Patent ID: 8596241

Claim:
An internal combustion engine provided with a sub chamber which is communicated with a combustion chamber and a variable volume device which changes a volume of the sub chamber, wherein the variable volume device includes a communication part arranged at a cylinder head including a crown face of the combustion chamber and formed into a tubular shape so as to communicate with the combustion chamber, a movement member which is formed in a tubular shape so as to engage with the inside of the communication part and which has a closed end at the side facing the combustion chamber, and a support part which has a projecting part which engages with the inside of the movement member and which supports the movement member in a movable manner, the movement member divides the space at the inside of the communication part whereby a sub chamber is formed at the side facing the combustion chamber and a sealable gas chamber is formed at the opposite side to the side facing the combustion chamber, when the pressure of the combustion chamber reaches a control pressure, the change in pressure of the combustion chamber is used as a drive source so that the movement member moves and thereby the volume of the sub chamber becomes larger, and the movement member has an open end at the opposite side to the side facing the combustion chamber and discharges gas of the gas chamber which leaks from the parts where the movement member and the projecting part contact to the outside of the cylinder head.