OPTICAL ICE-DEPOSITION SENSOR

Abstract: An optical ice-deposition sensor adapted to be connect­ ed with a cooling means and comprising light transmitting and receiving means for detecting ice-deposition on an ice-­ formation surface disposed in relationship to the optical path between the light transmitting and receiving means whereby at least that part of the ice-deposition sensor which comprises the connection with the cooling means is made from satisfactorily heat-conducting material and comprises an ice-deposition means made from satisfactorily heat-con­ ducting material determining the ice-formation surface.

Description: optical ice-deposition sensor. The invention relates to an optical ice-deposition sensor adapted to be connected with a cooling means and comprising light transmitting and receiving means for detecting ice-deposition on an ice-formation surface disposed in relationship to the optical path between the light transmitting and receiving means. A device of the kind set forth is known from German Patent Application 2,602,787. In this known device the ice-formation surface is formed by a part of a cooling means, whilst the connection of the device with the cooling means is possible but not necessary and the device, at least the housing thereof, consists of poorly heat-conductittt material. Since in this known device the ice-formation surface is determined hy a part. or a component of the cooling means to be monitored, there is no freedom of choice of a suitable or optimal ice-formation surface. A further disadvantage of the prescribed use of a part or a component of the cooling means as an ice-formation surface is that it may be subjected to deformation either due to the process of ice-deposition itself, for example, sagging resulting from increase in weight by the ice deposition or due to manupulation of the cooling means, for example, in cleaning. Due to said deformst,ion the illnlit.il of the detection is reduced. In order to mitigate to some extent this inherent inconvenience the known device could be disposed so that onlv a relatively thick layer of ice is detected, whilst after every manipulation of deformation of the cooling member the disposition has to be checked. Moreover, this positioning brings about contamination of the light transmitting and receiving means. The present invention has for its object to obviate one or more of the aforesaid or implied disadvantages and Drovides for this purpose a device of the kind set forth in the preamble, which is characterized in that at least that part of the ic-deposition sensor which comprises the connection with the cooling means is made from satisfactorily heat-conducting material and comprises the ice-deposition means made from satisfactorily hat-conducting material determining the ice-formation surface. The present invention is based on the recognition of the fact that ice-deposition occurs in the first place on rims of heat-conducting membPrs. The shape of the ie-foration surface is determinative of the rate of ice-deDosition. Owing to the thermal coupling of at least the housing or the supporting structure of the ice-depositioh sensor in accordance with the resent invention with a cooling means and externally providing the cooling means with an ice-dePosltion member of satisfactorily heat-conducting material thermally coupled with the housing of satisfactorily hent-conducting material, motHtlng on the cooling means does not affect the setting of the ice-depoUltion sensor. The ic-deposition means may be a set screw of satisfÅacitof heat-conducting material, the head face of which is disposed parallel to the optical path between the light transmitting and receiving means. The head face of the set screw may be given a suitable shape or b provided with a suitably shaped extension, which determines the desired ice-formation surface, whilst the adjustment can be simply quickly and accurately carried out. During the production the ice thickness to be detected can be previously set and by choosing other shapes of the ice-formation surface other adiustbe ranges of ice thickness can be detected. The invention will be described more fully with reference to embodiments shown in the drawing, in which Fig. 1 is a perspective view of an embodiment of the ice-deposition sensor in accordance with the invention and part of a cooling means to which the sensor has to he fastened. Fig. 2a is a perspective view of qn end part of a set screw for use in tho ic°-doposition sensor in accorda ce with the present invention, and Fig. 2b is an elevational view corresponding with Fig. 2a of a further embodiment of a set screw in accordance with the invention. Fig. 1 is a perspective view of the ice-deposition sensor embodying the invention and a part of a cooling means to which the ice-deposition sensor has to be fastened, in this case a cooling element having vanes 2. Reference numeral 1 denotes the possible connection between the cooling element and the ice-deposition sensor. In this embodiment the ice-deposition means has the shape of a set screw 7 with a retainer nut 10 and of an ice-formation surface 9, which is formed in this case, as is shown in Fig. 2a, by an extension 8 provided at the head face of the set screw 7, which has a point-shaped ice-formation surface. This point-shaped ice-formation surface furthers the ice deposition on the set screw. In other cases the flat head surface extending parallel to the light path between the light transmitting and receiving means may, of course, be used. Fig. 2b shows an extension 11 having a flat ice formation surface. The light transmitting and receiving means are accommodated in a housing of poorly heat-conducting material 3. In this case the housing 3 is the housing of a readily available opto-coupler comprising in co-operative relationship an infrared light emitting diode and a poto-diode or a photo-transistor. At least that part of the housing or supporting structure 6 of the ice-deposition sensor embo-lying the present invention which comprises the connection 1, as well as the set screw 7 is made from satisfactorily heat-conducting material, for example, aluminium. On the contrary the housing 3 is made from poorly heatconducting material. In operation owing to the effect of the cooling means via the housing or the supporting structure 6 of the ice-deposition sensor heat will be withdrawn from the set screw 7 and hence from the extension 8, 50 that the ice-for!nation surface 9 will also cool, whereby a vapour being present at a seven temperature in the surroundings of the ice-formation surface 9 will deposit in the form of ice. At a given thickness of the ice-deposition, which can be adjusted by turning the set screw 7, it will start interrupting the light ray or beam between the light transmitting and receiving means, whilst with further growth of the ice layer the light reveiving means wil: gradually receive less light Thus the output signal of the light receiving means is a measure for the thickness of the ice deposition on the ice-formation surface. Since the housing 3 accommodating the light transmitting and receiving means is made from poorly heat-conducting material, practically no heat is withdrawn therefrom. It will be obvious that ice deposition will take place more rapidly on the ice-formation surface of the extension 8 of Fig. 2a than on the ice-formation surface 6f the extension 11 of Fig. 2b. The lead wires of the opto-coupler are connected in the housing part 4 ith a cable 5, as the case may be, with the interposition of desired electronics, whilst the cable 5 is furthermore connected with the control-electronics for the device using the cooling means. It should finally be noted that the term "cooling means" should be interpreted in a broad sense and is not limited to the cooling element described above; it may also be an evaporator. The ice-deposition means is not limited to the set screw shown, it may be otherwise constructed and be otherwise adjustable. Moreover, the shape of the ice-formation surface is not limited to the em! > odiments shown; it may be advantageously conical or spherical. The invention is not limited to the use of extensions on the screw means, for example, a screw with a retainer nut or the ice-formation means. Although in the embodiments shown optical transmission is used, optical reflection may, as an alternative, be used again with visible or unvisible light. In principle other detectable forms of energy for example, radiation (X-ray, gamma rays) and sound (ultrasonic) may be used. The transmitting and receiving means are then designed accordingly. The figures used in the claims are only meant to explain more clearly the intention of the invention and are not supposed to be any restriction concerning the interpretation of the invention.

Claims: CLAIMS 1. An optical ice-deposition sensor adapted to be connected with a cooling means and comprising light transmitting and receiving means for detecting ice deposition on an ice-formation surface disposed in relationship to the optical path between the light transmitting and receiving means characterized in that at least that part of the ice-deposition sensor which comprises the connection with the cooling means is made from satisfactorily heat-conducting material and comprises an ice-deposition mess made from satisfactorilv heat-conducting material determining the ice-formation surface. 2. An ice-deposition sensor as claimed in Claim 1 characterized in that the ice-deposition means is adjustable with respect to the optical path between the light transmitting and receiving means. 3. An ice-deposition sensor as claimed in Claim 1 or 2 characterized in that the ice-deposition member has an ice-formation surface furthering ice-formation. LI. An ice-deposition sensor as claimed in anyone of the preceding Claims characterized in that the light transmitting and receiving means are accommodated in a housing of poorly heat-conducting material. 5. An ice-deposition sensor as claimed in anyone of the preceding Claims characterized in that the ice-deposition means is a screw means, a head face of which is or carries the ice-formation surface. 6. An iceepositionsensor as claimed in Claim 5 characterized in that the ice-deposition means or the head face of the screw means is provided with an extension comprising the ice-formation surface. 7. An ice-deposition sensor as claimed in anyone of the preceding Claims characterized in that the ice-formation surface is flat, point-shaped, conical or spherical. 8. A device using a cooling means characterized in that it comprises an ice-deposition sensor as claimed in anvone of the preceding Claims.

Inventors: TOES, GERRIT R.
Applicants: CONTRONICS HOLLAND B.V.
Application year: 1984
Main classification: F25D21
IPC codes: F25D21