JP2007046528A - Water hammer prevention mechanism of outboard motor for racing boat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the bending of a piston, a connecting rod, a piston pin or the like and the generation of indentations on the track planes of the large end bearings of the connecting rod and a main bearing. <P>SOLUTION: A break-valve screwing hole 40a is formed in a position bordering a combustion chamber in a combustion dome 40 of a cylinder 12 of a water hammer prevention mechanism. Then a break-valve 50 is screwed to the break-valve screwing hole through the medium of an O ring, and a notch 50a is formed in a position bordering the combustion chamber. When a racing boat is capsized, water is drawn in from a carburetor, and the engine comes to a sudden stop, the valve screwed into the break-valve screwing hole is disconnected from the break-valve screwing hole by hydraulic pressure and the impact given to each part of the engine is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water hammer prevention mechanism for an outboard motor for a racing boat, and more specifically, a racing boat that is sailing at high speed rolls over and the propeller of the outboard motor comes to the surface of the water until then. When the load suddenly disappears, the engine speed increases, and when the engine is submerged, water is sucked from the carburetor, a water hammer is generated, the connecting rod, piston pin, etc. are bent, and the impact that damages the connecting rod large end bearing, etc. The invention relates to a water hammer prevention mechanism for an outboard motor for a race boat that reduces the force applied to each part of the engine as much as possible.

  Multiple race boats 100 (usually 6) sailing on the surface of the race race at a high speed of about 80 km / H on a straight course, lose balance when turning corners, and contact other boats or In some cases, it may be overturned by being beaten by a wave that is generated or by a natural wind.

  Motor boat race athletes are allowed to board only after passing the test after rigorous training for a certain period of time, and in the motor boat race of the day, sail with great care However, the rollover of the race boat 100 is unavoidable in some cases due to the reasons described above.

  Specifically, as shown in FIG. 4, when the racing boat 100 running at high speed rolls over, the propeller 104 of the outboard motor 102 comes to the surface of the water. When the engine of the race boat 100 and the outboard motor 102 (not shown) is submerged and the piston 14 enters the intake process, the intake carburetor (not shown) Water enters the engine through the valve 44.

  When the piston enters the compression process, the crankshaft 20 rotating at high speed has a large inertial force, but the piston 14 connected thereto receives a large resistance because water is an incompressible fluid. Stop suddenly.

  At that time, the connecting rod 16, the piston pin 18 and the like are bent by the impact, and indentations are generated on the bearing raceways of the connecting rod large end bearing 22, the upper main bearing 24, the middle main bearing 26 and the lower main bearing 28. It is necessary to remove the machine 102 and disassemble and inspect the engine for repair.

As a water hammer prevention mechanism for outboard motors that has been proposed in the past,
Japanese Patent Application Laid-Open No. 10-0119158 (valve automatic switch), JP-A-2001-182542 (excluding the drain of the engine air supply system), and the like.

  The first aspect of the present invention is a cylinder, a piston provided at one end of a connecting rod in the cylinder via a piston pin, a connecting rod large end bearing, an upper main bearing, and a middle main bearing at the other end of the connecting rod. And a lower main bearing and a crankshaft provided via an upper journal, a center journal and a tail journal, a combustion chamber formed by a combustion chamber dome at the head of the cylinder, and an upper portion of the combustion chamber A cylinder head water jacket provided, a water jacket plug provided in the cylinder head water jacket, and an intake valve, an exhaust valve and a spark plug hole provided in the combustion chamber. A screw formed on the combustion chamber dome. A water-hammer prevention mechanism of the race boat outboard motor, characterized in that screwing the break valve in the hole.

  According to a second aspect of the present invention, a combustion chamber formed in a cylinder head by a combustion chamber dome, an intake valve, an exhaust valve and a spark plug hole provided in the combustion chamber, and formed in the combustion chamber dome An outboard motor for a race boat, comprising: a break valve screwed hole, wherein a break valve having a notch formed in a portion facing the combustion chamber is screwed into the break valve screw hole. This is a water hammer prevention mechanism.

  (1) In the water hammer prevention mechanism for an outboard motor for a racing boat according to the present invention, the race boat rolls over and the outboard motor propeller comes out to the surface of the water, and the load that has been applied underwater until then suddenly increases. Even if the engine that has run out and the engine speed has increased rapidly is submerged, water is sucked from the carburetor, a water hammer is generated, and even if shock pressure is applied to the combustion chamber, stress is applied to the notch formed in the break valve. Concentrate, and there is a circumferential crack, the valve jumps into the cylinder water jacket in an instant, and the water in the cylinder escapes at once and weakens the impact force applied to the piston, piston, connecting rod, crankshaft This reduces the force applied to the connecting rod, prevents bending of the connecting rod and piston pin and the generation of indentations on the bearing raceway surface.

  (2) According to the water hammer preventing mechanism of an outboard motor for a racing boat according to the present invention, the break valve is screwed into the break valve screwing hole via the O-ring, so that the normal operation is performed. Sometimes the water in the cylinder head water jacket does not enter the combustion chamber at all.

  (3) According to the water hammer preventing mechanism for an outboard motor for a racing boat according to the present invention, the valve that has come out can be removed by loosening the water jacket plug and removing it from the water jacket plug hole.

  (4) According to the water hammer preventing mechanism of an outboard motor for a racing boat according to the present invention, the valve that has come off is removed by loosening the bolt from the combustion chamber side, and a new break valve is installed in the break valve screwing hole. It becomes possible to attach to.

A water hammer preventing mechanism for an outboard motor for a racing boat according to the present invention will be described with reference to an embodiment shown in the accompanying drawings.
As shown in FIGS. 1 to 3, in the water hammer preventing mechanism 10 for an outboard motor for a race boat, which is the first gist of the present invention, a piston pin 18 is connected to one end of a connecting rod 16, 16 in a cylinder 12, 12. , 18 to provide pistons 14 and 14, respectively.

  In the cylinders 12 and 12, the other end of the connecting rods 16 and 16 is connected to the connecting rod large end bearings 22 and 22, the upper main bearings 24 and 24, the middle main bearings 26 and 26, the lower main bearings 28 and 28, and the upper. The crankshaft 20 is provided via the journals 30, 30, the center journals 32, 32 and the tail journals 34, 34.

  Also in FIG. 1, outer races 24a, 24a are provided on the upper main bearings 24, 24, outer races 26a, 26a are provided on the middle main bearings 26, 26, and outer races are provided on the main bearings 28, 28. 28a and 28a are provided, respectively.

  Combustion chamber domes 40 are provided at the heads of the cylinders 12 and 12 to form combustion chambers 42 and 42, and intake valves 44 and 44 and exhaust valves (not shown) are respectively provided in the combustion chambers 42 and 42. And a spark plug hole 46, 46 is formed inside the combustion chamber dome 40 adjacent to the intake valve 44, 44, respectively.

  A cylinder head water jacket 54 is formed in the head of the combustion chamber dome 40, a through hole 58 is formed in the outer wall 56, and a water jacket plug 60 is provided in the through hole 58.

  2 and 3 showing an embodiment of a water hammer preventing mechanism for an outboard motor for a racing boat according to the second aspect of the present invention, a combustion chamber dome 40 is provided at the heads of the cylinders 12 and 12 for combustion. The combustion chambers 42 and 42 are formed, and intake valves 44 and 44 and exhaust valves (not shown) are provided in the combustion chambers 42 and 42, respectively, and the intake valves 44 and 44 are disposed inside the combustion chamber dome 40. Spark plug holes 46, 46 are formed adjacent to each other.

  The combustion chamber dome 40 is formed with screw holes 40a, 40a of break valves 50, 50 adjacent to the spark plug holes 46, 46, respectively, and is formed outside the combustion chamber dome 40. The jacket 54 is communicated with the combustion chambers 42, 42.

  Notches 50a and 50a are formed at locations where the break valves 50 and 50 face the combustion chambers 42 and 42, respectively.

  As described above, according to the water hammer preventing mechanism 10 for an outboard motor for a racing boat according to the second aspect of the present invention, when an impulsive pressure is applied to the combustion chambers 42, 42, the break valves 50, 50 Stress concentrates in the notches 50a and 50a provided in the cylinder, and circumferential cracks enter there, and the valves 50b and 50b jump out into the cylinder water jacket 54 in an instant. The water of the water is discharged at a stretch and the impact force applied to the piston 14 is weakened, and the force applied to the piston 14, the connecting rod 16, the crank shaft 20 and the like is reduced.

  Further, the connecting rod 16 and the piston pin 18 are bent, and indentations are generated on the raceway surfaces of the connecting rod large end bearing 22, the upper main bearing 24, the middle main bearing 2632 and the lower main bearing 28. To prevent.

These are the partially cutaway sectional views of the Example which shows the water hammer prevention mechanism of the outboard motor for race boats concerning this invention. FIG. 2 is a partial cross-sectional view with a water jacket plug as a front surface in the water hammer preventing mechanism of the outboard motor for a racing boat shown in FIG. 1. These are the expanded partial sectional views of the Example of FIG. These are schematic diagrams showing a state in which the race boat has overturned and the outboard motor has come out of the water.

Explanation of symbols

10 Water hammer prevention mechanism;
12 cylinders;
14 pistons;
16 connecting rods;
18 piston pin;
20 crankshaft;
22 connecting rod big end bearing;
24 upper main bearing;
24a outer race;
26 Central main bearing;
26a outer race;
28 Lower main bearing;
30 upper journal;
32 Center Journal;
34 Tail Journal;
40 Combustion chamber dome;
40a screw hole;
42 combustion chambers;
44 intake valves;
46 spark plug holes;
50 break valves;
50a notch;
52 O-ring;
54 cylinder head water jacket;
56 outer wall;
58 through-holes;
60 water jacket plug;
100 racing boats;
102 outboard motor;
104 Propeller.

Claims (2)

  A cylinder, a piston provided at one end of a connecting rod in the cylinder via a piston pin, a connecting rod large end bearing, an upper main bearing, a middle main bearing, a lower main bearing and an upper A crankshaft provided via a journal, a center journal and a tail journal, a combustion chamber formed by a combustion chamber dome at the head of the cylinder, and a cylinder headwater provided at the upper portion of the combustion chamber A jacket, a water jacket plug provided in the cylinder head water jacket, and an intake valve, an exhaust valve and a spark plug hole provided in the combustion chamber, are formed in the combustion chamber dome. Break bar in the screwed hole Water hammer prevention mechanism of the race boat outboard motor, characterized in that screwing. A combustion chamber formed in the cylinder head by a combustion chamber dome, an intake valve, an exhaust valve and a spark plug hole provided in the combustion chamber, and a break valve screwing hole formed in the combustion chamber dome The race boat according to claim 1, wherein a break valve having a notch formed at a location facing the combustion chamber is screwed into the break valve screw hole through an O-ring. Water hammer prevention mechanism for external machine.