Precombustion chamber gas engine

A precombustion chamber gas engine including a precombustion chamber communicating with a main combustion chamber, comprising:

• 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;
• a valve-opening-degree control device configured to control an opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve,
• a precombustion-chamber-fuel-line-pressure detection unit for detecting the precombustion chamber fuel line pressure of the precombustion-chamber-fuel supply line, and
• an intake-precombustion-chamber-pressure detection unit for obtaining the precombustion chamber pressure, the intake-precombustion-chamber-pressure detection unit being capable of obtaining an intake precombustion chamber pressure which is a pressure related to the precombustion chamber pressure when an intake valve controlling a communication state between an intake passage and the cylinder is open,
• wherein 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,
• wherein the valve-opening-degree control device is configured to control the opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve so that the precombustion chamber fuel line pressure increases when the exhaust precombustion chamber pressure increases, and the valve-opening-degree control device is configured to control the opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve so that the precombustion chamber fuel line pressure decreases when the exhaust precombustion chamber pressure decreases,
• wherein the valve-opening-degree control device is configured to control the opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve so that a differential pressure during exhaust between the precombustion chamber fuel line pressure detected by the precombustion-chamber-fuel-line-pressure detection unit and the exhaust precombustion chamber pressure obtained by the exhaust-precombustion-chamber-pressure acquisition unit is equal to a target differential pressure during exhaust, and
• wherein the valve-opening-degree control device includes:
• a target-differential-pressure calculation section for calculating the target differential pressure during exhaust, based on an engine rotational speed, the intake precombustion chamber pressure, and the exhaust precombustion chamber pressure;
• and
• a valve-opening-degree adjustment section for adjusting the opening degree of the precombustion-chamber-fuel-line-pressure adjustment valve so that the differential pressure during exhaust is equal to the target differential pressure during exhaust.