U.S. patent application number 12/015571 was filed with the patent office on 2009-07-23 for key coupling and scroll compressor incorporating same.
This patent application is currently assigned to Bitzer Scroll Inc.. Invention is credited to James W. Bush, Ronald J. Duppert.
Application Number | 20090185927 12/015571 |
Document ID | / |
Family ID | 40568717 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090185927 |
Kind Code |
A1 |
Duppert; Ronald J. ; et
al. |
July 23, 2009 |
Key Coupling and Scroll Compressor Incorporating Same
Abstract
A scroll compressor includes a movable scroll compressor body
and a fixed scroll compressor body that are arranged for relative
orbital movement relative to one another to facilitate compression
of refrigerant. To guide the orbital movement, a Oldham key
coupling is provided that may include four keys spaced in separate
quadrants for guiding movement of the scroll compressor body along
a linear translational path along a lateral axis. Additionally,
running clearances may be unequally and non-symmetrically arranged
so as to prevent unwanted rotation of one of the scroll compressor
bodies and thereby prevent unwanted edge loading.
Inventors: |
Duppert; Ronald J.;
(Fayetteville, NY) ; Bush; James W.; (Skaneateles,
NY) |
Correspondence
Address: |
REINHART BOERNER VAN DEUREN P.C.
2215 PERRYGREEN WAY
ROCKFORD
IL
61107
US
|
Assignee: |
Bitzer Scroll Inc.
East Syracuse
NY
|
Family ID: |
40568717 |
Appl. No.: |
12/015571 |
Filed: |
January 17, 2008 |
Current U.S.
Class: |
418/55.1 |
Current CPC
Class: |
F01C 17/066 20130101;
F04C 18/0215 20130101 |
Class at
Publication: |
418/55.1 |
International
Class: |
F04C 18/02 20060101
F04C018/02 |
Claims
1. A scroll compressor, comprising: a housing; scroll compressor
bodies including a first scroll compressor body and a second scroll
compressor body, the second scroll compressor body being moveable
relative to the housing, the scroll compressor bodies having
respective bases and respective scroll ribs that project from the
respective bases and which mutually engage, the scroll ribs
generally surrounding a central axis, wherein the scroll compressor
bodies are movable relative to one another along first and second
lateral axes, the first and second lateral axes and the central
axis being generally mutually perpendicular; and a key coupler
acting upon the second scroll compressor body, the second scroll
compressor body being movable relative to the key coupler along the
second lateral axis, the key coupler having a first pair of
cooperating sliding contacts with the second scroll compressor body
including first and second contacts that act on a same side of the
first lateral axis and on opposite sides of the second lateral
axis, respectively, and wherein different keys provide said
different first and second contacts.
2. The scroll compressor of claim 1, wherein the first and second
contacts are confined to only on the same side of the first lateral
axis.
3. The scroll compressor of claim 2, further including a second
pair of cooperating sliding contacts between the key coupler and
the second scroll compressor body, including third and fourth
contacts that act only upon an opposite side of the first lateral
axis relative to the first pair, the third and fourth contacts
acting on opposite sides of the second lateral axis,
respectively.
4. The scroll compressor of claim 3, wherein the second scroll
compressor body includes first and second guide flanges, and
wherein the key coupler includes a ring body and four keys
projecting from the ring body to provide the first, second, third
and fourth contacts, each key being in a separate one of the four
quadrants defined by the first and second lateral axes, wherein the
first flange slides along the second axis between the first and
second keys, and wherein the second flange slides along the second
axis between the third and fourth keys.
5. The scroll compressor of claim 4, wherein the key coupler is
slidable relative to the first scroll compressor body along the
first axis, the key coupler including fifth and sixth keys
projecting from the ring body, the fifth and sixth keys being
received in first and second keyway slots defined by the first
scroll compressor body, respectively, the fifth and sixth keys and
the first and second keyway slots being aligned on the first
lateral axis.
6. The scroll compressor of claim 1, wherein the first and second
contacts are provided along projecting keys provided by one of the
second scroll and the key coupler, and wherein the keys engage
along a surface that is not a slot.
7. The scroll compressor of claim 6, wherein the keys are part of
the key coupler and project from a ring body, and wherein the
movement along the second lateral axis is guided free of slots and
free of ear structures on the second scroll compressor body.
8. The scroll compressor of claim 1, wherein the first scroll
compressor body is fixed relative to the housing and wherein the
second scroll compressor body is moveable about an orbital path
relative to the housing and the first scroll compressor body.
9. A scroll compressor, comprising: scroll compressor bodies
including a first scroll compressor body and a second scroll
compressor body, the first and second scroll compressor bodies
having respective bases and respective scroll ribs that project
from the respective bases and which mutually engage; a key coupler
acting upon the second scroll compressor body, the second scroll
compressor body being linearly movable relative to the key coupler
by a contact interface between the key coupler and the second
scroll compressor body, wherein the contact interface includes at
least four keys.
10. The scroll compressor of claim 9, wherein the second scroll
compressor body includes first and second guide flanges, and
wherein the key coupler includes a ring body with the at least four
keys projecting from the ring body toward the second scroll
compressor body, wherein the first flange slides along the second
axis between the first and second keys, and wherein the second
flange slides along the second axis between the third and fourth
keys.
11. The scroll compressor of claim 10, wherein the key coupler is
linearly slidable relative to the first scroll compressor body, the
key coupler including fifth and sixth keys projecting from the ring
body, the fifth and sixth keys being received in first and second
keyway slots defined by the first scroll compressor body,
respectively, for facilitating relative linear movement.
12. The scroll compressor of claim 9, wherein the at least four
keys are not received in slots.
13. The scroll compressor of claim 9, wherein the first scroll
compressor body is fixed relative to a housing and wherein the
second scroll compressor body is moveable relative to the housing
and the first scroll compressor body about an orbital path.
14. A scroll compressor, comprising: a housing; a drive unit
contained in the housing having a rotary output on an output shaft
that rotates about a central axis, the shaft including an offset
drive segment that is offset relative to the central axis; scroll
compressor bodies in the housing including a fixed scroll
compressor body and a movable scroll compressor body, the scroll
compressor bodies having respective bases and respective scroll
ribs that project from the respective bases and which mutually
engage, the scroll ribs generally surrounding the central axis,
wherein the fixed scroll compressor body is fixed relative to the
housing; and wherein the movable scroll compressor body has a drive
hub projecting from the base slidably receiving the segment wherein
rotation of the drive shaft is operative drive the moveable scroll
member along an orbital path; a key coupler between the second
scroll compressor body guiding movement of the moveable member
along first and second lateral axes, the first and second lateral
axes being generally mutually perpendicular with the central axis,
wherein the moveable scroll compressor body includes first and
second guide flanges, and wherein the key coupler includes a ring
body and four keys projecting from the ring body toward the movable
scroll compressor body to provide first, second, third and fourth
contacts, each key being in a separate one of the four quadrants
defined by the first and second lateral axes, wherein the first
flange slides along the second axis between the first and second
keys, and wherein the second flange slides along the second axis
between the third and fourth keys, and wherein the key coupler
including fifth and sixth keys projecting from the ring body, the
fifth and sixth keys being received in first and second keyway
slots defined by the fixed scroll compressor body, respectively,
for facilitating relative linear movement along the first lateral
axis.
15. The scroll compressor of claim 14, wherein the first, second,
third and fourth keys are not received in slots.
16. The scroll compressor of claim 15, further comprising a
non-symmetrical running clearance between the four keys and the
movable scroll compressor body, the non-symmetrical running
clearance arranged to correct key clearance backlash and minimize
edge loading wear.
17. The scroll compressor of claim 16, wherein the non-symmetrical
running clearance is accomplished through offset placement of pairs
of keys relative to the second lateral axis.
18. The scroll compressor of claim 17 wherein the non-symmetrical
running clearance is accomplished through offset placement of the
guide flanges relative to the second lateral axis.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to scroll
compressors for compressing refrigerant and more particularly to
key couplings often referred to in the art as "Oldham Couplings"
for preventing relative angular movement between the scroll members
as they orbit relative to each other.
BACKGROUND OF THE INVENTION
[0002] A scroll compressor is a certain type of compressor that is
used to compress refrigerant for such applications as
refrigeration, air conditioning, industrial cooling and freezer
applications, and/or other applications where compressed fluid may
be used. Such prior scroll compressors are known, for example, as
exemplified in U.S. Pat. Nos. 6,398,530 to Hasemann; 6,814,551, to
Kammhoff et al.; 6,960,070 to Kammhoff et al.; and 7,112,046 to
Kammhoff et al., all of which are assigned to a Bitzer entity
closely related to the present assignee. As the present disclosure
pertains to improvements that can be implemented in these or other
scroll compressor designs, the entire disclosures of U.S. Pat. Nos.
6,398,530; 7,112,046; 6,814,551; and 6,960,070 are hereby
incorporated by reference in their entireties.
[0003] As is exemplified by these patents, scroll compressors
conventionally include an outer housing having a scroll compressor
contained therein. A scroll compressor includes first and second
scroll compressor members. A first compressor member is typically
arranged stationary and fixed in the outer housing. A second scroll
compressor member is moveable relative to the first scroll
compressor member in order to compress refrigerant between
respective scroll ribs which rise above the respective bases and
engage in one another. Conventionally the moveable scroll
compressor member is driven about an orbital path about a central
axis for the purposes of compressing refrigerant. An appropriate
drive unit, typically an electric motor, is provided usually within
the same housing to drive the movable scroll member.
[0004] One of the common approaches for preventing relative
rotation or movement between the scroll members as they orbit
relative to each other is through the use of what is commonly
referred to as an "Oldham coupling". As exemplified by the patents
referenced herein, an Oldham coupling typically includes a ring
structure that has two sets of keys. One set of keys slides in one
linear direction on a surface of the orbiting scroll compressor
body while the other set of keys slides at right angles on a fixed
surface such as along the fixed scroll compressor body as
illustrated but not numbered in the '551 patent (see also the
Oldham key coupling at 90 in the '530 patent). For one of the set
of keys, the orbiting scroll compressor body will commonly employ
two slots spaced 180.degree. apart in separate quadrants defined by
the mutually perpendicular axes as for example is illustrated in
FIG. 10. Such slots receive the two keys of the Oldham coupling
guiding linear translational movement along one lateral axis. As
also shown in FIG. 10, the slots are typically provided for through
the provision of outwardly projecting ears. The movable scroll
compressor body slots are positioned in substantial spaced relation
from the respective axes so as to provide for carrying moment loads
necessary to prevent relative angular movement between the movable
and fixed scroll compressor bodies.
[0005] The present invention is directed towards improvements over
prior Oldham coupling configurations and scroll compressors
incorporating the same.
BRIEF SUMMARY OF THE INVENTION
[0006] In one aspect, the present invention provides contacts
between a key coupling and a movable scroll body that act in
adjacent quadrants. A scroll compressor according to this aspect
comprises scroll compressor bodies (including a first scroll
compressor body and a second scroll compressor body) having
respective bases and respective scroll ribs that project from the
respective bases and which mutually engage. The second scroll
compressor body is moveable relative to a housing. The scroll ribs
generally surround a central axis with scroll compressor bodies
moveable relative to one another along first and second lateral
axes (in which the first and second lateral axes and the central
axis are generally mutually perpendicular). A key coupler acts upon
the second scroll compressor body with the second scroll compressor
body movable relative to the key coupler along the second lateral
axis. The key coupler has a first pair of cooperating sliding
contacts that prevent relative rotation in opposing directions,
including first and second contacts that act on a same side of the
first lateral axis and also on opposite sides of the second lateral
axis, respectively.
[0007] Another aspect of the present invention pertains to four
keys of contact between a key coupler and one of the scroll
compressor bodies. According to this aspect, a scroll compressor
comprises scroll compressor bodies (including a first scroll
compressor body and a second scroll compressor body) having
respective bases and respective scroll ribs that project from the
respective bases and which mutually engage. A key coupler acts upon
the second scroll compressor body with the second scroll compressor
body being linearly movable relative to the key coupler by a
contact interface between the key coupler and the second scroll
compressor body. This contact interface is provided by at least
four keys.
[0008] Other aspects, objectives and advantages of the invention
will become more apparent from the following detailed description
when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings incorporated in and forming a part
of the specification illustrate several aspects of the present
invention and, together with the description, serve to explain the
principles of the invention. In the drawings:
[0010] FIG. 1 is a cross section of a scroll compressor assembly in
accordance with an embodiment of the present invention;
[0011] FIG. 2 is a partial cross section and cut-away view of an
isometric drawing of an upper portion of the scroll compressor
embodiment shown in FIG. 1;
[0012] FIG. 3 is a similar view to FIG. 2 but enlarged and taken
about a different angle and section in order to show other
structural features;
[0013] FIG. 4 is a partial cross section and cut-away view of a
lower portion of the embodiment of FIG. 1;
[0014] FIG. 5 is a partially cross sectional cutaway symmetric view
of the scroll compressor bodies and an Oldham key coupling in
accordance with an embodiment of the present invention;
[0015] FIG. 6 is an exploded view of the movable scroll member and
the Oldham key coupling used in previous embodiments;
[0016] FIG. 7 is a top view of the movable scroll member shown with
running clearances (in which the running clearances are greatly
exaggerated for demonstrative purposes) and Oldham key contacts
shown in accordance with an embodiment of the present
invention;
[0017] FIGS. 8 and 9 are illustrations similar to FIG. 7 except
showing a symmetrical Oldham key placement (again with exaggerated
running clearances shown) to illustrate that some unwanted rotation
of the scroll and edge loading of key surfaces could otherwise
occur without the non-symmetrical key contact surfaces of FIG.
7;
[0018] FIG. 10 is a top view of a movable scroll member using a
more conventional two slot arrangement for receiving two keys of an
Oldham coupling.
[0019] While the invention will be described in connection with
certain preferred embodiments, there is no intent to limit it to
those embodiments. On the contrary, the intent is to cover all
alternatives, modifications and equivalents as included within the
spirit and scope of the invention as defined by the appended
claims.
DETAILED DESCRIPTION OF THE INVENTION
[0020] An embodiment of the present invention is illustrated in the
figures as a scroll compressor assembly 10 generally including an
outer housing 12 in which a scroll compressor 14 can be driven by a
drive unit 16. The scroll compressor assembly may be arranged in a
refrigerant circuit for refrigeration, industrial cooling,
freezing, air conditioning or other appropriate applications where
compressed fluid is desired. Appropriate connection ports provide
for connection to a refrigeration circuit and include a refrigerant
inlet port 18 and a refrigerant outlet port 20 extending through
the outer housing 12. The scroll compressor assembly 10 is operable
through operation of the drive unit 16 to operate the scroll
compressor 14 and thereby compress an appropriate refrigerant or
other fluid that enters the refrigerant inlet port 18 and exits the
refrigerant outlet port 20 in a compressed high pressure state.
[0021] The outer housing 12 may take many forms. In the preferred
embodiment, the outer housing includes multiple shell sections and
preferably three shell sections to include a central cylindrical
housing section 24, a top end housing section 26 and a bottom end
housing section 28. Preferably, the housing sections 24, 26, 28 are
formed of appropriate sheet steel and welded together to make a
permanent outer housing 12 enclosure. However, if disassembly of
the housing is desired, other housing provisions can be made that
can include metal castings or machined components.
[0022] The central housing section 24 is preferably cylindrical and
telescopically interfits with the top and bottom end housing
sections 26, 28. This forms an enclosed chamber 30 for housing the
scroll compressor 14 and drive unit 16. Each of the top and bottom
end housing sections 26, 28 are generally dome shaped and include
respective cylindrical side wall regions 32, 34 to mate with the
center section 24 and provide for closing off the top and bottom
ends of the outer housing 12. As can be seen in FIG. 1, the top
side wall region 32 telescopically overlaps the central housing
section 24 and is exteriorly welded along a circular welded region
to the top end of the central housing section 24. Similarly the
bottom side wall region 34 of the bottom end housing section 28
telescopically interfits with the central housing section 24 (but
is shown as being installed into the interior rather than the
exterior of the central housing section 24) and is exteriorly
welded by a circular weld region.
[0023] The drive unit 16 may preferably take the form of an
electrical motor assembly 40, which is supported by upper and lower
bearing members 42, 44. The motor assembly 40 operably rotates and
drives a shaft 46. The electrical motor assembly 40 generally
includes an outer annular motor housing 48, a stator 50 comprising
electrical coils and a rotor 52 that is coupled to the drive shaft
46 for rotation together. Energizing the stator 50 is operative to
rotatably drive the rotor 52 and thereby rotate the drive shaft 46
about a central axis 54.
[0024] With reference to FIGS. 1 and 4, the lower bearing member 44
includes a central generally cylindrical hub 58 that includes a
central bushing and opening to provide a cylindrical bearing 60 to
which the drive shaft 46 is journaled for rotational support. A
plurality of arms 62 and typically at least three arms project
radially outward from the bearing central hub 58 preferably at
equally spaced angular intervals. These support arms 62 engage and
are seated on a circular seating surface 64 provided by the
terminating circular edge of the bottom side wall region 34 of the
bottom outer housing section 28. As such, the bottom housing
section 28 can serve to locate, support and seat the lower bearing
member 44 and thereby serves as a base upon which the internal
components of the scroll compressor assembly can be supported.
[0025] The lower bearing member 44 in turn supports the cylindrical
motor housing 48 by virtue of a circular seat 66 formed on a
plate-like ledge region 68 of the lower bearing member 44 that
projects outward along the top of the central hub 58. The support
arms 62 also preferably are closely toleranced relative to the
inner diameter of the central housing section. The arms 62 may
engage with the inner diameter surface of the central housing
section 24 to centrally locate the lower bearing member 44 and
thereby maintain position of the central axis 54. This can be by
way of an interference and press-fit support arrangement between
the lower bearing member 44 and the outer housing 12 (See e.g. FIG.
4). Alternatively according to a more preferred configuration, as
shown in FIG. 1, the lower bearing engages with the lower housing
section 28 which is in turn attached to center section 24.
Likewise, the outer motor housing 48 may be supported with an
interference and press-fit along the stepped seat 66 of the lower
bearing member 44. As shown, screws may be used to securely fasten
the motor housing to the lower bearing member 44.
[0026] The drive shaft 46 is formed with a plurality of
progressively smaller diameter sections 46a-46d which are aligned
concentric with the central axis 54. The smallest diameter section
46d is journaled for rotation within the lower bearing member 44
with the next smallest section 46c providing a step 72 for axial
support of the drive shaft 46 upon the lower bearing member 44. The
largest section 46a is journaled for rotation within the upper
bearing member 42.
[0027] The drive shaft 46 further includes an offset eccentric
drive section 74 that has a cylindrical drive surface 75 about an
offset axis that is offset relative to the central axis 54. This
offset drive section 74 is journaled within a cavity of the movable
scroll member of the scroll compressor 14 to drive the movable
member of the scroll compressor about an orbital path when the
drive shaft 46 is spun about the central axis 54. To provide for
lubrication of all of these bearing surfaces, the outer housing 12
provides an oil lubricant sump 76 at the bottom end in which
suitable oil lubricant is provided. The drive shaft 46 has an oil
lubricant pipe and impeller 78 that acts as an oil pump when the
drive shaft is spun and thereby pumps oil out of the lubricant sump
76 into an internal lubricant passageway 80 defined within the
drive shaft 46. During rotation of the drive shaft 46, centrifugal
force acts to drive lubricant oil up through the lubricant
passageway 80 against the action of gravity. The lubricant
passageway 80 includes various radial passages as shown to feed oil
through centrifugal force to appropriate bearing surfaces and
thereby lubricate sliding surfaces as may be desired.
[0028] The upper bearing member 42 includes a central bearing hub
84 into which the largest section 46a of the drive shaft 46 is
journaled for rotation. Extending outward from the bearing hub 84
is a support web 86 that merges into an outer peripheral support
rim 88. Provided along the support web 86 is an annular stepped
seating surface 90 which may have an interference and press-fit
with the top end of the cylindrical motor housing 48 to thereby
provide for axial and radial location. The motor housing 48 may
also be fastened with screws to the upper bearing member 42. The
outer peripheral support rim 88 also may include an outer annular
stepped seating surface 92 which may have an interference and
press-fit with the outer housing 12. For example, the outer
peripheral rim 88 can engage the seating surface 92 axially, that
is it engages on a lateral plane perpendicular to axis 54 and not
through a diameter. To provide for centering there is provided a
diametric fit just below the surface 92 between the central housing
section 24 and the support rim 88. Specifically, between the
telescoped central and top-end housing sections 24, 26 is defined
in internal circular step 94, which is located axially and radially
with the outer annular step 92 of the upper bearing member 42.
[0029] The upper bearing member 42 also provides axial thrust
support to the movable scroll member through a bearing support via
an axial thrust surface 96. While this may be integrally provided
by a single unitary component, it is shown as being provided by a
separate collar member 98 that is interfit with the upper portion
of the upper bearing member 42 along stepped annular interface 100.
The collar member 98 defines a central opening 102 that is a size
large enough to provide for receipt of the eccentric offset drive
section 74 and allow for orbital eccentric movement thereof that is
provided within a receiving portion of the movable scroll
compressor member 112.
[0030] Turning in greater detail to the scroll compressor 14, the
scroll compressor body is provided by first and second scroll
compressor bodies which preferably include a stationary fixed
scroll compressor body 110 and a movable scroll compressor body
112. The moveable scroll compressor body 112 is arranged for
orbital movement relative to the fixed scroll compressor body 110
for the purpose of compressing refrigerant. The fixed scroll
compressor body includes a first rib 114 projecting axially from a
plate-like base 116 and is designed in the form of a spiral.
Similarly, the second movable scroll compressor body 112 includes a
second scroll rib 118 projecting axially from a plate-like base 120
and is in the design form of a similar spiral. The scroll ribs 114,
118 engage in one another and abut sealingly on the respective base
surfaces 120, 116 of the respectively other compressor body 112,
110. As a result, multiple compression chambers 122 are formed
between the scroll ribs 114, 118 and the bases 120, 116 of the
compressor bodies 112, 110. Within the chambers 122, progressive
compression of refrigerant takes place. Refrigerant flows with an
initial low pressure via an intake area 124 surrounding the scroll
ribs 114, 118 in the outer radial region (see e.g. FIGS. 2-3).
Following the progressive compression in the chambers 122 (as the
chambers progressively are defined radially inward), the
refrigerant exits via a compression outlet 126 which is defined
centrally within the base 116 of the fixed scroll compressor body
110. Refrigerant that has been compressed to a high pressure can
exit the chambers 122 via the compression outlet 126 during
operation of the scroll compressor.
[0031] The movable scroll compressor body 112 engages the eccentric
offset drive section 74 of the drive shaft 46. More specifically,
the receiving portion of the movable scroll compressor body 112
includes a cylindrical bushing drive hub 128 which slideably
receives the eccentric offset drive section 74 with a slideable
bearing surface provided therein. In detail, the eccentric offset
drive section 74 engages the cylindrical drive hub 128 in order to
move the moveable scroll compressor body 112 about an orbital path
about the central axis 54 during rotation of the drive shaft 46
about the central axis 54. Considering that this offset
relationship causes a weight imbalance relative to the central axis
54, the assembly preferably includes a counter weight 130 that is
mounted at a fixed angular orientation to the drive shaft 46. The
counter weight 130 acts to offset the weight imbalance caused by
the eccentric offset drive section 74 and the movable scroll
compressor body 112 that is driven about an orbital path (e.g.
among other things, the scroll rib is not equally balanced). The
counter weight 130 includes an attachment collar 132 and an offset
weight region 134 (see counter weight shown best in FIG. 2) that
provides for the counter weight effect and thereby balancing of the
overall weight of the rotating components about the central axis 54
in cooperation with a lower counterweight 135 for balancing
purposes. This provides for reduced vibration and noise of the
overall assembly by internally balancing or cancelling out inertial
forces.
[0032] With reference to FIGS. 1-3, and particularly FIG. 2, the
guiding movement of the scroll compressor can be seen. To guide the
orbital movement of the movable scroll compressor body 112 relative
to the fixed scroll compressor body 110, an appropriate key
coupling 140 may be provided. Keyed couplings are often referred to
in the scroll compressor art as an "Oldham Coupling." In this
embodiment, the key coupling 140 includes an outer ring body 142
and includes two first keys 144 that are linearly spaced along a
first lateral axis 146 and that slide closely and linearly within
two respective keyway tracks 148 that are linearly spaced and
aligned along the first axis 146 as well. The keyway tracks 148 are
defined by the stationary fixed scroll compressor body 110 such
that the linear movement of the key coupling 140 along the first
lateral axis 146 is a linear movement relative to the outer housing
12 and perpendicular to the central axis 54. The keys can comprise
slots, grooves or, as shown, projections which project from the
ring body 142 of the key coupling 140. This control of movement
over the first lateral axis 146 guides part of the overall orbital
path of the moveable scroll compressor body 112.
[0033] Additionally, the key coupling includes four second keys 152
in which opposed pairs of the second keys 152 are linearly aligned
substantially parallel relative to a second traverse lateral axis
154 that is perpendicular to the first lateral axis 146. There are
two sets of the second keys 152 that act cooperatively to receive
projecting sliding guide portions 156 that project from the base
120 on opposite sides of the movable scroll compressor body 112.
The guide portions 156 linearly engage and are guided for linear
movement along the second traverse lateral axis by virtue of
sliding linear guiding movement of the guide portions 156 along
sets of the second keys 152.
[0034] By virtue of the key coupling 140, the moveable scroll
compressor body 112 has movement restrained relative to the fixed
scroll compressor body 110 along the first lateral axis 146 and
second traverse lateral axis 154. This results in the prevention of
any relative rotation of the moveable scroll body as it allows only
translational motion. More particularly, the fixed scroll
compressor body 110 limits motion of the key coupling 140 to linear
movement along the first lateral axis 146; and in turn, the key
coupling 140 when moving along the first lateral axis 146 carries
the moveable scroll 112 along the first lateral axis 146 therewith.
Additionally, the movable scroll compressor body can independently
move relative to the key coupling 140 along the second traverse
lateral axis 154 by virtue of relative sliding movement afforded by
the guide portions 156 which are received and slide between the
second keys 152. By allowing for simultaneous movement in two
mutually perpendicular axes 146, 154, the eccentric motion that is
afforded by the eccentric offset drive section 74 of the drive
shaft 46 upon the cylindrical drive hub 128 of the movable scroll
compressor body 112 is translated into an orbital path movement of
the movable scroll compressor body 112 relative to the fixed scroll
compressor body 110.
[0035] Referring in greater detail to the fixed scroll compressor
body 110, this body 110 is fixed to the upper bearing member 42 by
an extension extending axially and vertically therebetween and
around the outside of the moveable scroll compressor body 112. In
the illustrated embodiment, the fixed scroll compressor body 110
includes a plurality of axially projecting legs 158 (see FIG. 2)
projecting on the same side as the scroll rib from the base 116.
These legs 158 engage and are seated against the top side of the
upper bearing member 42. Preferably, bolts 160 (FIG. 2) are
provided to fasten the fixed scroll compressor body 110 to the
upper bearing member 42. The bolts 160 extend axially through the
legs 158 of the fixed scroll compressor body and are fastened and
screwed into corresponding threaded openings in the upper bearing
member 42. For further support and fixation of the fixed scroll
compressor body 110, the outer periphery of the fixed scroll
compressor body includes a cylindrical surface 162 that is closely
received against the inner cylindrical surface of the outer housing
10 and more particularly the top end housing section 26. A
clearance gap between surface 162 and side wall 32 serves to permit
assembly of upper housing 26 over the compressor assembly and
subsequently to contain the o-ring seal 164. An O-ring seal 164
seals the region between the cylindrical locating surface 162 and
the outer housing 112 to prevent a leak path from compressed high
pressure fluid to the un-compressed section/sump region inside of
the outer housing 12. The seal 164 can be retained in a radially
outward facing annular groove 166.
[0036] With reference to FIGS. 1-3 and particularly FIG. 3, the
upper side (e.g. the side opposite the scroll rib) of the fixed
scroll 110 supports a floatable baffle member 170. To accommodate
the same, the upper side of the fixed scroll compressor body 110
includes an annular and more specifically cylindrical inner hub
region 172 and an outwardly spaced peripheral rim 174 which are
connected by radially extending disc region 176 of the base 116.
Between the hub 172 and the rim 174 is provided an annular
piston-like chamber 178 into which the baffle member 170 is
received. With this arrangement, the combination of the baffle
member 170 and the fixed scroll compressor body 110 serve to
separate a high pressure chamber 180 from lower pressure regions
within the housing 10. While the baffle member 170 is shown as
engaging and constrained radially within the outer peripheral rim
174 of the fixed scroll compressor body 110, the baffle member 170
could alternatively be cylindrically located against the inner
surface of the outer housing 12 directly.
[0037] As shown in the embodiment, and with particular reference to
FIG. 3, the baffle member 170 includes an inner hub region 184, a
disc region 186 and an outer peripheral rim region 188. To provide
strengthening, a plurality of radially extending ribs 190 extending
along the top side of the disc region 186 between the hub region
184 and the peripheral rim region 188 may be integrally provided
and are preferably equally angularly spaced relative to the central
axis 54. The baffle member 170 in addition to tending to separate
the high pressure chamber 180 from the remainder of the outer
housing 12 also serves to transfer pressure loads generated by high
pressure chamber 180 away from the inner region of the fixed scroll
compressor body 110 and toward the outer peripheral region of the
fixed scroll compressor body 110. At the outer peripheral region,
pressure loads can be transferred to and carried more directly by
the outer housing 12 and therefore avoid or at least minimize
stressing components and substantially avoid deformation or
deflection in working components such as the scroll bodies.
Preferably, the baffle member 170 is floatable relative to the
fixed scroll compressor body 110 along the inner peripheral region.
This can be accomplished, for example, as shown in the illustrated
embodiment by a sliding cylindrical interface 192 between mutually
cylindrical sliding surfaces of the fixed scroll compressor body
and the baffle member along the respective hub regions thereof. As
compressed high pressure refrigerant in the high pressure chamber
180 acts upon the baffle member 170, substantially no load may be
transferred along the inner region, other than as may be due to
frictional engagement. Instead, an axial contact interface ring 194
is provided at the radial outer periphery where the respective rim
regions are located for the fixed scroll compressor body 110 and
the baffle member 170. Preferably, an annular axial gap 196 is
provided between the innermost diameter of the baffle member 170
and the upper side of the fixed scroll compressor body 110. The
annular axial gap 196 is defined between the radially innermost
portion of the baffle member and the scroll member and is adapted
to decrease in size in response to a pressure load caused by high
pressure refrigerant compressed within the high pressure chamber
180. The gap 196 is allowed to expand to its relaxed size upon
relief of the pressure and load.
[0038] To facilitate load transfer most effectively, an annular
intermediate or lower pressure chamber 198 is defined between the
baffle member 170 and the fixed scroll compressor body 110. This
intermediate or lower pressure chamber can be subject to either the
lower sump pressure as shown, or can be subject to an intermediate
pressure (e.g. through a fluid communication passage defined
through the fixed scroll compressor body to connect one of the
individual compression chambers 122 to the chamber 198). Load
carrying characteristics can therefore be configured based on the
lower or intermediate pressure that is selected for best
stress/deflection management. In either event, the pressure
contained in the intermediate or low pressure chamber 198 during
operation is substantially less than the high pressure chamber 180
thereby causing a pressure differential and load to develop across
the baffle member 170.
[0039] To prevent leakage and to better facilitate load transfer,
inner and outer seals 204, 206 may be provided, both of which may
be resilient, elastomeric O-ring seal members. The inner seal 204
is preferably a radial seal and disposed in a radially inwardly
facing inner groove 208 defined along the inner diameter of the
baffle member 170. Similarly the outer seal 206 can be disposed in
a radially outwardly facing outer groove 210 defined along the
outer diameter of the baffle member 170 in the peripheral rim
region 188. While a radial seal is shown at the outer region,
alternatively or in addition an axial seal may be provided along
the axial contact interface ring 194.
[0040] While the baffle member 170 could be a stamped steel
component, preferably and as illustrated, the baffle member 170
comprises a cast and/or machined member (and may be aluminum) to
provide for the expanded ability to have several structural
features as discussed above. By virtue of making the baffle member
in this manner, heavy stamping of such baffles can be avoided.
[0041] Additionally, the baffle member 170 can be retained to the
fixed scroll compressor body 110. Specifically, as can be seen in
the figures, a radially inward projecting annular flange 214 of the
inner hub region 184 of the baffle member 170 is trapped axially
between the stop plate 212 and the fixed scroll compressor body
110. The stop plate 212 is mounted with bolts 216 to a fixed scroll
compressor body 210. The stop plate 212 includes an outer ledge 218
that projects radially over the inner hub 172 of the fixed scroll
compressor body 110. The stop plate ledge 218 serves as a stop and
retainer for the baffle member 170. In this manner, the stop plate
212 serves to retain the baffle member 170 to the fixed scroll
compressor body 110 such that the baffle member 170 is carried
thereby.
[0042] As shown, the stop plate 212 can be part of a check valve
220. The check valve includes a moveable valve plate element 222
contained within a chamber defined in the outlet area of the fixed
scroll compressor body within the inner hub 172. The stop plate 212
thus closes off a check valve chamber 224 in which the moveable
valve plate element 222 is located. Within the check valve chamber
there is provided a cylindrical guide wall surface 226 that guides
the movement of the check valve 220 along the central axis 54.
Recesses 228 are provided in the upper section of the guide wall
226 to allow for compressed refrigerant to pass through the check
valve when the moveable valve plate element 222 is lifted off of
the valve seat 230. Openings 232 are provided in the stop plate 212
to facilitate passage of compressed gas from the scroll compressor
into the high pressure chamber 180. The check valve is operable to
allow for one way directional flow such that when the scroll
compressor is operating, compressed refrigerant is allowed to leave
the scroll compressor bodies through the compression outlet 126 by
virtue of the valve plate element 222 being driven off of its valve
seat 230. However, once the drive unit shuts down and the scroll
compressor is no longer operating, high pressure contained within
the high pressure chamber 180 forces the movable valve plate
element 222 back upon the valve seat 230. This closes off check
valve 220 and thereby prevents backflow of compressed refrigerant
back through the scroll compressor.
[0043] During operation, the scroll compressor assembly 10 is
operable to receive low pressure refrigerant at the housing inlet
port 18 and compress the refrigerant for delivery to the high
pressure chamber 180 where it can be output through the housing
outlet port 20. As is shown, in FIG. 4, an internal conduit 234 can
be connected internally of the housing 12 to guide the lower
pressure refrigerant from the inlet port 18 into the motor housing
via a motor housing inlet 238. This allows the low pressure
refrigerant to flow across the motor and thereby cool and carry
heat away from the motor which can be caused by operation of the
motor. Low pressure refrigerant can then pass longitudinally
through the motor housing and around through void spaces therein
toward the top end where it can exit through a plurality of motor
housing outlets 240 (see FIG. 2) that are equally angularly spaced
about the central axis 54. The motor housing outlets 240 may be
defined either in the motor housing 48, the upper bearing member 42
or by a combination of the motor housing and upper bearing member
(e.g. by gaps formed therebetween as shown in FIG. 2). Upon exiting
the motor housing outlet 240, the low pressure refrigerant enters
an annular chamber 242 formed between the motor housing and the
outer housing. From there, the low pressure refrigerant can pass
through the upper bearing member through a pair of opposed outer
peripheral through ports 244 that are defined by recesses on
opposed sides of the upper bearing member 42 to create gaps between
the bearing member 42 and housing 12 as shown in FIG. 3 (or
alternatively holes in bearing member 42). The through ports 244
may be angularly spaced relative to the motor housing outlets 240.
Upon passing through the upper bearing member 42, the low pressure
refrigerant finally enters the intake area 124 of the scroll
compressor bodies 110, 112. From the intake area 124, the lower
pressure refrigerant finally enters the scroll ribs 114, 118 on
opposite sides (one intake on each side of the fixed scroll
compressor body) and is progressively compressed through chambers
122 to where it reaches it maximum compressed state at the
compression outlet 126 where it subsequently passes through the
check valve 220 and into the high pressure chamber 180. From there,
high pressure compressed refrigerant may then pass from the scroll
compressor assembly 10 through the refrigerant housing outlet port
20.
[0044] In accordance with the present invention, the illustrated
embodiment includes improvements in relation to the key coupling,
which will additionally be focused upon below.
[0045] Referring to FIGS. 5-7 and particularly FIG. 7, it can be
seen that four sliding contacts 250 are provided between the key
coupling 140 and the movable scroll compressor body 112. As shown,
each of the sliding contacts 250 is contained in its own separate
quadrant 252 (the quadrants 252 being defined by the mutually
perpendicular lateral axes 146, 154). Each sliding contact 250 can
be provided by a sliding face 254 (e.g. such as an edge) defined by
the movable scroll compressor body and another sliding face 256
defined by one of the keys 152 of the key coupling 140. As shown,
cooperating pairs 258 of sliding contacts 250 are provided on each
side of the first lateral axis 146.
[0046] Preferably, four keys 152 are provided by the key coupling
140 and project from the ring body 142 to provide for the sliding
faces 256, with the keys 152 projecting axially from the ring body
142 toward the movable scroll compressor body 112. Alternatively,
it is also contemplated and herein disclosed that the reverse may
be true in that all or some of the keys may project from the base
120 of the movable scroll compressor body 112 instead.
[0047] As illustrated, guide portions 156 of the movable scroll
compressor body base 120 are provided by laterally extending flange
portion 262 projecting in opposite directions along the second
lateral axis 154 in an outward direction away from the movable
compressor body scroll rib 118. By projecting away from the scroll
rib 118, the flange portions 262 can provide edges for the sliding
faces 254 which lie in a plane parallel with a plane defined by the
central axis 54 and the second lateral axis 154. Additionally, it
can be seen that the flange portions 262 intersect and lie
generally symmetrical upon the second lateral axis 154.
[0048] Preferably, and as illustrated in the figures, the base 120
of the movable scroll compressor body 112 is slot free and need not
define a slot due to the key coupling afforded with this design as
compared with, for example, a more conventional design as
illustrated in FIG. 10. One benefit of this approach is that space
need not be occupied by outwardly projecting ears from the scroll
base in order to interact with the Oldham key coupling. As in the
present design, there are no ear structures and as a result the
overall diameter of the package can be reduced. For example, for a
scroll compressor having at least a thirty ton capacity output, the
housing can have a diameter of less than 320 millimeters. The
reduction in size that can be realized by eliminating the ear
structures is shown in FIG. 10 by schematically illustrating the
diameter 264 with the ears and a smaller diameter 266 that can be
realized without the ears. In particular, the center shell can be
reduced in diameter to under 310 millimeters to as little as 305
millimeters while providing up to thirty-five tons of capacity or
even potentially more with a suitable motor (e.g. a forty ton
capacity may be possible). This can all be done while also
realizing a significant weight savings, including roughly between
5-10 kilograms in weight savings of the shell alone due to the
decreased diameter. This can provide significant benefits in
relation to lightening the overall weight of the scroll compressor
assembly 10 and thereby make it more attractive for several reasons
including easier manipulation, easier installation, and material
savings. In contrast, comparable thirty-two ton scroll compressor
displacement capacities have had shell sizes of greater than 330
millimeters such as 331 or 333 millimeters for example.
[0049] To carry axial thrust loads, the movable scroll compressor
body 112 also includes flange portions 268 projecting in a
direction perpendicular relative to the guiding flange portions 262
(e.g. along the first lateral axis 146). These additional flange
portions 268 are preferably contained within the diametrical
boundary created by the guide flange portions 262 so as to best
realize the size reduction benefits. Yet a further advantage of
this design is that the sliding faces 254 of the movable scroll
compressor body 112 are open and not contained within a slot. This
is advantageous during manufacture in that it affords subsequent
machining operations such as finishing milling for creating the
desirable tolerances and running clearances as may be desired.
[0050] Preferably, but optionally in relation to this application,
a non-symmetrical contact relationship is also provided between the
key coupler and at least one of the scroll compressor bodies as
illustrated in FIG. 7. In comparing the non-symmetrical arrangement
of FIG. 7 with a symmetrical arrangement of FIGS. 8 and 9, it is
demonstrated that symmetric contact placement can cause unwanted
rotation and edge loading of key surfaces indicated in FIG. 9. Each
of these figures show exaggerated placement of running clearances
270 considering running clearances are typically on the order of
between ten micron and one hundred micron from a manufacturing
design standpoint (not counting tolerances). Such running
clearances 270 are provided to allow for easy sliding movement of
the movable scroll compressor body 112 along the second lateral
axis 154 and to allow for easier assembly. For example,
manufacturing tolerances may cause the surfaces to be slightly
greater or less. Also some running clearance should be provided to
facilitate sliding movement as opposed to a press fit relationship
or otherwise a binding relationship due to frictional forces,
expansion/contraction due to temperature differentials that might
occur either temporarily or otherwise, and for other similar
reasons. Preferably and as illustrated in FIG. 7, the running
clearance 270 is not equal for each pair 258 of sliding contacts
250. In particular, sliding contacts 250a, which continuously
engage during operation, are set at about or around a zero running
clearance while all or most of the running clearance is provided by
sliding contacts 250b. Sliding contacts 250b can engage, for
example, when the scroll compressor is shut down and to prevent
relative rotation in the opposite direction and thereby keep the
scroll compressor restrained for linear translation along the
second lateral axis 154.
[0051] There are various ways to accomplish the non-symmetrical
running clearance placement including having the sliding faces 256
of the keys slightly offset and not symmetrical about the second
lateral axis and/or having the sliding faces 254 of the movable
scroll compressor body 112 slightly offset and/or not symmetrical
relative to the second lateral axis 154, or a combination of both.
As shown in the drawings such as FIG. 7, each individual pair 258
of the keys 152 are non-symmetrically placed such that one key of
the pair is placed slightly farther from the second lateral axis
154 as compared to the other key of that pair. This offset
placement of adjacent keys minimizes scroll rotation and provides
parallel surface loading of the scroll compressor body sliding
faces 254 and key coupling sliding faces 256 during normal
operation when loads are being experienced on contacts 250a during
compression of refrigerant. Again, considering that contacts 250b
are not so loaded during normal operation, providing the running
clearance primarily or in full along sliding contacts 250b even
though it may allow for slightly greater counter rotation of the
scroll compressor body upon shut down is not of as much importance
due to the fact that unwanted rotation of the scroll and edge
loading of the key surfaces is more critical while the scroll
compressor is actively operating and subject to high loads on a
continuous basis. The contrast can be seen between FIGS. 7 and 9,
in that the scroll compressor body is driven truer to the second
lateral axes as shown in FIG. 7 whereas some unwanted rotation of
the scroll and edge loading of key surfaces can occur as shown in
FIG. 9 as the movable scroll compressor body 112 of FIG. 9 linearly
translates along the second lateral axis.
[0052] The above described embodiment and the alternatives in
relation thereto (e.g. as to where the offset placement of running
clearance may be provided) hereby provide means for correcting
clearance backlash due to the provision of running clearance.
[0053] It should be appreciated that a similar provision can also
be provided in an embodiment such as shown in FIG. 10 for a more
conventional key coupling. Specifically, such a non-symmetric
relationship can similarly be used by placing the running clearance
along one of the slot walls in this design so as to similarly
correct unwanted rotation and to keep the sliding faces of the keys
in the slots more parallel during operation to prevent unwanted
edge loading.
[0054] All references, including publications, patent applications,
and patents cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0055] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) is to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0056] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. Variations of those preferred embodiments may
become apparent to those of ordinary skill in the art upon reading
the foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *