The ornamental design for a palateexpander, as shown and described.
FIG. 1 is an elevated top isometric view of a palate expander showing the new design;
FIG. 2 is a bottom isometric view of the palate expander as shown in FIG. 1;
FIG. 3 is a front view of the palate expander as shown in FIG. 1;
FIG. 4 is a rear view of the palate expander shown in FIG. 1;
FIG. 5 is a left side view of the palate expander as shown in FIG. 1;
FIG. 6 is a right side view of the palate expander as shown in FIG. 1;
FIG. 7 is a top plan view of the palate expander as shown in FIG. 1; and,
FIG. 8 is a bottom plan view of the palate expander as shown in FIG. 1.
The broken lines shown in the figures are included for the purpose of illustrating portions of the palate expander and form no part of the claimed design.