Refrigeration system

• US 5,729,990 A
• Filed: 11/06/1996
• Issued: 03/24/1998
• Est. Priority Date: 05/26/1994
• Status: Expired due to Fees

• Current Assignee: Danfoss A/S
• Original Assignee: Danfoss A/S
• Inventors: Basse, Tage Stenberg, Decovski, Vladimir
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US08/737,617
• Time in Patent Office: 503 Days
• Field of Search: 62/130, 62/125, 62/126, 62/128, 62/129, 62/285, 62/288, 62/289, 340/608, 340/616, 340/618, 340/622
• US Class Current: 62/128
• CPC Class Codes: F25D 21/14 Collecting or removing condensed and defrost water; Drip trays
• CPC Class Codes: G01F 23/241 for discrete levels
• CPC Class Codes: G01F 23/247 for discrete levels

Abstract

A refrigeration system having at least one defrostable cold-production device is disclosed, beneath which device a drip tray provided with a drain channel is arranged. In such a refrigeration system, it is desirable to reduce the risk of flooding because of a blocked drain channel. For that purpose, a liquid sensor which detects the presence of liquid at a level above the drain channel is provided in the drip tray.

Claims

1. A refrigerating system having at least one defrostable cold-production device, beneath which device a drip tray provided with a drain channel is arranged, in which tray a temperature dependent resistor is located as a liquid sensor, electric power being provided to said resistor to heat it and means being provided for determining a change in resistance value of the temperature dependent resistor in dependence on defrost water level in the drip tray, and including a control device having means to determine the temperature at the liquid sensor at at least two different times and to compare the temperatures with one another.

2. A refrigeration system according to claim 1, in which the liquid sensor is surrounded by a protective guard.

3. A refrigeration system according to claim 2, in which the protective guard is in the form of a capsule having a wall which has openings for the passage of ice and/or water.

4. A refrigeration system according to claim 1, in which the control device has a memory for a first temperature value, a divider for forming a quotient from a second temperature value and the first temperature value, and a comparator, which produces an alarm signal when the quotient exceeds or falls below a predetermined value.

5. A refrigeration system according to claim 1, in which the control device includes a timer which initiates a measuring cycle at predetermined intervals.

6. A refrigeration system according to claim 1, in which the control device also includes means to control the heating of the liquid sensor.

7. A refrigeration system according to claim 1, in which the means to determine takes one measurement in an unheated state and another measurement at the end of a heating period of predetermined length.

8. A refrigeration system according to claim 7, in which the heating period lasts for about 3 minutes.

9. A refrigeration system according to claim 7, in which measurement takes place in the unheated state prior to measurement at the end of the heating period.

10. A refrigeration system according to claim 7, in which measurement in the unheated state takes place a predetermined time after the end of the heating period.

11. A refrigeration system according to claim 10, in which the predetermined time is about 1 minute.

12. A refrigeration system according to claim 7, in which three measurements are taken, a middle measurement being taken at the end of the heating period and the other two measurements being taken before and after without heating.

13. A refrigeration system according to claim 1, in which measurements are taken outside a defrosting period for the cold-production device.

14. A refrigeration system according to claim 1, in which the liquid sensor is fixedly adhesively secured in the drip tray by a layer of adhesive.