We claim the ornamental design for a thermal expansion device, as shown and described.
FIG. 1 is a perspective view taken from the top and one side of the design;
FIG. 2 is a first side elevational view of the design shown in FIG. 1;
FIG. 3 is a second side elevational view of the design shown in FIG. 1;
FIG. 4 is a front elevational view of the design shown in FIG. 1;
FIG. 5 is a rear elevational view of the design shown in FIG. 1;
FIG. 6 is a top elevational view of the design shown in FIG. 1;
FIG. 7 is a bottom elevational view of the design shown in FIG. 1; and,
FIG. 8 is a first side elevational view of the thermal expansion device in an installed position with the environment shown in stippled lines and the tensioning bar removed.
The broken lines shown in the drawings are for the purpose of illustrating environment and form no part of the claim.