JP2685104B2 - Engine idle speed control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine idle speed control device for performing feedback control of an engine speed to a target value by adjusting an intake air amount in an idle operation region or the like.

(Prior Art) Conventionally, as an engine idle speed control device, for example, as disclosed in Japanese Patent Publication No. 59-18124, a bypass passage for bypassing a throttle valve of an intake passage is provided, and a first passage is provided in the bypass passage. And a second valve are provided in parallel, and the second valve is configured by a temperature sensitive valve whose opening degree increases as the engine cooling water temperature becomes lower, and the throttle valve is substantially closed in an idle operation range. While the engine speed is feedback-controlled to the target value by the first valve, the opening degree of the second valve is controlled during warm-up operation from a cryogenic start where the cooling water temperature is low and fuel vaporization and atomization are poor. The increase prevents the feedback correction amount of the first valve from becoming excessive and secures its controllability, and also increases the intake air amount to obtain a sufficient air-fuel mixture amount to improve the low temperature startability. Those in so that is known.

(Problems to be Solved by the Invention) By the way, in such an idle speed control device,
The second valve is, for example, a wax type temperature sensitive valve, and engine cooling water is supplied from the water jacket to the temperature sensitive valve. In that case, (1) there is a temperature difference between the cooling water in the water jacket and the cooling water supplied to the temperature sensing valve, and (2) the wax of the temperature sensing valve with respect to the rising speed of the cooling water temperature in the water jacket. As shown in Fig. 7, there is a delay in response to the opening / closing operation of the temperature sensitive valve when the temperature of the cooling water rises during warming up from a very low temperature start, etc. Occasionally, there is a delay in closing.

That is, since the temperature-sensing valve tends to open due to this delay in closing, the first valve is feedback-controlled in the closing direction by a considerable amount in order to bring the engine speed to the target value, as compared with the warm time. . When the engine moves out of the idle operation region and shifts from the feedback zone to the open zone in such a case, the feedback correction amount is not input to the first valve, and the first valve is fixed to the opening degree according to the basic value. Will be done. That is, there is a problem in that the opening of the first valve suddenly increases due to the disappearance of this feedback correction amount, and the engine speed suddenly increases, which causes discomfort or discomfort.

Further, in the warm-up operation from such a cryogenic start, contrary to the above, in the case where the engine enters the idle operation area from the operation area other than idle and shifts from the open zone to the feedback zone, The feedback correction amount in the closing direction is suddenly returned to the first valve and is input, the opening of the first valve is suddenly reduced, the engine is dropped, and the engine stalls.
The problem is the same as above.

The present invention has been made paying attention to such a point, and an object of the present invention is to provide an open zone and a feedback zone when the intake air temperature is low such as during warm-up operation from cryogenic start. It is to reduce the fluctuation of the intake air amount during the transition.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the engine speed is fed back to a target value by the intake air temperature adjusting means such as the first valve described above in a predetermined operating region such as an idle operating region. With control, the lower the intake air temperature,
The correction is to reduce the intake air amount adjusted by the intake air amount adjusting means.

Specifically, the solution taken by the invention of claim 1 is the first solution.
As shown in the figure, intake air amount adjusting means 13 for adjusting the intake air amount of the engine, and rotation speed detecting means for detecting the engine rotation speed
37, a feedback control means 41 which receives the output of the rotation speed detection means 37 and feedback-controls the intake air amount adjustment means 13 so that the engine speed becomes a target value in a predetermined operation region, and a throttle valve in the intake passage is bypassed. A bypass passage for supplying intake air to the engine and a temperature sensitive valve provided in the bypass passage for opening and closing so that the opening degree increases as the engine temperature becomes lower based on a signal related to the engine temperature. Further, the intake air temperature detecting means 32 for detecting the intake air temperature of the engine, and the intake air temperature detecting means 32
And a correction means 42 for reducing and correcting the target value of the feedback control means 41 so that the intake air amount that the intake air amount adjusting means 13 bears becomes smaller as the intake air temperature becomes lower.

Here, in the invention of claim 2, as a specific example of the opening / closing operation of the temperature-sensitive valve in the above-mentioned claim 1, the opening degree of the temperature-sensitive valve at a predetermined engine temperature is lower when operating from a cryogenic start. It is assumed that the temperature sensing valve is set to have a larger amount of air than when it is operated from the start.

(Operation) With the above configuration, in the inventions of claims 1 and 2, the rotation speed detection means is provided in a predetermined operation region such as an idle operation region.
The intake air amount adjusting means 13 is controlled by the feedback control means 41 based on the rotation speed detected at 37, and the engine speed is feedback-controlled to the target value.

In addition, when the engine temperature is low and fuel vaporization / atomization is poor, such as during warm-up operation from a cryogenic start, the opening of the temperature sensing valve increases and the amount of intake air from the bypass passage increases. The feedback control amount of the amount adjusting means 13 is prevented from becoming excessive and its controllability is secured, and the overall intake amount is secured to be increased, and a sufficient air-fuel mixture amount is obtained and the cryogenic startability is improved. .

In that case, since the response of the operation of the temperature sensing valve is delayed with respect to the rise of the engine temperature and there is a closing delay, the intake air amount adjusting means 13 sets the intake air amount more than the warm time in order to set the engine speed to the target value. Feedback control is performed in the direction in which

However, based on the intake air temperature detected by the intake air temperature detecting means 32, the amount of intake air that the intake air amount adjusting means 13 bears is corrected by the correction of the correcting means 42 so that the lower the intake air temperature is, the more the feedback correction amount. Has become a small feedback zone and open
Fluctuation of intake air at the time of transition with the zone is reduced,
Sudden fluctuations in engine speed are suppressed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows an engine provided with an idle speed control device according to an embodiment of the present invention. Reference numeral 1 denotes an engine, a cylinder 2 is formed in the engine 1, a piston 3 is slidably fitted in the cylinder 2, and a combustion chamber 4 is formed by the cylinder 2 and the piston 3. ing.

An intake passage 6 has one end connected to the combustion chamber 4 and the other end opened to the atmosphere via an air cleaner 7, and an intake valve 8 is provided in the opening of the intake passage 6 to the combustion chamber 4.
A fuel injector 10 for supplying fuel to the engine is provided immediately upstream of the fuel injector. Further, the intake passage 6 is provided with a throttle valve 9 for adjusting the intake flow rate. Further, the intake passage 6 is provided with an ISC passage 11 that bypasses the throttle valve 9, and the ISC passage 11 is provided with an ISC valve 12. The ISC passage 11 and the ISC valve 12 constitute intake amount adjusting means 13 for adjusting the intake amount of the engine.

In addition to the ISC passage 11, the intake passage 6 is provided with a bypass passage 21 that bypasses the throttle valve 9. A temperature sensitive valve 22 is provided in the bypass passage 21. The temperature-sensitive valve 22 is of a wax type, and its temperature-sensitive portion is supplied with engine cooling water from the water jacket of the engine 1. The higher the temperature of the engine cooling water, the smaller the opening of the valve. Is set to have an air amount control characteristic as shown in FIG.

Further, 15 is an exhaust passage having one end connected to the combustion chamber and the other end opened to the atmosphere, and an exhaust valve 17 is provided at an opening of the exhaust passage 15 to the combustion chamber 4. A catalyst 16 for purifying exhaust gas is disposed in the exhaust passage 15. In addition, 18 is a cam shaft for driving the intake / exhaust valves 8 and 17, and 19 is a distributor. The operations of the injector 10 and the ISC valve 12 are controlled by the control unit 30.

Further, 31 is an air flow sensor provided in the intake passage 6 upstream of the throttle valve 9 for detecting the intake flow rate, and 32 is an intake temperature detecting means provided in the intake passage 6 upstream of the throttle valve 9 for detecting the intake temperature. Intake air temperature sensor,
33 is a throttle sensor connected to the throttle valve 9 for detecting the opening of the throttle valve 9, 34 is the camshaft 18
Is a crank angle sensor for detecting the crank angle, 35 is a water temperature sensor provided in the cooling water passage of the engine 1 for detecting the temperature of the engine cooling water, and 36 is an oxygen concentration in the exhaust gas provided in the exhaust passage 15. Is an O ₂ sensor for detecting the engine speed, and 37 is a speed sensor as a speed detecting means for detecting the engine speed. These various sensors 31-37
The output of is input to the control unit 30.

Then, the ISC valve 12 by the control unit 30
The operation control of will be described based on the flow of FIG. After starting, first in step S ₁ , the engine cooling water temperature THW is read, and in step S ₂ , the fourth cooling water temperature THW is read based on this cooling water temperature THW.
The basic amount G _B of the ISC valve 12 is obtained by the function f ₁ shown in the figure, and the target rotational speed N _O is obtained by the function f ₂ showing a tendency similar to that of the function f ₁ . Further, it reads the intake air temperature THA of the engine in step S _3, the engine in step S ₄ to determine whether during startup.

Then, when YES is starting is to perform the start-up increase in the amount of air supplied by the ISC valve 12, the starting increased air quantity G _SAW of ISC valve 12 in the coolant temperature THW and the intake air temperature THA proceeds to step S ₅ Based on this, calculation is performed by the function f ₃ shown in FIG. Further detects the operating state of the engine in step S _7,
Based on this operating state, another correction amount G _C is calculated in step S ₈ . This correction amount G _C is, for example, a dashpot correction,
It includes load correction and atmospheric pressure correction. And
The engine speed N is read in step S ₉ , and step S ₁₀
Is the deviation between the engine speed N and the target speed N _O (N−N _O ).
Based on the above, the feedback correction amount G _FB of the ISC valve 12 is obtained by the function f ₄ shown in FIG.

Then, the final value G of the control amount of the ISC valve 12 in step S _11
A is _calculated by "G _A = G _B + G _SAW + G _C + G _FB ". Furthermore,
Reading the battery voltage + B at step S _12, step S
The correction value D of the control amount of the ISC valve 12 corrected by this battery voltage in ₁₃ is obtained by the function f ₅ based on G _A , + B, THW. Then, in step S ₁₄ , I
Drive the SC valve 12 and return to step S ₁ .

On the other hand, after the startup is completed and warm-up operation is started,
When the determination in S ₄ is NO, the process proceeds to step S ₆ and the ISC valve 1
Step 2 After decreasing the amount of air for starting increase G _SAW by A, step S
Proceeds to _7, hereinafter, the processes to the same manner as described above step S _14. Here, the correction amount A is set according to the intake air temperature. That is, as shown in FIG.
The amount of air that 22 bears is greater during warm-up operation from cold start (solid line) than during warm-up operation from cold start (solid line). Therefore, the amount of air that the ISC valve 12 bears also fluctuates in response to this, so the correction amount A needs to be corrected according to the difference in the amount of the burdened air.

In the above flow, in steps S _{9 to} S ₁₁ , the output of the rotation speed detecting means (rotation speed sensor) 37 is received, and the intake air amount adjusting means 13 sets the target engine rotation speed in the predetermined operation area (idle operation area). A feedback control means 41 for feedback controlling the value is configured. Further, in step S ₆ , the output of the intake air temperature detecting means (intake air temperature sensor) 32 is received, and as the intake air temperature becomes lower, the target value of the feedback control means 41 is reduced so that the intake air amount adjusted by the intake air amount adjusting means 13 is reduced. Correction means 42 for decreasing
Is composed. Therefore, in the above embodiment,
When the engine temperature is low and fuel vaporization / atomization is poor, such as during warm-up operation from a very low temperature start, the opening of the temperature sensing valve 22 increases and the amount of intake air from the bypass passage 21 increases. The feedback correction amount G _FB of the valve 12 is prevented from becoming excessive and the controllability of the ISC valve 12 is secured, and the overall intake amount is increased and secured, and a sufficient air-fuel mixture amount is obtained and cryogenic startability is improved. It will be.

In that case, as shown in FIG. 7, there is a response delay in the operation of the temperature sensitive valve with respect to the rise of the engine temperature (solid line), and there is a closing delay (broken line). Therefore, the engine speed should be set to the target value. The ISC valve 12 is feedback-controlled in the direction in which the intake amount becomes smaller than that in the warm state.

However, at that time, the starting increased air amount G _SAW of the ISC valve 12 is corrected in accordance with the intake air temperature, and the intake air amount that the ISC valve 12 bears is corrected to a small amount.
_{Since the FB} becomes small, the fluctuation of the intake air amount during the transition between the feedback zone and the open zone becomes small, and the sudden fluctuation of the engine speed is suppressed.

Incidentally, in the above embodiment, the correction is made to reduce the starting increased air amount G _SAW of the ISC valve 12 by A, but the basic amount G _B of the ISC valve 12 may be corrected to be reduced.

Further, the intake air amount may be adjusted in a predetermined operation region by adjusting the opening degree of the throttle valve 9 without providing the ISC passage 11 and the ISC valve 12. In this case, the throttle valve 9 constitutes the intake air amount adjusting means.

(Effects of the Invention) As described above, according to the engine idle speed control device of the first and second aspects of the invention, the bypass passage for bypassing the throttle valve of the intake passage is operated based on the signal related to the engine temperature. A temperature-sensing valve that opens and closes so that the opening degree increases as the temperature lowers is provided, and the engine speed is feedback-controlled to the target value by the intake air amount adjusting means in a predetermined operating region, and the intake air amount adjusting means decreases as the intake air temperature decreases. Since the correction is made to reduce the amount of intake air to bear, it is possible to obtain the basic effect that the cryogenic startability can be improved while ensuring the controllability of the intake air amount adjusting means during warm-up operation from the cryogenic start. In addition, there is less fluctuation in intake air that can occur during the transition between the feedback zone and open zone due to the delay in the response of the temperature sensing valve. It is possible to suppress sudden fluctuations in engine speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 9 exemplify an embodiment of the present invention, FIG. 2 is an overall schematic configuration diagram, FIG. 3 is a flow chart showing operation control of an ISC valve by a control unit, and FIG. Fig. 5 is a characteristic diagram showing the basic amount, Fig. 5 is a characteristic diagram showing the feedback correction amount of the ISC valve, and Fig. 6 is a starting increased air amount G of the ISC valve.
FIG. 7 is a characteristic diagram showing _SAW , FIG. 7 is a diagram showing response delay of the temperature sensitive valve, FIG. 8 is a characteristic diagram showing air amount characteristic of the temperature sensitive valve, and FIG. 9 is air amount carried by the temperature sensitive valve. It is a figure. 1 ... Engine 13 ... Intake amount adjusting means 21 ... Bypass passage 22 ... Temperature sensing valve 32 ... Intake temperature sensor (intake temperature detecting means) 37 ... Rotation speed sensor (rotation speed detecting means) 41 ... Feedback Control means 42 ... Correction means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-203840 (JP, A) JP-A-60-19937 (JP, A) JP-A-2-102337 (JP, A) JP-A-2- 81940 (JP, A) JP 57-38643 (JP, A) JP 59-18124 (JP, Y2)

Claims (2)

(57) [Claims] 1. An intake air amount adjusting means for adjusting an intake air amount of an engine, a rotation speed detecting means for detecting an engine rotation speed, an output of the rotation speed detecting means, and an engine rotation speed in a predetermined operating region is a target value. Feedback control means for feedback controlling the intake air amount adjusting means, a bypass passage for bypassing the throttle valve of the intake passage to supply intake air to the engine, and a bypass passage provided in the bypass passage for changing the signal related to the engine temperature. On the basis of the temperature sensing valve that opens and closes so that the opening degree increases as the engine temperature decreases, the intake temperature detecting means for detecting the intake temperature of the engine, the output of the intake temperature detecting means, and the lower the intake temperature becomes Correction means for reducing the target value of the feedback control means so as to reduce the intake air amount that the intake air amount adjusting means bears. An engine idle speed control device characterized by the above. 2. The opening degree of the temperature sensitive valve at a predetermined engine temperature is set so that the amount of air that the temperature sensitive valve bears during the operation from the cryogenic start is larger than that during the operation from the low temperature start. The idle speed control device for the engine according to claim 1.