U.S. patent application number 09/792369 was filed with the patent office on 2002-04-18 for method and apparatus for controlling the attitude of an implement.
Invention is credited to Angelo, Gregorio, Luca, Nicolini, Sereni, Eugenio.
Application Number | 20020043374 09/792369 |
Document ID | / |
Family ID | 11438240 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020043374 |
Kind Code |
A1 |
Luca, Nicolini ; et
al. |
April 18, 2002 |
METHOD AND APPARATUS FOR CONTROLLING THE ATTITUDE OF AN
IMPLEMENT
Abstract
Method and apparatus for controlling the attitude of an
agricultural implement drawn by an agricultural tractor, the device
including a lift; two deflection sensors located at the attachment
points of the bottom arms of the lift to the frame of the
agricultural tractor; and an electronic central control unit for
processing data received from the sensors and controlling lifting
and lowering of the implement by the lift as a function of the data
detected by the two sensors; the device being characterised in that
each of the sensors has locking means for adjusting the position of
each of the sensors with respect to the frame so that each of the
sensors assumes a predetermined tilt with respect to the
ground.
Inventors: |
Luca, Nicolini; (Modena,
IT) ; Angelo, Gregorio; (Cittanova, IT) ;
Sereni, Eugenio; (Albareto, IT) |
Correspondence
Address: |
LARRY W. MILLER
NEW HOLLAND NORTH AMERICA , INC.
P.O. BOX 1895
NEW HOLLAND
PA
17557
US
|
Family ID: |
11438240 |
Appl. No.: |
09/792369 |
Filed: |
February 23, 2001 |
Current U.S.
Class: |
172/4 ; 172/439;
56/10.2E |
Current CPC
Class: |
G01L 5/136 20130101;
A01B 63/112 20130101 |
Class at
Publication: |
172/4 ;
56/10.20E; 172/439 |
International
Class: |
A01D 075/28; A01B
063/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 29, 2000 |
IT |
B02000A000101 |
Claims
Having thus described the invention, what is claimed is:
1. Apparatus for controlling the attitude of a ground-engaging
agricultural implement drawn along the ground by an agricultural
tractor, the tractor having a frame, an engine and an operator's
platform, said apparatus comprising: a lift for attachment to said
implement, said lift including two spaced apart and generally
parallel bottom arms pivotably attached to said tractor frame; a
deflection sensor located at the attachment points to said frame of
each said bottom arm of said lift, each said sensor having a
neutral axis; an electronic central control unit for processing
signals received from said sensors and controlling lifting and
lowering of said implement by said lift as a function of the
signals detected by said sensors; and separate locking means
holding each said sensor for adjusting the position of each said
sensor with respect to said frame so that said neutral axis of said
sensors assumes a predetermined angle with respect to an axis
substantially perpendicular to the ground.
2. The apparatus of claim 1, wherein said angle ranges between
0.degree. and 40.degree..
3. The apparatus of claim 2, wherein each said locking means
includes a semi-circular groove coaxial with respect to said
neutral axis and fitted 130.degree. around each said sensor and at
least one bolt fitted in said groove to lock said sensor in
position.
4. The apparatus of claim 3, wherein said locking means are
remote-controllable.
5. The apparatus of claim 4, wherein said sensor detects a first
vector component, said first vector component being the vector
component of the lifting force of said lift that is perpendicular
to said neutral axis.
6. The apparatus of claim 5, wherein each said sensor detects the
vector sum of said first vector component and a second vector
component, said second vector component being the component of the
pulling force of said implement that is perpendicular to said
neutral axis.
7. The apparatus of claim 6, wherein said electronic central
control unit, depending on the value detected instant by instant of
said vector sum, activates or not said lift to lift or lower said
agricultural implement with respect to the ground.
8. The apparatus of claim 7, wherein said angle of each said sensor
with respect to the ground is determined as a function of the
implement and the type of ground to be worked.
9. A method of controlling the attitude of an agricultural
implement drawn by an agricultural tractor; the method comprising
the steps of: (a) determining a vector sum (R) of a component (H1)
of a lifting force (H) of a lift and a component (F1) of the
pulling force (F) of said implement; said components (H1, F1) being
considered along an axis (C) perpendicular to the neutral axis of a
deflection sensor; (b) lifting said agricultural implement upon
said vector sum (R) exceeding a predetermined threshold value; (c)
arresting the lifting of said agricultural implement upon said
vector sum (R) falling within a predetermined acceptance range; and
(d) lowering the agricultural implement back to the ground.
10. The method of claim 9, wherein all the operations are
controlled by an electronic central control unit.
11. In an apparatus for controlling the attitude of a
ground-engaging agricultural implement drawn along the ground by an
agricultural tractor, said tractor having a frame, said apparatus
including a lift mechanism for attachment to said implement, said
lift including two spaced apart and generally parallel bottom arms
each attached at a pivot point to said tractor frame for pivotal
movement in a vertical plane generally perpendicular to the ground;
a deflection sensor located at the pivot points to said frame of
each said bottom arm of said lift, each said sensor having a
neutral axis; an electronic central control unit for processing
signals received from said sensors and controlling lifting and
lowering of said implement by said lift as a function of the
signals detected by said sensors, the improvement comprising:
separate locking means holding each said sensor for adjusting the
position of each said sensor with respect to said frame so that the
angle between said neutral axis of said sensors and an axis
substantially perpendicular to the ground may be changed to change
the signals received by said electronic central control unit from
said sensors.
12. The improvement of claim 11, wherein said angle may vary
between 0.degree. and 4.degree..
13. The apparatus of claim 12, wherein said sensor detects a first
vector component, said first vector component being the vector
component of the lifting force of said lift that is perpendicular
to said neutral axis.
14. The apparatus of claim 13, wherein each said sensor detects the
vector sum of said first vector component and a second vector
component, said second vector component being the component of the
pulling force of said implement that is perpendicular to said
neutral axis.
15. The apparatus of claim 14, wherein said electronic central
control unit, depending on the value detected instant by instant of
said vector sum, activates or not said lift to lift or lower said
agricultural implement with respect to the ground.
16. The apparatus of claim 15, wherein said angle of each said
sensor with respect to the ground is determined as a function of
the implement and the type of ground to be worked.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a method and
apparatus for controlling the attitude of an implement drawn by an
agricultural tractor, and more specifically to improved method and
apparatus for such purpose that do not rely on measurement of the
working resistances of the implement.
BACKGROUND OF THE INVENTION
[0002] Many agricultural tractors are equipped with devices for
automatically controlling the attitude of the implement by
detecting the force exerted on the lift attachment arms, so as to
optimise tractor performance by lifting the implement as a function
of its working resistance. In particular, devices applied to a
hydraulic lift are known in which ground action on the implement is
determined by two sensors fitted to two pins about which the bottom
lift arms pivot with respect to the tractor frame; and the
implement is lifted by two top arms pivoting with respect to the
frame, powered by a hydraulic system, and also connected
mechanically to the bottom arms. In other words, the two top arms
and respective bottom arms and connecting rods together define the
lift. The sensors on the bottom arm pins provide for measuring
deflection of the pins under the load exerted by the implement.
Such a device is described, for example, in European patent
application no. 95203063.3 (in the name of New Holland Italia
S.p.A.) in which the agricultural tractor described employs two
Hall-effect deflection sensors located at the attachment points of
the lift arms to the frame.
[0003] The neutral plane of the sensors remains substantially
perpendicular at all times to the ground being worked, so that the
apparatus shown in the European application identified above, and
similar apparatus, do not allow for the deflection sensor being
rotated a given angle with respect to the ground. For this reason,
since the deflection sensor detects stress substantially
perpendicular to the neutral plane, the arrangement shown in the
above-identified European application only provides for measuring
the pulling force of the implement, which results in poor
measurement and control when the pulling force is affected by the
configuration as opposed to the working depth of the implement.
[0004] With an implement such as a ripper, in which the pulling
force is mainly exerted by the ends, and which provides for
producing drainage holes of more or less constant depth, on
encountering ground areas of different consistency, pull-controlled
lifting is only effective in the presence of considerable undesired
variations in working depth. Lifting also produces an increase in
vertical load due to the geometry of the ends, which results in
increased lift pressure in the hydraulic circuit and in a chain
reaction which may even result in the implement being withdrawn
completely from the ground. At which point, the system commands a
rapid downstroke, thus resulting in jerky operation with the
implement being continually withdrawn and lowered rapidly.
SUMMARY OF THE INVENTION
[0005] Accordingly, it is an object of the present invention to
provide novel and improved method and apparatus for controlling the
attitude of an implement drawn by an agricultural tractor, and
which enables the operator to selectively adjust the tilt of the
deflection sensors with respect to the ground plane. More
particularly, these novel method and apparatus provide for tilting
the neutral plane of the sensor with respect to the substantially
horizontal ground plane for different working conditions of the
implement and different ground consistencies and properties.
[0006] Another object of the invention is to provide method and
apparatus wherein the deflection sensor detects not only the
pulling force of the implement but also a sustaining and lifting
force component indicating, instant by instant, the way in which
the pulling force is actually affected by the lifting force. The
lifting force produces a component on the read axis of the sensor
but oppositely oriented with respect to the pulling force
projection, so that the electronic central control unit receives a
lower reading which slows down, and eventually arrests, the lift
operation in proportion to the ground penetration force of the
implement. The lift operation can therefore be arrested long before
the implement is withdrawn completely from the ground, thus
eliminating any jerkiness and enabling smooth operation more in
keeping with conditions external to the automatic implement lift
system.
[0007] These and other objects, features and advantages are
accomplished according to the instant invention by providing method
and apparatus for controlling the attitude of an implement drawn by
an agricultural tractor, the device comprising a lift; two
deflection sensors located at the attachment points of the bottom
arms of the lift to the frame of the agricultural tractor; and an
electronic central control unit for processing data received from
the sensors and controlling lifting and lowering of the implement
by the lift as a function of the data detected by the two sensors.
The device is further characterised in that each of the sensors
comprises locking means for adjusting the position of the sensor
with respect to the frame so that the sensor assumes a
predetermined tilt with respect to the ground.
DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of the rear of an agricultural
tractor equipped with a device in accordance with the instant
invention;
[0009] FIG. 2 is a side elevational view of the of the sensor
arrangement of the instant invention;
[0010] FIG. 3 is a cross-sectional view, taken along lines III-III
of FIG. 2.;
[0011] FIG. 4 is a dynamic diagram relative to a deflection sensor
in the prior-art position with respect to the frame; and
[0012] FIG. 5 is a dynamic diagram relative to a sensor
positionable with respect to the frame according to the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] Referring now to FIG. 1, reference number 10 indicates the
rear of an agricultural tractor comprising a frame 11 for
supporting a seat 12 and a rear axle 13 fitted in known manner with
two rear wheels 10a (only one shown). Frame 11 is fitted
mechanically with a device 14 for controlling the attitude of an
agricultural implement A (not shown in FIG. 1), and which is the
main object of the present invention.
[0014] Device 14 comprises two bottom arms 15, by which respective
members 16 (only one shown in FIG. 1) projecting from frame 11 (see
also FIGS. 2 and 3) are connected mechanically to the agricultural
implement A drawn by agricultural tractor 10. Device 14 also
comprises two top arms 17 corresponding with and connected to
bottom arms 15 by respective articulated rods 18, i.e., as shown in
FIG. 1, each bottom arm 15 is connected mechanically to the
corresponding top arm 17 by a corresponding rod 18 pivoting with
respect to arms 15 and 17.
[0015] One end of each top arm 17 is integral with a shaft 19,
which is rotated in known manner (not shown) by an electronic
central control unit 20 for processing a number of signals from two
deflection sensors 21 fitted to members 16 projecting from frame
11.
[0016] Bottom arms 15, top arms 17, rods 18, and shaft 19 together
form part of a lift S powered, for example, by a hydraulic circuit
(not shown) and for lifting and lowering with respect to ground T
any implement A attached by known mechanical means to bottom arms
15. Lifting and lowering of implement A with respect to ground T
may obviously be controlled by electronic central control unit 20,
which may activate a hydraulic system (not shown) to rotate shaft
19 one way or the other.
[0017] As shown in FIG. 3, each sensor 21 is inserted inside two
coaxial through holes 22 and 23, between which cavity 24 houses a
spherical joint 25 interposed between sensor 21 and the
corresponding bottom arm 15.
[0018] When pull F (FIG. 3) is exerted by implement A, sensor 21
deflects by an amount depending on the value of force F. That is,
the greater the pull F exerted by implement A via arm 15, the
greater the deflection of corresponding sensor 21; and the amount
of deflection is convertible into an electrical signal transmitted
over a cable 26 to central control unit 20 which, as stated,
controls lift S.
[0019] Consequently, when an anomalous increase in force F occurs
during the working of ground T by implement A, central control unit
20 raises implement A from ground T in known manner, and, once the
cause of the anomalous increase in F is removed, lowers implement A
back down to ground T.
[0020] As shown in FIGS. 2, 4, and 5, the cross section of sensor
21 comprises three straight sides 21a-21c perpendicular to one
another, and a curved side 21d connecting straight sides 21a and
21c. The cross section of sensor 21 is so shaped to enable sensor
21 to be positioned correctly with respect to a locating plate 27
(FIGS. 2 and 3) which may be fixed by two bolts 28, 29 to member 16
integral with frame 11. More specifically, curved face 21d of
sensor 21 must be positioned facing implement A, so that, in the
prior-art embodiment shown in FIG. 4, the neutral axis N of sensor
21 is substantially perpendicular to the surface of ground T.
[0021] It should be pointed out that neutral axis N is the line
left in the drawing plane by the neutral plane N of the deflected
beam defined by sensor 21 (see also FIG. 3). If the neutral plane N
is not positioned correctly, the F values detected by sensor 21 are
unreliable and result in malfunctioning of the system as a
whole.
[0022] To position sensor 21 correctly with respect to locating
plate 27, a foolproof seat 30 need simply be formed in known manner
in the face 27a of plate 27 facing implement A. Seat 30 has three
flat perpendicular faces to house sides 21a-21c of sensor 21, so
that curved face 21d of sensor 21 is positioned correctly facing
implement A.
[0023] FIG. 4 shows a conventional position of sensor 21, in which
neutral axis N is coincident with the axis P perpendicular to
ground T, and, as stated, axis N is perpendicular to the force F
exerted by implement A on one of bottom arms 15. H indicates the
force produced by rod 18 to lift implement A off the ground upon
force F exceeding a predetermined threshold. As can be seen, in
this case, force H is not detected by sensor 21 by lying along
neutral axis N and therefore being unable to exert either tensile
or compressive stress on the fibers of sensor 21 on either side of
neutral plane N.
[0024] On the other hand, if, as shown in FIG. 5, sensor 21 is
tilted a given angle cc as explained in detail below, sensor 21 is
able to detect not only component F1 of F along an axis C
perpendicular to neutral axis N, but also component H1 of force H
along the same axis C. F1 will obviously be equal in absolute value
to (F cos .alpha.), and H1 equal in absolute value to (H sin
.alpha.).
[0025] From a different point of view, angle .alpha. may be
considered the angle formed by neutral axis N and axis P
perpendicular to ground T. Obviously, in the prior-art situation
shown in FIG. 4, angle .alpha.=0.degree..
[0026] In the FIG. 5 case, central control unit 20 is able to
determine force F1 perpendicular to neutral axis N, which is
actually less than F. By means of appropriate processing by central
control unit 20, however, it is possible to correct this false
reading to work out the real value of F from the detected F1
value.
[0027] Only being able to read a force lying along axis C, sensor
21 determines the value R of the vector sum of F1 and H1. In other
words, sensor 21 can also "see" the force H, in the form of H1,
produced by arms 17 via rods 18, and can therefore read the
instantaneous value of R=(F1-H1).
[0028] Consequently, when rod 18 lifts bottom arm 15, and hence H
is other than zero, not only is the resultant force R reduced on
account of the increase in H1, but there is also a simultaneous
reduction in force F1 by implement A being raised by arms 15. Arms
15 stop lifting as soon as value R falls within a predetermined
acceptance range. If force R increases again, central control unit
20 commands rods 18 to produce new forces H to lift implement A,
and so on.
[0029] Off-ground lifting of implement A is thus broken up into
several parts to prevent implement A from being withdrawn
completely from ground T to no purpose. In other words, in the
presence of an exceptional force F1, and hence F, lift S begins
lifting bottom arms 15 by just enough to restore the values of R to
a predetermined acceptance range, so that in many cases implement A
is allowed to continue working ground T as opposed to being
withdrawn completely by lift S.
[0030] By correctly co-ordinating forces H and F, the present
invention therefore provides for preventing jerky operation caused
by implement A being withdrawn completely from ground T, being
plunged straight back into ground T upon central control unit 20
determining a zero force F, and then being withdrawn completely
once more upon force F again exceeding the threshold value. For
example, when working fairly soft ground T beneath a very hard
layer, as in the case of grassland, using sensor 21 tilted at a
given angle a (FIG. 5), central control unit 20 stops implement A
from being lifted once R falls once more within an acceptable
range. Using a conventionally positioned sensor 21 (FIG. 4), on the
other hand, once the hard outer layer is detected, implement A is
withdrawn completely, thus giving rise to undesired jerking. As
stated, positioning sensor 21 with respect to frame 11 according to
the present invention prevents implement A from being withdrawn
completely to no purpose, thus keeping the implement longer in the
work position.
[0031] Tilt .alpha. depends on the desired sensitivity of the
system. More specifically, the further sensor 21 is tilted, i.e.
the greater angle .alpha., the greater the value of H1 and hence
system sensitivity with respect to H.
[0032] Tilt .alpha. is also user selected on the basis of mean
penetration of implement A, the type of ground, and desired system
sensitivity. The system may therefore be sold, for example,
together with maker's tables indicating recommended tilt angles
.alpha. for different ground consistencies and implements; and the
system may be in-field calibrated by the user on a trial and error
basis using values in the region of the a angles recommended by the
maker.
[0033] If implement A is a ripper, for example, ground penetration
is deep, so that lift action is preferably broken up considerably,
and a tilt angle .alpha. ranging between 20.degree. and 25.degree.
preferably selected to obtain substantial H1 components and
increase lift action break-up.
[0034] Conversely, in the case of soft ground and an implement A in
the form of a disk harrow or cultivator, tilt angles .alpha. of
close to zero and nearing the FIG. 4 (prior-art) position may be
used. In this case, in fact, a high degree of break-up is not
required.
[0035] Tests have shown that angles .alpha. ranging between
0.degree. and 40.degree. cover a wide range of agricultural
implements A and different types of ground.
[0036] Sensor 21 can be tilted using the system shown in FIG. 2. A
substantially C-shaped groove 31 is formed in the outer face 16a
(FIG. 3) of member 16, so that by means of bolts 28 and 29, plate
27 can be fitted in a position other than that shown by the
continuous line in FIG. 2. For example, plate 27 can be fitted in a
first position defined by a tilt angle .alpha.1 of 15.degree., or
in a second position defined by a tilt angle .alpha.2 of
25.degree.; .alpha.1 and .alpha.2 both being within an angle .beta.
of 40.degree. for the reason explained above. In the FIG. 2
embodiment, groove 31 is therefore in the form of a 130.degree.
sector (90.degree.+40.degree.).
[0037] To adjust the system to the conditions of a new implement A
or different ground T, or both, the user simply unscrews bolts 28
and 29 from groove 31, rotates plate 27, e.g. clockwise, to set the
approximate tilt angle .alpha. recommended, for example, in a table
supplied by the maker of agricultural tractor 10, and then fixes
plate 27 back on to member 16. The user then proceeds by trial and
error to determine the best tilt angle .alpha. for the implement A
and ground T involved.
[0038] To anyone skilled in the art, the above-described system
with particular reference to FIG. 2 may obviously be replaced with
a similar mechanical system for rotating plate 27 by the desired
angle .alpha. without, however, departing from the scope of the
present invention. For example, in a further embodiment not shown,
plate 27 is rotated by a lever connected to plate 27 itself. Plate
27 may also be rotated by remote-control systems, in particular,
operated by the user from seat 12.
* * * * *