U.S. patent application number 12/685354 was filed with the patent office on 2011-07-14 for articulated boom lifting arrangement.
This patent application is currently assigned to GENIE INDUSTRIES, INC.. Invention is credited to James Allen Donaldson.
Application Number | 20110168490 12/685354 |
Document ID | / |
Family ID | 44257665 |
Filed Date | 2011-07-14 |
United States Patent
Application |
20110168490 |
Kind Code |
A1 |
Donaldson; James Allen |
July 14, 2011 |
Articulated Boom Lifting Arrangement
Abstract
A bell crank and a mechanical link are included in an aerial
lift system to mechanically constrain motion of a two-boom aerial
lift mechanism to prevent the aerial lift system from accessing
unstable positions. Typically an aerial lift is coupled to a
vehicle via a turntable. The turntable includes a counterweight on
a rearward side of the turntable to balance the booms and
associated hardware as they are extended in a forward direction. If
the booms are in certain rearward, or even vertical positions, the
counterweight can cause the vehicle to tip and such unstable
positions are to be avoided. By providing the bell crank proximate
the pivot joint between upper and lower booms, with the bell crank
coupling at pivot joints with: the lower boom, the mechanical link,
and an upper hydraulic cylinder, the booms of the aerial lift
system are mechanically constrained to avoid vehicle tipping.
Inventors: |
Donaldson; James Allen;
(Puyallup, WA) |
Assignee: |
GENIE INDUSTRIES, INC.
Redmond
WA
|
Family ID: |
44257665 |
Appl. No.: |
12/685354 |
Filed: |
January 11, 2010 |
Current U.S.
Class: |
182/63.1 ;
182/141; 212/347 |
Current CPC
Class: |
B66F 11/046
20130101 |
Class at
Publication: |
182/63.1 ;
182/141; 212/347 |
International
Class: |
E04G 1/22 20060101
E04G001/22; E04G 5/00 20060101 E04G005/00; E04G 1/24 20060101
E04G001/24 |
Claims
1. A boom system, comprising: a support member; a lower boom
coupled to the support member at a first turntable pivot; a lower
linear actuator coupled between the support member and the lower
boom; a mechanical link coupled to the support member at a second
support member pivot; a bell crank comprising: a first bell-crank
pivot coupled to the lower boom; a second bell-crank pivot coupled
to the mechanical link; and a third bell-crank pivot; an upper boom
coupled to the lower boom via a boom-to-boom pivot; and an upper
linear actuator coupled to the bell crank at the third bell crank
pivot and coupled to the upper boom.
2. The boom system of claim 1 wherein the bell crank is generally
triangular with the first, second, and third bell crank pivots
located near corners of the generally triangular bell crank.
3. The boom system of claim 1 wherein the support member is a
rotatable turntable, the lower boom couples with the turntable
proximate a first end of the lower boom, the lower boom couples
with the upper boom and the bell crank proximate a second end of
the lower boom, and the lower linear actuator couples with the
lower boom at a point in between the first and second ends of the
lower boom.
4. The boom system of claim 1 wherein the lower linear actuator is
pivotally coupled to the lower boom at a coupling location and the
coupling location is proximate a first end of the lower linear
actuator and along the length of the lower boom.
5. The boom system of claim 4 wherein the support member is a
turntable, a second end of the lower linear actuator extends
through a slot in the turntable, the lower linear actuator is
trunnion mounted to the turntable at a location away from the
second end of the lower linear actuator, and the lower linear
actuator is configured to pivot with respect to the turntable.
6. The boom system of claim 1 wherein the lower linear actuator is
a lower hydraulic cylinder and the upper linear actuator is an
upper hydraulic cylinder.
7. The boom system of claim 6, further comprising: a lower
hydraulic line coupled to the lower hydraulic cylinder; an upper
hydraulic line coupled to the upper hydraulic cylinder; a lower
operator-controlled actuator to control supply of hydraulic fluid
in the lower hydraulic line; and an upper operator-controlled
actuator to control supply of hydraulic fluid in the upper
hydraulic line.
8. The boom system of claim 1 wherein the support member is a
turntable, the lower boom is coupled to the turntable at a first
end of the lower boom and the boom-to-boom pivot is located
proximate a second end of the lower boom and proximate a first end
of the upper boom.
9. The boom system of claim 8, further comprising a basket system
coupled to the upper boom at a second end of the upper boom.
10. A boom system, comprising: a turntable; a lower boom pivotally
coupled to the turntable; a lower linear actuator pivotally coupled
between the turntable and the lower boom; a mechanical link
pivotally coupled to the turntable; a bell crank pivotally coupled
to the lower boom and the mechanical link; an upper boom pivotally
coupled to the lower boom; and an upper linear actuator pivotally
coupled between the bell crank and the upper boom.
11. The boom system of claim 10 wherein the lower linear actuator
comprises a hydraulic cylinder and the upper linear actuator
comprises a hydraulic cylinder.
12. The boom system of claim 10 wherein the lower linear actuator
is coupled to the turntable rearward of a coupling between the
lower boom and the turntable, the system further comprising: a
counterweight mounted on the turntable, the counterweight located
rearward with respect to the coupling between the lower boom and
the turntable.
13. The boom system of claim 10 wherein: the mechanical link is
coupled to the turntable at a location that is rearward with
respect to a coupling between the lower boom and the turntable; and
the lower linear actuator is coupled to the turntable at a location
that is rearward with respect to a coupling between the mechanical
link and the turntable.
14. The boom system of claim 10 wherein the mechanical link
comprises two members and the lower linear actuator passes through
the two members of the mechanical link.
15. The boom system of claim 10 wherein one end of the lower linear
actuator extends through an opening in the turntable.
16. The boom system of claim 15 wherein the lower linear actuator
is trunnion coupled to the turntable, the lower linear actuator is
a hydraulic cylinder, and the upper linear actuator is a hydraulic
cylinder.
17. An aerial lift system, comprising: a vehicle; a turntable
rotably coupled to the vehicle; a lower boom pivotally coupled to
the turntable; a mechanical link pivotally coupled to the
turntable; a bell crank pivotally coupled to the lower boom and the
mechanical link; and an upper boom pivotally coupled to the lower
boom.
18. The aerial lift system of claim 17, further comprising: a lower
hydraulic cylinder pivotally coupled between the turntable and the
lower boom; and an upper hydraulic cylinder pivotally coupled
between the bell crank and the upper boom.
19. The aerial lift system of claim 18 wherein the bell crank is
generally triangular with a lower boom pivot proximate a first
corner of the bell crank, a mechanical link pivot proximate a
second corner of the bell crank, and an upper hydraulic cylinder
pivot proximate a third corner of the bell crank.
20. The aerial lift system of claim 17, further comprising: an
extendible link coupled to the upper boom; and a basket system
coupled to the extendible link.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to aerial lift systems and
vehicles provided with such lift systems.
[0003] 2. Background Art
[0004] One type of aerial lift includes a vehicle onto which a
pivotable turntable is mounted, with the turntable having a series
of adjustable, and possibly, extendable booms onto which a platform
or basket is mounted. Typically, a lower and an upper boom are used
to position a platform or basket away from the vehicle to a desired
location so that a person within the basket or platform may perform
work or maintenance on an object that is otherwise difficult to
access.
[0005] It is desirable for the boom to allow the basket to extend
beyond the footprint of the vehicle. However, as the basket moves
with respect to the vehicle, the center of mass of the vehicle
system, i.e., including the boom, basket, the person or persons in
the basket and whatever other cargo is in the basket, migrates.
Several measures can be taken to overcome a tendency of the vehicle
to tip when the boom is extended away from the vehicle.
[0006] For example, the weight and/or footprint of the vehicle are
increased so that the vehicle system is more stable. However, it is
undesirable to increase the weight of the vehicle because it makes
transporting the vehicle to a work site that much more difficult.
Also, if the surface near the work site is unstable, such as may
result from a presence of sand or mud, the more that the vehicle
system weighs, the more likely the vehicle will become stuck during
maneuvering. Another measure used to stabilize the vehicle in the
elevated position calls for increasing the track width and/or the
wheel base, whereby the foot print of the vehicle is increased,
which improves stability. However, the larger the footprint, the
less maneuverable the vehicle becomes. Also, a wider vehicle is
prevented from accessing certain locations that it may have
otherwise been able to access.
[0007] Another commonly employed measure involves providing a
counterweight on the turntable so that the counterweight rotates
with the turntable. The counterweight balances the boom extending
in a direction away from the counterweight, which is called a
"forward" direction regardless of the angle of the rotation of the
turntable. Thus, the forward and rearward directions are defined
with respect to the turntable, not with respect to the vehicle or
any object that is being accessed from the basket. However, the
counterweight provides an undesirable imbalance force when the
upper boom is rotated in a rearward direction. Thus, this measure
commonly includes taking additional measures to prevent the boom
from moving too far rearward.
[0008] In some other designs, the positions of the booms are
controlled by hydraulic cylinders. By knowing the extent that the
hydraulic cylinders are extended, the combinations of boom
positions leading to tipping can be avoided. However, such a system
relies on having sensors to measure positions of the hydraulic
cylinders, a controller, and frequent calibration of the sensors to
ensure sufficient measurement accuracy.
[0009] In yet another prior design, an upright member is provided
between the lower and upper booms. The upright is actively
controlled via hydraulic feedback to maintain it in a vertical
position. A disadvantage of such a system is that it requires
additional hydraulic cylinders managed by complex valving and
additional sensors. Furthermore, the system may require periodic
calibration. Also, by introducing an intermediate link, i.e., the
upright, additional play is introduced. The amount of play is
exacerbated at the operator's station in the `basket. Such play
undermines the operator's sense of security.
SUMMARY
[0010] To solve at least one problem in the prior art, an aerial
lift system is disclosed which includes a vehicle, a turntable
coupled to the vehicle, a lower boom coupled to the turntable at a
first turntable pivot, a lower linear actuator coupled between the
turntable and the lower boom, and a mechanical link coupled to the
turntable at a second turntable pivot. The turntable is coupled to
the vehicle with an axis of rotation of the turntable being
substantially vertical. The upper side of the turntable includes
pivot joints for at least a lower boom and a mechanical link. The
axis of rotation about these first turntable and second turntable
pivots, in some embodiments, is substantially perpendicular to the
axis of rotation of the turntable with respect to the vehicle. A
bell crank is coupled to: the lower boom at a first bell-crank
pivot and to the mechanical link at a second bell-crank pivot. The
system includes an upper boom coupled to the lower boom at a
boom-to-boom pivot. The system also includes an upper linear
actuator coupled to the bell crank at a third bell crank pivot and
coupled to the upper boom. The linear actuators are any suitable
linear actuator such a hydraulic cylinder. The mechanical link, in
some embodiments, includes two members. The lower linear actuator
passes between the two members of the mechanical link as it couples
between the lower boom and the turntable.
[0011] By providing the mechanical link and the bell crank, the
upper and lower booms are constrained in such a manner that they
are prevented from accessing positions in which vehicle tipping may
occur. This presents advantages over prior designs. For example, in
one embodiment of the invention in which the lower boom is coupled
to the upper boom, there are fewer pivot points than some prior art
systems. Thus, there is less play in the system at the operator
basket, which may extend 50 feet or more from the vehicle, during
positioning of the basket or due to the wind acting upon the
basket. The operator feels more secure and comfortable when the
basket bounces to a lesser degree.
[0012] At least one embodiment of the invention obviates the need
for complicated electronic/hydraulic control and hydraulic
actuators used to limit rear instability. Furthermore, the
mechanical system does not need calibration, as needed with a
system using control valves and actuators. Furthermore, service
intervals for some embodiments of the invention described by the
present disclosure, which are mechanically based, are likely longer
than service intervals for prior systems which may include sensors,
controllers, and complex valving.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows an aerial lift system in which the booms are in
a stowed position for transportation and in which the upper and
lower hydraulic cylinders are fully retracted;
[0014] FIG. 2 shows an aerial lift in which the upper hydraulic
cylinder is fully extended and the lower hydraulic cylinder is
fully retracted;
[0015] FIG. 3 shows an aerial lift in which the upper and lower
hydraulic cylinders are fully extended; and
[0016] FIG. 4 shows an aerial lift in which the upper hydraulic
cylinder is fully retracted and the lower hydraulic cylinder is
fully extended.
DETAILED DESCRIPTION
[0017] As shown in FIGS. 1 through 4, an aerial lift system 10
includes a vehicle 12 with an aerial lift 13. According to the
embodiment depicted in FIG. 1, vehicle 12 is a wheeled vehicle.
Alternatively, vehicle 12 may be a tracked vehicle. In some
embodiments, vehicle 12 is not self-propelled. A turntable 14 is
rotatably mounted on vehicle 12. Alternatively, element 14 is a
support member which is fixed to vehicle 12. A lower boom 16 is
coupled to turntable 14 via a pivot joint 18, at or near to a
proximal end of the lower boom 16. A lower hydraulic cylinder 20 is
pivotally coupled between turntable 14 and lower boom 16.
Generally, a distal end of the lower hydraulic cylinder 20 is
coupled to the lower boom 16 at some distance from the proximal end
of the boom 16.
[0018] In one embodiment, a proximal end of the lower hydraulic
cylinder 20 extends through a slot in turntable 14 to provide
stowage space for lower hydraulic cylinder 20. Lower hydraulic
cylinder 20 is trunnion that is in turn mounted to the turntable in
one embodiment, with the trunnion joint being located along the
body of lower hydraulic cylinder 20, i.e., not connected at the
proximal end of lower hydraulic cylinder 20. A mechanical link 22
is also coupled to turntable 14 via a pivot joint 23. In one
embodiment, mechanical link 22 comprises two members 24 and 26. In
the embodiment shown in FIG. 1, lower hydraulic cylinder 20 passes
between members 24 and 26 of mechanical link 22. A second end of
lower boom 16 pivotally couples with an upper boom 28 at a pivot
29
[0019] According to one embodiment, aerial lift 13 includes a bell
crank 30 which is pivotally coupled to mechanical link 22 and lower
boom 16. Bell crank 30 is also pivotally coupled to an upper
hydraulic cylinder 32 at one end of the upper hydraulic cylinder
with the other end of upper hydraulic cylinder 32 coupled to upper
boom 28. Upper hydraulic cylinder 32 couples with upper boom 28
away from either end of upper boom 28. Upper boom 28 is coupled to
lower boom 16 at a close end of upper boom 28. At a far end of
upper boom 28, a basket assembly 34 is coupled. Basket assembly 34
includes a platform and/or cage in which an operator, and possibly
tools and/or cargo, may be lifted. Basket assembly 34 includes
pivotal links and hydraulic cylinders so that it may be raised,
lowered, extended, etc. with respect to the far end of the upper
boom 28. Furthermore, basket assembly 34 may include components to
provide users with automated, or semi-automated, leveling to ensure
that basket assembly 34 remains substantially level. In the
embodiment shown in FIG. 1, an extendible link 36 is provided
between the basket assembly 34 and the upper boom 28. The
extendible link 36 provides users with apparatus for extending a
length of the upper boom 28, and thus extending a reach of the
basket assembly 34.
[0020] A counterweight 38 (shown in FIGS. 2-4), may be included. In
some embodiments, counterweight 38 has a counterweight portion
located on both sides of the lower boom 16. For illustration
purposes, only the counterweight portion behind lower boom 16 is
shown in FIGS. 2-4.
[0021] In the preceding paragraphs, embodiments showing some of the
elements of the present invention have been described. In the
succeeding discussion, the system characteristics leading to
improved operation are described in regards to FIGS. 2-4, in which
the aerial lift is shown with the hydraulic cylinders in extreme
positions.
[0022] In FIG. 2, upper hydraulic cylinder 32 is shown in a fully
extended position while lower hydraulic cylinder 20 is shown in a
fully retracted position. In practice, upper boom 28 and lower boom
16 can be adjusted to position basket assembly 34 close to the
desired location, i.e., rough location. To more finely adjust the
basket to placement into the desired location, basket assembly 34
can be raised, lowered, and rotated independently of upper boom 28
and lower boom 16. As shown in FIG. 2, basket assembly 34 is in a
lower position, but can be raised as needed to obtain further
height above vehicle 12.
[0023] Generally, bell crank 30 has three pivots: a lower boom
pivot 30a, a mechanical link pivot 30b, and an upper hydraulic
cylinder pivot 30c. As shown in FIG. 2, upper hydraulic cylinder
pivot 30c is below mechanical link 22. This limits the extent to
which upper hydraulic cylinder 32 can extend and thus limits the
rotation of upper boom 28 in the rearward direction.
[0024] In FIG. 3, both upper hydraulic cylinder 32 and lower
hydraulic cylinder 20 are shown in their fully extended positions,
i.e., a mostly vertical position. As discussed above, basket
assembly 34 can be raised from the position shown in FIG. 3 to
attain a slightly higher end position. Furthermore, extendible link
36 can be extended to its furthest position. When lower hydraulic
cylinder 20 is extended, lower boom 16 is caused to rotate about
pivot joint 18. Lower boom 16 acts on bell crank 30, the motion of
which is constrained by being coupled to mechanical link 22. The
pivot joint of bell crank 30, which is coupled to upper hydraulic
cylinder 32, is rotated so that it is in the interior of the obtuse
angle formed between upper boom 28 and lower boom 16.
[0025] In FIG. 2, the angle between lower boom 16 and upper boom 28
is about 45 degrees; whereas, in FIG. 3, the angle between lower
boom 16 and upper boom 28 is about 135 degrees. In both FIGS. 2 and
3, upper hydraulic cylinder 32 is fully extended. It is the
position of bell crank 30, as influenced by the position of lower
boom 16 and mechanical link 22, which causes the different relative
positions of the two booms. The relative angle between the two
booms, described in regards to FIGS. 2 and 3, is not intended to be
limiting, but is provided instead for illustrative purposes only.
The relative lengths of the booms, the mounting positions of the
hydraulic cylinders on the booms, the size and location of the
pivot joints on the bell crank, the position of the mechanical link
in relation to the lower boom, the extensions of the hydraulic
cylinders, and other parameters are parameters which influence the
angle in between the booms. Many alternative combinations of such
parameters are within the scope of the present disclosure and many
would provide for other angles between the booms.
[0026] In FIG. 3, hydraulic lines 40 and 42 are shown coupled to
bosses 41 and 43 on upper hydraulic cylinder 32. Bosses 41 and 43
and hydraulic lines 40 and 42 are not shown in FIGS. 1, 2, and 4
for illustration simplicity. When supplying fluid via hydraulic
line 40, the upper hydraulic cylinder 32 extends. When supplying
fluid via hydraulic line 42, the upper hydraulic cylinder 32
contracts. Lower hydraulic cylinder 20 has analogous hydraulic
lines 44 and 46. A lower operator-controlled actuator 48 and an
upper operator-controlled actuator 50 may be provided for operation
from within the basket assembly 34. In one embodiment, actuators 48
and 50 are push-pull levers. Actuators 48 and 50 control hydraulic
pressure supplied in lines 40, 42, 44, and 46. Other embodiments,
including electronically actuated actuators, may be used.
[0027] In FIG. 4, the combination of lower hydraulic cylinder 20
fully extended and upper hydraulic cylinder 32 fully retracted is
shown. Bell crank 30 is in the same position in FIG. 4 as in FIG.
3. Both FIGS. 3 and 4 show lower boom 16 in the furthest forward
position accessible (which is approximately 25 degrees rotated
toward the rearward direction from a vertical axis in the
embodiments shown in FIGS. 3 and 4). With upper hydraulic cylinder
32 fully retracted, this shows a position in which basket assembly
34 is far forward. In this example, counterweight 38
counterbalances the weight of basket assembly 34, upper boom 28,
and whatever cargo is in basket assembly 34.
[0028] Combinations of the extreme positions of hydraulic cylinders
20 and 32 are shown in FIGS. 1-4. Bell crank 30 and mechanical link
22 influence the range of motion of the lower boom 16 and upper
boom 28 such that a significant range of motion is provided in such
positions illustrated in FIGS. 1-4 as well as intermediate
positions of cylinders 20 and 32. However, bell crank 30 and
mechanical link 22 inhibit accessing unstable positions of the
aerial lift system, i.e., positions potentially leading to vehicle
tipping.
[0029] By adding bell crank 30 and mechanical link 22, as shown in
FIGS. 1-4, aerial lift 13 is prevented from accessing rearward
positions that might result in the vehicle tipping. The disclosed
system provides an advantage over prior art systems in that vehicle
tipping is prevented by a purely mechanical system . In prior art
systems, at least position sensors and a control system are used to
ensure that tipping positions are not accessed. Such systems depend
on the sensors providing an accurate measurement to the control
system, and the control system maintaining control over the
hydraulic cylinders. According to embodiments of the present
invention, tipping is prevented without relying on sensors and
actuators.
[0030] According to embodiments of the present disclosure, upper
boom 28 and lower boom 16 are directly linked with their range of
motion controlled via hydraulic cylinders, 20 and 32, mechanical
link 22, and bell crank 30. In some prior art systems, an
additional link is included between upper and lower booms. As each
link between the turntable and the basket adds to the amount of
play experienced at the basket, it is an advantage, according to
some embodiments of the present disclosure, that no such additional
link is employed.
[0031] Another advantage, according to the present disclosure, is
that the operator can directly control hydraulic cylinders 20 and
32 without relying on an electronic controller. In some prior art
systems, a controller is interposed between operator controls and
linear actuators to ensure that undesirable positions of associated
booms are not accessed. In other prior systems, an additional link
is provided between upper and lower booms and a complex control
scheme is employed to ensure that undesirable positions are not
accessed.
[0032] While the best mode has been described in detail, those
familiar with the art will recognize various alternative designs
and embodiments within the scope of the following claims. For
example, hydraulic cylinders 20 and 32 are shown in FIGS. 1-4.
However, any type of linear actuator, such as electro-mechanical
motors (such as a stepper motor), a linear motor, etc. can be used
in place of hydraulic cylinders. Where one or more embodiments have
been described as providing advantages or being preferred over
other embodiments and/or over prior art in regard to one or more
desired characteristics, one of ordinary skill in the art will
recognize that compromises, additions, subtractions or other
modifications may be made among various features to achieve desired
system attributes, which may depend on the specific application or
implementation. These attributes include, but are not limited to:
cost, strength, durability, life cycle cost, marketability,
appearance, packaging, size, serviceability, weight,
manufacturability, ease of assembly, etc. The embodiments described
as being less desirable relative to other embodiments with respect
to one or more characteristics are not outside the scope of the
disclosure as claimed.
* * * * *