Pressure regulating system for a dryer apparatus

Claim 3

The system as claimed in claim 1 additionally including a meter calibrated to indicate internal dryer vapor pressure, means for converting the dryer pressure signal into meter driving amperage.

Claim 4

The system as claimed in claim 2 wherein said pressure signalling means includes a pressure transducer in communication with the dryer interior and amplifier means.

Claim 5

The system as claimed in claim 3 wherein said pressure transducer is in communication with an internal area of the dryer having relatively high vapor pressure.

Claim 6

The system as claimed in claim 1 additionally including a meter calibrated to indicate damper position, means converting the damper position signal into meter driving amperage.

Claim 7

In combination with a veneer dryer apparatus having an internal heated airflow for the drying of veneer conveyed therethrough, said apparatus having one or more air outlets regulated by power operated damper means, the improvement comprising a system for regulating internal dryer vapor pressure and humidity including, a pressure responsive device providing an electrical signal proportional to internal dryer pressure, means amplifying said signal, first differential amplifier means having a normal output voltage and amplifying the voltage difference between two input signals one of which being the amplified dryer pressure signal, the remaining input signal being a settable voltage, the voltage difference detected causing an increase or decrease from the amplifiers normal output voltage to constitute an error signal, means providing said remaining input signal and being adjustable to provide a variable voltage input signal, said input signals being substantially equal when the dryer is operating at a desired pressure, the desired pressure being different for batches of veneer having different thicknesses and moisture content, second differential amplifier means having a normal output voltage and amplifying the voltage difference between two signal inputs one of which being the error signal from said first differential amplifier, damper signal producing means providing the second signal input into said second amplifier means with the last mentioned input increasing and decreasing with changes in the position of the dryers damper means, said second differential amplifier means producing, during an unbalanced signal input condition, an output signal proportional to the difference between the voltage of its two input signals, the voltage difference detected causing an increase or decrease from the second amplifier normal output voltage, switch means including high and low voltage switch contacts closeable in response to the increase or decrease away from the normal voltage output of said second amplifier means, said switch contacts in circuit with the power operated damper means of the dryer apparatus for movement of the damper toward an open or closed position to respectively lower or raise internal dryer pressure toward the desired dryer pressure, and the operation of the power driven damper means automatically terminating when the output of sAid second amplifier returns to a voltage intermediate the preset voltage values of said high and low switch contacts.

Claim 8

In combination with a veneer dryer apparatus having an internal heated airflow for the drying of veneer conveyed therethrough, said apparatus having one or more air outlets regulated by power operated damper means, the improvement comprising a system for regulating internal dryer vapor pressure and humidity including, a pressure responsive device providing an electrical signal proportional to internal dryer pressure, means amplifying said signal, first differential amplifier means having a normal output voltage and amplifying the voltage difference between two input signals one of which being the amplified dryer pressure signal, the remaining input signal being a settable voltage, the voltage difference detected causing an increase or decrease from the amplifiers normal output voltage to constitute an error signal, means providing said remaining input signal and being adjustable to provide a variable voltage input signal, said input signals being substantially equal when the dryer is operating at a desired pressure, the desired pressure being different for batches of veneer having different thicknesses and moisture content, second differential amplifier means having a normal output voltage and amplifying the voltage difference between two signal inputs one of which being the error signal from said first differential amplifier, damper signal producing means providing the second signal input into said second amplifier means with the last mentioned input increasing and decreasing with changes in the position of the dryers damper means, said second differential amplifier means producing, during an unbalanced signal input condition, an output signal proportional to the difference between the voltage of its two input signals, the voltage difference detected causing an increase or decrease from the second amplifier normal output voltage, switch means including high and low voltage switch contacts closeable in response to the increase or decrease away from the normal voltage output of said second amplifier means, said switch contacts in circuit with the power operated damper means of the dryer apparatus for movement of the damper toward an open or closed position to respectively lower or raise internal dryer pressure toward the desired dryer pressure, and the operation of the power driven damper means automatically terminating when the output of sAid second amplifier returns to a voltage intermediate the preset voltage values of said high and low switch contacts.

Claim 9

The system as claimed in claim 6 additionally including a meter calibrated to indicate internal dryer pressure, means for converting the dryer pressure signal into meter driving amperage.

Claim 10

The system as claimed in claim 7 wherein said pressure responsive device is a pressure transducer in pressure communication with the dryer interior.

Claim 11

The system as claimed in claim 8 wherein said pressure transducer is in communication with an internal area of the dryer having relatively high vapor pressure.

Claim 12

The system as claimed in claim 9 additionally including a meter calibrated to indicate damper position, means converting the damper position signal into meter driving amperage.