Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to apparatus for remote
adjustment of a control valve for controlling extension or
contraction of a piston rod of a power cylinder by
alternatively allowing or blocking the flow of hydraulic
fluid through said power cylinder. Devices of this type are
used in different fields of technology and in particular in
farming implements for controlling the length of stroke of a
hydraulic or pneumatic cylinder. In most practical
applications, the device serves the purpose of controlling
the depth of soil penetration by an earth working tool of a
farming implement such as the sweep of a cultivator.
Controlling devices of this type are shown in numerous
patents. For instance, U.S. Patent 3,972,265 issued August
3, 1976 to Magnuson describes a stroke control mechanism for
a hydraulic actuator. It has a piston and cylinder device
including a blocking valve which selectively blocks fluid
flow from one side of the actuator. The blocking valve is
usually a poppet valve. It is actuated by a plate which is
mounted to the piston rod of the hydraulic cylinder. As the
contraction of the hydraulic cylinder reaches a predetermined
position, the plate abuts against a valve rod and closes the
blocking valve. The closing results in an interruption of the
flow of fluid through the hydraulic cylinder. A similar
device is shown in U.S. Patent 3,667,374 issued June 6, 1972
to Patrick, U.S. Patent 2,606,414 issued August 12, 1952 to
Dyrr and U.S. Patent 2,606,532 issued August 12, 1952 to
Ziskal.
If it is desired to adjust the length at which the path
of travel of the piston rod of the hydraulic cylinder is to
be terminated, the place at which the tab or plate is mounted
to the piston rod is modified. This procedure is cumbersome
if the device is used in a heavy farming implement such as a
cultivator. The cultivators usually have a master/slave
hydraulic system. The location of the master cylinder is
usually close to the centre of a relatively complex
framework. It is not conveniently accessible. The operator
has to climb over the frame and back several times in order
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to adjust the device and to check it. A farming machinery,
depth control system, using a selectively adjustable length
of chain to trigger the mechanism is shown in the above
Ziskal patent 2,606,532.
In U.S. Patent 2,606,414 to Dyrr the control of depth of
penetration the ground by a farming implement is effected by
connecting a poppet valve associated with a hydraulic
cylinder to a chain. The length of the chain is selectively
adjustable from the seat of the operator of a tractor. This
device has many disadvantages. It is relatively complex. The
use of a chain and cable which is slack at certain points of
operation may cause misalignment and a subsequent
malfunction. The arrangement described also lacks in accuracy
of an adjustment.
It is an object of the present invention to improve the
art of earth working farming implements and in particular of
the control of the hydraulic cylinder used for the purpose
described.
Another object of the invention is to facilitate the
adjustment of the depth from a convenient location and
virtually without having to resort to a trial and error
method.
In general terms, the present invention provides
apparatus for remote adjustment of the actuation of a control
valve for controlling extension or contraction of a piston
rod of a power cylinder by alternatively allowing or blocking
the flow of hydraulic fluid through said power cylinder,
said control valve including a valve housing and a valve
member in said housing, the valve member being displaceable
from an open position, in which the valve allows the flow
through said power cylinder, to a closed position, in which
the valve blocks the flow through said power cylinder, said
valve member being connected to transmission means for
transmitting the movement of the piston rod to the valve
member to selectively bring the latter into a closed or open
state, said transmission means including a stop tab member
and an abutment member, said stop tab member and said
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abutment member being secured one to said housing and the
other to the piston rod such that, on operation of the
cylinder, said stop tab member and said abutment member move
towards or away from each other along a path which includes a
contact point at which the two members abut against each
other and move in common to displace said valve member, one
of said members including an adjustably displaceable
component for adjusting the position of the respective member
to thus adjust the length of said path. According to the
invention, the adjustably displaceable component includes a
first stem slidably received in a first guide, a first end of
said first stem extending from one end of said first guide,
the guide being fixedly secured to on one of said members, a
second end of said first stem being fixedly secured to one
end of a flexible cable slidably disposed in an elongated
flexible sheath, said flexible sheath having a first end
fixedly secured to said first guide, and a second end fixedly
secured to a second stem slidable in a second guide which is
fixedly secured to a remote support, said second stem being
secured to an indicator to allow movement of said indicator
along a predetermined indicator locus. The apparatus further
comprises lock means for fixedly but releasably securing said
second stem relative to said remote support. Thus, the length
of displacement of the free end of the first stem is
proportional to the length of displacement of the indicator
to enable selective adjustment of the length of said path.
The mechanism of flexible sheath combined with a control
cable is well known in many fields of technology. Reference
may be had, for instance, to arrangements described in U.S.
Patent 1,752,817 issued April 1, 1930 to Spohr, or U.S.
Patent 4,611,502 issued September 16, 1986 to Gregory, U.S.
Patent 4,646,206 issued February 24, 1987 to Bower et al.
The invention will now be described by way of preferred
embodiments with reference to the accompanying diagrammatic,
simplified, not-to-scale drawings.
FIGURES 1 - 3 show a diagrammatic representation of
basic operation of a hydraulic cylinder used in a farming
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implement with many parts of an associated hydraulic circuit
omitted for clarity.
FIGURES 4 and 5 an exemplary representation of two
extremes of an adjustment of the device of Figs. 1 - 3.
FIGURES 6 and 7 show diagrammatic perspective views of
one embodiment of the present invention in two different
positions of adjustment.
FIGURES 8, and 9 are partial top plan views showing
elements of the invention used in calibrating a depth
adjustment device of a cultivator.
FIGURE 10 (on the sheet of FIGURE 4) is a simplified
diagrammatic perspective view of the control of a hydraulic
cylinder showing a further feature of the present invention.
FIGURES 11 and 12 present diagrammatic perspective views
of two extreme positions of another embodiment of the present
invention.
Turning firstly to the arrangement shown in Figures 1 -
5, reference numeral 20 shows a housing of a poppet valve
member 21. The housing 20 has an inlet/outlet port 22. The
port 22 is connected to a first branch C of a hydraulic
circuit serving the system shown.
As is well known, the hydraulic system further includes
a second branch D, a manual valve y and a fluid supply branch
S. The hydraulic circuit itself in well known. It does not
have to be shown in greater detail. It will suffice to say
that the supply S serves to maintain the system under
pressure. The valve V is used in directing the pressurized
fluid to one of the two branches C, D, while relieving the
other branch D, C. It allow the flow of pressurized fluid
through the system in one direction or another to extend or
contract the cylinder 23. There are additional known elements
of the hydraulic circuit, for instance a return line to a
sump.
In the embodiment shown, the housing 20 is integral with
a hydraulic cylinder 23. A piston 24 associated with a piston
rod 25 is slidable in the cylinder 23 subdividing the
cylinder 23 into an upper or first chamber 23a adjacent to
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the housing 20 and a lower or second chamber 23b. The
cylinder 23 is provided with the usual pair of upper mounting
brackets 26. A similar pair of mounting brackets 27 is
provided at the free end of the piston rod 25. The piston
rod 25 carries a stop tab 28. The securement position of
stop tab 28 is selectively adjustable along the length of the
piston rod 25. The tab 28 faces the lower end of a lifting
rod 29. The lifting rod 29, which is an exemplary
embodiment of what is generally referred to as "abutment
member," is slidable relative to the power cylinder 23 in
suitable guide means which is not shown in the drawings for
the sake of simplicity.
The arrangement described presents prior art of which
many embodiments exist. Reference may be had, for instance,
to the Magnuson or Patrick patent.
The axes of the mounting brackets 26 and 27 are
designated with reference letters A and B. The particular
predetermined distance between the two points A, B determines
the spacing of the earth working tools such as cultivator
sweeps above the ground in case of transportation (the
maximum extension of Figure 1) or the depth of penetration of
the ground by the earth working tools at an adjusted minimum
extension shown in Figure 3, 4 and 5. The rising of the
implement can be achieved either by extension of the piston
rod 25 as in the embodiment shown, or by its contraction.
Similarly, the ratio at which the earth working tools (not
shown) are lowered or raised is optional. In the present
invention, a ratio of 1:2 is preferred (1" of displacement of
the piston rod changes the depth by 2").
In Figure 1, oil enters, via branch C, the valve port 22
of the control valve. The valve member or poppet 21 is in
open position allowing unrestricted oil flow into the first
chamber 23a of the cylinder 23. The fluid forces the piston
24 and rod 25 down. Oil is exiting the lower or second
chamber 23b via a port 30 and into the branch D and to an oil
sump (not shown). The distance between axes A and B shown in
Fig. 1 is at its maximum. The cultivator to which the device
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is attached is at a fully raised state.
In Figure 2, the oil flow is reversed by manipulating
the valve V (not shown in Fig.2). Here the hydraulic fluid
enters the second chamber 23b causing the movement of piston
24 upwards. Oil is now exiting the cylinder from the valve
port 22 into the branch C (only shown in Fig. 1) and thence
to the not shown sump. This operation gradually decreases
the distance between points A and B. The distance between
the tab 28 and the bottom of the lifting rod 29 is also
decreasing. In reference to an associated cultivator, the
cultivator frame is being lowered.
In Figure 3, the tab 28 had already made contact at a
contact point with the lower end of the lifting rod 29 which
then travelled in unison with the tab 28 and has made contact
with the lower end of the stem of the valve member or poppet
21. The poppet 21 has thus been raised to block the flow of
fluid from the valve port 22, thus blocking the flow of oil
through the power cylinder 23. The distance between axes A
and B is now locked at a predetermined setting
The distance between points A and B of Fig.3, can be
adjusted by adjusting the position of the depth stop tab 28
on the piston rod 25. For example, Figure 4 shows the depth
stop tab 28 positioned low on the rod 25 thus blocking the
constriction of the cylinder at a set minimum, e.g. 21",
resulting in a maximum depth of penetration of the soil.
Figure 5 shows the depth stop tab 28 positioned high on the
rod 25 to block the contraction of the cylinder at a greater
spacing between A and B. This corresponds to a smaller depth
of penetration of the soil. The distance between points A and
B is now about 29 inches.
The adjustment of the position of the stop tab 28 along
the piston rod 25 is cumbersome and in a location which is
difficult to adjust. As a consequence, it takes a long time
before the desired depth of the cultivator sweeps or the like
is reached. The accuracy of the depth is important for
proper operation in modern farming. The convenience of
adjustment is important not only for the sake of ease of
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operation but also as a safety feature.
Description will now be made of how the present
invention allows the adjustment of the length of the stroke
between the extended and contracted position from a remote
point and by very simple and thus reliable means. To this
end, the invention utilizes a flexible sheath/cable
mechanism. The sheath/cable in itself is, of course, known
and is not claimed in itself. Since many parts of the
transmission of the movement of the piston rod to the valve
member are the same as in the known device described,
identical reference numerals have been used throughout the
drawings to designate the corresponding parts.
Reference may now be had to the representations of
Figures 6, 7 and 11. They show a modification of an existing
power cylinder. The modified cylinder is that shown
previously in Figs. 1 - 5. For the sake of clarity and easy
comparison, the same reference numerals have been used for
the usual parts such as the hydraulic cylinder 23, the
housing 20, axes A, B etc.
The lifting rod 29 is provided with two mounting
brackets. A first mounting bracket 31 is fixedly secured,
for instance by welding, to the rod 29 near the upper end
thereof. The second or lower mounting bracket 32 is likewise
fixedly secured, for instance by welding, to the rod 29 at a
lower end thereof. The mounting brackets 31 and 32 move in
unison with the rod 29 in a vertical direction.
The mounting brackets 31 and 32 hold a tube 33. As best
shown in Figure 10, the hold of the tube 33 is resilient. One
end (the lower end) of the tube 33 passes through an
elongated slot 34 in the lower mounting bracket 32 and is
resiliently secured to the upper bracket 31 by way of an end
sleeve 35 which is generally integral with the tube 33 but
allows lateral displacement of the lower end of the tube 33.
Such displacement is indicated in Figure 10. The sleeve 35
forms a part of a known securement mechanism of a flexible
cable disposed in a sheath 36 the arrangement of which will
be described later in detail. The cable is not visible in the
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drawings. It is secured, at its end near the cylinder casing
23, to a first stem 38 which is slidably received in and
protrudes from the lower end of the tube 33. The tube 33 is
also referred to as a "first guide" and the stem 38 as a
"first stem". The first or lower end portion of the stem 38
is provided forms an abutment member 39. The abutment member
39 faces the top surface of the stop tab 28. The second end
of the first stem 38 is not visible. The end 36a (Figs.6 and
7) of the sheath 36 near the power cylinder 23 is also
referred to as ~the first end." The opposite end is
designated with reference number 36b. The second end of the
cable tnot shown) sliding within the sheath 36 is secured to
a second stem 40 slidable within a second guide or tube 41
which, in turn, is fixedly secured in a remote support 42.
The remote support 42 includes an upright column 43 firmly
secured to a transverse frame member 44 of a cultivator at a
position remote from the cylinder 23. Hence the term "remote
support".
The second stem 40 can assume, relative to the tube 41,
an extended position shown in Figure 6 and a contracted
position shown in Figure 7. The free end of the second stem
40 is fixed to a slide 45 which is integral with an invert L-
shaped indicator 47. The top, horizontal portion of the
indicator 47 forms a rectangular pointer tab 47a. It moves on
a straight indicator path or locus along a planar top surface
48 as the slide 45 moves along the slot 46. A lock provided
with a threaded knob 49 which is threaded on a bolt passing
through the slide 45. It prevents the sliding of the slide 45
along a slot 46 when the handle 49 is in a downward position
(Figure 6) and is loose on horizontal position of handle 49.
The planar top surface 48 of the remote support is
provided with adjustable linear calibration scale. In the
embodiment shown, the scale is a magnetic strip displaying
the scale and explanatory remarks. The arrangement of the
preferred embodiment of the magnetic strip is apparent from
Figures 8 and 9 which correspond to the positions of the
slide 45 as shown in Figures 7 and 6, respectively. The
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magnetic strip or tab 50 has a scale 4 inches long. The
indicator has the width of 1/2 inch which, in the embodiment
shown, corresponds to the travel the rod 29 has to make from
a contact point at which the tab 28 first contacts the
abutment member 39, to a full displacement of the poppet 21
within the inner chamber of the housing 20 to a closed
position similar to that of Fig. 3. The purpose of this
particular thickness will be apparent upon review of the
description of the operation of the device which will follow
shortly.
In operation, the lock handle 49 is loosened and brought
to the extreme left of Figure 10 or Figure 9. This results
in a maximum contraction of the first stem 38 so that the
abutment member 39 is at its uppermost position. The farming
implement, for instance, a cultivator (not shown) is then
manually lowered by operating the valve V included in the
line system feeding ports 22 and 30. The lowering of the
frame of the implement is conducted until such time as the
earth working tools, for instance cultivator sweeps, barely
rest on the ground. At such point, the piston rod 25 partly
projects from the cylinder 23, for example the distance shown
in Figure 7. At this point, the slide 47 is moved to the
right to assume the position indicated in Figure 7.
This movement results in that the abutment member 39
abuts against the stop tab 28 but does not otherwise
influence the instant position of the tube 33 or any other
members associated with the mechanism transmission device,
inclusive of the lifting rod 29 which is still spaced from
the stem of the valve member 21, as shown in Figure 1 or in
Figure 2. The space between the uppermost end of the rod 29
and the downwardly facing end of the stem of the poppet 21
plus the distance of poppet 21 to be travelled from the
position of Figure 1 or 2 to the position of Figure 3 equals
1/2" which is the width of the tab 47a.
Let it be assumed that the adjustment of Fig. 8 has been
locked. The valve V (Fig. 1) may be manipulated to flow the
oil from port 22 into the cylinder 23 and out of the cylinder
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23 through port 30 into branch D. This results in raising the
implement, for instance for transportation or at the turns.
If the flow is now reversed, the oil flows from D into port
30 and from port 22 into C, lowering the frame of an
implement. Eventually the tab 28 contacts the lower end of
the rod 29 and the two then move another 1/2 inch over the
clearance described, until the valve member 21 shuts off the
flow of oil through cylinder 23. The earth working tools are
thus one inch below the surface. The one inch distance is
caused by linkage (not shown) used in the exemplary
embodiment of the farming tool. The linkage transmits one
inch of the displacement between the cylinder 23 and its
cylinder rod 23 to two inches of a drop (or lift) at the
frame, in the ratio described.
Accordingly, the set up of Fig. 8 is that of one inch
depth of the penetration of the ground because that is the
distance the hydraulic cylinder will contract beyond the
original calibrating position, when the piston rod 21 and
with it the stop tab 28 are lifted.
If it is desired to calibrate a depth different from
that shown in Figure 9, for instance to three inches, the
indicator is displaced to a position of Figure 10. Here the
depth side of the indicator is aligned with number 3. The
overall displacement from the position of Figure 9 to Figure
10 is one inch. As already mentioned, this is due to the
fact that the linkage of the cultivator with which this
exemplary embodiment is used is such that it converts the
linear displacement at the calibrating device to twice the
length set. In other words, the travel of the piston rod 25
into or out of the cylinder 23 over a given length results in
twice the length of actual displacement of the frame of the
cultivator up or down.
In summary the operation of the device is generally as
shown in Figures 1, 2 and 3 but the effective length of the
diagrammatic representation of the rod 29 can be selectively
adjusted from a conveniently located position. At the same
time, the exactness of the adjustment is also secured.
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Turning briefly to the embodiment of Figure 11, it can
be seen that the tube 33 is normally held at parallel with
the lifting rod 29 but, in case of an unexpected obstacle or
the like being encountered, the stop tab 28 has sufficient
resiliency to become deflected and to cause the sliding of
the abutment member 39 off sideways as is shown in Figure 11.
If for some reason the poppet valve fails to stop the
cylinder from contracting, the plate 28 is made flexible
enough to yield and thus become inclined to one side,
allowing the abutment member 39 to slide over taking with it
the free end of the tube 33 to assume the position indicated
in Figure 11, at which the tension of the spring 51 has been
overcome.
Other embodiments differing from that described above
may exist without departing from the scope of the present
invention. One such arrangement is shown in Figs. 11 and 12.
As in the first embodiment described, the corresponding
members of the modified arrangement of Figures 11 and 12
utilizes the same reference numbers.
It should be firstly mentioned, that the modification is
only at the first guide 33, while the arrangement of the
remote support is identical to Figs. 6 and 7.
In Figs. 11 and 12, the stop tab 28 is fixedly secured
to the free end of the first stem 38. The tube 33 is fixedly
secured to a rod 52 which is fixedly secured with respect to,
and moves in common with, the piston rod 25. Accordingly, the
manipulation of the calibrating end of the mechanism as shown
in Figures 9 and 10 results in displacement of the tab 28 in
the desired direction rather than in the movement of the free
end of the first stem 38 towards or away from the tab 28.
The remaining operation, for instance the sideways
displacement of the first stem 38 in case of emergency
(Figure 10) is enabled by the relative arrangement of a slot
34 in tab 28 and another slot 34a in a guide 53 which is
fixedly secured to the rod 52. The spring 51, of course,
normally holds the tube 33 parallel with the rod 52 as shown
in both Figures 11 and 12.
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It will thus be appreciated that the present invention
provides an extremely simple, yet accurate device for
adjustment of the depth of operation of cultivators or other
earth working farming implements.
As already mentioned, there are many variants which can
be made within the frame work of the present invention. The
second embodiment described is but one of such variants.
Accordingly, we wish to protect by letters patent which may
issue on the present application all such embodiments as
properly fall within the scope of our contribution to the
art.
