JP2547766B2 - Engine idle speed controller - Google Patents

Description

TECHNICAL FIELD The present invention relates to an engine idle speed control device,
In particular, the present invention relates to measures for preventing engine blow-up due to stoppage of operation of an electric load when performing load correction.

(Prior Art) Conventionally, as an idle speed control device for an engine, for example, as disclosed in Japanese Patent Laid-Open No. 58-197449, feedback control of the idle speed to a target value and operation of an electric load are performed. It is known that the load is corrected so as to increase the idle speed when the engine load increases due to.

(Problems to be Solved by the Invention) By the way, the adjustment of the idle speed is usually performed by adjusting the opening / closing of the throttle valve or the passage area of a bypass passage bypassing the throttle valve to increase / decrease the intake air amount. The feedback control of the intake air amount adjusts the idle speed to the target value. In that case, when the load of the idle speed is corrected, the intake air amount of the engine is increased by increasing the intake air amount of the engine so as to compensate for the decrease in the air density due to the decrease in atmospheric pressure when the vehicle is traveling at high altitude. The rotation speed is maintained at the target value.

However, for example, when the intake air amount is adjusted by adjusting the passage area of the intake bypass passage, there is a limit maximum air amount that can be adjusted in the operating characteristics of the passage area adjusting actuator. In contrast to the amount, if the required intake air amount during high-altitude traveling exceeds this amount, the following problems will occur. That is, when the required intake air amount exceeds the adjusted maximum air amount, feedback control is normally performed to increase the intake air amount so as to satisfy the required intake air amount. Even though the increase of the air flow rate is stopped at the time of the adjusted maximum air amount of the passage area adjustment actuator, the feedback correction amount is still increased in order to increase the intake air amount,
Be too large. As a result, when the engine load decreases due to the stoppage of the operation of the electric load, etc., the feedback correction amount of the intake air amount gradually decreases, but there is a time delay, during which the idle speed rapidly increases and There is a drawback that uplift occurs. Although the above description has been made for the case where the engine speed is up, the required air amount of the engine is the minimum because there is a minimum amount of air that can be adjusted when adjusting the idle speed by adjusting the opening of the throttle valve. When the amount of air exceeds (or falls below), the feedback correction value becomes too small, and there is a drawback that the number of revolutions suddenly decreases when the required intake air amount increases.

The present invention has been made in view of the above problems, and an object thereof is to prevent an increase or a decrease in the feedback correction amount in a situation where the required intake air amount exceeds the adjustment limit air amount of the device in idle speed control. As a result, the feedback correction amount is set to an appropriate value and the intake air amount is controlled with a time delay even when the required intake air amount returns to the range of the adjustment limit air amount described above by preventing the excessive increase or decrease. Without going, it is to prevent the engine speed from suddenly rising and suddenly decreasing.

(Means for Solving Problems) In order to achieve the above object, the solution means of the present invention adjusts the intake air amount of the engine 1 to control the idle speed to a target value as shown in FIG. In the engine idle speed control device to
A target air amount setting means 35 for setting based on a feedback correction value is provided, an air amount adjusting means 17 for adjusting the intake air amount of the engine 1, and an intake air amount for the engine 1 is the target air amount setting means 35. Air amount control means for controlling the air amount adjusting means 17 so that the target intake air amount of
36 and Furthermore, when the output of the target air amount setting means 35 is received and the target air amount of the engine 1 exceeds the adjustment limit air amount of the air amount adjusting means 17, the feedback correction value of the target air amount setting means 35 is then set. And a feedback correction value fixing means 37 for holding the value until the value reaches the range of the adjustment limit air amount.

(Operation) With the above configuration, in the present invention, the target intake air amount of the engine 1 is set to the target air amount setting means during the idle operation.
When it is set based on the feedback correction value with 35, the air amount adjusting means 17 is controlled by the air amount controlling means 36, the actual intake air amount is adjusted to this target intake air amount, and the idle speed is set to the target. Converge to a value. Further, when the engine load increases due to the operation of the electric load, etc., the target intake air amount is further set based on the load correction value, so that the intake air amount increases by that amount and the reduction of the rotation speed is prevented. To be done.

Now, for example, when the vehicle is traveling at a high altitude in a state where the load is corrected, the intake air amount required by the engine is increased to compensate for the decrease in the air density, and the air amount adjusting means 17 is provided.
The adjustment limit air amount (maximum limit value) may be exceeded.
In this case, even if the feedback correction value is increased, the intake air amount is still regulated by the adjustment limit air amount. In this situation, the feedback correction value is fixed by the fixing means.
At 37, the value is fixed at the time when the adjustment limit air amount is exceeded, and the intake air amount is controlled to the adjusted maximum air amount. Then, when the load decreases and the required intake air amount becomes equal to or less than the adjustment limit air amount, the feedback correction value decreases from the fixed value, and the intake air amount is responsive toward the target intake air amount with good responsiveness. Since the rotation speed converges, the idle rotation speed well converges to the target value, and the increase in rotation speed is prevented. that's all,
The case where the required intake air amount exceeds the adjusted maximum air amount has been described, but the same applies when the required intake air amount exceeds (falls below) the adjusted minimum air amount.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows the overall configuration of an engine idle speed control device according to the present invention, where 1 is an engine and 2 is an engine 1.
A combustion chamber 5 formed by a piston 4 slidably fitted in a cylinder 3 of the one end has one end communicating with the atmosphere and the other end opening into the combustion chamber 2 to supply intake air to the engine 1. , 6 are exhaust passages, one end of which is open to the combustion chamber 2 and the other end of which is open to the atmosphere to discharge exhaust gas. A throttle valve 7 for controlling the intake air amount is provided in the middle of the intake passage 5.
A fuel injection valve 8 for injecting and supplying fuel to the intake passage 5 downstream of the throttle valve 7 is arranged. An intake valve 9 is arranged at the opening of the intake passage 5 to the combustion chamber 2, and an exhaust valve 10 is arranged at the opening of the exhaust passage 6 to the combustion chamber 2, and the top of the combustion chamber 2 is arranged. Is provided with an ignition plug 11 for igniting the air-fuel mixture in the combustion chamber 2.

Further, a bypass passage 15 that bypasses the throttle valve 7 is provided near the throttle valve 7 of the intake passage 5, and the bypass passage 15 is provided at an intermediate portion of the bypass passage 15.
A linear solenoid valve 16 for adjusting the passage area of the bypass passage 15 is provided. By adjusting the passage area of the bypass passage 15 by the linear solenoid valve 16, the throttle valve 7 is circulated in the bypass passage 15 at the time of idle operation in which the throttle valve 7 is fully closed. An air amount adjusting means 17 is configured to adjust the intake air amount to the engine 1 by adjusting the bypass intake air amount.

Then, the linear solenoid valve 16 is
The adjustment limit air amount (adjustment maximum air amount and adjustment minimum air amount) is set in consideration of the control stability when the rotation speed is feedback-controlled to the target value. As described above, when the duty signal value to the linear solenoid valve 16 is X ₁ % (0 <X ₁ ), the adjusted minimum air amount Qmin is reached, and the bypass passage is gradually increased from this X ₁ %.
The passage area of 15 is largely controlled to increase the bypass intake amount, and the duty signal value is X ₂ (X ₁ <X ₂ <100)%
Then, the adjusted maximum air amount Qmax is reached and the limit is reached. Therefore, when the required intake air amount increases in order to compensate for the decrease in air density when traveling at high altitudes, this adjusted maximum air amount qmax
May be exceeded.

Further, in FIG. 2, 20 is an air flow sensor for measuring the intake air amount on the upstream side of the throttle valve 7 in the intake passage 5,
21 is an intake air temperature sensor that detects the temperature of intake air on the downstream side of the air flow sensor 20, 22 is an opening sensor that detects the opening of the throttle valve 7, 23 is a cooling water temperature sensor that detects the engine cooling water temperature, and 24 is A rotation speed sensor that detects the rotation speed of the engine 1 by the number of ignition pulse signals to the spark plug 11, 25
Is a power steering sensor that detects when the power steering device is operating, 26 is a cooler switch that is operated when an in-vehicle cooler is requested to operate, 27 is an electric load sensor that detects the operation of other electric loads, and 28 is the atmospheric pressure around the vehicle. Is an atmospheric pressure sensor for detecting the above, 29 is an idle switch for detecting when the throttle valve 7 is in a fully closed state (in idle operation), and the detection signals of the sensors and the switches 20 to 29 are
Each of these is input to a controller 30 having a CPU or the like inside, and the controller 30 controls the operation of each of the fuel injection valve 8 and the linear solenoid valve 16.

Next, the operation control of the linear solenoid valve 16, that is, the idle speed control by the controller 30 will be described based on the control flow of FIG.

After starting, first in step S ₁ , the feedback correction intake air amount gfb, the excessive intake air amount demand flag fqmax, and the excessive intake air demand flag fqmin are all initialized to zero values, and then the cooling water temperature sensor 23 is operated in step S _2. The engine cooling water temperature θw is read, and the target intake air amount Gb during idle operation according to the engine cooling water temperature θw is determined and the target idle speed No is determined in steps S ₃ and S ₄ .

Thereafter, in step S ₅ , the engine speed n from the speed sensor 24 is read and the opening state of the throttle valve 7 from the idle switch 29 is grasped, and then in step S ₆ , the engine speed and the throttle valve 7 are detected. based on the opening state it is determined whether or not the idle operation of the engine 1, at the time of idling operation, while feedback controlling the idle speed in step S ₇ and subsequent, if not idling at step S ₁₂ the value of the feedback correction air quantity gfb set to zero value, the process immediately proceeds to step S _13. Then, when performing feedback control of the rotational speed, first step S ₇ above the actual engine speed n at Step S ₄
The comparison with the target idle rotational speed No, if low n-No <0 is the possible to increase adjusting a feedback correction amount of intake air gfb, when an excessive amount of intake air demand flag in step S ₈ FQM
to determine the value of ax, to if not at required excessive intake of fqmax = 0 (the case of YES), a minute amount fdgfb corresponding to the rotational speed deviation (No-n) in step S ₉ (No-n ) Is added to the feedback correction intake air amount gfb to increase the value gfb. On the other hand, if the high n-No> 0 in step S _7,
And reducing adjust the feedback correction air quantity gfb, to determine the value of under-air amounts demand flag Fqmin in step S _10, in a case not when requested under-intake amount of fqmin = 0 (the case of YES), rotation speed deviation in step S ₁₁ (n-
The small amount fdgfb (n-No) corresponding to No.) is subtracted from the feedback correction intake air amount gfb to reduce the value gfb. Also, if it matches the n-No = 0 at step S _7, the process immediately proceeds to step S ₁₃ without changing the feedback correction air quantity gfb.

Then, by adding the feedback correction air quantity gfb the intake air amount Gb of idling determined at Step S ₃ in step S _13, which was the intake air mass ga, then load correction according to the electric load In step S ₁₄ , S ₁₅ , and S ₁₆ , the power steering is operating,
During operation of the vehicle cooler, and determines whether or not the operation of other electrical loads, when in the power steering operation, adds the power steering correction intake air amount Gpst above intake air mass ga at Step S ₁₇ with, if during operation of the vehicle cooler, the cooler correction intake air amount gcol added in step S _18, in during the operation of other electrical loads, adds the electrical load correction intake air amount gel in step S _19.

Then, in step S ₂₀ , the intake air temperature θa from the intake air temperature sensor 21 and the atmospheric pressure Patp from the atmospheric pressure sensor 28 are read, respectively, and in step S ₂₁ , the target volume flow rate q of the intake air is read.
Is the intake air mass ga, intake air temperature θa, and atmospheric pressure P
Atp function q = fg-q (ga, θa, Patp) is calculated by performing air density correction.

Thereafter, adjusted minimum air quantity Qmi of steps S ₂₂ and S ₂₃ in the suction air of the target volumetric flow q each linear solenoid valve 16
n and the adjusted maximum air amount Qmax, and in the case of an under intake air amount demand of Q ≦ Qmin, the target volume flow rate q of the intake air is corrected to the adjusted minimum air amount Qmin in step S ₂₄ , and
The excessive intake air amount request flag fqmin is set to a "1" value, and the excessive intake air amount request flag fqmax is set to a "0" value. On the contrary, Q ≧ Qmax
If at the time an excessive intake air amount request is configured to modify the target volumetric flow q of the intake air in step S ₂₅ to adjust the maximum amount of air Qmax, and the "1" value excessive intake air quantity demand flag Fqmax, under-intake air amount The request flag fqmin is set to "0" value. Also, Qm
If it is within the adjustable range of in <Q <Qmax, step S
_{At 26} , the target volumetric flow rate q of intake air is not modified, and fqmax
= 0 and fqmin = 0.

The above as after setting a target volumetric flow q of the intake air finally in step S _27, bypass intake air quantity of the bypass passage 15 is linear solenoid valve with a duty ratio signal value becomes the target volumetric flow q The operation of 16 is controlled, and the process returns to step S ₂ .

And Thus, in the case of n-No <0 at step S _7, that is, in the case that requires increasing the feedback correction air quantity gfb, when an excessive amount of intake air demand flag in step S ₈ fqmax = 1
When, the required intake air amount (that is, the target volume flow rate q of the intake air) has already reached the adjusted maximum intake air amount Qmax of the linear solenoid valve 16.
The feedback correction intake air amount g
without increasing the fb, it holds the value of the intake air mass ga in step S _13.

Similarly, at step S ₇ of the n-No> 0, even if that requires reduction of the feedback correction air quantity gfb, Step S ₁₀
In the case of under-air amounts demand flag fqmin = 1, since already required intake air quantity q is in situations below the adjusted minimum intake air amount Qmin, without loss of the feedback correction air quantity gfb, the intake air in step S ₁₃ The value of mass ga is kept as it is.

Therefore, in the control flow of FIG.
The target bypass intake air amount (volume flow rate) of the bypass passage 15 that is added to the target intake air amount of the engine 1, that is, the constant intake air amount through the throttle valve 7 by S _{1 to} S ₇ , S ₉ , and S _{11 to} S _21. q) is calculated based on the feedback correction value gfb, the load correction values Gpst, Gcol, Gel, and the volume flow rate correction value fg-q (ga, θa, Patp) according to the intake air temperature θa and the atmospheric pressure Patp. The target air amount setting means 35 described above is configured.

Further, from the step S ₂₇ in the figure, the linear solenoid valve 16 to duty control, the bypass intake air quantity communicating the bypass passage 15 so as to control the target bypass intake air quantity q of the target air amount setting means 35 air amount It constitutes the control means 36. Further, in step _{S 8, S 10, S 22} ~S 25, adjustment limit air quantity Qmax of the target bypass intake air quantity q is the linear solenoid valve 16 of the bypass passage 15, when it exceeds qmin, the target air amount setting means 35 The feedback correction intake air amount gfb of is fixed to the value at that time, and this value is thereafter set to the target bypass intake air amount q.
The feedback correction value fixing means 37 is held until is within the range of the adjustment limit air amount Qmax, qmin.
Is composed.

Therefore, in the above-described embodiment, during the idling operation, after the feedback correction intake air amount gfb is adjusted according to the deviation between the actual engine speed n and the target idle speed No, the intake air containing the correction intake air amount gfb is adjusted. When the mass ga is corrected by the air density with the intake air temperature θa and the atmospheric pressure Patp and is set as the target bypass intake air amount q of the bypass passage 15 by the target air amount setting means 35, thereafter, the air amount control means 36.
Thus, the operation of the linear solenoid valve 16 of the air amount adjusting means 17 is controlled, and the bypass intake air amount of the bypass passage 15 is adjusted to the target bypass intake air amount q.

In addition, when the engine load increases due to the operation of the vehicle-mounted cooler during idle operation, for example, the cooler-corrected intake air amount gco
l is added to the intake air mass ga, and the target bypass intake air amount q is increased by that amount. Along with this, the passage area of the bypass passage 15 is also enlarged and adjusted by the linear solenoid valve 16, and the bypass intake air amount is set to the target intake air amount ga. The bypass intake air amount q is controlled.

Now, in the above-mentioned load correction state, when the vehicle is traveling at high altitude, for example, the volume flow rate q corresponding to the intake air mass ga is compensated so as to compensate for the decrease in air density due to the decrease in atmospheric pressure Patp. , Fg-q (ga, θa, Patp) (volume flow rate correction value) is calculated and increased, and this volume flow rate q may exceed the adjusted maximum air amount Qmax of the linear solenoid valve 16.

However, in that case, even if feedback control of the bypass intake air amount is performed, the adjusted maximum air amount of the linear solenoid valve 16
Since the value does not exceed Qmax, the value of the feedback correction intake air amount gfb is fixed by the feedback correction value fixing means 37 within the range where it exceeds the value, and the value at the time when the value is exceeded is prevented, so that it is prevented from becoming excessive. As a result, while maintaining the maximum controllable intake air amount (bypass intake air amount Qmax) within this range, the engine load decreases after the in-vehicle cooler is stopped and the target bypass intake air amount q becomes a linear solenoid valve. When the adjusted maximum air amount Qmax of 16 or less is reached, the linear solenoid valve 16 is feedback-controlled by the feedback-corrected intake air amount gfb of the fixed appropriate value, and the bypass intake air amount is quickly adjusted to the target bypass intake air amount q. become. Therefore, when the atmospheric pressure decreases, such as when traveling at a high value, it is possible to prevent the feedback correction intake air amount gfb from becoming excessive during idle speed control, and to effectively prevent the idle speed from rising when the engine load decreases.

The case where the target bypass intake air amount q exceeds the adjusted maximum air amount Qmax of the linear solenoid valve 16 has been described above, but the same applies to the case where the target bypass intake air amount q falls below the adjusted minimum air amount Qmin.

In the above embodiment, the air amount adjusting means 17 that adjusts the bypass intake air amount is used, but it may also be configured by adjusting the opening degree of the throttle valve 7.

(Effects of the Invention) As described above, according to the idle speed control device for an engine of the present invention, during idle operation, when the intake air amount required by the engine exceeds the adjustment limit air amount of the device, and when the atmospheric pressure decreases. In such a case, the feedback correction value is fixed to the value at the time when it exceeds this range to prevent it from becoming too large or too small, so that the required intake air amount is then within the adjustment limit air amount range. If it enters into, it is possible to quickly adjust the intake air amount to the target intake air amount with an appropriate value of the feedback correction value, prevent the engine speed from rising and sudden decrease, and improve the control accuracy of the idle speed. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 4 show an embodiment of the present invention, FIG. 2 is an overall schematic configuration diagram, FIG. 3 is a flow chart diagram showing the operation of the controller, and FIG. 4 is a diagram showing the operation characteristics of the linear solenoid valve. Is. 1 ... Engine, 15 ... Bypass passage, 16 ... Linear solenoid valve, 17 ... Air amount adjusting means, 30 ... Controller, 35
...... Target air amount setting means, 36 ...... Air amount control means, 37 ...
... Feedback correction value fixing means.

Continuation of the front page (56) Reference JP 58-170839 (JP, A) JP 55-101740 (JP, A) JP 59-26782 (JP, B2) JP 60-38544 (JP , B2) JP-B-61-23377 (JP, B2) JP-B-63-15461 (JP, B2)

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. An engine idle speed control device for adjusting an intake air amount of an engine to control an idle speed to a target value, wherein a target air amount of the engine is set based on a feedback correction value. Quantity setting means, air quantity adjusting means for adjusting the intake air quantity of the engine, and air for controlling the air quantity adjusting means so that the intake air quantity of the engine becomes the target intake air quantity of the target air quantity setting means. When the target air amount of the engine exceeds the adjustment limit air amount of the air amount adjusting means and the output of the target air amount setting means is received, the feedback correction value of the target air amount setting means is provided. Is fixed to the value at that time, and thereafter, it is provided with a feedback correction value fixing means for holding the value until it is within the range of the adjustment limit air amount. Idling speed control system for engine.