Filter sub-assembly for an upper-stop assembly of a suspension strut of a motor vehicle, and associated assembly, suspension strut and assembly method

A filter sub-assembly for an upper-stop assembly of a suspension strut of a motor vehicle, the filter sub-assembly comprising:

• a filter block comprising an elastomer material, the filter block extending along a reference axis and having an interface for securing one end of a rod of a shock absorber of the suspension strut;
• a lower support of the filter block, having an annular central portion bearing against a lower face of the filter block and passed through axially by a passage for the end of the rod of the shock absorber, the lower support having an annular peripheral portion surrounding the annular central portion;
• and
• a cover of the filter block, comprising a central portion bearing against an upper face of the filter block, and a peripheral portion surrounding the central portion and bearing against the annular peripheral portion of the lower support,
• wherein the filter sub-assembly further comprises a locking washer, a first element from among the lower support and the cover being located axially between the locking washer and a second element from among the lower support or the cover, flaps and notches being formed on the locking washer and the second element, each of the fixing-flaps formed on a part from among the locking washer and the second element being associated with one of the notches formed on another part from among the locking washer and the second element, the locking washer being movable relative to the second element between:
• a relative approach position and a relative position of interpenetration by means of relative translational movement between the locking washer and the second element along the reference axis wherein, in the relative interpenetration position, each of the flaps penetrates into the associated notch,
• the relative interpenetration position and a relative assembly position by means of relative rotational movement between the locking washer and the second element about the reference axis wherein, in the relative assembly position, each of the flaps is housed in a circumferential extension of the associated notch and is axially retained therein bearing axially against a rim of the associated notch.