CA1113581A - Sieve overload sensor - Google Patents
Sieve overload sensorInfo
- Publication number
- CA1113581A CA1113581A CA318,119A CA318119A CA1113581A CA 1113581 A CA1113581 A CA 1113581A CA 318119 A CA318119 A CA 318119A CA 1113581 A CA1113581 A CA 1113581A
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- Canada
- Prior art keywords
- signal
- signals
- responsive
- providing
- coupled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D—HARVESTING; MOWING
- A01D41/00—Combines, i.e. harvesters or mowers combined with threshing devices
- A01D41/12—Details of combines
- A01D41/127—Control or measuring arrangements specially adapted for combines
- A01D41/1276—Control or measuring arrangements specially adapted for combines for cleaning mechanisms
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- Life Sciences & Earth Sciences (AREA)
- Environmental Sciences (AREA)
- Threshing Machine Elements (AREA)
- Control Of Positive-Displacement Air Blowers (AREA)
- Combines (AREA)
- Harvester Elements (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A typical embodiment of the invention provides an apparatus for indicating, to the operator of a combine, that a sieve overload or blockage has developed. The apparatus comprises wind sensors disposed within the fan air flow within the cleaning section and responsive to the flow. The apparatus further comprises a monitor circuit for detecting a low flow indicative of blockage and means responsive thereto to alert the operator.
A typical embodiment of the invention provides an apparatus for indicating, to the operator of a combine, that a sieve overload or blockage has developed. The apparatus comprises wind sensors disposed within the fan air flow within the cleaning section and responsive to the flow. The apparatus further comprises a monitor circuit for detecting a low flow indicative of blockage and means responsive thereto to alert the operator.
Description
1. Field of the Invention The present invention relates generally to mobile grain harvesting equipment and, more particularly, to combine harvesters and the like in which means for improving the efficiency of the grain separation or harvesting process is provided.
2. Description of the Prior Art A~ mobile combines are harvesting in the field, the grain is threshed and separated from the straw and stored in a storage bin within the combine for later delivery to ~nother vehicle for transport from the field. This is the most economical method for harvesting grain. In general, the harvesting process of all combines is alike, that is, the material harvested enters the conbine through a header portion and is elevated through the ele~ator housing into the threshing and separating units within the combine. The threshing and separating units receive the unthreshed crop material and generally separate the grain from the straw by means of a rubbing or beating motion. The grain and other unthresed crop material separated from the straw falls fron the threshing and separating units onto the grain handling and cleaning means while the straw is discharged from the rear of the threshing and separating units onto a beater element which expels the threshed straw through an opening in the hood of the combine.
~ he grain handling and cleaning means includes means to separate the light straw material or chaff from the grain and means to segregate the unthreshed material (known in the art as tailings) from the grain in order to collect the clean grain in a grain bin or tank located at the top of the combine.
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1 The grain handling and cleaning means is generally conventional and comprises oscillating grain pan and sieves and a fan for the separation process. The grain pan, disposed beneath the threshing and separating units, receives the threshed material therefrom and discharges the threshed material to oscillating sieves disposed rearwardly and below the grain pan. That is, the vibration or oscillation of the grain pan causes the grain and threshed material to move rearwardl~ to be discharged onto the sieves below and thus subjected to the air flow from the grain handling and cleaning fan. The fan, moreover, blows a sufficient volume of air through ~he apertures provided in the sieves to aerodynamically separate the grain from the chaff.
Accordingly, the chaff and other small trash material are suspended in the airstream and are discharged through a rear opening in the combine while the grain drops to the sieves below. The first sieve or chaffer sieve is provided with means for adjusting the apertures such that the grain received thereon may fall therethrough while the larger trash material is shaken rearwardly for discharge out of the combine. In addition, the second or clean grain sieve disposed beneath the first or chaffer si~vo includes adjustable apertures such that only the grain drops therethrough to a guide where it may be collected for elevation to the grain bin. Any larger material (generally known in the art as tailings) discharged onto the lower second sieve i9 discharged rearwardly and collected within ~he combine to be elevated and discharged into the feed section of the threshing and separating units for reprocessing of the grain attached thereto. Thus, an excellent separation or cleaning of the grain is obtained along with a separate and rapid discharge of straw, trash and chaff material from the combine.
1 In certain operating conditions, however, perhaps more often with ~ew high capacity combines wherein a large amount of short straw is produced b~ the threshing operation and in muddy conditions whereby the mud and straw combination form a coagulated mass, the short straw or coagulated straw-mud mass often overloads the cleaning and handling system. Eurthermore, if the harvesting operation is being attempted at too great a load for the cleaning means to handle, the threshed material, including the chaff and straw, overloads the cleaning and handling system. When the sieves become overloaded with chaff and trash straw material or the coagulated straw-mud mas~, separation of the grain is not performed and a short straw and chaff material mat forms on the sieves further reducing the separation process. In addition, as the mat is moved rearwardly and discharged from the combine, some of the grain entrained therein is also discharged or lost thereby raducing the economic efficiency of the machine and from a practical viewpoint reducing the over-all yi~ld of the harvest.
It has been noted that during the harvesting operation, a localized straw mat buildup on the sieves effectively causes a localized blockage of the air flow through the sieves reducing the aerodynamic separation produced by the fan.
Further, as the flow of air through the sieves is blocked, additional straw and chaff material collapse from the air-stream onto the straw mat on the sieve forming a tighter and larger mat which progressively grows along the sieve reducing grain separation and increasing grain loss through the rear of the combine. As the blockage of the sieve increases, the increasing incoming material causes the "collapsed area", that is, the area through the sieves in
~ he grain handling and cleaning means includes means to separate the light straw material or chaff from the grain and means to segregate the unthreshed material (known in the art as tailings) from the grain in order to collect the clean grain in a grain bin or tank located at the top of the combine.
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1 The grain handling and cleaning means is generally conventional and comprises oscillating grain pan and sieves and a fan for the separation process. The grain pan, disposed beneath the threshing and separating units, receives the threshed material therefrom and discharges the threshed material to oscillating sieves disposed rearwardly and below the grain pan. That is, the vibration or oscillation of the grain pan causes the grain and threshed material to move rearwardl~ to be discharged onto the sieves below and thus subjected to the air flow from the grain handling and cleaning fan. The fan, moreover, blows a sufficient volume of air through ~he apertures provided in the sieves to aerodynamically separate the grain from the chaff.
Accordingly, the chaff and other small trash material are suspended in the airstream and are discharged through a rear opening in the combine while the grain drops to the sieves below. The first sieve or chaffer sieve is provided with means for adjusting the apertures such that the grain received thereon may fall therethrough while the larger trash material is shaken rearwardly for discharge out of the combine. In addition, the second or clean grain sieve disposed beneath the first or chaffer si~vo includes adjustable apertures such that only the grain drops therethrough to a guide where it may be collected for elevation to the grain bin. Any larger material (generally known in the art as tailings) discharged onto the lower second sieve i9 discharged rearwardly and collected within ~he combine to be elevated and discharged into the feed section of the threshing and separating units for reprocessing of the grain attached thereto. Thus, an excellent separation or cleaning of the grain is obtained along with a separate and rapid discharge of straw, trash and chaff material from the combine.
1 In certain operating conditions, however, perhaps more often with ~ew high capacity combines wherein a large amount of short straw is produced b~ the threshing operation and in muddy conditions whereby the mud and straw combination form a coagulated mass, the short straw or coagulated straw-mud mass often overloads the cleaning and handling system. Eurthermore, if the harvesting operation is being attempted at too great a load for the cleaning means to handle, the threshed material, including the chaff and straw, overloads the cleaning and handling system. When the sieves become overloaded with chaff and trash straw material or the coagulated straw-mud mas~, separation of the grain is not performed and a short straw and chaff material mat forms on the sieves further reducing the separation process. In addition, as the mat is moved rearwardly and discharged from the combine, some of the grain entrained therein is also discharged or lost thereby raducing the economic efficiency of the machine and from a practical viewpoint reducing the over-all yi~ld of the harvest.
It has been noted that during the harvesting operation, a localized straw mat buildup on the sieves effectively causes a localized blockage of the air flow through the sieves reducing the aerodynamic separation produced by the fan.
Further, as the flow of air through the sieves is blocked, additional straw and chaff material collapse from the air-stream onto the straw mat on the sieve forming a tighter and larger mat which progressively grows along the sieve reducing grain separation and increasing grain loss through the rear of the combine. As the blockage of the sieve increases, the increasing incoming material causes the "collapsed area", that is, the area through the sieves in
3 ~
1 which there is no air ~low, to enlarge. In addition, the tailings returns increase dramatically addiny more material to the inconing flow. When the straw mat fills the sieve blocking the front part thereof, pure aerodynamic separation fails and the overload is complete. In ~his stage, the grain is captured in the collapsed mat and rid~s over the sieve and is discharged onto the ground.
Accordingly, there is a need tv provide means for detecting the overload buildup or a localized blockage o~ the sieves and to indicate this condition to the operator of the combine.
According to the invention, apparatus is provided for detecting and alerting tne operator of a combine harvester of a sieve overload condition or formation thereof. Illustra~ively, the apparatus of this invention comprises sensing means dis-posed within the ombine to alert the operator of a sieve blockage or overload condition.
Specifically, the apparatus of this invention comprises a monitor circuit coupled to a sensor disposed within the combine. The sensor is responsive to the air flow through the sieves and provides signals indicative of the flow therethrough and of blocked flow due to sieve blockage or overload. The monitor circuit i8 responsive to the blockage signal and provides a signal for operation of warning devices to alert the operator.
More specifically, the apparatus of this invention conprises a monitor circuit including equalizing means to balance the sensor signal and to compensate the signal for varying combine internal air temperatures. The monitor circuit , ~3~
1 further includes a threshold circuit for establishing a predetermined lower limit which if exceeded will be indicative of sieve blockage, and a detector circuit for comparing the wind sensor signals to the lower limit signals for fault or blockage detection. If the detector circuit discovers a fault, a signal is produced which activates the warning devices to alert the operator before full sieve oYerload is e~tablishedO
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantage~
and specific bbjects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevation of a combine harvester, partially in section, that embodies principles of the invention.
Figure 2 is a block diagram of the invention.
Figure 3 is a blown up view of a portion of the internals of the combine of Eigure 1 showing the preferred location of a portion of this invention.
Figures 4 through 8 are circuit diagrams of portions of the block diagram of Figure 2.
DESCRIPrION OF THE_PR$FERRED E~BODIMENT
For a more complete appreciation of the invention, attention is invited to the following description of an illustrative embodiment of the invention. In the following description, this invention is described in association with a self-propelled combine harvester as described hereinabove.
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3~
lIt is noted that the direction of travel designated by arrow A (Fig. 1) iS opposite to the direction of movement of the crop material through the combine and, as the terms grain and straw are used principally throughout the specification, it should be understood that these terms are not intended to be limiting. The term ~grain~' as used herein refers to all crop material that may be threshed by the mechanism described herein. Similarly, the term "straw" refers to all discardable crop material.
10The com~ine harvester illustrated in Figure l includes a mobile main frame or housing means 20 supported on front drive wheels 21 and rear steerable wheels 22, the wheels being traversely spaced apart on opposite sides of the fr~me.
crop elevator housing 23 and a header 24 are mounted on the front of the main housing 20 to harvest the grain crop and feed it to the threshing and separating units 26 mounted in the main housing 20. The threshing and separating units thresh and separate the grain from the crop material and discharge the grainless crop material (straw) onto a rear beater 25 for discharge from the rear of the combine, generally through a large bottom opening in the hood 27. Grain cleaning means 28 are provided within the main housing for separating the straw and chaff from the grain. An encasement 30 extends below the main frame for housing a fan 32 and the grain and tailings collecting means 34 and 36 respectively. On the top of the combine i9 an engine 38 and a grain tank 40 with a hinged unloadin~ auger, not shown. An operator~s cab 42 is mounted on the front of the housing 20 a~ove the crop ele~ator housing 23.
30As indicated hereinabove, the threshing and separating unit~ 26 separate the grain from the straw and discharge the 1 grain and other crop bearing material onto the cleaning means 28. The cleaning means 28 includes a grain pan 44 and sieves 46 which cooperate with the fan 32 to clean the grain as indicated previously~ The sieves 46, how~ver, may develop - a localized blockage thereon of straw material which prevents the cleaning means from separating the grain from the discardable material. Furthermore, this localized blocXage or overload may increase in size as more material collapses thereon effectively blocking the entire sieve 46.
In accordance with this invention, apparatus 50 (Fig. 2) ~ -is provided to indicate to the operator of the combine C that a blockage or sieve overload is developing on the sieves 46 in order that the operator may taXe effective steps to prevent sieve overload. The apparatus 50 comprises means 52 disposed in cooperation with the air flow from the fan 32 to sense the air flow, a monitor 54 coupled to the sensor means 52 and a warning device 56 coupled and responsive to the monitor to alert the operator of a localized sieve overload or mat-like development on the sieves. As indicated in Fig. 2, the monitor 54 comprises an equalizing means 58 coupled to the sensing means 52 for balance and compensation as further explained herein.
The monitor further comprises a threshold means 60 coupled to e~ualizing means 58 and a detector means 62, the detector means 62 being coupled to both the equalizing means 58 and the threshold means 60.
In the preferred embodiment of the invention, the sensor means 52 is disposed in the air flow from the fan 32 and, more specifically, in the vicinity of the rear portion of the sieves 46. Attention is invited to Fig. 3 in which is shown an isometric blow up view of the threshing and separating units 26, 1 cleaning means 28 including fan 32, grain pan 44 and sieves 46.
In this embodiment of the invention, the sieves 46 are separated into a plurality of longitudinal (with respect to the combine C) sections, for example, Sl through S6~ and the sieves Sl through S6 are separated by vertical slats as dividers 47. Within each section (Sl-S6) a wind sensor 64 (only one being shown~ of sensing means 52 is disposed in the air flow passing through the cleaning sieves 46. Furthermore, although other locations for and combinations of sensors are possible, in the preferred ~mbodiment o this invention, the wind sensors 54 are disposed longitudinally across the rear portion of the sieves 46 (~ne to each section sl-S6) as it has been found that the initial localized blockage of the sieves occurs within this rear portion thereof. The wind sensors 64 are attached to the underside of the sieve within the air flow from ~he fan 32 such that it can sense the air passing through the sieve without being disturbed by the crop material itself.
In the preferred embodiment of this invention, the wind sensor 64 comprises a D.C. powered positive temperature coeficient thermistor 64A which provides a signal indicative of the wind or air flow from the fan 32 through the sieve sections (Sl~$6) of each respective thermistor by means of the heat transfer from the thermistor. A particularly useful characteristic of a positive temperature coefficient (PTC) thermistor, as applied to this invention, is that the resistance of the PTC thermistor increases ~o rapidly at its cnaracteristic or operating temperature that the PTC thermistor seeks an e~uilibrium near that characteristic t~perature substantiall~
independent of the heat loss from the surface of the thermistor.
In a "high" wind condition or for this invention a clean s~eve, - 1 for example, the PTC thermistor maintains the characteristic operating temperature by means o~ a lower electrical resistance which draws more electrical power, balancing the heat loss.
Correspondingly, in a ~low~ wind, sieve blockage conditions, the PTC thermistor resistance increases and the higher electrical resistance reduces the electrical power to match the lower heat loss. Although the PrC thermistor temperature is slightly higher in the ~low~ wind condition, wind conditions hardly affect or change the characteristic or operating temperature due to the rapid change in resistance with temperature of the PTC
device. It is noted, moreover, that the current through the PTC
thermistor varies substantially with the wind conditions a~dat a constant supply voltage the current is proportional to the heat loss from the thermistor, as further explained herein.
Thus, it is noted that a positive temperature coefficient thermistor is a sensor which seeks a certain operating temperature or maximum temperature which substantially will not vary at different supply voltage levels or as the heat transfer therefron increases or decreases. Accordingly, a positive temperature coefficient thermistor 64A offer~ a safety feature not found in other types of self-heated heat transfer wind sensors, such as a hot-wire aneomometer. That is, as the power supplied to the sensor increases, the temperature thereof remains substantially constant at its maximum operating temperature, which may be selected in advance as a temperature su~stantially below the ignition temperature of the material within the combine, thereb~ preventing a disaster which could occur if other typ~ self-heated or heat transfer sensors were used.
In the preferred embodiment shown in Fig. 3, the sensor means 64 is attached to or mounted on the lower portion of the 1 sieve 46 through insulation means 66, such as a ~r plastic, B which effectively insulates the thermistor 64A from the sieve while securely fixing the thermistor within its respective sieve section (Sl-S6) and within the air flow.
Attention is now invited to Fig. 4 wherein the sensor means 52 is shown including a plurality of wind sensors 64, one each for each sieve 46 section Sl through S6. Each wind sensor 64 is coupled by leads a through f to the equalizing means 58.
Equalizing means 58 includes respective amplifier means 70a through 70f, for each wind sensor 64, and a temperature bias means 72. The ternperature bias means 72 includes a temperature sensor 74 disposed within the combine C, preferably within the vicinity of the cleaning means 28. The temperature sensor 74 is preferably an unheated thermistor exposed to the air ternperature within the c~mbine. The temperature sensor 74 is coupled in series with a resistor Rl and the cor~bination theEeof is coupled in parallel with a resistor R2. One terminal of sensor 74 and resistor R2 is grounded, whereas the other terminal of resistor R2 is coupled in parallel to a resistor R3 which is coupled to a D.C. supply not shown. The parallel combination o resistors Rl,R2,R3 and sensor 74 is coupled to the non-inverting terminal of an amplifier 76. The inverting terminal of amplifier 76 is coupled to the output of amplifier 76 in a voltage follower manner. The output of the amplifier 76 is coupled to the inverting terminal of each amplifier means 70a through 70f through resistor R4 for purposes explained hereinbelow.
In the preferred embod~ment of the invention, each wind sensor 64 of the ~ieve sections Sl through S6 are coupled b~ -leads a through f, respectively, to the non-inver~ing terminal ~L~3~
1 of its respective amplifier means 70a through 70f. The amplifier means for each sensor 64 (a through f) each includes the resistor R4 coupled to its inverting terminal, as explained above, a resistor R5 coupled in feedback relation from the output terminal to the inverting terminal and a capacitor Cl also coupled in feedback relation from the output terminal to the inverting terminal. In addition, the amplifier means of 70a through 70f includes a variable resistor R6 series coupled to resistor R5.
Thç respective amplifier means for each sensor 64 (a through f) -each includes a resistor R2a through R2~, respectively, having one terminal coupled to the non-inverting terminal of the respective amplifier means 70a through 70f and the other terminal coupled to ground. As explained hereinabove, at a constant supply voltage, the PTC thermistor current is proportional to the heat loss from the thermistor. Accordingly, the respective thermistor signal of sensors 64 (a through f) coupled to respective amplifier means is directly responsive to the th~rmistor current flowing through respective resistors R2a through R2f. The output lead of each respective amplifier means is labelled h through m respectively.
The output of the equalizer 58 is coupled to threshold means 60 and more specifically the respective outputs h through m are coupled to a maximum signal circuit 80 Fig. S. The maximum signal circuit 80 includes respective amplifier and diode combination 82h through 82m having the diode output coupled together and the combination coupled to the inverting terminal of the amplifier and ground such that the output of the combination represents the output from a perfect diode. The non-inverting terminal of the respective amplifiers is coupled to the output of respective amplifier means and, accordingly, the output signal from each ~3~
1 individual wind sensor 64 of this preferred embodiment of the invention i5 couplsd through its respective amplifier means 70a through 70f to a respective amplifier-diode combination 80h through 80m via its respective lead (h through m), Figures 4 and 5.
The output of the maximum signal circuit 80 is coupled through a resistor R7 to a circuit 84, which includes a resistor R8 and an amplifier 86 connected as a voltage follower, hav~g an output lead n. One terminal of the resistor R8 is coupled to a terminal of resistor R7 and the non-inverting terminal of the amplifier 86, the other terminal of resistor R8 is coupled to ground such that resistors R7 and R8 are coupled in a common voltage divider manner.
Attention is now invited to Fig. 6 wherein the detector means 62 is shown having input leads h through m coupled to corresponding leads (h through ~) of equalizer 58 and an input lead n coupled to the output of threshold means 60 or more specifically output lead n of the circuit 84. The detector means 62 comprises a comparator circuit 88 and, as shown in this preferred embodiment of the invention, a comparator circuit 88h through 88m for each input lead h through m, i.e., for each respective wind sensor 64. Each respective comparator circuit 88 comprises an amplifier 90h through m each having its inverting te~ninal coupled to the respective input l~ad (h through m) of equalizer 58 and its non-inverting terminal coupled to the input lead n from the limiter circuit 84 through a resistor Rg. The output of each respective amplifier is coupled through a resistor Rlo to the non-inverting terminal.
The respective outputs o through t of amplifiers 90h through 90m of the comparator circuit 88 are coupled to the warning means 56, as explained hereinbelow.
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1 The warning means 56 (Fig. 7) comprises switch means 92 responsive to the output from the detector 62. The switch means 92 comprises respective transistors 940 through 94t, one for each wind sensor 64 for each sieve location S1 through S6 having its base electrode coupled through a resistor R11 to the respective input lead (o through t~ from the comparator circuits 88. The warning means 56 further comprises a signalling device, such as a plurality of light emitting diodes 960 through 96t coupled to a direct current power supply D.C. not shown and to the respective collector terminals of the transis~ors 940 through 94t via a resistor Rl~. The emitter terminal of the respective transistors is coupled to ground through a switch 98.
In this preferred embodiment of the invention, the warning means ~6 further comprises a counter 100 which in this embodiment of the invention is an analog type counter responsive to the output leads o through t from detector 62 and an alarm device 101 which may be a light, a bell or horn or both coupled to a power supply not shown. The alarm device is also coupled to the counter 100 through a switch 102 and to ground through the switch 98.
In operation, the apparatus of this invention provides a warning signal to the operator of the combine of a sieve blockage or overload development, as described hereinbelow, although it is apparent that the apparatu8 of this invention could also provide in the alternative a signal to the fan 32 or ~.:
other means within the combine to remove the blockage. In operation, the respective wind sensors 64, in particular, the positive temperature coefficient thermistors 64A are provided with power which heats the thermistor to a preselected operating temperature substantially below the flash temperature of.the - -1 crop and straw material within the combine. The sensors 64 provide a signal, responsive to the heat transfer therefrom, as explained hereinabove, to the individual respective amplifiers 70a through 70f within the equalizer 58. In addition, the ambi~nt temperature within the combine is sensed by the unheated thermistor sensor 74 of the temperature bias means 72, which provides a temperature bias signal Q to the inverting terminal of the amplifier 70. This temperature bias signal or offset voltage provides a ~emperature signal to the respective amplifiers which compensates ~he heat transfer signal from the respective thermi8tors for the ambient temperature within the combine and, , . .. .
therefore, the signal from each wind sensor 64 is independent of the 1mbient temperature within the combine. Further, this offset signal Q is such that although the heated wind sensors will produce a signal even when there is no wind or air flow in a shutdown condition for example, the output signal from the respective amplifiers on leads h through m will go to zero.
In this embodiment of the invention, the signal Q has the form:
/ 105 - T \
Q = Q ~ A J
where Q20 is the value of Q at 20C, TA is the temperature of the air in the combine in degrees ce~trigrade (C), and 105 and 85 are temperature values in (C), and which is merely a corrected temperature signal, as a function of the combine air temperature.
It is noted that the convective heat transfer from or to a fluid to or from a heat transfer sensor is a function of the temperature and the fluid flow. As the sensor temperature signal has been compensated by the temperature bias signal or offset signal Q, the outp~t from the respective amplifiers is a function of the fluid flow, and in particular, the square root of the wind speed.
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1 As there are six sieve locations Sl through S6 in this preferred embodiment each having a respective wind sensor 64 producing an output on leads a through f, respectively, each amplifier 70a through 70f may produce different initial signals.
Accordingly, balancing means, i.e., the variable resistors R6 previously mentioned in connection with amplifiers 70b through 70f are adjusted to balance ~he output signal from these respective amplifiers to the output signal of amplifier 70a.
It is app~rent that this operation may be performed by any standard or general electrical balancing or comparison technique.
Upon completion of the balancing of the respective individual signals from the plurality of amplifier-sensor c~mbinations to one particular amplifier-sensor combination, the output from all of the amplifier sensors will be insensitive to uni~orm disturbances, such as changes in combine fan, wind speed, as well as to changes in combine air temperature, as previously indicated.
The output signals from the respective amplifiers 70a through 70f are coupled via respective leads h through m to the maximum signal circuit 80, or to the respective amplifier-diode com-binations 82h through 82m such that the maximum output signal from leads h through m is coupled to the circuit 84. ~lthough it is noted that initially the amplifiers 70a through 70f are balanced to provide uniform signals, in the event that a blockage occurs locally in the sieves 46, the respective wind sensor 64 -~
associated with that location will detect that blockage and provide a reduced signal.
The output signal from the maximum signal circuit 80 is coupled through resistors R7 and R8 in a voltage divider fashion preselected to produce a preselected output signal magnitude -- . ., .. . . . - - ..
p~
1 fron amplifier 86 of circuit 84. Thls preselected signal magnitude represents the lower limit signal, based on the minimum wind speed, which the apparatus will sense without setting off the alarm. For example, in t~e preferred embodiment shown herein, t~e voltage divider resistors R7 and R~ were pre-selected to produce an outpu~ signal P from amplifier 86 equal to 0.633 times the maximum signal G of circuit 80. This signal P - 0.633G, it is noted, is substantially equivalent to a 60%
loss in wind speed as measured by wind sensors 64 as the signal thereof is a function of the square root of wind speed.
The output signals from respecti~e amplifiers 70a through 70f and amplifier 86 are coupled to the detector 62, i.e., to respectivs comparator circuits 88h through m,as previously explained, wherein the wind sensor signals are each compared to the lower ~imit signal P (0.633G) by the respective comparator circuits. The output signal from the respective comparator ~-circuits are each coupled to the warning m~ans 56 for alerting the operator if the lo~er limit signal is greater than the wind sen~or signal.
For example, assume that a localized sieve blockage has occurred at the sieve location associated with wind sensor 64 coupled to lead f. Accordinqly, as the output of the respective ampliier 70f associated therewith is a function of the s~uare root o the wind speed, the output signal thereof will be reduced from ~he signals associated ~ith the amplifier-sensor combinations not so blocked. Thus, if the output signal of the blocked amplifier-sensor of lead f is 0.5 that of the remaining amplifier-sensor signals G, the following occurs. The maximum signal circuit 80 and limiter circuit 84 produce a predetermined signal of 0.633G. The detector circuit 62 compares each - ~ , , ', ~
1 respective input signal from the respective amplifiers 70a through 70f with the lower limit signal of lead n to detect a faul~, i.e., a blockage. As the signals from the wind sensors 64 on leads a tl~ough e are all approximately equal to G, these signals when compared to the lower limit signal 0.633G
are greater than the lower limit and a ~Ow output or negative polarit~ output signal is produced by the comparator circuits 88h through 8 ~ and is coupled to leads o through s. The low or negative polarity output signals reverse biases the respective transistors 940 through 94s preventing conductio~. As there is no conduction through the transistors, the respective light emitting diodes 960 thxough 96s do not illuminate, as there is no blockage in their respective sieve sections to which the operator should be alerted. However, as the signal from lead f of a blocked sieve section is assumed equal to 0.5G (for this illustration), the comparator circuit 88m associated therewith through lead m will produce a HIG~ or positive polarity signal when compared to the lower limit siynal 0.633G. $he HIGH or positive polarity signal from t~e comparator 88 is coupled via lead t to the respective traasistor 94t coupled therewith. The HIGH signal forward biases the transistor allowing it to conduct, thereby causing the respective lisht emitting diode to illumin~te and warn the operator of a sieve blockage at that res~ective sieve location in order that appropriate action may be taken.
Thus, the sensing means is used to detect the airstream gradient a~ the sieves.
In addition, if one particular sieve location is not significant enough to alert the operator to pursue appropriate action, a counter 100 coupled to the comparator circuits via respective leads o through t may count the number of sieve _17-~ .
- - :
1 locations which are blocked as determined by theoutput signals on leads o through t and a~ap].y an appropriate signal when the preselected number of blocked sieves is established. The signal from the counter merely turns ~ON~ the switch 102 allowing the alarm 101 to respond to aler~ the opera~or. Switch 98, moreover, prevents the a~rm from working at the low wind speeds which would occur when the fan is not operating.
Attention is invited to Fig. 8 in which the threshold means 60 includes an average signal circuit 110 conprising input loads h through m from the respective output of amplifiers 70a through 70f coupled through respective resistors R13 to the non-inverting te~minal of an amplifier 112 coupled as a voltage follower, for providing a signal M based on the average of the input signals ~rom the respective wind sensors. In this embodiment, the voltage divider resistors R7 and ~8 and amplifier 86 of circuit 84 produce a preselected output signal of .707M. This output signal is equivalent to a 50% reduction .
or loss in wind speed.
In accordance with this invention, apparatus for sensing ` 20 the blockage of the sieves and alerting the opePat~r is provided.
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1 which there is no air ~low, to enlarge. In addition, the tailings returns increase dramatically addiny more material to the inconing flow. When the straw mat fills the sieve blocking the front part thereof, pure aerodynamic separation fails and the overload is complete. In ~his stage, the grain is captured in the collapsed mat and rid~s over the sieve and is discharged onto the ground.
Accordingly, there is a need tv provide means for detecting the overload buildup or a localized blockage o~ the sieves and to indicate this condition to the operator of the combine.
According to the invention, apparatus is provided for detecting and alerting tne operator of a combine harvester of a sieve overload condition or formation thereof. Illustra~ively, the apparatus of this invention comprises sensing means dis-posed within the ombine to alert the operator of a sieve blockage or overload condition.
Specifically, the apparatus of this invention comprises a monitor circuit coupled to a sensor disposed within the combine. The sensor is responsive to the air flow through the sieves and provides signals indicative of the flow therethrough and of blocked flow due to sieve blockage or overload. The monitor circuit i8 responsive to the blockage signal and provides a signal for operation of warning devices to alert the operator.
More specifically, the apparatus of this invention conprises a monitor circuit including equalizing means to balance the sensor signal and to compensate the signal for varying combine internal air temperatures. The monitor circuit , ~3~
1 further includes a threshold circuit for establishing a predetermined lower limit which if exceeded will be indicative of sieve blockage, and a detector circuit for comparing the wind sensor signals to the lower limit signals for fault or blockage detection. If the detector circuit discovers a fault, a signal is produced which activates the warning devices to alert the operator before full sieve oYerload is e~tablishedO
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantage~
and specific bbjects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevation of a combine harvester, partially in section, that embodies principles of the invention.
Figure 2 is a block diagram of the invention.
Figure 3 is a blown up view of a portion of the internals of the combine of Eigure 1 showing the preferred location of a portion of this invention.
Figures 4 through 8 are circuit diagrams of portions of the block diagram of Figure 2.
DESCRIPrION OF THE_PR$FERRED E~BODIMENT
For a more complete appreciation of the invention, attention is invited to the following description of an illustrative embodiment of the invention. In the following description, this invention is described in association with a self-propelled combine harvester as described hereinabove.
- .
3~
lIt is noted that the direction of travel designated by arrow A (Fig. 1) iS opposite to the direction of movement of the crop material through the combine and, as the terms grain and straw are used principally throughout the specification, it should be understood that these terms are not intended to be limiting. The term ~grain~' as used herein refers to all crop material that may be threshed by the mechanism described herein. Similarly, the term "straw" refers to all discardable crop material.
10The com~ine harvester illustrated in Figure l includes a mobile main frame or housing means 20 supported on front drive wheels 21 and rear steerable wheels 22, the wheels being traversely spaced apart on opposite sides of the fr~me.
crop elevator housing 23 and a header 24 are mounted on the front of the main housing 20 to harvest the grain crop and feed it to the threshing and separating units 26 mounted in the main housing 20. The threshing and separating units thresh and separate the grain from the crop material and discharge the grainless crop material (straw) onto a rear beater 25 for discharge from the rear of the combine, generally through a large bottom opening in the hood 27. Grain cleaning means 28 are provided within the main housing for separating the straw and chaff from the grain. An encasement 30 extends below the main frame for housing a fan 32 and the grain and tailings collecting means 34 and 36 respectively. On the top of the combine i9 an engine 38 and a grain tank 40 with a hinged unloadin~ auger, not shown. An operator~s cab 42 is mounted on the front of the housing 20 a~ove the crop ele~ator housing 23.
30As indicated hereinabove, the threshing and separating unit~ 26 separate the grain from the straw and discharge the 1 grain and other crop bearing material onto the cleaning means 28. The cleaning means 28 includes a grain pan 44 and sieves 46 which cooperate with the fan 32 to clean the grain as indicated previously~ The sieves 46, how~ver, may develop - a localized blockage thereon of straw material which prevents the cleaning means from separating the grain from the discardable material. Furthermore, this localized blocXage or overload may increase in size as more material collapses thereon effectively blocking the entire sieve 46.
In accordance with this invention, apparatus 50 (Fig. 2) ~ -is provided to indicate to the operator of the combine C that a blockage or sieve overload is developing on the sieves 46 in order that the operator may taXe effective steps to prevent sieve overload. The apparatus 50 comprises means 52 disposed in cooperation with the air flow from the fan 32 to sense the air flow, a monitor 54 coupled to the sensor means 52 and a warning device 56 coupled and responsive to the monitor to alert the operator of a localized sieve overload or mat-like development on the sieves. As indicated in Fig. 2, the monitor 54 comprises an equalizing means 58 coupled to the sensing means 52 for balance and compensation as further explained herein.
The monitor further comprises a threshold means 60 coupled to e~ualizing means 58 and a detector means 62, the detector means 62 being coupled to both the equalizing means 58 and the threshold means 60.
In the preferred embodiment of the invention, the sensor means 52 is disposed in the air flow from the fan 32 and, more specifically, in the vicinity of the rear portion of the sieves 46. Attention is invited to Fig. 3 in which is shown an isometric blow up view of the threshing and separating units 26, 1 cleaning means 28 including fan 32, grain pan 44 and sieves 46.
In this embodiment of the invention, the sieves 46 are separated into a plurality of longitudinal (with respect to the combine C) sections, for example, Sl through S6~ and the sieves Sl through S6 are separated by vertical slats as dividers 47. Within each section (Sl-S6) a wind sensor 64 (only one being shown~ of sensing means 52 is disposed in the air flow passing through the cleaning sieves 46. Furthermore, although other locations for and combinations of sensors are possible, in the preferred ~mbodiment o this invention, the wind sensors 54 are disposed longitudinally across the rear portion of the sieves 46 (~ne to each section sl-S6) as it has been found that the initial localized blockage of the sieves occurs within this rear portion thereof. The wind sensors 64 are attached to the underside of the sieve within the air flow from ~he fan 32 such that it can sense the air passing through the sieve without being disturbed by the crop material itself.
In the preferred embodiment of this invention, the wind sensor 64 comprises a D.C. powered positive temperature coeficient thermistor 64A which provides a signal indicative of the wind or air flow from the fan 32 through the sieve sections (Sl~$6) of each respective thermistor by means of the heat transfer from the thermistor. A particularly useful characteristic of a positive temperature coefficient (PTC) thermistor, as applied to this invention, is that the resistance of the PTC thermistor increases ~o rapidly at its cnaracteristic or operating temperature that the PTC thermistor seeks an e~uilibrium near that characteristic t~perature substantiall~
independent of the heat loss from the surface of the thermistor.
In a "high" wind condition or for this invention a clean s~eve, - 1 for example, the PTC thermistor maintains the characteristic operating temperature by means o~ a lower electrical resistance which draws more electrical power, balancing the heat loss.
Correspondingly, in a ~low~ wind, sieve blockage conditions, the PTC thermistor resistance increases and the higher electrical resistance reduces the electrical power to match the lower heat loss. Although the PrC thermistor temperature is slightly higher in the ~low~ wind condition, wind conditions hardly affect or change the characteristic or operating temperature due to the rapid change in resistance with temperature of the PTC
device. It is noted, moreover, that the current through the PTC
thermistor varies substantially with the wind conditions a~dat a constant supply voltage the current is proportional to the heat loss from the thermistor, as further explained herein.
Thus, it is noted that a positive temperature coefficient thermistor is a sensor which seeks a certain operating temperature or maximum temperature which substantially will not vary at different supply voltage levels or as the heat transfer therefron increases or decreases. Accordingly, a positive temperature coefficient thermistor 64A offer~ a safety feature not found in other types of self-heated heat transfer wind sensors, such as a hot-wire aneomometer. That is, as the power supplied to the sensor increases, the temperature thereof remains substantially constant at its maximum operating temperature, which may be selected in advance as a temperature su~stantially below the ignition temperature of the material within the combine, thereb~ preventing a disaster which could occur if other typ~ self-heated or heat transfer sensors were used.
In the preferred embodiment shown in Fig. 3, the sensor means 64 is attached to or mounted on the lower portion of the 1 sieve 46 through insulation means 66, such as a ~r plastic, B which effectively insulates the thermistor 64A from the sieve while securely fixing the thermistor within its respective sieve section (Sl-S6) and within the air flow.
Attention is now invited to Fig. 4 wherein the sensor means 52 is shown including a plurality of wind sensors 64, one each for each sieve 46 section Sl through S6. Each wind sensor 64 is coupled by leads a through f to the equalizing means 58.
Equalizing means 58 includes respective amplifier means 70a through 70f, for each wind sensor 64, and a temperature bias means 72. The ternperature bias means 72 includes a temperature sensor 74 disposed within the combine C, preferably within the vicinity of the cleaning means 28. The temperature sensor 74 is preferably an unheated thermistor exposed to the air ternperature within the c~mbine. The temperature sensor 74 is coupled in series with a resistor Rl and the cor~bination theEeof is coupled in parallel with a resistor R2. One terminal of sensor 74 and resistor R2 is grounded, whereas the other terminal of resistor R2 is coupled in parallel to a resistor R3 which is coupled to a D.C. supply not shown. The parallel combination o resistors Rl,R2,R3 and sensor 74 is coupled to the non-inverting terminal of an amplifier 76. The inverting terminal of amplifier 76 is coupled to the output of amplifier 76 in a voltage follower manner. The output of the amplifier 76 is coupled to the inverting terminal of each amplifier means 70a through 70f through resistor R4 for purposes explained hereinbelow.
In the preferred embod~ment of the invention, each wind sensor 64 of the ~ieve sections Sl through S6 are coupled b~ -leads a through f, respectively, to the non-inver~ing terminal ~L~3~
1 of its respective amplifier means 70a through 70f. The amplifier means for each sensor 64 (a through f) each includes the resistor R4 coupled to its inverting terminal, as explained above, a resistor R5 coupled in feedback relation from the output terminal to the inverting terminal and a capacitor Cl also coupled in feedback relation from the output terminal to the inverting terminal. In addition, the amplifier means of 70a through 70f includes a variable resistor R6 series coupled to resistor R5.
Thç respective amplifier means for each sensor 64 (a through f) -each includes a resistor R2a through R2~, respectively, having one terminal coupled to the non-inverting terminal of the respective amplifier means 70a through 70f and the other terminal coupled to ground. As explained hereinabove, at a constant supply voltage, the PTC thermistor current is proportional to the heat loss from the thermistor. Accordingly, the respective thermistor signal of sensors 64 (a through f) coupled to respective amplifier means is directly responsive to the th~rmistor current flowing through respective resistors R2a through R2f. The output lead of each respective amplifier means is labelled h through m respectively.
The output of the equalizer 58 is coupled to threshold means 60 and more specifically the respective outputs h through m are coupled to a maximum signal circuit 80 Fig. S. The maximum signal circuit 80 includes respective amplifier and diode combination 82h through 82m having the diode output coupled together and the combination coupled to the inverting terminal of the amplifier and ground such that the output of the combination represents the output from a perfect diode. The non-inverting terminal of the respective amplifiers is coupled to the output of respective amplifier means and, accordingly, the output signal from each ~3~
1 individual wind sensor 64 of this preferred embodiment of the invention i5 couplsd through its respective amplifier means 70a through 70f to a respective amplifier-diode combination 80h through 80m via its respective lead (h through m), Figures 4 and 5.
The output of the maximum signal circuit 80 is coupled through a resistor R7 to a circuit 84, which includes a resistor R8 and an amplifier 86 connected as a voltage follower, hav~g an output lead n. One terminal of the resistor R8 is coupled to a terminal of resistor R7 and the non-inverting terminal of the amplifier 86, the other terminal of resistor R8 is coupled to ground such that resistors R7 and R8 are coupled in a common voltage divider manner.
Attention is now invited to Fig. 6 wherein the detector means 62 is shown having input leads h through m coupled to corresponding leads (h through ~) of equalizer 58 and an input lead n coupled to the output of threshold means 60 or more specifically output lead n of the circuit 84. The detector means 62 comprises a comparator circuit 88 and, as shown in this preferred embodiment of the invention, a comparator circuit 88h through 88m for each input lead h through m, i.e., for each respective wind sensor 64. Each respective comparator circuit 88 comprises an amplifier 90h through m each having its inverting te~ninal coupled to the respective input l~ad (h through m) of equalizer 58 and its non-inverting terminal coupled to the input lead n from the limiter circuit 84 through a resistor Rg. The output of each respective amplifier is coupled through a resistor Rlo to the non-inverting terminal.
The respective outputs o through t of amplifiers 90h through 90m of the comparator circuit 88 are coupled to the warning means 56, as explained hereinbelow.
.
1 The warning means 56 (Fig. 7) comprises switch means 92 responsive to the output from the detector 62. The switch means 92 comprises respective transistors 940 through 94t, one for each wind sensor 64 for each sieve location S1 through S6 having its base electrode coupled through a resistor R11 to the respective input lead (o through t~ from the comparator circuits 88. The warning means 56 further comprises a signalling device, such as a plurality of light emitting diodes 960 through 96t coupled to a direct current power supply D.C. not shown and to the respective collector terminals of the transis~ors 940 through 94t via a resistor Rl~. The emitter terminal of the respective transistors is coupled to ground through a switch 98.
In this preferred embodiment of the invention, the warning means ~6 further comprises a counter 100 which in this embodiment of the invention is an analog type counter responsive to the output leads o through t from detector 62 and an alarm device 101 which may be a light, a bell or horn or both coupled to a power supply not shown. The alarm device is also coupled to the counter 100 through a switch 102 and to ground through the switch 98.
In operation, the apparatus of this invention provides a warning signal to the operator of the combine of a sieve blockage or overload development, as described hereinbelow, although it is apparent that the apparatu8 of this invention could also provide in the alternative a signal to the fan 32 or ~.:
other means within the combine to remove the blockage. In operation, the respective wind sensors 64, in particular, the positive temperature coefficient thermistors 64A are provided with power which heats the thermistor to a preselected operating temperature substantially below the flash temperature of.the - -1 crop and straw material within the combine. The sensors 64 provide a signal, responsive to the heat transfer therefrom, as explained hereinabove, to the individual respective amplifiers 70a through 70f within the equalizer 58. In addition, the ambi~nt temperature within the combine is sensed by the unheated thermistor sensor 74 of the temperature bias means 72, which provides a temperature bias signal Q to the inverting terminal of the amplifier 70. This temperature bias signal or offset voltage provides a ~emperature signal to the respective amplifiers which compensates ~he heat transfer signal from the respective thermi8tors for the ambient temperature within the combine and, , . .. .
therefore, the signal from each wind sensor 64 is independent of the 1mbient temperature within the combine. Further, this offset signal Q is such that although the heated wind sensors will produce a signal even when there is no wind or air flow in a shutdown condition for example, the output signal from the respective amplifiers on leads h through m will go to zero.
In this embodiment of the invention, the signal Q has the form:
/ 105 - T \
Q = Q ~ A J
where Q20 is the value of Q at 20C, TA is the temperature of the air in the combine in degrees ce~trigrade (C), and 105 and 85 are temperature values in (C), and which is merely a corrected temperature signal, as a function of the combine air temperature.
It is noted that the convective heat transfer from or to a fluid to or from a heat transfer sensor is a function of the temperature and the fluid flow. As the sensor temperature signal has been compensated by the temperature bias signal or offset signal Q, the outp~t from the respective amplifiers is a function of the fluid flow, and in particular, the square root of the wind speed.
3~
1 As there are six sieve locations Sl through S6 in this preferred embodiment each having a respective wind sensor 64 producing an output on leads a through f, respectively, each amplifier 70a through 70f may produce different initial signals.
Accordingly, balancing means, i.e., the variable resistors R6 previously mentioned in connection with amplifiers 70b through 70f are adjusted to balance ~he output signal from these respective amplifiers to the output signal of amplifier 70a.
It is app~rent that this operation may be performed by any standard or general electrical balancing or comparison technique.
Upon completion of the balancing of the respective individual signals from the plurality of amplifier-sensor c~mbinations to one particular amplifier-sensor combination, the output from all of the amplifier sensors will be insensitive to uni~orm disturbances, such as changes in combine fan, wind speed, as well as to changes in combine air temperature, as previously indicated.
The output signals from the respective amplifiers 70a through 70f are coupled via respective leads h through m to the maximum signal circuit 80, or to the respective amplifier-diode com-binations 82h through 82m such that the maximum output signal from leads h through m is coupled to the circuit 84. ~lthough it is noted that initially the amplifiers 70a through 70f are balanced to provide uniform signals, in the event that a blockage occurs locally in the sieves 46, the respective wind sensor 64 -~
associated with that location will detect that blockage and provide a reduced signal.
The output signal from the maximum signal circuit 80 is coupled through resistors R7 and R8 in a voltage divider fashion preselected to produce a preselected output signal magnitude -- . ., .. . . . - - ..
p~
1 fron amplifier 86 of circuit 84. Thls preselected signal magnitude represents the lower limit signal, based on the minimum wind speed, which the apparatus will sense without setting off the alarm. For example, in t~e preferred embodiment shown herein, t~e voltage divider resistors R7 and R~ were pre-selected to produce an outpu~ signal P from amplifier 86 equal to 0.633 times the maximum signal G of circuit 80. This signal P - 0.633G, it is noted, is substantially equivalent to a 60%
loss in wind speed as measured by wind sensors 64 as the signal thereof is a function of the square root of wind speed.
The output signals from respecti~e amplifiers 70a through 70f and amplifier 86 are coupled to the detector 62, i.e., to respectivs comparator circuits 88h through m,as previously explained, wherein the wind sensor signals are each compared to the lower ~imit signal P (0.633G) by the respective comparator circuits. The output signal from the respective comparator ~-circuits are each coupled to the warning m~ans 56 for alerting the operator if the lo~er limit signal is greater than the wind sen~or signal.
For example, assume that a localized sieve blockage has occurred at the sieve location associated with wind sensor 64 coupled to lead f. Accordinqly, as the output of the respective ampliier 70f associated therewith is a function of the s~uare root o the wind speed, the output signal thereof will be reduced from ~he signals associated ~ith the amplifier-sensor combinations not so blocked. Thus, if the output signal of the blocked amplifier-sensor of lead f is 0.5 that of the remaining amplifier-sensor signals G, the following occurs. The maximum signal circuit 80 and limiter circuit 84 produce a predetermined signal of 0.633G. The detector circuit 62 compares each - ~ , , ', ~
1 respective input signal from the respective amplifiers 70a through 70f with the lower limit signal of lead n to detect a faul~, i.e., a blockage. As the signals from the wind sensors 64 on leads a tl~ough e are all approximately equal to G, these signals when compared to the lower limit signal 0.633G
are greater than the lower limit and a ~Ow output or negative polarit~ output signal is produced by the comparator circuits 88h through 8 ~ and is coupled to leads o through s. The low or negative polarity output signals reverse biases the respective transistors 940 through 94s preventing conductio~. As there is no conduction through the transistors, the respective light emitting diodes 960 thxough 96s do not illuminate, as there is no blockage in their respective sieve sections to which the operator should be alerted. However, as the signal from lead f of a blocked sieve section is assumed equal to 0.5G (for this illustration), the comparator circuit 88m associated therewith through lead m will produce a HIG~ or positive polarity signal when compared to the lower limit siynal 0.633G. $he HIGH or positive polarity signal from t~e comparator 88 is coupled via lead t to the respective traasistor 94t coupled therewith. The HIGH signal forward biases the transistor allowing it to conduct, thereby causing the respective lisht emitting diode to illumin~te and warn the operator of a sieve blockage at that res~ective sieve location in order that appropriate action may be taken.
Thus, the sensing means is used to detect the airstream gradient a~ the sieves.
In addition, if one particular sieve location is not significant enough to alert the operator to pursue appropriate action, a counter 100 coupled to the comparator circuits via respective leads o through t may count the number of sieve _17-~ .
- - :
1 locations which are blocked as determined by theoutput signals on leads o through t and a~ap].y an appropriate signal when the preselected number of blocked sieves is established. The signal from the counter merely turns ~ON~ the switch 102 allowing the alarm 101 to respond to aler~ the opera~or. Switch 98, moreover, prevents the a~rm from working at the low wind speeds which would occur when the fan is not operating.
Attention is invited to Fig. 8 in which the threshold means 60 includes an average signal circuit 110 conprising input loads h through m from the respective output of amplifiers 70a through 70f coupled through respective resistors R13 to the non-inverting te~minal of an amplifier 112 coupled as a voltage follower, for providing a signal M based on the average of the input signals ~rom the respective wind sensors. In this embodiment, the voltage divider resistors R7 and ~8 and amplifier 86 of circuit 84 produce a preselected output signal of .707M. This output signal is equivalent to a 50% reduction .
or loss in wind speed.
In accordance with this invention, apparatus for sensing ` 20 the blockage of the sieves and alerting the opePat~r is provided.
_1~
Claims (10)
1. In a combine harvester having grain cleaning means and fan means providing an air flow through the cleaning means apparatus for indicating blockage of the cleaning means comprising: means adapted to detect the air flow for providing a plurality of first signals responsive thereto, monitor means responsive to the difference between the first signals and a predetermined signal for providing a plurality of second signals, and warning means responsive to the polarity of said second signals.
2. In a combine harvester having grain cleaning means and fan means providing an air flow through the cleaning means apparatus for indicating blockage of the cleaning means comprising: means adapted to detect the air flow for providing a first signal responsive thereto, monitor means responsive to the first signal for providing a second signal when the difference between the first signal and a predetermined signal assumes a predetermined polarity, and warning means responsive to the second signal.
3. Apparatus according to claim 1 wherein the monitor means includes threshold means for providing a predetermined signal representative of the acceptable lower limit signal of the plurality of first signals, and detector means responsive to said plurality of first signals and said predetermined signal for providing said plurality of second signals.
4. Apparatus according to claim 3 wherein the threshold means includes means responsive to the maximum signal of the plurality of first signals and voltage divider means coupled thereto for providing the predetermined lower limit signal of the maximum signal.
5. Apparatus according to Claim 4 wherein said detector means includes a respective plurality of comparison circuits each coupled to the predetermined signal and respectively coupled to the plurality of first signals for providing a respective plurality of second signals to the warning means.
6. Apparatus according to Claim 5 wherein the monitor means further includes an equalizer for balancing said plurality of first signals to the output signal of an unheated thermistor disposed within the combine harvester.
7. Apparatus according to Claim 6 wherein said equalizer further includes means for biasing said plurality of first signals to the temperature within the combine.
8. Apparatus according to Claim 7 wherein said means adapted to detect the air flow is a respective plurality of positive temperature coefficient thermistors.
9. Apparatus according to Claim 8 wherein said warning means includes a respective plurality of switch means responsive to the polarity of the respective plurality of second signals and blockage indicating means responsive thereto.
10. Apparatus according to Claim 9 further including a respective plurality of light emitting diodes responsive to the respective plurality of switch means, for indicating a local blockage, and counter means responsive to the polarity of the plurality of second signals for activating an alarm when a predetermined plurality of second signals are of a preselected polarity.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US88409878A | 1978-03-06 | 1978-03-06 | |
| US884,098 | 1978-03-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1113581A true CA1113581A (en) | 1981-12-01 |
Family
ID=25383947
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA318,119A Expired CA1113581A (en) | 1978-03-06 | 1978-12-18 | Sieve overload sensor |
Country Status (6)
| Country | Link |
|---|---|
| BR (1) | BR7901274A (en) |
| CA (1) | CA1113581A (en) |
| DE (1) | DE2908635A1 (en) |
| FR (1) | FR2419008A1 (en) |
| GB (1) | GB2015854B (en) |
| IT (1) | IT1202899B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110249780A (en) * | 2019-05-22 | 2019-09-20 | 江苏大学 | A kind of sorting screen surface material state monitoring system and control method and combine harvester |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2416636A1 (en) * | 1978-02-08 | 1979-09-07 | Sperry Rand Nv | HARVESTER |
| US4230130A (en) * | 1979-02-05 | 1980-10-28 | International Harvester Company | Combine grain loss sensing |
| US4360998A (en) * | 1981-03-27 | 1982-11-30 | Sperry Corporation | Absolute grain loss monitor |
| JP3037794B2 (en) * | 1991-09-25 | 2000-05-08 | 本田技研工業株式会社 | Glass harvester full detection device for reapers |
| US7354341B1 (en) * | 2007-03-29 | 2008-04-08 | Cnh America Llc | System and method for detecting an air flow condition indicative of plugging of a discharge apparatus of an agricultural combine |
| US9526211B2 (en) | 2014-02-28 | 2016-12-27 | Cnh Industrial America Llc | System and method of controlling airflow characteristics in an agricultural harvester |
| GB201820875D0 (en) * | 2018-12-20 | 2019-02-06 | Agco Int Gmbh | Grain cleaning system and method of controlling such |
| DE102022120634A1 (en) * | 2022-08-16 | 2024-02-22 | Claas Selbstfahrende Erntemaschinen Gmbh | Self-propelled combine harvester with a sensor system for detecting grain loss |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3345626A (en) * | 1964-12-24 | 1967-10-03 | Junior W Thomas | Combine photoelectric warning system |
| US3583405A (en) * | 1969-04-29 | 1971-06-08 | Deere & Co | Harvester shaft speed monitoring system |
| US4068223A (en) * | 1975-07-10 | 1978-01-10 | Dickey-John Corporation | Monitor system for agricultural harvesting apparatus |
| US4004289A (en) * | 1975-12-17 | 1977-01-18 | Canadian Patents And Development Limited | Acoustic grain flow rate monitor |
| US4056817A (en) * | 1976-11-22 | 1977-11-01 | Dickey-John Corporation | System for monitoring a periodic function |
| FR2416636A1 (en) * | 1978-02-08 | 1979-09-07 | Sperry Rand Nv | HARVESTER |
-
1978
- 1978-12-18 CA CA318,119A patent/CA1113581A/en not_active Expired
-
1979
- 1979-02-05 GB GB7903932A patent/GB2015854B/en not_active Expired
- 1979-02-23 FR FR7904641A patent/FR2419008A1/en active Granted
- 1979-03-01 IT IT20673/79A patent/IT1202899B/en active
- 1979-03-02 BR BR7901274A patent/BR7901274A/en unknown
- 1979-03-06 DE DE19792908635 patent/DE2908635A1/en active Granted
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110249780A (en) * | 2019-05-22 | 2019-09-20 | 江苏大学 | A kind of sorting screen surface material state monitoring system and control method and combine harvester |
| CN110249780B (en) * | 2019-05-22 | 2021-11-23 | 江苏大学 | Cleaning sieve surface material state monitoring system, control method and combine harvester |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2419008A1 (en) | 1979-10-05 |
| IT1202899B (en) | 1989-02-15 |
| DE2908635A1 (en) | 1979-09-13 |
| BR7901274A (en) | 1979-10-09 |
| GB2015854B (en) | 1982-04-07 |
| IT7920673A0 (en) | 1979-03-01 |
| DE2908635C2 (en) | 1989-07-13 |
| FR2419008B1 (en) | 1985-03-15 |
| GB2015854A (en) | 1979-09-19 |
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