Stirling cycle machine
A Stirling cycle machine. The machine includes at least one rocking drive mechanism which includes: a rocking beam having a rocker pivot, at least one cylinder and at least one piston. The piston is housed within a respective cylinder and is capable of substantially linearly reciprocating within the respective cylinder. Also, the drive mechanism includes at least one coupling assembly having a proximal end and a distal end. The linear motion of the piston is converted to rotary motion of the rocking beam. Also, a crankcase housing the rocking beam and housing a first portion of the coupling assembly is included. The machine also includes a working space housing the at least one cylinder, the at least one piston and a second portion of the coupling assembly. An airlock is included between the workspace and the crankcase and a seal is included for sealing the workspace from the airlock and crankcase. A burner and burner control system is also included for heating the machine and controlling ignition and combustion in the burner.
1. An external combustion engine comprising:
a crankcase, the crankcase comprising a crankcase gas and lubricating oil, the crankcase gas having a crankcase pressure;
at least two heater heads;
at least two pistons, each of the at least two piston reciprocating within one of the at least two heater heads;
a working volume defined in part by the at least two heater heads and at least two pistons;
at least one pair of piston rods comprising a first piston rod and a second piston rod, each piston rod coupled to one of the at least two pistons and located partially in the working volume;
a drive mechanism located in the crankcase, the drive mechanism comprising a rotating crankshaft and a rocking beam, the crankshaft rotating the rocking beam, the first piston rod attached to a proximal end of the rocking beam and the second piston rod attached to a distal end of the rocking beam, the rocking beam constrains the first piston rod to move 180 degrees out of phase with the second piston rod;
an airlock separating the crankcase and the working volume, the airlock comprising an airlock gas, the airlock gas having an airlock pressure, wherein the at least one pair of piston rods pass through the airlock and each piston rod is sealed to the airlock by a rolling bellows seal; and
a airlock pressure regulator comprising at least one valve and a compressor, the airlock pressure regulator maintaining a pressure differential between the crankcase pressure and the airlock pressure.
2. The external combustion engine of claim 1 wherein the airlock pressure regulator further comprises an oil filter fluidly connected to the crankcase, the compressor being fluidly connected to the filter and the valve being a pressure regulating spool valve fluidly connected to at least one of the filter, the compressor and the airlock.
3. The external combustion engine of claim 2 wherein a position of the pressure regulating spool valve is responsive to differences between the airlock pressure and the crankcase pressure.
4. The external combustion engine of claim 3 , further comprising a controller wherein the controller operates the compressor based on the position of the spool valve.
5. The external combustion engine of claim 3 wherein the position of the pressure regulating spool valve is determined with a proximity sensor.
6. The external combustion engine of claim 3 wherein the pressure regulating spool valve further comprises an under-pressure relief valve that limits the airlock pressure to less than a predetermined value above the crankcase pressure.
7. The external combustion engine of claim 1 , wherein the airlock pressure regulator controls the airlock pressure to be not less than a first predetermined value and not more than a second predetermined value above the crankcase pressure.
8. The external combustion engine of claim 1 , wherein the airlock pressure regulator controls the airlock pressure to be not more than a first predetermined value below the crankcase pressure and not more than second predetermined value above the crankcase pressure, while the drive mechanism is not in motion.
9. The external combustion engine of claim 1 , further comprising a controller, wherein the controller prevents the drive mechanism from being in motion while the airlock pressure is less than a predetermined value above the crankcase pressure.
10. The external combustion engine of claim 1 further comprising a pressure equalization orifice between the airlock and the working volume, whereby the air lock pressure is approximately equal to an average of a working volume pressure.
11. A reciprocating apparatus with a pressure regulator for maintaining a pressure differential between a first closed volume and a second closed volume, the first closed volume filled with a gas and liquid, the gas in the first closed volume having a first pressure, the second closed volume filled with the gas, the gas in the second closed volume having a second pressure, the reciprocating apparatus with a pressure regulator comprising:
a boundary between the first closed volume and the second closed volume, the boundary comprises at least one flexible section, the flexible section attached to a reciprocating rod, the reciprocating rod driven by a rotating shaft via a rocking beam in the first closed volume; and
the pressure regulator comprising:
a filter fluidly connected to the first closed volume;
a compressor having an input and an output, the input fluidly connected to the filter; and
a bidirectional pressure regulating spool valve having fluidic connections to at least one of the filter, the compressor and the second closed volume, wherein the fluidic connections are based on a position of the pressure regulating spool valve, wherein the bidirectional pressure regulator spool valve controls the second pressure to be not less than a first predetermined value above the first pressure and not more than a second predetermined value above the first pressure, while the rotating shaft is turning.
12. A reciprocating apparatus with a pressure regulator for maintaining a pressure differential between a first closed volume and a second closed volume, the first closed volume filled with a gas and liquid, the gas in the first closed volume having a first pressure, the second closed volume filled with the gas, the gas in the second closed volume having a second pressure, the reciprocating apparatus with a pressure regulator comprising:
a boundary between the first closed volume and the second closed volume, the boundary includes at least one flexible section, the flexible section attached to a reciprocating rod, the reciprocating rod driven by a rotating shaft via rocking beam in the first closed volume;
the pressure regulator comprising:
a filter fluidly connected to the first closed volume;
a compressor having an input and an output, the input fluidly connected to the filter; and
a bidirectional pressure regulating spool valve having fluidic connections to at least one of the filter, the compressor and the second closed volume, wherein the fluidic connections are based on a position of the bidirectional pressure regulating spool valve; and
a controller, wherein the controller prevents the rotating shaft from turning while the second pressure is less than a predetermined value above the first pressure.