Note: Descriptions are shown in the official language in which they were submitted.
CA 02358883 2001-10-09
CROP HARVESTING HEADER WITH CAM CONTROLLED
MOVEMENT OF THE REEL FINGERS
This invention relates to a crop harvesting header including a cutter bar
and a reel for controlling movement of the crop in the area over the cutter
bar. The
reel is rotatable about an axis generally parallel to the cutter bar and has a
plurality
of reel bats each having reel fingers projecting generally radially outwardly
from the
reel axis. The reel bats are pivotal each about a respective bat axis parallel
to the
reel axis so as to vary the angle of the fingers about the bat axis as the
reel rotates.
The reel co-operates with a cam carried on the header in generally stationary
position so that each bat has a crank arm with a cam follower on the crank arm
which follows the cam as the reel rotates and causes the required pivotal
movement
of the bat.
BACKGROUND OF THE INVENTION
Attention is directed to copending Application Serial No INSERT filed
on the same filing date (Remillard-- Attorney Docket No. 80070-3302) assigned
to
the same assignees which discloses a header using the same invention as set
forth
herein, the disclosure of which is incorporated herein by reference.
Some headers of the above type include a reel which has the reel axis
fixed relative to the header and particularly the cutter bar. Many of these
headers
include a cam which is fixed on the end frame of the header and is shaped in a
complex non-circular pattern so that the fingers follow a complex non-
cylindrical
path.
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Other headers of this type include a reel which is mounted on reel
arms which can raise and lower the reel relative to the cutter bar to provide
different
conditions for different crops.
In US Patent 4751809 (Fox et al) assigned to the present applicant is
disclosed an arrangement in which the movement of the bats is controlled by a
rotating ring carried by the reel on the same reel arms but rotating about an
axis off-
set from the reel axis.
In US Patent 6170244 (Coers et al ) assigned to Deere and Company
and in Canadian Application 2289164 also by the same inventor is disclosed an
arrangement in which the reel is mounted on reel arms and there is provided a
cam
which is carried also on the reel arms so that it raises and lowers with the
reel but it
is held at a position so that it does not rotate with the reel and controls
the angle of
the bats by crank arms and cam followers travelling on the cam.
The present invention is concerned with headers including a reel both
of the type in which the reel is fixed relative to the cutter bar and of the
type in which
the reel is mounted on arms which allow the reel to raise and lower relative
to the
cutter bar.
Pickup reels which use a cam path to establish desired finger angles
relative to the cutting device are used on forage and crop harvesting
equipment.
Conventional designs use a rotating reel with one or more transversely mounted
sets of fingers mounted at fixed radius to the reel center. Each set of
fingers, on a
bat, also has the ability to rock about its own axis of rotation that is
parallel to the
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reel axis. A crank arm with a cam follower is fixed rigidly to each set of
reel fingers.
The cam follower follows a cam path that is shaped to change finger angle as
the
reel rotates.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a header which
includes an improved drive to the bat fingers.
According to a first aspect of the invention there is provided a crop
harvesting header comprising:
a header frame structure arranged for movement in a direction of
working movement across ground carrying a crop to be harvested;
a cutter bar arranged across a forward edge of the header frame
structure for cutting the crop;
a cut crop transport arrangement mounted on the header frame
structure for receiving and transporting the cut crop for further processing;
and a reel for controlling movement of the crop in the area over the
cutter bar;
the reel being mounted on the header frame structure for movement
therewith in the direction of movement and for rotation about a reel axis
generally
parallel to the cutter bar;
the reel having a plurality of reel bats at spaced positions around the
reel axis each having reel fingers projecting generally radially outwardly
from the reel
axis;
each of the reel bats being pivotal about a respective bat axis parallel
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to the reel axis so as to vary the angle of the fingers about the bat axis as
the reel
rotates;
a stationary cam mounted on the header frame structure at the reel in
stationary position relative to the reel axis;
each bat having associated therewith a crank arm with a cam follower
on the crank arm which follows the cam as the reel rotates such that the
movement
of the follower in the cam as the reel rotates relative to the cam causes the
crank
arm to move relative to the bat axis to generate the required pivotal movement
of the
bat;
wherein, for each of the bats, the cam follower is arranged in the cam
at a position which is angularly advanced about the reel axis relative to the
bat axis.
The header frame structure may include reel arms which support the
reel and cam for up and down movement relative to the cutter bar or more
preferably
the reel may be directly mounted on end frame elements fixed relative to the
cutter
bar.
The term "bat" used herein is not intended to imply any particular
shape or construction of the bat and this may comprise merely a tube,
sometimes
known as a tine tube, or other longitudinal structural member which carries
the bat
fingers so as to project radially outwardly from a longitudinal bat axis of
the bat.
Preferably, for each bat, the respective crank arm has an end thereof
opposite the cam follower directly connected to the bat at a fixed angle
relative
thereto. However other arrangements of the crank arm can be used including
intervening links between the crank arm and the bat, for example of the type
shown
CA 02358883 2001-10-09
in the above mentioned copending application.
The fixed angle between the crank arm and the bat fingers while fixed
during use may be adjustable to obtain different finger action.
In this arrangement, the opposite end of the crank arm is preferably
5 fixed to the bat so as to rotate about the bat axis.
In this arrangement, the angle between the crank arm and the bat
fingers is greater than 90 degrees, more preferably in the range 110 to 160
degrees
and most preferably of the order of 135 degrees.
Preferably the cam is arranged such that the path length in a bottom
half is less than a path length in an upper half.
Preferably the cam is arranged such that the cam lies radially inwardly
of the path of the bat axes in a bottom part of the cam and lies radially
outwardly of
the path of the bat axes in an upper part of the cam.
Preferably the cam is arranged such that the path length thereof per
degree of rotation of the reel is shorter in the angles of movement of the
reel where
the fingers are in engagement with the crop than at other angles.
Preferably the length of the crank arm from the bat axis to an axis of
the cam follower is at least 3.0 inches and preferably of the order of 5.0
inches.
Preferably the reel is arranged such that the bat fingers at bottom dead
center of the reel relative to the reel axis are in front of the cutter bar,
such that the
bat fingers follow a finger pattern in which the bat i:engers are angularly
advanced
about the respective bat axis to the greatest extent at a position in front of
bottom
dead center, are generally radial at the bottom dead center and are angularly
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retarded to the greatest extent at a position behind and upwardly of the
cutter bar.
The improved arrangement defined above may result in greater
clearance to crop entry, improved mechanical advantages, improved range of
motion and improved cam durability.
The major difFerence with the new invention is that the finger to crank
arm angle is set so that the crank pushes the follower through the cam path
rather
than pulling the follower through the cam track as in conventional designs.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
Figure 1 is a schematic side elevational view of the frame, reel and
cam of a header according to the present invention.
Figure 2 is a similar schematic side elevational view of the frame, reel
and cam of a conventional header.
Figure 3 is a top plan view of one end of the header of figure 1.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
DETAILED DESCRIPTION
The embodiment shown in the drawings is related to the MacDon
header for a self propelled auger which is currently sold under the model
designation
922 which has been available for two years but a similar design under previous
model numbers has been available for a number of years. A similar construction
is
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used in the corresponding pull-type header which is sold under the model
designation 5010. Thus the details of this machine are readily available to
one
skilled in the art and are not described and discussed herein except in
relation to the
particular aspect to which the invention relates.
However in general and schematically there is shown a frame structure
generally indicated at 10 which includes a main beam 11 extending across the
width
of the frame and two end frame members 12 which extend downwardly and
forwardly from the beam. The frame structure includes elements for mounting on
a
suitable tractor vehicle of a conventional nature. The frame structure
includes a
platform 13 onto which crop material is deposited after cutting by a cutter
knife at a
cutter bar 14. On the platform 13 is provided an auger roll 15 which receives
the
crop material from the cutter bar and carries the crop material to a discharge
opening. All these elements are of course of conventional nature so that they
will
not be described in detail and various forms of cutter bar can be used all of
which
are available to one skilled in the art.
The end frames 12 carry a reel 16 which extends across the width of
the header above the cutter bar 14. The reel comprises a shaft 17 mounted for
rotation on the end frames so that the position of the shaft is fixed relative
to the
cutter bar 14. The shaft is located above and in front of the cutter bar and
is carried
on suitable bearings. The reel further includes a plurality of bats 18 at
angularly
spaced positions around the axis 19 of the shaft 17. In the embodiment shown
each
bat comprises a bat tube 20 to which is attached a plurality of bat fingers 21
which
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project outwardly from the bat tube at a predetermined angle. Thus, as is well
known, each tube carries a plurality of bat fingers at spaced positions along
its
length with the bat fingers arranged at the same angle relative to the axis 22
of the
bat.
The bat tubes 20 are mounted on reel support arms 23 of a support
plate 24. The number of support plates along the length of the reel may
variable in
dependence upon the length of the reel so that the tubes may be supported at
the
plurality of spaced positions along the length of the reel to maintain the
tubes at a
predetermined radial spacing from the axis 19.
Each tube includes a crank arm 25 which is attached to the tube so
that an inner end of the crank arm rotates with the tube around the axis 22.
Thus
each crank arm is attached to its respective bat tube at a predetermined set
angle
relative to the bat fingers, although this angle may be adjustable.
Each crank arm 25 includes a cam follower 26 at its outer end
mounted for rotation on the crank arm about a follower axis 27. The cam
follower
comprises a roller received between two side walls of a cam track 28 extending
in a
path around the axis 19 of the reel. The cam defines a complete path around
the
axis of the reel but is offset from the axis and is non-circular so that the
crank arms
are moved so as to rotate around the respective bat axis to define a
particular finger
pattern of movement of the fingers as the reel rotates.
Conventionally the finger pattern is arranged so that, at a bottom dead
center position indicated at 30, the fingers extend substantially radially
outwardly
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from the axis 19. At a position 31 forwardly of the bottom dead center
position, the
fingers are angularly advanced around the bat axis 22 so that they extend
forwardly
from a radius of the reel. At a third position 32 rearwardly of the bottom
dead center
position, the fingers are retarded relative to the radius from the axis 19.
This general
finger pattern has been used for many years and is accepted to provide the
required
action on the crop so that the angularly advanced position of the fingers as
the
fingers enter the crop is advantageous in a grasping action on the crop
followed by
the crop being carried rearwardly by the radial fingers at the bottom dead
center and
then at the position rearward of the cutter bar, the fingers move to a
retarded
position so that they can more effectively lift out of the crop lying on the
platform.
Slight modifications to this general finger pattern can be used as will be
known to one skilled in the art, for example the finger pattern may include a
further
advancement of the fingers to an angularly advanced position at the location
where
the fingers pass over the cutter bar so as to more effectively clear the
cutter bar.
The above description relates equally to the present invention and to
the conventional arrangement shown in figure 2.
The arrangement of the present invention is modified relative to the
conventional arrangement in that instead of the cam followers 26 being
angularly
behind the respective bat axis so as to be pulled in the cam track, in the
present
invention the cam followers are moved to a position angularly advanced of the
respective bat axis so that the cam followers are pushed within the cam track.
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While this modification may on the face of it appear to be relatively
minor, this modification is counter-intuitive since it would normally be
expected that
the pulling of the cam follower would provide reduced forces and reduced wear.
However complex calculations show that, contrary to this expected situation as
adopted in all conventional arrangements of this type, the movement of the cam
follower to an advanced position provides significant advantages in reducing
loads
between the cam track and the cam follower and decreasing wear on the
components. These advantages are set forth in more detail herein after.
This arrangement further provides an angle A between the crank arm
and the bat fingers which is greater than 90 degrees and more preferably of
the
angle set forth herein before.
Yet further this arrangement allows an increase in the length of the
crank arm by an amount of the order of 25 percent. Thus the crank arm can have
a
length as defined herein before and this increased length thus provides
increased
mechanical advantage and thus reduce loads on the cam follower.
It will be noted that the cam path which is shaped to provide the
conventional finger action is completely different in the arrangement of the
present
invention shown in figure 1 relative to the conventional arrangement. Thus it
will be
noted that the cam path in the lower half of the cam is significantly shorter
per
degree of rotation of the reel than is cam path in the upper part. It will be
noted that
the situation is the opposite in the conventional arrangement. This reduction
in
length of the cam path in the lower part where the fingers are undergoing
significant
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loading from the engagement with the crop significantly reduces the speed of
movement of the cam followers in the lower part and thus reduces forces and
wear
on the cam follower in the lower part. It will be noted that in order to
achieve this
reduced cam path length, the cam track moves to a position radially inward of
the
path of movement of the bat axis in the lower part of the cam path whereas the
cam
path is outside the path of movement of the bat axis in the upper part of the
cam.
Again it will be appreciated that this arrangement is opposite in the
conventional
arrangement.
As set forth above, the value of angular lead, A1, will vary through
each rotation, but can never shrink to zero or an over center condition will
occur,
causing the fingers to flip. Also, as A1 approaches zero the reaction forces
exerted
by the cam path to the cam follower become very high (theoretically infinite).
For the
same reasons the angular lag of a conventional design can never shrink to
zero.
This shows that the new invention operates in distinctly different angular
range from
the conventional design.
Another difference is in the reaction force created when the follower
contacts the cam track . The cam track/follower arrangement usually consists
of a
rolling member trapped between closed surfaces. Note that in the convention
trailing
arrangement, if crop load is applied to the fingers in the direction shown,
the torque
created will be opposed by a corresponding reaction force between the cam
follower
and the inner surface of the cam track. In the arrangement of the present
invention,
the same crop loads results in a reaction force on the outer surface of the
cam track.
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The arrangement as described above has the following advantages:
a) Advantageous geometric relationships allow the device to offer
superior mechanical advantage to the conventional design when averaged
throughout a complete rotation. (This is true even when comparing arrangements
with equal length crank arms, identical finger patterns and identical length
cam
paths.) This allows the invention to provide lowered forces on the mechanical
components and/or increased range of finger movements.
b) The device offers greater clearance to ground and to crops for
the cam, cam followers, and crank arms. This gives improved crop flow by
removing
obstructions and reducing risk of crop getting tangled in the cam components.
c) The device makes longer crank arms more practical since the
longer arms have no adverse affect on clearance to ground and crops. The
longer
crank arms provide a further increase to the mechanical advantages of the
system.
d) The device reduces cam wear due the cam surface/follower
contact characteristics. In the new invention crop load creates reaction
between the
cam roller and the concave outer surface of the cam path. In conventional
designs,
the crop load creates reaction forces between the cam follower and the convex
inner
surface of the cam path. Although both cases are theoretically point to point
contact,
real systems under load always have deflection at the point of contact. The
contact
characteristic of the new invention concave outer surface will offer superior
bearing
area under load, and therefore decreased wear characteristics.
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e) The device offers reduced cam wear in the portion under heavy
crop load since the cam path in the loaded area (lower half of cam) is shorter
than
the conventional design. The shorter path results in slower follower velocity
and
therefore reduced mechanical wear.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
within the spirit and scope of the claims without departing from such spirit
and
scope, it is intended that all matter contained in the accompanying
specification shall
be interpreted as illustrative only and not in a limiting sense.
