Mitsubishi Heavy Industries Engine & Turbocharger, Ltd.

Mitsubishi Heavy Industries Limited

Daisuke Takemoto

Akihiro Yuuki

Yuta Furukawa

Shunya Sasaki

Kazuo Ogura

Satoshi Yamada

Kazutoshi Nomura

Hiroyuki Endo

Tatsuo Ishiguro

Shinnosuke Osafune

Yuuta Furukawa

A precombustion chamber gas engine includes a main-chamber forming portion forming a main combustion chamber, a precombustion-chamber forming portion forming a precombustion chamber communicating with the main combustion chamber via a plurality of nozzle holes, and an ignition device disposed in the precombustion chamber and having an ignition portion spaced from a main chamber central axis of the main combustion chamber at a predetermined distance. In a plan view, the precombustion chamber has a near-ignition region including the ignition portion and a far-ignition region opposite to the near-ignition region separated by a borderline passing through a precombustion chamber central axis of the precombustion chamber and perpendicular to a straight line passing through the precombustion chamber central axis and the ignition portion. The distance between the precombustion chamber central axis and a precombustion-chamber-side opening end, connected to the precombustion chamber, of a specific far nozzle hole which is at least one nozzle hole in the far-ignition region is shorter or longer than the distance between the precombustion chamber central axis and a precombustion-chamber-side opening end of a specific near nozzle hole which is at least one nozzle hole in the near-ignition region.

Precombustion chamber gas engine

A precombustion chamber gas engine includes a main-chamber forming portion forming a main combustion chamber, a precombustion-chamber forming portion forming a precombustion chamber communicating with the main combustion chamber via nozzle holes, and an ignition device disposed in the precombustion chamber and having an ignition portion spaced from the main chamber central axis at a predetermined distance. In a plan view, the precombustion chamber has a near-ignition region including the ignition portion and a far-ignition region opposite to the near-ignition region separated by a borderline passing through the precombustion chamber central axis and perpendicular to a straight line passing through the precombustion chamber central axis and the ignition portion. The cross-sectional area of a specific near nozzle hole which is at least one nozzle hole in the near-ignition region is smaller than the cross-sectional area of a specific far nozzle hole which is at least one nozzle hole in the far-ignition region.

A precombustion chamber gas engine includes a main-chamber forming portion forming a main combustion chamber, a precombustion-chamber forming portion forming a precombustion chamber including a small-diameter cylinder chamber communicating with the main combustion chamber via a plurality of nozzle holes and a large-diameter cylinder chamber, an ignition device disposed in the large-diameter cylinder chamber of the precombustion chamber, and a precombustion-chamber-gas supply device for supplying a precombustion-chamber fuel gas to the precombustion chamber not via the main combustion chamber. The nozzle hole is formed so that a precombustion-chamber-side straight line passing through a central position of a precombustion-chamber-side opening of the nozzle hole and parallel to an extending direction of a central line of the precombustion-chamber-side opening of the nozzle hole intersects with a main-chamber-side straight line passing through a central position of a main-chamber-side opening of the nozzle hole and parallel to an extending direction of a central line of the main-chamber-side opening of the nozzle hole, and an acute angle between a precombustion chamber central axis of the precombustion chamber and the precombustion-chamber-side straight line is smaller than an acute angle between the precombustion chamber central axis and the main-chamber-side straight line.

A knocking detection method includes: a step of obtaining an oscillation waveform generated by combustion in the combustion chamber; a step of setting a first time window preceding a maximum inner pressure time at which an inner pressure of the combustion chamber is at maximum in a single combustion cycle and a second time window immediately after the maximum inner pressure time, and transforming each of a first waveform portion included in the first time window and a second waveform portion included in the second time window into an expression-domain expression, of the oscillation waveform; and a step of extracting a first peak at which amplitude of the frequency domain expression of the first waveform portion is at maximum in the first frequency windows and a second value at which the amplitude of the frequency domain region of the second waveform portion is at maximum in the second frequency window and determining whether knocking has occurred on the basis of the second peak value and the first peak value.

Knocking detection method, ignition timing control method, and ignition timing control system

A precombustion chamber gas engine including a precombustion chamber communicating with a main combustion chamber includes: a precombustion-chamber-fuel supply line through which a precombustion chamber fuel flows; a precombustion-chamber-fuel supply valve connected to the precombustion-chamber-fuel supply line and controlling supply of the precombustion chamber fuel to the precombustion chamber, the precombustion-chamber-fuel supply valve being configured to open when a precombustion chamber fuel line pressure, which is a pressure of the precombustion-chamber-fuel supply line, is larger than a precombustion chamber pressure, which is a pressure of the precombustion chamber; a precombustion-chamber-fuel-line-pressure adjustment valve disposed on the precombustion-chamber-fuel supply line and capable of adjusting the precombustion chamber fuel line pressure; an exhaust-precombustion-chamber-pressure acquisition unit capable of obtaining an exhaust precombustion chamber pressure which is a pressure related to the precombustion chamber pressure when an exhaust valve controlling a communication state between an exhaust passage and a cylinder forming the main combustion chamber is open; and a valve-opening-degree control device configured to control an opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve. The valve-opening-degree control device is configured to control the opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve in accordance with the exhaust precombustion chamber pressure obtained by the exhaust-precombustion-chamber-pressure acquisition unit.

An internal combustion engine includes: an engine body () having at least one cylinder; and an air-supply manifold () including an adjustment pipe (). The length of the adjustment pipe is set so that a first pressure wave (A) propagating from the air-supply manifold toward the adjustment pipe and a second pressure wave (B) propagating from the adjustment pipe toward the air-supply manifold have opposite phases from each other at the cylinder.

Internal combustion engine

A precombustion-chamber engine includes a cylinder, a cylinder head disposed on a top of the cylinder, and a piston reciprocably disposed within the cylinder. A main combustion chamber is defined between the piston and the cylinder head. The cylinder head includes a precombustion-chamber forming part which defines a precombustion chamber communicating with the main combustion chamber through a nozzle. The precombustion chamber includes a cylindrical first passage part extending upwardly from the nozzle, a second passage part extending upwardly from the first passage part and having an upwardly-increasing cross-sectional area, and a cylindrical space part which extends upwardly from the second passage part and in which a spark plug is disposed. Center O of a cross-section, orthogonal to straight line L, of the second passage part is eccentric with respect to straight line L composed of an axis of the first passage part and an extended line of the axis.

Precombustion-chamber engine

An object is to improve a trap effect to trap ignition fuel gas supplied to a pre-combustion chamber and reduce an amount of non-combusted ignition fuel gas flowing out of the pre-combustion chamber to suppress a decrease in combustion efficiency. A pre-combustion-chamber type gas engine includes: a pre-combustion chamber Sr disposed on a cylinder head portion; a spark plugdisposed on an upper part of the pre-combustion chamber Sr; a pre-combustion-chamber gas supply mechanism configured to supply ignition fuel gas 'g' to the pre-combustion chamber Sr via gas supply channels for the pre-combustion chamberandwith an opening on an upper part of the pre-combustion chamber Sr; and a check valvedisposed in the gas supply channelfor the pre-combustion chamber. The opening of the gas supply channelfor the pre-combustion chamber is disposed on a lower surface of a cover memberforming the pre-combustion chamber Sr or on an upper section of a side wall of a pre-combustion-chamber member, the opening facing in a tangent direction of a side-wall inner peripheral surfaceof the pre-combustion-chamber member. The ignition fuel gas 'g' supplied to the pre-combustion chamber Sr forms a swirl flow swhich swirls about a longitudinal axis x of the pre-combustion chamber Sr inside the pre-combustion chamber Sr.

Pre-combustion-chamber type gas engine

Disclosed is an oil jet device for cooling a piston, including: an oil coolerthat is disposed upstream of an oil injection nozzle; an oil pumpthat is disposed upstream of the oil cooler; a first switching adjustment valvethat is disposed between the oil injection nozzleand the oil coolerand adjusts a flow dividing ratio at which the cooling oil from the oil cooleris distributed to the oil injection nozzleside and to an oil pan side; and a control unit that has an oil quantity adjustment mapfor switching the first switching adjustment valvebased on a piston temperature calculation mapfor calculating the temperature of the pistonusing detection values acquired respectively by a cooling water temperature sensor, a rotation speed sensorand a load sensor

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Tokyo, Japan

Daisuke Takemoto