EP2828630A1

EP2828630A1 - Temperature sensor

Info

Publication number: EP2828630A1
Application number: EP13715316.9A
Authority: EP
Inventors: Jean Sannier; Stéphane MASSIERA; Marc Seigneur
Original assignee: SC2N SAS
Current assignee: SC2N SAS
Priority date: 2012-03-19
Filing date: 2013-03-14
Publication date: 2015-01-28
Also published as: CN104204745A; US20150023391A1; KR20140136035A; US9816879B2; FR2988172A1; JP2015512513A; WO2013140066A1; CN104204745B; FR2988172B1

Abstract

The invention relates to a temperature sensor (1) for a motor vehicle comprising: -a housing (3) defining an internal volume comprising a temperature sensitive element (5), -electrical wires (9) linked electrically to said temperature sensitive element (5) and configured to transmit an item of temperature information from said sensitive element (5) to the exterior of the housing (3), -a seal (13) partially surrounding the said electrical wires (9) so as to isolate the sensitive element (5) with respect to the exterior of the housing (3), the seal (13) extending preferably in a direction, termed the longitudinal direction. According to the invention, said sensor (1) furthermore comprises a guidance means (15) integral with said seal (13) for the guiding of said electrical wires (9) out of said sensor, said guidance means (15) lying in the extension of said seal (13) according to the longitudinal direction of said seal (13) from a central zone of the seal (13) towards the exterior of said sensor housing (3), and the cross section of said guidance means (15) being of smaller dimension than that of the cross section of the seal (13), at least one portion of said guidance means (15) lying outside the housing. FIGURE:

Description

Temperature sensor

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 motor vehicle gases such as exhaust gases or gases in the engine compartment.

Such 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.

For example, such a sensor comprises at one end a thermistor housed in a protective housing. Two first electrical wires in contact with this thermistor run along the protective housing to be accessible outside thereof and to provide electrical information representative of the resistance of the thermistor and therefore the measured temperature. For this, the first electrical son are connected, for example via an electrical connection piece in the form of a lug, to second electrical son used to provide the electrical connection with the electrical / electronic circuit. Generally the connection between the first and second electric son is performed in an electrical insulating device.

Such a sensor being used in particular in the exhaust line or in the engine compartment, it is exposed to a very hostile environment due to a corrosive environment and projections of oil or water. It is therefore important to ensure a good seal vis-à-vis the outside, especially at the second electrical son.

According to a known solution, this seal is provided by a seal in the sensor zone opposite to the temperature-sensitive element and having two parallel passage channels for the second electrical son. The protective housing is crimped onto the seal to insulate the sensor interior from the outside environment.

Moreover, at the output of the sensor that is to say at the outlet of the seal, the second electrical son used to provide the electrical connection with the electrical circuit / Electronics, even covered by a sheath, may not be protected against a severe fold leading to locally severe deformations and thus to the degradation or rupture of the son.

According to a known solution, the sheath can be introduced into the sensor housing.

Although this solution makes it possible to limit the risk of creases and to ensure continuous coverage of the second wires, this solution has the disadvantage of lengthening the sensor housing.

Indeed, the introduction of the sheath in the sensor housing forced to have a double crimping, on the one hand the crimping of the housing on the seal, and on the other hand the crimping on the sheath for holding of the sheath. In this case, the length between the innermost face of the seal and the end of the housing can be doubled compared to a standard sensor.

At equal sensor length, this has the disadvantage of bringing the electrical insulator and the connections between the first and second electrical son of the hot zone of the sensor located around the sensitive element.

Since these components are sensitive to temperature, it is generally preferred to extend the back of the sensor so as not to increase the maximum temperature on these components. However, this rear extension of the sensor housing can cause problems of size and costs of the sensor.

The invention therefore aims to at least partially overcome these disadvantages of the prior art by providing a sensor for guiding and protecting the second son output of the sensor.

For this purpose, the subject of the invention is a temperature sensor for a motor vehicle comprising:

a housing defining an internal volume comprising a temperature-sensitive element,

electrical wires electrically connected to said temperature sensitive element and configured to transmit temperature information of said sensing element to the outside of the case,

a seal partially surrounding said electrical wires so as to isolate the sensing element from the outside of the housing,

characterized in that said sensor further comprises a guiding means integral with said seal for guiding said electrical wires at the output of said sensor.

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

said guide means is made in one piece with said seal;

said seal has a generally substantially cylindrical shape and said guide means is in the extension of said seal in the longitudinal direction of said seal towards the outside of said sensor housing;

said guide means has a substantially cylindrical general shape with a diameter smaller than the diameter of said seal;

said guide means extends out of the housing of said sensor;

said guide means extends at least partially inside the housing of said sensor;

said guide means is configured to be covered with an insulating sheath;

said guide means is a body comprising passage channels for the electric wires;

said passage channels are recesses in the body of the guide means for the passage of their respective electrical wire;

said guide means is made of elastomer;

said sensor housing is crimped onto said seal.

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

a housing defining an internal volume comprising a temperature sensitive element, electrical wires electrically connected to said temperature-sensitive element and configured to transmit temperature information of said sensitive element to the outside of the housing,

a seal partially surrounding said electrical wires so as to isolate the sensitive element with respect to the outside of the housing, the gasket preferably extending in a direction, referred to as the longitudinal direction, said sensor further comprising guide means secured to said seal for guiding said electrical wires at the output of said sensor, said guide means extending in the extension of said seal in the longitudinal direction of said seal from a central zone of said joined outwardly of said sensor housing, and the cross-section of said guide means being smaller in size than that of the cross-section of the seal, at least a portion of said guide means extending out of the housing .

This sensor may comprise one or more of the preceding characteristics, taken separately or in combination.

Other features and advantages of the invention will emerge from the following description given by way of example, without limitation, with reference to the accompanying drawings, in which:

FIG. 1 represents a view in longitudinal section of a sensor according to the invention,

FIG. 2 is a perspective view of a seal and its extension,

FIG. 3 is a perspective view of the seal and its extension partially surrounding electric wires at the output of the sensor.

In these figures the substantially identical elements bear the same reference numbers.

FIG. 1 shows a temperature sensor 1 comprising a protective casing 3 of generally tubular shape housing, from a closed end:

a temperature-sensitive element such as a thermocouple or a thermistor 5; first two electrical wires 7 connected to two second electric wires 9 serving to provide the electrical connection with, for example, an electric / electronic circuit of a processing unit, for conveying thereto the temperature signal supplied by the thermistor 5;

an electrical insulator 11 at the level of the electrical connection of the first 7 and second 9 electrical wires.

The protective housing 3 further comprises a seal 13 partially surrounding the two second electrical wires 9 at the opposite end of the sensor 1 with respect to the thermistor 5, and a means 15 for guiding the two second electrical wires 9 sensor output 1.

The protective housing 3 is for example crimped on the seal 13 defining an internal volume comprising the temperature-sensitive element, the first two electrical wires 7, the electrical insulation 11 and at least a portion of the gasket. sealing 13 and second electrical wires 9.

The protective housing 3 is made of a metal material resistant to high temperatures, such as an alloy of chromium, nickel and iron type Inconel ^® 601 (trademark) or refractory steel.

As can be seen in FIG. 1, the housing 3 may comprise a first portion 3a at the thermistor 5 and a second portion 3b with a larger diameter than the first portion 3a at the connection area of the first 7 and second 9 Electric wires.

This housing 3 may comprise a fastening system 17 on a wall (not shown) delimiting a medium whose temperature is to be known, such as the cylinder head of an engine. For this, the fastening system 17 may include an outer stop 19 and a clamping means such as a screw 21 for clamping the stop 19 against a bearing surface complementary to the wall defining the medium to be measured.

Thermistor 5 is a passive component of semiconductor material whose resistance varies as a function of temperature. The thermistor 5 may be of the CTN type, negative temperature coefficient (or NTC, Negative Temperature Coefficient) when the resistance decreases as a function of the rise in temperature or type CTP, positive temperature coefficient (or PTC, Positive Temperature Coefficient in English) in the opposite case, such as a platinum thermistor.

The first electrical wires 7 can be held in an insulating sheath 23 having an associated passage channel 25 for each first electric wire 7 so that they are insulated from each other and held by the insulating sheath 23.

The insulating sheath 23 is for example of generally elongate shape, the longitudinal direction of which corresponds to the longitudinal direction of the first electric wires 7.

This sheath 23 may comprise a casing of generally cylindrical shape, so as to be able to fit the tubular-shaped wall, for example of the first part 3a, of the protective casing 3 and be held by the latter.

For example, the sheath 23 is internally made of electrically insulating ceramic material and resistant to heat, and outside for example refractory steel.

The first electrical wires 7 each have one end connected to the thermistor 5 and an opposite end connected to a second electrical wire 9. The first electrical wires 7 can be connected to the second electrical wires 9 via an electrical connection piece 27, for example in the form of a pod.

The second son 9 may have a larger diameter and be made of less noble materials than the first son 7 to reduce costs. The second electrical wires 9 are for example intended to be connected to a conjugate connector (not shown) remote from the sensor 1.

The electrical insulator 11 also has a generally cylindrical shape so as to marry the tubular wall, for example the second portion 3b, the protective housing 3 and be held by it.

By way of example, the electrical insulator 11 is made of electrically insulating ceramic material and resistant to heat. For example, steatite is used. It is also possible to provide an electrical insulator 11 made of a plastic material resistant to high temperatures.

In the example illustrated in FIG. 1, the electrical insulator 11 comprises two housings 29 for receiving the connecting terminals 27 as well as firstly two first passage channels 31 for the first electrical wires 7 and secondly two second passageways 33 for the second electric wires 9.

According to the example illustrated in FIG. 1 with second wires 9 of larger diameter than the diameter of the first wires 7, in concordance, the second passage channels 33 for the second electric wires 9 have a greater diameter than the diameter of the wires. first passage channels 31 for the first films 7.

The electrical insulator 11 arranged at the level of the connection between the first 7 and the second 9 electrical wires makes it possible to electrically isolate the two connection terminals 27 with respect to one another and also with respect to the housing 3.

In addition, the insulator 11 limits the translational movement of the terminal lugs 27 in order to prevent traction on the second electrical wires 9 from causing ejection or deterioration of the internal components of the sensor 1.

Moreover, the electrical insulator 11 is placed in abutment against the seal 13.

The seal 13, for its part is for example made of elastomer. By way of example, silicone or fluorocarbon may be chosen as the material.

According to the embodiment illustrated in Figures 1 and 2, the seal 13 has a substantially cylindrical general shape so as to marry the tubular wall, for example the second portion 3b, the protective housing 3 and to be maintained by it. The cylindrical seal 13 thus has a sleeve shape.

As mentioned above, the seal 13 partially surrounds the second electrical wires 9, and to do this, the seal 13 may have two passage channels 35 of the second electrical wires 9.

In addition, the housing 3 of the sensor 1 is for example crimped on the seal 13 so as to isolate the sensitive element 5 relative to the outside of the housing 3.

Regarding the guide means 15, it is arranged at the end of the seal 13 opposite the end of the seal 13 in abutment against the electrical insulator 11. The guide means 15 is therefore arranged on the side of the sensor 1 opposite the side housing the sensitive element 5.

Similarly to the seal 13, the guide means 15 may have a generally cylindrical general shape with its longitudinal axis substantially parallel to the longitudinal axis of the sensor 1.

The guide means 15 is integral with the seal 13. Thus, the guide means 15 is integral with the housing 3 via the seal 13 without necessarily crimping the housing on the guide means 15.

The guiding means 15 guides the second electrical wires 9 at the output of the sensor 1. It is understood that such a guide means 15 arranged at the output of the sensor housing 3 ensures the maintenance of the second electrical wires 9 at the output of the sensor 1 and protects against severe bending radii likely to damage the second son 9 and accelerate their wear.

Preferably, the guide means 15 is made of a flexible material. Thus, the guiding means 15 improves the protection against severe radii of curvature by avoiding the presence of a folding point which would damage the electrical wires 9. Similar to the seal 13, the guiding means 15 can be made of elastomer.

More specifically, the guide means 15 is in the extension of the seal 13 in the longitudinal direction of the seal 13 and towards the outside of the sensor housing 3.

For this purpose, the guide means 15 is for example made in one piece with the seal 13 (see Figures 2-3), for example by molding.

The extension 15 could also be an additional piece fixed, for example by gluing, to the seal 13 to ensure the protective function of the second electrical son 9 at the exit of the seal 13. Of course, this additional piece could be in a material different from that of the seal 13.

In addition, the guide means 15 can be thinned with respect to the seal 13 and therefore have a diameter smaller than the diameter of the seal 13. Furthermore, the guide means 15 may have a length within a range length of the order of 10 to 25 mm. In order to guide the second electrical wires 9 at the output of the sensor 1, the guide means 15 at least partially surrounds the two second electrical wires 9 at the outlet of the seal 13.

For this purpose, the guide means 15 may comprise two passage means for the two second electrical wires 9. More particularly, the guide means 15 is a body having passage channels for the electrical wires 9. This guide means 15 thus makes it possible to separate the two second electric wires 9.

These passage means may for example be made in the form of closed passageways, similarly to the channels 35 formed in the seal 13.

Alternatively, the passage means can be opened. For example, the passage means are made by recess in the body of the guide means 15 as illustrated in Figures 2 and 3. More specifically, the body, for example cylindrical, of the guide means 15 has two recesses 37 of each side for the passage of the two second electric wires 9.

In addition, an insulating sheath (not shown) may be provided to cover the guiding means 15 and the second electrical wires 9. This insulating sheath may, for example, be of generally elongate shape, the longitudinal direction of which corresponds to the longitudinal direction of the second ones. electrical wires 9. The sheath improves the protection of the second electrical wires 9. The guide means 15 thus makes it possible to guide the second electrical wires 9 and this insulating sheath (not shown) at the output of the sensor 1. The guiding means 15 protects the 9 son and the sheath of severe radii of curvature.

Furthermore, according to a variant illustrated in FIG. 1, the guiding means 15 extends longitudinally out of the sensor housing 3. In other words, it is not necessary to lengthen the rear part of the sensor 1, it is that is, the portion of the sensor housing 3 opposite to the thermistor 5, to protect the second electrical wires 9. Indeed, the guide means 15 holds the second wires 9 and thus protects them against a fold which can lead to their degradation. or their break. For example, the guiding means 15 extends out of the internal volume defined by the crimping of the protective casing 3 on the seal 13. When the guide means 15 extends out of the sensor, the sensor housing 3 may be standard since it is not necessary to bring the connection lugs 27 and the insulator 1 1 of the thermistor 5 together or to lengthen the rear part of the sensor housing 3.

According to another variant, not shown, the guide means 15 can be received at least partially or completely inside the housing 3 of the sensor 1. By making the guide means 15 covered with the sheath penetrate into the housing 3, improves the protection of electrical wires against wrinkles. And more precisely according to this alternative, it is the guide means 15 with a diameter smaller than that of the seal 13 and covered with insulating sheath (not shown) which can be received at least partially in the housing 3 of the sensor 1 Finally, when the guide means 15 made by extending the seal 13 is covered with sheath and is received in the housing 3 of the sensor, it is not necessary to provide additional crimping since the housing 3 of the sensor 1 is already crimped on the seal 13.

Of course, the invention is not limited to the examples described. Thus, the sensor may not include first electric wires 7, the second wires 9 being then configured to be directly connected to the thermistor 5.

In the example of sensor 1 described in FIGS. 1 to 3, the seal 13 and the guide means 15 have a generally substantially cylindrical shape. However, the seal 13 and the guide means 15 may have other shapes. For example, they could be of substantially parallelepiped shape. In particular, the seal 13 preferably extends in a direction, called the longitudinal direction. This direction may correspond to a direction of insertion of the seal 13 in the sensor 1. The transverse dimension of the seal 13 is shaped to ensure a seal of the sensor 1 when the seal 13 is mounted in the housing 3.

The guide means 15 may then be in the extension of the seal 13 in the longitudinal direction of the seal. In particular, the guide means 15 is connected to the seal 13 at a central zone of the seal 13. Thus, the guide means 15 forms a core around which the son 9 come to bear to be guided at the output of the sensor 1 Preferably, the cross-section of the means of The guide 15 is smaller than the cross section of the seal 13. Thus, the guide means 15 can be hinged more easily than the seal 13, which reduces the pulling stresses of the son 9 This size differential protects the seal / guide assembly. Indeed, if the seal 13 and the guide means 15 had identical sections, this would cause higher stresses in the joint assembly / guide means during reciprocating electric wires 9 around their central position (movements of the same type). jumping rope). A radial tear may appear prematurely. Repetitive motion could also cause a cut caused by the end of the housing 3.

The guiding means 13 makes it possible to guide the wires 9 at the output of the sensor 1, that is to say outside the housing 3. For this purpose, the guiding means 3 may comprise at least one portion extending out of the housing 3 so as to improve the output guidance of the sensor.

In particular, the sensor 1 may comprise a means for holding the electrical wires 9 on the guiding means, such as glue, a collar or a sheath surrounding the electric wires 9.

In a variant, the passageways of the guide means are recesses 37 therein. Each recess 37 may form a channel whose wall matches at least a portion of the periphery of its respective wire 9 so as to contribute to the maintenance of the wire 9 therein.

Claims

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

a housing (3) defining an internal volume comprising a sensitive element (5) at the temperature,

- electrical wires (9) electrically connected to said sensing element (5) at the temperature and configured to transmit temperature information of said sensing element (5) to the outside of the housing (3),

a seal (13) partially surrounding said electrical wires (9) so as to isolate the sensitive element (5) with respect to the outside of the housing (3), the gasket 13 extending preferentially in a direction, called the longitudinal direction,

said sensor further comprising guiding means (15) integral with said seal (13) for guiding said electrical wires (9) at the output of said sensor, said guiding means (15) extending in the extension of said seal sealing means (13) in the longitudinal direction of said seal (13) from a central zone of the seal (13) towards the outside of said sensor housing (3), and the cross-section of said guide means ( 15) being smaller in size than the cross section of the seal (13), at least a portion of said guide means (15) extending out of the housing.

2. Sensor according to claim 1, characterized in that said guide means (15) is made in one piece with said seal (13).

3. Sensor according to claim 1 or 2, characterized in that said seal (13) and said guide means (15) each have a substantially cylindrical general shape.

4. Sensor according to any one of claims 1 to 3, characterized in that said guide means (15) extends out of the housing (3) of said sensor.

5. Sensor according to any one of claims 1 to 3, characterized in that said guide means (15) extends at least partially inside the housing (3) said sensor.

6. Sensor according to any one of the preceding claims, characterized in that said guide means (15) is configured to be covered with an insulating sheath.

7. Sensor according to any one of the preceding claims, characterized in that said guide means (15) is a body having passage channels for the electrical son (9).

8. Sensor according to claim 7, characterized in that said passage channels are recesses (37) in the body of the guide means (15) for the passage of their respective wire (9).

9. Sensor according to any one of the preceding claims, characterized in that said guide means (15) is made of elastomer.

10. Sensor according to any one of the preceding claims, characterized in that said sensor housing (3) is crimped on said seal (13).