DE202008016201U1 - High temperature thermocouple - Google Patents

Abstract

High temperature probes, in which a sensor element is arranged in a metal tube (2), characterized in that in the metal tube (2) thermoelectric lines (4) are arranged, at least in the measuring medium facing area of the metal tube (2) surrounded by a powder filling (5) are, which consists of a thermally highly conductive ceramic powder, wherein the thermal conductors (4) in a welded thermowire bead (3) and wherein the metal tube (2) in this area a multi-level Has constriction and at its end facing the medium to be measured is closed with a bottom part (1).

Description

The The invention relates to a high-temperature sensor in which a sensor element is arranged in a metal tube.

In Temperature measurement is known, temperature sensor to use with sheathed cables. In sheathed cables are inner conductors guided in a metal tube. The inner conductors can be surrounded by a powder filling. The through the inner pipes guided signals are by means of electrical connection cables led to an electronic evaluation.

such Temperature sensors are for use in exhaust pipes of internal combustion engines suitable, in particular when charging by means Turbocharger and compressors. In general, need turbocharger and compressors are protected against overheating. These are temperature sensors in the turbocharger or compressor housing arranged and interconnected with evaluation. For turbochargers In diesel operation, the protective devices are at temperatures between 600 ° C and 900 ° C set. When gasoline powered Engines with turbochargers and compressors increase the Protective temperature to about 1,100 ° C. The temperature in the turbocharger but not only as a shutdown value, but also as a controlled variable in connection with other sensors in the exhaust and intake manifold used to control the drive.

in the State of the art are diverse designs known for temperature probes used for intended for use at elevated temperatures.

In DE 40 21 997 C1 is described a high-temperature thermistor, which is arranged inside a heat-resistant metal tube and which consists of a predetermined mixture to form a ceramic, so that a certain degree of change of the resistance is within predetermined limits.

Further, in EP 0 783 096 B1 proposed a temperature device, wherein a metal tube and an insulator for maintaining the electrical insulation of the metal tube and the inner metal wires are provided. In this case, a metal lid is provided on one end of the metal tube for covering a temperature detecting element.

In DE 198 06 110 C2 An exhaust gas sensor including a thermosensitive element made of a ceramic substrate on which platinum resistance lead contact pads are formed is described. With the contact pads, the cable connection is directly connected.

Out DE 10 2006 034 248 B3 It is known to arrange an electrical measuring resistor in a filler and a protective tube so that the density of the filler along the protective tube has a gradient, wherein the density of the filler has a maximum at the point at which the protective tube has a bottleneck.

Furthermore, after DE 10 2004 007 906 A1 a ceramic insulated high-temperature sensor is known in which the lower end of a socket element immersed in the medium to be measured, wherein the socket element consists of a ceramic body, extending in the inner bore inner conductor, which connect a measuring element with an electrical connection.

The Above versions have a continuous use of 1,100 ° C too short life and too high Sensor drift on.

Of the Invention is based on the object, a temperature sensor of the type mentioned above, at temperatures up to operational at 1200 ° C, rapid temperature changes can capture and has a low failure rate.

According to the invention the task with a temperature sensor, which in Claim 1 features specified solved.

advantageous Embodiments are specified in the subclaims.

The In the metal pipe outgoing internal cables are at least in the measuring medium facing the end of the metal tube of a powder filling surrounded, which consists of a thermally highly conductive ceramic powder. The metal tube has a multi-stage constriction in this area on, with which the powder filling was compacted. At her the measuring medium end facing into the metal tube is a bottom part shrink wrapped. The sensor element consists of a thermowire bead, which is arranged at the messmedienseitigen end of the metal tube.

The Multistage constriction preferably contains one on the End of the metal tube, which faces the measuring medium arranged first conical area, following one after an adjustment cone prismatic or cylindrical area and an adjoining one second conical area.

Of the prismatic area becomes advantageous with a polygonal cross section executed, in particular with a six or octagonal cross-section.

The temperature sensor can, for example, in the turbocharger housing directly in front of the turbine paddle wheel can be used seated, can measure rapid temperature changes and can also be used as a control element. The sensor has a long service life and low sensor drift even at continuous use at temperatures around 1,100 ° C. It is also advantageous that the exhaust gas flow is disturbed only slightly. It has a low static-thermal installation error. It is characterized by a low failure rate. The temperature sensor is modular and can be manufactured inexpensively.

The Invention will be described below with reference to an embodiment explained in more detail. The embodiment describes the application in a turbocharger.

In the accompanying drawing shows:

1 a partial section of the temperature sensor and

2 the side view of the temperature.

At the in 1 shown high-temperature sensor is located inside the heat-resistant metal tube 2 on the measuring medium end facing a sensor element in the form of a thermowire bead 3 , Through the metal tube of the sheathed cable 2 the thermal cables run 4 , The thermoelectric cables 4 are at least in the measuring medium facing the end of the metal tube 2 from a powder filling 5 surrounded, which consists of thermally conductive ceramic powder. The metal pipe 2 has in this area a multi-stage constriction, with which the powder filling was compacted. The metal pipe 2 is at its projecting into the measuring medium end with a welded circular bottom part 1 locked. Due to the cone-shaped design of the bottom part 1 and the pipe end 2.1 the bottom part is additionally secured positively, whereby the assembly is facilitated.

In the illustrated embodiment, the multi-stage constriction includes an end of the metal tube facing the measuring medium 2 arranged first conical area 2.1 , one after an adjustment cone 2.4 following prismatic or cylindrical area 2.2 and a subsequent second conical region 2.3 , In the example shown, the prismatic area has a hexagonal cross-section. The cone of the first conical area 2.1 is shorter than the cone of the second conical section 2.3 ,

2 shows the side view of the end of a high-temperature probe, which dips into the medium to be measured. The pipe area 2.2 is here pressed to a hexagonal cross-section.

1

the bottom part

2

metal pipe

2.1

first conical area

2.2

prima genetic Area

2.3

second conical area

2.4

adjusting cone

3

Thermo wire bead

4

Extension cables

5

powder filling

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4021997 C1 [0005]
• EP 0783096 B1 [0006]
• - DE 19806110 C2 [0007]
• - DE 102006034248 B3 [0008]
• - DE 102004007906 A1 [0009]

Claims (6)

High-temperature sensor, in which a sensor element in a metal tube ( 2 ), characterized in that in the metal tube ( 2 ) Thermoelectric cables ( 4 ) are arranged, at least in the measuring medium facing the region of the metal tube ( 2 ) of a powder filling ( 5 ), which consists of a thermally highly conductive ceramic powder, wherein the thermal conductors ( 4 ) in a welded thermowire bead ( 3 ) and wherein the metal tube ( 2 ) has in this area a multi-stage constriction and at its end facing the medium to be measured with a bottom part ( 1 ) is closed. Temperature sensor according to claim 1, characterized in that the bottom part ( 1 ) with the end of the metal tube ( 2 ) is welded. Temperature sensor according to claim 2, characterized in that the bottom part ( 1 ) additionally by a cone form-fitting at the end of the metal tube ( 2 ) is secured. Temperature sensor according to one of the preceding claims, characterized in that the multi-stage constriction on the measuring medium facing the end of the metal tube ( 2 ) arranged first conical area ( 2.1 ), a subsequent prismatic or cylindrical region ( 2.2 ) and a subsequent second conical region ( 2.3 ) contains. Temperature sensor according to claim 4, characterized in that the prismatic area ( 2.2 ) has a polygonal cross-section. Temperature sensor according to one of the preceding claims, characterized in that the first conical region ( 2.1 ) has a greater inclination than the second conical region ( 2.3 ).