Method and system for diagnosing failure of piston cooling device

1. A method for diagnosing a failure of a solenoid valve of a piston cooling device, comprising:

when an opening command or a closing command of the solenoid valve is transmitted to inject oil from the piston cooling device, varying, by a controller, a pressure in a variable proportional control oil pump;

monitoring, by the controller, a variation of an oil pressure in an oil flow path of the piston cooling device according to a variation of the pressure in the variable proportional control oil pump, the oil pressure in the oil flow path being measured using an oil pressure switch or an oil pressure sensor disposed at a supply flow path of oil supplied to the piston cooling device; and

after the opening command or the closing command of the solenoid valve is transmitted, determining, by the controller, whether or not a failure occurs at the solenoid valve of the piston cooling device based on whether or not the variation occurs in the oil pressure in the oil flow path measured by the oil pressure switch or the oil pressure sensor in accordance with the variation of the pressure of the variable proportional control oil pump.

2. The method of claim 1 , further comprising:

when the solenoid valve is in a state in which the closing command is transmitted, varying, by the controller, an oil discharge pressure of the variable proportional control oil pump;

determining, by the controller, whether a variation occurs at an oil pressure switch configured to monitor a pressure of oil supplied to the piston cooling device; and

when a variation occurs in the oil pressure in the oil flow path, determining, by the controller, that an open-stuck failure occurs at the solenoid valve of the piston cooling device.

3. The method of claim 1 , further comprising:

when the solenoid valve is in a state in which the opening command is transmitted, varying, by the controller, an oil discharge pressure of the variable proportional control oil pump;

determining, by the controller, whether a variation occurs at an oil pressure switch configured to monitor a pressure of oil supplied to the piston cooling device; and

when no variation occurs in the oil pressure in the oil flow path, determining, by the controller, that a closing-stuck failure occurs at the solenoid valve of the piston cooling device.

4. The method of claim 2 , further comprising:

when the failure is determined to occur at the piston cooling device, warning, by the controller, a driver of a failure occurrence of the piston cooling device using a failure display.

5. The method of claim 3 , further comprising:

when the failure is determined to occur at the piston cooling device, warning, by the controller, a driver of a failure occurrence of the piston cooling device using a failure display.

6. The method of claim 3 , further comprising:

when the failure is determined to occur at the piston cooling device, restricting, by the controller, an output of an engine when a temperature of cooling water of the engine is equal to or greater than a preset temperature.

7. A system for diagnosing a failure of a solenoid valve of a piston cooling device, comprising:

a piston cooling device installed at a cylinder block and configured to inject oil in an oil pan into a piston;

an oil pressure switch or an oil pressure sensor configured to monitor a pressure of oil supplied to the piston cooling device;

a variable proportional control oil pump configured to form an oil pressure of an engine;

a solenoid valve of the piston cooling device configured to open and close a supply flow path supplying oil, which is formed by the variable proportional control oil pump, to a piston cooling jet; and

an electronic control unit (ECU) configured to operate the variable proportional control oil pump, receive information regarding whether a variation occurs in an oil pressure value from the oil pressure switch or the oil pressure sensor disposed at a supply flow path of oil supplied to the piston cooling jet, transmit an opening command or a closing command to the solenoid valve of the piston cooling device, operate the variable proportional control oil pump to vary an oil discharge pressure discharged therefrom, and determine whether or not a failure occurs at the solenoid valve of the piston cooling device based on whether or not the variation occurs in the oil pressure value measured by the oil pressure switch or the oil pressure sensor in accordance with the variation of the pressure of the variable proportional control oil pump after the opening command or the closing command of the solenoid valve is transmitted.

8. The system of claim 7 , wherein when the solenoid valve of the piston cooling device is in a state in which the closing command is transmitted, the ECU is configured to determine that the variation occurs in the oil pressure value from the oil pressure switch or the oil pressure sensor when the oil discharge pressure of the variable proportional control oil pump is varied, and determine that an open-stuck failure occurs at the piston cooling device.

9. The system of claim 7 , wherein when the solenoid valve of the piston cooling device is in a state in which the opening command is transmitted, the ECU is configured to determine that no variation occurs in the oil pressure value from the oil pressure switch or the oil pressure sensor when the oil discharge pressure of the variable proportional control oil pump is varied, and determine that a closing-stuck failure occurs at the piston cooling device.

10. The system of claim 7 , further comprising:

a failure display configured to warn a driver of a failure occurrence when the failure occurs at the solenoid valve of the piston cooling device.

11. The system of claim 9 , wherein when the closing-stuck failure is determined to occur at the solenoid valve of the piston cooling device, the ECU is configured to restrict an output of an engine when a temperature of cooling water of the engine is equal to or greater than a preset temperature.

12. The system of claim 11 , wherein the output of the engine is restricted by limiting the output torque of the engine when the temperature of the cooling water of the engine is equal to or greater than the preset temperature.