U.S. patent application number 16/036344 was filed with the patent office on 2018-11-08 for rotary piston type actuator.
This patent application is currently assigned to Woodward, Inc.. The applicant listed for this patent is Woodward, Inc.. Invention is credited to Shahbaz H. Hydari, Joseph H. Kim, Robert P. O`Hara, Pawel A. Sobolewski.
Application Number | 20180320712 16/036344 |
Document ID | / |
Family ID | 50240058 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180320712 |
Kind Code |
A1 |
Kim; Joseph H. ; et
al. |
November 8, 2018 |
Rotary Piston Type Actuator
Abstract
A rotary actuator includes a first housing defining a first
arcuate chamber having a first cavity, a first fluid port in fluid
communication with the first cavity, and an open end. A rotor
assembly is rotatably journaled in the first housing and having a
rotary output shaft and a first rotor arm extending radially
outward from the rotary output shaft. An arcuate-shaped first
piston is disposed in the first housing for reciprocal movement in
the first arcuate chamber through the open end, wherein a first
seal, the first cavity, and the first piston define a first
pressure chamber, and a first portion of the first piston contacts
the first rotor arm.
Inventors: |
Kim; Joseph H.; (Valencia,
CA) ; O`Hara; Robert P.; (Castaic, CA) ;
Hydari; Shahbaz H.; (Los Angeles, CA) ; Sobolewski;
Pawel A.; (Arlington Heights, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Woodward, Inc. |
Fort Collins |
CO |
US |
|
|
Assignee: |
Woodward, Inc.
Fort Collins
CO
|
Family ID: |
50240058 |
Appl. No.: |
16/036344 |
Filed: |
July 16, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14992845 |
Jan 11, 2016 |
10030679 |
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16036344 |
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13778561 |
Feb 27, 2013 |
9234535 |
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14992845 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F15B 15/125 20130101;
F15B 15/06 20130101 |
International
Class: |
F15B 15/06 20060101
F15B015/06; F15B 15/12 20060101 F15B015/12 |
Claims
1. A rotary actuator comprising: a first housing defining a first
arcuate chamber comprising a first cavity, a first fluid port in
fluid communication with the first cavity, and an open end; a rotor
assembly rotatably journaled in said first housing and comprising a
rotary output shaft and a first rotor arm extending radially
outward from the rotary output shaft; and an arcuate-shaped first
piston disposed in said first housing for reciprocal movement in
the first arcuate chamber through the open end, wherein a first
seal, the first cavity, and the first piston define a first
pressure chamber, and a first portion of the first piston contacts
the first rotor arm.
2. The rotary actuator of claim 1, wherein the first housing
further defines a second arcuate chamber comprising a second
cavity, and a second fluid port in fluid communication with the
second cavity; the rotor assembly further comprises a second rotor
arm; the rotary actuator further comprising an arcuate-shaped
second piston disposed in said first housing for reciprocal
movement in the second arcuate chamber, wherein a second seal, the
second cavity, and the second piston define a second pressure
chamber, and a first portion of the second piston contacts the
second rotor arm.
3. The rotary actuator of claim 2, wherein the second piston is
oriented in the same rotational direction as the first piston.
4. The rotary actuator of claim 2, wherein the second piston is
oriented in the opposite rotational direction as the first
piston.
5. The rotary actuator of claim 1, wherein application of
pressurized fluid to the first pressure chamber urges the first
piston partially outward from the first pressure chamber to urge
rotation of the rotary output shaft in a first direction, and
rotation of the rotary output shaft in a second direction opposite
that of the first direction urges the first piston partially into
the first pressure chamber to urge pressurized fluid out the first
fluid port.
6. The rotary actuator of claim 1, further comprising a second
housing disposed about the first housing and having a second fluid
port, wherein the first housing, the second housing, the seal, and
the first piston define a second pressure chamber.
7. The rotary actuator of claim 6, wherein application of
pressurized fluid to the first pressure chamber urges the first
piston partially outward from the first pressure chamber to urge
rotation of the rotary output shaft in a first direction, wherein
application of pressurized fluid to the second pressure chamber
urges the first piston partially into the first pressure chamber to
urge rotation of the rotary output shaft in a second direction
opposite from the first direction.
8. The rotary actuator of claim 1, wherein the first seal is
disposed about an interior surface of the open end.
9. The rotary actuator of claim 1, wherein the first seal is
disposed about the periphery of the first piston.
10. The rotary actuator of claim 1, wherein the first seal provides
load bearing support for the first piston.
11. The rotary actuator of claim 1, wherein the first housing is
formed as a one-piece housing.
12. The rotary actuator of claim 1, wherein the first seal is a
one-piece seal.
13. The rotary actuator of claim 1, wherein the first piston is
solid in cross-section.
14. The rotary actuator of claim 1, wherein the first piston is at
least partly hollow in cross-section.
15. The rotary actuator of claim 14, wherein a structural member
inside the first piston is located between two cavities inside the
first piston.
16. The rotary actuator of claim 1, wherein the first piston has
one of a square, rectangular, ovoid, elliptical, or circular shape
in cross-section.
17. The rotary actuator of claim 2, the first housing further
defines a fluid port fluidically connecting the first cavity and
the second cavity.
18. The rotary actuator of claim 1, wherein the first arcuate
chamber defines at least a portion of an ellipse having a plane,
wherein a rotational axis of the output shaft is not perpendicular
to the plane.
19. A method of rotary actuation comprising: providing a rotary
actuator comprising: a first housing defining a first arcuate
chamber comprising a first cavity, a first fluid port in fluid
communication with the first cavity, and an open end; a rotor
assembly rotatably journaled in said first housing and comprising a
rotary output shaft and a first rotor arm extending radially
outward from the rotary output shaft; and an arcuate-shaped first
piston disposed in said first housing for reciprocal movement in
the first arcuate chamber through the open end, wherein a first
seal, the first cavity, and the first piston define a first
pressure chamber, and a first portion of the first piston contacts
the first rotor arm; applying pressurized fluid to the first
pressure chamber; urging the first piston partially outward from
the first pressure chamber to urge rotation of the rotary output
shaft in a first direction; rotating the rotary output shaft in a
second direction opposite that of the first direction; and, urging
the first piston partially into the first pressure chamber to urge
pressurized fluid out the first fluid port.
20. The method of claim 19, wherein the first housing further
defines a second arcuate chamber comprising a second cavity, and a
second fluid port in fluid communication with the second cavity;
the rotor assembly further comprises a second rotor arm; the rotary
actuator further comprising an arcuate-shaped second piston
disposed in said first housing for reciprocal movement in the
second arcuate chamber, wherein a second seal, the second cavity,
and the second piston define a second pressure chamber, and a first
portion of the second piston contacts the second rotor arm.
21. The method of claim 20, wherein the second piston is oriented
in the same rotational direction as the first piston.
22. The method of claim 20, wherein the second piston is oriented
in the opposite rotational direction as the first piston.
23. The method of claim 19, wherein the rotary actuator further
comprises a second housing disposed about the first housing and
having a second fluid port, wherein the first housing, the second
housing, the seal, and the first piston define a second pressure
chamber.
24. The method of claim 22, wherein rotating the rotary output
shaft in a second direction opposite that of the first direction
comprises: applying pressurized fluid to the second pressure
chamber; and urging the second piston partially outward from the
second pressure chamber to urge rotation of the rotary output shaft
in a second direction opposite from the first direction.
25. The method of claim 23, wherein rotating the rotary output
shaft in a second direction opposite that of the first direction
comprises: applying pressurized fluid to the second pressure
chamber; and urging the first piston partially into the first
pressure chamber to urge rotation of the rotary output shaft in a
second direction opposite from the first direction.
26. The method of claim 19, wherein urging the first piston
partially outward from the first pressure chamber to urge rotation
of the rotary output shaft in a first direction further comprises
rotating the output shaft in the first direction with substantially
constant torque over stroke.
27. The method of claim 19, wherein the first seal is disposed
about an interior surface of the open end.
28. The method of claim 20, wherein the second seal is disposed
about the periphery of the first piston.
29. The method of claim 19, wherein the first housing is formed as
a one-piece housing.
30. The method of claim 19, wherein the first seal is formed as a
one-piece seal.
31. The method of claim 19, wherein the first piston is solid in
cross-section.
32. The method of claim 19, wherein the first piston is at least
partly hollow in cross-section.
33. The method of claim 19, wherein the first piston has one of a
square, rectangular, ovoid, elliptical, or circular shape in
cross-section.
Description
TECHNICAL FIELD
[0001] This invention relates to an actuator device and more
particularly to a rotary piston type actuator device wherein the
pistons of the rotor are moved by fluid under pressure.
BACKGROUND
[0002] Rotary hydraulic actuators of various forms are currently
used in industrial mechanical power conversion applications. This
industrial usage is commonly for applications where continuous
inertial loading is desired without the need for load holding for
long durations, e.g. hours, without the use of an external fluid
power supply. Aircraft flight control applications generally
implement loaded positional holding, for example, in a failure
mitigation mode, using substantially only the blocked fluid column
to hold position.
[0003] In certain applications, such as primary flight controls
used for aircraft operation, positional accuracy in load holding by
rotary actuators is desired. Positional accuracy can be improved by
minimizing internal leakage characteristics inherent to the design
of rotary actuators. However, it can be difficult to provide
leak-free performance in typical rotary hydraulic actuators, e.g.,
rotary "vane" or rotary "piston" type configurations.
SUMMARY
[0004] In general, this document relates to rotary piston-type
actuators.
[0005] In a first aspect, rotary actuator includes a first housing
defining a first arcuate chamber having a first cavity, a first
fluid port in fluid communication with the first cavity, and an
open end. A rotor assembly is rotatably journaled in the first
housing and having a rotary output shaft and a first rotor arm
extending radially outward from the rotary output shaft. An
arcuate-shaped first piston is disposed in the first housing for
reciprocal movement in the first arcuate chamber through the open
end, wherein a first seal, the first cavity, and the first piston
define a first pressure chamber, and a first portion of the first
piston contacts the first rotor arm.
[0006] Various implementations may include some, all, or none of
the following features. The first housing may further define a
second arcuate chamber comprising a second cavity and a second
fluid port in fluid communication with the second cavity, the rotor
assembly may further include a second rotor arm, the rotary
actuator may further include an arcuate-shaped second piston
disposed in said first housing for reciprocal movement in the
second arcuate chamber, wherein a second seal, the second cavity,
and the second piston define a second pressure chamber, and a first
portion of the second piston contacts the second rotor arm. The
second piston can be oriented in the same rotational direction as
the first piston. The second piston can be oriented in the opposite
rotational direction as the first piston. Application of
pressurized fluid to the first pressure chamber can urge the first
piston partially outward from the first pressure chamber to urge
rotation of the rotary output shaft in a first direction, and
rotation of the rotary output shaft in a second direction opposite
that of the first direction can urge the first piston partially
into the first pressure chamber to urge pressurized fluid out the
first fluid port. The rotary actuator can include a second housing
disposed about the first housing and having a second fluid port,
wherein the first housing, the second housing, the seal, and the
first piston define a second pressure chamber. Application of
pressurized fluid to the first pressure chamber can urge the first
piston partially outward from the first pressure chamber to urge
rotation of the rotary output shaft in a first direction, and
application of pressurized fluid to the second pressure chamber can
urge the first piston partially into the first pressure chamber to
urge rotation of the rotary output shaft in a second direction
opposite from the first direction. The first seal can be disposed
about an interior surface of the open end. The first seal can be
disposed about the periphery of the first piston. The seal can
provide load bearing support for the first piston. The first
housing can be formed as a one-piece housing. The first seal can be
a one-piece seal. The first piston can be solid in cross-section.
The first piston can be at least partly hollow in cross-section. A
structural member inside the first piston can be located between
two cavities inside the first piston. The first piston can have one
of a square, rectangular, ovoid, elliptical, or circular shape in
cross-section. The first housing can further define a fluid port
fluidically connecting the first cavity and the second cavity. The
first arcuate chamber can define at least a portion of an ellipse
having a plane, wherein a rotational axis of the output shaft is
not perpendicular to the plane.
[0007] In a second aspect, method of rotary actuation includes
providing a rotary actuator having a first housing defining a first
arcuate chamber comprising a first cavity, a first fluid port in
fluid communication with the first cavity, and an open end, a rotor
assembly rotatably journaled in said first housing and comprising a
rotary output shaft and a first rotor arm extending radially
outward from the rotary output shaft, and an arcuate-shaped first
piston disposed in said first housing for reciprocal movement in
the first arcuate chamber through the open end, wherein a first
seal, the first cavity, and the first piston define a first
pressure chamber, and a first portion of the first piston contacts
the first rotor arm. Pressurized fluid is applied to the first
pressure chamber, urging the first piston partially outward from
the first pressure chamber to urge rotation of the rotary output
shaft in a first direction. Rotating the rotary output shaft in a
second direction opposite that of the first direction urges the
first piston partially into the first pressure chamber to urge
pressurized fluid out the first fluid port.
[0008] Various implementations can include some, all, or none of
the following features. The first housing can further define a
second arcuate chamber having a second cavity and a second fluid
port in fluid communication with the second cavity, the rotor
assembly can further include a second rotor arm, the rotary
actuator can further include an arcuate-shaped second piston
disposed in said first housing for reciprocal movement in the
second arcuate chamber, wherein a second seal, the second cavity,
and the second piston define a second pressure chamber, and a first
portion of the second piston contacts the second rotor arm. The
second piston can be oriented in the same rotational direction as
the first piston. The second piston can be oriented in the opposite
rotational direction as the first piston. The rotary actuator can
further include a second housing disposed about the first housing
and having a second fluid port, wherein the first housing, the
second housing, the seal, and the first piston define a second
pressure chamber. Rotating the rotary output shaft in a second
direction opposite that of the first direction can include applying
pressurized fluid to the second pressure chamber, and urging the
second piston partially outward from the second pressure chamber to
urge rotation of the rotary output shaft in a second direction
opposite from the first direction. Rotating the rotary output shaft
in a second direction opposite that of the first direction can
include applying pressurized fluid to the second pressure chamber,
and urging the first piston partially into the first pressure
chamber to urge rotation of the rotary output shaft in a second
direction opposite from the first direction. Urging the first
piston partially outward from the first pressure chamber to urge
rotation of the rotary output shaft in a first direction can
further include rotating the output shaft in the first direction
with substantially constant torque over stroke. The first seal can
be disposed about an interior surface of the open end. The second
seal can be disposed about the periphery of the first piston. The
first housing can be formed as a one-piece housing. The first seal
can be formed as a one-piece seal. The first piston can be solid in
cross-section. The first piston can be at least partly hollow in
cross-section. The first piston can have one of a square,
rectangular, ovoid, elliptical, or circular shape in
cross-section.
[0009] The systems and techniques described herein may provide one
or more of the following advantages. First, a system can provide
performance characteristics generally associated with linear fluid
actuators in a compact and lightweight package more generally
associated with rotary fluid actuators. Second, the system can
substantially maintain a selected rotational position while under
load by blocking the supply of fluids to and/or from the actuator.
Third, the system can use commercially available seal assemblies
originally intended for use in linear fluid actuator applications.
Fourth, the system can provide rotary actuation with substantially
constant torque over stroke.
[0010] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other features
and advantages will be apparent from the description and drawings,
and from the claims.
DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a perspective view of an example rotary
piston-type actuator.
[0012] FIG. 2 is a perspective view of an example rotary piston
assembly.
[0013] FIG. 3 is a perspective cross-sectional view of an example
rotary piston-type actuator.
[0014] FIG. 4 is a perspective view of another example rotary
piston-type actuator.
[0015] FIGS. 5 and 6 are cross-sectional views of an example rotary
piston-type actuator.
[0016] FIG. 7 is a perspective view of another embodiment of a
rotary piston-type actuator.
[0017] FIG. 8 is a perspective view of another example of a rotary
piston-type actuator.
[0018] FIGS. 9 and 10 show and example rotary piston-type actuator
in example extended and retracted configurations.
[0019] FIG. 11 is a perspective view of another example of a rotary
piston-type actuator.
[0020] FIGS. 12-14 are perspective and cross-sectional views of
another example rotary piston-type actuator.
[0021] FIGS. 15 and 16 are perspective and cross-sectional views of
another example rotary piston-type actuator that includes another
example rotary piston assembly.
[0022] FIGS. 17 and 18 are perspective and cross-sectional views of
another example rotary piston-type actuator that includes another
example rotary piston assembly.
[0023] FIGS. 19 and 20 are perspective and cross-sectional views of
another example rotary piston-type actuator.
[0024] FIGS. 21A-21C are cross-sectional and perspective views of
an example rotary piston.
[0025] FIGS. 22 and 23 illustrate a comparison of two example rotor
shaft embodiments.
[0026] FIG. 24 is a perspective view of another example rotary
piston.
[0027] FIG. 25 is a flow diagram of an example process for
performing rotary actuation.
[0028] FIG. 26 is a perspective view of another example rotary
piston-type actuator.
[0029] FIG. 27 is a cross-sectional view of another example rotary
piston assembly.
[0030] FIG. 28 is a perspective cross-sectional view of another
example rotary piston-type actuator.
DETAILED DESCRIPTION
[0031] This document describes devices for producing rotary motion.
In particular, this document describes devices that can convert
fluid displacement into rotary motion through the use of components
more commonly used for producing linear motion, e.g., hydraulic or
pneumatic linear cylinders. Vane-type rotary actuators are
relatively compact devices used to convert fluid motion into rotary
motion. Rotary vane actuators (RVA), however, generally use seals
and component configurations that exhibit cross-vane leakage of the
driving fluid. Such leakage can affect the range of applications in
which such designs can be used. Some applications may require a
rotary actuator to hold a rotational load in a selected position
for a predetermined length of time, substantially without
rotational movement, when the actuator's fluid ports are blocked.
For example, some aircraft applications may require that an
actuator hold a flap or other control surface that is under load
(e.g., through wind resistance, gravity or g-forces) at a selected
position when the actuator's fluid ports are blocked. Cross-vane
leakage, however, can allow movement from the selected
position.
[0032] Linear pistons use relatively mature sealing technology that
exhibits well-understood dynamic operation and leakage
characteristics that are generally better than rotary vane actuator
type seals. Linear pistons, however, require additional mechanical
components in order to adapt their linear motions to rotary
motions. Such linear-to-rotary mechanisms are generally larger and
heavier than rotary vane actuators that are capable of providing
similar rotational actions, e.g., occupying a larger work envelope.
Such linear-to-rotary mechanisms may also generally be installed in
an orientation that is different from that of the load they are
intended to drive, and therefore may provide their torque output
indirectly, e.g., installed to push or pull a lever arm that is at
a generally right angle to the axis of the axis of rotation of the
lever arm. Such linear-to-rotary mechanisms may therefore become
too large or heavy for use in some applications, such as aircraft
control where space and weight constraints may make such mechanisms
impractical for use.
[0033] In general, rotary piston assemblies use curved pressure
chambers and curved pistons to controllably push and pull the rotor
arms of a rotor assembly about an axis. In use, certain embodiments
of the rotary piston assemblies described herein can provide the
positional holding characteristics generally associated with linear
piston-type fluid actuators, to rotary applications, and can do so
using the relatively more compact and lightweight envelopes
generally associated with rotary vane actuators.
[0034] FIGS. 1-3 show various views of the components of an example
rotary piston-type actuator 100. Referring to FIG. 1, a perspective
view of the example rotary piston-type actuator 100 is shown. The
actuator 100 includes a rotary piston assembly 200 and a pressure
chamber assembly 300. The actuator 100 includes a first actuation
section 110 and a second actuation section 120. In the example of
actuator 100, the first actuation section 110 is configured to
rotate the rotary piston assembly 200 in a first direction, e.g.,
counter-clockwise, and the second actuation section 120 is
configured to rotate the rotary piston assembly 200 in a second
direction substantially opposite the first direction, e.g.,
clockwise.
[0035] Referring now to FIG. 2, a perspective view of the example
rotary piston assembly 200 is shown apart from the pressure chamber
assembly 300. The rotary piston assembly 200 includes a rotor shaft
210. A plurality of rotor arms 212 extend radially from the rotor
shaft 210, the distal end of each rotor arm 212 including a bore
(not shown) substantially aligned with the axis of the rotor shaft
210 and sized to accommodate one of the collection of connector
pins 214.
[0036] As shown in FIG. 2, the first actuation section 110 includes
a pair of rotary pistons 250, and the second actuation section 120
includes a pair of rotary pistons 260. While the example actuator
100 includes two pairs of the rotary pistons 250, 260, other
embodiments can include greater and/or lesser numbers of
cooperative and opposing rotary pistons. Examples of other such
embodiments will be discussed below, for example, in the
descriptions of FIGS. 4-25.
[0037] In the example rotary piston assembly shown in FIG. 2, each
of the rotary pistons 250, 260 includes a piston end 252 and one or
more connector arms 254. The piston end 252 is formed to have a
generally semi-circular body having a substantially smooth surface.
Each of the connector arms 254 includes a bore 256 substantially
aligned with the axis of the semi-circular body of the piston end
252 and sized to accommodate one of the connector pins 214.
[0038] The rotary pistons 260 in the example assembly of FIG. 2 are
oriented substantially opposite each other in the same rotational
direction. The rotary pistons 250 are oriented substantially
opposite each other in the same rotational direction, but opposite
that of the rotary pistons 260. In some embodiments, the actuator
100 can rotate the rotor shaft 210 about 60 degrees total.
[0039] Each of the rotary pistons 250, 260 of the example assembly
of FIG. 2 may be assembled to the rotor shaft 210 by aligning the
connector arms 254 with the rotor arms 212 such that the bores (not
shown) of the rotor arms 212 align with the bores 265. The
connector pins 214 may then be inserted through the aligned bores
to create hinged connections between the pistons 250, 260 and the
rotor shaft 210. Each connector pin 214 is slightly longer than the
aligned bores. In the example assembly, about the circumferential
periphery of each end of each connector pin 214 that extends beyond
the aligned bores is a circumferential recess (not shown) that can
accommodate a retaining fastener (not shown), e.g., a snap ring or
spiral ring.
[0040] FIG. 3 is a perspective cross-sectional view of the example
rotary piston-type actuator 100. The illustrated example shows the
rotary pistons 260 inserted into a corresponding pressure chamber
310 formed as an arcuate cavity in the pressure chamber assembly
300. The rotary pistons 250 are also inserted into corresponding
pressure chambers 310, not visible in this view.
[0041] In the example actuator 100, each pressure chamber 310
includes a seal assembly 320 about the interior surface of the
pressure chamber 310 at an open end 330. In some implementations,
the seal assembly 320 can be a circular or semi-circular sealing
geometry retained on all sides in a standard seal groove. In some
implementations, commercially available reciprocating piston or
cylinder type seals can be used. For example, commercially
available seal types that may already be in use for linear
hydraulic actuators flying on current aircraft may demonstrate
sufficient capability for linear load and position holding
applications. In some implementations, the sealing complexity of
the actuator 100 may be reduced by using a standard, e.g.,
commercially available, semi-circular, unidirectional seal designs
generally used in linear hydraulic actuators. In some embodiments,
the seal assembly 320 can be a one-piece seal.
[0042] In some embodiments of the example actuator 100, the seal
assembly 320 may be included as part of the rotary pistons 250,
260. For example, the seal assembly 320 may be located near the
piston end 252, opposite the connector arm 254, and slide along the
interior surface of the pressure chamber 310 to form a fluidic seal
as the rotary piston 250, 260 moves in and out of the pressure
chamber 310. An example actuator that uses such piston-mounted seal
assemblies will be discussed in the descriptions of FIGS. 26-28. In
some embodiments, the seal 310 can act as a bearing. For example,
the seal assembly 320 may provide support for the piston 250, 260
as it moves in and out of the pressure chamber 310.
[0043] In some embodiments, the actuator 100 may include a wear
member between the piston 250, 260 and the pressure chamber 310.
For example, a wear ring may be included in proximity to the seal
assembly 320. The wear ring may act as a pilot for the piston 250,
260, and/or act as a bearing providing support for the piston 250,
260.
[0044] In the example actuator 100, when the rotary pistons 250,
260 are inserted through the open ends 330, each of the seal
assemblies 320 contacts the interior surface of the pressure
chamber 310 and the substantially smooth surface of the piston end
252 to form a substantially pressure-sealed region within the
pressure chamber 310. Each of the pressure chambers 310 may include
a fluid port 312 formed through the pressure chamber assembly 300,
through with pressurized fluid may flow. Upon introduction of
pressurized fluid, e.g., hydraulic oil, water, air, gas, into the
pressure chambers 310, the pressure differential between the
interior of the pressure chambers 310 and the ambient conditions
outside the pressure chambers 310 causes the piston ends 252 to be
urged outward from the pressure chambers 310. As the piston ends
252 are urged outward, the pistons 250, 260 urge the rotary piston
assembly 200 to rotate.
[0045] In the example of the actuator 100, cooperative pressure
chambers may be fluidically connected by internal or external fluid
ports. For example, the pressure chambers 310 of the first
actuation section 110 may be fluidically interconnected to balance
the pressure between the pressure chambers 310. Similarly the
pressure chambers 310 of the second actuation section 120 may be
fluidically interconnected to provide similar pressure balancing.
In some embodiments, the pressure chambers 310 may be fluidically
isolated from each other. For example, the pressure chambers 310
may each be fed by an independent supply of pressurized fluid.
[0046] In the example of the actuator 100, the use of the
alternating arcuate, e.g., curved, rotary pistons 250, 260 arranged
substantially opposing each other operates to translate the rotor
arms in an arc-shaped path about the axis of the rotary piston
assembly 200, thereby rotating the rotor shaft 210 clockwise and
counter-clockwise in a substantially torque balanced arrangement.
Each cooperative pair of pressure chambers 310 operates
uni-directionally in pushing the respective rotary piston 250
outward, e.g., extension, to drive the rotor shaft 210 in the
specific direction. To reverse direction, the opposing cylinder
section's 110 pressure chambers 260 are pressurized to extend their
corresponding rotary pistons 260 outward.
[0047] The pressure chamber assembly 300, as shown, includes a
collection of openings 350. In general, the openings 350 provide
space in which the rotor arms 212 can move when the rotor shaft 210
is partly rotated. In some implementations, the openings 350 can be
formed to remove material from the pressure chamber assembly 300,
e.g., to reduce the mass of the pressure chamber assembly 300. In
some implementations, the openings 350 can be used during the
process of assembly of the actuator 100. For example, the actuator
100 can be assembled by inserting the rotary pistons 250, 260
through the openings 350 such that the piston ends 252 are inserted
into the pressure chambers 310. With the rotary pistons 250, 260
substantially fully inserted into the pressure chambers 310, the
rotor shaft 210 can be assembled to the actuator 100 by aligning
the rotor shaft 210 with an axial bore 360 formed along the axis of
the pressure chamber assembly 300, and by aligning the rotor arms
212 with a collection of keyways 362 formed along the axis of the
pressure chamber assembly 300. The rotor shaft 210 can then be
inserted into the pressure chamber assembly 300. The rotary pistons
250, 260 can be partly extracted from the pressure chambers 310 to
substantially align the bores 256 with the bores of the rotor arms
212. The connector pins 214 can then be passed through the keyways
362 and the aligned bores to connect the rotary pistons 250, 260 to
the rotor shaft 210. The connector pins 214 can be secured
longitudinally by inserting retaining fasteners through the
openings 350 and about the ends of the connector pins 214. The
rotor shaft 210 can be connected to an external mechanism as an
output shaft in order to transfer the rotary motion of the actuator
100 to other mechanisms. A bushing or bearing 362 is fitted between
the rotor shaft 210 and the axial bore 360 at each end of the
pressure chamber assembly 300.
[0048] In some embodiments, the rotary pistons 250, 260 may urge
rotation of the rotor shaft 210 by contacting the rotor arms 212.
For example, the piston ends 252 may not be coupled to the rotor
arms 212. Instead, the piston ends 252 may contact the rotor arms
212 to urge rotation of the rotor shaft as the rotary pistons 250,
260 are urged outward from the pressure chambers 310. Conversely,
the rotor arms 212 may contact the piston ends 252 to urge the
rotary pistons 250, 260 back into the pressure chambers 310.
[0049] In some embodiments, a rotary position sensor assembly (not
shown) may be included in the actuator 100. For example, an encoder
may be used to sense the rotational position of the rotor shaft 210
relative to the pressure chamber assembly or another feature that
remains substantially stationary relative to the rotation of the
shaft 210. In some implementations, the rotary position sensor may
provide signals that indicate the position of the rotor shaft 210
to other electronic or mechanical modules, e.g., a position
controller.
[0050] In use, pressurized fluid in the example actuator 100 can be
applied to the pressure chambers 310 of the second actuation
section 120 through the fluid ports 312. The fluid pressure urges
the rotary pistons 260 out of the pressure chambers 310. This
movement urges the rotary piston assembly 200 to rotate clockwise.
Pressurized fluid can be applied to the pressure chambers 310 of
the first actuation section 110 through the fluid ports 312. The
fluid pressure urges the rotary pistons 250 out of the pressure
chambers 310. This movement urges the rotary piston assembly 200 to
rotate counter-clockwise. The fluid conduits can also be blocked
fluidically to cause the rotary piston assembly 200 to
substantially maintain its rotary position relative to the pressure
chamber assembly 300.
[0051] In some embodiments of the example actuator 100, the
pressure chamber assembly 300 can be formed from a single piece of
material. For example, the pressure chambers 310, the openings 350,
the fluid ports 312, the keyways 362, and the axial bore 360 may be
formed by molding, machining, or otherwise forming a unitary piece
of material.
[0052] FIG. 4 is a perspective view of another example rotary
piston-type actuator 400. In general, the actuator 400 is similar
to the actuator 100, but instead of using opposing pairs of rotary
pistons 250, 260, each acting uni-directionally to provide
clockwise and counter-clockwise rotation, the actuator 400 uses a
pair of bidirectional rotary pistons.
[0053] As shown in FIG. 4, the actuator 400 includes a rotary
piston assembly that includes a rotor shaft 412 and a pair of
rotary pistons 414. The rotor shaft 412 and the rotary pistons 414
are connected by a pair of connector pins 416.
[0054] The example actuator shown in FIG. 4 includes a pressure
chamber assembly 420. The pressure chamber assembly 420 includes a
pair of pressure chambers 422 formed as arcuate cavities in the
pressure chamber assembly 420. Each pressure chamber 422 includes a
seal assembly 424 about the interior surface of the pressure
chamber 422 at an open end 426. The seal assemblies 424 contact the
inner walls of the pressure chambers 422 and the rotary pistons 414
to form fluidic seals between the interiors of the pressure
chambers 422 and the space outside. A pair of fluid ports 428 is in
fluidic communication with the pressure chambers 422. In use,
pressurized fluid can be applied to the fluid ports 428 to urge the
rotary pistons 414 partly out of the pressure chambers 422, and to
urge the rotor shaft 412 to rotate in a first direction, e.g.,
clockwise in this example.
[0055] The pressure chamber assembly 420 and the rotor shaft 412
and rotary pistons 414 of the rotary piston assembly may be
structurally similar to corresponding components found in to the
second actuation section 120 of the actuator 100. In use, the
example actuator 400 also functions substantially similarly to the
actuator 100 when rotating in a first direction when the rotary
pistons 414 are being urged outward from the pressure chambers 422.
e.g., clockwise in this example. As will be discussed next, the
actuator 400 differs from the actuator 100 in the way that the
rotor shaft 412 is made to rotate in a second direction, e.g.,
counter-clockwise in this example.
[0056] To provide actuation in the second direction, the example
actuator 400 includes an outer housing 450 with a bore 452. The
pressure chamber assembly 420 is formed to fit within the bore 452.
The bore 452 is fluidically sealed by a pair of end caps (not
shown). With the end caps in place, the bore 452 becomes a
pressurizable chamber. Pressurized fluid can flow to and from the
bore 452 through a fluid port 454. Pressurized fluid in the bore
452 is separated from fluid in the pressure chambers 422 by the
seals 426.
[0057] Referring now to FIG. 5, the example actuator 400 is shown
in a first configuration in which the rotor shaft 412 has been
rotated in a first direction, e.g., clockwise, as indicated by the
arrows 501. The rotor shaft 412 can be rotated in the first
direction by flowing pressurized fluid into the pressure chambers
422 through the fluid ports 428, as indicated by the arrows 502.
The pressure within the pressure chambers 422 urges the rotary
pistons 414 partly outward from the pressure chambers 422 and into
the bore 452. Fluid within the bore 452, separated from the fluid
within the pressure chambers 422 by the seals 424 and displaced by
the movement of the rotary pistons 414, is urged to flow out the
fluid port 454, as indicated by the arrow 503.
[0058] Referring now to FIG. 6, the example actuator 400 is shown
in a second configuration in which the rotor shaft 412 has been
rotated in a second direction, e.g., counter-clockwise, as
indicated by the arrows 601. The rotor shaft 412 can be rotated in
the second direction by flowing pressurized fluid into the bore 452
through the fluid port 454, as indicated by the arrow 602. The
pressure within the bore 452 urges the rotary pistons 414 partly
into the pressure chambers 422 from the bore 452. Fluid within the
pressure chambers 422, separated from the fluid within the bore 452
by the seals 424 and displaced by the movement of the rotary
pistons 414, is urged to flow out the fluid ports 428, as indicated
by the arrows 603. In some embodiments, one or more of the fluid
ports 428 and 454 can be oriented radially relative to the axis of
the actuator 400, as illustrated in FIGS. 4-6, however in some
embodiments one or more of the fluid ports 428 and 454 can be
oriented parallel to the axis of the actuator 400 or in any other
appropriate orientation.
[0059] FIG. 7 is a perspective view of another embodiment of a
rotary piston assembly 700. In the example actuator 100 of FIG. 1,
two opposing pairs of rotary pistons were used, but in other
embodiments other numbers and configurations of rotary pistons and
pressure chambers can be used. In the example of the assembly 700,
a first actuation section 710 includes four rotary pistons 712
cooperatively operable to urge a rotor shaft 701 in a first
direction. A second actuation section 720 includes four rotary
pistons 722 cooperatively operable to urge the rotor shaft 701 in a
second direction.
[0060] Although examples using four rotary pistons, e.g., actuator
100, and eight rotary pistons, e.g., assembly 700, have been
described, other configurations may exist.
[0061] In some embodiments, any appropriate number of rotary
pistons may be used in cooperation and/or opposition. In some
embodiments, opposing rotary pistons may not be segregated into
separate actuation sections, e.g., the actuation sections 710 and
720. While cooperative pairs of rotary pistons are used in the
examples of actuators 100, 400, and assembly 700, other embodiments
exist. For example, clusters of two, three, four, or more
cooperative or oppositional rotary pistons and pressure chambers
may be arranged radially about a section of a rotor shaft. As will
be discussed in the descriptions of FIGS. 8-10, a single rotary
piston may be located at a section of a rotor shaft. In some
embodiments, cooperative rotary pistons may be interspersed
alternatingly with opposing rotary pistons. For example, the rotary
pistons 712 may alternate with the rotary pistons 722 along the
rotor shaft 701.
[0062] FIG. 8 is a perspective view of another example of a rotary
piston-type actuator 800. The actuator 800 differs from the example
actuators 100 and 400, and the example assembly 700 in that instead
of implementing cooperative pairs of rotary pistons along a rotor
shaft, e.g., two of the rotary pistons 250 are located radially
about the rotor shaft 210, individual rotary pistons are located
along a rotor shaft.
[0063] The example actuator 800 includes a rotor shaft 810 and a
pressure chamber assembly 820. The actuator 800 includes a first
actuation section 801 and a second actuation section 802. In the
example actuator 800, the first actuation section 801 is configured
to rotate the rotor shaft 810 in a first direction, e.g.,
clockwise, and the second actuation section 802 is configured to
rotate the rotor shaft 810 in a second direction substantially
opposite the first direction, e.g., counter-clockwise.
[0064] The first actuation section 801 of example actuator 800
includes a rotary piston 812, and the second actuation section 802
includes a rotary piston 822. By implementing a single rotary
piston 812, 822 at a given longitudinal position along the rotor
shaft 810, a relatively greater range of rotary travel may be
achieved compared to actuators that use pairs of rotary pistons at
a given longitudinal position along the rotary piston assembly,
e.g., the actuator 100. In some embodiments, the actuator 800 can
rotate the rotor shaft 810 about 145 degrees total.
[0065] In some embodiments, the use of multiple rotary pistons 812,
822 along the rotor shaft 810 can reduce distortion of the pressure
chamber assembly 820, e.g., reduce bowing out under high pressure.
In some embodiments, the use of multiple rotary pistons 812, 822
along the rotor shaft 810 can provide additional degrees of freedom
for each piston 812, 822. In some embodiments, the use of multiple
rotary pistons 812, 822 along the rotor shaft 810 can reduce
alignment issues encountered during assembly or operation. In some
embodiments, the use of multiple rotary pistons 812, 822 along the
rotor shaft 810 can reduce the effects of side loading of the rotor
shaft 810.
[0066] FIG. 9 shows the example actuator 800 with the rotary piston
812 in a substantially extended configuration. A pressurized fluid
is applied to a fluid port 830 to pressurize an arcuate pressure
chamber 840 formed in the pressure chamber assembly 820. Pressure
in the pressure chamber 840 urges the rotary piston 812 partly
outward, urging the rotor shaft 810 to rotate in a first direction,
e.g., clockwise.
[0067] FIG. 10 shows the example actuator 800 with the rotary
piston 812 in a substantially retracted configuration. Mechanical
rotation of the rotor shaft 810, e.g., pressurization of the
actuation section 820, urges the rotary piston 812 partly inward,
e.g., clockwise. Fluid in the pressure chamber 840 displaced by the
rotary piston 812 flows out through the fluid port 830.
[0068] The example actuator 800 can be assembled by inserting the
rotary piston 812 into the pressure chamber 840. Then the rotor
shaft 810 can be inserted longitudinally through a bore 850 and a
keyway 851. The rotary piston 812 is connected to the rotor shaft
810 by a connecting pin 852.
[0069] FIG. 11 is a perspective view of another example of a rotary
piston-type actuator 1100. In general, the actuator 1100 is similar
to the example actuator 800, except multiple rotary pistons are
used in each actuation section.
[0070] The example actuator 1100 includes a rotary piston assembly
1110 and a pressure chamber assembly 1120. The actuator 1100
includes a first actuation section 1101 and a second actuation
section 1102. In the example of actuator 1100, the first actuation
section 1101 is configured to rotate the rotary piston assembly
1110 in a first direction, e.g., clockwise, and the second
actuation section 1102 is configured to rotate the rotary piston
assembly 1110 in a second direction substantially opposite the
first direction, e.g., counter-clockwise.
[0071] The first actuation section 1101 of example actuator 1100
includes a collection of rotary pistons 812, and the second
actuation section 1102 includes a collection of rotary pistons 822.
By implementing individual rotary pistons 812, 822 at various
longitudinal positions along the rotary piston assembly 1110, a
range of rotary travel similar to the actuator 800 may be achieved.
In some embodiments, the actuator 1100 can rotate the rotor shaft
1110 about 60 degrees total.
[0072] In some embodiments, the use of the collection of rotary
pistons 812 may provide mechanical advantages in some applications.
For example, the use of multiple rotary pistons 812 may reduce
stress or deflection of the rotary piston assembly, may reduce wear
of the seal assemblies, or may provide more degrees of freedom. In
another example, providing partitions, e.g., webbing, between
chambers can add strength to the pressure chamber assembly 1120 and
can reduce bowing out of the pressure chamber assembly 1120 under
high pressure. In some embodiments, placement of an end tab on the
rotor shaft assembly 1110 can reduce cantilever effects experienced
by the actuator 800 while under load, e.g., less stress or
bending.
[0073] FIGS. 12-14 are perspective and cross-sectional views of
another example rotary piston-type actuator 1200. The actuator 1200
includes a rotary piston assembly 1210, a first actuation section
1201, and a second actuation section 1202.
[0074] The rotary piston assembly 1210 of example actuator 1200
includes a rotor shaft 1212, a collection of rotor arms 1214, and a
collection of dual rotary pistons 1216. Each of the dual rotary
pistons 1216 includes a connector section 1218 a piston end 1220a
and a piston end 1220b. The piston ends 1220a-1220b are arcuate in
shape, and are oriented opposite to each other in a generally
semicircular arrangement, and are joined at the connector section
1218. A bore 1222 is formed in the connector section 1218 and is
oriented substantially parallel to the axis of the semicircle
formed by the piston ends 1220a-1220b. The bore 1222 is sized to
accommodate a connector pin (not shown) that is passed through the
bore 1222 and a collection of bores 1224 formed in the rotor arms
1213 to secure each of the dual rotary pistons 1216 to the rotor
shaft 1212.
[0075] The first actuation section 1201 of example actuator 1200
includes a first pressure chamber assembly 1250a, and the second
actuation section 1202 includes a second pressure chamber assembly
1250b. The first pressure chamber assembly 1250a includes a
collection of pressure chambers 1252a formed as arcuate cavities in
the first pressure chamber assembly 1250a. The second pressure
chamber assembly 1250b includes a collection of pressure chambers
1252b formed as arcuate cavities in the first pressure chamber
assembly 1250b. When the pressure chamber assemblies 1250a-1250b
are assembled into the actuator 1200, each of the pressure chambers
1252a lies generally in a plane with a corresponding one of the
pressure chambers 1252b, such that a pressure chamber 1252a and a
pressure chamber 1252b occupy two semicircular regions about a
central axis. A semicircular bore 1253a and a semicircular bore
1253b substantially align to accommodate the rotor shaft 1212.
[0076] Each of the pressure chambers 1252a-1252b of example
actuator 1200 includes an open end 1254 and a seal assembly 1256.
The open ends 1254 are formed to accommodate the insertion of the
piston ends 1220a-1220b. The seal assemblies 1256 contact the inner
walls of the pressure chambers 1252a-1252b and the outer surfaces
of the piston ends 1220a-1220b to form a fluidic seal.
[0077] The rotary piston assembly 1210 of example actuator 1200 can
be assembled by aligning the bores 1222 of the dual rotary pistons
1216 with the bores 1224 of the rotor arms 1214. The connector pin
(not shown) is passed through the bores 1222 and 1224 and secured
longitudinally by retaining fasteners.
[0078] The example actuator 1200 can be assembled by positioning
the rotor shaft 1212 substantially adjacent to the semicircular
bore 1253a and rotating it to insert the piston ends 1220a
substantially fully into the pressure chambers 1252a. The second
pressure chamber 1252b is positioned adjacent to the first pressure
chamber 1252a such that the semicircular bore 1253b is positioned
substantially adjacent to the rotor shaft 1212. The rotary piston
assembly 1210 is then rotated to partly insert the piston ends
1220b into the pressure chambers 1252b. An end cap 1260 is fastened
to the longitudinal ends 1262a of the pressure chambers
1252a-1252b. A second end cap (not shown) is fastened to the
longitudinal ends 1262b of the pressure chambers 1252a-1252b. The
end caps substantially maintain the positions of the rotary piston
assembly 1210 and the pressure chambers 1252a-1252b relative to
each other. In some embodiments, the actuator 1200 can provide
about 90 degrees of total rotational stroke.
[0079] In operation, pressurized fluid is applied to the pressure
chambers 1252a of example actuator 1200 to rotate the rotary piston
assembly 1210 in a first direction, e.g., clockwise. Pressurized
fluid is applied to the pressure chambers 1252b to rotate the
rotary piston assembly 1210 in a second direction, e.g.,
counter-clockwise.
[0080] FIGS. 15 and 16 are perspective and cross-sectional views of
another example rotary piston-type actuator 1500 that includes
another example rotary piston assembly 1501. In some embodiments,
the assembly 1501 can be an alternative embodiment of the rotary
piston assembly 200 of FIG. 2.
[0081] The assembly 1501 of example actuator 1500 includes a rotor
shaft 1510 connected to a collection of rotary pistons 1520a and a
collection of rotary pistons 1520b by a collection of rotor arms
1530 and one or more connector pins (not shown). The rotary pistons
1520a and 1520b are arranged along the rotor shaft 1510 in a
generally alternating pattern, e.g., one rotary piston 1520a, one
rotary piston 1520b, one rotary piston 1520a, one rotary piston
1520b. In some embodiments, the rotary pistons 1520a and 1520b may
be arranged along the rotor shaft 1510 in a generally intermeshed
pattern, e.g., one rotary piston 1520a and one rotary piston 1520b
rotationally parallel to each other, with connector portions formed
to be arranged side-by-side or with the connector portion of rotary
piston 1520a formed to one or more male protrusions and/or one or
more female recesses to accommodate one or more corresponding male
protrusions and/or one or more corresponding female recesses formed
in the connector portion of the rotary piston 1520b.
[0082] Referring to FIG. 16, a pressure chamber assembly 1550 of
example actuator 1500 includes a collection of arcuate pressure
chambers 1555a and a collection of arcuate pressure chambers 1555b.
The pressure chambers 1555a and 1555b are arranged in a generally
alternating pattern corresponding to the alternating pattern of the
rotary pistons 1520a-1520b. The rotary pistons 1520a-1520b extend
partly into the pressure chambers 1555a-1555b. A seal assembly 1560
is positioned about an open end 1565 of each of the pressure
chambers 1555a-1555b to form fluidic seals between the inner walls
of the pressure chambers 1555a-1555b and the rotary pistons
1520a-1520b.
[0083] In use, pressurized fluid can be alternatingly provided to
the pressure chambers 1555a and 1555b of example actuator 1500 to
urge the rotary piston assembly 1501 to rotate partly clockwise and
counterclockwise. In some embodiments, the actuator 1500 can rotate
the rotor shaft 1510 about 92 degrees total.
[0084] FIGS. 17 and 18 are perspective and cross-sectional views of
another example rotary piston-type actuator 1700 that includes
another example rotary piston assembly 1701. In some embodiments,
the assembly 1701 can be an alternative embodiment of the rotary
piston assembly 200 of FIG. 2 or the assembly 1200 of FIG. 12.
[0085] The assembly 1701 of example actuator 1700 includes a rotor
shaft 1710 connected to a collection of rotary pistons 1720a by a
collection of rotor arms 1730a and one or more connector pins 1732.
The rotor shaft 1710 is also connected to a collection of rotary
pistons 1720b by a collection of rotor arms 1730b and one or more
connector pins 1732. The rotary pistons 1720a and 1720b are
arranged along the rotor shaft 1710 in a generally opposing,
symmetrical pattern, e.g., one rotary piston 1720a is paired with
one rotary piston 1720b at various positions along the length of
the assembly 1701.
[0086] Referring to FIG. 18, a pressure chamber assembly 1750 of
example actuator 1700 includes a collection of arcuate pressure
chambers 1755a and a collection of arcuate pressure chambers 1755b.
The pressure chambers 1755a and 1755b are arranged in a generally
opposing, symmetrical pattern corresponding to the symmetrical
arrangement of the rotary pistons 1720a-1720b. The rotary pistons
1720a-1720b extend partly into the pressure chambers 1755a-1755b. A
seal assembly 1760 is positioned about an open end 1765 of each of
the pressure chambers 1755a-1755b to form fluidic seals between the
inner walls of the pressure chambers 1755a-1755b and the rotary
pistons 1720a-1720b.
[0087] In use, pressurized fluid can be alternatingly provided to
the pressure chambers 1755a and 1755b of example actuator 1700 to
urge the rotary piston assembly 1701 to rotate partly clockwise and
counterclockwise. In some embodiments, the actuator 1700 can rotate
the rotor shaft 1710 about 52 degrees total.
[0088] FIGS. 19 and 20 are perspective and cross-sectional views of
another example rotary piston-type actuator 1900. Whereas the
actuators described previously, e.g., the example actuator 100 of
FIG. 1, are generally elongated and cylindrical, the actuator 1900
is comparatively flatter and more disk-shaped.
[0089] Referring to FIG. 19, a perspective view of the example
rotary piston-type actuator 1900 is shown. The actuator 1900
includes a rotary piston assembly 1910 and a pressure chamber
assembly 1920. The rotary piston assembly 1910 includes a rotor
shaft 1912. A collection of rotor arms 1914 extend radially from
the rotor shaft 1912, the distal end of each rotor arm 1914
including a bore 1916 aligned substantially parallel with the axis
of the rotor shaft 1912 and sized to accommodate one of a
collection of connector pins 1918.
[0090] The rotary piston assembly 1910 of example actuator 1900
includes a pair of rotary pistons 1930 arranged substantially
symmetrically opposite each other across the rotor shaft 1912. In
the example of the actuator 1900, the rotary pistons 1930 are both
oriented in the same rotational direction, e.g., the rotary pistons
1930 cooperatively push in the same rotational direction. In some
embodiments, a return force may be provided to rotate the rotary
piston assembly 1910 in the direction of the rotary pistons 1930.
For example, the rotor shaft 1912 may be coupled to a load that
resists the forces provided by the rotary pistons 1930, such as a
load under gravitational pull, a load exposed to wind or water
resistance, a return spring, or any other appropriate load that can
rotate the rotary piston assembly. In some embodiments, the
actuator 1900 can include a pressurizable outer housing over the
pressure chamber assembly 1920 to provide a back-drive operation,
e.g., similar to the function provided by the outer housing 450 in
FIG. 4. In some embodiments, the actuator 1900 can be rotationally
coupled to an oppositely oriented actuator 1900 that can provide a
back-drive operation.
[0091] In some embodiments, the rotary pistons 1930 can be oriented
in opposite rotational directions, e.g., the rotary pistons 1930
can oppose each other push in the opposite rotational directions to
provide bidirectional motion control. In some embodiments, the
actuator 100 can rotate the rotor shaft about 60 degrees total.
[0092] Each of the rotary pistons 1930 of example actuator 1900
includes a piston end 1932 and one or more connector arms 1934. The
piston end 1932 is formed to have a generally semi-circular body
having a substantially smooth surface. Each of the connector arms
1934 includes a bore 1936 (see FIGS. 21B and 21C) substantially
aligned with the axis of the semi-circular body of the piston end
1932 and sized to accommodate one of the connector pins 1918.
[0093] Each of the rotary pistons 1930 of example actuator 1900 is
assembled to the rotor shaft 1912 by aligning the connector arms
1934 with the rotor arms 1914 such that the bores 1916 of the rotor
arms 1914 align with the bores 1936. The connector pins 1918 are
inserted through the aligned bores to create hinged connections
between the pistons 1930 and the rotor shaft 1912. Each connector
pin 1916 is slightly longer than the aligned bores. About the
circumferential periphery of each end of each connector pin 1916
that extends beyond the aligned bores is a circumferential recess
(not shown) that can accommodate a retaining fastener (not shown),
e.g., a snap ring or spiral ring.
[0094] Referring now to FIG. 20 a cross-sectional view of the
example rotary piston-type actuator 1900 is shown. The illustrated
example shows the rotary pistons 1930 partly inserted into a
corresponding pressure chamber 1960 formed as an arcuate cavity in
the pressure chamber assembly 1920.
[0095] Each pressure chamber 1960 of example actuator 1900 includes
a seal assembly 1962 about the interior surface of the pressure
chamber 1960 at an open end 1964. In some embodiments, the seal
assembly 1962 can be a circular or semi-circular sealing geometry
retained on all sides in a standard seal groove.
[0096] When the rotary pistons 1930 of example actuator 1900 are
inserted through the open ends 1964, each of the seal assemblies
1962 contacts the interior surface of the pressure chamber 1960 and
the substantially smooth surface of the piston end 1932 to form a
substantially pressure-sealed region within the pressure chamber
1960. Each of the pressure chambers 1960 each include a fluid port
(not shown) formed through the pressure chamber assembly 1920,
through with pressurized fluid may flow.
[0097] Upon introduction of pressurized fluid, e.g., hydraulic oil,
water, air, gas, into the pressure chambers 1960 of example
actuator 1900, the pressure differential between the interior of
the pressure chambers 1960 and the ambient conditions outside the
pressure chambers 1960 causes the piston ends 1932 to be urged
outward from the pressure chambers 1960. As the piston ends 1932
are urged outward, the pistons 1930 urge the rotary piston assembly
1910 to rotate.
[0098] In the illustrated example actuator 1900, each of the rotary
pistons 1930 includes a cavity 1966. FIGS. 21A-21C provide
additional cross-sectional and perspective views of one of the
rotary pistons 1930. Referring to FIG. 21A, a cross-section the
rotary piston 1930, taken across a section of the piston end 1932
is shown. The cavity 1966 is formed within the piston end 1932.
Referring to FIG. 21B, the connector arm 1934 and the bore 1936 is
shown in perspective. FIG. 21C features a perspective view of the
cavity 1966.
[0099] In some embodiments, the cavity 1966 may be omitted. For
example, the piston end 1932 may be solid in cross-section. In some
embodiments, the cavity 1966 may be formed to reduce the mass of
the rotary piston 1930 and the mass of the actuator 1900. For
example, the actuator 1900 may be implemented in an aircraft
application, where weight may play a role in actuator selection. In
some embodiments, the cavity 1966 may reduce wear on seal
assemblies, such as the seal assembly 320 of FIG. 3. For example,
by reducing the mass of the rotary piston 1930, the amount of force
the piston end 1932 exerts upon the corresponding seal assembly may
be reduced when the mass of the rotary piston is accelerated, e.g.,
by gravity or G-forces.
[0100] In some embodiments, the cavity 1966 may be substantially
hollow in cross-section, and include one or more structural
members, e.g., webs, within the hollow space. For example,
structural cross-members may extend across the cavity of a hollow
piston to reduce the amount by which the piston may distort, e.g.,
bowing out, when exposed to a high pressure differential across the
seal assembly.
[0101] FIGS. 22 and 23 illustrate a comparison of two example rotor
shaft embodiments. FIG. 22 is a perspective view of an example
rotary piston-type actuator 2200. In some embodiments, the example
actuator 2200 can be the example actuator 1900.
[0102] The example actuator 2200 includes a pressure chamber
assembly 2210 and a rotary piston assembly 2220. The rotary piston
assembly 2220 includes at least one rotary piston 2222 and one or
more rotor arms 2224. The rotor arms 2224 extend radially from a
rotor shaft 2230.
[0103] The rotor shaft 2230 of example actuator includes an output
section 2232 and an output section 2234 that extend longitudinally
from the pressure chamber assembly 2210. The output sections
2232-2234 include a collection of splines 2236 extending radially
from the circumferential periphery of the output sections
2232-2234. In some implementations, the output section 2232 and/or
2234 may be inserted into a correspondingly formed splined assembly
to rotationally couple the rotor shaft 2230 to other mechanisms.
For example, by rotationally coupling the output section 2232
and/or 2234 to an external assembly, the rotation of the rotary
piston assembly 2220 may be transferred to urge the rotation of the
external assembly.
[0104] FIG. 23 is a perspective view of another example rotary
piston-type actuator 2300. The actuator 2300 includes the pressure
chamber assembly 2210 and a rotary piston assembly 2320. The rotary
piston assembly 2320 includes at least one of the rotary pistons
2222 and one or more of the rotor arms 2224. The rotor arms 2224
extend radially from a rotor shaft 2330.
[0105] The rotor shaft 2330 of example actuator 2300 includes a
bore 2332 formed longitudinally along the axis of the rotor shaft
2330. The rotor shaft 2330 includes a collection of splines 2336
extending radially inward from the circumferential periphery of the
bore 2332. In some embodiments, a correspondingly formed splined
assembly may be inserted into the bore 2332 to rotationally couple
the rotor shaft 2330 to other mechanisms.
[0106] FIG. 24 is a perspective view of another example rotary
piston 2400. In some embodiments, the rotary piston 2400 can be the
rotary piston 250, 260, 414, 712, 812, 822, 1530a, 1530b, 1730a,
1730b, 1930 or 2222.
[0107] The example rotary piston 2400 includes a piston end 2410
and a connector section 2420. The connector section 2420 includes a
bore 2430 formed to accommodate a connector pin, e.g., the
connector pin 214.
[0108] The piston end 2410 of example actuator 2400 includes an end
taper 2440. The end taper 2440 is formed about the periphery of a
terminal end 2450 of the piston end 2410. The end taper 2440 is
formed at a radially inward angle starting at the outer periphery
of the piston end 2410 and ending at the terminal end 2450. In some
implementations, the end taper 2440 can be formed to ease the
process of inserting the rotary piston 2400 into a pressure
chamber, e.g., the pressure chamber 310.
[0109] The piston end 2410 of example actuator 2400 is
substantially smooth. In some embodiments, the smooth surface of
the piston end 2410 can provide a surface that can be contacted by
a seal assembly. For example, the seal assembly 320 can contact the
smooth surface of the piston end 2410 to form part of a fluidic
seal, reducing the need to form a smooth, fluidically sealable
surface on the interior walls of the pressure chamber 310.
[0110] In the illustrated example, the rotary piston 2400 is shown
as having a generally solid circular cross-section, whereas the
rotary pistons piston 250, 260, 414, 712, 812, 822, 1530a, 1530b,
1730a, 1730b, 1930 or 2222 have been illustrated as having various
generally rectangular, elliptical, and other shapes, both solid and
hollow, in cross section. In some embodiments, the cross sectional
dimensions of the rotary piston 2400, as generally indicated by the
arrows 2491 and 2492, can be adapted to any appropriate shape,
e.g., square, rectangular, ovoid, elliptical, circular, and other
shapes, both solid and hollow, in cross section. In some
embodiments, the arc of the rotary piston 2400, as generally
indicated by the angle 2493, can be adapted to any appropriate
length. In some embodiments, the radius of the rotary piston 2400,
as generally indicated by the line 2494, can be adapted to any
appropriate radius. In some embodiments, the piston end 2410 can be
substantially solid, substantially hollow, or can include any
appropriate hollow formation. In some embodiments, any of the
previously mentioned forms of the piston end 2410 can also be used
as the piston ends 1220a and/or 1220b of the dual rotary pistons
1216 of FIG. 12.
[0111] FIG. 25 is a flow diagram of an example process 2500 for
performing rotary actuation. In some implementations, the process
2500 can be performed by the rotary piston-type actuators 100, 400,
700, 800, 1200, 1500, 1700, 1900, 2200, 2300, and/or 2600 which
will be discussed in the descriptions of FIGS. 26-28.
[0112] At 2510, a rotary actuator is provided. The rotary actuator
of example actuator 2500 includes a first housing defining a first
arcuate chamber including a first cavity, a first fluid port in
fluid communication with the first cavity, an open end, and a first
seal disposed about an interior surface of the open end, a rotor
assembly rotatably journaled in the first housing and including a
rotary output shaft and a first rotor arm extending radially
outward from the rotary output shaft, an arcuate-shaped first
piston disposed in the first housing for reciprocal movement in the
first arcuate chamber through the open end. The first seal, the
first cavity, and the first piston define a first pressure chamber,
and a first connector, coupling a first end of the first piston to
the first rotor arm. For example, the actuator 100 includes the
components of the pressure chamber assembly 300 and the rotary
piston assembly 200 included in the actuation section 120.
[0113] At 2520, a pressurized fluid is applied to the first
pressure chamber. For example, pressurized fluid can be flowed
through the fluid port 320 into the pressure chamber 310.
[0114] At 2530, the first piston is urged partially outward from
the first pressure chamber to urge rotation of the rotary output
shaft in a first direction. For example, a volume of pressurized
fluid flowed into the pressure chamber 310 will displace a similar
volume of the rotary piston 260, causing the rotary piston 260 to
be partly urged out of the pressure cavity 310, which in turn will
cause the rotor shaft 210 to rotate clockwise.
[0115] At 2540, the rotary output shaft is rotated in a second
direction opposite that of the first direction. For example, the
rotor shaft 210 can be rotated counter-clockwise by an external
force, such as another mechanism, a torque-providing load, a return
spring, or any other appropriate source of rotational torque.
[0116] At 2550, the first piston is urged partially into the first
pressure chamber to urge pressurized fluid out the first fluid
port. For example, the rotary piston 260 can be pushed into the
pressure chamber 310, and the volume of the piston end 252
extending into the pressure chamber 310 will displace a similar
volume of fluid, causing it to flow out the fluid port 312.
[0117] In some embodiments, the example process 2500 can be used to
provide substantially constant power over stroke to a connected
mechanism. For example, as the actuator 100 rotates, there may be
substantially little position-dependent variation in the torque
delivered to a connected load.
[0118] In some embodiments, the first housing further defines a
second arcuate chamber comprising a second cavity, a second fluid
port in fluid communication with the second cavity, and a second
seal disposed about an interior surface of the open end, the rotor
assembly also includes a second rotor arm, the rotary actuator also
includes an arcuate-shaped second piston disposed in said housing
for reciprocal movement in the second arcuate chamber, wherein the
second seal, the second cavity, and the second piston define a
second pressure chamber, and a second connector coupling a first
end of the second piston to the second rotor arm. For example, the
actuator 100 includes the components of the pressure chamber
assembly 300 and the rotary piston assembly 200 included in the
actuation section 110.
[0119] In some embodiments, the second piston can be oriented in
the same rotational direction as the first piston. For example, the
two pistons 260 are oriented to operate cooperatively in the same
rotational direction. In some embodiments, the second piston can be
oriented in the opposite rotational direction as the first piston.
For example, the rotary pistons 250 are oriented to operate in the
opposite rotational direction relative to the rotary pistons
260.
[0120] In some embodiments, the actuator can include a second
housing and disposed about the first housing and having a second
fluid port, wherein the first housing, the second housing, the
seal, and the first piston define a second pressure chamber. For
example, the actuator 400 includes the outer housing 450 that
substantially surrounds the pressure chamber assembly 420.
Pressurized fluid in the bore 452 is separated from fluid in the
pressure chambers 422 by the seals 426.
[0121] In some implementations, rotating the rotary output shaft in
a second direction opposite that of the first direction can include
applying pressurized fluid to the second pressure chamber, and
urging the second piston partially outward from the second pressure
chamber to urge rotation of the rotary output shaft in a second
direction opposite from the first direction. For example,
pressurized fluid can be applied to the pressure chambers 310 of
the first actuation section 110 to urge the rotary pistons 260
outward, causing the rotor shaft 210 to rotate
counter-clockwise.
[0122] In some implementations, rotating the rotary output shaft in
a second direction opposite that of the first direction can include
applying pressurized fluid to the second pressure chamber, and
urging the first piston partially into the first pressure chamber
to urge rotation of the rotary output shaft in a second direction
opposite from the first direction. For example, pressurized fluid
can be flowed into the bore 452 at a pressure higher than that of
fluid in the pressure chambers 422, causing the rotary pistons 414
to move into the pressure chambers 422 and cause the rotor shaft
412 to rotate counter-clockwise.
[0123] In some implementations, rotation of the rotary output shaft
can urge rotation of the housing. For example, the rotary output
shaft 412 can be held rotationally stationary and the housing 450
can be allowed to rotate, and application of pressurized fluid in
the pressure chambers 422 can urge the rotary pistons 414 out of
the pressure chambers 422, causing the housing 450 to rotate about
the rotary output shaft 412.
[0124] FIGS. 26-28 show various views of the components of another
example rotary piston-type actuator 2600. In general, the actuator
2600 is similar to the example actuator 100 of FIG. 1, except for
the configuration of the seal assemblies. Whereas the seal assembly
320 in the example actuator 100 remains substantially stationary
relative to the pressure chamber 310 and is in sliding contact with
the surface of the rotary piston 250, in the example actuator 2600,
the seal configuration is comparatively reversed as will be
described below.
[0125] Referring to FIG. 26, a perspective view of the example
rotary piston-type actuator 2600 is shown. The actuator 2600
includes a rotary piston assembly 2700 and a pressure chamber
assembly 2602. The actuator 2600 includes a first actuation section
2610 and a second actuation section 2620. In the example of
actuator 2600, the first actuation section 2610 is configured to
rotate the rotary piston assembly 2700 in a first direction, e.g.,
counter-clockwise, and the second actuation section 2620 is
configured to rotate the rotary piston assembly 2700 in a second
direction substantially opposite the first direction, e.g.,
clockwise.
[0126] Referring now to FIG. 27, a perspective view of the example
rotary piston assembly 2700 is shown apart from the pressure
chamber assembly 2602. The rotary piston assembly 2700 includes a
rotor shaft 2710. A plurality of rotor arms 2712 extend radially
from the rotor shaft 2710, the distal end of each rotor arm 2712
including a bore (not shown) substantially aligned with the axis of
the rotor shaft 2710 and sized to accommodate one of a collection
of connector pins 2714.
[0127] As shown in FIG. 27, the first actuation section 2710 of
example rotary piston assembly 2700 includes a pair of rotary
pistons 2750, and the second actuation section 2720 includes a pair
of rotary pistons 2760. While the example actuator 2600 includes
two pairs of the rotary pistons 2750, 2760, other embodiments can
include greater and/or lesser numbers of cooperative and opposing
rotary pistons.
[0128] In the example rotary piston assembly shown in FIG. 27, each
of the rotary pistons 2750, 2760 includes a piston end 2752 and one
or more connector arms 2754. The piston end 252 is formed to have a
generally semi-circular body having a substantially smooth surface.
Each of the connector arms 2754 includes a bore 2756 substantially
aligned with the axis of the semi-circular body of the piston end
2752 and sized to accommodate one of the connector pins 2714.
[0129] In some implementations, each of the rotary pistons 2750,
2760 includes a seal assembly 2780 disposed about the outer
periphery of the piston ends 2752. In some implementations, the
seal assembly 2780 can be a circular or semi-circular sealing
geometry retained on all sides in a standard seal groove. In some
implementations, commercially available reciprocating piston or
cylinder type seals can be used. For example, commercially
available seal types that may already be in use for linear
hydraulic actuators flying on current aircraft may demonstrate
sufficient capability for linear load and position holding
applications. In some implementations, the sealing complexity of
the actuator 2600 may be reduced by using a standard, e.g.,
commercially available, semi-circular, unidirectional seal designs
generally used in linear hydraulic actuators. In some embodiments,
the seal assembly 2780 can be a one-piece seal.
[0130] FIG. 28 is a perspective cross-sectional view of the example
rotary piston-type actuator 2600. The illustrated example shows the
rotary pistons 2760 inserted into a corresponding pressure chamber
2810 formed as an arcuate cavity in the pressure chamber assembly
2602. The rotary pistons 2750 are also inserted into corresponding
pressure chambers 2810, not visible in this view.
[0131] In the example actuator 2600, when the rotary pistons 2750,
2760 are each inserted through an open end 2830 of each pressure
chamber 2810, each seal assembly 2780 contacts the outer periphery
of the piston end 2760 and the substantially smooth interior
surface of the pressure chamber 2810 to form a substantially
pressure-sealed region within the pressure chamber 2810.
[0132] In some embodiments, the seal 2780 can act as a bearing. For
example, the seal 2780 may provide support for the piston 2750,
2760 as it moves in and out of the pressure chamber 310.
[0133] Although a few implementations have been described in detail
above, other modifications are possible. For example, the logic
flows depicted in the figures do not require the particular order
shown, or sequential order, to achieve desirable results. In
addition, other steps may be provided, or steps may be eliminated,
from the described flows, and other components may be added to, or
removed from, the described systems. Accordingly, other
implementations are within the scope of the following claims.
* * * * *