Mix door and vehicle air conditioner using the same

1. A mix door comprising: at least three slide door units serially connected to one another; a slide driving part configured to drive each of the slide door units; and a gear cover partially covering the slide driving part, wherein the slide driving part includes a gear mechanism portion formed of a rack portion and a gear assembly, the at least three slide door units include a middle slide door unit having an output gear directly meshing with the rack, and each of the slide door units includes a slide door case, and wherein the gear cover is provided to cover the output gear and connect both side surfaces of the slide door case, the slide door case of the middle slide door unit is divided into at least two slide door case pieces, and the gear cover is divided into at least two gear cover portions connected by a connection portion.

2. The mix door according to claim 1 , wherein the gear assembly includes an input gear transmitting a driving force to the output gear; and the gear cover covers the input gear.

3. The mix door according to claim 1 , wherein the gear cover includes a portion having a cylindrical-surface shape extending along an external shape of the gear mechanism portion.

4. A vehicle air conditioner comprising:

a hollow air conditioner housing; and

an evaporator and the mix door according to claim 1 which are provided inside the housing.

5. A vehicle air conditioner comprising: a hollow air conditioner housing; the mix door according to claim 1 which is provided inside the housing; an evaporator configured to be mounted inside the housing near the mix door by being inserted from an opening portion provided in a side surface portion of the housing, wherein the at least two side door case pieces of the middle slide door unit of the mix door formed of three or more slide door units serially connected to one another, include left and right case pieces, and the gear cover includes a hook portion and a hook receiving portion connecting the left and right case pieces; and paired guide ribs formed to extend in a mounting direction of the evaporator and capable of protecting both side portions of the hook portion and the hook receiving portion.

6. A vehicle air conditioner comprising: a hollow air conditioner housing; the mix door according to claim 1 which is provided inside the housing; an evaporator configured to be mounted inside the housing near the mix door by being inserted from an opening portion provided in a side surface portion of the housing; wherein the at least two slide door case pieces of the slide door case of the middle slide door unit include left and right case pieces, and the gear cover includes a hook portion and a hook receiving portion connecting the left and the right case pieces; paired guide ribs formed to extend in a mounting direction of the evaporator and capable of protecting both side portions of the hook portion and the hook receiving portion, wherein each of the guide ribs includes an inclined surface inclined upward toward a top portion of the hook receiving portion.

7. A vehicle air conditioner comprising: a hollow air conditioner housing; the mix door according to claim 1 which is provided inside the housing; an evaporator configured to be mounted inside the housing near the mix door by being inserted from an opening portion provided in a side surface portion of the housing; wherein the at least two slide door pieces of the slide door case of the middle slide door unit include left and right case pieces, and the gear cover includes a hook portion and a hook receiving portion connecting the left and right case pieces; paired guide ribs formed to extend in a mounting direction of the evaporator and capable of protecting both side portions of the hook portion the hook receiving portion, wherein each of the guide ribs includes an inclined surface inclined upward toward a top portion of the hook receiving portion.