# US 4,450,691 A · Frost detecting device

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- Number: US 4,450,691 A
- Document ID: US4450691A
- Status: Granted
- Kind: A
- Application number: 06/435,286
- Filed: 1982-10-19
- Granted: 1984-05-29
- Earliest claimed: 1982-10-19
- Assignees: Dectron Inc.
- Inventors: John H. Taylor
- Web page: https://patentgrep.com/patent/US4450691A

## CPC

- F25D 21/02: Detecting the presence of frost or condensate
- F25B 2700/111: using an emitter and receiver, e.g. sensing by emitting light or other radiation and receiving reflection by a sensor
- F25D: REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR (refrigerated showcases A47F3/04; thermally-insulated vessels for domestic use A47J41/00; refrigerated vehicles, see the appropriate subclasses of classes B60 - B64; containers with thermal insulation in general B65D81/38; heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants, or materials for the production of heat or cold by chemical reactions other than by combustion C09K5/00; thermally-insulated vessels for liquefied or solidified gases F17C; air-conditioning or air-humidification F24F; refrigeration machines, plants, or systems F25B; cooling of instruments or comparable apparatus without refrigeration G12B)
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS

## Abstract

A frost detecting device for a refrigeration unit of the type having refrigeration coils and fins. The device is adapted to be mounted on the side of the unit with frost accumulating means projecting from the unit to contact at least one fin in a manner to accumulate frost thereon at about the same rate as the fin. The device carries means for detecting a predetermined amount of frost on the accumulating means, in order to activate a defrosting cycle.

## Claims

### Claim 1

A frost detecting device having:
a mounting block, the mounting block having one side face which is meant to be mounted against the edges of a plurality of refrigeration fins;
a recess in the mounting block between its ends, the recess extending inwardly into the mounting block from the one side face and located below the top face of the mounting block;
frost accumulating means fixed to the mounting block within the recess and projecting transversely outwardly from the recess past the one side face of the mounting block for surface contact with one of the refrigerator fins;
a radiation emitting means mounted in the mounting block on one side of the recess; radiation detecting means mounted in the mounting block on the other side of the recess opposite the radiation emitting means;
and passage means in that portion of the frost accumulating means within the recess for normally passing radiation between the radiation emitting and detecting means.

### Claim 2 (depends on 1)

A device as claimed in claim 1 wherein the frost accumulating means comprise a pair of parallel plates, spaced apart to tightly receive a fin of the refrigerating unit therebetween.

### Claim 3 (depends on 2)

A device as claimed in claim 2 wherein the passage means comprise a first narrow rectangular slot in one plate aligned with the radiation emitting and detecting means, and a second, wider rectangular slot in the other plate, centered with respect to the first slot.

### Claim 4 (depends on 3)

A device as claimed in claim 3 wherein the support is provided with a recess therein, the portions of the plates having the slots mounted within the recess.

### Claim 5 (depends on 3)

A device as claimed in claim 3 wherein the first slot has a width ranging between one and three-thirty seconds of an inch.

### Claim 6 (depends on 1)

A frost detecting device as claimed in claim 1 wherein the mounting block has rectangular cross-section and a length sufficient to extend across at least three successive fins.

### Claim 7 (depends on 1)

A frost detecting device as claimed in claim 1 including a bore through the block between its ends and above the recess for use in fastening the block tight against the fins.