U.S. patent application number 12/764042 was filed with the patent office on 2010-12-30 for compressor inlet guide vane control.
This patent application is currently assigned to ACCESSIBLE TECHNOLOGIES, INC.. Invention is credited to Michael A. Carlson, Matthew Scott Dunn.
Application Number | 20100329898 12/764042 |
Document ID | / |
Family ID | 43380970 |
Filed Date | 2010-12-30 |
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United States Patent
Application |
20100329898 |
Kind Code |
A1 |
Dunn; Matthew Scott ; et
al. |
December 30, 2010 |
COMPRESSOR INLET GUIDE VANE CONTROL
Abstract
A compressor airflow control assembly is operable to control
airflow through a centrifugal compressor. The control assembly
includes an air valve mounted in the airflow path to control
airflow through the compressor. The control assembly also includes
a controller operable to sense an airflow condition and control
shifting of the air valve.
Inventors: |
Dunn; Matthew Scott;
(Lawrence, KS) ; Carlson; Michael A.; (Overland
Park, KS) |
Correspondence
Address: |
Hovey Williams LLP
10801 Mastin Blvd., Suite 1000
Overland Park
KS
66210
US
|
Assignee: |
ACCESSIBLE TECHNOLOGIES,
INC.
Lenexa
KS
|
Family ID: |
43380970 |
Appl. No.: |
12/764042 |
Filed: |
April 20, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61220635 |
Jun 26, 2009 |
|
|
|
Current U.S.
Class: |
417/300 ;
415/151 |
Current CPC
Class: |
F04D 27/0253 20130101;
F05D 2250/51 20130101; F04D 29/462 20130101; F04D 29/563 20130101;
F04B 49/22 20130101; F04D 27/0246 20130101 |
Class at
Publication: |
417/300 ;
415/151 |
International
Class: |
F04B 49/00 20060101
F04B049/00; F04D 29/56 20060101 F04D029/56 |
Claims
1. A compressor airflow control assembly operable to control
airflow through a centrifugal compressor, said control assembly
comprising: an air valve assembly including a body that presents a
valve passage, said air valve assembly further including an air
valve shiftably mounted in the valve passage to control airflow
through the passage, said air valve assembly operable to be mounted
relative to the compressor so that the valve passage fluidly
communicates with the compressor and shifting of the valve controls
the compressor airflow; and a controller operable to sense an
airflow condition and responsively control shifting of the air
valve, said controller including a fluidly driven actuator and a
shiftable fluid valve fluidly connected to the actuator to control
pressurized fluid flow from a source to the actuator, said actuator
operably coupled to the air valve so that driven movement of the
actuator effects shifting of the air valve within the valve
passage, said fluid valve being shiftable in response to the sensed
airflow condition so as to vary fluid flow to the actuator causing
movement thereof and thereby shifting of the air valve.
2. The compressor airflow control assembly as claimed in claim 1,
said controller including a shiftable airflow sensor configured to
sense the airflow condition, with shifting of the sensor
corresponding with shifting of the air valve.
3. The compressor airflow control assembly as claimed in claim 2,
said airflow sensor comprising a velocity sensor assembly mounted
within the passage.
4. The compressor airflow control assembly as claimed in claim 3,
said velocity sensor assembly including a movable sensor arm
exposed to the airflow and movable in response to airflow velocity,
with the sensor arm being fixed relative to the fluid valve to move
therewith.
5. The compressor airflow control assembly as claimed in claim 4,
said velocity sensor assembly including a spring yieldably urging
the arm and fluid valve into a predetermined valve position
associated with a corresponding airflow velocity.
6. The compressor airflow control assembly as claimed in claim 5,
said velocity sensor assembly including a spring adjuster shiftably
mounted relative to the fluid valve, said spring adjuster attached
to the spring to adjust a spring length of the spring and thereby
vary the predetermined valve position.
7. The compressor airflow control assembly as claimed in claim 2,
said controller further including a shiftable pressure-biasing
element operable to sense pressure of airflow discharged from the
compressor, said shiftable pressure-biasing element being operably
coupled to the shiftable airflow sensor so that shifting of the
airflow sensor is responsive to the sensed airflow condition and
compressor discharge pressure.
8. The compressor airflow control assembly as claimed in claim 1,
said controller including a housing, said driven actuator including
a reciprocal piston slidably mounted in the housing and drivingly
attached to the air valve, with sliding movement of the piston
causing shifting of the air valve.
9. The compressor airflow control assembly as claimed in claim 8,
said air valve comprising an inlet guide vane assembly including a
plurality of adjustable inlet guide vanes and a vane transmission
drivingly interconnecting the vanes, said piston being drivingly
attached to the transmission so that piston movement adjusts the
position of the inlet guide vanes.
10. The compressor airflow control assembly as claimed in claim 9;
and a stop located between the housing and the piston, with the
stop being operable to limit sliding piston travel and thereby
limit adjustment of the inlet guide vanes in at least one
adjustment direction.
11. The compressor airflow control assembly as claimed in claim 9,
said piston comprising a double-acting piston, with the housing and
piston cooperatively defining opposite chambers that receive
pressurized fluid.
12. The compressor airflow control assembly as claimed in claim 8,
said fluid valve being shiftably mounted in the housing, said
housing and piston cooperatively defining a chamber that receives
pressurized fluid, said housing presenting fluid supply and return
ports operable to fluidly communicate with the source, said fluid
valve being shiftable between a closed position where the fluid
valve restricts fluid flow between the chamber and ports and a
first open position where the fluid valve permits pressurized fluid
to flow from the supply port to the chamber, said fluid valve being
shiftable between the closed position and a second open position
where the fluid valve permits pressurized fluid to flow from the
chamber to the return port.
13. The compressor airflow control assembly as claimed in claim 12,
said piston comprising a double-acting piston, with the housing and
piston cooperatively defining a second chamber that receives
pressurized fluid, said fluid valve being shiftable between the
closed position where the fluid valve restricts fluid flow between
the second chamber and ports and the second open position where the
fluid valve permits pressurized fluid to flow from the supply port
to the second chamber, said fluid valve being shiftable between the
closed position and the first open position where the fluid valve
permits pressurized fluid to flow from the second chamber to the
return port.
14. The compressor airflow control assembly as claimed in claim 13,
said controller including a bypass valve fluidly connectable to a
discharge of the compressor and operable to vent airflow from the
compressor to ambient when the bypass valve is open, said
controller including a pressure relief valve that fluidly
communicates with one of the chambers and the bypass valve, said
pressure relief valve allowing pressurized fluid to flow from the
one chamber to the bypass valve and thereby open the bypass valve
when the fluid in the one chamber exceeds a predetermined
pressure.
15. The compressor airflow control assembly as claimed in claim 1,
said air valve assembly comprising an inlet guide vane assembly
including a plurality of adjustable inlet guide vanes and a vane
transmission drivingly interconnecting the vanes.
16. A compressor assembly operable to provide substantially uniform
compressor airflow velocity along a path, said compressor assembly
comprising: a centrifugal compressor fluidly connectable to the
path; an air valve assembly operable to control airflow through the
centrifugal compressor, said air valve assembly including an air
valve shiftably positionable within the path to control airflow
through the compressor; a controller operably coupled to the air
valve to responsively control shifting of the air valve, said
controller including a shiftable airflow sensor component that
moves in response to a compressor airflow condition; and an
amplification mechanism including a power source to selectively
provide power to the air valve and thereby effect shifting thereof,
said mechanism being mechanically linked to the sensor component so
that movement of the sensor component directly causes power to be
provided to the air valve.
17. The compressor assembly as claimed in claim 16, said
amplification mechanism including a hydraulic system drivingly
connected to the sensor component and air valve.
18. The compressor assembly as claimed in claim 17, said controller
including a fluidly driven actuator and a shiftable fluid valve
fluidly connected to the actuator to control pressurized fluid flow
from the hydraulic system to the actuator, said actuator operably
coupled to the air valve so that driven movement of the actuator
effects shifting of the air valve within the valve passage, said
fluid valve being shiftable in response to the sensed airflow
condition so as to vary fluid flow to the actuator causing movement
thereof and thereby shifting of the air valve.
19. The compressor assembly as claimed in claim 17, said power
source comprising a powered hydraulic pump.
20. The compressor assembly as claimed in claim 17, said compressor
presenting an air inlet, with the air valve assembly being located
adjacent the air inlet.
21. The compressor assembly as claimed in claim 20, said air valve
assembly comprising an inlet guide vane assembly including a
plurality of adjustable inlet guide vanes and a vane transmission
drivingly interconnecting the vanes.
22. The compressor assembly as claimed in claim 16, said controller
further including a shiftable pressure-biasing element that senses
pressure of airflow discharged from the compressor, said shiftable
pressure-biasing element being operably coupled to the shiftable
airflow sensor so that shifting of the airflow sensor is responsive
to the sensed airflow condition and compressor discharge
pressure.
23. A compressor assembly operable to provide substantially uniform
compressor airflow velocity along a path, said compressor assembly
comprising: a centrifugal compressor fluidly connectable to the
path; an air valve assembly in fluid communication with and
operable to control airflow through the centrifugal compressor,
said air valve assembly including a body that presents a valve
passage, said air valve assembly further including an air valve
shiftably mounted in the valve passage to control airflow through
the passage, said air valve assembly mounted relative to the
compressor so that the valve passage fluidly communicates with the
compressor and shifting of the valve controls the compressor
airflow; and a controller operable to sense an airflow condition
and responsively control shifting of the air valve, said controller
including a fluidly driven actuator and a shiftable fluid valve
fluidly connected to the actuator to control pressurized fluid flow
from a source to the actuator, said actuator operably coupled to
the air valve so that driven movement of the actuator effects
shifting of the air valve within the valve passage and thereby
controls compressor airflow velocity, said fluid valve being
shiftable in response to the sensed airflow condition so as to vary
fluid flow to the actuator causing movement thereof and thereby
shifting of the air valve.
24. The compressor assembly as claimed in claim 23, said controller
including a shiftable airflow sensor configured to sense the
airflow condition, with shifting of the sensor corresponding with
shifting of the air valve.
25. The compressor assembly as claimed in claim 24, said airflow
sensor comprising a velocity sensor assembly mounted within the
passage.
26. The compressor assembly as claimed in claim 25, said velocity
sensor assembly including a movable sensor arm exposed to the
airflow and movable in response to airflow velocity, with the
sensor arm being fixed relative to the fluid valve to move
therewith.
27. The compressor assembly as claimed in claim 26, said velocity
sensor assembly including a spring yieldably urging the arm and
fluid valve into a predetermined valve position associated with a
corresponding airflow velocity.
28. The compressor assembly as claimed in claim 27, said velocity
sensor assembly including a spring adjuster shiftably mounted
relative to the fluid valve, said spring adjuster attached to the
spring to adjust a spring length of the spring.
29. The compressor assembly as claimed in claim 24, said controller
further including a shiftable pressure-biasing element that senses
pressure of airflow discharged from the compressor, said shiftable
pressure-biasing element being operably coupled to the shiftable
airflow sensor so that shifting of the airflow sensor is responsive
to the sensed airflow condition and compressor discharge
pressure.
30. The compressor assembly as claimed in claim 23, said controller
including a housing, said driven actuator including a reciprocal
piston slidably mounted in the housing and drivingly attached to
the air valve, with sliding movement of the piston causing shifting
of the air valve.
31. The compressor assembly as claimed in claim 30, said
centrifugal compressor including an impeller, said air valve
comprising an inlet guide vane assembly including a plurality of
adjustable inlet guide vanes and a vane transmission drivingly
interconnecting the vanes, said plurality of adjustable inlet guide
vanes being located upstream of the impeller, said piston being
drivingly attached to the transmission so that piston movement
adjusts the position of the inlet guide vanes and thereby controls
airflow into the impeller.
32. The compressor assembly as claimed in claim 31; and a stop
located between the housing and the piston, with the stop being
operable to limit sliding piston travel and thereby limit
adjustment of the inlet guide vanes in at least one adjustment
direction.
33. The compressor assembly as claimed in claim 31, said piston
comprising a double-acting piston, with the housing and piston
cooperatively defining opposite chambers that receive pressurized
fluid.
34. The compressor assembly as claimed in claim 31, said fluid
valve being shiftably mounted in the housing, said housing and
piston cooperatively defining a chamber that receives pressurized
fluid, said housing presenting fluid supply and return ports
operable to fluidly communicate with the source, said fluid valve
being shiftable between a closed position where the fluid valve
restricts fluid flow between the chamber and ports and a first open
position where the fluid valve permits pressurized fluid to flow
from the supply port to the chamber, said fluid valve being
shiftable between the closed position and a second open position
where the fluid valve permits pressurized fluid to flow from the
chamber to the return port.
35. The compressor assembly as claimed in claim 34, said piston
comprising a double-acting piston, with the housing and piston
cooperatively defining a second chamber that receives pressurized
fluid, said fluid valve being shiftable between the closed position
where the fluid valve restricts fluid flow between the second
chamber and ports and the second open position where the fluid
valve permits pressurized fluid to flow from the supply port to the
second chamber, said fluid valve being shiftable between the closed
position and the first open position where the fluid valve permits
pressurized fluid to flow from the second chamber to the return
port.
36. The compressor assembly as claimed in claim 35, said controller
including a bypass valve fluidly connected to a discharge of the
compressor and operable to vent airflow from the compressor to
ambient when the bypass valve is open, said controller including a
pressure relief valve that fluidly communicates with one of the
chambers and the bypass valve, said pressure relief valve allowing
pressurized fluid to flow from the one chamber to the bypass valve
and thereby open the bypass valve when the fluid in the one chamber
exceeds a predetermined pressure.
37. The compressor assembly as claimed in claim 23, said
centrifugal compressor including an impeller, said air valve
comprising an inlet guide vane assembly including a plurality of
adjustable inlet guide vanes and a vane transmission drivingly
interconnecting the vanes, said plurality of adjustable inlet guide
vanes being located upstream of the impeller to control airflow
into the impeller.
Description
RELATED APPLICATION
[0001] This application claims the priority benefit of U.S.
Provisional Application Ser. No. 61/220,635, filed Jun. 26, 2009,
entitled COMPRESSOR DRIVE AND PNEUMATIC CONVEYING COMPRESSOR, which
is hereby incorporated in its entirety by reference herein.
BACKGROUND
[0002] 1. Field
[0003] The present invention relates generally to compressor
systems, such as those used in pneumatic conveying systems. More
specifically, embodiments of the present invention concern a
compressor package with a centrifugal compressor and a controller
that controls the airflow through the compressor.
[0004] 2. Discussion of Prior Art
[0005] Centrifugal compressors with guide vanes are known in the
art. For example, compressor systems have been developed with inlet
guide vanes and/or diffuser guide vanes. Furthermore, it is also
known for a centrifugal compressor to have adjustable guide vanes
so as to permit control over airflow to and/or from the
compressor.
[0006] Prior art compressor systems suffer from various
limitations. For instance, conventional centrifugal compressors are
unable to provide compressed airflow at a substantially constant
velocity, particularly when the compressor is exposed to widely
varying backpressures or other widely varying environmental
conditions. Furthermore, conventional guide vane controls have
complicated and expensive designs and often require electronic
connections and/or interfaces to properly function in the overall
system.
SUMMARY
[0007] The following brief summary is provided to indicate the
nature of the subject matter disclosed herein. While certain
aspects of the present invention are described below, the summary
is not intended to limit the scope of the present invention.
[0008] Embodiments of the present invention provide a compressor
assembly that does not suffer from the problems and limitations of
the prior art compressor systems, such as those set forth
above.
[0009] A first aspect of the present invention concerns a
compressor airflow control assembly operable to control airflow
through a centrifugal compressor. The control assembly broadly
includes an air valve assembly and a controller. The air valve
assembly includes a body that presents a valve passage. The air
valve assembly further includes an air valve shiftably mounted in
the valve passage to control airflow through the passage. The air
valve assembly is operable to be mounted relative to the compressor
so that the valve passage fluidly communicates with the compressor
and shifting of the valve controls the compressor airflow. The
controller is operable to sense an airflow condition and
responsively control shifting of the air valve. The controller
includes a fluidly driven actuator and a shiftable fluid valve
fluidly connected to the actuator to control pressurized fluid flow
from a source to the actuator. The actuator is operably coupled to
the air valve so that driven movement of the actuator effects
shifting of the air valve within the valve passage. The fluid valve
is shiftable in response to the sensed airflow condition so as to
vary fluid flow to the actuator, causing movement of the actuator
and thereby shifting of the air valve.
[0010] A second aspect of the present invention concerns a
compressor assembly operable to provide substantially uniform
compressor airflow velocity along a path. The compressor assembly
broadly includes a centrifugal compressor, an air valve assembly, a
controller, and an amplification mechanism. The centrifugal
compressor is fluidly connectable to the path. The air valve
assembly is operable to control airflow through the centrifugal
compressor. The air valve assembly includes an air valve shiftably
positionable within the path to control airflow through the
compressor. The controller is operably coupled to the air valve to
responsively control shifting of the air valve. The controller
includes a shiftable airflow sensor component that moves in
response to a compressor airflow condition. The amplification
mechanism includes a power source to selectively provide power to
the air valve and thereby effect shifting thereof. The mechanism is
mechanically linked to the sensor component so that movement of the
sensor component directly causes power to be provided to the air
valve.
[0011] A third aspect of the present invention concerns a
compressor assembly operable to provide substantially uniform
compressor airflow velocity along a path. The compressor assembly
broadly includes a centrifugal compressor, an air valve assembly,
and a controller. The centrifugal compressor is fluidly connectable
to the path. The air valve assembly is in fluid communication with
and is operable to control airflow through the centrifugal
compressor. The air valve assembly includes a body that presents a
valve passage. The air valve assembly further includes an air valve
shiftably mounted in the valve passage to control airflow through
the passage. The air valve assembly is mounted relative to the
compressor so that the valve passage fluidly communicates with the
compressor and shifting of the valve controls the compressor
airflow. The controller is operable to sense an airflow condition
and responsively control shifting of the air valve. The controller
includes a fluidly driven actuator and a shiftable fluid valve
fluidly connected to the actuator to control pressurized fluid flow
from a source to the actuator. The actuator is operably coupled to
the air valve so that driven movement of the actuator effects
shifting of the air valve within the valve passage and thereby
controls compressor airflow velocity. The fluid valve is shiftable
in response to the sensed airflow condition so as to vary fluid
flow to the actuator causing movement thereof and thereby shifting
of the air valve.
[0012] Other aspects and advantages of the present invention will
be apparent from the following detailed description of the
preferred embodiments and the accompanying drawing figures.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0013] Preferred embodiments of the invention are described in
detail below with reference to the attached drawing figures,
wherein:
[0014] FIG. 1 is a fragmentary front left perspective of a
compressor package constructed in accordance with a first
embodiment of the present invention, and showing a base, motor,
centrifugal compressor, intake system, transmission, hydraulic
assembly, inlet guide vane assembly, and guide vane controller of
the compressor package, with the controller including a bypass
valve in fluid communication with the compressor discharge and
operable to vent compressor airflow to ambient;
[0015] FIG. 2 is a fragmentary front right perspective of the
compressor package shown in FIG. 1;
[0016] FIG. 3 is a fragmentary rear perspective of the compressor
package shown in FIGS. 1 and 2, with part of the transmission
housing being removed to show an internal gear drive of the
transmission;
[0017] FIG. 4 is a fragmentary front right perspective of the
compressor package shown in FIGS. 1-3, showing the compressor,
inlet guide vane assembly, and controller;
[0018] FIG. 5 is a front right perspective of the compressor, inlet
guide vane assembly, and controller similar to FIG. 4, but showing
part of the compressor housing and part of the guide vane housing
removed to show the guide vanes and transmission that controls
positioning of the guide vanes, with the guide vanes in a
predetermined preswirl position and the piston in a corresponding
central position, and showing part of the controller housing
removed to show a sensor assembly, valve, and hydraulic piston of
the controller, with the valve being in a closed position;
[0019] FIG. 6 is a right rear perspective of the compressor, inlet
guide vane assembly, and controller shown in FIG. 5, with the guide
vanes in the predetermined preswirl position and the valve in the
closed position;
[0020] FIG. 7 is an enlarged front right perspective of the
compressor, inlet guide vane assembly, and controller similar to
FIG. 5;
[0021] FIG. 8 is a front elevation of the inlet guide vane assembly
and controller shown in FIGS. 1-7, showing the controller
cross-sectioned to depict the valve within the controller
housing;
[0022] FIG. 9 is a perspective of the valve shown in FIGS. 5, 7,
and 8, showing slotted and chamfered ends of the cylindrical valve,
with upper and lower slots formed along the slotted end, and
showing upper and lower bores extending longitudinally from
corresponding upper and lower slots to corresponding ends of the
valve;
[0023] FIG. 10 is a cross section of the valve shown in FIGS. 5, 7,
8, and 9, showing the upper and lower bores extending
longitudinally through the valve;
[0024] FIG. 11 is a cross section of the inlet guide vane assembly
and controller shown in FIGS. 1-8, showing the valve rotated into
the closed position, with the closed valve preventing fluid flow
between the upper and lower slots and the supply and return
bores;
[0025] FIG. 12 is a front right perspective of the compressor,
inlet guide vane assembly, and controller similar to FIG. 5, but
showing the sensor assembly pivoted rearwardly toward the inlet
guide vanes in response to a high-velocity intake airflow so that
the valve assumes a vane-closing position, with the valve
permitting pressurized supply fluid to flow from the supply bore to
the right piston chamber so that the piston is shifted into a left
endmost position, and with the inlet guide vanes being shifted by
the piston into a corresponding maximum preswirl condition to
generally reduce the airflow to the compressor;
[0026] FIG. 13 is a cross section of the inlet guide vane assembly
and controller similar to FIG. 11, but showing the valve pivoted
into the vane-closing position, with the upper slot of the valve
fluidly communicating with the supply bore and the lower slot of
the valve fluidly communicating with the return bore;
[0027] FIG. 14 is a front right perspective of the compressor,
inlet guide vane assembly, and controller similar to FIG. 5, but
showing the sensor assembly pivoted forwardly from the inlet guide
vanes in response to a low-velocity intake airflow so that the
valve assumes a vane-opening position, with the valve permitting
pressurized supply fluid to flow from the supply bore to the left
piston chamber so that the piston is shifted into a right endmost
position, with the inlet guide vanes being shifted by the piston
into a corresponding maximum counterswirl condition to generally
increase the airflow velocity and, in instances where the
counterswirl condition does not increase the low-velocity airflow
to a predetermined velocity, the left piston chamber exceeds a
predetermined pressure so that a pressure relief valve allows fluid
to flow from the left piston chamber to the bypass valve and
thereby open the bypass valve;
[0028] FIG. 15 is a cross section of the inlet guide vane assembly
and controller similar to FIG. 11, but showing the valve pivoted
into the vane-opening position, with the upper slot of the valve
fluidly communicating with the return bore and the lower slot of
the valve fluidly communicating with the supply bore;
[0029] FIG. 16 is a schematic view of the hydraulic assembly and
controller shown in FIGS. 1-3, showing a pressure regulator, heat
exchanger, pump, and sump of the hydraulic assembly, and showing
the valve, actuator, pressure relief valve, and bypass valve of the
controller;
[0030] FIG. 17 is a fragmentary cross section of an alternative
compressor package constructed in accordance with a second
embodiment of the present invention, with the controller including
a diaphragm depicted schematically, showing the diaphragm attached
to an arm of the sensor assembly and fluidly communicating with the
compressor volute to sense compressor discharge pressure; and
[0031] FIG. 18 is a graph showing an operational characteristic of
the alternative compressor package without the diaphragm and
operational characteristics of the alternative compressor package
with the diaphragm installed in different configurations.
[0032] The drawing figures do not limit the present invention to
the specific embodiments disclosed and described herein. The
drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of the preferred
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Turning initially to FIGS. 1 and 2, a modular compressor
package 20 is illustrated for installation as part of a pneumatic
conveying system to convey various types of particulate media.
However, the compressor package 20 is capable of providing
compressed air for other applications without departing from the
scope of the present invention. Furthermore, the illustrated
compressor package 20 is particularly suitable for use as a
retrofit into a pneumatic conveying system in place of a
positive-displacement compressor. It has been found that the
compressor package 20 is operable to provide compressed air at a
substantially uniform velocity, much like a positive-displacement
compressor, while providing better overall compressor efficiency.
The modular compressor package 20 broadly includes a base 22, a
motor 24, a centrifugal compressor 26, an intake system 28, a
transmission 30, a hydraulic assembly 32, an inlet guide vane
assembly 34, and a guide vane controller 36.
[0034] Turning to FIGS. 1-3, the base 22 supports the rest of the
compressor package 20. The base 22 includes an elevated frame 38
supported on upright legs 40 and a compressor platform 42 secured
adjacent one end of the frame 38. In the usual manner, the elements
of base 22 are preferably formed of steel, although the base 22
could include other materials. While the base 22 has components
supported entirely by frame 38, the base 22 could have an
additional frame spaced above or below frame 38 to alternatively
support the package components.
[0035] The motor 24 provides power to the compressor package 20.
The motor 24 comprises an electric motor that is drivingly attached
to the transmission 30 in the usual manner. Another type of motor,
such as an internal combustion engine, could be substituted for the
electric motor without departing from the scope of the present
invention.
[0036] Turning to FIGS. 1-4, the compressor 26 is a conventional
centrifugal compressor and is operable to provide compressed air
for various applications, such as pneumatic conveying. The
compressor 26 includes a housing 44, an impeller shaft 46 rotatably
mounted on the housing 44, and an impeller 48 mounted on the shaft
46 to rotate with the shaft 46. The housing 44 presents a chamber
that rotatably receives the impeller 48 and presents an inlet 50
and a discharge 52. In the usual manner, the impeller 48 draws
airflow into the housing 44 via the inlet 50 and provides
compressed airflow through the discharge 52. As will be discussed,
the inlet guide vane assembly 34 is attached the housing 44
upstream of the inlet 50.
[0037] The intake system 28 is attached to the compressor 26 and
fluidly communicates with the inlet 50. The intake system 28
includes an air intake plenum 54 and flexible tube 56 that fluidly
interconnects the plenum 54 and the inlet guide vane assembly 34.
As will be discussed, a heat exchanger of the hydraulic assembly 32
is mounted to the inlet of plenum 54 to cool hydraulic fluid.
[0038] Turning to FIG. 3, the transmission 30 provides power from
the motor 24 to the compressor 26 and the hydraulic assembly 32.
The illustrated compressor package 20 is preferably configured so
that the transmission 30 is generally external to the compressor
26. However, the principles of the present invention are applicable
where the compressor 26 has an internal transmission. Furthermore,
the transmission could be configured to provide self-lubrication.
Preferred details of such a compressor and transmission arrangement
are disclosed in U.S. Pat. No. 6,439,208, issued Aug. 27, 2002,
entitled CENTRIFUGAL SUPERCHARGER HAVING LUBRICATING SLINGER, which
is hereby incorporated in its entirety by reference herein.
[0039] The transmission 30 preferably includes a housing 58, an
external belt drive 60, and an internal gear drive 62. The belt
drive 60 includes a drive sheave (not shown) mounted on the shaft
of the motor 24, a driven sheave 64 mounted on an input shaft 66 of
the gear drive 62, and a toothed belt 68 drivingly entrained on the
sheaves so that the motor 24 powers the input shaft 66.
[0040] The gear drive 62 includes the input shaft 66 and an
intermediate shaft 70. The gear drive 62 further includes a drive
gear (not shown) mounted on the input shaft 66. Gears 72,74 are
mounted on the intermediate shaft 70. The gear drive 62 further
includes a driven gear 76 mounted to a drive shaft (not shown) of a
hydraulic positive-displacement pump of the hydraulic assembly 32.
The gear drive 62 also includes a driven gear 78 mounted on the
impeller shaft 46.
[0041] The transmission 30 provides power to the impeller 48 by
transmitting power from the motor 24 to the input shaft 66. Power
is then transmitted to gear 72 and to driven gear 78, which is
drivingly mounted on the impeller shaft 46. The gears 72,78 are
preferably sized to provide a step-up arrangement to increase the
rotational speed of the compressor 26, although an alternative
drive configuration could be employed to power the impeller 48
[0042] The transmission 30 provides power to the hydraulic pump by
transmitting power through the belt drive 60 to the input shaft 66.
Power is then transmitted to gear 72 and intermediate shaft 70.
Power is further transmitted from the gear 74 to the driven gear 76
mounted on the pump shaft. The gears 74,76 preferably provide a
step-down arrangement to decrease the rotational speed of the
hydraulic pump, although an alternative drive could be used to
power the pump.
[0043] Turning to FIGS. 1-3 and 16, the hydraulic assembly 32
provides lubricant to transmission 30 and also provides hydraulic
power to the controller 36. The hydraulic assembly 32 broadly
includes a hydraulic pump 80, a sump 82, a heat exchanger 84, and a
pressure regulator 86, with hydraulic lines 87a,b,c,d,e,f,g,h
fluidly connecting the components. (see FIG. 16). The pump 80 is
preferably a conventional positive-displacement hydraulic pump and
includes a pump drive shaft (not shown). The pump 80 is mounted on
a sidewall of the housing 58. The pump drive shaft extends through
the sidewall into the transmission chamber and receives the driven
gear 76 so that the driven gear 76 rotates with the drive
shaft.
[0044] Turning to FIGS. 5, 6, 12, and 14, the inlet guide vane
assembly 34 controls airflow drawn through the inlet 50 of
compressor 26. The inlet guide vane assembly 34 broadly includes a
two-piece annular housing 88, a plurality of vanes 90 rotatably
mounted in the housing 88, and a gear assembly 92. The housing 88
preferably includes two annular housing sections that are removably
attached to one another and cooperatively form an annular chamber
that receives the vanes 90 and gear assembly 92. The housing 88 is
removably attached to the housing of compressor 26 adjacent the
inlet 50. However, it is also within the scope of the present
invention where the housing 88 is alternatively constructed. Yet
further, the assembly 34 could be configured so that housing 88 is
eliminated, e.g., where the assembly 34 is integrated into the
compressor housing.
[0045] The vanes 90 each preferably include a flat vane body 94 and
a shaft 96 attached to the body 94 with fasteners. The principles
of the present invention are also applicable where the body 94
takes a different shape, e.g., another shape that provides improved
vane performance.
[0046] The vanes 90 are pivotally mounted in the housing 88 and are
spaced circumferentially about a passage 98 that extends through
the housing and toward the impeller 48. The inlet guide vane
assembly 34 further includes bearings 100 that rotatably receive
corresponding shafts 96. Furthermore, the assembly 34 includes caps
102,103 that are attached to and are rotatable with corresponding
shafts 96. The illustrated assembly 34 preferably includes eight
vanes 90, although a larger or smaller number of vanes 90 could be
used to provide suitable vane performance.
[0047] The gear assembly 92 drivingly interconnects the vanes 90
with one another so that the vanes 90 are synchronously shiftable.
The gear assembly 92 broadly includes a ring gear 104 and pinion
gears 106 positioned along the length of the ring gear 104. The
ring gear 104 presents an endless toothed surface 108 that
generally faces in an axial direction. The ring gear 104 is
rotatably mounted within an annular groove of the housing 88 so
that the toothed surface 108 generally faces forwardly. The gear
assembly 92 also includes an annular bushing (not shown) and a wave
spring (not shown) received between the ring gear 104 and groove.
In particular, the bushing is positioned between the ring gear 104
and wave spring, with the wave spring engaging the base of the
groove. Thus, the wave spring urges the ring gear 104 into
engagement with pinion gears 106.
[0048] The pinion gears 106 each have a toothed body 110 and a
sleeve 112 integrally formed with the body 110. The sleeve 112
receives a threaded set screw 114. The teeth of body 110 present a
pinion diameter that tapers from adjacent the sleeve 112 to an end
of the pinion gear 106 opposite the sleeve 112. Preferably, the
pinion diameter presents a taper angle relative to the rotational
axis of the pinion gear 106 that ranges from about five (5) degrees
to about six (6) degrees, although the pinion gears 106 could be
alternatively configured.
[0049] The pinion gears 106 are mounted on corresponding shafts 96
of the vanes 90, and each gear 106 is positioned between the
respective bearing 100 and cap 102. The gears 106 are preferably
secured by threading set screw 114 into engagement with shaft 96.
Thus, the gears 106 are preferably spaced about the circumference
of the ring gear 104. It has been found that this arrangement of
gears 106 and the tapered pinion construction allow the pinion
gears 106 to cooperatively maintain the ring gear 104 centered
relative to the gears 106.
[0050] Again, the vanes 90 are spaced about the passage 98, and the
pinion gears 106 each engage the toothed surface 108. One of the
shafts 96 extends radially outwardly from the cap 103 and is
attached to a swing arm 116. Thus, rotation of the swing arm 116
causes rotation of the shaft 96 and pinion gear 106 attached to the
swing arm 116. Because the pinion gears 106 intermesh with the ring
gear 104, this movement causes rotation of the ring gear 104 about
the passage 98 and corresponding pivotal movement of the other
pinion gears 106. Thus, the pinion gears 106 and vanes 90 move
synchronously with one another. Furthermore, each gear 106 and vane
90 rotates in the same rotational direction as the other gears 106
and vanes 90. The rotational direction of a vane 90 is determined
from a corresponding fixed reference point on the housing 88. Thus,
if one vane 90 is rotated in a clockwise direction, the other vanes
90 also rotate in the clockwise direction at the same time.
[0051] Turning to FIG. 6, the vanes 90 can preferably be positioned
relative to a passage axis A to provide either preswirl or
counterswirl to the incoming airflow, or to impart substantially no
swirling motion to the air flow. The preswirl direction coincides
with the rotational direction of the impeller 48 and is clockwise
when viewing the impeller 48 along the passage axis A. Thus, the
counterswirl direction is counterclockwise when viewing the
impeller 48 along the passage axis A. When the vanes 90 are in a
neutral condition (i.e., the vanes 90 impart no preswirl or
counterswirl), the vanes 90 are arranged so that the plane of vane
body 90 is aligned with the passage axis A.
[0052] The vanes 90 can be rotated clockwise from the neutral
condition into a maximum preswirl condition. In the illustrated
maximum preswirl condition, the vanes 90 are preferably rotated to
an angle of about eighty (80) degrees clockwise from the axis A and
the passage 98 is almost fully occluded. However, as will be
discussed, the controller 36 can be adjusted to provide an
alternative vane preswirl position associated with maximum
preswirl. Similarly the vanes 90 can be rotated counterclockwise
from the neutral condition into a maximum counterswirl condition.
In the illustrated maximum counterswirl condition, the vanes 90 are
preferably rotated to an angle of about fifteen (15) degrees
counterclockwise from the axis A. Again, the controller 36 can be
adjusted to provide an alternative vane counterswirl position
associated with maximum counterswirl. However, for some
applications, the controller 36 can also be adjusted so that the
vanes 90 are not shiftable into any counterswirl position, i.e.,
the vanes 90 are always in a preswirl position or the neutral
condition.
[0053] The illustrated vanes 90 are preferably arranged upstream of
inlet 50 to provide preswirl of incoming airflow. However, the
principles of the present invention are applicable where vanes are
employed to control the discharge flow of compressor 26. For
instance, the compressor 26 could include vanes mounted into the
diffuser of compressor 26. Alternatively a vane arrangement similar
to the illustrated vane assembly 34 could be located downstream of
the compressor discharge 52. For some aspects of the present
invention, the compressor package 20 could employ an alternative
valve-type mechanism to control compressor airflow. For instance,
some types of valves (such as a butterfly valve) could be installed
upstream or downstream of the compressor 26 and used to throttle
compressor airflow.
[0054] Turning to FIGS. 4-10, the illustrated controller 36 is
operable to position the vanes 90 of assembly 34 so that the
compressor 26 provides a compressed airflow with a substantially
constant velocity. It has been found that such operation is
desirable in various compressor applications, such as pneumatic
conveying. The controller 36 broadly includes a controller housing
assembly 118, a valve assembly 120, a velocity sensor assembly 122,
a hydraulically-driven actuator 124, and a bypass valve 125.
[0055] The housing assembly 118 preferably includes a central
housing 126, end manifolds 128,130, and end caps 132. The central
housing 126 includes a generally rectangular cuboid body that
presents an open rear slot 134 spaced between ends of the housing
126 (see FIGS. 7 and 8), end faces 136,138 (see FIG. 8), a
centrally-located bottom cavity 140 that opens to front and bottom
faces of the housing 126, and transverse valve and piston bores
142,144 that extend laterally between the end faces 136,138. The
central housing 126 also includes a cover plate 146 that is
removably attached to the body with fasteners. The cover plate 146
covers the bottom cavity 140 along the front face (see FIGS. 1 and
11).
[0056] The end manifold 128 comprises a generally rectangular
cuboid body and presents end faces 148,150 (see FIG. 8). The end
face 150 includes a slot 152 spaced from the outer margin of the
end face 150 (see FIG. 7). A piston end bore 154 extends from the
slot 152 toward the end face 148, with a threaded hole 156
extending from the end face 148 to the bore 154.
[0057] The end manifold 128 is removably attached to the central
housing 126 with fasteners that extend through the body of manifold
128 and are threaded into the central housing 126. With the end
manifold 128 attached to the central housing 126, the end face 150
engages the end face 136 of central housing 126 (see FIG. 8). Also,
the piston end bore 154 is preferably aligned with the piston bore
144 (see FIG. 7). Furthermore, the recess presented by the slot 152
preferably fluidly communicates with the valve bore 142 (see FIG.
8).
[0058] The end manifold 130 also comprises a generally rectangular
cuboid body and presents end faces 158,160 (see FIG. 8). A piston
end bore 162 extends from end face 158 toward the end face 160,
with a threaded hole 164 extending from the end face 160 to the
bore 162. The end manifold 130 also presents transversely extending
supply and return bores 166,168 extending from the end face 160
toward the end face 158. A fore-and-aft bore 170 extends from the
front face of end manifold 130 to the return bore 168. An upright
bore 171 extends from the top face of end manifold 130 to a valve
end bore 172. Once the bores 170,171 are machined, the open ends of
the bores 170,171 are closed with plugs (not shown) to prevent
fluid leakage from the bores 170,171.
[0059] The end manifold 130 is removably attached to the central
housing 126 with fasteners 174 that extend through the body of
manifold 130 and are threaded into the central housing 126. With
the end manifold 130 attached to the central housing 126, the end
face 158 engages the end face 138 of central housing 126 (see FIG.
8). Also, the piston end bore 162 is preferably aligned with the
piston bore 144 (see FIG. 7). Furthermore, the valve end bore 172
is preferably aligned with the valve bore 142 (see FIG. 8).
[0060] The housing assembly 118 is preferably removably mounted on
a platform of the housing 88, with the housing assembly 118 being
located above the passage 98 and located forwardly of the vanes 90.
However, the housing assembly 118 could be alternatively supported
relative to the inlet guide vane assembly 34.
[0061] The central housing and end manifolds 128,130 of the housing
assembly 118 are preferably formed of aluminum, but could be formed
of other materials, such as stainless steel or carbon steel. Yet
further, the components of housing assembly 118 could be
alternatively configured to provide suitable controller
operation.
[0062] The hydraulic assembly 32 and housing assembly 118 are
fluidly connected to one another so that pressurized hydraulic
fluid can be supplied to the controller 36 and returned from the
controller 36. In particular, line 87d runs from the pressure
regulator 86 to supply port S so that pressurized hydraulic fluid
can flow to supply bore 166. Line 87h runs from return port R to
sump 82 so that pressurized hydraulic fluid can be returned from
return bore 168. While the controller 36 is preferably
hydraulically powered, for some aspects of the present invention
the controller 36 could be pneumatically operated.
[0063] Turning to FIGS. 7-10, the valve assembly 120 serves to
control and selectively allow hydraulic fluid flow within the
controller 36. The valve assembly 120 includes a rotatable valve
176, bearings 178, and seals 180. The valve 176 preferably
comprises a unitary and cylindrical metal body that presents a
chamfered end 182 and a slotted end 184 (see FIGS. 9 and 10). The
valve 176 presents upper and lower slots 186,188 that extend
perpendicular to the length of the valve 176 and along the end 184.
An upper longitudinal bore 190 extends from the end 184 to the
upper slot 186. A lower longitudinal bore 192 extends from the end
182 to the lower slot 188. The valve 176 further presents a
centrally spaced fore-and-aft slot 194 and a through hole 196.
[0064] The valve 176 is rotatably received within the valve bore
142 and valve end bore 172. In particular, the chamfered end 182 is
positioned adjacent the end face 136 and the slotted end 184 is
located within the valve end bore 172 so that a gap 198 is defined
between the slotted end 184 and the end of the valve end bore 172
(see FIG. 8).
[0065] Bearings 178 are secured in annular slots formed adjacent to
and surrounding corresponding ends of the valve bore 142. The
bearings 178 rotatably receive and support the valve 176 within the
housing assembly 118 and permit rotation relative thereto. A pair
of seals 180 are received in corresponding glands that surround the
valve bore 142 and are located between the annular bearing slots.
The seals 180 rotatably engage the valve 176 and restrict
pressurized fluid from flowing from the recess of slot 152 to the
bottom cavity 140 and from the valve end bore 172 to the bottom
cavity 140. Preferably, the seals 180 are formed of PTFE material
to provide low friction, although other materials could be
used.
[0066] Turning to FIGS. 7 and 11-15, the valve 176 is operable to
control hydraulic fluid flow within the controller 36 by
selectively allowing hydraulic fluid to flow between piston end
bores 154,162 and the supply and return bores 166,168. In a closed
position, the valve 176 is positioned so that neither of the slots
186,188 is in fluid communication with the fore-and-aft bore 170
(see FIGS. 7 and 11). The fore-and-aft bore 170 provides part of
the paths for fluid to flow between the bores 166,168 and piston
end bores 154,162. Thus, the closed valve 176 prevents fluid flow
into and out of the controller 36.
[0067] In a vane-closing position, the valve 176 is positioned so
that the upper slot 186 fluidly communicates with the supply bore
166 via a front portion of the fore-and-aft bore 170, and the upper
slot 186 thereby receives pressurized supply fluid (see FIGS. 12
and 13). The piston end bore 162, upright bore 171, gap 198, and
upper bore 190 are also in fluid communication with the upper slot
186 and also receive pressurized supply fluid.
[0068] At the same time, in the vane-closing position, the lower
slot 188 fluidly communicates with the return bore 168 via a rear
portion of the fore-and-aft bore 170, and the lower slot 188
thereby returns pressurized supply fluid. The piston end bore 154,
slot 152, and lower bore 192 are also in fluid communication with
the lower slot 188 to thereby return pressurized supply fluid in
the vane-closing position.
[0069] In a vane-opening position, the valve 176 is positioned so
that the lower slot 188 fluidly communicates with the supply bore
166 via the front portion of the fore-and-aft bore 170, and the
lower slot 188 thereby receives pressurized supply fluid (see FIGS.
14 and 15). Again, the piston end bore 154, slot 152, and lower
bore 192 are in fluid communication with the lower slot 188 and
also receive pressurized supply fluid.
[0070] At the same time, in the vane-opening position, the upper
slot 186 fluidly communicates with the return bore 168 via the rear
portion of the fore-and-aft bore 170, and the upper slot 186
thereby returns pressurized supply fluid. Again, the piston end
bore 162, upright bore 171, gap 198, and upper bore 190 are in
fluid communication with the upper slot 186 and also return
pressurized supply fluid in the vane-opening position. In this
manner, the illustrated vane arrangement simultaneously pressurizes
and depressurizes opposite sides of the illustrated hydraulic
piston, as will be discussed.
[0071] The illustrated valve assembly 120 preferably comprises a
mechanically-driven fluid valve. However, for some aspects of the
present invention, the valve assembly 120 could include an
alternatively-driven valve arrangement, such as an electronic
solenoid valve.
[0072] The velocity sensor assembly 122 is shiftably received in
the passage 98 and is operable to rotate the valve 176. The
velocity sensor assembly 122 broadly includes an elongated arm 200,
a plate 202, a spring 204, and an adjuster 206. The arm 200
presents opposite ends, with an upper end being removably attached
to the valve 176 within the central slot 194 by a threaded fastener
208. The plate 202 is generally circular and is removably attached
to a lower end of the arm 200 by screws 210 (see FIG. 5). The arm
200 and plate 202 preferably take the illustrated shape, but it is
also within the ambit of the present invention where the arm 200
and plate 202 have alternative shapes to provide desired sensor
operation. For example, the plate 202 could have a larger or
smaller diameter so that the plate 202 applies a correspondingly
larger or smaller drag force to the arm 200 when airflow is rushing
past the sensor.
[0073] With the arm 200 secured to the valve 176, the valve 176,
arm 200, and plate 202 are operable to pivot with one another about
a lateral axis. Again, the valve 176 pivots to direct pressurized
fluid through the controller 36. The sensor assembly 122 serves to
operate the valve 176, as will be discussed below.
[0074] Turning to FIG. 4, the adjuster 206 provides tension
adjustment of the spring 204. The adjuster 206 includes a slotted
body 212 with opposite end slots 214. The body 212 is slidably
received by complemental grooves 216 that form part of the bottom
cavity 140 of the central housing 126. Thus, the body 212 is
operable to slide up and down within the cavity 140. The body 212
is adjustably positioned by a tensioning screw 218 that extends
through a hole in the central housing 126 and is rotatably received
by the body 212.
[0075] The spring 204 includes opposite end hooks 220, with one end
hook 220 removably attached to the arm 200 at a location preferably
about one-third of the arm length from the upper arm end. The other
end hook 220 is removably attached to the body 212 (see FIG. 7).
The illustrated adjuster 206 is spaced in front of and above the
arm 200 so that the spring 204 urges the arm 200 in a forward
direction, i.e., generally opposite the normal airflow direction
into the inlet 50. However, the sensor assembly 122 could have an
alternative construction to provide adjustment of the valve 176.
For instance, the assembly 122 could have one or more alternative
springs to control positioning of the arm 200.
[0076] Furthermore, the sensor assembly 122 could include a
traditional damping mechanism, such as a fluid-filled damper,
connected between the arm 200 and housing 126 to provide additional
control of the valve 176. However, one of ordinary skill will
appreciate that suitable damping of the valve 176 and actuator 124
can be provided by various alternative constructions. Furthermore,
some damping of the controller 36 is provided inherently by the
hydraulic arrangement of the controller 36. That is, the hydraulic
fluid within the controller 36 provides some damping of the
actuator 124, valve 176, and fluid pressure signals transmitted
therebetween.
[0077] In the illustrated embodiment, the spring 204 urges the arm
200 so that the valve 176 assumes the closed position when the
airflow is at a predetermined airflow velocity; that is, the arm
200 is preferably held by the spring somewhere between the extreme
positions during "ideal" operating conditions. However, the
adjuster 206 is operable to change the spring tension (and thereby
the length of spring 204) to vary the predetermined airflow
velocity that corresponds to the valve 176 in the closed position.
In particular, as the adjuster 206 is shifted upwardly to provide
greater spring tension, the predetermined airflow velocity
associated with the closed valve position generally increases. As
the adjuster 206 is shifted downwardly to decrease spring tension,
the predetermined airflow velocity associated with the closed valve
position generally decreases.
[0078] Preferably, the illustrated sensor assembly 122 is primarily
responsive to airflow velocity through the passage 98. However, as
will be shown in a subsequent embodiment, the controller can be
alternatively configured to include a diaphragm attached to the arm
200, where the diaphragm senses compressor discharge pressure and
applies a force to the arm 200 in response to the pressure.
[0079] The illustrated sensor assembly 122 preferably comprises a
mechanical velocity sensor. However, for some aspects of the
present invention, an alternative velocity or mass flow sensor,
such as a pivot tube or hot wire anemometer, could be used to
determine airflow velocity for the compressor package 20. As
discussed above, the valve assembly 120 could include an
alternative valve, such as an electronic solenoid valve. For some
aspects of the present invention, the compressor package 20 could
utilize a solenoid valve in combination with an electronic velocity
sensor to alternatively sense airflow and provide fluid control of
the inlet guide vanes.
[0080] Turning to FIG. 7, the hydraulically-driven actuator 124
serves to drive the swing arm 116. The actuator 124 preferably
includes a piston 222, a screw 224, and a bushing 226. The piston
222 preferably comprises a unitary cylindrical rod that presents
opposite ends 228, a smooth cylindrical surface 230, and a central
flat 232 spaced between the ends 228.
[0081] The piston 222 is reciprocally received in piston bore 144
and end bores 154,162 so as to be slidable between left and right
endmost positions corresponding to the vanes 90 in the maximum
preswirl condition and the maximum counterswirl condition (see
FIGS. 12 and 14). In each endmost position, the piston 222 contacts
a corresponding stop 234, which comprises a threaded screw that is
adjustably positionable to change the location of the endmost
position. Thus, the left stop 234 can be adjusted to provide an
alternative vane preswirl position associated with maximum
preswirl. Also, the right stop 234 can be adjusted to provide an
alternative vane counterswirl position associated with maximum
counterswirl. Again, for some applications, the right stop 234 can
also be adjusted so that the vanes 90 are not shiftable into any
counterswirl position, i.e., the vanes 90 are always in a preswirl
position or the neutral condition. The stops 234 are covered by end
caps 132 secured to the respective end manifold with fasteners. The
stops 234 can be selectively accessed for adjustment by removing
the respective end cap 132.
[0082] The piston 222 and end bores 154,162 cooperatively form
corresponding fluid chambers 236,238 that receive pressurized
fluid. The illustrated piston 222 is preferably a double-acting
piston, although the controller 36 could be configured so that the
piston 222 is single-acting without departing from the scope of the
present invention. Low-friction seals 240 are located at
corresponding ends of the central housing 126 and extend around the
piston 222 to hold fluid within the chambers 236,238. Preferably,
the seals 240 are formed of PTFE material to provide low friction,
although other materials could be used.
[0083] The piston 222 is removably attached to the swing arm 116 by
inserting the screw 224 and bushing 226 through a slot 242 in the
swing arm 116. Thus, as the piston 222 reciprocates between the
endmost positions, the screw 224 and bushing 226 slide along the
slot 242. Thus, the swing arm 116 pivots in a manner corresponding
to sliding movement of the piston 222.
[0084] As discussed above, pivotal movement of the swing arm 116
causes corresponding pivotal movement of the vanes 90. Thus,
sliding movement of the piston 222 results in corresponding pivotal
movement of the vanes 90. With the piston 222 in the left endmost
position, the vanes 90 are shifted to the maximum preswirl
condition (see FIG. 12). With the piston 222 in the right endmost
position, the vanes 90 are shifted to the maximum counterswirl
condition (see FIG. 14).
[0085] The actuator 124 uses hydraulic fluid from the hydraulic
system to power the vanes 90 depending on the position of valve
176. As discussed above, the valve 176 has a closed position and
opposite open positions (i.e., the vane-opening position and the
vane-closing position).
[0086] In the vane-closing position, the valve 176 is positioned so
that the upper slot 186 fluidly communicates with the supply bore
166 (see FIG. 12). Consequently, the piston end bore 162 is in
fluid communication with the upper slot 186 to receive pressurized
supply fluid and fill the fluid chamber 238. At the same time, the
lower slot 188 fluidly communicates with the return bore 168. Thus,
the piston end bore 154 is in fluid communication with the lower
slot 188 to return pressurized supply fluid in the vane-opening
position and thereby empty the fluid chamber 236. The simultaneous
filling and emptying of chambers 236,238 causes the piston 222 to
shift to the left, with the vanes 90 shifting to the maximum
preswirl condition (see FIG. 12).
[0087] In the vane-opening position, the valve 176 is positioned so
that the lower slot 188 fluidly communicates with the supply bore
166. The piston end bore 154 is in fluid communication with the
lower slot 188 to receive pressurized supply fluid and fill the
fluid chamber 236. At the same time, the upper slot 186 fluidly
communicates with the return bore 168. The piston end bore 162 is
in fluid communication with the upper slot 186 to return
pressurized supply fluid in the vane-closing position and thereby
empty the fluid chamber 238. This simultaneous filling and emptying
of chambers 236,238 causes the piston 222 to shift to the right,
with the vanes 90 shifting to the maximum counterswirl condition
(see FIG. 14).
[0088] The inlet guide vane assembly 34 and controller 36 are
depicted with the piston 222 and vanes 90 in certain discrete
positions. Specifically, the piston 222 is shiftable between
endmost positions with the vanes 90 being shiftable between maximum
preswirl and maximum counterswirl conditions. However, it will be
appreciated that the illustrated piston 222 can position the vanes
90 into nearly an infinite number of intermediate positions between
the maximum preswirl and maximum counterswirl conditions. As
discussed above, the piston 222 is slidable continuously along a
lateral direction between the endmost positions. Also, the piston
222 is slidably attached to the swing arm 116. Thus, continuous
sliding movement of piston 222 between the endmost positions
results in corresponding pivotal movement of the swing arm 116,
which causes synchronized continuous pivotal movement of vanes 90
between the maximum preswirl and maximum counterswirl
conditions.
[0089] The illustrated actuator 124 preferably receives hydraulic
fluid to drive the inlet guide vanes. However, for some aspects of
the present invention, the actuator 124 could be alternatively
configured to receive hydraulic fluid and power the inlet guide
vanes. For instance, an alternative actuator could include a
hydraulic motor that receives a continuous hydraulic fluid flow
from the hydraulic system.
[0090] The illustrated controller 36 is preferably powered by the
hydraulic system so that the hydraulic system amplifies the power
input to the sensor assembly (caused by airflow in the passage 98)
and thereby drives the actuator 124 and guide vanes 90. Through the
direct mechanical connection between the sensor assembly and the
valve 176, the sensor assembly directly effects positioning of the
actuator 124 and thereby the vanes 90. For some aspects of the
present invention, the controller 36 could be configured so that
actuator 124 is powered by a conventional pneumatic power system,
such as a regulated shop-air system.
[0091] The compressor package 20 provides substantially uniform
airflow velocity by sensing the airflow and then shifting the inlet
guide vanes, if necessary, to maintain a desired airflow velocity.
For instance, in the illustrated embodiment, the compressor package
20 could maintain airflow velocity with a preset amount of preswirl
(see FIG. 7).
[0092] In some instances, the compressed airflow discharged from
the compressor 26 can encounter significant backpressure, such as
when the package 20 is used in a pneumatic conveying system and a
large volume of particulate matter is injected downstream of the
compressor discharge. In such an instance, airflow velocity through
the compressor 26 will decrease and the spring 204 will cause the
sensor arm 200 to shift forwardly (i.e., away from the impeller) so
that the valve 176 shifts into the vane-opening condition, which
causes the vanes 90 to open. Thus, the vanes 90 open so that the
inlet guide vane assembly 34 provides minimal restriction to intake
airflow and thereby permits airflow velocity to increase and return
to the desired airflow velocity.
[0093] Preferably, the bypass valve 125 is also operable to provide
increased compressor airflow by venting compressed airflow from the
compressor discharge to ambient. The illustrated bypass arrangement
has been found to be particularly effective for low velocity
conditions in pneumatic conveying systems when a large volume of
particulate matter causes excessive backpressure in the compressor
26. The bypass valve 125 is mounted on main compressed air line 244
that runs from the compressor discharge 52. A bypass line 246 is
fluidly connected to the main line 244 and terminates at the bypass
valve 125. The bypass valve 125 receives pressurized hydraulic
fluid from the housing assembly 118 via a pressure relief valve 248
and line 250 and returns hydraulic fluid to the sump 82 via line
252 (see FIG. 16).
[0094] When the compressor package 20 encounters a low airflow
velocity due to substantial compressor backpressure, e.g., due to
clogging of a pneumatic conveying line downstream of the
compressor, the controller 36 initially opens the inlet guide vanes
to reduce the intake airflow restriction of the inlet guide vane
assembly and thereby allow greater airflow into the compressor 26.
Again, the controller 36 opens the vanes 90 in a low velocity
condition because the sensor arm 200 pivots forwardly and the valve
176 pivots so that pressurized fluid builds in the chamber 236 to
shift the piston 222 to the right (see FIG. 14). In the event that
the valve 176 remains in the vane-opening position because of
continued low-velocity airflow, fluid pressure will build within
chamber 236 up to the pressure of the hydraulic system, which
preferably ranges from about fifty (50) psi to about sixty (60)
psi. Once the pressure in chamber 236 exceeds the preset pressure
value, the pressure relief valve will open and cause bypass valve
125 to open. In this manner, the bypass valve 125 is operable to
correct a continued low-velocity airflow condition.
[0095] In other instances, the compressed airflow discharged from
the compressor 26 can encounter greatly reduced backpressure. For
example, in a pneumatic conveying system, the operator may
eliminate particulate matter from the line downstream of the
compressor discharge. In this instance, airflow velocity through
the compressor 26 will generally increase and the spring 204 will
cause the sensor arm 200 to shift rearwardly, i.e., toward the
impeller, so that the valve shifts into a vane-closing condition,
which causes the vanes 90 to close. Thus, the vanes 90 close so
that the inlet guide vane assembly 34 provides a substantial
airflow restriction to intake airflow. Consequently, airflow
velocity will decrease and return to the desired airflow
velocity.
[0096] Turning to FIGS. 17 and 18, a second preferred embodiment of
an alternative compressor package 300 is depicted. For the sake of
brevity, the remaining description will focus primarily on the
differences of this embodiment relative to the embodiment described
above. The primary difference is the use an airflow sensor with a
damping diaphragm. The alternative compressor package 300 includes
a compressor 302, an inlet guide vane assembly 304, and an
alternative sensor assembly 306. The sensor assembly 306 broadly
includes an arm 308, plate 310, a spring 312, an adjuster 314, and
a diaphragm 316. The diaphragm 316 and spring 312 are both attached
to the arm 308 at the same location between ends of the arm 308.
The diaphragm 316 also fluidly communicates with the compressor
volute so as to sense a compressor discharge pressure.
Consequently, the illustrated sensor assembly 306 controls the
inlet guide vanes in response to airflow velocity and compressor
discharge pressure.
[0097] Turning to FIG. 18, without the diaphragm 316, the
compressor package 300 has an operational characteristic identified
by line 318, i.e., the compressor package 300 would provide a
substantially constant airflow velocity over a range of compressor
pressures. With the diaphragm 316, performance of the compressor
package 300 can be adjusted to provide alternative operational
characteristics identified by lines 320,322.
[0098] The adjustable compressor performance provided by diaphragm
316 has been found to be particularly desirable in a pneumatic
conveying application. For example, when little or no particulate
media is being conveyed in the system, the compressor will produce
a relatively low discharge pressure with relatively high velocity.
The diaphragm 316 is configured to push the sensor arm rearwardly
to thereby encourage opening of the inlet guide vanes in a
low-pressure condition (see FIG. 17). For example, when a heavy
media, such as flour, is initially introduced into the conveying
system, the flour can readily cause clogging of the media line.
Thus, the illustrated diaphragm 316 is preferably connected to the
sensor to further increase airflow velocity when the media line has
little or no media in it, and the illustrated diaphragm 316
provides a compressor operational characteristic identified by line
322 (see FIG. 18). In this manner, the media line is ready to
receive a subsequent slug of media without becoming clogged.
[0099] For other purposes, the diaphragm 316 can be configured so
as to push the sensor arm forwardly to encourage at least partial
closure of the inlet guide vanes in response to low compressor
discharge pressure to thereby reduce airflow velocity. By reducing
airflow velocity, the power requirements of the compressor are
reduced, thus saving energy. Such a diaphragm configuration
provides a compressor operational characteristic identified by line
320 (see FIG. 18). For some types of media, such as plastic
granules, it has been found that media can be introduced into the
conveying system at relatively low-velocity airflow without
clogging the media line.
[0100] The preferred forms of the invention described above are to
be used as illustration only, and should not be utilized in a
limiting sense in interpreting the scope of the present invention.
Obvious modifications to the exemplary embodiments, as hereinabove
set forth, could be readily made by those skilled in the art
without departing from the spirit of the present invention.
[0101] The inventors hereby state their intent to rely on the
Doctrine of Equivalents to determine and assess the reasonably fair
scope of the present invention as pertains to any apparatus not
materially departing from but outside the literal scope of the
invention as set forth in the following claims.
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