US1474903A - Pyrometer - Google Patents

Description

Nov. 20 1923. 1,474,903

R. HASE PYROMETER Filed July 26, 1922 Fig I Jnveni'orn Ruby In Patented Nov. 20, 1923.

UNITED STATES PATENT OFFICEI BUDOLF EASE, OF HANOVER, GERMANY.

PYROMETER.

' Application filed July as,

-H. 85936 IX/42i and H. 88511 VIII/21, b2,

filed the 21st June, 1921, and 24th January,

1922, respectively, and in France No. 156474,

filed the 8th March, 1922, of which the following is a specification.

ThlS invention relates to pyrometers of the type wherein a thermo element measures the radiation impinging upon it through a suitable optical system as of a telescope and supplies current to a galvanometer by which the measurement is indicated. The object of my invention is to provide a complete self-contained apparatus of this kind which shall be convenient in use and not liable to damage. A further and specific object of my invention is to avoid the use of external leads for makin the necessary electric connections. Such leads greatly interfere with the convenient handling of the apparatus, are readily damaged, and are a continual source of error.

My invention comprises in the first place a telescopic pyrometer wherein a thermo element is mounted within the casing of a telescopic optical system and is connected with a galvanometer contained within the same casing.

Yet a further object of my invention is to obviate errors and uncertainties by confinin the effect of the radiation so far as possib e to a single junction in the electrical circuit.

To this end my invention further includes an improved form of thermo element adapted to the situation in which it is mounted as above described. The thermo element is pref erably made of'well known metals or metal alloys which give a high thermo eleotromotive force, for example alloys of bismuth, antimony and so on. The one electrode is made in the form of a thin disc concentric with the optical axis of the instrument, and the other of a short rod secured in metallic 1922. Serial No. 577,749.

contact with the disc at its centre on the side remote from the source of radiation.

With this form of thermo element I prefer to combine a diaphragm by which radiation entering the optical system but not directed on to the disc will be cut off from the remainder of the electrical circuit.

This and other features of my invention will be found described in further detail with reference to the accompanying drawings which illustrate an example of construction of the new telescopic pyrometer and thermo element.

Figure 1 is a diagrammatic longitudinal section through the telescopic pyrometer.

Figure 2 is across section on the line 11-11 of Figure 1 seen from the left;

Figure 3 shows what is seen by an observer through the eye-piece of the telescope;

Figures 4 and 5 are front and side elevations of the thermo element on a larger scale.

The thermo element B, C mounted in an enlargement A of the telescope tube A receives radiation through the lens D while the eye-piece E is so adjusted that the observer can see through it both the body of which the temperature is to be measured and also the thermo element. Between the thermo element and the eye-piece there is placed a galvanometer so built that its permanent magnet F stands at right angles to and surrounds the optical axis of the instrument. The enlargement A of the telescope tube A may be so for-med as to constitute a shield for the observers eyes to protect them from the heat. The pointer F of the galvanometer moves over a scale E which is above the eye-piece, while the pointer itself-is not visible in the field of view since it is at less than focal distance from the eye-piece.

It is usual in such pyrometers to employ diaphragms in front of the thermo elements when the instrument is to be used for higher ranges of temperature; since the selectivity of other devices by which the radiation might be weakened is not sufliciently known. As a rule the galvanometer then needs to operate upon a different scale. By uniting one,

in one structure the device which receives the radiation and the current indicator it is easy to efiect the two adjustmentssimultaneousl for instance by causing insertion of a fres diaphragm to bring about simultaneously the shifting of the galvanometer on to a different scale. I I

Of the two electrodes B, C of the thermo element (Figures 4 and 5) on the point of contact of which the radiation is to strike, B, consists of a thin disc standing at right angles to the radiation and having the least possible heat capacity. It may consist for example of platinum of a thickness of 0.001 millimeter and a diameter of 3 to 5 millimeters. It is blackened upon the side turned towards the radiation (Figure 4 on the right) but is left polished on the other side to lessen radiation losses. The other electrode, C, consists of a metal alloy of high thermo-electromotlve force, and 15 made as a short rod secured to the disc B upon the side remote from the radiation. The length of the rod C may, for instance, be 1 to 3 millimeters and its diameter about 0.5 millimeter.

To the edge of the disc B there is soldered a lead G of hair-like fineness, the other end of which is soldered to a thicker wire H. To the free end of the rod C there is soldered a wire J which is thick throughout its length so that heat may readily be conducted away from the point of soldering. The wires J and G are held together by an insulating bridge K of glass or the like. They are cemented into-a socket L and make connection with contacts upon its under side. There is further cemented to the socket L a glass bulb N surrounding the parts of the.

thermo element and this bulb is exhausted as far as possible.

Between the thermo element B, C and the object glass D (Figure 1) there is placed a diaphragm O concentric with the cone of light. This'is in the form of a perforated disc made of material which is wholly or almost wholly opaque to heat rays but translucent, for instance smoked glass. This dia phragm further protects from the heat rays the point of junction at the free end of the rod C since it only permits the passage of so much of the cone of rays as will fall upon the disc B. Were it not for the presence of the diaphragm 0 heat rays would pass the edges of the disc B and might be reflected from behind it from the bulb N or the interior wall of the telescope tube upon the point where the wire J is soldered to the free end of the rod C.

If the. telescope is directed upon, for example, the inspection opening'of a furnace the observer sees through the eye-piece E what is shown in Figure 3. In the middle of the field is a dark circle corresponding with the disc B. Around that is a dark but not completel black rim 0 formed b such light as is able to penetrate the diap ragm 0. Between the circle B and the ring 0 there is a bright annulus P which is formed] by the light passing between the inner edge of thefldiaphragm and the outer edge of the disc B. When the telescope is properly adjusted upon the body to be observed all parts of the ring P must be equally bright. If they are not it is an indication that the telescope is not properly adjusted.

I claim- .1. A telescopic pyrometer comprising in combination an optical system, a casing enclosing and supporting said optical system, a thermo couple mounted within said casing in the axis of said system, a galvanometer also mounted within said casing and conductors connecting said thermo couple with said alvanometer.

2. n a pyrometer the combination of an optical system a casing surrounding and supporting said system, mounted within said casing in the axis of said system, and a galvanometer also ina thermo couple eluded within said casing, the magnet of said galvanometer surrounding the optical axis 0;? said system and the pointer of said galvanometer swinging in'a plane at right angles to said axis.

3. A telescopic pyrometer comprising in combination an optical system, including an eye-piece and ob ect-glass, a casing enclosing and supporting said optical system, a

thermo couple mounted within said casing in the axis of said system, a galvanometer also mounted within said casing and havin its pointer and scale in the field of view 0 said eye-piece,- and conductors connecting said thermo couple with said galvanometer.

4:. In a pyrometer the combination with an optical system of a thermo couple comprising a thin disc of metal standing at right angles to and concentric with the axis oi said system and a short rod of metal secured in metallic contact with said disc on the side thereof remote from the source of radiation.

5. In a pyrometer the combination of an optical system including an eye-piece an object-glass, a casing surroundingand supporting said system, a thermo couple supported in the axis of said system and including a thin metal disc at right angles to said axis and concentric therewith and a rod secured to said disc on the side remote coup and. adapted to intercept radiation that would not fall upon said disc.'

6. In a pyrometer the combination ofan optical system including eye-piece and heat rays mounted between said thermo couple and the object-glass of said system 10 and adapted to intercept radiation that would not fall upon said disc.

In testimony whereof I have signed my name to this specification.

RUDOLF HASE.

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