Temperature maintaining apparatus and temperature control apparatus and method therefor

• US 20040007628A1
• Filed: 07/15/2002
• Published: 01/15/2004
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Marine Canada Acquisition Inc. (Dometic Group AB)
• Original Assignee: Teleflex Canada Limited Partnership
• Inventors: Young, Jonathan, Paul, Douglas Thompson, Faccone, Angelo
• Granted Patent: US 6,766,962 B2
• Time in Patent Office: Days
• US Class Current: 236/78D
• CPC Class Codes: G05D 23/1917 using digital means
• CPC Class Codes: G05D 23/1951 with control of the working time of a temperature controlling device

Abstract

A method and apparatus are provided for maintaining a temperature between a first value and a second value. The method and apparatus utilize a heat transfer device capable of cycling through a series of cycles, the device being capable of changing the temperature from the second value to the first value when operational. During each cycle the device transfers heat for a first period of time when the temperature reaches the second volume until the first value is reached and thereafter the device stops transferring heat. The first period of time is compared to a desired cycle-on period of time during each cycle and the second temperature value then is adjusted for a subsequent cycle of the device so the first period of time when the device transfers heat approaches the desired cycle-on period of time. There may also be provided temperature controls for a liquid heater having a jacket containing the liquid. The jacket has an inner heated wall and an outer wall spaced apart from the inner wall. The controls include a temperature sensor capable of fitting to the jacket so that the sensor contacts the inner wall and the liquid. A control module monitors temperature sensed by the temperature sensor. The control module causes the heater to stop heating when the temperature is heated by the heater to a first value and causes the heater to heat when the liquid cools to a second value lower than the first value. The control module senses overheating when temperature sensed by the sensor increases to a third value, higher than the first value, when the heater is not heating, and then causes the heater to shut down.

Claims

1. A method of maintaining a temperature between a first temperature value and a second, variable temperature value, the method utilizing a heat transfer device capable of cycling through a series of cycles, the device being capable of changing the temperature from the second value to the first value when operational, during each said cycle the device transferring heat for a first period of time when the temperature reaches the second value until the first value is reached and thereafter the device ceasing to transfer heat, said first period of time being compared to a desired cycle-on period of time during each said cycle and said second value then being adjusted for a subsequent cycle of the device so said first period of time when the device transfers heat approaches said desired cycle-on period of time.

2. The method as claimed in claim 1, wherein the device is a heater and the first value is higher than the second value.

3. The method as claimed in claim 2, wherein the heater has a burner, the burner becoming operational when the second temperature value is reached and becomes nonoperational when the first temperature value is reached.

4. The method as claimed in claim 3, the device being a fluid heater and the first value, and the second value being temperatures of a fluid heated by the heater.

5. The method as claimed in claim 4, wherein the fluid is an aqueous solution including water and anti-freeze.

6. The method as claimed in claim 5, wherein the heater is a transit vehicle heater.

7. The method as claimed in claim 3, wherein the second temperature value is increased after each cycle where the first period of time exceeds the desired cycle-on period of time.

8. The method as claimed in claim 7, wherein the second temperature value is decreased after each cycle where the desired cycle-on period of time exceeds the first period of time.

9. The method as claimed in claim 3, wherein the heater becomes operational for another cycle after the heater is nonoperational for a preselected period of time, whether or not the second temperature is reached.

10. An apparatus for maintaining a temperature between a first temperature value and a second temperature value, the apparatus including a heat transfer device capable of cycling through a series of cycles, the device being capable of changing the temperature from the second value to the first value when operational, and controls which control the device so during each said cycle the device transferring heat for a first period of time when the temperature reaches the second temperature value until the first value is reached and thereafter the device ceases transferring heat, said controls comparing the first period of time to a desired cycle-on period of time during each said cycle and said controls adjusting the second temperature value for a subsequent cycle of the device so said first period of time when the device transfers heat approaches said desired cycle-on period of time.

11. The apparatus as claimed in claim 10, wherein the device is a heater and the first value is higher than the second value.

12. The apparatus as claimed in claim 11, wherein the heater has a burner, the burner becoming operational when the second temperature value is reached and becomes nonoperational when the first temperature value is reached.

13. The apparatus as claimed in claim 13, the device being a fluid heater and the first value and the second value being temperatures of a fluid heated by the heater.

15. The apparatus as claimed in claim 13, wherein the heater is a transit vehicle heater.

16. The apparatus as claimed in claim 13, wherein the controls increase the second temperature value after each cycle where the first period of time exceeds the desired cycle-on period of time.

18. The apparatus as claimed in claim 13, wherein the controls cause the heater to become operational for another cycle after the heater is nonoperational for a preselected period of time, whether or not the second temperature value is reached.

14. The apparatus as claimed in claim 14, wherein the fluid is an aqueous solution including water and anti-freeze.

17. The apparatus as claimed in claim 17, wherein the controls decrease the second temperature value after each cycle where the desired cycle-on period of time exceeds the first period of time.

19. A heater for a liquid including controls for maintaining a temperature of the liquid between a first value and a second lower value, the heater being capable of cycling through a series of cycles, the controls controlling the heater so during each said cycle the heater heats for a first period of time when the liquid cools to the second temperature value until the liquid is heated to the first value and thereafter the heater stops heating, said controls comparing the first period of time to a desired cycle-on period of time during each said cycle and said controls adjusting the second temperature value for a subsequent cycle of the device so said first period of time when the heater heats approaches said desired cycle-on period of time.

20. The heater as claimed in claim 19, wherein the heater has a burner, the burner becoming operational when the second temperature value is reached and becomes nonoperational when the first temperature value is reached.

21. The heater as claimed in claim 19, wherein the liquid is an aqueous solution including water and anti-freeze.

22. The heater as claimed in claim 19, wherein the heater is a transit vehicle heater.

23. The heater as claimed in claim 19, wherein the controls increase the second temperature value after each cycle where the first period of time exceeds the desired cycle-on period of time.

24. The heater as claimed in claim 19, wherein the controls decrease the second temperature value after each cycle where the desired cycle-on period of time exceeds the first period of time.

25. The heater as claimed in claim 19, wherein the controls cause the heater to commence heating for another cycle after the heater has stopped heating for a preselected period of time, whether or not the second temperature value is reached.

26. The heater as claimed in claim 19, wherein the controls include a temperature sensor.

27. The heater as claimed in claim 19, wherein the controls include a programmable control module.

28. A control system for a heat transfer device, the control system maintaining a temperature between a first value and a variable second value, the heat transfer device being capable of cycling through a series of cycles, the device being capable of changing the temperature from the second value to the first value, the control system controlling the device so during each said cycle the device transfers heat for a first period of time when the temperature reaches the second temperature value until the first value is reached and thereafter the device stops transferring heat, said controls comparing the first period of time to a desired cycle-on period of time during each said cycle and said control system adjusting the second temperature value for a subsequent cycle of the device so said first period of time when the device transfers heat approaches said desired cycle-on period of time.

29. The control system as claimed in claim 28, wherein the device is a heater and the first value is higher than the second value.

30. The control system as claimed in claim 28, wherein the heater has a burner, the burner becoming operational when the second temperature value is reached and becomes nonoperational when the first temperature value is reached.

31. The control system as claimed in claim 30, the device being a fluid heater, the first value and the second value being temperatures of a fluid heated by the heater.

32. The control system as claimed in claim 28, wherein the heater is a transit vehicle heater.

33. The control system as claimed in claim 28, wherein the control system increases the second temperature value after each cycle where the first period of time exceeds the desired cycle-on period of time.

34. The control system s as claimed in claim 28, wherein the control system decreases the second temperature value after each cycle where the desired cycle-on period of time exceeds the first period of time.

35. The control system as claimed in claim 28, wherein the control system causes the heater to heat for another cycle after the heater stops heating for a preselected period of time, whether or not the second temperature value is reached.

36. The control system as claimed in claim 28, including a temperature sensor and a programmable control module.

37. Temperature controls for a liquid heater having a jacket containing the liquid, the jacket having an inner heated wall and an outer wall spaced apart from the inner wall, the controls including a temperature sensor capable of fitting to the jacket so that the sensor contacts the inner wall and the liquid, and a control module which monitors temperature sensed by the temperature sensor, the control module causing the heater to stop heating when the temperature is heated by the heater to a first temperature value and causing the heater to heat when the liquid cools to a temperature second value, the control module sensing overheating when a temperature sensed by the sensor increases to a third temperature value, higher than the first value, when the heater is not heating, and then causing the heater to shut down.

38. A heater for a liquid, the heater having a jacket containing the liquid, the jacket having an inner heated wall and an outer wall spaced apart from the inner wall, and temperature controls operatively connected thereto, the controls including a temperature sensor capable of fitting to thejacket so that the sensor contacts the inner wall and the liquid, and a control module which monitors temperature sensed by the temperature sensor, the control module causing the heater to stop heating when the temperature is heated by the heater to a first temperature value and causing the heater to heat when the liquid cools to a second temperature value, the control module sensing overheating when a temperature sensed by the sensor increases to a third temperature value, higher than the first temperature value, when the heater is not heating, and then causing the heater to shut down.

39. The liquid heater as claimed in claim 38, wherein the sensor has a resiliently biased tip which contacts the inner wall.

40. A method of controlling temperature for a liquid heater having a jacket containing the liquid, the jacket having an inner heated wall and an outer wall spaced apart from the inner wall, the method including fitting a temperature sensor to the jacket so that the sensor contacts the inner wall and the liquid, monitoring temperature sensed by the temperature sensor, causing the heater to stop heating when the temperature is heated by the heater to a first temperature value and causing the heater to heat when the liquid cools to a second temperature value lower than the first value, detecting when temperature sensed by the sensor increases to a third value, higher than the first value, when the heater is not heating, treating said third value as an overheat condition and then causing the heater to shut down.

41. A temperature control apparatus for a liquid heater having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet for liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater having a first temperature sensor adjacent to said one fitting and a second temperature sensor adjacent to said another fitting, the apparatus including a memory having values for a first temperature value, where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value, higher than the first value, where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and one of the sensors also sensing the third temperature value, and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the second temperature value and the first temperature value and a low condition when a temperature is less than the second temperature value, the apparatus indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the third temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value.

42. The apparatus as claimed in claim 41, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the apparatus indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value.

43. The apparatus as claimed in claim 41, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the apparatus indicating the faulted condition when either sensor exceeds the short threshold or is less than the open threshold, the overheat condition being indicated when either of the sensors exceeds the third temperature value, but does not indicate the faulted condition.

46. The method as claimed in claim 41, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the faulted condition being indicated when either sensor exceeds the short threshold or is less than the open threshold, the overheat condition being indicated when either of the sensors exceeds the overheat temperature, but does not indicate the faulted condition.

44. A method of controlling temperatures in a liquid heater having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet for liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater having a first temperature sensor adjacent to said one fitting and a second temperature sensor adjacent to said another fitting, the method including retaining values for a first temperature, where the heater stops heating, a second temperature where the heater commences heating, and a third temperature where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and one of the sensors also sensing the third temperature value, comparing temperature readings from each of the sensors with each of the second temperature value, the first temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the second temperature value and the first temperature value and a low condition when a temperature is less than the second temperature value, the overheat condition being indicated when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the overheat temperature, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value.

45. The method as claimed in claim 44, wherein the second temperature value is varied between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the warm condition being indicated when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value.

47. A temperature control apparatus for a liquid heater having a first temperature sensor and a second temperature sensor, the apparatus including a memory having values for a first temperature, where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value where the heater is shut off, and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, both sensors being capable of sensing the first temperature value and the second temperature value and one of the sensors also sensing the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the apparatus indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value.

48. The apparatus as claimed in claim 47, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the apparatus indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value.

49. The apparatus as claimed in claim 47, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the apparatus indicating the faulted condition when both of the sensors indicate a faulted condition, whereby the heater is operational when only one sensor is present or if one of the sensors is faulted.

50. A method of controlling temperatures in a liquid heater, the heater having a first temperature sensor and a second temperature sensor, the method including retaining values for a first temperature value, where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and one of the sensors also sensing the third temperature value, comparing temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the overheat condition being indicated when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicate temperatures less than the second temperature value.

51. The method as claimed in claim 50, wherein the second temperature value is varied between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the warm condition being indicated when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value.

52. The method as claimed in claim 50, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the third temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the faulted condition being indicated when either sensor exceeds the short threshold or is less than the open threshold, the faulted condition being indicated when both of the sensors indicate a faulted condition, whereby the heater is operational when only one sensor is present or if one of the sensors is faulted.

53. A heater for liquids having two fittings for connecting liquid conduits to the heater, one of the fittings being either an inlet or an outlet for liquid, another of the fittings being another of the inlet or the outlet for the liquid, the heater having a first temperature sensor adjacent to said one fitting and a second temperature sensor adjacent to said another fitting, the heater including a memory having values for a first temperature value, where the heater stops heating, a second temperature value where the heater commences heating, and an overheat temperature where the heater is shut off, both sensors being capable of sensing the first temperature value and the second temperature value and one of the sensors also sensing the third temperature value, and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the apparatus indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicates temperatures less than the second temperature value.

54. The heater as claimed in claim 53, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the apparatus indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the first temperature value.

55. The heater as claimed in claim 53, wherein the heater has a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the their temperature value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the apparatus indicating the faulted condition when either sensor exceeds the short threshold or is less than the open threshold, the overheat condition being indicated when either of the sensors exceeds the third temperature value, but does not indicate the faulted condition.

56. A heater for liquids having a first temperature sensor and a second temperature sensor, a memory having values for a first temperature value, where the heater stops heating, a second temperature value where the heater commences heating, and a third temperature value where the heater is shut off, both sensors being capable of sensing the first amateur value and a second temperature value and one of the sensors also sensing the third temperature value, and controls which compare temperature readings from each of the sensors with each of the first temperature value, the second temperature value and the third temperature value, the heater having an overheat condition when a temperature exceeds the third temperature value, a high condition when a temperature exceeds the first temperature value, a normal condition when a temperature is between the first temperature value and the second temperature value and a low condition when a temperature is less than the second temperature value, the controls indicating the overheat condition when one of the sensors indicates a temperature exceeding the third temperature value, the high condition when either sensor indicates a temperature exceeding the first temperature value, but neither sensor indicates a temperature exceeding the third temperature value, the normal condition when either sensor indicates a temperature exceeding the second temperature value, but neither sensor indicates a temperature exceeding the first temperature value, and a low condition when both sensors indicates temperatures less than the second temperature value.

57. The heater as claimed in claim 56, wherein the second temperature value is variable between a minimum cycle-on temperature and a maximum cycle-on temperature, the heater having a warm condition when a temperature exceeds the maximum cycle-on temperature, the controls indicating the warm condition when one of the sensors indicates a temperature exceeding the maximum cycle-on temperature, but neither sensor indicates a temperature exceeding the second temperature value.

58. The heater as claimed in claim 56, having a faulted condition when a temperature reading exceeds a short threshold which indicates a short circuit, the short threshold exceeding the the attempt or value, or when a temperature reading is less than an open threshold which indicates an open circuit, the open threshold being less than the minimum cycle-on temperature, the controls indicating the faulted condition when both of the sensors indicate a faulted condition, whereby the heater is operational when only one sensor is present or if one of the sensors is faulted.

59. A heater for a liquid including a temperature sensor and controls for maintaining a temperature of the liquid between a first value and a second lower value, the heater being capable of cycling through a series of cycles, the controls controlling the heater so during each said cycle the heater commences heating when the temperature sensor indicates that the temperature has decreased to the lower value, the controls indicating a temperature sensor error if the temperature indicated by the sensor does not increase by a specified amount within a specified time after the heater commences heating.

60. A method of detecting a temperature sensor error in a heater for a liquid including a temperature sensor and controls for maintaining a temperature of the liquid between a first value and a second lower value, the heater being capable of cycling through a series of cycles, the controls controlling the heater so during each said cycle the heater commences heating when the temperature sensor indicates that the temperature has decreased to the lower value, the controls indicating a temperature sensor error if the temperature indicated by the sensor does not increase by a specified amount within a specified time after the heater commences heating.