JPS62113843A - Fail control device for vehicle equipped with internal combustion engine - Google Patents

Abstract

PURPOSE:To ensure proper engine action in no relation to abnormality, by inputting a fail value, set by a fail value setting means, to a corresponding action control means in place of the output of a temperature detecting means, when its abnormality is discriminated. CONSTITUTION:An internal-combustion engine 1 has a temperature detecting means 2, which detects an engine temperature condition, and plural action control means 3a, 3b which input a temperature signal of said means 2 to control different action control units in a vehicle. Here the engine provides each fail value setting means 4a, 4b which sets a fail value of temperature, when the temperature detecting means 2 is in abnormality, so as to be suitable respectively for the action control means 3a, 3b. And the engine is controlled so as to connect the temperature detecting means 2 with each action control means 3a, 3b by switching means 6a, 6b, when a fail condition discriminating means 5 discriminates the temperature detecting means 2 to be normal, while each setting means 4a, 4b with each action control means 3a, 3b when abnormality is discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fail control device for a vehicle that performs engine control such as idle rotation control and air-fuel ratio control based on a signal from a water temperature sensor.

[Conventional technology]

In a vehicle equipped with an internal combustion engine, idle rotation control or air-fuel ratio control may be controlled in accordance with engine temperature such as water temperature. Therefore, a water temperature sensor is attached to the engine, and a signal corresponding to the water temperature can be obtained. In order to maintain the idle speed and air-fuel ratio within appropriate ranges when the water temperature sensor malfunctions, a fail device is installed that fixes the water temperature signal at a certain level when an abnormality is detected in the water temperature sensor.

[Problem that the invention seeks to solve]

Conventionally, the fail value that is fixed when the water temperature sensor is abnormal has been a common value even when there are multiple engine control devices based on water temperature (for example, an idle speed control device and an air-fuel ratio control device). Therefore, it has been difficult to adapt the operation in the event of a failure between each control device. For example, regarding the idle speed control device and the air-fuel ratio control device, the fail value of the water temperature sensor is fixed to the water temperature (for example, 80° C.) when the engine is assumed to have warmed up. In the air-fuel ratio control device, fuel increase correction is performed according to the water temperature (the smaller the water temperature, the more the correction amount increases), but by fixing the fail value to a value equivalent to warm-up with a high water temperature, it is possible to prevent the water temperature from increasing due to an abnormality. Even if the sensor output is locked at a low temperature level, no fuel is added, so the air-fuel ratio is maintained at an appropriate level.

However, if the fail value is fixed to a value equivalent to the water temperature after warm-up, the first idle will not be effective for the idle speed control device even when the engine temperature is low. This is because the idle speed is set to be higher as the water temperature is lower, but the fail value is fixed at higher water temperatures. Therefore, there is a problem in that the first idle is not fast and the starting performance is deteriorated.

The above are problems when using both the idle speed control device and the air-fuel ratio control device, but other engine control devices (such as advance angle control device, electronically controlled transmission, knocking control device, supercharger control device, etc.) This problem arises when a water temperature sensor (air intake control device, air intake control device) is provided and the fail value of the water temperature sensor is made common.

[Means for solving problems]

In FIG. 1, an internal combustion engine 1 is operated by a temperature sensing means 2 for sensing engine temperature conditions and a signal representative of the temperature from the temperature sensing means 2, and a plurality of operations are performed to control different operating control devices of the vehicle. It has control means 3a and 3b. The fail control device of the present invention includes separate fail value setting means 4a and 4b for setting the fail value of the temperature of the temperature detecting means 2 at the time of abnormality so as to be compatible with the respective operation control devices 3a and 3b, and the temperature detecting means. 2
A fail condition determining means 5 is connected to the temperature sensing means to determine whether or not the temperature sensing means is operating abnormally, and when the temperature sensing means is in normal operation, the temperature sensing means 2 is connected to each operation control means 3a and 3b, and the fail condition determining means 5 is connected to the operation control means 3a and 3b. When the temperature detection means 2 determines that there is an abnormality, the respective fail value setting means 3a, 3b
and switching means 6a and 6b for performing a switching operation so as to connect the respective operation control means 4a and 4b to the corresponding operation control means 4a and 4b.

[For production]

When the fail condition determining means 5 detects an abnormality in the temperature detecting means, the fail value setting means 4a and 4b are connected to the respective engine operation control means. Therefore, each engine operation control means 3a, 3b has its own fail-safe control unit.

〔Example〕

FIG. 2 shows the configuration of an embodiment of this invention, with 10
is the engine body, 11 is the intake pipe, 12 is the nage tank,
13 is a throttle valve, 14 is an air flow meter, 15 is a distributor, and 16 is a fuel injector.

A bypass passage 18 is provided to bypass the throttle valve 13, and an idle speed control valve (ISC valve) 19 as a bypass flow rate control valve is disposed in the bypass passage 18.

Although there are various types of ISC valves 19, such as a rotary type and a step motor type, in this embodiment, for convenience, a case will be described in which the ISC valve is constructed as an on-off valve driven by a duty signal. Of course, it goes without saying that it can be applied to other types as well.

The control circuit 21 is configured as a microcomputer system. The control circuit 21 has a microprocessing unit (MPU) 22, a memory 23, an input port 24, an output port 25, and a bus 26 connecting these as basic components.

The air flow meter 14 is connected to the input port 24, and a signal corresponding to the intake air amount Q is input thereto.

Note that the present invention can also be applied to a device that uses an intake pipe pressure sensor instead of an air flow meter. A throttle sensor 28 is installed on the valve shaft of the throttle valve 13. The throttle sensor 28 is connected to the input port 24, and receives a signal corresponding to the throttle valve opening.

The crank angle sensors 29 and 30 are the distributor 1
It is provided so as to face the detection pieces 15b and 15C on the distribution shaft 15a of No. 5. The crank angle sensor 29 generates a pulse signal G every 720° (engine-revolution) of the crankshaft, while the crank angle sensor 30 generates a pulse signal G every 720° (engine-revolution) of the crankshaft.
A pulse signal N is generated every time. Crank angle sensor 29
, 30 are connected to the input port 24, and signals G and N are input thereto. The water temperature sensor 32 is installed in the water jacket of the engine body 10. The water temperature sensor 32 is connected to the input port 24, and receives a signal T)IW corresponding to the water temperature.

The output port 25 is connected to the injector 16 and receives a fuel injection signal output from the control circuit 21.

Next, the operation of the control circuit 21 will be explained with reference to flowcharts shown in FIGS. 3 to 5. A program that implements this flowchart is stored in the memory 23.

FIG. 3 shows a fail control routine, which can be a time interrupt routine executed at predetermined intervals. In step 50, AD conversion of the water temperature signal TIIW from the water temperature sensor 32 is executed. AD conversion is performed by an AD converter (not shown) connected to the human power port 24. In step 52, it is determined whether or not the actually measured water temperature Tl+- is smaller than the upper limit value UPLMT, and in step 54, the water temperature T)l- is determined as the lower limit value LWLM.
It is determined whether or not it is larger than T. In steps 52-54, the measured value of the water temperature sensor is within the normal operating range (LWLMT).
-UPLMT). If the water temperature sensor 32 is working normally, step 5
2, the process proceeds to step 56 from 54, where TI- is stored in the memory area for storing the water temperature data THWEFI used in the air-fuel ratio control routine, and then the process proceeds to step 58,
[Water temperature data THWI used in the SC valve control routine
TH- is stored in the memory area that stores SC.

If the water temperature sensor 32 is abnormal, the measured value exceeds the upper limit or falls below the lower limit, so step 50 or step 5
2, proceed to step 60, and set the air-fuel ratio control water temperature value THW.
Water temperature value after engine warm-up (e.g. 80℃) as EFI
Then, in step 62, a water temperature value when the engine is cold (for example, 0° C.) is entered as the ISO valve control water temperature value THWISC.

In step 64, a fail processing routine is executed,
For example, an alarm device is activated.

FIG. 4 shows a fuel injection routine, which is started when the crank angle sensors 29 and 30 detect a predetermined crank angle before the fuel injection timing. In step 66, the basic fuel injection amount 'rp is determined by Tp=(Q/N)xk. Here k is a constant. In the next step 68, a correction amount FWL of the fuel injection amount according to the water temperature is calculated. That is, the water temperature correction of the fuel injection amount is set to the characteristic shown in FIG. 6(a), which decreases as the water temperature increases. That is, FWL decreases as the temperature increases, reaches zero at the water temperature at complete warm-up (for example, 80° C.), and is not corrected at temperatures above this temperature. A map corresponding to this characteristic is stored in the memory 23 as the water temperature T) IWEFI for air-fuel ratio control.
It is set against. The MPU 22 executes a computation to supplement the water temperature correction amount FWL with respect to the actually measured water temperature THEFT.

In step 70, the fuel injection amount TAll is determined as TAU=T
It is calculated by p (1+F note)α+β. By including the water temperature increase amount FWL, temperature correction of the fuel injection amount is performed. α and β representatively represent other correction coefficients and correction amounts whose explanations are omitted because they are not directly related to the present invention.

In step 72, data on the fuel injection amount TAU is output, a fuel injection signal is output from the output port 25 to the fuel injector 16, and fuel injection is executed.

FIG. 5 shows a control routine for the ISC valve 19. This routine is a time interrupt routine that is executed at predetermined time intervals. In step 74, it is determined whether the engine is in an idling condition based on the engine rotational speed N obtained by processing the throttle valve opening signal from the throttle sensor I3 and the crank angle signal from the crank angle sensor 30 by a routine (not shown). When the engine is not in idle operation, the following routine is bypassed, and therefore the ISC valve is not controlled.

If it is determined that the vehicle is idling, the process proceeds to step 76;
A map calculation of the idle speed is executed. That is, the sixth
As shown in Figure (o), the idle speed is set to decrease as the water temperature increases.

For example, at 0° C., the engine speed is set to 11,000 rpm, and after warming up, the engine speed is set to a predetermined idle speed, for example, 700 rpm.

A map of the set idle rotation speed Nl5C with respect to the ISC valve control water temperature Tnwrsc is assembled in the memory.

The MPU 22 executes a map calculation of the set rotation speed with respect to the actually measured water temperature.

In step 78, the set value N15C of the idle rotation speed is compared with the actual value N. If the set value is larger than the actual value, the process proceeds to step 80, where the duty ratio DUTY in the drive signal corresponding to the opening degree of the ISC valve 9 is incremented. Therefore, the idle speed is increased towards the set value. On the other hand, if the actual value is larger than the set value, the process proceeds to step 82, where the duty DUTY is decremented. Therefore, the idle speed is reduced toward the set value. If there is substantially no difference between the set value and the measured value, the process proceeds to step 84, and the duty ratio DUTY is maintained as is.

In step 86, the duty signal is output from the output port 25 to the ISC valve 19, and the opening degree of the ISC valve becomes the opening degree corresponding to the duty ratio, and a bypass flow rate corresponding to this is obtained. Therefore, the idle rotation speed is feedback-controlled to a value set according to the water temperature.

In this embodiment, the fail value when the water temperature sensor is abnormal is set separately for a system equipped with an idle speed control device using an ISC valve and a fuel injection type air-fuel ratio control device. Specifically, the fail value for the air-fuel ratio control device is set to 80° C., which corresponds to warm-up, while the fail value for ISC valve control is set to 0° C., which corresponds to cold. Conventionally, a common value was set for ISC valve control and air-fuel ratio control, for example, 80° C., which corresponds to warm-up.

Setting the fail value to 80℃, which is equivalent to warm-up, is to increase fuel f during warm-up, assuming that the water temperature sensor has become abnormal.
This is to prevent iFWL from being executed and to properly control the air-fuel ratio without making it overrich. However, when looking at ISC valve control, the water temperature is fixed at 80 degrees Celsius, which is equivalent to warming up the engine, so there is a problem in that the first idle is not activated, making it difficult to start the engine. In contrast, in the present invention, separate fail values are set for air-fuel ratio control and ISC valve control. That is, regarding the control of the ISC valve, when the water temperature sensor is abnormal, 0° C. is entered as a fail value, so a fast idle is performed, so a stable start can be obtained.

In the embodiment, a combination of an air-fuel ratio control device and an ISC valve control device has been described, but the present invention can also be applied to combinations of other engine control devices. In other words, the scope of the present invention includes a plurality of engine control devices that are operated by signals from temperature sensors and that sets the fail value when the temperature sensor is abnormal to the optimum value for each control device. It is something.

The table below shows high and low fail values for various vehicle control factors.
This is a summary of the problems when setting as a seed, and which fail value should be selected, high or low, in view of the problems.

Margins below [Effects of the Invention] By setting different fail values suitable for each control device as fail values when the temperature sensor is abnormal, it is possible to obtain proper engine operation when the temperature sensor is abnormal.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the present invention. FIG. 2 is a diagram showing an embodiment of the invention. 3 to 5 are flowcharts illustrating the operation of the control circuit. FIG. 6 is a diagram showing the setting of fuel increase and idle speed with respect to water temperature. DESCRIPTION OF SYMBOLS 10... Engine body, 13... Throttle valve, 14... Air flow meter, 16... Fuel injector, 18... Bypass passage, 19... ISC valve, 25... Control circuit, 28 ... Throttle sensor, 29, 30... Crank angle sensor, 32... Water temperature sensor.

Claims (1)

[Scope of Claims] Temperature detection means for detecting temperature conditions of an internal combustion engine; and a signal operated by a signal representative of the temperature from the temperature detection means,
In a vehicle having respective operation control means for controlling different operation control devices of the vehicle, separate fail values are set to suit each operation control device as temperature fail values when the temperature detection means is abnormal. a setting means; a fail condition determining means connected to the temperature detecting means to determine whether the temperature detecting means is under an abnormal operating condition; and a fail condition determining means connected to the temperature detecting means to each operation control means during normal operation; A fail control device for a vehicle equipped with an internal combustion engine, comprising switching means for connecting each fail value setting means to a corresponding operation control means when the means determines that the temperature detection means is abnormal.