Dryer control circuit

Claim 2

A laundry appliance comprising: a rotatable drum for receiving laundry; a motor for rotating said drum; a presettable control device connectable to an electrical supply for controlling the operation of the appliance through a selected laundry program including a drying cycle; a source of heat for said drum connected to said control device for energization by the electrical supply, said source of heat including first and second controllable energization circuits for operating said source of heat at a high heat output and a lower heat output, means connected between said control device and said source of heat for controlling the operation of said source of heat including temperature-responsive-switching means disposed to sense the temperature within said drum and connected between said contrOl device and said first and second controllable energization circuits, said switching means being responsive to the temperature within said drum to effect operation of both of said controllable energization circuits during an initial portion of the drying cycle and to effect operation of only one of said energization circuits during a subsequent portion of the drying cycle, wherein said temperature-responsive-switching means includes a first thermostat having a first contact connected to said control device and a second movable contact connected to said first controllable energization circuit, and a second thermostat having a third contact connected to said control device, a fourth movable contact connected to said second controllable energization circuit, and a fifth contact connected to said contact of said first thermostat, said second thermostat being responsive to first and second temperature to transfer said fourth contact back and forth between said third and fifth contacts, and said first thermostat opening and closing said first and second contacts in response to third and fourth temperatures, respectively, which lie outside of the range defined by said first and second temperatures.

Claim 3

A laundry appliance according to claim 1, wherein said source of heat comprises a gas burner for connection to a gas supply, a first solenoid valve including on-off valve means serially interposed between said burner and the gas supply, and first operating winding means connected to said temperatureresponsive-switching means as said first controllable energization circuit, a second solenoid valve including a two-level valve means also serially interposed between said burner and the gas supply, said two-level being normally open to a flow-restricting condition and operable to a greater flow condition, and second operating winding means connected to said temperatureresponsive-switching means as said second controllable energization circuit, and an igniter connected to said first operating winding means for igniting the gas supplied to said burner.

Claim 4

A laundry appliance according to claim 1, wherein said source of heat comprises a gas burner for connection to a gas supply, a first solenoid valve including on-off valve means serially interposed between said burner and the gas supply, and first operating winding means connected to said temperature-responsive-switching means as said first controllable energization circuit, a second solenoid valve including a two-level valve means also serially interposed between said burner and the gas supply, said two-level being normally open to a flow-restricting condition and operable to a greater flow condition, and second operating winding means connected to said temperature-responsive-switching means as said second controllable energization circuit, and an igniter connected to said first operating winding means for igniting the gas supplied to said burner.

Claim 5

Drying apparatus comprising: means defining a treatment zone receiving material to be dried; supplied a source of heat for providing thermal energy to said treatment zone; and means for operating said source of heat during a timed drying cycle at a plurality of heating output levels including first means for operating said source of heat at a first heating output level during an initial portion of the cycle until a first predetermined temperature is attained in said treatment zone, comprising a first normally closed thermostat, and second means for operating said source of heat at a second heating output level which is lower than said first heating output level to maintain a temperature which is lower than said first predetermined temperature during a subsequent portion of said drying cycle, comprising a second normally closed thermostat cooperable with said first thermostat to establish a plurality of electrical circuits which connect said source of heat to an electrical supply, said first thermostat connected in a first of said electrical circuits and operable to an open condition in response to said first predetermined temperature, said second thermostat connected in a second of said electrical circuits and operable to open said second circuit in response to a second predetermined temperature and to close in response to a third predetermined temperature lower than said second predetermined temperature to maintain an intermediate temperature, said second thermostat comprising s first contact, a second movable contact normally closed to said first contact, and a third contact connected to said first thermostat, said movable second contact transferring from said first contact to said third contact in response to said second predetermined temperature to provide a third electrical circuit for said source of heat through said first thermostat prior tO attainment of said first predetermined temperature within said treatment zone, said first thermostat operable to reestablish its corresponding electrical circuit at a temperature below said third predetermined temperature.

Claim 6

Drying apparatus comprising: means defining a treatment zone receiving material to be dried; supplied a source of heat for providing thermal energy to said treatment zone; and means for operating said source of heat during a timed drying cycle at a plurality of heating output levels including first means for operating said source of heat at a first heating output level during an initial portion of the cycle until a first predetermined temperature is attained in said treatment zone, comprising a first normally closed thermostat, and second means for operating said source of heat at a second heating output level which is lower than said first heating output level to maintain a temperature which is lower than said first predetermined temperature during a subsequent portion of said drying cycle, comprising a second normally closed thermostat cooperable with said first thermostat to establish a plurality of electrical circuits which connect said source of heat to an electrical supply, said first thermostat connected in a first of said electrical circuits and operable to an open condition in response to said first predetermined temperature, said second thermostat connected in a second of said electrical circuits and operable to open said second circuit in response to a second predetermined temperature and to close in response to a third predetermined temperature lower than said second predetermined temperature to maintain an intermediate temperature, said second thermostat comprising s first contact, a second movable contact normally closed to said first contact, and a third contact connected to said first thermostat, said movable second contact transferring from said first contact to said third contact in response to said second predetermined temperature to provide a third electrical circuit for said source of heat through said first thermostat prior tO attainment of said first predetermined temperature within said treatment zone, said first thermostat operable to reestablish its corresponding electrical circuit at a temperature below said third predetermined temperature.

Claim 7

Drying apparatus comprising: means defining a treatment zone for receiving material to be dried; a source of heat for providing thermal energy to said treatment zone; and means for operating said source of heat during a timed drying cycle at a plurality of output heating levels including first means, including a first thermostat, for operating said source of heat at a first heating output level during an initial portion of the cycle until a first predetermined temperature is attained in said treatment zone, and second means, including a second thermostat, for operating said source of heat at a second heating output level which is lower than the first heating output level to maintain a temperature which is lower than said first predetermined temperature during a subsequent portion of the drying cycle, said source of heat comprising a gas burner including a connection to a gas supply, first solenoid valve means having a first valve means disposed in said gas supply connection and first operating winding means connected to said second thermostat to effect opening and closing of said first valve means, and second solenoid valve means including a second valve means disposed in said gas supply connection and having an open condition and a flow-restricting condition, and second operating winding means connected to said first thermostat for operating said second valve means between its open conditions.

Claim 8

Drying apparatus comprising: means defining a treatment zone for receiving material to be dried; a source of heat for providing thermal energy to said treatment zone; and means for operating said source of heat during a timed drying cycle at a plurality of output heating levels including first means, including a first thermostat, for operating said source of heat at a first heating output level during an initial portion of the cycle until a first predetermined temperature is attained in said treatment zone, and second means, including a second thermostat, for operating said source of heat at a second heating output level which is lower than the first heating output level to maintain a temperature which is lower than said first predetermined temperature during a subsequent portion of the drying cycle, said source of heat comprising a gas burner including a connection to a gas supply, first solenoid valve means having a first valve means disposed in said gas supply connection and first operating winding means connected to said second thermostat to effect opening and closing of said first valve means, and second solenoid valve means including a second valve means disposed in said gas supply connection and having an open condition and a flow-restricting condition, and second operating winding means connected to said first thermostat for operating said second valve means between its open conditions.