Personal watercraft and engine mounted in personal watercraft
View Patent ↗Disclosed is an engine of a personal watercraft capable of preventing water ingress into a penetrating hole for attaching an ignition plug. The engine comprises a cylinder head, a cylinder head cover provided over the cylinder head, an ignition plug attached to the cylinder head, a penetrating hole formed to extend from an upper surface of the cylinder head cover to a lower surface of the cylinder head, for accommodating and attaching the ignition plug inside thereof, a connecting member connected to an upper end of the ignition plug and located inside the penetrating hole, for connecting a power supply to the ignition plug that activates the ignition plug, a closing member for creating a seal between the connecting member and the penetrating hole, and an air hole formed to extend obliquely downward from the penetrating hole so as to communicate with an outside of the cylinder head.
1. An engine of a personal watercraft, comprising:
a cylinder head;
a cylinder head cover provided over the cylinder head;
an ignition plug attached to the cylinder head;
a penetrating hole formed to extend from an upper surface of the cylinder head cover to a lower surface of the cylinder head through the cylinder head cover and the cylinder head, for accommodating and attaching the ignition plug inside thereof, the penetrating hole including a step portion axially supporting the ignition plug, and a screw portion extending downwardly from the step portion to open in the lower surface of the cylinder head, for fixing the ignition plug;
a connecting member connected to an upper end of the ignition plug and located inside the penetrating hole, for connecting a power supply that activates the ignition plug to the ignition plug;
a closing member for creating a seal between the connecting member and the penetrating hole; and
an air hole formed to extend obliquely downward from a vicinity of the step portion so as to communicate with an outside of the cylinder head.
2. The engine of a personal watercraft according to claim 1 , wherein the connecting member is comprised of a stick-shaped member protruding from an upper end of the penetrating hole.
3. The engine of a personal watereraft according to claim 2 , wherein the connecting member contains an ignition coil inside thereof.
4. The engine of a personal watercraft according to claim 2 , wherein the penetrating hole is provided with an engagement protrusion on a periphery of an opening at an upper end of the penetrating hole, and the closing member is comprised of an upper inner peripheral portion in contact with a periphery of the connecting member and a lower inner peripheral portion fitted to the protrusion.
5. The engine of a personal watereraft according to claim 2 , wherein the closing member is provided between an outer surface of the connecting member and an inner surface of the penetrating hole.
6. The engine of a personal watercraft according to claim 5 , wherein the closing member is comprised of an O-ring.
7. A jet-propulsion personal watercraft equipped with an engine including a crankshaft extending along a longitudinal direction of a body of the watercraft and having a rear end portion for taking out an output from the engine, and an air-intake passage and an exhaust passage extending inside a cylinder head along a lateral direction of the body, the engine comprising:
a cylinder head cover provided over the cylinder head;
an ignition plug attached to the cylinder head;
a penetrating hole formed to extend from an upper surface of the cylinder head cover to a lower surface of the cylinder head through the cylinder head cover and the cylinder head, for accommodating and attaching the ignition plug inside thereof, the penetrating hole including a step portion axially supporting the ignition plug, and a screw portion extending downwardly from the step portion to open in the lower surface of the cylinder head, for fixing the ignition plug;
a connecting member connected to an upper end of the ignition plug and located inside the penetrating hole, for connecting a power supply to the ignition plug that activates the ignition plug;
a closing member for creating a seal between the connecting member and the penetrating hole; and
an air hole formed to extend obliquely downward from a vicinity of the step portion so as to communicate with an outside of the cylinder head.
8. The jet-propulsion personal watercraft according to claim 7 , wherein the air hole opens in an outer face of the cylinder head at a position lower than an opening of the air-intake passage or the exhaust passage.
9. The jet-propulsion personal watercraft according to claim 8 , wherein the air hole is located on a right-side portion of the engine as seen from behind when a propeller shaft rotates clockwise as seen from behind, or located on a left-side portion of the engine as seen from behind when the propeller shaft rotates counterclockwise as seen from behind.
10. The jet-propulsion personal watercraft according to claim 7 , wherein the air hole opens in an outer face of the cylinder head at a position lower than and forward of an opening of the air-intake passage or the exhaust passage.