Patent Grant
11506056
The present invention relates to rotary machines, particularly rotary compressors, pumps or expansion engines in which at least one rotor has planetary motion within a housing.
Rotary machines, in which at least one rotor has planetary motion within a housing, can be employed, for example, as rotary compressors, pumps (including positive displacement pumps, dynamic pumps and vacuum pumps) or expansion engines.
Conventional rotary machines can have one or more rotors. Various shapes of rotors are known, including circular, elliptical, triangular and, in some cases, the rotors incorporate vanes. Vanes can be mounted on a rotor in a housing, and can be of variable length or urged to maintain contact with the interior surface of the housing as the rotor rotates. The housing for the rotor is most commonly cylindrical although other housing shapes such as trochoidal (either hypo- or epitrochoidal) shapes are known. There is a class of rotary machines for which the rotor is trochoidal and the housing is also trochoidal, wherein the housing has one more apex than the rotor. Trochoidal shapes can be generated by tracing a point on the circumference of a first circle as it is rolled around the circumference of a second circle either on the inside (producing a hypotrochoidal shape) or outside (producing an epitrochoidal shape).
A configuration in which the housing (or an outer rotor) has one more apex (or tooth) than the inner rotor is known as a generated rotor or gerotor. A gerotor is a positive displacement pump and can comprise a trochoidal inner rotor and an outer rotor formed by a circle with intersecting arcs.
Various gerotor configurations can be designed by rotating an inner rotor about a first point moving in a circle about a second point wherein the second point is fixed. The inner rotor can comprise two or more apexes, and can rotate in the same direction or in the opposite direction as the rotation of the first point about the second point. The relative rotational rates of the rotor and the first point about the second point can be adjusted to achieve a desired gerotor configuration.
Rotary pumps are known devices that can move a fluid from one place to another. There is a wide range of end uses for rotary pumps including irrigation, fire-fighting, flood control, water supply, gasoline supply, refrigeration, chemical movement and sewage transfer.
Rotary pumps are typically positive displacement pumps comprising a fixed housing, gears, cams, rotors, vanes and similar elements. Rotary pumps usually have close running clearances, do not require suction or discharge valves, and are often lubricated only by the fluid being pumped.
A positive displacement pump moves the fluid by trapping a volume of fluid and forcing the trapped volume into a discharge pipe. Some positive displacement pumps employ an expanding cavity on the suction side and a decreasing cavity on the discharge side. Fluid flows into the pump as the cavity on the suction side expands and the fluid flows out of the discharge pipe as the cavity collapses. The output volume is the same for each cycle of operation. Theoretically, a positive displacement pump can produce the same flow rate at a given pump speed regardless of the discharge pressure.
A rotodynamic pump is a kinetic machine in which energy is imparted continuously to the fluid by means of a rotating impeller, propeller, or rotor.
Rotary machines, such as those described above, can be designed for various applications. The design and configuration of rotary machines can offer particular advantages for certain applications. For example, rotary pumps, such as those described above, can be designed for various applications with suitable capacity and discharge pressure. The design and configuration of rotary pumps can offer particular advantages, such as high volumetric efficiency, for certain applications.
A rotary machine comprises:
The housing cavity inner surface further comprises a first cut-out formed therein that extends circumferentially and is fluidly connected to one of the inlet or the outlet.
Upon connecting the inlet to a fluid source, rotation of the rotor draws fluid into a space formed between the rotor and the housing cavity inner surface and discharges the fluid from the outlet.
The housing inner surface can further comprise a second cut-out, wherein the first cut-out is fluidly connected to the inlet and the second cut-out is fluidly connected to the outlet. In some embodiments, the first cut-out can be configured to increase the amount of fluid drawn via the inlet into the space formed between the rotor and the housing cavity inner surface during rotation of the rotor. In some embodiments, the second cut-out is configured to reduce mechanical restraint of the rotor during discharge of an incompressible fluid via the outlet. The cut-outs can be connected to the housing cavity inner surface by a transition region.
In preferred embodiments of the rotary machine, the crankshaft induces rotation of the rotor about the second axis of rotation at a second angular velocity that is half the first angular velocity.
In some embodiments, the rotary machine further comprises a second rotor comprising an outer surface having an elliptical cross-section, and the second rotor is configured to rotate out of phase with respect to the first rotor.
In preferred embodiments of the rotary machine, the crankshaft is connected to a drive assembly for rotating the crankshaft at a rotational rate that varies during the period of each rotation of the crankshaft. In some embodiments the drive assembly can comprise a motor, a driveshaft and a universal joint. The driveshaft of the motor is configured to rotate at a substantially constant rate, and the universal joint is configured to provide a variation in the rotational rate of the crankshaft. In other embodiments, the drive assembly comprises transmission comprising a non-circular gearing mechanism, with the non-circular gearing mechanism configured to provide a variation in the rotational rate of the crankshaft.
In preferred embodiments of the rotary machine, the inverse apex region comprises a dynamic apex seal.
A rotary pump comprises:
The housing interior cavity is substantially circular in cross-section and comprises an interiorly-extending inverse apex region between the inlet and the outlet. The inverse apex region is in contact with the rotor during rotation of the rotor thereby providing separation between the inlet and the outlet.
Upon connecting the inlet to a fluid source, rotation of the rotor draws fluid into a space formed between the rotor and the housing cavity inner surface and discharges the fluid from the outlet.
In a preferred embodiment, the crankshaft induces rotation of the rotor about the second axis of rotation at a second angular velocity that is half the first angular velocity.
In a preferred embodiment, the rotor has a pair of oppositely disposed tips, the rotor tips separated by a distance that provides a substantially continuous gap between the tips and the housing cavity inner surface.
In some embodiments, the housing cavity inner surface has a first cut-out formed therein that extends circumferentially and is fluidly connected to one of the inlet or the outlet.
In some embodiments, the pump can further comprise a second rotor comprising an outer surface having an elliptical cross-section. The second rotor is preferably configured to rotate out of phase with respect to the first rotor.
In preferred embodiments of the rotary pump, the crankshaft is connected to a drive assembly for rotating the crankshaft at a rotational rate that varies during the period of each rotation of the crankshaft. In some embodiments the drive assembly can comprise a motor, a driveshaft and a universal joint. The driveshaft of the motor is configured to rotate at a substantially constant rate, and the universal joint is configured to provide a variation in the rotational rate of the crankshaft. In other embodiments, the drive assembly comprises transmission comprising a non-circular gearing mechanism, with the non-circular gearing mechanism configured to provide a variation in the rotational rate of the crankshaft.
In preferred embodiments, the inverse apex region comprises a dynamic apex seal.
The rotary pump can further comprise at least one lining disposed along at least a portion of the housing cavity inner surface. The lining can be formed of a material that is less abradable than the housing cavity inner surface. The lining can have uniform or non-uniform thickness.
An improved rotary machine directs a quantity of fluid from an inlet to an outlet. The apparatus comprises:
In a preferred embodiment, the crankshaft induces rotation of the rotor about the second axis of rotation at a second angular velocity that is half the first angular velocity.
In a preferred embodiment, the rotor has a major axis ending in pair of oppositely disposed tips, and the rotor tips contact the housing interior surface. Alternatively, the rotor tips can be spaced from the housing interior surface.
In a preferred embodiment, the inlet is formed within the housing for introducing the fluid quantity into the interior cavity and the outlet is formed within the housing for discharging the fluid quantity from the interior cavity. Rotation of the rotor about the second axis of rotation preferably divides the interior cavity into three separate chambers during at least a portion of the revolution of the rotor about the second axis of rotation. Preferably, the fluid quantity is introduced via the inlet into one of the chambers and substantially all of the fluid quantity is discharged from the one of the chambers upon completion of the one revolution of rotation, thereby fully scavenging the fluid quantity from the interior chamber.
In a preferred embodiment, the housing has a through-hole formed therein for introducing fluid into the interior cavity, and the rotor superimposes the through-hole during the one revolution of rotation. The rotor can have at least one interior chamber formed therein such that the rotor interior chamber fluidly communicates with the through-hole when the rotor interior chamber superimposes the through-hole. The fluid introduced via the through-hole can have a composition that is different from the composition of the fluid introduced to the interior chamber via the inlet.
An improved method directs a quantity of fluid from an inlet to an outlet. The method comprises:
In a preferred method embodiment, the crankshaft induces rotation of the rotor about the second axis of rotation at a second angular velocity that is half the first angular velocity.
In a preferred method embodiment, the rotor has a major axis ending in pair of oppositely disposed tips, and the rotor tips contact the housing interior surface. Alternatively, the rotor tips can also be spaced from the housing interior surface.
In a preferred method embodiment, the inlet is formed within the housing for introducing the fluid quantity into the interior cavity and the outlet is formed within the housing for discharging the fluid quantity from the interior cavity. The fluid quantity is preferably introduced via the inlet into one of the chambers and substantially all of the fluid quantity is discharged from the one of the chambers upon completion of the one revolution of rotation, thereby fully scavenging the fluid quantity from the interior chamber.
In a preferred method embodiment, the housing has a through-hole formed therein for introducing fluid into the interior cavity, and the rotor superimposes the through-hole during the one revolution of rotation. The rotor preferably has at least one interior chamber formed therein such that the rotor interior chamber fluidly communicates with the through-hole when the rotor interior chamber superimposes the through-hole. The fluid introduced via the through-hole can have a composition that is different from the composition of the fluid introduced to the interior chamber via the inlet.
An improved rotary pump comprises:
Upon connecting the inlet to a fluid source, rotation of the rotor draws fluid into a space formed between the rotor and the housing cavity inner surface and discharges the fluid from the outlet.
In a preferred embodiment, the rotary pump, the crankshaft induces rotation of the rotor about the second axis of rotation at a second angular velocity that is half the first angular velocity.
In another preferred embodiment, the rotor has a pair of oppositely disposed tips, and the rotor tips are separated by a distance that provides a substantially continuous gap between the tips and the housing cavity inner surface.
In another preferred embodiment, the housing cavity inner surface has an interiorly-extending inverted apex portion between the inlet and the outlet and a pair of cut-outs formed therein adjacent the inlet and the outlet. The cut-outs extending circumferentially away from the inverted apex portion and axially between the front plate and the rear plate. The cut-outs can extend partially between the front plate and the rear plate. Each of the cut-outs can be connected to the housing cavity inner surface by a transition portion. In this embodiment, the rotor preferably has a pair of oppositely disposed tips, the rotor tips separated by a distance that provides a substantially continuous gap between the tips and the housing cavity inner surface.
In another preferred embodiment, the rotary pump further comprises at least one lining disposed along at least a portion of the housing cavity inner surface. The at least one lining is preferably formed of a material that is less abradable than the housing cavity inner surface. The at least one lining can be replaceable. The at least one lining can be a plurality of stacked linings, each of the linings having a thickness such that when stacked an adjustable gap is formed between the elliptical rotor tips and the housing cavity inner surface. The linings can have a uniform thickness or thicknesses that vary such that the gap differs in radial distance at different locations along the housing cavity inner surface.
In another preferred embodiment, the rotor has a circumferential edge, and the rotary pump further comprises a compressible seal disposed around the elliptical rotor circumferential edge.
In another preferred embodiment, the elliptical rotor has a front face and a rear face and the elliptical rotor further comprises at least one friction feature disposed on at least one of the elliptical rotor front face and rear face. The at least one friction feature is preferably formed of abradable material.
In another embodiment, the rotary pump further comprises a second elliptical rotor capable of undergoing eccentric rotation within the housing interior cavity, and the elliptical rotors are separated within the housing interior cavity by a central plate. The rotary pump can further comprise a valve operatively associated with the central plate for relieving internal pressure within a volume defined by at least a portion of the housing cavity on one side of the central plate to a volume defined by at least a portion of the housing cavity on the other the of the central plate.
In another embodiment, the rotary pump further comprises a valve for relieving internal pressure within a volume defined by at least a portion of the housing cavity. The valve can be a one-way sprung check valve.
In another preferred embodiment, the inverse apex is hinged and biased such that the inverse apex is rotatable away from a position substantially perpendicular to a tangent to the housing cavity inner surface to form a gap between the housing cavity inner surface and the elliptical rotor, thereby relieving pressure in an adjacent volume formed in the housing cavity.
Another improved rotary pump comprising:
Upon connecting the inlet to a fluid source, rotation of the rotor draws fluid into a space formed between the rotor and the housing cavity inner surface and discharges the fluid from the outlet.
An improved method directs fluid from an inlet to an outlet formed in a housing having an interior cavity. The method comprises:
The housing interior cavity comprises an inner surface having a cross-sectional profile defined by a locus of a set of points on the rotor outer surface for which an instantaneous velocity vector is perpendicular to a line drawn from a member of the set of points to the second axis of rotation as the rotor completes one revolution of rotation.
Rotation of the rotor draws the fluid into a space formed between the rotor and the housing cavity inner surface and discharges the fluid from the outlet.
Another improved method directs fluid from an inlet to an outlet formed in a housing having an interior cavity encased by a front plate and a rear plate attached at opposite sides of the housing. The method comprises:
The housing interior cavity comprising an interiorly-extending inverted apex portion between the inlet and the outlet.
Rotation of the rotor draws the fluid into a space formed between the rotor and the housing cavity inner surface and discharges the fluid quantity from the outlet.
A rotary machine has a rotor with at least two rotor apexes. In some embodiments the rotor is elliptical in cross section. The rotor is located in a housing in which it can undergo eccentric rotation when driven by a crankshaft. The rotation of the crankshaft can be an integer multiple of the rotation rate of the rotor and in the same direction of the rotor. In some embodiments with an elliptical rotor, the integer multiple is two.
The rotor is in contact with at least one point of the interior surface of the housing during its rotation and forms multiple chambers from which different inlet and outlet ports can be connected. The rotary machine can also contain a dynamic apex seal which is formed at an inverse apex region of the interior of the housing. In a preferred embodiment, the inverse apex region can be shaped like the arc of a circle. In other embodiments, the inverse apex region can be shaped, among other things, like a portion of a parabolic curve, a portion of a polynomial of degree higher than two, and/or a portion of a sinusoidal curve.
In at least one embodiment, multiple rotors are used in the housing and are configured to rotate out of phase with respect to each other to reduce the variation in the net output flow rate.
In some embodiments, the crankshaft is coupled to a driveshaft of a motor via a universal joint wherein the driveshaft is configured to rotate at a substantially constant rate, and the universal joint is configured to provide a variation in the rotational rate of the crankshaft. Alternatively, or in addition, in some embodiments, the transmission can comprise a non-circular gearing mechanism that is configured to provide a variation in the rotational rate of the crankshaft
In one embodiment, the rotary machine also includes a sun gear, a ring gear, and a mechanical coupling. The ring gear rotates via the mechanical coupling when the crankshaft rotates. The sun gear can contain a protrusion which is configured to connect the sun gear to the rotor via a socket located on the surface of the rotor. In one embodiment the protrusion is a hexagonal key.
The present apparatus and method relate to rotary machines in which at least one rotor has planetary motion within a housing, wherein the housing is shaped to provide advantages for applications including, but not limited to, rotary compressors, positive displacement pumps, dynamic pumps, vacuum pumps and expansion engines.
If angular velocity ω1 is negative, it indicates that rotation of ellipse 110 about center C is in a clockwise direction relative to a frame of reference in which center C is stationary. If angular velocity ω2 is negative, it indicates that rotation of radial arm 120 about fixed end O is in a clockwise direction relative to a frame of reference in which fixed end O is stationary.
Depending on the relative magnitude of ω1 and ω2, ellipse 100 may appear to rotate in a clockwise direction relative to a frame of reference in which fixed end O is stationary even when ω1 and ω2 are both positive.
Circle 130 is the locus of the head of radial arm 120 as it rotates about fixed end O. Line OC is also referred to as the crank arm, and length k is also referred to as the crank radius.
Angular velocities ω1 and ω2 can be different from one another, and can be positive or negative; that is, rotation of ellipse 110 and/or rotation of radial arm 120 can be in a counter-clockwise or clockwise direction.
When angular velocity ω1 is half angular velocity ω2, ellipse 110 rotates half as fast as radial arm 120, and radial arm 120 completes two full revolutions for each full revolution of ellipse 110. There can be an initial phase lag between the rotations of ellipse 110 and radial arm 120 at the start of rotation. The initial phase lag is an angle describing the phase difference between the rotational motion of ellipse 110 and the rotational motion of radial arm 120. When the initial phase lag is 3π/4 radians (or equivalently 135 degrees), major axis AA of ellipse 210 is horizontal when radial arm 120 is vertical, with center C of ellipse 210 directly below fixed end O of radial arm 120. This is the configuration shown in
In operation, elliptical rotor 210 rotates in a manner as described for ellipse 110 in
The angular velocity (rotational rate) of elliptical rotor 210 about its instantaneous center of rotation R is ω1. The angular velocity of crankshaft 222 is ω2. In the example embodiment of elliptical rotor assembly 200 shown in
In the configuration described above, an instantaneous center of rotation R of elliptical rotor 210 lies at a point 2k from center C of elliptical rotor 210 on a line drawn from center C through the center O of crankshaft 222.
Circle 225 is the circumference of sun gear 220 and is the locus of instantaneous center of rotation R of elliptical rotor 210 as crankshaft 222 rotates.
Rotor tips 240 and 245 are defined as regions on the outer surface of elliptical rotor 210 at or close to the ends of major axis AA. For the purposes of the present description, the rotor tips are defined as places on the outer surface of elliptical rotor 210 that subtend an angle equal to or less than angle D from major axis AA at center C.
The magnitude of angle D varies with the relative lengths of major axis AA and minor axis BB. In an example embodiment, the ratio of major axis AA to minor axis BB can be approximately 1.85 and angle D can be approximately 12 degrees.
The term “rotolliptic motion” is defined to mean the motion of a rotary machine comprising a rotor having two or more rotor apexes (or lobes) and a housing in which the rotor undergoes eccentric rotation driven by a crankshaft, the rotation rate of the crankshaft being substantially an integer multiple of the rotation rate of the rotor, the rotations being in the same direction and the integer multiple being equal to the number of rotor apexes, wherein the rotor is in contact with one or more fixed points or localized regions on the interior surface of the housing throughout its rotation.
Circle 430 is the locus of the instantaneous center of rotation of ellipse 410.
Shape 420 encloses elliptical rotor 210 for all angles of rotation. The instantaneous velocity vector at a given point on ellipse 410 lies perpendicular to a line joining the given point to the instantaneous center of rotation (shown as R in
Shape 420 has three places of contact with ellipse 410 at all angles of rotation; that is for ellipse profiles 410A-410L and all intervening profiles that could be generated by rotation of elliptical rotor 210, with the exception of when the major axis of ellipse 410 is oriented vertically in which case shape 420 has just two points of contact with ellipse 410. Ellipse 410 is always in contact with the “inverse apex” 440.
The asterisks drawn in
As shown in
Region 450 is the region having no ellipse profile lines within it. All points belonging to region 450 lie within all ellipse profiles 410A-410L and all intervening profiles that could be generated by rotation of elliptical rotor 210.
The following paragraphs describe the design and configuration of a rotary machine using the geometry described heretofore in the present application.
Inner surface 525 of housing 520 in cross-section is designed such that at least a portion of each of rotor tips 530 and 535 is in contact with housing surface 525 at all times during a complete revolution of elliptical rotor 510.
Housing surface 525 comprises an inverse apex 540. For operation of assembly 500, it is desirable that inverse apex 540 is in contact with the outer surface of elliptical rotor 510 at all times during a complete revolution of elliptical rotor 510. Referring to the geometry shown in
The contact of elliptical rotor 510 with housing 520 at three positions, as described above, divides the interior volume of housing 520 into three chambers 550, 552 and 554. When elliptical rotor 510 is in contact with housing 520 at only two distinct positions (for example when the major axis of elliptical rotor 510 is oriented vertically), elliptical rotor 510 divides the interior volume of housing 520 into just two chambers.
In some embodiments, housing 520 comprises ports 560 and 565 for inflow and outflow of fluid as desired during operation.
Circular element 518 is the mechanical coupling referred to in the paragraphs describing
For the remainder of the description below for
Herein, the terms horizontal, vertical, front, rear and like terms related to orientation are used in reference to the Figures with the particular orientations illustrated. Nonetheless, the rotary mechanism and rotary machine assemblies described herein can be placed in any orientation suitable for their end use application.
Through-hole 570 is a passage that can be formed through elliptical rotor and housing assembly 500 of
Referring again to
Through-hole 570 does not compromise the integrity of any of the two or three working chambers such as 550, 552 and 554 of assembly 500. There is no path from the interior of through-hole 570 to the interior of working chambers 550, 552 or 554. Therefore, there is no path from the interior of the working chambers to the atmosphere outside assembly 500, and consequently no loss of pressure or fluids that may be contained within the working chambers provided the boundaries of the working chambers are sealed.
In
Through-hole 570 can be used for cooling, lubrication or other suitable purpose. In some embodiments, a first fluid introduced via through-hole 570 has a different composition than a second fluid that passes through working chambers 550, 552 and 554 of assembly 500. In other embodiments, the fluid that passes through working chambers 550, 552 and 554 can be directed through assembly 500 via through-hole 570 either before it enters the working chambers or having been discharged from the working chambers.
In the illustrated embodiment of
In another embodiment, assembly 500 can be designed such that rotor tips 530 and 535 are not always in contact with inner surface 525 of housing 520 during rotation. In this configuration, the rotary machine can, for example, operate as a dynamic pump.
As described in reference to
As described above, inner surface 925 of pump assembly 900 of
Referring to
As rotor 910 rotates clockwise, the volume of chamber 952 of
Housing 920 has an inlet 960 and an outlet 965 for flow of fluid in and out of pump assembly 900 respectively.
Housing 920 has two cut-outs 970 and 975. Cut-outs 970 and 975 are shown in
For pumping compressible fluids, cut-out 970 adjacent to inlet 960 is optional, and has a benefit of reducing a constriction on the flow of fluid into pump 900 through inlet 960. Cut-out 975 is not desirable for pumping compressible fluids because it would allow back-bleed of the fluid being compressed and would impair the ability of pump 900 to be fully scavenging.
For pumping incompressible fluids, cut-outs 970 and 975 are desirable to alleviate unwanted effects at inlet 960 and outlet 965. For example, cut-outs 970 and 975 can alleviate hydrolock, reduce constriction and allow greater flow.
In some embodiments of a pump assembly, elliptical rotor (such as 810 of
The modifications are described in two steps. The first step is illustrated in
Cut-outs 1070 and 1075 in housing 1020A extend the width of rotor 1010 from the front wall of pump assembly 1000A to the rear wall. Cut-out 1070 can be configured to allow chamber 1050 to increase the amount of fluid drawn in via inlet 1060 up to substantially the maximum volume possible in this embodiment. Cut-out 1075 can be configured to reduce mechanical restraint of the rotor when discharging an incompressible fluid via outlet 1065, thereby reducing the likelihood of hydrolock.
Transition regions 1080 and 1085 connect the cut-outs to the remainder of inner surface 1025A.
Elliptical rotor 1110 rotates within housing 1120 in a clockwise direction as indicated by arrow XX.
Elliptical rotor 1110 divides the interior volume of housing 1120 into three chambers 1150, 1152 and 1154 that are not fluidly isolated from one another. Fluid can move between chambers 1150 and 1152, and also between 1150 and 1154, via gaps 1160 and 1162 respectively.
A benefit of rotodynamic pump 1300 over rotodynamic pump 1200 is that, for a given distance between housing inside surface 1325 and the adjacent rotor tip, gap 1360 has a lower cross-sectional area than gap 1260 when gaps 1260 and 1360 have the same height and pumps 1200 and 1300 are dimensioned to have substantially the same volume within housings 1220 and 1320 respectively. The benefit of reducing the cross-sectional area of gap 1360 while maintaining the same volume within the housing of pump 1300 will be discussed in more detail in the following paragraph.
In rotodynamic pump 1300, gap 1360 between housing inside surface 1325 and the adjacent rotor tip is chosen to be large enough so that particles entrained in the fluid (such as in the case of a sludge), will not interfere with rotation of the rotor and will not cause significant gouging or abrading of housing inside surface 1325. Gap 1360 thus allows a deliberate leak of fluid between housing inside surface 1325 and the adjacent rotor tip and thereby degrades performance of the pump. It is therefore desirable for gap 1360 to be large enough to accommodate particles entrained in the fluid while as small as possible to reduce the detrimental impact the gap will have on performance. Having a “thinner” rotor (one with less depth, namely, a smaller W in
Rotolliptic motion can be applied to geometries other than those having elliptical rotors. Rotary machines similar to those described above can comprise a rotor having a non-elliptical shape in cross-section. Examples of such embodiments are described in the following paragraphs.
Shape 1520 encloses near-elliptical rotor 1420 for all angles of rotation. The instantaneous velocity vector at a given point on the outline of the cross-section of near-elliptical rotor 1420 lies perpendicular to a line joining the given point to the instantaneous center of rotation. For a given profile (such as 1510A-1510D and all intervening profiles that could be generated by rotation of near-elliptical rotor 1420), there exists a set of points lying on the profile at which the instantaneous velocity vector is tangential to the profile. The locus of all such sets of points for all profiles describes shape 1520.
Referring again to
As shown in
The smooth transition in inverse apex region 1640 of
Furthermore, when the contact of rotor 1420 of
Additionally, the configuration of the rotary machine having a wide dynamic apex seal with suitable geometry of a near-elliptical rotor and corresponding housing can provide an inherent pressure relief mechanism. This can be achieved by configuring the inverse apex region of the housing to move in response to sufficiently high pressure.
More generally, and referring again to
When the difference between the long dimension of the rotor and the short dimension of the rotor is equal to four times the crank radius, and the rotor is in the vertical position, the point of contact with the inverse apex region is in the same location regardless of the shape of the inverse apex region.
For an elliptical rotor, the inverse apex region shape comprises two convex parts that meet at the inverse apex. A housing with this shape does not interfere with motion of the rotor during eccentric rotation of the rotor as described above.
For a near-elliptical rotor described above, the inverse apex region shape is concave and the housing in the inverse apex region does not interfere with motion of the rotor during eccentric rotation of the rotor as described above.
In a preferred embodiment, the rotor is configured to be symmetric about its long dimension and its short dimension. Similarly, in a preferred embodiment, the housing is configured to be symmetric about an axis drawn vertically through the center of the inverse apex region.
Rotolliptic motion can be applied to geometries other than those having symmetric rotors. Rotary machines similar to those described above can comprise a rotor having an asymmetric shape in cross-section. An example of such an embodiment having asymmetry about the long and short axes of the rotor is described below.
For the purposes of the following explanation, outline of rotor 1700 is divided into four substantially equal quadrants 1710, 1720, 1730 and 1740.
Housing shape 1920 encloses asymmetric rotor 1700 for the various angles of rotation. The instantaneous velocity vector at a given point on the outline of the cross-section of asymmetric rotor 1700 lies perpendicular to a line joining the given point to the instantaneous center of rotation. For a given profile (such as 1910A and 1910B and other profiles that could be generated by rotation of asymmetric rotor 1700), there is a set of points lying on the profile at which the instantaneous velocity vector is tangential to the profile. The locus of such sets of points for the profiles describes housing shape 1920.
Housing shape 1920 further comprises an inverse apex region 1930 and an inverse apex 1940.
Housing shape 2020 further comprises an inverse apex region 2030 and an inverse apex 2040.
In some embodiments of the technology described above, the output of the rotary machine tends to vary (or pulsate) during each cycle of operation according to the rate of change of volume of the discharging chamber.
As an example,
Note that when rotor 510 is in a vertical position, it contacts housing 520 at only two places—at inverse apex 540 and at a point on housing 520 directly above inverse apex 540. In this position, rotor 510 divides the interior of housing 520 into just two chambers of substantially equal size, and the volume of the third chamber is zero.
Lines 2110, 2120 and 2130 of
Uneven output of the rotary machine can be undesirable in at least some applications. It can be beneficial in some applications to reduce or eliminate output flow variation.
Benefits of reducing output flow rate variation include reduced stress on the rotary machine—leading to improved function and durability.
One approach to reduce output flow rate variation is to configure the rotary machine with more than one rotor, the rotors configured to rotate out of phase with one another so as to compensate for flow variations associated with a single rotor. For example,
With reference to
Housing 2220 comprises an inlet 2260 and an outlet 2265. Fluid enters the pump through inlet 2260 and is expelled from the pump through outlet 2265. Rotation of elliptical rotor 2210A can be out of phase with respect to rotation of elliptical rotor 2210B. For example, rotors 2210A and 2210B can have an angular separation about the instantaneous axis of rotation of 90 degrees, and a phase angle between the mechanical couplings (not shown in
Housing 2220 also comprises a center plate 2228 located between the two rotors 2210A and 2210B. For clarity, center plate 2228 is not shown in
In some embodiments, more than two rotors operating out of phase with each other can be used to compensate for the output flow variation. In general, the flow variation will be reduced further by adding more rotors.
Another approach to reducing or eliminating output flow rate variation is to vary the rotational speed of the shaft driving the rotary machine to compensate for the variation in the rate of change of volume of the discharging chamber.
One approach to reduce flow variation is to modify the coupling between the rotary machine and the device driving the assembly (for example, a motor and drive shaft) to vary the rotational speed of the drive shaft.
If drive shaft 2720 rotates at a substantially constant rate, rotary machine assembly 2700A can have considerable net output flow rate variation, for example in accordance with the graph of
To reduce flow variation, it can be beneficial to provide a mechanism that varies the rotational rate of rotors 2732 and 2734 in rotor and housing assembly 2730 so as to at least partially compensate for the flow variation described above. U-joint 2740 acting as a coupling between drive shafts 2722 and 2724 can be used to provide a variation in rotational rate of drive shaft 2724 for an approximately constant rotational rate of drive shaft 2722. The variation in rotational rate of drive shaft 2724 depends on angle 2750 subtended by drive shaft 2722 and drive shaft 2724. (In
As shown in
Referring also again to
Driving the crankshaft of a rotary machine comprising two rotors by a suitably configured U-joint can reduce flow variation in the output of the rotary machine.
Line 2870 shows the output shaft speed of a U-joint coupling for substantially constant rotational speed of the input shaft of the U-joint coupling (for example, line 2840 of
Another approach to reducing output flow rate variation is to use a non-circular gearing mechanism to drive the crankshaft of a rotary machine such as rotary machine 800 of
When coupled with a rotary machine comprising one or more rotors, a crankshaft driven by suitably configured oval gears can reduce flow variation in the output of the rotary machine. Furthermore, identical non-circular gears (oval or otherwise) provide a constant axis of rotation.
More generally, a rotary machine comprising one or more rotors can be driven by a crankshaft connected to a transmission comprising non-circular gears configured to modify the output flow variation of the rotary machine. Gear shapes can be chosen and the gearing configured for the rotary machine such that the output flow variation of the rotary machine can be reduced or eliminated.
In addition to the mechanisms described above, the output flow rate variation of the machine can be modified by other suitable mechanisms including, but not limited to, a drive with a variable and electronically controlled rotational speed, or other suitable variable speed transmission.
Pump 3100 comprises an elliptical rotor 3110 in a housing 3120 having an inverse apex 3130 in contact with elliptical rotor 3110 throughout its rotation. Elliptical rotor 3110 undergoes eccentric rotation as described above.
In some embodiments, more than one lining 3140 can be installed in housing 3120. Lining 3140 can be a replaceable lining. Lining 3140 can be made from a different material than elliptical rotor 3110 and housing 3120. For example, the material of lining 3140 can be chosen to be more durable and/or softer.
By adding or removing one or more linings 3140, the gap between elliptical rotor 3110 and housing 3120 can be adjusted. In some embodiments, the gap can be approximately 5 mm. Some embodiments of lining 3140 can be of uniform thickness. Other embodiments of lining 3140 can have thickness that varies around the lining thereby providing an adjustment of the gap at different locations around the lining which can be beneficial for certain applications.
One or more linings can optionally be incorporated into the various embodiments of rotary machines described herein.
Friction features can optionally be incorporated into the various embodiments of rotary machines described herein.
In this manner, the system can be configured to provide pressure relief by means of dynamic apex seal 3775. While apex seal 3775 is in contact with rotor 3750, apex seal 3775 functions as a seal between rotor 3750 and inverse apex region 3770.
Dynamic apex seals can optionally be incorporated into the various embodiments of rotary machines described herein.
In a preferred embodiment, the crank radius can be related to the long and short dimensions of the rotor as follows: (AA−BB)=4C, where AA is the long dimension of the rotor (for example, major axis of an elliptical rotor), BB is the short dimension of the rotor (for example, minor axis of an elliptical rotor) and C is the crank radius. The corresponding ring gear has a pitch circle equal to 4C, and the corresponding sun gear has a pitch circle equal to 2C.
Sun gear 3840 comprises an opening for a drive shaft. The size of the drive shaft is constrained by the size of sun gear 3840. Furthermore, there are additional constraints on the size of the opening for the drive shaft that include the mechanical requirements for fastening sun gear 3840 to a mating surface in the rotor assembly. In one example, sun gear 3840 can be fastened to the mating surface in the rotor assembly by means of alignment pins and fasteners.
One approach to increasing the size of the opening for the drive shaft is to configure sun gear 3840 to comprise a geometric mechanical protrusion that can press into a corresponding socket in the mating surface of the rotor assembly.
A suitably shaped protrusion and corresponding socket can be used including, but not limited to, hexagonal, square, triangle, star and spur.
Center plate 2228 comprises a pressure relief valve 2280 allowing fluid to cycle back through the pump to relieve pressure in a volume defined by housing 2220 and one or both of the first and second elliptical rotors. Pressure relief valve 2280 can be a one-way sprung check valve.
In other embodiments, a pressure relief valve (such as one of those described above) can be used to provide pressure relief in a single rotor positive displacement pump assembly or rotodynamic pump assembly, such as those described above with reference to
Inlet cut-out 4445 and outlet cut-out 4455 can serve as manifolds for the inlet 4440 and outlet 4450 respectively.
In operation of rotary machine 4400, crankshaft 4430 rotates and is mechanically coupled via first sun gear 4432 and first ring gear 4434 to cause eccentric rotation of first rotor 4410 within housing 4420. Crankshaft 4430 is also mechanically coupled via second sun gear 4436 and second ring gear 4438 to cause eccentric rotation of second rotor 4415 within housing 4420. Fluid is drawn into rotary machine 4400 via inlet port 4440 and expelled from outlet port 4450. First rotor 4410 and second rotor 4415 are in contact with dynamic apex seal 4465 at inverse apex 4460 throughout rotation of rotors 4410 and 4415.
Particular elements, embodiments and applications of the present invention have been shown and described in relation to pumps and/or rotary machines. Embodiments of the present invention can be utilized in machines and applications including, but not limited to, rotary compressors, positive displacement pumps, dynamic pumps and expansion engines.
While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, that the invention is not limited thereto since modifications can be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.
This application is a continuation of U.S. patent application Ser. No. 15/924,173 filed on Mar. 16, 2018, entitled “Rotary Machine with Pressure Relief Mechanism”. The '173 application is a continuation of U.S. patent application Ser. No. 14/296,433 filed on Jun. 4, 2014, entitled “Rotary Machine”. The '433 application claims priority benefits, in turn, from U.S. provisional patent application Ser. No. 61/831,248, filed on Jun. 5, 2013, entitled “Rotary Machine With Elliptical Rotor”, from U.S. provisional patent application Ser. No. 61/865,604, filed on Aug. 13, 2013, entitled “Rotary Pump”, and from U.S. provisional patent application Ser. No. 61/939,737, filed on Feb. 13, 2014, entitled “Rotary Machine”. The '173, '433, '248, '604 and '737 applications are each hereby incorporated by reference herein in their entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 724994 | Cooley | Apr 1903 | A |
| 1340625 | Planche | May 1920 | A |
| 1575987 | Gilman | Mar 1926 | A |
| 1636486 | Planche | Jul 1927 | A |
| 1686569 | McMillan | Oct 1928 | A |
| 1738645 | Gilman | Dec 1929 | A |
| 1892217 | Moineau | Dec 1932 | A |
| 2612022 | Keys | Sep 1952 | A |
| 2919062 | Tryhom | Dec 1959 | A |
| 2988008 | Wankel | Jun 1961 | A |
| 3259113 | Hamada | Jul 1966 | A |
| 3279388 | Roudaut | Oct 1966 | A |
| 3296874 | Wyczalek | Jan 1967 | A |
| 3299822 | Payne | Jan 1967 | A |
| 3302870 | Schell | Feb 1967 | A |
| 3387772 | Wutz | Jun 1968 | A |
| 3398643 | Schudt | Aug 1968 | A |
| 3458120 | Pfaff et al. | Jul 1969 | A |
| 3465729 | Jones | Sep 1969 | A |
| 3512904 | Allen | May 1970 | A |
| 3533716 | Grun | Oct 1970 | A |
| 3728049 | Miller | Apr 1973 | A |
| 3764239 | Huf | Oct 1973 | A |
| 3917437 | Link | Nov 1975 | A |
| 3918137 | Telang | Nov 1975 | A |
| 3958906 | Catterson et al. | May 1976 | A |
| 3990817 | Ruf et al. | Nov 1976 | A |
| 4012180 | Berkowitz et al. | Mar 1977 | A |
| 4018548 | Berkowitz | Apr 1977 | A |
| 4028021 | Berkowitz | Jun 1977 | A |
| 4061445 | Doshi | Dec 1977 | A |
| 4118157 | Mayer | Oct 1978 | A |
| 4144001 | Streicher | Mar 1979 | A |
| 4218199 | Eiermann | Aug 1980 | A |
| 4296500 | Monties et al. | Oct 1981 | A |
| 4299097 | Shank et al. | Nov 1981 | A |
| 4330240 | Eslinger | May 1982 | A |
| 4382755 | Hoffmann | May 1983 | A |
| 4395206 | Hoffmann | Jul 1983 | A |
| 4397619 | Alliquander et al. | Aug 1983 | A |
| 4407639 | Maruyama | Oct 1983 | A |
| 4410305 | Shank et al. | Oct 1983 | A |
| 4487561 | Eiermann | Dec 1984 | A |
| 4507067 | Hansen | Mar 1985 | A |
| 4519206 | Van Michaels | May 1985 | A |
| 4551073 | Schwab | Nov 1985 | A |
| 4594060 | Schwab | Jun 1986 | A |
| 4728270 | Hoffmann | Mar 1988 | A |
| 4802830 | Nakajima | Feb 1989 | A |
| 4934325 | Snyder | Jun 1990 | A |
| 5069606 | Bachellerie | Dec 1991 | A |
| 5096004 | Ide | Mar 1992 | A |
| 5127377 | Yang | Jul 1992 | A |
| 5169298 | Hekman et al. | Dec 1992 | A |
| 5171138 | Forrest | Dec 1992 | A |
| 5295814 | Uebel | Mar 1994 | A |
| 5302096 | Cavalleri | Apr 1994 | A |
| 5372107 | Smythe | Dec 1994 | A |
| 5379736 | Anderson | Jan 1995 | A |
| 5439359 | Leroy et al. | Aug 1995 | A |
| 5609475 | Eiermann | Mar 1997 | A |
| 6074184 | Imai | Jun 2000 | A |
| 6093004 | Varadan et al. | Jul 2000 | A |
| 6213744 | Choroszylow et al. | Apr 2001 | B1 |
| 6236897 | Lee et al. | May 2001 | B1 |
| 6530357 | Yaroshenko | Mar 2003 | B1 |
| 6718938 | Szorenyi | Apr 2004 | B2 |
| 6776136 | Kazempour | Aug 2004 | B1 |
| 6923628 | Otto | Aug 2005 | B1 |
| 6926505 | Sbarounis | Aug 2005 | B2 |
| 6974313 | Beaudoin | Dec 2005 | B2 |
| 7101160 | Gennami et al. | Sep 2006 | B2 |
| 7117839 | Horstin | Oct 2006 | B2 |
| 7395805 | MacMurray | Jul 2008 | B1 |
| 7540728 | Gorban | Jun 2009 | B2 |
| 7549850 | Trapalis | Jun 2009 | B2 |
| 7553138 | Gorban | Jun 2009 | B2 |
| 7726115 | Murrow et al. | Jun 2010 | B2 |
| 7837451 | Wiedenhoefer et al. | Nov 2010 | B2 |
| 7942657 | Gray | May 2011 | B2 |
| 8356585 | Hathaway et al. | Jan 2013 | B2 |
| 8523545 | Wilbourn et al. | Sep 2013 | B2 |
| 8523546 | Shkolnik et al. | Sep 2013 | B2 |
| 8539930 | Gray | Sep 2013 | B2 |
| 8539931 | Hanna | Sep 2013 | B1 |
| 8888474 | Hohl et al. | Nov 2014 | B2 |
| 8905733 | Guidry | Dec 2014 | B2 |
| 9051780 | Trushin | Jun 2015 | B2 |
| 10087758 | Montie et al. | Oct 2018 | B2 |
| 10837444 | Montie et al. | Nov 2020 | B2 |
| 10844720 | Montie | Nov 2020 | B2 |
| 10844859 | Montie et al. | Nov 2020 | B2 |
| 20020122722 | Bertin et al. | Sep 2002 | A1 |
| 20030102629 | Bhate et al. | Jun 2003 | A1 |
| 20050017053 | Sbarounis | Jan 2005 | A1 |
| 20060073032 | Parrett | Apr 2006 | A1 |
| 20060127259 | Gorban | Jun 2006 | A1 |
| 20060233653 | Trapalis | Oct 2006 | A1 |
| 20080031758 | Rosam et al. | Feb 2008 | A1 |
| 20080193309 | Kothnur et al. | Aug 2008 | A1 |
| 20090220369 | Wiedenhoefer et al. | Sep 2009 | A1 |
| 20090241536 | Gale et al. | Oct 2009 | A1 |
| 20100183454 | Lübke et al. | Jul 2010 | A1 |
| 20110262291 | Fleger et al. | Oct 2011 | A1 |
| 20120070326 | Hammerbeck | Mar 2012 | A1 |
| 20120156078 | Guidry | Jun 2012 | A1 |
| 20120177484 | Lusted et al. | Jul 2012 | A1 |
| 20120240885 | Horn | Sep 2012 | A1 |
| 20130028775 | Gekht et al. | Jan 2013 | A1 |
| 20130064702 | Hohl et al. | Mar 2013 | A1 |
| 20150030492 | Montie et al. | Jan 2015 | A1 |
| 20160141921 | Kubes | May 2016 | A1 |
| 20170074100 | Jarvis et al. | Mar 2017 | A1 |
| 20170137005 | Weh et al. | May 2017 | A1 |
| 20170321697 | Beinert et al. | Nov 2017 | A1 |
| 20180291900 | Valkenberg et al. | Oct 2018 | A1 |
| 20200200174 | Montie et al. | Jun 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 2014499 | Oct 1971 | DE |
| 1552124 | May 2006 | EP |
| 1988288 | Nov 2008 | EP |
| 1010141265 | May 1998 | JP |
| H275663124 | Feb 2015 | JP |
| 1999056004 | Nov 1999 | WO |
| 2005078239 | Aug 2005 | WO |
| 2009103528 | Oct 2009 | WO |
| 2010131103 | Mar 2011 | WO |
| Entry |
|---|
| U.S. Appl. No. 14/296,433, filed Jun. 4, 2014, Office Action dated Dec. 23, 2016, Office Action dated Jun. 22, 2017. |
| U.S. Appl. No. 15/924,173, filed Mar. 16, 2018, Office Action dated Apr. 14, 2020. |
| U.S. Appl. No. 16/805,698, filed Feb. 29, 2020, Office Action dated Apr. 22, 2020, Notice of Allowance dated Sep. 10, 2020. |
| U.S. Appl. No. 16/805,712, filed Feb. 29, 2020, Office Action dated Apr. 20, 2020, Notice of Allowance dated Sep. 24, 2020. |
| PCT/CA2019/051272, International Search Report and Written Opinion dated Nov. 19, 2019. |
| PCT/CA2019/051273, International Search Report and Written Opinion dated Nov. 13, 2019. |
| PCT/CA2019/051274, International Search Report and Written Opinion dated Nov. 18, 2019. |
| U.S. Appl. No. 17/198,231, filed Mar. 10, 2021, Office Action dated Aug. 31, 2021. |
| Ansdale, R., The Wankel RC Engine, (1968), p. 20. |
| Wydra, L., The Development of Outer-Envelope Trochoidal Compressors, International Compressor Engineering Conference (1986), pp. 282-292. |
| Wrede et al., Recent Status of Trochoidal Type Compressors for Heat Pumps in Germany, International Compressor Engineering Conference (1986), pp. 254-282. |
| International Search Report and Written Opinion dated Nov. 13, 2019 issued in connection with International Application No. PCT/CA2019/051273. |
| International Search Report and Written Opinion dated Nov. 18, 2019 issued in connection with International Application No. PCT/CA2019/051274. |
| International Search Report and Written Opinion dated Nov. 19, 2019 issued in connection with International Application No. PCT/CA2019/051272. |
| Extended European Search Report dated May 16, 2022, in connection with PCT Patent Application PCT/CA2019/051274. |
| International Preliminary Report on Patentability dated Mar. 9, 2021, issued in connection with International Application No. PCT/CA2019/051272. |
| International Preliminary Report on Patentability dated Mar. 9, 2021, issued in connection with International Application No. PCT/CA2019/051273. |
| International Preliminary Report on Patentability dated Mar. 9, 2021, issued in connection with International Application No. PCT/CA2019/051274. |
| UK Examination Report dated Mar. 1, 2022, issued in connection with Great Britain Application No. GB 2104634.7. |
| International Search Report and Written Opinion dated Mar. 29, 2022, issued in connection with International Application No. PCT/CA2022/050021. |
| EP 19859949.0 filed on Apr. 7, 2021, Extended European Search Report dated May 16, 2022. |
| U.S. Appl. No. 17/067,755, filed Oct. 11, 2020, Office Action dated Mar. 16, 2022. |
| U.S. Appl. No. 17/198,124, filed Mar. 10, 2021, Office Action dated Mar. 31, 2022. |
| PCT/CA2019/051272, International Preliminary Report on Patentability dated Mar. 9, 2021. |
| PCT/CA2019/051273, International Preliminary Report on Patentability dated Mar. 9, 2021. |
| PCT/CA2019/051274, International Preliminary Report on Patentability dated Mar. 9, 2021. |
| PCT/CA2022/050021, International Search Report and Written Opinion dated Mar. 29, 2022. |
| GB 2104634.7 filed on Mar. 31, 2021, Examination Report dated Mar. 1, 2022. |
| Extended European Search Report dated Jul. 8, 2022, in connection with European Patent Application 19860104.9. |
| Number | Date | Country | |
|---|---|---|---|
| 20210062655 A1 | Mar 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61831248 | Jun 2013 | US | |
| 61865604 | Aug 2013 | US | |
| 61939737 | Feb 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15924173 | Mar 2018 | US |
| Child | 17067772 | US | |
| Parent | 14296433 | Jun 2014 | US |
| Child | 15924173 | US |
