Refrigeration module

• US 5,809,789 A
• Filed: 05/07/1997
• Issued: 09/22/1998
• Est. Priority Date: 05/07/1997
• Status: Expired due to Term

• Current Assignee: Philip L. Baker, Thomas E. Wrenn
• Original Assignee: Philip L. Baker, Thomas E. Wrenn
• Inventors: Baker, Philip L., Wrenn, Thomas E.
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US08/852,582
• Time in Patent Office: 503 Days
• Field of Search: 62/80, 62/81, 62/151, 62/155, 62/156, 62/234, 62/128, 62/140, 62/278, 62/277
• US Class Current: 62/81
• CPC Class Codes: F25B 2400/21 Modules for refrigeration systems
• CPC Class Codes: F25B 2600/23 Time delays
• CPC Class Codes: F25B 2700/21162 of the refrigerant at the inlet of the condenser
• CPC Class Codes: F25B 2700/21163 of the refrigerant at the outlet of the condenser
• CPC Class Codes: F25B 2700/21174 of the refrigerant at the inlet of the evaporator
• CPC Class Codes: F25B 2700/21175 of the refrigerant at the outlet of the evaporator
• CPC Class Codes: F25B 47/022 hot gas defrosting
• CPC Class Codes: F25D 19/00 Arrangement or mounting of refrigeration units with respect to devices or objects to be refrigerated, e.g. infrared detectors
• CPC Class Codes: F25D 21/002 Defroster control
• CPC Class Codes: F25D 2700/02 Sensors detecting door opening
• CPC Class Codes: F25D 2700/12 Sensors measuring the inside temperature
• CPC Class Codes: F25D 2700/14 Sensors measuring the temperature outside the refrigerator or freezer

Abstract

A refrigeration module removably suitable for use in either a refrigerator or a freezer uses signals from a series of temperature sensors for refrigeration control. An automatic defrost cycle is initiated when the evaporator outlet temperature drops to a value equal to the inlet temperature and is accompanied by a constant or rising temperature in the refrigerated cabin to which the module is connected. Field service is limited to an exchange of modules, so that refrigerating gas is not lost into the environment.

Claims

1. A self-contained refrigeration module comprising:

(a) A cabinet provided with a cold air outlet port, a cold air return port, an ambient air supply port and an ambient air discharge port;

(b) Insulative wall means defining a cold compartment within said cabinet, said cold compartment being in communication with said cold air outlet port and with said cold air return port and being isolated from said ambient air supply port and from said ambient air discharge port;

(c) Fan means mounted inside said cabinet for causing a flow of ambient air along a first path from said ambient air supply port to said ambient air discharge port and a flow of cold air along a second path from said cold air return port to said cold air outlet port;

(d) A compressor mounted inside said cabinet and outside said cold compartment for compressing a refrigerating gas;

(e) A condenser mounted inside said cabinet across said first path for receiving compressed refrigerating gas from said compressor and condensing said compressed refrigerating gas into a refrigerating liquid;

(f) An evaporator mounted inside said cold compartment across said second path, for receiving refrigerating liquid from said condenser and vaporizing said refrigerating liquid to produce a cold refrigerating gas, said evaporator being provided with heat transfer surfaces for transferring heat from said cold air to said cold refrigerating gas thereby generating a spent refrigerating gas for return to said compressor;

(g) A first temperature sensor for generating a first temperature signal corresponding to the temperature of said cold refrigerating gas;

(h) A second temperature sensor for generating a second temperature signal corresponding to the temperature of said spent refrigerating gas;

(i) A third temperature sensor for generating a third temperature signal corresponding to the temperature of said second flow of air at said cold air return port;

(j) A heater valve for defrosting said evaporator by selectively directing compressed refrigerating gas thereto; and

(k) Computing means for controlling said heater valve to direct said compressed refrigerating gas to said evaporator when said first and second temperature signals differ from each other by less than a predetermined minimum amount, and said third temperature signal increases more than a predetermined maximum amount in a predetermined time.

2. A method of defrosting an evaporator having a cold refrigerating gas flowing therethrough and positioned within a stream of cold, flowing air for transferring heat from said air into said gas, said method comprising the steps of:

(1) Measuring a spatial change in a temperature of said gas at different locations within said evaporator;

(2) Measuring a temporal change in a temperature of said air at a fixed location within said stream; and

(3) Supplying hot refrigerating gas to said evaporator when said spatial change is less than a predetermined amount and said temporal change is not negative.

3. A method according to claim 2 further comprising the step of terminating said supplying when temperatures greater than predetermined amounts are measured at said different locations.