JP5362959B2 - Sensor for exhaust gas analysis - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor for exhaust gas analysis that has the measurement accuracy of exhaust gas improved by reducing the temperature deformation of a sensor body and a reflector by exhaust gas. <P>SOLUTION: In this sensor 4 for exhaust gas analysis, the sensor body 40 having an exhaust gas passage port 41 for passing the exhaust gas discharged from an engine 20 is provided with an irradiation section 5 for having a laser beam for analysis irradiated toward the inside of the exhaust gas passage port 41, a reflector unit 6 having a reflector 60 for multiply reflecting the laser beam irradiated from the irradiation section 5, and a light-receiving section 6 for receiving the laser beam that has been transmitted through the exhaust gas. A cover ring 8 of a sleeve shape is arranged inside the exhaust gas passage port 41 at a distance from the inner wall 41a of the exhaust gas passing port 41. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a technology for an exhaust gas analysis sensor, and more specifically, after irradiating a laser beam toward an exhaust gas passage hole through which exhaust gas discharged from an internal combustion engine passes, and after multiple reflections of the laser beam by a reflecting mirror The present invention relates to an exhaust gas analysis sensor for detecting laser light transmitted through exhaust gas.

  Conventionally, as an apparatus for measuring and analyzing the concentration and temperature of exhaust gas discharged from an internal combustion engine such as an engine of an automobile, etc., for exhaust gas analysis consisting of a light source, a detector, etc. in an exhaust path (pipe) A configuration of an exhaust gas analyzer configured to measure a component concentration in exhaust gas in real time by directly arranging a sensor and detecting laser light transmitted through the exhaust gas flowing through the exhaust path is known. Yes (see, for example, Patent Document 1).

The exhaust gas analysis sensor disclosed in Patent Document 1 described above irradiates laser light toward an exhaust gas passage hole through which exhaust gas discharged from an internal combustion engine passes, and after multiple reflections of laser light by a reflector, the exhaust gas It is configured to detect laser light that has passed through. In this way, the exhaust gas analysis sensor ensures a longer distance (measurement length) through which the laser light passes through the exhaust gas by multiple reflection of the laser light by the pair of reflecting mirrors facing each other in the exhaust gas passage hole of the sensor body. By doing so, the measurement accuracy is improved.
JP 2006-184180 A

  By the way, since the exhaust gas analysis sensor described above is directly disposed in the exhaust path, it receives the influence (heat radiation and heat transfer) of the high temperature exhaust gas passing through the exhaust gas passage hole of the sensor main body, Each member constituting the sensor may be deformed by temperature (thermal distortion or thermal deformation). If the sensor body and each member constituting the sensor are deformed by temperature, the irradiation unit, the light receiving unit, and the reflecting mirror are loosely fixed, and the irradiation angle and reflection angle of the laser light emitted from the irradiation unit Will cause measurement failure such that the light receiving unit cannot receive the laser beam.

  In particular, the sensor for exhaust gas analysis disclosed in Patent Document 1 described above is configured such that the inner wall of the exhaust gas passage hole and the reflecting mirror are directly exposed to the exhaust gas. There was a problem that it is easy to receive and it is easy to produce temperature deformation.

  Accordingly, the present invention relates to an exhaust gas analysis sensor, which solves the above-described conventional problems, and reduces the temperature deformation of the sensor main body and the reflector caused by the exhaust gas, thereby improving the exhaust gas measurement accuracy. Is intended to provide.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, in claim 1, an irradiation unit that irradiates a laser beam for analysis toward the inside of the exhaust gas passage hole on the sensor body in which the exhaust gas passage hole through which the exhaust gas discharged from the internal combustion engine passes is provided. In the exhaust gas analysis sensor provided with a reflecting mirror that multi-reflects the laser light emitted from the irradiation unit and a light receiving unit that receives the laser light transmitted through the exhaust gas, a sleeve-shaped cover is provided in the exhaust gas passage hole. A ring is disposed so as to be spaced apart from the inner wall of the exhaust gas passage hole, and a pin member is disposed on the sensor body along the radial direction of the exhaust gas passage hole and toward the inner direction of the exhaust gas passage hole. A groove portion is formed on the outer peripheral surface of the cover ring, and the insertion end of the pin member inserted into the exhaust gas passage hole is fitted into the groove portion of the cover ring. The relative positions of the circumferential and axial directions relative to the sensor body of burring is fixed, the length of the passage direction of exhaust gas of the cover ring, the exhaust gas passage hole approximately formed to be the same as the inner diameter of the cover ring, It is formed substantially the same as the diameter of the pipe to which the sensor body is connected.

  According to a second aspect of the present invention, the cover ring is brought into contact with the inner wall of the exhaust gas passage hole through a pin member protruding from the outer peripheral surface.

  According to a third aspect of the present invention, a laser beam passage hole through which the laser beam irradiated from the irradiation unit passes is formed on the peripheral surface of the cover ring.

  According to a fourth aspect of the present invention, the laser beam passage hole is composed of a plurality of small holes.

  As effects of the present invention, the following effects can be obtained.

  Since it has the configuration shown in claim 1, it is possible to reduce the thermal influence of the exhaust gas on the sensor main body and the reflecting mirror, so the temperature deformation of the sensor main body and the reflecting mirror due to the exhaust gas is reduced and the exhaust gas measurement accuracy is improved. it can.

  Since it is set as the structure shown in Claim 2, the contact area of a cover ring and the inner wall of an exhaust gas passage hole can be made small, and the heat input by the heat transfer from a cover ring can be reduced.

  Since it is set as the structure shown in Claim 3, only the laser beam reflected correctly by the reflecting mirror can be passed, the laser beam which remove | deviated from the optical path can be interrupted | blocked, and the measurement precision of a laser beam can be improved.

  Since it is set as the structure shown in Claim 4, compared with the case where a single elongate hole is provided, the shift | offset | difference of the optical path of a laser beam can be detected more correctly, and the measurement precision of a laser beam can be improved more.

Next, the best mode for carrying out the invention will be described.
FIG. 1 is a side view showing a state in which an exhaust gas analyzer equipped with an exhaust gas analysis sensor according to an embodiment of the present invention is mounted on a vehicle, and FIG. 2 is an exploded view showing a state in which a pipe joint is attached to the exhaust gas analysis sensor. FIG. 3 is a cross-sectional view of a sensor for exhaust gas analysis, FIG. 4 is a cross-sectional view of a cover ring mounting structure, FIG. 5 is a side cross-sectional view of the sensor for exhaust gas analysis, and FIG. 7 and 7 are perspective views of a cover ring according to another embodiment.

First, the overall configuration of the exhaust gas analyzer 1 using the exhaust gas analysis sensor 4 of the present embodiment will be outlined below.
As shown in FIG. 1, the exhaust gas analyzer 1 of the present embodiment measures and analyzes the component concentration and temperature in exhaust gas discharged from an engine 20 disposed in an automobile 2. Specifically, the exhaust gas analysis device 1 is connected to a plurality of exhaust gas analysis sensors 4 disposed at a plurality of locations in the exhaust gas exhaust path 3 extending from the engine 20 and the exhaust gas analysis sensor 4. The controller 10 includes a laser transmitting / receiving controller 10 and a computer device 11 connected to the controller 10.

  The automobile 2 is provided with an exhaust path 3 for discharging exhaust gas from the engine 20 to the outside of the machine. The exhaust path 3 includes an exhaust manifold 30, an exhaust pipe 31, a first catalyst device 32, a second catalyst device 33, and a muffler 34. And the exhaust pipe 35 and the like. In addition, each component device of the exhaust path 3 is connected by a pipe 3a having a circular cross section.

  In the exhaust path 3, the exhaust gas of the engine 20 is first merged in the exhaust manifold 30, introduced into the first catalyst device 32 and the second catalyst device 33 through the exhaust pipe 31, and then into the atmosphere from the exhaust pipe 35 through the muffler 34. Released. By forming such an exhaust path 3, the exhaust gas from the engine 20 is purified by the two catalytic devices 32 and 33, muffled and decompressed by the muffler 34, and released into the atmosphere.

  Exhaust gas analysis sensors 4, 4... Are arranged at four locations in the exhaust path 3, specifically, between the engine 20 on the upstream side of the first catalyst device 32 and the exhaust pipe 31. They are arranged between the catalyst device 32 and the second catalyst device 33, between the second catalyst device 33 and the muffler 34, and at the end of the exhaust pipe 35 on the downstream side of the muffler 34.

  In the exhaust gas analyzer 1 of the present embodiment, in each exhaust gas analysis sensor 4, data obtained by receiving the infrared laser light by the controller 10 and receiving the laser light after passing through the exhaust gas is the controller. 10 is sent to the computer device 11 to analyze the components in the exhaust gas.

The controller 10 is an irradiation device that irradiates infrared laser light having a plurality of wavelengths, and the wavelength of the laser light is set according to the component of the exhaust gas to be detected. Further, the controller 10 is provided with a differential type photodetector (not shown) connected to the exhaust gas analysis sensor 4, and the signal light received by the exhaust gas analysis sensor 4 is guided to pass through the exhaust gas. The signal light of the laser beam transmitted and attenuated and the laser beam not transmitted through the exhaust gas is output to the connected computer device 11.
The computer apparatus 11 analyzes the output signal from the controller 10 to analyze the exhaust gas by calculating the component concentration of the exhaust gas and the temperature of the exhaust gas.

  Thus, in the exhaust gas analyzer 1 of the present embodiment, spot exhaust gas can be measured in one section of the exhaust path 3 by each exhaust gas analyzing sensor 4. In particular, as in the present embodiment, the exhaust gas analysis sensors 4 are provided at a plurality of locations in the exhaust path 3 so that it is possible to instantaneously measure how the exhaust gas changes in a predetermined section of the exhaust path 3. The state of exhaust gas can be continuously measured in real time.

  In the exhaust gas analyzer 1 of the present embodiment, the exhaust gas analysis sensors 4, 4... Arranged in the exhaust path 3 are configured substantially the same. The exhaust gas analysis sensor 4 disposed between the device 32 and the second catalyst device 33 will be described.

Next, the configuration of the exhaust gas analysis sensor 4 will be described in detail below.
As shown in FIGS. 2 and 3, the exhaust gas analyzing sensor 4 of the present embodiment has a circular exhaust gas passage hole 41 through which exhaust gas passes in a sensor body 40 formed of a thin plate-like member having a circular shape in plan view. The irradiation unit 5 that irradiates the laser beam for analysis toward the exhaust gas passage hole 41, the pair of reflecting mirror units 6 and 6 that multiplexly reflect the laser beam irradiated from the irradiation unit 5, and the exhaust gas A light receiving portion 7 for detecting the transmitted laser light, a sleeve-shaped cover ring 8 disposed in the exhaust gas passage hole 41, and the like are provided.
In the exhaust gas analyzing sensor 4, laser light is irradiated from the irradiation unit 5 along a cross section orthogonal to the exhaust path 3, and the irradiated laser light crosses the exhaust path 3 between the reflecting mirrors 60 of the reflecting mirror unit 6. As described above, the light is received by the light receiving unit 7 a plurality of times.

As shown in FIG. 2, the sensor 4 for exhaust gas analysis is fixed in a state where the sensor body 40 is sandwiched between a pair of pipe joints 36 and 36, and the pipe joints 36 and 36 are respectively connected to the first catalyst device 32 and the second catalyst. By being connected to the pipes 3 a and 3 a connected to the apparatus 33, the exhaust path 3 is arranged.
The pipe joints 36 and 36 are formed in a cylindrical shape with a through hole 36a having a circular cross section, and a flange portion 36b is provided at one opening edge. The exhaust gas analysis sensor 4 (the sensor body 40) is sandwiched between gaskets 37 and 37 at the opening end on the side where the flange portion 36b of the pair of pipe joints 36 and 36 is provided. 36 b is fixed by fastening with bolts 38.

  The through hole 36a of the pipe joint 36 is formed in a circular shape having the same diameter as that of the pipe 3a, and is configured so that the flow of exhaust gas is not hindered. Further, the gasket 37 has a hole having substantially the same diameter as the through hole 36a and the like, and even if the exhaust gas analyzing sensor 4 is sandwiched between the pipe joints 36 and 36 and connected to the pipe 3a, the exhaust gas leaks in the middle. There is no increase in the length of the exhaust path.

  In this way, the exhaust gas analysis sensor 4 is connected to the pipes 3a of the exhaust path 3 via the pipe joints 36 and 36 described above, and the exhaust gas flowing through the exhaust path 3 passes through the one pipe joint 36. After being sent to the sensor body 40 through the hole 36 a, it passes through the exhaust gas passage hole 41 of the sensor body 40 and is sent to the downstream side of the exhaust path 3 from the through hole 36 a of the other pipe joint 36.

Next, the sensor body 40 will be described in detail below.
As shown in FIG. 3, the sensor main body 40 serving as a machine base constituting the exhaust gas analysis sensor 4 is composed of a thin plate-like metal member formed in a circular shape in plan view as described above. A circular exhaust gas passage hole 41 is bored at a substantially central portion of the orthogonal facing surface.
The sensor body 40 of the present embodiment is provided with mounting holes 40a and 40b penetrating in the direction perpendicular to the flow direction of the exhaust gas from the outside to the exhaust gas passage hole 41 through the central portion of the plate thickness. The irradiation part 5 is attached to the hole 40a, and the light receiving part 7 is attached to the attachment hole 40b. The irradiation unit 5 and the light receiving unit 7 are respectively attached at positions facing the axial center of the exhaust gas passage hole 41.

  In addition, a pair of mounting grooves 40c and 40c are formed in the inner wall 41a of the exhaust gas passage hole 41 of the sensor body 40 toward the radially outer side of the exhaust gas passage hole 41, and each of the mounting grooves 40c and 40c passes through the exhaust gas passage. It is provided at a position facing the axial center of the hole 41. The reflecting mirror unit 6 is mounted in the mounting grooves 40c and 40c, and the reflecting surface of the reflecting mirror 60 constituting the reflecting mirror unit 6 is disposed so as to face the internal space of the exhaust gas passage hole 41.

  Thus, by attaching each member, in the exhaust gas analysis sensor 4, the laser light emitted from the irradiation unit 5 is introduced into the exhaust gas passage hole 41 through the attachment hole 40 a, and the inside of the exhaust gas passage hole 41. After the laser light introduced into is reflected multiple times between the reflecting mirrors 60 and 60, it is led out to the light receiving section 7 through the mounting hole 40b.

Next, the irradiation unit 5 and the light receiving unit 7 will be described in detail below.
As shown in FIG. 3, the irradiation unit 5 includes an optical fiber 50 for infrared transmission, and a connection block 51 that positions and attaches the optical fiber 50 to the sensor body 40.
The optical fiber 50 is connected to a light incident collimator 51 a provided in the connection block 51, and is attached so that the light projecting surface faces the center of the exhaust gas passage hole 41 of the sensor body 40. In the connection block 51, a light passage hole 52 is formed so as to penetrate from the light projecting surface of the optical fiber 50 to the attachment hole 40 a in a state where the connection block 51 is attached to the sensor body 40.
The optical fiber 50 is connected to the controller 10 described above, and the laser light emitted from the controller 10 is irradiated from the optical fiber 50 and enters the exhaust gas passage hole 41 from the light passage hole 52 through the attachment hole 40a. be introduced.

On the other hand, the light receiving unit 7 includes a detector 70 that detects laser light, and a connection block 71 that positions and attaches the detector 70 to the sensor body 40.
The detector 70 is connected to a light receiving collimator 71 a provided in the connection block 71 and attached so that its light receiving surface faces the center of the exhaust gas passage hole 41 of the sensor body 40. In the connection block 71, a light passage hole 72 is formed so as to penetrate from the light receiving surface of the detector 70 to the attachment hole 40 b in a state where the connection block 71 is attached to the sensor body 40.
The detector 70 is connected to the controller 10 described above, and the laser light transmitted through the exhaust gas is led out of the exhaust gas passage hole 41 from the mounting hole 40b through the light passage hole 72 and received by the detector 70. A light reception signal is input to the controller 10.

Next, the reflecting mirror unit 6 will be described in detail below.
As shown in FIGS. 3 and 4, the reflecting mirror unit 6 includes a reflecting mirror 60 that reflects the laser light emitted from the irradiation unit 5, a heater 61 as a heating member for preventing condensation of the reflecting mirror 60, and a sensor. A buffer member 62 composed of a member that absorbs the difference in temperature deformation between the main body 40 and the reflecting mirror 60, and the pressing plates 63 and 64, etc. are configured as unit bodies that are stacked and housed in the casing 65, respectively. Has been. Specifically, the reflecting mirror 60, one presser plate 63, the heater 61, the buffer member 62, and the other presser plate 64 are stacked and accommodated in the space provided in the casing 65 in the vertical direction. .

  In one side surface of the casing 65, a slit 65b having a long hole shape in plan view is formed along the longitudinal direction, and the space portion is continuous with the external space through the slit 65b. The reflecting mirror 60 accommodated in the space is exposed to the external space such that the reflecting surface closes the slit 65b.

  The reflecting mirror unit 6 is attached to a mounting groove 40c that is recessed in the inner wall 41a of the exhaust gas passage hole 41 of the sensor body 40 described above. In the present embodiment, the reflecting mirror unit 6 is inserted from the outside of the sensor body 40 toward the inside of the exhaust gas passage hole 41 with the upper surface in contact with the inner wall 41 a of the exhaust gas passage hole 41 of the sensor body 40. The sensor body 40 is fastened by a plurality of screw members 66, 66... (Four in this embodiment).

  When the reflector unit 6 is attached to the attachment groove 40c of the sensor body 40, the reflector unit 6 is positioned so that the attachment groove 40c and the casing 65 are in close contact with each other. Further, the reflecting surface of the reflecting mirror 60 faces the exhaust gas passage hole 41, and the reflecting mirrors 60 and 60 of the pair of reflecting mirror units 6 and 6 are vertically opposed to each other. In this state, the lower surface of the casing 65 is accommodated in the mounting groove 40 c without protruding from the inner wall 41 a toward the axial center of the exhaust gas passage hole 41.

  As described above, the exhaust gas analyzing sensor 4 is configured such that the pair of reflecting mirror units 6 (and the reflecting mirror 60) is disposed in the sensor body 40, so that the laser light irradiated into the exhaust gas passage hole 41 from the irradiation unit 5. Is reflected toward the reflecting mirror 60 of the other reflecting mirror unit 6 (upper in FIG. 3) by the reflecting mirror 60 of one reflecting mirror unit 6 (lower in FIG. 3). In this way, the laser light passes through the exhaust gas while being alternately reflected a plurality of times by the two reflecting mirrors 60 and 60 and eventually reaches the light receiving unit 7.

Next, the cover ring 8 will be described in detail below.
As shown in FIGS. 4 to 6, the cover ring 8 of the present embodiment is a sleeve-shaped member formed in a cylinder having a passage hole 81, and the exhaust gas passage is in the exhaust gas passage hole 41 of the sensor body 40. The hole 41 is disposed so as to be separated from the inner wall 41 a of the hole 41.
Specifically, the cover ring 8 is made of a material having low thermal conductivity such as ceramic, and is formed in a cylindrical sleeve shape having an exhaust gas passage hole 81 in the center. The cover ring 8 is formed such that the inner diameter of the passage hole 81 is slightly smaller than the inner diameter of the exhaust gas passage hole 41 and is substantially the same as the width of the sensor body 40 (the exhaust gas passage hole 41).

  That is, the cover ring 8 of the present embodiment is spaced apart from the inner wall 41a of the exhaust gas passage hole 41 and covers the inner wall 41a of the exhaust gas passage hole 41 in a state of being disposed in the exhaust gas passage hole 41. It is arranged in this way. Thus, the sensor main body 40 of the present embodiment covers the inner wall 41a of the exhaust gas passage hole 41 by the cover ring 8, so that the exhaust gas flowing through the exhaust gas passage hole 41 is not directly exposed to the inner wall 41a. The heat input to can be reduced.

The inner diameter of the passage hole 81 of the cover ring 8 is formed to be substantially the same as the diameter of the through hole 36 a of the pipe joint 36 and the hole 37 a of the gasket 37 described above. Further, in a state where the pipe joint 36 and the gasket 37 are attached to the exhaust gas analysis sensor 4, the cover ring 8 and the flange portion 36b of the pipe joint 36 and the gasket 37 are attached as close as possible.
With such a configuration, the exhaust gas that passes through the passage hole 81 of the cover ring 8 is prevented from leaking to the flange portion 36b of the pipe joint 36 and the gasket 37.

Further, the cover ring 8 is in contact with the inner wall 41a of the exhaust gas passage hole 41 via a pin member 82 that protrudes from the outer peripheral surface by a predetermined length in a state of being disposed in the exhaust gas passage hole 41.
The pin member 82 is, for example, a rod-like member whose outer peripheral surface is threaded, such as a worm screw or a set screw, and mounting holes 83, 83, drilled at a predetermined position substantially in the center in the width direction of the cover ring 8. ··· is screwed from the inner space of the passage hole 81 of the cover ring 8 toward the outside in the radial direction. The pin member 82 screwed into the mounting hole 83 is fixed so as to protrude from the outer peripheral surface of the cover ring 8 by a predetermined length.

  The cover ring 8 is positioned with respect to the exhaust gas passage hole 41 (the inner wall 41a thereof) by the pin members 82, 82... Protruding from the outer peripheral surface of the cover ring 8. That is, in the state in which the cover ring 8 is disposed in the exhaust gas passage hole 41, the pin member 82 protrudes from the outer peripheral surface by a predetermined length, whereby the outer peripheral surface of the cover ring 8 and the inner wall of the exhaust gas passage hole 41. The separation from 41a is adjusted so as to be uniform in the circumferential direction, and is positioned in the radial direction so as to be positioned substantially at the center of the exhaust gas passage hole 41.

  The cover ring 8 is fixed to the sensor main body 40 by a fixing pin 84 inserted into the sensor main body 40. Specifically, the sensor body 40 is displaced in the width direction along the radial direction of the exhaust gas passage hole 41 and in the width direction so as not to interfere with the optical path of the laser light. A through hole 40 e is formed at a position, and a fixing pin 84 is inserted into the through hole 40 e from the outside of the sensor body 40 toward the inside of the exhaust gas passage hole 41. In the present embodiment, the through holes 40e are drilled at two positions facing the axial center of the exhaust gas passage hole 41 of the sensor body 40.

  On the outer peripheral surface of the cover ring 8, a groove portion 85 fitted to the insertion end of the fixing pin 84 is recessed, and in the state where the cover ring 8 is disposed in the exhaust gas passage hole 41, the above-described through hole is formed. The insertion end of the fixing pin 84 inserted into 40e is fitted. In the present embodiment, the fixing pin 84 inserted into each pipe through hole 40e is fitted into the groove portion 85 of the cover ring 8, so that the cover ring 8 is in the circumferential direction and the axial direction (thrust direction) with respect to the sensor body 40. The direction is fixed so that the relative position cannot be changed.

  In this way, the cover ring 8 of the present embodiment is not firmly fixed to the sensor body 40 with a bolt member or the like, but is fixed with a certain degree of freedom. Even when the cover ring 8 that is most affected by the heat is subjected to temperature deformation, the cover ring 8 can be prevented from rotating and disposed in the thrust direction.

  On the peripheral surface of the cover ring 8, a pair of elongated laser beam passage small holes 86 are formed at positions facing the axial center of the passage hole 81 (see FIG. 6). The laser light passage small hole 86 is configured so that the laser light irradiated from the irradiation unit 5 toward the exhaust gas passage hole 41 is reflected a plurality of times between the reflecting mirrors 60 and 60 and then received by the light receiving unit 6. It is provided on the optical path of the laser beam. By providing the laser beam passage small hole 86, only the laser beam accurately reflected by the reflecting mirror 60 can be passed, and the laser beam deviating from the optical path can be blocked, and the measurement accuracy of the laser beam can be improved.

  As described above, the sensor 4 for exhaust gas analysis of the present embodiment is for analysis toward the sensor body 40 having the exhaust gas passage hole 41 through which the exhaust gas discharged from the engine 20 passes. An irradiating unit 5 that irradiates the laser beam, a reflecting mirror unit 6 that includes a reflecting mirror 60 that multi-reflects the laser beam irradiated from the irradiating unit 5, and a light receiving unit 6 that receives the laser beam that has passed through the exhaust gas. In the exhaust gas analysis sensor 4 in which the exhaust gas passage hole 41 is provided, the sleeve-shaped cover ring 8 is disposed so as to be separated from the inner wall 41 a of the exhaust gas passage hole 41. Therefore, it is possible to reduce the temperature deformation of the sensor main body 40 and the reflecting mirror 60 and improve the measurement accuracy of the exhaust gas.

That is, the exhaust gas analysis sensor 4 is directly exposed to the sensor main body 40 and the high-temperature exhaust gas because various optical devices such as the irradiation unit 5, the reflecting mirror unit 6, and the light receiving unit 7 are attached as described above. It is important to reduce the thermal influence on the reflecting mirror 60 as much as possible to prevent the irradiation unit 5, the light receiving unit 7, and the reflecting mirror 60 from being loosened. Therefore, as in the present embodiment, the cover ring 8 is disposed in the exhaust gas passage hole 41 so as to be separated from the inner wall 41a, so that the sensor body 40 (the inner wall 41a of the exhaust gas passage hole 41) passes through the exhaust gas. The exhaust gas sent to the hole 41 can be isolated from the exhaust gas, and the exhaust gas flowing through the exhaust gas passage hole 41 is not directly exposed to the inner wall 41a, so that the radiant heat from the high temperature exhaust gas can be largely blocked.
Further, since the cover ring 8 is not directly in contact with the sensor body 40 (the inner wall 41a of the exhaust gas passage hole 41), the heat radiation and heat transfer to the sensor body 40 and the reflecting mirror 60 should be minimized. In addition, heat input by heat transfer from the cover ring 8 can be greatly reduced by separation (part).
As described above, by adopting the configuration of this embodiment, it is possible to reduce the thermal influence of the exhaust gas on the sensor main body 40 and the reflecting mirror 60, thereby reducing the temperature deformation of these members and improving the measurement accuracy of the exhaust gas. It can be improved.

  In particular, since the cover ring 8 of the present embodiment is brought into contact with the inner wall 41a of the exhaust gas passage hole 41 via the pin member 82 protruding from the outer peripheral surface, the cover ring 8 and the inner wall 41a of the exhaust gas passage hole 41 are in contact with each other. The contact area can be reduced, and heat input due to heat transfer from the cover ring 8 can be reduced.

  Further, since a laser beam passage hole through which the laser beam emitted from the irradiation unit 5 passes is formed on the peripheral surface of the cover ring 8 of the present embodiment, only the laser beam reflected accurately by the reflecting mirror 60 is used. It is possible to block the laser beam that has passed through and deviated from the optical path, and to improve the measurement accuracy of the laser beam.

  In addition, as a structure of the sensor 4 for exhaust gas analysis, it is not limited to the Example mentioned above.

That is, in the above-described embodiment, the cover ring 8 is configured to be positioned and fixed in the exhaust gas passage hole 41 by the pin member 82 and the fixing pin 84, but the mounting structure of the cover ring 8 is as follows. There is no particular limitation.
The pin member 82 is not particularly limited as long as it is a member that positions the cover ring 8 relative to the exhaust gas passage hole 41 of the sensor main body 40. However, as in the above-described embodiment, the pin member 82 is a rod-shaped member. By using a member, the contact area with the inner wall 41a of the exhaust gas passage hole 41 can be reduced, which is preferable.

As shown in FIG. 7, the cover ring 8 is configured such that a laser beam passage hole 86 formed on the peripheral surface of the cover ring 8 is composed of a plurality of small holes 86 a, 86 a. May be. Since a plurality of small holes 86a, 86a,... Are disposed in advance on the optical path of the laser beam, the deviation of the optical path of the laser beam can be detected more accurately compared to the laser beam passage hole 86 having a long hole shape. Therefore, the measurement accuracy of the laser beam can be further improved.
However, the arrangement and number of the small holes 86a, 86a,... Are not particularly limited, and can be appropriately selected and changed according to the configuration of the exhaust gas analysis sensor 4.

  Moreover, although the reflecting mirror unit 6 of the Example mentioned above is comprised so that the reflecting mirror 60 etc. may be accommodated in the casing 65, the attachment structure of the reflecting mirror 60 is not limited to this, For example, a pair of plate shape The reflecting mirror 60 may be sandwiched and fixed integrally by a member, and this may be configured to be fastened to the sensor body 40 by a screw member 66.

  Further, the configuration of the irradiation unit 5 and the light receiving unit 7 constituting the exhaust gas analysis sensor 4 is not particularly limited. For example, the laser beam irradiated from the irradiation unit 5 may be an infrared laser beam or an ultraviolet laser beam, A laser diode or a photodiode may be used instead of the optical fiber 50 or the detector 70.

The side view which showed the state which mounted the exhaust gas analyzer provided with the sensor for exhaust gas analysis which concerns on one Example of this invention in the vehicle. The disassembled perspective view and side view which show the state which attached the pipe joint to the sensor for exhaust gas analysis. Sectional drawing of the sensor for exhaust gas analysis. Sectional drawing which showed the attachment structure of the cover ring. The sectional side view of the sensor for exhaust gas analysis. The perspective view of a cover ring. The perspective view of the cover ring of another Example.

DESCRIPTION OF SYMBOLS 1 Exhaust gas analyzer 4 Exhaust gas analysis sensor 5 Irradiation part 6 Reflector unit 7 Light receiving part 8 Covering 20 Engine (internal combustion engine)
40 Sensor Body 41 Exhaust Gas Passing Hole 41a Inner Wall 60 Reflecting Mirror 81 Passing Hole 82 Pin Member 83 Mounting Hole 86 Laser Light Passing Hole

Claims (4)

An irradiation unit that irradiates a sensor body having an exhaust gas passage hole through which an exhaust gas discharged from an internal combustion engine passes, and an laser beam for analysis toward the inside of the exhaust gas passage hole, and a laser irradiated from the irradiation unit In an exhaust gas analysis sensor provided with a reflecting mirror that multi-reflects light and a light receiving unit that receives laser light transmitted through the exhaust gas,
A sleeve-shaped cover ring is disposed in the exhaust gas passage hole so as to be separated from the inner wall of the exhaust gas passage hole,
A pin member is inserted into the sensor body along the radial direction of the exhaust gas passage hole and toward the internal direction of the exhaust gas passage hole,
A groove is formed on the outer peripheral surface of the cover ring,
The insertion end of the pin member inserted into the exhaust gas passage hole is fitted into the groove portion of the cover ring, so that the circumferential and axial relative positions of the cover ring with respect to the sensor body are fixed,
The length of the exhaust gas passing direction of the cover ring is formed substantially the same as the exhaust gas passage hole ,
The inner diameter of the cover ring is formed substantially the same as the diameter of the pipe to which the sensor body is connected.
An exhaust gas analysis sensor characterized by the above.   The exhaust gas analysis sensor according to claim 1, wherein the cover ring is brought into contact with an inner wall of the exhaust gas passage hole through a pin member protruding from an outer peripheral surface.   3. The exhaust gas analysis sensor according to claim 1, wherein a laser beam passage hole through which the laser beam emitted from the irradiation unit passes is formed on a peripheral surface of the cover ring.   The sensor for exhaust gas analysis according to claim 3, wherein the laser beam passage hole includes a plurality of small holes.

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