Hollow metal part of stator of rotating electrical machine, rotating electrical machine, and manufacturing process of hollow metal part

1. A hollow metal part of a stator of a rotating electrical machine that is used as a pipe component for a refrigerant flow path of the rotating electrical machine adapted to cool a stator coil with a refrigerant,

wherein the rotating electrical machine includes a connection arm and an insulating hose at a stator coil end portion of the stator coil, the connection arm is coupled to the stator coil, the insulating hose being coupled to the stator coil and the connection arm through a first hollow metal part in order to supply the refrigerant to the stator coil and the connection arm; and

wherein the first hollow metal part includes a bend, a first end coupled to one end of the bend, and a second end coupled to the other end of the bend,

wherein at least a part of the bend is formed of stainless steel,

wherein the first end and the second end are formed of oxygen-free copper, and

wherein the first hollow metal part is formed integrally by joining a portion formed of stainless steel at the bent portion and portions of the first end and the second end formed of oxygen free copper by HIP diffusion bonding.

2. The hollow metal part according to claim 1 , wherein the first hollow metal part includes an elbow body formed of stainless steel, a sleeve made of oxygen-free copper and coupled to one end of the elbow body, and a cup made of oxygen-free copper and coupled to the other end of the elbow body.

3. The hollow metal part according to claim 1 , wherein the first hollow metal part includes an inner periphery formed of stainless steel and an outer periphery made of oxygen-free copper to cover the outer circumference of the inner periphery.

4. The hollow metal part according to claim 1 ,

wherein the inside of the bend is formed of stainless steel, and the other portion is made of oxygen-free copper; and

wherein the opposing ends of the hollow metal part are continuously joined by the oxygen-free copper.

5. The hollow metal part according to claim 1 , further comprising a second hollow metal part that couples the stator coil to the connection arm and is bent at substantially right angles,

wherein the inside of the bend of the second hollow metal part is formed of stainless steel and the other portion is made of oxygen-free copper.

6. The hollow metal part according to claim 5 , further comprising a third hollow metal part that couples the stator coil to the second hollow metal part,

wherein the third hollow metal part includes:

an inner periphery formed of stainless steel; and

an outer periphery made of oxygen-free copper to cover the outer circumference of the inner periphery.

7. The hollow metal part according to claim 6 , wherein the third hollow metal part allows a connection target member to be inserted into the opposing ends of the third hollow metal part and is braze-joined to the connection target member.

8. The hollow metal part according to claim 5 , further comprising a third hollow metal part that couples the stator coil to the second hollow metal part,

wherein the third hollow metal part includes:

an inner periphery made of oxygen-free copper; and

an outer periphery formed of stainless steel to cover the outer circumference of the inner periphery; and

wherein the third hollow metal part allows a nipple, that is, a connection target member, to be inserted into the opposing ends of the third hollow metal part and is braze-joined to the connection target member.

9. A rotating electrical machine wherein a stator coil is formed with a hollow strand and liquid flows into the hollow strand to cool the stator coil and a connection arm, wherein the hollow metal part of the stator of the rotating electrical machine according to claim 1 is used as a flow path of the liquid.