EP0135958B1

EP0135958B1 - Optical ice-deposition sensor

Info

Publication number: EP0135958B1
Application number: EP84201212A
Authority: EP
Inventors: Gerrit R. Toes
Original assignee: Contronics Holland BV
Current assignee: Contronics Holland BV
Priority date: 1983-08-25
Filing date: 1984-08-23
Publication date: 1987-10-28
Also published as: EP0135958A2; DK404484D0; ATE30468T1; EP0135958A3; DK156095B; DK404484A; NL8302970A; DE3467032D1

Abstract

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 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-conducting material determining the ice-formation surface.

Description

The invention relates to an optical ice-deposition sensor adapted to be connected to 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 sight transmitting and receiving means, so that the optical path is interrupted when an ice layer formed on the ice-formation surface has reached a predetermined thickness, of which ice-deposition sensor at least that part comprising the connection to the cooling means is made from material having good heat conducting properties and comprises an ice-deposition means being made from material having good heat conducting properties and determining the ice-formation surface.
An optical ice-deposition sensor of the above nature is known from CA-A-1 089 949.
In the optical ice-deposition sensor known from the above publication the ice-formation surface is formed in the connection means for connecting the sensor to a cooling means. Therefore, in order to be able to choose a suitable or optimal ice-formation surface it is required to provide for a variety of connection means.
Further, the construction of the above known optical ice-deposition sensor is relatively complex and therefore difficult and costly to manufacture.
Once the known optical ice-deposition sensor is installed it is labour and time consuming to adjust the ice-formation surface or to enhance the ice-formation capabilities of the ice-formation surface.
Objects of the invention, inter alia, are to provide an optical ice-deposition sensor having a simple construction, and therefore being easy to manufacture and rather inexpensive, and to provide such a simple optical ice-deposition sensor having the features of an ice-deposition means being adjustable with respect to the optical path of the light transmitting and receiving means and possibly having an ice-deposition enhancing ice-formation surface.
To achieve the above and possible other objects the invention provides for a sensor of the nature described in the preamble being characterized in that the ice-deposition means is a screw means, of which an end face is or carries the ice-formation surface, and which is adjustable with respect to the optical path.
Advantageously the adjustable screw means is an adjustment screw made of material having good heat conducting properties, of which the end face is disposed parallel to the optical path between the light transmitting and receiving means. Therefore, in accordance with the invention the adjustment of the ice-formation surface can be simply, quickly and accurately carried out. During the manufacture the ice-thickness to be detected can be previously set.
In an embodiment of the invention the optical ice-deposition sensor is further characterized in that the end face of the screw means is provided with an extension comprising the ice-formation surface.
In the above embodiment other adjustable ranges of ice-thickness can be detected by choosing other shapes of the ice-formation surface, that is to say not only the shape of the extension, but also the shape of the end face of the screw means, for instance being flat, point-shaped, conical or spherical.
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 be fastened.
Fig. 2a is a perspective view of an end part of a set screw for use in the ice-deposition sensor in accordance 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 photo-diode or a photo-transistor.
At least that part of the housing or supporting structure 6 of the ice-deposition sensor embodying 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 heat-conducting 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, so that the ice-formation surface 9 will also cool, whereby a vapour being present at a given 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 receiving means will 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 of the extension 11 of Fig. 2b.
The lead wires of the opto-coupler are connected in the housing part 4 with 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. Moreover, the shape of the ice-formation surface is not limited to the embodiments 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.

Claims

1. An optical ice-deposition sensor adapted to be connected to 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, so that the optical path is interrupted when an ice layer formed on the ice-formation surface has reached a predetermined thickness, of which ice-deposition sensor at least that part comprising the connection to the cooling means is made from material having good heat conducting properties and comprises an ice-deposition means being made from material having good heat conducting properties and determining the ice-formation surface, characterized in that the ice-deposition means is a screw means, of which an end face is or carries the ice-formation surface, and which is adjustable with respect to the optical path.

2. An ice-deposition sensor as claimed in claim 1, characterized in that the end face of the screw means is provided with an extension comprising the ice-formation surface.