CA1129977A - Control of harvesters - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Apparatus for controlling the forward speed of operation of a combine harvester to either increase or decrease the speed, characterized by means for sensing the density of the output from the harvester and producing a first electrical signal one parameter of which varies with the variation in density of the harvester output, means for producing a second electrical signal the same parameter of which varies with variation in speed of operation of the .
drive for the harvesting apparatus, means for comparing the two electrical signals to produce a difference signal the magnitude and polarity of which indicate the relationship between the two generated electrical signals and means is provided for controlling the speed of operation of the drive producing forward movement of the harvester in a manner so as to cause the difference signal to be reduced to a minimum.

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Description

.z9~77 This invention concerns harvesting apparatus commonly known as combine harvesters and is particularly concerned with a device for controlling the operation of a combine harvester ~ as to maximise the output and reduce grain loss due to incorrect operating speeds.
It is an object of the present invention to provide a device which can be fitted to or built in to a combine harvester for controlling the forward speed of a harvester in relation to various operating parameters of the harvester and particularly in relation to the loss of harvested produc$s which occurs at certain points within the harvester.
The invention is of par~icular application to self-propelled combine harvesters but is not limited to such harvesters and may be fitted to combine harvesters which are themselves towed. In this second type of harvester an engine is still provided on the harvester but this is used to drive the harvesting machinery and there is no proviQion on such a harvester for propelling the harvester in a forward or reverse direction. In a self-propelled harvester an engine i~ provided for driving the road wheels of a harvester to : propeL it in a forward or reverse direction. Normally a single engine is provided to drive b~th the road wheels and the harvesting apparatus but it has been known to provide in self-propelled harvesters two engines, one to drive the road~wheels and the other to drive the harvesting machinery.
Where a single engine is provlded, lt is nevertheless usual to provide means for varying the speed of operation of both the road wheelQ~and/or the~harvesting~machinery independently ~ ~ of the other.
; ~ In:~a typical combine harvester, a reel rotates in front

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Z~7t7 of a cutting bar so as to cause the stems of corn to be cut near their lower end and the cut stalks are collected by an auger and supplied to a feed conveyor which elevates the stalks. After passing a feeder beater the stalks are ~ ~ `
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, Z~7 crushed below a cylinder which rotates against a curved tray or concave and the stalks containing the ears of corn are fed onto the tray between the latter and the cylinder. Threshed corn and unthreshed ears of corn fall th~rough the concave onto the preparation floor. The straw and what grain is held in suspension in the straw is carried around the cylinder and fed by a stripper beater onto straw walkers for æparation. After being pressed out of the ear, the corn falls through apertures in the tray onto a series of sieves and shakers and after passing through the sieves the corn is picked up by an elevator and transferred to a grain tank normally situated high up on the machine from which the grains of corn will fall under gravity into a sack or other collection vessel typically carried on the machine.
The separation of the corn from the stalks by the inter-action of the cylinder and tray is imperfect and quantities of chaff and parts of the ear can arrive on the shakers and sieves. In order to remove this chaff which tends to be less dense than the grains of corn, a blast of air is dixected in an upward direction through the sieves and when correctLy adjusted the chaff is blown~of~ the sieves whilst the grains of corn~remain on the sieves and are allowed to fall through the holes in the sieves to be picked up ~y-the elevator at the lower end of the machine If the air blast is too strong then corn will tend to be lifted as well as chaff and i the air blast is insuf-icient then considerable quantitles~of chaff will remain mixed with the grain.
Some of the~grains o~ corn remain in the ears attached ~to the stalks which are fed via the stripper beater onto

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` ' the straw shakers from which the straw stalks are ejected at the rear of the machine. This corn which tends to be shaken from the ears by the straw shakers can be recovered 3a -: ~

-1299"~7 by providing holes in the straw shakers through which the corn grains will fall and a return tray is usually provided which directs these grains of corn down onto the top of the sieves so that this reclaimed corn is mixed with the corn from the original separating stage and any chaff which a~so falls onto the sieves from the straw shakers will also be blown away in the same way as that which has come through from the main separating stage.
The forward speed of a combine harvester of the type described is usually such that the straw on the straw walkers forms a mat and grain does not fall through as it should, onto the preparation floor.
Likewise if the air blast is incorrectly adjusted grain will be blown from the sieves and will also be lost. By ob-taining a measure of the frequency of grains striking thesensQrs, so an indication as to whether too much grain is being blown from the sieves can be obtained.
Typically the sieves are shaken so that the grain pro-gresses from the front to the rear of the sieves and a collection tray to~the rear of the sieves collects the surplus grain whlch has not fallen through the sieves and returns it to the~main separating~stage to be reprocessed.
If the throughput is too great then the loading on the return elevator which collQc~s~and returns the unsieved grain to the maLn separating stage will be overloaded and an indication that too much grain is passing via the return elevator to the main separating stage is a further indi-cation that the machlne is progressing in the forward direction at a speed :: :
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To this end the invention provides in a harvesting apparatus having means for controlling the forward speed of operationof the harvester and means for sensing grain loss in said harvester, the improvement for improving the efficiency of the harvester and reducing grain loss comprising: producing a first electrical signal which varies with the variation in density of the harvester output, means for producing a second electrical signal which varies with variation in speed of operation of the drive for the harvesting apparatus, means for comparing the two electrical signals to producing a difference signal, the magnitude and polarity of which indicate the relationship between said first and said second electrical signals, and means for controlling the speed of operation of the drive producing forward movement of the harvester to cause said difference signal to be reduced to a minimum~
The function of the apparatus is therefore to control the forward speed of the harvester in such a way that the grain loss resulting from incomplete threshing of the ears of corn is kept at a constant ~alue which can be selected by the operator in advance.
Preferably display means is provided for indicating the degree of loss either as a numerical value in a scale of values or as a percentage o~ the harvested grain.

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Preferably indicator means are provided for indicating whether the forward speed of the harvester is correct or is too great or is less than could be sustained for any given grain loss and means may be provided to override the automatic speed controls to allow the operator to increase or decrease the forward speed of the harvester manuall~
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ViSUAl display ~hich i~ indicated. Typically three differently coloured lamps are provided one to indicate tnat the forward speed of the harvester is too ~reat, another to irldicate that the forward speed i6 les6 than it could be and another to indicate that the forward speed is just sufficient ~5 to produce the particular corn loss which can be accepted.
Preferably means is provided for derivirlg a third electrical ~ignal also proportional to the speed of the drive for the harvesting apparatu6 and further display means i6 provided for indicating the value of the electrical signal which is proportional to the speed of the drive.
/~ Typically a calibrated meter is provided the position of the needle indi-cating the speed of rotation of the drive at any time.
Preferably 6ensors are located to detect tha density of the output from the straw shaker6 or walkers as they are ~ometime6 called, the output from the upper region of tha sieve brought about by the air bla6t and the /5 output from the main ~ieve of the harve~ti~g apparatus.
Preferably the apparatus includes switch mean6 whereby the electrical 6ignals derived from each of the 6ensors located in the output6 previo~sly described can be separately applied to the control circuit means of the invention so that the lost corn from each of these three output~ of the c~C) machine can be monitored separately and an indication aR to the leYel of lost corn from each output ? splayed or otherwi6e indicated. The switch mean6 preferably include~ a fourth position in which all the three elec trical signal~ are supplied to the electrical circuit mean6 of the in-~ention simultaneou61y. When a~l three signals are supplisd 6imultane-ously, the circuit operates so as to produce a difference signal in the event that the signal indicating the total corn los~ i6 greater or les6 th~ the signal derived from the speed of the drive for the harvesting .
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, 1~2~7~7 apparatus and the dif~erence signals are employed to alter the forward sp2ed of the harvester to reduce the difference signal which has been produced.
The invention will now be described by way of example with reference to the accompanying drawings in which:
Fig. 1 is a cross~section through a typical combine harvester illustrating the crop flow through the harvester, Fig. 2 is a view of a front panel of apparatus constructed as an embodiment of the invention for indicating the per-formance of the combine harvester with regard to corn lossand Fig. 3 is a circuit diagram of the electronic apparatus to which the signals are supplied from the sensors and by which the forward speed of operation of the harvester can be controlled.
Referring fir t to Fig. 1, there is shown a combine harvester for harvesting a standing crop of corn 10. The harvester includes a transverse rotating reel 12 having flails which engage tha standing crop 10 and cause the stalks to be chopped by a cutting bar 14. The chopped stalks are fed via an auger 16 to a feed conveyor 18 which elevates the chopped stalks past a feeder beater 20 and into the threshing region of the harvester. This comprises a generally cyl-indrical member 22 having a plurality of peripheral transverse abutments which engage with part o the surface of a curved tray 24 between which the stalks are crushed. The crushing action causes the grains of corn in the ear to be rubbed or .
knocked out of the ear and the grains fall through perfor-ations in the tray 24 onto a shaker conveyor and sieve assembly Z6.

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The stalks from ~hich the g.rains of corn have been threshed leave the cylinder 24 and pass under a stripper beater 28 after which they fall onto .

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g9~7 a further shaker conveyor or straw walker as it is sometimes called generally designated by reference numeral 30.
The latter includes apertures or perforations and in the event that grains of corn remain in the ears, the shaking action tends to shake out any remaining grains and these pass through the apertures or perforations onto a collecting tray or grain pan 32 which is inclined in a downward direction to cause the grains to roll down onto the top of the sieve and shaker assembly 26.
Assuming that the threshing and shaking action is satisfactory, very few grains will remain in the ears of the stalks which arrive at the upper rear end of the shaker conveyor 30 from where the now threshed stalks or straw is ejected through an exit at the rear of the machine.
Grains of corn falling on the shaker and sieve assembly 26 pass through the sieve and through a second or bottom sieve 34 into a collection chamber or hopper 36. A conveyor 38 serves to lift the grain~ of corn from the hopper 36 above a tank 40 and a chute 44 allows the elevated grain to fall into the tank4 O. The latter is conventionally emptied into a trailer (not shown) towed alongsid~.
A fan is shown at 42 for directing an air blast upwardly through the sieves 26 and 34 so as to blow chaff off the sieves and out through a further exit at the rear of the machine. This chaff draught is denoted by reference numeral

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In the event that the thxoughput is too great, grain and chaff etc. and ears of corn which have only been partially threshed will reach the rear end of the ieve ~6. A large ~. . .-' ~ ~Z~977 mesh sieve in the form of an extension 48 beyond the sieve 26 allows grain and partially threshed grain to fall .
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down a chute to be collected by a return elevat~r 50 which conveys the grain etc. to an auger 52 for transferring the return grain etc. to the input to the cylinder 22 and tray 24 usually thought of as ~he main separating stage within the apparatus. The returned grain is then reprocessed. The chaff blows off the extension 48, as a third output from the machine and if loading on the sieves or air blast is in-correct grain will also be blown over on the output 46.
The invention requires sensors to be located at positions ~ , 56 and 58 so as to monitor the density of the overflow from the straw shakers 30, the air blast 56 and the output 46. Appropriate sensors comprise flat plate sensors such as are available from Ashtronic (Agricultural) Limited. Such sensors can be adapted to produce an increase in conductivity as the density of the overflow material falling thereon in-creases. This conductivity variation can be used to produce a varying electrical signal the value of ~hich is relatad to tha density of the overflow material falling on the sensor.
Fig. 2 shows the various controls and meter displays which can be made available to the operator such as 60 in Fig. 1 and Fig. 3 is an electrical circuit of the apparatus required to convert the electricaI signals ~rom the three monitors situa~ed at 54, 56 and 5B in Fig. 1 into contrsl signals for controlling the forward speed of the harvester and to produce a visual indication of the performanca of the harvester at any time~
The reference numerals used in Fig. 2 correspond to the appropriate parts of el~ctrical circuit shown in Fig. 3 and will be referred to as the circuit of Fig. 3 is d~scribed.

_ g _ . , - , 7~7 The three sensors are indicated by the circuit box 62, 64 and 66. A 3-pole 4-way switch generally designated 68 allows each of the sensors 62,64 and 66 to be connected in turn to the electronic equipment and in the fourth position allows all three sensors to be connected to the equipment simultaneously.
The sensors 62, 64 and 66 are located at the positions 54, 56 and 58 respectively in Fig. 1 and the signals on lines 70, 72 and 74 therefore correspond to the density of the out-10 put material from the s~raw shakers 30, air blast and sieve -overflow.
Transistors TRl, TR2 and TR3 provide signal amplification : of the three signals on lines 70, 72 and 74. For each of the amplifiers, the quiescent state of the sensor is arranged to cause the associated transistor TRl (TR2 or TR3) to conduct so causing the collector voltage of the transistor to be low.
; In the even* that grain particles strlke a sensor, a momentary reduction in base current available to the transistor assoc-iated therewith results and this causes a momentary rise of ~ 20 the collector potentlal which is conveyed via one of the : diodes Dl, D2~and D3 to the capacitor C5. If a continual stream of grains impinge on the~sensor then a continual train o~ pulses is supplied to the capacitor C5~;causing the base current~to ~ransistor TR4 to incxease:which in turn causes ~25 a rise in the current flowing through the transistor junction and a higher voltage to be developed across the potentivmeter : VR4.
~: The VR4 tapping determines ~he:base current available for TR5 and ths value of the base current will determine the current through the transistor junction as displayed by the 10- ~
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The signal at the tapping of VR4 is also supplied via D4 to one input of a differential amplifier 78 having a very high gain which is fed ' :

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back via an adjustable feedback resistor chain the value of which is determined by the setting of VR3 to the other input.
To this said other input is supplied a voltage derived from VR2 which constitutes a partially smoothed direct current voltage obtained by a 4-way rectifying bridge 80 which is supplied with alternating current from an alternator driven by an engine (not shown) mounted on the harvester shown in Fig. l and adapted to drive the harvesting apparatus such as the drum etc.
A second rectifying bridge 82 also produces a direct current voltage equivalent to the amplitude of the incoming alternating current signal amplitude and a second meter 84 is connected across this second bridge rectifying circuit 82 to produce a visual indication of engine speed. The alternator lS is designed and operated in a region in which increasing speed produces a proportional and linear increase in amplitude o~ the output voltage which in turn appears as an increase in voltage across the output of the 4-way rectifying circuit 82. Meter 84 can therefore comprise a voltmeter or current meter which is calibrated to indicate engine r.p.m.
The output from the differential amplifier 78 is supplied via resistor R21 to~the bases~of two transistors TR6 and TR7.
If~the output is posit1ve TR6 is~switched on and TR7 remains switched off and relay RL~l is operated causing its associated 25~ contacts to be closed wi~h the result that lamp 90 is illuminated.

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If the output is negative, TR7 is turned on and relay RhA2 is operated causing amber light 92 to be illuminated.

If the output from the differential amplifier is zero 30 ~ neither TR6 ,, ' ' ', ~ ' ' `.

LZ~77 , nor RR7 is turned on and lamp 88 which is a green lamp is illuminated.
Adjustment of the potentiometer VR2 determines the percentage of the direct current voltage developed from the generator which is applied to the upper input of the diff-erential amplifier 78.
Potentiometer VR4 determines the percentage of the signal which is developed across the capacitor C5 by grain falling upon the sensors which is to be applied to the lower input of differential amplifier 78 via diode D4.
The setting of VR3 determines the resistance of the negative feed-back path from the ou~put of the differential amplifier 78 to the upper input and by adjustment of VR3 so the magnitude of the difference voltage which will produce sufficient change in the output voltage one way or the other to trigger TR6 or TR7 is adjusted. In this way the so-called dead zone (i.e. the range o~ speed vari~tion of the motor or increase of loss of grain before TR~ or TR7 is triggered) can be increased or decreased.
Switching of the contacts associated with relays Rh~l and RLA2 is arranged to cause current to flow through a solenoid 94 or a solenoîd 96 re ~ ctively and valves op~rated by energisation of the solenoid serve to control the flow of hydraulic fluid to one side or the o her of a hydraulically operated speed control device. This speed control device operates on the drive to the road wheels such as 98.
Alternatively it may control the driving speed of road wheels on a tractor or other pulling vehiole (not shown in Fig. 1) which is adapted to pull th~ combine~harvester in a forward :' , ~' . ' , , .
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direction where the latter is not self-propelled~
The apparatus can be set to simply indicate whether the forward :, ~ :: : i , , ~ , :
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speed is too high or too low by disconnecting the solenoid valves or removing the hydraulic supply therefrom and providing a manual control for controlling the forward speed of the combine harvester. The operator such as 60 then simply watches the lights 88, 90 and 92 and makes appropriate adjustments in the forward sp~ed of the combine harvester in the event that either the red or amber lamp is illuminated.
When in its automatic mode of operation in which the solenoid valves automatically make adjustments in the forward speed of the combine harvester, the effect of the apparatus is to automatically adjust the forward speed of the vehicle until it is as high as is compatible with the desired level of grain loss. The apparatus is thus set up by adjusting VR2 so that loss monitor needle 76 is centralised and the acceptable level of loss is set up by adjusting VR4 so that the needle of 76 is deflected by the appropriate amount.
Once the harvester moves forward, -the grain loss is monitored by the three sensors and in the event the grain loss signal developed across C5 becomes large enough, the signal supplied from V~4 to the lower input of 78 will be sufficient to cause TR6 to trigger and the red ligh~ 90 will come on indicating that the forward speed of the harvester is too high. Solenoid 94 will be operated and assuming that the control means for adjusting the forward speed of the harvester is operational so the forward speed will be reduced until the grain loss signal on C5 has reverted to the acceptable level indicated by the difference signal in the output of 78 reducing to zero causing ~R6 to turn off and lamp 90 to be extinguished. Solenoid g4 becomes de-energised in consequence and the harvester continues at the new speed.

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If the grain loss was caused by a te~porary pro~lem the signal ~: :

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de~eloped across C5 will fall and this will cause a corresponding drop in the voltage fro~ VR4 and when a sufficiently lar~e difference between the two input signal6 to 78 is achieved, the output will cause TR7 to become conductin~ and relay RLA2 to be energised. Solenoid 96 will ~5 consequently be energised along with amber lamp 92 indicating that the forward 6peed of the harvester is les6 than it could be since the grain loss is smaller than would be accepted and with the operation of 601enoid 96, the speed of the forward drive for the harvester i6 increased until the grain 1066 6ignal across C5 has once again increa6ed to a value such J ~ that the input signal6 to amplifier 78 are once a~ain equal and the difference output signal has once again been reduced to zero thus causing TR7 to cease conducting and amber light 92 and solenoid 96 to become de-energised. Favourable operatior. of the harvester is indicated by the green light 88.
~5 In the event that the automatic 6peed control sets the forward speed of the harve6ter at what appears to be too low a speed, this is an indica-tion that grain los~ from one or other of the outlets from the harvester is too great and that an appropriate adjustment may be needed to com-pe~sate. By switching switch 68 from one position to the next ~o the O three sensor6 can be monitored in turn and the output producing the highest reading on monitor 76 can be checked and adjusted so as to reduce the grain 106s as ~een by that particular sensorO Having adjusted this particular loss on the machine the switch 68 is then returned to its original po6ition in which all three sensors are connected to the appro-c2 ~ priate input circuits TR1, TR2 and TR3 and the harvester can once againcontinue in operation. Having improved the efficiency of the offending stage in the har~ester, it will be found that the automatic control circuit ,~

99~7 will immediately allow the harvester to pick up speed and move forward at a higher speed than before until once again this forward speed is limited by the grain loss setting.
As engine speed drops due to crop conditions and the load being applied to the machine, the unit will automatically adjust the forward speed to reduce the loading on the engine.
This allows the engine to regain maximum revolutions, so returning the speed of operation of the threshing cylinder, cleaning fan, sieve box and straw walker to the manufacturer's required settings to get the best from their individual functions. This reduces losses and enables the machine to operate at high efficiency under most conditions, :
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Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a harvesting apparatus having means for controlling the forward speed of operation of the harvester and means for sensing grain loss in said harvester, the improvement for improving the efficiency of the harvester and reducing grain loss comprising:
means producing a first electrical signal which varies with the variation in density of the harvester output, means for producing a second electrical signal which varies with variation in speed of operation of the drive for the harvesting apparatus, means for comparing the two electrical signals to producing a difference signal, the magnitude and polarity of which indicate the relationship between said first and said second electrical signals, and means for controlling the speed of operation of the drive producing forward movement of the harvester to cause said difference signal to be reduced to a minimum.

2. Apparatus as claimed in claim 1, including display means for indicating the degree of loss either as a numerical value in a scale of values or as a percentage of the harvested grain.

3. Apparatus as claimed in claim 1 or 2, including indicator means for indicating whether the forward speed of the harvester is correct or is too great or is less than could be sustained for any given grain loss.

4. Apparatus as claimed in claim 1 or 2, including means to override the automatic speed control to allow the operator to increase or decrease the forward speed of the harvester manually according to the visual display which is indicated.

5. Apparatus as claimed in claim 1 or 2, including three differently coloured lamps, one to indicate that the forward speed of the harvester is too great, another to indicate that the forward speed is less than it could be and the third to indicate that the forward speed is just sufficient to produce the particular grain loss which can be accepted.

6. Apparatus as claimed in claim 1 or 2, including means for deriving a third electrical signal also proportional to the speed of the drive for the harvesting apparatus and further display means for indicating the value of the electrical signal which is proportional to the speed of the drive.

7. Apparatus as claimed in claim 1 or 2, including a calibrated meter, the position of the needle thereof indicating the speed of rotation of the drive at any time.

8. Apparatus as claimed in claim 1 further comprising straw shaker means thereon; and sensors to detect the density of an output from said straw shakers, an output from an upper region of a sieve, brought about by an air blast; and an output from a main sieve of the apparatus.

9. Apparatus as claimed in claim 8, including switch means whereby electrical signals derived from each of three sensors located in said outputs can be separately applied to the controlling means so that the amount lost grain from each of these three outputs can be monitored separately and indicated.

10. Apparatus as claimed in claim 9, wherein the switch means includes a fourth position in which all the three electrical signals are supplied to the controlling means simultaneously whereby to produce a fourth difference signal in the event that the signal indicating the total grain loss is greater or less than the signal derived from the speed of the drive for the apparatus, said further difference signal being employed to alter the forward speed of the harvester to reduce the original difference signal.