JPS6176738A - Air-fuel ratio control device in internal combustion engine - Google Patents

Abstract

PURPOSE:To sustain suitable emission, output power, fuel consumption, etc., by providing an abnormality detecting means for detecting an abnormality in an engine temperature detecting means, and a temperature setting means for setting the temperature of the engine when the above-mentioned abnormality is detected. CONSTITUTION:A supply amount controlling means III sets the amount of supply fuel in accordance with data detected by an engine temperature detecting means I and an intake-air amount detecting means II. An abnormality detecting means IV detects an abnormality in the engine temperature detecting means I. There is provided a temperature setting means V for setting the temperature of the engine instead of data detected by the engine temperature detecting means I when the abnormality detecting means IV detects an abnormality. With this arrangement it is possible to sustain suitable emission, output power, fuel con sumption, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air-fuel ratio control device for an internal combustion engine, and more particularly to an air-fuel ratio control device for compensating for abnormalities in internal combustion engine temperature detection means.

[Conventional technology] In recent years, it has been possible to improve exhaust gas purification performance, improve fuel efficiency, or increase output by precisely controlling the amount of fuel supplied based on intake air amount and other data and adjusting the air-fuel ratio to a target air-fuel ratio. A control device for an internal combustion engine is used. In order to precisely control the air-fuel ratio mentioned above, not only the intake air amount but also data on other engine conditions are important factors, but especially when starting an internal combustion engine, the influence of engine temperature data on the air-fuel ratio is big. Therefore, a configuration is generally adopted in which a sensor is provided to detect the temperature of the cooling water of the internal combustion engine, for example, and the amount of fuel supplied is adjusted according to the output from the sensor.

However, if no compensation is taken when the above-mentioned temperature sensor malfunctions, it will not be possible to take into account differences in the evaporation state of fuel due to temperature, and even if the amount of fuel supplied is the same, the air-fuel ratio will change. This caused a negative impact on engine stability, exhaust gas, and output during warm ocean conditions. Particularly in cold regions, the air-fuel ratio could become over lean, making it impossible to start or run.

Therefore, such iI [JP-A-54-141926 and JP-A-55-543 to compensate for sensor abnormality is proposed.
Techniques such as No. 3 have been proposed. When an abnormality is detected in the temperature sensor, these provide a fixed value to the air-fuel ratio control means in place of the temperature sensor output, or give the air-fuel ratio control means a value depending on the status of other sensors.

[Problem to be Solved by the Invention 1] However, since the output values given when these temperature sensors are abnormal are only one or two, it is not possible to correspond to the actual engine temperature in a wide range, and the output and emissions are Alternatively, maintenance of driving performance, stability, etc. was insufficient.

Means 1 for Solving the Problems The present invention employs the following means to solve the above problems.

That is, the air-fuel ratio control device for an internal combustion engine of the present invention includes a temperature detecting means, an intake air amount detecting means, and a supply amount control system that sets the fuel supply 1 based on the data detected by both of the above means. In the air-fuel ratio control device for an internal combustion engine, the air-fuel ratio control device for an internal combustion engine is further provided with an abnormality detecting means (V) for detecting an abnormality in the above-mentioned gateway temperature detecting means; For the supply amount f111 ul1 means (■), instead of the data detected by the engine temperature detection means, the internal combustion engine The engine is characterized in that it includes a temperature setting means V that sets the engine temperature according to the number of rotations.

[Operation] Here, the engine temperature detection means refers to a sensor or the like that detects the temperature of the internal combustion engine, such as the cooling water temperature or oil temperature of the internal combustion engine. The intake air amount detection means refers to a sensor that detects the amount of air sucked into the internal combustion engine, such as an air flow meter or an intake pressure sensor. The fuel supply is set by an electronic circuit that controls the supply opening.

It is composed of a computer, etc., and functions to set the basic fuel range based on the intake air amount, and to correct the basic fuel amount by m1 based on the engine temperature data. As a result, fuel atomization can be adjusted in response to changes in engine temperature, and the air-fuel ratio can be maintained at a predetermined air-fuel ratio. The abnormality detection means detects an abnormality in the engine temperature detection means.The abnormality detection means detects a failure in the engine temperature detection means and detects an abnormal output,
For example, means consisting of an electronic circuit or computer that detects when an engine temperature that is too high or too low to normally occur, or when the output stops completely, and determines that it is abnormal.

What is the temperature setting means for setting the engine temperature? When the above-mentioned abnormality detection means detects an abnormality, the temperature of the internal combustion engine increases according to the temperature change pattern that can naturally occur depending on the total number of revolutions or elapsed time since starting. Means consisting of an electronic circuit or computer that predicts and sets the engine temperature for the control means. This temperature change pattern has a minimum at the time of engine startup, gradually reaches an upper limit as the engine starts, and normally reaches equilibrium at about 80''C.

Due to the movement of these abnormality detection means and temperature setting means, the basic fuel supply amount is calculated based on the predicted internal combustion engine temperature so that the internal combustion engine will reach a predetermined air-fuel ratio even if normal data cannot be obtained from the engine temperature detection means. It is possible to correct the fuel supply amount and control the fuel supply amount correctly.

[Example] Embodiments of the present invention will be explained below with reference to the drawings.

FIG. 2 shows a configuration diagram of an embodiment of the device of the present invention applied to an internal combustion engine of an automobile. That is, 1 is a cylinder of the engine 2, 3 is an exhaust manifold connected to the exhaust port 5 of each cylinder of the cylinder head 4, 6 is an intake manifold connected to the intake port 7 of the cylinder head 4, and the intake manifold 6 A surge tank 8 is connected to.

An air meter 70-meter 9 is connected to the surge tank 8, which detects the amount of intake air from an air cleaner (not shown).
An intake temperature sensor 10 is installed near the air flow meter 9 to detect intake air temperature. 16 is a fuel injection valve that controls the injection amount of fuel supplied from a fuel injection pipe connected to the vicinity of the tip of the intake manifold 6 on the side of the intake port 7;
17 is a throttle sensor that detects the fully open state of the throttle valve 12; the former fuel injection valve 16 is driven and controlled by the arithmetic processing circuit 14; It is connected to output to 18. 19 is an oxygen sensor that is attached to the exhaust manifold 3 and detects the amount of oxygen remaining in the exhaust gas and generates an air-fuel ratio signal; 20 is a water temperature sensor that detects the cooling water temperature of the engine 2; and 21 is a vehicle speed sensor that detects the speed of the vehicle. and are connected so as to send each detection signal to the arithmetic processing circuit 18. 24 is engine 2
The distributor is a distributor that applies high voltage to each spark plug 25 at a predetermined timing, and is connected to an igniter 26 equipped with an ignition coil controlled by an arithmetic processing circuit 18. A rotation angle sensor 27 that rotates and generates a pulse signal proportional to the rotation, and a cylinder discrimination sensor 28 that detects the top dead center of a specific cylinder are provided, and each detection signal is sent to the arithmetic processing circuit 18. It is connected.

The arithmetic processing circuit 18 is composed of a microcomputer as shown in FIG. 3, and includes a CPtJ30, a fixed memory ROM31 in which control programs and various data necessary for arithmetic processing are stored, a temporary storage RAM32, and a key switch that turns off the CPtJ30. It is equipped with a backup RAM 33 whose power is backed up by a battery so that the memory can be retained even after the memory is stored, each input/output port 34, 35, and an output port 36, 37. Each element is connected by a pass line 38, and each input/output port is The output ports 34, 35 and each output port 36, 37 are provided with direct or buffer circuits 39 to 43, multiplexers 44,
A/D converter 45, comparator 46, shaping circuit 47,
Detection signals from the various sensors and drive signals from the fuel injection valve 17 and igniter 26 are connected via drive circuits 49 and 50.

In addition, 51 in Fig. 3 indicates the CPU 30, ROM 31, and RA.
It represents a clock circuit that sends a clock IL signal, which is a control timing, to M32 etc. at predetermined intervals.

Here, to briefly explain the operation of a normal fuel injection system, first, the CPU 30 inputs the data of the intake air amount detected by the air meter 9 and the engine speed detected by the rotation angle sensor 27 to the input/output port. 34 and 35, and calculate the basic fuel injection amount from these data. Then, this basic fuel injection amount is determined by the intake air temperature sensor 10.
The actual fuel injection amount is corrected according to the intake air temperature detected by the sensor and the cooling water temperature detected by the water temperature sensor 20, and further corrected based on the residual oxygen concentration in the exhaust gas detected by the oxygen sensor 19. Calculated. and,
The fuel injection valve 17 is controlled by the arithmetic processing circuit 18 based on this actual fuel injection amount, and fuel injection is performed in accordance with the operating state of the engine 2.

Next, the processing performed in the arithmetic processing circuit 18 is performed in the fourth
This is shown in the flowchart in Figure.

FIG. 4 shows the supply fuel amount temperature correction routine.

This routine is executed after another basic fuel calculation routine based on the intake air amount (not shown).

First, when the processing of this routine is started, step 100
At , the temperature of the internal combustion engine cooling water is read as T HW based on the output of the water temperature sensor 2o. Next, in step 110, the intake air temperature is read as THA. Next, in step 120, it is determined whether or not it is time to start the engine. This determination is made based on whether the key switch is in the starter position or whether the engine speed is below a predetermined value. If it is determined that it is time to start, then step 1
30 is executed, and it is determined whether the cooling water gTHW read in step 100 above shows an abnormal value. For example, it is determined whether the value is a value that cannot normally be taken. If the water temperature data THW is abnormal here, it is determined as [YESJ] in step 130, and then in step 1
40 is executed, and the value corresponding to the intake air temperature THA read in step 110 is set as the water ITHW. In this case, THW is determined by a map of TI-(A and THW or a function based on the value of THA. For example, when starting the engine after a long-term stop, the cooling water temperature is almost the atmospheric temperature, so THA is If the THW is set as is, or if the engine has just stopped, the THW can be determined by following the pattern shown in FIG. 5, which will be described later, in the reverse direction from the time after the engine has stopped.

If the water temperature data is not abnormal in step 130, step 140 is not executed and the THW is used as is for subsequent processing.

Next, step 150 is executed and if the THW or water temperature sensor set in step 140 is not abnormal,
Based on the THW determined in step 100, one curve corresponding to the THW is selected from the backup map shown in FIG. In this case, since the engine is at an early stage of drying, a curve corresponding to the water fA(i!

For example, in the case of THW-T'C, curve BC(I> is selected. Next, step 180 is executed, and the basic fuel amount is corrected based on the already determined THW and THA. Step 180 Then, other corrections may be made at the same time.Next, in step 190, the previous step 2
From the execution of 00, it is determined whether the engine has rotated once. If it has rotated once, step 200 is executed again.
A backup water temperature search value corresponding to the elapsed time or the number of rotations based on the curve BC(1) selected in step 150 is set as BTHW(1). If it has not completed one revolution, processing can be continued directly to another routine.

On the other hand, if it is determined in step 120 that the engine has been started, then step 160 is executed, and similarly to step 130, it is determined whether the output of the water temperature sensor 20 is abnormal. If it is abnormal, step 170 is executed, the value of BTHW(1) already set in step 200 is set as THW, and then the process moves to step 18o. If the water temperature sensor 20 is normal, step 170 is not executed and step 1 is performed.
The process moves to 80, where basic fuel consumption is corrected.

That is, if the water temperature sensor 20 outputs a normal output at the time of starting, the detected water temperature data THW is used as is to correct the fuel amount. However, if the output of the water temperature sensor 2o is abnormal, the water temperature data THW is first calculated and set using data from other sensors connected to the internal combustion engine, here the intake air temperature THA, and then Using the values, one curve that changes depending on the elapsed time after startup or the number of intake rotations is selected.

Thereafter, as long as the output of the water temperature sensor 20 is abnormal, the basic fuel amount will be corrected based on the backup water mBTHW (I>) determined using the curve thus selected.

The subsequent processing moves to step 160 when it is determined in step 120 that the engine has started, and since the output of the water temperature sensor 20 is abnormal even at this point, it is determined to be rYEsJ, and step 1 is executed.
In step 70, BTHW(I> is set as the value of THW. This BTHW(I) has already been set as the backup water temperature search value in step 200 in the processing of this routine before the previous time. In this way, From then on, control will be performed using the curve selected at startup.

On the other hand, if we consider a case where there is no abnormality at the time of starting but the water temperature sensor 20 becomes abnormal after starting, the curve will be selected from THW at the time of starting in this case as well. However, since the water temperature sensor 20 is normal, its output value TH
W will be used as is in the curve search (step 130).

Then, in step 200, the backup water temperature search value searched from the above curve is held in BTHW (I>.Furthermore, after the start, in step 12
0 is followed by step 160, in this case rNO
J is determined, and then steps 180 and 190 are executed, and step 200 is also executed for each revolution of the engine, so that the backup water temperature search value is always updated and set in BTHW (I>) even after starting. become.

Thereafter, if the output data of the water temperature sensor 2o becomes abnormal, it is determined in step 160 that it is rYEsJ, and then step 170 is executed and THW is set to BTI-IW (1). BTHW(I) at this time is also the same as when there is an abnormality in the water temperature sensor 20 at the time of starting, because BTHW(I> is constantly updated based on the selected curve for each revolution of the engine after starting. BT)-IW( according to a curve close to the actual water temperature data)
1) changes. Therefore, in the next step 180, the basic fuel amount is corrected using data close to the actual water temperature.

By having the configuration as described above, this embodiment can set a fuel amount that provides an accurate air-fuel ratio even if the water temperature sensor has already failed at the time of starting or if the water temperature sensor has failed after starting. There is no adverse effect on emissions, output, fuel efficiency, etc.

In this embodiment, the water temperature sensor 20 corresponds to the engine temperature detection means, and the air 70 meter 9 corresponds to the intake air amount detection means (2). Further, the arithmetic processing circuit 18 corresponds to the supply amount control means (2), the abnormality detection means (2), and the temperature setting means (V). The process and the process of step 180 represent the process of closing the supply control means, and the process of steps 130 and 160
The processing in steps 150, 170, and 200 represents the processing as the temperature setting means V.

In this embodiment, the cooling water temperature is assumed to be based on the output of the intake temperature sensor 10 when the water temperature sensor 2o is abnormal, but if other engine oil temperature sensors or exhaust temperature sensors are installed, The cooling water temperature can be estimated from the temperature. In the case of an exhaust temperature sensor, the output before combustion is used. Alternatively, without using these sensors, it is also possible to measure the time from when the warmed-up engine stops until it restarts, and to assume that the engine is wet with the cooling water.

Also, B T HW (I > is the curve shown in Fig. 5.
In step 200, a map of the curve is selected and a search is performed while referring to the map of the curve.If it is assumed that the temperature change changes linearly, in step 200, the initial 1 of the assumed water temperature is
Once the correct value is determined, the constant value can be simply adjusted at regular intervals without searching the map, which simplifies the process and improves the processing speed.

[Effects of the Invention] The air-fuel pressure control illumination device for an internal combustion engine according to the present invention determines an abnormality in the engine temperature detection means using an abnormality detection means that detects an abnormality in the engine temperature detection means, and when an abnormality is detected, the engine temperature detection means detects an abnormality in the engine temperature detection means. Since a temperature setting means is provided to set the engine temperature based on a preset line temperature change pattern instead of the data detected by the It becomes possible to calculate the air-fuel ratio by adapting it to the machine r8A temperature, and it becomes possible to precisely control and maintain the air-fuel ratio. Therefore, it is possible to suitably maintain emissions, output, fuel efficiency, etc.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a schematic configuration diagram showing an embodiment of the invention, Fig. 3 is a block diagram of an electronic control circuit, and Fig. 4 is a process performed in the electronic control circuit. FIG. 5 shows a graph corresponding to a map showing the engine temperature change pattern. ■... Temperature detection means ■... Intake air amount detection means ■... Supply port control means IV... Abnormality detection means V... Temperature setting means 9
...Air flow meter 10...Intake temperature sensor 16.
... Fuel injection valve 18 ... Monument processing circuit 20 ...
・Water temperature sensor

Claims (1)

[Scope of Claims] 1. Air-fuel ratio of an internal combustion engine comprising: engine temperature detection means; intake air amount detection means; and supply amount control means for setting the fuel supply amount based on data detected by both of the above means. The control device further includes an abnormality detection means for detecting an abnormality in the engine temperature detection means, and when the abnormality detection means detects an abnormality, the data detected by the engine temperature detection means is transmitted to the supply amount control means. In place of the engine temperature change pattern set in advance, the engine temperature setting means is provided for setting the engine temperature according to the elapsed time from the time of startup or the number of rotations of the internal combustion engine since the time of startup. Air-fuel ratio control device for internal combustion engines. 2. The air-fuel ratio control device for an internal combustion engine according to claim 1, wherein the engine temperature change pattern is selected based on the state of the internal combustion engine at the time of startup. 3. The air-fuel ratio of the internal combustion engine according to claim 2, wherein the state of the internal combustion engine is the engine temperature if the engine temperature detection means is not abnormal at the time of starting, and is the intake air temperature if it is abnormal at the time of starting. Control device.