Car air conditioning duct and railcar

1. A car air-conditioning duct configured to guide air to a suction side of an air conditioner mounted on a car or guide the air flowing from a blow-off side of the air conditioner mounted on the car, the car air-conditioning duct comprising:

a duct wall having a tubular shape,

a plurality of duct fixtures, the duct wall being attached to the car by the plurality of duct fixtures,

the duct wall forming a duct outer surface and a duct inner surface,

the duct wall being made of a composite foamed resin material containing polystyrene resin and polyolefin resin,

a content ratio of the polystyrene resin and a content ratio of the polyolefin resin each having a gradient in a thickness direction of the duct wall,

the content ratio of the polyolefin resin being higher than the content ratio of the polystyrene resin at the duct outer surface and the duct inner surface,

the duct wall having a rectangular cross section in which two face plate members are joined to each other at end edges thereof, the two face plate members having respective L-shaped cross sections arranged point symmetrically, being made of the composite foamed resin material,

each of the plurality of duct fixtures comprising a frame-shaped engaging portion engaged with the duct wall from outside the duct and coupling portions projecting from the engaging portion in a car width direction so as to separate from each other,

the engaging portion and the coupling portions being constituted by a band plate-shaped first part and a band plate-shaped second part, the first part and the second part being separated from each other in an upper/lower direction,

the first part and the second part being stacked on each other at the coupling portions,

the first part and the second part in a stacked state being also fastened to each other in the upper/lower direction by the duct fixtures and attachable to the car by the duct fixtures.

2. The car air-conditioning duct according to claim 1 , further comprising:

a closing member attached to a longitudinal direction terminal end portion of the duct wall, wherein

the closing member is made of a sound absorbing material.

3. A railcar comprising:

an air conditioner configured to adjust a temperature of suctioned air and blow out the air; and

an air conditioning duct configured to guide air to a suction side of the air conditioner or guide the air flowing from a blow-off side of the air conditioner,

the air conditioning duct including:

a duct wall having a tubular shape and forming a duct outer surface and a duct inner surface, and

a plurality of duct fixtures, the duct wall being attached to the car by the plurality of duct fixtures,

the duct wall being made of a composite foamed resin material containing polystyrene resin and polyolefin resin,

a content ratio of the polystyrene resin and a content ratio of the polyolefin resin each having a gradient in a thickness direction of the duct wall,

the content ratio of the polyolefin resin being higher than the content ratio of the polystyrene resin at the duct outer surface and the duct inner surface,

the duct wall having a rectangular cross section in which two face plate members are joined to each other at end edges thereof, the two face plate members having respective L-shaped cross sections arranged point symmetrically, being made of the composite foamed resin material,

the duct wall having a rectangular cross section in which two face plate members are joined to each other at end edges thereof, the two face plate members being arranged point symmetrically, being made of the composite foamed resin material, each having an L-shaped cross section,

each of the plurality of duct fixtures comprising a frame-shaped engaging portion engaged with the duct wall from outside the duct and coupling portions projecting from the engaging portion in a car width direction so as to separate from each other,

the engaging portion and the coupling portions being constituted by a band plate-shaped first part and a band plate-shaped second part, the first part and the second part being separated from each other in an upper/lower direction,

the first part and the second part being stacked on each other at the coupling portions,

the first part and the second part in a stacked state being also fastened to each other by the duct fixtures and attached to the car by the duct fixtures.

4. The railcar according to claim 3 , wherein:

the air conditioning duct is arranged in an internal space,

the internal space is formed at a carbody,

the air conditioning duct includes a plurality of duct bodies each formed in a tubular shape by the duct wall,

the duct bodies are coupled to one another in a longitudinal direction, and

the plurality of duct fixtures correspond to the plurality of duct bodies in one-to-one correspondence.

5. The railcar according to claim 4 , wherein each of the duct bodies has a size of 700 mm to 1,200 mm in the longitudinal direction.

6. The car air-conditioning duct according to claim 1 , wherein:

each of the engaging portions is engaged with an outer bottom surface of a bottom wall of the duct wall, outer surfaces of left and right side walls of the duct wall, and an outer upper surface of an upper wall of the duct wall;

the first part is engaged with at least the outer bottom surface of the bottom wall of the duct wall and the outer surfaces of the left and right side walls of the duct wall; and

the second part is engaged with at least the outer upper surface of the upper wall of the duct wall.

7. The railcar according to claim 3 , wherein:

each of the engaging portions is engaged with an outer bottom surface of a bottom wall of the duct wall, outer surfaces of left and right side walls of the duct wall, and an outer upper surface of an upper wall of the duct wall;

the first part is engaged with at least the outer bottom surface of the bottom wall of the duct wall and the outer surfaces of the left and right side walls of the duct wall; and

the second part is engaged with at least the outer upper surface of the upper wall of the duct wall.

8. A car air-conditioning duct configured to guide air to a suction side of an air conditioner mounted on a car or guide the air flowing from a blow-off side of the air conditioner mounted on the car, the car air-conditioning duct comprising:

a duct wall having a tubular shape,

a plurality of duct fixtures, the duct wall being attached to the car by the plurality of duct fixtures,

the duct wall forming a duct outer surface and a duct inner surface,

the duct wall being made of a composite foamed resin material containing polystyrene resin and polyolefin resin,

a content ratio of the polystyrene resin and a content ratio of the polyolefin resin each having a gradient in a thickness direction of the duct wall,

the content ratio of the polyolefin resin being higher than the content ratio of the polystyrene resin at the duct outer surface and the duct inner surface,

the duct wall having a rectangular cross section in which two face plate members are joined to each other at end edges thereof, the two face plate members having respective L-shaped cross sections arranged point symmetrically, being made of the composite foamed resin material,

the duct wall having a rectangular cross section in which two face plate members are joined to each other at end edges thereof, the two face plate members being arranged point symmetrically, being made of the composite foamed resin material, each having an L-shaped cross section,

each of the plurality of duct fixtures comprising a frame-shaped engaging portion engaged with the duct wall from outside the duct and coupling portions projecting from the engaging portion toward opposite sides in a car width direction.