Moisture measuring and control apparatus

Claim 2

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the standard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means, and timing means for permitting said means for producing dry correction control signals to respond to said dry condition signals and for permitting said means for producing wet correction control signals to respond to said wet condition signals only during periods of predetermined time duration at reoccurring intervals of predetermined frequency while said dry and wet condition signals continue, said timing means including an amount of correction timer means which determines the length of the time periods during which the dry and wet condition signals may be applied to said means for producing dry correction control signals and to said means for producing wet correction control signals respectively, and a frequency of correction timer means for periodically resetting said amount of correction timer at a predetermined frequency.

Claim 3

The apparatus set forth in claim 1 wherein said time delay period includes a start time delay initiated when the material conveying means begins to move material through the material moisture conditioning means and a correction time delay initiated at the end of said start time delay and only when said comparator is generating a dry or wet condition signal.

Claim 4

The apparatus set forth in claim 1 wherein said moisture measuring means is an electrical resistance type moisture meter which includes a substantially constant d.c. voltage source, a pair of electrodes for continuously bridging a portion of the material to be measured and a set moisture control resistor in series circuit with said voltage source and said electrodes, said set moisture control resistor being adjustable and being normally set so that its resistance value is equivalent to the resistance of the material to be measured at the desired moisture level, high input impedance voltage to current converter means for sensing the voltage across the set moisture resistor and producing an output current which is directly proportional to the voltage drop across the set moisture control resistor, a current to voltage converter responsive to said output current from said voltage to current converter for converting and scaling said output current into a ground-referred voltage, a moisture indicator means responsive to said ground-referred voltage for indicating the moisture content of said material, and circuit means for applying said ground-referred voltage to said control comparator.

Claim 5

The apparatus set forth in claim 3 wherein said moisture indicator has an indicator dial including a central normal zone, a wet zone and a dry zone, said wet zone and dry zone being on opposite sides of said normal zone.

Claim 6

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the staNdard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means, and timing means for permitting said means for producing dry correction control signals to respond to said dry condition signals and for permitting said means for producing wet correction control signals to respond to said wet condition signals only during periods of predetermined time duration at reoccurring intervals of predetermined frequency while said dry and wet condition signals continue and only after a time delay period, said moisture meansuring means being an electrical resistance type moisture meter which includes a substantially constant d.c. voltage source, a pair of electrodes for continuously bridging a portion of the material to be measured and a set moisture control resistor in series circuit with said voltage source and said electrodes, said set moisture control resistor being adjustable and being normally set so that its resistance value is equivalent to the resistance of the material to be measured at the desired moisture level, high input impedance voltage to current converter means for sensing the voltage across the set moisture resistor and producing an output current which is directly proportional to the voltage drop across the set moisture control resistor, a current to voltage converter responsive to said output current from said voltage to current converter for converting and scaling said output current into a ground-referred voltage, a moisture indicator means responsive to said ground-referred voltage for indicating the moisture content of said material, and circuit means for applying said ground-referred voltage to said control comparator, said moisture indicator having an indicator dial including a central normal zone, a wet zone and a dry zone, said wet zone and dry zone being on opposite sides of said normal zone, and said control comparator consisting of two operational amplifiers operating open loop for maximum sensitivity, each operational amplifier having an inverting input, a non-inverting input and an output terminal, one operational amplifier having its non-inverting input connected to receive the output voltage from said current to voltage converter while the other operational amplifier has its inverting input connected to receive the output voltage from said current to voltage converter, the one operational amplifier having its inverting input connected to receive said reference signal from said control point selector and the other operational amplifier having its non-inverting input connected to receive said reference signal from said control point selector, and a control sensitivity adjusting means for said comparator whereby the operational amplifiers are caused to produce said normal output signal when the moisture indicator reads within said normal zone.

Claim 7

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the staNdard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means, and timing means for permitting said means for producing dry correction control signals to respond to said dry condition signals and for permitting said means for producing wet correction control signals to respond to said wet condition signals only during periods of predetermined time duration at reoccurring intervals of predetermined frequency while said dry and wet condition signals continue and only after a time delay period, said moisture meansuring means being an electrical resistance type moisture meter which includes a substantially constant d.c. voltage source, a pair of electrodes for continuously bridging a portion of the material to be measured and a set moisture control resistor in series circuit with said voltage source and said electrodes, said set moisture control resistor being adjustable and being normally set so that its resistance value is equivalent to the resistance of the material to be measured at the desired moisture level, high input impedance voltage to current converter means for sensing the voltage across the set moisture resistor and producing an output current which is directly proportional to the voltage drop across the set moisture control resistor, a current to voltage converter responsive to said output current from said voltage to current converter for converting and scaling said output current into a ground-referred voltage, a moisture indicator means responsive to said ground-referred voltage for indicating the moisture content of said material, and circuit means for applying said ground-referred voltage to said control comparator, said moisture indicator having an indicator dial including a central normal zone, a wet zone and a dry zone, said wet zone and dry zone being on opposite sides of said normal zone, and said control comparator consisting of two operational amplifiers operating open loop for maximum sensitivity, each operational amplifier having an inverting input, a non-inverting input and an output terminal, one operational amplifier having its non-inverting input connected to receive the output voltage from said current to voltage converter while the other operational amplifier has its inverting input connected to receive the output voltage from said current to voltage converter, the one operational amplifier having its inverting input connected to receive said reference signal from said control point selector and the other operational amplifier having its non-inverting input connected to receive said reference signal from said control point selector, and a control sensitivity adjusting means for said comparator whereby the operational amplifiers are caused to produce said normal output signal when the moisture indicator reads within said normal zone.

Claim 8

The apparatus set forth in claim 5 wherein said means responsive to said dry condition signal for producing dry correction control signals includes a normally open, dry condition signal responsive switch in series circuit with a voltage source and the energizing coil of a dry correction relay, and wherein said means responsive to said wet condition signal for producing wet correction control signals includes a normally open wet condition signal responsive switch in series circuit with a voltage source and the energizing coil of a wet correction relay.

Claim 9

The apparatus set forth in claim 6 wherein said normally open dry condition signal responsive switch and said normally open wet condition signal responsive switch are solid state switches which are normally biased to cut off.

Claim 10

The apparatus set forth in claim 6 wherein said timing means provides bias for maintaining said normally open dry condition signal responsive switch and said normally open wet condition signal responsive switch open even when dry and wet condition signals are present, and removes said bias for periods of predetermined time duration at reoccurring intervals of predetermined frequency while said dry and wet condition signals continue thus permitting said dry and wet condition signal responsive switches to respond to said dry and wet condition signals respectively while said bias is removed.

Claim 11

The apparatus set forth in claim 6 wherein said means alternatively responsive to said dry and wet correction control signals includes a reversible correction control motor, a speed control potentiometer driven by said reversible correction control motor for adjusting the speed of said variable speed conveyor drive, and reversing circuit means for energizing said reversible correction control motor selectively in opposite directions, said reversing circuit means being controlled by said dry correction relay when energized to cause said correction control motor to move said speed control potentiometer in a direction to increase the speed of said variable speed conveyor drive means and said reversing circuit means being controlled by said wet correction relay when energized to cause said correction control motor to move said speed control potentiometer in a direction to decrease the speed of said variable speed conveyor drive means.

Claim 12

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the standard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means and timing means for blocking said dry and wet condition signals from said means for producing dry correction control signals and said means for producing wet correction control signals respectively and for unblocking said dry and wet condition signals during time periods of predetermined length at reocurring intervals, said timing means including an amount of correction timer means which determines the length of the time periods during which the dry and wet condition signals are applied to said means for producing dry correction control signals and to said means for producing wet correction control signals respectively, and a frequency of correction timer means for periodically resetting said amount of correction timer at a predetermined frequency.

Claim 13

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the standard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means and timing means for blocking said dry and wet condition signals from said means for producing dry correction control signals and said means for producing wet correction control signals respectively and for unblocking said dry and wet condition signals during time periods of predetermined length at reocurring intervals, said timing means including an amount of correction timer means which determines the length of the time periods during which the dry and wet condition signals are applied to said means for producing dry correction control signals and to said means for producing wet correction control signals respectively, and a frequency of correction timer means for periodically resetting said amount of correction timer at a predetermined frequency.

Claim 14

The apparatus set forth in claim 10 wherein said amount of correction timer means includes an amount of dry correction timer means for unblocking the means for producing dry correction signals and an amount of wet correction timer means for unblocking the means for producing wet correction signals, and means for selecting the amount of dry correction timer means to operate only when a dry condition signal is being generated, and for selecting the amount of wet correction timer means to operate when said wet condition signal is being generated.

Claim 15

The apparatus set forth in claim 11 wherein said amount of dry correction timer means and said amount of wet correction timer means are adjustable for operating over time periods of different length.

Claim 16

The apparatus set forth in claim 12 wherein said amount of wet correction timer means is adjusted to operate over a longer time period than said amount of dry correction timer means.

Claim 17

The apparatus set forth in claim 13 wherein said timing means further includes a correction delay timer means for delaying the operation of said amount of correction timer means a predetermined time period after said comparator begins to generate wet or dry condition signals to assure that an abnormal signal persists long enough to warrant correction.

Claim 18

The apparatus set forth in claim 14 wherein said timing means further includes a start delay timer means for delaying the operation of said correction delay timer for a predetermined time period after the material conveying means begins to move material through the material moisture conditioning means.

Claim 19

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the standard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means and timing means for blocking said dry and wet condition signals from said means for producing dry correction control signals and said means for producing wet correction control signals respectively and for unblocking said dry and wet condition signals during time periods of predetermined length at reoccuring intervals, said timing means including a start delay timer for establishing a start time delay sufficient to permit the material in the conditioning means at the time it is started to clear the machine, a correction delay timer which establishes a time delay period after the start time delay which insures that a condition requiring correction persists long enough to warrant correction, an amount of correction timer which is actuated after the correction delay period to establish a time period during which time said means responsive to said wet and dry condition signals for producing wet and dry correction control signals respectively are unblocked and permitted to respond to said wet and dry condition signals respectively, and a frequency of correction timer which is actuated at the end of the time period established by the amount of correction timer to recycle the amount of correction timer at reoccurring intervals of predetermined frequency for as long as an abnormal condition signal is being generated.

Claim 20

Moisture measuring and control apparatus for use with a material moisture conditioning means having conveyor means for conveying the material through the material moisture conditioning means and a variable speed drive means for driving the conveyor means at different speeds as determined by said moisture measuring and control apparatus, said moisture measuring and control apparatus comprising means for continuously measuring the moisture content of material conveyed through the material moisture conditioning means and producing an electrical output signal related to the moisture in the material, a control point selector means for generating a reference signal related to a selected standard moisture content, a control comparator means for comparing the measured moisture signal with the reference signal, said control comparator means generating a wet condition signal when said measured moisture content exceeds the standard moisture content by a predetermined amount, generating a dry condition signal when the measured moisture content is less than the standard moisture content by a predetermined amount and generating a normal signal when the measured moisture content is within a predetermined range centered with respect to said standard moisture content, means responsive to said dry condition signal for producing dry correction control signals, means responsive to said wet condition signal for producing wet correction control signals, means responsive alternatively to said dry and wet correction control signals for increasing and decreasing respectively the speed of said variable speed conveyor drive means and timing means for blocking said dry and wet condition signals from said means for producing dry correction control signals and said means for producing wet correction control signals respectively and for unblocking said dry and wet condition signals during time periods of predetermined length at reoccuring intervals, said timing means including a start delay timer for establishing a start time delay sufficient to permit the material in the conditioning means at the time it is started to clear the machine, a correction delay timer which establishes a time delay period after the start time delay which insures that a condition requiring correction persists long enough to warrant correction, an amount of correction timer which is actuated after the correction delay period to establish a time period during which time said means responsive to said wet and dry condition signals for producing wet and dry correction control signals respectively are unblocked and permitted to respond to said wet and dry condition signals respectively, and a frequency of correction timer which is actuated at the end of the time period established by the amount of correction timer to recycle the amount of correction timer at reoccurring intervals of predetermined frequency for as long as an abnormal condition signal is being generated.

Claim 21

The apparatus set forth in claim 16 wherein said timers are energized from the same power source, and sequencing means are provided for energizing said start delay timer when the conditioning means is turned on, for energizing said correction delay timer after the start delay period and when an abnormal condition signal is being generated, for energizing said amount of correction timer at the end of said correction time delay, for energizing said frequency of correction timer at the end of the time period established by the amount of correction timer.

Claim 22

The apparatus set forth in claim 17 wherein said sequencing means includes a plurality of series switches separating the respective timers from said power source, said series switches including a first normally open switch connected in a sequencing circuit between said power source and said start delay timer which is closed when said moisture conditioning means is turned on, a second normally open switch connected in said sequencing circuit between said start delay timer and said correction delay timer which is closed at the end of said start delay when an abnormal condition signal is being generated, a third normally open switch connected in said sequencing circuit between said correction delay timer and said amount of correction timer which is closed at the end of said correction delay period, and a fourth normally open switch connected in said sequencing circuit between said amount of correction timer and said frequency of correction timer which is closed at the end of said amount of correction time period.

Claim 23

The apparatus set forth in claim 18 wherein said switches are solid state switches and said timers are solid state timers.

Claim 24

The apparatus set forth in claim 16 wherein all of said timers have means for adjusting their respective time periods.