Electronic control system for low temperature grain drying

Claim 2

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs, dry down indicating means responsive to a first one of said control outputs to indicate an unsuccessful drying operation whenever the set of input signals corresponds to initial conditions for which the probability of successful drying of the grain is less than a preselected value, and to indicate when completion of drying of the grain can be expected whenever the set of input signals corresponds to initial conditions for which the probability of successful drying of the grain is equal to or greater than said preselected value; fan control means including fan enable circuit means normally operable to effect continuous operation of said fan, said fan control means including condition responsive circuit means enabled by a second one of said control outputs to respond to condition sensing means and generate a signal for disabling said fan enable circuit means to interrupt the operation of said fan whenever a predetermined condition is sensed; and aeration circuit means operable when enabled to control said fan enable circuit means to provide intermittent operation of the fan, said condition responsive circuit means being ineffective in disabling said fan enable circuit means when it is operating under the control of said aeration circuit means.

Claim 3

A system as set forth in claim 1 wherein said initializing means includes first, second and third selector switches individually settable to a plurality of different positions to indicate values of initial conditions including the harvest date of the grain, the harvest moisture of the grain, and the rate of air flow through the storage bin, and circuit means for providing a set of input signals for the initialization circuit means indicative of the settings of said selector switches.

Claim 4

A system as set forth in claim 1 wherein said initialization circuit means is preprogrammed on the basis of long-term computer simulation of the low-temperature grain conditioning process to respond to different sets of input signals, representing correspondingly different sets of initial conditions to provide different control outputs.

Claim 5

A system as set forth in claim 3 wherein said initialization circuit means includes memory means having a plurality of addressable storage locations, different ones of said storage locations storing a different multibit control word corresponding to different sets of initial conditions, and memory address means responsive to a given set of input signals for controlling said memory means to effect readout of the control word stored at a storage location corresponding to the set of initial conditions represented by the set of input signals.

Claim 6

A system as set forth in claim 1 wherein said condition responsive circuit means of said fan control means includes timing means responsive to said second control output to define a predetermined interval of time, and inhibit means enabled by said timimg means at the end of said time interval to respond to said condition sensing means and disable said fan enable circuit means whenever said predetermined condition is sensed.

Claim 7

A system as set forth in claim 1 which includes heater means for heating the air supplied to said storage bin, and heater control means operable when enabled to effect energization of said heater means, said initialization circuit means providing a third control output for enabling said heater control means as a function of the set of input signals supplied to said initialization circuit means.

Claim 8

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs, dry down indicating means responsive to a first one of said control outputs to provide an indication of the probability of success of drying the grain; mode select means for enabling said controller to initially be operable in a drying mode and to thereafter be operable in an aeration mode; fan control means responsive to a second one of said control outputs and to first condition sensing means when said controller is operable in the drying mode to maintain the fan operating continuously in the absence of a predetermined condition and to disable the fan whenever said predetermined condition is sensed by said first condition sensing means; and aeration means including timing means for defining timing intervals of at least first and second durations, and aeration circuit means enabled by said mode select means to respond to second condition sensing means for controlling said fan control means while the controller is operating in aeration mode whereby the fan is operated continuously during an aeration period of said first duration whenever preselected ambient conditions are sensed by said second condition sensing means and the operation of the fan is prevented for a period of at least said second duration following each aeration period.

Claim 9

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs, dry down indicating means responsive to a first one of said control outputs to provide an indication of the probability of success of drying the grain; mode select means for enabling said controller to initially be operable in a drying mode and to thereafter be operable in an aeration mode; fan control means responsive to a second one of said control outputs and to first condition sensing means when said controller is operable in the drying mode to maintain the fan operating continuously in the absence of a predetermined condition and to disable the fan whenever said predetermined condition is sensed by said first condition sensing means; and aeration means including timing means for defining timing intervals of at least first and second durations, and aeration circuit means enabled by said mode select means to respond to second condition sensing means for controlling said fan control means while the controller is operating in aeration mode whereby the fan is operated continuously during an aeration period of said first duration whenever preselected ambient conditions are sensed by said second condition sensing means and the operation of the fan is prevented for a period of at least said second duration following each aeration period.

Claim 10

A system as set forth in claim 7 which includes heater means operable to heat the air supplied to the storage bin and heater control means enabled in response to a third one of said control outputs to effect energization of said heater means when said controller is operable in the drying mode, said heater control means being maintained disabled, preventing operation of said heater means in the absence of said third control output.

Claim 11

A system as set forth in claim 8 wherein said heater control means is disabled in response to an output provided by third condition sensing means to interrupt operation of said heater means when a predetermined condition is sensed.

Claim 12

A system as set forth in claim 9 wherein said third condition sensing means comprises a humidistat which responds to ambient relative humidity of a predetermined value to effect interruption of the operation of said heater means.

Claim 13

A system as set forth in claim 7 which further comprises heater means including a solar heating system for heating air supplied to an inlet of said fan.

Claim 14

A system as set forth in claim 11 wherein said heater means further comprises an electrical resistance heater, heater control circuit means for controlling the energization of said resistance heater, and enabling circuit means for controlling the enabling of said heater control circuit means as a function of the occurrence of a minimum temperature rise of a collector of the solar heating system.

Claim 15

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs, dry down indicating means responsive to a first one of said control outputs to provide an indication of the probability of success of drying the grain; mode select means for enabling said controller to initially be operable in a drying mode and to thereafter be operable in an aeration mode; fan control means responsive to a second one of said control outputs and to first condition sensing means to enable intermittent operation of the fan when said controller is operable in the drying mode; heater means including a solar heating system for heating air supplied to an inlet of said fan, and aeration means enabled by said mode select means to respond to second condition sensing means for controlling said fan control means to provide intermittent operation of the fan while the controller is operating in the aeration mode; said heater means further including an electrical resistance heater energizable to provide supplemental heating of the air supplied to said fan inlet, heater control circuit means for controlling the energization of said resistance heater, and enabling circuit means including timing means for defining a time interval and for generating a signal for enabling said heater control circuit means to energize said resistance heater, and inhibit circuit means enabled in response to an output of a differential temperature sensor, indicative of the presence of a minimum collector temperature rise to prevent said timing means from generating its enabling signal thereby preventing the enerigization of said resistance heater.

Claim 16

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs, dry down indicating means responsive to a first one of said control outputs to provide an indication of the probability of success of drying the grain; mode select means for enabling said controller to initially be operable in a drying mode and to thereafter be operable in an aeration mode; fan control means responsive to a second one of said control outputs and to first condition sensing means to enable intermittent operation of the fan when said controller is operable in the drying mode; heater means including a solar heating system for heating air supplied to an inlet of said fan, and aeration means enabled by said mode select means to respond to second condition sensing means for controlling said fan control means to provide intermittent operation of the fan while the controller is operating in the aeration mode; said heater means further including an electrical resistance heater energizable to provide supplemental heating of the air supplied to said fan inlet, heater control circuit means for controlling the energization of said resistance heater, and enabling circuit means including timing means for defining a time interval and for generating a signal for enabling said heater control circuit means to energize said resistance heater, and inhibit circuit means enabled in response to an output of a differential temperature sensor, indicative of the presence of a minimum collector temperature rise to prevent said timing means from generating its enabling signal thereby preventing the enerigization of said resistance heater.

Claim 17

A system as set forth in claim 12 wherein said heater control means includes gating means responsive to a control output of a humidity sensor to prevent the energization of said electrical heater whenever the relative humidity sensed is less than a selected set point value.

Claim 18

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controlling comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs; dry down indicating means responsive to a first one of said control outputs or provide an indication of the probability of success of drying the grain; mode select means for enabling said controller to initially be operable in a drying mode and to thereafter be operable in an aeration mode; fan control means including fan enable means normally enabled to effect continuous operation of the fan while the controller is operating in the drying mode, condition responsive circuit means including inhibit means responsive to said first condition sensing means to disable said fan enable means whereby providing intermittent operation of the fann as a function of the condition sensed by said first condition sensing means, and timing means responsive to said second control output to define a predetermined time interval and to prevent said inhibit means from responding to said first condition sensing means during said time interval thereby providing continuous operation of the fan during said time interval; and aeration means enabled by said mode select means to respond to second condition sensing means for controlling said fan enable means to provide intermittent operation of the fan while the controller is operating in the aeration mode.

Claim 19

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controlling comprising: initializing means including initialization circuit means responsive to a set of input signals representing initial conditions to provide a plurality of control outputs; dry down indicating means responsive to a first one of said control outputs or provide an indication of the probability of success of drying the grain; mode select means for enabling said controller to initially be operable in a drying mode and to thereafter be operable in an aeration mode; fan control means including fan enable means normally enabled to effect continuous operation of the fan while the controller is operating in the drying mode, condition responsive circuit means including inhibit means responsive to said first condition sensing means to disable said fan enable means whereby providing intermittent operation of the fann as a function of the condition sensed by said first condition sensing means, and timing means responsive to said second control output to define a predetermined time interval and to prevent said inhibit means from responding to said first condition sensing means during said time interval thereby providing continuous operation of the fan during said time interval; and aeration means enabled by said mode select means to respond to second condition sensing means for controlling said fan enable means to provide intermittent operation of the fan while the controller is operating in the aeration mode.

Claim 20

A system as set forth in claim 15 wherein said first condition sensing means comprises a humidistat which responds to ambient relative humidity of a predetermined value to generate an inhibit signal to cause said inhibit means to disable said fan enable means.

Claim 21

A system as set forth in claim 15 wherein said condition responsive circuit means includes second timing means enabled by said first-mentioned timing means at the end of said time interval to respond to said inhibit signal and to permit disabling of said fan enable means only when said inhibit signal is provided for a preselected time interval.

Claim 22

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: mode select means for enabling the controller to be operable initially in a drying mode and thereafter in an aeration mode; fan control means including fan enable circuit means operable when enabled to normally effect continuous operation of the fan when the controller is operating in the drying mode; and aeration means for controlling said fan enable circuit means to provide intermittent operation of the fan when the controller is operating in the aeration mode, said aeration means including aeration circuit means enabled by said mode select means to respond to a control output provided by a condition sensing means when ambient conditions within first limits are sensed by said condition sensing means and cause the fan to operate, timing means responsive to said aeration circuit means for maintaining the fan operating for a first period of time after said aeration circuit means responds to said control output, and inhibit means responsive to said timing means to prevent said aeration circuit means from responding to said condition sensing means for a second period of time following said first period of time.

Claim 23

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: mode select means for enabling the controller to be operable initially in a drying mode and thereafter in an aeration mode; fan control means including fan enable circuit means operable when enabled to normally effect continuous operation of the fan when the controller is operating in the drying mode; and aeration means for controlling said fan enable circuit means to provide intermittent operation of the fan when the controller is operating in the aeration mode, said aeration means including aeration circuit means enabled by said mode select means to respond to a control output provided by a condition sensing means when ambient conditions within first limits are sensed by said condition sensing means and cause the fan to operate, timing means responsive to said aeration circuit means for maintaining the fan operating for a first period of time after said aeration circuit means responds to said control output, and inhibit means responsive to said timing means to prevent said aeration circuit means from responding to said condition sensing means for a second period of time following said first period of time.

Claim 24

A system as set forth in claim 18 wherein said fan control means further includes condition responsive means for normally enabling said fan enable circuit means, said condition responsive means being responsive to a further condition sensing means sensing a predetermined condition to disable said fan enable circuit means.

Claim 25

A system as set forth in claim 18 wherein said mode selector switch manually operable to effect the transfer of the controller operation from the drying mode to the aeration mode, said selector switch being settable to a first position to select a dry grain aeration cycle for grain which is dried while the controller is operating in the drying mode, and being settable to a second position to select a wet grain aeration cycle when the grain is only partially dried while the controller is operating in the drying mode.

Claim 26

A system as set forth in claim 20 wherein said aeration circuit means is enabled when said selector switch is set to either one of said positions.

Claim 27

A system as set forth in claim 20 wherein said aeration means further includes secondary aeration circuit means enabled by said first-mentioned aeration circuit means, in the absence of said preselected ambient conditions with a given time following said second period of time, to respond to further condition sensing means for enabling said fan enable circuit means to effect operation of the fan for a time interval, less than said first period of time, when ambient conditions within second limits are sensed by said further condition sensing means.

Claim 28

A system as set forth in claim 22 wherein said aeration means includes means for maintaining said secondary aeration circuit means disabled whenever said selector switch is set to said first position.

Claim 29

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: mode select means for enabling the controller to be operable in drying and aeration modes; fan control means including fan enable means operable when enabled to effect continuous operation of the fan when the controller is operating in the drying mode; and aeration means operable when enabled to respond to condition sensing means for controlling said fan enable means to provide intermittent operation of the fan when the controller is operating in the aeration mode, said condition sensing means including first sensor means for providing a first control output when a first condition is sensed, and second sensor means for providing a second control output when a second condition is sensed, said aeration means including primary aeration circuit means operable when enabled to respond to said first control output to enable said fan enable means to effect operation of the fan for a time interval of a given duration, thereby effecting a primary aeration, and secondary aeration circuit means controlled by said primary aeration circuit means to respond to said second control output for enabling said fan enable means to effect operation of the fan for a time interval of a duration less than said given duration, thereby effecting a secondary aeration and timing means for preventing said primary aeration circuit means from responding to said first control output for a predetermined time following a primary aeration.

Claim 30

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: mode select means for enabling the controller to be operable in drying and aeration modes; fan control means including fan enable means operable when enabled to effect continuous operation of the fan when the controller is operating in the drying mode; and aeration means operable when enabled to respond to condition sensing means for controlling said fan enable means to provide intermittent operation of the fan when the controller is operating in the aeration mode, said condition sensing means including first sensor means for providing a first control output when a first condition is sensed, and second sensor means for providing a second control output when a second condition is sensed, said aeration means including primary aeration circuit means operable when enabled to respond to said first control output to enable said fan enable means to effect operation of the fan for a time interval of a given duration, thereby effecting a primary aeration, and secondary aeration circuit means controlled by said primary aeration circuit means to respond to said second control output for enabling said fan enable means to effect operation of the fan for a time interval of a duration less than said given duration, thereby effecting a secondary aeration and timing means for preventing said primary aeration circuit means from responding to said first control output for a predetermined time following a primary aeration.

Claim 31

A system as set forth in claim 24 wherein said aeration means includes control circuit means operable when enabled to respond to said timing means to enable said secondary aeration circuit means whenever said first control output fails to be provided within a predetermined time following a primary aeration.

Claim 32

A system as set forth in claim 25 wherein said control means includes delay means responsive to said timing means to delay the enabling of said secondary aeration circuit means for an interval of time after said predetermined time following a primary aeration.

Claim 33

A system as set forth in claim 26 wherein said control means includes means responsive to said timing means for enabling said secondary aeration circuit means to respond to said second control output after said predetermined time following a secondary aeration.

Claim 34

A system as set forth in claim 27 wherein said mode select means includes exit drying mode circuit means responsive to a predetermined condition to enable said primary aeration circuit means.

Claim 35

A system as set forth in claim 20 wherein said mode select means includes exit aeration circuit means responsive to a predetermined condition and to said selector switch to effect shutdown of the controller whenever a dry grain aeration cycle preceeded the exit, and to transfer controller operation from the aeration mode to the drying mode whenever a wet grain aeration cycle preceeded the exit.

Claim 38

A method as set forth in claim 30 including the further steps of enabling a heater to operate continuously from the start of the drying operation until the grain moisture content reaches said given value; sensing ambient relative humidity by way of a further humidistat; and enabling the further humidistat to maintain the heater operating whenever the ambient relative humidity is greater than a preset value and to cause the heater operation to be halted whenever ambient relative humidity is less than set preset value.

Claim 39

A method as set forth in claim 31 including the further step of causing the operation of the heater to be halted whenever the operation of the fan is halted.

Claim 40

A method as set forth in claim 30 including the further steps of using a solar heat source to heat the air supplied to an inlet of the fan, and sensing a given minimum solar collector temperature rise; and energizing an electrically resistance heater for heating the air whenever said given minimum solar collector temperature rise fails to be sensed within a given time period.

Claim 41

A method as set forth in claim 33 including the further steps of sensing ambient relative humidity by way of a further humidistat; and enabling the further humidistat to prevent the operation of the electrical resistance heater whenever ambient relative humidity is less than a set point value.

Claim 42

A method as set forth in claim 34 including the further step of causing the operation of the electrical resistance heater to be halted whenever the operation of the fan is halted.

Claim 45

A method as set forth in claim 36 including the further steps of sensing ambient temperature by way of second condition sensing means; enabling a second aeration circuit means to respond to a second control output provided by said second condition sensing means and to cause operation of the fan to effect a secondary aeration whenever the first mentioned control output fails to be provided within a predetermined time following a primary aeration; and causing the operation of the fan to be halted after a time interval defined by a third timer.

Claim 46

A method as set forth in claim 37 including the further step of preventing the secondary aeration circuit means from responding to said second control output for a predetermined time after a primary aeration.

Claim 47

A method as set forth in claim 37 which includes the further step of preventing the secondary aeration circuit means from responding to said second control output for a predetermined time following a secondary aeration.

Claim 48

A method as set forth in claim 36 which includes the steps of sensing grain temperature by way of a further condition sensing means; and enabling a fan control circuit means to respond to a control output provided by said further condition sensing means and effect continuous operation of the fan as long as said further condition sensing means provides its control output.

Claim 49

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: input means for receiving signals representing initial conditions including the grain harvest date, the initial moisture content of the grain, and the air flow rate, and signals representing sensed conditions including grain temperature, ambient temperature and ambient relative humidity, signal processing means responsive to the received signals for defining a drying cycle and an aeration cycle and for using the received signals to generate control outputs based upon predicted grain moisture levels for controlling the operation of the fan during the drying and aeration cycles whereby during the drying cycle, the fan is initially operated continuously for a time indicated by at least one of said control outputs and is thereafter operated intermittently as a function of the presence or absence of a sensed ambient condition as indicated by one of said received signals, and during the aeration cycle, the fan is maintained disabled in the absence of preselected conditions as indicated by at least one other one of said received signals, and is operated whenever said preselected ambient conditions are sensed.

Claim 50

In a low-temperature grain conditioning system including a grain storage bin, and a fan operable to draw air into the storage bin and force the air through the grain, a controller for controlling the operation of the fan, said controller comprising: input means for receiving signals representing initial conditions including the grain harvest date, the initial moisture content of the grain, and the air flow rate, and signals representing sensed conditions including grain temperature, ambient temperature and ambient relative humidity, signal processing means responsive to the received signals for defining a drying cycle and an aeration cycle and for using the received signals to generate control outputs based upon predicted grain moisture levels for controlling the operation of the fan during the drying and aeration cycles whereby during the drying cycle, the fan is initially operated continuously for a time indicated by at least one of said control outputs and is thereafter operated intermittently as a function of the presence or absence of a sensed ambient condition as indicated by one of said received signals, and during the aeration cycle, the fan is maintained disabled in the absence of preselected conditions as indicated by at least one other one of said received signals, and is operated whenever said preselected ambient conditions are sensed.

Claim 51

A system as set forth in claim 41 which further comprises dry down indicating means responsive to a further one of said control outputs to provide an indication of the probability of success of drying the grain.

Claim 52

A system as set forth in claim 18 wherein said mode select means comprises exit drying mode circuit means controlled by a temperature sensing means to transfer the operation of the controller from the drying mode to the aeration mode when the temperature of the grain decreases to a given value.