JPH0316496B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an idle speed control device, particularly an internal combustion engine having an air valve that bypasses a throttle valve and closes at a predetermined temperature or higher, to control the valve opening degree of idle speed control during engine starting. The present invention relates to a device for controlling the idle speed.

In recent years, with the deterioration of the energy situation, the demand for lower fuel consumption of automobiles has increased, and in conjunction with the tightening of exhaust gas regulations, various methods have been proposed. One such method is to precisely control the idle speed according to various conditions under which the engine is placed, such as intake air temperature and engine cooling water temperature.

This method is usually called an idle speed control system (hereinafter referred to as ISC) and attempts to control the idle speed to a desired value, that is, the target speed by adjusting the amount of air flowing into the bypass path of the throttle valve during idle. It is something.

Similarly, a method of using ISC to fully open the ISC valve to assist the starting of the internal combustion engine at the time of starting, and then immediately reducing the ISC valve opening to the target opening after starting has been considered. There is.

However, with this method, the ISC valve tends to immediately close to the target value from fully open at startup, which tends to cause the ISC valve to temporarily go below the target value, that is, overshoot, especially when cold. When the air valve necessary for starting is closed, that is, when the engine is at a high temperature, insufficient air intake into the engine can lead to unstable engine rotation and engine stall.

The present invention is intended to prevent the above-mentioned phenomenon, and prevents the ISC valve from being overclosed by gradually reducing the opening degree of the ISC valve when the engine is at a high temperature.

That is, the gist of the present invention is to provide an idle speed control means for bypassing the throttle valve, an internal combustion engine temperature detection means, and an internal combustion engine starting means in an internal combustion engine having an air valve that bypasses the throttle valve and closes at a temperature higher than a predetermined temperature. control means for controlling the idle speed control valve based on the signal from each detection means and the learned value based on the opening degree of the idle speed control valve during the previous feedback; An idle rotation speed control device is provided, characterized in that the valve opening degree is gradually changed from fully open to a learned value when the internal combustion engine is idling immediately after starting in a state where the internal combustion engine is at a predetermined temperature or higher.

The present invention will be explained below by giving an example and referring to the drawings.

First, FIG. 1 is a schematic system diagram showing an idle speed control device to which the present invention is applied and its surroundings.

1 is an engine body, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is an oxygen sensor provided in the exhaust manifold 4 and detects the residual oxygen concentration in the exhaust gas, 6 is an oxygen sensor in the intake air of the engine body 1 a fuel injection valve for injecting fuel; 7 is an intake manifold; 8 is provided in the intake manifold 7;
An intake temperature sensor that detects the temperature of intake air sent to the engine body 1; 9 a water temperature sensor that detects the temperature of engine cooling water; 10 a throttle valve;
11 is a throttle position sensor that is linked to the throttle valve 10 and outputs a signal according to the opening degree of the throttle valve 10; 12 is a bypass passage that is an air passage that bypasses the throttle valve 10; and 13 is a bypass passage. Idle speed control valve (hereinafter simply referred to as
(referred to as an ISC valve), 14 represents an air flow meter for measuring the amount of intake air, and 15 represents an air cleaner for purifying the intake air. Of these,
The bypass passage 12 and the ISC valve 13 correspond to idle speed control means, and the water temperature sensor 9
corresponds to the internal combustion engine temperature detection means.

Further, 16 is an igniter that outputs the high voltage necessary for ignition, 17 is a distributor that is linked to a crankshaft (not shown) and distributes the high voltage generated by the igniter 16 to the spark plugs 3 of each cylinder, and 18 is a distributor. A rotation angle sensor 19 is attached to the distributor 17 and outputs a pulse signal 24 times per one revolution of the distributor 17, that is, two revolutions of the crankshaft.
a cylinder discrimination sensor that outputs a pulse signal once per rotation; 20 is an electronic control circuit; 21 is a key switch;
22 each represents a starter motor.
Of these, the rotation angle sensor 18 and the throttle position sensor 11 correspond to internal combustion engine idle state detection means, and the key switch 21 corresponds to internal combustion engine start detection means.

Furthermore, 23 indicates a passage through which air flows bypassing the throttle valve when the engine is cold, that is, a first idle bypass passage. Reference numeral 24 indicates an air valve that controls the amount of air passing through the first idle bypass passage 23. still,
The air valve 24 operates to open the first idle bypass passage 23 in order to secure the engine speed necessary for warm-up operation when the engine is cold. At this time, the ISC valve 13 is also opened, but when the engine is idling at a high temperature, the air valve is closed and only the ISC valve is opened.

Next, FIG. 2 shows a block diagram of the electronic control circuit 20. As shown in FIG.

30 inputs and calculates the data output from each sensor according to the control program, and also inputs and calculates the data output from each sensor.
A central processing unit (hereinafter simply referred to as CPU) performs processing for controlling the operation of various devices such as the valve 13; 31 is a read-only memory (hereinafter simply referred to as ROM) in which the control program and initial data are stored; 32 is electronic control circuit 2
Random access memory (hereinafter simply referred to as RAM) 33 is used to read and write data input to 0 and data necessary for arithmetic control, and 33 is connected to a battery so that data necessary for engine operation is retained even when the key switch 21 is turned off. A backup random access memory (hereinafter simply referred to as backup RAM), 34 is an input port (not shown), a waveform shaping circuit is provided as necessary, and output signals from each sensor are selectively output to the CPU 30. The input sections each include a multiplexer for converting an analog signal into a digital signal, an A/D converter for converting an analog signal into a digital signal, and the like. 35 is provided with an output port in addition to an input port (not shown), and other ISC valves 13 etc. are connected to the CPU as necessary.
30 represents an input/output unit equipped with a drive circuit etc. that drives according to control signals, and 36 represents the CPU 30,
It represents a bus line connecting each element such as the ROM 31, the input section 34, and the input/output section 35, and through which various data are sent.

Next, FIG. 3 shows a flowchart of the processing of the apparatus of the present invention.

Reference numeral 51 represents a processing section at the time of starting the ISC. Here, step 52 represents a determination as to whether or not it is time to start, and this determination is made based on a signal from the key switch 21, which is means for detecting the start of the internal combustion engine. If it is the time of starting, the process moves to step 53; otherwise, the process moves to step 55. Step 53 determines the opening degree of the ISC valve.
100%, or fully open processing. Step 54 represents the process of setting a decrease flag. Step 55 represents a determination as to whether or not the decrease flag is set, and if the flag is set, the process proceeds to step 56.
Otherwise, the process moves to ISC feedback processing 62. Step 56 is based on the signal from the water temperature sensor 9.
This represents a determination as to whether or not the engine cooling water temperature is equal to or higher than a predetermined value. The predetermined value is usually set at 70°C or higher. If the water temperature is above the predetermined value, step 5
If not, the process moves to step 57. Here, determining the cooling water temperature based on the predetermined value means determining whether or not the engine is in first idle. Step 57 represents a determination as to whether the current opening degree D of the ISC valve 13 exceeds the sum of the opening degree learning value DG and the constant value α. The opening degree learning value DG means the ISC valve opening degree at the time of the previous ISC feedback, and for example, the one stored in the backup RAM is used. The constant value α is set as a warm-up opening degree so that the engine rotation becomes faster for warm-up operation during first idle. D＞
If DG+α, the process moves to step 59; otherwise, the process moves to step 61. Step 58
In this case, the current opening degree D of the ISC valve 13 is the opening degree learning value.
Indicates whether or not the DG has been exceeded. D＞
If it is DG, the process moves to step 59; otherwise, the process moves to step 61. Step 59 represents a determination as to whether a certain amount of time has elapsed since the last time the opening degree D of the ISC valve 13 was decreased. Here, instead of the predetermined time, the determination may be made based on whether or not the engine has rotated for a predetermined time. When a predetermined period of time has elapsed or the engine has reached a predetermined rotation, step 60
Otherwise, ISC feedback processing 62
Processing moves to The predetermined time is measured by a timer installed in the electronically controlled rotation 20;
In the case of determining the predetermined rotation, the rotation angle sensor 18 of the distributor 17 or the cylinder discrimination sensor 19 measures the rotation angle. Step 60 represents a process of decreasing the opening degree D by a predetermined value β. This process causes the ISC valve opening to gradually decrease. Step 61 represents the process of turning down the decrease flag. 62 represents an ISC feedback processing section. Here, step 63 represents a determination as to whether conditions have been reached that allow feedback processing. This determination is made when it is determined that D≦DG+α or D≦DG in step 57 or step 58 when the vehicle is in an idle state, and it is determined that the ISC feedback condition is satisfied. If the condition is met, proceed to step 64;
If not, exit from this flow and proceed to other processing. Step 64 represents a process of performing ISC feedback calculation processing and adjusting the ISC valve opening degree based on the calculation result.

Next, based on actual processing, we will follow the processing performed by the apparatus of the present invention while also referring to FIG. 4, which shows changes in ISC valve opening over time.

First, the engine is started by turning on the key switch 21, but at the time of starting,
At step 52, the determination is ``YES'', and the process moves to step 53. In step 53, the ISC
Valve 13 is fully opened (D=100%) and serves to assist in starting the engine. Then, in step 54, a decrease flag is set. Next, the process moves to ISC feedback processing, but since the opening degree of the ISC valve 13 has just reached full open, the determination is "NO" and the process exits to other processing. The above process continues until the engine starts, and the ISC valve remains fully open. The opening degree of the ISC valve is at time t ₁ in Figure 4.
This is the flat state it was in before.

Next, if the engine starts running, step 5
In step 2, the determination is "NO" and the process moves to step 55. In Fig. 4, this corresponds to time _t1 . In the determination at step 55, since the decrease flag has already been set at step 54, the result is ``YES'' and the process moves to step 56. In step 53, if the engine is not in fast idle, that is, if the cooling water temperature is above a predetermined value, the process moves to step 58. Then, in step 58, the ISC
The magnitude of the learned opening degree DG of the valve 13 and the current opening degree D is compared and determined. In the process of step 53, since the valve is initially fully open, the determination in step 58 is "YES", and the process then moves to step 59. At step 59, the opening time for reducing the opening degree is adjusted. Here, each time a certain period of time or a certain rotation of the engine has elapsed since the previous opening reduction process, step 60 is processed and the opening degree D is gradually reduced. This is because the constant value β in step 60 is set to a sufficiently smaller value than the learning value DG, so that a gradual decrease is achieved. In FIG. 4, this corresponds to the straight line a or the curve b between <sub>t1</sub> and <sub>t2</sub> . ``a'' is the opening degree that is decreased at regular intervals, and ``b'' is the opening degree that is decreased every constant rotation. Next, D decreases in this way, and if it is determined in step 58 that D>DG is no longer satisfied, the process proceeds to step 61.
, and the decrease flag is defeated. In Figure 4, the time point
Applies to _t2 . In this way, the decrease flag is defeated,
The process moves to the next process, ISC feedback process 62, and if the feedback condition is satisfied in step 63, the ISC valve enters the feedback state. The opening degree is the state represented by the waveform after _t2 in FIG. 4.

Next, in step 56, if the engine is in a fast idle state and the cooling water temperature is less than a predetermined value, the process moves to step 57. Next, in step 57, the opening degree learning value of the ISC valve 13 is determined.
A constant value α is added to DG, and the magnitude of the opening degree D is compared and determined using the value as a reference. Adding α here is
This is to maintain the opening degree of the ISC valve larger as the warm-up opening degree for warm-up operation since the engine has not yet warmed up. In the process of step 53, since the valve is initially fully open, the determination in step 57 is "YES", and the process then moves to step 59. At step 59, the opening time for reducing the opening degree is adjusted. here,
Each time a certain period of time or a certain number of rotations of the engine have passed since the previous opening reduction process, step 60 is executed and the opening D is gradually reduced. this is,
Since the constant value β in step 60 is set to a sufficiently small value compared to the learning value DG,
A gradual reduction is achieved. In FIG. 4, this corresponds to the straight line a or the curve b between _t1 and _t3 . ``a'' is the opening degree that is decreased at regular intervals, and ``b'' is the opening degree that is decreased every constant rotation. Next, D decreases in this manner, and if it is determined in step 57 that D>DG+α is no longer satisfied, the process moves to step 61, and the decrease flag is set down. In Figure 4, this corresponds to time _t3 . In this way, the decrease flag is defeated, and the next process, ISC feedback process 6
2, since the warm-up operation is still in progress, it is not determined in step 63 that the feedback condition is satisfied. In FIG. 4, a flat state C of the warm-up opening degree α + learned value continues from _t3 . Here, α corresponds to approximately 50 to 450 rpm in terms of engine speed.

However, when the engine cooling water temperature rises sufficiently to eliminate the need for warm-up operation, the reduction flag has already been set down, so the feedback condition is met in step 63, and the ISC valve enters the feedback state. In FIG. 4, the state is represented by the waveform after _t4 .

In this way, the ISC valve, which is fully open at startup,
By gradually reducing the value to the learned value, unstable engine rotation or engine stall that would occur if the value suddenly changed does not occur. In addition, after the engine starts, the opening degree decreases and the decrease flag is set down, and the ISC feedback processing
The time it takes for the ISC valve to be controlled is
Usually 2-3 seconds or 40-50 engine revolutions
Rotation is appropriate.

As described above, the present invention provides an idle speed control means for bypassing the throttle valve in an internal combustion engine having an air valve that bypasses the throttle valve and closes at a temperature above a predetermined temperature.
Internal combustion engine temperature detection means, internal combustion engine start time detection means, internal combustion engine idle state detection means, and idle detection based on the signals from each detection means and the learned value based on the opening degree of the idle speed control valve during the previous feedback. and a control means for valve-controlling the speed control, and gradually changes the valve opening from fully open to a learned value when the internal combustion engine is idling immediately after starting with a temperature above a predetermined temperature, so as to prevent sudden changes. It does not close too much temporarily,
Even when the air valve is closed, the engine speed can be changed smoothly.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram showing an idle speed control device and its surroundings according to an embodiment of the present invention, Fig. 2 is a block diagram showing its electronic control part, and Fig. 3 is a flowchart showing its processing flow. , Figure 4 is
It is a graph showing the time course of the ISC valve opening degree. 10... Throttle valve, 11... Throttle position sensor, 13... ISC valve, 18
...Rotation angle sensor, 20...Electronic control circuit, 21
...Key switch.

Claims (1)

[Claims] 1. In an internal combustion engine having an air valve that bypasses the throttle valve and closes at a predetermined temperature or higher, idle speed control means that bypasses the throttle valve, internal combustion engine temperature detection means, internal combustion engine start detection means, and internal combustion engine idle state detection means , control means for controlling the idle speed control valve based on the signals from each detection means and the learned value based on the opening degree of the idle speed control valve during the previous feedback, An idle rotation speed control device characterized in that the valve opening degree is gradually changed from fully open to a learned value during idling immediately after startup.