JPH05306632

PURPOSE:To reduce an air volume in a space part so as to reduce resonance vibration for preventing the peak of noise by forming the space part with respective outside and inside covers for enclosing a timing belt, and also constituting the space part to be capable of being reduced in its volume. CONSTITUTION:An engine 2 is provided with a timing belt 16 for transmitting driving force from a crank shaft 8 to a cam shaft 10. The timing belt 16 is enclosed with a timing belt cover 18 consisting of an outside cover 20 and an inside cover 22. In this case, an space part 24 is formed inside by means of the outside cover 20 and the inside cover 22. A space reducing means 28 for reducing the space part 24 is arranged in order to reduce noise of the timing belt 16. The space reducing means 28 is formed by a box shaped member 30 arranged between a crank shaft pulley 12 and a cam shaft pulley 14 for example, inside the space part 24. It is thus possible to reduce resonance vibration by reducing the air volume in the space part 24.