PRESSURE REGULATING SYSTEM FOR A DRYER APPARATUS

摘要

A system for regulating internal dryer vapor pressure to provide a continuous, optimum pressure for the wood veneer being dried. A voltage proportional to dryer pressure is compared with a settable voltage corresponding to optimum dryer pressure with the potential difference therebetween being detected by a first differential amplifier. The output signal of said amplifier constitutes an error signal to a second differential amplifier. Said second differential amplifier compares said error signal with a voltage proportional to the position of a power operated damper. Switch means in circuit with said second amplifier includes high and low voltage actuated relays which energize a damper motor for operation in opposite directions for opening and closing the damper to decrease or increase dryer pressure. In a balanced condition wherein the dryer is operating within an optimum pressure range the output of said second amplifier is such as to cause the high and low relays to remain open and hence the damper and dryer pressure being static.