WO1995002750A1 - Ensemble palier de tige de piston d'un moteur a piston alternatif - Google Patents

Ensemble palier de tige de piston d'un moteur a piston alternatif Download PDF

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Publication number
WO1995002750A1
WO1995002750A1 PCT/GB1994/001552 GB9401552W WO9502750A1 WO 1995002750 A1 WO1995002750 A1 WO 1995002750A1 GB 9401552 W GB9401552 W GB 9401552W WO 9502750 A1 WO9502750 A1 WO 9502750A1
Authority
WO
WIPO (PCT)
Prior art keywords
piston
piston rod
cylinder
balls
bearing assembly
Prior art date
Application number
PCT/GB1994/001552
Other languages
English (en)
Inventor
John Varga
Original Assignee
Carding Specialists (Canada) Limited
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 Carding Specialists (Canada) Limited filed Critical Carding Specialists (Canada) Limited
Publication of WO1995002750A1 publication Critical patent/WO1995002750A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/14—Pistons, piston-rods or piston-rod connections
    • F04B53/144—Adaptation of piston-rods
    • F04B53/146—Piston-rod guiding arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B11/00—Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type
    • F01B11/001—Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type in which the movement in the two directions is obtained by one double acting piston motor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C31/00—Bearings for parts which both rotate and move linearly
    • F16C31/04—Ball or roller bearings

Definitions

  • This invention relates to a bearing assembly for a piston rod of a linearly reciprocating piston type engine.
  • the type of linearly reciprocating piston engine with which the invention is concerned has a cylinder, a piston movable axially in said cylinder, at least one piston rod secured to and projecting from one side of the piston, said piston rod extending axially of the piston and being movable with the piston in a fixed plane parallel to the axis of the cylinder, a cover closing one end of the cylinder and facing said one side of the piston, and an opening formed in said cover through which the piston rod extends.
  • the piston will have a pair of piston rods, each extending axially outwardly of a respective one of the opposed working faces of the piston.
  • the invention has been developed primarily in connection with a reciprocating piston type compressor having a "floating" piston, though it should be understood that the invention may be applied to other forms of reciprocating piston type engine which require mechanical power input in order to do mechanical work e.g. to pressurise a working fluid as in a pump or compressor, or which are energised by a pressurised working fluid in order to generate mechanical power e.g. an air motor.
  • the invention seeks to reverse this trend, and to overcome perceived drawbacks to the use of linearly reciprocating piston type compressors.
  • the balls are arranged in an annular array between two coaxial annular surfaces, in which the inner annular surface is formed by the cylindrical periphery of the shaft and the outer annular surface is formed by a fixed sleeve or bush which is normally rigidly secured against the internal wall of the opening in which the bearing is mounted.
  • Grease or oil is normally contained within the annular space in which the balls are arranged, and lubricate the rotation of the balls. While the balls are rotating, a film of lubricant builds-up at the interfaces between the instantaneous surfaces of contact of the balls and the inner and outer annular surfaces. However, each time the shaft reverses its linear movement, there is a "dwell period" in which the rotation of the balls is arrested (prior to rotation in a reverse direction) and this tends to break down the lubricant film and allow direct metal to metal contact which is a source of wear and heat which, over a period of time, results in unacceptable wear and breakdown.
  • the invention seeks, by simple means, to improve the lubrication of the bearings in the bearing assembly for a piston rod of a reciprocating piston type of engine of the type defined above.
  • a linearly reciprocating piston engine comprising: a cylinder; a piston movable axially in said cylinder; a piston rod secured to and projecting from one side of the piston, said piston rod extending parallel to the axis of the piston and being movable with the piston in a fixed plane parallel to the axis of the cylinder; a cover closing one end of the cylinder and facing said one side of the piston; an opening formed in said cover through which the piston rod extends; and, a bearing assembly mounted in said opening and arranged to guide the linear reciprocating movement of the piston rod, said bearing assembly comprising an annular array of balls surrounding and making contact with the cylindrical periphery of the piston rod, and housing in which the balls are received; and, means for applying rotation to the balls about respective axes extending generally parallel to the axis of the piston rod.
  • the balls rotate about respective axes extending perpendicular to the axis of the piston rod, by reason of linear reciprocation of the piston rod, but also carry out further rotation about axes extending parallel to the axis of the piston rod. Therefore, even when the rod is reversing its reciprocation (which in known constructions would arrest the rotation of the balls), the balls continue to rotate about their axes which extend parallel to the rod axis (under action of said rotation applying means) so that lubrication of the balls can be maintained at all stages of reciprocation of the piston rod.
  • the bearing assembly comprises an annular array of balls surrounding and making contact with the cylindrical periphery of the piston rod; a sleeve radially spaced from the axis of the piston rod to define an annular space in which the array of balls is housed; means rotatably mounting the sleeve in the opening in the cover; and means for applying rotation to the sleeve about the axis of the piston rod during linear reciprocation of the latter.
  • grease or oil provided as lubricant can maintain a protective lubricant film between the interfaces of both the inner and outer annular surfaces on which the balls rotate, thereby reducing wear, and providing more reliable operation.
  • the means by which the sleeve is rotatably mounted in the cover opening through which the piston rod extends may take any convenient form, which may be, for example, a further annular array of bearing balls. However, other arrangements may be provided, which allows the sleeve to rotate about the axis of the piston rod during operation.
  • the invention is applied to a reciprocating piston type compressor having a "floating piston", and which will have a pair of oppositely projecting piston rods, each secured to a respective one of the opposed working faces of the piston, and extending through a mounting opening in a corresponding cover end plate of the housing.
  • the piston rods guide the movement of the piston so that the piston does not normally engage the side wall of the cylinder, which avoids necessity for piston seals, and provides substantially friction-free movement of the piston.
  • a small proportion of gas can leak from one side of the piston to the other side (via the radial clearance between piston and cylinder wall), but this can be tolerated for many applications in view of the considerably enhanced service life and reduced maintenance costs of a friction-free movement of the piston and absence of piston seals.
  • a reciprocating piston type compressor having a cylinder, a piston mounted for linear reciprocation in said cylinder substantially without guidance of sliding contact with the inner wall of the cylinder, at least one piston rod rigidly secured to the piston, and a bearing assembly provided in one end of said cylinder and which slidably receives said piston rod so as to guide the reciprocating movement of the piston.
  • a pair of piston rods is provided, each rigidly secured to a respective end face of the piston, and mounted slidably in a respective bearing assembly.
  • Figure 1 is a schematic illustration of a linearly reciprocating piston type engine according to the invention, but in which bearing housings through which the piston rods extend are omitted for clarity;
  • Figure 2 is a schematic illustration of one of the bearing housings.
  • linearly reciprocating piston engine having a "floating piston" which is intended primarily for use as a high pressure or low pressure air compressor.
  • the engine is designated generally by reference 10 and has a cylinder 11, a floating piston 12 movable axially in the cylinder 11, and at least one piston rod secured to and projecting axially from one side of the piston.
  • a pair of oppositely extending piston rods 13 will usually be provided, each being secured to and projecting from a respective one of the two opposed working sides or faces 14 of the piston.
  • Each piston rod 13 extends axially of the piston and is movable with the piston in a fixed plane parallel to the axis of the cylinder, and when the rods 13 are centrally mounted, as shown, this plane of movement will contain the longitudinal axis of the cylinder 11.
  • Piston rods 13 are rigidly secured to the piston 12, unlike the connection of a piston rod in an internal combustion engine, so as to provide guidance for the movement of the piston 12 without need to engage the wall of cylinder 11.
  • a cover 15 closes each end of the cylinder, and each faces a respective one of the opposed sides 14 of the piston. Further, as shown in Figure 1, a mounting opening 16 is formed in each cover 15 through which a respective piston rod 13 extends .
  • a respective bearing assembly shown by reference 17 in Figure 2, is mounted in each mounting opening 16 and guide the movement of the piston / piston rod assembly, and comprises an inner annular array of balls 18 (of one or more rows) which roll on the cylindrical outer surface of piston rod 13 during its reciprocation, and which are housed in an annular space defined between the cylindrical outer surface of each rod 13 and a bearing housing formed by a sleeve or bush 19.
  • Bush 19 is rotatably mounted in opening 16 in cover 15 by any suitable rotary support, which is shown schematically by two outer annular arrays of bearings 20.
  • the bearings 20 also prevent the bush 19 from rocking during reciprocation of rod 13.
  • means (not shown) locates the bush 19 against axial displacement.
  • a rigid assembly is obtained by interference fit in the opening 16 to provide radial loading of all engaging parts .
  • Balls 18 may be "caged", as shown schematically by reference 22, to be retained against relative axial displacement. Stops 23 limit the axial movement of balls 18, and also form a means of aligning the balls at the end of each reciprocation of the piston 12 (if cage 22 is omitted).
  • Grease or oil will be contained in the annular space in which the bearings 18 are housed, and this provides lubrication between the instantaneous contact interfaces between the rotating balls 18 and the cylindrical surface of rod 13 (or a wear sleeve mounted on rod 13) and the cylindrical inner wall of bush 19.
  • Linear reciprocation of the piston rod 13 causes the balls 18 to rotate about their axes, and thereby guide in a smooth and lov; friction manner the axial reciprocation of the piston rod 13.
  • an improved means is provided to maintain lubrication of the contact surfaces at this critical point in each linear reciprocating cycle.
  • a hydrodynamic lubricating effect is maintained for as long as the balls 18 are rotating, and the invention provides a means whereby the balls 18 can be caused to continue to rotate, even at the critical point of reversal of linear movement of the piston rod 13.
  • bush 19 is rotatably mounted in the mounting opening 16, and in addition means is provided (not shown) to apply continuous rotation to the bush 19 about the axis 21 of the piston rod i3. The balls therefore continue to rotate, at all stages during the linear reciprocation of the piston rods 13, and this provides improved retention of lubricant film which builds-up at the contact interfaces.
  • a speed of rotation of sleeve 19 of about 100 rpm is suitable.
  • the bush 19 may be rotated whenever the piston rod 13 is approaching the end of its linear movement in one direction and / or is commencing its return path of movement, but in practice it will be generally more convenient to provide a more continuous rotary drive to bush 19 during operation of the engine.
  • Suitable seals will be provided to provide some form of sealing to the mounting assembly of each piston rod 13, though in the case of a compressor a limited amount of air leakage through opening 16 can be tolerated.
  • a stepped arrangement (not shown) of cover 15 may approach the surface of rod 13 more closely to provide improved sealing.
  • Suitable inlet and outlet valves will be provided (not shown) to control induction of air to be compressed during the induction stroke, and exhaust of compressed air during the compression stroke.
  • the engine operates as a double acting cylinder.
  • novel aspects of the bearing assembly disclosed herein (which are particularly suitable in providing substantially wear-free guidance of a floating area-sealed piston of a compressor) may be applied in other types of linearly reciprocating piston engines, including air motors.
  • the preferred embodiment has a bearing assembly in which the sleeve 19 forms a housing in which the balls 20 are received, and which applies rotation to the balls about axes extending parallel to the axis of the piston rod 13 (whereas linear reciprocation of the rod rotates the balls about axes which extend perpendicular to the axis of the rod).
  • the preferred embodiment of the invention provides an oil-free, floating piston type of reciprocating compressor working at pressures for industrial usage (up to 9 atmospheres). It has the advantage of high efficiency, both when compressing and when running unloaded. There is no wear between piston and cylinder, and low maintenance by reason of absence of piston seals. Further, the bearing assemblies provide much reduced friction and wear. It can be operated with a supercharger if required. The simplicity of design, reduced wear, and reduction of friction enable the compressor to be competitively priced relative to rotary compressors.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Compressor (AREA)

Abstract

Ensemble palier pour une tige de piston d'un moteur du type à piston à mouvement alternatif linéaire, tel qu'un compresseur du type à piston flottant, comprenant un cylindre (11), un piston flottant (12) mobile dans le sens axial dans le cylindre (11), et au moins une tige (13) de piston fixée au piston et faisant saillie fans le sens axial à partir d'un côté du piston de façon à être reçu dans un ensemble palier respectif (17) situés à une extrémité du cylindre et qui guide le déplacement de l'ensemble piston/tige de piston, ledit ensemble palier comprenant: un alignement interne et annulaire de billes (18) qui roulent sur la surface externe cylindrique de la tige (13) de piston au cours de son mouvement alternatif, et qui sont logées dans un espace annulaire défini entre la surface externe cylindrique de la tige (13) et un manchon (19); des paliers (20) sur lesquels est monté rotatif le manchon (19); ainsi que des moyens permettant de mettre le manchon (19) en rotation autour de l'axe de la tige (13) de piston au cours du mouvement alternatif linéaire de cette tige, afin de réduire l'usure produite sur les billes en maintenant la lubrification de ces dernières, et de permettre ainsi un fonctionnement plus fiable.
PCT/GB1994/001552 1993-07-17 1994-07-18 Ensemble palier de tige de piston d'un moteur a piston alternatif WO1995002750A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB939314957A GB9314957D0 (en) 1993-07-17 1993-07-17 Piston rod bearing assembly of reciprocating piston engine
GB9314957.3 1993-07-17

Publications (1)

Publication Number Publication Date
WO1995002750A1 true WO1995002750A1 (fr) 1995-01-26

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1994/001552 WO1995002750A1 (fr) 1993-07-17 1994-07-18 Ensemble palier de tige de piston d'un moteur a piston alternatif

Country Status (2)

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GB (1) GB9314957D0 (fr)
WO (1) WO1995002750A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996022473A1 (fr) * 1995-01-19 1996-07-25 Carding Specialists (Canada) Limited Ensemble roulement de tige de piston destine a un moteur a pistons alternatifs
CN105377443A (zh) * 2013-07-19 2016-03-02 格瑞克明尼苏达有限公司 用于喷射系统的配料缸

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR576073A (fr) * 1924-08-11
US2647807A (en) * 1951-06-30 1953-08-04 Standard Oil Co Nonfretting antifriction bearing
GB901231A (en) * 1960-02-20 1962-07-18 Rotolin Bearings Ltd Improvements relating to rectilinear-motion bearings
FR1575079A (fr) * 1968-07-22 1969-07-18
GB1193466A (en) * 1967-08-12 1970-06-03 Rotolin Bearings Ltd Guides for Die Sets
BE782267A (fr) * 1972-04-18 1972-10-18 Roosen Jean E J Dispositif pouvant servir de verin ou de pompe, hydraulique ou pneumatique.
DE2327140A1 (de) * 1973-05-28 1974-12-19 Helmut John Verschieblicher rotationskolben fuer unterwasserpumpen, u.a
DE2823667A1 (de) * 1978-05-31 1979-12-06 Erich Roser Druckluftmotor
EP0223288A1 (fr) * 1985-11-06 1987-05-27 Koninklijke Philips Electronics N.V. Dispositif comprenant un piston alternatif et rotatif à effet hydrodynamique
US5141337A (en) * 1991-12-06 1992-08-25 Hanaway Ronald L Guide post, guide sleeve and air impulse rotary ball cage

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR576073A (fr) * 1924-08-11
US2647807A (en) * 1951-06-30 1953-08-04 Standard Oil Co Nonfretting antifriction bearing
GB901231A (en) * 1960-02-20 1962-07-18 Rotolin Bearings Ltd Improvements relating to rectilinear-motion bearings
GB1193466A (en) * 1967-08-12 1970-06-03 Rotolin Bearings Ltd Guides for Die Sets
FR1575079A (fr) * 1968-07-22 1969-07-18
BE782267A (fr) * 1972-04-18 1972-10-18 Roosen Jean E J Dispositif pouvant servir de verin ou de pompe, hydraulique ou pneumatique.
DE2327140A1 (de) * 1973-05-28 1974-12-19 Helmut John Verschieblicher rotationskolben fuer unterwasserpumpen, u.a
DE2823667A1 (de) * 1978-05-31 1979-12-06 Erich Roser Druckluftmotor
EP0223288A1 (fr) * 1985-11-06 1987-05-27 Koninklijke Philips Electronics N.V. Dispositif comprenant un piston alternatif et rotatif à effet hydrodynamique
US5141337A (en) * 1991-12-06 1992-08-25 Hanaway Ronald L Guide post, guide sleeve and air impulse rotary ball cage

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996022473A1 (fr) * 1995-01-19 1996-07-25 Carding Specialists (Canada) Limited Ensemble roulement de tige de piston destine a un moteur a pistons alternatifs
CN105377443A (zh) * 2013-07-19 2016-03-02 格瑞克明尼苏达有限公司 用于喷射系统的配料缸
EP3021977A4 (fr) * 2013-07-19 2017-06-21 Graco Minnesota Inc. Cylindre de dosage pour système de pulvérisation
US10413924B2 (en) 2013-07-19 2019-09-17 Graco Minnesota Inc. Proportioning cylinder for spray system

Also Published As

Publication number Publication date
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