timer counter TL uses a predetermined address area within the RAM 32 as a register and measures time by incrementing the value stored in the register at regular intervals. In this step 70, if it is determined that the value of the timer counter T1- is greater than or equal to A, the process moves to the next step 8o, and on the other hand, if the value of the timer counter TL is determined to be smaller than A. If so, the process moves to step 110, which will be described later. In the process of step 80, which is performed when it is determined in the startup 70 that the value of the timer counter IL is equal to or greater than A, a process of increasing the amount of air is performed. That is, ■S
The actuator (pulse motor) of the C valve 13 is driven by a predetermined amount to increase the amount of air during idling. This process increases the idle speed. At step J5, the timer counter TL is re-hit to zero and the processing of this routine ends. On the other hand, in steps 50, 60 and 70, both r
In the process of step 110 performed when the determination is NOJ, the value of the timer counter ]-L is incremented by one. Thereafter, the processing of this routine ends. When the engine speed in the idling state becomes equal to or lower than the lower limit value N1- by the process shown in the flowchart in FIG. At times, processing to increase the amount of air is performed and the idle speed is increased, and at other times, processing to increase the amount of air is not performed. As a result, even if a condition in which the engine speed falls below a certain value during idling occurs several times in succession within a short period of time, the inconvenience that the idling speed becomes extremely high is eliminated. Also, an idol. Within the prohibition period of rotation speed increase processing, that is, timer counter T
If the value of L is smaller than A, even if the engine speed falls below the lower limit value NL again, in that case, the air amount has already been increased by the previous process. It never goes down. If the above-mentioned control is explained with reference to Fig. 6, (a) in the figure,
As shown in (b), when the engine speed falls below the lower limit value NL, the air amount is increased to a constant value. but,(
As shown in c), when the value of the timer counter T1- is smaller than A, even if the engine speed falls below the lower limit value N1, the process of increasing the air amount is not performed. Next, another embodiment of the present invention will be described with reference to the flowchart of the control program shown in FIG. This control program is an example in which the value of the timer counter T is always incremented at almost constant intervals in the above-mentioned embodiment, whereas in the present embodiment, the value of the timer counter TL is incremented only during feedback control. In this embodiment, as in the previous embodiment, step 50.6
If the determination result in the processes at steps 0 and 70 is rNOj, the process at step 100 is performed. In step 100, it is determined whether feedback control is currently being performed. The determination as to whether this feedback control is in progress is made based on the idle switch, engine speed, and engine water temperature. That is, if the idle switch is on, the engine speed is below a certain value, and the engine cooling water temperature is above a certain value, it is determined that feedback control is being performed. If it is determined that the feedback control is not in progress, the process of this routine is immediately finished; on the other hand, if it is determined that the feedback control is in progress, the following step 1 is performed.
The process moves on to step 10. 'The processing at step 110 is the same as in the previous embodiment, and the value of the timer counter T is incremented. After the value of the timer counter is incremented in step 110, the processing of this program ends. Note that the processes shown in other steps and other configurations are the same as those in the above-described embodiment, and therefore their explanations will be omitted. In this way, in the process of this embodiment, the value of the timer counter TL is incremented only during feedback control. As a result, as shown in (a), (b), (c), and (d) of the graph showing the engine speed in Figure 8, when the engine speed becomes less than the lower limit value NL, the timer counter T
The intake air amount is increased only in cases (a) and (c) where the value of L is greater than or equal to Δ. If the value of the timer counter TL is not incremented due to interruption of feedback control and is not greater than A (b), (A
11-A2=A), and in the case (d) where feedback control is being performed but the value on the timer counter has not yet reached 8, the intake air amount increasing process is not performed. That is, in cases (b) and (d), in (a) and (c), it may be determined that the increased running air m has not yet been lowered to the predetermined level by feedback control (b) In (d), the process for increasing the amount of air is stopped and the idle speed is prevented from increasing excessively. This embodiment is particularly effective when the load is constantly fluctuating in a vehicle equipped with various accessory devices such as a near conditioner, a power steering device, a power seat, a power window, and even an automatic mill transmission. [Effects of the Invention] As described above in detail, according to the method for controlling the engine rotation speed of an internal combustion engine of the present invention, when the engine rotation speed falls below a predetermined lower limit value during idling, the air amount is reduced. is increased by a certain amount, and the air amount increase process is not performed until a predetermined period of time has elapsed even if the idle rotation speed falls below the lower limit value. Therefore, according to the present invention, even if the idling speed frequently falls below a certain engine speed due to load fluctuations, the intake air amount is increased each time.
The idle speed does not become extremely high due to the accumulation of the increased amount, and the idle speed is always controlled within a certain range. In addition, since the idle speed is stable, the driver does not feel that the engine is malfunctioning, and since the engine speed does not become abnormally high, it is possible to save fuel consumption during idling. It is possible to obtain side effects of
.

[Brief explanation of drawings]

Fig. 1 is an action explanatory diagram for explaining the action of the conventional example, Fig. 2 is a flowchart for explaining the present invention in detail, and Fig. 3 is an example engine and its A schematic system diagram of peripheral devices, FIG. 4 is a block diagram showing the electronic control circuit of the embodiment, and FIG. 5 shows the control program of the embodiment of the present invention.
FIG. 7 is an explanatory diagram explaining the operation of the embodiment, FIG. 7 is a photo of a control program showing another embodiment of the present invention, and FIG. 8 is an explanatory diagram explaining the operation of the same embodiment. It represents. 1... Engine (internal combustion engine) 10... Throttle valve 13... Idle speed control valve 18.
...Rotation angle sensor 19...Cylinder discrimination sensor 20...Electronic control circuit agent, patent attorney Tsutomu Ashioki and 1 other person Hour 20

Claims (1)

[Claims] When the internal combustion engine is idling, an idle rotation speed is detected, and if the detected idle rotation speed deviates from a predetermined range, the idle rotation speed is supplied to the internal combustion engine so that the idle rotation speed falls within the predetermined range. In an internal combustion engine idle speed control method that performs feedback control of an air amount, when the idle speed becomes less than or equal to a predetermined lower limit value, an air amount increasing process is performed to increase the air amount by a predetermined amount, and A method for controlling an idle speed of an internal combustion engine, characterized in that the air amount increasing process is not performed until a predetermined period of time has elapsed, even if the idle speed becomes less than or equal to the lower limit value.