JPS62178752A - Idle speed control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an engine speed from abnormally increasing even when a detector outputs a signal of abnormality, by inhibiting an actuator, when its driving position is located to the opening side of a throttle valve from its reference position, from being driven to the opening side. CONSTITUTION:A control circuit 30, which generates the first control pulse, second control pulse and an intermittent feedback control pulse, drives an actuator 20 to variably control an opening of a throttle valve 8 when an engine is in idle operation. Here the first control pulse sets the throttle valve opening to a reference position by receiving a detection output of each detecting means. And the second control pulse increases or decreases the throttle valve opening, set to the reference position, by a predetermined degree in accordance with an engine temperature detected by a temperature detector 28. Here the actuator 20, when its driving position detected by a position detecting switch 29 is located to an opening side of the throttle valve 8 from its reference position, is inhibited from being driven to the opening side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an idle speed control device for an internal combustion engine used in an automobile or the like.

[Conventional technology]

FIG. 2 is a general configuration diagram of an idle speed control device for an internal combustion engine. In Fig. 2, first, the configuration on the engine side will be explained. 1 is a piston, 2 is a cylinder, 3 is an intake valve, 4 is a cylinder.
5 is an exhaust valve, 5 is an exhaust pipe, 6 is a three-way catalytic converter, 7 is an intake pipe, and 8 is a throttle valve. On the upstream side of the throttle valve 8, a henturi 9 and an air cleaner 10 are provided. When the intake air taken in through the air cleaner 10 passes through the venturi 9, the fuel is
The fuel is sucked in through the main fuel passage 12 and atomized, becomes a mixture with intake air, and is guided into the cylinder 2 via the throttle valve 8 and the intake pipe 7.

In this case, a main air bleed 13 is provided in the middle of the main fuel passage 12, and the fuel in the float chamber 11 is passed through the main air bleed passage 13 provided upstream of the venturi 9.
It is atomized after being atomized by the intake air from the air.

On the other hand, an idle port 15 is located downstream of the throttle valve 8.
A slow air bleed passage 16 is also provided on the upstream side of the venturi 9, and the fuel in the main fuel passage 12 is atomized in the slow air bleed 17 by the intake air from this slow air bleed passage 16, and then transferred to the idle port. It is discharged from 15. As a result, fuel is secured during idling when the opening degree of the throttle valve 8 is almost fully closed. In this case, the amount of fuel discharged from the idle port 15 is adjusted by eight turns by the slow adjustment screw 18.

Here, the throttle valve 8 is an accelerator pedal (not shown)
During driving, the opening degree corresponds to the amount of depression of the accelerator pedal, and when the accelerator pedal is released and the vehicle is idling, the opening degree is the degree necessary to maintain the idling operating state. Further, the throttle valve 8 is provided with a lever 19 on its rotating shaft, and by driving this lever 19 with an actuator 20, which will be described later, the opening degree during idling is varied. Reference numeral 27 indicates cooling water for the engine, and 28 indicates a temperature detector serving as an engine temperature detection means for detecting the temperature of the engine.

Next, to explain the configuration of the idle rotation speed control system, reference numeral 20 consists of a DC motor 21 and a gear mechanism 22.The gear mechanism 22 converts the rotational motion of the DC motor 21 into linear motion of the plunger 23, and by this linear motion, It is an actuator that drives the lever 19 to vary the opening degree of the throttle valve 8, and the direct current motor 21 is supplied with a forward rotation control pulse U and a reverse rotation control pulse D of a predetermined pulse width from the control circuit 3o. In this case, the actuator 20 is provided with an idle state detection switch 24 that is turned on (closed) when the tip of the plunger 23 is in contact with the lever 19, that is, when the accelerator pedal is released and the vehicle is idle. Further, the plunger 2 of the actuator 20
A position detection switch 29 is provided which is turned off when the switch is on the open side from the reference position No. 3 and turned on when it is on the closed side.

Next, 25 is a rotation speed detector as an engine rotation speed detection means for detecting the engine rotation speed, and here, the ignition coil 251
A rotation pulse signal having a period corresponding to the engine rotation speed N is extracted from the connection point between the engine breaker 252 and the interrupter 252. 26 is a shift switch 30 that detects that the transmission (not shown) is in the neutral position or that the clutch (not shown) is turned on (depressed), that is, that the engine and the wheels are disconnected;
are an idle switch 24 that detects an idle state, and a rotation speed detector 25. Speed change switch 26. This is a control circuit that controls the throttle valve opening degree during idling based on the output signals of the temperature detector 28 and the position detection switch 29, and converges the engine speed to the target rotation speed NO.

As shown in FIG. 3, the control circuit 30 includes an arithmetic processing unit (
300 (hereinafter referred to as rcPUJ), a read-only memory (hereinafter referred to as "FROM") 301 that stores programs, constants, etc. for controlling the idle rotation speed, and a random access memory (hereinafter referred to as "FROM") that stores results etc. during calculations.
302 (hereinafter referred to as rRAMJ), and an interface circuit (hereinafter referred to as rlFcJ) 303 for transmitting and receiving signals between the various switches and actuator 20 described above.

Next, the operation of the conventional idle speed control device will be explained using FIG. 2, FIG. 3, and FIG. 9. First, when the engine is started, the CPU 300 executes the processing shown in the flowchart of FIG. 9 according to the program stored in the ROM 3'01. That is, in step 100, the CPU 300 captures the output signal from the rotation detector 25, detects the current engine rotation speed N by measuring the period of this output signal, and in the next step 101, detects the engine cooling water temperature. TW is detected, and further, in step 102, the target rotation speed No. during idling is detected. The target rotational speed NO during idling is stored in advance in the ROM 301 as a constant.

Therefore, the calculation of the target rotation 9NO at idle is based on ROM3.
This is realized by reading the above constant from 01.

Next, in step 103, it is determined whether or not the rotation fiN of the internal combustion engine is equal to or higher than the idle rotation speed control target range of 40 Orpm. If it is equal to or higher than 400 rpm, the routine advances to step 104; otherwise, the routine advances to step 114.

In step 104, it is determined whether or not the plunger 23 of the actuator 20 has reached the reference position. If so, the process moves to step 105; otherwise, the process moves to step 114.

In step 105, it is determined whether or not prospective control has been implemented. If it has been implemented, the process moves to step 106; otherwise, the process moves to step 118. Step 118
121 is a flow for performing prospective control.

In step 118, the cooling water temperature T8 is set to the reference temperature 1.
Determine whether the temperature is lower than 0°C, and if it is lower, step 119
The process moves to step 120 to set the drive mode of the actuator 20 to the opening side drive mode, and if not, the process moves to step 120 and sets the drive mode of the actuator 20 to the closing side drive mode. Thereafter, the process moves to step 121. In step 121, the pulse width P is determined according to the deviation (TwlO) as shown in FIG. Pulse drive control as shown in step 113 is performed using the prospective control pulse.

In step 106, it is determined whether the shift switch 26 is on, that is, whether the transmission is in the neutral position or the clutch is on, based on the output signal of the shift switch 26. If so, the process moves to step 107. If the speed change switch 26 is off, it is assumed that the vehicle is in a running state and the process proceeds to step 12.
2, the drive mode of the actuator 20 is set to the hold mode, and idle rotation speed control for the actuator 20 is not executed.

Next, in step 107, the idle switch 24
If it is on (in this case, the speed change switch 26 is also on), it is assumed that the main fuel to the engine is being supplied from the idle port 15, that is, the engine is in an idle state, and the next step 108 Move to. If the idle switch 24 is off, it is assumed that the driver is operating the accelerator pedal, and in step 122, the drive mode of the actuator 20 is set to the hold mode, and idle rotation speed control for the actuator 20 is not executed.

In step 108, the deviation between the rotation speed N of the internal combustion engine and the target rotation speed NO is calculated, and it is determined whether the absolute value of the deviation is smaller than a predetermined deviation value ΔN. If it is smaller, the process moves to step 122 and the drive mode of the actuator 20 is set to the hold mode. However, the deviation is a predetermined value ΔN
If it is larger than O, in steps 109 to 113 below, idle rotation speed control processing is performed to converge the engine rotation speed N to the target rotation speed No.

That is, in step 109, the current engine speed N is compared with the target speed NO, and if NO>N, the drive mode of the actuator 20 is changed because it is necessary to control the opening of the throttle valve 8 to the open side. The drive mode of the actuator 20 is set to the closing mode (step 110); conversely, if NO<N, it is necessary to control the opening of the throttle valve 8 to the closing side (step 110). 111). After that, in step 112, drive time data P of the actuator 20 corresponding to the rotation speed deviation between No and N (No-N) is determined.

is read from the ROM 301. This driving time data P,
The relationship between the rotation speed deviation (NO-N) and the rotation speed deviation (NO-N) is, for example, as shown in FIG.
It is determined that as O) becomes larger, drive time data P8 also becomes thicker almost proportionally.

In this way, the actuator 20 corresponds to the rotation speed deviation between the idle target rotation speed NO and the current engine rotation speed N.
driving time data P. When obtained, in step 113, the CPU 300 generates from the I Fe 203 a forward rotation speed control pulse U or a reverse rotation speed control pulse D for driving the actuator 20 in the direction corresponding to the drive mode for a time corresponding to the data Pu. let in this case,
When the drive mode is on the open side, a forward rotation speed control pulse U is generated, and when the drive mode is on the closed side, a reverse rotation speed control pulse D is generated.

As a result, the throttle valve 8 is set and controlled in a direction corresponding to the target rotational speed NO during idling, and the engine rotational speed N comes to converge to the target rotational speed NO. After this, CPU3
In step 00, the processing after step 100 is repeated again, and after a certain hold time TH has elapsed, a control pulse corresponding to the change in the rotational speed at that time is generated.

The engine rotation speed N is maintained at the target rotation speed NQ by controlling the opening degree of the throttle valve 8 corresponding to the rotation speed deviation between the target rotation speed NO and the engine rotation speed N, that is, feedback control.

In steps 114 to 117, the rotation speed N is 40O
When the opening is smaller than the rpm, control is performed to set the throttle valve opening to the reference position. The reference position is, for example,
Set the position corresponding to the throttle valve opening degree when the cooling water temperature is 10°C.

First, in step 114, the position detection switch 29
If it is on, it means that the opening degree of the throttle valve 8 is on the closing side from the reference position, so the process moves to step 115 and the drive mode of the actuator 20 is set to the opening side drive mode. and position detection switch 29
If it is off, it means that the opening degree of the throttle valve 8 is on the opening side from the reference position, so the process moves to step 116 and the drive mode of the actuator 20 is set to the closing side drive mode. Then, the process moves to step 117.

In step 117, drive time data pwo of the actuator 20 is read from the ROM 301.

[Problem that the invention seeks to solve]

In the conventional rotational speed control method as described above, for example, if the rotational speed detector 252 fails and its output signal becomes abnormal and always detects a lower rotational speed than the target rotational speed NO.
There was a problem in that the feedback control pulse in the open side drive mode continued to be output, the throttle valve opened to the mechanical upper limit of the actuator 20, and the engine rotation @N increased abnormally.

The present invention has been made in view of these points, and its purpose is to provide an idling system in which the engine speed does not rise abnormally even if a detector such as a rotation speed detector outputs an abnormal signal. The purpose is to obtain a rotation speed control device.

[Means for solving problems]

In order to achieve such an object, the present invention includes an engine rotation speed detection means for detecting the rotation speed of an internal combustion engine, an engine temperature detection means for detecting the temperature of the internal combustion engine, and a variable throttle valve opening degree during idling. An actuator to be controlled, a position detection means for detecting a predetermined reference position as a drive position of the actuator, a target rotation speed setting means for setting an idle target rotation speed in response to the detection output of the engine temperature detection means, and each detection A first control pulse for setting the throttle valve opening to a reference position in response to the detection output of the means;

a second control pulse for increasing or decreasing the throttle valve opening by a predetermined amount according to the engine speed; and an intermittent pulse for converging the engine speed at idle to the target speed after changing the throttle valve opening using the second control pulse. a control means for generating feedback control pulses and driving the actuator with each control pulse; A prohibition means for prohibiting opening side drive is provided.

[Effect]

In the present invention, when the throttle valve is on the opening side from the reference position, it is not driven to the opening side from that position;
Further, when the valve is closer to the closed side than the reference position, it is driven only up to the reference position at most.

[Embodiment] FIG. 1 shows an embodiment of an idle speed control device for an internal combustion engine according to the present invention. In FIG. 1, 4I corresponds to the rotation speed detector 25 in FIG. 2 and detects the rotation speed of the internal combustion engine, and 42 is the temperature detector 29 in FIG.
engine temperature detection means for detecting the temperature of the internal combustion engine;
Reference numeral 43 corresponds to the position detection switch 29 in FIG. 2 and detects a predetermined reference position of the plunger 23 (see FIG. 2) of the actuator 20. Reference numeral 44 corresponds to the control circuit in FIG. It is a control means for driving the actuator 20. The control means 44 includes an IFC 303, a target rotation speed setting means 441 for setting an idle target rotation speed in response to the detection output of the engine temperature detection means, and a throttle valve opening degree at a reference position in response to the detection outputs of each detection means. A first control pulse generation circuit 442 generates a first control pulse for setting the throttle valve opening, and after setting the throttle valve opening to the reference position using the control pulse shown in FIG. A second control pulse generation circuit 443 generates a second control pulse for increasing or decreasing the throttle valve by a predetermined amount, and a second control pulse generating circuit 443 generates a second control pulse to increase or decrease the throttle valve opening by a predetermined amount. An intermittent feed bank control pulse generation circuit 444 generates an intermittent feedback control pulse for convergence to the number, and when the drive position of the actuator is on the opening side of the throttle valve from the reference position after generating the second control pulse. is a prohibition means 445 that prohibits the opening side drive of the actuator.
and has.

Next, the operation of the device configured in this way is shown in Figure 1~
This will be explained using FIG. FIG. 4 is a flowchart for explaining the operation of this device, FIG. 5 is a flowchart showing details of step 111 in FIG. 4, and FIG. 6 is a flowchart showing the relationship between cooling water temperature T and target rotation speed NO. Graph showing,
Figure 7 shows the deviation between the target rotation speed No. and the engine rotation speed N (NO-
FIG. 8 is a graph showing the relationship between the control pulse width P8 and the deviation between the cooling water temperature T, 1 and the reference temperature (10° C. in this case) and the control pulse width P. It is a graph showing the relationship of T8.

The flow shown in Figure 4 is different from the flow shown in Figure 9.
Since step 123 is added, only step 123 will be explained in FIG. Step 123
In step 110, it is detected whether or not the position detection switch 29 is on, and if it is on, the throttle valve 8 is on the closing side, so the process moves to step 110, and the drive mode of the actuator 20 is set to the opening side drive mode. If the switch 29 is off, the throttle valve 8 is on the open side, so the process moves to step 122 and the drive mode of the actuator 20 is set to the hold mode.

As described above, in step 123, the opening drive on the opening side from the reference position is prohibited, so the throttle valve 8 will not open more than necessary on the opening side from the reference position, and the engine speed will not increase abnormally. do not have.

By the way, the pulse drive control process in step 113 is configured as shown in the flowchart of FIG.
0 driving is executed. That is, in step 201, the CPU 300 detects whether or not the predetermined hold time TH has been completed, and if it has not been completed, the CPU 300 repeatedly executes the processes from step 100 to step 113 shown in FIG. 4. When the completion of the predetermined hold time TH is detected, in step 202 the actuator 2
It is determined whether or not the drive mode 0 is the motor hold mode. If the drive mode is the motor hold mode, the process ' from step 100 to step 113 shown in FIG. 4 is repeatedly executed, and if not, the process moves to step 203.

In step 203, drive time data is stored in the RAM 30.
In the next step 204, the drive mode is set to the open side drive mode or the close side drive mode.

After setting the drive time data and drive mode corresponding to the change in the operating state, the CPU 300 causes the I Fe 203 to start generating a forward rotation control pulse U or a reverse rotation control pulse D corresponding to the drive mode in step 205. Then, it is detected whether the generation time of this control pulse U or D has been completed, that is, whether the driving time of the actuator 20 has reached the time corresponding to the driving time data Pw, Pwo or PWT. 4, the control pulse U or D is stopped, and in the next step 206, a predetermined hold time TH is set in the timer register, and then the drive mode is set to the hold mode as shown in step 207 in FIG. The process moves to step 100.

〔Effect of the invention〕

As explained above, the present invention sets the throttle valve opening at the reference position, increases or decreases the throttle valve opening by a predetermined amount according to the cooling water temperature using the second control pulse, and then increases or decreases the engine speed. In intermittent feedback control to converge to the target rotation speed, by prohibiting the open side drive from the reference position to the open side, even if the detection means such as the engine rotation speed detection means outputs an abnormal signal, the engine rotation speed can be maintained. This has the effect of preventing abnormal increases.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of an idling speed control device for an internal combustion engine according to the present invention, and FIG. 2 is a block diagram for explaining the general idling speed control device for an internal combustion engine.
3 is a system diagram showing a control circuit constituting the apparatus shown in FIG. 2, and FIG. 4 is a diagram showing the control circuit shown in FIG. 1. Flow chart for explaining the operation of the device shown in FIG. 2, FIG. 5 is a flow chart for explaining step 113 in FIG. 4, FIG. 6 is a graph showing the relationship between cooling water temperature and target rotation speed, Figure 7 is a graph showing the relationship between the rotation speed deviation between the target rotation speed and the engine rotation speed and the control pulse width.
The figure is a graph showing the relationship between the temperature deviation between the cooling water temperature and the reference temperature (10° C. in this case) and the control pulse width, and FIG. 9 is a flowchart for explaining the operation of the conventional device. ■・・・Piston, 2...Cylinder, 3...
Intake valve, 4...exhaust valve, 5...exhaust pipe, 6...
... Three-way catalytic converter, 7... Intake pipe, 8...
・Throttle valve, 9...Venturi, 10...
Air cleaner, 11...Float chamber 11.12...
... Main fuel passage, 13... Main air bleed, 14... Main air bleed passage, 15...
Idle port, 16... Slow air bleed passage, 17... Slow air bleed, 18... Slow adjustment screw, 19... Lever, 20...
... Actuator, 21 ... DC motor, 22
... Gear mechanism, 23 ... Plunger, 24 ...
... Idle state detection switch 24.25 ... Rotation speed detector, 26 ... Speed change switch, 27 ... Cooling water, 28 ... Temperature detector, 29 ... Position detection Switch, 30...Control circuit, 41...Engine speed detection means, 42...Engine temperature detection means, 43.
. . . Position detection means, 44 . . . Control means, 251.
...Ignition coil, 252...Interrupter, 300...
・・CPU, 301・・・ROM, 302・
・ ・ ・RAM, 303 ・・・・IFC144
1...Target rotation speed setting means, 442...First control pulse generation circuit, 443...Second control pulse generation circuit, 444...Intermittent feedback control pulse generation circuit, 445 ... Prohibited means.

Claims (1)

[Claims] An engine rotation speed detection means for detecting the rotation speed of the internal combustion engine, an engine temperature detection means for detecting the temperature of the internal combustion engine, an actuator for variable control of the throttle valve opening during idling, and a drive position of the actuator. position detection means for detecting a predetermined reference position; target rotation speed setting means for setting an idle target rotation speed in response to the detection output of the engine temperature detection means; The first step is to set the throttle valve opening.
and a second control pulse for increasing or decreasing the throttle valve opening by a predetermined amount in accordance with the engine temperature after setting the throttle valve opening to the reference position by the first control pulse. a control means for generating an intermittent feedback control pulse for converging the engine speed at idle to a target rotation speed after changing the throttle valve opening using the control pulses, and driving the actuator using the respective control pulses; and prohibiting means for prohibiting the actuator from being driven to the opening side when the driving position of the actuator is on the opening side of the throttle valve compared to the reference position after generating the second control pulse. Idle speed control device for internal combustion engines.