U.S. patent application number 16/856318 was filed with the patent office on 2020-11-19 for driver assistance system of a forage harvester.
This patent application is currently assigned to CLAAS Selbstfahrende Erntemaschinen GmbH. The applicant listed for this patent is CLAAS Selbstfahrende Erntemaschinen GmbH. Invention is credited to Markus BRUNE, Frederic FISCHER, Christoph HEITMANN, Jochen HUSTER, Dennis NEITEMEIER, Bjoern STREMLAU.
Application Number | 20200359563 16/856318 |
Document ID | / |
Family ID | 1000004807600 |
Filed Date | 2020-11-19 |
United States Patent
Application |
20200359563 |
Kind Code |
A1 |
HEITMANN; Christoph ; et
al. |
November 19, 2020 |
DRIVER ASSISTANCE SYSTEM OF A FORAGE HARVESTER
Abstract
A driver assistance system of an agricultural work machine
constructed as forage harvester, wherein the agricultural work
machine comprises a header for gathering crop, a chopping device
having a chopping drum and chopping knives for comminuting the
crop, and a monitoring device operable to generate a signal
containing information about the wear status of the respective
chopping knife and/or about the distance of the cutting edge of a
chopping knife from a shear bar. This information is compared with
a reference value, and the agricultural work machine has activation
devices for activating and deactivating a knife grinding process
and means for change of position of the shear bar. The monitoring
device is integrated in the driver assistance system so that the
driver assistance system automatically detects when a knife
grinding process or a change of position of the shear bar must be
activated or deactivated.
Inventors: |
HEITMANN; Christoph;
(Warendorf, DE) ; NEITEMEIER; Dennis; (Lippetal,
DE) ; BRUNE; Markus; (Harsewinkel, DE) ;
HUSTER; Jochen; (Guetersloh, DE) ; STREMLAU;
Bjoern; (Recke, DE) ; FISCHER; Frederic;
(Arnsberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CLAAS Selbstfahrende Erntemaschinen GmbH |
Harsewinkel |
|
DE |
|
|
Assignee: |
CLAAS Selbstfahrende Erntemaschinen
GmbH
Harsewinkel
DE
|
Family ID: |
1000004807600 |
Appl. No.: |
16/856318 |
Filed: |
April 23, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A01F 29/095 20130101;
A01D 43/085 20130101; G01B 7/14 20130101; A01D 41/1271 20130101;
G01B 7/293 20130101; A01F 29/22 20130101 |
International
Class: |
A01D 43/08 20060101
A01D043/08; A01D 41/127 20060101 A01D041/127; A01F 29/09 20060101
A01F029/09; A01F 29/22 20060101 A01F029/22; G01B 7/14 20060101
G01B007/14; G01B 7/293 20060101 G01B007/293 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2019 |
DE |
10 2019 112 968.0 |
May 16, 2019 |
DE |
10 2019 112 973.7 |
Jul 1, 2019 |
DE |
10 2019 112 965.6 |
Claims
1. A driver assistance system of an agricultural work machine
constructed as forage harvester having a header for gathering crop
and a chopping device comprising a chopping drum and chopping
knives associated with the chopping drum for comminuting the crop,
and activation devices for activating and deactivating a knife
grinding process and for changing a position of the shear bar, the
driver assistance system comprising: a monitoring device that is
operable to generate a signal which contains information about a
wear status of a respective one of the chopping knives or about a
distance of a cutting edge of one of the chopping knives from a
shear bar, wherein the driver assistance system is configured to
compare information about the wear status of the chopping knives or
about the distance of the cutting edge from the shear bar with a
reference value in each instance, and wherein the monitoring device
is integrated in the driver assistance system in such a way that
the driver assistance system automatically detects when a knife
grinding process must be activated or deactivated or a change of
position of the shear bar is to be activated or deactivated.
2. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 1, wherein the
driver assistance system is configured to activate or deactivate
the knife grinding process or the change of position of the shear
bar, or generates a notification for an operator of the
agricultural work machine to activate or deactivate the knife
grinding process or the change of position of the shear bar.
3. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 1, wherein the
driver assistance system is configured such that signals generated
by the monitoring device which contain information about the wear
status of the respective chopping knife or about the distance of
the cutting edge of a chopping knife from a shear bar are converted
into an actual cutting sharpness value and an actual distance value
of the shear bar, and the respective actual value is compared with
the stored associated reference value, and when the respective
actual value lies below a sharp knife reference value or above the
reference distance value, the knife grinding process or the change
of position of the shear bar is activated.
4. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 3, wherein the
driver assistance system is configured such that signals which are
generated by the monitoring device and which contain information
about the wear status of the respective chopping knife or about the
distance of the cutting edge of a chopping knife from a shear bar
are converted into an actual cutting sharpness value and an actual
distance value of the shear bar, and the respective actual value is
compared with the stored associated reference value, and when the
actual value reaches or lies above a sharp knife reference value or
when the actual value reaches or lies below the reference distance
value, the knife grinding process or the change of position of the
shear bar is deactivated.
5. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 3, wherein the
driver assistance system is configured such that the sharp knife
reference value and the reference distance values of the shear bar
can be changed depending on the type of crop.
6. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 1, wherein the
monitoring device monitors the cutting sharpness or the wear status
or a magnitude of a cutting gap for each chopping knife.
7. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 1, wherein the
driver assistance system is configured to determine a radius of the
chopping drum from distance signals generated by the monitoring
device.
8. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 1, wherein the
driver assistance system is configured to determine a quantity of
chopping knives positioned on a chopping drum from signals
generated by the monitoring device, and a configuration of the
chopping drum is brought about automatically in the driver
assistance system.
9. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 1, wherein the
driver assistance system is configured such that a product
feed-dependent wear status is inferred from signals generated by
the monitoring device, and steps are derived which bring about a
product feed that reduces wear.
10. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 9, wherein the
derived steps contain a change of one or more parameters of the
header for receiving crop and/or gathering and pre-compacting
rollers arranged downstream of the header.
11. The driver assistance system of an agricultural work machine
constructed as a forage harvester according to claim 1, wherein the
monitoring device comprises a detection arrangement for detecting
the wear status of a respective chopping knife of the chopping
device, wherein the drum is a revolving chopping drum and wherein
there is at least one shear bar which cooperates with the chopping
knives, wherein the detection arrangement comprises at least one
sensor arrangement which has a magnetic exciter arrangement and a
flux conducting device magnetically coupled thereto, wherein the
sensor arrangement provides a pole arrangement which forms at least
one magnetic pole with a pole surface for conducting magnetic flux,
wherein the sensor arrangement is positioned such that at least a
portion of the chopping knives passes the pole arrangement during a
rotation of the chopping drum, the chopping knife passing the pole
arrangement forms an air gap arrangement with at least one air gap
with respect to the pole arrangement, and at least one magnetic
circuit excited by the exciter arrangement is accordingly closed
via the respective chopping knife, wherein the detection
arrangement has a measuring arrangement and an evaluating unit,
wherein the measuring arrangement is configured to detect at least
one measured magnetic value pertaining to the magnetic flux in at
least one magnetic circuit excited by the exciter arrangement, and
the evaluating unit is configured to determine the wear status of
the respective chopping knife from the at least one detected
measured value.
12. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 11, wherein the
voltage induced when the chopping knife arrangement passes the
sensor arrangement forms the measured magnetic value, and the
detection arrangement is configured to determine the induced
voltage and record it as a voltage signal, the evaluating unit is
configured to resolve the voltage signal into its frequency
components by means of frequency analysis in which frequency
components are separated into frequency components of a fundamental
oscillation and into frequency components of a superposed
oscillation which cause signal distortion, wherein the separated
frequency components of the superposed oscillation which cause a
signal distortion are inverse-transformed in a time domain, and a
measurement for the wear status or cutting sharpness of one of the
chopping knives is derived from the inverse-transformed frequency
components of the superposed oscillation.
13. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 11, wherein the
at least one sensor arrangement is positioned at a circumference of
the chopping drum such that every chopping knife of the chopping
drum is detected by means of a sensor arrangement, wherein
right-hand-side and left-hand-side chopping knife arrangements are
associated with the chopping drum, and at least one sensor
arrangement is associated with each of these chopping knife
arrangements.
14. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 11, wherein a
plurality of induction sensors are associated with each sensor
arrangement, and each induction sensor is configured to generate a
voltage signal, wherein each of the generated voltage signals is
analyzed separately, and wherein a plurality of voltage signals, or
all of the voltage signals, of a detected chopping knife are
combined to form one or more voltage signals prior to an
analysis.
15. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 14, wherein the
frequency analysis of the voltage signal is carried out by means of
Fourier analysis to classify the respective voltage signal into
frequency components of a fundamental oscillation and frequency
components of a superposed oscillation which cause signal
distortions, and wherein the frequency components representing the
fundamental oscillation are not taken into account in the
derivation of the wear status or of the cutting sharpness of the
respective chopping knife.
16. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 15, wherein an
amplitude of the respective voltage signal of the frequency
components causing a signal distortion forms a measurement for
assessing the wear status and/or the cutting sharpness of the
respective chopping knife.
17. The driver assistance system of an agricultural work machine
constructed as forage harvester according to claim 16, wherein the
assessment of the cutting sharpness or wear status is effected by
means of evaluation criteria selected from the group consisting of
grinding surface length of the respective chopping knife, roundness
of a chopping knife tip, general knife wear, camber of the chopping
knife and relative distance of the shear bar from the chopping
knife.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 USC 119 of German
Application No. DE 10 2019 112 968.0, filed on May 16, 2019, German
Application No. DE 10 2019 112 973.7, filed on May 16, 2019 and
German Application No. DE 10 2019 112 965.6, filed on Jul. 1, 2019,
the disclosure of which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The invention is directed to a driver assistance system of
an agricultural work machine constructed as forage harvester for
monitoring the wear status of chopping knives.
[0003] A sensor arrangement which detects the revolving knives of a
chopping drum arrangement by means of inductive sensors and derives
a wear status of the chopping knives from the determined magnetic
flux is known from DE 10 2017 103 537. Wear is determined from the
induced voltage.
[0004] In addition, a similar cutting sharpness detection device is
known, inter alia, from EP 1 522 214. In this case, optical sensors
such as camera systems, lasers and near infrared sensors are used
as detection devices.
[0005] Optical sensors have the problem that the cutting edge
analysis is made more difficult by the high revolving speeds of the
chopping knives, which often leads to poor-quality analysis
results. On the other hand, the analysis of an induced voltage is
influenced appreciably less by the high revolving speeds of the
chopping knives to be detected. However, the evaluating process
which is exclusively directed to the induced voltage does not
always lead to a sufficiently accurate estimation of a wear
status.
[0006] Further, a forage harvester outfitted with a driver
assistance system is known from DE 10 2018 106 915.4. The work
elements of the forage harvester are constructed as automatic
adjusting means which are controllable by the driver assistance
system in such a way that the work parameters of the forage
harvester can be optimized without necessitating the involvement of
the operator of the forage harvester in this process. This has the
effect in particular that the operator need no longer personally
monitor the work quality of the forage harvester. The drawback of
this is that the known driver assistance system does not remove the
operator of the agricultural work machine from the process of
grinding the chopping knives.
SUMMARY OF THE INVENTION
[0007] Therefore, it is the object of the invention to avoid the
disadvantages of the prior art described above and in particular to
enable a driver assistance system to monitor the wear status of
chopping knives.
[0008] This object is met according to the invention by an
agricultural work machine constructed as forage harvester that
comprises a monitoring device integrated in the driver assistance
system in such a way that the driver assistance system
automatically detects when a knife grinding process must be
activated or deactivated and/or a change of position of the shear
bar is to be activated or deactivated. In this way, it is ensured
that a knife grinding process and a change of position of the shear
bar is not dependent on monitoring by or judgment of the operator,
which has the effect in particular that the knife grinding process
is limited to the necessary extent.
[0009] In an advantageous configuration of the invention, the
driver assistance system activates or deactivates the knife
grinding process and/or the change of position of the shear bar
automatically or generates a notification for an operator of the
agricultural work machine to activate or deactivate the grinding
process and/or the change of position of the shear bar so that the
operator is completely relieved of monitoring tasks with regard to
the cutting sharpness of the chopping knives. Further, the driver
of the machine is notified about the state of the knives.
[0010] In an advantageous further development of the invention, it
is ensured that the chopping knives are always kept in a sharp
state which, in addition to high chopping quality, results in
optimal fuel consumption in that the signals generated by the
monitoring device which contain information about the wear status
of the respective chopping knife and/or about the distance of the
cutting edge of a chopping knife from a shear bar are converted
into an actual cutting sharpness value and an actual distance value
of the shear bar, and the respective actual value is compared with
the stored associated reference value, and when the respective
actual value lies below the "sharp knife" reference value or above
the reference distance value, the knife grinding process or the
change of position of the shear bar is activated.
[0011] In order to limit the grinding process to the necessary
extent, the signals which are generated by the monitoring device
and which contain information about the wear status of the
respective chopping knife and/or about the distance of the cutting
edge of a chopping knife from a shear bar are converted into an
actual cutting sharpness value and an actual distance value of the
shear bar, and the respective actual value is compared with the
stored associated reference value, and when the actual value
reaches or lies above the "sharp knife" reference value or when the
actual value reaches or lies below the reference distance value,
the knife grinding process or the change of position of the shear
bar is deactivated.
[0012] In order that crop-dependent effects on the wear of the
chopping knives can be better taken into account, the "sharp knife"
reference value and the reference distance values of the shear bar
can be changed depending on the type of crop.
[0013] A high precision is achieved in the monitoring of cutting
sharpness in that the monitoring device monitors the cutting
sharpness and/or the wear status and/or the magnitude of the
cutting gap for each chopping knife.
[0014] In view of the fact that an irregular product flow to the
chopping drum to the chopping drum substantially influences the
wear of the chopping knives, a radius of the chopping drum is
determined from the distance signals generated by the monitoring
device. This has the effect that an irregular wear and, therefore,
an irregular product feed to the chopping drum can be inferred from
the change of radius of the chopping drum. In this connection, it
is also advantageous when a product feed-dependent wear status is
inferred from the signals generated by the monitoring device,
preferably the derived change of the radius of the chopping drum,
and steps are derived which bring about a product feed that reduces
wear. In the simplest case, the wear-reducing product feed can be
brought about in that the derived steps contain a change of one or
more parameters of the header for receiving crop and/or gathering
and pre-compacting rollers arranged downstream of the header.
[0015] It is further ensured that the operator is substantially
relieved from configuring effort in that the quantity of chopping
knives positioned on a chopping drum is determined from the signals
generated by the monitoring device, and the configuration of the
chopping drum is brought about automatically in the driver
assistance system.
[0016] It is ensured in a simple manner that the wear status of
each chopping knife can be determined individually in that the
detection arrangement for detecting a wear status of a chopping
knife arrangement of a chopping device provided for processing a
product flow is constructed as an inductive detection arrangement,
and the voltage induced when a chopping knife arrangement passes
over the sensor arrangement forms the measured magnetic value, and
the detection arrangement determines the induced voltage and
records it as a voltage signal, and an evaluating unit determines
the wear status of the respective chopping knife from the at least
one detected measured value.
[0017] In a further advantageous configuration of the invention,
the detection of the wear status of chopping knives can be improved
through simple measures in that the voltage signal is resolved into
its frequency components in the evaluating unit by means of
frequency analysis, and the frequency components are separated into
frequency components of a fundamental oscillation and into
frequency components of a superposed oscillation which cause signal
distortion, and the separated frequency components of the
superposed oscillation which cause a signal distortion are
inverse-transformed in the time domain, and a measurement for the
wear status and/or the cutting sharpness of a chopping knife is
derived from the inverse-transformed frequency components of the
superposed oscillation.
[0018] A sensor arrangement or the plurality of sensor arrangements
are positioned at the circumference of the chopping drum such that
every chopping knife of the chopping drum is detected by means of a
sensor arrangement, it is ensured that each chopping knife
positioned at the circumference of the chopping drum can be
detected. This effect is also achieved in a further advantageous
configuration in that right-hand-side and left-hand-side chopping
knife arrangements are associated with the chopping drum and at
least one sensor arrangement is associated with each of these
chopping knife arrangements.
[0019] A high-resolution and therefore very precise analysis of the
wear status and knife sharpness is achieved in that a plurality of
induction sensors, preferably five induction sensors, are
associated with each sensor arrangement and each induction sensor
generates a voltage signal, and each of the generated voltage
signals is preferably analyzed separately and, further preferably,
a plurality of voltage signals, or all of the voltage signals, of a
detected chopping knife are combined to form one or more voltage
signals prior to an analysis.
[0020] By means of Fourier analysis, the respective voltage signal
is classified into frequency components of a fundamental
oscillation and frequency components of a superposed oscillation
which cause signal distortions, and the frequency components
representing the fundamental oscillation are not taken into account
in the derivation of the wear status and/or of the cutting
sharpness of the respective chopping knife. In this way, it is
ensured that only those frequency components which change
significantly depending on the wear of the chopping knives and
which are therefore suitable as indicators for qualifying wear or
knife sharpness are taken into account. A particularly advantageous
configuration results in this respect when the amplitude of the
respective voltage signal of the frequency components causing a
signal distortion is taken into account because this amplitude is a
measurement for assessing the wear status and/or cutting sharpness
of the respective chopping knife and can be determined in a simple
manner.
[0021] A particularly efficient monitoring of the wear status or
chopping knife sharpness, particularly with respect to different
types of wear occurring on the chopping knives, is made possible
when the assessment of the cutting sharpness is effected by means
of evaluation criteria, and the evaluation criteria are one or more
of the evaluation criteria comprising "grinding surface length of
the respective chopping knife", "roundness of the chopping knife
tip", "general knife wear" and/or "camber of the chopping knife" or
"relative distance of the shear bar from the chopping knife".
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Further advantageous configurations are the subject of
further subclaims and are described in the following with reference
to an embodiment example shown in the figures. In the drawings:
[0023] FIG. 1 shows a forage harvester with cutting sharpness
detection device according to the invention;
[0024] FIG. 2 shows a detailed view of the forage harvester
according to FIG. 1 with cutting sharpness detection device
according to the invention;
[0025] FIG. 3 shows a detailed view of the inductive sensor
arrangement;
[0026] FIG. 4 shows a schematic view of the frequency analysis
according to the invention;
[0027] FIG. 5 shows a detailed view of the frequency analysis
according to the invention;
[0028] FIG. 6 shows a further detailed view of the frequency
analysis according to the invention;
[0029] FIG. 7 shows a schematic view of a use of the frequency
analysis according to the invention;
[0030] FIG. 8 shows a schematic view of the driver assistance
system according to the invention; and
[0031] FIG. 9 shows a detailed view of the driver assistance system
according to the invention referring to FIG. 8.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0032] FIG. 1 schematically shows an agricultural work machine 1
which is constructed as a forage harvester 2 and which receives a
harvesting header 3 in the front area thereof. Gathering and
pre-compacting rollers 4 which accept the crop flow 5 coming from
the harvesting header 3, compress it and transfer it to a chopping
device 6 in the rear area is associated with the header 3 in the
rear area thereof. In a manner to be described further, the
chopping device 6 comprises a chopping drum 7 which is outfitted
with chopping knives 8 of a chopping knife arrangement 9. In the
feed-in area 10 of the chopping drum 7, the revolving chopping
knives 8 are moved past a shear bar 11 by means of which the crop
flow 5 to be comminuted is conveyed. In the rear area of the
chopping drum 7, the comminuted crop 5 is then transferred either
to an after-comminution device 13 constructed as a so-called
cracker 12 or directly to an after-acceleration device 14. While
the after-comminution device 13 further comminutes the grain
constituents of the crop flow 5, e.g., corn kernels, the
after-acceleration device 14 accelerates the crop flow 5 such that
this crop flow 5 can be moved through a deflector 15 and exit from
the forage harvester 2 at the end in the area of a deflector flap
16 and can be transferred to a transport vehicle, not shown.
Further, a knife grinding device 17 which is known per se and
therefore need not be described in detail is associated with the
chopping drum 7 at the circumference. The grinding stone 18 of the
knife grinding device 17 is movable horizontally over the width of
the chopping drum 7 such that every chopping knife 8 positioned at
the circumference of the chopping drum 7 can be ground. An
activation device 19 which will be described more fully is
associated with the knife grinding device 17 for purposes of
activating or deactivating the knife grinding process.
[0033] According to FIG. 2, the chopping knife arrangement 9
comprises right-hand-side and left-hand-side chopping knife
arrangements 9a, 9b. Each chopping knife arrangement 9a, 9b
comprises a plurality of chopping knives 8 positioned oblique to
the rotational axis 20 of the chopping drum 7 at the circumference
of the chopping drum 7. The chopping drum 7 is sheathed on the
underside by a drum base 21 preferably comprising stainless steel.
At the upper side, the chopping drum 7 is enclosed by a rear drum
wall 22 which likewise preferably comprises stainless steel. The
sensor arrangement 23 according to the invention which will be
described in more detail later can be positioned either at the rear
drum wall 22 according to the embodiment example shown in FIG. 2 or
at the drum base 21. It is also conceivable that a sensor
arrangement 23 is arranged both at the drum base 21 and the rear
drum wall 22 at the same time. Regardless of the specific position,
at least two sensor arrangements 23a, 23b are associated with every
chopping drum 7 in such a way that one of the sensor arrangements
23a, 23b is associated in each instance with the associated
chopping knife arrangement 9a, 9b, respectively. Each sensor
arrangement 23a, 23b completely covers the cutting edge 24 of the
respective chopping knife 7 so that each cutting edge 24 can be
detected over its entire length by the respective sensor
arrangement 23a, 23b. Further, it lies within the scope of the
invention that the respective sensor arrangement 23a, 23b is
positioned either parallel to the rotational axis 20 of the
chopping drum 7 or parallel to the cutting edge 24 of the chopping
knives 8 at the drum base 21 and/or rear drum wall 22. The view at
lower right in FIG. 2 shows the possible orientations of the sensor
arrangements 23a, 23b depicted individually merely by way of
example. All of the sensor arrangements 23a, 23b are preferably
positioned either parallel to the rotational axis 20 of the
chopping drum 7 or parallel to the cutting edge 24 of the chopping
knives 8. In the depicted embodiment example, the sensor
arrangements 23a, 23b are constructed as induction sensors 25 to be
described more fully in the following. Each sensor arrangement 23
comprises one or more magnetic exciter arrangements 26 and, in each
instance, a pole arrangement 27 cooperating with the latter.
[0034] FIG. 3 depicts some characteristics of the sensor
arrangements 23a, 23b. The further details of the sensor
arrangements are given in DE 10 2017 103 537 A1, the disclosure of
which is hereby incorporated by reference in its entirety herein.
The detection arrangement 28 according to the invention for
detecting a wear status of a chopping knife arrangement 9a, 9b
comprises a plurality of sensor arrangements 23a, 23b, preferably
for each chopping knife arrangement 9a, 9b. Every sensor
arrangement 23a, 23b is formed by a plurality of magnetic exciter
arrangements 26 which are coupled with a flux conducting device 29.
The respective sensor arrangement 23a, 23b provides a pole
arrangement 27 which forms at least one magnetic pole 30,
preferably five magnetic poles 30, with a pole surface 31 in each
instance for conducting magnetic flux. During a rotation of the
chopping drum 7, a chopping knife 8 passes the respective pole
arrangement 27, and the chopping knife 8 passing the pole
arrangement 27 forms an air gap arrangement 32 with at least one
air gap 33 with respect to the pole arrangement 27, and at least
one magnetic circuit 34 excited by the exciter arrangement 26 is
accordingly closed via the respective chopping knife 8. The
detection arrangement 28 further has a measuring arrangement 35 and
an evaluating unit 36. In a manner which will be described more
fully later, the measuring arrangement 35 detects at least one
measured magnetic value 37 pertaining to the magnetic flux,
preferably an induced voltage 38 in at least one magnetic circuit
34 excited by the exciter arrangement 26, and the evaluating unit
36 determines the wear status 39 of the respective chopping knife 8
from the at least one detected measured value 37.
[0035] Details of the measuring device will now be described
referring to FIG. 4. During operation of the chopping drum 7, the
chopping knives 8 are guided past the respective sensor arrangement
23a, 23b according to the rotational direction 40 of the chopping
drum 7. Owing to the virtually non-magnetic properties of the rear
drum wall 22 or of the drum base 21 which preferably comprises
stainless steel, the magnetic circuits 34 formed by adjacent
magnetic poles 30 penetrate the chopping knife 8 passing over the
sensor arrangement 23a, 23b, respectively. In the depicted
embodiment example, four magnetic circuits 34 which penetrate the
respective chopping knife in four sections L1 to L4 are formed
between the five poles 30. For each of these sections L1 to L4, a
voltage 38, i.e., the measured magnetic value 37, is induced in the
measuring arrangement 35 associated with each section L1 to L4. The
evaluating unit 36 associated with the detection arrangement 28
determines and records the section-by-section induction voltage
38a-e in each instance. In this respect, it lies within the scope
of the invention that the respective sensor arrangement 23 has more
or less than the disclosed five magnetic poles 30 so that there can
also be more or less than five induced voltages 38a-e. It also lies
within the scope of the invention that the voltage signals 38a-e
can be combined to form one or more voltage signals 38 for each
chopping knife 8 detected.
[0036] The respective voltage signal 38a . . . e is converted in
the evaluating unit 36 into a voltage signal 49a . . . e which can
be further processed. This voltage signal 49a . . . e which can be
further processed is formed in such a way that the induced voltage
38, i.e., the reference value 38 of the induced voltage, is
initially determined for a sharp, unworn chopping knife 8, the
induction voltage 38a . . . e which changes contingent on wear is
then determined during the operation of the chopping knife 8 and,
lastly, the voltage signals 49a . . . e which can be further
processed are determined from the difference of the wear-dependent
change in induction voltage 38a . . . e minus the reference value
38 of the induced voltage of an unworn chopping knife 8.
[0037] The respective voltage signals 49a . . . e is then resolved
into its frequency components 42, preferably oscillation period or
phase 43 and amplitude 44, in the evaluating unit 36 in a manner
known per se by means of frequency analysis 41, preferably by means
of Fourier analysis 47. In doing so, the respective induced voltage
signal 49a . . . e is separated into frequency components 42 of a
fundamental oscillation 45 and into frequency components 42 of a
superposed oscillation 46 which cause signal distortions. The
separated frequency components 42 causing a signal distortion,
i.e., the so-called superposed oscillation 46, are then
inverse-transformed in the time domain 48 in a manner to be
described more fully later and, lastly, a measurement for the
cutting sharpness, i.e., the wear status 39, of a chopping knife 8
is derived from the inverse-transformed frequency components 42 in
a manner which will likewise be described more fully later.
[0038] The frequency analysis 41 carried out according to the
invention by the evaluating unit 36 is shown schematically in
detail in FIG. 5. The voltage signal 49a-e derived in each instance
from the induced voltage 38a-e is initially derived in the manner
described above. The respective voltage signal 49a . . . e is then
resolved into its frequency components 42 by means of Fourier
analysis 47. In this case, as has already been described, a
fundamental oscillation 45 and one or more superposed oscillations
46, so-called harmonics 50, causing the signal distortions are
separated. When a chopping knife 8 moves past the sensor
arrangement 23a . . . b formed as induction sensor 25, the
respective chopping knife 8 changes the permeability in the air gap
33 in front of the sensor arrangement 23a . . . b. Consequently,
the magnetic induction changes. This change can be measured by
means of the respective induced voltage 38a . . . e. Regardless of
whether its cross-sectional shape is curved or planar, a typical
chopping knife 8 comprises essentially three characteristic areas.
The first area 51 defines the roundness of the knife tip 52 and is
determined by its radius; the smaller its radius, the sharper a
chopping knife 8 is. The so-called grinding surface length 54
defines a further area 53. An increasing grinding surface length 54
is a measurement for increasing wear 39 of the respective chopping
knife 8. Lastly, the so-called knife back 56 is distinguished as
the third area 55; its shape and quality can be utilized as a
measurement for describing the general wear status 39 of the
respective chopping knife 8. The general wear status and wear are
both denoted in the following as wear 39 for reasons of
simplicity.
[0039] The voltage signal 49a . . . e shown at bottom right in FIG.
5 results for the curved chopping knife 8 in the depicted
embodiment example. Voltage signal 49a. . . e is shown here over
the angle position 57 of the chopping knife 8 relative to the
respective sensor arrangement 23a . . . b, and the angle position
0.degree. describes the central position of the chopping knife 8 in
front of the respective sensor arrangement 23a . . . b.
[0040] It will be noted that the described characteristic areas 51,
53, 55 induce voltages 49a . . . e of different levels. The area
51, 52 describing the roundness of the knife tip induces the
highest total voltage 49a . . . e. It will be noted at the same
time that the size of the air gap 33 has an influence on the
induced voltage 49a,e. As expected, the value of the induced
voltage 49a . . . e decreases as air gap 33 increases. The signal
shape of the induced voltage 49a . . . e is acquired and separated
for every knife. This means that a plurality of voltage signals 49a
. . . e are available for each chopping knife 8 depending on the
configuration of the sensor arrangement 23a . . . b. According to
FIG. 3, every magnetic pole 30 of the pole arrangement 27 generates
an induced voltage 38a . . . e. These induced voltages 38a . . . e
are then subjected to the frequency analysis 41 by means of Fourier
analysis 47 in the evaluating unit 36 after conversion into the
voltage signals 49a . . . e described above. As has already been
described, the Fourier analysis 47 separates these voltage signals
49a . . . e into frequency components 42 of a fundamental
oscillation 45 and frequency components 42 of one or more
superposed oscillations 46, or harmonics 50, which cause the signal
distortion.
[0041] FIG. 6 describes the individual steps of the frequency
analysis 41 in detail. In the first analysis step 58, the induced
voltages 38a . . . e are subjected to a Fourier analysis 47 as
voltage signals 49a . . . e in the manner already described, and
the fundamental oscillation 45 and superposed oscillation 46
determine approximately one or more of the harmonics 50. The
frequency analysis 60 shown in a further analysis step 59 shows
that the amplitudes 61 of sharp knives 62 differ only
insignificantly from those of blunt knives 63 regardless of whether
the oscillation is a fundamental oscillation 45 or a superposed
oscillation 46. In the subsequent analysis step 64, the determined
fundamental oscillation 45 is no longer taken into account, and
only the frequency components 42 of the superposed oscillations 46
causing a signal distortion are inverse-transformed in the time
domain 48. The results of this inverse-transformation are
visualized in an exemplary manner in analysis step 64 with the
example of three chopping knives 8 with chopping performance of
different lengths. Chopping knife 8a has the highest chopping
performance, while chopping knife 8b delivered approximately 40% of
the chopping performance of chopping knife 8a, and chopping knife
8c delivered only approximately 10% of the chopping performance of
chopping knife 8a. Consequently, the wear status 39 and, therefore,
the cutting sharpness 65 of each chopping knife 8 can be deduced
from the inverse-transformed frequency components 42 of the
superposed oscillations 46.
[0042] FIG. 7 schematically shows the implementation of a cutting
sharpness adjustment. As already stated, the amplitude 44 of the
respective induced voltage 38a . . . e and the voltage signal 49a .
. . e derived therefrom form a measurement for the wear status 39
and, analogously, the cutting sharpness 65 of a chopping knife 8.
Usually, a chopping knife 8 counts as sharp when the roundness (the
radius) of the knife tip 52 amounts to approximately 0.04 mm. The
amplitudes 44 of the chopping knives 8a . . . c shown by way of
example in FIG. 7 correspond to radii of the knife tip 52 of
approximately 0.1 mm-0.25 mm-0.6 mm, and an increasing roundness 52
corresponds to an increasing wear 39 and a decreasing cutting
sharpness 65. In the simplest case, a "sharp knife" reference value
66 can now be stored in the evaluating unit 36 or other data
processing device, including an external data processing device. In
the simplest case, this reference value is a stored reference value
66 of the amplitude 44 of the induced voltage 38a . . . e, 49a . .
. e. If the value falls below reference value 66, a grinding signal
67 is then generated. In this case, as will be explained in the
following, this grinding signal 67 can conceivably be generated in
different ways. In the simplest case, the chopping knife or
chopping knives 8 which have fallen below the "sharp knife"
threshold value can be displayed to an operator 68 on a display 69.
In this case, the operator decides when a grinding process 70 of
the chopping knives 8 is to be initiated. However, it is also
conceivable that a control device 71 monitors the adherence to the
"sharp knife" reference value 66 and automatically initiates the
grinding process 70. The automatic initiation of the grinding
process 70 is preferably defined such that a minimum number of
chopping knives 8 must fall below the reference value 66 before a
grinding process 70 is activated. In a manner known per se, it is
also taken into account that the forage harvester 2 is not in a
working mode in that crop 5 is moved through the forage harvester
2.
[0043] Alternatively or additionally, the assessment of the wear
status 39 or of the cutting sharpness 65 can also be coupled to
evaluation criteria 72. Preferably, the evaluation criteria can be
one or more of the evaluation criteria comprising "grinding surface
length 54 of the respective chopping knife 8" 72a, "roundness of
the chopping knife tip 52" 72b, "general knife wear 39" 72c and/or
"camber of the chopping knife 8" 72d or "relative distance of the
shear bar 11 from the chopping knife 8" 72e. Analogous to the
preceding description, a reference value 73 can also be stored in
the evaluating unit 36 or other data processing device, including
an external data processing device, with respect to the evaluation
criteria 72a . . . e. In the simplest case, this is a stored
reference value 73 of the amplitude 44 of the induced voltage 38a .
. . e, 49a . . . e. Depending on the selected evaluation criterion
or individual stored evaluation criterion 72a . . . e, the stored
reference value 73 is then either a measurement for the wear status
39 of the respective chopping knife 8 in total or for the sharpness
of the cutting edge 24. If the value falls below the reference
value 73, the grinding signal 67 described above is generated. This
grinding signal 73 can then conceivably be generated in different
ways. In the simplest case, the chopping knife or chopping knives 8
which have fallen below the reference value 73 can be displayed to
an operator 68 on a display 69. In this case, the operator decides
when a grinding process 70 of the chopping knives 8 is to be
initiated. However, it is also conceivable that a control device 71
monitors the adherence to reference value 73 and automatically
initiates the grinding process 70. The automatic initiation of the
grinding process 70 is preferably defined such that a minimum
number of chopping knives 8 must fall below the reference value 73
before a grinding process 70 is activated. It is also taken into
account in a manner known per se that the forage harvester 2 is not
in a working mode in that crop 5 is moved through the forage
harvester 2.
[0044] Alternatively or additionally, when the value falls below
the reference value 66 or reference value 73, replacement of a
chopping knife 8 can be suggested, namely, when measurements fall
below reference value 66, 73 to such an extent that it can be
inferred that the respective chopping knife 8 is at the end of its
usable range.
[0045] In view of the fact that the induced voltage 38a . . . e,
i.e., the voltage signal 49a . . . e derived therefrom increases
with increasing roundness 52 of the cutting edge 24 of the chopping
knives 8, it is provided that the reference value 73 is an
amplitude 44 of the determined voltage signal 49 when the
"roundness of the chopping knife tip 52" evaluation criterion 72b
is selected.
[0046] Since the oscillation period 43 of the induced voltage 38a .
. . e increases with increasing grinding surface length 54 of the
chopping knife 8, the reference value 73 is an oscillation period
43 of the derived voltage signal 49a . . . e when the "grinding
surface length 54 of the respective chopping knife 8" evaluation
criterion 72a is selected.
[0047] Due to the fact that the oscillation period 43 and the
amplitude 44 of the induced voltage 39a . . . e both increase
significantly with increasing general wear 39 of chopping knife 8,
reference value 73 is an amplitude 44 and an oscillation period 43
of the determined voltage signal 49a . . . e when the "general
knife wear" evaluation criterion 72c is selected.
[0048] The distance of the chopping knife 8 from the shear bar 11
increases and the amplitude 44 of the induced voltage 38a . . . e
decreases significantly with increasing wear 39 of the chopping
knife 8 so that when the "camber of the chopping knife 8" or
"relative distance of the shear bar 11 from the chopping knife 8"
evaluation criterion 72d, e is selected, reference value 73 is an
amplitude of the determined voltage signal 49a . . . e.
[0049] The driver assistance system 80 according to the invention
is shown in detail in FIG. 8. As has already been described, sensor
arrangements 23a . . . b which determine the wear status 39 of the
chopping knives 8 in the manner that has already been described are
associated with the chopping drum 7 in the area of the drum base 21
and/or with the rear drum wall 22. The knife grinding device 17 is
associated with the chopping drum 7 in upper area thereof. The
knife grinding device 17 comprises at least the grinding stone 18,
a carriage 81 receiving the grinding stone, and an adjusting
cylinder 82 moving the carriage 81 parallel to the rotational axis
20 of the chopping drum 7. The grinding stone 18 is guided by the
carriage 81 in a manner known per se such that it is positioned in
a nonworking position lateral to the chopping drum 7 and is guided
in the work position 83 along the envelope curve 84 defined by the
chopping knives 8 during the rotation of the chopping drum 7 so
that the grinding stone 18 passes over at least the grinding
surface length 54 of the knife back 56 of the chopping knives
8.
[0050] In a manner known per se, the shear bar 11 associated with
the chopping drum 7 is swivelably movably guided in a bearing 86
associated with the underside of the shear bar 11 by a swiveling
mechanism 85. The edge 87 of the shear bar 11 facing the chopping
drum 7 is positioned so as to be spaced apart from the envelope
curve 84 of the chopping drum 7 by a determined distance 88, the
so-called cutting gap 89. Further, at least one actuating motor 90
which enables a change of position of the shear bar 11 and,
therefore, a change in the cutting edge 89, is associated with the
swiveling mechanism 85 likewise in a known manner. Further, the
shear bar 11 receives one or more ping sensors 91 which are capable
of determining the distance of the shear bar 11 from the envelope
curve 84 of the chopping drum 7 by means of vibration analysis.
[0051] The driver assistance system 80 according to the invention
further comprises a monitoring device 92. In a known manner, the
monitoring device 92 receives the acoustic signals A generated by
the ping sensors 91 and generates distance signals B therefrom
which correspond to the distance 88 of the shear bar 11 from the
envelope curve 84 of the chopping drum 7. Further, the monitoring
device 92 is capable of generating actuating signals C for
activating the actuating motor or actuating motors 90. Further, the
monitoring device 92 is constituted such that it generates the
knife grinding signal D which causes the knife grinding device 17
to be activated or deactivated so that the grinding stone 18 can be
moved radially and tangentially relative to the respective cutting
edge 24 of the chopping knives 8. The monitoring device 92 further
comprises a module 93 which is constituted in such a way that it
generates information I about the wear status 39 of every chopping
knife 8. The module 93 is preferably formed by the above-described
evaluating unit 36. Further, the "sharp knife" reference value 66
which has already been described and a reference distance value 94
for the distance 88 of the shear bar 11 from the envelope curve 84
of the chopping drum 7 are stored in the monitoring device 92.
[0052] The monitoring device 92 further comprises a comparison step
95 in which the information I concerning the wear status 39 of the
chopping knives 8 and/or the distance signal B representing the
distance 80 of the shear bar 11 from the envelope curve 84 of the
chopping knives 8 are compared with the respective reference value,
namely, the "sharp knife" reference value 66 and the reference
distance value 94. According to the invention, the monitoring
device 92 is integrated in the driver assistance system 80 in such
a way that the driver assistance system 80 automatically detects
when a knife grinding process 96 must be activated or deactivated
and/or when a change of position 97 of the shear bar 11 must be
activated or deactivated. In the simplest case, this is effected in
such a way that it is determined in comparison step 95 whether the
actual value lies below or above the respective reference values
66, 94. As soon as this is determined, the driver assistance system
80, in a manner to be described more fully, generates the actuating
signal C for activating the actuating motor or actuating motors 90
of the shear bar 11 for the purpose of change of position 97 of the
shear bar and/or generates the knife grinding signal D for
activating or deactivating the grinding process 96. In this
respect, the grinding process 96 is terminated when it is
determined in comparison step 95 that the information I defining
the wear status 39 of the chopping knives 8 has reached or again
lies above the stored associated "sharp knife" reference value 66.
Analogously, the change of position 97 of the shear bar 11 is
deactivated when it is determined in comparison step 95 that the
stored reference distance value 94 was reached. With respect to the
process, known per se, of moving the shear bar 11 into the
respective position, reference is made to EP 2 764 767, the
disclosure of which is hereby incorporated by reference in its
entirety herein.
[0053] Further, the driver assistance system 80 is constituted in
such a way that the actuating signals C generated by it and the
generated knife grinding signals D either start and stop the
grinding process 96 directly or start or stop the change of
position 97 of the shear bar 11. Alternatively or additionally, it
also lies within the scope of the invention that the actuating
signals C and/or the knife grinding signals D generate a
notification to an operator 68 of the agricultural work machine 1
to activate or deactivate the grinding process 96 and/or the change
of position 97 of the shear bar 11.
[0054] It further lies within the scope of the invention that the
"sharp knife" reference value 66 and the reference distance value
94 of the shear bar 11 which are stored in the monitoring device 92
can be changed depending on the crop.
[0055] According to FIG. 9, the signals B, I which are generated by
the monitoring device 92 and which contain information I about the
wear status 39 of the respective chopping knife 8 and/or the
distance 88 of the cutting edge 24 of a chopping knife 8 from a
shear bar 11, the so-called cutting gap 89, are converted into an
actual cutting sharpness value 98 and an actual distance value 99
of the shear bar 11. The respective actual value 98, 99 is then
compared with the respective stored associated reference value, the
"sharp knife" reference by 66 or the reference distance value 94,
in comparison step 95 described above. If the actual cutting
sharpness value 98 lies below the "sharp knife" reference value 66
in comparison step 95', the grinding process 96 is activated.
Conversely, if the actual distance value 99 lies above the stored
reference distance value 94 in comparison step 95'', the change of
position 97 of the shear bar 11 is activated in one of the ways
described previously.
[0056] The actual cutting sharpness value 98 is monitored during
the activated grinding process 96. If the actual cutting sharpness
value 98 reaches or lies above the "sharp knife" reference value 66
in comparison step 95''', the grinding process 96 is deactivated.
The respective chopping knife 8 is deemed sharp. On the other hand,
if the actual distance value 99 reaches or lies below the stored
reference distance value 94 in comparison step 95'', the change of
position 97 of shear bar 11 is deactivated in one of the ways
described above, since the shear bar 11 has reached its position
stored in the monitoring device 92, i.e., the predefined cutting
gap 89.
[0057] Accordingly, the monitoring device 92 is constituted in such
a way that it monitors the cutting sharpness 65 and/or the wear
status 39 and/or the magnitude of the cutting gap 89 for each
chopping knife 8.
[0058] At the same time, the driver assistance system 80 is
constituted in such a way that a radius R of the chopping drum 7 is
determined from the distance signals B generated by the monitoring
device 92. Due to the fact that the distance signal B describes the
distance 88 of the shear bar 11, the edge 87 of the shear bar 11,
from the envelope curve 84, the distance of the cutting edge 24 of
a chopping knife 8 from the shear bar 11, a change in the radius AR
of the chopping drum 7 can be inferred from this distance signal
B.
[0059] Further, the driver assistance system 80 is adapted to infer
the quantity 100 of chopping knives 8 positioned on a chopping drum
7 from the chopping knife-specific signals generated by the
monitoring device 92, e.g., acoustic signals A and/or distance
signals B and/or the information I with respect to the wear status
39. A configuration signal K which automatically configures the
respective chopping drum 7 that is used in the driver assistance
system 80 is then generated from the determined quantity 100 of
chopping knives 8.
[0060] In a further advantageous configuration, a product
feed-dependent wear status 102 can be inferred, for example, from
the detected change in radius AR of the chopping drum 7 in a
further evaluating step 101, and steps are derived for bringing
about a product feed that reduces wear. In particular, the derived
steps can comprise a change in one or more parameters of the header
3 and/or of the gathering and pre-compacting rollers 4 arranged
downstream of the latter for picking up and conveying crop 5.
REFERENCE CHARACTERS
[0061] 1 agricultural work machine [0062] 2 forage harvester [0063]
3 header [0064] 4 gathering and pre-compacting rollers [0065] 5
crop flow [0066] 6 chopping device [0067] 7 chopping drum [0068] 8
chopping knife [0069] 9 chopping knife arrangement a . . . b [0070]
10 feed-in area [0071] 11 shear bar [0072] 12 cracker [0073] 13
after-comminution device [0074] 14 after-acceleration device [0075]
15 deflector [0076] 16 deflector flap [0077] 17 knife grinding
device [0078] 18 grinding stone [0079] 20 rotational axis of the
chopping drum [0080] 21 drum base [0081] 22 rear drum wall [0082]
23 sensor arrangement a . . . b [0083] 24 cutting edge [0084] 25
induction sensor [0085] 26 magnetic exciter arrangement [0086] 27
pole arrangement [0087] 28 detection arrangement [0088] 29 flux
conducting device [0089] 30 magnetic pole [0090] 31 pole surface
[0091] 32 air gap arrangement [0092] 33 air gap [0093] 34 magnetic
circuit [0094] 35 measuring arrangement [0095] 36 evaluating unit
[0096] 37 measured magnetic value [0097] 38 reference value of
induced voltage [0098] 38a.e induced voltage [0099] 39 wear status
[0100] 40 rotational direction [0101] 41 frequency analysis [0102]
42 frequency component [0103] 43 oscillation period/phase [0104] 44
amplitude [0105] 45 fundamental oscillation [0106] 46 superposed
oscillation [0107] 47 Fourier analysis [0108] 48 time domain [0109]
49 voltage signal a . . . e [0110] 50 harmonic [0111] 51 first area
[0112] 52 roundness of the knife tip [0113] 53 further area [0114]
54 grinding surface length [0115] 55 third area [0116] 56 back of
knife [0117] 57 angle position [0118] 58 first analysis step [0119]
59 further analysis step [0120] 60 frequency analysis [0121] 61
amplitude [0122] 62 sharp knife [0123] 63 blunt knife [0124] 64
analysis step [0125] 65 cutting sharpness [0126] 66 "sharp knife"
reference value [0127] 67 grinding signal [0128] 68 operator [0129]
69 display [0130] 70 grinding process [0131] 71 control device
[0132] 72 evaluation criterion a . . . e [0133] 73 reference value
[0134] 80 driver assistance system [0135] 81 carriage [0136] 82
adjusting cylinder [0137] 83 working position [0138] 84 envelope
curve [0139] 85 swiveling mechanism [0140] 86 bearing [0141] 87
edge [0142] 88 distance [0143] 89 cutting gap [0144] 90 actuating
motor [0145] 91 ping sensor [0146] 92 monitoring device [0147] 93
module [0148] 94 reference distance value [0149] 95 comparison step
[0150] 96 knife grinding process [0151] 97 change of position
[0152] 98 actual cutting sharpness value [0153] 99 actual distance
value [0154] 100 quantity of chopping knives [0155] 101 evaluating
step [0156] 102 wear status [0157] L1 . . . L4 sections [0158] A
acoustic signal [0159] B distance signal [0160] C actuating signal
[0161] D knife grinding signal [0162] I information on wear status
[0163] R radius [0164] .DELTA.R change in radius [0165] K
configuration signal
* * * * *