ROTOR ATTACHMENT FOR COMPRESSOR

ACCESSOIRE DE ROTOR POUR COMPRESSEUR

English Abstract

A compressor having drive assembly including a crankshaft and a motor having a
stator and a rotor. The rotor is received on a crankshaft and secured to the
crankshaft via a
counterweight. In one exemplary embodiment, the counterweight is shrink-fit or
press-fit in
position on the crankshaft and the rotor is attached to the counterweight. In
one exemplary
embodiment, the rotor may be secured to the counterweight by fasteners, such
as bolts. The
interference between the counterweight and the crankshaft is sufficiently
strong to transfer
driving loads from the rotor and through the counterweight to drive the
crankshaft. In one
exemplary embodiment, the rotor includes a central opening having a diameter
larger than the
diameter of the crankshaft. This allows for the rotor to fit closely to the
crankshaft without
touching the same. As a result, the rotor may be easily assembled as a slip-
fit on the
crankshafts and then secured to the counterweights.

Claims

WHAT IS CLAIMED IS:
1. A drive assembly in a compressor, the drive assembly comprising:
a motor having a stator and a rotor;
a crankshaft connected to a compression mechanism; and
a counterweight secured to said crankshaft, said counterweight rotatably fixed
to said rotor, wherein said rotor is rotatably secured to said crankshaft
solely by said
counterweight.
2. The drive assembly of Claim 1, wherein said counterweight is secured to
said
crankshaft by one of a shrink-fit and a press-fit.
3. The drive assembly of Claim 2 wherein said rotor is secured to said
counterweight by means of at least one fastener.
4. The drive assembly of Claim 3 wherein said fastener is a bolt.
5. The drive assembly of Claim 1 wherein said rotor is secured to said
counterweight by means of at least one fastener.
6. The drive assembly of Claim 5 wherein said rotor is secured to said
counterweight by means of at least one fastener.
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Description

CA 02640539 2008-10-07
ROTOR ATTACHMENT FOR COMPRESSOR
BACKGROUND
I. Field of the Invention.
100011 The present invention relates to compressors and, particularly, to
compressors
having a rotatable counterweight.
2. Description of the Related Art.
[00021 Compressors generally have a drive assembly including a motor having a
stator and
a rotor, in which the rotor is press-fit or shrink-fit to a crankshaft to
rotate the crankshaft and
drive a compression mechanism. Due to eccentric loading that occurs during the
rotation of
the compression mechanism, counterweights are attached to the rotor to
facilitate even weight
distribution during operation of the compressor. However, some rotors have
magnets
contained therein that may become demagnetized if they are heated to
facilitate a shrink fit.
Alternatively, the magnets andlor rotor may become damaged if the rotor is
forced on the
crankshaft to facilitate a press-fit. Additionally, when utilizing rotors
containing magnets, the
necessary manipulation of the rotor and extra assembly operations may be
difficult.
[0003] What is needed is an improvement over the foregoing.
SUMMARY OF THE INVENTION
[0004) The present invention provides a compressor having drive assembly
including a
crankshaft and a motor having a stator and a rotor. The rotor is received on a
crankshaft and
secured to the crankshaft via a counterweight. In one exemplary embodiment,
the
counterweight is shrink-fit or press-fit in position on the crankshaft and the
rotor is attached
to the counterweight. In one exemplary embodiment, the rotor may be secured to
the
counterweight by fasteners, such as bolts. The interference between the
counterweight and
the crankshaft is sufficiently strong to transfer driving loads from the rotor
and through the
counterweight to drive the crankshaft. In one exemplary embodiment, the rotor
includes a
central opening having a diameter larger than the diameter of the crankshaft.
This allows for
the rotor to fit closely to the crankshaft without touching the same. As a
result, the rotor may
be easily assembled as a slip-fit on the crankshaft and then secured to the
counterweight.
[0005] Advantageously, by limiting the need to shrink-fit or press-fit the
rotor to the
crankshaft, any potential distortion of the rotor is substantially eliminated.
For example, if
the rotor includes magnets, such as rare earth magnets, demagnetization of the
magnets in the
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CA 02640539 2008-10-07
rotor is substantially prevented. Additionally, the rotor may be purchased
magnetized,
eliminating additional manufacturing costs and decreasing the difficulty in
assembling the
rotor to the crankshaft. Further, in order to press-fit the rotor to the
crankshaft, a relief is
commonly formed in the crankshaft to allow the rotor to be press-fit over a
small distance.
By eliminating the need to press-fit the rotor to the crankshaft, the need to
machine a relief
into the crankshaft is eliminated and the corresponding manufacturing time and
cost
decreased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The above-mentioned and other features and advantages of this
invention, and the
manner of attaining them, will become more apparent and the invention itself
will be better
understood by reference to the following description of an embodiment of the
invention taken
in conjunction with the accompanying drawing, wherein:
[0007] Fig. 1 is a cross-sectional view of the drive assembly of the present
invention.
[00081 Corresponding reference characters indicate corresponding parts. The
exemplification set out herein illustrates one preferred embodiment of the
invention, in one
form, and such exemplification is not to be construed as limiting the scope of
the invention in
any manner.
DETAILED DESCRIPTION
[0009] Referring to Fig. 1, crankcase 2, bearing support 5, bearing assembly 6
and drive
assembly 8 are shown in accordance with one exemplary embodiment of the
present
invention. Drive assembly 8 includes motor 10 having stator 12 and rotor 14.
Rotor 14 is
rotationally locked to crankshaft 16 via upper counterweight 18. Counterweight
18 has
opening 20 configured for receipt of crankshaft 16. In order to secure
counterweight 18 to
crankshaft 16, counterweight 18 is shrink-fit or press-fit to crankshaft 16 or
fixedly connected
by a suitable fastener. Once counterweight 18 is sufficiently secured to
crankshaft 16, rotor
14 is connected to counterweight 18.
[0010] In one exemplary embodiment, counterweight 18 and rotor 14 have
corresponding
apertures 22, 24, respectively, configured for the receipt of fasteners, such
as bolts 26. Bolts
26 include an oversized head 28 and a threaded portion 30 configured for
receipt of nut 32
thereon. By aligning apertures 22, 24 of counterweight 18 and rotor 14, bolt
26 may be
inserted therethrough and nut 32 secured to threaded portion 30 of bolt 26. In
order to
facilitate the assembly of rotor 14 to crankshaft 16, rotor 14 may have an
oversized aperture
extending therethrough. The oversized aperture of rotor 14 allows for rotor 14
to slip-fit on
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CA 02640539 2008-10-07
crankshaft 16. In this embodiment, rotor 14 does not tightly contact
crankshaft 16, but may
allow for a small gap to be formed therebetween.
100111 Additionally, lower counterweight 34 may also be secured through
counterweight
18 to crankshaft 16. Specifically, lower counterweight 34 further includes
aperture 36
configured for the receipt of bolt 26. By aligning aperture 36 with apertures
22, 24 in
crankshaft 16 and rotor 14, bolt 26 may be inserted through apertures 22, 24,
36 and nut 32
secured to threaded portion 30 of bolt 26. Once connected via bolt 26, lower
counterweight
34 and rotor 14 are rotationally secured to crankshaft 16 via counterweight
18. Thus, during
operation of the compressor, rotor 14 of motor 10 is rotated and the rotation
of rotor 14 is
transferred via contact region 36 of counterweight 18 to crankshaft 16.
Crankshaft 16 may
then correspondingly rotate a compression mechanism, such as a scroll
compression
mechanism (not shown).
[0012) The fluid is then discharged at a relatively high discharge pressure
through
discharge port 32. The compressor may further include other features such as
those described
in U.S. Patent No. 7,094,043 to Sldnner, issued August 22, 2006, and U.S.
Patent
No. 7,063,523 to Skinner, issued June 20, 2006, the entire disclosures of
which are expressly
incorporated by reference herein.
[0013] While this invention has been described as having a preferred design,
the present
invention can be further modified within the spirit and scope of this
disclosure. This
application is therefore intended to cover any variations, uses, or
adaptations of the invention
using its general principles. Further, this application is intended to cover
such departures
from the present disclosure as come within known or customary practice in the
art to which
this invention pertains and which fall within the limits of the appended
claims.
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Representative Drawing