JP2751322B2 - Fuel control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an internal combustion engine, and more particularly to a fuel control device for an internal combustion engine, which prevents fluctuations in engine speed during idling of the internal combustion engine without deteriorating exhaust gas values. The invention relates to a fuel control device for an internal combustion engine to be obtained.

[Conventional technology]

The internal combustion engine mounted on a vehicle has extremely large fluctuations in the vehicle speed, that is, the engine speed and the engine load, and in various operating states in which these two variables are combined, a low fuel consumption rate, a low harmful exhaust gas value, etc. Is required. In order to control the fuel so as to obtain an appropriate air-fuel ratio in various operating states, there is, for example, one disclosed in JP-A-62-63149. What is disclosed in this publication is an internal combustion engine that performs feedback control of fuel so as to have a predetermined air-fuel ratio according to the operation range of the internal combustion engine,
When an external load is added during so-called racing,
There is disclosed a fuel control device that performs fuel control so that the air-fuel ratio in the low load side operation region is maintained even when the operation region shifts from the low load side to the high load side. As a result, when the operating range shifts from the low load side to the high load side, a drop in the engine speed due to a rapid change in the fuel supply amount or the like is prevented, and the operating state is stabilized.

[Problems to be solved by the invention]

By the way, an idle operation region and a partial operation region are respectively set in the operation region of the internal combustion engine, and whether the operation region of the internal combustion engine is the idle operation region or the partial operation region is determined by, for example, a throttle sensor or an idle switch. When the intake throttle valve is at idle opening, it is determined that the engine is in the idling operation region, and when the intake throttle valve exceeds the idle opening, it is determined that the engine is in the partial operation region. In the case where the engine speed exceeds the predetermined speed even when the intake throttle valve is at the idle opening, it is determined that the engine is in the partial operation region, and the engine is set according to the idle operation region and the partial operation region. The idle control constant and a partial control constant of a control constant larger than the idle control constant are used to determine a predetermined value in each operation region. There is a fuel control apparatus for an internal combustion engine feedback-controls the fuel so that the fuel ratio.

In the idling operation state, the fuel control device for the internal combustion engine stabilizes the idling speed by slowly controlling the idling control constant with a small amplitude and a large period as shown in FIG. 5 (A). ing.
On the other hand, in the partial operation state, as shown in FIG. 5 (B), by quickly controlling with a partial control constant having a large amplitude and a small cycle, the exhaust gas is quickly brought close to a predetermined air-fuel ratio, that is, the stoichiometric air-fuel ratio. The value is good.

With such a fuel control device for an internal combustion engine, in a no-load operation state (no load; NO LOA
D) When the intake throttle valve of the internal combustion engine is opened from the idle opening to gradually increase the engine speed, the intake throttle valve exceeds the idle opening, for example, the idle switch is turned off, and the engine speed is reduced. Is the predetermined number of revolutions (usually 1500 to 2000 rp
When the value exceeds m), the process shifts to the partial operation region, and the feedback control based on the partial control constant is performed.

However, at this time, mechanical loss (mechanical loss)
In a so-called lightly rotating internal combustion engine with little
Due to the partial control constant having a large amplitude and a small period as shown in FIG. 4A, a phenomenon occurs in which the engine speed fluctuates up and down due to the rich / lean amplitude in a range of about 100 rpm as shown in FIG. There was a problem.

When such a change in the engine speed occurs, the partial control constant in the partial operation region is determined from a request for a small exhaust gas value, so that the partial control constant cannot be simply reduced. For this reason, there is an inconvenience that it is not possible to prevent fluctuations in the engine speed when shifting from the idle operation region to the partial operation region as described above.

[Object of the invention]

Accordingly, an object of the present invention is to provide a fuel for an internal combustion engine that performs feedback control of a fuel so that a predetermined air-fuel ratio is obtained based on an idle control constant and a partial control constant that are set according to an idle operation region and a partial operation region of the internal combustion engine. It is an object of the present invention to provide a fuel control device for an internal combustion engine that can prevent fluctuations in the engine speed during idling of the internal combustion engine without causing deterioration of the exhaust gas value.

[Means for solving the problem]

In order to achieve this object, the present invention sets an idle operation region and a partial operation region in accordance with the opening degree of an intake throttle valve of an internal combustion engine or the opening degree of the intake throttle valve and the engine speed, and sets each of these operating modes. An idle control constant and a partial control constant of a control constant larger than the idle control constant are set for each region, and a predetermined idle in each of the operation regions is set by the control constants set in accordance with each of the operation regions. In a fuel control device for an internal combustion engine that performs feedback control of fuel to have a fuel ratio, when the speed of a vehicle equipped with the internal combustion engine is zero, when the internal combustion engine shifts from an idle operation region to a partial operation region, For a predetermined time after the shift to the partial operation region, the fuel is feedback-controlled by the partial control constant so that a predetermined air-fuel ratio is obtained. In addition, after the predetermined time has elapsed, even when the partial operation region is continued, the feedback control of the fuel is performed by a control constant smaller on the idle control constant side than the partial control constant so that the predetermined air-fuel ratio is obtained. Means are provided.

[Action]

According to the configuration of the present invention, when the internal combustion engine shifts from the idle operation region to the partial operation region when the vehicle speed of the vehicle equipped with the internal combustion engine is zero, the control unit shifts to the partial operation region. For a predetermined period of time from the time when the vehicle is started, the fuel is feedback-controlled to a predetermined air-fuel ratio by a partial control constant larger than the idle control constant, thereby avoiding deterioration of the exhaust gas value when starting the vehicle. Can be. Further, after the predetermined time has elapsed, the control means may provide a predetermined air-fuel ratio by a control constant smaller on the idle control constant side than the partial control constant even when the partial operation region is continued. By performing the feedback control of the fuel, the control can be performed slowly with a control constant having a smaller amplitude and a larger cycle than the partial control constant. With this, it is possible to clearly determine when the vehicle starts and when the vehicle is idling while stopped, and to avoid deterioration of the exhaust gas value when starting the vehicle while maintaining the engine in the partial operation area when idling while the vehicle is stopped. It is possible to prevent the rotation speed from fluctuating.

〔Example〕

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

 1 to 3 show an embodiment of the present invention.

In FIG. 1, 2 is an internal combustion engine, 4 is an intake passage, and 6 is an exhaust passage. An intake throttle valve 8 is provided in the intake passage 4 of the internal combustion engine 2. In the intake passage 4 downstream of the intake throttle valve 8, a fuel injection valve 10 constituting a fuel system is provided with a combustion chamber 12.
It is provided to be oriented. The fuel injected from the fuel injection valve 10 is sucked into the combustion chamber 12 together with the air and burned. The exhaust gas generated by combustion is discharged to the outside through the exhaust passage 6.

The combustion injection valve 10 is connected to a fuel tank 16 by a fuel supply passage 14. The fuel in the fuel tank 16 is supplied from the fuel injection valve 10 by the fuel pump 18 through the fuel supply passage 14.
Supplied to The fuel supply passage 14 is provided with a fuel regulator 20. The fuel regulator 20 is a pressure guiding passage that communicates one end with the intake passage 4 downstream of the intake throttle valve 8.
The intake pressure is introduced into the pressure chamber 24 by 22 to adjust the fuel pressure to a predetermined pressure, and excess fuel is returned to the combustion tank 16 by the fuel return passage 26.

The fuel injection valve 10 is connected to a control unit 28 as control means. An ignition coil 30 for detecting the engine speed and a pressure sensor 32 for detecting the pressure in the intake passage 4 are connected to the control unit 28. The control unit 28
As shown in the figure, the fuel injection valve 10 is basically controlled by a signal of an engine speed and an intake pressure input from an ignition coil 30 and a pressure sensor 32 to inject and supply fuel to the internal combustion engine 2.

As shown in FIG. 2, the control unit 28 detects a CO adjustment register 34, a water temperature sensor 36 for detecting a coolant temperature, an intake temperature sensor 38 for detecting an intake air temperature, and an opening degree of the intake throttle valve 8. Throttle sensor 40, vehicle speed sensor 4 that detects vehicle speed
2. An idle switch 46 that is turned on when the battery 44 and the intake throttle valve 8 is at the idle opening and is turned off when the intake throttle valve 8 exceeds the idle opening is connected. The control unit 28
The fuel injection valve 10 is corrected and controlled by various signals input from these various sensors 34 to 46 to inject and supply fuel to the internal combustion engine 2.

The control unit 28 sets an idle operation region and a partial operation region in accordance with the opening degree of the intake throttle valve 8 of the internal combustion engine 2 or the opening degree of the intake throttle valve 8 and the engine speed. An idle control constant and a partial control constant of a control constant larger than the idle control constant are set, and whether the operating region of the internal combustion engine 2 is an idle operating region or a partial operating region is determined by, for example, When the intake throttle valve 8 is at the idle opening, it is determined that the intake throttle valve 8 is in the idling operation region, and when the intake throttle valve 8 exceeds the idle opening, it is determined that the intake throttle valve 8 is in the partial operation region, or the idle switch 46 and the ignition coil 30 are switched. If the engine speed exceeds a predetermined speed even if the intake throttle valve 8 is at the idle opening degree, it is determined that the engine is in the partial operation range. Then, the fuel is controlled so as to have a predetermined air-fuel ratio in each operation region by using an idle control constant set in accordance with the idle operation region and the partial operation region and a partial control constant larger than the idle control constant. Perform feedback control.

In the fuel control device that performs the feedback control of the fuel, the control unit 28 causes the internal combustion engine 2 to move from the idling operation region to the partial operation mode when the vehicle speed (not shown) of the vehicle equipped with the internal combustion engine 2 is zero. When shifting to the region, a predetermined time t from the time of shifting to the partial operation region is feedback controlled so that the fuel becomes a predetermined air-fuel ratio by a partial control constant of a control constant larger than an idle control constant. Predetermined time t
After the time elapses, the fuel is feedback-controlled by a control constant smaller on the idle control constant side than the partial control constant so that the predetermined air-fuel ratio is obtained even when the partial operation region is continuing.

 Next, the operation will be described with reference to FIG.

When the control is started (100), it is determined whether or not the fuel feedback control is being performed (101). If feedback control is not performed, it is irrelevant to the present invention (102)
The control is separately performed as needed.

If the feedback control of the fuel is being performed in step (101), it is determined whether the vehicle speed is zero (103). If the vehicle speed is not zero (vehicle speed ≠ 0), it is irrelevant to the present invention (102) as described above, and control is separately performed as necessary.

In step (103), the vehicle speed is zero (vehicle speed = 0).
In this case, it is determined whether the idle switch 46 has been turned off from on (104). When the idle switch 46 is on, feedback control (105) is performed using an idle control constant.

When the idle switch 46 is turned off from on in step (104), it is determined whether the vehicle speed is zero (106). If the vehicle speed is not zero (vehicle speed ≠ 0), feedback control (10
7) Yes.

In step (106), the vehicle speed is zero (vehicle speed = 0).
In this case, it is determined whether or not a predetermined time t (for example, 2 seconds) has elapsed after the idle switch 46 was turned off from on (108). If the predetermined time t has not elapsed, feedback control (109) is performed using a partial control constant.

If the predetermined time t has elapsed in step (108), it is determined (110) whether or not the vehicle speed is zero. If the vehicle speed is not zero (vehicle speed ≠ 0), feedback control (111) is performed using a partial control constant.

In step (110), the vehicle speed is zero (vehicle speed = 0).
In the case of (1), feedback control (112) is performed using a control constant smaller on the idle control constant side than the partial control constant, for example, an idle control constant. Alternatively, feedback control (113) may be performed using a control constant intermediate between the partial control constant and the idle control constant as a control constant smaller on the idle control constant side than the partial control constant.

Thereafter, it is determined whether the vehicle speed has exceeded zero (114),
When the vehicle speed exceeds zero (vehicle speed> 0), the feedback control (115) is immediately performed using the partial control constant, and the end (116) is reached.

If the vehicle speed is zero (vehicle speed = 0) in the step (114), the steps (112) or (113) are executed until the idle switch 46 is turned on from off, and the vehicle speed exceeds zero ( If the vehicle speed is greater than 0), feedback control is immediately performed using the partial control constant (115),
End (116).

As described above, when the speed of the vehicle equipped with the internal combustion engine 2 is zero and the internal combustion engine 2 shifts from the idle operation region to the partial operation region by the control unit 28,
A predetermined time t from the shift to the partial operation region is feedback-controlled so that the air-fuel ratio becomes a predetermined air-fuel ratio by a partial control constant that is a control constant larger than an idle control constant. It is possible to avoid confusion with the air blowing and to avoid deterioration of the exhaust gas value when starting. This is because CO is most likely to be generated when the vehicle starts moving.For this reason, a predetermined time t from when the vehicle shifts to the partial operation region is controlled by a feedback control so that the fuel becomes a predetermined air-fuel ratio by a partial control constant. In addition, deterioration of the exhaust gas value can be avoided. In normal operation, running starts within a predetermined time t after the idle switch 46 is turned off from on and the vehicle speed exceeds zero (vehicle speed> 0). Therefore, feedback control is performed using a partial control constant. become.

Further, after the predetermined time t has elapsed, the control unit 28 sets the air-fuel ratio to a predetermined value by using a control constant that is smaller on the idle control constant side than the partial control constant even if the partial operation region is continuing. By performing the feedback control of the fuel, the control can be performed slowly with a control constant having a smaller amplitude and a larger cycle than the partial control constant.

Therefore, the exhaust gas value does not deteriorate, and
It is possible to avoid confusion with the start and to clearly determine when the internal combustion engine 2 is idling, thereby preventing fluctuations in the engine speed during the idling.

The control constant that is smaller on the idle control constant side than the partial control constant is defined as the P value (proportional portion) of the control constant and I
The value (integral component) and / or one of the values is reduced. Further, in the above embodiment, it is determined by the idle switch 46 that the operation has shifted from the idle operation region to the partial operation region. However, the determination may be made by the throttle sensor 40.

〔The invention's effect〕

Thus, according to the present invention, by the control means,
When the speed of the vehicle equipped with the internal combustion engine is zero and the internal combustion engine shifts from the idling operation region to the partial operation region, the predetermined time from the shift to the partial operation region is larger than the idle control constant. By performing feedback control of the fuel so that the predetermined air-fuel ratio is obtained by the partial control constant of the following control constant, it is possible to avoid confusion between when the vehicle starts and when the vehicle is idling while the vehicle is stopped, and the exhaust gas value when starting is deteriorated. Can be avoided. Further, after the predetermined time has elapsed, the control means may provide a predetermined air-fuel ratio by a control constant smaller on the idle control constant side than the partial control constant even when the partial operation region is continued. By performing the feedback control of the fuel, the control can be performed slowly with a control constant having a smaller amplitude and a larger cycle than the partial control constant.

Therefore, the fuel control device for an internal combustion engine of the present invention can clearly determine when the vehicle starts and when the vehicle is idling while the vehicle is stopped, while avoiding deterioration of the exhaust gas value when the vehicle starts.
It is possible to prevent fluctuations in the engine speed in the partial operation region when the vehicle is idling while the vehicle is stopped.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a fuel control device, FIG. 2 is a block diagram of the fuel control device, and FIG. 3 is a control flowchart. FIGS. 4A and 4B are timing charts of the partial control constant and the engine speed. FIGS. 5A and 5B are diagrams showing an idle control constant and a partial control constant. In the figure, 2 is an internal combustion engine, 4 is an intake passage, 6 is an exhaust passage, 8 is an intake throttle valve, 10 is a fuel injection valve, 12 is a combustion chamber, 28
Is a control unit, 30 is an ignition coil, 32 is a pressure sensor,
34 is a CO adjustment register, 36 is a water temperature sensor, 38 is an intake temperature sensor, 40 is a throttle sensor, 42 is a vehicle speed sensor, 44 is a battery, and 46 is an idle switch.

Claims (1)

(57) [Claims] An idle operation region and a partial operation region are set according to an opening degree of an intake throttle valve or an opening degree of an intake throttle valve of an internal combustion engine and an engine speed, and an idle control constant is set for each of these operation regions. And a partial control constant of a control constant larger than the idle control constant, and the fuel is fed back so that a predetermined air-fuel ratio is obtained in each of the operation regions by the respective control constants set in accordance with the respective operation regions. In the fuel control device for the internal combustion engine to be controlled, when the vehicle speed of the vehicle equipped with the internal combustion engine is zero,
When the internal combustion engine shifts from the idling operation region to the partial operation region, the fuel is feedback-controlled so that the air-fuel ratio becomes a predetermined air-fuel ratio by a partial control constant for a predetermined time after the shift to the partial operation region. After a lapse of time, control means is provided for performing feedback control of the fuel so as to attain a predetermined air-fuel ratio by a control constant smaller on the idle control constant side than the partial control constant even when the partial operation region is continued. A fuel control device for an internal combustion engine, comprising: