[Claim 1]
An air-conditioning apparatus indoor unit comprising:
a plastic design panel that includes a front panel part having a rectangular shape in front view and a flange part projecting toward a back surface from one longitudinal edge of the front panel part; and
a reinforcement member that has a shape extending in a longitudinal direction of the front panel part across a middle part of the design panel and is fixed to the design panel so as to be in contact with a back surface of the front panel part and an inner surface of the flange part. [Claim 2]
The air-conditioning apparatus indoor unit of Claim 1, wherein
the front panel part has, on the back surface thereof, at least two panel-side restricting-and-fixing claws that support one end and an other end of the reinforcement member and restrict a position of the reinforcement member, and
the flange part has, on the inner surface thereof, at least one flange-side fixing claw that supports a flange-part-side edge of the reinforcement member. [Claim 3]
The air-conditioning apparatus indoor unit of Claim 1, wherein
the front panel part has, on the back surface thereof, at least one panel-side fixing claw that supports a front-panel-part-side edge of the reinforcement member, and
the flange part has, on the inner surface thereof, at least two flange-side restricting-and-fixing claws that support one end and an other end of the reinforcement member and restrict a position of the reinforcement member. [Claim 4]
The air-conditioning apparatus indoor unit of Claim 1, wherein

the front panel part has, on the back surface thereof, two panel-side restricting-and-fixing claws that support one end and an other end of the reinforcement member and restrict a position of the reinforcement member, and
the flange part has, on the inner surface thereof, at least two flange-side restricting-and-fixing claws that support the one end and the other end of the reinforcement member and restrict the position of the reinforcement member. [Claim 5]
The air-conditioning apparatus indoor unit of Claim 4, wherein
the front panel part has, on the back surface thereof, at least one panel-side fixing claw that supports a front-panel-part-side edge of the reinforcement member, and
the flange part has, on the inner surface thereof, at least one flange-side fixing claw that supports a flange-part-side edge of the reinforcement member. [Claim 6]
The air-conditioning apparatus indoor unit of any one of Claims 1 to 5, wherein the design panel has two touch-preventing walls at positions adjacent to an one end and an other end of the reinforcement member so as to project and extend over the back surface of the front panel part and the inner surface of the flange part. [Claim 7]
The air-conditioning apparatus indoor unit of Claims 4 or 5, wherein the design panel includes: a one-end touch-preventing wall that connects the panel-side restricting-and-fixing claw and the flange-side restricting-and-fixing claw at the one end of the reinforcement member and projects from the back surface of the front panel part and the inner surface of the flange part; and an other-end touch-preventing wall that connects the panel-side restricting-and-fixing claw and the flange-side restricting-and-fixing claw at the other end of the reinforcement

member and projects from the back surface of the front panel part and the inner surface of the flange part. [Claim 8]
The air-conditioning apparatus indoor unit of any one of Claims 1 to 7, wherein the reinforcement member is made of metal, and at least one of a front-panel-part-side edge and a flange-part-side edge thereof is subjected to contact-bending processing. [Claim 9]
The air-conditioning apparatus indoor unit of any one of Claims 1 to 8, wherein the reinforcement member is formed so as to have an L shape in section according to an angle formed between the back surface of the front panel part and the inner surface of the flange part. [Claim 10]
The air-conditioning apparatus indoor unit of any one of Claims 1 to 9, wherein the design panel is provided with, in at least one of the back surface of the front panel part and the inner surface of the flange part, a recessed groove part that accommodates at least a portion of the reinforcement member. [Claim 11]
The air-conditioning apparatus indoor unit of any one of Claims 1 to 10, wherein a longitudinal length of the reinforcement member is 70% or more of a longitudinal length of the front panel part. [Claim 12]
The air-conditioning apparatus indoor unit of any one of Claims 1 to 11, wherein the longitudinal direction of the front panel part is a left-right direction of the front panel part, and the one longitudinal edge of the front panel part is a lower longitudinal edge of the front panel part.