U.S. patent application number 11/080008 was filed with the patent office on 2006-09-21 for hydraulic cylinder with integrated accumulator.
This patent application is currently assigned to Deere & Company, a Delaware corporation. Invention is credited to Jahmy Jomont Hindman.
Application Number | 20060207246 11/080008 |
Document ID | / |
Family ID | 36216793 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060207246 |
Kind Code |
A1 |
Hindman; Jahmy Jomont |
September 21, 2006 |
HYDRAULIC CYLINDER WITH INTEGRATED ACCUMULATOR
Abstract
A hydraulic cylinder assembly includes a hydraulic cylinder and
an integral concentric accumulator. The hydraulic cylinder has a
first piston surface for extending the cylinder, a second piston
surface for retracting the cylinder and a third piston surface in
dedicated communication with the accumulator.
Inventors: |
Hindman; Jahmy Jomont;
(Durango, IA) |
Correspondence
Address: |
DEERE & COMPANY
ONE JOHN DEERE PLACE
MOLINE
IL
61265
US
|
Assignee: |
Deere & Company, a Delaware
corporation
|
Family ID: |
36216793 |
Appl. No.: |
11/080008 |
Filed: |
March 15, 2005 |
Current U.S.
Class: |
60/413 |
Current CPC
Class: |
A01D 34/246 20130101;
F15B 1/02 20130101; F15B 2201/31 20130101; F15B 15/1466
20130101 |
Class at
Publication: |
060/413 |
International
Class: |
F16D 31/02 20060101
F16D031/02 |
Claims
1. A hydraulic cylinder assembly, comprising: an accumulator; a
floating accumulator piston disposed in the accumulator; and a
hydraulic cylinder having a first piston surface for extending the
hydraulic cylinder, a second piston surface for retracting the
hydraulic cylinder and a third piston surface in dedicated
communication with the accumulator, the accumulator being integral
to the hydraulic cylinder, the accumulator being concentric with
the hydraulic cylinder.
2. A hydraulic cylinder assembly, comprising: an accumulator having
a piston, a first accumulator port, and a second accumulator port;
and a hydraulic cylinder having a first cylinder port, a second
cylinder port, and a third cylinder port, the hydraulic cylinder
including a first piston surface having a first effective area, a
second piston surface having a second effective area and a third
piston surface having a third effective area, the first piston
surface in communication with the first cylinder port, the second
piston surface in communication with the second cylinder port, the
third piston surface in communication with the third cylinder port,
the third piston surface also in communication with the second
accumulator port, the accumulator being integral to the hydraulic
cylinder, the accumulator being concentric with the hydraulic
cylinder.
3. The hydraulic cylinder assembly of claim 2, wherein the first
effective area is about equal to the second effective area.
4. The hydraulic cylinder assembly of claim 2, wherein a pressure
on the first piston surface acts to extend the hydraulic
cylinder.
5. The hydraulic cylinder assembly of claim 2, wherein a pressure
on the second piston surface acts to retract the hydraulic
cylinder.
6. The hydraulic cylinder assembly of claim 2, wherein a retraction
of the hydraulic cylinder increases a pressure in the
accumulator.
7. The hydraulic cylinder assembly of claim 2, wherein an extension
of the hydraulic cylinder automatically lowers a pressure in the
accumulator.
8. The hydraulic cylinder assembly of claim 2, further comprising a
fourth port for charging the accumulator with a gas.
9. The hydraulic cylinder assembly of claim 2, wherein the first
accumulator port comprises a gas charge port.
10. The hydraulic cylinder assembly of claim 9, wherein the piston
progressively blocks the second accumulator port as it nears an end
of travel during an extension of the hydraulic cylinder
assembly.
11. The hydraulic cylinder assembly of claim 9, wherein the third
cylinder port comprises a drain for hydraulic fluid.
Description
FIELD OF THE INVENTION
[0001] The invention relates to hydraulic cylinders and, more
particularly, relates to hydraulic cylinders with integrated
accumulators. Such hydraulic cylinders are normally used in
off-road work vehicles, i.e., construction equipment.
BACKGROUND OF THE INVENTION
[0002] Conventional hydraulic cylinders in hydraulic circuits
utilizing hydraulic accumulators come under the following two
general categories: (1) stand alone hydraulic cylinders using
remote accumulators and (2) hydraulic cylinder assemblies formed by
integrating hydraulic cylinders with the accumulators. Addressed
herein are hydraulic cylinder assemblies.
SUMMARY OF THE INVENTION
[0003] Conventional hydraulic cylinders falling under category (1)
are separated from the remote accumulators by hydraulic equipment
having a resistance to the flow of hydraulic energy. Thus, in such
systems, the net amount of energy delivered to the conventional
hydraulic cylinder is reduced as the hydraulic fluid flows through
intervening hydraulic equipment such as hydraulic lines, spool
valves, etc. Further, any spatial considerations are amplified as
each intervening piece of hydraulic equipment, including the
accumulator tends to awkwardly consume space. For these and other
reasons, such systems suffer from the standpoint of energy and
spatial efficiency.
[0004] Conventional hydraulic cylinders falling under category (2)
tend to be bulky and awkward. The hydraulic lines and valve(s)
necessitated in arrangements for hydraulic cylinders under category
(1) are often eliminated but the accumulator is usually bulky and
awkwardly placed. The awkwardness of such an arrangement tends to
limit its usefulness, particularly on off road vehicles requiring
optimal ranges of motion and having limited space available.
[0005] Described herein is a hydraulic cylinder assembly where the
accumulator at least partially surrounds the outer cylindrical wall
of the hydraulic cylinder. The particular accumulator described is
concentric with the outer wall of the hydraulic cylinder. Thus, it
follows that the outer diameter of the accumulator decreases as the
length of cylinder wall covered increases. Such an arrangement
tends to minimize bulkiness and awkwardness of the hydraulic
cylinder assembly as what remains is a hydraulic cylinder with a
slightly larger diameter.
[0006] The accumulator described herein includes a piston that
tends to slow down as it reaches the end of travel during an
extension of the hydraulic cylinder. This feature is a cushioning
effect that minimizes the risk of shock loading from the
accumulator piston suddenly slamming into an accumulator wall at
the end of travel and results from progressive blockage, by the
accumulator piston, of flow from the accumulator to the
cylinder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The invention will be described in detail, with references
to the following figures, wherein:
[0008] FIG. 1 is an oblique frontal view of an exemplary embodiment
of the hydraulic cylinder assembly of the invention with exemplary
hosing;
[0009] FIG. 2 is an oblique rear view of the exemplary embodiment
illustrated in FIG. 1;
[0010] FIG. 3 is a sectional schematic of the hydraulic cylinder
assembly illustrated in FIGS. 1 and 2 with the exemplary hosing
removed;
[0011] FIG. 4 is another sectional schematic of the hydraulic
cylinder assembly illustrated in FIGS. 1 and 2 with the exemplary
hosing removed and fully retracted; and
[0012] FIG. 5 is another sectional schematic of the hydraulic
cylinder assembly illustrated in FIGS. 1 and 2 with the exemplary
hosing removed and fully extended.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
[0013] FIGS. 1 and 2 are oblique views of an exemplary embodiment
of the invention. FIGS. 3, 4 and 5 are schematics of the exemplary
embodiment illustrated in FIGS. 1 and 2. The embodiment illustrated
is a hydraulic cylinder assembly 100 which includes: a hydraulic
cylinder 110 having first, second and third cylinder ports 101, 102
and 104; and a hydraulic accumulator 120 that is concentric with
and integral to the hydraulic cylinder 110 having first and second
accumulator ports 103 and 105.
[0014] The hydraulic cylinder 110 includes: a piston rod 111; a
first longitudinal cylinder wall 112; a second longitudinal
cylinder wall 119; a first cylinder end wall portion 113a; a second
cylinder end wall portion 114a; a first cylinder port 101; and a
second cylinder port 102. The piston rod 111 includes: a
cylindrical rod portion 116 having an inner rod diameter A and an
outer rod diameter B; a rod end wall 117 enclosing a first end of
the cylindrical rod portion 116; and a piston ring disk 118 having
a first ring surface 118a with an inner piston ring disk diameter C
approximately equal to the inner rod diameter A and a second ring
surface 118b with an outer piston ring disk diameter D. The piston
rod 111 also includes first, second and third piston rod surfaces
111a, 111b and 111c in communication with the first cylinder port
101, the second cylinder port 102 and the third cylinder port 104,
respectively. The piston rod surface 111c is also in communication
with the second accumulator port 105. The effective area of the
first piston rod surface 111a is approximately equal to the
effective area of the second piston rod surface 111b. The effective
area is defined as the component of a surface area that is
orthogonal to a direction of movement for the part associated with
the surface area.
[0015] As illustrated in FIGS. 3, 4 and 5, the piston ring disk 118
is outfitted with a first o-ring 125 and a second o-ring 126 on its
first and second ring surfaces 118a, 118b. These o-rings 125, 126
slidably seal the interfaces between the second cylinder inner
surface 119a and the second ring surface 118b and between the first
cylinder outer surface 112b and the first ring surface 118a.
[0016] The first longitudinal cylinder wall 112 includes a first
cylinder inner surface 112a with a first cylinder inner surface
diameter E and a first cylinder outer surface 112b with a first
cylinder surface outer diameter F. The second longitudinal cylinder
wall 119 includes a second cylinder inner surface 119a with a
second cylinder inner surface diameter G and a second cylinder
outer surface 119b with a second cylinder outer surface diameter H.
An end wall o-ring 115 along an end wall inner diameter L of the
second cylinder end wall 114 slidably seals an interface between
the second cylinder end wall 114 and the piston rod 111.
[0017] The accumulator 120 includes: a piston 121 with a first
accumulator piston surface 121a, a second accumulator piston
surface 121b, a third accumulator piston wall surface 121c and a
fourth accumulator piston wall surface 121d; a first longitudinal
accumulator wall 122; a first accumulator end wall portion 113b; a
second accumulator end wall portion 114b; and a second longitudinal
accumulator wall which is, in this particular embodiment, the
second longitudinal cylinder wall 119. The first longitudinal
accumulator wall 122 includes a first accumulator wall surface 122a
with a first accumulator wall diameter J and a second accumulator
wall surface 122b with a second accumulator wall diameter K. An
inner accumulator o-ring 123 and an outer accumulator o-ring 124
slidably seal the interfaces between the first accumulator wall
surface 122a and the first accumulator piston surface 121a and
between the second cylinder outer surface 119b and the second
accumulator piston surface 121b. The third accumulator piston wall
surface 121c is in communication with the first accumulator port
103 and the fourth accumulator piston wall surface 121d is in
communication with the second accumulator port 105.
[0018] In operation, the accumulator 120 is charged with an inert
gas at the first accumulator port 103 and the hydraulic cylinder
110 and the accumulator 120 are pre-filled with hydraulic fluid at
the third cylinder port 104 and the second accumulator port 105,
respectively. The hydraulic cylinder assembly 100 is then extended
as hydraulic fluid enters the first cylinder port 101 under
sufficient pressure. As the hydraulic cylinder assembly 100
extends, the accumulator piston moves toward the first accumulator
end wall 113b and the pressure between the third accumulator piston
wall 121c and the second accumulator end wall 114b decreases as
stored energy is released.
[0019] The hydraulic cylinder assembly 100 is retracted as
hydraulic fluid enters the second cylinder port 102 under
sufficient pressure. The hydraulic cylinder assembly 100 is
retracted as hydraulic fluid enters the second cylinder port 102
under sufficient pressure and hydraulic fluid is allowed to drain
from the first cylinder port 101. As the hydraulic cylinder
assembly 100 retracts, the third piston rod cylinder wall 111c
moves toward the first hydraulic cylinder end wall 113a. This
causes hydraulic fluid to flow into the second accumulator port
105, increasing the pressure against the fourth accumulator piston
wall 121d and causing the accumulator piston 121 to increase gas
pressure against the third accumulator piston wall 121c by moving
the accumulator piston 121 toward the second accumulator end wall
114b. Hydraulic energy is stored in the accumulator as the
accumulator piston 121 moves toward the second accumulator wall.
Stored hydraulic energy is released from the accumulator 120 when
the hydraulic cylinder assembly 100 is, once again, extended and
the accumulator piston 121 moves toward the first accumulator end
wall 113b, causing hydraulic fluid to flow across the second
accumulator port 105 with pressure sufficient to act on the third
piston rod surface 111c and aid in the extension.
[0020] As illustrated in FIGS. 3, 4 and 5, the accumulator piston
121 progressively blocks the second accumulator port 105 as the
accumulator piston 121 nears the end of travel toward the first
accumulator wall 113b. This progressive restriction of the opening
slows the flow of hydraulic fluid and creates a cushioning effect
by providing a greater resistance to movement of the accumulator
piston 121 and, thus, slowing the travel rate of the accumulator
piston 121 as it nears the first accumulator end wall 113b. Such an
arrangement reducing the risk of shock loading from a slamming of
the accumulator piston 121 into the first accumulator end wall
113b.
[0021] Having described the illustrated embodiment, it will become
apparent that various modifications can be made without departing
from the scope of the invention as defined in the accompanying
claims.
* * * * *