US20080008606A1 - Axially Driven Piston/Cylinder Unit - Google Patents
Axially Driven Piston/Cylinder Unit Download PDFInfo
- Publication number
- US20080008606A1 US20080008606A1 US11/794,026 US79402605A US2008008606A1 US 20080008606 A1 US20080008606 A1 US 20080008606A1 US 79402605 A US79402605 A US 79402605A US 2008008606 A1 US2008008606 A1 US 2008008606A1
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- United States
- Prior art keywords
- piston
- cylinder
- cylinder unit
- unit according
- axially driven
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B71/00—Free-piston engines; Engines without rotary main shaft
- F02B71/04—Adaptations of such engines for special use; Combinations of such engines with apparatus driven thereby
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- 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
- F04B35/00—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
- F04B35/04—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric
- F04B35/045—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for the means being electric using solenoids
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- 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
- F04B35/00—Piston pumps specially adapted for elastic fluids and characterised by the driving means to their working members, or by combination with, or adaptation to, specific driving engines or motors, not otherwise provided for
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- 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
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- 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
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- 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
- F16C32/00—Bearings not otherwise provided for
- F16C32/06—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings
Definitions
- the invention relates to an axially driven piston-cylinder unit and compressors comprising the same.
- Such a piston-cylinder unit is disclosed in U.S. Pat. No. 5,525,845.
- This piston-cylinder unit of prior art comprises a piston driven by a linear drive, the piston being connected to the linear drive by means of a piston rod.
- This piston rod is rigid in the axial direction and is flexible in the lateral direction, i.e. in the radial direction.
- This design of the piston rod is intended to ensure that the piston is guided free from friction in the air bearing of the cylinder even when the drive axis does not run parallel with the cylinder axis.
- This unspecific flexible design of the piston rod may, however, lead to a situation where transverse forces act on the piston causing the piston to tilt in the cylinder or giving rise to a lateral offset of the piston axis relative to the cylinder axis.
- the object of this invention is to further develop a generic piston-cylinder unit so that reliable operation of the fluid bearing, and hence reliable guidance of the piston in the cylinder, is guaranteed even when there is a lateral offset between the drive axis and the piston axis or where there is an inclination of both these axes relative to each other.
- the second piston-side joint is preferably provided in the direction of the longitudinal axis of the piston at a point which lies level with the rear region of the piston-side bearing surface. This guarantees that any transverse forces introduced by the piston rod into the piston are directly supported at this point in the piston-side bearing surface on the fluid bearing.
- Each joint section is preferably pivotable about at least one axis. However, it is also preferable for each joint section to be pivotable about two axes which are orthogonal to each other.
- a particularly preferred design comprises joint sections which move in the manner of a ball and socket joint. This ensures that any offset relative to the radial direction between the drive axis and the cylinder axis can be compensated for without special alignment of the piston in the circumferential direction.
- the fluid bearing preferably has a plurality of outlet nozzles for the fluid provided in the inner circumferential wall of the cylinder.
- outlet nozzles are arranged, in a particularly preferred embodiment, so that when the piston is in its second piston position, first outlet nozzles supply the front region of the piston-side bearing surface relative to the longitudinal extension of the piston, and second discharge nozzles supply the central or rear region of the piston-side bearing surface relative to the longitudinal piston extension, with pressure fluid.
- outlet nozzles are provided in the front and rear regions of the piston-side bearing surface, an extremely uniform support of the piston over its longitudinal extension is achieved in the compression position of the piston.
- first outlet nozzles to be provided in the front region and the second outlet nozzles to be provided in the central region, whereby the centre of gravity of the bearings extends forwards, i.e. towards the piston crown.
- outlet nozzle are arranged so that when the piston is in its first piston position, the second outlet nozzles supply the front region of the piston-side bearing surface relative to the longitudinal piston extension with pressure fluid, and third outlet nozzles supply the rear region of the piston-side bearing surface relative to the longitudinal piston extension with pressure fluid.
- third outlet nozzles in the rear region can provide improved support of the piston in its retracted position, particularly during the action of a transverse force.
- the fluid bearing prefferably be formed by a gas pressure bearing, the outlet nozzles being formed by gas outlet nozzles; an advantageous and particularly preferred embodiment is that of an air bearing.
- a plurality of outlet nozzles preferably form nozzle devices.
- the nozzle devices are preferably arranged annularly about the cylinder axis, preferably separated from each other in the axial direction of the piston-cylinder unit. As a result of this an extremely uniform fluid or gas cushion is developed between the piston and the cylinder.
- each nozzle ring For the formation of an extremely uniform fluid or gas cushion between the piston and the cylinder it is also advantageous for each nozzle ring to have a plurality of outlet nozzles uniformly separated from each other in the circumferential direction.
- the outlet nozzles are preferably formed by micro holes drilled by means of an energy-rich jet, which bores are preferably of a conical design, their narrowest cross-section being located on the opening into the cylinder-side bearing surface.
- the micro holes produced in this manner generate a fluid or gas cushion of high uniformity and high load carrying capacity.
- micro holes are preferably drilled by means of a laser jet.
- the pressure fluid for supplying the outlet nozzles is derived from a fluid flow generated by compression of the cylinder volume, from the outlet duct, for example, a simple structure of the piston-cylinder unit can be achieved and at the same time an additional pressure generator for the pressure fluid for supplying the outlet nozzles may be dispensed with, thereby contributing to low cost production of such a piston-cylinder unit.
- This piston-cylinder unit is particularly preferred when the piston is loaded by a moving part of a linear drive for the back and forth drive movement.
- a particularly noteworthy and advantageous application of the piston-cylinder unit according to the invention takes place in a compressor for generating a pressure fluid, preferably in a linear compressor driven by a linear motor.
- FIG. 1 shows a piston-cylinder unit according to the invention with the piston in a retracted position
- FIG. 2 shows the same piston-cylinder unit with the piston in the vicinity of the compression position.
- FIG. 1 shows a longitudinal section through a piston-cylinder unit 1 with a cylinder 2 and a piston 3 .
- Cylinder 2 is provided with a cylinder bore 10 in which piston 3 is accommodated so that it can be displaced back and forth in the direction of the longitudinal axis X of cylinder bore 10 and is freely guided.
- the head-side end wall 12 of cylinder bore, formed on a cylinder head 23 , inner circumferential wall 14 of cylinder bore 10 and piston crown 16 delimit cylinder volume 18 .
- An inlet duct 22 provided with a valve 20 shown diagrammatically, opens into head-side end wall 12 of cylinder bore 10 .
- an outlet duct 24 which has a corresponding valve 26 ; this outlet duct also opens into cylinder bore 10 .
- Piston-cylinder unit 1 shown is part of a piston working machine in which the expelled fluid is gaseous, as is the case with a compressor. In principle, however, the invention may also be used in other piston working machines such as pumps.
- annular ducts 30 , 32 , 34 are separated from each other in the direction of longitudinal axis X of cylinder bore 10 .
- Each of annular ducts 30 , 32 , 34 is provided with a multiplicity of micro holes 30 ′, 32 ′, 34 ′ which, distributed uniformly around the circumference of cylinder bore 10 , connect each annular duct 30 , 32 , 34 to the inside of cylinder bore 10 and in doing so penetrate inner wall 14 of the cylinder.
- Micro holes 30 ′, 32 ′, 34 ′ of each annular duct 30 , 23 , 34 therefore form a corresponding annular nozzle arrangement 30 ′′, 32 ′′, 34 ′′.
- Compressed gas which is conveyed through connecting duct 28 into annular ducts 30 , 32 , 34 can therefore escape through micro holes 30 ′, 32 ′, 34 ′ and form a gas cushion laterally supporting the piston between a cylinder-side bearing surface 15 on the inner circumferential wall 14 of cylinder 2 and a piston-side bearing surface 38 on the outer circumferential wall 36 of piston 3 .
- First annular duct 30 with micro holes 30 ′ assigned to it, is located in a region in which the piston only covers micro holes 30 ′ when it is in the vicinity of the compression position, i.e. when cylinder volume 18 is minimised, as shown in FIG. 2 .
- piston 3 covers the front, first micro holes 30 ′ with bearing surface 38 in front region 3 ′′.
- micro holes 30 ′ do not contribute to the formation of a gas cushion between inner circumferential wall 14 of cylinder 2 and outer circumferential wall 36 of the piston. Because of the extremely small cross-section of micro holes 30 ′, however, the pressure loss that therefore occurs is not serious. However, a valve arrangement (not shown). which loads first annular duct 30 with compressed gas when piston 3 covers micro holes 30 ′, may also be provided.
- Second annular duct 32 is arranged so that micro holes 32 ′ assigned to it are always covered by piston 3 , so that micro holes 32 ′ contribute to the formation of the gas cushion between inner circumferential wall 14 of cylinder 2 and outer circumferential wall 36 of piston 3 throughout the axial path of movement of piston 3 .
- Third annular duct 34 is furthest away from head-side end wall 12 of cylinder bore 10 .
- Micro holes 34 ′, assigned to third annular duct 34 are therefore not covered by piston 3 , i.e. by bearing surface 38 in rear region 3 ′ of the piston, until piston 3 is located in the region of its retracted position in which cylinder volume 18 is at a maximum.
- the provision of third annular channel 34 with micro holes 34 ′ assigned to it is optional and only serves to improve the running properties of piston 3 in cylinder bore 10 .
- annular nozzle arrangements in inner wall 14 of cylinder bore 10 may be provided between annular ducts 30 , 32 , 34 with micro holes 30 ′, 32 ′, 34 ′ assigned to them, which holes each form the annular nozzle devices 30 ′′, 32 ′′, 34 ′′.
- Piston 3 is driven by drive element 50 of a linear drive 5 that is longitudinally displaceable back and forth along an axis Y, in a vibrating manner, which drive is only represented diagrammatically in the figure.
- Moving drive element 50 is connected mechanically to piston 3 by means of a piston rod 4 .
- Piston rod 4 is non-elastic in the axial direction and is therefore capable of transmitting axial forces from drive element 50 to piston 3 . This force transmission presents no problems if longitudinal axis Y of drive element 50 and longitudinal axis X′ of piston 3 and longitudinal axis X of cylinder 2 are identical.
- longitudinal axis X of drive element 50 can be inclined to longitudinal axis X of cylinder 2 or offset parallel with it.
- axis X′ of piston 3 is not aligned exactly with axis X of cylinder 2 either, so that according to the state of the art piston 3 is positioned slightly obliquely in cylinder 2 , thus giving rise to contact between the piston and cylinder, which under certain circumstances cannot even be supported by gas pressure bearing.
- piston rod 4 is provided with a first drive-side joint section 40 and a second piston-side joint section 42 .
- these joint sections 40 , 42 are designed as sections with a diameter that is reduced relative to the remaining piston rod sections. Piston rod 4 is therefore more flexible in joint sections 40 , 42 than in the remaining piston rod sections, with the result that they are able to be bent into joint sections 40 , 42 .
- piston rod 4 compensates for the angular offset of these two axes relative to each other or the lateral offset of these two axes relative to each other, denoted in the figures by d, which means that longitudinal axis X′ of piston 3 is aligned essentially with axis X of the cylinder.
- d longitudinal axis X′ of piston 3 is aligned essentially with axis X of the cylinder.
- small transverse forces are introduced into the piston, which forces act essentially perpendicularly to axis X′ of piston 3 and can be supported by the gas cushion formed between cylinder-side bearing surface 15 and piston-side bearing surface 38 .
- Piston-side joint section 42 of piston rod 4 is arranged in rear region 3 ′ of piston 3 .
- the rear region is here defined as the region facing away from piston crown 16 with respect to a central plane M situated orthogonally on piston-side bearing surface 38 .
- Front piston region 3 ′′ is therefore that region between central plane M and the front, piston-crown-side end of piston 3 .
- the design of the axially driven piston-cylinder unit according to the invention provides improved guidance of piston 3 in cylinder 2 due to the special position of piston-side joint section 42 in rear piston region 3 ′, and results in a high degree of operational reliability.
- the front, first nozzle arrangement 30 ′′ reinforces this higher degree of reliability by strengthening the gas cushion formed by the fluid bearing at this point in the compressed condition of the piston-cylinder unit.
- the invention is not limited to the above exemplary embodiment, which serves merely as a general explanation of the core concept of the invention.
- the device according to the invention may instead assume embodiments other than those described above.
- the device may, in particular, have features which represent a combination of the individual features described in the claims.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Actuator (AREA)
- Compressor (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
- Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
- Reciprocating Pumps (AREA)
- Fluid-Damping Devices (AREA)
- Chairs Characterized By Structure (AREA)
- Radiation-Therapy Devices (AREA)
- Braking Systems And Boosters (AREA)
Abstract
Description
- The invention relates to an axially driven piston-cylinder unit and compressors comprising the same.
- Such a piston-cylinder unit is disclosed in U.S. Pat. No. 5,525,845. This piston-cylinder unit of prior art comprises a piston driven by a linear drive, the piston being connected to the linear drive by means of a piston rod. This piston rod is rigid in the axial direction and is flexible in the lateral direction, i.e. in the radial direction. This design of the piston rod is intended to ensure that the piston is guided free from friction in the air bearing of the cylinder even when the drive axis does not run parallel with the cylinder axis. This unspecific flexible design of the piston rod may, however, lead to a situation where transverse forces act on the piston causing the piston to tilt in the cylinder or giving rise to a lateral offset of the piston axis relative to the cylinder axis. This results in asymmetries in the air gap between the outer circumference of the piston and the inner circumference of the cylinder, so that the fluid bearing is weakened in the region in which the distance between the outer piston circumference and the inner cylinder circumference is increased because the pressure of the bearing fluid is reduced at this point. However, this reducing pressure enables the fluid compressed in the cylinder volume to penetrate the bearing gap at this weakened point as soon as the fluid pressure increases, further expanding the bearing gap until the piston finally bears against the cylinder wall at the radially opposite point on the piston, causing undesirable friction.
- The object of this invention is to further develop a generic piston-cylinder unit so that reliable operation of the fluid bearing, and hence reliable guidance of the piston in the cylinder, is guaranteed even when there is a lateral offset between the drive axis and the piston axis or where there is an inclination of both these axes relative to each other.
- This object is achieved by the features specified in the claims.
- The provision of the two joint sections in the piston rod first of all ensures that the piston rod is given the required flexibility, at defined points, to be able to compensate for a lateral offset of the axes. Because of the arrangement according to the invention of the piston-side joint of the piston rod in the rear region of the piston facing away from the piston crown, transverse forces acting on the piston are supported radially by the fluid bearing in the rear piston region, and away from the front piston-crown-side peripheral edge of the piston so that the fluid bearing is not influenced or is not substantially influenced by these harmful transverse forces. The risk that the piston may experience a lateral offset in the piston-cylinder unit of the invention due to transverse forces introduced into the piston by the piston rod in its front piston-crown-side region, which offset results in the state of the art in the detrimental weakening of the fluid bearing, is almost eliminated in the piston-cylinder unit according to the invention.
- The second piston-side joint is preferably provided in the direction of the longitudinal axis of the piston at a point which lies level with the rear region of the piston-side bearing surface. This guarantees that any transverse forces introduced by the piston rod into the piston are directly supported at this point in the piston-side bearing surface on the fluid bearing.
- Each joint section is preferably pivotable about at least one axis. However, it is also preferable for each joint section to be pivotable about two axes which are orthogonal to each other.
- A particularly preferred design comprises joint sections which move in the manner of a ball and socket joint. This ensures that any offset relative to the radial direction between the drive axis and the cylinder axis can be compensated for without special alignment of the piston in the circumferential direction.
- The fluid bearing preferably has a plurality of outlet nozzles for the fluid provided in the inner circumferential wall of the cylinder.
- Here the outlet nozzles are arranged, in a particularly preferred embodiment, so that when the piston is in its second piston position, first outlet nozzles supply the front region of the piston-side bearing surface relative to the longitudinal extension of the piston, and second discharge nozzles supply the central or rear region of the piston-side bearing surface relative to the longitudinal piston extension, with pressure fluid.
- If the outlet nozzles are provided in the front and rear regions of the piston-side bearing surface, an extremely uniform support of the piston over its longitudinal extension is achieved in the compression position of the piston. However, it is also advantageous for the first outlet nozzles to be provided in the front region and the second outlet nozzles to be provided in the central region, whereby the centre of gravity of the bearings extends forwards, i.e. towards the piston crown. Consequently a higher pressure is developed in the fluid bearing between the piston and cylinder in the region of the front end of the annular gap between the piston and cylinder, which pressure offers a higher resistance to the compressive pressure in the cylinder volume and is even better at preventing compressed pressure fluid from the cylinder volume from penetrating the bearing gap, even when a transverse force acts on the piston.
- In a further optional embodiment the outlet nozzle are arranged so that when the piston is in its first piston position, the second outlet nozzles supply the front region of the piston-side bearing surface relative to the longitudinal piston extension with pressure fluid, and third outlet nozzles supply the rear region of the piston-side bearing surface relative to the longitudinal piston extension with pressure fluid. These optionally provided third outlet nozzles in the rear region can provide improved support of the piston in its retracted position, particularly during the action of a transverse force.
- It is particularly preferable for the fluid bearing to be formed by a gas pressure bearing, the outlet nozzles being formed by gas outlet nozzles; an advantageous and particularly preferred embodiment is that of an air bearing.
- A plurality of outlet nozzles preferably form nozzle devices.
- The nozzle devices are preferably arranged annularly about the cylinder axis, preferably separated from each other in the axial direction of the piston-cylinder unit. As a result of this an extremely uniform fluid or gas cushion is developed between the piston and the cylinder.
- For the formation of an extremely uniform fluid or gas cushion between the piston and the cylinder it is also advantageous for each nozzle ring to have a plurality of outlet nozzles uniformly separated from each other in the circumferential direction.
- The outlet nozzles are preferably formed by micro holes drilled by means of an energy-rich jet, which bores are preferably of a conical design, their narrowest cross-section being located on the opening into the cylinder-side bearing surface. The micro holes produced in this manner generate a fluid or gas cushion of high uniformity and high load carrying capacity.
- These micro holes are preferably drilled by means of a laser jet.
- If the pressure fluid for supplying the outlet nozzles is derived from a fluid flow generated by compression of the cylinder volume, from the outlet duct, for example, a simple structure of the piston-cylinder unit can be achieved and at the same time an additional pressure generator for the pressure fluid for supplying the outlet nozzles may be dispensed with, thereby contributing to low cost production of such a piston-cylinder unit.
- This piston-cylinder unit is particularly preferred when the piston is loaded by a moving part of a linear drive for the back and forth drive movement.
- A particularly noteworthy and advantageous application of the piston-cylinder unit according to the invention takes place in a compressor for generating a pressure fluid, preferably in a linear compressor driven by a linear motor.
- The invention is explained in detail in the following by way of an example with reference to the drawing, in which:
-
FIG. 1 shows a piston-cylinder unit according to the invention with the piston in a retracted position; -
FIG. 2 shows the same piston-cylinder unit with the piston in the vicinity of the compression position. -
FIG. 1 shows a longitudinal section through a piston-cylinder unit 1 with acylinder 2 and apiston 3.Cylinder 2 is provided with acylinder bore 10 in whichpiston 3 is accommodated so that it can be displaced back and forth in the direction of the longitudinal axis X ofcylinder bore 10 and is freely guided. The head-side end wall 12 of cylinder bore, formed on acylinder head 23, innercircumferential wall 14 ofcylinder bore 10 andpiston crown 16 delimitcylinder volume 18. - An
inlet duct 22 provided with avalve 20, shown diagrammatically, opens into head-side end wall 12 ofcylinder bore 10. In head-side end wall 12 is also arranged anoutlet duct 24, which has acorresponding valve 26; this outlet duct also opens intocylinder bore 10. - During a movement of
piston 3 to the left, shown inFIG. 2 , fluid is sucked throughinlet duct 12 and inletvalve 20 intocylindrical space 18, and during a movement ofpiston 3 to the right, this fluid is expelled in the compressed state throughoutlet valve 26 andoutlet duct 24. Piston-cylinder unit 1 shown is part of a piston working machine in which the expelled fluid is gaseous, as is the case with a compressor. In principle, however, the invention may also be used in other piston working machines such as pumps. - Some of the expelled gaseous fluid is conveyed out of
outlet duct 24 through a connectingduct 28, which is provided incylinder head 23 andhousing 21 ofcylinder 2 and fed intoannular ducts housing 21 ofcylinder 2, and which surround cylinder bore 10 annularly.Annular ducts cylinder bore 10. Each ofannular ducts micro holes 30′, 32′, 34′ which, distributed uniformly around the circumference ofcylinder bore 10, connect eachannular duct cylinder bore 10 and in doing so penetrateinner wall 14 of the cylinder.Micro holes 30′, 32′, 34′ of eachannular duct annular nozzle arrangement 30″, 32″, 34″. Compressed gas, which is conveyed through connectingduct 28 intoannular ducts micro holes 30′, 32′, 34′ and form a gas cushion laterally supporting the piston between a cylinder-side bearingsurface 15 on the innercircumferential wall 14 ofcylinder 2 and a piston-side bearingsurface 38 on the outercircumferential wall 36 ofpiston 3. - First
annular duct 30, withmicro holes 30′ assigned to it, is located in a region in which the piston only coversmicro holes 30′ when it is in the vicinity of the compression position, i.e. whencylinder volume 18 is minimised, as shown inFIG. 2 . In thiscase piston 3 covers the front,first micro holes 30′ withbearing surface 38 infront region 3″. - In the position shown in
FIG. 1 , in whichcylinder volume 18 is at a maximum,micro holes 30′ do not contribute to the formation of a gas cushion between innercircumferential wall 14 ofcylinder 2 and outercircumferential wall 36 of the piston. Because of the extremely small cross-section ofmicro holes 30′, however, the pressure loss that therefore occurs is not serious. However, a valve arrangement (not shown). which loads firstannular duct 30 with compressed gas whenpiston 3 coversmicro holes 30′, may also be provided. - Second
annular duct 32 is arranged so thatmicro holes 32′ assigned to it are always covered bypiston 3, so thatmicro holes 32′ contribute to the formation of the gas cushion between innercircumferential wall 14 ofcylinder 2 and outercircumferential wall 36 ofpiston 3 throughout the axial path of movement ofpiston 3. - Third
annular duct 34 is furthest away from head-side end wall 12 ofcylinder bore 10.Micro holes 34′, assigned to thirdannular duct 34, are therefore not covered bypiston 3, i.e. by bearingsurface 38 inrear region 3′ of the piston, untilpiston 3 is located in the region of its retracted position in whichcylinder volume 18 is at a maximum. The provision of thirdannular channel 34 withmicro holes 34′ assigned to it is optional and only serves to improve the running properties ofpiston 3 incylinder bore 10. - Further similarly constructed annular nozzle arrangements in
inner wall 14 of cylinder bore 10 may be provided betweenannular ducts micro holes 30′, 32′, 34′ assigned to them, which holes each form theannular nozzle devices 30″, 32″, 34″. -
Piston 3 is driven bydrive element 50 of alinear drive 5 that is longitudinally displaceable back and forth along an axis Y, in a vibrating manner, which drive is only represented diagrammatically in the figure. Movingdrive element 50 is connected mechanically topiston 3 by means of a piston rod 4. Piston rod 4 is non-elastic in the axial direction and is therefore capable of transmitting axial forces fromdrive element 50 topiston 3. This force transmission presents no problems if longitudinal axis Y ofdrive element 50 and longitudinal axis X′ ofpiston 3 and longitudinal axis X ofcylinder 2 are identical. - Where
linear drive 5 is not aligned exactly with piston-cylinder unit 1, longitudinal axis X ofdrive element 50 can be inclined to longitudinal axis X ofcylinder 2 or offset parallel with it. This means that axis X′ ofpiston 3 is not aligned exactly with axis X ofcylinder 2 either, so that according to the state of theart piston 3 is positioned slightly obliquely incylinder 2, thus giving rise to contact between the piston and cylinder, which under certain circumstances cannot even be supported by gas pressure bearing. - For this reason piston rod 4 is provided with a first drive-side
joint section 40 and a second piston-sidejoint section 42. In the example shown, thesejoint sections joint sections joint sections piston 3 is aligned essentially with axis X of the cylinder. In this case small transverse forces are introduced into the piston, which forces act essentially perpendicularly to axis X′ ofpiston 3 and can be supported by the gas cushion formed between cylinder-side bearing surface 15 and piston-side bearing surface 38. - Piston-side
joint section 42 of piston rod 4 is arranged inrear region 3′ ofpiston 3. The rear region is here defined as the region facing away frompiston crown 16 with respect to a central plane M situated orthogonally on piston-side bearing surface 38.Front piston region 3″ is therefore that region between central plane M and the front, piston-crown-side end ofpiston 3. - Since the above-mentioned lateral forces act from piston rod 4 in the region of
joint section 42 orthogonally to longitudinal piston axis X′, they are supported by the section of piston-side bearing surface 38 located in this region against the gas cushion and hence against cylinder-side bearing surface 15. If in this case there is a slight deformation of the gas cushion, i.e. displacement of the annular space formed between piston-side bearing surface 38 and cylinder-side bearing surface 15, this deformation takes place essentially locally inrear region 3′ ofpiston 3 without exerting any substantial effect infront region 3″ ofpiston 3. The risk that compressed gas escapes from cylinder volume 80 and enters bearing gap asymmetrically due to such a deformation of the annular bearing gap betweenpiston 3 andcylinder 2 infront region 3″ ofpiston 3, and may then slide or tip the piston to the side, is therefore extremely small. - The design of the axially driven piston-cylinder unit according to the invention provides improved guidance of
piston 3 incylinder 2 due to the special position of piston-sidejoint section 42 inrear piston region 3′, and results in a high degree of operational reliability. The front,first nozzle arrangement 30″ reinforces this higher degree of reliability by strengthening the gas cushion formed by the fluid bearing at this point in the compressed condition of the piston-cylinder unit. - The invention is not limited to the above exemplary embodiment, which serves merely as a general explanation of the core concept of the invention. Within the scope of protection the device according to the invention may instead assume embodiments other than those described above. In this case the device may, in particular, have features which represent a combination of the individual features described in the claims.
- Reference symbols used in the claims, description and drawings serve merely to ensure a better understanding of the invention and will not limit the scope of protection.
Claims (18)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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DE102004061941.7A DE102004061941B4 (en) | 2004-12-22 | 2004-12-22 | Axially driven piston-cylinder unit |
DE102004061941.7 | 2004-12-22 | ||
PCT/EP2005/013865 WO2006069731A1 (en) | 2004-12-22 | 2005-12-22 | Axially driven piston/cylinder unit |
Publications (1)
Publication Number | Publication Date |
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US20080008606A1 true US20080008606A1 (en) | 2008-01-10 |
Family
ID=36049244
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US11/794,026 Abandoned US20080008606A1 (en) | 2004-12-22 | 2005-12-22 | Axially Driven Piston/Cylinder Unit |
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US (1) | US20080008606A1 (en) |
EP (1) | EP1831517B1 (en) |
JP (1) | JP2008524505A (en) |
KR (1) | KR20070098813A (en) |
CN (1) | CN100559020C (en) |
AT (1) | ATE406511T1 (en) |
DE (2) | DE102004061941B4 (en) |
ES (1) | ES2312047T3 (en) |
PL (1) | PL1831517T3 (en) |
RU (1) | RU2365784C2 (en) |
WO (1) | WO2006069731A1 (en) |
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US20080240950A1 (en) * | 2003-05-30 | 2008-10-02 | Mcgill Ian Campbell | Compressor improvements |
US20100098356A1 (en) * | 2006-11-07 | 2010-04-22 | BSH Bosch und Siemens Hausgeräte GmbH | Gas thrust bearing and associated production method |
US20120316479A1 (en) * | 2011-06-10 | 2012-12-13 | Tyco Healthcare Group Lp | Compression device having a pause feature |
CN104040177A (en) * | 2011-11-16 | 2014-09-10 | 惠而浦股份公司 | Piston cylinder arrangement of an aerostatic liner compressor |
EP2848810A1 (en) * | 2013-09-16 | 2015-03-18 | Lg Electronics Inc. | Reciprocating compressor |
US20150192117A1 (en) * | 2013-08-13 | 2015-07-09 | Bill P. BRIDGES | Well Service Pump System |
US20150377531A1 (en) * | 2014-06-26 | 2015-12-31 | Lg Electronics Inc. | Linear compressor and refrigerator including a linear compressor |
US9845797B2 (en) | 2012-09-03 | 2017-12-19 | Lg Electronics Inc. | Reciprocating compressor and method for driving same |
CN108397369A (en) * | 2016-07-21 | 2018-08-14 | 陕西仙童科技有限公司 | A kind of method of oil-free lubrication Linearkompressor and gas compression |
US10267299B2 (en) * | 2016-03-30 | 2019-04-23 | Kabushiki Kaisha Toyota Jidoshokki | Double-headed piston type swash plate compressor |
CN110701189A (en) * | 2019-09-23 | 2020-01-17 | 浙江大学 | Gas lubrication method adopting axial non-uniform arrangement and application |
EP3805560A1 (en) * | 2019-10-08 | 2021-04-14 | LG Electronics Inc. | Linear compressor |
US11415127B2 (en) | 2018-04-27 | 2022-08-16 | Ameriforge Group Inc. | Well service pump system structural joint housing having a first connector and a second connector each including one or more lands and grooves that are configured to mate with corresponding lands and grooves in an end cylinder housing and a ram cylinder housing |
US11852133B2 (en) | 2018-04-27 | 2023-12-26 | Ameriforge Group Inc. | Well service pump power system and methods |
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DE102012104165B3 (en) * | 2012-05-11 | 2013-08-08 | AeroLas GmbH Aerostatische Lager- Lasertechnik | Piston-cylinder unit for e.g. linear air compressor, has exhaust pipe deriving fluid into exhaust groove at pressure level lower than pressure in compression space if piston is moved to top dead center or proximity to top dead center |
DE102012104163B3 (en) * | 2012-05-11 | 2013-08-08 | AeroLas GmbH Aerostatische Lager- Lasertechnik | Piston cylinder unit of linear compressor, has bearing gap whose radial extent is greater than radial extent of compression space facing away from bearing gap section during piston approximation to top dead center of compression space |
KR102003442B1 (en) * | 2012-05-11 | 2019-07-24 | 에어로라스 게엠베하, 에어로슈타티쉐 라거- 레이저테크닉 | Piston/cylinder unit |
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DE102020114948A1 (en) | 2020-06-05 | 2021-12-09 | Aerolas Gmbh, Aerostatische Lager- Lasertechnik | Linear compressor |
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- 2005-12-22 CN CNB200580044450XA patent/CN100559020C/en not_active Expired - Fee Related
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- 2005-12-22 RU RU2007121328/06A patent/RU2365784C2/en not_active IP Right Cessation
- 2005-12-22 EP EP05850330A patent/EP1831517B1/en not_active Not-in-force
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Cited By (22)
Publication number | Priority date | Publication date | Assignee | Title |
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US8684706B2 (en) * | 2003-05-30 | 2014-04-01 | Fisher & Paykel Appliances Limited | Connecting rod for a linear compressor |
US20080240950A1 (en) * | 2003-05-30 | 2008-10-02 | Mcgill Ian Campbell | Compressor improvements |
US20100098356A1 (en) * | 2006-11-07 | 2010-04-22 | BSH Bosch und Siemens Hausgeräte GmbH | Gas thrust bearing and associated production method |
US20120316479A1 (en) * | 2011-06-10 | 2012-12-13 | Tyco Healthcare Group Lp | Compression device having a pause feature |
CN104040177A (en) * | 2011-11-16 | 2014-09-10 | 惠而浦股份公司 | Piston cylinder arrangement of an aerostatic liner compressor |
US9845797B2 (en) | 2012-09-03 | 2017-12-19 | Lg Electronics Inc. | Reciprocating compressor and method for driving same |
US10876523B2 (en) * | 2013-08-13 | 2020-12-29 | Ameriforge Group Inc. | Well service pump system |
US20150192117A1 (en) * | 2013-08-13 | 2015-07-09 | Bill P. BRIDGES | Well Service Pump System |
US20230340949A1 (en) * | 2013-08-13 | 2023-10-26 | Ameriforge Group Inc. | Well service pump system and methods |
US11506189B2 (en) * | 2013-08-13 | 2022-11-22 | Ameriforge Group Inc. | Well service pump |
EP2848810A1 (en) * | 2013-09-16 | 2015-03-18 | Lg Electronics Inc. | Reciprocating compressor |
US10151308B2 (en) | 2013-09-16 | 2018-12-11 | Lg Electronics Inc. | Reciprocating compressor having a gas bearing |
US10837434B2 (en) | 2013-09-16 | 2020-11-17 | Lg Electronics Inc. | Reciprocating compressor having a gas bearing |
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US20150377531A1 (en) * | 2014-06-26 | 2015-12-31 | Lg Electronics Inc. | Linear compressor and refrigerator including a linear compressor |
US10267299B2 (en) * | 2016-03-30 | 2019-04-23 | Kabushiki Kaisha Toyota Jidoshokki | Double-headed piston type swash plate compressor |
CN108397369A (en) * | 2016-07-21 | 2018-08-14 | 陕西仙童科技有限公司 | A kind of method of oil-free lubrication Linearkompressor and gas compression |
US11415127B2 (en) | 2018-04-27 | 2022-08-16 | Ameriforge Group Inc. | Well service pump system structural joint housing having a first connector and a second connector each including one or more lands and grooves that are configured to mate with corresponding lands and grooves in an end cylinder housing and a ram cylinder housing |
US11852133B2 (en) | 2018-04-27 | 2023-12-26 | Ameriforge Group Inc. | Well service pump power system and methods |
CN110701189A (en) * | 2019-09-23 | 2020-01-17 | 浙江大学 | Gas lubrication method adopting axial non-uniform arrangement and application |
EP3805560A1 (en) * | 2019-10-08 | 2021-04-14 | LG Electronics Inc. | Linear compressor |
US11603834B2 (en) | 2019-10-08 | 2023-03-14 | Lg Electronics Inc. | Linear compressor |
Also Published As
Publication number | Publication date |
---|---|
PL1831517T3 (en) | 2009-02-27 |
WO2006069731A1 (en) | 2006-07-06 |
EP1831517B1 (en) | 2008-08-27 |
RU2365784C2 (en) | 2009-08-27 |
DE102004061941B4 (en) | 2014-02-13 |
KR20070098813A (en) | 2007-10-05 |
JP2008524505A (en) | 2008-07-10 |
EP1831517A1 (en) | 2007-09-12 |
DE502005005222D1 (en) | 2008-10-09 |
CN100559020C (en) | 2009-11-11 |
ES2312047T3 (en) | 2009-02-16 |
ATE406511T1 (en) | 2008-09-15 |
RU2007121328A (en) | 2009-01-27 |
DE102004061941A1 (en) | 2006-07-06 |
CN101091043A (en) | 2007-12-19 |
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