Abstract: Injectors 2 are connected to a common rail 4 via respective dispensing conduits 3. A mixture of a liquid fuel fed from a liquid fuel tank 2 and an additional fluid fed from an additional fluid tank 9 is formed, and is fed to the common rail 4. The additional fluid contained in the mixture is turned to its supercritical state, and the mixture is injected from the injectors 2 to the engine. The inlets of the dispensing conduits 3 are positioned, with respect to the common rail 4, to open out into a liquid fuel layer which will be formed in the common rail 4 when a separation of the mixture occurs.

Abstract: Injectors 2 are connected to a common rail 4 via respective dispensing conduits 3. A mixture of a liquid fuel fed from a liquid fuel tank 2 and an additional fluid fed from an additional fluid tank 9 is formed, and is fed to the common rail 4. The additional fluid contained in the mixture is turned to its supercritical state, and the mixture is injected from the injectors 2 to the engine. The inlets of the dispensing conduits 3 are positioned, with respect to the common rail 4, to open out into a liquid fuel layer which will be formed in the common rail 4 when a separation of the mixture occurs.

Abstract: An intake air control device including a reed valve passage for supplying intake air via reed valves, and a sub intake passage for creating a swirl in the combustion chamber. The intake air control device further comprises a main intake passage for supplying intake air without passing same through the reed valves. A selection unit selects a passage through which the intake air is passed in response to a current engine driving condition, by selecting the sub intake passage when the current engine driving condition is a low engine speed and low engine load driving condition, selecting the reed valve passage when the current engine driving condition is a low engine speed and high engine load driving condition, and selecting the main intake passage when the current engine driving condition is a high engine speed driving condition.

Abstract: Disclosed is a piston for an internal combustion engine, which includes a land portion, and a skirt portion including a non-coated portion which is formed in an arbitrary shape on a sliding portion thereof and a coated portion which is formed on a sliding portion thereof other than the sliding portion on which the non-coated portion is formed. When the piston is descending, an oil which has adhered on a cylinder bore is introduced into the non-coated portion and accordingly an oil film is established in the non-coated portion. Since the advantageous effects of the coated portion and the oil film are combined in the piston, the sliding resistance can be reduced remarkably. Hence, the coated portion can be inhibited from wearing out, and its function of the sliding resistance reduction can be maintained for a long period of time. In addition, since the non-coated portion does not work as a sliding surface, there arises a reduced sliding surface area which also results in the reduction of the sliding resistance.

Abstract: An intake air control device including an intake passage provided with reed valves to prevent a back flow of intake air and exhaust gas. The intake passage has a predetermined length and a substantially uniform section, except for an enlarged portion close to an intake valve. A reed valve assembly is arranged in the enlarged portion and has side walls which divide an inside space of the enlarged portion into a first space surrounding the side walls, and a second space surrounded by the side walls, to have a section similar to the uniform section, and are mounted with reed valves to allow an intake air to flow only from upstream to the first space. When the current engine speed condition is a high engine speed condition, a closing unit for closing the second space downstream of the reed valve is opened, and a communicating unit for communicating the first space with the second space is interrupted.

Abstract: An engine control system having an oxygen density sensor arranged in an intake system at a position downstream of a throttle valve for detecting the amount of air newly introduced into the engine. The sensor is a limit electric current detection type capable of detecting a continuously changing density of the oxygen. An amount of fuel to be injected is calculated in accordance with the output level of the sensor by using mapped data of the output level of the sensor signal. A precise detection of new air is made possible while maintaining the advantages of the known D-J system. An ignition timing also may be calculated by the signal from the oxygen sensor.

Abstract: An engine control system having an oxygen density sensor arranged in an intake system at a position downstream of a throttle valve for detecting the amount of air newly introduced into the engine. The sensor is a limit electric current detection type capable of detecting a continuously changing density of oxygen. An amount of fuel to be injected is calculated in accordance with the output level of the sensor by using mapped data of the output level of the sensor signal. The sensitivity of the sensor is detected and multiplied by the output value of the sensor for obtaining a precise oxygen partial pressure. Instead of calculating the basic fuel amount from the output level of the oxygen density sensor, a normal intake pressure sensor with an intake pressure-engine speed map can be employed. In the latter case, the oxygen partial pressure from the oxygen density sensor is used for correcting the calculated basic fuel amount. The sensitivity of the sensor is also corrected.

Abstract: In a piezoelectric pressure indicator comprising a casing, a pressure receiving member at the bottom of the casing, piezoelectric elements mounted on the pressure receiving member, an acceleration compensating weight and acceleration compensating piezoelectric elements, both piezoelectric elements being connected such that the voltage produced thereby cancel with each other, thereby compensating for an effect of acceleration, an uppermost acceleration compensating element is formed with a perforation, and a lead wire for deriving the voltage is connected to the electrode of a lower imperforate acceleration compensating piezoelectric element to extend through the perforation of the imperforated element. In a modification, the pressure receiving member is covered by a heat resistant protective layer made of ceramic.

Abstract: A method of and an apparatus for measuring fluctuations in the indicated mean effective pressure of an engine from a deviation of the mean pressure or from an unbiased variance (mean square) of the mean pressure obtained from the deviation in the mean pressure by utilizing a deviation of the mean pressure becomes substantially identical with a deviation of the indicated mean effective pressure or an unbiased variance (mean square) of this mean pressure becomes substantially identical with an unbiased variance (mean square) of the indicated mean effective pressure in a cylinder of the engine. This deviation of the mean pressure is calculated from detected changes in the rotational speed of the engine.

Abstract: A multi-cylinder engine comprising a carburetor housing forming therein at least two branch intake passages. Each of the branch intake passages is connected to a respective intake port. A throttle valve of the carburetor is provided for each cylinder. Each of the throttle valves is arranged in the respective branch intake passage. A single common passage and branch connecting passages which are connected to the common passage are provided. Each of the branch connecting passages opens into the respective intake port in the vicinity of the rear face of the valve head of the corresponding intake valve.

Abstract: An internal combustion engine comprising a carburetor having a throttle valve. A secondary throttle valve is arranged in the intake passage at a position located downstream of the throttle valve of the carburetor. When the engine is operating under a light load, the secondary throttle valve remains fully closed. When the engine is operating under a heavy load, the secondary throttle valve remains fully opened. The intake passage located upstream of the secondary throttle valve is interconnected with the intake passage located downstream of the secondary throttle valve via an auxiliary intake passage having a cross-sectional area which is extremely smaller than that of the intake passage.

Abstract: A multi-cylinder engine comprising an intake manifold equipped with a carburetor. A secondary throttle valve is provided for each cylinder. Each of the secondary throttle valves is arranged in the respective manifold branch and fixed onto a common throttle shaft. An auxiliary intake passage is branched off from the collecting portion of the intake manifold and connected to a distribution channel. Each of the intake ports is connected to the distribution channel via a corresponding channel branch which opens into the intake port at a position near the intake valve. The common throttle shaft of the secondary throttle valves is connected to a vacuum operated diaphragm apparatus so that the secondary throttle valves are opened in accordance with a reduction in the level of vacuum produced in the intake manifold.

Abstract: A fuel system for an internal combustion engine comprises a pair of carburetors provided one each on the exhaust and intake side of the engine. The fuel-air mixture from the first carburetor is heated by exhaust gas before being introduced into an intake manifold through a passage within a cylinder head. Throttle valves are associated with the respective carburetors and are controlled in an interlocked manner so as to open the throttle valve associated with the first carburetor while maintaining the other throttle valve closed during a partial load operation, and to open the throttle valve associated with the second carburetor to supply the air enriched mixture to the cylinders while closing the first mentioned throttle valve during a full load operation. Alternatively, a combined use of supply from the first and second carburetors concurrently may be chosen.

Abstract: An intake manifold for a multicylinder internal combustion engine has a riser connectable to a carburetor and branch pipes connecting the riser and each suction port of respective cylinders of the engine, and is characterized by being provided with orifice means located at a position in each said branch pipe for defining the cross sectional area of the position to a preselected magnitude thereby rendering pressure in each said branch pipe and each said intake ports of the cylinder equal. The orifice means can be constituted by a plate-shaped gasket having orifices to be located in the positions in each said branch pipes.

Abstract: A fuel-air mixture heating device for use with an internal combustion engine wherein a combustion chamber of an auxiliary burner is disposed adjacent to an intake manifold of the engine for heating the same, said combustion chamber being communicated with said intake manifold through a control valve which varies its opening degree in response to a parameter or signal representative of at least one of the operating conditions of the engine.

Abstract: In a fuel-air mixture supply system, a rotor is provided at the junction of an intake manifold into which the mixture is supplied from the carburetor, and the branch pipes from the intake manifold are arranged equidistantly. The carburetor has a primary side mixture passage and a secondary side mixture passage, and the rotor is disposed beneath the primary side passage and arranged to be checked in rotation corresponding to the opening behavior of a throttle valve in the secondary side mixture passage.

Abstract: An intake manifold for a multicylinder internal combustion engine has a riser connectable to a carburetor and branch pipes connecting the riser and each suction port of respective cylinders of the engine, and is characterized by being provided with orifice means located at a position in each said branch pipe for defining the cross sectional area of the position to a preselected magnitude thereby rendering pressure in each said branch pipe and each said intake ports of the cylinder equal. The orifice means can be constituted by a plate-shaped gasket having orifices to be located in the positions in each said branch pipes.

Abstract: In a multicylinder internal combustion engine a cylindrical member is located downstream of a carburetor, with the cylindrical member disposed parallel to a vaporizing barrel of the carburetor and arranged downstream of the vaporizing barrel. A deflector plate for changing the stream of a fuel-air mixture is provided at a downstream position of the cylindrical member. Further, a cylindrical member with a deflector plate is disposed in the downstream of the primary vaporizing barrel of a duplex carburetor, and a cylindrical member with a slant port is disposed downstream of the secondary vaporizing barrel.

Abstract: A misfire detection system for an internal combustion engine is arranged to generate a first signal indicative of the oxygen concentration in the exhaust gas. Such first signal, whose instantaneous value is normally employed to adjust the engine fuel supply to control its air-to-fuel ratio, is additionally employed to interrupt the supply of fuel and secondary air to the engine when the first signal remains above a prescribed level after the elapse of a prescribed duration of the fuel supply adjustment.

Abstract: A system for heating the intake pipe of an internal combustion engine including a combustion equipment disposed adjacent to the intake pipe, a fuel supply system for supplying the fuel into the combustion equipment and an air supply system including an air pump for charging the air into the combustion equipment, the intake pipe being heated by the heat generated by the combustion of the air-fuel mixture in the combustion equipment. The fuel supply system includes a main fuel injection nozzle and an auxiliary fuel injection nozzle which is controlled by control means so as to start or stop the fuel injection depending upon the operating conditions of the engine. When the engine is started, both the main and auxiliary fuel injection nozzles inject fuel so as to attain the rapid heating of the intake pipe, but when the temperature of the intake pipe exceeds a predetermined level, the injection by the auxiliary fuel injection nozzle is stopped.