Mazda Motor Corporation

Mikihito Fujii

Toshihiko Hattori

Mitsuo Hitomi

Naoyuki Yamagata

Masashi Marubara

Hiroyasu Uchida

Toshimitsu Tanaka

Kazuaki Umezono

Shunki Okazaki

Takamasa Matsumoto

Mitsuo Nakamura

Nobuhiro Soumiyou

Hiroyuki Yamashita

Hiroyuki Oda

Kazuhiko Ueda

Fumihiko Saito

Yoshihisa Nakamoto

Kazuya Yokota

Kazuaki Narahara

Masaharu Marumoto

Hidetoshi Kudou

Masakazu Matsumoto

Susumu Masuyama

Yoshito Wakabayashi

An exhaust device includes a plurality of independent exhaust passages connected to an exhaust port of one cylinder or a plurality of cylinders that are non-sequential in exhaust order, and a mixing pipe into which exhaust that has passed through the respective independent exhaust passages flows. The downstream ends of the respective independent exhaust passages are connected in a bundled form to the upstream end of the mixing pipe. A cavity expansion chamber is disposed in an exhaust passage downstream from the mixing pipe. The cavity expansion chamber is disposed in a position (at a distance L2) such that, in the intermediate speed range, a negative pressure wave generated due to an exhaust pressure wave generated by opening an exhaust valve being reflected by the cavity expansion chamber reaches the exhaust port during an overlap period of the exhaust valve and an intake valve of the cylinder.

Exhaust device for multicylinder engine

A multi-cylinder engine intake and exhaust having a plurality of independent exhaust passages each connected to an exhaust port in a respective one of a plurality of cylinders, a collecting pipe connected to downstream ends of the plurality of independent exhaust passages, and a volume-enlarged portion provided downstream with respect to the collecting pipe. Each of at least a downstream portion of each of the plurality of independent exhaust passages and at least an upstream portion of the collecting pipe is formed such that a cross-sectional area thereof gradually decreases toward a downstream direction. The volume-enlarged portion is formed such that a cross-sectional area thereof is relatively increased so as to cause a positive pressure wave of exhaust gas reaching the volume-enlarged portion to be reflected and converted to a negative pressure wave.

Intake and exhaust system for multi-cylinder engine

An exhaust apparatus for a multi-cylinder engine which is capable of suppressing deterioration in ejector effect with a simple configuration comprises: a plurality of independent exhaust ducts each having an upstream end connected to an exhaust port of one cylinder or exhaust ports of two or more cylinders which are non-successive in terms of exhaust order; and a merged portion configured to allow exhaust gas passing through each of the independent exhaust ducts to flow thereinto and formed to be gradually reduced in diameter toward a downstream side in an exhaust gas flow direction. The independent exhaust ducts are connected to an upstream end of the merged portion in such a manner that downstream ends thereof are bundled together. An O2 sensor is provided in the merged portion or a portion of an exhaust duct line downstream of the merged portion, to partially block an exhaust gas flow passage.

Exhaust apparatus for multi-cylinder engine

A valve overlap period is increased as a desired torque of an engine increases by advancing an opening timing of an intake valve at a rate greater than that of retarding a closing timing of an exhaust valve in a low engine-torque area in which the desired torque of the internal combustion engine is relatively low (step S). The valve overlap period is increased as the desired torque of the engine increases by retarding the closing timing of the exhaust valve at a rate greater than that of advancing the opening timing of the intake valve in a high engine-torque area in which the desired torque of the internal combustion engine is relatively high (step S). Accordingly, the drivability can be improved by obtaining the proper torque and the smooth torque curve in the wide driving area.

Method of controlling engine system and engine system

An engine system with a turbocharger is provided. The system may include an exhaust manifold having plural independent exhaust passages, each of the exhaust passages being connected to an exhaust port of a corresponding engine cylinder. The system may further include a collective part formed by gathering said independent exhaust passages in said exhaust manifold or on a downstream side of said exhaust manifold. The system may further include an exhaust turbocharger connected to a downstream side of said collective part. The system may further include a variable exhaust valve for changing each passage cross-sectional area of said independent exhaust passage at an upstream side of said collective part. The system may further include a controller for controlling said variable exhaust valve, wherein said controller is configured to perform independent exhaust throttle control for reducing a passage cross-sectional area of at least one of said independent exhaust passages.

Supercharger for an engine

There is provided a method for controlling an electrically driven supercharger of an internal combustion engine. The method comprises operating the supercharger at a first speed during a first engine operating condition. The method further comprises operating the supercharger at a second speed during a second engine operating condition, the second speed being lower than the first speed and increasing as the capacity of the electric power source decreases. According to the method, during a transition from the second engine operating condition to the first engine operating condition, the speed of the supercharger is increased from the second speed to the first speed. At that time, the second speed is increased as the capacity of the electric power source decreases, and as a result, the supercharger speed increase that results from the transition may become smaller. Consequently, the inrush electric current from the electric power source to the electric motor may be reduced during the transition, thereby avoiding further degradation of the electric power source.

Control for electrically driven supercharger

A direct-injection, spark-ignition engine of the present invention includes a turbo-charging device which promotes the temperature rise or activation of the exhaust-gas purification catalyst disposed downstream of a turbine during cold start. During engine cold start, the fuel injection by the fuel injector is divided into a leading fuel injection performed during the latter half of the compression stroke, prior to the ignition timing, and a trailing fuel injection performed during the expansion stroke, after the ignition timing. The amount of the intake-air and the amount of the fuel injection are so controlled that the air-fuel ratio in the combustion chamber during the combustion of the fuel by the leading fuel injection (a leading air-fuel ratio) is within the range of 2<&lgr;<3, and the air-fuel ratio in the combustion chamber during the combustion of the fuel by the trailing fuel injection (a total air-fuel ratio) is within the range of 1<&lgr;<2. This raises exhaust-gas temperature with heat from the combustion of the fuel injected in the compression stroke and by the oxidization of the unburned HG from turbine agitation, to raise the exhaust-gas temperature for promoting the temperature rise or activation of the exhaust-gas purification catalyst downstream of the turbine.

Direct-injection spark-ignition engine with a turbo charging device

A spark-ignition type 4-cycle direct injection engine is provided with a turbocharger for boosting intake air and an injector for directly injecting fuel to a combustion chamber within a cylinder, wherein in a &lgr;&equals;1 region (II) and an enriched region (III) on the high-speed high-load side, fuel is injected during the intake stroke of the cylinder to attain a state of homogenous combustion. When the engine is in the high-speed side (specific region) of the enriched region (III), the air-fuel ratio A/F of the air-fuel mixture in the cylinder is controlled to become A/F&lE;13, the tumble flow T is strengthened by closing the TSCVs, and the opening degree of a wastegate valve of the turbocharger is controlled in order to increase the maximum boost pressure and compensate the drop in intake efficiency that is caused by closing the TSCVs. Thus, in the high-speed side of the enriched region (III), a maximum output of the engine is ensured and the dependability of the exhaust system is secured while the PM in the exhaust can be decreased.

Spark-ignition direct injection engine with supercharger

A control device for a direct injection engine having a catalyst provided in an exhaust passage for converting exhaust gases and an injector for injecting fuel directly into a combustion chamber, includes a temperature state identifier for judging the temperature state of the catalyst, a load condition detector for sensing engine load conditions, and a fuel injection controller for controlling fuel injection from the injector. The fuel injection controller performs quick light-off control operation by causing the injector to inject fuel in one-time injection mode during a compression stroke in a specific low-load operating range of the engine when the catalyst is in its unheated state where its temperature is below its activation temperature, and switching the mode of fuel injection to intake-compression stroke split injection mode in a specific high-load operating range of the engine.

Control device for direct injection engine

An intake system for a vehicle for delivering intake air through separate or discrete intake passages of the intake system into engine cylinders through discrete intake passages. A collector chamber and a resonator chamber connect with an upstream main intake passage and the discrete intake passages. The collector chamber communicates at one end with upstream ends of the discrete intake passages and at its another end, opposite to the one end, with the resonator chamber. The discrete intake passages are clustered or grouped together at their upstream ends and connected as a cluster to the collector chamber.

Intake system for multi-cylinder engine

Discrete intake passages communicating with respective cylinders of a multiple-cylinder in-line engine are merged into an integrated chamber at their upstream ends. The integrated chamber is disposed above the engine and extends substantially horizontally. Each discrete intake passage extends from the engine body, bends upward toward the integrated chamber and is connected to the downstream side end face of the integrated chamber. The discrete intake passages for the cylinders which are positioned relatively near to the integrated chamber are connected to the downstream side end face of the integrated chamber at an upper portion of the end face and the discrete intake passages for the cylinders which are positioned relatively far from the integrated chamber are connected to the downstream side end face of the integrated chamber at a lower portion of the end face.

Intake system for engine

An engine has a plurality of cylinders and the cylinders are divided into first and second cylinder groups so that the cylinders in each cylinder group do not fire one after another. An intake system for the engine has a plurality of discrete intake passages extending from the respective cylinders of the engine and merge into a junction chamber, a common intake passage which opens to the atmosphere at its upstream end and communicates with the junction chamber at its downstream end, a first communicating passage which is connected to the discrete intake passages for the first cylinder group at their intermediate portions and communicates them with each other, and a second communicating passage which is connected to the discrete intake passages for the second cylinder group at their intermeidate portions and communicates them with each other.

A multiple-cylinder engine has first and second groups of cylinders, the firing order being set so that the cylinders in each group do not fire one after another. An intake system for the engine has first and second groups of discrete intake passages which communicate with the respective cylinders in the first and second groups at their downstream ends and with first and second branch intake passage at their upstream ends. A circular passage communicates with the discrete intake passages at their intermediate portions so that all the discrete intake passages communicate with each other through the circular passage, and an on-off valve opens the circular passage when the engine speed is higher than a predetermined value and closes the same when the engine speed is not higher than the predetermined value. The length of each discrete intake passage is such that a first inertia tuning is obtained at a first engine speed lower than a maximum allowable engine so long as the discrete intake passages are not communicated with the circular passage, and the length of the part of each discrete intake passage downstream of the circular passage is such that a second inertia tuning is obtained at a second engine speed higher than the maximum allowable engine so long as the discrete intake passages are communicated with the circular passage.

An intake system for a multiple-cylinder engine has a plurality of discrete intake passages which are substantially equal to each other in length and are connected to the respective cylinders at their downstream ends. The upstream ends of the discrete intake passages are merged into an integrated chamber, and an upstream side intake passage communicates the integrated chamber with the atmosphere. The integrated chamber has an upstream side end face and a downstream side end face, and the cross-sectional area of the integrated chamber increases from the upstream side end face to the downstream side end face, the upstream side intake passage having opening into the integrated portion in the upstream side end face, and the discrete intake passages respectively having openings into the integrated chamber in the downstream side end face. The area of the upstream side and downstream side end faces of the integrated chamber S.sub.0 S.sub.1, the sum of the areas of the openings of the discrete intake passages into the integrated chamber S.sub.N and the distance H between the upstream side and downstream side end faces of the integrated chamber satisfy the following formulae ##EQU1##

Intake system for multiple-cylinder engine

An air intake device of an engine has intake pipes connected to each of the engine cylinders divided into first and second groups to prevent the continuance of the intake strokes of adjacent cylinders. A first connecting cavity connected to the first group of cylinders and a second connecting cavity connected to the second group of cylinders are arranged in parallel with each other, for effecting supercharging by utilizing the dynamic effect of intake air into each cylinder. A first communicating passage is connected at one end to a longitudinal end of the first connecting cavity and at the other end to a longitudinal end of the second connecting cavity. A second communicating passage arranged on the same side as the first communicating passage is connected at one end to a side of the first connecting cavity and at the other end to a side of the second collecting cavity. The effective passage length of the first communicating passage is shorter than that of the second communicating passage.

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Aki-gun, Japan

Mikihito Fujii