U.S. patent application number 12/917541 was filed with the patent office on 2011-05-12 for vibratory pile driving apparatus.
This patent application is currently assigned to International Construction Equipment, Inc.. Invention is credited to Kingsley S. Evarts.
Application Number | 20110110725 12/917541 |
Document ID | / |
Family ID | 43970320 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110110725 |
Kind Code |
A1 |
Evarts; Kingsley S. |
May 12, 2011 |
VIBRATORY PILE DRIVING APPARATUS
Abstract
Pile driving apparatus comprises first and second sets of
eccentric members mounted in a housing for opposing rotation. A
phase shifting arrangement connects the sets of eccentric members
for controlling coordinated rotation thereof, and comprises a
limiting device between the first and second sets of eccentric
members for shifting between a first condition wherein the
eccentric members are constrained to rotate out of phase to negate
generation of vibration and a second condition wherein the
eccentric members are constrained to rotate in phase to generate
vibration. Two motors are connected with the limiting device for
alternatively driving rotation thereof. A control arrangement
selectively drives the limiting device predominantly by the first
motor for shifting the limiting device into the first condition
thereof for preventing vibration or predominantly by the second
motor for shifting the limiting device into the second condition
for generating vibration in the housing.
Inventors: |
Evarts; Kingsley S.;
(Montgomery, TX) |
Assignee: |
International Construction
Equipment, Inc.
Matthews
NC
|
Family ID: |
43970320 |
Appl. No.: |
12/917541 |
Filed: |
November 2, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61280535 |
Nov 6, 2009 |
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Current U.S.
Class: |
405/232 |
Current CPC
Class: |
E02D 7/18 20130101; B06B
1/166 20130101 |
Class at
Publication: |
405/232 |
International
Class: |
E02D 7/18 20060101
E02D007/18 |
Claims
1. Apparatus for driving an object into the ground and for removing
an object from the ground by imparting to the object longitudinal
vibration generated via rotation of a plurality of eccentric
members, the apparatus comprising: (a) a housing, (b) a first set
of eccentric members mounted in the housing for synchronized
rotation in opposing directions relative to one another, (c) a
second set of eccentric members mounted in the housing for
synchronized rotation in opposing directions relative to one
another, (d) the first and second sets of eccentric members being
disposed relative to one another to generate vibrational force in
the housing in a common longitudinal direction, and (e) a phase
shifting arrangement connecting the first and second sets of
eccentric members for controlling coordinated rotation thereof, the
phase shifting arrangement comprising: (i) a limiting device
arranged between the first and second sets of eccentric members,
(ii) the limiting device being shiftable between a first condition
wherein the first and second sets of eccentric members are
constrained to rotate out of phase with one another to negate
generation of vibration in the housing and a second condition
wherein the first and second sets of eccentric members are
constrained to rotate in phase with one another to generate
vibration in the housing, (iii) a first motor connected with the
limiting device for driving rotation thereof, (iv) a second motor
connected with the limiting device for driving rotation thereof,
and (v) a control arrangement for selectively driving the
shift-limiting device predominantly by the first motor for shifting
the limiting device into the first condition thereof for
maintaining the first and second sets of eccentric members in the
first non-vibrating condition and for selectively driving the
limiting device predominantly by the second motor for shifting the
limiting device into the second condition for generating vibration
in the housing.
2. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 1, wherein the first
set of eccentric members comprises a first pair of eccentric
members.
3. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 1, wherein the second
set of eccentric members comprises a second pair of eccentric
members.
4. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 1, wherein the
limiting device comprising first and second drive components which
are shiftable relative to one another between the first and second
conditions.
5. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 4, wherein the first
motor is a hydraulic motor connected with the first drive component
of the limiting device for driving rotation thereof.
6. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 5, wherein the second
motor is a hydraulic motor connected with the second drive
component of the limiting device for driving rotation thereof.
7. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 6, wherein the phase
shifting arrangement further comprises a first hydraulic circuit
connecting the first and second motors in hydraulic series for
delivering a first source of pressurized hydraulic driving fluid to
the first and second motors in sequence.
8. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 7, wherein the control
arrangement comprises a second hydraulic circuit including a second
source of pressurized hydraulic driving fluid.
9. Apparatus for driving an object into the ground and for removing
an object from the ground according to claim 8, wherein the second
hydraulic circuit is connected to the first hydraulic circuit and
wherein the control arrangement further comprises a control device
for selectively adding supplementary hydraulic fluid to and
withdrawing hydraulic fluid from the first hydraulic circuit to
selectively shift the limiting device between the first and second
conditions thereof.
10. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 9, wherein
the control device comprises a solenoid valve movable between a
position wherein the second source of pressurized hydraulic driving
fluid delivers the hydraulic fluid to the first hydraulic circuit
and a position for receiving hydraulic fluid from the first
hydraulic circuit.
11. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 4, wherein
the first drive component of the limiting device comprises a first
pinion connected with the first set of eccentric members for
driving rotation thereof and the second drive component of the
limiting device comprises a second pinion connected with the second
set of eccentric members for driving rotation thereof, the first
and second pinions being mounted for relative rotation about a
common axis and having respective stop surfaces arranged for
abutment to limit relative rotation between the first and second
conditions.
12. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 1, wherein
the first and second motors are equivalent and each motor is
capable of driving the phase shifting arrangement and the eccentric
members.
13. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 1, wherein
first and second sets of eccentric members are arranged with one
set vertically above and in alignment with the other set.
14. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 1, wherein
the eccentric members are identical to one another.
15. Apparatus for driving an object into the ground and for
removing an object from the ground by imparting to the object
vibration generated via rotation of eccentric members, the
apparatus comprising: (a) a housing, (b) a first set of eccentric
members mounted in the housing for synchronized rotation in
opposing directions relative to one another, (c) a second set of
eccentric members mounted in the housing for synchronized rotation
in opposing directions relative to one another, (d) the first and
second sets of eccentric members being disposed relative to one
another to generate vibrational force in the housing along a common
longitudinal direction, and (e) a phase shifting arrangement
connecting the first and second sets of eccentric members for
controlling coordinated rotation thereof, (f) the phase shifting
arrangement comprising (i) a limiting device arranged between the
first and second sets of eccentric members, (ii) the limiting
device comprising first and second drive components which are
shiftable relative to one another between a first condition wherein
the first and second sets of eccentric members are constrained to
rotate out of phase with one another to negate generation of
vibration in the housing and a second condition wherein the first
and second sets of eccentric members are constrained to rotate in
phase with one another to generate vibration in the housing, (iii)
a first hydraulic motor connected with the first drive component of
the limiting device for driving rotation thereof, (iv) a second
hydraulic motor connected with the second drive component of the
limiting device for driving rotation thereof, (v) a first hydraulic
circuit connecting the first and second motors in hydraulic series
for delivering a first source of pressurized hydraulic driving
fluid to the first and second motors in sequence, (vi) a second
hydraulic circuit including a second source of pressurized
hydraulic driving fluid, (vii) the second hydraulic circuit being
connected to the first hydraulic circuit and including a control
device for selectively adding supplementary hydraulic fluid to and
withdrawing hydraulic fluid from the first hydraulic circuit to
selectively shift the limiting device between the first condition
thereof for maintaining the first and second sets of eccentric
members in the first non-vibrating condition during start-up
acceleration and shut-down deceleration thereof and the second
condition for generating vibration in the housing when the first
and second sets of eccentric members are rotating at an operating
speed.
16. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 15, wherein
the first drive component of the limiting device comprises a first
pinion connected with the first set of eccentric members for
driving rotation thereof and the second drive component of the
limiting device comprises a second pinion connected with the second
set of eccentric members for driving rotation thereof, the first
and second pinions being mounted for relative rotation about a
common axis and having respective stop surfaces arranged for
abutment to limit relative rotation between the first and second
conditions.
17. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 15, wherein
the control device comprises a solenoid valve movable between a
position wherein the second source of pressurized hydraulic driving
fluid delivers the hydraulic fluid to the first hydraulic circuit
and a position for receiving hydraulic fluid from the first
hydraulic circuit.
18. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 15, wherein
the first and second hydraulic motors are equivalent and each motor
is capable of driving the phase shifting arrangement.
19. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 15, wherein
first and second sets of eccentric members are arranged with one
set vertically above and in alignment with the other set.
20. Apparatus for driving an object into the ground and for
removing an object from the ground according to claim 15, wherein
the eccentric members are identical to one another.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is entitled to the benefit of, and
claims priority from, U.S. Provisional Patent Application Ser. No.
61/280,535, filed Nov. 6, 2009, and entitled "Series Motor
Resonance-Free System," the entirety of which is incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to vibration systems
and methods for driving objects into the earth and, more
specifically, to vibration systems that use counter-rotating
eccentric members to generate linear vibratory amplitude via
centrifugal force.
BACKGROUND OF THE INVENTION
[0003] Counter-rotating sets of eccentric members are often used in
so-called pile-driving equipment to generate vibratory forces for
driving objects into the ground, typically elongate members such as
H-beams, sheet piles, caissons, and the like, often collectively
referred to as "piles." The eccentric members used in such
equipment may be of any type or shape of rotating element or
assembly in which the weighting of the member offsets the center of
gravity of the member radially from its axis of rotation. The
product of the mass of the eccentric weight of the member times the
perpendicular distance of its offset from the rotational axis is
referred to as "eccentric moment."
[0004] Such an eccentrically weighted member generates centrifugal
force as its offset center of gravity rotates about its axis which
thereby produces vibration. As is well-known in the art, when two
such eccentrically weighted members of equal eccentric moment are
constrained to rotate in synchronism in opposite directions and at
equal speed, the opposing centrifugal forces generated by the
counter-rotating members will cancel each other in a transverse
direction but will be additive, positively or negatively, in a
longitudinal direction. The resulting output generates a linear
vibration in such longitudinal direction, but essentially no
vibration in the transverse direction, and is the basic operating
principle of vibratory pile drivers, also known as "vibrodrivers."
Such synchronous opposing rotation is typically accomplished by
rotatably connecting the eccentric members via gears, chains,
electro-hydraulic control or a similar means. As is also well known
in the art, when two pair of eccentric members are arrayed so that
the longitudinal axes of the eccentric pairs are aligned and both
pairs of eccentric members are constrained to rotate "in-phase" at
the same speed and with the identical angular position of the
centers of gravity of the eccentric members, the additive
longitudinal forces generated by the eccentric members produce a
linear sinusoidal vibration. Conversely, when the pairs of
eccentric members are rotated "out-of-phase" at an identical speed
but with the angular position of their respective centers of
gravity offset from one another by 180.degree., both the
longitudinal and transverse force components of each set of
eccentric members cancel each other, so that no linear vibration is
produced. This is the basic operating principle of vibratory pile
drivers.
[0005] Such resonance-free vibratory pile driving equipment may
employ eccentric members arranged in pairs or alternatively may
group eccentric members in sets of a greater number of counter
rotating eccentric members, e.g., a set of three eccentric members
comprised of one large eccentric member and two smaller eccentric
members each having an eccentric moment that is one half that of
the larger member. This arrangement is essentially the equivalent
of a pair of counter-rotating eccentric members of equal
masses.
[0006] Known vibratory pile driver constructions include a support
frame adapted to be suspended from a crane or a like support and a
vibratory assembly mounted to the support frame via elastomeric or
similar springs to isolate vibrations from the crane. The vibratory
assembly comprises one or more sets of eccentric members for
generating linear vibrational forces to drive a pile into the earth
and a clamping assembly for selectively clamping and releasing the
piles and for transmitting the vibrational forces to said piles
while clamped. One or more hydraulic or electric motors are
provided for driving rotation of the eccentric members at
sufficient speeds, e.g. 1500-2500 rpm, to produce high force, large
amplitude vibrations in the vibratory pile driver for driving the
piles into the earth.
[0007] At start-up, the motor increases the rotational speed of the
eccentric members from a standstill to the working speed of the
vibratory pile driver. Likewise, when the vibratory pile driver is
shut down, the speed of the eccentric members is reduced to a stop.
A common problem experienced with known vibratory pile drivers
arises during these start-up and shut-down periods. As the speed of
the vibratory pile driver increases or decreases through a
frequency equal to its natural frequency (i.e., its resonant
frequency), potentially destructive vibrations of extreme amplitude
can occur that can cause damage to the vibratory pile driver, the
pile, the crane and/or possibly adjacent structures such as
buildings or the like. Although operators attempt to bring the
vibratory pile drivers up to speed and to shut them down as quickly
as possible to minimize the amount of damaging vibration that
occurs, this practice does not eliminate the risk.
[0008] The conventional means for addressing the above-described
problems are known vibratory pile driver design variations commonly
referred to as variable moment (VM) or resonance free (RF) designs.
Both of these designs employ a "phase shifting" arrangement to
allow the vibratory pile driver to accelerate to, or decelerate
from, operating speed while generating no vibration. By selective
phase shifting, vibration output is initiated after the eccentric
members have reached operating speed, thus eliminating any period
of vibrating at resonant frequencies. An example of a variable
moment (VM) vibratory pile driver is described in U.S. Pat. No.
6,604,583, and an example of a resonance free (RF) vibratory pile
driver is described in U.S. Pat. No. 7,168,890.
[0009] Both variable moment (VM) and resonance free (RF) vibratory
pile drivers include a vibratory assembly which comprises at least
two sets of multiple eccentric members arranged so that their
longitudinal output force components align, producing a uniaxial
vibratory force. The eccentric member sets may be arranged
concentrically, as represented in U.S. Pat. No. 5,177,386, or
horizontally, as represented in U.S. Pat. No. 7,168,890, but are
most commonly arranged vertically, as represented in U.S. Pat. No.
6,604,583, i.e., with a top row of eccentric members positioned
directly above a bottom row of eccentric members. Typically, the
top row and bottom row of eccentric members are each driven by
independent hydraulic motors, although any number of motors may be
used depending on the size of the vibratory pile driver and other
design criteria of the unit. The top and bottom eccentric members
are connected and synchronized by the aforementioned phase shifting
arrangement, which is capable of adjusting the relative angular
relationship of the top and bottom eccentric members from
0.degree., or "in phase" with each other, to 180.degree., or "out
of phase" with each other. Depending upon the type of phase
shifting arrangement utilized, the top set of eccentric members and
the bottom set of eccentric members may rotate in the same
direction or in opposite directions. Many types of phase shifting
arrangements are known and used in these vibratory pile drivers,
and include bevel gear sets, harmonic gear sets, planetary gear
sets, swinging spur gear sets, helical splines, helical cams,
differential motor displacement, hydraulic rotary actuators and the
like. In the forgoing types of phase shifting devices, some are
self limiting to produce only a maximum of 180.degree. relative
movement, while others require additional limiting mechanisms
(e.g., stops or a stop mechanism) to limit the phase shift to
180.degree..
[0010] In the case of a variable moment (VM) vibratory pile driver,
the phase shifting device has the ability to adjust infinitely the
phase relationship of the top eccentric members to the bottom
eccentric members between 0.degree. and 180.degree. and to hold the
relationship setting while the vibratory pile driver is running.
Thus, the overall effective eccentric moment of the machine is
infinitely adjustable between a zero value and a maximum value.
[0011] In the known types of resonance free (RF) vibratory pile
drivers, the phase shifting mechanism is only capable of setting
the phase relationship of the top eccentric members and the bottom
eccentric members at two positions, i.e. 0.degree. in phase and
180.degree. out of phase. Consequently, the overall effective
eccentric moment of the machine is either a zero value or a maximum
value.
[0012] Both the variable moment (VM) and the resonance free (RF)
types of vibratory pile drivers solve the low speed resonance
problems described above. On one hand, the additional ability of
variable moment (VM) vibratory pile drivers to permit infinite
eccentric moment adjustment would seem to be an advantage. On the
other hand, however, this infinitely adjustable feature is seldom
used since maximum eccentric moment will almost always drive piles
faster than a lesser moment. Further, all the known applicable
phase shifting arrangements used in variable moment (VM) pile
drivers are extremely expensive and fairly complicated. This
adverse effect on the overall cost of a variable moment (VM)
vibratory pile drivers essentially means that they cannot be
justified except in extremely high risk areas or very sensitive job
sites. It is also well known that these infinitely variable phase
shifters are often unreliable, due to the vibrating environment and
the relative small space into which they must fit.
[0013] The resonance free (RF) type of vibratory pile driver tends
to be less complex, with resultant lower cost. However, the known
phase shifting arrangements which produce the resonance free (RF)
type of functionality have little or no control of the shifting
speed and rely on mechanical stops to limit the maximum phase shift
angular displacement. Due to the heavy masses being phase shifted,
and the violent, high velocity impacts of the stop mechanism, these
phase shifting arrangements are also unreliable.
SUMMARY OF THE INVENTION
[0014] The present invention seeks to address the disadvantages and
problems of known phase shifting arrangements in vibratory pile
drivers. Basically, the present invention provides an apparatus for
driving an object into the ground and for removing an object from
the ground by imparting to the object vibration generated via
rotation of eccentric members, comprising a housing, a first set of
eccentric members mounted in the housing for synchronized rotation
in opposing directions relative to one another, and a second set of
eccentric members mounted in the housing for synchronized rotation
in opposing directions relative to one another, with the first and
second sets of eccentric members being disposed relative to one
another (e.g., vertically or horizontally with respect to one
another) to generate vibrational force in the housing in a common
longitudinal direction.
[0015] The apparatus further includes a phase shifting arrangement
connecting the first and second sets of eccentric members for
controlling coordinated rotation thereof. More specifically, the
phase shifting arrangement comprises a limiting device arranged
between the first and second sets of eccentric members to be
shiftable between a first condition wherein the first and second
sets of eccentric members are constrained to rotate out of phase
with one another to negate generation of vibration in the housing
and a second condition wherein the first and second sets of
eccentric members are constrained to rotate in phase with one
another to generate vibration in the housing. According to the
present invention, each of a first motor and a second motor is
independently connected with the limiting device for driving
rotation thereof. A control arrangement is provided for selectively
driving the limiting device predominantly by the first motor for
shifting the limiting device into the first condition thereof for
maintaining the first and second sets of eccentric members in the
first non-vibrating condition or for selectively driving the
limiting device predominantly by the second motor for shifting the
limiting device into the second condition for generating vibration
in the housing.
[0016] In a preferred embodiment of the invention, the first set of
eccentric members may comprise a first pair of eccentric members,
and likewise the second set of eccentric members may comprise a
second pair of eccentric members. The limiting device preferably
comprises first and second drive components which are shiftable
relative to one another between the first and second conditions.
The first motor is preferably a hydraulic motor connected with the
first drive component of the limiting device for driving rotation
thereof, and similarly the second motor is preferably a hydraulic
motor connected with the second drive component of the limiting
device for driving rotation thereof.
[0017] In a preferred embodiment, the phase shifting arrangement
further comprises a first hydraulic circuit connecting the first
and second motors in hydraulic series for delivering a first source
of pressurized hydraulic driving fluid to the first and second
motors in sequence. The control arrangement preferably comprises a
second hydraulic circuit including a second source of pressurized
hydraulic driving fluid. The second hydraulic circuit is connected
to the first hydraulic circuit and the control arrangement further
comprises a control device for selectively adding supplementary
hydraulic fluid to and withdrawing hydraulic fluid from the first
hydraulic circuit to selectively shift the limiting device between
the first and second conditions thereof. Preferably, the first
condition of the limiting device is utilized for maintaining the
first and second sets of eccentric members in the first
non-vibrating condition during start-up acceleration and shut-down
deceleration thereof and the second condition of the limiting
device is utilized to generate vibration in the housing when the
first and second sets of eccentric members are rotating at an
operating speed. The control device may comprise a solenoid valve
movable between a position wherein the second source of pressurized
hydraulic driving fluid delivers the hydraulic fluid to the first
hydraulic circuit and a position for receiving hydraulic fluid from
the first hydraulic circuit.
[0018] In a preferred embodiment, the first drive component of the
limiting device may comprise a first pinion connected with the
first set of eccentric members for driving rotation thereof and the
second drive component of the limiting device may similarly
comprise a second pinion connected with the second set of eccentric
members for driving rotation thereof. The first and second pinions
are mounted for relative rotation about a common axis and have
respective stop surfaces arranged to shift between engagement in a
first abutting relationship in the first condition and in a second
abutting relationship in the second condition, thereby to limit
relative rotation between the first and second conditions.
[0019] It is preferred that the first and second motors are
equivalent and each motor is independently capable of driving the
phase shifting arrangement. The eccentric members are preferably
identical to one another. In a preferred embodiment, the first and
second sets of eccentric members are arranged with one set
vertically above and in alignment with the other set.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic view of a representative arrangement
of a pair of eccentric members, illustrating the basic principle of
operation of prior art vibratory pile driving apparatus;
[0021] FIGS. 2 and 3 are schematic views similar to FIG. 1 showing
alternative representative prior art arrangements of eccentric
members;
[0022] FIG. 4 is a schematic side view of a prior art vibratory
pile driving apparatus, showing the eccentric members thereof
rotating in phase with one another;
[0023] FIG. 5 is a vertical cross-sectional view of the prior art
pile driving apparatus of FIG. 1, taken along line V-V thereof;
[0024] FIG. 6 is another side view of the prior art apparatus of
FIGS. 4 and 5, showing the eccentric members thereof rotating out
of phase with one another;
[0025] FIG. 7 is a schematic isometric view of a vibratory pile
driving apparatus according to one preferred embodiment of the
present invention, depicting the eccentric members thereof rotating
in phase with one another;
[0026] FIG. 8 is a schematic isometric view of the vibratory pile
driving apparatus of FIG. 7, depicting the eccentric members
thereof rotating out of phase with one another;
[0027] FIG. 9 is a schematic isometric view of a vibratory pile
driving apparatus according to a second preferred embodiment of the
present invention;
[0028] FIG. 10 is a schematic isometric view of a vibratory pile
driving apparatus according to a third preferred embodiment of the
present invention;
[0029] FIG. 11 is a schematic isometric view of an alternative
embodiment of synchronizing arrangement for a vibratory pile
driving apparatus according to the present invention;
[0030] FIGS. 12A-12D are schematic isometric views of the
synchronizing arrangement of FIG. 11, depicting differing
operational conditions thereof; and
[0031] FIG. 13A-13D are schematic vertical cross-sectional views of
the synchronizing arrangement of FIG. 11, corresponding to the
conditions of FIGS. 12A-12D, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Referring now to the accompanying drawings, FIGS. 1-6 depict
schematically the above-described principle of operation of known
vibratory pile driving apparatus wherein counter-rotating eccentric
members are utilized to vibrationally generate rectilinear motion
that can be transmitted to a pile or other object to be driven into
the earth. Basically, such eccentric members can be substantially
any form of rotating element or assembly in which the weight
distribution of the member offsets its center of gravity from its
axis of rotation, as representatively depicted in FIG. 4 wherein
each rotating member has a center of gravity spaced by the
indicated radial offset from the axis of rotation of the member.
Such an eccentrically weighted member generates centrifugal force
as its offset center of gravity rotates about the axis which
thereby produces vibration.
[0033] FIGS. 1-3 depict the basic principles of operation of
vibratory pile drivers as described above. Specifically, FIG. 1
illustrates a single pair of synchronously counter-rotating
eccentric members showing their centers of gravity and
corresponding centrifugal force output vectors at four differing
positions of rotation. Each of FIGS. 2 and 3 similarly illustrate
four differing rotational positions of vibratory arrangements
wherein eccentric members are grouped in sets of three counter
rotating eccentric members comprised of one large eccentric member
and two smaller eccentric members each having an eccentric moment
that is one half that of the larger member, arranged horizontally
with respect to one another as depicted in FIG. 2, or vertically
with respect to one another, as depicted in FIG. 3.
[0034] FIGS. 4-6 depict one known prior art vibratory pile driving
apparatus of the type disclosed in European Patent Document
EP-A-0524056, as further described in U.S. Pat. No. 6,604,583. In
such apparatus, a first pair of eccentric weights 1, 2 are
rotatably disposed vertically above a second pair of rotatable
eccentric members 3, 4 within a housing 14 adapted to be clamped or
otherwise affixed to an object (such as a pile, not shown) to be
vibrationally driven. Each of the eccentric weights 1, 2, 3, 4 is
mounted on a respective gear 5, 6, 7, 8, with the gears 5, 6 and 7,
8 of each respective pair of weights in meshing engagement with
each other, whereby the weights 1, 2, 3, 4 of each pair rotate in
opposite directions as indicated by directional arrows. Each pair
of eccentric weights is driven via a respective hydraulic motor 9,
10 disposed in mesh with a respective gear 5, 7 of the eccentric
weight 1, 3. Gears 6, 8 supporting eccentric weights 2, 4 are each
in mesh with respective gears 11, 12 mounted on a shaft 15 of a
differential type of phase shifter 13 which is operative to shift
the eccentric weights 1, 2 relative to the eccentric weights 3, 4
between an in-phase orientation depicted in FIG. 1, causing the
weights to vibrate rectilinearly in a vertical direction, i.e.,
from top to bottom as viewed in FIG. 1, and an out-of-phase
orientation depicted in FIG. 3, wherein the pairs of eccentric
weights 1, 2 and 3, 4 cancel the vibratory force of the other
thereby attenuating any vibration of the apparatus.
[0035] With reference now to FIGS. 7 and 8, a vibratory pile
driving apparatus according to the present invention is
schematically depicted in one embodiment of a simple, rugged,
reliable and inexpensive design functional as a resonance free (RF)
type of apparatus. In this embodiment, the apparatus only provides
minimum and maximum eccentric moment adjustment positions, as is
characteristic of resonance-free (RF) apparatus. The vibratory pile
driver structure of FIG. 7 comprises two pairs of eccentric members
20, 21 and 22, 23, respectively, mounted in a common vertically
arrayed layout (e.g., as in FIGS. 1-3) for counter-rotation (e.g.,
via coaxial intermeshing gears, not shown) with one pair vertically
above the other within a housing (also not shown), which may be of
any suitable structure and configuration adapted to be suspended
via a crane or other support structure for operation to drive piles
or like objects.
[0036] A phase shifting arrangement, indicated overall at 24,
connects the two pairs of eccentric members 20, 21, 22, 23 to
control coordinated rotation of the members, and includes a
limiting device in the form of a double pinion mechanism 26
comprised of two pinion gears 28, 29 mounted coaxially with one
another and in meshing engagement respectively with the gears of
eccentric members 20, 22. The pinions 28, 29 are independently
rotatable except that each pinion 28, 29 includes a stop 28A, 29A,
respectively, projecting axially toward each other for engagement
whenever one pinion rotates substantially a full revolution in
either direction relative to the other pinion, thereby to limit the
amount of relative rotation of the pinions. The gear ratios of the
eccentric members 20, 21, 22, 23 and the pinions 28, 29 and the
respective centers of gravity of the eccentric members are arranged
such that, when the pinions 28, 29 are rotated in respective
clockwise directions into a first condition wherein their stops
28A, 29A abut, the two pairs of eccentric members are disposed out
of phase with one another to negate generation of vibration in the
housing, as depicted in FIG. 8, and when the pinions 28, 29 are
rotated in respective counterclockwise directions into a second
condition into abutment of their stops 28A, 29A, the two pairs of
eccentric members are disposed in phase with one another for
generating vibration in the housing, as depicted in FIG. 7. Each
pinion 28, 29 is driven independently via a respective motor 30,
31, preferably a hydraulic motor.
[0037] According to the present invention, the two hydraulic motors
30, 31 are driven from a hydraulic power unit, such as a pump 32,
via a hydraulic circuit 34 in which the motors 30, 31 are arranged
in series to receive pressurized hydraulic fluid in sequence first
to the motor 30 and then to the motor 31. The hydraulic motors 30,
31 are of equal power displacement selected such that either motor
is sufficiently powered to alone drive the overall pile driving
apparatus, but because the motors 30, 31 are plumbed together in
series, the motors only develop the torque of a single motor and
only rotate at the same speed as a single motor. As will be
understood, if the pinions 28, 29 did not include stops 28A, 29A,
the motors 30, 31 would rotate at approximately the same speed, but
with nothing to control their particular phase relationship. Also,
as will be understood, the fluid pressure in the intermediate
section 34A of the hydraulic circuit 34 between the exhaust port A
of motor 30, and the intake port A of motor 31, will be about half
that applied at the intake B to pump 30.
[0038] According to a unique feature of the current invention, a
second hydraulic circuit 36 supplied with pressurized hydraulic
fluid from an independent pump or other hydraulic power unit 38 is
connected in fluid communication with the intermediate section 34A
of the hydraulic circuit 34 between the two motors 30, 31. The
hydraulic circuit 36 is controlled via a solenoid valve 40 to
operate to selectively add or subtract small amounts of hydraulic
fluid flow to or from the intermediate section 34A of the hydraulic
circuit 34. When vibration is desired in the apparatus, the
solenoid valve 40 is deenergized to move into the position shown in
FIG. 7 to disconnect the hydraulic circuit 36 from the pump 38,
thereby relieving pressure within the circuit 36 and allowing a
small flow of hydraulic fluid to flow from the hydraulic circuit 34
into the circuit 36. The motors 30, 31 are constrained to rotate at
the same speed by engagement of the pinion stops 28A, 29A, and
accordingly this diverted fluid flow causes the pressure in the
circuit section 34A and the pressure at the intake port A of the
motor 31 to reduce to a sufficiently low level that the motor 31
ceases to apply driving torque to the pinion 29 and the motor 30
begins to drive both the bottom pair of eccentric members 22, 23
and the top pair of eccentric members 20, 21 via the pinions 28,
29.
[0039] When it is desired to prevent vibration in the apparatus,
the solenoid valve 40 is energized to move into the position shown
in FIG. 8 to connect the pump 38 to the hydraulic circuit 36,
whereby the pressurization of the circuit 36 directs a small
controlled flow of hydraulic fluid from the pump 38 into the
hydraulic circuit 34. The hydraulic pressure in the section 34A of
the circuit 34 thereby increases such that, when the pressure
prevailing in the circuit section 34A exceeds the system pressure
at the pump 32, the continuing fluid flow from the circuit 36 into
the circuit section 34A causes the two motors 30, 31 to slowly
rotate in opposite relative directions from one another, which in
turn causes the top pair of eccentric members 20, 21 and the bottom
pair of eccentric members 22, 23 to slowly rotate toward their
out-of-phase disposition. This relative opposing rotation of the
eccentric members occurs whether the apparatus is stopped or is
running at full speed. When the respective stops 28A, 29A of the
pinions 28, 29 contact each other due to their opposite rotation,
the eccentric members 20, 21, 22, 23 are 180 degrees out of phase.
Opposite rotation of the pinions ceases and both motors 30, 31 are
again constrained to rotate at the same speed. At this point, the
hydraulic pressure is the same at both the intake and exhaust ports
A, 13 of the motor 30, whereupon the motor 30 ceases to generate
torque. Full system pressure prevails at the intake port A of the
motor 31 such that the motor 31 begins to drive both the top and
bottom pairs of eccentric members in their phase shifted position
via the engaged pinions 28, 29. Thus, since only one of the motors
30, 31 drives the vibratory pile driving apparatus whether its
eccentric members are in phase or out of phase with one another,
and since half the torque in the system is transmitted through the
pinion stops 28A, 29A, the stops are sure to be in contact, with
force applied, during continuous operation.
[0040] The rate of fluid flow into and from the hydraulic circuit
34 via the circuit 36 is regulated via two pressure compensated
flow control valves and ball checks, indicated overall at 42,
regardless of the pressure prevailing in the two circuits. The
amount and rate of flow must be accurately controlled to prevent
the motors 30, 31 from driving the pinions 28, 29 too rapidly
between the positions of FIGS. 7 and 8, which risks potentially
violent rotational impact between the stops 28A, 29A of the pinions
28, 29. Similarly, it is equally important to provide a sufficient
fluid flow to the motor 31 in the condition of FIG. 7 to prevent
cavitation of the motor.
[0041] Although the above description of operation for the current
invention relates to a vibratory pile driver apparatus in which
sets of eccentric members are vertically arrayed, the principles of
the present invention apply equally well to apparatus having
horizontally arrayed eccentric members and to apparatus having
concentrically arranged eccentric members. Fundamentally, it is
merely important that the sets of eccentric members be disposed
relative to one another to be capable of generating vibrational
force in the housing in a common uniaxial direction when the
eccentric members are rotated in phase with each other. Persons
skilled in the art will also recognize and understand that
embodiments with a greater number of pairs of eccentric members or
with more than two eccentric members in each set are equally
possible. Likewise, a greater number of hydraulic motors may be
utilized, and may be differently arranged, e.g., at the same side
of the apparatus.
[0042] For example, FIG. 9 depicts an alternative embodiment of the
present invention wherein both motors 30, 31 are disposed on the
same side of the limiting device, which in this embodiment is
accomplished by the provision of another pinion 129 disposed on the
opposite side of the top pair of eccentric members 20, 21 in
meshing engagement with the eccentric member 21 to be driven by the
motor 31 from the same side of the apparatus as the motor 30.
[0043] FIG. 10 depicts another embodiment of the present invention
utilizing additional hydraulic motors to drive the vibratory
apparatus to accommodate a much larger eccentric moment than is
economically or physically feasible with only two larger motors
arranged as in the embodiments of FIGS. 7-9. In this embodiment,
two reasonable sized motors 30, 31 are used to perform the phase
shifting function in conjunction with the double pinion arrangement
28, 29, as well as to apply some power to the rotating system. Two
additional motors 130, 131 are mounted and connected to the system
via two additional pinion gears 128, 129, and are supplied with
operating hydraulic fluid via an additional hydraulic circuit 134.
In such arrangement, the additional motors 130, 131 and pinions
128, 129 have no phase shifting function and act only to add
driving power to the apparatus, the motor 131 driving the top pair
of eccentric members 20, 21 and the motor 130 driving the bottom
pair of eccentric members 22, 23. As many additional pairs of
motors and pinions may be installed as necessary or desirable to
achieve a required or desired power input for any given vibratory
pile driving apparatus.
[0044] As will be understood, each of the embodiments of the
present invention thus far described is of the resonance free (RF)
type of vibratory pile driving apparatus. The present invention
however is not limited to such resonance free (RF) embodiments.
FIGS. 11, 12A-12D and 13A-13D depict another possible embodiment of
the present invention utilizing a modified form of double pinion
mechanism 228, 229 wherein each pinion 228, 229 is formed with two
axial levels of stops which permit the pinions to be selectively
engaged in each of 0.degree. in-phase engagement with each other
(FIGS. 12A, 13A), 180.degree. out of phase engagement with each
other (FIGS. 12B, 13B), and intermediate selectable positions
therebetween (FIGS. 12C,13C, and 12D, 13D). More specifically, as
best seen in FIG. 11, each synchronizing pinion gear 228, 229 has a
stop surface 228B, 229B projecting axially from the main body of
the pinion gear and spanning approximately 210.degree. about the
gear, with stops 228A, 229A (corresponding to the stops 28A, 29A of
FIGS. 7-9) projecting axially from the stops 22813, 229B. The stops
228A, 229A function identically to the stops 28A, 29A in the
embodiments of FIGS. 7-9 to limit relative rotation of the top and
bottom pairs of eccentric members to the maximum out-of-phase and
the minimum in-phase eccentric moment positions represented in
FIGS. 12A, 13A and 12B, 13B. The shaft on which the pinion 229 is
mounted is connected via a thrust bearing 250 to be axially
shiftable toward and away from the pinion 228 via a double acting
hydraulic cylinder assembly 252. Thus, when an intermediate
eccentric moment is desired, the pinion 229 may be moved axially
toward the pinion 228 to dispose the stop 229A within the recessed
area within the stop surface 228B of pinion 228, whereby relative
rotation of the pinions 228, 229 is further restricted between two
intermediate dispositions wherein the stop 228A abuts opposite
sides of the stop 229B, as depicted in FIGS. 12C, 13C and 12D, 13D.
The circumferential extent of the stops 228B, 229B may be
selectively set to achieve any desired intermediate level of
eccentric moment, e.g., 30% and 60% eccentric moments as
represented in FIGS. 12C, 13C and 12D, 13D.
[0045] As will thus be understood, the vibratory pile driving
apparatus of the present invention advantageously provides a
simplified design, as compared to known prior art apparatus, which
is rugged, reliable and inexpensive as well as being adapted to
function in differing embodiments as a resonance free (RF) type of
pile driving apparatus and as a variable moment (VM) type of pile
driving apparatus with selectively fixed intermediate
positions.
[0046] Those persons skilled in the art will thus recognize and
understand that the invention is susceptible of broader utility and
application. Many embodiments and adaptations of the present
invention other than those herein described, as well as many
variations, modifications and equivalent arrangements, will be
apparent from or reasonably suggested by the present invention and
the foregoing description thereof, without departing from the
substance or scope of the present invention. Accordingly, it is to
be understood that the foregoing disclosure is only illustrative
and exemplary of the present invention and is made merely for
purposes of providing a full and enabling disclosure of the
invention. The foregoing disclosure is not intended or to be
construed to limit the present invention or otherwise to exclude
any such other embodiments, adaptations, variations, modifications
and equivalent arrangements, the present invention being limited
only by the claims appended hereto and the equivalents thereof.
* * * * *