FR3105426A1 - Gas sensor - Google Patents

Abstract

Gas sensor Gas sensor (1), of the type capable of measuring a concentration of a component in a gas, comprising a measuring device (21- 23), a support (31-34) capable of enabling the device to be fixed measuring device (21-23) on a gas pipe (G) and a transport device (41-43) able to take gas from the gas pipe (G) and to transport the gas taken from the gas pipe ( G) to the measuring device (21-23) and return, further comprising at least one vibration damper (51-53, 55) arranged between the support (31-34) and the measuring device (21-23). Figure for abstract: Figure 1

Description

gas sensor

The invention relates to the field of gas sensors, such as motor vehicle exhaust gas, capable of measuring a concentration of a component in said gas.

In known manner, such a gas sensor is typically attached to a gas pipe carrying a gas to be analyzed. It is capable of taking a flow of gas from said pipe, in order to analyze it. Such a sensor comprises a measuring device, a support able to allow the fixing of the measuring device on a gas pipe, a transport device able to take gas from the gas pipe and to transport the gas taken from the gas pipe gas to the measuring device and back.

The problem that can be encountered is that the vibrations of the gas pipeline are transmitted, via the support, to the measuring device. These vibrations are detrimental in that they can distort the measurements and/or damage the measuring device.

In order to solve this problem, the invention proposes to insert, between the support and the measuring device, a vibration damper, in order to vibrationally isolate the measuring device by reducing or eliminating the vibrations transmitted to the sensor.

For this, the subject of the invention is a gas sensor, of the type capable of measuring a concentration of a component in a gas, comprising a measuring device, a support capable of allowing the fixing of the measuring device on a pipe of gas and a transport device capable of taking gas from the gas pipe and transporting the gas taken from the gas pipe to the measuring device and back, further comprising at least one vibration damper disposed between the support and the device of measurement.

Particular characteristics or embodiments, which can be used alone or in combination, are:

- said at least one vibration damper is made of silicone,

- said at least one vibration damper comprises a go channel capable of transporting the gas taken from the gas pipeline to the measuring device and a return channel capable of transporting the gas from the measuring device to the gas pipeline,

- the measuring device comprises a sensitive cell and a radiator integral with the sensitive cell,

- the sensitive cell is photo-acoustic,

- said at least one vibration damper comprises a continuous membrane extending between the sensitive cell and the support, in order to ensure a seal between the sensitive cell and the support, by letting the radiator out,

- the sensor also includes a stiffener fixed to the radiator, enclosing the vibration damper between the stiffener and the radiator,

- the vibration damper still includes at least one stud at the points of contact with the support,

- the vibration damper comprises a first part, substantially cylindrical, comprising the outward channel and the return channel, secured to the support by one of its ends and with the sensitive cell by its other end and a second part, substantially tubular, fixed to the support by a border secured to its generatrix, secured to the radiator in a sealed manner by a first end, containing the sensitive cell and surrounding at a second end the first part at the level of its generatrix, in a sealed manner.

In a second aspect of the invention, an exhaust line comprising such a sensor.

In a third aspect of the invention, a vehicle comprising such a line.

The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended figures in which:

shows, in side cutaway view, a gas sensor installed on a gas pipeline, according to one embodiment,

shows, in front sectional view, the embodiment of FIG. 1,

shows, in perspective view, the embodiment of FIG. 1,

shows, in exploded view, the embodiment of FIG. 1,

shows, in plan 3 views, 2 sections and 2 perspectives, the first part of the vibration damper,

shows, in plan 3 views, 2 sections and 2 perspectives, the second part of the vibration damper.

Referring to Figures 1-4, a gas sensor 1, of the type capable of measuring a concentration of a component in a gas, comprises a measuring device 21-23, a support 31-34 and a transport device 41- 44. The measuring device 21-23 is designed to carry out the measurement, i.e. the determination of the concentration of a given component in the gas. It comprises a sensitive cell 21 and means for assisting the operation of the sensitive cell 21: radiator 22 and stiffener 23. The support 31-34 secures the measuring device 21-23 to a gas pipe G of which it is desired to measure the gas and forms a protective casing around the measuring device 21-23. The transport device 41-44 is designed to take gas from the gas pipe G and transport this gas taken from the gas pipe G to the measuring device 21-23, for the outward journey, and from the measuring device 21-23 to gas line G for return trip.

The gas line G may be subject to a high level of vibration. Thus in the particular case of exhaust gas, a gas pipe G is subjected to a vibratory regime resulting from the operation of the heat engine to which the gas pipe G is connected. A transmission of vibration to the measuring device 21 can be detrimental in that it disturbs the measurement carried out and/or that it can lead to premature aging of the measuring device 21-23.

Also, in order to reduce the vibrations transmitted to the measuring device 21-23, the gas sensor 1 further comprises at least one vibration damper 51-59. This vibration damper 51-59 provides the interface between the support 31-34 and the measuring device 21-23. Thus at each place where the support 31-34 could be in contact with the measuring device 21-23, the vibration damper 51-59 is inserted between the support 31-34 and the measuring device 21-23. Thus the measuring device 21-23 as a whole is suspended relative to the support 31-34 and therefore relative to the gas pipe G.

The vibration damper 51-59 can be made of any material capable of filtering a vibration, or of any damping material.

Advantageously, said at least one vibration damper 51-59 is made of silicone.

According to another characteristic, said at least one vibration damper 51-59 comprises a forward channel 52 and a return channel 53 passing through said at least one vibration damper 51-59. The outgoing channel 52 makes it possible to transport the gas taken from the gas pipe G, by the transport device 41-44, to the measuring device 21-23, to be treated there by the measuring device 21-23. The return channel 53 makes it possible to transport the gas from the measuring device 21-23 to the gas pipe G, after its treatment. The realization of the outgoing channel 52 and the return channel 53 by crossing the vibration damper 51-59 makes it possible to ensure sealed fluidic connections between the transport device 41-44 and the measuring device 21-23.

According to another characteristic, the measuring device 21-23 comprises a sensitive cell 21 and a radiator 22. The sensitive cell 21 carries out the actual measurement and as such receives the sampled gas, treats it, before it returns to the gas pipe G. The radiator 22 cools the sensitive cell 21. Also the radiator 22 is integral, rigidly fixed to the sensitive cell 21.

According to another characteristic, the sensitive cell 21 is photo-acoustic. The principle of measurement of a photo-acoustic cell is to emit, by means of a laser, a pulsed light according to a wavelength chosen to be absorbed in the infrared by the component / the molecule which is wants to measure the concentration. The component/molecule absorbs the energy from the pulsed light and releases the excess energy as a pressure swing, creating sound in the medium. This sound is picked up by a microphone and analyzed to determine the concentration of the component/molecule. It is obvious that a vibration disturbs the microphone and therefore risks distorting the measurement.

According to another characteristic, said at least one vibration damper 51-59 is further shaped so as to include a membrane 58. This membrane 58 is continuous and extends between the sensitive cell 21 and the support 31-34. This makes it possible to produce a seal mainly against gases, but also against liquids, between the sensitive cell 21 and the support 31-34. However, it is preferable, to increase the dissipative efficiency, to let the radiator 22 come out. Also, as can be seen in the figures, the radiator 22, at least its fins, overflows outside the envelope made around of the sensitive cell 21. A contour at the level of one end 56a of the vibration damper 51-59 is assembled, in a sealed manner, substantially at the junction between the sensitive cell 21 and the radiator 22, to achieve a seal around the sensitive cell 21 while letting the radiator 22 come out. The membrane 58 continuously connects around the radiator 22 with the support 31-34 at the level of the housing 31 and its cover 32.

According to another characteristic, a stiffener 23 makes it possible to achieve the previous characteristic. For this the stiffener 23 is fixed to the radiator 22, along said junction between the sensitive cell 21 and the radiator 22. The stiffener 23 encloses the vibration damper 51-59 between the stiffener 23 and the radiator 22, so as to tighten said contour at the level of the end 56a of the vibration damper 51-59 and thus to produce a sealed assembly.

According to another characteristic, the vibration damper 51-59 still comprises at least one stud 59 at the points of contact with the support 31-34. Such contact pads 59, arranged on the surface of the vibration damper 51-59, at points where said surface is brought into contact with another part, typically the support 31-34, makes it possible to modify this contact by greatly limiting the contact surfaces. This makes it possible to reduce the stiffness of the contact, thus to lower the vibration cut-off frequency and therefore to further reduce the transmission of vibrations to the sensitive cell 21.

According to another feature, not shown, the vibration damper 51-59 is made in one piece.

According to another characteristic, the vibration damper 51-59 comprises a first part 51, substantially cylindrical. This first part 51 is, along the length of said cylinder, pierced with the outward channel 52 and the return channel 53. This first part 51 is secured to the support 31-34 by one of its ends 54b. It is still secured to the sensitive cell 21 by its other end 54a. The vibration damper 51-59 further comprises a second part 55, substantially tubular. The hollow of said tube makes it possible to contain the sensitive cell 21. A first end 56a of the tube/vibration damper 51-59 makes it possible to achieve tight connection with the radiator 22, as previously described, by clamping the contour of the said first end 56a against the radiator 22, by means of the stiffener 23. A second end 56b of the tube/vibration damper 51-59 makes it possible to achieve tight connection with the first part 51, surrounding it in a tight manner, at the level of its generatrix. Finally, the second part 55 is fixed to the support 31-34 by a protruding edge 57, here made of material, at the level of its generatrix. The border 57 is secured to the support 31-34 by clamping between a box 31 and its cover 32.

This housing 31/cover 32 assembly substantially envelops the measuring device 21-23 and the transport device 41-44 so as to protect them. The support 31-34 further comprises a flange, integral with the housing 31, composed of two half-flanges 33-34 allowing the fixing around the gas pipe G.

The transport device 41-44 comprises a collector 41 which passes through the wall of the gas pipe G in order to be able to collect gas. The collected gas is then transported via a tube 42. It then passes through a filter assembly 43. The outlet of the filter assembly 43 is connected to the forward channel 52. A washer 44 is interposed between the filter assembly 43 and the half-flange 33.

Between the ends 56a, 56b of the second part 55, the tube has a membrane 58. This membrane 58 forms the envelope around the sensitive cell 21 while having a thin thickness so as not to transmit vibration.

The measurement cell 21 is connected to the outside, typically to a processing unit, by means of a cable 62, located inside the casing, and connected to a connector 61 passing through a wall of the support 31- 34 at the housing 31. The sheet 62 is flexible so as not to transmit vibration.

Fig. 5 shows the first part 51. FIG. 5 comprises from left to right and from top to bottom: a front view, a left sectional view, a left view, a front sectional view, a perspective view according to a first point of view, a top view and a perspective view from another point of view.

Fig. 6 shows the second piece 55. FIG. 6 comprises from left to right and from top to bottom: a front view, a left sectional view, a left view, a front sectional view, a perspective view according to a first point of view, a top view and a perspective view from another point of view.

The invention also relates to an exhaust line comprising such a sensor 1.

The invention also relates to a vehicle comprising such a line or such a sensor 1.

The invention has been illustrated and described in detail in the drawings and the foregoing description. This must be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Many variant embodiments are possible.

1: gas sensor,

21: sensitive cell,

22: radiator,

23: stiffener,

31: housing,

32: lid,

33: top flange,

34: lower flange,

41: collector,

42: tubing,

43: filter assembly,

44: washer,

51: first piece,

52: forward channel,

53: return channel,

54a: first end,

54b: second end,

55: second piece,

56a: first end,

56b: second end,

57: border,

58: diaphragm,

59: pad,

G: channeling.

Claims (11)

Gas sensor (1), of the type capable of measuring a concentration of a component in a gas, comprising a measuring device (21-23), a support (31-34) capable of allowing the fixing of the measuring device ( 21-23) on a gas pipeline (G) and a transport device (41-44) able to take gas from the gas pipe (G) and to transport the gas taken from the gas pipe (G) to to the measuring device (21-23) and back, characterized in that it further comprises at least one vibration damper (51-59) arranged between the support (31-34) and the measuring device (21-23) . Sensor (1), according to the preceding claim, wherein said at least one vibration damper (51-59) is made of silicone. Sensor (1) according to any one of the preceding claims, wherein said at least one vibration damper (51-59) comprises a forward channel (52) capable of transporting the gas taken from the gas pipe (G) to the device (21-23) and a return channel (53) capable of transporting the gas from the measuring device (21-23) to the gas pipe (G). Sensor (1) according to any one of the preceding claims, in which the measuring device (21-23) comprises a sensitive cell (21) and a radiator (22) integral with the sensitive cell (21). Sensor (1) according to the preceding claim, wherein the sensitive cell (21) is photo-acoustic. Sensor (1), according to any one of the two preceding claims, wherein said at least one vibration damper (51-59) further comprises a continuous membrane (58) extending between the sensitive cell (21) and the support (31 -34), in order to ensure a seal around the sensitive cell (21), letting out the radiator (22). Sensor (1) according to any one of the three preceding claims, further comprising a stiffener (23) fixed to the radiator (22), sandwiching the vibration damper (51-59) between the stiffener (23) and the radiator (22) . Sensor (1) according to any one of the four preceding claims, wherein the vibration damper (51-59) further comprises at least one stud (59) at the points of contact with the support (31-34). Sensor (1) according to any one of the five preceding claims, wherein the vibration damper (51-59) comprises a first part (51), substantially cylindrical, comprising the forward channel (52) and the return channel (53), secured with the support (31-34) by one of its ends (54b) and with the sensitive cell (21) by its other end (54a) and a second part (55), substantially tubular, fixed to the support (31-34 ) by a border (57) secured to its generatrix, secured to the radiator (22) in a sealed manner by a first end (56a), containing the sensitive cell (21) and surrounding at a second end (56b) the first part (51) at its generatrix, in a sealed manner. Exhaust line comprising a sensor (1) according to any one of the preceding claims. Vehicle, characterized in that it comprises an exhaust line according to claim 10.