Defrost delay module

• US 6,694,753 B1
• Filed: 07/16/2002
• Issued: 02/24/2004
• Est. Priority Date: 07/17/2001
• Status: Expired due to Term

• Current Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Original Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Inventors: Lanz, Douglas C., Johncock, James C.
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US10/196,536
• Time in Patent Office: 588 Days
• Field of Search: 621/51, 621/54, 621/55, 621/56, 622/34, 621/58, 621/57, 622/30, 307/35, 307/39
• US Class Current: 62/155
• CPC Class Codes: F25B 2600/23 Time delays
• CPC Class Codes: F25D 21/006 with electronic control circuits
• CPC Class Codes: F25D 21/08 by electric heating

Abstract

A device and method for automatically defrosting a refrigeration system only during times of non-peak energy demand. The device is a defrost delay module that plugs into the current defrost timer supplied with frost-free refrigerators. The defrost delay module includes a microprocessor that utilizes a clock to define peak power consumption periods. If the defrost cycle will occur during a peak power period, the delay module interrupts the normal operation and prevents defrosting of a refrigerator or freezer until the peak power periods has passed. The delay module is able to learn the operating characteristics of the defrost timer such that the delay module can be retrofit to existing appliances.

Claims

1. A method of controlling the operation of a refrigerator having a defrost timer that supplies power to a compressor during a cooling cycle and supplies power to a defrost heater during a defrost cycle, the method comprising the steps of:

positioning a delay module between the defrost timer and both the compressor and the defrost heater;

defining a peak demand period in the delay module; and

activating the delay module to prevent the defrost timer from beginning the defrost cycle when the defrost cycle will begin during the peak demand period.

2. The method of claim 1 further comprising the step of keeping the current time within the delay module such that the delay module will prevent the defrost timer from beginning the defrost cycle when the current time is during the peak demand period.

3. The method of claim 1 wherein the defrost timer includes a timer motor that controls the length of the cooling cycle and the defrost cycle, wherein the delay module interrupts the supply of power to the timer motor to prevent the beginning of the defrost cycle.

4. The method of claim 1 further comprising the steps of:

monitoring the length of time the defrost timer operates the compressor during the cooling cycle;

monitoring the length of time the defrost timer operates the defrost heater in the defrost cycle; and

anticipating the beginning of the defrost cycle based upon the monitored length of the current cooling cycle and preventing the beginning of the defrost cycle when the anticipated beginning of the defrost cycle is during the peak demand period.

5. The method of claim 4 further comprising the step of resupplying power to the timer motor of the defrost timer when the current time falls outside of the peak demand period such that the defrost timer can trigger the defrost cycle.

6. A method of controlling the operation of a refrigerator having a defrost timer that supplies power to a compressor during a cooling cycle and supplies power to a defrost heater during a defrost cycle, the method comprising the steps of:

positioning a delay module between the defrost timer and both the compressor and the defrost heater, the delay module including a microprocessor configured to keep a current time within the delay module;

defining a peak demand period in the delay module;

determining in the delay module the length of time the defrost timer operates the compressor during the cooling cycle;

determining in the delay module the length of time the defrost timer operates the defrost heater in the defrost cycle;

monitoring the operation of the defrost timer;

anticipating the beginning of the defrost cycle; and

preventing the defrost timer from beginning the defrost cycle when the defrost cycle will begin during the peak demand period.

7. The method of claim 6 wherein the defrost timer includes a timer motor that controls the length of the cooling cycle and the length of the defrost cycle, wherein the delay module interrupts the supply of power to the timer motor to prevent the beginning of the defrost cycle.

8. The method of claim 7 further comprising the step of resupplying power to the timer motor of the defrost timer when the current time of outside of the peak demand period such that the defrost timer can trigger the defrost cycle.

9. The method of claim 6 wherein the step of determining the length of time of the cooling cycle and the length of time of the defrost cycle comprises the steps of:

monitoring the length of time of both the cooling cycle and the defrost cycle for an initialization period;

storing the length of time the defrost timer operates the compressor during the cooling cycle in the microprocessor; and

storing the length of time the defrost timer operates the defrost heater in the defrost cycle in the microprocessor.

10. The method of claim 9 wherein the initialization period is two cooling cycles and two defrost cycles.

11. The method of claim 10 wherein the defrost delay module includes a latching device operable between an open state and a closed state and the step of interrupting power to the timer motor includes moving the latching device to the open state.