JP2001329841A - Failuar diagnostic device for thermostat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and accurately diagnose the failure of a thermostat valve with a simple structure. SOLUTION: This failure diagnostic device is provided with a failure detecting means 13 for detecting at least one of the open failure or the close failure of the thermostat valve 10 for adjusting the cooling water temperature of an engine and a radiation quantity control means 14 for controlling a radiator 2 to increase its radiation quantity by driving a cooling fan 20 when a failure is detected by the failure detecting means 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermostat failure diagnosis device provided in a cooling system of an engine.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. H11-15937
As disclosed in Japanese Patent Application Laid-Open No. 9-209, a coolant temperature sensor for detecting a coolant temperature, load detection means for detecting a load on an engine, and an engine load detected by the load detection means are integrated to obtain a calorific value of the engine. A calorific value calculating means for calculating, and a diagnosing means for diagnosing whether or not an abnormality has occurred in the cooling system according to the coolant temperature and the calorific value of the engine. In this case, the coolant temperature rises rapidly due to the large amount of heat generated by the engine. It has been practiced to be able to accurately diagnose whether or not the thermostat valve is operating normally on the basis of this.

[0003]

As described above, at the time of high-load operation, by correcting the failure determination reference value, erroneous diagnosis due to a sudden rise in the engine coolant temperature (coolant temperature) is prevented. Even with such a configuration, when the heat radiation amount in the radiator is small, a remarkable temperature change does not occur even if the thermostat valve is opened and closed, so that a closing failure has occurred even though the thermostat valve is normal. Are easily misdiagnosed.

That is, when the engine is under a high load and generates a large amount of heat and the radiator emits a small amount of heat due to a low vehicle speed when the vehicle is traveling on an uphill, the thermostat valve is closed. At the time of failure detection, the temperature of the cooling water rises significantly despite the thermostat valve being open, and it is erroneously assumed that the thermostat valve has closed and the supply of cooling water to the radiator has been stopped. There is a problem that diagnosis is easy. Further, when detecting the open failure of the thermostat valve in a state in which the heat radiation amount of the radiator is small, the cooling water temperature does not significantly decrease even though the thermostat valve is in the open failure state, There is a problem that the thermostat valve is erroneously diagnosed as being normally operated and closed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a thermostat failure diagnosis apparatus which can quickly and accurately diagnose a failure of a thermostat valve with a simple configuration. .

[0006]

The invention according to claim 1 is
Failure detection means for detecting at least one of an open failure and a closed failure of a thermostat valve for adjusting the temperature of cooling water of the engine, and a heat radiation amount control for increasing a heat radiation amount of the radiator when the failure detection means detects a failure. Means.

[0007] According to the above configuration, the control for increasing the heat radiation amount of the radiator is executed by the heat radiation amount control means, so that the cooling water temperature is controlled so as to be significantly changed when the thermostat valve is opened and closed. In this state, the failure detection means detects the open failure or the closed failure of the thermostat valve, so that the failure of the thermostat valve can be quickly and accurately diagnosed without erroneous diagnosis.

According to a second aspect of the present invention, in the thermostat failure diagnosis apparatus according to the first aspect, it is confirmed that the vehicle is in a low-speed traveling state when the failure of the thermostat valve is detected by the failure detecting means. Only if
The heat radiation amount control means executes control for increasing the heat radiation amount of the radiator.

According to the above configuration, when it is confirmed that the vehicle is in a low-speed running state when the failure detecting means detects the open failure or the closed failure of the thermostat valve, the radiator is controlled by the heat radiation amount control means. Is executed to control the cooling water temperature to change significantly when the thermostat valve is opened and closed. In addition, when it is confirmed that the vehicle is not in the low-speed running state, the detection of the open failure or the close failure of the thermostat valve is performed without performing the control for increasing the heat radiation amount of the radiator. Become.

According to a third aspect of the present invention, in the thermostat failure diagnosis apparatus according to the first or second aspect, the failure detection means determines whether the thermostat valve is in a failure state, in a normal state, or in an accurate state. It is configured to determine whether the state is in a suspended state where it is difficult to perform the detection, and to perform the re-failure detection of the thermostat valve when the suspension determination is made, and only when the failure detection means detects the re-failure of the thermostat valve, The heat radiation amount control means executes a control for increasing the heat radiation amount of the radiator.

According to the above configuration, at the time of the first failure detection by the failure detection means, the failure detection of the thermostat valve is performed without executing the control for increasing the heat radiation amount of the radiator by the heat radiation amount control means. If the suspension determination is made at the time of the first failure detection, the failure detection of the thermostat valve by the failure detection means is performed in a state in which the control of increasing the radiation amount of the radiator is executed by the radiation amount control means. Since it is executed again, the failure of the thermostat valve can be quickly and accurately diagnosed without erroneous diagnosis.

According to a fourth aspect of the present invention, in the thermostat failure diagnosis apparatus according to any one of the first to third aspects,
The thermostat valve includes an electric control valve that is electrically controlled to open and close. The thermostat valve further includes an open / close temperature setting unit that sets an open / close temperature of the thermostat valve in accordance with an operating state of the engine. When the open failure of the thermostat valve is detected, control is performed to increase the amount of heat radiated by the radiator while the open / close temperature of the thermostat valve is set to the high temperature side, and when the closed failure of the thermostat valve is detected, the open / close temperature of the thermostat valve is lowered. The control for increasing the heat radiation amount in the radiator is executed in the state set on the side.

According to the above construction, when the failure detecting means detects an open failure of the thermostat valve in a valve closing temperature region where the cooling water temperature is lower than the opening / closing temperature of the thermostat valve, the switching temperature is set by the opening / closing temperature setting means. When the temperature is set to a higher temperature side than usual and the cooling water temperature is higher than the opening / closing temperature in the valve opening temperature range, when the thermostat valve closing failure is detected by the failure detecting means, the opening / closing temperature setting means Since the opening / closing temperature is set lower than normal, the occurrence of erroneous diagnosis due to no difference between the opening / closing temperature and the actual cooling water temperature is prevented.

According to a fifth aspect of the present invention, in the thermostat failure diagnosis apparatus according to any one of the first to fourth aspects,
The heat radiation amount control means increases a heat radiation amount of the radiator by controlling at least one of a cooling fan for supplying cooling air to the radiator or an opening area increasing means for increasing an opening area of a cooling air intake for the radiator. This is configured to execute the control to cause the control to be performed.

According to the above arrangement, at least one of the cooling fan for supplying the cooling air to the radiator or the opening area increasing means for increasing the opening area of the cooling air intake for the radiator is controlled by the heat radiation amount controlling means. Accordingly, in a state where the heat radiation amount of the radiator is effectively controlled to be large, the failure detection means can quickly and accurately detect the open failure or the close failure of the thermostat valve.

[0016]

FIG. 1 shows a cooling system of a vehicle engine having a thermostat failure diagnosis apparatus according to an embodiment of the present invention. In this cooling system, the first cooling water supplied from the engine body 1 is supplied to the radiator 2.
A pipe 3 and a second pipe 4 for supplying cooling water cooled by the radiator 2 to the engine body 1, a cooling water pump 5 for supplying cooling water to the engine body 1, Temperature sensor 6 for detecting the temperature of the cooling water
And a cooling fan 20 for supplying cooling air to the radiator 2.

The first pipe 3 and the second pipe 4 are connected at two places by a first bypass pipe 7 and a second bypass pipe 8. In addition, the two bypass pipes 7, 8
A heater core 9 of a heating device is provided in the first bypass pipe 7 on the engine body 1 side, and an electrically controlled type is provided in a connection portion between the second bypass pipe 8 and the second pipe 4 on the radiator 2 side. A thermostat valve 10 is provided. In addition,
The first bypass passage 7 is provided with an opening / closing valve (not shown) for preventing cooling water from flowing into the first bypass passage 7 when indoor heating is not performed.

The thermostat valve 10 is electrically opened when the cooling water temperature of the engine is higher than the opening / closing temperature of the thermostat valve 10, and the upstream side 4 a and the downstream side of the second pipe 4 are opened. 4b, and by shutting off the second bypass pipe 7 and the second pipe 4, high-temperature cooling water derived from the engine body 1 is supplied to the radiator 2 and cooled, and then the second cooling pipe is cooled. It is configured to supply the engine body 1 via the two pipes 4.

When the temperature of the cooling water of the engine is lower than the opening / closing temperature of the thermostat valve 10, the thermostat valve 10 is electrically closed so that the upstream side 4a of the second pipe 4 and the downstream side are closed. The second bypass pipe 7 communicates with the second pipe 4 while shutting off the second bypass pipe 7 and the second pipe 4, so that the high-temperature cooling water derived from the engine body 1 is not supplied to the radiator 2 without being supplied to the radiator 2. The three-way switching valve circulates from the pipe 7 to the engine body 1 via the downstream side 4b of the second pipe 4.

In the thermostat failure diagnostic device,
Opening / closing temperature setting means 11 for setting the opening / closing temperature in accordance with the operating state of the engine;
Feedback control means 12 for performing feedback control of the thermostat valve 10 based on the opening / closing temperature set by the above, failure detection means 13 for detecting an open failure and close failure of the thermostat valve 10, and failure detection by the failure detection means 13. Sometimes, the cooling fan 20 is actuated as needed to increase the heat radiation of the radiator 2, and the thermostat according to a failure detection signal output from the failure detection means 13. Alarm means 15 for notifying that a failure has occurred in the valve 10 is provided.

The opening / closing temperature setting means 11 is used to set the temperature of the cooling water to an optimum value during normal operation of the engine, for example, during a warm operation excluding an extremely low load state or an extremely high load state. The switching temperature of 10 is set to 80, for example.
° C, the opening / closing temperature is set to, for example, about 90 ° C in order to quickly raise the temperature of the cooling water during low load operation of the engine, and the engine body is operated at high load operation of the engine. The opening / closing temperature is set to less than 80 ° C. in order to prevent the temperature such as 1 from excessively rising.

The feedback control means 12 includes a thermostat valve 1 set by the open / close temperature setting means 11.
A difference between the open / close temperature of 0 and the actual cooling water temperature detected by the temperature sensor 6 is obtained, and an opening / closing signal corresponding to this deviation is output to the thermostat valve 10 so that the actual cooling water temperature becomes the opening / closing temperature. It is configured to execute a feedback control for matching.

The failure detecting means 13 opens the thermostat valve 10 based on a deviation between the opening / closing temperature of the thermostat valve 10 set by the opening / closing temperature setting means 11 and the actual cooling water temperature detected by the temperature sensor 6. It is determined whether a failure or a closed failure has occurred, whether the thermostat valve 10 is in a normal state, or whether the thermostat valve 10 is in a holding state where accurate detection is difficult. State is detected,
The detection signal is output to the alarm means 15.

That is, in a valve closing temperature region where the actual cooling water temperature is lower than the opening / closing temperature of the thermostat valve 10, the state in which the absolute value of the deviation is equal to or higher than a predetermined first reference value for a certain period of time. If it is confirmed that the cooling water temperature has not risen, the thermostat valve 10
It is determined that an open failure has occurred, and a state in which the absolute value of the deviation is less than a second reference value set to a value smaller than the first reference value is continued for a certain period of time, and the cooling water temperature is reduced. When it is confirmed that the temperature has risen, it is determined that it is normal, and the absolute value of the deviation is equal to the first reference value and the second reference value.
When a state between the reference value and the reference value is continued for a certain period of time, it is configured to determine that the state is a hold state where accurate determination is difficult.

In a valve opening temperature region in which the actual cooling water temperature is higher than the opening / closing temperature of the thermostat valve 10, the state in which the absolute value of the deviation is equal to or greater than the first reference value is continued for a certain period of time. When it is confirmed that the temperature has not decreased, it is determined that a closed failure has occurred in the thermostat valve 10, and the absolute value of the deviation is set to a second reference value smaller than the first reference value. The state of being less than the value is continued for a certain period of time, and when it is confirmed that the cooling water temperature is decreasing, it is determined to be normal, and the absolute value of the deviation is equal to the first reference value. When the state between the second reference value and the second reference value is continued for a certain period of time, it is determined that the state is a hold state where accurate determination is difficult.

The heat radiation amount control means 14 may suspend the determination when the failure detection means 13 first detects a failure of the thermostat valve 10 and may be in a low vehicle speed state in which the traveling speed of the vehicle is less than a certain value. Only when it is confirmed, an operation command signal is output to the drive motor 21 of the cooling fan 20 to execute a control for forcibly increasing the amount of heat radiation of the radiator 2.

The basic control operation executed in the fault diagnostic apparatus having the above configuration will be described with reference to the flowchart shown in FIG. When the control operation is started, it is determined whether or not a suspension determination flag PF indicating that the determination is suspended when the failure of the thermostat valve 10 is first detected by the failure detecting means 13 is set to 1. If the determination is NO (step S1), the process proceeds to step S7 described below to execute the failure detection control of the thermostat valve 10.

If the result of the determination in step S1 is YES and it is confirmed that the failure determination of the thermostat valve 10 is in a suspended state, the vehicle speed detected by a vehicle speed sensor or the like (not shown) is preset. It is determined whether or not the vehicle speed is lower than the reference vehicle speed v (step S2). If NO is determined in step S2 and it is confirmed that the vehicle is not in the low-speed running state, the count value Ca of the counter for determining whether or not the cooling fan 20 is to be driven is set to 0. (Step S3)
Move to step S7.

If it is determined YES in step S2 and it is confirmed that the vehicle is running at a low speed, the count value Ca of the counter is incremented by 1 (step S4). Then, it is determined whether or not the count value Ca is greater than a preset first reference time β1 (step S5).
The control signal for driving the cooling fan 20 is transmitted to the drive motor 2.
1, after the control to drive the cooling fan 20 to forcibly increase the heat radiation amount of the radiator 2 (step S6), the failure detection control of the failure detection means 13 for the thermostat valve 10 is performed. Execute (step S7).

Next, it is determined whether or not a flag FF indicating that the failure detection control of the thermostat valve 10 has been completed is set to 1 (step S8). If YES, the control operation is performed. finish. If NO is determined in step S8 and it is confirmed that the failure detection control of the thermostat valve 10 is not completed, an opening / closing temperature serving as an opening / closing reference of the thermostat valve 10 and the temperature detected by the temperature sensor 6 After the opening / closing control of the thermostat valve 10 is performed based on the deviation of the actual cooling water temperature (step S9). Return and repeat the above control operation.

Next, the failure detection control executed in step S7 of the basic control will be described with reference to the flowchart shown in FIG. When the above control operation starts,
It is determined whether a predetermined time, for example, about 300 seconds, has elapsed after the start of the engine and the coolant temperature has risen to some extent (step S11).

If the determination in step S11 is YES, the open / close temperature TT of the thermostat valve 10 set by the open / close temperature setting means 11 and the actual cooling water temperature TS detected by the temperature sensor 6 are compared. Deviation Δ
After obtaining T (step S12), the absolute value of this deviation |
It is determined whether ΔT | is larger than a first reference deviation α1 set in advance (step S13).

If the determination in step S13 is YES, the count value Cb of the failure determination counter is incremented by 1 (step S14), and the count value Cb is compared with a preset reference time β2. By comparison, it is determined whether a predetermined time has elapsed (step S15).

[0034] In step S15, YES is determined.
If it is confirmed that the state where the absolute value | ΔT | of the deviation is larger than the first reference deviation α1 has been continued for a predetermined time or more, an open failure or a closed failure of the thermostat valve 10 occurs. The determination is made (step S16), and a detection signal indicating that a failure has occurred in the thermostat valve 10 is output to the alarm means 15, thereby notifying that the failure has occurred.

For example, when the open / close temperature TT of the thermostat valve 10 is detected in the closed valve temperature range where the thermostat valve 10 is higher than the actual cooling water temperature TS, the opening / closing temperature TT becomes lower than the actual cooling water temperature TS. Is greater than a predetermined value for a predetermined time, and the actual cooling water temperature TS
If it is confirmed that the temperature has not risen so as to approach the opening / closing temperature TT, it is determined that an open failure such as the thermostat valve 10 is stuck in an open state has occurred, and the alarm means 15 detects the open failure. Output a signal.

The switching temperature TT is equal to the actual cooling water temperature T.
When the closed failure of the thermostat valve 10 executed in the valve opening temperature region lower than S is detected, the state where the actual cooling water temperature TS is higher than the opening / closing temperature TT of the thermostat valve 10 by a predetermined value or more is continued for a predetermined time, When it is confirmed that the actual cooling water temperature TS has not decreased so as to approach the switching temperature TT, it is determined that a closing failure such as the thermostat valve 10 has been fixed in a closed state has occurred, and the alarm means has been determined. 15 outputs a closed fault detection signal.

On the other hand, if NO is determined in step S13 and it is confirmed that the absolute value | ΔT | of the deviation is equal to or smaller than a first reference deviation α1 set in advance to a predetermined value, the deviation is determined. Is the absolute value | ΔT |
It is determined whether or not the difference is smaller than a second reference deviation α2 set to a smaller value (step S17). If YES is determined in step S18, the count value Cb of the failure determination counter is incremented by 1 (step S18), and the count value Cb is compared with a preset reference time β2. It is determined whether or not a predetermined time has elapsed (step S19).

If YES is determined in the above step S19,
If it is confirmed that the state in which the absolute value | ΔT | of the deviation is smaller than the second reference deviation α2 has continued for a predetermined time or more, it is determined that the thermostat valve 10 is normal. (Step S20), a flag FF indicating that the failure detection control of the thermostat valve 10 has been completed is set to 1 (Step S21). That is,
When the thermostat valve 10 is normally opened / closed, it is determined that the control for bringing the actual cooling water temperature TS close to the opening / closing temperature TT of the thermostat valve 10 is properly executed, and the control operation ends.

If the determination in step S17 is NO and it is confirmed that the absolute value | ΔT | of the deviation is between the first reference deviation α1 and the second reference deviation α2, a failure determination is made. After the count value Cb of the application counter is incremented by 1 (step S22), whether the predetermined time has elapsed is determined by comparing the count value Cb with a preset reference time β2 (step S23). ).

It is determined YES in the above step S23,
If it is confirmed that the absolute value | ΔT | of the deviation is between the first reference deviation α1 and the second reference deviation α2 for a predetermined time or more, the thermostat valve 10 is turned off. It is determined that it is in a hold state where it is difficult to accurately determine whether or not a failure has occurred (step S24), and a flag PF indicating that the hold determination has been made is set to 1 (step S25), and then the process returns.

The above steps S15, S19, S2
If NO is determined in any of the cases 3 and it is confirmed that the predetermined time has not elapsed, the process returns to the basic control operation shown in FIG. 2 and repeats the control operation of the failure diagnosis.

As described above, the failure detecting means 13 for detecting at least one of the open failure and the closed failure of the thermostat valve 10 for adjusting the temperature of the cooling water of the engine, and the release of the radiator 2 when the failure detection means 13 detects a failure. Since the heat release amount control means 14 for controlling the heat amount is provided, at least one of the open failure and the close failure of the thermostat valve 10 can be quickly and accurately detected with a simple configuration.

For example, when the open failure of the thermostat valve 10 is detected in the valve closing region where the actual cooling water temperature TS is lower than the opening / closing temperature TT of the thermostat valve 10, the cooling fan 20 is driven to release the radiator 2. When the control for increasing the heat quantity is executed, if the thermostat valve 10 is normal, the thermostat valve 1
When 0 is closed, feedback control is performed to bring the actual cooling water temperature TS closer to the opening / closing temperature TT as shown by the solid line in FIG. When the thermostat valve 10 has an open failure, the heat radiation amount of the radiator 2 is large, and therefore the actual cooling water temperature TS is considerably lower than the opening / closing temperature TT as shown by a broken line in FIG. TT and the actual cooling water temperature T
The deviation from S increases.

On the other hand, if the thermostat valve 10 is configured to detect an open failure without driving the cooling fan 20, even if the open failure occurs, the radiator 2 may be disconnected for any reason. When the amount of heat radiation is small, the actual cooling water temperature TS rises so as to approach the switching temperature TT, and therefore, there is a possibility that the thermostat valve 10 having the open failure is erroneously diagnosed as normal.

Therefore, as described above, the failure detecting means 1
3, when the open failure is detected, the control to increase the heat radiation amount of the radiator 2 is executed, and when the open failure of the thermostat valve 10 occurs, the actual cooling water temperature TS is lowered early so that the switching temperature TT can be reduced. Erroneous diagnosis caused by a small deviation between the temperature and the actual cooling water temperature TS is effectively prevented, and it is possible to quickly and accurately determine whether or not an open failure has occurred in the thermostat valve 10 based on the deviation. Can be diagnosed.

Further, when the thermostat valve 10 is detected to be closed in a valve opening region where the actual cooling water temperature TS is higher than the opening / closing temperature TT of the thermostat valve 10, the cooling fan 20 is driven to activate the radiator 2. By executing the control for increasing the amount of heat radiation so as to lower the actual cooling water temperature TS early when the thermostat valve 10 is opened, even if the thermostat valve 10 does not have a closed failure, In other words, it is possible to effectively prevent the thermostat valve 10 from being erroneously diagnosed as being in a closed failure state due to a state in which the heat radiation amount of the radiator 2 is small and the actual cooling water temperature TS does not decrease for some reason. However, it is possible to quickly and accurately diagnose the closing failure of the thermostat valve 10.

In the above embodiment, the failure detecting means 1
3, when the failure of the thermostat valve 10 is detected, only when it is confirmed that the vehicle is in the low-speed running state, the control to increase the heat radiation amount of the radiator 2 by the heat radiation amount control means 14 is performed. The cooling fan 20 is used for high-speed running or the like in which a sufficient amount of heat can be secured by running wind blown to the radiator 2.
, The generation of noise and the waste of power due to the driving of the motor can be prevented. When the vehicle travels at a low speed with a small amount of wind blown to the radiator 2, the cooling fan 20 is driven to forcibly increase the amount of heat radiation of the radiator 2, so that the erroneous diagnosis due to the small amount of heat radiation is performed. Generation can be effectively prevented.

In the above embodiment, the failure detecting means 1
3 is used to determine whether the thermostat valve 10 is in a faulty state, in a normal state, or in a hold state where it is difficult to accurately detect the thermostat valve 10. Since the control for increasing the heat radiation amount of the radiator 2 is performed by the heat radiation amount control means 14 only at the time of this re-failure determination, the failure detection means 13 detects the first failure. In addition, the failure of the thermostat valve 10 can be detected without causing power waste or the like due to the driving of the cooling fan 20.

If, at the time of the first failure detection, the suspension determination is made because the actual cooling water temperature TS does not match the opening / closing temperature TT and the difference between the two temperatures is not more than a certain value, By executing the control for increasing the heat radiation amount of the radiator 2 by the heat radiation amount control means 14, when the thermostat valve 10 is stuck in the open state when the open failure is detected, the actual cooling water temperature TS decreases. The control is performed so that the deviation increases, and when the thermostat valve 10 is normally opened at the time of detection of the closed failure, the actual cooling water temperature TS is reduced so that the actual cooling water temperature TS becomes substantially equal to the switching temperature TT. In the controlled state, the failure detection of the thermostat valve 10 by the failure detection means 13 is performed again, so that the open failure or the closed failure of the thermostat valve 10 is determined. It is possible to detect the probability.

In the above embodiment, the thermostat valve 10 is constituted by an electric control valve that is electrically controlled to open and close, and the opening and closing temperature TT of the thermostat valve 10 is set in accordance with the operating state of the engine. Although the engine including the temperature setting unit 11 has been described,
The present invention is also applicable to an engine having a mechanical thermostat valve in which the opening / closing temperature TT is set to a constant value.

In an engine provided with a thermostat valve 10 comprising the above-mentioned electric control valve and an opening / closing temperature setting means 11, when an open failure of the thermostat valve 10 is executed in a closed temperature range, the failure detection means Until the detection of the failure by 13 is completed, the opening / closing temperature of the thermostat valve 10 is set to a higher temperature side (for example, about 90 ° C.) than usual by the above-mentioned opening / closing temperature setting means 11, and the closing failure of the thermostat valve 10 is opened. When the operation is performed in the valve temperature range, the thermostat valve 1 is controlled by the open / close temperature setting unit 11 until the failure detection by the failure detection unit 13 is completed.
The opening / closing temperature TT of 0 is set to a lower temperature side than normal (for example, 70 °).
C), the thermostat valve 10
Open faults and closed faults may be accurately detected.

That is, as shown in FIG. 5, the thermostat valve 1 set by the opening / closing temperature setting means 11 is used.
It is determined whether the open / close temperature TT of 0 is higher than the actual cooling water temperature TS detected by the temperature sensor 6 (Step S31), and YES is determined in Step S31,
When it is confirmed that the opening / closing temperature TT is higher than the actual cooling water temperature TS, that is, in the valve closing temperature range of the thermostat valve 10, the opening / closing temperature setting means 11 is used.
In step S32, the opening / closing temperature TT of the thermostat valve 10 is set higher than normal.

Next, the failure detection control by the failure detection means 13 is executed, whereby the thermostat valve 10 is controlled.
Is detected (step S33), the control of opening and closing the thermostat valve based on the deviation between the above-mentioned opening and closing temperature TT and the actual cooling water temperature TS is executed (step S34).

Further, when the determination at step S31 is NO, the opening / closing temperature TT of the thermostat valve 10 is lower than the actual cooling water temperature TS, that is, the thermostat valve 10
If it is confirmed that the temperature is in the valve opening temperature range, after the opening / closing temperature setting means 11 sets the opening / closing temperature TT to a temperature lower than normal (step S35), the process proceeds to step S33 to cause a failure. By executing the failure detection control by the detection means 13, a closed failure of the thermostat valve 10 is detected.

As described above, when the open failure of the thermostat valve 10 is detected, in addition to the control for increasing the heat radiation amount of the radiator 2, the control for setting the open / close temperature TT to the higher temperature side is executed. In this case, it is determined whether or not the feedback control for bringing the actual cooling water temperature TS close to the high opening / closing temperature TT is properly performed based on the deviation, thereby determining the opening / closing temperature TT of the thermostat valve 10 and the actual cooling temperature. Without causing erroneous detection due to a small deviation from the water temperature TS, the thermostat valve 10
Can be detected more accurately.

Also, as described above, the thermostat valve 10
When detecting the closing failure of the radiator 2, if the control for setting the opening / closing temperature TT on the low temperature side is executed in addition to the control for increasing the heat radiation amount of the radiator 2, the actual By determining whether the feedback control for bringing the cooling water temperature TS close to the low opening / closing temperature TT is properly performed, it is possible to reduce the deviation between the opening / closing temperature TT of the thermostat valve 10 and the actual cooling water temperature TS. The closing failure of the thermostat valve 10 can be detected more accurately without causing erroneous detection.

It should be noted that the determination in step S31 is omitted, the open fault detection control when the open / close temperature TT of the thermostat valve 10 is set to the high temperature side, and the closed fault when the open / close temperature TT is set to the low temperature side. And the detection control of the thermostat valve 1
Zero failure diagnosis may be performed.

When the opening / closing temperature setting means 11 confirms that the opening / closing temperature TT is set to a low temperature side when the opening failure is detected, the failure detecting means 13 detects the opening failure of the thermostat valve 10. And when the opening / closing temperature setting means 11 confirms that the opening / closing temperature TT is set to the high temperature side when the closing failure is detected, the failure detecting means 13 detects the closing failure of the thermostat valve 10. Is prevented, the occurrence of erroneous detection due to a small deviation between the opening / closing temperature TT and the actual cooling water temperature TS is prevented, and the thermostat valve 10 is prevented.
May be detected accurately.

Further, in the above embodiment, as shown in FIG. 3, the deviation ΔT between the opening / closing temperature TT of the thermostat valve 10 and the actual cooling water temperature TS during the feedback control.
The thermostat valve 1 is detected by the failure detection means 13 based on the
Since it is configured to detect the failure of 0, an open failure or a closed failure of the thermostat valve 10 can be accurately detected with a simple configuration.

The radiator 2 is driven by driving a cooling fan 20 for supplying cooling air to the radiator 2.
Instead of the above-described embodiment having the heat radiation amount control means 14 for increasing the heat radiation amount of the radiator 2, the discharge area of the radiator 2 is controlled by controlling the opening area increasing means for increasing the opening area of the cooling air inlet to the radiator 2. Increase the amount of heat,
Alternatively, a configuration may be adopted in which both the cooling fan 20 and the area increasing means are controlled to increase the heat radiation amount of the radiator 2.

[0061]

As described above, the present invention provides a failure detecting means for detecting at least one of an open failure and a closed failure of a thermostat valve for adjusting the temperature of cooling water of an engine, and a method for detecting a failure by the failure detecting means. Since the heat radiation amount control means for controlling the heat radiation amount of the radiator is increased, the open failure or the close failure of the thermostat valve can be quickly and quickly performed without erroneous diagnosis due to the small heat radiation amount of the radiator. There is an advantage that an accurate diagnosis can be made.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a cooling system including a thermostat failure diagnosis device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a basic control operation for failure detection.

FIG. 3 is a flowchart illustrating a specific example of failure detection control.

FIG. 4 is a graph showing a change state of a cooling water temperature.

FIG. 5 is a flowchart showing another example of the basic control operation for failure detection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 2 Radiator 10 Thermostat valve 11 Opening / closing temperature setting means 20 Cooling fan 13 Failure detection means 14 Heat release amount control means

Claims (5)

[Claims] 1. A failure detection means for detecting at least one of an open failure and a close failure of a thermostat valve for adjusting a temperature of a cooling water of an engine, and increasing a heat radiation amount of a radiator when the failure detection means detects a failure. A thermostat failure diagnosis device, comprising: a heat radiation amount control means for controlling the heat radiation amount. 2. The thermostat failure diagnosis apparatus according to claim 1, wherein when the failure detection means detects a failure of the thermostat valve, the heat radiation amount is determined only when the vehicle is confirmed to be in a low-speed running state. A thermostat failure diagnosis device, characterized in that the control means executes control for increasing the heat radiation amount of the radiator. 3. The failure diagnostic device for a thermostat according to claim 1, wherein the failure detection means determines whether the thermostat valve is in a failure state or in a normal state.
Also, it is configured to determine whether or not the detection is in a hold state where accurate detection is difficult, and to perform the re-failure detection of the thermostat valve when the reservation determination is performed, and to detect the re-failure of the thermostat valve by the failure detection means. A thermostat failure diagnosis apparatus characterized in that only the heat radiation amount control means executes control to increase the heat radiation amount of the radiator. 4. The thermostat failure diagnosis apparatus according to claim 1, wherein the thermostat valve is constituted by an electric control valve that is electrically controlled to open and close, and the temperature of opening and closing of the thermostat valve is controlled by an engine. Opening / closing temperature setting means for setting corresponding to the operation state of
At the time of detection of an open failure of the thermostat valve by the failure detection means, in a state where the opening and closing temperature of the thermostat valve is set to a high temperature side, control for increasing the amount of heat radiation in the radiator is executed.
A thermostat failure diagnostic device configured to execute a control for increasing a heat radiation amount in the radiator in a state where an opening / closing temperature of the thermostat valve is set to a low temperature side. 5. The thermostat failure diagnostic device according to claim 1, wherein the heat radiation amount control means includes a cooling fan for supplying cooling air to the radiator or an opening area of a cooling air intake for the radiator. A thermostat failure diagnosis device configured to execute control for increasing the heat radiation amount of the radiator by controlling at least one of the opening area increasing means for increasing the opening area.