U.S. patent application number 13/784687 was filed with the patent office on 2013-08-08 for hydraulic hammer.
This patent application is currently assigned to Global Piling Solutions, L.L.C.. The applicant listed for this patent is Global Piling Solutions, L.L.C.. Invention is credited to Bryce Everett Huff, Kurt N. Winters, Robert James Zimmerman.
Application Number | 20130199813 13/784687 |
Document ID | / |
Family ID | 48901901 |
Filed Date | 2013-08-08 |
United States Patent
Application |
20130199813 |
Kind Code |
A1 |
Zimmerman; Robert James ; et
al. |
August 8, 2013 |
Hydraulic Hammer
Abstract
A piston cylinder is formed inside a ram and is fitted with a
piston attached to a stationary hollow piston rod, creating a 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 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 that 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.
Inventors: |
Zimmerman; Robert James;
(Shawnee Mission, MO) ; Huff; Bryce Everett;
(Kansas City, MO) ; Winters; Kurt N.; (North Palm
Beach, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Global Piling Solutions, L.L.C.; |
North Palm Beach |
FL |
US |
|
|
Assignee: |
Global Piling Solutions,
L.L.C.
North Palm Beach
FL
|
Family ID: |
48901901 |
Appl. No.: |
13/784687 |
Filed: |
March 4, 2013 |
Current U.S.
Class: |
173/200 |
Current CPC
Class: |
E02D 7/10 20130101 |
Class at
Publication: |
173/200 |
International
Class: |
E02D 7/10 20060101
E02D007/10 |
Claims
1. A hydraulic hammer comprising a ram and a piston cylinder formed
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.
2. A hydraulic hammer in accordance with claim 1 wherein said
hydraulic 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.
3. A hydraulic hammer in accordance with claim 1 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.
4. A hydraulic hammer in accordance with claim 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.
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.
6. A hydraulic hammer in accordance with claim 3 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.
7. A hydraulic hammer in accordance with claim 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.
8. A hydraulic hammer in accordance with claim 7 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.
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.
10. A hydraulic hammer in accordance with claim 2 wherein said
cylinder further comprises a sleeve inserted into said
cylinder.
11. A hydraulic hammer comprising; a. a ram; b. a cylinder formed
inside said ram and sealed at its lower end and sealed at its upper
end by a cylinder head; c. a piston seated in said cylinder and
dividing said cylinder into an upper piston chamber and a lower
piston chamber; d. a hollow piston rod having an upper end fixed to
a supporting member and a lower end fixed to said piston.
12. A hydraulic hammer in accordance with claim 11 further
comprising means for supplying hydraulic fluid under pressure to
said upper piston chamber.
13. A hydraulic hammer in accordance with claim 11 further
comprising means for releasing hydraulic pressure from said upper
piston chamber.
14. A hydraulic hammer in accordance with claim 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.
15. A hydraulic hammer in accordance with claim 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.
16. A hydraulic hammer in accordance with claim 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.
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.
18. A hydraulic hammer comprising; a. a ram; b. a cylinder formed
inside said ram and sealed at its lower end and at its upper end;
c. a piston seated in said cylinder and dividing said cylinder into
an upper piston chamber and a lower piston chamber; d. a hollow
piston rod having an upper end fixed to a supporting member and a
lower end fixed to said piston; e. 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.
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.
20. A hydraulic hammer in accordance with claim 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.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
SEQUENCE LISTING
[0003] Not applicable
BACKGROUND OF THE INVENTION
[0004] The present invention is related to an improved 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
[0005] 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.
[0006] 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 the pile. Another disadvantage of this
technique is that it is typically relatively slow, reducing
productivity.
[0007] Also frequently used for driving piles are hydraulic
hammers. One hydraulic hammer is disclosed in U.S. Pat. No.
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.
[0008] Therefore, there is a need for a low headroom hammer that is
a hydraulic hammer.
BRIEF SUMMARY OF THE INVENTION
[0009] Accordingly, it is a primary object of the present invention
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.
[0010] It is another object of the present invention to provide a
hydraulic hammer that requires less energy to operate than similar
conventional hammers.
[0011] It is another object of the present invention to provide a
nearly free-fall low headroom hydraulic hammer that has a smaller
overall weight than comparable hammers of similar impact.
[0012] It is another object of the present invention 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.
[0013] It is another object of the present invention 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.
[0014] These and other objects of the invention are achieved 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 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
predetermined, and a second position, which is the lowest position
of the ram, i.e., the striking position.
[0015] Other objects and advantages of the present invention 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 of the present
invention and the best mode currently known to the inventor for
carrying out the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0016] 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.
[0017] FIG. 2 is a cross section side view of the hammer of FIG. 1
at the beginning the hammer lifting stroke.
[0018] 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.
[0019] 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.
[0020] FIG. 5 is a cross section side view of the hammer of FIG. 1
shown during the falling stroke of the ram.
[0021] 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.
[0022] FIG. 7 is a cross section taken along lines 7-7 of FIG. 1 or
FIG. 8.
[0023] 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.
[0024] FIG. 9 is a cross section side view of the hammer of FIG. 8
at the beginning the hammer lifting stroke.
[0025] 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.
[0026] 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.
[0027] FIG. 12 is a cross section side view of the hammer of FIG. 8
shown during the falling stroke of the ram.
[0028] 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 of FIG. 8, in equilibrium, at rest and ready
to begin another cycle.
[0029] 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
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.
[0030] FIG. 15 is a cross section side view of the hammer of FIG.
14 at the beginning the hammer lifting stroke.
[0031] 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.
[0032] 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.
[0033] FIG. 18 is a cross section side view of the hammer of FIG.
14 shown during the falling stroke of the ram.
[0034] 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.
[0035] 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.
[0036] 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 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.
[0037] FIG. 22 is a cross section side view of an alternative
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 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
[0038] 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 cylinder 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 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.
[0039] 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 formed 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 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 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.
[0040] 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
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.
[0041] 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
formation) 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 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 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 decreases 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.
[0042] 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 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.
[0043] 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.
[0044] 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 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.
[0045] 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 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
of forces that might be desired on a particular job. Naturally,
hammers 10 of different sizes will have different, appropriate,
maximum lifts.
[0046] 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.
[0047] Referring to FIG. 4, the desired predetermined height of the
ram 16 has been 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 cavity 41 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 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.
[0048] 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 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 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 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.
[0049] 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 30 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 closing the directional valve 68
and once again forcing hydraulic fluid into the upper piston
chamber 50 to force the ram 16 to rise.
[0050] 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 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.
[0051] 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.
[0052] 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
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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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
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 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.
[0057] Still referring to FIG. 14, as shown in FIGS. 14-19, this
embodiment is shown without the shuttle member 30, upper stop
member 32 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] Referring to FIG. 18, the fluid flows shown in FIG. 17
continue, allowing the ram 16 to continue its descent.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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. 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.
[0066] 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 quickly 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 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.
[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.
* * * * *