DE10358778B4 - Arrangement for temperature measurement and temperature sensor - Google Patents

Abstract

Arrangement for measuring temperature at a measuring point (4) with a temperature-sensitive measuring element (5), wherein the temperature-sensitive measuring element (5) is coated with a thermally conductive mass (6), wherein the envelope (6) is geometrically designed so that a planar contact to the measuring point (4) is present, characterized in that the temperature-sensitive measuring element (5) is an NTC element, which is glued to the thermally conductive compound (6) and a sleeve (11), wherein the measuring element in a sensor housing (12) is received, which is designed as a folding housing and the element which has the measuring point (4) encloses.

Description

The invention relates to an arrangement for temperature measurement according to the preamble of claim 1.

To control or regulate in the vehicle area, the detection of the temperature of refrigerants, coolants or other media is required. Frequently, temperature sensors for insertion or screwing into a pipeline or other components are used for this purpose. Due to the required for the introduction of the temperature sensors openings in the media tube a potential leak is created. Especially at high pressures and high operating temperature ranges, the seal is problematic in the use of such temperature sensors, if there is a demand not to allow leakage of the medium.

As a remedy, temperature sensors can be used to attach or apply to a pipeline or other components. In the use of such temperature sensors, the good thermal coupling to a measuring point is a major problem. A poor thermal coupling leads to a slow reaction of the temperature sensor with a change in the temperature of the medium. Thus, the long response time of the temperature sensor is a significant disadvantage of such overlay sensors. Furthermore, poor thermal coupling causes a difference between the measured temperature and the true media temperature, causing a mis-measurement of the media temperature.

The publication DE 202 08 698 U1 discloses a temperature application sensor for the electrical measurement of surface temperatures, wherein at least one thermoelectric conversion element is embedded in a molded, more elastic silicone rubber block, wherein the silicone rubber block simultaneously forms the thermally conductive contact surface of the thermoelectric conversion element.

Furthermore, the document discloses CH 678891 A5 a method for improving the heat transfer for temperature sensors on pipelines and an apparatus for carrying out the method. An embossing stamp is used to produce a dent on a thermally conductive and plastically deformable tubular piece which corresponds to the counter-shape of a part of the heat transfer surface of the temperature sensor. Tuned to the deformation properties of the pipe section and the shape to be generated support surfaces and hold-down surfaces and in special cases a matrizenähnlicher support core are effective in the deformation.

The publication DE 92 92 705 U1 discloses a temperature sensor for hot water with a metallic tubular sensor housing and a passive temperature sensor with a thin layer technically produced on a ceramic substrate electrically conductive layer in meandering, the two end points are provided with flexible leads and connectable to a Meßwerkschaltung.

The invention is based on the object, an arrangement for measuring temperature with improved thermal coupling, and to provide a temperature sensor for use in vehicles, this object is achieved by an arrangement with the features of claim 1.

The dependent claims relate to advantageous embodiments and further developments of the invention.

A main idea of the invention is to improve the thermal contact between a temperature-dependent measuring element, for example an NTC element and a measuring point, for example a pipe through which flows the medium whose temperature is to be determined by a highly thermally conductive mass, but the Keep thermal mass of the measuring element low. For this purpose, the temperature-dependent element is coated with the highly thermally conductive mass, such as a thermal adhesive. This enclosure is advantageously geometrically designed so that a good thermal contact with the measuring point is achieved. The enclosure can be made so that the measuring element is placed in a suitable mold and then this is poured with the thermal adhesive. After curing of the thermal adhesive, the mold can be removed again. As a result, the thermal mass of the coated measuring element can be reduced and the time behavior positively influenced.

In a further development of the invention, the mold remains after curing of the highly thermally conductive mass on the temperature-sensitive measuring element, wherein the mold is preferably designed as a specially designed highly thermally conductive sleeve, for example as a metal sleeve.

In a particularly advantageous embodiment of the invention, the geometry of the envelope over the mold or the sleeve remaining on the measuring element is adapted to the geometry of the measuring point or the geometry of the measuring point is adapted to the geometry of the envelope or the sleeve, for example by a special processing of the measuring point For example, by flattening the tube. By the measures mentioned becomes, a achieved as flush and large-scale edition of the temperature-dependent element on the measuring point. The invention also encompasses the type of embodiment that the NTC element with its original envelope has a specially adapted to the measuring point geometry to improve the heat transfer.

The thermally conductive sheath can also be realized by a plastic extrusion of the measuring element, which also serves as a mechanical support of the measuring element. The adaptation of the envelope to the geometry of the measuring point is achieved via the appropriate choice of the injection mold.

In a further advantageous embodiment, the measuring element with casing is thermally insulated from the sensor housing. This can be realized, for example, by a sufficiently large air space between the measuring element with casing and the sensor housing and / or by introducing a thermally insulating material between measuring element with casing and sensor housing. Due to this configuration of the sensor housing, the disadvantageous influence of the ambient temperature on the measuring element, in particular in the case of large temperature differences between the medium in the pipe and the bypass, can be significantly reduced, since the thermal coupling of the measuring element to the media pipe is significantly better than for the sensor housing or housing . is to bypass the sensor housing.

A further development is to improve the thermal contact between the temperature-sensitive element and the Maßstelle by a resilient attachment of the temperature-dependent element, wherein the element can be stored on one side or multi-sided resilient. This ensures that the temperature-sensitive element is pressed against the measuring point. In addition, a secure concern of the temperature-sensitive element at the measuring point is guaranteed even with different manufacturing and assembly tolerances.

In a particularly advantageous embodiment, both the envelope and the resilient mounting is used in a temperature sensor.

Due to the improved thermal coupling of the temperature-sensitive element to the measuring point, ie to the medium pipe or a component through which the medium flows, the temperature-sensitive element reacts faster to changes in the temperature of the medium and also allows a more accurate measurement of the temperature of the medium.

The use of humidity-sensitive temperature-sensitive elements ensures that the temperature sensor remains fully functional even when moisture penetrates into the mounting base.

The described arrangement for temperature measurement is in principle suitable for all applications in which a medium temperature is to be measured without introducing the temperature-sensitive element into the medium and the associated potential leaks (eg gas temperatures, refrigerant temperatures, coolant temperatures, etc.).

The advantages of the invention are in particular in the faster reaction time than in known Aufklemm- or support sensors, a lower measurement error of the temperature by better thermal coupling to the measuring point and thermal decoupling from the ambient conditions and in a safe and reproducible positioning over other support or Aufklemmfühlern.

Embodiments of the invention will be explained in more detail with reference to the drawing. Show it:

1a . 1b . 1c in each case a sectional view of a device for measuring temperature;

2a . 2 B . 2c in each case a schematic detail of a temperature-dependent element;

3a . 3b . 3c in each case a schematic representation of coupling possibilities to a measuring point;

4a . 4b in each case a schematic representation of a temperature sensor with resilient attachment of the measuring element.

5 a sectional view of the arrangements for temperature measurement 1c along the section line AA;

Corresponding parts or parameters are provided in all figures with the same reference numerals.

How out 1a can be seen, the arrangement for measuring a temperature comprises a temperature sensor 1 , a sensor recording 2 , a component 3 in the illustrated embodiment, a tube through which a medium to be measured (not shown) flows and a measuring point 4 at which the temperature of the medium is determined. How out 1a is apparent, includes the temperature sensor 1 a temperature-dependent element 5 , for example an NTC element, a cladding 6 made of thermally conductive material, in particular thermal adhesive, in which an adhesive base is either highly thermally conductive itself or this is mixed with highly thermally conductive material, such as metal chips, a plug connection 7 , a springy storage 8th for the NTC element 5 and a seal 9 , in particular an O-ring seal, for tightly connecting the plug connection 7 with the sensor holder 2 , By a suitable embodiment of the sensor holder 2 on the pipe 3 is to achieve that the thermal coupling of the measuring element 5 to the desired measuring point 4 stronger than the thermal coupling to the pipe 3 attached sensor holder 2 , This can be achieved by a sufficient distance between the measuring element 5 and the sensor holder 2 be achieved.

1b additionally shows a sensor guide 10 for guiding the NTC element 5 , The positioning of the measuring element 5 at the measuring point 4 can through additional guide elements 10 on the pipe 3 be improved. Through the guide element 10 can due to the increased contact surface to the NTC element 5 also strengthen the thermal coupling.

1c shows an embodiment in which the measuring element 5 with serving 6 in the longitudinal direction of the tube 3 is arranged. The resilient mounting of the measuring element 5 is by a spring tongue 8th realized. In 1c is the sensor recording 2 through a sensor housing 12 replaced, which is connected to the connector. The sensor housing 12 is designed as a folding housing, for example, that the tube 3 with encloses (see 5 ).

Alternatively, the sensor housing can be fastened to the pipe by means of a clamp or by a fastening tape. Through an airspace 13 between the measuring element 5 with serving 6 becomes the measuring element 5 from the sensor housing 12 thermally insulated. Additionally or alternatively, between the measuring element 5 with serving 6 and the sensor housing a thermally insulating material are introduced. In known Rohrauflagefühlern and systems for fixing of measuring elements on pipes, the measuring element is often replaced by metallic elements such. B. straps, clips o. Ä. Fastened to the pipe or is solidly poured into a plastic housing, which is then mounted on the pipe. These embodiments result in that the measuring element receives a good thermal coupling to the environment, which can lead to incorrect measurements of the medium temperature, especially at high temperature differences between the medium in the pipe and the environment. In addition, these systems by the connection of the fastener with the measuring element on a large thermal mass, causing these temperature sensors react inertly to temperature changes. By the described thermal insulation of the measuring element 5 with serving 6 from the sensor housing 12 the adverse influence of the ambient temperature on the measurement is significantly reduced and kept the thermal mass of the measuring element as low as possible.

In an alternative embodiment not shown, the sensor housing 12 at the bearing surface to the pipe 3 a sealing element on which the interior of the sensor, the actual measuring element 5 contains, protects against the ingress of liquids and particles.

2a shows the essential elements of the arrangement for temperature measurement for a good thermal connection at the measuring point 4 , How out 2a is apparent, is at the measuring point 4 the temperature-dependent element 5 about his serving 6 flat to the pipe 3 coupled. 2 B shows an additional sleeve 11 around the serving 5 is arranged. 2c shows an arrangement of the measuring element 5 with serving 6 in the longitudinal direction of the tube 3 ,

The 3a shows a measuring point 4 in which the geometry of the envelope for the flat edition 6 to the geometry of the pipe 3 was adjusted. The 3b shows a measuring point 4 , in the case of the surface edition the geometry of the tube 3 to the geometry of the envelope 6 was adjusted. The 3c shows a measuring point 4 in which the geometry of the envelope for the flat edition 6 to the geometry of the pipe 3 was adapted, wherein the measuring element 5 with serving 6 in the longitudinal direction of the tube 3 is arranged. Of course, it is also possible both the geometry of the envelope 6 as well as the geometry of the pipe 3 , or the component through which the measuring medium flows to change, for optimum thermal transfer at the measuring point 4 to obtain.

Furthermore, the optional use of a paste-like heat-conducting medium (eg thermal paste) causes between the measuring element 5 with serving 6 and bearing surface of the measuring point 4 a further improvement of the thermal coupling.

4a and 4b show the temperature sensor 1 with different springy bearings 6 the temperature-dependent element 5 , So shows 4a the temperature sensor 1 with a one-sided springy bearings 8th for the NTC element 5 and 4b shows a two-sided resilient mounting 8th for the NTC element 5 ,

Because the NTC element 5 can be exposed to a moisture load, are advantageously moisture-suitable special NTC elements 5 used so that there is no failure of the NTC element 5 comes through damp damage.

5 shows a sectional view of the arrangements for temperature measurement 1c along the section line AA. How out 5 is apparent, is the sensor housing 12 designed as a folding housing and encloses next to the measuring element 5 with serving 6 also the tube 3 ,

LIST OF REFERENCE NUMBERS

1

temperature sensor

2

sensor recording

3

Component, pipe

4

measuring point

5

temperature-dependent element, NTC element

6

Envelope, thermally conductive material

7

plug connection

8th

resilient storage

9

poetry

10

sensor guide

11

shell

12

sensor housing

13

thermal insulation of the measuring element (air space)

Claims (7)

Arrangement for temperature measurement at a measuring point ( 4 ) with a temperature-sensitive measuring element ( 5 ), wherein the temperature-sensitive measuring element ( 5 ) with a thermally conductive mass ( 6 ), wherein the envelope ( 6 ) is geometrically designed so that a flat contact with the measuring point ( 4 ), characterized in that the temperature-sensitive measuring element ( 5 ) is an NTC element, which with the thermally conductive mass ( 6 ) and a sleeve ( 11 ), wherein the measuring element in a sensor housing ( 12 ), which is designed as a folding housing and the element which the measuring point ( 4 ) encloses. Arrangement according to claim 1, characterized in that the overall arrangement of measuring element ( 5 ) and wrapping ( 6 ) is designed so that it has the lowest possible thermal mass. Arrangement according to one of claims 1 or 2, characterized in that the geometry of the envelope ( 6 ) or the sleeve ( 11 ) to the geometry of the measuring point ( 4 ) is adjusted. Arrangement according to one of claims 1 to 3, characterized in that the geometry of the measuring point ( 4 ) to the geometry of the envelope ( 6 ) or the sleeve ( 11 ) is adjusted. Arrangement according to one of claims 1 to 4, characterized in that the thermally conductive mass ( 6 ) is a thermal adhesive. Arrangement according to one of claims 1 to 5, characterized in that the measuring element ( 5 ) with wrapping ( 6 ) from the sensor housing ( 12 ) is thermally isolated. Arrangement according to claim 6, characterized in that the thermal insulation by an air space ( 13 ) between the measuring element ( 5 ) with wrapping ( 6 ) and the sensor housing ( 12 ) and / or by introducing a thermally insulating material between the measuring element ( 5 ) with wrapping ( 6 ) and sensor housing ( 12 ) is realized.

Images