WO2016170267A1

WO2016170267A1 - High-temperature sensor with integrated connector

Info

Publication number: WO2016170267A1
Application number: PCT/FR2016/050919
Authority: WO
Inventors: Gabriel KOPP; Mahamoud SFAXI; Franck Menard
Original assignee: Sc2N
Priority date: 2015-04-20
Filing date: 2016-04-20
Publication date: 2016-10-27
Also published as: FR3035211B1; EP3286535A1; FR3035211A1

Abstract

The present invention concerns a temperature sensor (1) for a motor vehicle comprising: - a temperature-sensitive element (2), - a protective shell (3) comprising a closed end (4) in which the temperature-sensitive element (2) is housed, - an electrical connector (5) comprising two electrical connection elements (6), - two electric wires (7) connecting the temperature-sensitive element (2) to the two electrical connection elements (6) of the electrical connector (5), and - an insulating sheath (8) surrounding the two electric wires (7). According to the invention, the temperature sensor (1) comprises a junction element (11) attached to the insulating sheath (8) and to the electrical connector (5), said junction element (11) surrounding the two electrical connection elements (6) of the electrical connector (5).

Description

HIGH TEMPERATURE SENSOR WITH INTEGRATED CONNECTOR

The present invention relates to a temperature sensor, especially for measuring high temperatures, for example greater than 900 ° C, or even 1000 ° C.

The invention applies in particular to temperature sensors adapted to measure the temperature of gases, such as exhaust gases, motor vehicles, and for example automobiles or trucks. Such temperature sensors are particularly used in exhaust gas recirculation (EGR) systems ("Exhaust Gas Recirculation").

These sensors generally comprise a temperature sensitive element, such as a thermistor, connected to the outside to an electrical / electronic circuit for operating a measurement signal via electrical wires.

By way of example and as shown in FIG. 1, such a temperature sensor 1 of the prior art comprises at one end a thermistor housed in a protective envelope 3. Two first electrical wires in contact with this thermistor run along the protective envelope 3 to be accessible outside thereof and to provide electrical information representative of the resistance of the thermistor and therefore the measured temperature. For this purpose, the first electrical wires are connected, for example by means of an electrical connection piece in the form of a lug, for example, to second electrical wires used to provide the electrical connection with an electrical connector 5. - even connected to the electrical / electronic circuit. Generally the connection between the first and second electrical wires is made in an electrical insulating device, as shown in patent FR29881 72.

A mineral insulating sheath 8 surrounds the two electrical wires from the thermistor to the connection between the first and second electrical wires.

Such a sensor being used in particular in the exhaust line or in the exhaust manifold of the engine, it is exposed to a very hostile environment due to a corrosive environment due to the flue gases from the combustion chambers and strong thermal variations and mechanical. In order to ensure a good seal against the outside, in particular at the level of the second electrical wires, the temperature sensor comprises a seal in the zone of the sensor opposite to the temperature sensitive element.

The protective envelope 3 is crimped and welded to the mineral insulating sheath 8 to isolate the inside of the sensor from the outside environment.

At the outlet of the seal, the second electrical wires used to provide the electrical connection with the electrical / electronic circuit may be covered by a protective sheath, forming an electric harness 29, as illustrated in FIG. The protective sheath may be silicone and be reinforced with glass fibers, for example. It protects the electrical wires and provide them with good mechanical resistance. The protective sheath surrounds the electrical wires to the electrical connector 5. The electrical connector 5 being temperature sensitive, the harness 29 is lengthened to move it away from the hot zone. It has variable lengths depending on the vehicle models and can thus have a length of at least 10 cm, which can cause problems of size, grip and handling on the engine or vehicle assembly line, and problems cost of the temperature sensor. Indeed, when mounting the temperature sensor on the vehicle, the operator is often hampered by the length of the electrical harness 29. It is also necessary to provide a means for holding the electrical connector 5 in the vehicle.

A temperature sensor for measuring high temperatures in a hostile environment such as an exhaust line or the engine compartment of a vehicle therefore comprises a complex arrangement and is bulky.

The invention therefore aims to overcome these disadvantages of the prior art by providing a simpler and less cumbersome temperature sensor.

The invention relates to a temperature sensor for a motor vehicle comprising:

a temperature sensitive element,

a protective envelope having a closed end in which the temperature sensitive element is housed,

an electrical connector comprising two electrical connection elements,

two electrical wires connecting the temperature-sensitive element to the two electrical connection elements of the electrical connector, and

an insulating sheath surrounding the two electrical wires.

According to the invention, the temperature sensor comprises a connecting element fixed on the one hand to the insulating sheath and on the other hand to the electrical connector, said connecting element surrounding the two electrical connection elements of the electrical connector.

The temperature sensor may further comprise one or more of the following features, taken separately or in combination:

the insulating sheath is extended to the vicinity of the electrical connector;

the joining element is attached to an upper end portion of the insulating sheath;

- The joining element has a generally frustoconical general shape with a lower opening of diameter D1 and an upper opening of diameter D2 greater than the diameter D1;

the upper end portion of the insulating sheath is inserted into the lower opening of the connecting element, the joining element being welded or crimped on the outer surface of the insulating sheath;

the joining element has a thermal conductivity of less than 50 Wm ^-1 .K ^-1 (at 25 ° C) and preferably less than 15 Wm ^-1 .K ^-1 (at 25 ° C); the average thickness of the connecting element is less than 1.5 mm;

the joining element has a mass of less than 10 g, and preferably less than 5 g;

the electrical connector is inserted into the upper opening of the connecting element, the connecting element being crimped to the electrical connector;

the protective envelope covers the insulating sheath from a lower end of the insulating sheath located in the vicinity of the temperature-sensitive element to an upper part of the protective envelope, the insulating sheath extending longitudinally out of from the top of the protective envelope towards the electrical connector;

the temperature sensor comprises a fastening means intended to be fixed on a wall, said fastening means surrounding a portion of the protective envelope, the upper part of the protective envelope extending longitudinally out of the fastening means; in the direction of the electrical connector, when the temperature sensor is fixed on said wall;

the insulating sheath comprises an elbow;

the temperature sensor comprises a thermal insulator disposed between the insulating sheath and the connecting element;

The invention thus provides a temperature sensor for measuring temperatures above 900 ° C simpler because comprising fewer components compared to those of the prior art. In particular, this temperature sensor no longer includes a beam connecting the temperature sensor to the electrical connector. This bundle included lugs connected to the electrical connector, electrical conductors, mineral insulation, and a fiberglass-reinforced silicone sheath. Nor is it necessary to use a sealing element, an electrical insulator between the beam and the insulating sheath.

The electrical connector of the sensor is integrated in the front part of the sensor which is in contact with the hot zone. This temperature sensor is therefore shorter, more compact and less bulky than those of the prior art.

The electrical harness, the sealing element and the electrical insulator are replaced by a single connecting element making it possible both to protect the two electrical connection elements from external aggression, to connect the electrical connector to the rest of the temperature sensor. , and thermally protect the electrical connector.

The invention therefore provides a simpler temperature sensor and therefore less expensive.

The temperature sensor is rigid and can be self-supported. It is thus possible to remove the holding devices of the connector on the engine.

In addition, the proposed sensor facilitates its mounting on a motor assembly line and / or vehicle because the operator is not embarrassed by the harness. With the sensors of the prior art, it was necessary to provide sensors having different electrical beam lengths adapted to various vehicles. The proposed temperature sensor being compact, it is no longer necessary to provide several different sensors. A single model can be proposed as standard.

The removal of the electrical harness also simplifies the packaging of the sensor. It is no longer necessary to group bundles with a staple.

The features of the invention will be described in more detail with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a temperature sensor of the prior art;

Figure 2 is a longitudinal sectional view of a temperature sensor according to the invention;

FIG. 3 is a perspective view of this temperature sensor; Figure 4 is a longitudinal sectional view of this temperature sensor showing the detail of the connecting element;

Figure 5 is a perspective view of this temperature sensor mounted on a line of the exhaust line.

FIG. 2 represents a longitudinal sectional view of a temperature sensor 1 for a motor vehicle according to the invention.

This temperature sensor 1 comprises a temperature-sensitive element 2, a protective envelope 3 comprising a closed end 4 in which the temperature sensitive element 2 is housed, an electrical connector 5 comprising two electrical connection elements 6, two electrical wires 7 connecting the temperature-sensitive element 2 to the two electrical connection elements 6 of the electrical connector 5 and an insulating sheath 8 surrounding the two electrical wires 7.

According to the invention, the temperature sensor 1 comprises a junction element 1 1 fixed on the one hand to the insulating sheath 8 and on the other hand to the electrical connector 5. The junction element surrounds the two electrical connection elements 6 electrical connector 5.

The insulating sheath 8 is advantageously extended to the vicinity of the electrical connector 5, ensuring better mechanical strength.

FIG. 3 represents a perspective view of this temperature sensor 1.

The protective envelope 3 has a generally tubular shape extending longitudinally.

The protective envelope 3 is made of a metal material resistant to high temperatures, such as an alloy of chromium, nickel and iron of the Inconel® type (registered trademark) or refractory steel.

As illustrated in FIG. 2, the protective envelope 3 may comprise a closed end 4 having a diameter smaller than the rest of the envelope of 3. The temperature sensitive element 2 is disposed at this closed end 4.

The temperature sensitive element 2 is a thermocouple or thermistor, for example. The thermistor is a passive component in semiconductor material whose resistance varies as a function of temperature.

The thermistor can be of the CTN type, negative temperature coefficient (or NTC, Negative Temperature Coefficient in English) when the resistance decreases as a function of the temperature rise or type CTP, positive temperature coefficient (or PTC, Positive Temperature Coefficient in English) otherwise, such as a platinum thermistor.

The insulating sheath 8 surrounds the two electrical wires 7 from a lower end 9 located in the vicinity of the temperature sensitive element 2, to an upper end portion 1 0 located in the vicinity of the electrical connector 5.

The two electrical wires 7 are surrounded and held in the insulating sheath 8 which has two passage channels (not shown) associated with each of the electric wires 7 so that the two electric wires 7 are isolated from each other and held by the insulating sheath 8 .

The insulating sheath 8 is for example of generally elongate shape in a longitudinal direction corresponds to the longitudinal direction of the two electrical son 7. This insulating sheath 8 may have a generally cylindrical shape.

For example, the insulating sheath 8 has an electrically insulating and heat-resistant ceramic core 8a which is surrounded by an outer layer 8b of refractory steel. The outer layer 8b may be stainless steel, for example. The core 8a of the insulating sheath 8 may be in magnesia or alumina, for example.

Preferably, the protective envelope 3 surrounds the insulating sheath 8 partially, that is to say that it does not surround it over its entire length. The protective envelope 3 covers the insulating sheath 8 from a lower end 9 of the insulating sheath 8 located in the vicinity of the temperature-sensitive element 2 to an upper portion 16a of the protective envelope 3. The insulating sheath 8 extending longitudinally out of the upper part 1 6a of the sheath 3 towards the electrical connector 5.

In a variant (not shown), the protective envelope surrounds the insulating sheath over its entire length, as far as the joining element. The junction element is welded or crimped to the outer surface of the shroud.

Alternatively (not shown), the insulating sheath 8 is formed of several portions of insulating sheaths of different compositions.

As illustrated in FIG. 4, the electrical wires 7 comprise a portion of electrical wires 19 extending out of the upper end portion 1 0 of the insulating sheath 8. This portion of electrical wires 1 9 is not surrounded by the insulating sheath 8 and is connected to the two electrical connection elements 6 of the electrical connector 5. The joining element 1 1 of the invention makes it possible to overcome the use of an electrical sealing element at this portion of electrical son 1 9, since the electrical insulation is obtained by air.

The two electrical connection elements 6 may be lugs or folded connections as described in the application FR2983648 and in Figure 4, for example. This patent application describes a weld between the electrical son and pods said "wallet", allowing a compact assembly. The electrical wires 7 of the temperature-sensitive element 2 can be soldered directly to the electrical connection elements 6 of the electrical connector 5, making it possible to obtain a compact temperature sensor.

The connecting element 1 1 is fixed to the upper end portion 1 0 of the insulating sheath 8, situated in the vicinity of the electrical connector 5.

The joining element 1 1 has a generally frustoconical general shape.

The joining element 1 1 comprises a lower opening 1 2 of diameter D 1 and an upper opening 1 3 of diameter D 2 greater than the diameter D 1. The upper end portion 1 0 of the insulating sheath 8 is inserted into the lower opening 12 of the connecting element January 1. The lower openings 1 2 and upper 1 3 are circular.

For example, the diameter D1 may be about 4.8 mm. The diameter D2 may be about 14.7 mm. The length of the connecting element 11 may be about 20 mm.

The junction element January 1 is fixed on the outer surface 14 of the insulating sheath 8, at the upper end portion 1 0 of the insulating sheath 8. The junction element January 1 is fixed on the outer surface 14 of the insulating sheath 8 by means of a laser weld, for example. In a variant, the joining element 11 can be brazed on the outer surface 14 of the insulating sheath 8.

The electrical connector 5 is inserted into the upper opening 1 3 of the connecting element 1 January. The connecting element 1 1 is crimped to the electrical connector 5.

By way of example and as illustrated in FIG. 4, the joining element 1 1 comprises a frustoconical central portion 20a extended by an upper part 20b of circular section and a lower part 20b 'of circular section also. The upper part 20b is opposed to the lower part 20b 'and has a diameter greater than that of the lower part 20b'.

This upper portion 20b is surmounted by an annular portion 20c having a circular section and a diameter greater than the diameter of the upper portion 20b of the connecting element January 1. This annular portion 20c is intended to receive the electrical connector 5 which has a smaller diameter than the annular portion 20c. This ring-shaped annular portion 20c comprises a flange 27 surrounding the base of the electrical connector 5. The flange 27 is connected to the upper portion 20b by an intermediate ring-shaped portion 28, substantially perpendicular to the flange 27 and to the outer surface of the upper part 20b. The upper end of the flange 27 is bent inwards after crimping the joining element 1 1 to hold the electrical connector 5.

More precisely, it is the lower part 20b 'of the joining element 11 which is fixed to the insulating sheath 8.

A tight O-ring 18 may be provided between the electrical connector 5 and the annular portion 20c of the connecting element 11.

The joining element 11 has a mass of less than 10 g and preferably less than 5 g. Its mass is advantageously 5g in order to limit an excessive weight at the end of the temperature sensor which already comprises an electrical connector 5 and the electrical harness extending after (not shown). This low weight makes it possible to avoid damage to the insulating sheath 8 by limiting the mechanical stresses associated with the vibrations of the motor and the chassis.

The joining element January 1 may be stainless steel (304L for example) or multilayer steel, so as to have a low thermal conductivity. The thermal conduction of the joining element 11 is less than 50 Wm ^-1 .K ^-1 (at 25 ° C.) and advantageously less than 15 Wm ^-1 .K ^-1 (at 25 ° C.).

Alternatively, the connecting element 1 1 may be plastic or ceramic. The advantage of the ceramic is that the connecting element 1 1 and the core 8a of the insulating sheath 8 can be formed of a single piece and the same material during a same manufacturing step.

The average thickness of the connecting element 1 1 is advantageously less than 1.5 mm and is preferably about 1 mm, which makes it possible to limit the thermal conduction.

The connecting element 1 1 is preferably rigid to provide mechanical rigidity to the entire temperature sensor 1. The joining element 1 1 is obtained by machining (machining), for example.

Alternatively, the joining element 11 may be semi-rigid. It can be obtained by stamping and stamping a metal sheet. The advantage is to reduce the weight of the connecting element 1 1.

As illustrated in Figures 2 to 5, the electrical connector 5 of the temperature sensor 1 is intended to receive a connector of a vehicle 21 which is connected to an electronic control device (not shown).

The temperature sensor 1 comprises a fixing means 1 5 intended to be fixed on a wall 22, as shown in FIG. 5. This wall 22 defines a medium whose temperature is to be known. The wall 22 may be a wall of a combustion gas exhaust system, for example.

The fastening means 15 surrounds a portion of the protective envelope 3. The fastening means 15 comprises a central channel 23 through which the protective envelope 3 passes. The protective envelope 3 has an upper portion 16a. extending longitudinally out of the fastening means 1 5 in the direction of the electrical connector 5, when the temperature sensor 1 is fixed on the wall 22, as shown in Figure 5. The upper portion 1 6a of the protective envelope 3 may protrude from the fixing means 15 when it is fixed on the wall 22. This excess can be 0.5 cm to 2 cm for example. As a variant, the protective envelope 3 may even extend as far as the joining element 11. This makes it possible to increase the mechanical strength at the level of the insulating sheath 8.

The fastening means 15 may comprise a stop 24 at its lower part which is fixed to the protective casing 3 and a clamping means such as a screw 25 for tightening the abutment 24 against a bearing surface of the wall 22. delimiting the medium to be measured, as illustrated in Figure 5. The screw 25 is above the stop 24 and is free to rotate and translate around the protective envelope 3.

Alternatively, the screw 25 can be fixed to the stop 24.

The abutment 24 may be spaced from the joining element 11 by a distance of between approximately 3 and 4 cm, without being limiting. This proximity is possible due to the thermal efficiency of the connecting element 1 1 which protects the electrical connector 5 of the hot zone. This small distance makes it possible to obtain a compact temperature sensor 1.

The protective casing 3 also has a lower portion 16b extending longitudinally out of the fixing means 15 in the direction of the temperature sensitive element 2.

According to a particular embodiment (not shown), the insulating sheath 8 comprises a bend in order to facilitate the integration of the sensor in its environment. In other words, the insulating sheath 8 is not rectilinear. This elbow may have an angle of 90 ° C, for example.

According to another particular embodiment (not shown), the temperature sensor 1 comprises a thermal insulator disposed between the insulating sheath 8 and the connecting element 11. This reduces the temperature of the electrical connector 5 from 20 ° C to 30 ° C.

Thus, the invention makes it possible to obtain a temperature sensor 1 for a motor vehicle that is more compact than those of the prior art and has fewer components. The invention is particularly intended to measure high temperatures, for example higher than 900 ° C, or even 1000 ° C, but it can also be applied to lower temperatures, from 450 ° C.

Claims

1. Temperature sensor (1) for a motor vehicle comprising

a temperature sensitive element (2),

a protective envelope (3) comprising a closed end (4) in which the temperature-sensitive element (2) is housed,

an electrical connector (5) comprising two electrical connection elements (6),

two electric wires (7) connecting the temperature-sensitive element (2) to the two electrical connection elements (6) of the electrical connector (5), and

an insulating sheath (8) surrounding the two electrical wires (7), characterized in that it comprises: a connecting element (1 1) fixed on the one hand to the insulating sheath (8) and on the other hand to the electrical connector (5), said connecting element (1 1) surrounding the two electrical connection elements (6) of the electrical connector (5).

2. Temperature sensor (1) according to claim 1, characterized in that the insulating sheath (8) is extended to the vicinity of the electrical connector (5).

3. Temperature sensor (1) according to claim 1, characterized in that the connecting element (1 1) is fixed to an upper end portion (10) of the insulating sheath (8). ).

4. Temperature sensor (1) according to any one of claims 1 to 3, characterized in that the connecting element (1 1) has a generally frustoconical general shape with a lower opening (12) of diameter D1 and a upper opening (13) of diameter D2 greater than the diameter D1.

Temperature sensor (1) according to claim 4, characterized in that the upper end portion (10) of the insulating sheath (8) is inserted into the lower opening (12) of the connecting element ( 1 1), the joining element (1 1) being welded or brazed or crimped on the outer surface (14) of the insulating sheath (8).

6. Temperature sensor (1) according to any one of claims 1 to 5, characterized in that the connecting element (1 1) has a thermal conductivity less than 50 Wm ^-1 .K ^-1 (at 25 ° C) and preferably less than 15 Wm ^-1 .K ^-1 (at 25 ° C).

7. Temperature sensor (1) according to any one of claims 1 to 6, characterized in that the average thickness of the connecting element (1 1) is less than 1, 5 mm.

8. Temperature sensor (1) according to any one of claims 1 to 7, characterized in that the connecting element (1 1) has a mass less than 10 g, and preferably less than 5 g.

9. Temperature sensor (1) according to any one of claims 4 to 8, characterized in that the electrical connector (5) is inserted into the upper opening (13) of the connecting element (1 1), the joining element (1 1) being crimped to the electrical connector (5).

10. Temperature sensor (1) according to any one of claims 1 to 9, characterized in that the protective envelope (3) covers the insulating sheath (8) from a lower end (9) of the insulating sheath ( 8) located in the vicinity of the temperature-sensitive element (2) to an upper portion (16a) of the protective casing (3), the insulating sheath (8) extending longitudinally out of the upper part (16a) of the protective envelope (3) towards the electrical connector (5).

1 1. Temperature sensor (1) according to any one of claims 1 to 10, characterized in that it comprises a fixing means (15) intended to be fixed on a wall (22), said fixing means (15) surrounding a portion of the shroud (3), the upper portion (16a) of the shroud (3) extending longitudinally out of the fastening means (15) in the direction of the electrical connector (5), when the temperature sensor (1) is fixed on said wall (22).

12. Temperature sensor (1) according to any one of claims 1 to 1 1, characterized in that the insulating sheath (8) comprises a bend.

13. Temperature sensor (1) according to any one of claims 1 to 12, characterized in that it comprises a thermal insulator disposed between the insulating sheath (8) and the connecting element (1 1).

14. Use of the sensor according to one of claims 1 to 13 in a motor vehicle.