U.S. patent application number 16/973567 was filed with the patent office on 2021-08-12 for method and system for cooling a motor during motor startup.
The applicant listed for this patent is Carrier Corporation. Invention is credited to Frederick J. Cogswell, Ahmad M. Mahmoud, Parmesh Verma, Jinliang Wang.
Application Number | 20210247107 16/973567 |
Document ID | / |
Family ID | 1000005565582 |
Filed Date | 2021-08-12 |
United States Patent
Application |
20210247107 |
Kind Code |
A1 |
Wang; Jinliang ; et
al. |
August 12, 2021 |
METHOD AND SYSTEM FOR COOLING A MOTOR DURING MOTOR STARTUP
Abstract
A HVAC system includes a compressor having a low pressure input
and a high pressure output. The compressor is driven by a motor
having a liquid coolant flowpath configured to cool and lubricate
the motor. The motor has a coolant input and a coolant output. An
evaporator is in communication with the compressor, and includes a
coolant input and a coolant output. A condenser is in fluid
communication with the evaporator and the compressor. A first
coolant flowpath, includes a coolant drive system connecting the
output of the condenser to a valve switching device. A second
coolant flowpath connects the output of the condenser to the input
of the evaporator and to a second input of the valve switching
device. A third coolant flowpath connects the valve switching
device to the inputs of the motor. A fourth coolant flowpath
connects outputs of the motor to the input of the evaporator.
Inventors: |
Wang; Jinliang; (Palm Beach
Gardens, FL) ; Mahmoud; Ahmad M.; (Palm Beach
Gardens, FL) ; Cogswell; Frederick J.; (Palm Beach
Gardens, FL) ; Verma; Parmesh; (Palm Beach Gardens,
FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carrier Corporation |
Palm Beach Gardens |
FL |
US |
|
|
Family ID: |
1000005565582 |
Appl. No.: |
16/973567 |
Filed: |
August 30, 2019 |
PCT Filed: |
August 30, 2019 |
PCT NO: |
PCT/US2019/049019 |
371 Date: |
December 9, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62740476 |
Oct 3, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 2500/16 20130101;
F25B 2500/26 20130101; F25B 2600/23 20130101; F25B 31/002 20130101;
F25B 49/025 20130101; F25B 31/026 20130101; F25B 41/20 20210101;
F25B 49/022 20130101; F25B 1/053 20130101; F25B 31/008 20130101;
F25B 9/002 20130101 |
International
Class: |
F25B 1/053 20060101
F25B001/053; F25B 31/00 20060101 F25B031/00; F25B 31/02 20060101
F25B031/02; F25B 41/20 20060101 F25B041/20; F25B 49/02 20060101
F25B049/02; F25B 9/00 20060101 F25B009/00 |
Claims
1. A heating ventilation and air conditioning (HVAC) system
comprising: a compressor comprising a low pressure input and a high
pressure output, the compressor driven by a motor, the motor
including a liquid coolant flowpath configured to cool and
lubricate the motor and having a liquid coolant input and a liquid
coolant output; an evaporator in fluid communication with the
compressor, the evaporator including a liquid coolant input, and a
vapor coolant output, the vapor coolant output being connected to
the low pressure input of the compressor; a condenser in fluid
communication with the evaporator and the compressor, the condenser
including a vapor cooling input and a liquid coolant output, the
vapor cooling input being connected to a high pressure output of
the compressor; a first liquid coolant flowpath, including a liquid
coolant drive system connecting the liquid coolant output of the
condenser to the input of a valve switching device; a second liquid
coolant flowpath connecting the liquid coolant output of the
condenser to the liquid input of the evaporator and to a second
input of the valve switching device; a third liquid coolant
flowpath connecting an output of the valve switching device to the
liquid coolant inputs of the motor; and a fourth liquid coolant
flowpath connecting the liquid coolant outputs of the motor to the
liquid coolant input of the evaporator.
2. The HVAC system of claim 1, wherein the liquid coolant drive
system comprises an electric pump.
3. The HVAC system of claim 2, wherein the electric pump is
disposed within a reservoir integrated into the condenser.
4. The HVAC system of claim 2, wherein the electric pump is
disposed within a reservoir exterior to the condenser.
5. The HVAC system of claim 2 wherein the electric pump is disposed
outside of the condenser.
6. The HVAC system of claim 2, further comprising a controller
controllably connected to the valve switching device, the electric
pump and the motor.
7. The HVAC system of claim 6, wherein the controller is configured
to activate the electric pump at least five seconds prior to
activating the motor.
8. The HVAC system of claim 1, wherein the liquid coolant drive
system comprises a liquid coolant reservoir.
9. The HVAC system of claim 8, wherein the liquid coolant reservoir
is disposed above the motor, relative to a force of gravity, such
that a liquid coolant is gravity fed from said reservoir to said
motor when the valve switching device is in a first state.
10. The HVAC system of claim 8, wherein the liquid coolant
reservoir includes an electric heater disposed within the liquid
coolant reservoir.
11. The HVAC system of claim 10, wherein the electric heater is
controllably coupled to a controller, and the controller is
configured to activate the electric heater at least 5 minutes prior
to activating the motor.
12. The HVAC system of claim 8, further comprising a one way valve
disposed in the first liquid coolant flowpath between the liquid
coolant output of the condenser and the input to the reservoir, and
oriented such that liquid coolant flows from the condenser to the
reservoir and is prevented from flowing from the reservoir to the
condenser.
13. The HVAC system of claim 1, wherein the liquid coolant flowpath
includes a liquid phase R1233zd(E) (CHCl=CH=CF3) refrigerant.
14. The HVAC system of claim 1, wherein the second liquid coolant
flowpath includes an expansion device connecting the liquid coolant
output of the condenser to the liquid input of the evaporator.
15. The HVAC system of claim 1, wherein the first liquid coolant
flowpath includes a check valve connecting the liquid coolant
output of the condenser to the liquid coolant drive system.
16. A method for operating a heating ventilation and air
conditioning (HVAC) system comprising: driving a liquid coolant
from a condenser to a compressor motor during a startup sequence of
the compressor motor using a liquid coolant drive system, thereby
cooling and lubricating the compressor motor; and drawing liquid
coolant from the condenser to the compressor motor using a pressure
differential between the condenser and an evaporator once the
startup sequence has completed.
17. The method of claim 16, wherein driving the liquid coolant
comprises providing liquid coolant from the condenser to a
reservoir and heating the liquid coolant in the reservoir, thereby
increasing a pressure of the liquid coolant.
18. The method of claim 16, wherein driving the liquid coolant
comprises operating an electric pump disposed within the
condenser.
19. The method of claim 16, wherein driving the liquid coolant
comprises operating an electric pump disposed between an outlet of
the condenser and a liquid coolant inlet of the compressor
motor.
20. The method of claim 16, further comprising transitioning from
driving the liquid coolant using the liquid coolant driving system
to drawing liquid coolant from the condenser to the compressor
motor using a pressure differential between the condenser and the
evaporator in response to the compressor motor exceeding a
rotational speed.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to compressor motor
cooling and lubrication, and more specifically to compressor motor
cooling and lubrication during a startup sequence.
CROSS-REFERENCE TO RELATED APPLICATION
[0002] This application claims priority to U.S. Provisional Patent
Application No. 62/740,476 filed on Oct. 3, 2018.
BACKGROUND
[0003] Global warming and other environmental concerns have lead
the heating, ventilation and cooling (HVAC) industry to explore
alternative low Global Warming Potential (GWP) refrigerants in
place of existing refrigerants in HVAC systems. However, due to
their low pressure characteristics, some low GWP refrigerants,
especially those suitable for use in small capacity systems such as
rooftops and residential systems, require the utilization of a
high-efficiency compressor, evaporator and condenser.
[0004] Certain high-efficiency compressors, such as high speed
centrifugal compressors, require a high speed motor for proper
operation. High speed motors, however, require that the motor
bearings be cooled and lubricated via a cooling system in order to
keep the motor system below a limitation temperature and prevent
the bearings from overheating. Traditional air cooling of such
systems can be inadequate for a high speed motor, and independent
oil based liquid cooling leads to complex systems and increases
costs.
SUMMARY OF THE INVENTION
[0005] In one exemplary embodiment a heating ventilation and air
conditioning (HVAC) system includes a compressor comprising a low
pressure input and a high pressure output, the compressor driven by
a motor, the motor including a liquid coolant flowpath configured
to cool and lubricate the motor and having a liquid coolant input
and a liquid coolant output, an evaporator in fluid communication
with the compressor, the evaporator including a liquid coolant
input, and a vapor coolant output, the vapor coolant output being
connected to the low pressure input of the compressor, a condenser
in fluid communication with the evaporator and the compressor, the
condenser including a vapor cooling input and a liquid coolant
output, the vapor cooling input being connected to a high pressure
output of the compressor, a first liquid coolant flowpath,
including a liquid coolant drive system connecting the liquid
coolant output of the condenser to the input of a valve switching
device, a second liquid coolant flowpath connecting the liquid
coolant output of the condenser to the liquid input of the
evaporator and to a second input of the valve switching device, a
third liquid coolant flowpath connecting an output of the valve
switching device to the liquid coolant inputs of the motor, and a
fourth liquid coolant flowpath connecting the liquid coolant
outputs of the motor to the liquid coolant input of the
evaporator.
[0006] In another example of the above described heating
ventilation and air conditioning (HVAC) system the liquid coolant
drive system comprises an electric pump.
[0007] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the electric pump
is disposed within a reservoir integrated into the condenser.
[0008] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the electric pump
is disposed within a reservoir exterior to the condenser.
[0009] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the electric pump
is disposed outside of the condenser.
[0010] Another example of any of the above described heating
ventilation and air conditioning (HVAC) systems further includes a
controller controllably connected to the three way valve, the
electric pump and the motor.
[0011] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the controller is
configured to activate the electric pump at least five seconds
prior to activating the motor.
[0012] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the liquid coolant
drive system comprises a liquid coolant reservoir.
[0013] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the liquid coolant
reservoir is disposed above the motor, relative to a force of
gravity, such that a liquid coolant is gravity fed from the
reservoir to the motor when the valve switching device is in a
first state.
[0014] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the liquid coolant
reservoir includes an electric heater disposed within the liquid
coolant reservoir.
[0015] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the electric heater
is controllably coupled to a controller, and the controller is
configured to activate the electric heater at least 5 minutes prior
to activating the motor.
[0016] Another example of any of the above described heating
ventilation and air conditioning (HVAC) systems further includes a
one way valve disposed in the first liquid coolant flowpath between
the liquid coolant output of the condenser and the input to the
reservoir, and oriented such that liquid coolant flows from the
condenser to the reservoir and is prevented from flowing from the
reservoir to the condenser.
[0017] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the liquid coolant
flowpath includes a liquid phase R1233zd(E) (CHCl=CH=CF3)
refrigerant.
[0018] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the second liquid
coolant flowpath includes an expansion device connecting the liquid
coolant output of the condenser to the liquid input of the
evaporator.
[0019] In another example of any of the above described heating
ventilation and air conditioning (HVAC) systems the first liquid
coolant flowpath includes a check valve connecting the liquid
coolant output of the condenser to the liquid coolant drive
system.
[0020] An exemplary method for operating a heating ventilation and
air conditioning (HVAC) system includes driving a liquid coolant
from a condenser to a compressor motor during a startup sequence of
the compressor motor using a liquid coolant drive system, thereby
cooling and lubricating the compressor motor, and drawing liquid
coolant from the condenser to the compressor motor using a pressure
differential between the condenser and an evaporator once the
startup sequence has completed.
[0021] In another example of the above described exemplary method
for operating a heating ventilation and air conditioning (HVAC)
system driving the liquid coolant comprises providing liquid
coolant from the condenser to a reservoir and heating the liquid
coolant in the reservoir, thereby increasing a pressure of the
liquid coolant.
[0022] In another example of any of the above described exemplary
methods for operating a heating ventilation and air conditioning
(HVAC) system driving the liquid coolant comprises operating an
electric pump disposed within the condenser.
[0023] In another example of any of the above described exemplary
methods for operating a heating ventilation and air conditioning
(HVAC) system driving the liquid coolant comprises operating an
electric pump disposed between an outlet of the condenser and a
liquid coolant inlet of the compressor motor.
[0024] Another example of any of the above described exemplary
methods for operating a heating ventilation and air conditioning
(HVAC) system further includes transitioning from driving the
liquid coolant using the liquid coolant driving system to drawing
liquid coolant from the condenser to the compressor motor using a
pressure differential between the condenser and the evaporator in
response to the compressor motor exceeding a rotational speed.
[0025] 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
[0026] FIG. 1 illustrates a high level schematic view compressor
motor cooling system for a high speed motor for a heating,
ventilation and air condition (HVAC) system.
[0027] FIG. 2 schematically illustrates a variation of the
configuration of FIG. 1.
[0028] FIG. 3A schematically illustrates a second variation on the
configuration of FIG. 1.
[0029] FIG. 3B schematically illustrates a variation on the
configuration of FIG. 3A.
[0030] FIG. 4 schematically illustrates a third variation on the
configuration of FIG. 1.
DETAILED DESCRIPTION
[0031] FIG. 1 schematically illustrates a vapor compression system
with a compressor motor cooling subsystem 10 for a compressor 20
driven by a high speed motor 22 for HVAC applications. In one
non-limiting example, the high speed motor 20 is a motor for a
mini-centrifugal compressor. The system includes a condenser 30, an
evaporator 40, and an expansion device 11 in fluid communication
with the compressor 20. In order to provide cooling and lubrication
to a high speed motor 22, a pressure rise generated by the
compressor 20 provides liquid coolant from the condenser 30 to the
motor 22 along a fluid flowpath 50 during full speed operations of
the compressor 20. In the embodiment of FIG. 1, the liquid coolant
cools and lubricates the motor 22, and is then provided to the
evaporator 40 via the flowpath 58. Once in the evaporator 40, the
coolant is evaporated, and provided to the compressor 20 in a vapor
form along a vapor flowpath 60. The vapor flowpath 60 provides the
evaporated coolant from the compressor to the condenser 30.
[0032] Once the compressor 20 has begun operating at a designed
speed, the pressure buildup due to the operation of the compressor
20 is sufficient to drive the liquid coolant through the motor 20
and provide the cooling and lubricating effects. However, during
initial startup there can be insufficient pressure to drive the
liquid coolant, and a liquid coolant driving system 70 provides
supplemental pressure to drive the liquid coolant through the motor
20. The liquid coolant driving system 70 can include multiple
variations configured to generate the requisite compressor rise.
FIGS. 2-4 describe exemplary embodiments of the liquid coolant
driving system.
[0033] With regards to the liquid coolant flowpath 50, the flowpath
50 includes a first leg 52 that provides coolant from the condenser
30 to an input of a three-way valve 80. The first leg 52 includes
the liquid coolant driving system 70. In alternative systems, the
three-way valve 80 can be replaced with any other type of valve or
regulator capable of regulating flow or flow switching between two
input flow sources. Also included in the liquid coolant flowpath 50
is a second leg 54 that connects the condenser 30 directly to the
three-way valve 80, or other flow switching device, to an expansion
device 11, and to a liquid coolant input of the evaporator 40. As
used herein a "valve switching device" generically refers to any
flow switching device capable of switching a connection of an
output between at least two inputs. A third leg 56 connects an
output of the three-way valve 80 to a liquid coolant input of the
motor 22, and a fourth leg 58 connects an output of the motor 22 to
the output of the expansion device 11 in the second leg 54. After
merging the coolant flows into the evaporator 40.
[0034] When the system 10 is initially switched on, the three-way
valve 80 is set to receive liquid coolant from the condenser 30 via
the liquid coolant driving system 70. The liquid coolant driving
system 70 drives liquid coolant from the condenser 30 (via the
first leg 52) to the motor 22, through the three way valve 80 and
the expansion device 11, as the motor 22 begins operating thereby
lubricating and cooling the motor 22.
[0035] Once the motor 22 is up to speed, and is generating
sufficient liquid coolant feeding power due to the pressure buildup
within the condenser 30, the three way valve 80 switches to
receiving the liquid coolant from the second leg 54, and the liquid
coolant driving system 70 is switched off. In this way, coolant is
actively provided to the motor 22 directly from the condenser 30
through the second leg 54, the three way valve 80 and the third leg
56. Once provided to the evaporator 40, the liquid coolant
evaporates and absorbs heat from another fluid that flows through
the evaporator 40.
[0036] Operations of the motor 22, the three-way valve 80 and the
liquid coolant driving system 70 are controlled via a controller
90. The controller 90 can be a dedicated cooling system controller,
a motor controller, or any other controller capable of storing and
implementing the control sequences described herein.
[0037] The liquid coolant can be any suitable low global warming
potential refrigerant. In one example, the liquid coolant is the
refrigerant R1233zd(E) (CHCl=CH=CF3) which has a very low direct
global warming potential, a high cycle efficiency, is non-toxic and
is non-flammable.
[0038] With continued reference to FIG. 1, FIG. 2 schematically
illustrates an HVAC system 100, according to the example of FIG. 1,
with the inclusion of a heat driven liquid coolant driving system
170. The heat driven liquid coolant driving system 170 is connected
to an outlet of the condenser 130 via a check valve 172 positioned
in a first leg 152 of a liquid coolant flowpath 150. The heat
driven liquid coolant driving system 170 includes a reservoir 174,
where liquid coolant is pooled. As used herein, the reservoir 174
refers to any component capable of storing liquid refrigerant, and
can include oversized lines, a fluid tank, a portion of the
condenser, etc.
[0039] In the embodiment of FIG. 2, an electric heater 176 (i.e. a
device that generates heat using electricity) is disposed within
the reservoir 174, or connected to the reservoir 174 such that the
electric heater 176 raises the temperature of the liquid coolant
within the reservoir 174 when activated. Alternative heat sources
beyond those using electricity to generate heat can be utilized to
the same effect with minor modifications to the described system.
Raising the temperature in the reservoir 174 increases the pressure
in the reservoir 174, and the increased pressure drives liquid
coolant along the second leg 152 of the liquid coolant flowpath
when a three way valve 180 connects the first leg 152 of the liquid
coolant flow from the reservoir 174 to the third leg 156 of the
liquid coolant flowpath.
[0040] In order to ensure sufficient pressure is built up within
the reservoir 174, the electric heater 176 is activated prior to
the activation of the motor 122. In some examples, this can include
activation as many as 5 or 10 minutes prior to motor 122 activation
and is governed by controller 90. The specific length of time by
which the activation of the electric heater 176 must precede the
activation of the motor 122 is determined by multiple factors
including, but not limited to, the volume of coolant, the type of
refrigerant, etc. Alternatively, activation of the motor is
controlled by the pressure difference between the reservoir 174 and
the evaporator 140.
[0041] With continued reference to FIGS. 1 and 2, FIGS. 3A and 3B
illustrate an HVAC system 200 utilizing an electric pump 272 as the
liquid coolant driver. In alternative examples, other means to
drive the liquid coolant (e.g. electrohydrodynamics, etc.) are can
be utilized to pump the liquid coolant without requiring an
electrically driven pump 272. The HVAC system 200 is substantially
identical to the systems described with regards to FIGS. 1 and 2,
with the exception of the electric pump 272 being utilized to drive
the liquid coolant in place of the heat driven liquid coolant
driving system 170 of FIG. 2. The electric pump 272 can be included
inside the base of the condenser 230, as shown in the example of
FIG. 3A, or can be outside of the condenser 230 within the first
liquid coolant flowpath 252. In both cases, the electric pump 272
receives electrical power via a connection to an external power
source, such as a building electrical grid, or from an electrical
connection to the HVAC system, and is activated by the controller
configured to control the motor 220. The electric pump 272 can be
any conventional electric pump having sufficient size and power to
drive the liquid coolant.
[0042] Unlike the heat driven liquid coolant driving system 170 of
FIG. 2, the pump driven system of FIG. 3A or 3B requires a minimal
amount of lead up time after being activated and before the motor
22 can begin startup operations. By way of example, the lead-up
time can be less than ten seconds. In some such examples, the
lead-up time can be five seconds.
[0043] With continued reference to FIGS. 1-3B, FIG. 4 illustrates
an HVAC system 300 having third variation on the liquid coolant
driving system 70 of FIG. 1. The liquid coolant driving system of
FIG. 4 utilizes a gravity fed reservoir 374 positioned physically
above the motor, relative to a force of gravity, the reservoir is
filled with liquid coolant from the condenser 330. The reservoir
374 is connected to an outlet of the condenser 330 via a check
valve 372 positioned in a first leg 352 of a liquid coolant loop
350. When the three way valve 380 is switched to connecting the
reservoir outlet to the motor 322, gravity causes the liquid
coolant to pass through the motor 322, and allows the motor 322 to
begin startup sequences. Due to the continuous application of
gravitational forces, no lead-up time beyond the connection of the
three-way valve 380 is required before the system of FIG. 4 is able
to begin rotating.
[0044] In some examples, the gravity fed coolant system of FIG. 4
carries with it additional packaging restrictions, and the physical
structure of the motor 322 is constructed to support the weight of
the liquid coolant reservoir.
[0045] With reference now to all of FIGS. 1-4, after the initial
startup the motor is cooled and lubricated by the liquid coolant
provided directly from the condenser by switching the three-way
valve to bypass the liquid coolant drive system. The liquid coolant
flow is adjusted in order to maintain high performance evaporating
cooling in the motor and low quality two phase refrigerant leaving
from the motor.
[0046] It is further understood that any of the above described
concepts can be used alone or in combination with any or all of the
other above described concepts. Although 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.
* * * * *