JPS6131647A - Engine temperature detector - Google Patents

Abstract

PURPOSE:To permit the correct fuel correction by calculating the initial value of the engine temperature on the basis of the intake-air temperature on engine start by a temperature calculating means and varying the degree of rise of the engine temperature according to the initial value, when the trouble of an engine-temperature detecting means is detected. CONSTITUTION:Fuel injection pulses at least for a fuel injection nozzle 6 are properly controlled by an operation-state control means 5 according to the output of an engine-temperature detecting means 2, and a trouble detecting means 8 for detecting the trouble of the temperature detecting means 2 is installed. When the trouble detecting means 8 detects a trouble, an engine-temperature calculating means 9 calculates the initial value of the engine temperature on the basis of the intake temperature on engine start which is detected by ansintake- temperature detecting means 4 in the engine-temperature calculating means 9, and the degree of rise of the calculated engine temperature is varied according to the initial value. Therefore, the correction control of the fuel injection pulse is carried-out similarly by the operation-state control means 5 according to the calculated engine temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine temperature detection device that detects engine temperature in order to temperature-correct fuel supply amount and the like in controlling the operating state of an engine.

<Prior art> Conventionally, when controlling the operating state of an engine, for example, when performing various controls such as fuel control, exhaust gas recirculation control (EGR control), and idle speed control (SIG control), temperature correction in these controls has been used. In order to perform this, the engine temperature is detected and used by engine temperature detection means such as a water temperature sensor and a wall temperature sensor. In other words, for example, in fuel control, the amount of fuel supplied at engine startup is set to be rich depending on the engine temperature, and is gradually reduced as the engine temperature rises, and the idle speed during warm-up is also adjusted accordingly. It is set to gradually decrease depending on the situation. Further, when the engine temperature is low, exhaust gas recirculation is not performed.

If the engine temperature detection means (sensor) that detects the engine temperature fails, there is a possibility that various controls of the engine operating state may not be performed properly.

Therefore, in response to a failure of the engine temperature detection means, as seen in Japanese Patent Laid-Open No. 59-32647, since engine startability is correlated with engine temperature, the supplied air-fuel ratio is gradually enriched when the engine is started. Set it so that
The engine temperature is determined from the air-fuel ratio when the engine starts, and the temperature rises at a constant rate after the engine starts.
Techniques have been proposed that calculate engine temperature.

First, the rate of increase in engine temperature changes depending on the initial temperature at engine startup, and when the rate of increase is set to a constant rate as in the above proposed technology, the calculated engine temperature may differ from the actual temperature. Unlike the engine temperature, there is a problem in that the temperature correction in the fuel supply amount, etc. as described above is inaccurate. In addition, in certain engines, the air tightness changes depending on the intake air temperature, so in order to correct the fuel supply amount etc. according to the intake air temperature, an intake air temperature detection means (intake air temperature sensor) is installed. The engine temperature at the time of starting the engine can be appropriately set based on this intake air temperature, and there is no need for the above-mentioned means of gradually increasing the amount of starting fuel.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides an engine temperature detection device that can appropriately calculate and determine the engine temperature in d) at the time of starting the engine and thereafter even if the engine temperature detection means fails. The purpose is to

(Structure of the Invention) The engine temperature detection device of the present invention provides an engine temperature detection device for use in an engine equipped with an engine temperature detection means, an intake air temperature detection means, and an operating state control means for correcting and controlling at least a fuel supply amount according to the engine temperature. When the failure detection means detects a failure in the engine temperature detection means, the engine temperature calculation means calculates and determines the initial value of the engine temperature based on the intake air temperature at the time of starting the engine, and also calculates and determines the initial value of the engine temperature based on the intake air temperature at the time of starting the engine. This is characterized in that the degree of rise in the temperature of the calculation engine is changed.

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention.

Engine 1 is provided with engine temperature detection means 2 for detecting engine temperature, and intake passage 3 is provided with intake air temperature detection means 4 for detecting intake air temperature. Then, the operating state control means 5 receiving the output of the engine temperature detecting means 2 corrects and controls at least the fuel injection pulse to the fuel injection nozzle 6 according to the engine temperature, thereby controlling the operating state of the engine 1 such as the amount of fuel supplied. is controlled. The operating state control means 5 includes a fuel supply device that supplies fuel to the engine 1, as well as an exhaust passage 7.
It includes control devices for controlling various operating states of the engine 1, such as an EGR device that recirculates exhaust gas into the intake passage 3 and a SIG device that adjusts the amount of intake air during idling to control the idling speed.

Further, failure detection means 8 receives the output of the engine temperature detection means 2 and detects a failure of the engine temperature detection means 2.
is set, and the signals from this failure detection means 8 and the intake air temperature detection means 4 are output to the engine temperature calculation means 9,
When the engine temperature detection means 2 fails, the initial value of the engine temperature is calculated based on the intake air temperature at the time of engine startup, and the degree of increase in the calculated engine temperature is changed according to this initial value. The detected engine temperature is supplied to the operating state control means 5 and used in place of the signal from the failed engine concentration detection means 2 to control the fuel supply system, EG'R system, SIG system, etc. .

There is a close correlation between the intake air temperature measured by the intake air temperature detection means 4 and the engine temperature at the engine stop poem, and the initial value of the calculated engine temperature calculated by the engine temperature calculation means 9 based on this intake air temperature is , approximates the engine temperature at the time of actual engine startup, and changes the degree of increase in engine temperature after engine startup according to this calculated initial value, and calculates and determines when the initial value is low compared to when it is high. By setting the degree of increase in engine temperature small, the engine temperature during warm-up also approximates the actual engine temperature, and when the engine temperature detection means 2 fails, the engine operating state is controlled according to this calculated engine temperature. Appropriate control can be performed even if the ,.

(Effects of the Invention) According to the present invention, even if it becomes impossible to control the engine operating state such as the fuel supply amount based on the engine temperature due to a failure of the engine temperature detection means, the engine temperature can be determined appropriately from the intake air temperature. Based on this calculation, the operating state of the engine can be controlled in the same manner as before the failure of the engine temperature detection means.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is an overall configuration diagram showing a specific structural example.

Facing the cooling water passage 11 of the cylinder block 1a of the engine 1, an engine temperature detection means 2 comprising a water temperature sensor 12 for detecting the engine temperature from the temperature of the cooling water is disposed. Water temperature sensor 1 of this engine temperature detection means 2
In No. 2, a failure may occur due to engine vibration or the like.

Further, an air cleaner 13, a fuel injection nozzle 6, and a throttle valve 14 are respectively provided in the intake passage 3 that supplies intake air to the engine 1 from the upstream side. An intake air temperature sensor 15 for detecting intake air temperature is installed in the intake passage 3 downstream of the air cleaner 13, and intake air temperature detection means 4 is provided therein.

Furthermore, a negative pressure sensor 16 for detecting intake negative pressure is provided in the intake passage 3 downstream of the throttle valve 14, and a throttle sensor 17 is provided for the throttle valve 14 for detecting its throttle opening.

A fuel supply passage 18 is connected to the fuel injection nozzle 6, and a fuel supply device W19 that supplies fuel to the engine 1 is configured. Further, an EGR passage 20 is provided, one end of which is connected to the exhaust passage 7 and the other end of which is connected to the intake passage 3. An EGR valve 21 is interposed in the middle of this EGR passage 20, and the EGR valve 21 A three-way solenoid 22 is provided to control the introduction of negative pressure for opening into the intake passage 3, thereby forming an EGR device 23 that introduces exhaust gas from the exhaust passage 7 into the intake passage 3. Furthermore, a bypass air passage 24 that bypasses the throttle valve 14 of the intake passage 3 is provided,
A SIG valve 25 is interposed in the middle of this bypass air passage 24, and a three-way solenoid 26 is provided to control the introduction of negative pressure for opening operation into the SIG valve 25. A SIG device 27 is configured to adjust the intake air amount and control the engine speed.

On the other hand, an ignition coil 29 is connected to a spark plug 28 provided in the engine 1, and an ignition device 30 for igniting the compressed air-fuel mixture by discharge is configured.

The fuel supply device 19, EGR device 23, SIG device 2
7 and the ignition device 30 are operated and controlled by control signals from a control unit 32, respectively. That is, a fuel injection pulse is output to the fuel injection nozzle 6 of the fuel supply device 19 to inject a predetermined amount of fuel at a predetermined time, and a three-way solenoid 22 that closes the EGR valve 2 of the EGR device 23 operates to close the valve pipe 1. An activation signal is output and a predetermined amount of exhaust gas is recirculated, and roughly speaking, S and I of SIG equipment @27
An operating signal is output to the three-way solenoid 26 that opens and closes the G valve 25 to control it to a predetermined idle speed, and an ignition signal is output to the ignition coil 29 of the ignition device 30 to ignite at a predetermined timing.

Each of the above controls is performed based on the detection of the operating state of the engine, and the control unit 32 receives a signal from the water temperature sensor 12 of the engine temperature detection means 2 and an intake temperature sensor of the intake air temperature detection means In addition to the signals from the negative pressure sensor 16 that detects the intake angle and pressure, and the signal from the throttle sensor 17 that detects the throttle opening, the engine speed and reference crank angle (
a crank angle signal from a crank angle sensor 33 for detecting cylinder discrimination); and an EGR position sensor 3 for performing position feedback control of the EGR valve 21.
4, a position signal from the SIG position sensor 35 for performing position feedback control of the SIG valve 25, and a starter switch 36 for detecting the start time.
signals are respectively input.

In addition to the above-mentioned sensors, in order to perform various other precise controls, there is also a signal from the 02 sensor that detects the supply air-fuel ratio from the concentration of exhaust components, a signal from the atmospheric pressure sensor that detects atmospheric pressure, and a signal that detects when the cooler is in use. Signals of the cooler switch to be detected and the like are input as necessary.

The control unit 32 has the function of the failure detection means 8 that receives a signal from the water temperature sensor 12 and compares the signal value with a set value to detect whether or not the water temperature sensor 12 is in a failure state. In the event of a failure, countermeasures are taken for various types of control failures, and the failure indicator lamp 37 is turned on and displayed.

The internal configuration of the control unit 32 is as shown in FIG. 33 signals are input via the waveform shaping circuit 44, and the water temperature sensor 12, intake temperature sensor 15, negative pressure sensor 16, throttle sensor 17, EGR
Position sensor 34, S'lG position sensor 35
The signals of the starter switch 36 are inputted via the A/D conversion circuit 45, and the signal from the starter switch 36 is inputted via the switch input circuit 46.

The main processing unit 41 calculates basic control amounts for fuel, ignition, EGR, and SIG based on the engine temperature measured by the negative pressure sensor 16 and the engine rotation speed measured by the crank angle sensor 33, The data is corrected based on engine humidity, etc., and then used in each drive circuit 47 to
50 and the fuel injection nozzle 6 of the fuel supply device 19;
Control signals are output to the ignition coil 29 of the ignition device 30, the three-way solenoid 22 of the EGR device 23, and the three-way solenoid 26 of the SIG device 27, respectively, to perform predetermined fuel control, ignition control, EGR control, and STG control. .

On the other hand, the failure determination unit 42 receives a water temperature signal from the water temperature sensor 12, and this signal is set at a preset upper limit T.
It is determined whether or not the water temperature sensor 12 is within the range between max and lower limit Tm1n, and if a malfunction occurs such as a short circuit or disconnection of the water temperature sensor 12, the malfunction countermeasure unit 43 detects the intake temperature sensor 1 at the time of starting the engine.
The initial value of the engine temperature is calculated based on the intake air temperature according to No. 5, and the time constant τ (τ=temperature/time) that determines the degree of temperature rise after engine startup is calculated based on this initial value. Correspondingly, an engine temperature value that increases over time is calculated. The calculated engine temperature data is outputted to the main processing section 41, and the main processing section 41 uses the calculated data from the troubleshooting section 43 as the engine temperature value in place of the signal from the water temperature sensor 12.
It performs various controls similar to those described above. Further, when a failure occurs, an activation signal is outputted from the failure countermeasure section 43 to the failure indicator lamp 37 via the fuel drive circuit 47 to indicate the failure.

Next, the operation of the control unit 32 will be explained using the flowchart shown in FIG. Start with power on, initialize in step S1 (flag F=O,
After turning off the lamp, water temperature sensor 1 is turned off in step S2.
2. Read various input information from the negative pressure sensor 16 and the like.

Subsequently, in step S3, it is determined whether 7 lag F is set. When this flag F is set to 1, it means that a failure has occurred in the engine temperature detection means 2, and when it is reset to 0, it means that it is operating normally. When this flag F b (O), it is determined NO in step S3, and the process proceeds to step S4, where a failure determination is performed. That is, in step S4, the input signal from the water temperature sensor 12 reaches the upper limit value T ma
In step S5, the lower limit value T mi is determined.
It is determined whether or not it is less than or equal to n, and when the determinations in both steps are NO, it is normal, and when YES, it is when a failure has occurred.

During normal operation, in step S6, the engine temperature based on the detected water temperature signal from the water temperature sensor [2] is used as control data, and based on this data, an interrupt signal 1.
2.3 is input, the fuel control (87~S
9), ignition control (S10-512), EGR control (8)
13 to 515) and SIG control (S16 to 818).

That is, it is determined in step S7 whether or not interrupt signal 1 has been output, and if YES, the process proceeds to step $8 to proceed to the fuel control routine, where control data is calculated from a map of intake negative pressure and engine speed, and engine temperature, This data is corrected based on the intake air temperature, etc., and is output to the fuel drive circuit 47 to perform predetermined fuel injection (step 89). Also, it is determined in step S10 whether or not interrupt signal 2 has been output, and if YES, the process proceeds to the ignition control routine in step S11, calculates control data from a map of intake negative pressure, engine speed, etc., and uses this data. The signal is output to the ignition drive circuit 48 and ignition is performed at a predetermined timing based on the signal from the crank angle sensor 33 (step 512).

Roughly speaking, it is determined in step 813 whether interrupt signal 3 has been output, and if YES, EGR is activated in step 814.
Proceed to the control routine and start EGR according to engine temperature etc.
It determines whether it is in the range, calculates control data from a map of intake negative pressure and engine speed, compares this data with the detection signal from the EGR position sensor 34, and outputs a signal corresponding to the difference to the EGR drive circuit 49. , ' A predetermined amount of exhaust gas is recirculated by position feedback (step 515). On the other hand, in step 816, it is determined whether or not the idle mode is set based on the throttle opening degree and the engine speed. If YES, the process proceeds to the SIG control routine in step S17, where the target idle speed is determined in accordance with the engine temperature, and the actual engine speed is determined. Control data is calculated from the difference between the two numbers, this data is compared with the detection signal from the SIG position sensor 35, a signal corresponding to the difference is output to the SIG drive circuit 5o, and the idle rotation speed is adjusted to a predetermined amount by position feedback. (Step 5)
15).

In contrast to the above-mentioned normal state, when a failure occurs in which step s4 or $5 is YES, the process proceeds to step 819, first sets flag F to 1, and then determines whether or not the engine is in a stopped state (step 520). , when stopped (YE
S) That is, when starting the engine, the intake air temperature detected by the intake air temperature sensor 15 is set as the initial value of the water temperature (engine temperature) in step 821, and a time constant of temperature rise is determined in step 822 corresponding to the initial value. continue,
After setting the calculated set water temperature value as water temperature control data (step 529) and outputting a signal to turn on the failure indicator lamp 37 (step 330), the steps 87 to 818 are performed.
Then, various controls of fuel, ignition, EGR, and SIG are performed based on the calculated engine temperature value.

If the determination in step S20 is NO and the engine is started, it is determined in step 823 whether the set water temperature is equal to or higher than the upper limit of 80°C, and if YES, the set temperature is not increased and the process proceeds to step 829. On the other hand, if the answer is No below 80°C, the set temperature is increased in steps 824-328. That is, in step 824 it is determined whether the subtraction timer is O or not, and if it is other than O (No), this timer is subtracted in step 828. When the timer reaches 0 (YE, S), a predetermined time corresponding to the time constant obtained in step S22 is set in the timer in step S25, and the degree of temperature rise changes depending on the length of this predetermined time. In addition, the predetermined time set in the timer in step 826 is corrected according to the operating state determined from the negative pressure and the engine speed, and when the load is high and the engine speed is high, the heating port is large and the temperature rise is large. This will be corrected because it will cause stiffness. Subsequently, in step S27, a predetermined temperature is added to the previous set water temperature to calculate an increase in the set water temperature, and in step 329, the set temperature, which increases over time, is used as water temperature control data.

When this failure occurs, the flag F is set to 1, so the determination in step S3 becomes YES, and various controls using the calculated set engine temperature value are continued until the power is turned off, and then the next power is turned on. At that time, the failure judgment is performed again.

Therefore, even in the event of a failure, the water temperature can be determined appropriately, and
Step $ both during normal operation and when a failure occurs.
The various control routines from step 7 to step 818 can be used as they are, and countermeasures against failures of the engine temperature detection means 2 can be realized without increasing the number of maps for various controls.

It should be noted that the above-mentioned control of the various operating states describes only the basic matters, and detailed corrections are further performed on this control based on various detected data.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing the configuration of the present invention; FIG. 2 is an overall configuration diagram showing a specific configuration example of the invention; FIG. 3 is a block diagram showing the internal configuration of the control unit; The figure is a flow chart diagram explaining the operations of the controller 1 to the roll unit. 1...Engine 3...Intake passage 2...Engine temperature detection means 4...Intake air temperature detection means 5...Operating state control means 8...Failure detection means 9...Engine temperature calculation means 12...Water temperature sensor 15...Intake temperature sensor 19...Fuel supply device 23...
... EGR device 27 ... SIG device 32 ... Control unit 37 ...
・Failure indicator lamp diagram 1

Claims (1)

[Claims] (1) An engine temperature detection means for detecting engine temperature, an intake air temperature detection means for detecting intake air temperature, and controlling the operating state of the engine and supplying at least fuel according to the engine temperature in response to the output of the engine temperature detection means. In the engine, the engine is equipped with an operating state control means for correcting and controlling the amount, and a failure detection means receives the output of the engine temperature detection means and detects a failure of the engine temperature detection means;
In response to the outputs of the failure detection means and the intake air temperature detection means, when the engine temperature detection means fails, the initial value of the engine temperature is calculated and determined based on the intake air temperature at the time of engine startup, and the calculated engine temperature is determined according to the initial value. An engine temperature detection device characterized by comprising: an engine temperature calculation means for changing the degree of increase in the temperature of the engine.