Abstract: Method and apparatus for controlling emissions, particularly of unburnt hydrocarbons, from a two stroke engine. The engine has direct in-cylinder fuel injection and has in the air inlet port and the exhaust port respective devices to control the flow therethrough. The devices are each independently controlled in relation to engine load demand and engine speed to regulate the mass of exhaust gases retained in the combustion chamber. The exhaust flow control device perferably also alters the timing of opening and closing of the exhaust port.

Abstract: Disclosed herein is an exhaust control system of an internal combustion engine. The exhaust control system comprises an electrically controlled valve installed in one of two tail pipes of a muffler; an engine speed sensor; an exhaust gas temperature sensor; a first control circuit for causing the valve to assume selectively a pipe closing position when the engine speed is lower than a reference level, and a pipe opening position when the engine speed is equal to or higher than the reference level; and a second control circuit for varying the reference level in accordance with the temperature of the exhaust gas.

Abstract: In an automotive vehicle installed with a V-6 engine, engine revolution speed and engine load are detected and a selector valve provided in a silencer is normally closed but it is opened when the engine revolution speed exceeds a predetermined engine revolution speed value when the 3rd order component of exhaust sound coincides with a longitudinal resonance frequency within a vehicle cabin when the vehicle is at acceleration. The selector valve which is normally closed is opened when the engine revolution speed exceeds a second predetermined engine revolution speed value when the 1.5th order component of the exhaust sound coincides with the longitudinal resonance frequency.

Abstract: A number of embodiments of silencing devices for marine propulsion units using acoustical lenses that are positioned across either the air inlet device, the air exhaust device or both. The acoustical lenses direct the sound waves in such a way so as to effect silencing while, at the same time, ensuring that water will not enter the engine combustion chambers. The invention is shown in conjunction with both outboard motors and inboard mounted engines.

Abstract: An exhaust silencer for a car includes a housing, a partitioning diaphragm plate, a conduction pipe for conducting therethrough an exhaust gas from the car engine, an exhaust pipe exhausting thereout the exhaust gas to the atmosphere, an exhaust conduit capable of exhausting therethrough the exhaust gas, a valve mounted in the conduit, and a controlling device responsive to the rpm of the car engine for enabling the valve to/not to block up the conduit so that the exhaust gas can be exhausted to the atmosphere in a quicker manner, if desired.

Abstract: Several embodiments of motorcycle exhaust systems having forward and rearward exhaust pipes at least one of which extends transversely in a transversely extending expansion chamber for improving high speed performance. In addition, a variety of control valves are incorporated for varying the reflective area of the exhaust pipe ends so as to improve low speed and mid-range performance.

Abstract: A straight through type muffler for generating an exhaust flow from an internal combustion engine includes a closed expansion chamber in communication with the straight through passage of the muffler. A minority of the gases passing through the straight through passage will be accumulated in the expansion chamber and will be returned to the straight through passage when the pressure of the gases passing through the straight through passage is reduced, thereby minimizing the back pressure from the muffler.

Abstract: A control system for controlling a DC control motor which controls an internal combustion engine to follow-up a target value varying continuously depending on the operation condition of the engine, the current flowing through the DC control motor being controlled through pulse width modulation.

Abstract: A control system for controlling an actuator which controls operation of an internal combustion engine in compliance with a target value varying continuously depending on the operation condition of the engine.

Abstract: A motorcycle embodying an improved exhaust device comprised of an expansion chamber that extends in part beneath the engine and transmission and which extends at least partially vertically upwardly adjacent to the transmission. A U-shaped inlet pipe delivers exhaust gases from the engine to the expansion chamber and a further expansion chamber is provided for discharging the exhaust gases to the atmosphere. Stainless steel, single thickness exhaust pipes deliver the exhaust gases from the engine exhaust ports to the expansion chamber.

Abstract: An exhaust plenum chamber for a supercharged engine having a variable volume. A mechanical spring is arranged to an exhaust plenum chamber to increase the spring action of the plenum chamber volume. In this connection, the plenum chamber interior is divided into a flow chamber and a dead volume. The efficiency especially of relatively small plenum chambers in internal combustion engines with a small number of cylinders and/or slight supercharging is improved.

Abstract: An afterburner combustion chamber receives internal combustion engine exhaust gases and the ignition of the gases in the main engine combustion chamber and the afterburner combustion chamber are synchronized with one another. Auxiliary air is supplied to an afterburn area including the combustion chamber. Exahust gases are expelled onto a reflection wall upstream from the afterburner combustion chamber. The waste gases are ignited by spark ignition means. A volume expansion chamber leads from the ignition area and communicates with a convergent flow channel and a draft section for forming a gas column tuned by the cross section and length of the draft section for optimum filling of the engine combustion chamber. Ambient air is introduced into the draft section for stabilizing the thermal accumulation within the afterburner apparatus.

Abstract: An exhaust control system for use in an internal combustion engine for controlling the flow of exhaust gases discharged from the engine to the atmosphere. The apparatus determines a first condition representing the engine speed being higher than a predetermined value, a second condition representing the transmission being not in neutral, and a third condition representing the throttle valve being not at or near its closed position. A control circuit generates a command signal only upon simultaneous occurrence of the first, second and third conditions. The apparatus includes a device responsive to the command signal from the control circuit for increasing the effective area of the exhaust passage.

Abstract: This invention is directed to a novel camshaft for engine timing. The cam positions of the camshaft include secondary lobes in conjunction with normal primary lobes. The secondary lobes are positioned so that they precede their associated primary lobe during camshaft rotation. The secondary lobes cause an associated valve to open slightly and close completely prior to the normally expected valve opening caused by the primary lobe. This slight opening and closing creates a shock wave that aids the atomizing air and fuel mixing in the intake system prior to normal intake valve opening and enhances the scavenging of combustion gases during the exhaust cycle.

Abstract: Two embodiments of outboard motors incorporating improved silencing systems for the exhaust gases of the powering engine. In each embodiment, a Helmholtz resonator is provided by a resonance chamber formed at least in part by a spacer plate that is interposed between the power head and drive shaft housing of the engine and which communicates with an expansion chamber of the engine through a tuning neck. In each embodiment, the effective volume of the resonance chamber of the Helmholtz resonator is varied in response to engine speed by delivering coolant to it from the engine cooling jacket and discharging the coolant at a restricted rate.

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: A resonator for internal combustion engines having intake and exhaust pipes connected with a cylinder of said internal combustion engines comprising resonator means for absorbing resonant noises generated in said engines, a plurality of tubular connecting members disposed between said resonator means and one of said pipes for forming a continuous passage from said one pipe to said resonator means, and switch means connected with said tubular connecting means for changing said tubular connecting members in accordance with operational conditions of said engines to absorb said noises from said engines.

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: A resonator for internal combustion engines, having an enclosed chamber of predetermined volumn connected to an intake duct by a tubular connecting member which is composed of an external member and an internal member. The internal member is disposed within the external member and moved by an actuator which is controlled by an electrical signal corresponding to a resonant frequency calculated by a computer in synchronism with engine rotational speeds. The resonator thereby functions to absorb resonant noises from the engines by appropriately changing the length and/or cross-sectional area of the tubular connecting member.

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: 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: The invention includes an outboard motor comprising a power head having an exhaust gas port, a drive shaft housing extending downwardly from the power head and including an exhaust gas discharge outlet adjacent its lower end, and a continuous folded passage housed in the drive shaft housing. The folded passage includes a first passage portion having an upper end communicating with the exhaust gas port a second portion extending upwardly from the lower end of the first portion and having an upper end, and a third portion communicating with the upper end of the second portion. The folded passage functions to return to the exhaust port as positive pressure pulses the pressure pulses emitted by the exhaust ports, the folded passage causing return of the pressure pulses in timed relation with respect to closing of the exhaust port to thereby facilitate precompression of the fuel mixture entering the cylinder.

Abstract: A high-efficiency combustion gas exhaust system for four-stroke internal combustion engines. This system uses two overlapping converging conical pipes to provide excellent scavenging at high piston speeds without the usual adverse effects at idle or moderate speeds. A generally conical converging first pipe is installed over the exhaust gas opening in the engine head. A second pipe with a generally converging conical introductory section is secured in an overlapping relationship to the first pipe. Certain size relationships among these components are important in obtaining optimum performance.

Abstract: An exhaust gas purification system for internal combustion engines comprising two exhaust gas passages which are substantially equal in length and each of which has a substantially constant cross-section. A thermal reactor communicates with the exhaust gas passages, and a collector is provided on the open ends of the exhaust gas passages. Since the ignition timing of every cylinder is different from each other, the mass of exhaust gases and the mass of secondary air are ejected from the exhaust passages in different phases. The collector is formed to collect and mix the mass of exhaust gases and the mass of secondary air which are ejected from both of the exhaust gas passages at a different time, and has an outlet for discharging the exhaust gases and the secondary air into the chamber of the thermal reactor with mixing thereof.

Abstract: An exhaust line including an exhaust pipe assembly, a reactor for oxidizing hydrocarbons and carbon monoxide, a main muffler and a mechanism for drawing secondary air from the atmosphere into the exhaust line upstream of the reactor based on the pulsation of the exhaust pressure, wherein a front tube of the exhaust pipe assembly for passing the exhaust gas from the engine to the reactor has a smaller cross-sectional area than a center tube connecting the reactor to the main muffler, so that the pulsation is of a great magnitude even at an engine speed where the pulsation is in an anti-resonance state.

Abstract: An internal combustion gasoline engine comprises a determined region which is so formed in an exhaust passage from an exhaust valve to a thermal reactor as to pass exhaust gases therethrough in their discharging order, a secondary air passage with a check valve means communicating with the exhaust port near the exhaust valve, and means for maintaining the temperature of exhaust gases over the trigger temperature of the thermal reactor. The exhaust passage has a volume equal to or more than the displacement of the engine and less than four times the displacement volume and has a cross-sectional area less than three times the opening area of the exhaust valve.

Abstract: A power control valve attachment is provided for assembly to a pre-existing exhaust system of a two cycle motorcycle type engine for effecting a back pressuring of the engine cylinder chambers during operation of the engine and includes an assembly of pressure plate and spring biasing means and means for mounting the assembly in the exhaust system duct at a minimum cross sectional area thereof for axial deflective movement under the pressure of the exhaust gases.

Abstract: A tuned exhaust gas relief system for marine propulsion systems, for example an outboard motor, includes a lower drive shaft housing coupled to a two stroke engine by a pair of intermediate stacked exhaust extension plates. The housing directs the exhaust gas downwardly to a through-the-hub exhaust propeller for exit therethrough. With the unit in reverse or idling, exhaust gases are trapped within the housing. A pair of tuned exhaust relief passageways may be formed by cavities in the mating faces of the two extension plates with a pair of inlet openings in the lower wall of the bottom plate. A baffle member may overlie the inlet openings. The passageways define constant cross-sectional area channels which terminate in exhaust openings in the rear wall of the drive shaft housing. A resonant cavity, which may be integrally formed by mating recesses in the opposed faces of the extension plates, is in close spaced relation to each idle exhaust passageway.

Abstract: Exhaust system for an internal combustion engine with wall means forming a wave tube having a substantially unimpeded flow passage with one end adapted to be placed in communication with the exhaust opening of the internal combustion engine. The wall means forming a wave tube is formed with a slot in relatively close proximity to the exhaust opening. Means is provided for collecting gases passing through the slot and for supplying the same to the intake of the internal combustion engine. Collecting means is provided for collecting the exhaust gases passing through the wave tube and for maintaining them at an elevated temperature before they are exhausted to the atmosphere.