JPH0156357B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frost detection device that optically detects frost adhering to an evaporator of a refrigerator or the like.

Generally, frost adhering to the evaporator of a refrigerator or other freezer is removed by defrosting at regular intervals based on the cumulative operation time of the compressor. However, the amount of frost formed on the evaporator of a refrigerator, etc. is greatly affected by the outside temperature and humidity of the refrigerator, the frequency of opening and closing the refrigerator door, and the contents stored in the refrigerator. There were disadvantages such as defrosting cannot be carried out when necessary, and defrosting cannot be carried out properly even though a large amount of frost forms on the evaporator, reducing the refrigerating capacity.

Therefore, in order to overcome these drawbacks, it has been considered to install an optical detector between the fins as a means of directly detecting frost formation, but since the fin spacing is extremely narrow, the detector must be very small. had to be formed.

The present invention aims to eliminate such drawbacks, and one embodiment thereof will be described below with reference to the accompanying drawings. In Figure 1, 1 is an evaporator of a refrigerator or other freezer, 2 is a pipe through which refrigerant passes, and 3
is a fin plate disposed perpendicular to the pipe; 4 is a frost detection hole provided in the fin plate; and 5 is a fin plate provided parallel to each other facing each other through the frost detection hole 4 for transmitting and receiving light. This is a frost detector having an optical transmission body, which detects a change in the amount of light passing through the frost detection hole 4 due to the progress of frost formation, and issues a defrosting command.

That is, the frost detector 5 will be explained in further detail in FIGS. 2 and 3. The frost detector 5 includes an optical transmitter/receiver 6 that transmits and receives light, and an optical transmitter 7 that transmits light from the optical transmitter/receiver. The light transmitting/receiving section 6 is provided with a light source 8 such as a lamp on the light emitting side and a light receiving element 9 such as a cadmium sulfide photovoltaic cell on the light receiving side. Alternatively, there is a method of using a semiconductor element such as a light emitting diode or a phototransistor for emitting and receiving light. The light transmitting section 7 is made of transparent resin, and the light transmitting body 10 on the light emitting side and the light transmitting body 11 on the light receiving side are arranged in parallel. By cutting both ends of the optical transmission section 7 at 45 degrees as shown in the figure, the optical transmission section 7
The light 12 that travels through the transmission section is directed against the cutting surface 13
Since the light is incident at 45 degrees and reflected at 45 degrees, in the light emitting section 14 of the light transmitting body 10 on the light emitting side, the light is transmitted to the outside of the light transmitting section orthogonally to the light transmitting section 7, so that the light on the receiving side In the light receiving section 15 of the transmitting body 11, light enters the optical transmitting section 7 at right angles, and the cut surface 1
After being reflected by the light beam 3, the light beam propagates through the light transmission section 7 and reaches the light receiving element 9.

In order to prevent the leakage of light from the light transmitting section 7 other than the light emitting section 14 and the light receiving section 15 and ensuring the reflection on the cutting surface 13, the light emitting section 14 and the light receiving section of the light transmitting section 7 and the light receiving section An effective method is to evaporate aluminum or the like over the entire optical transmission section, leaving only the portion 15.

By making the length of the light transmission section 7 sufficiently long, the light source 8 and the light receiving element 9 can be installed at any location apart from the evaporator 1, so problems such as cold resistance and thermal shock resistance are solved. Ru. Furthermore, since the optical transmitter 7 and the optical transmitter/receiver 6 can be sufficiently miniaturized, it is possible to operate in extremely narrow spaces such as between the fins of an evaporator. In addition, since the areas of the light emitting section 14 and the light receiving section 15, which transmit and receive light, are small, the optical axis can be narrowed down, and the scattering of light can also be minimized, so frost formation can be prevented consistently and very reliably. Can be detected.

As is clear from the above description, the frost detection device of the present invention has a frost detection hole provided in the fin plate of the evaporator, which is arranged opposite to the frost detection hole, and whose tip is opposite to the frost detection hole. It is composed of a pair of optical transmitters whose sides are cut at 45 degrees, and a light emitting source and a light receiving source respectively arranged at the rear end of the optical transmitter, so that the light from the light emitting sources is transmitted to other places than the optical transmitters. It reaches the end side, where it is transmitted from the 45 degree cut surface to the optical transmission body on the opposite side via the frost detection hole, and also transmitted from the 45 degree cut surface to the light receiving source. If it is attached, the amount of emitted light changes and the defrosting time can be detected, and since only two light transmitters are interposed between the fin plates, the size can be reduced.

[Brief explanation of drawings]

FIG. 1 is a plan view of a portion of a freezing chamber having a frost detection device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the device, and FIG. 3 is a plan view illustrating the operation of the device. 4...Frost detection hole, 10, 11...Light transmission body, 8
...Light-emitting source, 9... Light-receiving element (light-receiving source).

Claims (1)

[Claims] 1. A frost detection hole provided in the fin plate of the evaporator, a pair of optical transmission bodies arranged opposite to the frost detection hole, and having a tip cut at a 45 degree angle on the side opposite to the frost detection hole; A frost detection device consisting of a light emitting source and a light receiving source respectively placed at the rear end of an optical transmission body.