Safety device and method for electric heating appliances

• US 8,710,406 B2
• Filed: 09/19/2008
• Issued: 04/29/2014
• Est. Priority Date: 09/19/2008
• Status: Active Grant

• Current Assignee: Conair LLC (Conair Corporation)
• Original Assignee: Conair Corporation
• Inventors: Sanders, Daniel Lee, Berera, Jonathan G
• Primary Examiner(s): FUQUA, SHAWNTINA T
• Application Number:
  US12/234,225
• Publication Number:
  US 20100073838A1
• Time in Patent Office: 2,048 Days
• Field of Search: 219/200, 219/240, 219/250, 219/251, 219/386, 219/419, 219/423, 219/481, 219/482, 219/507, 361/87, 361/94, 361/103, 361/93.9, 361/89, 307/31
• US Class Current: 219/200
• CPC Class Codes: A47J 37/0871 Accessories
• CPC Class Codes: H02J 2310/14 The load or loads being home appliances
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/242 Home appliances

Abstract

An appliance includes a plurality of electrical loads and a load control circuit including at least a clock enable circuit and a full power timer. The clock enable circuit is configured and operatively connected to activate the full power timer when all of the loads are energized, and the full power timer is configured and operatively connected to de-energize at least one load selected from the plurality of loads on reaching a predetermined full power time limit.

Claims

1. An over current protection circuit for an appliance, the circuit comprising:

a plurality of contacts for sensing a plurality of corresponding load currents;

a full power timer configured and operatively connected to reduce a total current I_avg in the appliance on reaching a full power time limit T₁; and

a clock enable circuit configured and operatively connected to operate the full power timer only while all of the contacts sense corresponding load currents.

2. The circuit according to claim 1, and further comprising:

a cycle timer configured to produce a cycle signal on reaching a cycle time limit T_cyc, and operatively connected to provide the cycle signal as a reset signal to the cycle timer and to the full power timer, the cycle timer further being configured to reset to a cycle reset value on receipt of the reset signal,

wherein the full power timer is operatively connected to receive the reset signal from the cycle timer and is configured to reset to a full power reset value on receipt of the reset signal.

3. The circuit according to claim 2, wherein the cycle time limit T_cyc is three hours.

4. The circuit according to claim 2, the full power timer having a reset pin for receiving the reset signal.

5. The circuit according to claim 2, the cycle timer having an output pin for providing the reset signal.

6. The circuit according to claim 2, wherein I_rated is a plug-rated current of the appliance, I_FP is a full power current draw of the appliance, and wherein the full power timer and the cycle timer are configured such that

T₁≦

T_cyc×

(1.6 I_rated−

I_FP)/I_FP.

7. The circuit according to claim 1, and further comprising:

a release circuit configured and operatively connected to receive a full power signal and to provide a control signal to de-energize a part of the appliance when the release circuit receives the full power signal,

wherein the full power timer is configured and operatively connected to provide the full power signal to a release circuit on reaching the full power time limit T₁.

8. The circuit according to claim 7, wherein the control signal forward biases a solenoid bypass transistor.

9. The circuit according to claim 7, wherein the part of the appliance is a heating element.

10. The circuit according to claim 7, wherein the part of the appliance is a solenoid.

11. An appliance comprising:

a plurality of electrical loads; and

a load control circuit including at least a clock enable circuit and a full power timer,

wherein the clock enable circuit is configured and operatively connected to activate the full power timer when all of the loads are energized, and the full power timer is configured and operatively connected to de-energize at least one load selected from the plurality of loads on reaching a predetermined full power time limit.

12. The appliance according to claim 11, wherein the load control circuit also includes a cycle timer configured and operatively connected to reset the cycle timer and the full power timer on reaching a cycle time limit.

13. The appliance according to claim 11, further comprising:

a carriage movable between an engaged position and a plurality of non-engaged positions;

a toast switch operable to energize the at least one selected heating element only when the carriage is in the engaged position; and

a solenoid operable to hold the carriage in the engaged position when the solenoid is energized, and to release the carriage from the engaged position when the solenoid is de-energized,

wherein the plurality of loads are heating elements, and the full power timer is operatively connected to de-energize at least one selected heating element by de-energizing the solenoid.

14. The appliance according to claim 13, further comprising a transistor operatively connected to divert current from the solenoid, wherein the full power timer is operatively connected to de-energize the solenoid by forward-biasing the transistor.