DE1253932B - Temperature sensor - Google Patents

Description

GERMAN WTVWi- PATENT OFFICE

EDITORIAL

German class: 42 i- 7/01

Number: 1 253 932

File number: K46417IXb / 42i

1253 932 Filing date: April 7, 1962

Opened on: November 9, 1967

The invention relates to a temperature sensor with a resistance wire wound as a disc coil as a measuring element which is attached to a component at a distance from it by means of a support block.

Such temperature sensors are used to measure the temperature of a medium, e.g. B. Air, which the component surrounds or is enclosed by the component to measure. There is often a problem with that the component has a temperature different from the medium to be measured, e.g. B. by that the heating elements in this component, for. B. a furnace wall, are arranged or that a reinforced Cooling takes place in the component.

A temperature sensor is known in which a meander-shaped sensor is used to measure the temperature of a gas flow wound coil of resistance wire in a cage-like gas-permeable housing sits, which protrudes into the gas flow and in a thermally insulated base in a Terminating sleeve is attached to the pipe. However, this known temperature sensor protrudes when he has a has the necessary length of the resistance wire for an accurate measurement, with a relative extensive body very far beyond the supporting component, namely the pipe. This does not generate only an increased flow resistance and an increased turbulence of the air, but hindered also mechanical processes or manipulations carried out in the vicinity of the temperature sensor Need to become.

In another known temperature sensor for sensing the temperature of heating plates Set up cooking appliances, such as pots, pans or the like, is the resistance wire to a disc coil wrapped and pressed between two discs, the discs on a thermally insulated The base is located telescopically in a tube located in a central opening of the heating plate or the like the force of a spring can be pushed in such that it is pushed by the spring against the bottom of the on the heating plate standing cooking device is pressed. In this known arrangement is primarily a The largest possible heat transfer surface can be created in the resistance wire, with the problem the heat transfer from the adjacent heating plate through a corresponding gap without Difficulties can be solved, in particular because the actual support device for the The measuring element is not in direct contact with the heating plate, so that through a heat transfer, d. H. Convection transmission, the measurement accuracy is not significantly affected.

Temperature sensor

Applicant:

King-Seeley Thermos Co.,
Ann Arbor, Mich. (V. St. A.)
Representative:

Dr.-Ing. H. Ruschke, patent attorney,
Munich 27, Pienzenauer Str. 2

Named as inventor:

Anthony Karl Otto, Ann Arbor, Mich. (V. St. A.)

Claimed priority:

V. St. v. America April 20, 1961 (104 449)

2

It is the object of the invention to provide such a sensor the greatest possible length of the resistance

a5 wire can be arranged so that the probe is relatively flat at a distance from the surface of the component, while on the other hand influencing the measurement result, ie a transfer of heat from the component, even via the base is prevented with certainty. It should be noted that even when using thermally insulating materials for the base with little movement of the medium to be measured, eg. B. the air, but considerable amounts of heat can be transferred by heat transfer from the component through the base into the coil.

According to the invention, this object is achieved in that the disc coil between two circular ring discs is inserted, which by means of one or more discs with low thermal conductivity are attached to the support block so that the inner turn of the disc coil is concentrically spaced around the support block. With this arrangement according to the invention, a disk coil is also provided relatively large diameter parallel to the surface at a short distance from this surface of the den Temperature sensor-bearing component held, but with a heat transfer through the support block in the resistance wire is prevented by the low conductivity of the support disks. Possibly heat that is still transferred to the supporting disks from the supporting block is reduced due to the large upper

709 687/176

area corresponding to the radial distance of the coil from the due to the diameter of the disks Support block in the surrounding atmosphere, so the medium to be measured, discharged, so that a temperature influence the circular ring disks accommodating the coil and thus an influence on the measurement result in the coil is avoided with certainty is.

The arrangement of resistance wire in the form of a disc coil, which is located at a radial distance from a support part, is known for producing a ballast resistor in arc lamps. The problem here, however, lies exclusively in the spatial accommodation of the largest possible wire length of the ballast resistor without hindering the construction of the lamp itself and not in preventing the heat transfer between the support part and the coil. Accordingly, the coil is directly with the wires receiving annular disks in this known arrangement, ie connected without extraordinary interposition of support disks, with the lamp itself.

In order to ensure safe storage of the measuring element in the support disks, a peripheral wall of these disks at a distance from the outer turn of the coil, the circular ring disks surrounding them associate. By this arrangement, the circular ring disks are set against each other and in addition, a displacement of the coil is prevented with certainty. Furthermore, this is a closure of the reached the resistance wire receiving gap between the circular ring disks on the outer circumference. This peripheral wall can consist of one piece with one of the support disks and for fixing z. B. be beaded with the free edge around the other of the support disks.

A further simplification of the structure is possible that one of the circular ring disks through a disk connecting the measuring element to the support block is formed so that the resistance wire is inserted between this support disc and the remaining circular ring disc. A Be arranged circumferential wall on the support disc, which z. B. is crimped around the circular ring disc and thereby closes the disc coil on the outer circumference.

In order to compensate for the stresses in to enable the arrangement and at the same time to create a stable, easy-to-manufacture construction, the disc lying on the underside of the measuring element can rest on the support block and the disc lying on the top of the measuring element arched inwards in the middle of the support block be attached. This creates the one consisting of a disk coil, circular ring disks and support disks The arrangement is elastically pressed against the surface of the support block in accordance with the bulge, whereby by the attachment only at one point, namely in the middle of the overhead Disc, a large degree of freedom of movement to compensate for thermal stresses is given.

The invention is explained in more detail below with reference to the drawings of exemplary embodiments. In the drawings, g, ->

F i g. 1 shows a section through a preferred embodiment of the measuring sensor, which is attached to a furnace wall is grown.

F i g. FIG. 2 is a bottom view of the FIG. 1 shown measuring device without furnace wall,

Fig. 3 is a section along the line 3-3 in Fig. 1,

F i g. 4 is a view of the in the sensor of FIG. 1 coil used,

Fig. 5 is a partial section through a compared to FIG. 1 modified embodiment of certain Parts,

F i g. 6 shows a partial section through a modification of the one shown in FIG. 1 shown device,

F i g. 7 shows a partial section through a modified heat sensor and

F i g. 8 is a partial section through a further modification of the heat meter.

The in F i g. 1 shown heat sensor is attached to the wall 10 of a furnace. A support bracket 12 has a cranked end portion 14, which in a slot 16 of the furnace wall 10 so up to the outer surface is inserted. The console 12 also has an elongated slot 18 which extends from one into the furnace wall 10 screwed retaining screw 20 is penetrated.

A round support block 22, for example made of ceramic material, is located in a cranked portion 24 of the Holding bracket 12 which penetrates an opening 26 in the furnace wall 10. The support block 22 is on in diameter opposite sides flats 28 and 30 (F i g. 1 and 2), which the side legs of the Record cranking 24 and in this way a relative rotation between the support block 22 and the Prevent retaining bracket 12.

The support block 22 also has an upper central surface 32 (FIGS. 1 and 3) and an outboard one upper ring surface 34. Both surfaces are separated from one another by an annular groove 36. the Flanges 38 of two clamps 40 and 46 are located on the bottom surface of the annular groove 36 via longitudinal bores 42 (FIGS. 2 and 3) in the support block 22. The shaft 44 of each clamp 40 penetrates one Slot in the support block 22 on the side of the retaining bracket 12. The shaft 44 can be close to the lower surface of the support block 22 shoulders that allow upward movement of the clamp 40 with respect to the support block 22, seen in Fig. 1, prevent. The flange 38 is bent into the position shown after the Terminal shaft 44 is pushed through the slot in block 22.

The support block 22 carries the heat sensor, which has an electrically insulated resistance wire 48 (Fig. 1) having.

The measuring wire 48 is wound into a single-layer disc coil containing several turns. The diameter of the inner winding 50 is larger (in a running device 60% larger) than that Outside diameter of the support block 22 and is several times as large (in an implemented device about ten times) as the distance between the inner turn 50 and the outer turn 52. The wire is in the embodiment shown wound in two coils, d. i.e. there are two parallel disks, e.g. B. 49 and 51st in the coil.

The coil consisting of the wire 48 is made of one material between two annular disks 54 and 56 good thermal conductivity, e.g. B. made of aluminum, pressed in. The disks 54 and 56 have offsets 58 and 60, which together form an inner wall against which the inner wall 50 of the coil rests. Each wall consists of an inwardly

Claims (2)

directed flange 62 and 64, which abut one another (FIG. 4). The flanges are fastened to the flange 62 by diametrically opposed tabs 66 and 68 or 70, 72, which bear against the lower surface of the flange and vice versa through slots. The ends of the wire 48 extend radially inward from the spool through slots 74 or 76, which protrude slightly outward in the two annular disks 54 and 56 beyond the cranked sections 58 and 60. The distance between the disks 54 and 56 is chosen so that the wire is clamped between these disks. However, the coil can also be secured between the disks 54 and 56 by means of an adhesive. To improve the heat transfer between the electrically insulated wire 48 and the disks 54 and 56, the assembly consisting of the wire and the disks is subjected to a pressing force which presses the disks 54 and 56 against one another. If soft aluminum is used for the disks 54 and 56 and a sufficiently large pressing force is applied, the turns of the electrically insulated wire are pressed into the surface of these disks, as shown in FIG. 6 shows, so that each cross section of the wire does not have a line contact but a surface contact with both disks. If a harder aluminum or a harder metal is used for the disks 54 and 56, then the insulated wire is not embedded in these plates, but is flattened, as is shown for the turn 78 in FIG. The assembly of washers 54 and 56 and wire 48 is then installed between a thin upper washer 80 and a thin lower washer 82. Since the support block 22 is at a different temperature than the air mass in the oven, the insulated wire 48 is thermally isolated from the support block 22 by designing and arranging the disks 80 and 82 to form a poor heat transfer path. The disks are therefore made of a metal which has a relatively poor thermal conductivity, for example thin stainless steel. The lower disk 82 is annular, and its inner circumferential section rests on the outer annular surface 34 of the support block 22. The outer diameter of the disk 82 is essentially the same as the diameters of the annular disks 54 and 56. The upper disk 80 rests on the central surface 32 of the support block 22. It is provided on its outer circumference with a downwardly directed flange 84 which serves as the peripheral wall of the assembly. An annular flange 86 is flanged under the peripheral edge of the lower disk 82 and clamps the entire assembly together. The upper surface of the upper disc 80 is curved inwardly when manufactured or assembled with the support block 82. The upper disk 80 has a central opening which is aligned with a central longitudinal bore 90 which extends through the support block 22. At this opening, the disk 80 forms a short rib 92 (FIG. 1) which engages in a transverse groove 94 (FIG. 3) in the central surface 32. A rivet 94 'penetrates the central opening of the washer 80 and the bore 90 as well as an enlarged bore 96 in the support bracket 12. An insulating washer 98, a flat washer 100 and a spring washer 102 are inserted between the rivet and the lower surface of the bracket 12, so that the rivet is isolated from the console 12. The clamping ends of the wire 48 are connected to the clamps 40 and 46, for example by welding, prior to the assembly of the washer 80 to the support block 22. The openings 42 in the support block (FIGS. 2 and 3) can serve to insert a counter-electrode onto the head section 38 of the clamp. In the case of the in FIG. In the embodiment shown in FIG. 5, the upper disk 80 & around and under the lower disk 82b is pulled down using a pressing device 104, the diameter of which is slightly smaller than the outer diameter of the disks 54b and 56 &. The pressing tool then forms the flange portions 84 b and 866 and bends the edge of the lower disk 826 upwards, so that the turns of the wire 48 b between the two disks 54 b and 566 are pressed. The in F i g. The modification shown in FIG. 7 differs from FIG. 1 in that the two annular disks 54c and 56c are made in one piece with one another and with the inner wall 106. The in F i g. The one-piece coil form shown in FIG. 7 can be made from a thin, tough metal, for example from aluminum sheet 0.3 mm thick. In the case of the in FIG. The modification shown in FIG. 8 is an annular disk through the upper support disk 108, while the lower support disk is omitted. The support surface 108 rests both on the central surface 1Sld and on the outer annular surface 34d of the support block 22d lying in the same plane. The peripheral edge of the upper disk 108 is bent over below the peripheral edge of a lower annular disk 110 which has an inner annular flange 112 which is attached to the disk 108 in any desired manner, for example by welding. The lower disk 110 is connected to the flange 112 via a crank 114, which serves as an inner wall for the installation of the inner turn of the resistance wire 48d, while the edge of the disk 108 forms the outer wall. The heat transfer between the coil of resistance wire 48 d and the support block 22 d is inhibited by the small cross section and by the radial length of the disk 108 between the wire 48 d and the block 22 d. Patent claims: 1. Temperature sensor with a resistance wire wound as a disc coil as a measuring element, which is fastened to a component at a distance therefrom by means of a support block, characterized in that the disc coil is inserted between two circular ring disks (54, 56), which by means of one or more Disks (108 or 80, 82) with low thermal conductivity attached to the support block (22) in this way are that the inner turn (59) of the disc coil concentrically spaced around the support block (22) lies. 2. Temperature sensor according to claim 1, characterized in that a peripheral wall (84) of the Disks (80, 82) at a distance from the outer turn (52) of the coil, the circular ring disks (54, 56) connects.