Positive displacement expander

A positive displacement expander having within a casing an expansion mechanism for generating power by the expansion of fluid in an expansion chamber, wherein:

• the casing further contains therein pressure snubbing means for inhibiting at least either variation in the pressure of fluid which is drawn into the expansion chamber or variation in the pressure of fluid which is discharged out of the expansion chamber;
• (a) the expansion mechanism is provided with a suction passageway for introducing fluid into the expansion chamber and a discharge passageway for discharging fluid after expansion from the expansion chamber;
• and
• (b) the pressure snubbing means is provided with a pressure snubbing chamber separated into a fluid inflow/outflow chamber in fluid communication with either the suction passageway or the discharge passageway, and a back pressure chamber by a partitioning member;
• and
• the pressure snubbing chamber is configured such that the partitioning member displaces to cause the volume of the inflow/outflow chamber to increase or decrease in response to fluid pressure pulsation of the suction passageway or the discharge passageway, thereby causing the inflow/outflow chamber to perform suction of fluid from and discharge of fluid into either the suction passageway or the discharge passageway.