Note: Descriptions are shown in the official language in which they were submitted.
CA 02238247 1998-OS-22
TITLE OF THE INVENTION
SEGMENTED METER ROLLER WITH SYMMETRICAL COMPONENTS
FIELD OF THE INVENTION
This application relates to segmented meter roller assemblies and to
molded segmented metering sections for use in such assemblies.
BACKGROUND OF THE INVENTION
In modern large scale agricultural operations, seed and/or fertilizer are
typically applied to the soil through a series of seed tubes which are
associated
with soil working tools across the width of a soil working machine. Typically
a
group of such tubes is fed seed or fertilizer by a distribution header. The
distribution header is in turn fed from a tank which may be configured as a
separate
cart for towing in advance of or trailing the soil working implement.
A metering system is associated with the tank for distribution of
product from the tank to the distribution headers of the seed tubes.
The present invention is concerned with a metering system comprising
a segmented meter roller situated below the tank in a meter box assembly
secured
to the tank. Typically the meter box will have a series of outlets known as
runs,
each of which leads through intermediate tubing to one of the distribution
headers.
The total number of possible runs typically extends the length of the
segmented
CA 02238247 1998-OS-22
-2-
meter roller. Depending on the number of distribution headers on the soil
working
implement, the segmented roller assembly will consist of fluted metering
sections
corresponding to runs which are operational and preferably a single blank
roller
spacer extending across the width of the runs which are not operational.
Product
is then delivered to distribution headers which are connected to the runs
containing
the fluted metering sections and no product is delivered from those runs which
are,
in effect, blanked off. Along with the metering sections and blank sections,
the
segmented meter roller assembly may comprise various spacers, bearings, etc.
Various problems have arisen in the use of meter rollers. Typical such
problems involve corrosion caused by leakage of product through gaps between
segments; pulsing delivery of product to the headers; difficulties in
delivering a large
seed or large particle product to the headers at the proper rate; and
difficulties in
delivering very fine products to the headers at the desirable rate.
Against this background the present invention addresses problems in
each of the enumerated areas and others.
PRIOR ART
Various approaches have been used in the past to attempt to provide
segmented meter rollers.
One such prior method varies the amount of product delivered by each
fluted metering roller by fixing a varying number of thin rings about the
center line
CA 02238247 1998-OS-22
-3-
of the roller to simply reduce the volume of product to be delivered by the
roller.
This was intended to compensate for the differing numbers of seed or
fertilizer
delivery tubes emanating from the distribution header fed by that particular
metering roller.
Another method used to reduce flow from a given run comprises
reducing the width of the fluted metering section and inserting separate
spacers on
each side of the metering section. This method results in a very large number
of
parts in the segmented meter roll assembly with consequent severe tolerance
and
torque problems.
SUMMARY OF THE INVENTION
It has now been discovered that all of the problem areas to which
reference was made in the background discussion above can be alleviated to a
significant extent by the use of molded segmented metering sections which are
formed as a single unit per run which may have any desired combination of
blank
and fluted surfaces.
Thus, the invention provides a segmented meter roller assembly for
metered product delivery between a meter box and a series of product runs
leading
to a series of product distributors or distribution headers, the assembly
comprising:
a shaft for mounting for rotation in the box; and a series of roller sections
mounted
on the shaft, the roller sections chosen from the group consisting of blank
sections
CA 02238247 1998-OS-22
-4-
or molded segmented metering sections; and wherein the series of roller
sections
includes at least one of the molded segmented metering sections, each of the
molded segmented metering sections secured to the shaft for rotation therewith
and comprising at least one fluted segment and at least one blank segment.
In a further embodiment the invention provides a molded metering
section for use in a segmented meter roller assembly, the segmented metering
section comprising at least one fluted segment and at least one blank segment.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate embodiments of the invention:
FIGURE 1 illustrates an air cart of which the present invention may
form a component;
FIGURE 2 is a cross-section through a part of the cart of Figure 1
illustrating the general layout in the meter box;
FIGURE 3 is an exploded view of segmented metering sections and a
meter roller assembly according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figures 1 and 2 illustrate the context of the present invention. Air cart
40 is of known configuration and comprises tank 42, or optionally a number of
CA 02238247 1998-OS-22
-5-
tanks (not illustrated), which may be mounted on frame 44, which is in turn
carried
on wheels 46. A metering assembly 48 is mounted on the bottom 50 of tank 42.
A blower 52 forces air past the outlet area 54 of metering assembly 48 to
carry
product 55 from metering assembly 48 to appropriate tubing to distribution
headers
on a soil working implement (headers and implement not shown). A series of
dividers 56 at the meter assembly outlet 54 define a series of runs which
direct
product into a corresponding series of delivery tubes 58.
In addition to dividers 56, meter assembly 48 includes meter box 60
within which are disposed agitators 62 and meter roller assembly 64.
All of the foregoing is known in the prior art.
With reference to the segmented meter roller assembly illustrated in
Figure 3, a shaft 1 1, preferably of hexagonal configuration, is journalled
for rotation
in the metering box 60 of an air cart 40. A sprocket 1 is secured at one end
of
shaft 11 to indicate shaft rotation speed. The shaft is preferably driven by a
hydraulic motor, and certain implications of this drive mode will be discussed
later.
The segmented roller assembly shown in the drawings is intended for
an air cart 40 having several runs, 2 of which include a segmented metering
section
12. As will be understood by those skilled in the art, such assemblies may
include
additional runs, typically, for example, 8 runs. Any of those runs may contain
a
metering section or a blank section, depending on the number of distribution
headers which are provided on the soil working implement in association with
which the air cart is used.
CA 02238247 1998-OS-22
-6-
A central blank section having an outer spacer 19 is illustrated to blank
out unused runs. It is highly preferred that all unused runs be grouped
centrally, so
that a single blank section can be used across all unused runs.
The central blanked section comprises an outer spacer 19 and an inner
spacer 20, the latter fixed by pin 7 to shaft 1 1 for centrally locating the
spacer 20
on shaft 1 1.
The bearing seats 14 abut against inner spacer 20 and include a
hexagonal bore, so that they rotate with spacer 11. Bearing seats 14 abut a
machined shoulder within outer spacer 19. When bearings 5 are seated on seats
14, the outer races of the bearings are in frictional engagement with outer
spacer
19, thus allowing inner spacer 20 to rotate, while outer spacer 19 is held
against
rotation. Outer spacer 19 is held against rotation by virtue of the cap screw
18
abutting against a part of the top of meter box 60.
The bearing shield 13 is then forced against the surface of bearing seat
14 sealingly engaging the O-ring 6 between the two. Bearing shield 13 is also
in
sealing engagement with the end of the central spacer assembly.
It should be noted that the central spacer assembly illustrated in Figure
3 may be a special purpose arrangement which may serve functions unrelated to
the metering per se as, for example, in pressure equalization.
The two metering roller sections 12 abut against the bearing shields
13.
CA 02238247 1998-OS-22
_7_
Outer bearing seats 4 carry similar bearings 5 separated from the outer
ends of metering rollers 12 by a second set of bearing shields 13. The outer
bearing seats 4 are pinned by associated pins 7 to maintain the position of
the
segments between them. The outer bearings 5 journal shaft 1 1. It is important
to
note that there would be no more bearings in the case of say, a 6 run
assembly.
In that case the intermediate sections or blank section would simply abut one
another. In the absence of a central spacer assembly where all runs are in
use, the
shaft would carry only the two outer end bearings.
In this respect it is important to note that it is highly preferable that
all of the sections be somewhat compressed together for sealing purposes. It
is
outer seats 4 and their associated pins which maintain the compression across
the
roller assembly. The covers 3 are applied at the end of the metering section
of the
roll. A hub 2 is preferably fixed on the end of shaft 1 1 and incorporates a
speed
sensor.
At the other end of the assembly there is preferably positioned an
identification disk 23 to identify the metering roller type as, for example,
between
extra fine, fine, and coarse. A cam arrangement 24 and 25 is fixed to the end
of
shaft 1 1 by pin 26 and forms the driver for agitator 62 (Figure 2) to ensure
smooth
flow from the product tank into the meter box.
The segmented metering sections 12 comprise a fluted segment 30
and two smooth blank segments 32. The combined width of the fluted section and
the two blank sections is essentially the same as the width of a single run.
CA 02238247 1998-OS-22
_g_
While the positioning and the proportions of the segments may vary
as desired, it is preferable that the metering sections comprise, as
illustrated, a
central fluted segment and two blank segments which are symmetric about the
mid
point of the roller.
Clearly, a run may have a preselected width, as in the case of existing
machines, and the overall width of the metering section and of the fluted and
blank
segments of that roller can be varied to adapt an existing machine to the
invention.
The arrangement described offers significant advantages over prior art
such assemblies.
In a conventional assembly, wherein the metering roller is fluted across
its entire width; that is, across the width of the run, the shaft will often
be required
to be operated at relatively low rpm, as, for example, typically down to about
2 rpm, in order to deliver correct amounts of product. At this lower rpm,
there is
a significant time during each rotation when no product is moved from the
metering
box into a run. This is because there is no flow when the end of a flute
passes the
run inlet. There is an interruption of flow as every flute passes. This has
been
found to result in a pulsing effect in the delivery of product to the
distribution
header and, consequently, in the uneven application of seed or fertilizer. By
increasing the speed of rotation, the blank time during which a given flute is
passing is reduced and the result is that a much more even flow of product to
the
distribution headers and hence into the soil can be achieved.
Clearly the increase in rpms means that a larger quantity of product
CA 02238247 1998-OS-22
-9-
would be delivered to the distribution header by any given metering roller.
The
present arrangement avoids that problem by decreasing the capacity of the
fluted
section of the metering roller. Thus, the shaft can be operated at higher rpm
while
delivering the same amount of product to the distribution header as would have
been delivered under an older full width fluted metering section.
The arrangement offers the additional advantage that product can be
readily handled which could not have been handled at low rpm. For example, for
large size low volume seed, such as corn, the metering roller in the prior art
could
not be operated at a sufficiently low rpm to efficiently deliver proper
amounts of
product. At the higher rpm these types of product can readily be handled.
A further very significant advantage of the arrangement is that the
hydraulic motors which are the preferable drive means for the assembly are
very
inefficient at low rpm. An increase of rpms from 2 to 4 or 6 rpm is highly
significant in this regard. At those higher rpms, the variable rate hydraulic
drive will
operate very efficiently. Furthermore, the equipment cost for the variable
hydraulic
motor to operate only at the higher rpms is significantly decreased.
Apart from the above operational advantages, there are significant
improvements in cost and life expectancy of the present assembly over prior
art
assemblies. Since it is highly preferable that the present metering section be
molded as a single urethane piece, there is a clear cost saving over prior art
such
assemblies where multiple components were used. As well, because there are
significantly fewer components on the shaft, there is much less of a tolerance
CA 02238247 1998-OS-22
-10-
problem as between any two components. For example, in some prior art such
assemblies, because there are a large number of components, the components
must
be manufactured somewhat shorter than ideal tolerance, in order to ensure that
all
components will be able to be fitted on the shaft. The result is a somewhat
sloppy
and loose arrangement. This results in product working down through the gaps
between components and resulting in corrosion problems.
In the present case the components are substantially all urethane and
are assembled on the shaft under overall compression, so that there are no
gaps or
much less chance of gaps developing. Hence corrosion problems are minimized.
In certain prior art such assemblies, where spacers are employed for
various reasons, it is common to simply use a plastic spacer with a circular
bore
which will fit over the shaft in a loose arrangement, such that the spacer
does not
rotate with the shaft. This frequently results in the bore in the spacer
becoming
eccentric and this can contribute to the opening of gaps in the assembly, thus
leading to the corrosion problem noted above. In the present case some of the
spacers are integral with the metering rollers and others are blanks with
hexagonal
bores which are fitted on the shaft for rotation with the shaft. In the
present case
for other purposes a central spacer may be provided, as described above, the
outer
shell of which is held against rotation but the inner shell of which rotates
with the
shaft, the two shells being separated by bearings.
Further, the use of multiple components which are in contact with, but
not rotating with, the shafts results in severe torque problems.
CA 02238247 1998-OS-22
-11-
In a typical air cart, there might be eight runs emanating from the
meter box and thus up to eight metering sections. Typically a run is about 3
inches
wide, so that the assembly would then be about 24 inches long. Typically a
variety
of metering sections are interchangeable on the shaft, the flutes of which are
of
varying degrees of fineness.
In the preferred case the tank is pressurized to essentially equalize
pressure on both sides of the metering assembly. The pressurization may be at
about 40 inches of water or 1 '/Z psi.
The product is pneumatically driven through the runs and ultimately
to the soil, and such air seeders are well known in the art.
The metering roller section in the present case may have fluted
sections up to about 1 inch of the 3 inch overall width.
