1.  Field of the Invention
The present invention relates to a scroll expansion machine in which high pressure fluid that is introduced in the machine is prevented from flowing out from an expansion chamber in order that the configuration members of the machine is not adversely affected by the flowing-out fluid. 
2.  Background of the Invention
In a scroll expansion machine in which high pressure fluid is fed into an expansion chamber where the high pressure fluid is expanded, the energy of the high pressure fluid expanding in the expansion process is used for revolving a revolving scroll; thereby, the scroll expansion machine is provided with the revolving scroll having a spirally formed lap thereof and a fixed scroll having a spirally formed lap thereof, the lap of the revolving scroll and the lap of the fixed scroll being meshed with each other so as to form the expansion chamber.  Further, the energy of the revolving movement regarding the revolving scroll is, for example, used as the energy for compressing gas.  Or, the revolving movement of the revolving scroll is transmitted to a generator via a rotating shaft so as to regenerate electric power. 
In comparison with an expansion machine provided with a turbine, the advantageous points are that the scroll expansion machine can be smaller scale equipment, and the machine can be driven with a smaller power; thus, the machine can advantageously regenerate power.  Or, the expansion machine can be supplied to land facilities so that the electric power obtained by the high-pressure steam that is introduced in the scroll expansion machine is sent to the utility power grid (transmission network).  Patent Reference 1 discloses an expansion machine provided with such a regeneration generator.