RU2079065C1 - Gas refrigerating machine with working piston possessing members with form memory - Google Patents

Abstract

FIELD: gas regenerative refrigerating machines working by Stirling cycle. SUBSTANCE: in starting the motor of machine, part of compressable working gas is forced into crankcase through clearances between sealing ring 11 and inner surface of cylinder 13, as well as between inner sealing rings 14 and expulsor rod 15. Remaining part of gas enters reservoirs 3 and 4 through valve gears 16 and 17. Temperature of gas rises due to compression, increasing length of corrugated plates made from material possessing form memory and causing outer sealing ring 11 and inner sealing rings 14 to move towards surface of cylinder 13 and expulsor rod 15, thus reducing the clearance between them. When motor is stopped, gas flows from reservoirs 3 and 4 through holes of smaller diameter in body of balls of valve gears 16 and 17 to working chamber due to difference in pressures, causing drop of temperature and reduction of length of corrugated plates, thus returning the devices to the initial state. EFFECT: enhanced efficiency. 1 dwg

Description

 The invention relates to the field of gas regenerative machines operating on the Stirling cycle.

The known effect of "shape memory", the phenomenon of spontaneous shape recovery with temperature. In some materials, the effect of repeatedly reversible shape memory does not disappear after almost any number of heat exchanges. Thus, it has been established that in AuCd alloys a multiple-reversible shape memory appears at least for 3 • 10 ⁷ thermal cycles [1]
A sealing device for the piston rod of a Stirling engine is known, including a gas seal and intermediate chambers connected to the oil tank [2]
The disadvantage of this device is a complex diagram of the relationship of its elements, an increase in weight and size parameters associated with the introduction of additional elements and pipelines.

Known gas cryogenic machine containing a housing divided by a piston into the crankcase volume and the compression cavity, equipped with a line of communication between the compression cavities and the crankcase with non-return valves [3]
The disadvantage of this device is the complication of the design of the refrigeration machine associated with the introduction of additional air channels, temperature sensors, an electronic control unit.

Known refrigeration cryogenic machine, including compression cavity, expansion and crankcase, displacer, regenerator, heat exchangers, buffer cavity connected to the working through the discharge valve to reduce the starting torque, the working piston with a sealant rod displacer [4]
The disadvantage of this refrigeration machine is the increase in overall dimensions, the complexity of the design due to the introduction of a buffer cavity to facilitate starting the machine and the possibility of some leakage of working gases from the compression cavity into the crankcase during operation of the refrigeration machine through the sealant of the displacer rod.

 The technical result that can be obtained by carrying out the invention consists in the possibility of creating a decompression condition in the compression cavity at the time of starting up and leaving the chiller to an operating mode that facilitates start-up and shortens the exit time, and in increasing the efficiency of the displacer rod during operation by using elements with shape memory in the form of pre-compressed corrugated plates.

 To achieve this technical result, a gas chiller, including compression, expansion and crankcase cavities, a displacer, a regenerator, heat exchangers, is equipped with a working piston made in the form of a piston body with an upper figured end and a piston cover forming a container for installing two dynamic sealing assemblies, consisting of stops and corrugated plates of material with shape memory, an external sealing ring having a tip with a metal filler, inner rings for densification of the displacer rod with valve devices in the form of spring-loaded balls with small diameter holes in the body of the balls installed in the conical holes of the cover, which is attached to the upper end of the piston body using fixing bolts.

 The introduction into the composition of the working piston of dynamic sealing assemblies in the form of stops, corrugated plates of material with shape memory, external and internal sealing rings, valve devices allows to obtain a new property, which consists in the possibility of moving the external and internal sealing rings (leading to a change in the gap between the inner surface cylinder and the outer o-ring, the gap between the inner o-rings and the surface of the displacer rod) due to changes in temperature in mkostyah dynamic sealing nodes in the start-up and release during the chiller to the operating mode.

 The drawing shows a gas chiller with a working piston having elements with shape memory.

 The gas refrigerating machine comprises a working piston body 1 with a figured upper end, a cover 2 forming containers 3 and 4 with the body 1, in which dynamic sealing assemblies are installed, consisting of stops 5, 6, 7, 8, corrugated plates 9 and 10, previously compressed, from a material with shape memory, an external sealing ring 11 with a tip made of metal filler 12 for sealing the inner surface of the cylinder 13, internal sealing rings 14 for sealing the rod of the displacer 15, valve devices 16, 17 installed in nusnyh cover holes 2 made in the form of spring-loaded balls in the body which have small diameter holes for the return gas passage. In the body of the cover 2, holes are made for the passage of the fixing bolts 18, which press the cover 2 against the piston body 1, for which holes with thread are made in the body 1. O-rings 11 and 14 are made of elastic elastic material. Between the stem of the displacer 15 and the piston housing 1 is a locking sleeve 13. The stops 6 and 7 have openings for the passage of the working gas into the area under the corrugated plates 9 and 10.

 The device operates as follows.

 In the initial position, there is a gap between the outer sealing ring of the piston 11 and the inner surface of the cylinder 13, which allows part of the working gas to be bypassed from the compression cavity into the crankcase, the inner sealing rings 14 are not tight against the surface of the displacer rod 15. When starting the engine, the working gas partially compressed in the compression cavity It is displaced into the crankcase due to the pressure drop through the gaps, creating a decompression condition for the initial period of operation of the refrigeration machine. Another part of the gas also passes through the valve devices 16 and 17 in the tanks 3 and 4 due to the difference, increasing the pressure in it. The increase in pressure is accompanied by an increase in temperature, which leads to heating of the pre-compressed corrugated plates 9 and 10, an increase in the length of the plates due to the shape memory effect, and, as a consequence, the movement of the outer sealing ring 11 towards the inner surface of the cylinder 13, causing a decrease in the gap between them and the movement of the inner rings 14 to the surface of the rod of the displacer 15, forming an effective seal of the rod of the displacer 15. Work in this mode occurs until the extension rings are tight e nestle against the inner surface of the cylinder 13 and the surface of the displacer rod 15, thereby compressing the encapsulation cavity from the crankcase and the pressure in the tanks 3 and 4 becomes equal to the pressure in the compression chamber. By this time, the chiller is operating. When the engine is stopped, gas from tanks 3 and 4 due to the pressure drop in it and the working volumes flows through a small diameter hole in the body of the balls of the valve devices 16 and 17 into the working volume of the machine. A decrease in pressure will cause a decrease in temperature, which will lead to the adoption of corrugated plates of the same length. The elastically stretched sealing rings 11, 14 due to the reverse action of the tensile forces move to the center of the piston, forming the necessary clearance with the inner surface of the cylinder 13 and the rod 15, for subsequent start-up.

Claims (1)

 Gas chiller with a working piston having elements with shape memory operating according to the Stirling cycle, including compression, expansion and crankcase cavities, a working piston, a displacer, a regenerator, heat exchangers, characterized in that tanks for installation are made in the upper part of the working piston body dynamic sealing assemblies containing elastic sealing rings, stops and plates, made of materials with shape memory, valve devices located in the piston cover, allowing gas bypass in both directions phenomena.