Marine propulsion – Means for accomodating or moving engine fluids – Means for handling exhaust gas
Reexamination Certificate
1998-07-16
2001-06-26
Swinehart, Ed (Department: 3612)
Marine propulsion
Means for accomodating or moving engine fluids
Means for handling exhaust gas
C440S012610
Reexamination Certificate
active
06250982
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an outboard motor and more particularly to an exhaust arrangement for outboard motors.
As is well known, the design of the exhaust system for an outboard motor is an area that presents considerable problems. The reason for this is that the space available for treating and silencing the exhaust gases before discharge to the atmosphere is quite small. For that reason, it has been the practice to discharge the exhaust gases under most running conditions through an underwater exhaust gas discharge. Thus, the body of water in which the watercraft is operating may be utilized as a silencing medium.
In addition to this, the problem of discharging cooling water from the engine when the engine is of the water-cooled type, as is typical with most outboard motors. In an outboard motor, the engine cooling system relies on water from the body of water in which the watercraft is operating. This water is circulated through the engine and then returned back to the body of water in which the watercraft is operated. In this way, the body of water actually acts as a heat exchanger for the engine cooling which provides significant improvement.
It has been the practice to utilize an arrangement wherein the cooling water is returned along with the exhaust gases to the body of water. If this is done in a proper way, the water that has been drawn from within the body of water in which the watercraft is operating can also be utilized to cool the exhaust gases and provide some silencing.
However, since most outboard motors use two-cycle engines, there are some particular dangers in doing this. With two-cycle engines, there is frequently a negative pulse in the exhaust system during a normal operating cycle. Thus, if the cooling water is discharged in proximity to the exhaust system, it may actually be drawn into the combustion chamber during this negative pulse condition. Obviously, this is not desirable.
It is, therefore, a principal object of this invention to provide an improved exhaust system for an outboard motor.
It is a further object of this invention to provide an exhaust system for an outboard motor wherein the coolant for the engine can also be employed to cool the exhaust system.
It is a further object of the invention to provide an exhaust system cooling arrangement for an outboard motor as described, wherein the cooling water is returned in such a way that it will not come into direct contact with the exhaust gases and thus cannot be drawn back into the engine.
Frequently, the drive shaft housing of the outboard motor is employed in some manner as an expansion chamber. This expansion chamber cooperates with an exhaust pipe that delivers the exhaust gases from the engine into the expansion chamber, and which functions to assist in the silencing of the exhaust gases before they are discharged into the water. Frequently, the cooling water from the engine is also discharged into this expansion chamber and thus this gives rise to the possibility of water injection through the exhaust system, as before referred to.
It is a further object of this invention to provide an improved outboard motor exhaust system employing an expansion chamber in the drive shaft housing and in which the exhaust gases and water can be mixed in such a way that the water is not directed toward the exhaust pipe.
SUMMARY OF THE INVENTION
This invention is adapted to be embodied in an outboard motor comprised of a power head and a drive shaft housing and lower unit depending from the power head. The power head contains a powering internal combustion engine and a surrounding protective cowling. A propulsion device is contained within the lower unit for propelling an associated watercraft through a body of water in which it is operating. A transmission system transmits drive from the engine to this propulsion device. An expansion chamber is formed in the drive shaft housing and an exhaust pipe depends from the engine exhaust system into this expansion chamber for deliver of exhaust gases to the expansion chamber. The expansion chamber is defined by an outer peripheral wall. A cooling jacket is provided along a side of the exhaust pipe and receives coolant for cooling the exhaust pipe. The coolant water from this cooling jacket is returned to the body of water in which the watercraft is operating by a discharge passage from the cooling jacket which is directed toward the wall of the expansion chamber and away from the exhaust pipe.
REFERENCES:
patent: 3052087 (1962-09-01), Kiekhaefer
patent: 4983135 (1991-01-01), Boda et al.
patent: 5232387 (1993-08-01), Sumigawa
Knobbe Martens Olson & Bear LLP
Sanshin Kogyo Kabushiki Kaisha
Swinehart Ed
LandOfFree
Exhaust arrangement for outboard motor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Exhaust arrangement for outboard motor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exhaust arrangement for outboard motor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513808