Abstract: Disclosed are several embodiments of a turbo-charged two cycle internal combustion engines utilized in combination with an outboard motor are disclosed. In each embodiment, the exhaust system for the engine includes devices for insuring that sufficient backpressure is exerted at the exhaust port of one cylinder during the overlap period when its scavenge passages and exhaust ports are both open so as to preclude the discharge of fresh fuel/air mixture to the atmosphere without adversely affecting the turbo-charger performance. In some embodiments of the invention, a valve arrangement is controlled for controlling the proportion of the exhaust gases that flow across the turbo-charger so that at some running conditions, the turbo-charger receives all of the exhaust gases. In all embodiments, an expansion chamber device is incorporated in the drive shaft housing of the outboard motor and in some embodiments, the turbo-charger turbine inlet receives its gases from this expansion chamber.

Abstract: An exhaust control system for 2-cycle engines has a main exhaust passage, auxiliary exhaust passages arranged in parallel with the main exhaust passage, and an expansion chamber communicatable with the main exhaust passage. During low-speed operation of the engine, the auxiliary exhaust passages are shut-off while the expansion chamber is connected to the main exhaust passage, whereas, during high-speed operation of the engine, the auxiliary exhaust passages are opened and the expansion chamber is closed.

Abstract: An apparatus for controlling an exhaust system of an internal-combustion engine includes a resonance chamber having its terminating end closed and communicating with an intermediate portion of an exhaust passage of the engine, and a stop valve provided at the inlet of the resonance chamber for opening or closing the inlet in a predetermined operation region of the engine. The stop valve is actuated to effect its opening/closing operation in accordance with a predetermined operation region of the engine by means of a governor mechanism actuated in response to the rotation of a crankshaft of the engine. Through the opening/closing control effected by the stop valve, the natural frequency of the exhaust system is controlled in accordance with the operating conditions of the engine, thereby allowing the intake efficiency of the engine to be raised over a wide operation range, from low speed to high speed. Accordingly, a high output is maintained at all times.

Abstract: Exhaust apparatus for a vehicle engine, having a connecting line which connects a sub-chamber to an engine exhaust line and which is provided with an opening and closing valve connected to a power source responsive to the number of engine revolutions per minute, i.e. speed, and causing the valve to open and close in dependency of the number of such revolutions. The power source is connected to the shaft mounting the valve by elements inserted through the outer walls of an engine cylinder, the exhaust line and a crank case.

Abstract: An exhaust system of a two-cycle engine mounted on a motorcycle is provided with a subchamber branching off from the exhaust pipe. The subchamber is disposed by utilizing a so called dead space in the frame of the motorcycle, particularly in a position in front of the engine and between a pair of cradle pipes of a body frame on which the engine is mounted. With this arrangement, it becomes possible to layout the position of the subchamber without altering the configuration of the body frame, and there is further advantage that the subchamber is well protected by the structural members.

Abstract: An improved two cycle engine is disclosed which includes a subchamber which is in communication with the exhaust port with a cylindrical valve rotatably disposed therebetween. A reed valve unit is turnably supported in the inlet port to open and close the latter. The cylindrical valve is operatively connected to the reed valve unit by way of a linkage mechanism. Either of the cylindrical valve and the reed valve unit is actuated by a servomotor and the other one is actuated by the linkage mechanism. The servomotor is controlled with the aid of a control circuit so as to allow the engine to be operated at a predetermined number of revolutions.

Abstract: An exhaust system control apparatus for the exhaust of an internal combustion engine which is particularly useful on two-cycle engines. The exhaust system includes a subsidiary chamber connected to the normal engine exhaust passage with a valve for opening and closing communication between the chamber and exhaust passage to change the pressure wave at the engine cylinder exhaust port to provide optimum performance at high and low speeds. The chamber valve is operated rapidly by a pneumatic actuator supplied with compressed air from one or more of the sources disclosed, namely, a belt driven or electric air compressor and piston and cylinder devices extending between or forming the suspension components of a two wheeled vehicle. A pneumatic valve is operated by engine speed sensing means to supply or release the pressurized air to the actuator at a predetermined engine speed.

Abstract: A compact expansion chamber for increasing the power of small internal combustion engines, particularly outboard engines for model boats. Its very compact, generally S-shaped configuration allows its center of gravity to be quite close to the engine to which it is attached, thus providing a very short moment arm. This allows model boats upon which it is installed to remain well balanced and level so that they are more maneuverable and quicker to respond to the radio control signals. The expansion chamber (10) comprises: a straight inlet pipe (12) having a flange (22), a diverging section (14) having a 150 degree bend, a straight tubular section (16), a converging section (18) having a 90 degree bend in the direction opposite to the bend in the diverging section, and an outlet pipe (20). A pressure tap fitting (24) connects to the fuel tank pressure line so as to improve fuel flow to the engine.

Abstract: Exhaust system control apparatus for internal combustion engine having an exhaust line and a branch line thereon, and an opening and closing valve on said branch line adapted to open when the engine operates at low speed and to close when the engine operates at high speed. The ratio between the cross-sectional areas of the branch line and the exhaust line is about 0.6 to 0.8.

Abstract: A four cylinder, two-cycle engine (10) has an exhaust system formed in a die-cast cylinder block. The exhaust system includes four legs (25) connected to the exhaust ports (23) of the cylinders (12). The upper two legs join together, as do the lower two legs to form two exhaust branches (26) connected by an exhaust trunk (27). An exhaust outlet passage (28) connected to the trunk (27) to provide an outlet for exhaust gases. The exhaust system is formed to lie in a plane on the exhaust side of the cylinder block (16).

Abstract: A three cylinder, two-cycle engine 10 has a tuned exhaust system formed in a die-cast cylinder block 14. The exhaust manifold is formed by a cavity on the exhaust side of the cylinder block 14 with an exhaust gas outlet passageway 30 formed in the head end of the block 14.

Abstract: An outboard engine has a casing, an internal combustion engine with a water cooling circuit and an exhaust pipe. The exhaust pipe discharges exhaust gases into an expansion chamber, and gases from the expansion chamber are discharged into the body of water in which the vessel propelled by the engine floats. The exhaust pipe projects into the expansion chamber and has pores (perforations) near its outlet end. Coolant water is discharged into the expansion chamber and mixes with the exhaust gases. Gas flow through the pores discourages reverse flow of water droplets through the exhaust pipe to the engine cylinders.

Abstract: In the present invention, a second expansion chamber which includes a second diffuser is provided in pneumatic connection with the prior art first expansion chamber of an exhaust system for a two-cycle engine. The second expansion chamber creates a second pressure drop or relative vacuum substantially adjacent the point of pneumatic connection between the first and second expansion chambers, which acts to draw-out the exhaust gases present at the rear-cone shaped portion of the first diffuser. The second pressure drop or relative vacuum created by the second expansion chamber of the present invention thus overcomes the deficiencies caused by the pressure increase produced by the rear-cone shaped portion of the first diffuser. Several embodiments of the present invention are disclosed.

Abstract: An exhaust device is provided comprising a first diverging portion extending into a cylindrical envelope into which is axially displaceably mounted a streamlined conically shaped member adapted to be moved in relationship to the engine rating.

Abstract: A two-stroke internal combustion engine having at least three cylinders includes an exhaust means with an exhaust cavity, an exhaust port at each cylinder and an exhaust port extension forming a chamber between the exhaust cavity and the exhaust port. Within the exhaust cavity exhaust pulse transmission means connect the port extension of an exhausting cylinder and the port extension of a charging cylinder with a pulse transmission path of a proper length to cause the exhaust pulse from an exhausting cylinder to arrive at the exhaust port of a charging cylinder prior to the complete closing of the exhaust port of the charging cylinder thereby forcing the air fuel mixture which escaped from the exhaust port of the charging cylinder and which is within the chamber thereof back into the charging cylinder prior to the closing of the exhaust port of the charging cylinder.

Abstract: A hollow, generally conical member is provided in a cylindrical portion of a muffler shell and has a surface cooperating with the shell to compress oncoming exhaust gases, the surface being of a special curved configuration calculated for reflecting impinging gas flow in a non-linear pattern which results in the development of pressure waves that arrive at an open exhaust port of the engine at the proper time for providing efficient scavenging and/or supercharging. The generally conical member also serves as an expansion chamber and, in one embodiment thereof, an elongate tube is provided for conveying gases axially thereinto while elongate perforations are provided in the rear end wall thereof for conveying gases therefrom. In a second embodiment thereof, a plurality of radial openings are provided for conveying gases thereinto while a tube extends axially through an end wall thereof for conveying gases therefrom.

Abstract: Connecting exhaust ducts of gradually widening cross section lead from the exhaust ports of a particular cylinder to a common manifold, being continued inside the manifold for a length greater than half of the diameter of the manifold and leaving an outflow cross section between the end of the connecting duct and the facing wall of the manifold equal to or slightly greater than the exit cross section of the connecting duct. Between junctions with the connecting ducts the manifold has sections of constricted cross section, providing baffling between the connecting ducts. The arrangement enables the kinetic energy of the outflow of exhaust gas to be more effectively utilized for sucking in the scavenging air.

Abstract: Exhaust means for internal combustion engines which comprises an exhaust pipe having one end connected with exhaust port of the engine, said exhaust pipe having an enlarged expansion chamber adjacent to the other end thereof, said exhaust pipe being closed at the other end and provided with an exhaust gas outlet port which is located at a position where the maximum value of noise producing pulsating pressure is relatively low, there being a first portion of substantially uniform cross-section connecting the engine to the enlarged expansion chamber.

Abstract: In an outboard motor having an engine located above the water level, a lower unit is provided extending downwardly from the engine and includes an exhaust gas tube within the lower unit with its lower end positioned below the water level. Laterally enclosing the exhaust gas tube is a liquid jacket and a heat insulating jacket is positioned between the exhaust gas tube and the liquid jacket for maintaining the temperature of the exhaust gases at a level such that an afterburning of any oil residue in the exhaust gases is achieved before the gases are discharged from the exhaust gas tube.