Note: Descriptions are shown in the official language in which they were submitted.
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Suspension System for a Work Vehicle
Field of the Invention
This invention relates to a shock reducing suspension used with
agricultural work vehicles for connecting an implement such as a sprayer
boom assembly to the work vehicle.
Background
Agricultural work vehicles such as sprayers and wind rowers typically
comprise a work vehicle supported on wheels and to which is connected a
working implement with provision for raising and lowering the implement
relative to the ground and to the work vehicle. Typically this provision
comprises generally parallel arm linkages which maintain the orientation of
the
implement relative to the work vehicle as it raised or lowered. Particular
implements for use with a work vehicle may be a wind rower header or a
sprayer boom assembly. These implements may have additional supports such
as wheels to guide the height of the assembly above the ground or to make
intermittent contact with the ground to prevent other components of the
implement from contacting the ground, or they may have none at all. The
implement may be fully suspended by the work vehicle. Hydraulic actuators
are typically used for raising or lowering the implement. The actuators may be
connected between the parallel arms, or between one of the parallel arms and
either the work vehicle or the implement, or between the work vehicle and the
implement.
The work vehicle may of the type adapted to be pulled by a pulling
vehicle or may be self-propelled. The ground across which the work vehicle
moves may be uneven, subjecting the work vehicle to sudden vertical
components of movement. Sudden changes in movement of the work vehicle
are transmitted to the implement through the parallel arm connection and
result
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in shock forces between the work vehicle and implement through the parallel
arm connection.
In an effort to reduce work time and increase efficiency, implements
such as sprayer booms are generally being made longer to cover a wider area of
ground in a single pass. As the boom length increases, so does the mass of the
implement, and the resultant shock forces increase in proportion to that mass.
Uncontrolled movement of the implement can also result in undesirable
variations in the work being performed, for example, variations in spray
pattern
on a field from liquid spray nozzles mounted across a spray boom.
Prior attempts have been made to reduce the shock forces that result
from sudden changes in movement such as those shown in US patents 5375767
and 4197999. These patents show spray boom assemblies with parallel arm
connections to a work vehicle in which springs and dampers are used to allow
controlled movement between the work vehicle and implement and to reduce
acceleration of the implement and minimize shock forces. However, these
designs do not have convenient means to adjust the height of the spray boom
relative to the work vehicle or relative to the ground.
Other known prior art designs known have hydraulic actuators used to
control movement between a work vehicle and an implement connected to it by
parallel arms. Some of these include hydraulic accumulators in the circuit in
which the actuators are connected so that increased forces are absorbed by the
accumulator.
Another prior design is used on machines made by Redball in which a
hydraulic actuator is used to control movement between a work vehicle and
spray boom connected to the work vehicle by parallel arms. In this design a
suspension device is mounted to the work vehicle comprising of a rockshaft
supported at both ends to the vehicle by torsional elastic joints as are
disclosed
in patents of Neidhart US 2712742 or Henschen US 5411287 and US 3436069.
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An arm extends from the rockshaft and one end of the hydraulic actuator is
connected to an end of the arm offset from the rotational axis of the
rockshaft.
The other end of the actuator is connected to the spray boom implement or to a
parallel arm near one end which is connected to the spray boom implement.
Force from sudden changes to vertical movement of the implement act through
the hydraulic actuator and arm to be absorbed by the elastic joints through
rotation of the rockshaft.
It is desirable to provide a suspension system for agricultural work
vehicle implements that allows for adjustment of the height of the implement,
is
effective at such various heights to reduce shock forces from sudden changes
in
vertical movement of the implement, and which is comparatively less
expensive and less complicated than that of the prior art. It is desirable
that
such suspension system be easily incorporated into the boom lift linkage which
supports the implement on the work vehicle.
Summary of the Invention
A suspension system for supporting an implement on a work vehicle, in
= accordance with one aspect of the invention includes: a linkage mechanism
adapted for pivotal connection between the work vehicle and the implement
and adapted to pivot in such manner as to permit relative upward and
downward movement between the vehicle and the implement while
maintaining a controlled or selected orientation between them; a hydraulic
actuator capable of extending and retracting and adapted to interact between-
the
work vehicle and the implement when in use so as to effect the pivotal motion
of said linkage and relative motion between the vehicle and implement in at
least one direction; and a shock absorber adapted to be interposed between
said
hydraulic actuator and one of the work vehicle and the implement for absorbing
shock loadings tending to pass between the vehicle and the implement via said
hydraulic actuator when in use and regardless of the degree of extension or
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retraction of said actuator.
In another aspect the invention provides the combination of an
agricultural work vehicle, an implement and a suspension system as recited
above.
The shock absorber preferably includes a resilient cushion to absorb the
shock loadings tending to be transmitted via said actuator.
The shock absorber also preferably includes an elongated link mounted
for pivotal motion at a point between opposing ends thereof, one end portion
of
said elongated link being connected to an end of said actuator and the other
end
of said link being in a load transmitting relation to said resilient cushion
whereby forces exerted by or on said actuator tend to effect pivotal motion of
said elongated link and are transformed into compression forces on said
resilient cushion.
The linkage mechanism preferably comprises upper and lower arm
assemblies both of which have joints at their opposing ends to allow for
pivotal
connection thereof between the work vehicle and the implement. The
elongated link of the shock absorber is also preferably mounted for said
pivotal
motion at a point which is co-axial with the joints at one end of one of said
arm
assemblies.
The suspension system advantageously includes mounting bracket
securable to one of said implement and work vehicle and co-operating with the
joints at said one end of said one of said arm assemblies to define a pivot
axis
therewith co-axial with the pivot axis of said elongated link. The mounting
brackets preferably further define bearing surfaces with each said resilient
cushion being interposed between a respective one of the bearing surfaces and
a
respective said other end of an associated said elongated link.
A further resilient cushion may be associated with another one of said
bearing surfaces and said elongated link such that said shock absorber is
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capable of absorbing both compressive and tensile shock loadings passing
through said hydraulic actuator. Each said resilient cushion is preferably of
a
resilient polyurethane material.
In a preferred form, said hydraulic actuator is connected in use between
one of said arm assemblies and said one end portion of said elongated link of
the shock absorber. The upper and lower arm assemblies may also be of
equal length so as to form a parallel arm linkage system, said hydraulic
actuator
having one end thereof connected adjacent to an end portion of one of said arm
assemblies while the other end of said actuator is connected to said one end
portion of said elongated link.
Other aspects of the invention will be apparent from the following
specification.
Brief Description of Drawings
Fig.1 shows a side view of a suspension system according to the present
invention;
Fig.2 shows a perspective view of the suspension system shown in Fig. 1;
Fig.3 shows a perspective exploded view of the suspension system
shown in Fig.1;
Fig.4 shows a rear view of a work vehicle with a product applicator
boom implement;
Fig.5 shows a side view of a work vehicle with a product applicator
boom implement;
Fig.6 shows a top view of a work vehicle with a product applicator
boom implement.
Detailed Description
Embodiments of the invention are described here in terms of a
suspended boom sprayer as shown in Figs. 4-6, but it is recognized that it may
also be incorporated in conjunction with other implements such as wind rowers.
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The drawings illustrate a preferred suspension system connection 10 between a
work vehicle 12 and a sprayer boom assembly 14 including pairs of arm
assemblies arranged as a parallel arm linkages. Parallel arm linkages include
at
least two arms that are generally parallel. Typically each arm has a pivotal
connection on each end spaced the same distance between each other as on the
other arms of the linkage, i.e. the arms are of the same effective length. Two
component items can be connected together by the linkage arms to maintain
their angular orientation relative to each other while allowing relative
movement to each other.
Alternately other linkages may be used having arms of different length,
or arms that are not parallel, for connecting two component items to each
other.
This geometry of arms may be desirable for connection of two items and
controlling their angular orientation which changes in a selected manner as
the
arms are rotated and as the component items are moved relative to each other.
In the embodiment shown in Fig.l the suspension system 10 includes an
upper arm assembly 16 including a horizontally spaced pair of arms pivotally
connected to the work vehicle 12 at a pair of generally horizontal joints 18
for
pivotal movement in a generally vertical plane about the joints 18. The upper
arm assembly 16 is also pivotally connected to the sprayer boom assembly 14
at a pair of generally horizontal joints 20 for pivotal movement in a vertical
plane about the joints 20. A lower arm assembly 22 is pivotally connected to
the work vehicle 12 at a pair of generally horizontal joints 24 and to the
sprayer
boom assembly 14 at a pair of generally horizontal joints 26 for pivotal
movement in a vertical plane about the pairs ofjoints 24 and 26. Joints 24 and
26 of the lower arm assembly 22 are spaced from each other a distance equal to
that between joints 18 and 20 of the upper arm assembly 16. The joints 24 and
18 at which the arm assemblies 22 and 16 are connected to the work vehicle are
also spaced the same distance apart as the joints 26 and 20 at which the arm
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assemblies are connected to the sprayer boom assembly 14. With this parallel
arm linkage suspension connection the sprayer boom assembly angular
orientation relative to the work vehicle is maintained constant as the sprayer
boom assembly 14 is moved relative to the work vehicle 12.
A pair of hydraulic actuators 28 are pivotally connected at their base
ends to tabs 30 fixed on the arms of the upper arm assembly 16, near the ends
of the arm assemblies which are connected to the spray boom assembly at joints
20. The rod ends of the actuators 28 are connected at joints 32 to (upper)
first
ends of respective suspension links 34 forming part of a shock absorbing
system to be described below..
Fig.3 shows the suspension links 34 in more detail. Each suspension
link 34 has a second (lower) end 36 through which there is a bore for
receiving
elongated fastener 38. The links 34 are also connected intermediate their
first
and second ends to the joints 24 at which the lower arm assembly 22 is also
connected. This joint comprises a journal at the end of each lower arm,
journals through the suspension link 34, and a pin 40 which is held secure in
an
associated mount bracket 42 fixed to the work vehicle frame. Each suspension
link 34 comprises two elongated side plates 35 which straddle the associated
arm of the lower arm assembly 22 when the joint is assembled. The second
(lower) end of the suspension link 34 includes a tab 37 joining the side
plates
35 through which the fastener 38 receiving bore extends. This tab also
provides a bearing surface 44 for abutting with a resilient cushion 46. The
mounting bracket 42 also has spaced parallel side plates between which is
attached a further tab 47 with inner and outer bearing surfaces 48 and 50
respectively. This further tab 47 also has a bore for receiving the fastener 3
S.
The shock absorber for the suspension system includes the suspension
links 34, resilient cushions 46, and second resilient cushions 52. The
cushions
46 and 52 and washers 54 each have a central bore through which fasteners 3 8
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extend to retain their co-axial positions. The fasteners 3 8 each extend
through
the bore through the bearing surface 44 and through a bore through the
surfaces
48 and 50 of the further tab 47 of mount bracket 42. The first resilient
cushion
46 is retained in position between the suspension link bearing surface 44 and
the mount bracket inner bearing surface 48. The second resilient cushion 52 is
retained in position between the washer 54 and the outer bearing surface 50.
The washer is retained by the head of the fastener 38 and the fastener 38 is
also
secured to the tab 37 of the suspension link 34 by a threaded nut on the side
of
the tab opposite the bearing surface 44.
As best seen in Fig.1, when the sprayer boom assembly 14 is decelerated
from a downward movement or accelerated upward, due to movement of the
work vehicle 12 over uneven ground, then the actuators 28 will resist
compressive forces acting on the actuators. These forces will act on the
suspension links 34 tending to pivot same about joints 24, with said forces
being transformed to compressive forces acting on the resilient cushions 46,
each cushion abutting between bearing surfaces 44 and 48. Deceleration from
upward movement or acceleration downward may impose tension forces on the
actuators 28. These tension forces would be transmitted through the
suspension links 34, and through the fasteners 38 to act on the washers 54,
imposing compressive forces on the second resilient cushions 52 abutting
between outer bearing surfaces 50 and the washers 54.
Shock forces from situations contemplated above are in which the
actuators 28 resist movement in at least one of the extending and retracting
directions. The shock absorbers also conveniently absorb shock forces that
may result if actuators 28 are stopped abruptly when being retracted to lower
the sprayer boom assembly 14 relative to the work vehicle 12, in which case
the
resulting shock forces from the abrupt stop are also absorbed by the resilient
cushions 46.
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In a preferred embodiment the actuators 28 have been found to need
only be single acting hydraulic cylinders resisting compressive forces only.
The second resilient cushions 52 minimize shock that may otherwise occur if
the actuators are suddenly extended to their limit.
The preferred embodiment has the hydraulic actuators connected at the
base end to the upper arms 16 and at the rod end to the suspension links 34 at
joints 32. Successful operation of the system is dependent on one end of each
actuator being connected to its associated suspension link; however, it is
recognized that other embodiments of the suspension system may be
constructed. An example of one alternate may have a second end of each
actuator attached to the spray boom assembly at points which provides
actuation of the suspension system, whether it be a system having parallel
arms
or otherwise as discussed above. The actuator may be connected at points at
which the actuators must retract to raise the sprayer boom assembly, or at
points such that it must extend to raise the sprayer boom assembly.
Alternately
the shock absorbers may otherwise be connected to the sprayer boom assembly
and the second ends of the actuators connected to either the upper arms or
lower arms of the suspension system, or to the work vehicle. Again each
actuator may function while either extending or retracting to raise the
sprayer
boom assembly, depending on where its second end is connected and where the
shock absorber is connected. The shock absorbers can alternately be
connected with the intermediate joints coaxial with joint 18, or at separate
locations. The advantages of the invention are gained in the simplicity of the
shock absorber design and its connection with the actuators.
The resilient cushion 46 and second resilient cushion 52 are preferably
constructed of polyurethane material. They are preferably disc shaped with a
central bore. The resilient cushions diameter and thickness dimensions are
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dependent on the mass of the sprayer boom assembly 14, or other implement
and the degree of shock absorbing effect desired. For various alternate
constructions as described above, the proportionate relative size of cushions
46
and 52 may be reversed from what is seen in Fig.1 or Fig.3 if the predominant
shock forces act on the second resilient cushion 52. The actuator may be
single or double acting as required.
The suspension system preferably includes two pairs of parallel arms as
shown in Fig.2 and Fig.3. The lower arms of each pair are preferably
connected together by cross members as shown which provide lateral stability
of the suspension system so that the implement does not move laterally
relative
to the work vehicle 14. Alternately the upper arms may be connected together,
or both sets of arms, upper and lower. Still further the suspension system
may be constructed of arms that are not contained in the same vertical plane.
This can include a suspension system that has two lower arms cross connected
as shown in Fig.3, but with a single upper arm located above and between the
lower arms. One or more actuators may be used in suitable locations as
described above with associated shock absorbers connected between the
actuator and either the work vehicle or the implement.
Another alternative construction is one in which the hydraulic actuator is
connected to and between the upper and lower arms with the connection to one
of said arms being via a lever pivotally joined to the arm and having one or
more resilient cushions to restrain its pivotal movement relative to the arm,
thus
serving to absorb shocks tending to pass via the actuator between the work
vehicle and the implement. Again, as with the other embodiments described,
the hydraulic actuator interacts between the work vehicle and the implement to
effect relative motion between them while the shock absorber, interposed
between the actuator and either the work vehicle or the implement, serves to
absorb shock loadings tending to pass between the vehicle and the implement
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via said hydraulic actuator.
Preferably the shock absorbers described above include the resilient
cushions described above to restrain rotational movement of the suspension
link in both the clockwise and counterclockwise directions about its
intermediate joint. However, in some situations, restraint of motion may be
required in only one direction in which case a single resilient cushion may be
used, or the restrained end of the suspension link may be restrained by other
means, such as by springs or a unitary cushion that provides restraint in both
directions.
As previously indicated, the invention is not limited in application to
sprayer boom assemblies but is applicable to boom assemblies that may be used
for application of agricultural products other than liquids, such as granules,
and
to other implements such as wind rower headers.
These and other embodiments of the invention will become apparent to
persons skilled in the art without departing from the spirit and scope of the
invention defined in the claims attached.
