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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to crop harvesters, and more
particularly to such a harvester which is adapted to travel along a row of
crops, and to engage said crops and bring them more closely together to
enhance the harvesting operation of the crops.
2. Background Art
There are in the prior art harvesting machines which are adapted to harvest
such crops as berries, grapes, fruit, other produce from standing plants.
Normally such machines comprise a chassis having two side portions which
define therebetween a crop engaging area. As the machine travels down a
crop row, the crops pass between the two side portions of the machine, and
suitable harvesting implements, such as beater rods or the like engage the
crop to shake the crop and thus cause removal of the berries or other food
product.
It has been found that this harvesting operation can be enhanced if the
lower portions of the crops or plants can be engaged so as to squeeze the
lower portions of the crops toward the row centerline. Accordingly, one
prior art device for accomplishing this is to have two crop engaging belts
positioned on opposite sides of the crop, with these belts being urged
toward a center location so as to engage the crops with the appropriate
pressure. These two belts are then driven so that the crop engaging
portions thereof travel rearwardly at substantially the same speed as the
forward travel of the vehicle, so that the crop engaging belt portions are
"stationary" relative to the crop. Thus, there arises a need to coordinate
the rearward speed of the belt engaging portions with the forward travel
of the machine. Such an aggregating device is disclosed on pages 33 and 34
of a book entitled "Mechanical Harvesting of Raspberries: Development of a
System for Scottish Conditions", authored by A. M. Ramsay, published by
the Scottish Institute of Agricultural Engineering, Technical Report No.
7. Also, illustrations of this same system are shown in photographs
appearing in different parts of this publication.
U.S. Pat. No. 4,204,389 (Delfosse) shows an endless conveyor in a
harvester, the conveyor being timed to be stationary relative to the crop.
One means of monitoring the ground speed of the harvesting machine so that
the speed of a crop engaging member can be controlled is by actually
measuring the forward speed of the machine and then providing control
means responsive to the forward speed of the machine. One method of
accomplishing this is by means of a ground engaging wheel which engages
the ground and thus rotates at a speed proportional to the forward
velocity. One such system is shown in U.S. Pat. No. 4,176,511 (Scudder et
al), entitled "Conveyor System for a Harvester", where there are shown two
conveyors in the form of endless belts which are positioned on opposite
sides of the crop row and which travel rearwardly relative to the machine
so that these are "stationary" relative to the crop row. With reference to
FIGS. 8, 16 and 17, there is a hydraulic motor 30a which rotates the two
belt conveyors, with this motor 30a being driven by a motor 49 which
powers a pump 50 that in turn delivers hydraulic fluid through a throttle
control valve 53 that in turn delivers the hydraulic fluid to the motor
30a. To control the speed of the motor 30a, the hydraulic fluid that
passes from the motor 30a is directed through a feedback system to control
operation of the throttle valve 53. More specifically, there is an
unloaded ground engaging wheel 52, the speed of rotation of which is a
measure of the speed of forward travel of the machine. This wheel 52
connects through a shaft 59 to a drive transmission comprising gears 61,
62 and 63. The hydraulic motor 55 which is a positive drive motor driven
from the pump 30a rotates a gear 64 which in turn rotates a gear 58 which
in turn rotates the case 60 of the differential transmission. When the
speed of the hydraulic motor 30a matches the ground speed as indicated by
the wheel 52, the rotational speed of the differential casing 60 matches
the rotational speed of the shaft 59 so that there is no output from the
differential transmission, and the shaft 54 leading to the throttle valve
53 remains stationary. However, when a difference in the two speeds is
sensed, the shaft 54 will be cause to rotate to change the setting of the
throttle valve 53 so that the ground speed does match the speed of the
hydraulic motor 30a that in turn drives the belt conveyors. One of the
problems of this type of system is that not only must the operating
components be closely matched, but there is some margin of error in that
the ground wheel (such as a ground wheel 52) may not be a truly reliable
indication of ground speed. For example, if the ground surface has some
irregularities where the ground wheel must travel upwardly and downwardly
over the ground surface, the rate of rotation will increase relative to
the forward speed of the vehicle. Further, even though these ground wheels
can be arranged with devices to increase friction (high friction treads or
even pins or the like) which would engage the ground, there can under
certain circumstances be slippage of such wheels.
Various other systems and method time the speed of a conveyor or the like
to the rotation of a ground wheel, by using a governor responsive to
rotation of the ground wheel to control a throttle valve in a hydraulic
conveyor drive system, U.S. Pat. No. 3,414,200 (Savory), monitors for
monitoring the speed of the conveyor belt and of a vehicle which use
electro-optical aperture discs, U.S. Pat. No. 3,550,866 (Swenson),
magnetic sensors 46 for sensing and equalizing the speeds of a driven axle
and a non-driven axle, U.S. Pat. No. 4,441,848 (Bailey), chains and
sprockets, U.S. Pat. Nos. 4,195,570 (Rodriquez) and 3,901,005 (Rohrbach et
al) and an intermediate wheel 101 that meshes with a ground wheel and a
conveyor to drive the conveyor, U.S. Pat. No. 4,081,094 (Pereira et al).
Additionally, U.S. Pat. No. 4,212,428 (Walker) shows a ground wheel that
drives a pump 52. The pump 52 provides fluid pressure to operate a motor
36 that drives a conveyor belt.
SUMMARY OF THE INVENTION
The present invention relates to a system for positioning crops in a row
which is being harvested by a machine.
A system for positioning crops in a row which is being harvested by a
machine in a manner to minimize damage to the crops, comprises crop
aggregating means, crop aggregating drive means, and control means. The
crop aggregating means, connected to the harvester, aggregates the crops
by bringing first and second crop engaging means into engagement with the
crops as the crops pass rearwardly with respect to the machine in a
pathway defined between the first and second crop engagement means. The
crop aggregating drive means drives the crop engaging means rearwardly
along the crop engaging path with respect to the machine as the machine
travels forwardly relative to the crops. The control means responds to a
force imparted by the engaging means by engagement with the crops along
the crop engaging path, thereby matching the speed of the crop engaging
means with the speed of the machine. This protects the crops from the
effects of friction between the crop engaging means and the crops.
The drive means comprising a hydraulic motor, receives hydraulic fluid the
pressure of which is controlled by the control means. The control means
comprises pressure relief valve means operably connected to the hydraulic
motor, thereby controlling fluid pressure directed to the hydraulic motor.
The hydraulic pump means is operably connected to the hydraulic motor
means so as supply hydraulic fluid under pressure to the hydraulic motor
means. At a given volumetric flow rate of hydraulic fluid, the hydraulic
pump means drives the machine at a given linear speed which is less than
the linear speed at which the crop aggregating drive means drives linearly
the crop engaging means, at the given rate of volumetric flow.
Accordingly, with the speed of travel of the machine being equal to the
linear speed of the crop engaging means, the pressure relief valve means
remains in an open position to bypass a portion of hydraulic flow around
the aggregating drive means.
The pressure relief valve means is connected in parallel with the hydraulic
motor means in a manner that fluid flow above a preset pressure level is
bypassed from around the hydraulic motor. The pressure relief valve means
comprises pressure differential valve means which opens in response to a
predetermined difference in pressure at locations upstream and downstream
of the hydraulic motor.
Alternatively, the crop aggregating drive means comprises first and second
hydraulic motors connected to, respectively, the first and second crop
aggregating means, the control means comprising pressure relief valve
means positioned in parallel with the first and second hydraulic motors.
The pressure relief valve means comprises pressure differential valve
means which senses pressure at locations upstream and downstream of the
first and second hydraulic motors.
Also, there is selectively operable valve means connected between the
hydraulic pump means and the crop aggregating drive means to selectively
drive hydraulic fluid from the hydraulic pump means to the hydraulic motor
means, bypassing the crop aggregating drive means, or on a path through
the crop aggregating drive means to the hydraulic motor means.
In a second embodiment, the crop aggregating drive means comprises a
hydraulic motor means which delivers power to the crop aggregating means
and hydraulic pump means which delivers hydraulic fluid to the hydraulic
motor, the system further comprising ground speed monitoring means to
measure speed of the machine and to control output of the hydraulic motor
means in accordance with the speed of the machine. The control means
comprises pressure relief valve means operably connected to the hydraulic
motor means thereby controlling fluid pressure directed to the hydraulic
motor means, wherein at a given volumetric flow rate of hydraulic fluid,
the hydraulic pump means drives the machine at a given linear speed which
is less than a linear speed at which the crop aggregating drive means
drives linearly the crop engaging means, at the given rate of volumetric
flow. Accordingly, the speed of travel of the machine is equal to the
linear speed of the crop engaging means, with the pressure relief valve
means remaining in an open position to bypass a portion of hydraulic flow
around the aggregating drive means.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a harvesting machine employing teachings of
the present invention with the top removed and with portions of the
components removed for purposes of illustration, also including a
schematic representation of a drive system for the crop aggregating belts;
FIG. 1a is a detail of a positioning member which is used to support the
crop aggregating belt;
FIG. 2 is a front end view of the harvester of FIG. 1;
FIG. 3 is a view similar to the view of FIG. 1 showing a second embodiment
of the invention;
FIG. 4 is a schematic view of the pump and drive components in a hydraulic
system in the present invention;
FIG. 5 is a view similar to FIG. 4 showing a second embodiment of the
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a top plan view showing generally a harvesting machine 10
suitable for incorporating the system of the present invention. As is
common in the prior art, the operator's section 14 provides a seat 18 for
the operator and a manually operated steering wheel 20. In addition, the
operator's section 14 could provide a location for collecting the food
product that is being harvested and possibly serve other functions.
The harvesting section 16 comprises right and left frame portions 22 and
24, respectively, which define therebetween a middle crop harvesting area
or region 26. For purposes of description, the harvesting section 16 will
be considered as having a center longitudinal axis 28, and this axis 28
will generally coincide rather closely with a centerline of a row of the
crops which are being harvested.
In describing the present invention, the terms "inward" or "inwardly" will
denote a direction toward, or proximity to, the longitudinal center axis
28, while the terms "outward" or "outwardly" will denote the opposite.
In general, such harvesting machine 10 will comprise a turning means, such
as at least one forward steerable wheel (not shown for ease of
illustration) located at a forward corner of the machine, and being
steerable to properly align the machine 10, and a pair of rear wheels, one
of which is shown at 30, with at least one of these rear wheels being a
power driven wheel to move the machine. Also, as is common in the prior
art, there are provided suitable harvesting elements such as beater rods
32 which reciprocate to come into engagement with the crop so as to shake
the food product from the bushes or plants.
A suitable automatic steering means can be provided. Specifically, as shown
herein, there are two crop engaging members 34 positioned at a forward
location on the machine 10 on opposite sides of the longitudinal axis 28.
These crop engaging members have converging end portions 36 that define a
converging throat to receive the crop, and lateral displacement of these
crop engaging members 34 operate a suitable control mechanism which
automatically steers the front steerable wheel to maintain the machine 10
in close alignment with the crop row. Such a steering mechanism is
disclosed in a U.S. Patent Application, entitled "METHOD AND SYSTEM FOR
AUTOMATICALLY STEERING ALONG ROW CROPS" with the inventors being the same
as the inventors herein, this application being filed on May 19, 1989, the
contents of which are hereby incorporated by reference.
As indicated previously, the present invention is particularly directed
toward a means of aggregating the crop (i.e. squeezing the crop inwardly)
to enhance the harvesting operation. As shown herein, there is a crop
aggregating assembly 38 which comprises a pair of endless belts 40 which
are mounted at a lower location of the chassis 12 and are positioned on
opposite sides of the longitudinal axis 28. Each belt 40 has a forward
belt portion 42, which engages a related hydraulic drive motor 44 and
extends rearwardly and moderately inwardly to a crop engaging belt portion
46 that is positioned more closely to the longitudinal center axis 28.
Rearwardly of the crop engaging belt portion 46, the belt extends at 48
around a pair of rear idler wheels 50, with the belt having a return run
52 that leads to the aforementioned forward belt section 42 that engages
the drive motor 44.
To urge each of the crop engaging belt sections 46 into proper engagement
with the crop, there are provided along the length of the belt section 46
a plurality of positioning arms 54 as best shown in FIG. 1A. Each
positioning arm 54 is mounted at 56 and coiled to form a coiled spring
portion 57 leading to an arm portion 58 which extends from the mounting 56
rearwardly and inwardly to a respective roller 60 mounted at the rear
swing end of the arm portion 58, with this roller 60 engaging its related
crop engaging belt portion 46, the coil portion 57 bringing the arm
portion 58 into proper yielding engagement with the belt section 46. Thus,
it is imperative as shown in FIG. 1 that as the crops enter into the
harvesting area of the chassis 12, the two belt engaging portions 46
engage the crop (a couple of plants of this crop having the lower portions
thereof indicated at 62 in FIG. 2) with the appropriate pressure as
determined by the strength of the respective coiled spring portions 57) to
hold the lower stems of the crop plant 62 together.
As a preliminary comment, is to be understood that the main components of
the crop aggregating assembly 38 as described above are already known in
the prior art, and actually are shown in the publication noted under
Background Art, entitled "Mechanical Harvesting of Raspberries:
Development of a System for Scottish Conditions". One of the important
considerations in incorporating such a crop aggregating assembly 38 is
that the linear speed of each of the crop aggregating belts 40 closely
match the forward speed of travel of the machine 10 so that there is no
scruffing action which might damage the somewhat sensitive stems of the
plants. Further, it is desirable that the force exerted by the crop
engaging portions 46 be substantially a lateral inward force, and not a
longitudinally directed force which would have the tendency of possibly
damaging the stems.
With the foregoing in mind, there will now be a description of the drive
and control system of the present invention which, in combination with the
elements described above, provide unique advantages over the prior art.
To describe a first embodiment of the present invention, reference is made
to the schematic drawing of FIG. 4. There is a fluid reservoir 64 which
provides hydraulic fluid for makeup oil for a main hydraulic pump 66 which
in turn delivers fluid under pressure through a selectively operable
control valve 68. This control valve 68 has a first position (shown in
FIG. 4) where the fluid is moved directly through a line 70 to a main
hydraulic motor 72 that in turn rotates the one or more of the drive
wheels 30. The valve 68 can be moved to a second position where no fluid
is delivered through the line 70, the fluid is directed through a second
line 74 that leads to the two aforementioned hydraulic motors 44 which are
connected in series with one another. The hydraulic line 76 from the
second of these drive motors 44 then leads to the main hydraulic motor 72.
There is provided a differential pressure relief valve 78 that is connected
through a first line 80, and a second line 82 which extends from the valve
78 to the line 76 that leads from the second motor 44 to the main
hydraulic motor 72. This relief valve 78 is arranged so that it responds
to a pressure differential in the lines 80 and 82. This function is
indicated somewhat schematically, by the broken line 84 extending from the
first line 80 into one side of a valve element 86, and a second valve line
88 extending from the line 82 to an opposite side of the valve element 86.
A spring member 90 urges the valve element 86 toward its closed position,
as shown in FIG. 4. Thus, when the pressure differential in the two lines
80 and 82 is at a lower level, the force of the spring 90 will be
sufficient to maintain the valve element 86 in its closed position.
However, when the pressure in the line 80 exceeds the pressure of the line
82 by a predetermined margin, the hydraulic pressure will be sufficient to
move the valve element 86 (downwardly as shown in FIG. 4) to its open
position to cause hydraulic fluid to bypass the two motors 44. Also, the
spring member 90 is adjustable so that the level of the pressure
differential at which the bypass valve 78 will open can be accurately
adjusted.
With regard to the setting of the control valve 78, it is to be understood
that the pressure drop at locations upstream and downstream of the drive
motors 44 will be proportional to the resistance (primarily internal)
against the movement of the belts 40 of the crop aggregating assemblies
38. As indicated previously, it is desirable that the engagement of the
belt portions 46 against the crops 62 be such that there is essentially an
inwardly directed force (i.e. a "squeezing" force toward the longitudinal
center locating plane 28), and very little, if any, longitudinal force
which would tend to cause the belt portions 46 to possibly scruff away
bark or possibly damage the plants in some other way. Thus, the setting of
the pressure relief valve 78 should be such that it will react to a
pressure differential level which is just at the level at which the motors
44 are able to generate sufficient force to overcome the internal
resistance or power losses due to the operation of the assemblies 48
themselves.
In actual practice, a fairly close estimate of the setting of the valve 78
can be achieved simply by operating the belt aggregating assembly 38
without engaging any of the crop 62, and then manually grasping one of the
belts 40 to determine if the belt can be stopped simply by a moderate
force exerted by the person's hand. At such time as the person is manually
able to stop the belt without exerting an excessive amount of force on the
belt, the setting of the valve 78 would be at the level where the motors
44 are just able to overcome the internal operating resistance of the
assembly 38 and possibly deliver just slightly greater power to compensate
for any additional losses which might be contributed, for example, to
greater internal frictional resistance of the belt 40 against the
positioning rollers 58.
To describe the overall operation of the present invention, let it be
assumed that the machine 10 is traveling toward a crop, but is not engaged
in a harvesting operation. In this instance, the main control valve 68 is
set to the position shown in FIG. 4 so that there is no operation of the
crop aggregating assemblies 38. At such time as the machine 10 begins
moving into engagement with a crop row, the valve 68 is moved to its
second position (i.e. moved upwardly in the showing of FIG. 4) so that
hydraulic power is delivered first through the belt drive motors 44 and
thence through the main drive motor 72 which powers the drive wheel or
wheels 30 and possibly performs other functions of the machine 10. It is
to be understood that since the fluid flow path is in series between the
motors 44 and the motor 72, the relative speeds of these motors 44 and 72
are fixed. Desirably, these relative speeds are such that the linear speed
of the belts 40 is just greater than the speed of travel of the machine
10. Thus, with the relief valve 78 closed, there is a tendency for the
belts 40 to travel faster than the forward motion of the machine 10. For
this reason, in normal operation, the valve 78 will generally remain open
just to the extent to provide the proper balance of pressure on the
upstream and the downstream sides of the motors 44.
Under a situation where the pressure relief valve 78 is set at a level just
below the desired pressure level at which it should open, there could be a
situation where the power delivered by the hydraulic fluid to the motors
44 would not be sufficient to overcome the internal resistance of the
operation of the aggregating assembly 38. Under these conditions, the belt
engaging portions 46 would engage the crop 62, but there would not be
quite enough power to move the belt portions 44 to match the forward speed
of the machine 10. Under these circumstances, there would be a force
exerted by the plants 62 engaging the belts 40 to help move the belt
portions 46 rearwardly so as to supplement the power supplied by the
motors 44. Thus, it is to be understood that while the setting of the
pressure relief valve 78 is desirably set at the precise operating level,
and even if it is at a level just below the desired operating level, the
scruffing action against the plants is substantially alleviated.
Let us now examine a situation where the machine 10 requires that greater
power be delivered by the main hydraulic motor 72 to maintain an adequate
ground speed, with such a situation arising when the machine 10 is
traveling up an incline. Under these circumstances, the hydraulic pump 66
must necessarily deliver hydraulic fluid at higher pressure, and this
would in turn increase the pressure on the upstream side of the motors 44.
However, since the control valve 78 is responsive to differential pressure
on the upstream and downstream side of the motors 44, the power delivered
to the motors 44 would be substantially the same as if the machine 10 were
operating over a level surface where the drive power requirements are less
and the fluid pressure in the system upstream of the main drive motor 72
would be less.
A second embodiment of the present invention is illustrated in FIGS. 3 and
5, FIG. 3 being a top plan view of the machine and FIG. 5 being a
schematic drawing of the control system of the second embodiment.
Components of this second embodiment which are similar to those of the
first embodiment will be given like numerical designations, with an "a"
suffix distinguishing those of the second embodiment.
This second embodiment is distinguished from the first embodiment primarily
in that the drive system for the belts second embodiment is separated from
the main drive system of the machine. Thus, there is provided a relatively
small hydraulic pump 92 which draws fluid from a reservoir 94. This pump
92 is connected directly to a speed monitoring ground wheel 96 so that the
volume output of the pump 92 corresponds to the rotational speed of the
ground wheel 96. As shown herein, there is a direct drive connection
between the ground wheel 96 and the pump 92 so that the power for the pump
92 is derived from the ground wheel 96. However, power for the pump could
be derived from another source.
The pump 92 leads through an on/off valve 98 to the motors 44a which are,
as in the first embodiment, connected in series with one another and which
are operatively connected to the belts 40a, and the flow from the second
motor 44a leads directly back to the pump 92. There is a pressure relief
control valve 78a connected in parallel with the two motors 44a, but this
pressure relief valve 78a leads directly to the pump 92. As shown herein,
this valve 78a is again a pressure relief differential valve.
On the assumption (which is not shown) that the reservoir 94 is connected
in series between the motors 44a and the main pump 92, and that the fluid
in the reservoir 94 is maintained at substantial ambient pressure this
valve 78a could be a pressure relief valve that opens simply at a
predetermined hydraulic pressure upstream of the valve 78.
It is believed that the operation of this second embodiment is evident from
the description of the operation if the first embodiment, so it will be
described briefly herein. The ground engaging wheel 96 rotates at a speed
corresponding to the ground speed of the vehicle 10, causing the pump 92
to operate. The speed of this pump 92, relative to the speed of the ground
wheel 96, and of the motors 44a are selected so that with the by-pass
valve 78a being closed, the pump 44 will drive the belts 38a at a linear
speed greater than the speed of travel of the machine 10a over the ground
surfaces. However, as the fluid pressure upstream of the motors 44a
increases, this valve 78a opens to an extent just sufficient to drop the
pressure in the line upstream of the motors 44a so that there is just
enough power delivered to cause linear travel of the belts 40a, but not so
much power to enable the belts 40a to scruff against the stems of the
plants.
It is understood that various modification could be made to the present
invention without departing from the basic teachings thereof.
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