JPH02233842A - Air-fuel ratio controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent any engine stall from occurring by using an idle map which checks a supply of exhaust gas recirculation to an intake system consisting of preset intake pipe pressure, engine speed and idle opening by a throttle sensor, at time of idling of an internal combustion engine. CONSTITUTION:An internal combustion engine 2 sets an EGR value control map to a control part 66 by engine speed Ne by a speed sensor and intake pipe pressure Rm by a pressure sensor 74 at a fuel injection control map, and adjusts an EGR value by this EGR valve control map, thereby controlling an air-fuel ratio. Then, an idle control map is preset to the control part 66 by those of engine speed Ne, intake pipe pressure PM and idle opening by a throttle sensor 72, and it controls the air-fuel ratio to keep off any leanness at time of warming up after cold starting with the idle control map as checking a supply of exhaust gas recirculation to an intake system at time of idling of the engine 2. With this constitution, any drop in idling speed is checked, and the air-fuel ratio is properly controlled.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an air-fuel ratio control device for an internal combustion engine, and in particular sets an EGR amount control map in a fuel injection control map based on intake pipe pressure and engine speed, The present invention relates to an air-fuel ratio control device for an internal combustion engine that controls the air-fuel ratio by adjusting the EGR amount using this EGR amount control map.

[Conventional technology Internal combustion engines for vehicles have extremely large fluctuations in vehicle running speed, that is, engine rotational speed, and load, and under various operating conditions that combine these two fluctuation factors, performance such as low fuel consumption and low back-harming exhaust gas can be achieved. is requested. Therefore, it is necessary to maintain an appropriate air-fuel ratio under various operating conditions.

Further, some air-fuel ratio control is disclosed in Japanese Patent Laid-Open No. 83-100248. The air-fuel ratio control device for an internal combustion engine disclosed in this publication detects the operation of an exhaust gas recirculation device, and uses constant variation means to detect the operation of the exhaust gas recirculation device until a predetermined period of time elapses after the exhaust gas recirculation device starts operating or stops operating. ,
At least one of the integral constant and the skip constant used in the correction coefficient updating means is changed to a value larger than normal, and even if the air-fuel ratio temporarily deviates greatly from the target air-fuel ratio, the air-fuel ratio is quickly returned to the target air-fuel ratio, and the response is significantly improves sex.

[Problems to be Solved by the Invention] By the way, in a conventional air-fuel ratio control device for an internal combustion engine, an EGRffi control map is set in the fuel injection control map for the internal combustion engine based on intake pipe pressure and engine speed, and The fuel injection control map and EGR
The fuel injection amount and EGRi are adjusted using a quantity control map to control the air-fuel ratio.

However, during idling operation during warm-up after a cold start of the internal combustion engine, a predetermined amount of EGR is supplied to the intake system according to the above-mentioned EGR amount book map, and the fuel injection amount is reduced by supplying this EGRffi. .

As a result, the air-fuel ratio becomes leaner than necessary due to a decrease in the amount of fuel injection, resulting in a decrease in output and idle speed, an increase in the amount of harmful exhaust gases such as NOx, and an engine stall. This has the disadvantage of being a practical disadvantage.

[Objective of the Invention] Therefore, an object of the present invention is to provide a throttle sensor for detecting the throttle opening of the internal combustion engine in order to eliminate the above-mentioned inconvenience, and to adjust the intake pipe pressure and engine rotation speed to preset values during idling operation of the internal combustion engine. A control unit that controls the air-fuel ratio to prevent lean during warm-up after a cold start, using an idle control map that prevents the supply of EGR to the intake system, which is based on the idle opening determined by the throttle sensor and the idle opening determined by the throttle sensor. By providing an idle control map, it is possible to prevent the idle speed from becoming lean during warm-up operation after a cold start, prevent the idle speed from decreasing, and control the air-fuel ratio appropriately, reducing harmful exhaust gas emissions. In addition to reducing the amount of damage caused by engineering, it also reduces industrial engine stalls. An object of the present invention is to realize an air-fuel ratio control device for an internal combustion engine that can avoid the occurrence of air leakage.

[Means for solving the problem] In order to achieve this object, the present invention sets an EGR amount control map based on intake pipe pressure and engine speed in the fuel injection control map of the internal combustion engine, and sets this EGR amount control map. In an air-fuel ratio control device for an internal combustion engine that controls an air-fuel ratio by adjusting an EGR amount, a throttle sensor for detecting a throttle opening of the internal combustion engine is provided, and the intake pipe pressure is set in advance during idling operation of the internal combustion engine. The system uses an idle control map that prevents the supply of EGR to the intake system, which is based on the engine speed and idle opening determined by the throttle sensor, and controls the air-fuel ratio to prevent lean during warm-up after a cold start. The present invention is characterized in that it is provided with a control section that performs the following operations.

[Function] As described above, when the internal combustion engine is warmed up after a cold start, the idle control map prevents the internal combustion engine from becoming lean during warm-up after a cold start. This prevents the idle speed from dropping, appropriately controls the air-fuel ratio, reduces harmful exhaust gas emissions, and prevents engine stalls.

[Examples] Examples of the present invention will be described in detail below based on the drawings.

1 to 5 show embodiments of this invention. Second
In the figure, 2 is an internal combustion engine, 4 is an intake passage, and 6 is an exhaust passage. The first intake passage 4- in the upstream part of the intake passage 4
An air cleaner 8 is provided on the upstream side of the first air cleaner 8.
A second intake passage 4-2 formed in a throttle body 12 including an intake throttle valve 10 communicates with the downstream side of the intake passage 4-1. A surge tank 14 is connected to the throttle body 12, and the inside of the surge tank 14 communicates with a third intake passage 4-3 formed in the intake manifold 1e. The downstream end of the third intake passage 4 - 3 communicates with the combustion chamber 20 of the internal combustion engine 2 via the intake valve 18 .

This combustion chamber 20 is provided with a spark plug (not shown), and communicates with the upstream side of the exhaust passage 6 via an exhaust valve 22. Further, in the upper part of the internal combustion engine 2, a first intake passage 4 is provided.
-1 are in communication with blow-by gas passages 24, respectively. A fuel injection valve 26 is mounted on the intake manifold 16 so as to be oriented toward the combustion chamber 20 . The fuel in the fuel injection valve 26 is guided to the fuel supply pipe 30 by the driving of the fuel pump 28, and the fuel in the fuel tank 32 is fed under pressure. A fuel filter 3 is provided in the middle of the fuel supply pipe 30.
4 is interposed therebetween, and a pressure adjustment passage 36 is provided, which communicates at one end and opens into the fuel in the fuel tank 32 at the other end. A fuel pressure regulator 38 for regulating the pressure of fuel acting on the fuel injection valve 28 is interposed in the middle of the pressure regulation passage 36.

The second intake passage 4 - 2 of the throttle body 12 and the fuel tank 32 are communicated through an evaporated fuel passage 40 . The vaporized fuel passage 40 includes a second intake passage 4
A canister 42 and a two-way valve 44 are interposed in order from the -2 side.

The second intake passage 4-2 and the inside of the surge tank 14 are communicated through an idle-up passage 4θ that bypasses the intake throttle valve 10.

In this idle up passage 46, first and second idle up control wells 48 and 50 are provided in parallel. 1st
The idle-up control well 48 increases the amount of air to increase the idle rotation speed by forming the idle-up passage 46 into a σU when idle-up is required, such as when starting, at high temperatures, or when the electrical load increases. The second idle-up control valve 50 opens the idle-up passage 46 when an AC switch 82 (described later) is turned on, increases the amount of air, and increases the idle speed.

Further, an advance pressure introduction passage 58 for introducing pressure to a vacuum controller 56 attached to a distributor 54 of an ignition mechanism 52 is opened in the second intake passage 4-2. The ignition mechanism 52 distributes and supplies the high voltage generated by the ignition solenoid coil 60 to an ignition plug (not shown) using a distributor 54 to cause sparking. An exhaust passage 6 is provided in the third intake passage 4-3 of the intake manifold 16.
An EGR passage 62 is provided with an opening at the beginning and an opening at the end. This EGR passage 62 includes an EGR valve 64 which is controlled to open and close in order to adjust the amount of EGR to the third intake passage 4-3.
is provided.

The fuel injection valve 26, fuel bomb 28, eye/L/7
The buffer control well 50 and the ignition coil 60 are each connected to a control section 66. The control unit 66 includes a water temperature sensor 70 that detects the temperature of cooling water in a cooling water passage 68 provided in the intake manifold 16 to warm intake air;
A throttle sensor 72 that detects the throttle opening state of the intake throttle valve 10 of the throttle body 12, and a pressure sensor 7 that detects the intake pipe pressure in the surge tank 14.
4 is connected.

Note that 76 is a battery, 7.8 is a main switch, and 8 is a battery.
0 is a thermo fuse, and 82 is an AC switch for the air conditioner.

During idling operation of the internal combustion engine 2, the control unit 66 controls the EG to the intake system, which is comprised of a preset intake pipe pressure and an idling opening degree determined by an engine speed throttle sensor.
An idle control map that blocks the supply of R is used to control the air-fuel ratio to prevent lean during warm-up operation after a cold engine start.

More specifically, as shown in FIG. 3, the internal combustion engine 2 uses the engine rotational speed NE (rpm) determined by a rotational speed sensor (not shown) and the intake pipe pressure P determined by a pressure sensor 74 in a fuel injection control map. (a+mllg) and a lot of EGRf
The fi control map is set in the control unit 66, and the EGR amount is adjusted using this EGR amount control map to control the air-fuel ratio.

Then, as shown in FIG. 3, an idle control map is created in advance by the control unit based on the engine speed Nε (rl)m), the intake pipe pressure P n (mmHg) detected by the pressure sensor 74, and the idle opening THR detected by the throttle sensor 72. 66, and prevent the supply of EGR to the intake system during idle operation of the internal combustion engine 2, and use the idle control map to prevent the air-fuel ratio from becoming lean during warm-up operation after a cold start. It is something to control.

Next, the operation of the air-fuel ratio control flowchart of the air-fuel ratio control device for the internal combustion engine 2 shown in FIG. 1 will be explained.

The operating state of the internal combustion engine 2 is detected by the throttle sensor 72, and this detection signal is input to the control unit 6G to determine whether the throttle opening is the idle opening (100)
If the determination (100) is NO, injection control is performed using the normal map (102).

In other words, as shown in FIG. 4, the engine rotation speed NE (rpm) (f02-1) measured by a rotation speed sensor (not shown)
and intake pipe pressure PN (mmHg) measured by pressure sensor 74
(102-2), the basic injection amount (102-3) is determined, and the air-fuel ratio is controlled using the fuel injection control map (see FIG. 3), which is a normal map.

In addition, the engine rotation speed N is determined by a rotation speed sensor (not shown).
E (rlm) and intake pipe pressure P measured by pressure sensor 74
For the numerical value n (mmHg), a predetermined amount of EGRm is also supplied to the intake system according to the EGR amount control map. At this time, the fuel injection amount when the EGR amount is supplied is reduced in order to maintain the air-fuel ratio appropriately.

If the above judgment (100) is YES, injection control is performed using a separate map that does not include EGR (104).

More specifically, as shown in FIG. 5, the engine rotation speed Nt. is detected by a rotation speed sensor (not shown). (rpm) (1
04-1) and intake pipe pressure PM by pressure sensor 74
(mmHg) (!04 2) and the idle opening THR (104-3) determined by the throttle sensor 72 to determine the injection amount exclusively for idle operation, and determine the air-fuel ratio by using the idle control map (see Figure 3), which is a separate map. control.

Then, the control section 66 controls the E to the intake system in the shaded area in FIG. 3, for example, during warm-up operation after a cold start.
The supply of GR is blocked and EGR is turned on to maintain the air-fuel ratio properly. The amount of fuel injected is increased compared to when it is supplied.

As a result, when the internal combustion engine 2 is idling, the control section 66 increases the fuel injection amount based on the idle control map compared to when EGR is being supplied, thereby preventing the air-fuel ratio from becoming leechy during warm-up operation after a cold start. It is possible to prevent the idle speed from decreasing, the air-fuel ratio can be properly controlled, the amount of harmful exhaust gas can be reduced, and the occurrence of engine stall can be avoided, which is advantageous in practice.

[Effects of the Invention] As described in detail above, according to the present invention, a throttle sensor is provided to detect the throttle opening of the internal combustion engine, and when the internal combustion engine is idling, the preset intake pipe pressure, engine speed, and throttle sensor are provided. We have installed a control unit that controls the air-fuel ratio to prevent lean during warm-up after a cold start, using an idle control map that prevents the supply of EGR to the intake system based on the idle opening. ,
The idle control map increases the amount of fuel injected compared to when EGR is supplied, prevents the engine from accelerating during warm-up after a cold start, prevents the idle speed from decreasing, and properly controls the air-fuel ratio. As a result, the amount of harmful exhaust gases emitted can be reduced, and the occurrence of engine stall can be avoided.

[Brief explanation of the drawing]

1 to S show embodiments of the present invention, FIG. 1 is a flowchart for air-fuel ratio control of an air-fuel ratio control device for an internal combustion engine, FIG. 2 is a schematic diagram of the air-fuel ratio control device for an internal combustion engine, and FIG. is a diagram showing each control map set based on intake pipe pressure and engine speed, Figure 4 is an explanatory diagram showing air-fuel ratio control during normal operation of the internal combustion engine, and Figure 6 is an illustration showing the air-fuel ratio control during idling operation of the internal combustion engine. FIG. 3 is an explanatory diagram showing air-fuel ratio control. In the figure, 2 is an internal combustion engine, 4 is an intake passage, 4-1 is a first intake passage, 4-2 is a second intake passage, 4-3 is a third intake passage, 6 is an exhaust passage, 8 is an air cleaner, 10 is the intake throttle valve, 12 is the throttle body, 14 is the surge tank,
16 is an intake manifold, 18 is an intake valve, 20 is a combustion chamber,
22 is an exhaust valve, 24 is a blow-by gas passage, 26 is a fuel injection valve, 28 is a fuel pump, 30 is a fuel supply pipe, 32 is a fuel tank, 34 is a fuel filter, 36 is a pressure adjustment passage, 38 is a fuel pressure adjustment 40 is a passage for vaporized fuel, 4
2 is a canister, 44 is a two-way valve, 46 is an idle up passage, 48 is a first idle up control valve, 50 is a second
Idle up control valve, 52 is an ignition mechanism, 54 is a distributor, 5G is a vacuum controller, 58 is an advance river pressure introduction passage, GO is an ignition coil, 62
is the EGR passage, e4 is the EGR valve, 66 is the control unit, 6
8 is a cooling water passage, 70 is a water temperature sensor, -72 is a throttle sensor, 74 is a pressure sensor, 76 is a battery, 78 is a main switch, 80 is a thermo fuse, and 82 is an AC switch for the air conditioner. Patent Applicant Suzuki Motor Co., Ltd. Representative Patent Attorney Yoshimi Saigo Figure 1 Figure 3

Claims (1)

[Claims] 1. Set the EGR amount control map based on the intake pipe pressure and engine speed in the fuel injection control map of the internal combustion engine.
In an air-fuel ratio control device for an internal combustion engine that controls an air-fuel ratio by adjusting an EGR amount based on a GR amount control map, a throttle sensor for detecting a throttle opening of the internal combustion engine is provided, and a throttle sensor configured in advance when the internal combustion engine is idling is provided. In order to prevent lean operation during warm-up after a cold start by using an idle control map that blocks the supply of EGR to the intake system, which is based on the intake pipe pressure, engine speed, and idle opening determined by the throttle sensor. 1. An air-fuel ratio control device for an internal combustion engine, comprising a control section for controlling an air-fuel ratio.