Breathing assistance apparatus having floating function

1. A breathing assistance apparatus comprising:

a main body unit having a rearwall, a frontwall, a connecting wall connected between said rearwall and said frontwall to define a chamber thereamong, said rearwall having an insert hole in fluid communication with said chamber, said frontwall having a coupling hole in fluid communication with said chamber, said connecting wall having a rearwall-connecting portion connected to said rearwall, and a frontwall-connecting portion connected between said frontwall and said rearwall-connecting portion, said frontwall-connecting portion having a thickness smaller than that of said rearwall-connecting portion so as to allow for floating movement of said frontwall relative to said rearwall;

a head strap unit connected to said main body unit;

a nasal prong unit including a main plate inserted into said main body unit and aligned with said insert hole, and two nasal prongs disposed on said main plate; and

an intake unit mounted to said main body unit and extending into said coupling hole in said main body unit.

2. The breathing assistance apparatus as claimed in claim 1 , wherein said frontwall-connecting portion is formed with at least one rearwardly extending annular projection and at least one forwardly opening annular groove aligned with said annular projection in a front-to-rear direction.

3. The breathing assistance apparatus as claimed in claim 2 , wherein said frontwall-connecting portion is U-shaped in cross-section.

4. The breathing assistance apparatus as claimed in claim 1 , wherein said rearwall of said main body unit further has a first insert groove disposed behind said insert hole and having a width reducing rearwardly, said main plate of said nasal prong unit being confined within said first insert groove.

5. The breathing assistance apparatus as claimed in claim 4 , wherein said frontwall of said main body unit further has an annular inner surface defining said coupling hole and formed with an annular second insert groove, said intake unit including a tube-sleeving member inserted into said coupling hole, and an intake tube having an end permitting said tube-sleeving member to be sleeved fixedly thereon, said tube-sleeving member including a tubular body and an annular flange extending radially and outwardly from said tubular body and engaging rotatably said second insert groove.

6. The breathing assistance apparatus as claimed in claim 1 , wherein said main body unit is made of silicone gel, and further has two side straps connected to said rearwall, said head strap unit having a first head strap and a second head strap, each of which is connected between said side straps.