The ornamental design for an inflator, as shown and described.
FIG. 1 is a front perspective view of an inflator according to the present invention;
FIG. 2 is a left side view of the inflator of FIG. 1;
FIG. 3 is a right side view of the inflator of FIG. 1;
FIG. 4 is a top view of the inflator of FIG. 1;
FIG. 5 is a bottom view of the inflator of FIG. 1;
FIG. 6 is an elevated bottom view of the inflator of FIG. 1; and,
FIG. 7 is an elevated top view of the inflator of FIG. 1.
The broken lines in the figures merely illustrate the environment for the inflator of the present design and therefore form no part of the claimed design.