Note: Descriptions are shown in the official language in which they were submitted.
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W. Travis Horton
Robert D. Mowatt
Dan Hadesh
DRIVE SHAFT FOR COMPRESSOR
CROSS REFERENCE TO RELATED APPL1CATION
[0001] This application claims the benefit under 35 U.S.C. ~ 119(e) of U.S.
Provisional Patent Application Serial No. 60/626,787, entitled DRIVE SHAFT FOR
COMPRESSOR, filed on November 10, 2004, the entire disclosure of which is
hereby
expressly incorporated by reference herein.
BACKGROUND OF THE INVENT10N
1. Field of the Invention.
[0002] 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.
2. Description of the Related Art.
[0003] 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.
[0004] 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,
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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 vibration and noise produced by the compressor. However, oftentimes
the
eccentric portions define a larger cross-section than that of the drive shaft
and cannot fit
through the bore of the rotor. Consequently, it is difficult to assemble such
a compressor
using a one-piece shaft. Instead, these compressors require a two-piece drive
shaft that is
joined inside the rotor. However, 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.
[0005] 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
[0006] The present invention provides a compressor assembly that includes a
driveshaft and at least one eccentric press-fit to the shaft. In one
embodiment, the driveshaft
includes an opening at a first end and the eccentric includes a linking rod
press-fit into the
opening. During assembly, the first end of the shaft is inserted through an
opening in a rotor
and the eccentric is then press-fit to the first end. This arrangement allows
the opening in the
rotor to closely receive the driveshaft and allows the eccentric to be
assembled to the
compressor without passing the eccentric through the rotor opening. In use,
the eccentric is
operably engaged with a compressor mechanism such as, for example, a rotary
compression
mechanism, a reciprocating piston mechanism, or an orbiting scroll mechanism.
In one
embodiment, a second eccentric is press-fit to a second end of the driveshaft
and is operably
engaged with a second compressor mechanism.
(0007] Owing to the press-fit relationship described above, in one embodiment,
a set
screw, fastener, pin, or welding process is not required to maintain the
relative position of the
eccentric and the driveshaft, as required by previous compressors.
Advantageously, the time
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and cost to machine recesses for receiving the fasteners, pins or set screws
can be eliminated.
Additionally, in previous compressors, these recesses may wear or fret over
time allowing the
fasteners, pins, or set screws to come loose.
[0008] In one form, a compressor comprises a motor including a rotor, a
driveshaft
operably engaged with the rotor, the driveshaft including a first end
extending from the rotor;
and a first eccentric press-fit to the first end of the driveshaft.
[0009] In one form, a compressor comprises a motor, a driveshaft operably
engaged
with the motor, and a first eccentric, wherein one of the driveshaft and the
first eccentric
includes a first opening, and wherein the other of the driveshaft and the
first eccentric is
press-fit into the opening.
[0010] In one form, a method of assembling a compressor comprises the steps of
inserting a first end of a driveshaft through an opening in a rotor, securing
the rotor to the
driveshaft, and press-fitting a first eccentric to the first end of the
driveshaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0091] 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:
[0092] Figure 1 is a sectional view of a dual mechanism hermetic compressor
assembly according to the present invention;
[0013] Figure 2 is a sectional view of the compressor assembly of Fig. 1 taken
along
lines 2-2;
[0014] Figure 3 is an inner end perspective view of the crankcase/shaft
assembly of
the compressor assembly of Fig. 1;
[OOHS] Figure 4 is an outside end view of the compressor mechanism of the
compressor assembly of Fig. 1;
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[006] Figure 5 is a perspective view of the shaft roller assembly of the
compressor
assembly of Fig. 1;
[0017] Figure 6 is a perspective view of the inner roller of the compressor
assembly
of Fig. I;
[0018] Figure 7 is a perspective view of the shaft of the compressor assembly
of Fig.
l;
[0019] Figure 8 is a perspective view of a shaft according to another
embodiment of
the present invention;
[0020] Figure 9 is a perspective view of a shaft/eccentric/piston assembly
according
to the embodiment of Fig. 8; and
[0021] Figure 10 is a sectional view of compressor assembly with the assembly
in
Fig. 9.
[0022] Corresponding reference characters indicate corresponding parts
throughout
the several views. Although the exemplifications set out herein illustrate
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 1M'VENTION
[0023] Referring first to Fig. 1, 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 I2c. Housing members
12a,
I Zb, 12c are hermetically sealed to one another to define interior volume 13.
[0024] Still refen-ing to Fig. 1, motor assembly l 8 defines first end 26 and
opposite
second end 28 and includes rotor 20, stator 22 and stator windings 24. Motor
assembly I 8 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
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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.
[00251 As illustrated in Fig. 1, drive shaft 30 is integrally formed as a
single unit and
defines first 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 18 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
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
described in further
detail below.
[0026] 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.
[0027] As shown in Figs. 1 and 2, roller assembly 43 is disposed within
compression
chamber 52 and includes eccentric inner roller 44 and main roller 48 rotatably
mounted about
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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.
[0028] Referring to Fig, l, 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
through legs 41 of crankcase 38, and engaging the bolts to threaded holes (not
shown) in
stator 22.
[0029] As illustrated in Figs. 1 and 3-4, crankcase 38 defines a substantially
cylindrical perimetrical sidewall 45 that firmly and sealingly bears against
main housing
member 12c. The firm 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
ofhousing 12.
Second discharge plenum 68 includes the portion of interior plenum 13 located
between
crankcase 38 of second compression mechanism I 6 and second end member 12b of
housing
12. Suction plenum 69 comprises the portion of imerior 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.
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[0030j 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.
[t)031j 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
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 intem~ediate 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 l 0 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.
[OO32j Referring now to Figs. 5-7, the configuration of drive shaft 30 and its
engagement with first and second compressor mechanisms 14, 16 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 opposite 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,
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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 radialty 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.
[0033] Turning to Fig. 6, inner roller 44 of each of the roller assemblies 43
of 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.
[0034j 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
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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.
[0035] 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.
[0036] 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. 5,0I3,225 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
t)~pe than that of second compressor mechanism.
[0037j 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 ofboth 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
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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.
[0038] 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 refi~gerant 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
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
from port
56. From second discharge plenum 68 the refrigerant enters second discharge
tube 72 and
exits compressor assembly 10.
[0039] If compressor assembly 10 is configured 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 first 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.
[0040] In an alternative embodiment, shown in Figs. 8-10, compressor 110
generally
includes motor assembly l 8, first compressor mechanism 114, second compressor
mechanism 116, and shaft 130 operably engaged with compressor mechanisms 114
and 116.
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
central bore 21
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
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adjacent opposite ends of motor assembly 18. Each of first and second end
portions 132, 136
define a central opening 138 extending axially into first and second end
portions 132, 136
along rotational axis A-A.
[0041] Referring to Figs. 8-10, first and second compressor mechanisms 114,
116
each include an eccentric member 144. Each eccentric member 144 includes
substantially
cylindrical eccentric portion 144a which defines member axis A~-A~, and
linking rod 144b
extending from eccentric portion 144a along a rod axis substantially parallel
to but spaced
apart from member axis A~-A~. In the present embodiment, linking rod 144b has
a
substantially cylindrical outer surface 145 and a diameter that is slightly
larger than the
diameter of central opening 138. As a result, when linking rod 144b is
inserted into opening
138, inner surface l39 of central opening 138 bears against outer surface 145
of linking rod
144b such that they are in a press-fit, or interference-fit, relationship.
Owing to the press-fit
relationship, eccentric member 144 does not rotate with respect to shaft 130.
[0042] Owing to the press-fit relationship described above, in one embodiment,
a set
screw, fastener, pin, or welding process is not required to maintain the
relative position of
eccentric member 144 and shaft 130, as required by previous compressors.
Advantageously,
the time and cost to machine recesses for receiving the fasteners, pins or set
screws can be
eliminated. Additionally, these recesses may wear or fret over time allowing
the fasteners,
pins, or set screws to come loose. Further, owing to the press-fit of
eccentric 144 into
opening 138, as illustrated in Figs. 8 and 9, the overall size of the
compressor can be reduced.
More particularly, in previous compressors, the diameter of the eccentric was
determined by
the stroke length, or throw, needed to operate the compressor in addition to
the diameter of
the shaft received therein, thereby resulting in a large eccentric. In the
present embodiment,
the diameter of eccentric 144, as it is not placed over shaft 130, is not
determined by the
diameter of shaft 130. Stated in another way, eccentric portion 144a can be
smaller than
previous eccentric portions, as it does not need to be enlarged to accommodate
shaft 130
therein. As a result, the rollers or pistons operably engaged with eccentrics
144 can be
moved closer to the shaft, resulting in a more compact compressor.
[0043] To assemble compressor 110, in the present embodiment, first end 132 of
shaft
130 is inserted through opening 21 of rotor 20. Thereafter, linking rod 144b
is aligned with
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opening 138 such that, for example, outer surface 145 of linking rod 144b is
substantially
concentric with inner surface 139 of opening 138. Thereafter, a force is
applied to eccentric
member 144 and/or shaft 130 in a direction substantially parallel to axis A-A.
This force
causes wall 141 surrounding opening 138 to flex or expand outwardly as linking
rod 144b is
pressed into opening 138. A second eccentric member 144 can then be assembled
to second
end portion 136. Alternatively, the second eccentric member 144 can be
assembled to shaft
130 prior to inserting first end 132 through opening 21 of rotor 20. In a
further alternative
embodiment, the second eccentric can be integral with shaft 130. In this
embodiment, second
end 136 is not inserted through opening 21, and thus, the eccentric may be
integral with the
shaft.
[0044] In the illustrated embodiment, each eccentric member 144 includes a
recess or
groove 146 which extends around the circumference of linking rod 144b. Shaft
130 also
includes grooves 140 which extend around the outer circumference of first and
second end
portions l 32 and 136 (not shown at end portion 132) and lubmcant apertures
162 which
extend between the inside surface of shaft 130 and grooves 140. In operation,
grooves 146
of linking rods 144b cooperate with lubricant apertures 162 of shaft 130 to
define a
lubrication passage between the interior of shaft 130 and the outside surface
of shaft 130. In
use, oil flows from lubricant apertures 162 into grooves 146 on the outside
surface of shaft
I 30 to lubricate the relative rotational movement between the shaft and
bearings supporting
the shaft, for example. In the present embodiment, each eccentric member 144
further
includes a lubricant aperture l 60 which extends beWeen end l 61 of linking
rod 144b and the
outside surface of eccentric portion 144a. In operation, oil can flow from the
interior of shaft
130 to the outside surface of eccentric member 144 to lubricate the relative
rotational
movement between linkage key 150 and eccentric member 144, as described in
further detail
below.
[0045] In an alternative embodiment, eccentric members 144 may have recesses
in
lieu of linking rods 144b that engage end portions 132 and 136 of shaft 130 in
a press-fit
relationship. In one embodiment, the recesses have non-circular geometries and
end portions
132 and I36 have complementary non-circular cross-sections that are closely
received and
press-fit within the recesses of eccentric members 144.
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[0046] As discussed above, 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~-A~ of each of first and second compressor mechanisms 114,
116 are
positioned diametrically opposite one another relative to rotational axis A-A.
[0047] 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 1 SOa includes a lubrication passage 164 for communicating
lubrication fluid to the
mating surfaces of ring portion 150a and eccentric portion I44a. Linkage key
150 also
includes a linkage arm I SOb which extends from linkage ring and engages
piston 149 in a
conventional manner. The rotation of shaft l30 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 I50.
[0048] While Figs. 9-10 illustrate compressor mechanisms 1 I4 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 I 30.
[0049] 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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