KR100736546B1 - Method for diagnosing thermostat of car - Google Patents

Abstract

A method for diagnosing a thermostat of a vehicle is provided to improving reliability of an engine by diagnosing the thermostat on the basis of the variation of a cooling water temperature after forcibly driving a cooling fan. A method for diagnosing a thermostat of a vehicle includes the steps of: receiving engine condition information supplied from the outside(S101); checking whether an engine is idling on the basis of the received engine condition information(S103); receiving temperature information of the external air when the engine is idling(S105); receiving temperature information of cooling water lowered by driving a cooling fan(S111); calculating variation of the received cooling water temperature(S113); determining that the thermostat is malfunctioned when the cooling water temperature is lower than a reference value(S117); and determining that the thermostat is normal when the cooling water temperature is not lower than the reference value and a predetermined set time elapses(S119,S121).

Description

Thermostat fault diagnosis method of automobile {METHOD FOR DIAGNOSING THERMOSTAT OF CAR}

1 is a view showing the configuration of a cooling device of a typical vehicle.

2A and 2B are diagrams illustrating the configuration of the thermostate illustrated in FIG. 1.

3 is a view showing the configuration of a vehicle to which the present invention is applied.

4 is a flowchart illustrating a process for diagnosing a thermostate failure of a vehicle according to the present invention.

<Explanation of symbols for main parts of drawing>

11: control unit 13: cooling fan

15: display unit

The present invention relates to a method for diagnosing a thermostat failure of an automobile, and more particularly, to diagnose a failure of a thermostate based on a change in a cooling water temperature which is lowered when a cooling fan is driven while the engine is idle after driving stops. It's about one way to help.

In general, the cooling device is a device that cools the engine to prevent overheating and maintains the temperature at a constant temperature. There is an air cooling type that directly cools the outside of the engine using outside air, and a water cooling type that circulates and cools the cooling water inside the engine.

As shown in FIG. 1, the water-cooled cooling apparatus includes a water jacket 30 surrounding the cylinder 10 and the combustion chamber 20, a water pump 40 for pumping and circulating water into the cylinder 10, and high temperature cooling water. It consists of a radiator 50 for transferring the heat to the outside air to cool, a fan 60 for helping the radiator 50 to ventilate, and a thermostat 100 for quickly raising the coolant to an appropriate temperature immediately after starting. The coolant is circulated inside the water jacket 30 surrounding the cylinder 10 by the pump 40 to cool the heat generated in the cylinder block 70 and the cylinder head 80, and then the water jacket 30. The coolant warmed in the) draws into the radiator 50 to radiate heat. Then, the water radiated from the radiator 50 is circulated back to the water jacket 30 to cool the engine.

In addition, the fan is forced to contact the radiator 50 to the outside air to improve the heat dissipation effect, and the upper flow path 90 between the water jacket 30 and the radiator 50 automatically according to the change of the temperature of the coolant By controlling the opening and closing to control the flow rate flowing to the radiator 50, the thermostat 100 which maintains the temperature of cooling water at the appropriate temperature is provided, and the circulation path of cooling water is changed according to temperature.

The operation of the thermostate will be described in more detail below with reference to FIGS. 2A and 2B.

FIG. 2A is a cross-sectional view showing a state when the thermostate is closed, and FIG. 2B is a cross-sectional view showing a state when the thermostate is opened by increasing the temperature of the cooling water inside the water jacket.

As shown in FIG. 2A, when the temperature of the coolant inside the water jacket rises above the prescribed temperature in the state in which the valve 110 is closed, the wax 125 in the pallet 120 expands to form the inside of the pallet 120. By compressing the inserted rubber 130, the spindle 140 in the center of the rubber 130 is pressed upward, but the spindle 140 is mounted on the bracket 150, so the pallet 120 is fixed It descends and the valve 110 opens as shown in FIG. 2B.

On the other hand, as shown in FIG. 2B, when the valve 110 is opened and the hot coolant of the water jacket circulates to the radiator, and the temperature of the coolant is lowered, the expanded wax 125 is contracted and the rubber 130 is compressed. The pallet 120 is removed and is returned to its original position as shown in FIG. 2A by the elasticity of the spring 160.

However, the water jacket warmed by the heat generated from the engine when the thermostat fails and the valve is kept closed even when the valve opens above a certain temperature, that is, when the valve to be opened at 88 ° C. is closed even at a temperature above 88 ° C. As the coolant inside is not cooled and the engine is overheated, the cylinder is deformed or the oil film on the cylinder wall is broken, resulting in poor lubrication. Also, the combustion condition worsens, leading to knocking or premature ignition. do.

In addition, when the coolant is overheated, the coolant turns into water vapor and raises the pressure inside the radiator. Thus, the increased pressure acts on the radiator cap, causing the radiator cap to open upward. This is generated to generate a concentration on the driver's driving.

On the other hand, if the thermostat fails and the valve remains open at a predetermined temperature or less, the coolant continues to cool down through the radiator. Therefore, the amount of heat lost by cooling increases due to combustion, which reduces the engine's thermal efficiency. The ECU, which controls the fuel injection amount based on the coolant temperature, increases the fuel consumption by increasing the fuel injection amount because the coolant temperature is low, and dilutes the engine oil by the gasoline because the insufficiency of gasoline in the cylinder is supplied. It is a cause of making and accelerating wear of the cylinder. In addition, the water temperature is always low, resulting in a decrease in the performance of the air conditioner.

As described above, the thermostate controlling the coolant temperature of the engine plays an important role, and the failure of the thermostate is diagnosed based on the change in the coolant temperature when the radiator is driven while driving. However, such thermostate failure diagnosis could not be applied because the amount of heat generated in the engine during the idling after the engine is small and there is little change in the temperature of the coolant temperature through the radiator. Therefore, a separate method for diagnosing a failure of the thermostate after the engine is still required is needed.

Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to diagnose a failure of the thermostat based on a change in the cooling water temperature which is lowered after forcibly driving the cooling fan in the engine idle state after driving stop. In addition, the present invention provides a method for diagnosing a thermostat failure of an automobile, which can further improve reliability of an engine.

Technical problem according to the present invention for achieving the above object,

In an automobile having a thermostat measuring the coolant temperature,

a) receiving state information of the engine and checking whether the engine is idle after stopping driving;

b) receiving the outside air temperature information in the case of engine idle, checking whether the outside air temperature exists within a preset reference range, and driving a cooling fan to lower the cooling water temperature if the outside air temperature exists within the reference range; And

c) diagnosing the failure of the thermostate based on the coolant temperature falling through step (b);

Here, step c),

c-1) receiving a descending current coolant temperature value;

c-2) calculating the amount of coolant temperature change (the value of the previous coolant temperature minus the value of the current coolant temperature) that falls through the current coolant temperature value received through step c-1);

c-3) comparing the amount of change in the coolant temperature calculated in step c-2 with a preset reference value and determining the thermostat as a failure when the reference value is less than the reference value; And

c-2) If the predetermined time has not elapsed in step c-1), check whether a predetermined time has elapsed. If the predetermined time has not elapsed, proceed to step c-1) and the predetermined time has elapsed. And if so, determining the thermostate to be normal.

According to the present invention, it is possible to further improve the reliability of the engine by diagnosing a failure of the thermostate based on a change in the coolant temperature that falls when the cooling fan is driven in the engine idle state.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

3 is a view showing the configuration of a cooling apparatus of a vehicle to which the present invention is applied. As shown therein, the cooling apparatus of the vehicle to which the present invention is applied drives the cooling fan 13 according to the outside temperature and the engine state information, and then the thermostat (not shown) is based on the change in the cooling water temperature received thereafter. Is provided as a control unit 11 for diagnosing a failure of the control unit 11, and an output unit of the control unit 11 further includes a display unit 15 for recognizing a diagnosis result of a thermostate to a driver or a maintenance worker. That is, the controller 11 detects that the engine is idle after driving stops based on the received outside air temperature and engine state information to drive the cooling fan 13, and the cooling water descends by driving of the cooling fan 13. Diagnose thermostat failure based on temperature.

4 is a flowchart illustrating a process of diagnosing a thermostate failure of a vehicle of the controller 11 illustrated in FIG. 3. That is, the controller 11 receives the engine state information supplied from the outside (step 101), checks whether the engine is idling based on the received engine state information (step 103), and is supplied from the outside when the engine is idling. An outdoor temperature is received (step 105).

It is checked whether the outside air temperature received through the step 105 exists within a preset reference range (step 107), and the cooling fan 13 is driven when the outside temperature exists within the reference range.

Here, preferably, the reference range is set to -7 degrees or more and 30 degrees or less.

Subsequently, the control unit 11 receives the cooling water temperature lowered by the driving of the cooling fan 13 (step 111), and calculates the change in the received cooling water temperature (step 113). That is, the coolant temperature change amount is calculated by subtracting the current coolant temperature value from the previous coolant temperature value.

At this time, when the coolant temperature change amount is equal to or less than a preset reference value, the control unit 11 determines that the thermostat is a failure (step 117), and the determination result is supplied to the display unit 15.

On the other hand, the control unit 11 checks whether the predetermined time has elapsed when the amount of change in the coolant temperature is greater than or equal to the reference value through the step 115 (step 119). Receive the current coolant temperature via.

When the amount of change in the coolant temperature has elapsed by more than the reference value, the controller 11 determines that the thermostat is normal (step 121), and transmits the determination result to the display unit 15.

Therefore, according to the present invention described above, it is possible to diagnose a failure of the thermostate even in the engine idle state.

As described above, the method for diagnosing a thermostat failure of a vehicle according to the present invention is based on the reliability of the engine by diagnosing a failure of the thermostat based on a change in the coolant temperature that falls when the cooling fan is driven while the engine is idle. Can be further improved.

The present invention is not limited to the above embodiments, and various changes can be made by any person having ordinary skill in the art without departing from the gist of the present invention as claimed in the following claims. It will be said that there is a technical spirit of the present invention to the extent.

Claims (3)

In an automobile having a thermostat measuring the coolant temperature, a) receiving state information of the engine and checking whether the engine is idle; b) receiving the outside air temperature information in the case of engine idle, checking whether the outside air temperature exists within a preset reference range, and driving a cooling fan to lower the cooling water temperature if the outside air temperature exists within the reference range; And c) diagnosing a failure of the thermostate based on the cooling water temperature falling through the step (b). The method of claim 1, wherein step c) c-1) receiving a descending current coolant temperature value; c-2) calculating the amount of coolant temperature change (the value of the previous coolant temperature minus the value of the current coolant temperature) that falls through the current coolant temperature value received through step c-1); c-3) comparing the amount of change in the coolant temperature calculated in step c-2 with a preset reference value and determining the thermostat as a failure when the reference value is less than the reference value; And c-2) If the predetermined time has not elapsed in step c-1), check whether a predetermined time has elapsed. If the predetermined time has not elapsed, proceed to step c-1) and the predetermined time has elapsed. And determining the thermostat as normal if it is. The method of diagnosing a thermostate failure of an automobile according to claim 1 or 2, wherein the reference range is -7 degrees or more and 30 degrees or less.

Images