Air conditioner cut control system and method thereof

1. An air conditioner cut control system comprising:

a driving condition detection unit configured of detecting operation conditions of a vehicle;

an air conditioner controller configured of determining an intake manifold negative pressure stored in a brake booster at a value obtained by subtracting intake manifold pressure from an atmospheric pressure detected by the driving condition detection unit when an air conditioner is operated; and

an engine control unit (ECU) configured of integrating the intake manifold negative pressure according to a brake negative pressure prediction logic and determining a virtual brake booster sensor value by modeling change of booster negative pressure according to driving information, and when the virtual brake booster sensor value is below a reference negative pressure of an A/C CUT standard logic, the ECU is configured to determine that brake negative pressure is insufficient and activates A/C CUT,

wherein the ECU is configured to set an initial value of the virtual brake booster sensor value, which corresponds to a first ratio of the intake manifold negative pressure initially determined when the air conditioner is operated,

wherein the ECU is configured to determine a temporary sensor value as a value corresponding to a second ratio of an intake manifold negative pressure peak value detected during a system update unit time in a charging condition of the booster negative pressure in which a brake is not operated, and

wherein the second ratio is lower than the first ratio.

2. The air conditioner cut control system of claim 1 , further including:

a memory that stores the brake negative pressure prediction logic and stores modeling information related to the change of the booster negative pressure according to the intake manifold negative pressure and the driving information.

3. The air conditioner cut control system of claim 1 ,

wherein the driving condition detection unit detects at least a driving information among an air conditioner operation condition, a vehicle speed, an atmospheric pressure, an intake manifold pressure, a brake operation condition, an altitude, a road gradient, a timer and a vehicle deceleration.

4. The air conditioner cut control system of claim 1 ,

wherein the ECU is configured to update the virtual brake booster sensor value by exceeding the temporary sensor value when the temporary sensor value exceeds the virtual brake booster sensor value set to the initial value.

5. The air conditioner cut control system of claim 1 ,

wherein the ECU is configured to fix the virtual brake booster sensor value to a predetermined value less than the reference negative pressure when the vehicle travels on a road having a predetermined gradient.

6. The air conditioner cut control system of claim 1 ,

wherein the ECU is configured to update the virtual brake booster sensor value to reflect a brake negative pressure decompression rate by referring to a virtual brake booster sensor decompression rate control map in accordance with a brake operation in the booster negative pressure release condition.

7. The air conditioner cut control system of claim 6 ,

wherein the ECU is configured to determine a booster decompression rate corresponding to a vehicle deceleration and the intake manifold negative pressure in the virtual brake booster sensor decompression rate control map during brake operation, and the ECU subtracts value of which the booster decompression rate is lasted for a system update time from the virtual brake booster sensor value.

8. The air conditioner cut control system of claim 6 ,

wherein the virtual brake booster sensor decompression rate control map is set to increase a booster decompression rate as the vehicle deceleration increases under the same intake manifold negative pressure.

9. The air conditioner cut control system of claim 8 ,

wherein the virtual brake booster sensor decompression rate control map is set to decrease the booster decompression rate as the intake manifold negative pressure increases under the same intake manifold negative pressure.

10. The air conditioner cut control system of claim 1 ,

wherein the ECU reduces the reference negative pressure of the A/C CUT standard logic as the virtual brake booster sensor value increases by referring altitude change.

11. The air conditioner cut control system of claim 1 ,

wherein the ECU is configured to increase a MAX vehicle speed condition of the A/C CUT standard logic at altitudes above a predetermined altitude by referring to a vehicle speed condition change map according to an altitude change condition.

12. An air conditioner cut control method for a vehicle of which a virtual brake booster sensor according to a brake negative pressure prediction logic is applied, the air conditioner cut control method comprising:

(a) detecting, by a controller, operating information related to the vehicle when an air conditioner (A/C) is activated, and determining an intake manifold negative pressure stored in a brake booster at a value obtained by subtracting intake manifold pressure from an atmospheric pressure;

(b) setting, by the controller, a value corresponding to a first ratio of the determined intake manifold negative pressure to an initial value of a virtual brake booster sensor value;

(c) updating, by the controller, the virtual brake booster sensor value to an exceeded value when the value corresponding to a second ratio of an intake manifold negative pressure peak value exceeds the initial value in which a brake is not operated;

(d) subtracting, by the controller, a booster decompression rate corresponding to a vehicle deceleration and an intake manifold negative pressure condition from the virtual brake booster sensor value when the brake is actuated; and

(e) activating, by the controller, A/C CUT when the virtual brake booster sensor value is less than a reference negative pressure of an A/C CUT standard logic,

wherein the step (c) includes:

for a predetermined time storing a value corresponding to a second ratio of the intake manifold negative pressure peak value detected at a predetermined system update unit time to a temporary sensor value, wherein the second ratio is lower than the first ratio;

maintaining the temporary sensor value when the temporary sensor value is less than the virtual brake booster sensor value; and

when the temporary sensor value exceeds the virtual brake booster sensor value, updating the virtual brake booster sensor value to be a same as the exceeded temporary sensor value.

13. The air conditioner cut control method of claim 12 , wherein the step (c) or the step (d) includes:

fixing the virtual brake booster sensor value to a predetermined value less than the reference negative pressure when it is determined by the ECU that the vehicle is traveling on a gradient road by detecting a road inclination in driving information.

14. The air conditioner cut control method of claim 12 , wherein the step (d) includes:

collecting the intake manifold negative pressure and vehicle deceleration from driving information;

determining the booster decompression rate according to the intake manifold negative pressure and the vehicle deceleration in a virtual brake booster sensor decompression rate control map; and

determining a first virtual brake booster sensor value in which the booster decompression rate is subtracted from the virtual brake booster sensor value.

15. The air conditioner cut control method of claim 14 ,

wherein the first virtual brake booster sensor value is determined by subtracting the booster decompression rate times the predetermined system update unit time from the virtual brake booster sensor value.

16. The air conditioner cut control method of claim 12 ,

wherein in the step (e), an A/C CUT reference negative pressure condition is changed according to the virtual brake booster sensor value and an altitude by referring to a variable reference negative pressure setting map, and

wherein the reference negative pressure is decreased as the virtual brake booster sensor value is increased, and the reference negative pressure of the A/C CUT standard logic increases as the altitude rises.

17. The air conditioner cut control method of claim 12 ,

wherein in the step (e), a MAX vehicle speed condition of the A/C CUT standard logic is increased at altitudes above a predetermined altitude by referring to a vehicle speed condition change map according to an altitude change condition.