Hybrid electric vehicle and method of controlling shift pattern therefor

1. A method of controlling shift pattern change of a hybrid electric vehicle (HEV), the method comprising:

determining whether or not a shift pattern change is required;

determining whether or not an HEV mode related condition is satisfied, in response to a determination that the shift pattern change is required; and

performing the shift pattern change according to a determination that the shift pattern change is required, when it is determined that the HEV mode related condition is satisfied,

wherein the determining whether or not a shift pattern change is required comprises:

determining whether a first shift pattern change from a first shift pattern based on motor efficiency to a second shift pattern based on engine efficiency is required or a second shift pattern change from the second shift pattern to the first shift pattern is required, and

wherein, in response to the determination that the first shift pattern change is required, the HEV mode related condition being satisfied comprises determination that a transition from an EV mode to an HEV mode is going to occur.

2. The method according to claim 1 , further comprising:

determining whether or not shifting occurs, after performing the first shift pattern change;

delaying mode transition to the HEV mode until shifting is completed, in response to a determination that occurrence of shifting is expected; and

executing the mode transition when shifting is completed.

3. The method according to claim 1 , further comprising delaying the first shift pattern change until the determination of the transition from the EV mode to the HEV mode is made, in response to the determination that the first shift pattern change is required.

4. The method according to claim 1 , wherein, in response to a determination that the second shift pattern change is required, the HEV mode related condition being satisfied comprises at least one of a case that the hybrid electric vehicle is not driven in the HEV mode and a case that there is a low possibility that the hybrid electric vehicle is driven in the HEV mode.

5. The method according to claim 4 , wherein the case that there is a low possibility that the hybrid electric vehicle is driven in the HEV mode excludes at least an uphill driving situation, a high-speed driving situation or a situation using low electrical load.

6. The method according to claim 4 , further comprising, in response to a determination that the HEV mode related condition is not satisfied, delaying the second shift pattern change until the HEV mode related condition is satisfied.

7. The method according to claim 1 , wherein:

the first shift pattern includes a charge depleting (CD) shift pattern; and

the second shift pattern includes a charge sustaining (CS) shift pattern.

8. A non-transitory computer readable recording medium having a program recorded therein to implement the method according to claim 1 .

9. A hybrid electric vehicle comprising:

a first controller configured to:

determine whether or not a shift pattern change is required,

determine whether or not a HEV mode related condition is satisfied in response to a determination that the shift pattern change is required, and

determine to perform the shift pattern change according to the determination that the shift pattern change is required, when it is determined that the HEV mode related condition is satisfied; and

a second controller configured to control a transmission,

wherein the second controller is further configured to perform the shift pattern change according to a control command from the first controller,

wherein the first controller determines whether a first shift pattern change from a first shift pattern based on motor efficiency to a second shift pattern based on engine efficiency is required, or a second shift pattern change from the second shift pattern to the first shift pattern is required, and

wherein, in response to the determination that the first shift pattern change is required, the HEV mode related condition being satisfied comprises determination that a transition from an EV mode to an HEV mode is going to occur.

10. The hybrid electric vehicle according to claim 9 , wherein the first controller is further configured to:

determine whether or not shifting occurs, after performing the first shift pattern change,

delay mode transition to the HEV mode until shifting is completed, in response to a determination that occurrence of shifting is expected, and

execute the mode transition when shifting is completed.

11. The hybrid electric vehicle according to claim 9 , wherein the first controller is further configured to delay the first shift pattern change until the determination of the transition from the EV mode to the HEV mode is made, in response to the determination that the first shift pattern change is required.

12. The hybrid electric vehicle according to claim 9 , wherein, in response to a determination that the second shift pattern change is required, the HEV mode related condition being satisfied comprises at least one of a case that the hybrid electric vehicle is not driven in the HEV mode and a case that there is a low possibility that the hybrid electric vehicle is driven in the HEV mode.

13. The hybrid electric vehicle according to claim 12 , wherein the case that there is a low possibility that the hybrid electric vehicle is driven in the HEV mode excludes at least one of an uphill driving situation, a high-speed driving situation and a situation using low electrical load.

14. The hybrid electric vehicle according to claim 12 , wherein, in response to a determination that the HEV mode related condition is not satisfied, the first controller is configured to delay the second shift pattern change until the HEV mode related condition is satisfied.

15. The hybrid electric vehicle according to claim 9 , wherein:

the first shift pattern includes a CD shift pattern; and

the second shift pattern includes a CS shift pattern.