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Claims  |
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What is claimed is:
1. A compressor assembly, comprising:
a hermetically sealed housing defining a discharge pressure space therein;
pressure space therein;
a crankcase within said housing, including a plurality of radially disposed
cylinders formed therein, said crankcase including a cavity into which
said plurality of cylinders open;
a crankshaft rotatably received in said crankcase and having a plurality of
pistons operably connected thereto within said cavity, said pistons being
operably received in respective said cylinders to compress gaseous
refrigerant received therein;
a first muffling chamber and a second muffling chamber located on
respective opposite axial ends of said crankcase, said second muffling
chamber comprising an annular channel formed in said respective axial end,
and a substantially planar, ring-shaped channel cover plate fixedly
mounted to said respective axial end portion at one of a radially inner
adjacent portion and a radially outer adjacent portion of said axial end
with respect to said channel, said cover plate being biased in engagement
with the other of said radially inner adjacent portion and said radially
outer adjacent portion;
means for discharging gaseous refrigerant compressed within said plurality
of cylinders into said first muffling chamber;
gas passage means extending through said crankcase for providing
communication between said first muffling chamber and said second muffling
chamber; and
means for exhausting gaseous refrigerant from said second muffling chamber
into said discharge pressure space, said means comprising an annular
exhaust port defined by an annular space between said cover plate and said
one of said radially inner adjacent portion and said radially outer
adjacent portion.
2. The compressor assembly of claim 1 in which:
said gas passageway means comprises an axial bore extending between said
first muffling chamber and said second muffling chamber through said
crankcase at a radial location between adjacent said cylinders.
3. The compressor assembly of claim 1 and further comprising:
a plurality of valve plates closing respective said cylinders;
discharge valve means operably associated with each of said plurality of
valve plates for discharging compressed gas from within said cylinder
through a respective said valve plate; and
a cylinder head cover associated with each of said plurality of cylinders
and attached to said crankcase with a corresponding said valve plate
interposed therebetween whereby a discharge space is formed by said valve
plate and said head cover, said means for discharging comprising said
discharge valve means, said discharge space, and a respective discharge
passage communicating between each said discharge space and said first
muffling chamber through said crankcase.
4. A compressor assembly, comprising:
a hermetically sealed housing having a discharge pressure space therein;
an electric motor operatively disposed within said housing and having a
rotatable rotor;
a crankcase within said housing, including a plurality of radially disposed
cylinders formed therein, said crankcase including a cavity into which
said plurality of cylinders open;
a crankshaft rotatably connected to said rotor and operably journalled in
said crankcase, said crankshaft having a plurality of pistons operably
connected thereto within said cavity, said pistons being operably received
in respective said cylinders to compress gaseous refrigerant received
therein;
an annular channel formed in said crankcase on the outer surface thereof
adjacent said motor, said channel comprising a radially inner wall and a
radially inner wall and a radially outer wall, each of said radially inner
wall and said radially outer wall having an outwardly facing top surface;
means for discharging gaseous refrigerant compressed within said plurality
of cylinders into said channel;
a channel cover plate;
means for attaching said cover plate to said crankcase at the top surface
of one of said radially inner wall and said radially outer wall such that
said cover plate is biased in engagement with the top surface of the other
of said radially inner wall and said radially outer wall; and
means for exhausting gaseous refrigerant from said channel into said
discharge pressure space, said means comprising an annular exhaust port
defined by an annular space between said cover plate and the top surface
of said one of said radially inner wall and said radially outer wall.
5. A compressor assembly, comprising:
a hermetrically sealed housing having a discharge pressure space therein,
said housing in its operative position having a top end and a bottom end;
a crankcase mounted within said housing and having a top surface and a
bottom surface facing respective said top and bottom ends of said housing,
said crankcase including a plurality of radially disposed cylinders formed
therein, said crankcase also including an inner cavity into which said
plurality of cylinders open;
an electric motor operatively disposed within said housing below said
crankcase, said motor having a stator winding and a rotatable rotor;
a vertical crankshaft operably journalled in said crankcase and extending
outwardly from said bottom surface thereof to rotatably connect with said
rotor, said crankshaft having a plurality of pistons operably connected
thereto within said cavity, said pistons being operably received in
respective said cylinders to compress refrigerant received therein;
a first muffling chamber on said top surface of said crankcase;
means for discharging gaseous refrigerant compressed within said plurality
of cylinders into said first muffling chamber;
an annular channel formed in the bottom surface of said crankcase
surrounding said crankshaft, said channel comprising a radially inner
wall, a radially outer wall, and a bottom wall said crankcase bottom
surface having an inner annular ledge adjacent to and extending radially
inwardly from said radially inner wall and having an outer annular ledge
adjacent to and extending radially outwardly from said radially outer
wall;
gas passage means extending through said crankcase for providing
communication between said first muffling chamber and said annular
channel;
a ring-shaped channel cover plate; and
means for attaching said cover plate to said bottom surface of said
crankcase such that said cover plate is fixedly mounted against one of
said inner and outer ledge while being biased in engagement with the other
of said inner and outer ledge, said attachment means including a plurality
of circumferentially spaced spacers interposed between said cover plate
and said ledge, whereby a substantially unimpeded annular port is provided
for exhausting gaseous refrigerant from said second channel into said
discharge pressure space adjacent said motor stator winding for cooling
thereof.
6. The compressor assembly of claim 5 in which:
said cover plate is fixedly mounted against said inner ledge and is biased
in engagement with said outer ledge, said spacers being interposed between
said cover plate and said inner ledge.
7. The compressor assembly of claim 5 in which:
said gas passage means comprises an axial bore extending between said first
muffling chamber and said channel through said crankcase at a radial
location between adjacent said cylinders.
8. The compressor assembly of claim 5, and further comprising:
a plurality of valve plates closing respective said cylinders;
discharge valve means operably associated with each of said plurality of
valve plates for discharging compressed gas from within said cylinder
through a respective said valve plate; and
a cylinder head cover associated with each of said plurality of cylinders
and attached to said crankcase with a corresponding said cover plate
interposed therebetween, whereby a discharge space is formed by said valve
plate and said head cover, said means for discharging comprising said
discharge valve means, said discharge space, and a respective discharge
passage communicating between each said discharge space and said first
muffling chamber through said crankcase.
9. The compressor assembly of claim 5 in which:
said cover plate comprises a bellville washer.
10. The compressor assembly of claim 5 in which:
said crankshaft extends axially outwardly from said bottom surface of said
crankcase, said annular channel circumscribing said crankshaft on said
bottom surface.
11. The compressor assembly of claim 5 in which:
said plurality of spacers comprise bosses on said cover plate.
12. The compressor assembly of claim 5 in which:
said plurality of spacers comprise washers.
13. The compressor assembly of claim 12 in which:
said means for attaching includes a plurality of bolts extending through
corresponding holes in said cover plate and being received within
corresponding threaded holes in said crankcase bottom surface, said bolts
extending through said washers interposed between said cover plate and
said crankcase bottom surface.
14. The compressor assembly of claim 12 in which:
said means for attaching comprises a plurality of rivets extending through
respective holes in said cover plate and through respective washers
interposed between said cover plate and said crankcase bottom surface to
which said rivets are attached.
15. A compressor assembly, comprising:
a hermetically sealed housing having a discharge pressure space therein;
an electric motor operatively disposed within said housing and having a
rotatable rotor;
a crankcase within said housing, including a cylinder formed therein, said
crankcase including a cavity into which said cylinder opens;
a crankshaft rotatably connected to said rotor and operably journalled in
said crankcase, said crankshaft having a piston operably connected thereto
within said cavity, said piston being operably received in said cylinder
to compress gaseous refrigerant received therein;
an annular channel formed in said crankcase on the outer surface thereof
adjacent said motor, said channel comprising a radially inner wall and a
radially outer wall, each of said radially inner wall and said radially
outer wall having an outwardly facing top surface, said radially inner
wall top surface and said radially outer wall top surface being defined in
parallel offset planes, and one of said radially inner and said radially
outer wall top surfaces being recessed in said crankcase outer surface
with respect to the other one of said radially inner wall and said
radially outer wall top surfaces;
means for discharging gaseous refrigerant compressed within said cylinder
into said channel;
a substantially planar channel cover plate; and
means for attaching said cover plate to said crankcase at the top surface
of one of said inner and said outer walls such that said cover plate is
biased in engagement with the top surface of the other of said inner and
said outer walls, said means for attaching comprising attachment of said
cover plate to said recessed top surface.
16. The compressor assembly of claim 15 in which:
said crankshaft extends axially outwardly from said outer surface of said
crankcase, said annular channel circumscribing said crankshaft on said
outer surface.
17. The compressor assembly of claim 15 in which:
said means for discharging includes a first muffling chamber on the top
outer surface of said crankcase axially opposite said motor, and said
channel and said cover plate comprise a second muffling chamber, whereby
two stage muffling is provided.
18. A compressor assembly, comprising:
a hermetically sealed housing having a discharge pressure space therein;
an electric motor operatively disposed within said housing and having a
rotatable rotor;
a crankcase within said housing, including a cylinder formed therein, said
crankcase including a cavity into which said cylinder opens;
a crankshaft rotatably connected to said rotor and operably journalled in
said crankcase, said crankshaft having a piston operably connected thereto
within said cavity, said piston being operably received in said cylinder
to compress gaseous refrigerant received therein;
an annular channel formed in said crankcase on the outer surface adjacent
said motor, said channel comprising a radially inner wall and a radially
outer wall, each of said radially inner wall and said radially outer wall
having an outwardly facing top surface, said radially inner wall top
surface and said radially outer wall top surface being substantially
coplanar;
means for discharging gaseous refrigerant compressed within said cylinder
into said channel;
a dish-shaped channel cover plate;
means for attaching said cover plate to said crankcase at the top surface
of one of said inner and said outer walls such that said cover plate is
biased in engagement with the top surface of the other of said inner and
said outer walls, said means for attaching comprising attachment of said
cover plate at a raised central portion thereof to said radially inner
wall top surface such that an outer circumferential edge of said cover
plate is biased in engagement with said radially outer wall top surface.
19. The compressor assembly of claim 18 in which said cover plate comprises
a belliville washer. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates generally to a hermetic compressor assembly
and, more particularly, to such a compressor assembly wherein pressurized
gas refrigerant is directed through at least one muffling chamber prior to
being discharged into the interior of the hermetically sealed housing in
the vicinity of the motor windings for cooling thereof.
In general, prior art compressor assemblies of the type to which the
present invention relates, comprise a housing which is hermetically
sealed. Located within the housing are an electric motor and a compressor
mechanism. The electric motor is connected to a crankshaft which has an
eccentric portion thereon. In the case of a scotch yoke reciprocating
piston compressor, the eccentric portion of the crankshaft is located
within a suction cavity defined by a crankcase. Low pressure suction gas
is delivered directly to the suction cavity and is compressed in radially
disposed cylinders by means of piston valve assemblies reciprocably
disposed therein. Gas refrigerant compressed within the cylinder is
discharged through discharge ports and valves associated with a valve
plate mounted to the outside of the crankcase to close off the cylinders.
The discharge gas then typically enters a cylinder head cover mounted on
top of the valve plate and defining a discharge space therein. From the
discharge space defined by the valve plate and the cylinder head cover,
the gas is routed through a muffling system to reduce noise pulsations
produced by the reciprocating nature of the compressor and associated
valving.
In prior art hermetically sealed scotch yoke compressor assemblies, the
interior of the housing is typically at low suction pressure and,
therefore, pressurized discharge gas exiting the cylinder head cover is
directed through a muffler and then discharged outside of the housing. In
such a configuration, a discharge muffler may take the form of a
multi-piece annular muffler assembly mounted to, but not integral with,
the compressor crankcase. A disadvantage of such a system is not only the
complexity associated with assembling such a structure but also the need
for interconnecting tubing from the cylinder head cover to the muffler and
from the muffler to the exterior of the housing.
Another prior art design for a discharge muffler in a multi-cylinder scotch
yoke compressor is the provision of a generally annular cavity in the
bottom surface of the crankcase adjacent the oil sump and opposite the
drive motor. A cover for the cavity in this design takes the form of a
structure incorporating a crankshaft bearing and an oil pump. This
particular prior art discharge muffler system further requires that
discharge tubing connect into the annular cavity and communicate with the
exterior of the housing.
Disadvantages of the aforementioned prior art muffling systems include the
lack of provision for a two-stage muffler for a scotch yoke reciprocating
piston compressor. Furthermore, the prior art systems are not entirely
applicable to a compressor assembly having a pressurized housing into
which discharge gas is released. More specifically, none of the prior art
discharge muffler systems provides for effective cooling of the motor
windings adjacent the compressor crankcase.
SUMMARY OF THE INVENTION
The present invention overcomes the disadvantages of the above-described
prior art muffler systems for scotch yoke compressor assemblies by
providing an improved muffling system for directing gas from within the
cylinder head cover through an annular discharge muffler chamber having a
cover plate that directs the discharge gas toward the motor windings for
cooling thereof.
Generally, the invention provides, in one form thereof, a compressor
assembly comprising a hermetically sealed pressurized housing, a
compressor assembly within the housing including a crankcase, an annular
channel formed in the outside surface of the crankcase into which
compressed gas is discharged, and a cover plate associated with the
annular channel to define an annular muffling chamber and to allow for
release of discharge gas from within the muffling chamber to the housing
interior.
More specifically, the invention provides, in one form thereof, a two-stage
muffler system for a hermetically sealed scotch yoke compressor assembly
wherein a first muffling chamber and a second muffling chamber are located
on respective opposite axial ends of the compressor crankcase. Gas
passages extend through the crankcase for providing communication between
the first and second muffling chambers. Accordingly, compressed gas
discharged from cylinders within the compressor crankcase is directed into
a first annular muffling chamber, and then proceeds through passageways in
the crankcase to the second annular muffling chamber before being
discharged into the housing. The second discharge chamber may be
positioned adjacent the drive motor to provide cooling thereof upon
release of compressed discharge gas into the housing interior. To this
end, the cover plate for the annular channel formed in the crankcase
adjacent the motor is attached so as to provide an annular space
permitting for release of the discharge gas. In one form of the present
invention, attachment of the cover plate to the crankcase is accomplished
by attachment at one radially extreme and by biased engagement at the
other radial extreme.
An advantage of the muffler system of the present invention is that a
simple, inexpensive cover plate is provided for an annular chamber formed
in a compressor crankcase.
Another advantage of the discharge muffler system of the present invention
is that two-stage muffling is provided for greater noise reduction.
A still further advantage of the discharge muffler according to the present
invention is the provision of an annular exhaust port adjacent the motor
windings for 360.degree. expulsion of the discharge gas from the second
muffling stage directed toward the motor windings.
Yet another advantage of the discharge muffler cover plate of the present
invention is the ease of assembly wherein mounting of the cover plate to
the crankcase is performed at only one circumferential edge of the cover
plate.
Another advantage of the discharge muffler according to the present
invention is that less material is required by providing annular chambers
integral with the crankcase.
Yet another advantage of the discharge muffler according to the present
invention is that a discharge muffler stage is provided with a minimum
number of parts.
A still further advantage of the discharge muffler in accordance with the
present invention is that the annular chamber in the crankcase is spaced
from the rotating shaft, thereby obviating the need for a slip fit or
journalled fit between the muffler and the crankshaft.
The compressor assembly of the present invention, in one form thereof,
provides a hermetically sealed housing defining a discharge space therein.
A crankcase is also provided within the housing including a plurality of
radially disposed cylinders formed therein. The crankcase also includes a
cavity into which the plurality of cylinders open. A crankshaft is
rotatably received in the crankcase and has a plurality of pistons
operably connected thereto within the cavity. The pistons are operably
received in respective cylinders to compress gaseous refrigerant received
therein. A first muffling chamber and a second muffling chamber are
located on respective opposite axial ends of the crankcase. Gas passage
means extend through the crankcase and provide communication between the
first muffling chamber and the second muffling chamber. Means are also
provided for discharging gaseous refrigerant compressed within the
cylinders into the first muffling chamber. Also, means are provided for
exhausting gaseous refrigerant from the second muffling chamber into the
discharge pressure space.
There is further provided, in one form of the present invention, a
compressor assembly comprising a hermetically sealed housing having a
discharge pressure space therein. An electric motor is operatively
disposed within the housing and has a rotatable rotor. A crankcase within
the housing includes a plurality of radially disposed cylinders formed
therein. The crankcase also includes a cavity into which the plurality of
cylinders opens. Furthermore, a crankshaft is rotatably connected to the
rotor and is operably journalled in the crankcase. The crankshaft has a
plurality of pistons operably connected thereto within the cavity, the
pistons being operably received in respective cylinders to compress
gaseous refrigerant received therein. An annular channel is formed in the
crankcase on the outer surface thereof adjacent the motor. The channel
comprises a radially inner wall and a radially outer wall, each wall
having an outwardly facing top surface. Means are provided for discharging
gaseous refrigerant compressed within the cylinders into the channel. A
channel cover plate is provided, as well as means for attaching the cover
plate to the crankcase at the top surface of one of the inner and outer
walls such that the cover plate is biased in engagement with the top
surface of the other wall.
The compressor assembly of the present invention further provides, in one
form thereof, a hermetically sealed housing having a discharge pressure
space therein, the housing having a top end and a bottom end in its
operative position. A crankcase is mounted within the housing and has a
top surface and a bottom surface facing the respective top and bottom ends
of the housing. The crankcase includes a plurality of radially disposed
cylinders formed therein. The crankcase also includes an inner cavity into
which the plurality of cylinders open. An electric motor is operatively
disposed within a housing below the crankcase and has a stator winding and
a rotatable rotor. A vertical crankshaft operably journalled in the
crankcase extends from the bottom surface thereof to rotatably connect
with the rotor. The crankshaft has a plurality of pistons operably
connected thereto within the cavity. Furthermore, the pistons are operably
received in respective cylinders to compress gaseous refrigerant received
therein. A first muffling chamber is provided on the top surface of the
crankcase. Means are provided for discharging gaseous refrigerant
compressed within the plurality of cylinders into the first muffling
chamber. An annular channel formed in the bottom surface of the crankcase
surrounds the crankshaft and comprises a radially inner wall, a radially
outer wall, and a bottom wall. The crankcase bottom surface has an inner
annular ledge adjacent to and extending radially inwardly from the inner
wall. The crankcase bottom surface also has an outer annular ledge
adjacent to and extending radially outwardly from the outer wall. Gas
passage means extend through the crankcase providing communication between
the first muffling chamber and the annular channel. A ring-shaped channel
cover plate is provided, as well as means for attaching the cover plate to
the bottom surface of the crankcase. Attachment of the cover plate to the
crankcase is such that the cover plate is fixedly mounted against the
inner ledge while being biased in engagement with the outer ledge. The
attachment means also includes a plurality of circumferentially spaced
spacers interposed between the cover plate and the inner ledge.
Accordingly, a substantially unimpeded annular port is provided for
exhausting gaseous refrigerant from the second channel into the discharge
pressure space adjacent the motor stator winding for cooling thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side sectional view of a compressor of the type to which the
present invention pertains;
FIG. 2 is a fragmentary sectional view of the compressor of FIG. 1 taken
along the line 2--2 in FIG. 1 and viewed in the direction of the arrows;
FIG. 3 is a top view of the crankcase of the compressor of FIG. 1, showing
a sectional view of the housing taken along the line 3--3 in FIG. 1 and
viewed in the direction of the arrows;
FIG. 4 is a fragmentary sectional view of the crankcase and housing
assembly of FIG. 3 taken along the line 4--4 in FIG. 3 and viewed in the
direction of the arrows with portions removed to better illustrate the
crankcase structure;
FIG. 5 is an enlarged front view of a muffler cover plate of the compressor
of FIG. 1, in accord with the present invention;
FIG. 6 is a sectional view of the muffler cover plate of FIG. 5 taken along
the line 6--6 in FIG. 5 and viewed in the direction of the arrows; and
FIG. 7 is a sectional view similar to FIG. 6 of an alternative embodiment
of the muffler cover plate of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In an exemplary embodiment of the invention as shown in the drawings, and
in particular by referring to FIG. 1, a compressor assembly 10 is shown
having a housing generally designated at 12. The housing has a top portion
14, a central portion 16, and a bottom portion 18. The three housing
portions are hermetically secured together as by welding or brazing. A
mounting flange 20 is welded to the bottom portion 18 for mounting the
compressor in a vertically upright position. Located within hermetically
sealed housing 12 is an electric motor generally designated at 22 having a
stator 24 and a rotor 26. The stator is provided with windings 28. Rotor
26 has a central aperture 30 provided therein into which is secured a
crankshaft 32 by an interference fit. A terminal cluster 34 is provided in
central portion 16 of housing 12 for connecting the compressor to a source
of electric power. Where electric motor 22 is a three-phase motor,
bidirectional operation of compressor assembly 10 is achieved by changing
the connection of power at terminal cluster 34.
Compressor assembly 10 also includes an oil sump 36 located in bottom
portion 18. An oil sight glass 38 is provided in the sidewall of bottom
portion 18 to permit viewing of the oil level in sump 36. A centrifugal
oil pick-up tube 40 is press fit into a counterbore 42 in the end of
crankshaft 32. Oil pick-up tube 40 is of conventional construction and
includes a vertical paddle (not shown) enclosed therein.
Also enclosed within housing 12, in the embodiment of FIG. 1, is a
compressor mechanism generally designated at 44. Compressor mechanism 44
comprises a crankcase 46 including a plurality of mounting lugs 48 to
which motor stator 24 is attached such that there is an annular air gap 50
between stator 24 and rotor 26. Crankcase 46 also includes a
circumferential mounting flange 52 axially supported within an annular
ledge 54 in central portion 16 of the housing. A bore 236 extends through
flange 52 to provide communication between the top and bottom ends of
housing 12 for return of lubricating oil and equalization of discharge
pressure within the entire housing interior.
Compressor mechanism 44, as illustrated in the preferred embodiment, takes
the form of a reciprocating piston, scotch yoke compressor. More
specifically, crankcase 46 includes four radially disposed cylinders, two
of which are shown in FIG. 1 and designated as cylinder 56 and cylinder
58. The four radially disposed cylinders open into and communicate with a
central suction cavity 60 defined by inside cylindrical wall 62 in
crankcase 46. A relatively large pilot hole 64 is provided in a top
surface 66 of crankcase 46. Various compressor components, including the
crankshaft, are assembled through pilot hole 64. A top cover such as cage
bearing 68 is mounted to the top surface of crankcase 46 by means of a
plurality of bolts 70 extending through bearing 68 into top surface 66.
When bearing 68 is assembled to crankcase 46, an O-ring seal 72 isolates
suction cavity 60 from a discharge pressure space 74 defined by the
interior of housing 12.
Crankcase 46 further includes a bottom surface 76 and a bearing portion 78
extending therefrom. Retained within bearing portion 78, as by press
fitting, is a sleeve bearing assembly comprising a pair of sleeve bearings
80 and 82. Two sleeve bearings are preferred rather than a single longer
sleeve bearing to facilitate easy assembly into bearing portion 78.
Likewise, a sleeve bearing 84 is provided in cage bearing 68, whereby
sleeve bearings 80, 82, and 84 are in axial alignment. Sleeve bearings 80,
82, and 84 are manufactured from steel-backed bronze.
A sleeve bearing, as referred to herein, is defined as a generally
cylindrical bearing surrounding and providing radial support to a
cylindrical portion of a crankshaft, as opposed to a thrust bearing which
provides axial support for the weight of the crankshaft and associated
parts. A sleeve bearing, for example, may comprise a steel-backed bronze
sleeve insertable into a crankcase, or a machined cylindrical surface made
directly in the crankcase casting or another frame member.
Referring once again to crankshaft 32, there is provided thereon journal
portions 86 and 88, wherein journal portion 86 is received within sleeve
bearings 80 and 82, and journal portion 88 is received within sleeve
bearing 84. Accordingly, crankshaft 32 is rotatably journalled in
crankcase 46 and extends through a suction cavity 60. Crankshaft 32
includes a counterweight portion 90 and an eccentric portion 92 located
opposite one another with respect to the central axis of rotation of
crankshaft 32 to thereby counterbalance one another. The weight of
crankshaft 32 and rotor 26 is supported on thrust surface 93 of crankcase
46.
Eccentric portion 92 is operably coupled by means of a scotch yoke
mechanism 94 to a plurality of reciprocating piston assemblies
corresponding to, and operably disposed within, the four radially disposed
cylinders in crankcase 46. As illustrated in FIG. 1, piston assemblies 96
and 98, representative of four radially disposed piston assemblies
operable in compressor assembly 10, are associated with cylinders 56 and
58, respectively.
Scotch yoke mechanism 94 comprises a slide block 100 including a
cylindrical bore 102 in which eccentric portion 92 is journalled. In the
preferred embodiment, cylindrical bore 102 is defined by a steel backed
bronze sleeve bearing press fit within slide block 100. A reduced diameter
portion 103 in crankshaft 32 permits easy assembly of slide block 100 onto
eccentric portion 92. Scotch yoke mechanism 94 also includes a pair of
yoke members 104 and 106 which cooperate with slide block 100 to convert
orbiting motion of eccentric portion 92 to reciprocating movement of the
four radially disposed piston assemblies. For instance, FIG. 1 shows yoke
member 106 coupled to piston assemblies 96 and 98, whereby when piston
assembly 96 is at a bottom dead center (BDC) position, piston assembly 98
will be at a top dead center (TDC) position.
Referring once again to piston assemblies 96 and 98, each piston assembly
comprises a piston member 108 having an annular piston ring 110 to allow
piston member 108 to reciprocate within a cylinder to compress gaseous
refrigerant therein. Suction ports 112 extending through piston member 108
allows suction gas within suction cavity 60 to enter cylinder 56 on the
compression side of piston 108.
A suction valve assembly 114 is also associated with each piston assembly,
and will now be described with respect to piston assembly 96 shown in FIG.
1. Suction valve assembly 116 comprises a flat, disk-shaped suction valve
116 which in its closed position covers suction ports 112 on a top surface
118 of piston member 108. Suction valve 116 opens and closes by virtue of
its own inertia as piston assembly 96 reciprocates in cylinder 56. More
specifically, suction valve 116 rides along a cylindrical guide member 120
and is limited in its travel to an open position by an annular valve
retainer 122.
As illustrated in FIG. 1, valve retainer 122, suction valve 116, and guide
member 120 are secured to top surface 118 of piston member 108 by a
threaded bolt 124 having a buttonhead 128. Threaded bolt 124 is received
within a threaded hole 126 in yoke member 106 to secure piston assembly 96
thereto. As shown with respect to the attachment of piston assembly 98 to
yoke member 106, an annular recess 130 is provided in each piston member
and a complementary boss 132 is provided on the corresponding yoke member,
whereby boss 132 is received within recess 130 to promote positive,
aligned engagement therebetween.
Compressed gas refrigerant within each cylinder is discharged through
discharge ports in a valve plate. With reference to cylinder 58 in FIG. 1,
a cylinder head cover 134 is mounted to crankcase 46 with a valve plate
136 interposed therebetween. A valve plate gasket 138 is provided between
valve plate 136 and crankcase 46. Valve plate 136 includes a coined recess
140 into which buttonhead 128 of threaded bolt 124 is received when piston
assembly 98 is positioned at top dead center (TDC).
A discharge valve assembly 142 is situated on a top surface 144 of valve
plate 136. Generally, compressed gas is discharged through valve plate 136
past an open discharge valve 146 that is limited in its travel by a
discharge valve retainer 148. Guide pins 150 and 152 extend between valve
plate 136 and cylinder head cover 134, and guidingly engage holes in
discharge valve 146 and discharge valve retainer 148 at diametrically
opposed locations therein. Valve retainer 148 is biased against cylinder
head cover 134 to normally retain discharge valve 146 against top surface
144 at the diametrically opposed locations. However, excessively high mass
flow rates of discharge gas or hydraulic pressures caused by slugging may
cause valve 146 and retainer 148 to be guidedly lifted away from top
surface 144 along guide pins 150 and 152.
Referring once again to cylinder head cover 134, a discharge space 154 is
defined by the space between top surface 144 of valve plate 136 and the
underside of cylinder head cover 134. Cover 134 is mounted about its
perimeter to crankcase 46 by a plurality of bolts 135, shown in FIG. 2.
Discharge gas within discharge space 154 associated with each respective
cylinder passes through a respective connecting passage 156, thereby
providing communication between discharge space 154 and a top annular
muffling chamber 158. Chamber 158 is defined by an annular channel 160
formed in top surface 66 of crankcase 46, and cage bearing 68. As
illustrated, connecting passage 156 passes not only through crankcase 46,
but also through holes in valve plate 136 and valve plate gasket 138.
Top muffling chamber 158 communicates with a bottom muffling chamber 162 by
means of passageways 234 extending through crankcase 46. Chamber 162 is
defined by an annular channel 164 and a muffler cover plate 166. Cover
plate 166, as shown in FIGS. 5 and 6 in accord with a preferred embodiment
of the present invention, is an annular metal plate including three
circumferentially spaced holes 165 extending therethrough at a radially
inward circumferential portion 167 of plate 166. In an alternative
embodiment of the present invention, cover plate 166 may take the form of
a bellville washer, as illustrated in FIG. 7. Cover plate 166 is mounted
against bottom surface 76 at the location of holes 165 by bolts 168
extending therethrough and into threaded holes 169 (FIG. 3) in the
crankcase. Bolts 168 may also take the form of rivets or the like.
A plurality of spacers 170, each associated with a respective hole 165 and
bolt 168, space cover plate 166 from bottom surface 76 approximately 0.050
inches at inward portion 167 of cover plate 166 to form an annular exhaust
port 172. Spacers 170 may take the form of an annular boss integral with
plate 166 and associated with each hole 165 on an outer face 173 of plate
166. Alternatively, spacers 170 may comprise separate washers interposed
between plate 166 and bottom surface 76 through which bolts 168 extend. A
radially outward circumferential portion 171 of cover plate 166 is biased
in engagement with bottom surface 76 to prevent escape of discharge gas
from within bottom muffling chamber 162 at this radially outward location.
Compressor assembly 10 of FIG. 1 also includes a lubrication system
associated with oil pick-up tube 40 previously described. Oil pick-up tube
40 acts as an oil pump to pump lubricating oil from sump 36 upwardly
through an axial oil passageway 174 extending through crankshaft 32. An
optional radial oil passageway 176 communicating with passageway 174 may
be provided to initially supply oil to sleeve bearing 82. The disclosed
lubrication system also includes annular grooves 178 and 180 formed in
crankshaft 32 at locations along the crankshaft adjacent opposite ends of
suction cavity 60 within sleeve bearings 80 and 84. Oil is delivered into
annular grooves 178, 180 behind annular seals 182, 184, respectively
retained therein. Seals 182, 184 prevent high pressure gas within
discharge pressure space 74 in the housing from entering suction cavity 60
past sleeve bearings 84 and 80, 82, respectively. Also, oil delivered to
annular grooves 178, 180 behind seals 182 and 184 lubricate the seals as
well as the sleeve bearings.
Another feature of the disclosed lubrication system of compressor assembly
10 in FIG. 1, is the provision of a pair of radially extending oil ducts
186 from axial oil passageway 174 to a corresponding pair of openings 188
on the outer cylindrical surface of eccentric portion 92.
A counterweight 190 is attached to the top of shaft 32 by means of an
off-center mounting bolt 192. An extruded hole 194 through counterweight
190 aligns with axial oil passageway 174, which opens on the top of
crankshaft 32 to provide an outlet for oil pumped from sump 36. An
extruded portion 196 of counterweight 190 extends slightly into passageway
174 which, together with bolt 192, properly aligns counterweight 190 with
respect to eccentric portion 92.
Referring now to FIG. 2, an upper portion of compressor mechanism 44 is
shown to better illustrate the discharge muffling system in accord with
the present invention. More specifically, FIG. 2 further shows connecting
passage 156 of FIG. 1 as comprising a plurality of bores 230, associated
with each radially disposed cylinder arrangement, to connect between
discharge space 154 within cylinder head cover 134 and top muffling
chamber 158. Also shown in FIGS. 2 and 3 is a suction inlet opening 232
included in crankcase 46, providing communication between the outside of
the crankcase and suction cavity 60 defined therein.
FIGS. 3 and 4 provide views of the crankcase showing three gas passageways
234 extending through crankcase 46 at circumferentially spaced locations
between cylinders t | | |
