Pipe joint structure

1. A pipe joint structure comprising:

a connector having opposed first and second axial end faces;

a through hole that extends in the connector from the second axial end face of the connector toward the first axial end face of the connector;

a recess that is recessed in the first axial end face of the connector and extends outward from an inner peripheral surface of the through hole in a radial direction of the through hole; and

at least one holding projection that extends outward from the second axial end face of the connector; and

a pipe that is received through the through hole of the connector, wherein:

the pipe includes a protrusion, which extends along an outer peripheral surface of the pipe and which protrudes radially outward from the outer peripheral surface of the pipe;

the protrusion of the pipe is received in the recess of the connector; and

the at least one holding projection of the connector is bent and is thus urged against the outer peripheral surface of the pipe at a position spaced from the through hole to hold the pipe.

2. The pipe joint structure according to claim 1 , wherein:

the through hole of the connector has a radial opening, which opens radially outward to an exterior of the connector; and

the radial opening of the through hole of the connector axially extends along an entire axial extent of the through hole and thus axially extends through the recess to enable insertion of the pipe into the through hole in the radial direction of the through hole.

3. The pipe joint structure according to claim 1 , wherein:

the protrusion of the pipe extends all around the pipe near an end of the pipe; and

each of the at least one holding projection of the connector extends generally in an axial direction of the through hole and is bent inward in the radial direction of the through hole, so that each of the at least one holding projection is angled relative to the axial direction of the through hole.

4. The pipe joint structure according to claim 3 , wherein the protrusion of the pipe is press fitted into the recess of the connector.

5. The pipe joint structure according to claim 3 , wherein the at least one holding projection of the connector includes a plurality of holding projections, which are arranged one after another in a circumferential direction of the through hole.

6. The pipe joint structure according to claim 3 , wherein:

the recess of the connector has a non-circular cross section;

an inner peripheral surface of the recess of the connector includes a radially close section and a radially remote section, wherein the radially close section is radially closer to an inner peripheral surface of the through hole of the connector in comparison to the radially remote section; and

an outer diameter of the protrusion of the pipe is larger than a diameter of an imaginary inscribed circle, which inscribes the inner peripheral surface of the recess of the connector.

7. The pipe joint structure according to claim 1 , wherein:

the pipe is made of an aluminum alloy; and

the connector is made of an aluminum alloy, which has a hardness greater than that of the aluminum alloy of the pipe.

8. The pipe joint structure according to claim 1 , wherein the pipe is one of a plurality of pipes, which are held by the connector.

9. The pipe joint structure according to claim 1 , wherein:

the pipe joint structure is for a refrigeration cycle of an air conditioning system; and

the pipe is a refrigerant pipe for conducting refrigerant.