IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0296745
(2005-12-07)
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등록번호 |
US-7256372
(2007-08-14)
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발명자
/ 주소 |
- Knoeppel,Ray O.
- Van Sistine,Thomas G.
- Scott,Jason W. T.
- Morris,David E.
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출원인 / 주소 |
|
대리인 / 주소 |
Michael Best & Friedrich LLP
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인용정보 |
피인용 횟수 :
3 인용 특허 :
10 |
초록
▼
A fluid-heating apparatus for heating a fluid and method of operating the same. The fluid-heating apparatus includes a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source. The control circuit inc
A fluid-heating apparatus for heating a fluid and method of operating the same. The fluid-heating apparatus includes a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source. The control circuit includes a current path from the power source to the heating element back to the power source, a switch connected in the current path, and a current sensor. The method includes initiating a heating state of the fluid-heating apparatus, initiating a non-heating state of the fluid-heating apparatus, applying a voltage to the heating element during the non-heating state, sensing a leakage current of the heating element during the application of the voltage, and determining a degradation of the heating element with the sensed leakage current.
대표청구항
▼
What is claimed is: 1. A method of controlling a fluid-heating apparatus, the fluid-heating apparatus comprising a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source, the control circuit compri
What is claimed is: 1. A method of controlling a fluid-heating apparatus, the fluid-heating apparatus comprising a heating element for heating a fluid surrounding the heating element and a control circuit connected to the heating element and connectable to a power source, the control circuit comprising a current path from the power source to the heating element back to the power source, a switch connected in the current path, and a current sensor, the method comprising: initiating a heating state of the fluid-heating apparatus by establishing a current in the current path, the establishing act comprising making the switch to allow current in the current path; initiating a non-heating state and ceasing the heating state of the fluid-heating apparatus by ceasing the current in the current path, the ceasing act comprising breaking the switch to not allow current in the current path; applying a voltage to the heating element during the non-heating state; sensing a leakage current of the heating element during the application of the voltage; and determining a degradation of the heating element prior to a failure of the heating element with the sensed leakage current. 2. A method as set forth in claim 1 wherein the control circuit further comprises a second switch connected in the current path. 3. A method as set forth in claim 1 wherein the fluid-heating apparatus is a storage-type water heater, and the element is an electric-resistance heating element. 4. A method as set forth in claim 1 wherein the storage-type water heater comprises a tank, wherein the heating element comprises a connector assembly that secures the heating element to the tank, and wherein the connector assembly comprises a ground contact. 5. A method as set forth in claim 1 wherein the current path comprises a first leg connecting the power source to a first point of the heating element and a second leg connecting the power source to a second point of the heating element, wherein the switch is connected in circuit in the first and second legs, wherein applying a voltage to the heating element comprises applying the power source to the first point of the heating element thereby allowing a current in the first leg, and wherein sensing a leakage current comprises sensing a current in the second leg. 6. A method as set forth in claim 1 wherein the current path comprises a first leg connecting the power source to a first point of the heating element and a second leg connecting the power source to a second point of the heating element, wherein the switch is connected in circuit in the first leg, wherein applying a voltage comprises making the switch to a low-voltage power supply thereby allowing a current in a second current path from the low-voltage power supply to the first point of the heating element, and wherein sensing a leakage current comprises sensing a current in the second current path. 7. A method as set forth in claim 6 wherein the sensor is connected in circuit in the second current path. 8. A method as set forth in claim 1 wherein the method further comprises issuing an alarm when the determination indicates a degradation of the heating element. 9. A method as set forth in claim 1 wherein applying a voltage comprises intermittently applying a voltage to the heating element. 10. A method as set forth in claim 5 wherein the switch comprises a thermostat switch. 11. A method as set forth in claim 10 wherein the control circuit further comprises a voltage measurement circuit connected to the first leg and the second leg, wherein the voltage measurement circuit is connected to the first leg between the thermostat switch and the heating element, and wherein the method further comprises sensing a voltage with the voltage measurement circuit and determining the state of the fluid-heating apparatus based on the sensed voltage. 12. A method as set forth in claim 1 wherein the current sensor comprises a current transformer. 13. A method as set forth in claim 1 wherein the control circuit further comprises a microcontroller, and wherein the switch comprises a relay responsive to the microcontroller. 14. A method as set forth in claim 1 wherein the method further comprises determining a value representative of the leakage current, and wherein the determining act comprises determining whether the value is greater than a threshold indicative of the degradation. 15. A fluid-heating apparatus for heating a fluid, the fluid-heating apparatus being connectable to a power source, the fluid-heating apparatus comprising: a vessel; an inlet to introduce the fluid into the vessel; an outlet to remove the fluid from the vessel; a heating element at least partially surrounded by the fluid in the vessel, the heating element comprising a wire, an insulating material surrounding at least a portion of the wire, and a sheath surrounding at least a portion of the insulating material; a ground contact in electrical communication with the sheath; a control circuit connectable to the power source and connected to the heating element, the control circuit comprising a current path having a first leg connecting the power source to a first point of the heating element and a second leg connecting the power source to a second point of the heating element, a switch connected in circuit in the first leg, and a current sensor connected to the current path, the control circuit being configured to initiate a heating state of the fluid-heating apparatus by establishing a current in the current path, the establishing act comprising making the switch to allow current in the first current path, initiate a non-heating state and ceasing the heating state of the fluid-heating apparatus by ceasing the current in the current path, the ceasing act comprising breaking the switch to not allow current in the first current path, allow connection of the power source to the second point of the heating element during the non-heating state thereby allowing a current in the second leg during the non-heating state, sense a leakage current of the heating element during the connection of the power source to the second point of the heating element during the non-heating state; and determine a degradation of the heating element prior to a failure of the heating element with the sensed leakage current. 16. A fluid-heating apparatus as set forth in claim 15 wherein the fluid-heating apparatus is a storage-type water heater, wherein the vessel comprises a storage tank, and wherein the heating element is supported by the storage tank. 17. A fluid-heating apparatus as set forth in claim 16 wherein the heating element comprises a connector assembly that secures the heating element to the tank, and wherein the connector assembly comprises the ground contact. 18. A fluid-heating apparatus as set forth in claim 15 wherein the ground contact is in electrical communication with the sheath via the fluid. 19. A fluid-heating apparatus as set forth in claim 15 wherein the control circuit comprises a second switch connected in circuit of the second leg, wherein the control circuit is further configured to allow connection of the power source to the second point of the heating element thereby allowing a current in the second leg during the non-heating state by intermittently making the second switch. 20. A fluid-heating apparatus as set forth in claim 15 wherein the current sensor comprises a toroidal transformer sensing a current of the first and second legs. 21. A fluid-heating apparatus as set forth in claim 15 wherein the control circuit further comprises a speaker and wherein the control circuit is further configured to issue an alarm when the determination indicates a degradation of the heating element. 22. A fluid-heating apparatus as set forth in claim 15 wherein the switch comprises a thermostat switch. 23. A fluid-heating apparatus as set forth in claim 22 wherein the control circuit further comprises a voltage measurement circuit connected to the first leg and the second leg, wherein the voltage measurement circuit is connected to the first leg between the thermostat switch and the heating element, and wherein the control circuit is further configured to sense a voltage with the voltage measurement circuit and determine the state of the fluid-heating apparatus based on the sensed voltage. 24. A fluid-heating apparatus as set forth in claim 15 wherein the control circuit further comprises a microcontroller, and wherein the switch comprises a relay responsive to the microcontroller. 25. A fluid-heating apparatus for heating a fluid, the fluid-heating apparatus being electrically connectable to a power source, the fluid-heating apparatus comprising: a vessel; an inlet to introduce the fluid into the vessel; an outlet to remove the fluid from the vessel; a heating element at least partially surrounded by the fluid in the vessel, the heating element comprising a wire, an insulating material surrounding at least a portion of the wire, and a sheath surrounding at least a portion of the insulating material; a ground contact in electrical communication with the sheath; a control circuit connectable to the power source and connected to the heating element, the control circuit comprising a first current path having a first leg connecting the power source to a first point of the heating element and a second leg connecting the power source to a second point of the heating element, a switch connected in circuit in the first leg, a second current path connecting a low-voltage power supply to the heating element via the switch, and a current sensor connected to the second current path, the control circuit being configured to initiate a heating state of the fluid-heating apparatus by establishing a current in the first current path, the establishing act comprising making the switch to allow current in the first current path, initiate a non-heating state and ceasing the heating state of the fluid-heating apparatus by ceasing the current in the current path, connect the low-voltage power supply to the heating element during the non-heating state thereby allowing a current in the second current path during the non-heating state, sense a leakage current of the heating element during the connection of the low-voltage power supply to the heating element; and determine a degradation of the heating element prior to a failure of the heating element with the sensed leakage current. 26. A fluid-heating apparatus as set forth in claim 25 wherein the current sensor is connected in circuit in the second current path. 27. A fluid-heating apparatus as set forth in claim 25 wherein the fluid-heating apparatus is a storage-type water heater, wherein the vessel comprises a storage tank, and wherein the heating element is supported by the storage tank. 28. A fluid-heating apparatus as set forth in claim 27 wherein the heating element comprises a connector assembly that secures the heating element to the tank, and wherein the connector assembly comprises the ground contact. 29. A fluid-heating apparatus as set forth in claim 25 wherein the ground contact is in electrical communication with the sheath via the fluid. 30. A fluid-heating apparatus as set forth in claim 25 wherein the control circuit further comprises a speaker and wherein the control circuit is further configured to issue an alarm when the determination indicates a degradation of the heating element. 31. A fluid-heating apparatus as set forth in claim 25 wherein the switch comprises a thermostat switch. 32. A fluid-heating apparatus as set forth in claim 25 wherein the control circuit further comprises a microcontroller, and wherein the switch comprises a relay responsive to the microcontroller.
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