US3285142A - Piston type cryogenic apparatus - Google Patents

Piston type cryogenic apparatus Download PDF

Info

Publication number
US3285142A
US3285142A US357401A US35740164A US3285142A US 3285142 A US3285142 A US 3285142A US 357401 A US357401 A US 357401A US 35740164 A US35740164 A US 35740164A US 3285142 A US3285142 A US 3285142A
Authority
US
United States
Prior art keywords
piston
cylinder
gas
grooves
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US357401A
Other languages
English (en)
Inventor
Doll Robert
Eder Franz Xaver
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Application granted granted Critical
Publication of US3285142A publication Critical patent/US3285142A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/06—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using expanders

Definitions

  • This invention relates generally to cryogenic apparatus and more particularly is concerned with such apparatus using a piston reciprocating in a suitable cylinder, there being annular grooves provided on the bearing surfaces of the piston or cylinder and gas under high pressure flowing in the clearance space between the piston and cylinder.
  • cryogenic apparatus of the character with which this invention is concerned, a working gas is expanded approximately adiabatically from high to low pressure by producing mechanical work, the gas being thereby cooled.
  • Such apparatus are of two types, namely, expansion turbines and expansion piston machines, both being used to produce low temperatures, particularly in the liquefying of gases which have low boiling points, and without pre-cooling through the use of other liquefied gases having higher boiling points. Examples of such gases which require cooling for liquefying are neon, hydrogen and helium. Since expansion turbines can generally effectively process large quantities of gas and low pressure ratios, only expansion machines of the reciprocating piston type are used for medium to small liquefying and gas cooling installations.
  • the working piston is provided with annular grooves on its surface and the clearance volume between the piston and the cylinder surface is of right cylindrical configuration, that is, the juxtaposed surfaces are co-parallel with the theoretical distance between them parallel throughout.
  • This clearance volume in prior devices has not been of equal dimension on opposite sides of the piston, as will be seen.
  • the clearance volume will hereinafter be called the space between the piston and the inner cylinder surface.
  • the annular grooves had two function, one-to improve the pressure seal of the working chamber from the outer chamber, and,-twoto equalize the pressure around the circumference of the piston.
  • prior cryogenic apparatus of the piston type could be operated only at low speeds, and even then wear on the bearing surfaces was unavoidable.
  • the invention herein has as its most important objects the elimination of the above disadvantages and the provision of a piston type cryogenic apparatus in which the piston reciprocates in a fully floating condition without contacting the surfaces of the cylinder so that the piston may be operated at high speed and without substantially any wear on the moving parts thereof.
  • Still a further object of the invention is to provide a piston type cryogenic apparatus in which the construction and control thereof are considerably simplified over prior devices through the elimination of valve mechanisms having moving parts.
  • Another object of the invention is to provide apparatus of the character described in which a floating stroke of the piston is achieved by means of gas lubrication, there being a plurality of annular grooves along the length of the working surface of the piston or the cylinder, and the grooves being of such axial distance apart and the clearance space between the piston and wall being of such configuration as to achieve the desired floating effect, irrespective of the direction of flow of the gas.
  • Still another object of the invention is to provide a piston type cryogenic apparatus in which the valve gear is eliminated by providing suitable inlet and outlet chambers in the cylinder itself and means in the piston for operating the same for achieving the introduction, expansion and expulsion of the gas.
  • the piston or the cylinder of the apparatus is provided on its walls with fine annular grooves spaced along the length of the working surface, the axial distance between adjacent grooves being between l and the circumference of the piston, and the surface of the piston or cylinder is so formed that the radial clearance space varies, being different dimensions axially along the length of the piston between any two adjacent grooves.
  • the invention is further character pied by the provision of means in the piston itself to enable the same to function as a control valve, inlet and outlet ports and chambers being formed in the bearing surface of the cylinder.
  • FIG. 1 is a fragmentary diagrammatic view on a greatly exaggerated scale showing one side of the radial clearance space between a piston and cylinder constructed in accordance with the invention.
  • FIG. 2 is a pressure diagram illustrating the flow conditions in the clearance space of FIG. 1, the principal points of pressure being aligned for discussion.
  • FIG. 3 is a fragmentary schematic and diagrammatic I view of a piston and cylinder constructed in accordance with the invention, specifically the structure of FIG. 1.
  • FIG. 4 is a view similar to that of FIG. 3, but illustrating a modified form of the invention.
  • FIG. 5 is a pressure diagram similar to that of FIG. 2 but related in this case to the construction of FIG. 4.
  • FIG. 6 is a schematic vertical sectional view through a cylinder and piston unit of a cryogenic machine constructed in accordance with the invention, the grooves and clearance space not being shown in this view because of the practical problems of illustrating the same.
  • FIG. 7 is a schematic vertical sectional view through a modified form of cylinder and piston unit.
  • FIG. 8 is a fragmentary schematic vertical sectional view of a modified form of the invention in which there i is an adjustable bottom plug in the cylinder.
  • FIG. 9 is a chart illustrating the relative values of pressure and volume in the working cycle of the apparatus of the invention.
  • FIG. 1 a fragment is shown of a piston and cylinder unit constructed in acco'mpressible medium in the isotherrnic case.
  • cordance with the invention the view being sectional and taken at one side of the piston. It will be appreciated that the dimensions are greatly exaggerated to aid in the explanation, since the radial distance between the piston and the cylinder wall is'a few microns.
  • the cylinder is designated 1
  • the piston 2 and 3 and 4 are two successiv annular grooves.
  • the direction of flow of the gas is designated by the arrow and the space between the piston and inner surface of the cylinder is designated s.
  • this space varies substantially uniformly, decreasing in the direction of flow, so that there is a change in pressure along the length ofthe piston.
  • This arrange- ;ment of decrease in clearance space may be provided overall or part of the piston (or the cylinder surface).
  • the gas pressure p in the annular groove 3 is higher than the gas pressure p" in the annular groove 4.
  • Equation 1 shows, the pressure distribution between two annular grooves in the case of a clearance space which is uniform, i.e., parallel, does not .depend upon the radial .distance of the space itself, so long as the latter remains so small that the conditions under which Equation 1 has been derived are met.
  • FIG. 3 shows in exaggerated scheand' throttling clearance spaces between the annular grooves whose radial dimension decreases in the direction of gas flow. A stabilizing effect by the gas flowing in the clearance Space is achieved to provide the self-' If it ,matic diagram, a piston 2 constructed according to the. invention and having the annular grooves 3, 4, 5, 6
  • the pressure distribution on the narrow clearance side of the piston will be substantially different, therefore, than on the wider clearance side, considering of course the distribution along the axial length of the piston between annular grooves. This difference will increase as the piston and cylinder approach one another on the narrow side, and the distribution is like the solid line curve of FIG. 2. Because. of this, there is a higher mean static gas pressure on the narrow clearance side than there is on the wider clearance side, and consequently a resultant force is exerted by the gas which tends to force the piston into a perfectly concentric position within the cylinder.
  • the mean static gas pressure is expressed as follows:
  • the annular grooves on the piston circumference have the function of-maintaining the same outlet and end pressure at all points of the circumference for gas flow in the wedge shaped clearance space between grooves.
  • the dilferent pressure distribution around the circumference of the piston when eccentric can be equalized by the flow of gas around the piston.
  • a sufliciently close spacing of the grooves may result in the creation of a greater resistance to flow in the clearance space along the circumference than the flow from groove to groove.
  • the gas under these circumstances would flow mainly in an axial direction between the annular grooves and the tangential or circumferential fiow would be of little substantial consequence.
  • this distance should be between and of the piston circumference.
  • FIG. 5 is a chart showing qualitativelythe pressure 1 distribution along the axial length of the clearance space for the flow in the direction of increasing 1, (from the bottorn to the top).
  • the dashed line curve represents the pressure distribution for a clearance space of uniform, that is, parallel, radial dimension.
  • the solidline curve represents qualitatively the pressure distribution for the profile shown in FIG. 4. The explanation of this curve is as follows: At the start (bottom) there is a great pressure drop due to the narrow clearance dimensionat this point, followed by a region of relatively low pressure drop because of the wide clearance dimension, and finally another 'high pressure drop at the end because of the narrow radial clearance dimension.
  • FIGS. 6 to 8 there are illustrated diagrammatic views of piston type cryogenic machines constructed in accordance with the invention as described above, but including additional novel features which result in simple and highly efiicient apparatus.
  • a cylinder 10 with a reciprocating piston 11 arranged to move therein and perform work during the expansion of the working gas.
  • the piston is preferably coupled with a connecting rod 12 which can perform the work upon some external instrumentality (not shown).
  • the cylinder and piston 11 define the chamber 13 which will be filled by the incoming gas.
  • the cylinder 10, according to the invention, is provided in the axial range of the stroke of the piston, with an annular groove 14 connected by several radial passageways 15 circumferentially spaced about the cylinder with an annular enclosed gallery 16 connected to a high pressure source of the Working gas (not illustrated) through a conduit 17. Adjacent lower dead center of the piston movement an annular groove 18 is formed in the piston connected by radially and downwardly extending channels 19 spaced circumferentially about the piston to a central axially extending bore 20.
  • the bottom end 21 of the piston uncovers an annular groove 22 formed in the cylinder wall, and the expanded, cooled gas escapes through a plurality of radial passageways 23 into the annular gallery 24 and thence passes by way of the conduit 25 to the means for re-cycling the gas (not shown).
  • the ratio of incoming charge volume to terminal volume is chosen so that the pressure p in the chamber 13 is greater at the end of the expansion portion of the cycle than the counter pressure 17 in the exhaust gas line 25.
  • the central axial bore 20 is advantageous in that the piston 11 is interiorly scavenged by cold gas. This is important during the cooling period, since the coefficient of expansion of the piston and cylinder are relatively great in the range of room temperature, so that it is essential that they both cool simultaneously. If this were not achieved, the cylinder would cool faster than the piston and contract to seize the piston.
  • Regulation of the intake and exhaust volume ratio can be effected by the arrangement shown in FIG. 8.
  • a piston-like plug 26 fitted into the bottom of the cylinder, its position being adjusted by a threaded adjusting screw 27 axially engaged through an end cap 30 or extension secured to the cylinder.
  • a bellows 28 ensures against escape of gas through the extension 30 or screw 27.
  • the volume of the chamber 13 can be varied continually during operation. Any gas which bleeds through the clearance space between the cylinder and the plug 26 is returned to the exhaust gas gallery 24 through a line 29.
  • the piston bottom and cylinder bottom are preferably covered with a layer of heat insulating material.
  • cryogenic apparatus Although primarily developed and best suited for use with cryogenic apparatus, the invention is likewise applicable to machines and apparatus where a piston is required to reciprocate in a cylinder and oil lubrication cannot be used.
  • a machine which includes a piston reciprocating in a cylinder, and in which a gas under high pressure flows through the clearance space between the piston and the inner surface of the cylinder; means for eifccting a selfcentering action of the piston to maintain the same concentric with the cylinder without contact with the cylinder walls during reciprocation, comprising a plurality of annular grooves formed in one of the piston and cylinder surfaces, axially spaced along the length thereof, the intervening clearance space defined by the piston and cylinder surfaces between adjacent grooves varying axially in radial dimension.
  • a reciprocating piston machine having a cylinder and a piston moving relative one another, inlet and exhaust means for admitting gas into the cylinder to expand for driving the piston in one direction, said inlet and exhaust means being located along the length of stroke of the piston to always provide a diiferential gas pressure along a portion of the cylinder occupied by the piston, a clearance space between the piston and cylinder comprised of a plurality of annular grooves formed between the piston and cylinder separated by radial dimension clearances axially varying of such construction to cause a self-centering action of the piston during reciprocation.
  • a machine as claimed in claim 8 in which the grooves are in at least a portion of the length of the .piston, are separated by a distance which is substantially less than the circumference of the piston, and in which the radial clearance dimension between grooves varies along the axial lengthof the piston.
  • inlet and outlet means include pasageways opening to the inside of the cylinder, a cooperating annular groove in the piston adapted during reciprocation to cover and uncover the first mentioned passageways and passage means through the interior of the piston from said annular groove to the piston end.
  • a machine a claimed in claim 8 in 'which there is an expansion chamber in one end of the cylinder, the inlet means is adapted to have said "gas enter tinder pressure-and leave in expanded condition, and in which the inlet and exhaust means are formed by recesses circum ferentially disposed about the cylinder and opening to the bearing surface thereof.
  • a machine as claimed in claim 12 in which the piston has a bore connecting with an annular groove therein, and located relative to said recesses to admit gas during a short portion of the stroke in the vicinity of lower dead center of the piston, and release the expanded gas from the bottom of the piston when the end uncovers the exhaust means in the vicinity of the lower dead center of the piston.
  • a piston type cryogenic device which comprises a cylinder having a cylindrical chamber therein, a piston arranged to reciprocate in the chamber and convert the heat from expanding gas into work while cooling the gas, a link connected with the piston and extending out of the cylinder adapted to have a work absorbing apparatus coupled therewith, a plurality of grooves spaced along the length of at least a portion of the piston, the diameter of the piston being such relative to the diameter of he chamber to provide a clearance space of very small dimensions, the piston having a profile between grooves to produce a radial dimension of the clearance space which varies in an axial direction, and said radial dimension being substantially greater between grooves than adjacent at least one of the grooves, the grooves being spaced axially by a dimension which is between and V the piston circumference, inlet and exhaust means for gas to be admitted into said cylinder at high pressure and exhausted after cooling, the piston stroke, dimensions of the chamber and the pressures being chosen so that there is always a diilerential pressure along the length of the piston whereby to
  • a piston type cryogenic device which comprises a cylinder having a cylindrical chamber therein, a piston arranged to reciprocate in the chamber and convert the heat from expanding gas into work While cooling the gas, a link connected with the piston and extending out of the cylinder adapted to have a work absorbing apparatus coupled therewith, a plurality of grooves spaced along the length of at least a portion of the piston, the diameter of the piston being such relative to the diameter of the chamber to provide a clearance space of very small dimensions, the piston having a profile between grooves to produce a radial dimension of the clearance space which varies in an axial direction, and said radial dimension being substantially greater between grooves than adjacent at least one of the grooves, the cylinder having first passage means formed therein opening to said chamber to permit the introduction of gas at a relatively high presure into the chamber While the piston is atapproximately one end of its stroke, the expansion of the gas adapted to drive the piston in the opposite direction, with the piston having valving means for cutting off the first passage means shortly after the piston
  • said valving means of the piston comprise an annular recess in the piston, a central bore in the piston connecting With said recess and the piston end and said piston end, the latter serving to uncover said second passageway.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)
US357401A 1963-04-10 1964-04-06 Piston type cryogenic apparatus Expired - Lifetime US3285142A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DED0041347 1963-04-10

Publications (1)

Publication Number Publication Date
US3285142A true US3285142A (en) 1966-11-15

Family

ID=7046047

Family Applications (1)

Application Number Title Priority Date Filing Date
US357401A Expired - Lifetime US3285142A (en) 1963-04-10 1964-04-06 Piston type cryogenic apparatus

Country Status (5)

Country Link
US (1) US3285142A (de)
CH (1) CH443371A (de)
DE (1) DE1426943A1 (de)
GB (1) GB1043295A (de)
NL (1) NL6403818A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3640845A (en) * 1968-07-09 1972-02-08 Atomic Energy Commission Dynamic seal
US4711153A (en) * 1986-12-15 1987-12-08 General Electric Company Seal
WO2018183895A1 (en) 2017-03-30 2018-10-04 Quest Engines, LLC Piston sealing system
CN110678639A (zh) * 2017-03-30 2020-01-10 奎斯特发动机有限责任公司 活塞密封系统

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4545738A (en) * 1984-02-03 1985-10-08 Helix Technology Corporation Linear motor compressor with clearance seals and gas bearings
WO2000029793A1 (de) * 1998-11-18 2000-05-25 FKW HANNOVER Forschungszentrum für Kältetechnik und Wärmepumpen GmbH Kolbenverdichter

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1835790A (en) * 1927-12-02 1931-12-08 Phelps Dodge Corp Feed control for furnaces
US2291243A (en) * 1939-04-27 1942-07-28 Siam Pneumatic remote controlled release
US2833602A (en) * 1954-03-26 1958-05-06 Thompson Prod Inc Self-centering piston
US3032017A (en) * 1958-07-21 1962-05-01 Joseph F Pollauf Hydraulic elevators
US3035879A (en) * 1958-03-14 1962-05-22 Sulzer Ag Means for centering the piston of a piston compressor
US3058450A (en) * 1959-06-25 1962-10-16 Lissau Frederic Hydraulic positioning servo system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1835790A (en) * 1927-12-02 1931-12-08 Phelps Dodge Corp Feed control for furnaces
US2291243A (en) * 1939-04-27 1942-07-28 Siam Pneumatic remote controlled release
US2833602A (en) * 1954-03-26 1958-05-06 Thompson Prod Inc Self-centering piston
US3035879A (en) * 1958-03-14 1962-05-22 Sulzer Ag Means for centering the piston of a piston compressor
US3032017A (en) * 1958-07-21 1962-05-01 Joseph F Pollauf Hydraulic elevators
US3058450A (en) * 1959-06-25 1962-10-16 Lissau Frederic Hydraulic positioning servo system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3640845A (en) * 1968-07-09 1972-02-08 Atomic Energy Commission Dynamic seal
US4711153A (en) * 1986-12-15 1987-12-08 General Electric Company Seal
WO2018183895A1 (en) 2017-03-30 2018-10-04 Quest Engines, LLC Piston sealing system
CN110678639A (zh) * 2017-03-30 2020-01-10 奎斯特发动机有限责任公司 活塞密封系统
EP3601774A4 (de) * 2017-03-30 2021-01-06 Quest Engines, LLC Kolbendichtungssystem
CN110678639B (zh) * 2017-03-30 2021-08-13 奎斯特发动机有限责任公司 活塞密封系统

Also Published As

Publication number Publication date
CH443371A (de) 1967-09-15
GB1043295A (en) 1966-09-21
DE1426943A1 (de) 1969-04-03
NL6403818A (de) 1964-10-12

Similar Documents

Publication Publication Date Title
US3035879A (en) Means for centering the piston of a piston compressor
US3733837A (en) Thermodynamic reciprocating machine
US3175645A (en) Shock absorber with primary and secondary damping chambers
US3333513A (en) Guide arrangement for pistons and cylinders
US3285142A (en) Piston type cryogenic apparatus
US3653303A (en) Guide means for a piston in a cylinder
US2790462A (en) Accumulators
GB1313392A (en) Device comprising two coaxial elements of which one is reciprocable within the other
GB1188984A (en) Improvements in or relating to Apparatus for Converting Mechanical Energy into Heat Energy or vice versa.
US4305741A (en) Cryogenic apparatus
US4310337A (en) Cryogenic apparatus
US3045447A (en) Rotary device, such as refrigerating machine or similar device
US4296675A (en) Cylinder cushion with contractable ring
US3538815A (en) Reciprocating piston engine
US3292501A (en) Device including at least one cylinder with a piston-shaped body which is movable therein
US3863676A (en) Piston type accumulator
US3667349A (en) Seal for piston-cylinder assembly
US4543792A (en) Refrigeration system with clearance seals
US5125325A (en) Piston with cushioning spear having exhaust ports therein
RU2037704C1 (ru) Радиально-торцевое контактное уплотнение
US3137439A (en) Centering the piston of a piston compressor
US3333433A (en) Closed cycle cryogenic refrigerator
US3270626A (en) Fluid-powered linear actuators
GB1313393A (en) Piston-and-cylinder device having a rolling-diaphragm seal
US3362340A (en) Three-area vane type pressure energy translating device having shock absorbing valve means