Solenoid valve diagnostic apparatus and method

1. A solenoid valve diagnostic apparatus, comprising:

a plurality of solenoid valves each configured to open or close an entrance/exit opening of a fuel tank;

a single current sensor configured to measure an operating current supplied to the solenoid valves; and

a controller configured to diagnose whether the solenoid valves fail, based on the operating current measured by the current sensor, wherein diagnosing whether the solenoid valves fail includes:

in a current check step of a plurality of check steps, determining whether the measured operating current is less than a reference current for the current check step; and

when the measured operating current is less than the reference current for the current check step, entering a diagnostic mode for the current check step;

wherein the reference currents are differently set for respective check steps of the plurality of check steps; and

wherein the number of check steps is determined by the number of solenoid valves.

2. The solenoid valve diagnostic apparatus of claim 1 , wherein the controller:

changes duties of PWM control signals transmitted to the solenoid valves when the controller enters the diagnostic mode; and

determines a solenoid valve normal situation, when the duties of the PWM control signals and duties of PWM control signals fed back from the solenoid valves are inverted.

3. The solenoid valve diagnostic apparatus of claim 2 , wherein the controller maintains the current check step, when the solenoid valve normal situation is determined in the diagnostic mode.

4. The solenoid valve diagnostic apparatus of claim 2 , wherein the controller determines solenoid valve failure, when the duties of the PWM control signals and the duties of the PWM control signals fed back are not inverted.

5. The solenoid valve diagnostic apparatus of claim 4 , wherein the controller transitions to a following check step, when the solenoid valve failure is determined.

6. The solenoid valve diagnostic apparatus of claim 1 wherein the apparatus contains a single current sensor that is configured to measure an operating current of the plurality of solenoid valves.

7. The solenoid valve diagnostic apparatus of claim 1 consisting of:

a) a plurality of solenoid valves each configured to open or close an entrance/exit opening of a fuel tank;

b) a single current sensor configured to measure an operating current of the plurality of solenoid valves; and

c) a controller configured to diagnose whether the solenoid valves fail, based on the operating current measured by the current sensor.

8. A solenoid valve diagnostic method, comprising the steps of:

measuring, by a single current sensor, an operating current supplied to a plurality of solenoid valves; and

diagnosing, by a controller, whether the solenoid valves fail, based on the measured operating current;

wherein diagnosing whether the solenoid valves fail includes:

in a current check step of a plurality of check steps, determining whether the measured operating current is less than a reference current for the current check step; and

when the measured operating current is less than the reference current for the current check step, entering a diagnostic mode for the current check step;

wherein the reference currents are differently set for respective check steps of the plurality of check steps; and

wherein the number of check steps is determined by the number of solenoid valves.

9. The solenoid valve diagnostic method of claim 8 , wherein diagnosing whether the solenoid valves fail further includes

determining solenoid valve failure by using a PWM feedback measurement method in the diagnostic mode.

10. The solenoid valve diagnostic method of claim 9 , wherein determining the solenoid valve failure includes:

changing duties of PWM control signals transmitted to the solenoid valves;

identifying duties of PWM control signals fed back from the solenoid valves;

determining a solenoid valve normal situation, when the duties of the PWM control signals and the duties of the PWM control signals fed back are inverted; and

determining solenoid valve failure, when the duties of the PWM control signals and the duties of the PWM control signals fed back are not inverted.

11. The solenoid valve diagnostic method of claim 10 , wherein diagnosing whether the solenoid valves fail includes:

transitioning to a following check step, when the solenoid valve failure is determined.

12. The solenoid valve diagnostic method of claim 10 , wherein diagnosing whether the solenoid valves fail further includes:

maintaining the current check step, when the solenoid valve normal situation is determined.

13. The method of claim 8 wherein an operating current of a plurality of solenoid valves is measured by a single current sensor.