JPH02218835A - Fuel control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the aggravation of the exhaust gas value at a starting time by performing the feedback control of fuel so as to obtain a specified air-fuel ratio by a partial control constant for a specified time from the shifting time when an internal combustion engine is shifted from the idle operating region to the partial operating region at the time of the car speed being zero. CONSTITUTION:At the time of idle operation, the stabilization of idle engine speed is promoted by performing fuel injection control slowly by an idle control constant small in amplitude and large in cycle. When the shifting from the idle operating region to the partial operating region is judged from the signal of an idle switch 46 at the time of detecting the car speed being zero in a control part 28 by a speed sensor 42, the fuel is feedback controlled to have the specified air-fuel ratio by a partial control constant large in amplitude and small in cycle for the specified time from the shifting time. After the lapse of the specified time, the fuel is feedback controlled by a smaller control constant on the idle control constant side than the partial control constant.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel control device for an internal combustion engine, and in particular, to a fuel control device for an internal combustion engine, which prevents fluctuations in engine speed when the internal combustion engine is revving without causing deterioration of exhaust gas values. The present invention relates to a fuel control device for an internal combustion engine.

[Conventional technology]

The internal combustion engine installed in a vehicle has extremely large fluctuations in vehicle speed, that is, engine speed, and engine load, and under various operating conditions that combine these two fluctuation factors, low fuel consumption, low harmful exhaust gas values, etc. is required. Therefore, for example, there is a method disclosed in Japanese Patent Laid-Open No. 62-63149 that controls fuel so that the air-fuel ratio is appropriate under various operating conditions. What is disclosed in this publication is that in an internal combustion engine that performs feedback control of fuel to a predetermined air-fuel ratio according to the operating range of the internal combustion engine, when an external load is added during revving, so-called racing, the operating range changes. Even when shifting from the low load side to the high load side, the fuel side i
A fuel control system is disclosed that performs the following steps. As a result, when the operating range shifts from the low load side to the high load side,
This prevents the engine speed from dropping due to sudden changes in the amount of fuel supplied, thereby stabilizing the operating state.

[Problem that the invention seeks to solve]

By the way, the operating range of the internal combustion engine is set to an idle operating range and a partial operating range, respectively, and whether the operating range of the internal combustion engine is the idle operating range or the partial operating range is determined by, for example, a throttle sensor or an idle switch. It is determined whether the intake throttle valve is at the idle opening or exceeds the idle opening, and the idle control constant and partial control constant are set according to the idle operating range and the partial operating range, respectively. There is a fuel control device for an internal combustion engine that performs feedback control of fuel to maintain the fuel ratio.

This fuel control device for an internal combustion engine attempts to stabilize the idle speed by slowly controlling the idle speed using an idle control constant with a small amplitude and a large period, as shown in FIG. 5(A), as shown in FIG. 5(A). ing. On the other hand, in the partial operation state, as shown in Figure 5 (B), by quickly controlling the partial control constant with a large amplitude and a small period, the exhaust gas is quickly brought close to the predetermined void ratio, that is, the stoichiometric air-fuel ratio. Good value.

With such a fuel control device for an internal combustion engine, a no-load operating state (no load; No LO), which is feedback-controlled by an idle control constant in an idle operating region
When the intake throttle valve of an internal combustion engine (AD) is opened from the idle opening to gradually increase the engine speed, the intake throttle valve exceeds the idle opening and, for example, the idle switch is turned off, causing the engine speed to increase. is the specified number of rotations (usually 1500 to 2
When the speed exceeds 000 rpm), a transition is made to a partial operation region, and feedback control using a partial control constant is performed.

However, at this time, in a so-called lightly rotating internal combustion engine that has little mechanical loss, the partial control constant has a large amplitude and a small period as shown in FIG. As shown in FIG. 2, there is a problem in which the upper limit fluctuates due to the rich/lean amplitude in the engine speed range of approximately 1100 rpm.

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

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fuel control device for an internal combustion engine that performs feedback control of fuel to a predetermined air-fuel ratio using control constants set according to the operating range of the internal combustion engine. An object of the present invention is to realize a fuel control device for an internal combustion engine that can prevent fluctuations in the engine speed when the engine is idling.

[Means for solving problems]

In order to achieve this object, the present invention provides a fuel control device for an internal combustion engine that performs feedback control of fuel to a predetermined air-fuel ratio using control constants set according to the operating range of the internal combustion engine, and provides a fuel control system for a vehicle equipped with the internal combustion engine. When the internal combustion engine shifts from the idle operating region to the partial operating region when the vehicle speed of In addition, after the predetermined time has elapsed, a control means is provided for feedback controlling the fuel to a predetermined air-fuel ratio using a control constant that is smaller on the idle control constant side than the partial control constant.

[Operation] According to the configuration of the present invention, when the internal combustion engine moves from the idle operating region to the partial operating region when the vehicle speed of the vehicle equipped with the internal combustion engine is zero, the control means causes the internal combustion engine to shift from the idle operating region to the partial operating region. By controlling the fuel to a predetermined air-fuel ratio using a partial control constant for a predetermined period of time from the time of transition, it is possible to avoid deterioration of the exhaust gas value when starting the vehicle. Also,
After the predetermined time has elapsed, the control means feedback-controls the fuel to a predetermined air-fuel ratio using a control constant that is smaller on the idle control constant side than the partial control constant, so that the fuel ratio is lower than the nominal control constant. can also be controlled slowly by a control constant with a small amplitude and a large period.

〔Example〕

Next, embodiments of the present invention will be described in detail based on the drawings.

1 to 3 show embodiments of this 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 on the downstream side of the intake throttle valve 8, a fuel injection valve 10 forming a fuel system is connected to the combustion chamber 1.
2. Fuel injected from the fuel injection valve 10 is sucked into the combustion chamber 12 together with air,
be burned.

The exhaust gas produced by combustion is discharged to the outside through the exhaust passage 6.

The fuel injection valve 10 is communicated with a fuel tank 16 through a fuel supply passage 14 . The fuel in the fuel tank 16 is
Fuel is supplied to the fuel injection valve 10 by the fuel pump 18 via the fuel supply passage 14 .

A fuel regulator 20 is provided in the fuel supply passage 14 . The fuel regulator 20 is an intake throttle valve 8
Intake pressure is introduced into the pressure chamber 24 through a pressure guiding passage 22 whose one end communicates with the intake passage 4 on the downstream side, the fuel pressure is adjusted to a predetermined pressure, and excess fuel is returned to the fuel tank 16 through a fuel return passage 26.

The fuel injection valve 10 is connected to a control section 28 which is a 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 section 28 . Control part 2
8, as shown in FIG. 2, basically controls the fuel injection valve 10 based on the engine speed and intake pressure signals input from the ignition coil 30 and the pressure sensor 32, and injects and supplies fuel to the internal combustion engine 2. do.

Further, as shown in FIG. 2, the control unit 28 includes a CO adjustment register 34, a water temperature sensor 36 that detects the cooling water temperature, an intake air temperature sensor 38 that detects the intake air temperature, and an opening degree of the intake throttle valve 8. A throttle sensor 40, a vehicle speed sensor 42 that detects vehicle speed, a battery 44, and an idle switch 46 that is turned on when the intake throttle valve 8 is at the idle opening and turned off when the opening exceeds the idle opening are connected. The control unit 28 corrects and controls the fuel injection valve 10 based on various signals input from these various sensors 34 to 46, and injects and supplies fuel to the internal combustion engine 2.

As a result, the control unit 28 sets the operating range of the internal combustion engine 2 to the idle operating range and the partial operating range, respectively.
Determines whether the operating range of the internal combustion engine 2 is in the idle operating range or the partial operating range, for example, whether the intake throttle valve 8 is at the idle opening or exceeds the idle opening, based on the signal from the idle switch 46. Then, the fuel is feedback-controlled to a predetermined air-fuel ratio in each operating region using an idle control constant and a partial control constant that are respectively set according to the idle operating region and the partial operating region.

In the fuel control device that performs feedback control of fuel in this manner, the control unit 28 controls the internal combustion engine 2 from the idle operating region to the partial operating region when the vehicle speed of a vehicle (not shown) equipped with the internal combustion engine 2 is zero. When transitioning to the partial operation region, the fuel is feedback-controlled to a predetermined air-fuel ratio using a partial control constant for a predetermined time t from the time of transition to the partial operation region, and after the predetermined time t has elapsed, the partial control constant is The fuel is feedback-controlled to a predetermined air-fuel ratio using a control constant that is smaller than the idle control constant.

Next, the operation will be explained according to FIG.

When the control starts (100), it is determined whether or not fuel feed pack control is in progress (101). If feedback control is not performed, it is irrelevant to this invention (10
2), and control is performed separately as necessary.

If fuel feedback control is in progress in step (101), determine whether the vehicle speed is zero (103).
do. If the vehicle speed is not zero (vehicle speed≠0), this is irrelevant to the present invention (102) as described above, and separate control is performed as necessary.

In step (103), the vehicle speed is zero (vehicle speed - 〇)
If so, it is determined whether the idle switch 46 has been turned from on to off (104).

When the idle switch 46 is on, feedback control is performed using the idle control constant (105).

In step (104), the idle switch 46
If it changes from on to off, it is determined whether the vehicle speed is zero (106). If the vehicle speed is not zero (vehicle speed≠0),
Feedback control (
107) Do.

In step (106), the vehicle speed is zero (vehicle speed = 0).
In this case, it is determined whether 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 (1
09) Do.

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

In step (111), the vehicle speed is zero (vehicle speed - 〇)
In this case, feedback control (112) is performed using a control constant that is smaller on the idle control constant side than the partial control constant, for example, an idle control constant. Alternatively, feedback control (113) is performed using a control constant that is intermediate between the partial control constant and the idle control constant as a control constant that is smaller on the idle control constant side than the partial control constant.
You may do so.

After that, it is determined whether the vehicle speed has exceeded zero (114),
When the vehicle speed exceeds zero (vehicle speed > 0), feedback control (115) is immediately turned to L and end (116) by the partial control constant.

Note that if the vehicle speed is zero (vehicle speed = 0) in the step (114), the step (112) or (113) is continued until the idle switch 46 is turned on from off.
If the vehicle speed exceeds zero (vehicle speed > 0), feedback control (11
5) L, becomes the end (116).

In this way, when the internal combustion engine 2 shifts from the idle operating region to the partial operating region when the vehicle speed of the vehicle equipped with the internal combustion engine 2 is zero, the control unit 28 controls the control unit 28 to control the timing when the internal combustion engine 2 shifts from the idle operating region to the partial operating region. By feedback-controlling the fuel to a predetermined air-fuel ratio using a partial control constant for a predetermined period of time, it is possible to avoid confusion between when the vehicle starts and when the vehicle is idling while the vehicle is stopped.
, it is possible to avoid deterioration of exhaust gas values when starting the vehicle. This is because CO is most likely to be generated when the vehicle starts, and therefore, for a predetermined time t from the time the vehicle shifts to the partial operation region, the fuel is feedback-controlled to a predetermined air-fuel ratio using the partial control constant. This makes it possible to avoid deterioration in exhaust gas values.

In addition, in normal driving, the vehicle starts running within a predetermined time 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 the partial control constant. become.

Further, after the predetermined time t has elapsed, the control section 28 feedback-controls the fuel to a predetermined air-fuel ratio using a smaller control constant on the side of the idle control constant than the partial control constant, thereby increasing the partial control constant. It is possible to perform slow control using a control constant that has a smaller amplitude and a larger period than the above.

Therefore, it is possible to clearly determine when the internal combustion engine 2 is revving without causing a deterioration of the exhaust gas value, and to avoid confusion with when starting, and to prevent fluctuations in engine speed when revving the internal combustion engine 2. can do.

In addition, a control constant that is smaller on the idle control constant side than the partial control constant is a control constant that is smaller than both the P value (proportional component) and I value (integral component), or either one of them. It is. Furthermore, in the embodiment described above, the transition from the idle operation range to the partial operation range was determined by the idle switch 46, but the determination can also be made by the throttle sensor 40.

〔Effect of the invention〕

As described above, according to the present invention, when the internal combustion engine shifts from the idle operating region to the partial operating region when the vehicle speed of the vehicle equipped with the internal combustion engine is zero, the control means causes the internal combustion engine to shift to the partial operating region. By feedback-controlling the fuel to a predetermined air-fuel ratio using a partial control constant for a predetermined period of time, it is possible to avoid deterioration of the exhaust gas value when starting the vehicle. Furthermore, after the predetermined time has elapsed, the control means feedback-controls the fuel to a predetermined air-fuel ratio using a control constant that is smaller than the partial control constant on the side of the idle control constant, so that the fuel ratio is lower than the partial control constant. Slow control can be achieved by using a control constant with a small amplitude and a large period.

Therefore, it is possible to avoid confusion with the time of starting, and to prevent fluctuations in the engine speed when the internal combustion engine is revving, without causing a deterioration of the exhaust gas value.

[Brief explanation of the drawing]

1 to 3 show embodiments 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. 4(A) and 4(B) are timing charts of partial control constants and engine speed. FIGS. 5A and 5B are diagrams showing idle control constants and partial control constants. 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 C0II adjustment register, 36 is a water temperature sensor, 38 is an intake air temperature sensor, 40 is a throttle sensor, 4
2 is a vehicle speed sensor, 44 is a battery, and 46 is an idle switch. Figure 3

Claims (1)

[Claims] 1. In a fuel control device for an internal combustion engine that performs feedback control of fuel to a predetermined air-fuel ratio using control constants set according to the operating range of the internal combustion engine, when the vehicle speed of a vehicle equipped with the internal combustion engine is zero, When the engine shifts from the idle operating region to the partial operating region, the fuel is feedback-controlled to a predetermined air-fuel ratio using a partial control constant for a predetermined period of time from the time the engine shifts to the partial operating region, and after the predetermined period of time has elapsed. A fuel control device for an internal combustion engine, comprising a control means for feedback controlling the fuel to a predetermined air-fuel ratio using a control constant that is smaller on the idle control constant side than the partial control constant.