U.S. patent application number 10/322002 was filed with the patent office on 2004-08-05 for telescopic hydraulic cylinder.
Invention is credited to Albright, Larry E., Bares, Mark F., Fischer, Gregory L., Roan, Thomas J., Shelbourn, William C..
Application Number | 20040148822 10/322002 |
Document ID | / |
Family ID | 32770154 |
Filed Date | 2004-08-05 |
United States Patent
Application |
20040148822 |
Kind Code |
A1 |
Albright, Larry E. ; et
al. |
August 5, 2004 |
Telescopic hydraulic cylinder
Abstract
An extension cylinder is provided and includes an elongated tube
having a distal end, a proximal end, and a first fluid opening
formed proximate the proximal end. The extension cylinder also
includes an elongated rod that is telescopically received within
the elongated tube through the distal end thereof. The elongated
rod has a second fluid opening formed proximate a rod distal end. A
fluid communication tube is disposed between, and enables fluid
communication between, the first and second fluid openings. The
fluid communication tube includes a length that varies depending on
how far the elongated rod is extended or retracted from the distal
end of the elongated tube.
Inventors: |
Albright, Larry E.;
(Gwinner, ND) ; Roan, Thomas J.; (Fargo, ND)
; Fischer, Gregory L.; (Lake City, SD) ;
Shelbourn, William C.; (Bismarck, ND) ; Bares, Mark
F.; (Oakes, ND) |
Correspondence
Address: |
Christopher L. Holt
WESTMAN CHAMPLIN & KELLY
International Centre - Suite 1600
900 South Second Avenue
Minneapolis
MN
55402-3319
US
|
Family ID: |
32770154 |
Appl. No.: |
10/322002 |
Filed: |
December 17, 2002 |
Current U.S.
Class: |
37/466 |
Current CPC
Class: |
E02F 3/3402 20130101;
E02F 3/3414 20130101; E02F 9/2271 20130101 |
Class at
Publication: |
037/466 |
International
Class: |
E02F 003/00 |
Claims
What is claimed is:
1. An extension cylinder, comprising: an elongated tube having a
distal end, a proximal end, and a first fluid opening formed
proximate the proximal end; an elongated rod that is telescopically
received within the elongated tube through the distal end thereof,
the elongated rod having a second fluid opening formed proximate a
rod distal end; and a fluid communication tube disposed between,
and enabling fluid communication between, the first and second
fluid openings, wherein the fluid communication tube includes a
length that varies depending on how far the elongated rod is
extended or retracted from the distal end of the elongated
tube.
2. The extension cylinder of claim 1, wherein the fluid
communication tube comprises: a first fluid chamber formed by an
interior surface of the elongated rod; and a second fluid chamber
formed by an interior surface of an internal tube member that is
positioned within the elongated tube, wherein at least a portion of
the internal tube member extends into the first fluid chamber, the
internal tube member and the first fluid chamber being configured
such that the amount of the internal tube member that extends into
the first fluid chamber varies depending on how far the elongated
rod is extended or retracted from the distal end of the elongated
tube, thereby enabling uninterrupted fluid communication between
the first and second fluid openings during and following an
extension or retraction of the elongated rod.
3. The extension cylinder of claim 2, wherein the elongated tube
further comprises a tube interior surface that forms an extension
chamber, the internal tube member and the elongated rod being
radially displaced from the tube interior surface.
4. The extension cylinder of claim 3, further comprising a piston
attached to the elongated rod, the piston being slidably received
within the extension chamber.
5. The extension cylinder of claim 1, wherein the elongated tube
further comprises a tube interior surface that forms an extension
chamber, said fluid communication tube being radially displaced
from the tube interior surface.
6. The extension cylinder of claim 5, further comprising a piston
attached to the elongated rod and dividing the extension chamber
into first and second portions, the piston being configured to
extend or retract the elongated rod in response to fluid being
added and subtracted to the first and second portions of the
extension chamber.
7. The extension cylinder of claim 1, further comprising a base end
member that is attached to the proximal end of the elongated tube
and includes a fluid conduit opening and a fluid chamber formed by
an interior surface, wherein the fluid chamber extends between, and
enables fluid communication between, the fluid conduit opening and
the first fluid opening formed proximate the proximal end of the
elongated tube.
8. The extension cylinder of claim 1, further comprising a base end
member that is attached to the proximal end of the elongated tube,
wherein the fluid communication tube extends through the base end
member.
9. The extension cylinder of claim 1, further comprising a rod end
member that is attached to the distal end of the elongated rod and
includes a fluid conduit opening and a fluid chamber formed by an
interior surface, wherein the fluid chamber extends between, and
enables fluid communication between, the fluid conduit opening and
the second fluid opening.
10. The extension cylinder of claim 1, further comprising: a rod
end member that includes a fluid conduit opening that is connected
to a fluid chamber formed by an interior surface, wherein the fluid
chamber extends through the rod end member and enables fluid
communication to the fluid conduit opening; a rod extension piece
that is secured between the distal end of the elongated rod and the
rod end member, wherein the rod extension piece includes an
extension fluid chamber formed by an interior surface, and wherein
the extension fluid chamber extends between, and enables fluid
communication between, the second fluid opening and the fluid
conduit opening.
11. The extension cylinder of claim 10, wherein an extension
coupler is secured between the distal end of the elongated rod and
the rod extension piece to facilitate connection of the rod
extension piece to the distal end of the elongated rod.
12. The extension cylinder of claim 1, further comprising a rod end
member that is attached to the distal end of the elongated rod,
wherein the fluid communication tube extends through the base end
member.
13. An actuator rod for use within a hydraulic extension cylinder,
comprising: a proximal end and a distal end; an exterior surface; a
fluid opening formed proximate the distal end; a tube-receiving
opening formed proximate the proximal end; a fluid chamber formed
by an interior surface of the elongated rod, the fluid chamber
being connected to, and extending between, the fluid and
tube-receiving openings; and a piston engaged proximate the
proximal end and having a piston opening configured to accommodate
and prevent significant obstruction of the tube-receiving
opening.
14. The actuator rod of claim 13, further comprising a rod end
member that is attached to the distal end and includes a fluid
conduit opening and a fluid chamber formed by an interior surface,
wherein the fluid chamber extends between, and enables fluid
communication between, the fluid conduit opening and the fluid
opening.
15. The actuator rod of claim 13, further comprising: a rod end
member that includes a fluid conduit opening that is connected to a
fluid chamber formed by an interior surface, wherein the fluid
chamber extends through the rod end member and enables fluid
communication to the fluid conduit opening; a rod extension piece
that is secured between the distal end of the actuator rod and the
rod end member, wherein the rod extension piece includes an
extension fluid chamber formed by an interior surface, and wherein
the extension fluid chamber extends between, and enables fluid
communication between, the fluid opening of the actuator rod and
the fluid conduit opening of the rod end member.
16. The actuator rod of claim 15, wherein an extension coupler is
secured between the distal end of the actuator rod and the rod
extension piece to facilitate connection of the rod extension piece
to the distal end of the elongated rod.
17. The actuator rod of claim 13, further comprising a rod end
member that is attached to the distal end of the actuator rod,
wherein the fluid chamber formed by an interior surface of the
elongated rod extends through the base end member.
18. A power machine, comprising: a frame; a plurality of ground
engaging wheels supporting the frame; a cab operably coupled to the
frame and defining an operator compartment; an engine operably
coupled to the wheels; a telescoping lift arm operably coupled to
the frame; a hydraulically actuated device secured to the power
machine proximate a distal end of the telescoping lift arm; and a
hydraulic cylinder that is attached to a portion of the telescoping
lift arm for extending and retracting the telescoping lift arm,
while at the same time providing a path for fluid communication to
the hydraulically actuated device, comprising: an elongated tube
having a distal end, a proximal end, and a first fluid opening
formed proximate the proximal end; an elongated rod that is
telescopically received within the elongated tube through the
distal end thereof, the elongated rod having a second fluid opening
formed proximate a rod distal end; and a fluid communication tube
disposed between, and enabling fluid communication between, the
first and second fluid openings, wherein the distance between the
first and second fluid openings varies depending on how far the
elongated rod is extended or retracted form the distal end of the
elongated tube.
19. The power machine of claim 18, wherein the fluid communication
tube comprises: a first fluid chamber formed by an interior surface
of the elongated rod; and a second fluid chamber formed by an
interior surface of an internal tube member that is positioned
within the elongated tube, wherein at least a portion of the
internal tube member extends into the first fluid chamber, the
internal tube member and the first fluid chamber being configured
such that the amount of the internal tube member that extends into
the first fluid chamber varies depending on how far the elongated
rod is extended or retracted from the distal end of the elongated
tube, thereby enabling uninterrupted fluid communication between
the first and second fluid openings during and following an
extension or retraction of the elongated rod.
20. The power machine of claim 18, wherein the elongated tube
further comprises a tube interior surface that forms an extension
chamber, said fluid communication tube being radially displaced
from the tube interior surface.
Description
BACKGROUND OF THE INVENTION
[0001] The present application generally pertains to telescoping
lift arms that may be utilized, either in pairs or as an individual
arm, in the context of a loader, such as a skid steer loader. More
specifically, the present application pertains to a hydraulic
extension cylinder designed to hydraulically extend and retract a
telescopic lift arm, while at the same time facilitating consistent
fluid communication between a fluid tank (and/or a fluid pump) at a
base end of the lift arm and a hydraulically actuated device
located proximate a distal end of the lift arm.
[0002] Telescoping lift arms have been well known and used in
various applications, including front-end loaders, crane booms, and
the like. Certain of these known telescoping lift arms include a
hydraulic extension cylinder that is configured to slide or
telescope an inner lift arm section relative to an outer lift arm
section in response to an instruction or signal. In this way, the
over all length of the lift arm can be desirably adjusted.
[0003] Within certain applications, it becomes desirable to
position a hydraulically actuated device (e.g., a tool) proximate a
distal end of a telescoping lift arm. For example, the distal end
of the telescoping lift arm may be configured to support a
hydraulically actuated tree cutting tool, a cement mixing tool, an
adjustable bucket, or some other hydraulically active device. In
order to provide hydraulic power, a fluid communication path is
typically provided to connect a fluid tank (and/or a fluid pump),
generally located at a proximal end of the telescoping lift arm,
with the hydraulically actuated device, generally located proximate
a distal end of the of the telescoping lift arm.
[0004] It is desirable that a hydraulically actuated device located
proximate a distal end of a telescoping lift arm remains
operational regardless of the lift arm's extension status.
Therefore, it is desirable to maintain continuous fluid
communication between the fluid tank (and/or a fluid pump) and the
hydraulically actuated device regardless of the extension status of
the telescoping lift arm. Because the precise distance between the
fluid tank (and/or a fluid pump) and the hydraulically actuated
device varies depending on extension and retraction of the
telescoping lift arm, maintaining continuous fluid communication
presents a challenging design task.
[0005] One way to maintain the necessary continuous fluid flow
regardless of the extension status of an associated telescoping
lift arm is to provide a telescoping feed line between the tank
(and/or a fluid pump) and the hydraulically actuated device.
Accordingly, as the telescoping lift arm extends and retracts, so
does the telescoping feed line. Incorporation of a telescoping feed
line, however, requires specialized mechanical and hydraulic
components that generally increase overall design costs. Also, due
to the active mechanical nature of a telescoping feed line, a
significantly increased maintenance burden is virtually
inevitable.
[0006] The present invention provides a solution to these and other
problems and offers advantages over the prior art.
SUMMARY OF THE INVENTION
[0007] One aspect of the present invention generally pertains to an
extension cylinder that includes an elongated tube having a distal
end, a proximal end, and a first fluid opening formed proximate the
proximal end. The extension cylinder also includes an elongated rod
that is telescopically received within the elongated tube through
the distal end thereof. The elongated rod has a second fluid
opening formed proximate a rod distal end. A fluid communication
tube is disposed between, and enables fluid communication between,
the first and second fluid openings. The fluid communication tube
includes a length that varies depending on how far the elongated
rod is extended or retracted from the distal end of the elongated
tube.
[0008] Another aspect of the present invention generally pertains
to an actuator rod for use within a hydraulic extension cylinder.
The actuator rod includes a proximal end, a distal end and an
exterior surface. A fluid opening is formed proximate the distal
end. A tube-receiving opening is formed proximate the proximal end.
A fluid chamber is formed by an interior surface of the elongated
rod. The fluid chamber is connected to, and extends between, the
fluid and tube-receiving openings. A piston is engaged proximate
the proximal end of the actuator rod. The piston has a piston
opening configured to accommodate and prevent significant
obstruction of the tube-receiving opening.
[0009] Still another aspect of the present invention generally
pertains to a power machine that includes a frame, a plurality of
ground engaging wheels that support the frame, and a cab that is
operably coupled to the frame and defines an operator compartment.
In addition, an engine is operably coupled to the wheels and a
telescoping lift arm is operably coupled to the frame. A
hydraulically actuated device is secured to the power machine
proximate a distal end of the telescoping lift arm. A hydraulic
cylinder is attached to a portion of the telescoping lift arm for
extension and retraction, while at the same time providing a path
for fluid communication to the hydraulically actuated device. The
hydraulic cylinder includes an elongated tube having a distal end,
a proximal end, and a first fluid opening formed proximate the
proximal end. An elongated rod is telescopically received within
the elongated tube through the distal end thereof. The elongated
rod has a second fluid opening formed proximate a rod distal end. A
fluid communication tube is disposed between, and enables fluid
communication between, the first and second fluid openings. The
distance between the first and second fluid openings varies
depending on how far the elongated rod is extended or retracted
form the distal end of the elongated tube.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic side elevational view of a skid steer
loader having a specialized lift arm assembly for extending and
retracting a telescoping loader arm.
[0011] FIG. 2 is an exploded perspective view of the specialized
lift arm assembly.
[0012] FIG. 3 is a top plan view of the specialized lift arm
assembly.
[0013] FIG. 4A is a side view of an actuator cylinder made
according to the present invention.
[0014] FIG. 4B is an end view of the actuator cylinder and is
depicted from the perspective of line 4B-4B in FIG. 4A.
[0015] FIG. 4C is an end view of the actuator cylinder and is
depicted from the perspective of line 4C-4C in FIG. 4A.
[0016] FIG. 5 is a cross-sectional view of the actuator cylinder
taken along line 5-5 in FIGS. 4B and 4C.
[0017] FIG. 6A is a side view of a portion of an actuator cylinder
that includes a rod extension piece.
[0018] FIG. 6B is a cross-sectional view of the components depicted
in FIG. 6A and is taken through line 6B-6B in FIG. 6A.
[0019] FIG. 7A is a side view of a portion of an actuator cylinder
that includes a rod extension piece.
[0020] FIG. 7B is a cross-sectional view of the components depicted
in FIG. 7A and is taken through line 7B-7B in FIG. 7A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] FIG. 1 is a schematic representation of a skid steer loader
10 having a telescoping loader arm (also known as a loader boom).
Skid steer loader 10 includes specialized lift arm assemblies for
extending and retracting the telescoping loader arm. FIG. 2 is an
exploded view of the specialized lift arm assemblies incorporated
into skid steer loader 10. FIG. 3 is a top plan view of the
specialized lift arm assemblies.
[0022] It should be noted that skid steer loader 10 includes
telescoping lift arms having a bell-shaped cross section that
permits an inner lift arm to slide or telescope relative to an
outer lift arm while being guided along linear bearings. This
particular telescopic lift arm arrangement, which should be
considered only one illustrative arrangement of many that are
suitable to accommodate embodiments of the present invention, is
described specifically in co-pending U.S. application Ser. No.
10/123,469, filed on Apr. 15, 2002, and entitled "TELESCOPING
LOADER LIFT ARM."
[0023] Skid steer loader 10 has a frame 12, and drive wheels 14 for
propelling the loader across the ground. Frame 12 supports an
operator's cab 16, and an engine compartment 18 for housing the
engine (not shown). The frame 12 also includes boom support plates
or frame members 20 on which a telescoping lift arm assembly 22 is
pivotally mounted on pivots 36. The lift arm assembly 22 comprises
individual lift arms 24 and 26, one pivoted on each of the opposite
sides of the skid steer loader. The two lift arms are
illustratively identical except that one is on the right-hand side
and the other is on the left-hand side.
[0024] The lift arm assembly 22 is made up of an individual inner
lift arm tube 42 that is held in a complementary-shaped outer arm
tube 40. The inner tubes 42 are held together with a suitable cross
member 28 proximate their forward ends. The outer arm portion of
lift arm assembly 22 is raised and lowered by pivoting the lift arm
assembly about the pivots 36 with hydraulic cylinders 30 that have
base end pivots 32 connected to the vehicle frame, and rod ends
connected at pivots 34 to the lift arms 24 and 26. The actuators 30
are controlled in a conventional manner using suitable valves in
the hydraulic system of the skid steer loader.
[0025] Each of the telescoping tubular lift arms 24 and 26 includes
the main outer lift arm tube or housing 40 and the telescoping
inner lift arm tubes 42. The inner lift arm tubes 42 telescope
relative to the outer lift arm tubes 40 as an inner assembly 29.
The lift arm tubes 42 fit inside the outer lift arm tubes 40 and
slide longitudinally relative thereto. The inner assembly 29 of the
inner lift arm tubes is moved as a unit through the use of
hydraulic actuators 44 in a conventional manner. A collar 40C is
provided proximate the end of outer lift arm tubes for reinforcing
and adding rigidity to the side walls of the outer tube.
[0026] As shown, the base ends of actuators 44 are mounted to the
outer lift arm housing or tubes 40 on pins 44A, so that the
actuators 44 pivot up and down therewith. Each actuator 44 has a
rod end pivotally connected with pins 48 to the inner lift arm
tubes 42 so that upon extending and retracting the actuator
cylinders 44 with a suitable valve 45, the inner lift arm tubes 42
are extended and retracted as desired. The inner lift arm tube
assembly 29, as shown, has a tool or accessory attachment
connection plate 52 proximate its outer or forward ends. Depending
side frames 53, which are fixed to the inner lift arm tubes 42, are
connected with a cross member 28. The attachment plate is pivotally
mounted to the lower ends of the side frame 53 and optionally
controlled with control cylinders 53A. Cross member 28 can be used
for mounting a hydraulic valve. In accordance with one embodiment,
a hydraulically actuated device is mounted on the distal end of the
loader arms (e.g., mounted to the attachment plate) and operably
connected to a hydraulic valve mounted on cross member 28.
[0027] The hydraulic actuators 44 in FIGS. 1-3 are merely
representative of the types of actuators that can be used to enable
telescoping movement of the inner lift arm tubes. Embodiments of
the present invention pertain to specialized hydraulic actuators
that can be used to enable telescoping movement of the inner lift
arm tubes, while at the same time providing a fluid communication
path to and/or from a hydraulically-actuated device positioned
proximate a distal end of the telescoping lift arm. These
specialized hydraulic actuators are described below in detail.
[0028] FIG. 4A is a side view of an actuator cylinder 400, in
accordance with an embodiment of the present invention. Generally
speaking, actuator cylinder 400 is configured to extend and retract
a telescoping lift arm, while at the same time providing a fluid
communication path to and/or from a hydraulically-actuated device
positioned proximate a distal end of the telescoping lift arm.
Actuator cylinder 400 is illustratively of an overall configuration
making it appropriate to be incorporated as a hydraulic actuator 44
within skid steer loader 10 (FIGS. 1-3).
[0029] Actuator cylinder 400 has a base end member 402 that is
configured to be pivotally connected to outer lift arm tube 40 on a
pin connection 44A such that cylinder 400 is able to pivot up and
down with the tube. Base end member 402 is connected to a proximal
end of a tube 408. Cylinder 400 further includes a rod end member
404 that is configured to be pivotally connected with a pin
connection 48 to an inner lift arm tube 42. Rod end member 404 is
connected to a distal end 418 of a rod 420. Rod 420 extends through
and is slidably and telescopically engaged within tube 408.
[0030] A proximal end of rod 420 is connected to a piston (not
shown in FIG. 4) that is controlled in a conventional manner using
a suitable valve or valves within the hydraulic system of the skid
steer loader (e.g., valve 45 in FIG. 1) so as to enable rod 420 to
be desirably extended and retracted. Tube 408 includes fluid
conduit openings 414 and 416 through which fluid is transferred to
desirably drive the piston in one direction or the other, thereby
causing rod 420 to extend and retract as described. In this way, in
the context of skid steer loader 10, the inner lift arm tube 42,
which is connected to rod end member 404, can be telescopically
extended or retracted, thereby causing a corresponding extension or
retraction of the associated lift arm.
[0031] In accordance with one embodiment of the present invention,
an actuator cylinder 400 is incorporated with a lift arm on both
sides of skid steer loader 10. In other words, one actuator
cylinder 400 is utilized to telescopically extend or retract the
lift arm on the right-hand side of loader 10 and another is
utilized in association with the lift arm on the left-hand side. In
accordance with another embodiment, however, an actuator cylinder
400 is only used on one side or the other.
[0032] In addition to enabling actuation of a telescopic lift arm,
actuator cylinder 400 also provides a fluid communication path to
and/or from a distally positioned hydraulically actuated device.
Accordingly, a first fluid conduit opening 410 is formed within a
proximal end 411 of actuator cylinder 400. A second fluid conduit
opening 412 is formed within a distal end 413. Fluid conduit
opening 410 is configured to be in fluid communication with fluid
conduit opening 412, even during and following an extension or
retraction of rod 420. Fluid conduit opening 410 is configured for
direct or indirect connection to a fluid tank (and/or a fluid
pump). An indirect connection, for example, is made utilizing an
intermediate hose and/or a valve or valve box. Fluid conduit
opening 412 is configured for connection to a hydraulically
actuated tool. The connection between fluid conduit opening 412 and
the hydraulically actuated tool is illustratively made either
directly or indirectly (e.g., indirectly through a hose and/or
through an associated hydraulic valve or valve box mounted on cross
member 28 shown in FIG. 1).
[0033] As will be described in more detail in relation to FIG. 5,
fluid is communicated between conduit openings 410 and 412 through
chambers formed within rod 420 and an internal tube member. Fluid
communication between conduit openings 410 and 412 through the
chambers remains uninterrupted during and following an extension or
retraction of rod 420. Illustratively, the stroke of the piston
within actuator cylinder 400, and/or the length of rod 420, can be
customized to accommodate a desired range of extension and
retraction that can be accomplished without interruption of fluid
communication between conduit openings 410 and 412. Specific
structural strategies for customizing the length of rod 420 will be
discussed below in relation to FIGS. 6A, 6B, 7A and 7B. Through
incorporation and customization of an actuator cylinder 400, a
hydraulically actuated device located proximate a distal end of
skid steer loader 10's telescoping lift arms is able to remain in
operable fluid communication with a fluid tank (and/or a fluid
pump) generally regardless of the extension status of an associated
telescoping lift arm.
[0034] Different hydraulic valves and hydraulically actuated
devices require different fluid flow schemes. It is within the
scope of the present invention to specifically adapt one or more
actuator cylinders 400 to accommodate different fluid flow schemes.
In accordance with one embodiment, the actuator cylinder 400 on the
right-hand side provides a fluid communication path to a
hydraulically-actuated device positioned proximate a distal end of
the telescoping lift arm, while the other actuator cylinder
provides a return fluid communication path away from the
hydraulically-actuated device, or vice versa. In accordance with
another embodiment of the present invention, however, at least one
and illustratively both actuator cylinders 400 are configured to
provide a reversible fluid communication path to and from a
hydraulically-actuated device positioned proximate a distal end of
the telescoping lift arm (e.g., two-way switchable fluid
communication).
[0035] FIG. 4B is an end view of actuator cylinder 400 as viewed
from the perspective of line 4B-4B in FIG. 4A. An end view of
actuator cylinder as viewed from the perspective of line 4C-4C in
FIG. 4A is depicted by FIG. 4C. FIG. 5 is a cross-sectional view of
actuator cylinder 400 taken along line 5-5 in FIGS. 4B and 4C.
[0036] With reference to FIG. 5, a proximal end 502 of rod 420 is
connected to a piston 504. Piston 504 is connected to (e.g.,
inertia welded to) rod 420. In addition, piston 504 slidably
engages an interior surface of tube 408. Accordingly, piston 504
divides a fluid chamber 505 into two portions, namely, a first
portion that is proximally located relative to piston 504 and a
second portion that is distally located relative to piston 504. An
O-ring, a nylon seal, a wear ring and/or some other similar device
can illustratively be integrated with piston 504 to enhance the
ability of piston 504 to move within fluid chamber 505 while still
isolating the first and second portions of the fluid chamber from
one another.
[0037] The portion of fluid chamber 505 that is distally located
relative to piston 504 is illustratively in fluid communication
with conduit opening 414 (FIG. 4A). The portion of fluid chamber
505 that is proximally located relative piston 504 is
illustratively in fluid communication with conduit opening 416
(FIG. 4A). Accordingly, as was described above in relation to FIG.
4A, fluid is transferred through conduit openings 414 and 416 in
order to desirably drive piston 504 in one direction or the other,
thereby causing rod 420 to extend or retract. Therefore, piston 504
is configured to be hydraulically driven by a suitable valve system
(e.g., valve 45 in FIG. 1) so as to enable rod 420 to be desirably
extended or retracted, thereby causing a corresponding extension or
retraction of a lift arm.
[0038] A chamber 532 is formed within rod 420 and is generally
formed by an internal surface of the rod. In accordance with one
embodiment, chamber 532 illustratively extends from an opening 528
(formed through piston 504) to conduit opening 412. In accordance
with another embodiment, however, chamber 532 terminates at the
proximal end of rod end member 404, which includes a corresponding
internal chamber that extends between its proximal and distal ends.
An O-ring, lock nut, or some other sealing mechanism is optionally
utilized to prevent leakage proximate the area where rod 420
adjoins rod end member 404. Whether rod 420 extends through rod end
member 404 or cooperates with a separate channel formed within rod
end member 404 is not critical to the present invention. Both
designs enable a fluid communication path that reaches conduit
opening 412.
[0039] An inner tube element 560, which includes an inner chamber
562, extends from conduit opening 410, through the piston opening
528 and into the rod chamber 532. Inner tube element 560 is
sealingly engaged proximate piston 504 such that fluid flow is
generally prevented between chamber 505 and the rod chamber 532,
and between chamber 505 and the tube element chamber 562. Inner
tube element 560 is also slidingly engaged proximate piston
504.
[0040] In accordance with one embodiment, inner tube element 560
terminates proximate the distal end of end member 402. Accordingly,
end member 402 includes a corresponding internal chamber that
extends between its proximal and distal ends. An O-ring, lock nut
or some other sealing mechanism is optionally utilized to prevent
leakage proximate the area where inner tube element 560 adjoins end
member 402. Whether inner tube element 560 extends through end
member 402 or cooperates with a separate channel formed within end
member 402 is not critical to the present invention. Both designs
enable a fluid communication path that reaches conduit opening
410.
[0041] Inner tube element 560 illustratively has an overall length
that enables a distal end 564 thereof to remain within the rod
chamber 532 regardless of the position of piston 504 within chamber
505. Accordingly, fluid can be transferred between conduit openings
410 and 412 regardless of whether rod 420 is fully extended, fully
retracted, or somewhere in between. Regardless of the extension
status of rod 420, fluid can be transferred between chamber 562 and
fluid chamber 532, and therefore between conduit openings 410 and
412, and therefore between a fluid tank (and/or a fluid pump) at a
base end of the lift arm and a hydraulically actuated device
located proximate a distal end of the lift arm.
[0042] In FIGS. 4A-4C and 5, rod 420 is directly connected to rod
end member 404. In accordance with one embodiment, this connection
is made utilizing a thread/seal interface. For example, the distal
end of the rod includes threads that correspond to threads in the
end member. An O-ring and/or some other fluid sealing device can be
utilized to seal and secure the cooperating threaded components.
Other means for attaching rod 420 to rod end member 404 are within
the scope of the present invention.
[0043] Chamber 562 and chamber 532 together form a fluid
communication tube that extends from a distal end of fluid chamber
532 to a proximal end of chamber 562. The distance between the
distal end of fluid chamber 532 and the proximal end of chamber 562
will illustratively vary depending on how far tube 420 is extended
or retracted (e.g., depending on how far distal end 564 is inserted
into chamber 532). The distance between the distal end of fluid
chamber 532 and the proximal end of chamber 562 may or may not
include the chamber portions within ends 402 and 404 (e.g.,
depending on whether the chamber portions within ends 402 and 404
are integrally formed with chambers 532 and 562). Either way, the
general length of the communication tube (e.g., chamber 532+chamber
562) will vary depending on how far tube 420 is extended or
retracted.
[0044] For some applications, directly attaching the rod to the end
member does not enable an economical cylinder and/or rod length.
For these applications, in accordance with one aspect of the
present invention, a low cost extension tube can be incorporated
between the rod and end members (e.g, to reduce costs associated
with long lengths of expensive material).
[0045] FIG. 6A, in accordance with one embodiment of the present
invention, is a side view of a portion of an actuator cylinder that
includes an actuator rod extension piece 602 and an associated rod
extension coupler 604. FIG. 6B is a cross-sectional view of the
components depicted in FIG. 6A and is taken through line 6B-6B in
FIG. 6A. Elements identified in FIGS. 6A and 6B that are the same
as or similar to elements identified and described in relation to
previous Figures have been given a same or similar reference
numeral.
[0046] Rod extension coupler 604 is illustratively utilized to
align and connect distal end 418 of rod 420 with a proximal end 606
of rod extension piece 602. Lock nuts 608 facilitate and secure the
connection of the rod ends. It should be pointed out that
connection devices other than lock nuts (e.g., inertia welded
joints, etc.) could be utilized without departing from the scope of
the present invention. One or more O-ring seals 610 are optionally
and internally positioned between rod end 610 and coupler 604, and
between rod end 418 and coupler 604, so as to prevent fluid leakage
proximate coupler 604. A distal end 612 of rod extension piece 602
is connected and secured to rod end member 404 utilizing a lock nut
614. An optional O-ring seal 616 is internally positioned between
rod end 612 and end member 404 to prevent fluid leakage.
[0047] Rod extension piece 602 has an internal chamber 620 formed
therein. After piece 602 has been secured in place utilizing
coupler 604, chamber 620 is securedly positioned so as to be in
fluid communication with chamber 532 and the chamber formed within
rod end member 404. Accordingly, conduit opening 412 remains in
fluid communication with chamber 532, regardless of the extension
status of rod 420. In accordance with one embodiment, internal
chamber 620 extends through rod end member 404 to conduit opening
412 (e.g., instead of engaging a chamber formed within rod end
member 404).
[0048] FIG. 7A, in accordance with another embodiment of the
present invention, is a side view of a portion of an actuator
cylinder that includes an actuator rod extension piece 702. FIG. 7B
is a cross-sectional view of the components depicted in FIG. 7A and
is taken through line 7B-7B in FIG. 7A. Elements identified in
FIGS. 7A and 7B that are the same as or similar to elements
identified and described in relation to previous Figures have been
given a same or similar reference numeral.
[0049] FIGS. 7A and 7B depict another embodiment wherein a rod
extension piece 702 is directly connected to distal end 418 of rod
420, without incorporation of a coupler component. The distal end
418 illustratively includes threads that are designed to engage
corresponding threads formed within the proximal end 706 of rod
extension piece 702. A lock nut 704 facilitates and secures the
connection of the rod ends. An optional sealing member 708 (e.g., a
ring seal or an O-ring) is optionally and internally placed between
the component ends to prevent fluid leakage at the point of
connection. Connection devices other than a threaded engagement
and/or a lock nut arrangement could be utilized without departing
from the scope of the present invention. A distal end 712 of rod
extension piece 702 is connected and secured to rod end member 404
utilizing an inertia weld attachment or some other means of
attachment (e.g., a threaded engagement, lock nut, etc.). An
optional O-ring seal can be internally positioned between rod end
712 and end member 404 to prevent fluid leakage.
[0050] Rod extension piece 702 has an internal chamber 720 formed
therein. After piece 702 has been secured in place, chamber 720 is
in fluid communication with chamber 532 and the chamber formed
within rod end member 404. Accordingly, conduit opening 412 remains
in fluid communication with chamber 532, regardless of the
extension status of rod 420. In accordance with one embodiment,
internal chamber 720 extends through rod end member 404 to conduit
opening 412 (e.g., instead of engaging a chamber formed within rod
end member 404).
[0051] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *