JPS59200035A - Idling speed contol device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To simplify a device in structure as well as to reduce the cost of production, by performing both of idling speed feedback control and throttle valve control in an internal-combustion engine with one control device in time of deceleration. CONSTITUTION:An actuator 20 consisting of a motor 31 and a gearing mechanism 22 is installed in a throttle valve 8 of a suction pipe 7 inside an internal-combustion engine and is controlled by a control circuit 30. When this control circuit 30 judges that an engine is in a state of being idled by means of signals out of an engine speed detector 25 and a transmission switch 29, it performs feedback control on the basis of a deflection between an idling speed desired value and a state of an operation start switch 28, that is, an actual engine speed signal being set according to the load. In addition, when the engine speed is more than the specified value and an idle switch is 24 is turned to ON, the control circuit 30 judges it being in a state of deceleration, controlling the throttle valve into minimum opening and intercepting useless fuel, and prevents a ternary catalyzer from overheating. A fact that two functions aforesaid are controlled with one control circuit 30 and one actuator each alone nows comes to fruition, so that simplification in a device and a reduction in production cost both are thus attainable.

Description

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

[Prior art]

In automobiles, the engine speed at idle is compared with the target idle speed, and the throttle valve opening is changed according to the deviation to control the engine speed to the target speed). Some models are equipped with an idle speed control device designed to reduce the number of idle revolutions.

By the way, in a car, when the accelerator pedal is released and the vehicle decelerates to transition from a high-speed driving state to a low-speed driving state, the engine side is driven from the vehicle width side, but at this time the throttle valve opening is different from that of the vehicle when the vehicle is stopped. Since the opening is the same as when the throttle valve is idling, a constant amount of fuel is still supplied from the upstream side of the throttle valve. Therefore, if such deceleration driving continues and is repeated, the fuel supplied to the engine combustion chamber becomes slightly excessive, causing incomplete combustion, and the incomplete combustion gas is combusted in the three-way catalyst. This causes a problem in that the temperature of the three-way catalyst rises abnormally, eventually destroying its function.

However, when it comes to air-fuel ratio control during deceleration, conventional idle speed control devices do not control the air-fuel ratio, and even though the same throttle valve opening is controlled, a dedicated control device for deceleration It was controlled. This has resulted in problems such as the complexity of the engine control system and increased costs.

[Summary of the invention]

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide an inexpensive configuration, set the engine speed at idle to a target speed, and prevent abnormal increase in the three-way catalyst during deceleration. An object of the present invention is to provide an idle speed control device for an internal combustion engine that can also prevent overheating.

To this end, the present invention provides an actuator that variably controls the throttle valve opening, and drives the actuator so that the engine speed converges to the target rotational speed during idling, and the throttle valve opening reaches the minimum opening during deceleration. The actuator is configured to drive the actuator as follows.

[Embodiments of the invention]

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the same figure, the configuration of the engine side will be explained first: (1)
is the piston, (2) is the cylinder, and (3) is the intake valve.

(4) is the exhaust valve, (5) is the exhaust pipe, (6) is the three-way catalytic converter, (7) is the intake pipe, (8) is the throttle valve, and the upstream side of the throttle valve (8) is the Venturi (
9) and an air cleaner (10) are provided, and the fuel in the float chamber (11) is sucked through the main fuel passage (12) when the intake air sucked through the air cleaner (10) passes through the venturi (9). The air is atomized, becomes a mixture with intake air, and is introduced 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 (14) provided upstream of the venturi (9). ) is atomized in advance and then atomized.

On the other hand, there is an idle bow on the downstream side of the throttle valve (8).
(15) is provided, and a slow air bleed passage (16) is provided upstream of the venturi (9), and the fuel in the main fuel passage (12) is fed to the intake air from this slow air bleed passage (16). Yo Shislow Air Bleed (
17), it is finely divided and discharged from the idle port (15). As a result, fuel is secured during idling when the throttle valve (8) is approximately fully closed. In this case, the amount of fuel discharged from the idle port (15) is adjusted by the slow adjustment screw (18).

Here, the throttle valve (8) is connected to an accelerator pedal (not shown), and while driving the throttle valve (8) opens according to the amount of depression of the accelerator pedal, and when the accelerator pedal is released and is idling, the throttle valve (8) is in an idling operating state. This is the opening degree necessary to maintain this. Further, this throttle valve (8) is provided with a lever (19) on its rotating shaft.
) is moved by an actuator (20), which will be described later, to vary the opening degree at idle.

Next, to explain the configuration of the idle rotation speed control system, (20) consists of a DC motor (21) and a gear mechanism (22), and the rotational movement of the DC motor (21) is controlled by the gear mechanism (20).
22), change the plunger (23) to linear motion,
An actuator that drives the lever (19) by this linear movement to vary the opening degree of the throttle valve (8);
A forward rotation control pulse U and a reverse rotation control pulse D having a predetermined pulse width are applied to the DC motor (21) from a control circuit (30). In this case, the actuator (20) contains an idle state detection switch (24) that is turned on (closed) when the tip of the plunger (23) is in drawing contact with the lever (19), that is, when the accelerator pedal is released and the accelerator pedal is released. )
is provided.

Next, (25) is a rotation speed detector that detects the engine rotation speed, and here, a rotation pulse with a period corresponding to the engine rotation speed N is generated from the connection point between the ignition coil (26) and the interrupter (27). Taking out the signal. (28) is the operation start switch for the air conditioner (hereinafter referred to as A/C-8W), which is one of the engine loads.
), (29) indicates that the transmission (not shown) is in the neutral position or that the clutch (not shown) is on (
(30) is an idle switch (24) that detects the idle state, and a rotation speed detector (24).
5), A/C-5W (28), speed change switch (2
Control that controls the throttle valve opening during idling and deceleration based on the output signals of 9) and the position detection switch (31), converges the engine speed to the target rotation speed NQ, and controls the air-fuel ratio during deceleration. It is a circuit.

As shown in FIG. 2, the control circuit (30) includes an arithmetic processing unit (hereinafter abbreviated as CPU) (300) and a read-only memory (hereinafter referred to as "CPU") that stores programs and constants for controlling the idle rotation speed. (abbreviated as ROM) (301), a random access memory (hereinafter abbreviated as RAM) (302) that stores results during calculations, etc., and an interface circuit for transmitting and receiving signals between the various switches and actuators (20) mentioned above. (hereinafter abbreviated as NFC) (aOa)
It is composed of.

Next, the operation of the above configuration will be explained using the 70-ch and yard shown in FIGS. 3 and 4.

First, when the engine is started, the CPU (300) stores the ROM (
301), the process is executed as shown in FIG. That is, the CPU (300) receives the output signal from the rotation detector (27) and measures the period of the signal to detect the current engine rotation speed N (step 100), and then detects the target rotation speed at idle. A number NQ is calculated (step 101). The target rotational speed NQ during idling is set differently depending on when the air conditioner is in the operating state and in the non-operating state, for example, as shown in Table 1.

Table 1 And this idle target rotation speed NO is stored in the ROM (301
) is stored in advance as a constant. Therefore, calculation of the idle target rotation speed No. is realized by reading the above constant from the ROM (301).

Next, crty (300) has an engine speed N of 40OR.
It is determined in steps (102) and (103) whether or not the idle rotation speed is within the control target range of PM to 1500 RPM, and if it is not within the control target range, step (11) is performed.
In step 4), the drive mode of the actuator (20) is set to the hold mode, and no idle rotational speed control is performed on the actuator (20) K. However, if the engine speed N is within the control target range of 40 ORPM to 1500 RPM, whether the engine speed N has changed from 150 ORPM or more to 150 ORPM or less in step (104) has changed to the range of 40 ORPM to 1500 RPM. is detected, and if the speed has not changed from 1500 RPM or more to 1500 RPM or less, the next step (105) is to check whether the gear change switch (29) is on, that is, whether the gearbox is in the neutral position or whether the clutch is on. After determining whether the idle switch (24) is on based on the output signal of the speed change switch (29), in the next step (106) it is determined whether the idle switch (24) is on. As a result, if the gear shift switch (29) is turned on, it is assumed that it is in the running state, and the drive mode is set to the hold mode in step (114), and even if the gear shift switch (29) is turned off, it is assumed that the drive mode is set to the hold mode. When the switch (24) is off, it is assumed that the driver is operating the accelerator pedal, and step (114)
In both cases, the drive mode is set to the hold mode, and idle rotation speed control for the actuator (20) is not performed in either case.

However, if the gear shift switch (29) is on (neutral state or clutch on state) and the idle switch (24) is on, the main fuel for the engine is supplied from the idle port (15), i.e. Assuming that it is in an idle state, in the next step (107) it is determined whether the A/C-SW (28) has changed from on to off or from off to on. As a result,
If there is no change in the state of A/c-sw (28), the idle target rotation speed No.
and the current engine speed N (absolute value), and further detects whether the deviation is larger than a predetermined value ΔNn,
If the deviation is smaller than AND, the drive mode of the actuator (20) is set to the hold mode in step (114). However, if the deviation is larger than the predetermined value ΔND, an idle speed control process is performed to converge the engine speed N to the target speed NO in steps (109) to (113) below.

That is, in step (109), the current engine speed N is compared with the target engine speed No. If No>N, it is necessary to control the opening of the throttle valve (8) to the open side. Step 11o) to set the drive mode of the actuator (2o) to the opening mode, since it is necessary to control the opening of the throttle valve (8) to the closing side (step 11o). Set to the close mode (step 111).After this, in step (112), the deviation between NQ and N (No-N) is determined.
Drive time data P of the actuator (20) corresponding to
Read w from ROM (301). The relationship between the drive time data FW and the deviation (No-N) is, for example, as shown in FIG. A relationship is established in which as -1(N-No) increases, the driving time data Pw also increases almost proportionally.

In this way, when the drive time data Pw of the actuator (20) corresponding to the deviation between the idle target rotation speed No. and the current engine rotation speed N is obtained, the CPU (300) in step (113) The IFC (303) generates a forward rotation control pulse U or a reverse rotation control pulse D for driving the actuator (20) in a direction corresponding to the drive mode for a time corresponding to PW.

In this case, when the drive mode is on the open side, a forward rotation control pulse U is generated, and on the other hand, when the drive mode is on the close side, a reverse rotation control pulse D is generated.

As a result, the throttle valve (8) is set and controlled in a direction corresponding to the target engine speed N during idling, and the engine speed N
comes to converge to the target rotational speed NQ. After this, CP
U (aoo) repeats the process after step (100) again, and after a certain hold time TH has elapsed, generates a control pulse corresponding to the change in the rotational speed at that time.

The engine rotation speed N is maintained at the target rotation speed NQ by controlling the opening of the throttle valve (8) corresponding to the deviation between the target rotation speed NQ and the engine rotation speed N, that is, by feedback control. 'lHowever,
When the A/C-8W (28) changes from on to off and from off to on, the CPU (300) detects the change in step (107). Furthermore, it is detected in step (115) whether or not this i-ization is a change from on to off of the A/C-sw (28), and if it is a change to the on state, the drive mode of the actuator (20) is opened. If the change is to the OFF state, the closing side sliding mode is set (Step 117). Then, in the next step (118), the drive time data pi' of the actuator (20) corresponding to the expected load fluctuation is calculated by anticipating the rotational speed fluctuation due to an increase or decrease in the engine load due to the start or stop of operation of the air conditioner. Read rAc from ROM (301). After this, in step (113), the data pwA
Forward rotation control pulse U or reverse rotation control pulse D f: IFC (303
).

As a result, the opening degree of the throttle valve (8) will be the same as the opening degree corresponding to the drive time data p wAc when the air conditioner starts operating, and conversely, the opening degree corresponding to the drive time data P WAG when the air conditioner stops operating.
Closes only to the opening degree corresponding to.

After performing such prospective control, CPtJ (300) performs the feed/
(The engine idle speed is converged to the target speed NO by the control.

In this case, the pulse drive control process in step (113) is configured as shown in the flowchart of FIG. 4, and the actuator (20) is driven after waiting for the completion of the predetermined hold time TH.

That is, the CPU (300) detects whether or not the predetermined hold time TH has been completed in step (201), and if it has not been completed, the CPU (300) executes step (100) in FIG.
The processes from to (113) are repeatedly executed. and,
When the completion of the predetermined hold time TH is detected, the drive mode of the actuator (20) is set to the opening side or the closing side mode in step (202), and then the third drive mode is set.
The driving time data PW or P WAO determined in step (112) or (118) in the figure is transferred to step (203).
) is set in the timer register in the RAM (302), and the IFC (303) starts generating the forward rotation control pulse U or reverse rotation control pulse D corresponding to the drive mode. Then, in the next step (204), it is determined whether the generation time of this control pulse U or D has been completed, that is, whether the driving time of the actuator (2o) has reached the time corresponding to the driving time data pwitakeP FIAC. is detected, and when the control pulse U is reached, the control pulse U is
Alternatively, the generation of D is stopped, and in the next step (205), a predetermined hold time TH is set in the timer register, the drive mode is set to hold mode, and the process moves to step (100) in FIG. This results in
During idle rotation speed control by feedback control, the actuator (20) is operated for a predetermined hold time T.
If the engine is operated intermittently by a control pulse having a rest time of H, the engine rotation speed N is converged to the target rotation speed NQ.

FIG. 6 shows a time chart of the forward rotation control pulse U and the reverse rotation control pulse D when the A/C-SW (2B) changes from OFF to ON, for example.

On the other hand, when the air conditioner starts operating, the engine speed N increases to 1500 I? , if there is a sudden drop from more than PM to less than this, the CPU (300) will process this in step (10
When detected in step 4), predetermined drive time data P1vO is set in the timer register in step (119), the drive mode is set to the open side mode in the next step (120), and the actuator is activated in step (113). (20) is driven in a direction that increases the opening degree of the throttle valve (8) for a time corresponding to time data PWO. This prevents engine rotation from stopping when the air conditioner starts operating.

On the other hand, if the engine speed N is 150 ORPM or more, CP
When U (300) detects this in step (103), it detects in step (121) whether or not the idle switch (24) is on, and if it is on, it means that the vehicle is decelerating. Throttle valve (8
) is set to the minimum opening (for example, fully closed) determined by a throttle valve opening adjusting screw or the like. However, idol
,.

If the switch (24) is in the OFF state, it means that the vehicle is running at high speed, so the drive mode is set to the hold mode and the actuator (20) is not driven at all.

FIG. 7 is a flowchart showing detailed processing contents of step (121), in which the CPU (300)
At Step 250), it is detected whether or not the current engine speed N has suddenly increased from 1500 RPM or less to 150 ORPM or higher.
), it is detected whether the idle switch (24) is on or not. If it is not on, it means that the vehicle is running at high speed, so in step (252) the frl Ql mode is set to the hold mode. .

However, in an operating state in which the engine speed N does not rise rapidly but the idle switch (24) is in the on state, that is, at wave speed, the CPU (300) executes step (2).
After setting the predetermined drive time data PWI in the timer register in step Q53), the Pg and dynamic mode are set to the closing side mode in the subsequent step Q54), and the actuator (20) is set to the throttle valve in the next step (255). The above time data P
Drives only for a time corresponding to WI. After that, if the detection results in steps (250) and (251) in FIG. 7 are the same as before after going through steps (100) to (103) in the flowchart in FIG.
255) is executed. Through this repeated process, the opening degree of the throttle valve (8) finally reaches the fully closed state, but at this time, the lever (19) of the throttle valve (8) and the tip of the granger (23) are still in contact and the idling state is reached. The switch (24) is in the on state. For this reason, C.P.
U (300) further executes steps (253) to (255), but after the throttle valve (8) is fully closed, the lever (19) does not move and the plunger (23)
) only moves to the right in FIG. 1, and the contact relationship with the lever (19) is severed. This allows the idle switch (
24) is turned off. Then, cpu (300)
is determined in step (252) by the judgment in step (251).
) and set the drive mode to hold mode.

This causes the plunger (23) to connect to the throttle valve (8).
It stops at the position where it is fully closed. As a result, fuel from the upstream side of the throttle valve (8) is completely cut off, incomplete combustion gas is controlled, and abnormal temperature rise of the three-way catalytic converter (6) can be prevented. .

In this case, the processes of steps (253) to (254) are executed only once even when the engine speed N changes from 150 ORPM or less to 150 ORPM or more. This is executed in anticipation of the fact that the vehicle will eventually start decelerating. This results in
The opening degree of the throttle valve (8) can be quickly brought to a fully closed state when decelerating travel begins.

In addition, by setting the throttle valve opening to the fully open state,
If the engine speed N suddenly decreases from more than 150 ORPM to less than 150 ORPM, follow steps (119) to (12) in Figure 3.
0) is executed, and a situation where the engine rotation stops is prevented.

FIG. 8 shows a time chart of the output signal ID of the idle switch (24), the position PP of the plunger (23), and the control pulse D when deceleration running is repeated after the engine speed N changes from less than 150 ORPM to more than 150 ORPM. It shows.

As described above, according to this embodiment, the engine speed during idling can be controlled to the target speed, and the air-fuel ratio during deceleration can be controlled to an optimal value. Furthermore, since the control function during deceleration is realized using the software for controlling the idle rotation speed, the configuration of the entire control system can be simplified and costs can be reduced.

In the embodiment, the throttle valve opening was set to the fully closed state during deceleration, but when the throttle valve opening reached, for example, about 2 degrees, the contact relationship 2 between the lever (19) and the plunger (23) was severed. A locking mechanism may be provided for the lever (19) so that the lever (19) is sagging, and the throttle valve opening degree during deceleration may be set to an opening degree corresponding to the allowable temperature of the three-way catalyst of about 2 degrees.

〔Effect of the invention〕

As explained above, the present invention is provided with an actuator that variably controls the throttle valve opening, and when idling, the actuator is driven so that the engine rotation speed converges to the target rotation speed, and when decelerating, the throttle valve opening is set to the minimum opening. The actuator is configured to drive the actuator at the same time.

Therefore, the idle speed can be controlled with an inexpensive configuration.
1", it is also possible to prevent abnormal temperature rise of the three-way catalyst during deceleration, and it is possible to improve fuel efficiency and extend the service life of the three-way catalyst.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing the detailed structure of the control circuit, Figs. 3 and 4 are flow charts showing the operation contents of the control circuit, and Fig. 5 is a block diagram showing the detailed structure of the control circuit. A graph showing an example of the drive time of the actuator with respect to the deviation between the target rotation speed and the engine rotation speed, Fig. 6 is a time chart showing an example of the control pulse generated at the start of operation of the air conditioner, and Fig. 7 is during deceleration. FIG. 8 is a time chart showing the relationship between changes in rotational speed during deceleration and changes in actuator jump position. (1)...Piston, (2)...Cylinder, (
3)...Intake valve, (6)...Three-way catalytic converter, (7)...Intake 'fl, (8)...Throttle valve, (9)...Penchu ! J, (10)...
・Air cleaner, (11)...Float chamber, (19)
)... Lever, (20)... Actuator,
(21)...DC motor, (22)...Gear mechanism, (23) F...Plunger, (24)...
Idle switch, (25)...Rotation speed detector, (
28)...A/C-SW, (4)...speed change switch, (30)...control circuit, (300)...
...Arithmetic processing unit, (301) ...Read-only memory, (302) ...Fist/random access memory, (303)...Fist/interface circuit. Agent Masuo Oiwa jz
Law 1 CL Q Procedural amendment band (spontaneous) August 2, 1981 Mr. Commissioner of the Japan Patent Office 1, Case description Japanese Patent Application No. 58-74347 2, Title of invention Internal combustion engine idle speed control device 3, amendment 4. Agent 5, Column 6 of the detailed description of the invention in the specification to be amended, contents of the amendment Changed ``Along with the start of operation, etc.'' to ``Along with a change in the operating condition.'' and correct it. (Delete "suddenly" in line 19 of page 16 of the same book for the 21st time. (4) In the same book, page 17, lines 2-3, there has been a sudden drop in engine speed.
Delete. (5) In the fourth line of the same page of the same book, “unless there is a sharp rise” is r.
``If the speed continues to be 1500 RPM or higher,'' the correction is made. (6) In the 9th line of the same page of the same book, amend the phrase ``although it is not a rapid increase in '' to ``at 150 ORPM or more.'' (Power) In the same book, page 19, line 6, ``full-open state'' is changed to ``full-open state''.
and correct it. that's all

Claims (1)

[Claims] A rotation speed detection means for detecting the rotation speed of an internal combustion engine having a catalytic converter in an exhaust passage, a target rotation speed setting means for setting an idle target rotation speed, and an actuator for variably controlling the opening degree of a throttle valve during idle. Feedback control means receives the detection outputs of the rotation speed detection means and the target rotation speed setting means and drives the actuator so that the engine rotation speed during idling converges to the target rotation speed;
An idling speed control device for an internal combustion engine, comprising: control means for driving the actuator so that the opening degree of the throttle valve becomes a minimum opening degree when the engine is decelerated.