Multi Stage Compressor

The present disclosure relates to a multi stage compressor for compressing fluid.

U.S. Pat. No. 11,156,231 discloses a multistage compressor for compressing fluid. US application publication 20090044548 discloses a two-stage vapor cycle compressor.

Objects of the invention are to provide a more efficient and compact multistage compressor.

In one aspect, the disclosure provides a compressor device for compressing fluid, comprising: a motor-compressor housing side portion; a fixed group; a rotatable group; wherein all elements of the fixed group are fixed relative to the motor-compressor housing side portion so that they do not move relative to the motor-compressor housing side portion; wherein all elements of the rotatable group are fixed to one another so that they do not move relative to one another; wherein the motor-compressor housing side portion, the fixed group, and the rotatable group are configured, so that the rotatable group is rotatable about to an axis of rotation relative to the motor-compressor housing side portion and the fixed group, and so that the rotatable group is constrained from moving along the axis of rotation, constrained from rotating perpendicular to the axis of rotation, and constrained from translating perpendicular to the axis of rotation relative to the motor-compressor housing side portion and the fixed group; wherein the fixed group comprises a motor stator section, a first stage compressor wheel housing, a diffuser structure, and a second stage compressor wheel housing; wherein the rotatable group comprises a permanent magnet, a first stage compressor wheel; and a second stage compressor wheel; wherein the motor-compressor housing side portion extends from a motor-compressor housing side portion rear end to a motor-compressor housing side portion front end; wherein the motor-compressor housing side portion has interior surfaces that define a motor chamber; wherein the motor stator section and the permanent magnet reside in the motor chamber; wherein the motor-compressor housing side portion, the fixed group, and the rotatable group are configured to provide a fluid flow path for fluid to flow to a first stage compression passage and then to a second stage compression passage; wherein the second stage compressor wheel housing comprises a rear disk portion, a front disk portion, and an axially extending neck portion; wherein the axially extending neck portion comprises a rear region that extends from the rear disk portion and a front region that extends from the front disk portion; wherein the axially extending neck portion extends from the rear region to the front region; wherein the rear disk portion has a substantially radially extending rear surface region and a substantially radially extending first portion of a front surface region; wherein the front disk portion has a substantially radially extending rear surface region and a substantially radially extending front surface portion; wherein the first stage compression passage includes a first stage initial region and a first stage final region; wherein the first stage initial region comprises space between a generally cylindrically shaped outer surface region of the first stage compressor wheel and an opposing surface of the first stage compressor wheel housing; whereby rotation of the rotatable group in a first direction of rotation about the axis of rotation urges fluid in the first stage initial region to move along the fluid flow path towards the first stage final region; wherein the first stage final region comprises space between opposing surfaces of the diffuser structure and a rear surface region of the rear disk portion; wherein fluid flowing from the first stage initial region through the first stage final region enters the second stage compression passage; wherein the second stage compression passage comprises a second stage first region and a second stage second region; wherein the second stage first region is formed by opposing surfaces of the axially extending neck portion and a generally cylindrically shaped outer surface region of the second stage compressor wheel; whereby rotation of the rotatable group in the first direction about the axis of rotation urges fluid in the second stage first region to move along the fluid flow path towards the second stage second region; wherein the second stage second region has one surface formed by the substantially radially extending front surface portion of front disk portion; and wherein the substantially radially extending first portion of the front surface region of the rear disk portion opposes, and is spaced, along a direction of the axis of rotation, from the substantially radially extending rear surface region of the front disk portion, defining a gap there between.

In addition, dependent aspects include: wherein an aspect ratio of the gap is between 0.3 and 1000; between 1 and 100; between 2 and 100; and between 3 and 20; wherein an aspect ratio of the gap is between 3 and 10; wherein a thermal ratio is between 0 and 0.8; wherein a thermal ratio is between 0 and 0.5; wherein a front disk periphery thickness to gap length ratio is between 0.5 and 10; wherein a front disk center thickness to gap length ratio is between 0.3 and 10; wherein the second stage compressor wheel housing further comprises an axially and radially extending support wall extending radially out from the axially extending neck portion and extending axially from the rear disk portion to the front disk portion.

In addition, dependent aspects include: wherein the substantially radially extending rear surface region extends at an angle of within plus or minus thirty degrees from a plane perpendicular to the axis of rotation; the substantially radially extending first portion extends at an angle of within plus or minus thirty degrees from a plane perpendicular to the axis of rotation; and the substantially radially extending front surface portion extends at an angle of within plus or minus thirty degrees from a plane perpendicular to the axis of rotation; wherein the substantially radially extending rear surface region extends at an angle of within plus or minus ten degrees from a plane perpendicular to the axis of rotation;

In addition, dependent aspects include: wherein the diffuser structure comprises a diffuser cover and a diffuser back plate, and wherein the diffuser cover is press fit onto the diffuser back plate; further comprising a motor-compressor housing end cap and wherein a first rear surface region of the motor-compressor housing end cap opposes the substantially radially extending front surface portion of front disk portion and forms a surface of the second stage second region.

In addition, dependent aspects include wherein the second stage second region opens to a volute defined by a recessed region of the motor-compressor housing end cap extending azimuthally around axis of rotation, and an opposing front surface portion of the front disk portion; and wherein the volute has an opening to a compressor fluid outlet conduit which terminates at a compressor fluid outlet port to space outside the compressor device.

In addition, dependent aspects include wherein the interior surfaces of the motor-compressor housing side portion defines a motor-compressor housing outlet port; and wherein the motor-compressor housing side portion, the fixed group, and the rotatable group are configured to provide a fluid flow path for fluid to flow from the motor-compressor housing outlet port to the first stage compression passage.

Each of these dependent aspects is useable with any of the other dependent aspects in a compressor device.

are taken from a solid model for a specific disclosed embodiment, and therefore fine detail is significant. However, horizontal and vertical scale between figures varies somewhat since the 2-dimensional images were magnified by slightly different amounts in the horizontally and vertically directions. Variations that are believed to be feasible and operable are mentioned after describing the relevant features of the disclosed embodiment.

shows compressor housing front sideand compressor housing right sideof novel compressor device, axis of rotation, and direction of rotation. Arrowhead on axis of rotationdefines a positive direction.

shows novel compressor devicecomprises housingcomprising, from front to back relative to the positive direction defined by axis of rotation, motor-compressor housing end cap, motor-compressor housing side portion, separator housing portion, converter housing side portion, and converter housing end cap.

shows exterior surfaces of motor-compressor housing end cap, motor-compressor housing side portion, separator housing portion, converter housing side portion, and converter housing end capcomprise: compressor fluid outlet conduit; converter housing side portion; converter housing end cap; bolt; bolt; compressor fluid outlet port; instrumentation ports; projected portionof motor-compressor housing side portion; right rear AC phase cable gland; compressor fluid inlet port; bosses of motor-compressor housing side portionincluding boss, boss, boss, and boss, and compressor fluid inlet conduit, and bolt.

shows bolt, and another bolt identical to bolt, each extending through apertures in upper portions of separator housing portion, converter housing side portion, and converter housing end cap.

shows bolton the right side of compressor device, extending through apertures in bossof motor-compressor housing side portion, separator housing portion, converter housing side portion, and converter housing end capshows two more bolts on the right side of compressor deviceextending through apertures in motor-compressor housing side portion, separator housing portion, converter housing side portion, and converter housing end cap.shows boltextending through an aperture in motor-compressor housing end capand into an aperture in motor-compressor housing side portion. Bolts,,and the other bolts mentioned rigidly constrain housing elements of compressor deviceto one another.

shows motor-compressor housing side portioncomprises boss, bossboss, boss. The term “boss” refers to additional material of a physical structure, generally having a form that can be used for mechanical structural connection to other elements.shows motor-compressor housing side portionalso comprises instrumentation portsand projected portion.shows right rear AC phase cable gland, partially visible, projects from the rear side of compressor device.shows motor-compressor housing end capcomprising compressor fluid outlet conduit, which terminates at compressor fluid outlet port.

is a front view of compressor devicein which lower center electrical feedthrough connectoris visible.

is a left side view of compressor devicein which appear measurement port, measurement conduit, boss, and casting datum, all as portions of motor-compressor housing side portion.

is a right-side view of compressor devicein which more fully appears right rear AC phase cable gland.

is a top view of compressor deviceshowing tops views of left rear AC phase cable gland, center rear AC phase cable gland, as well as right rear AC phase cable gland.

s a back view of compressor deviceshowing the back surface of converter housing end cap.

is a bottom view of compressor device.

is a perspective view of the rear of separator housing portionshowing O-ring groove, axially aligned cylindrical aperture, tubular inner surface, and fluid flow aperture.

O-ring grooveprovides a seat for an elastomeric loop to provide a fluid seal. Fluid flow apertureprovides a path for fluid to flow therethrough to motor chamber(see).shows 3 additional apertures similar in shape and function to fluid flow aperturewhich are spaced azimuthally around axis of rotation. Axially aligned cylindrical apertureprovides a constraint to retain rotatable group(see) substantially colinear with axis of rotation.

is a substantially rear perspective view, having axis of rotationcanted slightly towards the left of motor-compressor housing side portion.shows O-ring groove, motor-compressor housing outlet port, inner surfaceof motor-compressor housing side portion, motor chamber, axially aligned cylindrical aperture, tubular inner surfaceof motor-compressor housing side portion, rear endof motor-compressor housing side portion, and identifies hidden front endof motor-compressor housing side portion.

shows rear endincludes O-ring groove. O-ring grooveprovides a seat for an elastomeric loop to provide a fluid seal.

shows inner surfacesubstantially defines motor chamberwhich substantially encloses motor stator section(see).

shows that inner surfacesubstantially defines compressor housing outlet portwhich provides a path for fluid to flow therethrough, from motor chamberout of a front end of motor-compressor housing side portion, to conduitof first stage compressor wheel housing(see).

shows that motor-compressor housing outlet portis one of six such ports substantially equally spaced in the azimuthal direction around axis of rotation.

shows axially aligned cylindrical aperturewhich provides a constraint to retain rotatable group(see) substantially colinear with axis of rotation. Axially aligned cylindrical apertureextends to a front end (not shown) of motor-compressor housing side portion.

is a substantially rear perspective view having axis of rotationcanted slightly towards the left, of first stage compressor wheel housing.

shows O-ring groove, conduit surface, conduit, axially aligned cylindrical aperture, and generally cylindrical inner surfaceof first stage compressor wheel housing.

shows O-ring groovewhich provides a seat for an elastomeric loop to provide a fluid seal. Conduit surfacedefines conduitfor fluid to flow there through. Conduitis canted toward axis of rotationso that the port of conduiton the front side of first stage compressor wheel housingis closer to axis of rotationthan the port of first stage compressor wheel housingon the rear side of first stage compressor wheel housing. Conduitprovides for fluid flow therethrough to inletto first stage compressor wheel(see). Axially aligned cylindrical apertureand generally cylindrical inner surfaceprovide a constraint to retain rotatable group(see) substantially colinear with axis of rotation.

shows that conduitis one of six such conduits equally spaced in the azimuthal direction around axis of rotation.

is the “I” side section view of.shows power converter chamber, power converter, bolt, thrust bearing plate, rear stub, permanent magnet, front stub, securing bolt, first stage compressor wheel, second stage compressor wheel, rotatable group, rear fluid foil bearing slot, secondary fluid flow conduit, motor stator section, front fluid foil bearing slot, and fixed group.

shows that power converter chambercontains power converter. Power converteris shown schematically, and represents a power converter for converting electrical power received in compressor device into a form useful for driving rotatable sectionby applying the converted power to motor stator section. Power conversion is well known in the art.

shows motor stator sectionresides in motor chamber.

identifies rotatable groupwhich consists of elements that are constrained to rotate together. Rotatable groupincludes bolt, thrust bearing plate, rear stub, permanent magnet, front stub, securing bolt, first stage compressor wheel, second stage compressor wheel. Securing boltsecures in a recess in rear stub. Thrust bearing platehas surfaces that oppose surfaces constrained to housing elements, thereby constraining axial movement of rotatable grouprelative to housing elements. Rear stuband front stubare formed from Inconel. Securing boltsecures in a recess in front stub. Securing boltpasses through apertures in first stage compressor wheeland second stage compressor wheel. Securing bolthas a head defining a rim that opposes a forward annular surface of second stage compressor wheel.

shows that permanent magnetresides in the motor chamber.

also identifies fixed group. Fixed groupcomprises all elements that are fixed relative to motor-compressor housing side portionso that they do not move relative to motor-compressor housing side portion. Fixed groupincludes elements identified inincluding motor stator section; first stage compressor wheel housing; a diffuser structure consisting of diffuser coverand diffuser back plate; and second stage compressor wheel housing. These fixed elements either contain peripheral structure that mate to interior surfaces of the housing that fix them relative to the housing or blanks or threaded bores for pins or bolts to secure them to other fixed elements within the housing in manners well known in the art.

Motor-compressor housing side portionand fixed groupconstrain rotatable groupfrom translating and rotating perpendicular to the axis of rotation.

shows rear fluid foil bearing slotand front fluid foil bearing slotprovide for relatively low friction bearing surfaces that facilitate rotation of rotatable group. Secondary fluid flow conduitprovides a path defined within motor-compressor housing side portionthat communicated with thrust bearing plate.

is a magnified view of the “II” section of, showing first stage compressor wheel housing, first stage compressor wheel, second stage compressor wheel, inletto first stage compressor wheel, diffuser cover, diffuser back plate, second stage compressor wheel housing, bolt, O-ring, inletto second stage compressor wheel, volute, opposing surface region, rear disk portion, axially extending neck portion, front disk portion, front surface regionof rear disk portion, substantially radially extending rear surface regionof front disk portion, gap, axially extending support wall, O-ring, peripheral generally cylindrical surfaceof front disk portion, rear regionof annular outer surfaceof axially extending neck portion, front regionof annular outer surfaceof axially extending neck portion, inside surface portion of motor-compressor housing side portion, cylindrical inner surfaceof motor-compressor housing end cap, substantially radially extending first portionof front surface region, second portionof front surface region, and third portionof front surface region.

shows inletto first stage compressor wheelcommunicating with first stage compression passage, for fluid flow. Diffuser coveris press fit onto diffuser back plate. Bolthelps secure diffuser back plateto second stage compressor wheel housing. Additional bolts like boltmay be present, but are not shown by the cross-section of. O-ringis an elastomeric seal disposed in a groove in a rear surface of motor-compressor housing end cap. O-ringforms a seal between the rear surface of motor-compressor housing end capand a front surface of motor-compressor housing side portion. Voluteextends azimuthally around axis of rotationand communicates with compressor fluid outlet conduit(see) to provide fluid out of compressor deviceat a higher pressure than fluid entering compressor devicethrough compressor fluid inlet conduit.

shows voluteis a space between a region of front surface region(see) of front disk portionof second stage compressor wheel housingand a rear surface region of motor-compressor housing end cap.

shows opposing surfaces contact regionto be where a front surface region of first stage compressor wheel housingopposes and contacts a rear surface region of rear disk portionof second stage compressor wheel housing. Opposing surfaces contact regionextends from the first stage compression passage(see) radially outward to inside surface regionof motor-compressor housing side portion.

shows front surface regionof rear disk portionincludes substantially radially extending first portion, second portion, and third portion. Substantially radially extending first portionextends, from rear regionof annular outer surface(see) of axially extending neck portionof second stage compressor wheel housing, substantially radially outward. Second portionextends from substantially radially extending first portionand curves towards the negative direction of axis of rotation. Third portionextends from second portionradially away from axis of rotation, and terminates at inside surface regionof motor-compressor housing side portion.

shows substantially radially extending rear surface regionof front disk portionof second stage compressor wheel housingextends from front regionof annular outer surface(see) of axially extending neck portionof second stage compressor wheel housing, substantially radially outward to generally cylindrical surfaceof front disk portion(see).

shows gapdefined by the space between substantially radially extending first portionof front surface regionof rear disk portionof second stage compressor wheel housingand substantially radially extending rear surface regionof front disk portionof second stage compressor wheel housing(see).