Heating Circuit with Monitoring Arrangement for a Household Appliance

• US 20130119047A1
• Filed: 04/26/2011
• Published: 05/16/2013
• Est. Priority Date: 05/14/2010
• Status: Active Grant

• Current Assignee: Electrolux Home Products Incorporated (AB Electrolux)
• Original Assignee: Electrolux Home Products Incorporated (AB Electrolux)
• Inventors: Lorenzi, Marco, Driussi, Paolo
• Granted Patent: US 10,136,473 B2
• Time in Patent Office: Days
• US Class Current: 219/507
• CPC Class Codes: D06F 2103/40 Opening or locking status of doors
• CPC Class Codes: D06F 2103/44 Current or voltage
• CPC Class Codes: D06F 2105/28 Electric heating
• CPC Class Codes: D06F 2105/58 Indications or alarms to the control system or to the user
• CPC Class Codes: D06F 33/46 Control of the energy or water consumption
• CPC Class Codes: D06F 33/47 Responding to irregular working conditions, e.g. malfunctioning of pumps safety arrangements D06F37/42
• CPC Class Codes: D06F 34/08 Control circuits or arrangements thereof
• CPC Class Codes: D06F 37/42 Safety arrangements, e.g. for stopping rotation of the receptacle upon opening of the casing door
• CPC Class Codes: D06F 39/04 Heating arrangements
• CPC Class Codes: D06F 58/50 Responding to irregular working conditions, e.g. malfunctioning of blowers
• CPC Class Codes: H05B 3/02 Details

Abstract

A washing and/or drying appliance includes a heating circuit (140) for heating a washing liquid and/or a drying air flow. The heating circuit is connected to voltage distribution lines (105a,105b) distributing power inside the appliance and includes at least one heating resistor (205) in series to switch means (210a,210b) controlled by an appliance control unit (125) for selectively energizing the heating resistor when required. The switch means of the heating circuit includes first and second switches (210a,210b) in series to the heating resistor, the heating resistor being interposed between the first and second switch. A monitoring circuit arrangement is associated with the heating circuit. The monitoring circuit arrangement includes a resistive network including a first resistor (R1) connected to the heating circuit so as to be bypassed when the first switch is closed, the heating resistor, and a second resistor (R2) connected to the heating circuit so as to be bypassed when the second switch is closed. The monitoring circuit arrangement further includes a current sensor (240) arranged to measure a current flowing through the resistive network and to feed an indication of the measured current to the control unit. The monitoring unit is configured for assessing possible faults of the heating circuit based on the indication of the measured current.

Claims

1. A washing and/or drying appliance, comprising a heating circuit for heating a washing liquid and/or a drying air flow, the heating circuit being connected to voltage distribution lines distributing power inside the appliance and comprising at least one heating resistor in series to switch means controlled by an appliance control unit for selectively energizing the heating resistor when required, wherein:

the switch means of the heating circuit comprise first and second switches in series to the heating resistor, the heating resistor being interposed between the first and second switches;

a monitoring circuit arrangement is associated with the heating circuit, said monitoring circuit arrangement comprising a resistive network including a first resistor connected to the heating circuit so as to be bypassed when the first switch is closed, the heating resistor, and a second resistor connected to the heating circuit so as to be bypassed when the second switch is closed, the monitoring circuit arrangement further comprising a current sensor arranged to measure a current flowing through the resistive network and to feed an indication of the measured current to the control unit, and

the monitoring unit is configured for assessing possible faults of the heating circuit based on the indication of the measured current.

2. The appliance of claim 1, further comprising a main switch controlled by the control unit for selectively allowing the powering of the appliance, wherein the heating circuit is connected to the voltage supply lines upstream or downstream the main switch with respect to an AC voltage plug of the appliance.

3. The appliance of claim 2, wherein said main switch is switchable to close only conditioned to the fact that the control unit detects that an appliance door is closed.

4. The appliance of claim 2, wherein said resistive network of the monitoring circuit arrangement is connected to the voltage distribution lines either downstream or upstream the main switch.

5. The appliance of claim 1, wherein the resistive network further comprises a third resistor connected in shunt to the heating resistor and having a resistance value substantially higher than the heating resistor resistance value.

6. The appliance of claim 1, wherein said current sensor comprises a resistor in series to the first and/or second resistors.

7. The appliance of claim 1, wherein said current sensor comprises one among an amperometric transformer or a Hall sensor.

8. The appliance of claim 1, wherein the first resistor has a first terminal coupled to a first one of the voltage distribution lines and a second terminal connected to a first terminal of the heating resistor which is coupled to said first one of the voltage distribution lines, and the second resistor has a first terminal connected to a second terminal of the heating resistor opposite the first heating resistor terminal and a second terminal coupled to a second one of the voltage distribution lines.

9. The appliance of claim 1, wherein the first resistor has a first terminal coupled to a first one of the voltage distribution lines and a second terminal connected to a second terminal of the heating resistor which is coupled to a second one of the voltage distribution lines, and the second resistor has a first terminal connected to a first terminal of the heating resistor which is coupled to the first voltage distribution lines and a second terminal coupled to the second voltage distribution line.

10. The appliance of claim 3, wherein said resistive network of the monitoring circuit arrangement is connected to the voltage distribution lines either downstream or upstream the main switch.

11. The appliance of claim 2, wherein the resistive network further comprises a third resistor connected in shunt to the heating resistor and having a resistance value substantially higher than the heating resistor resistance value.

12. The appliance of claim 3, wherein the resistive network further comprises a third resistor connected in shunt to the heating resistor and having a resistance value substantially higher than the heating resistor resistance value.

13. The appliance of claim 4, wherein the resistive network further comprises a third resistor connected in shunt to the heating resistor and having a resistance value substantially higher than the heating resistor resistance value.

14. The appliance of claim 2, wherein said current sensor comprises a resistor in series to the first and/or second resistors.

15. The appliance of claim 3, wherein said current sensor comprises a resistor in series to the first and/or second resistors.

16. The appliance of claim 4, wherein said current sensor comprises a resistor in series to the first and/or second resistors.

17. The appliance of claim 5, wherein said current sensor comprises a resistor in series to the first and/or second resistors.

18. The appliance of claim 2, wherein the first resistor has a first terminal coupled to a first one of the voltage distribution lines and a second terminal connected to a first terminal of the heating resistor which is coupled to said first one of the voltage distribution lines, and the second resistor has a first terminal connected to a second terminal of the heating resistor opposite the first heating resistor terminal and a second terminal coupled to a second one of the voltage distribution lines.

19. The appliance of claim 5, wherein the first resistor has a first terminal coupled to a first one of the voltage distribution lines and a second terminal connected to a first terminal of the heating resistor which is coupled to said first one of the voltage distribution lines, and the second resistor has a first terminal connected to a second terminal of the heating resistor opposite the first heating resistor terminal and a second terminal coupled to a second one of the voltage distribution lines.

20. The appliance of claim 2, wherein the first resistor has a first terminal coupled to a first one of the voltage distribution lines and a second terminal connected to a second terminal of the heating resistor which is coupled to a second one of the voltage distribution lines, and the second resistor has a first terminal connected to a first terminal of the heating resistor which is coupled to the first voltage distribution lines and a second terminal coupled to the second voltage distribution line.