Note: Descriptions are shown in the official language in which they were submitted.
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,SCROLL MACHINE WITH FLOATING SEAL
The present invention relates to seals for scroll-type machinery, and
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more particularly to a multi-function floating seal for axially compliant
scroll compressors.
BACKGROUND AND SUMMARY OF THE INVENTION
A typical scroll machine has an orbiting scroll member having a spiral
wrap on one face thereof, a non-orbiting scroll member having a spiral wrap on
one face thereof, said wraps being entermeshed with one another, and means for
causing said orbiting scroll member to orbit about an axis with respect to
said non-orbiting scroll member, whereby said wraps will create pockets of
progressively changing volume.
To maximize efficiency, it is important for the wrap tips of each scroll
member to sealingly engage the end plate of the other scroll member so that
there is minimum leakage therebetween. One way this has been accomplished,
other than by using tip seals (which are very difficult to assemble and which
often present reliability problems) is by using fluid under pressure to
axially bias one of the scroll members against the other scroll member. This,
of course, requires seals in order to isolate the biasing fluid at the desired
pressure. Accordingly, there is a continuing need in the field of scroll
machines for improved axial biasing techniques, including improved seals to
facilitate same.
The seals of the present invention are embodied in a compressor_ and
suited for use in machines which use discharge pressure alone, discharge and
an independent intermediate pressure, or solely an intermediate pressure only,
in order to provide the necessary axial biasing forces to enhance tip sealing.
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In addition, the seals of the present invention, which in most
embodiments are three seals in one, are suitable for use in
applications which bias the non-orbiting scroll or those which
bias the orbiting scroll, although they are particularly suited
for the former.
The invention provides a multi-function seal assembly
comprising: (a) an annular inner lip seal adapted to sealingly
engage the outside of a first cylindrical surface; (b) an
annular outer lip seal adapted to sealingly engage the inside
of a second cylindrical surface, said seal assembly being
mounted for movement along the center axes of said seals; (c)
first and second clamping elements clamping said first and
second seals therebetween; and (d) a third annular seal
operatively associated with one of said elements and being
adapted to sealingly engage a generally flat annular sealing
surface. The improved seals disclosed herein are relatively
simple in construction, easy to install and inspect, and
effectively provide the complex sealing functions desired. The
seals of the present invention can provide significant
additional advantages. For example, the seal has been
discovered to be particularly sensitive to the pressure ratio
of the scroll machine and consequently provides particularly
good protection against vacuum conditions such as caused by
reverse rotation or a blocked suction condition. In this
condition, the seal will become ineffective and thus permit
discharge gas to be bypassed directly into a zone of suction
gas at suction gas pressure. This prevents the creation of a
high vacuum on the inlet side of the compressor which might
otherwise occur and which could cause excessive and damaging
forces pulling the scroll members together. Even more
importantly, it prevents the arcing or burning of the motor
protector connector pins which has been observed to occur under
some vacuum conditions.
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The seals of the present invention also, in some
applications, provide a degree of temperature protection,
particularly in motor-compressors where suction gas is used to
cool the motor. This is because the seal will leak from the
high side to the low side at pressure differentials which are
significantly higher than those for which the machine was
designed. This leakage of discharge fluid to the suction side
of the compressor will cause the machine to have a reduced
output and the resulting heat build-up within the compressor
enclosure due to the reduced flow of cooling gas will cause the
standard motor protector to trip and shut the machine down.
This characteristic of the seals of the present invention
therefore provides a degree of protection in certain
applications from excessive discharge temperatures which could
result from loss of working fluid charge, or from a blocked
condensor fan in a refrigeration system, or from an excessive
discharge pressure (for whatever reason). All of these
undesirable conditions will cause a scroll machine to function
at a pressure ratio greater than that which is designed into
the machine in terms of its predetermined fixed volume ratio.
The invention also provides a scroll machine
comprising: (a) a hermetic shell; (b) an orbiting scroll
member disposed in said shell and having a first spiral wrap on
one face thereof; (c) a non-orbiting scroll member disposed in
said shell and having a second spiral wrap on one face thereof,
said spiral wraps being intermeshed with one another; (d) means
for causing said orbiting scroll member to orbit about an axis
with respect to said non-orbiting scroll member whereby said
wraps will create pockets of progressively changing volume
between a suction pressure zone defining a suction pressure and
a discharge pressure zone defining a discharge pressure; (e)
means defining a cavity disposed within one of said scroll
members; (f) means defining a fluid path between said discharge
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pressure zone and said suction pressure zone; (g) means for
supplying intermediate pressurized fluid to said cavity, said
intermediate pressurized fluid being at a pressure inbetween
said suction and discharge pressures; and (h) seal means
disposed in said cavity to isolate said intermediate
pressurized fluid in said cavity whereby said seal means
engages another component of said compressor to close said
fluid path and said discharge pressure zone.
The invention further provides a scroll machine
comprising: (a) a hermetic shell; (b) an orbiting scroll
member disposed in said shell and having a first spiral wrap on
one face thereof; (c) a non-orbiting scroll member disposed in
said shell and having a second spiral wrap on one face thereof,
said spiral wraps being intermeshed with one another; (d) means
for causing said orbiting scroll member to orbit about an axis
with respect to said non-orbiting scroll member whereby said
wraps will create pockets of progressively changing volume to
compress a working fluid between a suction pressure zone
defining a suction pressure and a discharge pressure zone
defining a discharge pressure; (e) means defining a cavity
disposed within one of said scroll members; (f) means defining
a fluid path between said discharge pressure zone and said
suction pressure zone; (g) means for supplying said working
fluid under pressure to said cavity; and (h) seal means
disposed to move in said cavity between a first position
wherein said seal means engages another component of said
scroll machine to isolate said discharge pressure zone from
said suction pressure zone and a second position in which a
leakage of fluid in said discharge pressure zone into said
suction pressure zone is permitted.
The invention still further provides a scroll machine
comprising: (a) a hermetic shell; (b) an orbiting scroll
member disposed in said shell and having a first spiral wrap on
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one face thereof; (c) a non-orbiting scroll member disposed in
said shell and having a second spiral wrap on one face thereof,
said wraps being intermeshed with one another; (d) means for
causing said orbiting scroll member to orbit about an axis with
respect to said non-orbiting scroll member whereby said wraps
will create pockets of progressively changing volume; (e) means
for mounting one of said scroll members for limited axial
movement with respect to the other scroll member; (f) means
defining an annular cavity exposed to a surface of one of said
scroll members which will cause pressurized fluid in said
cavity to bias said one scroll member toward the other scroll
member, said cavity having an inner wall surface and an outer
wall surface; (g) means disposed within said cavity defining a
fluid leakage path between said cavity and the interior of said
shell; (h) means for supplying fluid under pressure to said
cavity for biasing said scroll members axially together; and
(i) annular seal means sealingly engaging said means for
defining a fluid leakage path and being disposed in said
cavity, said seal means having first and second seals sealingly
engaging said inner and outer wall surfaces, respectively, to
isolate said pressurized fluid in said cavity from said leakage
path.
Advantages of the present invention will become more
apparent when viewed in light of the accompanying drawings and
following detailed description.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
Figure 1 is a partial vertical sectional view through
a scroll machine in which fluid pressure is used to bias the
non-orbiting scroll member axially against the orbiting scroll
member, and which embodies the principles of the present
invention;
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Figure 2 is an enlarged vertical sectional view of a
floating seal forming a part of the Figure 1 first embodiment
of the invention, shown in its relaxed state;
Figure 3 is a sectional view taken along line 3-3 of
Figure 2 and having line 2-2 showing where the section of
Figure 2 is taken;
Figure 4 is a view similar to Figure 1 showing a
second embodiment of the floating seal of the present
invention;
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Figure 5 is an enlarged vertical sectional view of a
portion of the seal shown in Figure 4;
Figure 6 is an enlarged vertical sectional view of the
floating seal of the embodiment of Figure 4, shown in its
relaxed state;
Figure 7 is a sectional view taken along line 8-8 in
Figure 6 and having line 6-6 showing where the section of
Figure 6 is taken;
Figure 8 is a fragmentary view similar to Figure 1
showing a third embodiment of the floating seal of the present
invention;
Figure 9 is an enlarged vertical cross-sectional view
of the floating seal of Figure 8, shown in its relaxed state;
Figure 10 is a sectional view taken along line 10-10
in Figure 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the present~invention is suitable for incorpora-
tion in many different types of scroll machines, for exemplary
purposes it will be described herein incorporated in a scroll
refrigerant compressor of the general structure illustrated in
vertical section in Figure 1. Generally speaking, the compressor
comprises a cylindrical hermetic shell 10 having welded at the
upper end thereof a cap 12, which is provided with a refrigerant
discharge fitting 14 optionally having the usual discharge valve
therein (not shown). Other elements affixed to the shell include
a transversely extending partition 16 which is welded about its
periphery at the same point that cap 12
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is welded to shell 10, a main bearing housing 18 which is affixed to shell 10
at a plurality of points in any desirable manner, and a suction gas inlet
fitting 17 having a gas deflector 19 disposed in communication therewith
inside the shell.
A motor stator 20 which is generally square in cross-section but with the
corners rounded off is press fit into shell 10. The flats between the rounded
corners on the stator provide passageways between the stator and shell,
indicated at 22, which facilitate the flow of lubricant from the top of the
shell to the bottom. A crankshaft 24 having an eccentric crank pin 26 at the
upper end thereof is rotatably journaled in a bearing 28 in main bearing
housing 18 and a second bearing in a lower bearing housing (not shown).
Crankshaft 24 has at the lower end the usual relatively large diameter
oil-pumping concentric bore (not shown) which communicates with a radially
outwardly inclined smaller diameter bore 30 extending upwardly therefrom to
the top of the crankshaft. The lower portion of the interior shell 10 is
filled with lubricating oil in the usual manner and the pump at the bottom of
the crankshaft is the primary pump acting in conjunction with bore 30, which
acts as a secondary pump, to pump lubricating fluid to all of the various.
portions of the compressor which require lubrication.
Crankshaft 24 is rotatively driven by an electric motor including stator
20, windings 32 passing therethrough, and a rotor 34 press fit on the
crankshaft and having one or more counterweights 36. A motor protector 35, of
the usual type, is provided in close proximity to motor windings 32 so that if
the motor exceeds~its normal temperature range the protector will deenergize
the motor.
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The upper surface of main bearing housing 18 is provided with an annular
flat thrust bearing surface 38 on which is disposed an orbiting scroll member
40 comprising an end plate 42 having the usual spiral vane or wrap 44 on the
upper surface thereof, an annular flat thrust surface 46 on the lower surface,
and projecting downwardly therefrom a cylindrical hub 48 having a journal
bearing 50 therein and in which is rotatively disposed a drive bushing 52
having an inner bore 54 in which crank pin 26 is drivingly disposed. Crank
pin 26 has a flat on one surface (not shown) which drivingly engages a flat
surface in a portion of bore 54 (not shown) to provide a radially compliant
driving arrangement, such as shown in assignee's U.S. Letters Patent No.
4,877,382, the disclosure of which is herein incorporated by reference.
Wrap 44 meshes with a non-orbiting spiral wrap 56 forming a part of
non-orbiting scroll member 58 which is mounted to main bearing housing 18 in
any desired manner which will provide limited axial movement of scroll member
58. The specific manner of such mounting 15 not relevant to the present
invention, however, in the present embodiment, for exemplary purposes,
non-orbiting scroll member 58 has a plurality of circumferentially spaced
mounting bosses 60, one of which is shown, each having a flat upper surface 62
and an axial bore 64 in which is slidably disposed a sleeve 66 which is bolted
to main bearing housing 18 by a bolt 68 in the manner shown. Bolt 68 has an
enlarged head having a flat lower surface 70 which engages surface 62 to limit
the axially upper or separating movement of non-orbiting scroll member,
movement in the opposite direction being limited by axial engagement of the
lower tip surface of wrap 56 and the flat upper surface of orbiting scroll
member 40.
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Non-orbiting scroll member 58 has a centrally disposed discharge
passageway 72 communicating with an upwardly open recess 74 which is in fluid
communication via an opening 75 in partition 16 with the discharge muffler
chamber 76 defined by cap 12 and partition 16. Non-orbiting scroll member 58_
has in the upper surface thereof an annular recess 78 having parallel coaxial
side walls in which is. sealingly disposed for relative axial movement an
annular floating seal 80 which serves to isolate the bottom of recess 78 from
the presence of gas under suction and discharge pressure so that it can be
placed in fluid communication with a source of intermediate fluid pressure by
means of a passageway 82. The non-orbiting scroll member is thus axially
biased against the orbitisxg scroll member by the forces created by discharge
pressure acting on the central portion of scroll member 58 and those created
by intermediate fluid pressure acting on the bottom of recess 78. This axial
pressure biasing, as well as various techniques for supporting scroll member
58 for limited axial movement, are disclosed in much greater detail in
assignee's aforesaid U.S. Letters Patent No. 4,877,328.
Relative rotation of the scroll members is prevented by the usual Oldham
coupling comprising a ring 82 having a first pair of keys 84 (one of which is
shown) slidably disposed in diametrically opposed slots 86 (one of which is
shown) in scroll member 58 and a second pair of keys (not shown) slidably
disposed in diametrically opposed slots (not shown) in scroll member 40.
The compressor is preferably of the "low side" type in which suction gas
entering via deflector 19 is allowed, in part, to escape into,the shell and
assist in cooling the motor. So long as there is an adequate flow of
returning suction gas the motor will remain within desired temperature limits.
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When this flow ceases, however, the loss of cooling will cause motor protector
35 to trip and shut the machine down.
The scroll compressor as thus far broadly described is either now known
in the art or is the subject matter of other pending applications for patent
by applicants' assignee. The details of construction which incorporate the
principles of the present invention are those which deal with several
embodiments of a novel multi-function floating seal.
With reference to Figures 1-S, the floating seal of the first embodiment
is of a coaxial sandwiched construction and comprises an annular base plate
100, cast out of aluminum or the like, having a plurality of equally spaced
upstanding integral projections 102 each having an enlarged base portion 104.
Disposed on plate 100 is an annular gasket 106 formed of epoxy coated fiber
gasket material having a plurality of equally spaced holes which receive base
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portions 104, on top of which is disposed a pair of normally flat identical
lower lip seals 108 formed of glass filled PTFE (approximately SX) and
optionally including 5X MoS2, by weight. Seals 108 have a plurality of
equally spaced holes which receive base portions 104. On top of seals 108 is
disposed an annular spacer plate 110, which can be a simple steel stamping,
having annular recesses 112 and 114 on the top and bottom surfaces thereof and
a plurality of equally spaced holes which receive base portions 104, and on
top of plate 110 are a pair of normally flat identical annular upper lip seals
116 formed of the same material as lip seals 108 and maintained in coaxial
position by means 'of an annular upper seal plate 118 having a, plurality of
equally spaced holes receiving projections 102 and an annular rim 120 disposed
in recess 112. Seal plate 118, which may be formed of grey cast.iron, has
disposed about the inner periphery thereof an upwardly projecting planar
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sealing lip 122. The assembly is secured together by swaging the ends of each
of the projections 102, as indicated at 123.
The overall seal assembly therefore provides three distinct seals;
namely, an inside diameter seal at 124 and 126, an outside diameter seal at
128 and a top seal at 130, as best seen in Figure 1. Seal 124 is between the
inner periphery of lip seals 108 and the inside wall of recess 78, and seal
12b is between the inner periphery of lip seals 116 and the inside wall of
recess 78. Seals 124 and 126 isolate fluid under intermediate pressure in the
bottom of recess 78 from fluid under discharge pressure in recess 74. Seal
128 is between the outer periphery of lip seals 108 and the outer wall of
recess 78, and isolates fluid under intermediate pressure in the bottom of
recess 78 from fluid at suction pressure within shell 10. Seal 130 is betwen
lip seal 122 and an annular wear ring 132, formed of cast iron or the like and
affixed to partition 16 by a suitable adhesive in a position surrounding
opening 75, and isolates fluid at suction pressure from fluid at discharge
pressure across the top of the seal assembly. In lieu of a separate wear ring
132 for the upper seal the lower surface of partition 16 surrounding opening
75 can be locally hardened, by nitriding, carbo-nitriding or the like.
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The diameter of seal 130 is chosen so that there is a positive upward
sealing force on seal 80 under normal operating conditions, i.e., at normal
pressure differentials. Therefore, when excessive pressure differentials are
encountered, the seal will be forced downwardly by discharge pressure, thereby
permitting a leak of high side discharge gas directly across the seal-to a
zone of low side suction gas. If this leakage is great enough, then the
resultant loss of flow of motor-cooling suction gas (aggravated by the
excessive temperature of the leaking discharge gas) will cause the motor
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protector to trip, thereby deenergizing the motor. The width of seal 130 is
chosen so that the unit pressure on the seal itself (i.e., between seal 122
and seat 132) is greater than normally encountered discharge pressure, thus
insuring consistant sealing.
With reference to Figures 4-7, the floating seal of the second embodiment
is also of a coaxial sandwiched construction and comprises an annular base
plate 200, cast out of aluminum or the like and having an annular upstanding
integral rib 202. Disposed on plate 200 is a lower inner lip seal 204 formed
of SX glass and 5X molydisulfide filled PTFE and having a conical resilient
sealing lip 206; and an outer lip seal 208 of the same material having a
resilient conical sealing lip 210. Disposed on top of inner seal 204 and
inside rib 202 is an annular metal separator plate 212 having minutely ribbed
upper and lower surfaces to increase mechanical contact with the seals. On
top of plate 110 are a pair of identical annular upper lip seals 214 formed of
the same material as lip seals 206 and 208, also maintained in coaxial
position by means of an annular rib 202, and an upper seal element 216 having
disposed about the inner periphery thereof an upwardly projecting planar
sealing lip 218. Seals 214 have resilient conical inner sealing lips 220.
Seal plate 118 is preferably formed of cast iron. Outer seal 208 is retained
in place by an annular metal ring 222, and the entire assembly is secured
together by swaging the top of rib 202 at spaced locations, as indicated at
224.
This seal assembly also provides three distinct seals; namely, an inside
diameter seal at 226 and 228, an outside diameter seal at 230 and a top seal
at 232, as best seen in Figure 4. Seal 226 is between the inner periphery of
lip seal 204 and the inside wall of recess 78, and seal 228 is between the
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inner periphery of lip seals 214 and the inside wall of recess 78. Seals 226
and 228 isolate fluid under intermediate pressure in the bottom of recess 78
from fluid under discharge pressure in recess 74. Seal 230 is between the
outer periphery of lip seal 208 and the outer wall of recess 78, and isolates
fluid under intermediate pressure in the bottom of recess 78 from fluid at
suction pressure within shell 10. Seal 232 is between lip seal 218 and
annular wear ring 132 surrounding opening 75 in partition 16, and isolates
fluid at suction pressure from fluid at discharge pressure across the top of
the seal assembly. The diameter and width of the top seal are chosen in the
same manner as for the first embodiment.
With reference to Figure 8-10, the floating seal of the third embodiment
is also of a coaxial sandwiched construction and comprises an annular base
plate 300, cast out of alumminum or the like, having a plurality of equally
spaced upstanding integral projections 302 projecting from a shallow annular
rib 304. Disposed on the inner periphery of plate 300 inside rib 304 are a
pair of normally flat identical inner lip seals 306 formed of suitably filled
PTFE. Disposed on top of the outer periphery of plate 300, outside rib 304,
are a pair of normally flat identical annular outer lip seals 308 formed of
the same material as lip seals 306. Both pairs of seals are maintained in
coaxial position by means of rib 304, and are clamped in place by an annular
upper seal plate 310 having a plurality of equally spaced holes receiving
projections 302. Seal plate 118, which is preferably formed of grey cast
iron, stamped steel or powered metal, has disposed about the inner periphery
thereof an upwardly projecting planar sealing lip 312. The assembly is
secured together by swaging the ends of each of the projections 302, as
indicated at 314.
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Again, the overall seal assembly therefor provides
three distinct seals; namely, an inside diameter seal at 316,
an outside diameter seal at 318 and a top seal at 320, as best
seen in Figure 8. Seal 316 is between the inner periphery of
lip seals 306 and the inside wall of recess 78. Seal 316
isolates fluid under intermediate pressure in the bottom of
recess 78 from fluid under discharge pressure in recess 74.
Seal 318 is between the outer periphery of Zip seals 308 and
the outer. wall of recess 78, and isolates fluid under intermediate
pressure in the bottom of recess 78 from fluid at suction
pressure within shell 10. Seal 320 is between lip seal 312 and
annular wear ring 132 surrounding opening 75 in partition 16,
and isolates fluid at suction pressure from fluid at discharge
pressure across the top of the seal assembly. The diameter and
width of the top seal are chosen in the same manner as for the
first embodiment.
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In order to prevent excessive intermediate pressure
from building up between the inner and outer seals, which would
occur in a liquid slugging situation and could blow out the
high-side seal, a suitable vent can be provided, such as at 125
in Figure 2 and at 316 in Figure 8.
While this invention has been described in connection
with these particular examples, no limitation is intended
except as defined by the following claims. The skilled
practitioner will realize that other modifications may be made
without departing from the spirit of this invention after
studying the specification and drawings.
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