JPH04194324A - Fan control diagnosis apparatus for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the structure from becoming complicated and prevent the cost from increasing, by making diagnosis of whether the radiator fan is in normal operation depending upon whether or not the number of engine revolutions becomes small at the moment when the fan control conditions have changed from OFF conditions to ON conditions. CONSTITUTION:A control unit 17 reads control conditions for a radiator fan 14 and, in case of 'ON' conditions, decides next whether or not the engine is in an idle state. If, in case of an idle state, the reading time point is immediately after the fan control conditions have changed from the 'OFF' condition to the 'ON' conditions, a timer is reset which shows a time passage from the change to the 'ON' conditions, whereby the number of engine revolutions at the moment when the fan control conditions have changed to the 'ON' conditions is stored as a number of revolutions for fan-OFF time period. Then, determination is made of a difference between the stored fan-OFF time period number of engine revolutions and an actual number of engine revolutions during this time period. And when the amount reduced in the number of engine revolutions becomes even once higher, during a predetermined time period, than a prescribed decision level, it is decided that fan control is being normally performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fan control diagnostic device for diagnosing whether a control system of an internal combustion engine radiator fan, particularly an electric radiator fan, is operating normally.

Conventional technology An electric radiator fan driven by an electric motor is
In general, engine cooling water temperature, vehicle speed, and even the ON of the air conditioner,
It is controlled to be turned ON or OFF based on control conditions such as an OFF state.

In such a radiator fan, if the fan control is not performed normally due to some cause such as a disconnection of the electric motor, a disconnection of the harness, or an abnormality on the control unit side, the cooling water temperature will become unstable. Therefore, it is desirable to promptly detect the abnormality and notify the driver.

However, this type of self-diagnosis device has not conventionally been provided for radiator fans, and it has not been possible to self-diagnose abnormalities in fan control.

Note that, as a similar self-diagnosis device, there is one that diagnoses, for example, a fuel injection control system of an internal combustion engine.

For example, as described in Japanese Patent Application Laid-Open No. 58-214634, the electric current flowing through the fuel injection valve is monitored to diagnose whether or not the fuel injection valve is operating normally.

Problems to be Solved by the Invention However, even if the conventional self-diagnosis device as described above were applied to fan control, a new detection circuit, input board, etc. would be required to monitor the current flowing to the electric motor. There are defects that complicate the configuration and increase costs.

Means to solve problems Therefore, this invention turns on the radiator fan.

This system performs self-diagnosis of fan control by focusing on changes in engine speed due to OFF. That is, the fan control diagnosis device for an internal combustion engine according to the present invention includes a radiator fan driven by an electric motor, and the radiator fan is turned on and off based on control conditions such as cooling water temperature.
In an internal combustion engine that is OFF-controlled, a rotation speed detection means 1 detects the rotation speed of the internal combustion engine, an idle state detection means 2 detects that the internal combustion engine is in an idle state, and a radiator fan ON to detect that the control condition has changed from OFF condition to ON condition
an operation detection means 3; a storage means 4 for storing the engine speed when the OFF condition changes from the OFF condition to the ON condition as the fan OFF rotation speed; The fan is configured to include an abnormality determining means 5 that compares the rotation speed when the fan is OFF to determine whether or not there is an abnormality.

The electric motor for the working radiator fan is powered by an alternator driven by the engine output and an on-board battery, so when the electric motor is turned on,
The electrical load on the alternator increases temporarily. Therefore, the output consumed to drive the alternator increases, and the engine speed temporarily decreases.

This change in engine speed can be reliably detected if the engine is in an idle state.

That is, if the radiator fan actually turns on when the control conditions such as the engine cooling water temperature change from the OFF condition to the ON condition, the engine speed will decrease. On the other hand, if the radiator fan does not operate due to some abnormality, the rotational speed will not decrease, and therefore it is determined that there is an abnormality.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 2 is a configuration explanatory diagram showing the configuration of a fan control system equipped with a diagnostic device according to the present invention.

In this embodiment, an internal combustion engine 11 is mounted in a so-called horizontal type in a vehicle, and a radiator 12 is disposed at the front of the vehicle.

Above radiator! A radiator fan 14 driven by an electric motor 13 is disposed on the front surface of the fan 2 . The electric motor 13 of the radiator fan 14 is driven by an on-vehicle battery 15, and is turned on and off by a control signal from a control unit 17 via a relay 16.

An alternator 18 is attached to the internal combustion engine 11 as an auxiliary device, and an output terminal of the alternator 18 is connected to the battery 15 so that the battery 15 is charged by the output of the alternator 18.

This alternator 18 is driven by engine output via, for example, a V-belt.

The internal combustion engine 11 is also provided with a water temperature sensor 19 that detects the engine cooling water temperature and a crank angle sensor 20 that detects the engine speed. Further, an idle switch 21 is provided for a throttle valve (not shown) in the intake passage for detecting that the throttle valve is in a fully closed position.

The control unit 17 is composed of a so-called microcomputer system, and controls ON/OFF of the radiator fan 14 via the relay 16. The main control conditions include the detection signal from the water temperature sensor 19, the rotational speed signal from the crank angle sensor 20, the detection signal from the idle switch 21, and the neutral switch 2, which is turned on when the transmission is in neutral.
2, a vehicle speed signal from a vehicle speed sensor 23, an ON/OFF signal of an air conditioner switch 24 in a vehicle air conditioner, etc. are inputted, respectively.

Further, as will be described later, the control unit 17 diagnoses whether or not the radiator fan control is normal when the engine is idling, and in the event of an abnormality, activates warning means such as the warning light 25, and stores information to that effect in the memory. It is designed to be remembered.

Next, the operation of the above embodiment will be explained.

First, in this embodiment, the ON/OFF control of the radiator fan 14 is performed using the engine cooling water temperature, the vehicle speed, and the ON/OFF state of the air conditioner switch 24 as control conditions. The following table summarizes these three conditions and the ON/OFF states of the radiator fan 14.

Then, when the engine is idling, a self-diagnosis is performed to determine whether the fan control is being performed normally. Third
The figure is a flowchart showing this self-diagnosis process, and the self-diagnosis process will be explained below with reference to this flowchart.

The routine shown in FIG. 3 is repeatedly executed at a predetermined time or every predetermined crank angle. First, the control conditions for the radiator fan 14 described above are read (step 1).
, it is determined whether the ON condition is met (step 2). O
If the condition is FF, no diagnosis is performed. If it is an ON condition,
Next, it is determined whether it is in an idle state (step 3
). This determination is made based on, for example, the idle switch 21 and the neutral switch 22. Specifically, it is determined that the vehicle is idling when the throttle valve is fully closed and the transmission is in the neutral state.

If it is not in the idle state, the fan control is not substantially diagnosed, and the flag F indicating that it is in the idle state is
ID, flag FOK indicating that a decrease in engine speed greater than a predetermined level has been detected, fan control condition is O
When the FF condition changes to the ON condition, a flag FJG indicating that one abnormality determination has been made is reset (steps 4 and 5.6).

On the other hand, if it is in the idle state, it is determined whether the above-mentioned fan control condition has just changed from the OFF condition to the ON condition, that is, whether the previous condition was the OFF condition (step 7). Here, if YES, that is, immediately after the change to the ON condition, each process of steps 8 to 12 is performed. That is, the timer TMRFON indicating the elapsed time after changing to the ON condition is reset (step 8), and the flag FID indicating the idle state is set to 1 (step 9). Further, the engine speed N at the moment when the ON condition changes is stored as the fan OFF speed NMEM (step 10). Furthermore, the aforementioned flags FOK and FJG are reset (step 11.12).

From the next time onwards, the process will proceed from step 7 to step 13, and it will be determined whether the flag FID is 1 or not. If the engine becomes non-idle during diagnosis, the flag FID becomes O (
Since step 4), the diagnosis is aborted. In other words, one abnormality determination is made on the condition that the idle state continues, and the process proceeds from step 13 to step 14.

In this step i4, it is determined whether or not the value of the timer TMRFON, which indicates the elapsed time after changing to the ON condition, has exceeded a predetermined time TI.

One abnormality determination is performed during the above-mentioned predetermined time TI. For details, see the previously memorized fan OFF rotation speed NME.
Difference between M and actual rotation speed N at that time (NMEM-N)
In other words, find the amount of rotation speed decrease and use this as the predetermined judgment level N
A successive comparison is made with J (step 15). Then, during the predetermined time TI, the rotational speed decrease amount (NMEM
-N) is equal to or higher than the predetermined judgment level NJ, the flag FO
Let K be 1 (step 16).

When the elapsed time TMRFON after changing to the ON condition exceeds the predetermined time TI, the flag FJG is set to 1 only for the first time in step 17.18), and 1 for each ON condition change.
Proceed to step 19 only once.

In step 19, the state of the flag FOK is determined, and if the flag FOK is 1, the abnormality determination counter NGC is set to O (step 20).

If the flag FOK is 0, the abnormality determination counter NGC is sequentially incremented (step 21). Then, the value of the abnormality determination counter NGC is compared with a predetermined value Nl, and if it exceeds the predetermined value Nl, it is finally determined that the fan control is abnormal (step 22). In this case, the warning light 25 lights up and the fact that there is an abnormality is stored in the memory.

That is, as shown in FIG. 4, when the radiator fan 14 is actually turned on due to a change in the cooling water temperature, a large current momentarily flows through the electric motor 13 and the alternator 18
Since the power consumed to drive the engine increases, the idle speed decreases over time. Therefore, the fan control conditions are OF
When changing from the F condition to the ON condition, if a decrease in the rotation speed by a predetermined judgment level NJ or more is observed, it is considered that the radiator fan 14 has actually turned ON, and it can be determined that the fan control is being performed normally. I can do it.

The electrical load, which was relatively large when the engine was turned on, gradually decreases over time, and since the generally known idle speed control works to increase the speed, the figure also shows the speed that has dropped once. It will recover over time.

On the other hand, if the electric motor 13 does not operate due to a disconnection of the electric motor 13, a disconnection of the harness, or an abnormality on the control unit 17 side, the idle rotation speed does not decrease. If the idle rotation speed control is used to increase the amount of bypass air when the radiator fan 14 is ON, the rotation speed will rather rise slightly, as shown by the broken line. Therefore, if such an abnormality is detected multiple times (N1 or more), it is determined that there is some abnormality in the fan control.

Note that if the radiator fan 14 is equipped with idle rotation speed control that increases the amount of bypass air by a certain amount when the radiator fan 14 is ON as described above, even if the radiator fan 14 operates normally, the rotation Since the decrease in the number decreases by the increase in the amount of bypass air, it is necessary to take this into consideration when setting the determination level NJ.

Effects of the Invention As is clear from the above explanation, according to the internal combustion engine fan control diagnosis device according to the present invention, when the fan control conditions such as the cooling water temperature change from the OFF condition to the ON condition, the engine speed decreases. Depending on whether or not the radiator fan is operating normally, it can be diagnosed whether or not the radiator fan is operating normally, and it is possible to prevent the cooling water temperature from becoming unstable due to an abnormality in fan control.

Furthermore, it can be easily configured using existing sensors such as a crank angle sensor, and there is no need to add a new detection circuit, harness, etc., so the configuration does not become complicated or the cost increases.

[Brief explanation of the drawing]

Fig. 1 is a complaint response diagram of the fan control diagnostic device according to the present invention, Fig. 2 is a configuration explanatory diagram showing an embodiment of the invention, Fig. 3 is a flowchart showing the diagnostic processing in this embodiment, and Fig. 4 2 is a time chart showing changes in the ON/OFF state of the radiator fan and the idle rotation speed due to changes in cooling water temperature. l...Rotational speed detection means, 2...Idle state detection means, 3...ON operation detection means, 4...Storage means, 5
...Anomaly determination means. Figure 1 Figure 2

Claims (1)

[Claims] (1) In an internal combustion engine that is equipped with a radiator fan driven by an electric motor, and in which the radiator fan is controlled to turn on and off based on control conditions such as cooling water temperature, the rotational speed at which the rotational speed of the internal combustion engine is detected. a detection means, an idle state detection means for detecting that the internal combustion engine is in an idle state, and an ON operation detection means for detecting that a control condition of the radiator fan has changed from an OFF condition to an ON condition during the idling state; Storage means for storing the engine speed when changing from the OFF condition to the ON condition as the fan OFF speed, and comparing the engine speed after changing from the OFF condition to the ON condition with the fan OFF speed. A fan control diagnostic device for an internal combustion engine, comprising an abnormality determining means for determining the presence or absence of an abnormality.