A dryer of the type having a burner for supplying a source of hot gas for drying material being tumbled. The apparatus provides a cool-down cycle for the dryer. A burner control circuit enables and disables the burner to supply hot gasses in accordance with a sequence which produces a substantially linearly decreasing temperature over time. At the end of the time interval a signal is generated indicating that the cool-down sequence has been completed. Each cool-down cycle starts from the same initial temperature as determined by the operator such that the final cool-down temperature for the same cool-down run time is the same.

Apparatus and method for controlling a drying cool-down cycle of a clothes dryer

A solenoid valve having particular utility in adaptive braking systems on automotive vehicles, in which the armature is provided with a conventional coil spring urging it toward its released position. A supplementary spring in the form of a bowed or wave washer whose free height is less than the total air gap of the valve also acts as an anti-residual magnetism shim. The supplementary spring makes it possible to minimize closing and opening times of the valve.

Solenoid valve with plural springs

A capacitor discharge ignition system wherein an energy storage capacitor is charged to a relatively high voltage and synchronously discharged into the primary winding of an ignition coil to develop a high-energy short-time duration spark discharge at the secondary winding of the ignition coil, and a circuit is provided for increasing the time duration of the spark discharge beyond that normally obtained from the capacitor discharge system to improve the fuel-igniting properties of the spark.

Spark duration for capacitor discharge ignition systems

A fuel burner includes an electrical igniter which lights a pilot burner which then lights the main burner. Operation of each of these steps is monitored, and if any are improper, the control device reverts to lighting the pilot burner with the main burner valve shut. If the igniter is sensed as incapable of lighting the pilot burner, the pilot burner valve is shut, and an error is indicated to the operator.

Fuel burner having an intermittent pilot with pre-ignition testing

A system for controlling the pilot and main burner gas valves of a gas furnace or the like, including a pilot spark igniter and a pilot flame sensor. A relay having a first standby mode providing power to the spark igniter circuit when the thermostat switch is closed and the pilot valve solenoid is energized, and a second operating mode disconnecting power from the spark igniter circuit and providing power to the main valve solenoid when a flame is sensed at the pilot burner. A fast responding, stable and failsafe circuit for operating the relay utilizing a 24 volt supply, with a 48 volt supply provided only for the flame sensor.

Intermittent pilot igniter and valve controller for gas burner

Magnetic operator for valves or the like

High voltage spark generator from low voltage supply

Fuel burner control using silicon controlled rectifier spark generation and thermocouple actuated reed switch

A control arrangement for a fuel ignition system to provide an interlock on start-up to prevent energization of fuel valves under certain failure conditions includes a pulse generating circuit operable when enabled to provide pulses for enabling a first switching device which energizes a pilot valve to supply fuel to a fuel outlet and prepares an energizing path for a main valve, and a second switching device enabled by a flame sensing circuit when a flame is established at the outlet to close associated contacts to complete the energizing path for the main valve and to cause the pulse generating circuit to continue to generate pulses for maintaining the first switching device enabled, the pulse generating circuit being inhibited whenever the contacts are closed at start-up, or close after the system is in a lock out state, preventing the enabling of the first switching device to maintain the pilot valve and the main valve deenergized.

Fuel ignition system control arrangement providing total fuel shutoff and contact protection

An electromagnetic relay is energized by the sequence of first energizing a warp switch sufficiently for the warp switch to close a pair of contacts in an energizing circuit for the relay. Actuation of the relay closes self-holding contacts and cams open a pair of warp switch normally closed contacts in the initiating circuit. Both the relay and the warp switch heater are maintained energized at reduced power through the self-holding relay contacts. Upon any interruption of power the control recycles after a delay of from 3 1/2 to 5 1/2 minutes. This relatively long delay occurs, since the relay, upon releasing,, opens its self-holding contacts necessitating that the warp switch heater cool sufficiently to place its contacts again closed for initiating starting. Starting is then initiated by again reheating the warp switch heater, thereby, providing the sequence of warp switch ''''cooldown'''' and ''''reheat'''' time intervals between cycles. The initiating warp switch normally closed contacts, once opened, cannot reclose unless the camming relay first releases to remove a mechanical block to such opening. This insures a full cooldown and heating warp switch cycle for each operation. The control provides foolproof operation in that a ''''make before break'''' is obtained between the relay self-holding contacts and the warp switch initiating circuit contacts, since the relay self-holding contacts must close before the warp switch contacts can be cammed open. This insures that the operating control is in ''''run'''' condition before the warp switch is placed on reduced power. Upon cooldown of the warp switch, a lost motion connection of its actuator insures that the warp switch initiating contacts reclose only after its self-holding contacts have opened to insure a full reheat cycle of the warp switch for restarting.

Gerald E Dietz

Papers

Magnetic operator for valves or the like

High voltage spark generator from low voltage supply

Fuel burner control using silicon controlled rectifier spark generation and thermocouple actuated reed switch

Fuel ignition system control arrangement providing total fuel shutoff and contact protection

Delayed cycling control