Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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HYDRAULIC HAMMER
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to and claims priority to U.S.
Non-Provisional
Patent Application Serial No. 13/784,687, filed March 4, 2013, which is hereby
incorporated
by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT.
Not applicable.
SEQUENCE LISTING.
Not applicable.
BACKGROUND
[0002] The present technology is related to a hydraulic hammer
principally for
driving piles into the earth.
DESCRIPTION OF THE RELATED ART INCLUDING INFORMATION
DISCLOSED UNDER 37 C.F.R. 1.97 and 1.98.
[0003] Many structures, including for example, buildings, piers and
the like, are
supported by piles that are driven into the ground, either dry ground or
ground that is
underwater.
[0004] Dropping a free weight of a certain weight from a certain
height is one
common technique for driving piles. An advantage of this technique is that the
force needed
to drive the pile further corresponds to the load the pile can bear in use and
well-known tables
allow builder to calculate the load bearing capacity very accurately. A
disadvantage of this
technique is that the weight must be raised a substantial height and the
lifting mechanism,
typically a crane, is even higher, requiring a good deal of space, or
headroom, available above
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the pile. Another disadvantage of this technique is that it is typically
relatively slow,
reducing productivity.
[0005] Also frequently used for driving piles are hydraulic
hammers. One
hydraulic hammer is disclosed in U.S. Patent Number 6,557,647, which describes
a hammer
having a piston cylinder inside a ram, with the stationary piston fixed to a
stationary solid
piston rod, which is fixed to the bottom of the ram. The piston forms an upper
piston
cylinder above the piston and a lower piston cylinder below the piston.
Hydraulic fluid
under pressure is forced into a lower piston chamber to raise the ram above
the pile and
hydraulic fluid under pressure is forced into the upper chamber as the ram
fall toward the
extended, or striking, position. A substantial physical portion of this device
lies outside of
the ram, increasing the headroom needed for its operation. The structure is
also
mechanically complex. It also requires several valves.
[0006] Therefore, there is a need for a low headroom hammer that is
a hydraulic
hammer.
BRIEF SUMMARY
[0007] An attempt with the present technology is to provide a
nearly free-fall
hydraulic hammer that has a faster cycle time than conventional hammers and,
in some
embodiments, to provide a low-headroom hydraulic hammer.
[0008] It is another desire in creating the present technology to
provide a
hydraulic hammer that requires less energy to operate than similar
conventional hammers.
[0009] Another goal when creating the present technology is to
provide a nearly
free-fall low headroom hydraulic hammer that has a smaller overall weight than
comparable
hammers of similar impact.
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[0010] A further interest when creating the present technology is
to provide a
nearly free-fall low headroom hydraulic hammer that has a low headroom,
permitting its use
in situations where a hammer cannot be raised high above the pile to be
driven, i.e., a low
headroom environment.
[0011] A yet further interest when creating the present technology is to
provide a
nearly free-fall low headroom hydraulic hammer that mimics the impact force of
a true
free-falling hammer or weight, which have very precise driving property tables
for calculating
pile load bearing factors, allowing the present hammer to utilize these well-
developed load
tables.
[0012] These and other aspects are considered by providing a nearly free-
fall
hydraulic hammer, which may be a low-headroom hydraulic hammer, in which a ram
having
a piston cylinder inside it is lifted by pumping hydraulic fluid into the
chamber above a
stationary piston and then dropping the ram by relieving the pressure on the
hydraulic fluid.
The low-headroom hydraulic hammer is made a relatively short and therefore,
low headroom,
hammer by having the cylinder and the piston located entirely inside the ram
or actuator. A
closed sealed compressed gas chamber in the piston cylinder below the piston
and continuing
up into a hollow piston rod provides a spring-like bounce to accelerate the
outflow of the
hydraulic fluid from the chamber above the piston. In one embodiment a sealed
cylindrical
shuttle member inside the hollow piston connecting rod reciprocates between an
upper stop
member and a lower stop member, to change the gas pressure inside the sealed
gas chamber
and also serves as a barrier between the hydraulic fluid and the gas, keeping
them separated.
In another embodiment, the shuttle member is omitted and only a single working
fluid, a
hydraulic fluid is used. In another embodiment a receptacle, resembling a
bucket or other
convenient shape, is connected to the bottom of the piston to old hydraulic
fluid and thereby
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reduce the volume of hydraulic fluid that must be pumped, thereby reducing the
cycling time
for a give size hydraulic pump and increasing the efficiency of the hydraulic
hammer. In all
embodiments, the ram of the hammer moves between a first position, which is
the ram at its
maximum lift point above the pile, which is predetennined, and a second
position, which is
the lowest position of the ram, i.e., the striking position.
[0013] Other aspects of the present technology will become apparent
from the
following description taken in connection with the accompanying drawings,
wherein is set
forth by way of illustration and example, the preferred embodiment and the
best mode
currently known to the inventor for carrying out the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0014] Fig. 1 is a cross section side view of a first embodiment of
a hydraulic
hammer (hammer) according to the present invention having a reciprocating
shuttle member
inside a hollow piston rod and showing the hammer at the completion of a
downward strike
on a pile or the like in equilibrium, at rest and ready to begin the lifting
stroke of its cycle,
that is, in a second position.
[0015] Fig. 2 is a cross section side view of the hammer of Fig. 1
at the beginning
the hammer lifting stroke.
[0016] Fig. 3 is a cross section side view of the hammer of Fig. 1
shown at a
position during the lifting stroke of the ram.
[0017] Fig. 4 is a cross section side view of the hammer of Fig. 1 shown at
the
top of its predetermined height and the beginning of the falling stroke of the
ram, that is, in a
first position.
[0018] Fig. 5 is a cross section side view of the hammer of Fig. 1
shown during the
falling stroke of the ram.
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[0019] Fig. 6 is a cross section side view of the hammer of Fig. 1
shown at the end
of the falling stroke, having made impact with the pile or other driven
object, at which point,
the hammer is returned to the configuration of Fig. 1, in equilibrium, at rest
and ready to
begin another cycle.
[0020] Fig. 7 is a cross section taken along lines 7-7 of Fig. 1 or Fig. 8.
[0021] Fig. 8 is a cross section side view of another embodiment of
a hydraulic
hammer (hammer) according to the present invention showing the hammer at the
completion
of a downward strike on a pile or the like in equilibrium, at rest and ready
to begin the lifting
stroke of its cycle.
[0022] Fig. 9 is a cross section side view of the hammer of Fig. 8 at the
beginning
the hammer lifting stroke.
[0023] Fig. 10 is a cross section side view of the hammer of Fig. 8
shown at a
position during the lifting stroke of the ram.
[0024] Fig. 11 is a cross section side view of the hammer of Fig. 8
shown at the
top of its predetermined height and the beginning of the falling stroke of the
ram.
[0025] Fig. 12 is a cross section side view of the hammer of Fig. 8
shown during
the falling stroke of the ram.
[0026] Fig. 13 is a cross section side view of the hammer of Fig. 8
shown at the
end of the falling stroke, having made impact with the pile or other driven
object, at which
point, the hammer is returned to the configuration ofFig. 8, in equilibrium,
at rest and ready
to begin another cycle.
[0027] Fig. 14 is a cross section side view of another embodiment
hydraulic
hammer, in which a cylinder having a closed lower end is attached to the lower
surface of a
piston, i.e., forming a receptacle resembling a bucket, suspended beneath the
piston and
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reciprocating within a well below the otherwise normal floor of the piston
cylinder to reduce
the volume of fluid that must be removed from the cylinder space below the
piston, according
to the present invention showing the hammer at the completion of a downward
strike on a pile
or the like in equilibrium, at rest and ready to begin the lifting stroke of
its cycle.
[0028] Fig. 15 is a cross section side view of the hammer of Fig. 14 at the
beginning the hammer lifting stroke.
[0029] Fig. 16 is a cross section side view of the hammer of Fig.
14 shown at a
position during the lifting stroke of the ram.
[0030] Fig. 17 is a cross section side view of the hammer of Fig.
14 shown at the
top of its predetermined height and the beginning of the falling stroke of the
ram.
[0031] Fig. 18 is a cross section side view of the hammer of Fig.
14 shown during
the falling stroke of the ram.
[0032] Fig. 19 is a cross section side view of the hammer of Fig.
14 shown at the
end of the falling stroke, having made impact with the pile or other driven
object, at which
point, the hammer is returned to the configuration of Fig. 8, in equilibrium,
at rest and ready
to begin another cycle.
[0033] Fig. 20 is a cross section side view of another embodiment
hydraulic
hammer of Fig. 14, in which a lid seals the receptacle attached beneath the
piston
reciprocates within a well below the otherwise normal floor of the piston
cylinder to reduce
the weight of fluid that reciprocates, showing the hammer at the completion of
a downward
strike on a pile or the like in equilibrium, at rest and ready to begin the
lifting stroke of its
cycle.
[0034] Fig. 21 is a cross section side view of Fig. 14 showing an
alternative
embodiment of the hydraulic hammer of Fig. 1 or Fig. 14 in which a cylinder
sleeve 17
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forming a piston cylinder is only loosely seated in a bore in the ram and the
space between
these elements is filled with a fluid such as oil a first embodiment of a
hydraulic hammer
(hammer) according to the present invention having a reciprocating shuttle
member inside a
hollow piston rod and showing the hammer at the completion of a downward
strike on a pile
or the like in equilibrium, at rest and ready to begin the lifting stroke of
its cycle.
[0035] Fig. 22 is a cross section side view of an alterative
embodiment of the
hammer having a reciprocating shuttle member inside a hollow piston rod as
shown in Fig. 1
and the reciprocating receptacle resembling a bucket suspended below the
piston and
reciprocating with in a well below the otherwise normal floor of the piston
cylinder as shown
io in Fig. 14, showing the hammer at the completion of a downward strike on
a pile or the like
in equilibrium, at rest and ready to begin the lifting stroke of its cycle.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Referring to Fig. 1, a hydraulic hammer 10 ("hammer" 10), in
an
embodiment illustrated in Figs. 1-7 which is a low headroom hammer, is mounted
on a frame
or saddle 12, which is preferably a spherical bearing connection and manifold,
resting on a
suitable supporting surface frame 15 above the pile 14 that is to be driven,
or other suitable
object to be driven, as the case may be. A hallmark of the hammer 10 is that
the piston
cyclinder 24 is formed wholly inside the ram 16, with only a cylinder head 48
projecting
above the top surface of the ram 16, which allows the hammer 10 to be a low-
headroom
hammer for any given capacity of the hammer 10. The hammer 10 includes an
"outer casing
of the actuator" 16, that is a ram 16, which may be cylindrical or other
desired cross section
shape and that may include an inwardly tapered reduced neck portion 18,
terminating in a
reduced size impact or bottom portion 20 having a face 22 for striking the top
surface of the
pile 14. The face 22 may be flat, or have a convex dished shape. The hammer 10
may
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employ a conventional external frame (not shown), which is connected to the
support frame
15 and which is principally cylindrical and encloses the vertical portion of
the hydraulic
hammer 10, with suitable guide rails to insure that the ram portion falls and
rises along a
desired straight path and may also include a suitable striker member (not
shown) interposed
between the ram 16 and the pile 13 to cushion the blow and prevent damage to
the top of the
pile 13.
[0037] Still referring to Fig. 1, the ram 16 is shown in a second
position, that is, a
striking position and is show Fig. 1 at the end of the striking position, that
is, without
significant pressure in the hammer 10. A piston cylinder 24, having a bottom
wall 25
connected to a cylindrical side wall 27, is formed inside the ram 16. The top
of the piston
cylinder 24 is sealed by a cylinder head 48. The piston cylinder 24 may be
foimed integrally
into the ram 16 or preferably consists of a sleeve 17 having a connected
bottom wall 25 that is
inserted into a cavity 19 in the ram 16 to form the piston cylinder 24 and may
be sealed by
press-fitting or the like, permitting the use of a sleeve 17 and connected
bottom wall 25 of a
different material that the ram 16 for longer life, more accurate machining,
replacement and
the like. In an alternative embodiment discussed in detail below, the sleeve
17 and
connected bottom wall 25 assembly is suspended within the cavity 19 in the ram
16 with an
annular space between these two members, which may be partially filled with
oil or other
fluid. The piston cylinder 24 is a double-acting cylinder with an accumulator.
Enclosed
within the piston cylinder 24 is a piston 26 that is connected to a lower end
38 of a hollow
piston rod cavity 28. The upper end 23 of the hollow piston rod, which is
preferably tubular,
is fixed to an upper portion of the frame 12, so that the hollow piston rod 28
does not
reciprocate. The piston 26 is sealed against the piston cylinder 24 by
suitable piston ring
seals to prevent the flow of fluids around the circumference of the piston 26,
i.e. to prevent
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bypass or blow-by of fluids. Inside the hollow piston rod 28 is a freely
moving shuttle
member 30 that reciprocates in response to changes in gas pressure below it
and liquid fluid
pressure above it, with freedom to move constrained only the friction of its
seals against the
hollow piston rod 28. The shuttle member 30 is a small solid cylindrical
member that is
preferably made of steel, brass or the like and, in a typically sized hammer,
is about 15 cm (6
in.) long and about 5.5-7.75 cm (2.5-3 in.) in diameter and weighs about 14-16
kilograms
(30-35 pounds), depending on the size of a particular hammer 10 and its
desired stroke
length, etc. The shuttle member 30 fits into the longitudinal cylindrical
cavity of the hollow
piston rod 28, i.e., the cavity 40 (see especially Fig. 7). The shuttle member
30, which
io operates as a hydraulic accumulator, i.e., to store energy and reduce
system shock, is fitted
with appropriate seals to block the flow of fluids past it in either
direction. The shuttle
member 30 is free to float between an upper stop member 32 that is adjacent to
the top end 34
of the piston rod 28 and a lower stop member 36, located adjacent to the lower
end 38 of the
piston rod 28. The upper stop member 32 and the lower stop member are
preferably rings set
into mating grooves in the inner surface of the hollow piston rod 28 and serve
to constrain the
reciprocal movements of the shuttle member 30. In Fig. 1, the shuttle member
30 is shown
in its highest position, creating the lowest gas pressure of the cycle of
lifting and falling and at
its lowest position in Fig. 6, creating the highest gas pressure of the cycle
of lifting and
falling.
100381 Still referring to Fig. 1, the piston 26 is fixed to the lower end
38 of the
piston rod 28 and these members are always stationary. It is the ram 16 that
moves up to a
first or raised position (shown at its maximum height in Fig. 4) and down
relative to the
piston 26 and piston rod 28, that is down to its second or lowest or striking
position in which
the ram 16 strikes the top of the pile 14 (as first shown in Fig 1). The
cylinder reciprocates
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up and down relative to the piston 26. The piston cylinder 24 and the ram 16
that encloses
and carries the piston cylinder 24 reciprocates by sliding up or down along
the piston 26.
This is the opposite of an ordinary internal combustion engine or a pump in
which the engine
block is stationary and the piston reciprocates inside a stationary cylinder
and it is opposite of
every existing hydraulic ram known the inventors of the present invention.
Also opposite is
that the piston rod 28 is stationary and that it does not transfer any power
to another part such
as a crankshaft. Conceptually, the piston cylinder 24 is the ram 16, or the
piston cylinder 24
is formed in the ram 16 itself, however one wishes to view the structure. In
either way of
visualizing the structure of the hammer 10, the piston cylinder 24
reciprocates along a
stationary piston 26. The length of the lift and subsequent fall of the ram,
i.e., its stroke, is
about 1.1 meters (4 feet), but it can be designed to longer or shorter, as
desired.
[0039] Still referring to Fig. 1, the hammer 10 includes two
separate fluid
chambers for permitting fluid flows that raise and lower the ram 16. The
interior volume 40
of the hollow piston rod 28 below the shuttle member 30, and of the lower
piston chamber 29,
which is the volume of the piston cylinder 24 above the bottom wall 25 of the
piston cylinder
24 and the lower surface 31 of the piston 26, both of which vary throughout a
cycle, is filled
with a substantially inert gas, preferably Nitrogen (to prevent Oxygen and oil
from possibly
forming an explosive mixture and to prevent water foimation) and operating at
about 1,725
kPa (250 psi) in a closed system in which the top end is defined by the
shuttle member 30,
which is fitted with suitable seals to minimize leakage of the gas past it.
This gas is
indicated by the numeral 41, which designates a variable volume cavity 41, and
is shown by
stippling, with the volume of the varying volume cavity 41 varying during the
cycles shown
by the stippled area in the drawings, i.e, the greatest volume is at the
lowest point or striking
point of the ram 16, e.g., Fig. 1, and the smallest volume at the top of the
stroke, or highest
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point of the ram 16, e.g., Fig. 4, that is, when the piston 26 is closest to
the bottom wall 26 of
the piston cylinder. The variable volume 41 is formed by the lower piston
chamber 29 and
the hollow piston rod cavity 28 up to the lower surface of said shuttle member
30, with the
lower piston chamber 29 and the said hollow piston rod cavity 28 being in
fluid
communication with each other.
These observations apply to all embodiments in this paper. Alternatively, in
all
embodiments, the working fluid may be water, which may be any water locally
available,
including salt water. The variable volume of the lower piston chamber 29 and
the cavity in
the hollow piston rod 28 up to the lower surface 66 of the shuttle member 30
combine to form
io a single sealed chamber, whose volume changes as the position of the ram
16 changes within
the cylinder. Gas is added to this closed system only to maintain the desired
pressure in the
system. The enclosed volume of the system increases and deceases as the
shuttle member 30
moves up and down inside the hollow piston rod 28 and as the lower piston
chamber 29
moves up and down. The lower piston chamber 29 and the portion of the cavity
of the
hollow piston rod 28 below a lower surface 66 of said shuttle member 30
together form the
sealed cavity that is filled with a substantially inert gas under pressure,
e.g. Nitrogen.
[0040] Still referring to Fig. 1, a hydraulic fluid conduit tube 42
is concentric with
and larger in diameter than the hollow piston rod 28, as best seen in Fig. 7,
and is larger in
diameter than the hollow piston rod 28 and is open to the top surface 44 of
the piston 26
throughout the area of the cross section of the hydraulic fluid conduit tube
42 that is outside
the cross section area of the hollow piston rod 28, that is, in the tube
passageway 46. The
hollow piston rod 28, the hydraulic fluid conduit tube 42 and the variable
cylinder volume
above the top surface 44 of the piston 28 are sealed by a top wall 48, that
is, a cylinder head
48. The passageway 46 opens into the larger diameter cylinder volume 50 above
the top
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surface of the piston 28. The hydraulic fluid conduit tube 42 is connected to
a high pressure
line 52 that is connected to a supply of hydraulic fluid pressurized by a high
pressure pump
54. A pressure relief line 56 is connected to a pressure relief tank 58 at
its distal end 60 and
to the hollow piston rod 28 at its proximal end 62. The shuttle member 30
seals the
hydraulic fluid from the gas, with the hydraulic fluids always contained above
the top surface
64 of the shuttle member 30 and the gas always contained below the bottom
surface 66 of the
shuttle member 30. A directional valve 68 allows (open) or disallows (closed)
the flow of
hydraulic fluid from the high pressure hydraulic fluid line 52 to the pressure
relief line 56 and
thereby controlling whether or not high pressure hydraulic fluid flows into
the volume space
50 above the top surface 44 of the piston 26. The flow of high-pressure
hydraulic fluid into
the upper piston chamber 50, exerting a downward force on the top surface 44
of the piston
28, and an upward force on the cylinder head 48. Since the piston cannot move,
the
increasing volume of high pressure hydraulic fluid in the variable space 50
requires that the
cylinder head 48 and the attached ram 16 must be lifted up.
[0041] Still referring to Fig. 1, the upper piston chamber 50, at its
maximum
volume, is filled with hydraulic fluid, which may be any substantially
incompressible fluid,
such as petroleum oil or water, which requires less fluid that comparable
prior art hydraulic
hammers of similar size, resulting in more efficient hydraulic hammers. The
use of reduced
volumes of hydraulic fluid allows the use of a smaller capacity high pressure
hydraulic fluid
pump 54, reducing the energy needed to raise the ram 16, and to faster cycle
times, decreasing
the time needed to drive a particular pile 14, both increasing the efficiency
of the overall pile
driving operation.
[0042] As shown in Fig. 1, the directional valve 68 is open, so
there is no pressure
in the high pressure hydraulic line 52, the volume of the piston cylinder
chamber 50 above the
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piston 26 and below the cylinder head 48 is at its minimum volume and the
shuttle member
30 is at its highest point, that is, pushing against the upper stop member 32,
so the gas
pressure in the lower piston chamber 29 is at its lowest while the lower
piston chamber 29 is
at the largest volume it will reach during any portion of a cycle. The
variable volume cavity
41, indicated by stippling in the relevant drawings, is at its maximum. In
this configuration,
the ram 16 has just struck the pile 14 and the hammer 10 is at rest and in
equilibrium, ready to
being the next cycle.
100431 Referring to Fig. 2, the directional valve 68 closed, allowing the
hydraulic
pump 54 to pressurize the hydraulic fluid in the line 52, causing the
hydraulic fluid to flow
io along the direction of the arrows 70 and then into the passageway 46 of
the hydraulic fluid
conduit tube 42 and then into the upper piston chamber 50, thereby exerting
downward force
on the top surface 44 of the piston 26. Since the cylinder head 48 is
stationary, the resulting
forces on the hydraulic fluid and its increased volume force the ram 16 to
move upward,
lifting the face 22 of the ram 16 above the pile 14. At the same time, the gas
in the lower
piston chamber 29 and the interior of the hollow piston rod 28 is being
compressed, as the
volume of the lower piston chamber 29 decreases, forcing the shuttle member 30
to remain
pressed against the upper stop member 32. The volume of the upper piston
chamber 50 and
the volume of the lower piston chamber 29 change in inverse direct proportion
to one another.
This lifting step continues until the desired amount of lift is achieved,
which may be any
amount from zero, i.e., face 22 now being lifted free from the top of the pile
14, up to the
maximum lift stroke allowed by the design of a particular ram 16 of particular
capacity and
lift, but generally being a typical lift of about 3.5 meters (4 feet), which
can be controlled by
opening the directional valve 68 when the desired about of lift has been
achieved. This
flexibility in operation allows the hammer 10 to be operated to produce any of
a wide range
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of forces that might be desired on a particular job. Naturally, hammers 10 of
different sizes
will have different, appropriate, maximum lifts.
[0044] Referring to Figs. 3, 4 the lifting step of the process of
Fig. 2, that is,
pumping high pressure hydraulic fluid into the passageway 46 of the hydraulic
fluid conduit
tube 42 and then into the upper piston chamber 50, continues and the volume of
the upper
piston chamber 50 increases as the volume of the hydraulic fluid in it
increases and the
volume of the lower piston chamber 29 continues to decrease, raising the ram
16
progressively until the desired predetermined height is reached, as shown in
Fig. 3.
[0045] Referring to Fig. 4, the desired predetermined height of the
ram 16 has been
io achieved and the ram 16 is now in a first position, and at that point,
the directional valve 68 is
opened, providing an alternative and un-pressurized path for the hydraulic
fluid flowing from
the high pressure hydraulic pump 54 and for the pressurized hydraulic fluid in
the high
pressure hydraulic fluid line 52, the hydraulic fluid conduit tube 42 and the
upper piston
chamber 50. The variable volume cavity41 is here at its minimum volume and
hence at its
greatest pressure. All the hydraulic fluid in these cavities flows toward the
pressure relief
line 56 and the connected pressure relief tank 58, immediately releasing all
the pressure in
these cavities, i.e., all the pressure and the volume of hydraulic fluid that
has been forcing the
ram 16 into the top-of-its-stroke position shown in Fig. 3, causing the entire
reversal of the
flows of hydraulic fluid previously described so that the hydraulic fluid
flows along the lines
of the reverse direction directional arrows 72. As hydraulic fluid flows
through the open
directional valve 68, some of it flows through the pressure relief line 56 to
the top surface 64
of the shuttle member 30 along the pressure relief directional flow arrows 74,
i.e., toward the
left-hand side of Fig. 4 as shown. The shuttle member 30 thereby provides a
movable seal
on the vessels that contain the hydraulic fluid, which becomes important in
the downstroke of
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the ram 16. Other portions of the hydraulic fluid flow toward the right-hand
side of Fig. 4 as
shown, through the pressure relief line 56 to the pressure relief tank 58 as
shown by the
pressure relief tank flow directional arrows 76, assuring that the high
pressure pump 54
cannot contribute to any hydraulic pressure in the upper piston chamber 50.
Combining the
stopping of applying more hydraulic fluid pressure into the upper piston
chamber 50 and
relieving the existing pressure via the pressure relief line 56 removes the
forces that keep the
ram 16 suspended above the pile 14, causing the ram 16 to fall.
[0046] Referring to Fig. 5, the ram 16 is essentially falling in
free-fall and is
accelerating at approximately the rate of gravitational acceleration, aided by
the additional
io force developed by the compressed gas in the variable volume cavity 41
acting on the lower
surface of the piston 26. As the ram 16 falls, the volume of the lower piston
chamber 29
increases, causing the gas pressure within the sealed system of the lower
piston chamber 29
and the interior of the hollow piston rod 40 to decrease. The decreased gas
pressure is
eventually insufficient to support the shuttle member 30 against the upper
stop member 32, as
shown in Fig. 4, so the shuttle member 30 falls within the hollow piston rod
40, which creates
a certain amount of downward force, that is, the production of a lower
pressure in the variable
volume cavity 41 as the variable volume 41 expands due to the falling of the
ram 16. At the
same time, the hydraulic fluid is flowing along the direction of the
directional arrows 74,
creating downward force on the shuttle member 30, which in turn aids in
drawing out
hydraulic fluid from the upper piston chamber 50 faster than would occur if
the only pressure
relief were to provide a zero pressure pressure relief line. Because the gas
in the lower
piston chamber 29 and hollow piston rod 40 is sealed and the pressure on it
varies only due to
movement of the ram 16 relative to the piston 26 and the up or down position
of the shuttle
member 30 inside the hollow piston rod 40, the shuttle member 30 reciprocates
up and down
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as the lower piston chamber increases or decreases. Since the gas is
compressible, the
movement of the shuttle member 30 acts like a spring, drawing further pressure
off of the
hydraulic fluid during the falling ram 16 step of the cycle and allowing the
ram 16 to fall
more nearly at the speed of gravity, since less of the gravitational drop
energy is used to
extract hydraulic fluid from the upper piston chamber 50 than would otherwise
be the case.
The movement of the shuttle member 30 and ram 16, which vary the volume of the
sealed
chamber 29 provides a spring action in the form of a downward force to
accelerate the
emptying of hydraulic fluid from the upper piston chamber 50. The magnitude of
the
downward force of the compressing gas on the ram 16 in the sealed chamber 29
can be
io controlled or modified by setting the pre-load or static equilibrium
pressure int the sealed
chamber 29 (and the also sealed volume of the interior of the hollow piston
rod cavity 28
below the shuttle member 30, which varies throughout an up and down cycle of
the ram 16,
as described above) at the beginning of the lifting step of the cycle, as
shown, for example, in
Fig. 2.
[0047] Referring to Fig. 6, in the time between the positions of the parts
shown in
Figs. 5, 6, the ram 16 has continued its fall until, as shown in Fig. 6, the
shuttle member 30
being drawn downward to its lowest point where it contacts the lower stop
member 36, which
also marks the largest volume of the lower piston chamber 29 and the lowest
resulting gas
pressure within the lower piston chamber, simultaneously exerting the
strongest sucking force
on the hydraulic fluid that now fills the volume 40 of the hollow piston rod
28 as the shuttle
member 30 falls toward the lower stop member 36. At the moment that the
shuttle member
strikes the lower stop member 36 and the ram 16 strikes the pile 14, the
hammer 10 is
again at rest and equilibrium and ready for the start of the next stroke,
which is initiated by
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closing the directional valve 68 and once again forcing hydraulic fluid into
the upper piston
chamber 50 to force the ram 16 to rise.
[0048] Referring to Figs. 8-13 and 7, an alternative embodiment of
the hammer 10
is shown. This embodiment is a low headroom hammer. The structure of this
embodiment
is identical to the structure of the embodiment of Fig. 1-7 except that the
shuttle member 30
and the related stops 32, 36, 38 are omitted. This change leads to a single
fluid hydraulic
hammer, which is again any suitable substantially incompressible fluid, such
as oil, hydraulic
fluid, water or the like. The steps involved in the cycling of the embodiment
of Figs. 8-13
are identical to those described above in detail relative to the embodiment of
Figs. 1-7, but the
o fluid flows are different due to the use of a single fluid and these are
described immediately
below. This embodiment requires a higher pressure hydraulic system than the
embodiment
shown in Figs. 1-6 to achieve the same cycle times because a greater weight or
mass of
hydraulic fluid must be moved.
[0049] As shown in Fig. 8, the hammer 10 is at rest, the
directional valve 68 is
open and there is no pressure or fluid flow inside the hammer 10 or the high-
pressure
hydraulic fluid line 52 leading to it or the pressure relief line 56 leading
away from it.
[0050] Referring to Fig. 9, the directional valve 68 is closed,
causing the flow from
the high-pressure hydraulic fluid pump 54 to flow through the line along the
directional
arrows 70 and into and down the tube 42 and into the upper piston chamber 50,
thereby
increasing the volume of the upper piston chamber 50 as it fills with fluid
and thereby pulling
the ram or actuator 16 up, beginning the lift portion of the cycle. At the
same time, the
hydraulic fluid inside the lower piston chamber 29 beneath the piston 26 is
forced upwardly
through the hollow piston rod cavity 28 along the path of the directional
arrows 90 and
through the pressure relief line 56 and to the pressure relief tank 58. The
advantage of this
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embodiment over the embodiment of Figs. 1-6 is that in the present embodiment,
the
elimination of the shuttle member reduces the complexity of the hammer 10 and
the necessity
of providing separate gas and liquid fluid compartments and the necessity of
using a
substantially inert gas to prevent possible explosions. The advantage of the
embodiment of
Figs. 1-6 to this embodiment is that the embodiment of Figs. 1-6 can be
expected to have
faster cycle times and achieve closer to free-fall operation because in this
embodiment of
Figs. 1-7, a smaller volume of hydraulic fluid is used and there is the
previously described
air-spring effect that encourages the downward movement of the hammer 10 when
it is
dropped.
[0051] Referring
to Fig. 11, at the predetermined desired height of the ram 16, the
directional valve 68 is opened, relieving all the pressure on inside the
hammer 10, causing the
hydraulic fluid to flow upward through the tube 42 along the lines of the
directional arrows
92 and into the high-pressure hydraulic fluid line 52. At the same time,
pressurized
hydraulic fluid from the high-pressure hydraulic pump 54 flows into the high-
pressure
hydraulic fluid line 52 along the path indicated by the directional arrows 94.
Flows along the
directional arrows 92 and 94 merge as they flow through the open directional
valve 68
indicated by the merge arrow 96, causing the flow of hydraulic fluid through
the pressure
relief line 56 along the direction of the arrows 98 and thereby downwardly
through the hollow
piston rod cavity 28 and into the lower piston chamber 29, causing the volume
of the lower
piston chamber 29 to increase. Relieving the hydraulic fluid pressure on the
top of the piston
26 in the upper piston chamber 50 allows gravity to cause the ram 10 to fall,
with the
pressurized hydraulic fluid flowing into the lower piston chamber 29
accelerates the fall,
helping overcome frictional losses and so forth.
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[0052] Fig. 12 shows the hammer 10 in the falling portion of the
cycle farther
down toward the pile 14, with the fluid flows shown in Fig. 11 continuing.
[0053] Fig. 13 shows the hammer 10 returned to its equilibrium
position at impact,
that is with no hydraulic pressure inside the hammer 10 at impact.
[0054] Referring to Fig. 14, another embodiment of the hammer is shown in a
the
form of a modification that can be used with the embodiment of Figs. 1-6 or
the embodiment
of Figs. 8-14. As shown in Fig. 14, a cylinder having a closed lower end is
attached to the
lower surface of a piston, i.e., forming a receptacle 78, which resembles a
bucket, suspended
beneath the piston 26 and reciprocating within a well 82 below the otherwise
normal floor of
to the piston cylinder to reduce the volume of fluid that must be removed
from the cylinder
space below the piston, that is in the lower piston chamber 29, showing the
hammer 10 at the
completion of a downward strike on a pile or the like in equilibrium, at rest
and ready to
begin the lifting stroke of its cycle. The receptacle 78 is attached to the
lower surface of
the piston 26 by welding 80, but may be connected by any convenient means,
such as
threaded connection, brazing, bolting and the like. A plurality of
perforations 81 are formed
into an upper end of the receptacle 78 to allow the flow of hydraulic fluid
from inside the
receptacle 78 to outside the receptacle 78 and into the annular volume outside
the receptacle
78, although there will be little flow, see below. Cut into the bottom wall 25
of the piston
cylinder and into the ram 10 is a well 82, directly beneath the receptacle 78.
Suitable seals in
the bottom wall 25 prevent leakage of fluids around the perimeter of the
receptacle 78, which
reciprocates in tandem with the piston 26. This is not a low headroom
embodiment, since
the overall length must be greater in order to accommodate the well 82. The
advantage of
this embodiment is that the hydraulic fluid that is captured in the receptacle
78, which
remains substantially static at all times, need not be pumped out of the lower
piston chamber
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29 during any portion of the cycle of lifting and falling, reducing the amount
of hydraulic
fluid that must be pumped, thereby reducing cycle times for a given capacity
hydraulic pump
54. The disadvantages of this embodiment are that it is more complicated to
build and
maintain and likely cannot be made a low headroom hammer of substantial impact
power.
[0055] Still referring to Fig. 14, as shown in Figs. 14-19, this embodiment
is
shown without the shuttle member 30, upper stop member32 and lower stop member
36 as
previously disclosed in relation to Figs. 8-13, but this modification can also
be used with the
embodiment of Figs. 1-6. In either case, the fluids and the fluid flows are
the same as
described above in connection with their respective embodiments. When this
modification is
used with the embodiment of Figs. 1-6, the shuttle member 30 and its upper
stop member 32
and lower stop member 36 are included. When the embodiment of Fig. 14 is used
with the
embodiment of Figs. 8-13, the shuttle member 30 and its upper stop member 32
and lower
stop member 36 are omitted and a single working fluid is used and the fluid
flows are those
described above in connection with Figs. 8-13.
[0056] Referring to Fig. 15, at the beginning of the lifting of the ram 16,
the fluid
flows are the same as those shown in Fig. 9 and as described in the
description of Fig. 9.
[0057] Referring to Fig. 16, the lifting of the ram is continued
and the fluid flows
are those shown in Fig. 10 and as described in connection with Fig. 10.
[0058] Referring to Fig. 17, the ram 16 has reached its
predetermined desired
height and the directional valve 68 is opened, changing the fluid flows to
those shown in Fig.
11 and described in connection with Fig. 11.
[0059] Referring to Fig. 18, the fluid flows shown in Fig. 17
continue, allowing the
ram 16 to continue its descent.
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[0060] Referring to Fig. 19, the directional valve 68 remains open,
and the ram 16
has continued to fall until it strikes the pile 14 and is ready for the next
cycle, initiated by
closing the directional valve 68.
[0061] Referring to Fig. 20, in a modification of the embodiment of
Fig. 19, a lid
84 is sealed across the top of the receptacle 78 during manufacturing, sealing
a substantially
inert gas such as Nitrogen inside, thereby reducing the weight of the
receptacle 78 and
contents, thereby reducing the reciprocating weight of the piston 26 and the
receptacle 78 and
its contents.
[0062] Referring to Fig. 21, there is shown an alternative
embodiment of the
hammer 10 in which the sleeve 17 and connected bottom wall 25 assembly is
suspended
within the cavity 19 in the ram 16 with an annular space 100 between these two
members,
including between the bottom wall 25 of the sleeve 17 and bottom wall 25
assembly and a
bottom wall 102 of the cavity 19, which is partially filled with oil or other
fluid. The oil fills
the annular space 100 nearly to the lower surface of the cylinder head 48, but
a significant gas
gap is preserved so that the oil can slosh around. This arrangement makes the
piston 26 and
piston cylinder 24 self-aligning with the ram 16, that is, in the case that,
for whatever reason,
the ram 16 and piston 26 and piston cylinder 24 are urged to move along
somewhat different
lines, the annular space 100 and oil 88 allow for this state without damaging
either the ram 16
or the piston 26 and piston cylinder 24 assembly and further, urges these
members back into
vertical alignment.
[0063] Referring to Fig. 22, the modification of Fig. 14, that is,
including the
receptacle 78 and the well 82, is shown in use with the embodiment of Figs. 1-
6, that is the
embodiment utilizing the shuttle member 30 and its upper and lower stop
members 34, 36.
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The stages of the reciprocating cycle and the fluids flows are therefore
identical to those
shown in Figs. 1-6 and as described above in connection with Figs. 1-6.
[0064] The hammer 10 has shorter cycle times than related hammers
of similar
striking capacity and uses less hydraulic fluid and a smaller capacity
hydraulic pump. The
embodiment utilizing the shuttle member 30 uses less energy than a now
standard hydraulic
hammer due to the use of the gas chamber actuating the moveable shuttle
member, providing
a spring effect to more quicky and efficiently empty the upper piston chamber
of hydraulic
fluid for the nearly free-fall gravity operated downstroke. The embodiment
utilizing the
receptacle reciprocating in the well also uses less energy than a now standard
hydraulic
io hammer because the volume and weight of hydraulic fluid that must be
exhausted from the
chamber beneath the piston is reduced. The hammer 10, in, for example, the
embodiment
shown in Figs. 1-6, is also a very low headroom hammer due to the advancement
of forming
the piston cylinder inside the ram itself
[0065] Broadly, this writing discloses at least the following. A
piston cylinder is
formed inside a ram and is fitted with a piston attached to a stationary
hollow piston rod,
creating an upper piston chamber for receiving pressurized hydraulic fluid,
which causes the
ram to rise as the volume of the upper piston chamber is expanded due to the
hydraulic
pressure and increasing volume of hydraulic fluid. When the ram reaches a
predetermined
desired height, hydraulic pressure is released by opening a directional valve,
allowing the ram
to drop. A lower piston chamber is sealed and filled with gas. A moveable
shuttle member
reciprocates up and down inside a hollow piston rod in response to the
changing volume of
the lower piston cylinder, facilitating the evacuation of hydraulic fluid from
the upper piston
chamber. An alternative embodiment uses a single fluid and has no shuttle
member.
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[0066] All elements, parts and steps described herein are preferably
included. It is
to be understood that any of these elements, parts and steps may be replaced
by other
elements, parts and steps or deleted altogether as will be obvious to those
skilled in the art.
[0067] While the present invention has been described in accordance
with the
preferred embodiments thereof, the description is for illustration only and
should not be
construed as limiting the scope of the invention. Various changes and
modifications may be
made by those skilled in the art without departing from the spirit and scope
of the invention
as defined by the following claims.
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CONCEPTS
At least the following concepts are disclosed in this writing.
Concept 1. A hydraulic hammer comprising a ram and a piston cylinder fonned
inside said ram, a piston seated in said cylinder, with said piston fixed to a
lower end of a
connecting rod with an upper end of said connecting rod fixed to a support
member above
said ram and hydraulic means operatively connected to said ram for moving said
ram between
a first position and a second position.
Concept 2. A hydraulic hammer in accordance with claim 1 wherein said
hydraulic
io means further comprises a source of pressurized hydraulic fluid
operatively connected to an
upper piston chamber created by a piston inserted into said cylinder and a
cylinder head above
said piston for creating hydraulic pressure inside said upper piston chamber
and wherein said
piston is fixed to a lower end of a piston rod and means for selectively
relieving hydraulic
fluid pressure inside said upper piston chamber.
Concept 3. A hydraulic hammer in accordance with claim 1 or 2 wherein said
piston
rod is hollow and further comprising a shuttle member seated within said
hollow piston rod,
said hollow piston rod having an upper end fixed to a supporting member and
wherein said
shuttle member is free to reciprocate within said hollow piston rod.
Concept 4. A hydraulic hammer in accordance with claim 2 or 3 wherein said
pressure relieving means further comprises a valve in a pressurized hydraulic
fluid source that
can be opened to allow pressurized hydraulic fluid to flow into a pressure
relief line.
Concept 5. A hydraulic hammer in accordance with claim 4 wherein said pressure
relief line further comprises a passageway to an upper surface of said shuttle
member inside
said hollow piston rod.
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Concept 6. A hydraulic hammer in accordance with claim 2, 3 or 4 wherein said
source of pressurized hydraulic fluid operatively connected to said upper
piston chamber
further comprises a hydraulic fluid conduit tube larger in diameter than said
hollow piston rod
and concentric with said hollow piston rod.
Concept 7. A hydraulic hammer in accordance with claim 2, 3, 4 or 5 further
comprising a lower piston chamber and a cavity of said hollow piston rod below
a lower
surface of said shuttle member that further comprises a sealed cavity that is
filled with a
substantially inert gas under pressure.
Concept 8. A hydraulic hammer in accordance with claim any one of the
preceding
to claims wherein the volume of said lower piston chamber and said cavity
of said hollow piston
rod below a lower surface of said shuttle member form a variable volume cavity
that varies in
volume as said ram moves between said first and second positions.
Concept 9. A hydraulic hammer in accordance with claim 2 further comprising
upper
and lower stop members seated inside said hollow piston rod for constraining
the reciprocal
movements of said shuttle member.
Concept 10. A hydraulic hammer in accordance with claim 2 wherein said
cylinder
further comprises a sleeve inserted into said cylinder.
Concept 11. A hydraulic hammer comprising:
a ram;
a cylinder formed inside said ram and sealed at its lower end and sealed at
its
upper end by a cylinder head;
a piston seated in said cylinder and dividing said cylinder into an upper
piston
chamber and a lower piston chamber; and
a hollow piston rod having an upper end -fixed to a supporting member and a
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lower end fixed to said piston.
Concept 12. A hydraulic hammer in accordance with claim 11 further comprising
means for supplying hydraulic fluid under pressure to said upper piston
chamber.
Concept 13. A hydraulic hammer in accordance with claim 11 further comprising
means for releasing hydraulic pressure from said upper piston chamber.
Concept 14. A hydraulic hammer in accordance with claim 11, 12 or 13 further
comprising means for applying a force to a lower surface of said piston for
accelerating the
relief of pressure from the hydraulic fluid in said upper piston chamber and
thereby
accelerating the falling of said ram.
Concept 15. A hydraulic hammer in accordance with claim 11, 12, 13 or 14
wherein
said force applying means further comprises a shuttle member seated inside
said hollow
piston rod and free to reciprocate between upper and lower stop members.
Concept 16. A hydraulic hammer in accordance with claim 11, 12, 13, 14 or 15
further comprising a sealed chamber filled with gas under pressure, with said
sealed chamber
comprising said lower piston chamber and a cavity in said hollow piston rod up
to a lower
surface of said shuttle member, with said lower piston chamber and said cavity
in said hollow
piston rod being in fluid communication with each other.
Concept 17. A hydraulic hammer in accordance with claim 16 wherein said gas
under pressure when acted upon by a varying volume of said variable volume
cavity during
movements of said ram and said shuttle member provides a spring action
expansion force to
said lower surface of said piston to accelerate the emptying of hydraulic
fluid from said upper
piston chamber.
Concept 18. A hydraulic hammer comprising:
a ram;
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a cylinder formed inside said ram and sealed at its lower end and at its upper
end;
a piston seated in said cylinder and dividing said cylinder into an upper
piston
chamber and a lower piston chamber;
a hollow piston rod having an upper end fixed to a supporting member and a
lower end fixed to said piston; and
means for applying hydraulic fluid pressure to said upper piston chamber for
raising said ram and means for relieving said hydraulic fluid pressure in said
upper piston
cylinder for allowing said ram to fall and means for introducing hydraulic
fluid into a lower
piston chamber as said ram falls for accelerating the falling of said ram.
to Concept 19. A hydraulic hammer in accordance with claim 18 further
comprising a
receptacle attached to a lower surface of said piston and depending therefrom
and a well
beneath said receptacle formed in said ram whereby the volume of hydraulic
fluid to be
pumped is reduced.
Concept 20. A hydraulic hammer in accordance with claim 18 or 19 further
comprising means for supplying hydraulic fluid under pressure to said upper
piston cylinder
and means for relieving the pressure on the hydraulic fluid and for emptying
the hydraulic
fluid from said upper piston chamber and means for applying a downward
acceleration force
on said ram, said accelerating means further comprising means for controlling
the magnitude
of said downward acceleration force.
27
