HYDRAULIC PISTON ASSEMBLY
Technical Field
The present disclosure provides a compact high-output piston assembly
that includes multiple pistons.
Background
Hydraulic pistons are used for mechanical actuation in many
applications. The hydraulic pistons are arranged such that extending and retracting a
piston rod connected to pistons housed in a cylinder body causes a desired mechanical
action. Pressurized hydraulic fluid is directed into and out of the cylinder thereby
causing the piston rod to extend and retract. Improved high performance pistons are
desirable.
Summary
The present disclosure provides a method of assembling and
disassembling a hydraulic cylinder. In addition it provides a hydraulic cylinder that
includes a modular intermediate head construction that enable the assembly thereof
between two adjacent pistons without removing the piston from the piston rod.
Brief Description of the Figures
FIG. 1 is an isometric view of a hydraulic cylinder according to an
embodiment of the present disclosure;
FIG. 2 is a top elevation view of the hydraulic cylinder of FIG. 1;
FIG. 3 is a cross-sectional view of the hydraulic cylinder of FIG. 1;
FIG. 4 is an isometric view of a component of the hydraulic cylinder of
FIG. I;
FIG. 5 is an enlarged view of a portion of FIG. 3; and
FIG. 6 is a cross-sectional view of an alternative embodiment of a
hydraulic cylinder according to the present disclosure.

Detailed Description
Referring to the FIGS. 1-5, a first embodiment of a hydraulic piston according to
the present disclosure is described below in further detail. In the depicted embodiment,
the hydraulic cylinder 10 includes a cylinder body 12, a first intermediate head
assembly 14, and a second intermediate head assembly 16. In the depicted
embodiment, each intermediate head assembly 14, 16 is configured to enable hydraulic
fluid to simultaneously flow into and out of the cylinder body through hydraulic ports
18, 20, 22, 24 on the intermediate head assemblies 14, 16. In the depicted embodiment
the hydraulic cylinder 10 further includes a first head cap 26 located at a first end 28 of
the cylinder body 12, and a second head cap 30 located at a second end 32 of the
cylinder body 12. Each of the first and second head caps 26, 30 are configured to
enable hydraulic fluid to flow into and out of the cylinder body. It should be
appreciated that many other alternative hydraulic piston configurations are possible.
In the depicted embodiment the hydraulic piston includes a piston rod 34 that
extends coaxially into the cylinder body 12, which in the depicted embodiment is
generally cylindrical. Pistons 36, 38, 40 are supported on the piston rod 34 and slide
within the cylinder body 12 in response to hydraulic pressure due to the flow of
hydraulic fluid into and out of the heads 26, 14, 16 and 30. The pistons in the depicted
embodiment are cylindrical member that interface with the inside surface of the cylinder
body 12. In the depicted embodiment end piston 36 is positioned between the first head
cap 26 and the first intermediate head assembly 14, end piston 40 is positioned between
the second head cap 30 and the second intermediate head assembly 16, and intermediate
piston 38 is positioned between the first intermediate head assembly 14 and the second
intermediate head assembly 16. It should be appreciated that many other alternative
configurations are possible.
During normal operations to move the piston to the left, hydraulic fluid would
be allowed to escape through the first head cap 26 and be delivered to the hydraulic
cylinder through the second head cap 30. Simultaneously, ports 18 and 22 of the
intermediate head assemblies 14, 16 would deliver hydraulic fluid, and ports 20 and 24
would allow for the escape of hydraulic fluid from the cylinder body 12. Conversely, to
move the piston to the right, hydraulic fluid would be allowed to escape through the

second head cap 30 and be delivered through the first head cap 26. Simultaneously,
ports 20 and 24 of the intermediate head assemblies 14, 16 would deliver hydraulic
fluid and ports 18 and 22 would allow for the escape of hydraulic fluid from the
cylinder body 12. It should be appreciated that many other alternative hydraulic piston
configurations and modes of operation are possible (for example, the piston can be
moved to the left by delivering fluid to the cylinder body only via the second head cap
30).
In the depicted embodiment, each of the pistons 36, 38 and 40 are all integrally
formed on the piston rod 34 (includes a unitary construction). The depicted
configuration provides a system that can withslandhigh forces as it minimizes stress
concentration within the piston rod and piston assembly. It also facilitates quick and
easy assembly and disassembly. It should be appreciated that many other alternative
configurations are possible (e.g., embodiments where at least some of the pistons are
not integrally formed on the piston rod).
Assembly of the hydraulic piston 10 of the depicted embodiment can include the
following steps: positioning a cylindrical housing portion 54 of the intermediate
hydraulic head assembly 14 between a first piston 36 and a second piston38, the first
piston and the second piston being spaced apart and adjacently arranged on a piston rod
34; positioning a split bearing assembly 56 around the piston rod between the first
piston 36 and second piston 38 on the piston rod 34 in a coaxial radial overlapping
arrangement with the cylindrical housing portion 54 of the intermediate hydraulic head
assembly 14; positioning a first cylindrical body housing portion 58 around the first
piston 36 and connecting the first cylindrical body housing portion 58 to the cylindrical
housing portion 54 of the intermediate hydraulic head assembly 14; and positioning a
second cylindrical body housing portion 60 around the second piston 38 and connecting
the second cylindrical body housing portion 60 to the cylindrical housing portion 54 of
the intermediate hydraulic head assembly 14. It should be appreciated that many other
methods of assembling hydraulic pistons according to the present disclosure are
possible including some that including a different combination of steps some of the
steps being ones that are identified above as well as some other steps.

As discussed above, it should be appreciated that the above-identified assembly
steps are only one of a number of assembly methods. Also, the sequence in the above
recitation can vary as well. In one embodiment at least one of the steps of either
connecting the first cylindrical body housing portion 58 to the cylindrical housing
portion 54 of the intermediate hydraulic head assembly 14, or connecting the second
cylindrical body housing portion 60 to the cylindrical housing portion 54 of the
intermediate hydraulic head assembly 14, occurs after the step of positioning the split
bearing assembly 56 around the piston rod 34 between the first piston 36 and second
piston 38 on the piston rod 34 in a coaxial radial overlapping arrangement with the
cylindrical housing portion 54 of the intermediate hydraulic head assembly 14. For
easy assembly, the split bearing asembly 56 can be positioned between the adjacent
pistons 36 and 38 before the section of piston rod 34 between the pistons 36, 38 are
enclosed by the combination of the cylindrical housing portion 54 and the adjacent
cylindrical body housing portions 58, 60. In other embodiments the sequence of steps is
not as described above.
As already discussed above the assembly method can also include more, less, as
well as different steps, and the sequence of the steps can also vary. For example, the
method of assembly can also include the additional steps of: positioning a cylindrical
housing portion 62 of an auxiliary intermediate hydraulic head assembly (second
intermediate head assembly 16) between the second piston 38 and a third piston 40, the
second piston 38 and the third piston 40 being spaced apart and adjacently arranged on
a piston rod 34 as depicted in FIG. 3; positioning a second split bearing assembly 64 (in
the depicted embodiment the second split bearing assembly 64 has the same
construction of the first split bearing assembly 56) around the piston rod 34 between the
second piston 38 and third piston 40 on the piston rod 34 in a coaxial radial overlapping
arrangement with the cylindrical housing portion 62 of the auxiliary intermediate
hydraulic head assembly 16; positioning a third cylindrical body housing portion 66
around the third piston 40 and connecting the third cylindrical body housing 66 to the
cylindrical housing portion 62 of the auxiliary intermediate hydraulic head assembly 16;
and connecting the second cylindrical body housing 60 to the cylindrical housing
portion 62 of the auxiliary intermediate hydraulic head assembly 16.

The method of assembly can also, for example, include the additional step of:
connecting a first end hydraulic head cap (first head cap 26) to the first cylindrical body
housing portion 54, and connecting a second end hydraulic head cap (second head cap
30) to the third cylindrical body housing portion 66 of the cylinder body 12.
In some embodiments the above-identified step of positioning a split bearing
assembly 56 around the piston rod 34 in a coaxial radial overlapping arrangement with
the cylindrical housing portions 54, 62 of the intermediate hydraulic head assemblies
14, 16 includes aligning a fluid channel (a first annular hydraulic fluid channel 68) on
an exterior of the split bearing assembly with a fluid aperture (a hydraulic fluid channel
70) in the cylindrical housing portion 54 of the intermediate hydraulic head assembly
14.
It should be appreciated that the first and second intermediate hydraulic head
assemblies 14, 16 can share the same construction or have differences. In the depicted
embodiment the first and second intermediate hydraulic head assemblies share similar
features and therefore these similar features will not be described herein separately.
As discussed above, in the depicted embodiment each of the first and second
intermediate head assemblies includes a first hydraulic port and a second hydraulic port.
In the depicted embodiment the first hydraulic port 18 directs hydraulic fluid to flow
through a first hydraulic fluid channel 70. The second hydraulic port 20 directs
hydraulic fluid to flow through a second hydraulic fluid channel 72. The split bearing
assembly 56 includes a first annular hydraulic fluid channel 68 on an exterior surface of
the split bearing assembly that is in fluid communication with at least one hydraulic
fluid aperture 74, which is in fluid communication with a second annular fluid channel
76. The first and second intermediate head assemblies 14, 16 are configured such that
hydraulic fluid can flow from outside of the cylinder body 12 into the cylinder body via
a flow path that includes the hydraulic fluid channel 70 of the intermediate head
assemblies, the first annular hydraulic fluid channel 68 of the split bearing assembly,
and the at least one hydraulic fluid aperture 74 of the split bearing assembly, and the
second annular hydraulic fluid channels 76 of the split bearing assembly.It should be
appreciated that many other alternative embodiments of the intermediate heads are
possible.

In the depicted embodiment each of the first intermediate head assembly
and a second intermediate head assembly include a shoulder 78 and recess 80
configuration that secures the split bearing assemblies at least in a fixed longitudinal
position relative to the cylinder body 12. In the depicted embodiment the recess 80 in
the inner surface of the cylindrical housing portion 54 of the intermediate hydraulic
head assembly 14 is sized to receive the exterior surface 82 of the split bearing
assembly 56. When the cylindrical housing portion 54 of the intermediate hydraulic
head assembly 14 is secured to the cylindrical body portion 58 via bolts 84, the split
bearing assembly 56 is fixed laterally with respect to the cylinder body 12. The
alternative intermediate heads may or may not share some of the features of the
embodiment of the intermediate head that arc described above.
In the depicted embodiment the split bearing assembly 56 is configured to limit
fluid flow within the cylinder body 12 from a first side of the split bearing to a second
side of the split bearing. In the depicted embodiment the split bearing assembly 56
includes a fluid blocking portion 86 with an outer diameter D1 and an inner diameter
D2 that limits flow of the hydraulic fluid from traveling from adjacent fluid channels
70, 72 of the intermediate head assembly. The diameter D1 is slightly smaller than the
inner diameter of the cylindrical housing portion 54 of the intermediate hydraulic head
assembly 14, and the diameter D2 is slightly larger than the diameter of the piston rod
34. Ring seals 88 provide further scaling at the interface between the surface of the
split bearing assembly 56 and the cylindrical housing portion 54 of the intermediate
hydraulic head assembly 14. It should be appreciated that many alternative split bearing
configuration are possible.
In the depicted embodiment the first annular hydraulic fluid channel 68 is
located in a center portion of the generally cylindrical split bearing assembly and is
defined by an exterior surface that has a diameter D3 that is smaller than D1 and larger
than D2. In the depicted embodiment D3 varies, thereby forming a radiuses surface on
the split bearing assembly that cooperates with the inner surface of the cylindrical
housing portion 54 to form an annular fluid channel. In the depicted embodiment the
second annular fluid channel 76 is defined between an interior surface of the split
bearing assembly that has a radius of D4 which is greater than D2 and the exterior

surface of the piston rod 34. In the depicted embodiment, two apertures 74 and 90
connect the first and second annular fluid channels 68, 76. It should be appreciated that
many other alternative configurations are possible.
In the depicted embodiment the split bearing assembly 56 includes a first portion
and a second portion that are configured to be joined together around the piston rod
without the need to access an end of the piston rod 34. In the depicted embodiment the
split bearing portion includes a first half and a second half and each half is substantially
identical. It should be appreciated that many other configurations are possible.
As described above, in one embodiment in accordance with the present
disclosure the hydraulic piston comprises a cylinder body 12 including a first end and a
second end; a first head cap 26 is connected to the first end of the cylinder body, the
first head cap is configured to enable hydraulic fluid to flow into and out of the cylinder
body 12; a second head cap 30 is connected to the second end of the cylinder body, the
second head cap is configured to enable hydraulic fluid to flow into and out of the
cylinder body; at least one intermediate head assembly 14, 16 is connected to the
cylinder body between the first and second head caps, the intermediate head configured
to enable hydraulic fluid to simultaneously flow into and out of the cylinder body; a
piston rod assembly is coaxially arranged with the cylinder body 12 and extends
through the cylinder body, the piston rod assembly including: a piston rod 34 that
extends through the cylinder body 12, the piston rod including a first end and a second
end; a first piston 36 is integrally formed on the piston rod between the first head cap 26
and the at least one intermediate head 14,16, the first piston slidably engaged with the
cylinder body; a second piston 38 integrally formed on the piston rod between the
second head cap 30 and the at least one intermediate head 14,16; wherein the at least
one intermediate head assembly 14, 16 includes an outer housing portion 54 and an
inner split bearing portion 56, wherein the outer housing portion 54 includes inner
cross-sectional configurations that enable the first and second piston to extend
therethrough and wherein the inner split bearing portion includes at least a first portion
92 and a second portion 94 that connects together around the piston rod and extends
between the outer housing portion 54 of the intermediate head assemblies 14, 16 and the

piston rod 34. Many alternative embodiment that are in accordance with the present
disclosure are also possible.
Referring to FIG. 6, an alternative embodiment is shown. In the depicted
embodiment the intermediate head assembly includes portions 100, 102 that are integral
to different adjacent portions 104, 106 of the cylinder body. In the embodiment of FIG.
6, unlike the embodiments disclosed in FIGS. 1 -5, the intermediate head is not a
separate component that is connected to the cylinder body via fasteners. In particular,
the first hydraulic fluid port and channel 108 of the first intermediate head assembly is
integral to a first cylinder body portion 100, and a second hydraulic fluid port and
channel 110 of the first intermediate head assembly is integral to a second cylinder body
portion 102 that abuts the first cylinder body portion.
In both depicted embodiments the hydraulic cylinder 10 also includes a preload
assembly that includes end caps 42, 44 and tensioning members 46 that extend
therethrough that are configured to apply tension to the piston rod 34. In the depicted
embodiment the tension member of the preloading assembly includes a multi-jackbolt
tensioner type bolt. The multi-jackbolt is configured such that the bolt applies tension
(tightens) by torqueing multiple smaller bolts 48 located at the bolt head 52 that press
against a washer 50 and thereby together pull on the larger center bolt. It should be
appreciated that many alternative embodiments of the tensioning members 46 exist
including, for example, standard type bolts.
The above specification, examples and data provide a complete description of
the manufacture and use of the composition of the invention. Since many embodiments
of the invention can be made without departing from the spirit and scope of the
invention, the invention resides in the claims hereinafter appended.

ABSTRACT

The present disclosure provides a method of assembling and
disassembling a hydraulic cylinder. In addition it provides a hydraulic cylinder that
includes a modular intermediate head construction that enable the assembly thereof
between two adjacent pistons without removing the piston from the piston rod.