DE2413909A1 - TEMPERATURE SENSOR - Google Patents

Description

Dipl.-Ing.

Dipl.-Ing.

RolfCharrier

Patent attorneys

89QO Augsburg 31 · P.O. Box 242 '.

Rehlingenstrasse 8
Tel. 08 21/2 88 45

Postal checking account: Munich No. 1547 89-801

6654/39 / ÜO / Fr Augsburg, March 19, 1974

SMITHS INDUSTRIES LIMITED

CRICKLEWOOD WORKS

GB -LOND 0 N N.W.2

Temperature sensor

The invention relates in particular to a temperature sensor for use in gas turbine aircraft engines having a tubular at one end Sheath a temperature measuring device is arranged and a cable within the sheath along the sample runs, which forms an electrical connection to the temperature door measuring device.

Temperature sensors of this type sometimes have to work at temperatures of around 800 ^° C. with severe vibrations and withstand the thermal shock that comes with sudden changes in the temperature.

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Stand, for example, in the combustion chamber of the engine. It is a goal of the present Invention to provide a temperature sensor of the type specified, this requirement Fulfills.

According to the present invention, the object is achieved in that the cable along a helical Path runs on the inner surface of the shell and on the shell at least in certain Intervals along this path.

With this type of construction of a temperature sensor, the cable that makes the electrical connection to the electrical temperature measuring device, held in the sensor and can vibrate and withstand thermal stresses, including those found in gas turbine aircraft engines. Through the helical path of the cable on the inner surface the tubular sheath and the connection of the cable to it becomes a fixed connection achieved the changes in dimensions and other changes occurring in the antennae and in particular take place in the case in use, can easily be collected.

The temperature measuring device can be a thermocouple and the cable can be a metal-sheathed one Be cables with mineral insulation.

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The invention will now be explained in more detail with reference to an embodiment shown in the drawing; show it

1 shows a side section through one in the nozzle tube of a gas turbine engine mounted sensor;

Fig. 2 shows a section through the sensor according to line U-II of Fig. -1 in ver ■ -... ' larger scale.

The probe shown in Figs. 1 and 2 has an outer tubular sheath 1 and a Flange 2, with which it is screwed to the wall 3 of the motor nozzle tube. The shell 1 protrudes through the wall 3 and has a cavity at its end remote from the wall within the nozzle tube 4, which contains a thermocouple 5. The opening 4 takes through a Opening 6, which points upstream in the gas flow in the nozzle tube, hot combustion gases. That 'Thermocouple 5 is from a cup-shaped insert 7 carried in the sheath 1, which seals the cavity 4 from the rest of the interior of the sensor. on the downstream side of the casing 1 in the vicinity of the insert 7 is a small opening provided, which causes a gas flow through the cavity, so 'that between the hot gases and the Thermocouple 5 an effective heat transfer is possible.

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The thermocouple 5 is with a metal-encapsulated and welded connection 9 between the Wires 10 made of nickel-chromium and 11 made of nickel-aluminum alloy Mistake. The two wires 10 and 11 are the inner conductors of a 2-core cable 12 with mineral insulation, which is inside the Sheath 1 runs along the sample away from the insert 7 and the electrical connection to the connection point 9 forms. The cable 12 leaves the sheath 1 at the end near the wall outside the nozzle tube through a stopper seal 13. Between the stopper seal 13 and the insert 7, the Cable 12 in a helical path on the inner surface the shell 1. Its outer metal shell is essentially along its entire length brazed onto this surface. ;

As a result, the cable 12 is held firmly in the sensor and can withstand strong vibrations. aside from that The helical shape of the cable .12 captures easily variations of the sample and in particular of the sheath in the dimensions and other variations that are im

Operation occur on. In this way, the stresses and strains on the cable and its fastening in the sensor is reduced.

Thermal stresses between the cable 12 with mineral insulation and the sheath 1 can be controlled by suitable Choice of materials can be minimized. For this purpose, the sheath 1 and the sheath 14 of the cable 12 preferably the same or almost the same

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Expansion coefficient. In the exemplary embodiment, they are made of a nickel-chromium alloy or a Nickel-chromium-iron alloy. The inner conductors or wires 10 and 11 of the cable 12 are from each other and isolated from the envelope 14 by compacted magnesium oxide powder 15.

The casing 1 of the sensor is made of a tube 16, which is closed on the other side of the insert by a slotted cap 17, which forms a cavity 4. In the manufacture of the sensor, the cable 12, on one of which End the thermocouple 5 (formed by the encapsulated connection point 9) is formed on one Spindle with a helical groove shaped on its surface. It is then inserted into the tube 16 before the cap 17 attaches to the end remote from the wall will. The cable 12 is wound to a diameter that is a sliding fit in the tube 16 forms, and coated with a hard solder before insertion.

After the cable 12 has been inserted into the tube 16, the cup-shaped insert 7 is fitted into the far end of the tube 16 above the thermocouple 5; the plug seal 13 is inserted into the other end via the free end of the cable 12. Where a connection is required between these components, brazing is applied _J and then the whole is placed in a furnace and 'heated in vacuum to a temperature of 1075 ° C. Through this

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brazed connections are made between sleeve 1 and cable 12 causes. At the same time, the cap 17 is soldered in place.

The invention has heretofore been made with respect to a temperature sensor having a single warm connection point described. However, there can be two or more warm connection points in the temperature sensor be provided, whereby a multi-core cable with, for example, several pairs of conductors, corresponding to wires 10 and 11 is used. The two or more warm joints can alternatively also be provided with separate cables corresponding to cable 12 each of which is helically wound and connected to the shell of the probe. Also can the or each cable only one conductor for the or Own every thermocouple; in this case, for example, the electrical return path from a outer metal sheath of the cable or the sheath of the sensor.

The connection of the cable 12 to the sheath 1 was carried out in the embodiment described above Brazing causes. However, when the sample is used in other external conditions, for example when lower temperatures are involved or when the vibrational stresses on affect the sample, are not so serious, the connection can also be effected in other ways, for example by glue. Also can

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it turns out in practice that it is unnecessary to connect the cable 12 (not necessarily must be a cable with mineral insulation) along practically its entire length with the Sheath 1 to connect. It may be sufficient to only have such connections along at certain intervals its length to be provided.

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Claims (4)

6654/39 / UO / Fr - 8-19 March 1974 Expectations rl.JTemperature sensor, especially for use in gas turbine aircraft engines, in which an electrical temperature measuring device attached to one end of a tubular sheath and a cable along the sample inside the sheath runs, which provides an electrical connection to the temperature measuring device manufactures, characterized in that the cable (12) along a helical path on the inner surface of the shell (1) and with the shell (1) is connected at least at certain intervals along this path. 2. Sensor according to claim 1, characterized in that the cable (12) is a cable with mineral insulation is. 3. Sensor according to claim 1 and / or 2, characterized in that the temperature measuring Device is a thermocouple (5). - 9 409840/0829 6654/39 / UO / Fr - 9-19 March 1974 4. Sensor according to claim 3, characterized in that the thermocouple (5) is formed by the connection point · of two conductors (10, 11) which are insulated from one another Form wires of the cable (12). Sensor according to one or more of Claims 1 to 4, characterized in that that the cable (12) has an outer sheath (14) made of metal, that the sheath (1) made of metal and the cable sheath (14) is hard soldered to the sheath (1). 409840/0 8 29 Blank page