Refrigerator

1. A refrigerator comprising:

a cabinet having a storage chamber; and

a door configured to open and close at least a portion of the storage chamber,

wherein the door comprises:

a panel assembly comprising:

a front panel that is made of glass and defines a front surface of the door,

a rear panel made of glass and spaced apart from the front panel, the rear panel defining a rear surface of the door, and

a rod that is disposed between the front panel and the rear panel and defines a sealed space between the front panel and the rear panel,

a side frame that is coupled to the front panel and defines a side surface of the door,

an upper frame that is coupled to the side frame and defines an upper surface of the door,

a lower frame that is coupled to the side frame and defines a lower surface of the door,

a door liner that has a rectangular frame shape and is coupled to the upper frame, the lower frame, the side frame, and the rear panel, and

an insulator provided in a foaming space that is defined by the panel assembly, the upper frame, the lower frame, and the side frame,

wherein at least one of the upper frame or the lower frame comprises:

a main part that defines a horizontal exterior of the door,

a front surface portion that extends vertically from the main part and is disposed on the front panel, and

a front protruding portion that extends forward from the main part and is seated on the front panel, and

wherein the main part defines a contraction prevention groove that is depressed and extends along the main part in a longitudinal direction of the main part parallel to the front panel, wherein the contraction prevention groove is disposed between the main part and the front protruding portion.

2. The refrigerator of claim 1 , wherein the at least one of the upper frame or the lower frame further comprises:

a rear surface portion that vertically extends from the main part and defines an attachment surface to which a front surface of the door liner is coupled; and

a rear protruding portion that extends rearward from the main part, and

wherein the main part further defines another contraction prevention groove that is depressed from the main part and extends in the longitudinal direction parallel to the door liner.

3. The refrigerator of claim 1 , wherein the at least one of the upper frame or the lower frame further comprises:

a plurality of reinforcement ribs that are arranged with intervals and configured to restrict the at least one of the upper frame or the lower frame from twisting or bending in a foaming process of a foam solution.

4. The refrigerator of claim 1 , wherein the main part defines an inlet having a stepped surface, and

wherein the at least one of the upper frame or the lower frame further comprises a shield cover that covers the inlet after injecting a foam solution through the inlet and that is seated on the stepped surface.

5. The refrigerator of claim 1 , wherein a width of the front panel is greater than a width of the rear panel, and an edge of the front panel protrudes outward relative to an edge of the rear panel to thereby define a protruding portion of the front panel,

wherein the panel assembly further comprises:

a bezel portion located at the protruding portion of the front panel; and

a see-through portion provided inside the bezel portion, and

wherein the front surface portion is positioned at a rear side of the bezel portion.

6. The refrigerator of claim 5 , wherein at least one of the upper frame or the lower frame further comprises a sensor mounting part that is depressed from the main part and that defines a space configured to receive a door sensor, and

wherein the sensor mounting part comprises:

a sensing part disposed at the rear side of the bezel portion, and

a plurality of transfer ribs that are spaced apart from one another and protrude from the main part.

7. The refrigerator of claim 5 , further comprising:

a locking device disposed at the rear side of the bezel portion, the locking device comprising:

a handle disposed at the lower frame;

a long bar that extends upward from the handle and is disposed within the foaming space;

a locking housing that covers the locking device and protects the locking device in a foaming process;

a locking part having a hook structure, the locking part being configured to operate in conjunction with the handle; and

an elastic member disposed in the locking device and configured to cause the handle to move to an initial location of the handle.

8. The refrigerator of claim 2 , wherein the door liner further comprises:

a locking arm having a cantilever shape and protruding from the front surface of the door liner, the locking arm being configured to couple to the rear surface portion in the upper frame.

9. The refrigerator of claim 8 , wherein the door liner further comprises:

a locking hook having a cantilever shape and protruding from the front surface of the door liner, the locking hook being configured to couple to the rear surface portion in the lower frame.

10. The refrigerator of claim 1 , wherein the door liner further comprises:

a center portion that is open in a thickness direction of the door liner and exposes the rear panel in a rearward direction;

a foam boundary portion that protrudes relative to the center portion and defines a periphery of the center portion; and

a damping plate disposed within the foaming space between the foam boundary portion and the rear panel.

11. The refrigerator of claim 1 , wherein the side frame comprises a side front surface portion coupled to the front surface portion of the upper frame by a coupling member.

12. The refrigerator of claim 11 , wherein the coupling member comprises:

a locking arm that projects from the side front surface portion of the side frame;

a locking hole defined at a front surface portion of the side frame; and

a locking hook that projects from the front surface portion in the upper frame, the locking hook being configured to insert into the locking hole based on the side frame being coupled to the upper frame.

13. The refrigerator of claim 11 , wherein the upper frame has a stepped assembly surface disposed at the front surface portion, and

wherein the side front surface portion of the side frame is coupled to the stepped assembly surface.

14. The refrigerator of claim 1 , wherein a front protruding end of the front protruding portion is located between a front surface of the front panel and a rear surface of the front panel in a thickness direction.

15. The refrigerator of claim 1 , wherein the side frame comprises a side front surface portion attached to a rear surface of the front panel by an adhesive or an adhesive tape.

16. The refrigerator of claim 5 , further comprising a heating device disposed at the bezel portion.

17. The refrigerator of claim 16 , further comprising a heater housing that covers the heating device and is attached to the bezel portion by an adhesive or an adhesive tape.

18. The refrigerator of claim 1 , wherein each of the upper frame and the lower frame comprises the main part, the front surface portion, and the front protruding portion.

19. The refrigerator of claim 1 , wherein the longitudinal direction of the main part is a left-right direction of the door.