Internal return pump

An internal return pump for a heat engine converting energy from a vapor source to an output device, the vapor source having a high pressure vapor supply and a low pressure vapor return, comprising:

• a heat engine section including,
• a heat engine body extending between a first and a second end and defining a heat engine bore therebetween;
• a first and a second heat engine body end secured to said first and a second end of said heat engine body or sealing opposed ends of said heat engine bore;
• a heat engine piston located in said heat engine bore;
• a heat engine piston rod connected to said heat engine piston;
• a first valve and a second valve assembly communicating with said heat engine bore for reciprocating said heat engine piston within said heat engine bore;
• a condensate pump operated by said heat engine piston rod for pumping low pressure vapor to the low pressure vapor return of the vapor source;
• said condensate pump has an input vein for channeling low pressure vapor from said first and second valve assemblies into said condensate pump;
• an output vein for channeling vapors from said pump to the low pressure vapor return of the vapor source;
• an input and an output check-valve disposed in said input vein and said output vein for controlling direction of pressure vapors from said first and second valve assemblies to the low pressure vapor return of the vapor source;
• an output section including,
• said heat engine piston rod extending through said second heat engine body end for connection to the output device.