Note: Descriptions are shown in the official language in which they were submitted.
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DRIVE SHAFT FOR COMPRESSOR
PRIORITY REFERENCE
BACKGROUND
[0001] The present invention relates generally to hermetic compressor
assemblies
having two compressor mechanisms driven by a single motor and, more
particularly, to
hermetic compressor assemblies having an improved drive shaft operably
coupling the motor
to the two compressor mechanisms.
[0002] Compressor assemblies having two compressor mechanisms operably coupled
to a single motor by a drive shaft are known. In many such assemblies, the
drive shaft
includes two integral eccentric portions defined at one end of the shaft.
These eccentric
portions are often machined into, or integrally molded with, the shaft such
that they are
unitary with the shaft. The motor includes a rotating rotor which defines a
central bore
extending through the rotor along a rotational axis. The end of the drive
shaft opposite the
eccentric portions extends into the bore and is affixed to the rotor for
rotation therewith.
Each of the integral eccentric portions operably engages one of the two
compressor
mechanisms, thereby mounting both of the two compressor mechanisms at one end
of the
drive shaft and adjacent one end of the motor.
[0003] Still other dual mechanism compressor assemblies are known in which the
unitary eccentric portions are defined at opposite ends of the drive shaft. In
such assemblies,
the two compressor mechanisms are operably mounted about the eccentric
portions at
opposite ends of the shaft and are thereby positioned adjacent opposite ends
of the motor.
Such an arrangement may be used to improve the balance of the compressor
assembly, which
may reduce the vibration and lower noise. However, oftentimes the eccentric
portions define
a larger cross-section than that of the drive shaft. These eccentric portions
cannot fit through
the bore of the rotor and, consequently, it is difficult to assemble such a
compressor using a
one-piece shaft. Instead, these compressor mechanisms require a two-piece
drive shaft that is
joined inside the rotor. The two-piece drive shaft design may be less rigid
than the one-piece
design, thereby causing the shaft to bend or deflect. Deflection of the shaft
may cause the
misalignment of the bearings, which ultimately may result in leaks and housing
deformation.
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[OOO4] Due to the problems associated with a drive shaft having unitary
eccentric
portions, a need remains for a hermetic compressor assembly having two
compressor
mechanisms operably engaged to opposite ends of a drive shaft without the use
of eccentric
portions unitarily defined in the drive shaft.
SUMMARY OF THE INVENTION
[0005] The present invention provides a compressor assembly that uses a shaft,
which
does not include unitarily defined eccentric portions at both ends and which
extends through
the motor to operably engage a compression mechanism at each end of the shaft
on the
opposite ends of the motor.
[0006] The compressor assembly comprises, in one form thereof, a motor
including a
stator and a rotor, and a drive shaft including an elongate central portion
and first and second
end portions located on opposite ends of the central portion. The drive shaft
defines a
rotational axis. First end portion, second end portion and central portions
define respective
first, second and third cross-sectional configurations oriented perpendicular
to the rotational
axis. Each of the first and second cross-sectional configurations has an outer
perimeter
disposed radially within the outer perimeter of the third cross-sectional
configuration relative
to the rotational axis. The drive shaft extends through the rotor with the
central portion being
rotationally secured to the rotor, the first end portion disposed proximate a
first end of the
motor and the second portion disposed proximate a second end of the motor. A
first
compressor mechanism is disposed proximate the first end of the motor and is
operatively
coupled to the first end portion of the drive shaft wherein the first end
portion rotationally
drives the first compressor mechanism. A second compressor mechanism is
disposed
proximate the second end of the motor and is operatively coupled to the
.second end portion
of the drive shaft wherein the second end portion rotationally drives the
second compressor
mechanism.
[0007] In another form, the compressor assembly comprises a motor including a
stator and a rotor, and a drive shaft comprising an elongate central portion
and first and
second end portions located on opposite ends of the central portion. The drive
shaft defines a
rotational axis. The first end portion, second end portion and central portion
define first,
second and third cross-sectional configurations, respectively, oriented
perpendicular to the
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rotational axis. Each of the first and second cross-sectional configurations
has an outer
perimeter disposed radially within the outer perimeter of the third cross-
sectional
configuration relative to the rotational axis. The first and second end
portions each define a
substantially similar non-circular cross-sectional configuration. The first
and second
configurations are rotationally offset by 180 degrees relative to the
rotational axis. The drive
shaft extends through the rotor with the central portion being rotationally
secured to the rotor,
the first end portion disposed proximate a first end of the motor and the
second end portion
disposed proximate a second end of the motor. A first rotary compressor
mechanism is
disposed proximate the first end of the motor and operatively coupled to the
first end portion
of the drive shaft wherein the first end portion rotationally drives the first
compressor
mechanism. A second rotary compressor mechanism is disposed proximate the
second end of
the motor and is operatively coupled to the second end portion of the drive
shaft wherein the
second end portion rotationally drives the second compressor mechanism.
[0008] The present invention also provides a method of assembling a compressor
assembly. The method, in one form thereof, includes providing a motor having a
stator and a
rotor, the rotor having an axially extending central bore, forming a drive
shaft with an
integral elongate member wherein the drive shaft includes an elongate central
portion and
first and second end portions located on opposite ends of the central portion,
the drive shaft
defining a rotational axis, the first end portion defining a first cross-
sectional configuration
oriented perpendicular to the rotational axis, the second end portion defining
a second cross-
sectional configuration oriented perpendicular to the rotational axis and the
central portion
defining a third cross-sectional configuration oriented perpendicular to the
rotational axis
wherein each of the first and second cross-sectional configurations has an
outer perimeter
disposed radially within the outer perimeter of the third cross-sectional
configuration relative
to the rotational axis, securing the drive shaft to the rotor by thermally
expanding the rotor,
inserting one of the first and second end portions of the drive shaft through
the central bore of
the rotor wherein the first end portion of the drive shaft accessible from a
first end of the rotor
and the second end portion of the drive shaft is accessible from a second end
of the rotor, and
allowing the rotor to cool and rotationally secure the drive shaft in the
central bore of the
rotor in a shrink-fit engagement, operably coupling a first compressor
mechanism to the first
end portion of the drive shaft wherein the drive shaft rotationally drives the
first compressor
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mechanism, and operably coupling a second compressor mechanism to the second
end
portion of the drive shaft wherein the drive shaft rotationally drives the
second compressor
mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The above mentioned and other features and objects of this invention,
and the
manner of attaining them, will become more apparent and the invention itself
will be better
understood by reference to the following description of embodiments of the
invention taken
in conjunction with the accompanying drawings, wherein:
[0010] Figure 1 is a sectional view of a dual mechanism hermetic compressor
assembly according to the present invention;
[0011] Figure 2 is a top sectional view of the compressor assembly of Fig. 1
taken
along lines 2-2;
[0012] Figure 3 is an inner end perspective view of the crankcase/shaft
assembly of
the compressor assembly of Fig. 1;
[0013] Figure 4 is an outside end view of the compressor mechanism of the
compressor assembly of Fig. l;
[0014] Figure 5 is a perspective view of the shaft roller assembly of the
compressor
assembly of Fig. l;
[0015] Figure 6 is a perspective view of the inner roller of the compressor
assembly
of Fig. 1;
[0016] Figure 7 is a perspective view of the shaft of the compressor assembly
of Fig.
l;
[0017) Figure 8 is a perspective view of a shaft according to another
embodiment of
the present invention;
[0018] Figure 9 is a perspective view of a shaft/eccentric/piston assembly
according
to the embodiment of Fig. 8; and
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[0019] Figure 10 is a sectional view of compressor assembly with the assembly
in
Fig. 9.
[0020] Corresponding reference characters indicate corresponding parts
throughout
the several views. Although the exemplification set out herein illustrates
embodiments of the
invention, in several forms, the embodiments disclosed below are not intended
to be
exhaustive or to be construed as limiting the scope of the invention to the
precise forms
disclosed.
DESCRIPTION OF THE PRESENT INVENTION
[0021] Referring first to Fig. I, compressor assembly 10 generally includes
first
compressor mechanism 14, second compressor mechanism 16 and motor assembly 18,
all of
which are disposed within interior volume 13 of housing 12. Housing 12
includes first and
second end members 12a, 12b and cylindrical main member 12c. Housing members
12a,
12b, 12c are hermetically sealed to one another to define interior volume 13.
[0022] Still referring to Fig. 1, motor assembly 18 defines first end 26 and
opposite
second end 28 and includes rotor 20, stator 22 and stator windings 24. Motor
assembly 18 is
connected to a power source (not shown) which drives the rotation of rotor 20
about
rotational axis A-A. Elongate drive shaft 30 extends through motor assembly 18
and
operably connects first and second compressor mechanisms 14, 16 to motor
assembly 18.
Drive shaft 30 extends through a central bore in rotor 20 along rotational
axis A-A and is
rotatably secured to rotor 20 for rotation therewith about axis A-A. Shaft 30
may be secured
to rotor 20 using conventional shrink-fit methods. One such method includes
thermally
expanding rotor 20, inserting shaft 30 through the central bore of thermally
expanded rotor
20, and allowing rotor 20 to cool and, thus, shrink around shaft 30 to secure
shaft 30 within
rotor 20.
[0023] As illustrated in Fig. I, drive shaft 30 is integrally formed as a
single unit and
defines f rst end portion 32, elongate central portion 34 and second end
portion 36. First and
second end portions 32, 36 of shaft 30 protrude from respective first and
second ends 26, 28
of motor assembly I 8 and operably engage first and second compressor
mechanisms 14, 16,
respectively, thereby positioning first and second compressor mechanisms 14,
16 proximate
opposite ends of motor assembly 18. The positioning of first and second
compressor
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mechanisms 14, 16 proximate opposite ends of motor assembly 18 provides
improved
balance in comparison to an assembly wherein one or more compressors are
positioned
proximate a single end of the motor. This improved balance may result in lower
vibration
and, ultimately, lower noise. The configuration of first and second end
portions 34, 36 and
their engagement with first and second compressor mechanisms 14, 16 is
descmbed in further
detail below.
[0024] Turning to Figs. 1 and 2, first and second compressor mechanisms 14, 16
are
identical rotary-type mechanisms and each generally includes crankcase 38,
annular cylinder
block 40, top member 42, and roller assembly 43. Cylinder block 40 is mounted
between
crankcase 38 and top member 42. Top member 42, cylinder block 40 and crankcase
38 are
secured to one another by fasteners (not shown) which extend through fastener-
receiving
holes 42a, 40a, 38a of top member 42, cylinder block 40, and crankcase 38,
respectively.
Cylinder block 40 defines an inside wall which cooperates with crankcase 38
and top member
42 to form compression chamber 52 in which a compressible fluid, such as a
refrigerant, may
be compressed.
[0025] As shown in Figs. I and 2, roller assembly 43 is disposed within
compression
chamber 52 and includes eccentric inner roller 44 and main roller 48 rotatably
mounted about
eccentric inner roller 44. Inner roller 44 is operably coupled to drive shaft
30, the rotation of
which causes roller assembly 43 to orbit within compression chamber 52. The
engagement
between drive shaft 30 and inner roller 44 is described in further detail
below. Needle roller
bearings (not shown) may be mounted between inner roller 44 and main roller 48
to facilitate
the rotation of main roller 48 about inner roller 44. Main roller 48 defines a
cylindrical outer
surface which travels along and sealingly engages the inside wall of cylinder
block 40 to give
compression chamber 52 an evolving crescent shape. Sliding vane 50
reciprocates within slot
51 defined in cylinder block 40 and engages main roller 48.
(0026] Refernng to Fig. 1, crankcase 38 of each of first and second mechanisms
14,
16 is mounted on respective first and second ends 26, 28 of motor assembly 18,
thereby
securing first and second compressor mechanisms 14, 16 to opposite ends of
motor assembly
18. Crankcase 38 may be mounted to motor assembly 18 in any conventional
manner. One
such manner involves inserting bolts (not shown) through holes 39 (Figs. 2-4),
which extend
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through legs 41 of crankcase 38, and engaging the bolts to threaded holes (not
shown) in
stator 22.
[0027] As illustrated in Figs. 1 and 3-4, crankcase 38 defines a substantially
cylindrical perimetrical sidewall 45 that finely and sealingly bears against
main housing
member 12c. The firn~ engagement between the sidewall of crankcase 38 and main
housing
member may be achieved by conventional shrink-fit methods. As a result of the
sealed
engagement between crankcase 38 and housing 12, the crankcases 38 of first and
second
compression mechanisms 14, 16 cooperate with one another to sealingly divide
interior
plenum 13 into first discharge plenum 66, second discharge plenum 68 and
suction plenum
69. First discharge plenum 66 includes that portion of interior plenum 13
located between
crankcase 38 of first compression mechanism 14 and first end member 12a of
housing 12.
Second discharge plenum 68 includes the portion of interior plenum 13 located
between
crankcase 38 of second compression mechanism 16 and second end member 12b of
housing
12. Suction plenum 69 comprises the portion of interior plenum 13 located
between the
crankcases of first and second compression mechanisms 14, 16. Suction inlet 15
extends
through main housing member 12c and communicates with suction plenum 69. First
and
second discharge tubes 70, 72 extend through first and second end housing
members 12a,
12c, respectively, and communicate with respective discharge plenums 66, 68.
[0028] Referring now to Figs. 1 and 4, top member 42 of each of first and
second
compression mechanisms 14, 16 includes discharge port 56, which provides fluid
communication between compression chambers 52 of first and second compression
mechanisms 14, 16 and respective discharge plenums 66, 68. As illustrated in
Fig. 4, the
outer surface of top member 42 defines recess 58 which surrounds and extends
from
discharge port 56. Discharge valve assembly 60 fits within recess 58 and
includes flexible
discharge valve member 62, rigid valve retainer 64, and valve fastener 65.
Valve assembly
60 is mounted within recess 58 by valve fastener 65, which engages valve
fastener
opening 67.
[OO29] Referring to Figs. 1 and 3, crankcase 38 of each of first and second
compression mechanisms 14, 16 defines inlet opening 74 by which the
refrigerant flows into
compression chamber 52. Compressor assembly 10 can be configured as either a
single-stage
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compressor, in which the refrigerant enters both first and second compressor
mechanisms 14,
16 at suction pressure and is compressed therein and discharged at a final
pressure, or a two-
stage compressor, in which the refrigerant enters first compressor mechanism
14 at suction
pressure, is compressed to an intermediate pressure, and is discharged to
second compressor
mechanism 16 wherein the refrigerant is further compressed to and discharged
at a final
pressure. In first compressor mechanism 14, inlet opening 74 communicates the
refrigerant
from suction plenum 69 to compression chamber 52. In second compressor
mechanism 16,
inlet opening 74 is in fluid communication with compression chamber 52 and
either suction
plenum 69, if compressor assembly 10 is a single-stage compressor, or first
discharge tube
70, if compressor assembly is a two-stage compressor. If compressor assembly
is a two-stage
compressor, first discharge tube 70 may extend from first end housing member
12a, through
main housing member 12c, and join inlet opening 74 of second compressor
mechanism 16.
[0030] Referring now to Figs. 5-7, the configuration of drive shaft 30 and its
engagement with first and second compressor mechanisms 14, I6 will now be
described. As
noted above, drive shaft 30 is a unitary elongate member including elongate
central portion
34 and first and second end portions 32, 36 located on apposite ends of
central portion 34.
Drive shaft 30 may be made of steel or any other rigid material sufficient to
withstand the
pressures and forces generated during operation without deformation or
deflection. Drive
shaft 30 extends along and rotates about rotational axis A-A. Each of first
end portion 32,
central portion 34 and second end portion 36 defines a cross-sectional
configuration oriented
perpendicular to rotational axis A-A. As shown in Figs, 5 and 7, the cross-
sectional
configuration of central portion 34 is substantially circular, while the cross-
sectional
configurations of first and second end portions 32, 36 are substantially non-
circular. The
cross-sectional configurations of first and second end portions 32, 36 define
a pair of
opposing planar flats 33 which give the cross-sectional configurations of
first and second end
portions 32, 36 an outer perimeter that is disposed radially within the outer
perimeter of the
cross-sectional configuration of central portion 34 relative to the rotational
axis A-A. The
cross-sectional configuration of first and second end portions 32, 36 may be
machined into
shaft 30 or, alternatively, shaft 30 may be molded to form by any conventional
method, such
as by investment casting.
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[0031] Turning to Fig. 6, inner roller 44 of each of the roller assemblies 43
of the first
and second compressor mechanisms 14, 16 includes an outer cylindrical surface
which
defines roller axis A~-A~. A shaft mounting opening 46 extends through inner
roller 44 along
a line parallel to but spaced apart from the corresponding roller axis.
Opening 46 has a
substantially non-circular configuration, which includes a pair of opposing
flats 47. The
overall configuration of opening 46 is complementary to the cross-sectional
configurations of
first and second end portions 32, 36 of shaft 30, such that first and second
end portions 32, 36
of shaft 30 may be slip-fit into opening 46 of roller 44 of first and second
compressor
mechanisms 14, 16, respectively. This slip-fit engagement prevents relative
rotation of shaft
30 with respect to inner roller 44. Because opening 46 is offset from the
corresponding roller
axis, the rotation of shaft 30 imparts an orbiting motion to inner roller 44.
[0032] As shown in Fig. 1, first and second end portions 32, 36 of drive shaft
30
extend through and are journaled in crankcase 38 of first and second
compression
mechanisms 14, 16, respectively. Roller 44 of first and second compressor
mechanisms 14,
16 is mounted, as described above, on first and second end portions 32, 36 of
shaft 30. As
shown in Fig. 5, roller 44 of first and second compressor mechanisms 14, 16
may be oriented
on shaft 30 such that roller axis A,-A~ of each of first and second compressor
mechanisms
14, 16 are positioned diametrically opposite one another relative to
rotational axis A-A. Such
an orientation may aid in rotationally balancing shaft 30. In addition or in
the alternative, the
cross-sectional configurations of first and second end portions 32, 36 may be
oriented so as to
be rotationally offset from one another relative to rotational axis A-A. More
specifically, the
cross-sectional configurations of each of first and second end portions 32, 36
defines a line of
symmetry which divides the cross-sectional configuration into two symmetrical
halves. As
shown in Fig. 7, the cross-sectional configurations of first and second end
portions 32, 36
may be oriented such that the line of symmetry of first end portion 32 is
rotationally offset
from the line of symmetry of second end portion 36 by 180° relative to
rotational axis A-A.
(0033] In alternative embodiments, the cross-sectional configurations of first
and
second end portions and their corresponding shaft receiving openings may take
different
shapes. For instance, first and second end portions and their corresponding
shaft receiving
openings may be square, semi-circular, or pentagonal in cross-section.
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[0034] As illustrated in Figs. 1 and 2 and described above, both first and
second
compressor mechanisms 14, 16 may be rotary-type compression mechanisms.
Alternatively,
first and second compressor mechanisms may be any type of compression
mechanism,
including reciprocating-piston mechanisms, orbiting-scroll mechanisms, and
rotary-screw
mechanisms. For instance, first and/or second compressor mechanisms could be
an orbiting-
scroll mechanism such as that disclosed in U.S. Patent No. 5,013,225 to
Richardson, Jr.
which is assigned to Tecumseh Products Company, the assignee of the present
invention and
which is hereby incorporated by reference. In this case, the shaft receiving
opening may be
defined in the hub of the orbiting plate and the shaft may be slip-fit into
the opening. It
should also be understood that first and second compressor mechanisms need not
necessarily
be identical to one another. In other words, first compressor mechanism may be
of a different
type than that of second compressor mechanism.
[0035] In operation, rotor 20 rotates about rotational axis A-A which in turn
causes
the rotation of shaft 30 about axis A-A: The rotation of shaft 30 imparts a
rotational force on
roller 44 of both first and second compressor mechanisms 14, 16. This
rotational force is
translated into an orbiting motion of rollers 44 simultaneously within
chambers 52 of both
first and second compressor mechanisms 14, 16. As roller 44 orbits within
chamber 52, it
engages sliding vane 50 and the inside wall of cylinder block 40 to cause the
crescent-shaped
chamber 52 to expand and contract in size and, thereby, draw in and compress
the refrigerant
within the chambers 52 of first and second compressor mechanisms 14, 16. The
refrigerant is
drawn into suction plenum 69 at suction pressure via suction inlet 15.
[0036] Assuming compressor assembly 10 is a two-stage compressor, the
refrigerant
flows from suction plenum 69 to compression chamber 52 of first compressor
mechanism 15
via inlet opening 74. The refrigerant is compressed within compression chamber
52 of first
compressor mechanism 14. When the pressure of the refrigerant within chamber
52 of first
compressor mechanism 14 reaches a pressure sufficient to bias valve member 62
away from
port 56, the refrigerant is discharged through discharge port 56 into first
discharge plenum 66.
From discharge plenum 66 the refrigerant enters discharge tube 70 and flows to
second
compressor mechanism 16 where it enters compression chamber 52 of second
compressor
mechanism 16 through inlet opening 74 of second compressor mechanism 16. The
refrigerant is then compressed to a higher pressure and is discharged through
discharge port
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56 of second compressor mechanism 16 when the pressure within compression
chamber 52
of second compressor mechanism 16 is sufficient to bias valve member 62 away
fr, om port
56. From second discharge plenum 68 the refrigerant enters second discharge
tube 72 and
exits compressor assembly 10.
[0037] If compressor assembly 10 is conf guyed as a single-stage compressor,
the
refrigerant flows from suction plenum 69 into the compression chambers 52 of
both first and
second compressor mechanisms 14, 16. The refrigerant is then compressed within
compression chambers 52 of frst and second compressor mechanisms 14, 16 and is
discharged through discharge ports 56 and into first and second discharge
plenums 66 and 68,
respectively. From discharge plenums 66, 68 the refrigerant enters discharge
tubes 70, 72,
respectively, and exits the compressor assembly 10.
[0038] In an alternative embodiment shown in Figs. 8-10, compressor 110
generally
includes motor assembly 18, first and second compressor mechanisms 114, 116
and shaft
130, which also does not include unitarily defined eccentric portions. As
shown in Fig. 8,
shaft 130 includes a one-piece elongate member defining first end portion 132
and opposite
second end portion 136. Shaft 130 extends through a central bore in rotor 20
of motor
assembly 18 along rotational axis A-A and is rotatably secured to rotor 20 for
rotation
therewith. First and second end portions 132, 136 of shaft 130 are positioned
adjacent
opposite ends of motor assembly 18. Each of first and second end portions 132,
136 define a
central opening 138 extending axially into frst and second end portions 132,
136 along
rotational axis A-A. Groove 140 extends around the circumference of each of
first and
second end portions 132, 136 (not shown at end portion 132) and extends inward
toward
central opening 138.
[0039] First and second compressor mechanisms 114, 116 each include eccentric
member 144. Eccentric member 144 of first and second compressor mechanisms
114, 116
each includes substantially cylindrical eccentric portion 144a which defines
member axis A~-
A~, and a linking rod 144b extending from eccentric portion 144a along a rod
axis parallel to
but spaced apart from member axis A~-A~. Linking rod 144b is sized and shaped
to fit within
central opening 138 and defines groove 146, which extends around the
circumference of
linking rod 144b. Grooves 140 and 146 cooperate to define a lubrication
passage. Opening
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162 is formed in groove 146 and acts as a lubrication passage for delivering
lubricant to
grooves 140 and 146. Eccentric member defines a lubrication passage 160
extending through
linking rod 144b and eccentric portion 144a along the rod axis.
[0040] An eccentric member 144 may be mounted to each of first and second end
portions 132, 136 of shaft 130 by press fitting linking rod 144b into central
opening 138.
Alternative means may be provided for securing rod 144b in central opening
138. To achieve
optimum balance eccentric members 144 may be oriented on shaft 130 such that
member axis
A~-At of each of first and second compressor mechanisms I 14, 116 are
positioned
diametrically opposite one another relative to rotational axis A-A.
[0041] As illustrated in Figs. 9-10, first and second compressor mechanisms
114, 116
may be reciprocating piston-type compressor mechanisms. First and second
compressor
mechanisms 114, 116 each includes piston 149 which operably engages eccentric
member
144 through linkage key 150. Linkage key 150 includes a ring portion 1 SOa
which is
rotatably mounted about cylindrical eccentric portion 144a of eccentric member
144. Ring
portion 150a includes a lubrication passage 164 for communicating lubrication
fluid to the
mating surfaces of ring portion 1 SOa and eccentric portion 144a. Linkage key
also includes a
linkage arm I SOb which extends from linkage ring and engages piston 149 in a
conventional
manner. The rotation of shaft 130 about rotational axis A-A imparts a
rotational force on
eccentric member 144 causing eccentric member 144 to orbit about rotational
axis A-A. The
orbiting motion of eccentric member 144 imparts a reciprocating motion to
piston 149 within
cylindrical chamber 148 through linkage key 150.
[0042] While Figs. 9-10 illustrate compressor mechanisms 114 and 116 as
reciprocating piston-type mechanisms, it is contemplated that other compressor
mechanisms
may be used. For instance, member 144 could serve as the inner roller of a
rotary-type
compressor mechanism and, therefore, a rotary-type compressor mechanism could
be
mounted to the opposite ends of drive shaft 130.
[0043] While this invention has been described as having an exemplary design,
the
present invention may be further modified within the spirit and scope of this
disclosure. This
application is therefore intended to cover any variations, uses, or
adaptations of the invention
using its general principles.
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