Note: Descriptions are shown in the official language in which they were submitted.
TITLE: ELECTRO-HYDRAULIC VALVE ACTUATOR HAVING
MODULAR MANIFOLD WITH CONFIGURABLE REDUNDANCY
FIELD
[0001] The present subject-matter relates to electro-hydraulic
actuators such as
are used to control process valves.
INTRODUCTION
[0002] The flow of fluids and other substances carried in process
transport pipes
is typically controlled using process valves. It may be necessary in an
industrial process
to close or open a valve in response to specific conditions of the flow and/or
the
environment, such as a detected change in flow rate, pressure, temperature,
and so
forth.
[0003] Conventional control systems for valve actuators are often
designed to
respond to changes in process flow in different modes, such as fail open, fail
close, and
fail last (or fail last locked).
[0004] Electro-hydraulic actuators are often used in remote field locations
where
installing and maintaining a hydraulic network that can power multiple valve
actuators is
not practical. Conventional electro-hydraulic units are often bulky, complex,
fragile, and
time consuming to install and maintain. They include a hydraulic cylinder with
a piston
whose piston rod connects via an arm to open and close the process valve; a
separate
hydraulic reservoir that communicates with the cylinder via a pipe or hose
connection; a
hydraulic power unit consisting of an electric motor and a hydraulic pump; and
a control
system which includes valves that direct the flow of hydraulic fluid so as to
raise or
lower the piston in the cylinder and thereby control the process valve.
[0005] In the case of electro-hydraulic actuators designed to
operate in a fail
open or fail close mode, a return spring (or a hydraulic accumulator) is
included to bias
the actuator to its failsafe position, usually either to fully open the
process valve or fully
close it.
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[0006] In addition to having a failsafe mode, it may be desirable
for electro-
hydraulic actuators in some installations to be equipped with hydraulic power
redundancy, that is, a back-up pump for use in the event that the main pump
ceases to
be operational. The back-up pump could be a manually-operated pump, or it
could be a
motorized pump, preferably having an independent electric motor. Providing
such
operational redundancy further complicates the configuration of conventional
electro-
hydraulic valve actuators, and makes it very difficult to retrofit existing
installations to
add operational redundancy.
SUMMARY
[0007] The following summary is intended to introduce the reader to the
more
detailed description that follows, and not to define or limit the claimed
subject matter.
[0008] According to a first aspect, the present subject matter
provides an electro-
hydraulic valve actuator that includes a modular manifold assembly, a
hydraulic cylinder
assembly, and a hydraulic power assembly. The modular manifold assembly has a
network of channels therein. The hydraulic cylinder assembly has a piston with
a piston
rod that can connect directly or indirectly to open or close a process valve.
The
hydraulic power assembly has a main pump and motor that is fluidly connected
to the
hydraulic cylinder assembly by the channels of the manifold assembly. The
manifold
assembly includes a main manifold block to which is mounted the hydraulic
cylinder
assembly and the main pump and motor. The main manifold block has pluggable
channel ports that can be unplugged to provide fluid communication with
corresponding
channel ports of at least one auxiliary manifold block mounted to and
integrated with the
main manifold block.
[0009] In some examples, the electro-hydraulic valve actuator
comprises at least
two auxiliary manifold blocks mounted to and integrated with the main manifold
block.
[0010] In some examples, the at least one auxiliary manifold block
has a second
pump and motor.
[0011] In some examples, the at least one auxiliary manifold block
as a manual
override pump.
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[0012] In some examples, the electro-hydraulic valve actuator
further includes a
failsafe biasing mechanism for moving the process valve from a normal
operating
position to a failure mode position.
[0013] In some examples, the biasing mechanism includes a return
spring.
[0014] In some examples, the biasing mechanism includes an accumulator.
[0015] According to another aspect, the present subject matter
provides a
modular manifold assembly for an electro-hydraulic valve actuator having a
main pump
and motor assembly and having a hydraulic cylinder assembly. The modular
manifold
assembly includes a main manifold block to which can be mounted the hydraulic
cylinder assembly and the main pump and motor assembly. The main manifold
block
has pluggable channel ports that can be unplugged to provide fluid
communication with
corresponding channel ports of at least one auxiliary manifold block mounted
to and
integrated with the main manifold block.
[0016] In some examples, the at least one auxiliary manifold block
has a second
pump and motor mounted to it.
DRAWINGS
[0017] For a better understanding of the subject matter, and to show
more clearly
how it may be carried into effect, reference will now be made, by way of
example, to the
accompanying drawings which show exemplary embodiments, and in which:
[0018] FIG. 1 shows a perspective view of a modular electro-hydraulic valve
actuator.
[0019] FIG. 2 is a front elevation view thereof.
[0020] FIG. 3 is a side elevation view thereof.
[0021] FIG. 4 is a cross-sectional view thereof.
[0022] FIG. 5 is a detailed view of the hydraulic cylinder assembly
thereof.
[0023] FIG. 6 is an isolated perspective view of the manifold
assembly thereof.
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[0024] FIG. 7 is a similar view of the manifold assembly revealing
the internal
channels of portions of the manifold assembly.
[0025] FIG. 8 is a similar perspective view revealing all of the
internal channels of
the manifold assembly.
[0026] FIG. 9 is a schematic view of the hydraulic circuit thereof.
DESCRIPTION OF VARIOUS EMBODIMENTS
[0027] In the following description, specific details are set out to
provide
examples of the claimed subject matter. However, the embodiments described
below
are not intended to define or limit the claimed subject matter.
[0028] It will be appreciated that, for simplicity and clarity of
illustration, where
considered appropriate, reference numerals may be repeated among the figures
to
indicate corresponding or analogous elements or steps. Certain specific
details are set
forth in order to provide a thorough understanding of the subject matter.
However, it will
be understood by those of ordinary skill in the art that many details could be
varied
without departing from the claimed subject matter. Moreover, structures and
components that are well known to those skilled in the art have not been
described in
detail so as not to obscure the present subject matter.
[0029] Referring first to Figs. 1-5 an electro-hydraulic actuator 20
has a modular
manifold assembly 30, a hydraulic power assembly 40, a hydraulic cylinder
assembly 50
and a return spring assembly 60.
[0030] The modular manifold assembly 30 has a main manifold block
31, an
integral secondary manifold block 32, and an integral manual override manifold
block
33.
[0031] The hydraulic cylinder assembly 50 is mounted to the main
manifold block
31. The hydraulic cylinder assembly 50 includes a cylinder barrel 51, a piston
52 with a
piston rod 53. The cylinder barrel 51 is sealed at its upper end by a cylinder
cap 54 and
at its lower end by a cylinder head 55 which provides a base by which the
hydraulic
cylinder assembly 50 is mounted to the main manifold block 31.
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[0032] The hydraulic power assembly 40 comprises a main pump and
motor
assembly 41, and a secondary pump and motor assembly 42. The main pump and
motor assembly 41 is mounted to the main manifold block 31, whereas the
secondary
pump and motor assembly 42 is mounted to the secondary manifold block 32.
[0033] The hydraulic power assembly 40, also includes a manual override
pump
43 which is mounted to the manual override manifold block 33.
[0034] The return spring assembly 60 is also mounted to the main
manifold block
31 by means of a mounting block 61. The return spring assembly 60 is aligned
with, and
opposite to, the hydraulic cylinder assembly 50. Assuming that the electro-
hydraulic
actuator is oriented such that the modular manifold assembly 30 is generally
horizontal,
the hydraulic cylinder assembly 50 is mounted vertically above the main
manifold block
31, whereas the return spring assembly 60 is mounted vertically below the main
manifold block 31.
[0035] The return spring assembly 60 as a spring canister 62
containing a
compression spring 63. The end of the spring canister 62 that is distal from
the main
manifold block 31 has a mounting plate 66 by which the electro-hydraulic
actuator 20
can be mounted to a process valve assembly (not shown). A connecting arm 67
extends from the piston rod 53 through the spring canister 62 and exteriorly
of the valve
mounting plate 66 so that the connecting arm 67 can be linked directly or
indirectly to
the valve stem of the process valve (not shown).
[0036] The hydraulic cylinder assembly 50 also includes hydraulic
supply lines
56, and an annular hydraulic reservoir 57 defined by the outer surface of the
cylinder
barrel 51 and the inner surface of a concentric reservoir wall 58.
[0037] A network of channels 70 within the manifold assembly 30
connects the
hydraulic power assembly 40 to the hydraulic cylinder assembly 50.
[0038] As shown, the electro-hydraulic actuator 20 is configured for
operation in a
fail open mode. However, the main manifold channels 71 can be reconfigured
with an
alternate return spring assembly (not shown) that enables the electro-
hydraulic actuator
20 to operate in fail closed mode, or alternatively with no return spring
assembly 60 so
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that the electro-hydraulic actuator 20 operates in fail last mode. (In fail
last mode, the
solenoid valves SOLI and SOL2 shown in Fig. 9 are omitted and their connection
parts
on the manifold assembly 30.)
[0039] Certain of the main manifold channels 71 terminate at portals
73 on side
faces in of the main manifold block 31. The portals 73 can be plugged, or can
be open
to provide fluid communication with corresponding aligned portals of channels
in
mounted integral auxiliary manifold blocks 32, 33.
[0040] Turning to the hydraulic circuit diagram of Fig. 9, during
normal operation,
solenoid valves SOL1 and SOL2 are energized to prevent leakage of the cylinder
ports
back to the reservoir 57. When the main pump and motor assembly 41 operates,
hydraulic pressure is forwarded to the cylinder on the cap side of piston 52
via piloted
check valves PCV1 and PCV2. The piloted check valves require that pressure be
applied to one to permit opening the other. The hydraulic pressure moves the
piston 52
in the direction away from the cap 54 toward the head 55. The piston rod 53
thereby
extends and moves the connecting arm 67 so as to close the process valve. At
the
same time, spring 63 is compressed within the canister 62. When the process
valve is
fully closed (or in an intermediary position in the case of a modulating
actuator), the
main pump and motor assembly 41 is turned off. The pressure at the check
valves thus
drops and they close, maintaining the existing pressure in the cylinder.
[0041] In the event of a failure, solenoid valves SOLI and SOL2 are de-
energized and connect both cylinder ports to the reservoir 57. This permits
the
compressed spring 63 to decompress and move the piston to its retracted
position,
thereby opening the process valve.
[0042] In the event that the main pump and motor assembly 41 become
non-
operable, the actuator 20 automatically switches to the secondary pump and
motor
assembly 42. Referring again to the hydraulic circuit of Fig. 9, switching
from the main
pump and motor assembly 41 to the secondary pump and motor assembly 42 is
effected by de-energizing solenoid valves SOL3A and SOL3B to isolate the main
pump
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and motor assembly 41, and energizing solenoid valves SOL4A and SOL4B to
select
and activate the secondary pump and motor assembly 42.
[0043] The manual override pump 43 can be activated by opening needle
valves
NVBLK, to actuate the manual hand valve HOVD for the appropriate actuator
direction
(either process valve open or process valve closed), and then operating the
manual
override pump 43 to generate actuator movement. When a manual override
operation
has been completed, the needle valves NVBLK are closed to isolate the override
circuit
from the actuator.
[0044] While the above description provides examples of the present
subject
matter, it will be appreciated by those skilled in the art that certain
features and/or
functions of the described examples can be modified without departing from the
scope
of the subject matter as defined in the claims appended hereto.
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