U.S. patent application number 12/183149 was filed with the patent office on 2010-02-04 for line fed permanent magnet synchronous type motor for scroll compressor with bypass ports.
Invention is credited to Gregory W. Hahn.
Application Number | 20100028182 12/183149 |
Document ID | / |
Family ID | 41301344 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100028182 |
Kind Code |
A1 |
Hahn; Gregory W. |
February 4, 2010 |
LINE FED PERMANENT MAGNET SYNCHRONOUS TYPE MOTOR FOR SCROLL
COMPRESSOR WITH BYPASS PORTS
Abstract
A scroll compressor is provided with some capacity reduction
technique such as a bypass port. The electric motor for driving the
scroll compressor is not an induction motor, but rather a line fed
permanent magnet synchronous motor is utilized. Such motors have a
higher overall efficiency, and thus will be more efficient at
reduced capacity operation.
Inventors: |
Hahn; Gregory W.;
(Arkadelphia, AR) |
Correspondence
Address: |
Theodore W. Olds
Suite 350, 400 West Maple Road
Birmingham
MI
48009
US
|
Family ID: |
41301344 |
Appl. No.: |
12/183149 |
Filed: |
July 31, 2008 |
Current U.S.
Class: |
418/55.1 |
Current CPC
Class: |
F04C 18/0215 20130101;
F04C 27/005 20130101; F04C 28/26 20130101; F04C 29/0085
20130101 |
Class at
Publication: |
418/55.1 |
International
Class: |
F01C 1/02 20060101
F01C001/02 |
Claims
1. A scroll compressor comprising: a first scroll member having a
base and a generally spiral wrap extending from said base; a second
scroll member having a base and a generally spiral wrap extending
from its base, said generally spiral wraps interfitting to define
compression chambers; and an electric motor operable to drive a
rotary shaft to in turn cause said second scroll member to orbit
relative to said first scroll member, said electric motor being a
permanent magnet synchronous motor, wherein said permanent magnet
synchronous motor is a line fed motor, running directly from the
mains without requirement of frequency inverter.
2. Scroll compressor as set forth in claim 1, wherein a capacity
reduction feature being incorporated into the scroll compressor to
allow the reduction of capacity provided by the scroll compressor
under certain conditions.
3. The scroll compressor as set forth in claim 1, wherein bypass
ports are provided to reduce the capacity of the scroll
compressor.
4. The scroll compressor as set forth in claim 1, wherein said
second scroll member and said first scroll member are held
together, but are movable away from each other in an axial
direction.
5. The scroll compressor as set forth in claim 1, wherein the wraps
of said first and second scroll member are held together but are
capable of moving radially away from each other.
Description
BACKGROUND OF THE INVENTION
[0001] This application relates to a scroll compressor having a
line fed permanent magnet synchronous type motor, which has a
relatively constant power curve as a load changes, and wherein the
scroll compressor is provided with a function to reduce
capacity.
[0002] Scroll compressors are becoming widely utilized in
refrigerant compression applications. In a scroll compressor, a
pair of scroll elements each have a base and a generally spiral
wrap extending from the base. The wraps interfit to define
compression chambers. An electric motor drives a shaft, and the
shaft drives one of the two scroll members to rotate relative to
the other through a non-rotation coupling.
[0003] There are many enhancements to the basic scroll compressor
design. In one enhancement, partially or fully compressed
refrigerant may be tapped back to a suction pressure to reduce the
load on the compressor motor when there is a reduced capacity
needed for a refrigerant system associated with the compressor.
This is known as bypass or unloaded operation.
[0004] Other ways of reducing the capacity of the compressor, such
as pulse width modulation to a back pressure chamber are also
known. With all of these functions, the torque on the compressor
motor is reduced.
[0005] In all known scroll compressor designs, an induction motor
has been utilized. An induction motor has a peak efficiency at a
certain load torque, above as well as below which the efficiency
decreases. The value of reducing the capacity, which is to save
energy, is somewhat lost due to the reduced efficiency.
SUMMARY OF THE INVENTION
[0006] In the disclosed embodiment of this invention, a scroll
compressor having some way of reducing capacity is provided with a
line fed permanent magnet synchronous type motor. The permanent
magnet motor has a higher peak efficiency, and a flatter efficiency
versus torque curve compared to the prior art induction motor.
[0007] These and other features of the present invention can be
best understood from the following specification and drawings, the
following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a scroll compressor incorporating the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0009] A scroll compressor 20 is illustrated in FIG. 1. As shown, a
motor stator 22 causes a motor rotor 23 to rotate. When rotor 23
rotates, a shaft 24 is driven to rotate. Shaft 24 causes an
orbiting scroll 26 to orbit relative to a non-orbiting scroll 28,
as known. The components as described at this point are housed
within a shell 30. A suction port 32 receives a suction refrigerant
from a refrigerant cycle, and delivers that refrigerant to
compression chambers between the orbiting scroll 26 and
non-orbiting scroll 28. A discharge tube 34 delivers a compressed
refrigerant downstream into the refrigerant cycle.
[0010] Bypass ports 36 communicate with the compression chambers,
and may return a partially or fully compressed refrigerant to the
suction pressure, such as suction tube 32. As shown, a bypass line
38 incorporates a valve 40 to selectively communicate this
refrigerant back to the suction port. However, any other way of
communicating partially or fully compressed refrigerant back to the
suction pressure may be utilized with this invention. Moreover,
other ways of modulating the capacity of the compressor would come
within the scope of this invention. As an example, scroll
compressors are known wherein a biasing force is provided behind
one of the two scroll compressors. Pulse width modulation
techniques may be utilized to lower that biasing force under
certain conditions such that the scroll members can come away from
each other and reduce the capacity.
[0011] As shown in FIG. 1, the scroll compressor includes a tap 100
extending through the orbiting scroll member 26 into a back
pressure chamber 102. As known, this creates a biasing force
holding the orbiting scroll member 26 in contact with the
non-orbiting scroll member 28. In addition, the drive between the
shaft 24 and the scroll compressor 26 is through a slider block
arrangement 110. Such arrangements allow for radial movement of the
orbiting scroll 26. Both the axial compliance and the radial
compliance allow the reduction of capacity by allowing the wraps of
the scroll members to move out of contact with each other.
Techniques for providing this reduction in capacity are known. It
is the use of a particular motor with such an ability to reduce
capacity which is inventive here.
[0012] Any other capacity modulation technique would come within
the scope of this invention.
[0013] This invention relates to the use of a permanent magnet
synchronous motor for any scroll compressor having the ability to
reduce its capacity. Such motors have a high peak efficiency, and a
flatter efficiency versus torque curve. Thus, when the capacity is
reduced, the motor 22/23 will still operate more efficiently than
the prior art which utilize an induction motor.
[0014] While an embodiment of this invention has been disclosed, a
worker of ordinary skill in this art would recognize that certain
modifications would come within the scope of this invention. For
that reason, the following claims should be studied to determine
the true scope and content of this invention.
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