We claim:
1. A multipipe heat exchanger used for extracorporeal circulation of blood, comprising:
a heat exchanger case (70);
a bottom member (90B) attached to one end (70a) of said heat exchanger case (70); and
a plurality of heat transfer pipes (8) loaded in inside of said heat exchanger case (70), in which said blood flows from one end (8a) through said bottom member (90B), said bottom member (90B) having an annular wall (93) fitted in a fluid-tight manner to said one end (70a) of said heat exchanger case (70),
a bottom surface (96) opposed to said one end (8a) of said heat transfer pipe (8) and closing in a fluid-tight manner, an end portion opposite to a side of said annular wall (93) fitted to said heat exchanger case (70), and
a blood inlet port (98) formed like a pipe, having an inside (98c) communicating with a space (S) surrounded by said one end (70a) of said heat exchanger case (70), said annular wall (93), and said bottom surface (96), and extending in a direction of normal (91) to an outer circumferential surface (93d) of said annular wall (93),
said bottom surface (96) including a groove portion (96c) extending along said direction of normal (91) and a raised bottom portion (96a, 96b) provided on each of opposing end sides of said groove portion (96c), and
said raised bottom portion (96a, 96b) being inclined such that a distance (H2) between said raised bottom portion (96a, 96b) on a side where said blood inlet port (98) is provided and said one end (8a) of said heat transfer pipe (8) is smaller than a distance (H1) between said raised bottom portion (96a, 96b) opposite to the side where said blood inlet port (98) is provided and said one end (8a) of said heat transfer pipe (8).
2. The heat exchanger as claimed in claim 1, wherein
said bottom member (90C) further has a rib (96R, 96L) provided on said bottom surface (96), to stand at a position not including a projection region (96T) obtained by projecting said inside (98c) of said blood inlet port (98) in said direction of normal (91) and to bend along said annular wall (93).
3. The heat exchanger as claimed in claim 1, wherein
said bottom member (90A) further has a protrusion (95) disposed such that its tip end portion (95a) extends toward said blood inlet port (98) and said tip end portion (95a) stands on said bottom surface (96), in a portion of an inner circumferential surface (93c) of the annular wall (93) opposed to said blood inlet port (98).

4. A heat-exchanger-integrated oxygenator, comprising:
the heat exchanger as claimed in claim 1;
heat exchange medium supply means (74, 76) for supplying a prescribed heat exchange medium to an outer surface of said heat transfer pipe (8);
gas exchange means (22, 24, 30) communicating with the other end (70b) of said heat exchanger case (70), through which said blood that flowed out of the other end (8b) of said heat transfer pipe (8) flows; and
a blood outlet port (28) communicating with said gas exchange means (22, 24, 30) and discharging said blood that flowed through said gas exchange means (22, 24, 30).
5. A heat-exchanger-integrated oxygenator, comprising:
the heat exchanger as claimed in claim 1;
a cylindrical core (40) having a diffusion portion (48) on the other end (40b) side, into which said heat exchanger is fitted from a one end (40a) side, the diffusion portion being disposed to oppose to the other end (70b) side of said heat exchanger and deflecting outward in a direction of cylinder diameter, flow of blood that flowed out of said the other end (70b) side of said heat exchanger;
a bundle (30) formed of a hollow fiber membrane and surrounding an outer surface (41) of said cylindrical core (40), in which said blood that flowed out through an outlet portion (47) of said diffusion portion (48) flows; and
a blood outlet port (28) communicating with said bundle (30) and discharging said blood that flowed in said bundle (30),
said outer surface on said the other end (40b) side of said cylindrical core (40) being subjected to round chamfering around an entire circumference.
6. A heat-exchanger-integrated oxygenator, comprising:
the heat exchanger as claimed in claim 1;
a cylindrical core (40) having a diffusion portion (48) on the other end (40b) side, into which said heat exchanger is fitted from a one end (40a) side, the diffusion portion being disposed to oppose to the other end (70b) side of said heat exchanger and deflecting outward in a direction of cylinder diameter, flow of blood that flowed out of said the other end (70b) side of said heat exchanger;

a bundle (30) formed of a hollow fiber membrane and surrounding an outer surface (41) of said cylindrical core (40), in which said blood that flowed out through an outlet portion (47) of said diffusion portion (48) flows; and
a blood outlet port (28) communicating with said bundle (30) and discharging said blood that flowed in said bundle (30),
on said outer surface (41) on said the other end (40b) side of said cylindrical core (40), a plurality of ribs (44) protruding outward in a direction of cylinder diameter and extending by a length (44H) not reaching said one end (40a) of said cylindrical core (40) from said the other end (40b) side of said cylindrical core (40) being provided,
and
some of said blood that flowed out through said outlet portion (47) of said diffusion portion (48) flowing into each gap (S42) formed between said bundle (30) and said outer surface (41) of said cylindrical core (40), owing to said plurality of ribs (44).
7. The heat-exchanger-integrated oxygenator as claimed in claim 5, wherein said heat exchanger further has heat exchange medium supply means (74, 76) for supplying a prescribed heat exchange medium to an outer surface of said heat transfer pipe (8).