# Patent

## Title
Compressor, engine or pump with a piston translating along a circular path

## Abstract

Described herein is a device comprising: a chamber wall comprising outer and inner surfaces, wherein the inner surface encloses a lobed chamber with a plurality of lobes and the inner surface comprises segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments, and wherein the chamber wall further comprises channels connecting the outer surface and the inner surface of the chamber wall and/or channels through an end surface of the chamber wall; a lobed piston configured to translate along a circular path relative to the chamber wall, the outer surface of the piston and the inner surface of the chamber wall engaged during translation; and holes fluidly connected to the lobed chamber and configured to allow fluid discharge from the lobed chamber through the holes and to prevent fluid flow into the lobed chamber through the holes.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent application Ser. No. 13/238,107, filed on Sep. 21, 2011, which is hereby incorporated by reference in its entirety.


BACKGROUND
Mechanical power can be derived from pressure differential of fluid such as steam. The history of the steam engine stretches back as far as the first century AD. James Watt developed a steam engine that provides a rotary motion suitable for driving factory machinery. This enabled factories to be sited away from rivers, and further accelerated the pace of the Industrial Revolution. Around 1800, Richard Trevithick introduced engines using high-pressure steam. These were much more powerful than previous engines and could be made small enough for transport applications.
A reciprocating compressor or piston compressor is a positive-displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure. The intake gas enters the suction manifold, then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft, and is then discharged. Applications include oil refineries, gas pipelines, chemical plants, natural gas processing plants and refrigeration plants.
SUMMARY
Described herein is a device comprising: a chamber wall comprising an outer surface and an inner surface, wherein the inner surface encloses a lobed chamber with a plurality of lobes and the inner surface comprises segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments, and wherein the chamber wall further comprises channels connecting the outer surface and the inner surface of the chamber wall and/or channels through an end surface of the chamber wall; a piston configured to translate along a circular path relative to the chamber wall and form enclosed spaces between the piston and the chamber wall; and holes fluidly connected to the lobed chamber and configured to allow fluid discharge from the lobed chamber through the holes and to prevent fluid flow into the lobed chamber through the holes.
Also described herein is a device comprising: a chamber wall comprising an outer surface and an inner surface, wherein the inner surface encloses a lobed chamber with a plurality of lobes and the inner surface comprises segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments, and wherein the chamber wall further comprises channels connecting the outer surface and the inner surface of the chamber wall and/or channels through an end surface of the chamber wall; a piston configured to translate along a circular path relative to the chamber wall and form enclosed spaces between the piston and the chamber wall; and a through hole configured to fluidly connect to the enclosed spaces only when fluid in the enclosed spaces are being compressed.
Also described herein is a method of generating mechanical power using the device summarized above.
Additionally described herein is a method of compressing and/or driving a fluid using the device summarized above.



BRIEF DESCRIPTION OF FIGURES
FIG. 1 shows an end view of the inner surface of the chamber wall (left panel) and an end view of the outer surface of the piston (right panel), according to an embodiment.
FIG. 2 shows end views of the piston and the inner surface of the chamber wall at six different translation positions.
FIG. 3 shows end view of the chamber wall, the piston including the seal plate and holes therein, the transportation plate and holes therein at six different translation positions.
FIG. 4 shows a sectional view of a device according to an embodiment.
FIG. 4B shows details in the dotted oval in FIG. 4.
FIG. 5 shows an end view of the chamber wall and the piston wherein channels are located through an end surface of the chamber wall.
FIG. 6 shows a sectional view of a device according to an embodiment.
FIG. 7 shows a sectional view of a device according to an embodiment.
FIG. 8 shows a top view of an exemplary chamber wall.
FIG. 9 shows a top view of an exemplary piston.
FIG. 10 shows a top view of an exemplary transportation plate.
FIG. 11 is a vertical sectional view of a device according to an embodiment.
FIG. 12 is a sectional view of the surface A-A in FIG. 11.
FIG. 13 is a view of the device in FIG. 11 from the top of the device with a shell removed.
FIG. 14 shows a vertical sectional view of a device according to an embodiment.
FIG. 15 shows a vertical sectional view of a device according to an embodiment.
FIG. 16A shows an end view of the chamber wall and the piston according an embodiment.
FIG. 16B shows a vertical sectional view of a device according to an embodiment.



DETAILED DESCRIPTION
A device as described herein comprises a chamber wall having an outer surface and an inner surface, the inner surface enclosing a lobed chamber and comprising segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments. Two arcuate surfaces “being tangent” as used herein means that the angles between the two arcuate surfaces are zero at an intersecting line between the two arcuate surfaces. The device also comprises a lobed piston located inside the lobed chamber. The piston can have an outer surface comprising segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments. The lobes of the piston are located in the lobes of the chamber. The outer surface of the piston encloses a main body of the piston.
The piston is configured to translate along a circular path relative to the chamber wall. Preferably, the piston translates along a circular path concentric with a rotational symmetric center of the chamber wall. Preferably, the piston does not rotate relative to the chamber wall during translation. The outer surface of the piston and the inner surface of the chamber wall are engaged during translation and form a fluid-tight seal between some portions of the outer surface of the piston and the inner surface of the chamber wall, such that enclosed spaces are formed between lobes of the piston and lobes of the chamber wall. As explained in more details below, the enclosed spaces between a lobe of the piston and the lobe of the chamber in which the lobe of the piston is located change volume during translation. The chamber wall has channels connecting the outer surface and the inner surface of the chamber wall. The channels are fluidly connected to the spaces between a lobe of the piston and the lobe of the chamber in which the lobe of the piston is located. As the spaces expand in volume, fluid can be drawn from the channels into the spaces. The chamber wall having channels connecting the outer surface and the inner surface of the chamber wall reduces fluid flow resistance and increases fluid flow rate.
The piston further comprises a seal plate attached to an end of the main body. The seal plate forms a fluid-tight seal with the chamber wall. The seal plate is preferably circular and extends beyond the lobes of the piston. The seal plate has holes between two opposing surfaces and the through holes can be fluidly connected to the enclosed spaces. Preferably, each of the holes is tangent with one segment of arcuate surface of the outer surface of the piston. The holes in the seal plate preferably are through holes and can have any suitable shape such as circular shape.
The device further comprises a transportation plate that is fixed to and forms a fluid-tight seal with the chamber wall. The transportation plate and the chamber wall enclose the piston in the lobed chamber while allowing the piston to translate therein. The transportation plate urges the piston against a bottom of the chamber and restraints the axial position of the piston. The transportation plate has through holes that overlap and fluidly connect to the holes in the seal plate of the piston, when the piston is selected translational positions of the piston relative to the chamber wall.
The holes in the transportation plate can have any suitable shape. The number of the holes in the transportation plate preferably equals the number of the holes in the seal plate. The number of the holes in the transportation plate preferably equals the number of lobes of the lobed chamber. The holes in the transportation plate preferably are located such that portions of the inner surface of the chamber wall overlap each of the holes in the transportation plate.
According to an embodiment, each of the holes of the transportation plate corresponds to each lobe of the lobed chamber. The location of the holes of the transportation plate are configured such that each hole of the transportation plate overlaps with a hole in the seal plate of the piston and fluidly connect to the lobe of the lobed chamber that the hole of the transportation plate corresponds to, only when an enclosed space forms in the lobe between the chamber wall and the piston and fluid in the sealed place is compressed to a predetermined compression ratio. The term “compression ratio” as used herein means the pressure ratio of compressed fluid to uncompressed fluid. The exact location of the holes in the transportation plate can be changed in order to tune the predetermined compression ratio. When a hole in the seal plate of the piston overlaps with a hole in the transportation plate, compressed fluid in the corresponding enclosed space discharges from the enclosed space through the holes. The hole in the transportation plate disconnects from the enclosed space before a volume of the enclosed space reduces to zero. The transportation plate is configured to prevent fluid leakage.
According to an embodiment, the transportation plate may be fixed or rotatable. The transportation plate and the seal plate cooperatively control the connection between the enclosed spaces and output space. The through holes of the transportation plate and the through holes of the seal plate can be arranged such that when the pressure of fluid in the enclosed spaces increases to a certain value, the through holes of the seal plate and the through holes of the transportation plate may overlap so that the fluid inside the enclosed spaces can discharge therefrom.
Compressed fluid discharged from the lobed chamber through the holes of the seal plate can press the seal plate against the chamber wall so as to enhance the fluid-tight seal between the seal plate and the chamber wall, reduce fluid leakage between the seal plate and the chamber wall, reduce fluid leakage between the lobes of the lobed chamber through any gap between the piston and the bottom of the lobed chamber and reduce any friction between the seal plate and the transportation plate.
According to an embodiment, compressed fluid discharged from the lobed chamber can be used to drive lubricant into any drive shaft of the piston, any gap between the piston and the chamber wall, any gap between the seal plate and the transportation plate wherein the lubricant can reduce friction and form fluid-tight seals.
FIG. 1 shows an end view of the inner surface 100 of the chamber wall 1 (left panel) and an end view of the outer surface 200 of the piston 2 (right panel), according to an embodiment. The inner surface 100 consists of twelve segments of arcuate surfaces: 110A, 120A, 1108, 120B, 110C, 120C, 110D, 120D, 110E, 120E, 110F and 120F. The black triangles mark intersecting lines between neighboring segments. Each segment is tangent to its neighboring segments. For example, 110A is tangent to 120A and 120F; 120C is tangent to 110D and 110C. The inner surface 100 has n-fold rotational symmetry with point O as its rotational symmetric center, wherein n can be any integer greater than one, such as six. r denotes the shortest distance between a point on 120A, 120B, 120C, 120D, 120E and 120F and point O. R denotes the longest distance between a point on 110A, 1108, 110C, 110D, 110E and 110F and point O. Distance from each of the centers of 110A, 1108, 110C, 110D, 110E and 110F to point O is A. The outer surface 200 consists of twelve segments of arcuate surfaces: 210A, 220A, 210B, 220B, 210C, 220C, 210D, 220D, 210E, 220E, 210F and 220F. The black triangles mark intersecting lines between neighboring segments. Each segment is tangent to its neighboring segments. For example, 210A is tangent to 220A and 220F; 220C is tangent to 210D and 210C. The inner surface 200 has n′-fold rotational symmetry with point O′ as its rotational symmetric center, wherein n′ can be any integer greater than one and preferable equals n. r′ denotes the shortest distance between a point on 220A, 220B, 220C, 220D, 220E and 220F and point O′. R′ denotes the longest distance between a point on 210A, 210B, 210C, 210D, 210E and 210F and point O′. Distance from each of the centers of 10A, 210B, 210C, 210D, 210E and 210F to point O′ is A′. A essentially equals A′. (R-R′) essentially equals (r-r′). R is greater than R′. r is greater than r′. The piston 2 translates along a circular path 150 of a diameter of (R-R′) and concentric with point O.
FIGS. 2A-2F show locations of the piston 2 relative to the inner surface 100 of the chamber wall 1, as the piston 2 translates along the circular path 150, according to an embodiment. Enclosed spaces, such as enclosed spaces 203 and 204, form between lobes of the outer surface 200 of the piston 2 and lobes of the inner surface 100 of the chamber wall 1, when the piston 2 is at certain translational locations.
Volume of the enclosed spaces 203 and 204 change as the piston 2 translates along the circular path 150 relative to the chamber wall 1. In this particular example, as the piston 2 translates along the circular path 150 counterclockwise, the enclosed space 203 periodically forms, contracts and disappears (i.e., connected to space between another lobe of the inner surface 100 and the outer surface 200, such as shown in FIGS. 2E and 2F); the enclosed space 204 periodically forms, expands and disappears (i.e., connected to space between another lobe of the inner surface 100 and the outer surface 200, such as shown in FIGS. 2D and 2E). The enclosed space 203 can be used as a compression chamber to compress and/or increase pressure of fluid therein. The enclosed space 204 can be used as an intake chamber to draw fluid to be compressed.
FIGS. 3A-3F correspond to FIGS. 2A-2F, respectively, and additionally show the transportation plate 3 and holes 3A therein, the seal plate 2B of the piston 2 and holes 2A therein. A long dotted line shows the outer surface of the chamber wall 1. A solid line shows the contour of the transportation plate 3. The short dotted line shows the contour of the seal plate 2B. In this particular example, the piston 2 translates along the circular path 150 counterclockwise relative to the chamber wall 1. At the location as shown in FIG. 3A, the hole 2A is not fluidly connected to the hole 3A; the enclosed space 204 is fluidly connected to a channel 1A of the chamber wall 1. At the location as shown in FIG. 3B, the enclosed space 203 has contracted from its state shown in FIG. 3A. Any fluid therein is thus compressed or has elevated pressure. The hole 2A barely fluidly connects to the hole 3A and fluid in the enclosed space 203 begins to be discharged from the enclosed space 203. The enclosed space 204 expands and draws fluid from the channel 1A of the chamber wall 1. At the location shown in FIG. 3C, the hole 2A is fully fluidly connected to the hole 3A and most fluid in the enclosed space 203 has been discharged therefrom. The enclosed space 204 further expands, draws more fluid from the channel 1A, and reaches its maximal volume. At location shown in FIG. 3D, the enclosed space 203 contracts to almost nil and essentially all fluid in therein has been discharged. The hole 2A is no longer fluidly connected to the hole 3A. The enclosed space 204 disappears, i.e., connected to space between another lobe of the inner surface 100 and the outer surface 200. At location shown in FIG. 3E, the enclosed space 203 disappears, i.e., connected to space between another lobe of the inner surface 100 and the outer surface 200. In this particular example, 6 enclosed spaces form, contracts and disappear and 6 enclosed spaces form, expands and disappear while the piston 2 translates by a full circle along the circular path 150.
FIG. 4 is a cross-sectional view of a device according to an embodiment. In this embodiment, the channels 1A are located through a side wall of the chamber wall 1, connecting the outer surface and inner surface of the chamber wall 1. The piston 2 has the seal plate 2B fixed to a main body 2C of the piston 2. The main body 2C of the piston 2 can be viewed as a boss extending from the seal plate 2B into the lobed chamber. The term “main body 2C” and “boss 2C” are used interchangeable here after. The height of the boss 2C and the depth of the lobed chamber are substantially equal so as to form seals between the piston 2 and the chamber wall 1. The piston 2 also has a blind bearing hole open from the seal plate 2B, and an oil channel 2D connecting the blind bearing hole to an end surface of the boss 2C.
The holes 3A of the transportation plate 3 is fluidly connected to a lower chamber 40. The holes 3A can have a cross-sectional shape of a nozzle, i.e., the opening of the holes 3A open to the lower chamber 40 is larger in area than the opening of the holes 3A facing the seal plate 2B. Such cross-sectional shape of the holes 3A can be effective to lower the fluid flow speed through the holes 3A and decrease fluid flow resistance.
A driving shaft 5 is operably connected with a rotor 6A of an electric motor 6. An oil channel through the driving shaft 5 opens at opening 5A at one end of the driving shaft 5 and at opening 5B at another end of the driving shaft 5.
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
A shell 8 fixed to transportation plate 3 and chamber wall 1, is part of an enclosure that encloses the chamber wall 1, piston 2, transportation plate 3, and has at least one fluid inlet 9 and at least one outlet 11.
Low temperature fluid flows through the inlet 9 into an upper chamber 30, and the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency. Fluid discharged from the lobed chamber flows through holes 2A of piston 2 and holes 3A of transportation plate 3 into a lower chamber 40, then flows through the electric motor 6, which can cool the motor 6, and into a bottom chamber 50. The fluid finally flows through a gap between the motor 6 and a shell 8B and is exhausted through the outlet 11.
The fluid in bottom chamber 50 produces high force on the surface of the oil in an oil pool 8D and causes the oil to flow into the driving shaft oil channel opening 5A which is submerged in the oil. The oil reaches another end 5B of the driving shaft 5. Some of the oil flows through a gap in a bearing in the bearing shaft of the piston 2 and into a gap between the transportation plate 3 and the seal plate 2B so as to reduce friction therebetween. Some of the oil flows through the oil channel 2D of piston 2 and into a gap between the boss 2C and the chamber wall 1 and the lobed chamber so as to reduce friction between the piston 2 and the chamber wall 1, and cool the chamber wall 1 and piston 2. The oil flows through the holes 3A and returns to the oil pool 8D.
When the oil flows through the oil channel 2D into the lobed chamber, and the fluid in the lobed chamber is compressed, the piston 2 can be urged to move axially away from the chamber wall 1, which can break the seal between the chamber wall 1 and the piston 2 and cause leakage. High pressure fluid in the lower chamber 40 exerts force through holes 3A onto the seal plate 2B and pushes the piston 2 against the chamber wall 1, which enhances seal of between the chamber 1 and the piston 2.
The piston 2 may have a recess 2F on a surface engaging the end surface of the chamber wall 1. The recess 2F may be configured to accommodate oil from the oil channel 5B. There may be a chamber 2G between a bottom of the piston 2 and the driving shaft 5. The chamber 2G is configured to accommodate oil from the oil channel 5B through a hole 5D in a wall of the driving shaft 5. The hole 5D functions as a throttle to oil flow into the chamber 2G. The hole 2D functions as a throttle to oil flow into the recess 2F. The recess 2F and the chamber 2G are functional to suspend the piston 2 in the axial direction by oil pressure so as to reduce contact friction between the piston 2 and chamber wall 1 and the transportation plate 3. Upward movement of the piston 2 reduces a gap between the piston 2 and the chamber wall 1 and enlarges a gap between the piston 2 and the transportation plate 3, which increases oil pressure inside the recess 2F, decreases oil pressure inside the chamber 2G, and drives the piston 2 back downward. The oil pressure in the recess 2F increases because the gap between the piston 2 and the chamber 1 is reduced by the upward movement of the piston 2, which reduces oil flow rate and flow resistance in the hole 2D. The oil pressure in the recess 2F is essentially equal to the oil pressure in the driving shaft 5 minus the flow resistance through the hole 2D. Downward movement of the piston 2 enlarges the gap between the piston 2 and the chamber wall 1 and reduces the gap between the piston 2 and the transportation plate 3, which decreases oil pressure inside the recess 2F, increases oil pressure inside the chamber 2G, and drives the piston 2 back upward. The oil pressure in the chamber 2G increases because the gap between the piston 2 and the transportation plate 3 is reduced by the downward movement of the piston 2, which reduces oil flow rate and flow resistance in the hole 5D. The oil pressure in the chamber 2G is essentially equal to the oil pressure in the driving shaft 5 minus the flow resistance through the hole 5D.
FIG. 6 is a vertical sectional view of a device according to an embodiment. In this embodiment, the channels 1A are located through a side wall of the chamber wall 1, connecting the outer surface and inner surface of the chamber wall 1. The channels 1A′ can also be located through an end surface of the chamber wall 1 shown in FIG. 5.
The piston 2 has the seal plate 2B fixed to a main body 2C of the piston 2. The main body 2C of the piston 2 can be viewed as a boss extending from the seal plate 2B into the lobed chamber. The term “main body 2C” and “boss 2C” are used interchangeable here after. The height of the boss 2C and the depth of the lobed chamber are substantially equal so as to form seals between the piston 2 and the chamber wall 1. The piston 2 also has a blind bearing hole open from the seal plate 2B, and an oil channel 2D connecting the blind bearing hole to an end surface of the boss 2C.
The holes 3A of the transportation plate 3 is fluidly connected to a lower chamber 40A. The holes 3A can have a cross-sectional shape of a nozzle, i.e., the opening of the holes 3A open to the lower chamber 40 is larger in area than the opening of the holes 3A facing the seal plate 2B. Such cross-sectional shape of the holes 3A can be effective to lower the fluid flow speed through the holes 3A and decrease fluid flow resistance.
A high pressure shell 21 is fixed with the transportation plate 3, is used to collect high pressure fluid discharged from holes 3A in transportation plate 3.
A driving shaft 5 is operably connected with a rotor 6A of an electric motor 6. An oil channel through the driving shaft 5 opens at opening 5A at one end of the driving shaft 5 and at opening 5B at another end of the driving shaft 5.
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
A shell 8 which is fixed to transportation plate 3 and chamber wall 1, is part of an shell that encloses the chamber wall 1, piston 2, transportation plate 3, and has at least one fluid inlet 9A and at least one outlet 11A.
Low temperature fluid flows through the inlet 9A into a chamber 30A inside the shell 21, through the motor 6 so as to cool the motor 6, into a chamber 30B, through a space 30C between the motor 6 and the shell 21 so as to cool the motor 6, through a gap 30D between the transportation plate 3 and the shell 21 into a chamber 30E. Fluid in the chamber 30E then flows through the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency. Fluid discharged from the lobed chamber flows through holes 2A of piston 2 and holes 3A of transportation plate 3 into a chamber 40A, and finally is exhausted through the outlet 11A.
The fluid in the chamber 30B produces high force on the surface of the oil in an oil pool 8D and causes the oil to flow into the driving shaft oil channel opening 5A which is submerged in the oil. The oil reaches another end 5B of the driving shaft 5. Some of the oil flows through a gap in a bearing in the bearing shaft of the piston 2 and into a gap between the transportation plate 3 and the seal plate 2B so as to reduce friction therebetween. Some of the oil flows through the oil channel 2D of piston 2 and into a gap between the boss 2C and the chamber wall 1 and the lobed chamber so as to reduce friction between the piston 2 and the chamber wall 1, and cool the chamber wall 1 and piston 2. The oil flows through the holes 3A, 21A and returns to the oil pool 8D.
When the oil flows through the oil channel 2D into the lobed chamber, and the fluid in the lobed chamber is compressed, the piston 2 can be urged to move axially away from the chamber wall 1, which can break the seal between the chamber wall 1 and the piston 2 and cause leakage. High pressure fluid in the lower chamber 40A exerts force through holes 3A onto the seal plate 2B and pushes the piston 2 against the chamber wall 1, which enhances seal of between the chamber 1 and the piston 2.
FIG. 7 is a vertical sectional view of a device according to an embodiment. The device in this embodiment can be used to transport clean fluid. In this embodiment, the channels 1A are located through a side wall of the chamber wall 1, connecting the outer surface and inner surface of the chamber wall 1. The channels 1A′ can also be located through an end surface of the chamber wall 1 shown in FIG. 5. The chamber wall 1 has at least one groove 1C located in and open to a surface of the chamber wall 1, wherein the surface faces the seal plate 2B. The groove 1C is filled in lubricant effective to form a fluid-tight seal and provide lubrication between the seal plate 2B and the chamber wall 1.
The piston 2 has the seal plate 2B fixed to a main body 2C of the piston 2. The main body 2C of the piston 2 can be viewed as a boss extending from the seal plate 2B into the lobed chamber. The term “main body 2C” and “boss 2C” are used interchangeable here after. The height of the boss 2C and the depth of the lobed chamber are substantially equal so as to form seals between the piston 2 and the chamber wall 1. The piston 2 also has a blind bearing hole open from the seal plate 2B. The boss 2C has at least one groove 2E located in and open to an end surface of the boss 2C, wherein the end surface faces the chamber wall 1. The groove 2E is filled in lubricant effective to form a fluid-tight seal and provide lubrication between the boss 2C and the chamber wall 1.
The holes 3A of the transportation plate 3 is fluidly connected to a lower chamber 40B. The holes 3A can have a cross-sectional shape of a nozzle, i.e., the opening of the holes 3A open to the lower chamber 40B is larger in area than the opening of the holes 3A facing the seal plate 2B. Such cross-sectional shape of the holes 3A can be effective to lower the fluid flow speed through the holes 3A and decrease fluid flow resistance. The transportation plate 3 has at least one groove 3B located in and open to a surface of the transportation plate, wherein the surface faces the seal plate 2B. The groove 3B is filled in lubricant effective to form a fluid-tight seal and provide lubrication between the seal plate 2B and the transportation plate 3.
A high pressure shell 21 is fixed with the transportation plate 3, is used to collect high pressure fluid comes from holes 3A in transportation plate 3. The said high pressure shell 21 has groove 21A in which filled with material of lubrication and seal.
A high pressure shell 21 is fixed with the transportation plate 3, is used to collect high pressure fluid discharged from holes 3A in transportation plate 3. The shell 21 has at least one outlet 11B.
A low pressure shell 22 is fixed with the chamber wall 1. The shell 22 has at least one inlet 9B.
A driving shaft 5 can be connected to a motor (not shown in FIG. 7).
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150.
An anti-rotation ring 12 can be disposed in the device and operable to prevent rotation of the piston 2 during the translation of the piston 2 along the circular path 150.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
Low temperature fluid flows through the inlet 9B into a chamber 30F inside the shell 22, through heat sink fins 1B on the chamber wall 1 so as to cool the chamber wall 1. Fluid in the chamber 30F then flows through the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency. Fluid discharged from the lobed chamber flows through holes 2A of piston 2 and holes 3A of transportation plate 3 into a chamber 40B, and finally is exhausted through the outlet 11B.
When the fluid in the lobed chamber is compressed, the piston 2 can be urged to move axially away from the chamber wall 1, which can break the seal between the chamber wall 1 and the piston 2 and cause leakage. High pressure fluid in the lower chamber 40B exerts force through holes 3A onto the seal plate 2B and pushes the piston 2 against the chamber wall 1, which enhances seal of between the chamber 1 and the piston 2.
Each pair of surface the move relative to each other is lubricated by solid lubricant to reduce friction loss and enhance seal therebetween. For example, grooves 1C and 2E provide lubricant and form a fluid-tight seal between the chamber wall 1 and the piston 2. FIG. 8 shows a top view of an exemplary chamber wall 1 with the groove 1C. FIG. 9 shows a top view of an exemplary piston 2 with the groove 2E. Groove 3B provides lubricant and form a fluid-tight seal between the seal plate 2B and the transportation plate 3. FIG. 10 shows a top view of an exemplary transportation plate 3 with the groove 3B. The transportation plate 3 can further have a groove 3C in and open to a surface facing the driving shaft 5 to provide lubricant and form a fluid-tight seal between the transportation plate 3 and the driving shaft 5. The shell 21 can have a groove 21A in and open to a surface facing the driving shaft 5 to provide lubricant and form a fluid-tight seal between the shell 21 and the driving shaft 5. The grooves 1C, 2E, 3B, 3C can be arranged in any suitable fashion. The device can have any suitable number of grooves to provide lubricant.
FIG. 11 is a vertical sectional view of a device according to an embodiment. FIG. 12 is a sectional view of the surface A-A in FIG. 11, with the piston 2, the chamber wall 1 and the transportation plate 3 overlaid thereon. FIG. 13 is a view of the device in FIG. 11 from the top of the device with a shell removed. Same reference numerals in FIGS. 11-13 refer to the same feature.
In this embodiment, a flow regulation plate 101 is rotatably attached to and forms a fluid-tight seal with the chamber wall 1, and forms the bottom of the lobed chamber. The flow regulation plate 101 can be attached to the chamber wall 1 by any suitable means, such as being retained in a recess on the chamber wall 1 by a cover plate 102. The cover plate 102 is effective to maintain a fluid-tight seal between the flow regulation plate 101 and the chamber wall 1.
The flow regulation plate 101 has connection slots 101A in and open to a surface of the flow regulation plate 101, the surface facing the lobed chamber. The connection slots 101A correspond to the lobes of the lobed chamber. FIG. 12 is a top view of an exemplary flow regulation plate 101 with the chamber wall 1 and the piston 2 overlaid thereon. At some rotational positions of the flow regulation plate 101 relative to the chamber wall 1, the connection slots 101A connect the enclosed space 203 as a compression chamber and the enclosed space 204 as an intake chamber (e.g., 101A′′ in FIG. 12, which is one of the slots 101A), effectively reducing the volume of the enclosed space 203. When the enclosed space 203 and the enclosed space 204 are connected by the connection slots 101A, fluid can flow between the enclosed spaces 203 and 204 through the connection slots 101A. By changing the rotational position of the flow regulation plate 102 relative to the chamber 1, the duty cycle of the connection between the enclosed spaces 203 and 204, and the amount of fluid in the enclosed space 203, can adjusted. The rotational movement of the flow regulation plate 101 can be driven by any suitable mechanism. For example, the flow regulation plate 101 can have a lever slot 101B engaged with a drive pole 103A of a flow regulation lever 103. The flow regulation plate 101 can have an oil channel 101C for delivery of lubricant between the flow regulation plate 101 and the piston 2. The oil channel 101C can be fluidly connected to a four-way solenoid valve 108.
The piston 2 has the seal plate 2B fixed to a main body 2C of the piston 2. The main body 2C of the piston 2 can be viewed as a boss extending from the seal plate 2B into the lobed chamber. The term “main body 2C” and “boss 2C” are used interchangeable here after. The height of the boss 2C and the depth of the lobed chamber are substantially equal so as to form seals between the piston 2 and the chamber wall 1 and between the piston 2 and the flow regulation plate 101. The piston 2 also has a blind bearing hole open from the seal plate 2B, and an oil channel 2D connecting the blind bearing hole to an end surface of the boss 2C.
The transportation plate 3 is rotatably attached to the chamber wall 1 by any suitable mechanism. For example the transportation plate 3 can be retained in a recess in a support 31 and urged against the chamber wall 1 by the support 31. The holes 3A can have a cross-sectional shape of a nozzle, i.e., the opening of the holes 3A open to the lower chamber 40 is larger in area than the opening of the holes 3A facing the seal plate 2B. Such cross-sectional shape of the holes 3A can be effective to lower the fluid flow speed through the holes 3A and decrease fluid flow resistance. The rotation of the transportation plate 3 can be drive by any suitable mechanism. For example, the transportation plate 3 can have a lever slot 3B engaged with a drive pole 105A of a pre-compression ratio regulation lever 105, for driving the transportation plate. Rotation of the transportation plate 3 and rotation of the flow regulation plate 101 are linked, which maintains the pre-compression ratio despite change of the volume of the enclosed space 203 effected by the flow regulation plate 101. The term “pre-compression ratio” as used herein means the pressure ratio of compressed fluid in the compression chamber to uncompressed fluid at the moment when the holes 2A begins to overlap with the holes 3A. The rotation of the flow regulation plate 101 and the transportation plate 103 can be linked by any suitable mechanism. In one example, as shown in FIG. 11 and FIG. 13, a drive lever 106 is connected with a slider 107A of a hydraulic actuator 107 and lever axle 104, to transfer the from slide 107A to lever axle 104. The hydraulic actuator 107 controls the slider 107A and drives the lever axle 104 to rotate. The lever axle 104 is connected to the flow regulation lever 103 and the pre-compression ratio regulation lever 105.
As shown in FIG. 12, the piston 2 translates along a circular path 150 counterclockwise around the symmetry center axis of the chamber wall 1. The upper panel of FIG. 12 demonstrates a state without flow regulation, wherein the connection slots 101A of the flow regulation plate 101 are not fluidly connected to any enclosed space 203 and thus have no influence to compression in the enclosed space 203. OA is an initial angular position of one of the connection slots 101A; OB is an initial angular position of one of the holes 3A. The lower panel of FIG. 12 demonstrates a state with flow regulation. Compared to the state shown in the upper panel of FIG. 12, the flow regulation plate 101 rotates around the symmetry center axis of the chamber wall 1 by an angle AOA′; and the transportation plate 3 rotates around the symmetry center axis of the chamber wall 1 by an angle is BOB′. Angle AOA′ is preferably greater than angle BOB′. In the state of the lower panel of FIG. 12, when the enclosed space 203 as the compression chamber forms and the enclosed space 204 as the intake chamber are connected through the connection slot 101A′′ and thus the fluid inside the enclosed space 203 is not compressed and flows into the enclosed space 204 as the piston 2 translates. When the piston 2 translates to a position wherein the connection slot 101A′′ is no longer connected to both the enclosed spaces 203 and 204, the fluid inside the enclosed space 204 begins to be compressed. Rotation of the transportation plate 3 and the flow regulation plate 101 are synchronized such that a nearly constant pre-compression ratio is maintained, which leads to high compression efficiency.
The support 31 is fixed with the shell 8, and has holes 31A corresponding to and fluidly connected to the holes 3A. Fluid discharged from the holes 3A flows through the holes 31A into the chamber 40. High pressure fluid in the lower chamber 40 exerts force through holes 31A and 3A onto the transportation plate 3 and the seal plate 2B, pushes the transportation plate 3 against the piston 2, and pushes the piston 2 against the chamber wall 1, which enhances seal of between the transportation plate 3 and the piston 2, and seal of between the chamber 1 and the piston 2.
The four-way solenoid valve 108 is used to control the action of the hydraulic actuator 107. When the four-way solenoid valve 108 is not powered, hydraulic fluid is blocked inside the hydraulic actuator 107 and the slider 107A of the hydraulic actuator 107 is locked. When an increment solenoid of the four-way solenoid valve 108 is powered, the oil channel 101C, which delivers high pressure lubricant (e.g., hydraulic oil) is fluidly connected with an oil chamber 107B of the hydraulic actuator 107; an oil chamber 107C is fluidly connected with an oil channel 1D, which delivers low pressure oil. The pressure differential in the oil chambers 107B and 107A causes the slider 107A to move away from the oil chamber 107B, which turns the flow regulation plate 101 and the transportation plate 3 counterclockwise in FIG. 13. When a decrement solenoid of the four-way solenoid valve 108 is powered, the oil channel 101C, which delivers high pressure lubricant (e.g., hydraulic oil) is fluidly connected with the oil chamber 107C of the hydraulic actuator 107; the oil chamber 107B is fluidly connected with an oil channel 1D, which delivers low pressure oil. The pressure differential in the oil chambers 107B and 107A causes the slider 107A to move towards the oil chamber 107B, which turns the flow regulation plate 101 and the transportation plate 3 clockwise in FIG. 13.
A driving shaft 5 is operably connected with a rotor 6A of an electric motor 6. An oil channel through the driving shaft 5 opens at opening 5A at one end of the driving shaft 5 and at opening 5B at another end of the driving shaft 5.
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
The shell 8 which is fixed to transportation plate 3 and chamber wall 1, is part of an shell that encloses the chamber wall 1, piston 2, transportation plate 3, and has at least one fluid inlet 9 and at least one outlet 11.
Low temperature fluid flows through the inlet 9 into a chamber 30 inside the shell 8, through the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency. Fluid discharged from the lobed chamber flows through holes 2A of piston 2 and holes 3A of transportation plate 3 into a chamber 40, through the motor 6 so as to cool the motor 6, into a chamber 50, through a space 8B between the motor 6 and the shell 8 and finally is exhausted through the outlet 11.
The fluid in the chamber 50 produces high force on the surface of the oil in an oil pool 8D and causes the oil to flow into the driving shaft oil channel opening 5A which is submerged in the oil. The oil reaches another end 5B of the driving shaft 5. Some of the oil flows through a gap in a bearing in the bearing shaft of the piston 2 and into a gap between the transportation plate 3 and the seal plate 2B so as to reduce friction therebetween. Some of the oil flows through the oil channel 2D of piston 2 and into a gap between the boss 2C and the chamber wall 1, a gap between the boss 2C and the flow regulation plate 101, and the lobed chamber, so as to reduce friction between the piston 2 and the chamber wall 1 and the flow regulation plate 101, and cool the chamber wall 1, piston 2 and flow regulation plate 101. The oil flows through the holes 3A and returns to the oil pool 8D. The oil is also fed through the oil channel 101C to drive the hydraulic actuator 107.
When the oil flows through the oil channel 2D into the lobed chamber, and the fluid in the lobed chamber is compressed, the piston 2 can be urged to move axially away from the chamber wall 1, which can break the seal between the chamber wall 1 and the piston 2 and cause leakage. High pressure fluid in the lower chamber 40 exerts force through holes 3A onto the seal plate 2B and pushes the piston 2 against the chamber wall 1, which enhances seal of between the chamber 1 and the piston 2 and between the piston 2 and the flow regulation plate 101.
FIG. 14 is a vertical sectional view of a device according to an embodiment. In this embodiment, the channels 1A are located through a side wall of the chamber wall 1, connecting the outer surface and inner surface of the chamber wall 1.
The piston 2 has the seal plate 2B fixed to a main body 2C of the piston 2. In this embodiment, the seal plate 2B does not have through holes thereon (e.g., no holes 2A in prior embodiments). The main body 2C of the piston 2 can be viewed as a boss extending from the seal plate 2B into the lobed chamber. The term “main body 2C” and “boss 2C” are used interchangeable here after. The height of the boss 2C and the depth of the lobed chamber are substantially equal so as to form seals between the piston 2 and the chamber wall 1. The piston 2 also has a blind bearing hole open from the seal plate 2B, and an oil channel 2D connecting the blind bearing hole to an end surface of the boss 2C.
The chamber wall 1 in this embodiment has holes 1E through the end surface of the chamber wall 1. The holes 1E are fluidly connected to the lobed chamber and are configured for fluid in the lobed chamber to discharge through the holes 1E into chamber 40.
The holes 1E have a suitable mechanism (e.g., a one-way valve or an elastic seal 12 at an opening of the holes 1E) therein configured to allow fluid discharge from the lobed chamber into chamber 40 and to prevent fluid flow from chamber 40 into the lobed chamber. For example, the elastic seal 12 can bend toward chamber 40 so as to open the holes 1E to allow fluid discharge from the lobed chamber into chamber 40; the elastic seal 12 can bend away from chamber 40 (i.e. towards the holes 1E) so as to seal the holes 1E to prevent fluid flow from chamber 40 into the lobed chamber. Preferably, a stopper plate 14 is attached to the chamber wall 1 and configured to limit bending of the elastic seal 12. Holes 300A of a support 300 is fluidly connected to a lower chamber 50.
The piston 2 is urged against the chamber wall 1 so as to provide a seal between the seal plate 2B and the chamber wall 1, and between the main body 2C and the end surface of the chamber wall 1. In one example, a ring 18 is disposed between the support 300 and the seal plate 2B. The ring 18 is configured to allow motion of the piston 2 relative to the support 300 and to urge the piston 2 against the chamber wall 1. Other suitable mechanism may be used in conjunction with or as an alternative to the ring 18.
A driving shaft 5 is operably connected with a rotor 6A of an electric motor 6. An oil channel through the driving shaft 5 opens at opening 5A at one end of the driving shaft 5 and at opening 5B at another end of the driving shaft 5. Preferably, a pump 5F is mounted to the opening 5A to force oil from the oil pool 8D into the oil channel in the driving shaft 5.
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
A shell 8 which is fixed to chamber wall 1, is part of an shell that encloses the chamber wall 1, piston 2, support 300, and has at least one fluid inlet 9A and at least one outlet 11A.
Low temperature fluid flows through the inlet 9A into lower chamber 50 inside the shell 8, through the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency. Fluid discharged from the lobed chamber flows through holes 1E of chamber wall 1 into chamber 40, and is exhausted through the outlet 11A.
The pump 5F causes the oil to flow into the driving shaft oil channel opening 5A which is submerged in the oil. The oil reaches another end 5B of the driving shaft 5. Some of the oil flows through a gap in a bearing in the bearing shaft of the piston 2 and into a gap between the support 300, the ring 18 and the seal plate 2B so as to reduce friction therebetween. Some of the oil flows through the oil channel 2D of piston 2 and into a gap between the boss 2C and the chamber wall 1 and the lobed chamber so as to reduce friction between the piston 2 and the chamber wall 1, and cool the chamber wall 1 and piston 2. The oil flows through the holes 300A and returns to the oil pool 8D.
FIG. 15 is a vertical sectional view of a device according to an embodiment. In this embodiment, the channels 1A are located through a side wall of the chamber wall 1, connecting the outer surface and inner surface of the chamber wall 1. The channels 1A′ can also be located through an end surface of the chamber wall 1 shown in FIG. 5.
The piston 2 in this embodiment does not have the seal plate 2B fixed to a main body 2C of the piston 2. The piston 2 has a blind bearing hole open from a surface facing away from the end surface of the chamber wall 1, and an oil channel 2D connecting the blind bearing hole to an end surface of the boss 2C.
The holes 3A of the transportation plate 3 is fluidly connected to a lower chamber 40. The holes 3A are fluidly connected to the lobed chamber. The holes 3A have a suitable mechanism (e.g., a one-way valve or an elastic seal 12) therein configured to allow fluid discharge from the lobed chamber into chamber 40 and to prevent fluid flow from chamber 40 into the lobed chamber. For example, the elastic seal 12 can bend toward chamber 40 so as to open the holes 3A to allow fluid discharge from the lobed chamber into chamber 40; the elastic seal 12 can bend away from chamber 40 so as to seal the holes 3A to prevent fluid flow from chamber 40 into the lobed chamber. Preferably, a stopper plate 14 is attached to the transportation plate 3 and configured to limit bending of the elastic seal 12. In this embodiment, the transportation plate 3 is fixed on the chamber wall 1 and retains the piston 2 in the lobed chamber.
A driving shaft 5 is operably connected with a rotor 6A of an electric motor 6. An oil channel through the driving shaft 5 opens at opening 5A at one end of the driving shaft 5 and at opening 5B at another end of the driving shaft 5.
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. Preferably, the upper portion 5C does not extend to the full depth of the blind bearing hole of the piston 2. Namely, there is a gap between the upper portion 5C and an end surface of the blind bearing hole. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150. A lower portion of the driving shaft is supported by a support 7.
The piston 2 may have a recess 2F on a surface engaging the end surface of the chamber wall 1. The recess 2F may be configured to accommodate oil from the oil channel 5B. The oil in the recess 2F balances pressure from the oil in the gap between the upper portion 5C and the end surface of the blind bearing hole, to reduce the force urging the piston 2 against the chamber wall 1, and thus to reduce friction between the piston 2 and chamber wall 1.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
A shell 8 which is fixed to chamber wall 1, is part of an shell that encloses the chamber wall 1, piston 2, transportation plate 3, and has at least one fluid inlet 9A and at least one outlet 11A.
Low temperature fluid flows through the inlet 9A into a chamber 50 and then flows through the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency. Fluid discharged from the lobed chamber flows through holes 3A of transportation plate 3 into a chamber 40, and finally is exhausted through the outlet 11A.
The fluid in the chamber 40 produces high force on the surface of the oil in an oil pool 8D and causes the oil to flow into the driving shaft oil channel opening 5A which is submerged in the oil. The oil reaches another end 5B of the driving shaft 5. Some of the oil flows through an opening 5E into a gap between the driving shaft 5 and the support 7.
Some of the oil flows through a gap in a bearing in the bearing shaft of the piston 2 and into a gap between the transportation plate 3 and the piston 2 so as to reduce friction therebetween. Some of the oil flows through the oil channel 2D of piston 2 and into a gap between the piston 2 and the chamber wall 1 and the lobed chamber so as to reduce friction between the piston 2 and the chamber wall 1, and cool the chamber wall 1 and piston 2. The oil flows through the holes 3A and returns to the oil pool 8D.
FIG. 16B is a vertical sectional view of a device according to an embodiment. In this embodiment, the channels 1A are located through a side wall of the chamber wall 1, connecting the outer surface and inner surface of the chamber wall 1. The channels 1A′ can also be located through an end surface of the chamber wall 1 shown in FIG. 5.
The piston 2 in this embodiment does not have the seal plate 2B fixed to a main body 2C of the piston 2. The piston 2 has a blind bearing hole open from a surface facing away from the end surface of the chamber wall 1, and an oil channel 2D connecting the blind bearing hole to an end surface of the boss 2C.
The transportation plate 3 may be fixed on the chamber wall 1 and retains the piston 2 in the lobed chamber. The transportation plate 3 is configured to accommodate a plurality of gears 322 thereon. In an embodiment, the plurality of gears are rotatably positioned in a plurality of holes in the transportation plate 3. The plurality of gears can be coupled to the transportation plate 3 through any suitable bearings. The gears 322 may be supported by any suitable structure such as a support 33. The gears 322 comprise a through holes 322A. Preferably, the number of the gears 322 is equal to the number of lobes of the piston 2.
The support 33 can have holes 33A fluidly connected to a lower chamber 40. The holes 33A may be fluidly connected to the lobed chamber through the through holes 322A in the gears 322.
A driving shaft 5 is operably connected with a rotor 6A of an electric motor 6. An oil channel through the driving shaft 5 opens at opening 5A at one end of the driving shaft 5 and at opening 5B at another end of the driving shaft 5. The driving shaft 5 has teeth 5G meshing with teeth 322B on the gears 322 such that when the driving shaft 5 rotates, the gears 322 is driven to rotate.
FIG. 16A shows a top view of the device and illustrates the spatial relationship of the through holes 322A and the lobed chamber. The through holes 322A are off center of the gears 322. The gears 322 and the through holes 322A are configured such that a gear 322 rotates to a position where the through hole 322A in this gear 322 is fluidly connected to an enclosed space 204 after the enclosed space 204 forms (preferably after fluid in the enclosed space 204 has been pre-compressed) by the translation motion of the piston 2 relative to the chamber wall 1. Fluid in the enclosed space 204 may discharge therefrom through the through hole 322A. The through hole 322A remains fluidly connected to the enclosed space 204 until essentially all fluid in the enclosed space 204 has discharged therefrom. The through holes 322A are not limited to a circular cross-section but may have any suitable cross-sectional shape. The gears 322 preferably rotate by a full revolution when the piston 2 translates along the circular path 150 once. Of course, the gears 322 are only an example. One of ordinary skill in the art will appreciate that other suitable mechanism may be effective to render a through hole fluidly connected to an enclosed space only when fluid in the enclosed space is being compressed.
An upper portion 5C of the driving shaft 5 is disposed in the blind bearing hole of the piston 2 and rotatably connected to the piston 2 through a bearing. Preferably, the upper portion 5C does not extend to the full depth of the blind bearing hole of the piston 2. Namely, there is a gap between the upper portion 5C and an end surface of the blind bearing hole. An axis of the upper portion 5C is displaced from an axis of the driving shaft 5. The upper portion 5C converts the rotational movement of the driving shaft 5 to the translation of the piston 2 along a circular path 150. A lower portion of the driving shaft is supported by a support 7.
The piston 2 may have a recess 2F on a surface engaging the end surface of the chamber wall 1. The recess 2F may be configured to accommodate oil from the oil channel 5B. The oil in the recess 2F balances pressure from the oil in the gap between the upper portion 5C and the end surface of the blind bearing hole, to reduce the force urging the piston 2 against the chamber wall 1, and thus to reduce friction between the piston 2 and chamber wall 1.
A counterweight 4 is connected to the driving shaft 5 to counter centrifugal force caused by translation of the piston 2 that is eccentric relative to the driving shaft 5 and to reduce vibration.
A shell 8 which is fixed to chamber wall 1, is part of an shell that encloses the chamber wall 1, piston 2, transportation plate 3, and has at least one fluid inlet 9A and at least one outlet 11A.
Low temperature fluid flows through the inlet 9A into a chamber 50 and then flows through the channel 1A of chamber wall 1, into the lobed chamber. The low temperature fluid can be effective to cool the chamber wall 1 and the piston 2 and reduce the temperature of the fluid in the lobed chamber and increase compression efficiency.
Fluid discharged from the lobed chamber flows through holes 322A of gears 322 and holes 33A of support 33 into a chamber 40, and finally is exhausted through the outlet 11A.
The fluid in the chamber 40 produces high force on the surface of the oil in an oil pool 8D and causes the oil to flow into the driving shaft oil channel opening 5A which is submerged in the oil. The oil reaches another end 5B of the driving shaft 5. Some of the oil flows through an opening 5E into a gap between the driving shaft 5 and the support 7. Some of the oil flows through a gap in a bearing in the bearing shaft of the piston 2 and into a gap between the transportation plate 3 and the piston 2 so as to reduce friction therebetween. Some of the oil flows through the oil channel 2D of piston 2 and into a gap between the piston 2 and the chamber wall 1 and the lobed chamber so as to reduce friction between the piston 2 and the chamber wall 1, and cool the chamber wall 1 and piston 2. The oil flows through the holes 3A and returns to the oil pool 8D.
A method of generating mechanical power using the device described herein comprises maintaining a pressure differential between openings of the holes 3A of the transportation plate 3 and openings of the channels 1A of the chamber wall 1.
A method of compressing and/or driving a fluid using the device described herein, comprises providing the fluid to the channels 1A of the chamber wall 1 and driving the translation of the piston 2.
In relation to the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim.
The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made without departing from the scope of the claims set out below.

## Claims

1. A device comprising:
a chamber wall comprising an outer surface and an inner surface, wherein the inner surface encloses a lobed chamber with a plurality of lobes and the inner surface comprises segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments, and wherein the chamber wall further comprises channels connecting the outer surface and the inner surface of the chamber wall and/or channels through an end surface of the chamber wall;
a piston configured to translate along a circular path relative to the chamber wall and form enclosed spaces between the piston and the chamber wall; and
holes fluidly connected to the lobed chamber and configured to allow fluid discharge from the lobed chamber through the holes and to prevent fluid flow into the lobed chamber through the holes;
wherein the piston comprises an outer surface enclosing a main body of the piston, the main body having a plurality of lobes located in the lobes of the lobed chamber, the outer surface of the piston and the inner surface of the chamber wall engaged during translation and forming a fluid-tight seal between some portions of the outer surface of the piston and the inner surface of the chamber wall;
wherein the main body of the piston and the lobed chamber have a same number of lobes.

2. The device of claim 1, wherein the piston does not rotate relative to the chamber wall during translation.

3. The device of claim 1, wherein the outer surface of the piston comprises segments of arcuate surfaces, each of the segments of arcuate surfaces being tangent with its immediate neighboring segments.

4. The device of claim 1, further comprising an anti-rotation part operable to prevent rotation of the piston during the translation of the piston along the circular path.

5. The device of claim 1, wherein the circular path is concentric with a rotational symmetric center of the chamber wall.

6. The device of claim 1, wherein the piston comprises an oil channel fluidly connected to the lobed chamber, the oil channel configured to provide oil into the lobed chamber for lubrication and cooling.

7. The device of claim 1, wherein the holes are disposed through an end surface of the chamber wall.

8. The device of claim 1, wherein the holes comprises a one-way valve.

9. The device of claim 1, wherein the piston comprises a recess on a surface of the piston, wherein the surface abuts the end surface of the chamber wall.

10. The device of claim 1, further comprising an elastic seal at an opening of the holes.

11. The device of claim 10, further comprising a stopper plate configured to limit bending of the elastic seal.

12. The device of claim 1, further comprising a transportation plate wherein the transportation plate is fixed on the chamber wall and retains the piston in the lobed chamber.

13. The device of claim 12, wherein the holes are disposed through the transportation plate.

14. The device of claim 1, further comprising a shaft wherein an upper portion is rotatably connected to the piston and an axis of the upper portion is displaced from an axis of the shaft.

15. The device of claim 14, further comprising a chamber between a bottom of the piston and the shaft, wherein the piston comprises a recess on a surface of the piston, the surface abutting the end surface of the chamber wall.

16. The device of claim 15, further comprising a hole fluidly connected to the chamber and another hole fluidly connected to the recess.

17. A device comprising:
a chamber wall comprising an outer surface and an inner surface, wherein the inner surface encloses a lobed chamber with a plurality of lobes and the inner surface comprises segments of arcurate surfaces, each of the segments of arcurate surfaces being tangent with its immediate neighboring segments, and wherein the chamber wall further comprises channels connecting the outer surface and the inner surface of the chamber wall and/or channels through an end surface of the chamber wall;
a piston configured to translate along a circular path relative to the chamber wall and form enclosed spaces between the piston and the chamber wall; and
a through hole configured to fluidly connect to the enclosed spaces only when fluid in the enclosed spaces are being compressed;
wherein the position and the lobed chamber have a same number of lobes.

18. The device of claim 17, further comprising a gear wherein the through hole is disposed through the gear and is off center of the gear.

19. The device of claim 18, wherein the gear is configured to rotate by a full revolution when the piston translates along a circular path once relative to the chamber wall.

20. The device of claim 18, further comprising a shaft wherein an upper portion is rotatably connected to the piston and an axis of the upper portion is displaced from an axis of the shaft.

21. The device of claim 20, wherein the shaft comprises teeth meshing with teeth on the gear.