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An auxiliary piston device to be used in an internal combustion engine

IP.com Disclosure Number: IPCOM000022244D
Publication Date: 2004-Mar-02
Document File: 3 page(s) / 83K

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention relates to an auxiliary piston device, which is placed in connection with a combustion chamber of an internal combustion engine. Preferably, the auxiliary piston device is used in an internal combustion engine of the type where a fuel-air mixture is self-ignited by the compression heat, such as HCCI-engines. By the use of such an auxiliary piston device, the volume of the combustion chamber may be varied. The auxiliary piston device comprises a controllable outlet port for the exhaust gases from the combustion chamber. Thereby, it is possible to provide an engine braking by the use of the auxiliary piston device. The auxiliary piston device may be used instead of an exhaust valve in the combustion chamber or as a separate unit working together with the ordinary exhaust valves.

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An auxiliary piston device to be used in an internal combustion engine

The invention relates to an auxiliary piston device, which is placed in connection with a combustion chamber of an internal combustion engine. Preferably, the auxiliary piston device is used in an internal combustion engine of the type where a fuel-air mixture is self-ignited by the compression heat. Such internal combustion engines are usually called HCCI-engines (Homogeneous Charge Compression Ignition). However, the auxiliary piston device is also possible to use in other types of internal combustion engines. By the use of such an auxiliary piston device, the volume of the combustion chamber may be varied. The auxiliary piston device comprises a controllable outlet port for the exhaust gases from the combustion chamber. Thereby, it is possible to provide an engine braking by the use of the auxiliary piston device. The auxiliary piston device may be used instead of an exhaust valve in the combustion chamber or as a separate unit working together with the ordinary exhaust valves.

Figs. 1a-d show a piston device according to an embodiment of the invention. The piston device is mounted in a cylinder head 1 of an HCCI-engine. The piston device comprises a piston 2 and a rod piston member 3 having an extension through an elongated hole in cylinder head 1. The rod piston member 3 comprises a first part 3a, which is connected to the piston 2, a second part 3b, which is connected to a suitable camshaft mechanism, and an adjustable space 3c, which is arranged between the first part 3a and the second part 3b. The space 3c is intended to be filled with an incompressible fluid such as an oil. A fluid control system is arranged to supply a variable amount of oil to the space 3c. The fluid control system comprises a first channel 4 having a control valve 4a for controlling the fed of oil to the space 3c. The fluid control system comprises a second channel 5 having a control valve 5a and a third channel 6 having a control valve 6a. These channels are used for discharging oil from the space 3c. The piston 2 is provided in a cylinder-shaped recess 7. The cylinder-shaped recess 7 constitutes an additional volume of the combustion chamber 8. The cylinder-shaped recess 7 comprises an opening for an outlet conduit 9 for the exhaust gases. A spring, which is not visible in the drawings, acts on the piston 2 for moving it in a vertical direction upwards in the cylinder-shaped recess 7.

Fig 1a shows the piston 2 in a base position, which is located substantially in the middle of the cylinder-shaped space 7. In the base position, the piston 2 covers the opening of the outlet conduit 9. Oil is fed to the space 3c from the first channel 4 and it is discharged from the space 3c through the third channel 6. The second channel 5 is closed. In Fig. 1b, a main piston 10 of the cylinder moves upwards during compression of the fuel-air mixture in the combustion chamber 8. In order to move the piston 2 fr...