Abstract: An air filter is substantially made up of a filter element having a pleated filtering portion and a collar portion that extends on an outer periphery of the filtering portion and that has a sealing function, the filtering portion and the collar portion being integrally formed from the same material, and a cap and a case each of which has a flange for clamping the collar portion of the filter element. One of the flange of the cap and the flange of the case has a protruded portion that has an inclined portion. The collar portion of the filter element has a recess portion that contacts the inclined portion of the protruded portion and is guided by the inclined portion and fits to the protruded portion at a predetermined position so as to become set in position.

Abstract: A muffler including an offshoot path, one end of which is connected to a middle of a ventilation path so as to diverge from the ventilation path, and another end of which is closed. One portion of the offshoot path and another portion thereof are communicated through a communicating portion. Accordingly, sound waves entering the offshoot path are propagated in a direction of a closed portion, and are also propagated via the communicating portion from the one portion to the other portion.