A cryogenic refrigerator includes a displacer that is reciprocably mounted within a cylinder; a spool valve that is connected to the compressor and performs switching between an intake mode where a high-pressure refrigerant gas is supplied from the compressor to the cylinder and an exhaust mode where a low-pressure refrigerant gas within the cylinder is made to flow back to the compressor; and a drive unit that drives the spool valve. The spool valve has a valve body, and a drive rod that moves relative to the valve body and is integrated with the spool. The drive unit performs driving so that the magnitude of a speed when the drive rod moves from a top dead center to a bottom dead center is different from the magnitude of a speed when the drive rod moves from the bottom dead center to the top dead center, at the same displacement position.

A positive displacement machine comprises a cylinder inside which there are a mobile piston, at least one first and one second insulation chamber containing a respective set of gaskets, at least one first and one second gland each of which is suitable for operating on one of the sets of gaskets, each gland comprising a tubular threaded portion and a ring nut fixedly attached to the tubular threaded portion. A sleeve able to slide with respect to said cylinder has a first end in contact with the first set of gaskets and a second threaded end for receiving in engagement the tubular threaded portion of the second gland, the sleeve being slidingly engaged by the first gland, and at least one of the ring nuts being a cylindrical gear wheel with straight teeth.

Systems and methods include providing an aircraft with a direct drive dual-concentric valve (D3V) having a body, an outer secondary spool coaxially located within a bore of the body and linearly displaceable relative to the body, an inner primary spool coaxially located within a bore of the secondary spool and linearly displaceable relative to the secondary spool and the body. A plurality of piezo stacks is coupled to a first end of the primary spool, and applying a voltage to at least one of the piezo stacks causes an output stroke of the plurality of the piezo strokes for displacing the primary spool. The secondary spool is displaced together with the primary spool relative to the body if displacement of the primary spool relative to the secondary spool cannot occur.

Systems and methods include providing an aircraft with a direct drive dual-concentric valve (D3V) having a body, an outer secondary spool coaxially located within a bore of the body and linearly displaceable relative to the body, an inner primary spool coaxially located within a bore of the secondary spool and linearly displaceable relative to the secondary spool and the body. A plurality of piezo stacks is coupled to a first end of the primary spool, and applying a voltage to at least one of the piezo stacks causes an output stroke of the plurality of the piezo strokes for displacing the primary spool. The secondary spool is displaced together with the primary spool relative to the body if displacement of the primary spool relative to the secondary spool cannot occur.

A reciprocating linear/rotational motion conversion device has a main shaft, a linear motion guiding mechanism, a sector gear and a rack frame. The sector gear is fixedly connected with the main shaft. A rack pair is arranged on the inner wall of the rack frame. The rack pair comprises a first gear rack and a second gear rack separately arranged on both sides of the sector gear. The reciprocating linear/rotational motion conversion device further includes a reversing mechanism fixedly connected with the main shaft. A cylinder device contains the reciprocating linear/rotational motion conversion device, connecting rods, pistons and cylinder bodies. The cylinder body is sleeved on the piston, and a cylinder head is arranged on one end of the cylinder body.

Various exemplary embodiments relate to an engine including a cylindrical cassette that converts linear into rotational motion. The linear motion is provided by a normal cylinder and valve mechanism driving pistons in a reciprocating motion, and the rotational motion is transmitted to an output shaft. Further embodiments relate to methods of converting linear motion to rotational motion by using a cylindrical cassette.

A reciprocating linear/rotational motion conversion device has a main shaft, a linear motion guiding mechanism, a sector gear and a rack frame. The sector gear is fixedly connected with the main shaft. A rack pair is arranged on the inner wall of the rack frame. The rack pair comprises a first gear rack and a second gear rack separately arranged on both sides of the sector gear. The reciprocating linear/rotational motion conversion device further includes a reversing mechanism fixedly connected with the main shaft. A cylinder device contains the reciprocating linear/rotational motion conversion device, connecting rods, pistons and cylinder bodies. The cylinder body is sleeved on the piston, and a cylinder head is arranged on one end of the cylinder body.

Systems and methods include providing an aircraft with a direct drive dual-concentric valve (D3V) having a body, an outer secondary spool coaxially located within a bore of the body and linearly displaceable relative to the body, an inner primary spool coaxially located within a bore of the secondary spool and linearly displaceable relative to the secondary spool and the body. A plurality of piezo stacks is coupled to a first end of the primary spool, and applying a voltage to at least one of the piezo stacks causes an output stroke of the plurality of the piezo strokes for displacing the primary spool. The secondary spool is displaced together with the primary spool relative to the body if displacement of the primary spool relative to the secondary spool cannot occur.

Systems and methods include providing an aircraft with a direct drive dual-concentric valve (D3V) having a body, an outer secondary spool coaxially located within a bore of the body and linearly displaceable relative to the body, an inner primary spool coaxially located within a bore of the secondary spool and linearly displaceable relative to the secondary spool and the body. A plurality of piezo stacks is coupled to a first end of the primary spool, and applying a voltage to at least one of the piezo stacks causes an output stroke of the plurality of the piezo strokes for displacing the primary spool. The secondary spool is displaced together with the primary spool relative to the body if displacement of the primary spool relative to the secondary spool cannot occur.

Systems and methods include providing an aircraft with a direct drive dual-concentric valve (D3V) having a body, an outer secondary spool coaxially located within a bore of the body and linearly displaceable relative to the body, an inner primary spool coaxially located within a bore of the secondary spool and linearly displaceable relative to the secondary spool and the body, and multiple motor assemblies coupled to the primary spool that provide selective displacement of the primary spool or the secondary spool. Each motor assembly includes a clutching mechanism that selectively couples a motor of the motor assembly to and from the primary spool.