JPS5945825B2 - Internal combustion engine speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for feedback controlling the idle speed of an automobile internal combustion engine to a set value, and particularly to a device for canceling the feedback control when the engine temperature is high.

There is a device that improves idle stability by controlling the idle speed of an internal combustion engine to a predetermined target value depending on operating conditions.

This system determines the idle state based on vehicle speed, throttle opening, transmission gear position, etc., and the engine speed at idle is predetermined based on the engine temperature at that time and whether the vehicle's near conditioner is on or off. Feedback control that automatically increases or decreases the engine speed based on whether or not the engine speed is at the optimum speed.For example, an air-fuel ratio control device corrects the amount of fuel and air and provides feedback control to obtain the target speed. It is something to do.

(Unexamined Japanese Patent Publication No. 50-44327 U.S. Patent Specification No. 3,25
(No. 2,539) However, since this device always performs feedback control of the rotational speed during idling operation, the following problems may occur.

For example, if you stop immediately after driving at high power when the outside temperature is extremely high, the engine compartment temperature or engine temperature will rise significantly, and some of the fuel (gasoline) will vaporize (evaporate) in the fuel pipes. ), and the unstable situation 6) occurs in which the amount of fuel supplied to the engine is temporarily insufficient or inadequate due to passage clogging due to this vapor.

If feedback control is performed when the rotational speed fluctuates relatively sharply, due to the response time (delay) inherent in the control system, overcontrol (even if the fuel level reaches the correct level immediately due to vapor is caused by vapor). However, when this is detected and the fuel is increased), when the phase of this excessive response matches the air-fuel ratio fluctuation cycle, engine instability factors are amplified and a severe bunching condition occurs. occurs, and the engine vibration becomes severe.

In other words, feedback control of rotation speed is based on the assumption that the fuel properties are constant, and controls such that if the rotation speed falls below the target value, the fuel supply amount (air mixture amount) is increased, and conversely, if it rises, it is decreased. However, when the fuel temperature rises abnormally, unpredictable fuel properties may occur, including the phenomena described above, so fuel feedback may not necessarily be appropriate under these preconditions. There was a problem that this could lead to abnormalities in the engine.

Therefore, the present invention is designed to temporarily stop rotation speed feedback control during idling and return to normal open control when the engine temperature, fuel temperature, cooling water temperature, etc. become higher than a predetermined state. The purpose of this is to avoid at least the bunching phenomenon at abnormally high rotational speeds.

Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, 1 is an engine main body, 2 is an intake passage, and 3 is an exhaust passage.

Reference numeral 4 denotes a throttle valve interposed in the intake passage 2, 5 a bypass passage for adjusting the amount of idle air that bypasses the throttle valve 4 from upstream to downstream thereof, and an auxiliary air control valve 6 is provided in the middle thereof.

The auxiliary air control valve 6 has a negative pressure chamber 9 separated by a diaphragm 8 and a valve body 10 that opens and closes the passage 5 in response to the negative pressure controlled by the solenoid valve 7. .

Note that a damper 11 is installed in the negative pressure chamber 9 of the auxiliary air valve 6 in order to appropriately control the movement of the diaphragm 8.

The solenoid valve I is operated on and off by a pulse signal from an arithmetic circuit 12, which will be described later, and controls the dilution of the negative pressure supplied from the constant negative pressure valve 13 with approximately atmospheric pressure from the passage 14.
5 to the negative pressure chamber 9 of the auxiliary air valve 6.

In order to increase the responsiveness of the electromagnetic valve 7, a valve body 16 is attached to a diaphragm 17, and the valve port 19 is opened and closed based on the excitation and demagnetization of the solenoid 18.

□Also, the constant negative pressure valve 13 introduces suction negative pressure from the downstream intake passage 2 of the throttle valve 4 through the passage 22 to the negative pressure chamber 21 partitioned by the diaphragm 20, and this negative pressure and the spring 23
The valve port 24 opens and closes based on the balance between the valves 23a and 23b, moves to keep the negative pressure in the negative pressure chamber 21 substantially constant, and guides this constant negative pressure to the electromagnetic valve 1 through the orifice 25.

Next, an air flow meter 27 for detecting the amount of intake air is provided upstream of the throttle valve 4, and a crank angle sensor 29 for detecting the rotational speed of the engine crankshaft 28.
Based on the signal, the arithmetic circuit 12 generates a fuel injection signal that is synchronized with the engine speed and has a pulse width corresponding to the engine load, and this signal operates the fuel injection valve 31 installed in the intake port 30 to perform a predetermined injection. Control is performed to obtain an air-fuel ratio of .

On the other hand, this arithmetic circuit 12 includes a throttle valve opening sensor 33 that detects the fully closed state of the throttle valve 4, a neutral switch 35 that detects the gear neutral position of the transmission 34, and a predetermined value from the rotation of the transmission output side. An idle signal is input from an idle detection device including a vehicle speed sensor 36 that detects a low vehicle speed, and a pulse signal is output to the electromagnetic valve 7 described above so that a predetermined idle rotation speed is obtained at this time. .

In other words, the optimum idle speed is set in advance depending on the engine operating state, such as the on/off state of the near conditioner or the warm-up state, and these state detection signals are used (however, sensors are not shown). A target rotation speed is determined, and in order to control the amount of air that bypasses the throttle valve 4 so as to obtain this rotation speed, an on/off signal is adjusted to the solenoid valve 7 that controls the opening degree of the auxiliary control valve 6. Supplied.

When the air amount is finely adjusted in this way independently of the opening degree control of the throttle valve 4, the crank angle sensor 29 monitors the changes in the idle rotation speed and calculates the changes to match the target rotation speed. The circuit 12 performs feedback control.

Therefore, the idle rotation speed is corrected to accurately match the target rotation speed, which changes depending on the operating state.

By the way, in the present invention, in order to temporarily cancel this feedback control of the idle speed when the engine is at high temperature and prevent the aforementioned bunching phenomenon, for example, an engine cooling water temperature detection sensor 37 is provided, and the engine cooling water temperature detection sensor 37 is installed. For example, when the temperature is about 94° C. or higher, feedback is stopped, and only a signal corresponding to the target rotation speed is given to the electromagnetic valve 7 to switch to so-called open control.

In order to determine the high temperature state of the engine, the temperature of the engine atmosphere in the engine room, the temperature of fuel (gasoline) flowing through the fuel pipe, or even the temperature of engine oil or intake air may be detected.

Next, the overall operation will be explained.

As shown in FIG. 2, the idle state is determined, for example, when the throttle valve is fully open and the gear is neutral, or when the throttle valve is fully open and the vehicle speed is 81aIl/h or less.

As shown in FIG. 3, the target idle rotation speed is set depending on, for example, the state of the cooling water temperature.

Therefore, as shown in FIG. 4, feedback control is performed so that there is no deviation between the target rotational speed and the actual rotational speed, provided that the engine is not in a high temperature state during idling.

The greater the duty ratio of the pulse signal supplied from the arithmetic circuit 12 to the solenoid valve 7, the lower the control negative pressure becomes.
Along with this, the valve body 10 of the auxiliary air valve 6 is lowered, the opening degree becomes larger, and the amount of bypass air increases.

If this bypass flow rate increases, the air flow meter 27
detects an increase in the total amount of intake air, so the amount of fuel injected from the fuel injection valve 31 is increased, and the idle speed increases relatively.

If the amount of bypass air is reduced by the opposite operation, the idle speed will decrease.

By repeating this operation, the engine state is feedback-controlled to the target idle speed (this control includes a signal that eliminates the deviation by the proportional and integral parts of the deviation between the target value and the detected value). PI control for output, etc.).

By the way, when abnormalities such as fuel vapor lock are likely to occur, such as during idling immediately after the engine is operated at full power when the outside temperature is very high, the temperature from the cooling water temperature sensor 37, which serves as a means for detecting the high temperature state of the engine, is detected. Based on the output (
For example, when the water temperature is 94° C. or higher), feedback control for correcting the rotation speed to the target value is stopped.

Therefore, at this time, only the signal corresponding to the target rotational speed is supplied to the electromagnetic valve 7, and the multi-pressure operation based on the actually measured rotational speed is not performed, and the control is simply switched to open control.

As a result, even if vapor or the like occurs in the fuel piping, resulting in irregular fuel supply and a slight bunching phenomenon, the risk of large and severe bunching caused by feedback control can be avoided. Improves engine stability at high temperatures.

Note that an extreme rise in engine room temperature is likely to occur when the engine is stopped after the vehicle has been running, so when restarting the engine in a high temperature state, feedback control is performed only for a certain period of time after starting or for a certain rotation period. Even if you cancel the
The actual effect remains unchanged.

As described above, according to the present invention, feedback control of the rotational speed is canceled during idling operation where the temperature in the engine room is high and fuel tends to vaporize in the piping. Interference due to control delay can be eliminated, and problems such as 7'% engine rotation speed can be avoided.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the overall schematic structure of the present invention;
FIG. 2 is a flowchart showing a part of the control system, FIG. 3 is an explanatory diagram showing an example of setting the idle target rotation speed, and FIG. 4 is a flowchart showing cancellation of feedback control. 1... Engine body, 2... Intake passage, 4
... Throttle valve, 5 ... Bypass passage, 6.
...Auxiliary air valve, 7...Solenoid valve, 12.
... Arithmetic circuit, 13 ... Constant negative pressure valve, 27
...Air flow meter, 29...Crank angle sensor, 31...Fuel injection valve, 33...
... Throttle valve opening sensor, 35 ... Neutral switch, 36 ... Vehicle speed sensor, 37 ...
...Cooling water temperature detection sensor.

Claims (1)

[Claims] 1. An idle detection device for determining an engine idle state;
A rotation speed control device for an internal combustion engine that has a rotation speed detection means for detecting the engine rotation speed, and performs feedback control so that the rotation speed during idling matches a target rotation speed determined by operating conditions. A rotation control device for an internal combustion engine, comprising means for directly or indirectly detecting a fuel temperature, and configured to cancel the rotation speed feedback control and switch to open control when the detected temperature reaches a predetermined value. 2. The rotation speed control device for an internal combustion engine according to claim 1, wherein the temperature detection means is an engine cooling water temperature detection sensor. 3. The rotational speed control device for an internal combustion engine according to claim 1, wherein the temperature detection means is a fuel temperature detection sensor. 4. The rotational speed control device for an internal combustion engine according to claim 1, wherein the temperature detection means is an engine atmosphere temperature detection sensor. 5. The rotation speed control device for an internal combustion engine according to any one of claims 1 to 4, wherein the rotation speed feedback control is canceled for a certain period of time or a certain rotation period after the engine is restarted at a high temperature. .