Vibration floating washer assembly and method of attaching the same to heat insulating plate

A method of attaching a vibration floating washer with a sleeve to a heat insulating plate including an attaching-bolt insertion hole, said vibration floating washer being attached with a metallic damping element placed therebetween, said vibration floating washer including a male washer and a female washer, said male washer and said female washer respectively including a male sleeve and a female sleeve, at least one of said male sleeve and said female sleeve including a fitting portion provided thereon, said method comprising:

• disposing a cushioning element on the inside and the peripheral edge portion of the attaching-bolt insertion hole;
• inserting said male sleeve of said male washer and said female sleeve of said female washer respectively into the bolt insertion hole from both sides of the heat insulating plate;
• and
• fitting and fixing said male washer and said female washers to each other with said fitting portion provided on at least one of said male sleeve and said female sleeve so that said heat insulating plate is maintained in a state of noncontact with both said male washer and said female washer, wherein said male sleeve includes holes on its surface, and said fitting portion is a discontinuous projecting portion and configured to have circular protrusions on a periphery of each hole thereon.