JP5052259B2 - Sensor for exhaust gas analysis - Google Patents

Description

  The present invention relates to a technology of an exhaust gas analysis sensor. Specifically, the exhaust gas is irradiated with laser light toward the exhaust gas passage hole through which exhaust gas discharged from an internal combustion engine or the like passes, and after the laser beam is multiple-reflected by a reflecting mirror, the exhaust gas that detects laser light transmitted through the exhaust gas is detected. The present invention relates to an analysis sensor.

Conventionally, as an apparatus used for measuring and analyzing the component concentration and temperature of combustion product gas such as H ₂ O, CO ₂ and NO contained in exhaust gas discharged from an internal combustion engine such as an automobile engine, the following An exhaust gas analyzer having such a structure is known. That is, an exhaust gas analysis sensor including a light source and a detector unit is directly disposed in an exhaust path (pipe) from the internal combustion engine, and laser light transmitted through the exhaust gas flowing through the exhaust path is detected. In this configuration, the component concentration in the exhaust gas is measured in real time (see, for example, Patent Document 1).

  For example, an exhaust gas analysis sensor disclosed in Patent Document 1 irradiates laser light toward an exhaust gas passage hole through which exhaust gas discharged from an internal combustion engine passes, and multiple reflections (reflection multiple times) of the laser light by a reflecting mirror. Then, the laser beam transmitted through the exhaust gas is detected. In other words, the sensor for exhaust gas analysis having such a configuration multiplexes the laser light irradiated toward the exhaust gas passage hole formed in the sensor body in the exhaust gas by a pair of mirrors that are opposed to each other in the exhaust gas passage hole. Detect after reflection. The reason why the laser beam is configured to be multiple-reflected is as follows. That is, in the exhaust gas analyzer configured as described above, the component concentration and the like in the exhaust gas are measured based on the absorption spectrum of the laser light that has passed through the exhaust gas detected by the exhaust gas analysis sensor. For this reason, as for the laser light detected by the exhaust gas analysis sensor, the measurement sensitivity increases and the measurement accuracy can be improved as the distance (measurement length) passing through the exhaust gas increases. Therefore, as described above, the laser beam is configured to be multiple-reflected in the exhaust gas, so that a longer distance (measurement length) for the laser beam to pass through the exhaust gas is secured, and the concentration of components in the exhaust gas is measured. The measurement accuracy of is improved.

As described above, the exhaust gas analyzing sensor configured to multiple-reflect laser beams has the following problems.
In the multiple reflection of the laser light in the exhaust gas analysis sensor, a pair of mirrors facing each other in the exhaust gas passage hole is used as described above. That is, the laser beam is reflected a plurality of times between a pair of opposing mirrors and reciprocates between the mirrors. Here, since the “distance” through which the laser light passes through the exhaust gas is used when measuring the component concentration or the like in the exhaust gas, the number of reflections of the laser light between the mirrors is set to a predetermined number in advance. In other words, in measurements using an exhaust gas analysis sensor that multi-reflects laser light, the number of times the laser light is reflected from the viewpoint of keeping the optical path length (measurement length) of the laser light constant in order to guarantee the quantitativeness of the measured value. Is required to be maintained a predetermined number of times.

On the other hand, in the sensor for exhaust gas analysis, the optical axis (path) of the laser beam is shifted due to temperature deformation (thermal strain or thermal deformation) due to the influence of high temperature exhaust gas passing through the exhaust gas passage hole, impact from the outside, or the like. Sometimes. In this regard, even when the optical axis of the laser beam is deviated, depending on the deviation, the detection of the laser beam itself is continued with the number of reflections of the laser beam reflected between mirrors changed (increase / decrease). There is. That is, when the optical axis of the laser beam is shifted, the laser beam reflected by the number of times changed from a predetermined number of reflections is received by the prescribed light receiving unit. Further, the change in the number of reflections of the laser beam due to the deviation of the optical axis of the laser beam in this way depends on the measurement value (change) in measuring the concentration of the component in the exhaust gas depending on the preset number of reflections. May be difficult to distinguish. In other words, the measured value of the component concentration in the exhaust gas also changes depending on the condition of the measuring device and the internal combustion engine, and so the change in the measured value is caused by the change in the number of reflections of the laser light. It may not be possible to identify. In such a case, although the measurement itself continues smoothly, the number of reflections of the laser light has changed from a predetermined number of times set in advance, so that the quantitativeness of the measured value cannot be guaranteed.
Therefore, in the exhaust gas analysis sensor having the configuration in which the laser beam is multiply reflected as described above, the laser beam is periodically or when a phenomenon causing the deviation of the optical axis of the laser beam occurs. It is necessary to check the number of reflections.

Conventionally, the number of reflections of laser light in an exhaust gas analysis sensor (hereinafter also simply referred to as “sensor”) has been confirmed as follows.
That is, first, the sensor directly disposed in the exhaust path (pipe) as described above is once removed from the pipe. Next, the number of times the laser beam is reflected by the removed sensor is confirmed by using a sensor card or the like. Then, the sensor whose number of reflections of the laser beam has been confirmed is attached again to the original position in the exhaust path.
Thus, when confirming the number of reflections of laser light in a conventional sensor, a complicated operation of removing the sensor → confirming the number of reflections → reattaching the sensor is required.

As described above, the problems in the conventional exhaust gas analysis sensor are caused mainly by the following two reasons.
One is that the sensor does not have a structure for defining (limiting) the path of the laser light and the number of reflections inside the sensor body. In other words, since the sensor does not have a structure for defining the path of the laser beam, etc., as described above, measurement continues even when the number of reflections of the laser beam has changed from a predetermined number of times set in advance. May be. For this reason, it is necessary to confirm the number of reflections of laser light.
Secondly, in the sensor attached at a predetermined position in the exhaust path (pipe), the optical axis position of the laser beam and the number of reflections cannot be confirmed from the outside. For this reason, in order to confirm the number of times of reflection of the laser beam by the sensor, the complicated work as described above is required.
JP 2006-343293 A

  The present invention has been made in view of the above-described problems of the prior art, and the problem to be solved is that in a configuration in which laser light is multiple-reflected in exhaust gas to be analyzed, Providing a sensor for exhaust gas analysis that can specify (limit) the number of paths and the number of reflections, guarantee the quantitativeness of measured values, and eliminate the need to check the number of reflections of laser light. There is to do.

  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, the flange portion disposed at a position sandwiched between the upstream side pipe and the downstream side pipe that conveys the exhaust gas to be analyzed, and provided at the downstream end of the upstream side pipe And a pair of contact surfaces that contact a flange portion provided at an upstream end portion of the downstream pipe via a gasket, and an exhaust gas passage hole through which the exhaust gas passes through the pair of contact surfaces. a sensor body having having an irradiation unit for irradiating a laser beam for analysis toward the exhaust gas passage hole, the reflective surface for reflecting the laser beam in the exhaust gas passage hole, the laser beam predetermined a photodetection unit for receiving a reflection portion that transmits the exhaust gas, the laser beam transmitted through the exhaust gas of the exhaust gas passage hole in a predetermined path in the exhaust gas passage hole by number of reflections, the waste gas A cylindrical member that covers the reflecting surface by being provided in the exhaust gas passage hole in a state where a gap is separated from a wall surface that forms a hole, the inner diameter of which is an upstream pipe and a downstream pipe An optical path restriction having a passage hole portion that is substantially the same as the inner diameter, has a length in the cylinder axis direction that is substantially the same as the length of the exhaust gas passage hole, and allows a laser beam to enter and reflect on a reflecting surface in a predetermined path. A member and a positioning jig for positioning the radial position of the optical path limiting member in the exhaust gas passage hole so as to be adjustable .

The exhaust gas analyzing sensor according to claim 1, wherein the positioning jig is screwed into a screw hole provided in the sensor body and opening in the exhaust gas passage hole, and the exhaust gas passage hole. The tip part projected inward consists of a spacer pin which contacts the outer peripheral surface of the optical path limiting member.

According to a third aspect of the present invention, in the exhaust gas analyzing sensor according to the second aspect, a fixing jig is provided for fixing a radial position of the optical path limiting member in the exhaust gas passage hole.

According to a fourth aspect of the present invention, in the exhaust gas analysis sensor according to the third aspect, the fixing jig is rotatably provided in a through-hole penetrating from the outer peripheral surface of the sensor body to the exhaust gas passage hole. The portion protrudes into the exhaust gas passage hole, and includes a fixing bolt in which a male screw formed at the tip is screwed into a screw hole formed in the optical path limiting member.

In claim 5, the sensor for exhaust gas analysis according to any one of claims 1 to 4, wherein the irradiation unit and the light receiving portion is fixed to the sensor body, the exhaust gas passage hole The first optical path forming member that forms the first optical path communicating with the first optical path forming member and the attitude relative to the first optical path forming member are adjusted, so that the irradiation direction of the laser light with respect to the exhaust gas passage hole in the irradiation unit or The light receiving direction of the laser light from the exhaust gas passage hole in the light receiving unit is adjusted, and a second optical path forming member that forms a second optical path communicating with the first optical path, and the first An adjusting member for engaging the optical path forming member with the second optical path forming member, and adjusting an attitude of the second optical path forming member with respect to the first optical path forming member; The second optical path forming member is interposed between the first optical path forming member and the second optical path forming member in a state of being engaged with each other by the adjusting member, and the second optical path forming member is elastically attached to the first optical path forming member. And an elastic member that holds the posture.

According to a sixth aspect of the present invention, in the exhaust gas analysis sensor according to the fifth aspect , the elastic member is made of a material having a lower thermal conductivity than a material constituting the first optical path forming member.

As effects of the present invention, the following effects can be obtained.
That is, according to the present invention, in a configuration in which laser light is multiple-reflected in the exhaust gas to be analyzed, the path of the laser light and the number of reflections can be defined (restricted), and the quantitativeness of the measured value is guaranteed. In addition, the work for confirming the number of reflections of the laser beam can be omitted.

Next, embodiments of the invention will be described.
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 this 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.

  An exhaust path 3 for discharging exhaust gas from the engine 20 to the outside of the machine is laid in the automobile 2. The exhaust path 3 includes an exhaust manifold 30, an exhaust pipe 31, a first catalyst device 32, a second catalyst device 33, a muffler 34, an 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 from the exhaust pipe 35 through the muffler 34 to the atmosphere. To be 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.

  The exhaust gas analysis sensors 4 are arranged at four locations in the exhaust path 3. Specifically, the exhaust gas analysis sensor 4 is provided between the upstream side of the first catalyst device 32 and the exhaust pipe 31 of the engine 20, between the first catalyst device 32 and the second catalyst device 33, and between the second catalyst device. 33 and the muffler 34 are respectively disposed at the end portions 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, the 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 beams having a plurality of wavelengths. 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 photodetector (not shown) connected to the exhaust gas analysis sensor 4. The signal light received by the exhaust gas analysis sensor 4 is guided by the controller 10, and the signal light of the laser light transmitted through the exhaust gas and attenuated and the laser light not transmitted through the exhaust gas are computer devices. 11 is output.
In the computer device 11, the output signal from the controller 10 is analyzed, and the exhaust gas analysis is performed 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, it is possible to measure spot exhaust gas in one section of the exhaust path 3 by each exhaust gas analysis 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.

  Next, the configuration of the exhaust gas analysis sensor 4 will be described in detail below. 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.

  As shown in FIGS. 2 and 3, the exhaust gas analyzing sensor 4 of the present embodiment includes a sensor main body 40 having an exhaust gas passage hole 41 through which exhaust gas to be analyzed passes, and an irradiation unit that irradiates laser light for analysis. 5, reflection parts 6 and 6 having a reflection surface 60 a for reflecting the laser light in the exhaust gas passage hole 41, and a light receiving part 7 for receiving the laser light transmitted through the exhaust gas in the exhaust gas passage hole 41. Prepare.

In the present embodiment, the sensor body 40 has an exhaust gas passage hole 41 formed in a circular shape at a substantially central portion of a substantially disk-shaped member, and is configured in a substantially cylindrical shape as a whole. Therefore, as shown in FIG. 3, the sensor body 40 has a substantially annular shape when viewed in the direction in which the exhaust gas flows in the exhaust gas passage hole 41 (the axial direction of the exhaust gas passage hole 41, hereinafter also referred to as “exhaust gas flow direction”). Become.
Moreover, in this embodiment, the reflection part 6 is comprised by the reflective mirror unit which has the reflective mirror 60 which forms the reflective surface 60a. In the present embodiment, each of the pair of reflecting portions 6 is provided on both sides in the radial direction with respect to the exhaust gas passage hole 41. The pair of reflecting portions 6 are provided such that the reflecting surfaces 60a face each other in parallel.
In the exhaust gas analysis sensor 4, laser light is irradiated from the irradiation unit 5 along one cross section orthogonal to the exhaust path 3, and the irradiated laser light is exhausted between the reflection surfaces 60 a and 60 a of the reflection unit 6. The light is reflected by a plurality of times (multiple reflection) so as to cross the path 3 and received by the light receiving unit 7.

  As shown in FIG. 2, the exhaust gas analysis sensor 4 is fixed in a state where the sensor body 40 is sandwiched between a pair of pipe joints 36 and 36. The pipe joint 36 on one side (upstream side) is connected to the pipe 3 a connected to the first catalyst device 32, and the pipe joint 36 on the other side (downstream side) is connected to the pipe 3 a connected to the second catalyst device 33. Connected. That is, the exhaust gas analysis sensor 4 is connected to the upstream pipe 3a and the downstream pipe 3a via pipe joints 36 and 36 provided on both sides in the direction in which the exhaust gas passes, so that the exhaust path 3 It is arranged.

  The pipe joint 36 is formed in a cylindrical shape having a through-hole 36a having a circular cross section, and a flange portion 36b is provided at one opening edge. Exhaust gas analysis sensor 4 (sensor body 40) is sandwiched between gaskets 37 and 37 at both sides of the opening end of the pair of pipe joints 36 and 36 on the side where the flange portion 36b is provided. Then, the flange portions 36b and 36b are fixed by being fastened by bolts 38 and 38.

  The through hole 36a of the pipe joint 36 is formed so that the diameter thereof is substantially the same as the diameter of the pipe 3a, and is configured not to disturb the flow of exhaust gas. Further, the gasket 37 has a hole 37a opened with substantially the same diameter as the through hole 36a and the like, and the exhaust gas analysis sensor 4 is connected to the pipe 3a in a state of being sandwiched between the pipe joints 36 and 36. The exhaust gas does not leak in the middle, and the increase in the length of the exhaust path is reduced.

  In this way, the exhaust gas analysis sensor 4 is connected to each pipe 3a of the exhaust path 3 via the pipe joints 36 and 36 described above. The exhaust gas flowing through the exhaust path 3 is sent to the sensor body 40 through the through hole 36a of one (upstream side) pipe joint 36, then passes through the exhaust gas passage hole 41 of the sensor body 40, and the other Is sent to the downstream side of the exhaust passage 3 from the through hole 36a of the pipe joint 36 (on the downstream side).

As shown in FIG. 3, the sensor main body 40 constituting the exhaust gas analysis sensor 4 is composed of a substantially cylindrical metal member having an annular shape when viewed in the exhaust gas flow direction as described above, and has a surface orthogonal to the exhaust gas flow direction. A circular exhaust gas passage hole 41 is provided at a substantially central portion.
The sensor body 40 of the present embodiment is provided with an introduction hole 40 a and a lead-out hole 40 b that communicate with the exhaust gas passage hole 41. The introduction hole 40a and the lead-out hole 40b are respectively drilled in the direction orthogonal to the exhaust gas flow direction through the center of the sensor body 40 in the plate thickness direction (depth direction in FIG. 3). In the present embodiment, as shown in FIG. 3, the introduction hole 40a and the lead-out hole 40b are substantially point symmetric with respect to the center point (axial center) of the circular shape of the exhaust gas passage hole 41 that is circular when viewed in the exhaust gas flow direction. So as to be substantially opposed to each other.

  In the sensor body 40, the irradiation unit 5 is provided on the side (inside) opposite to the side (inside) communicating with the exhaust gas passage hole 41 in the introduction hole 40a. Similarly, the light receiving part 7 is provided outside the lead-out hole 40b. In the sensor body 40, the irradiation unit 5 and the light receiving unit 7 are substantially point-symmetric with respect to the exhaust gas passage hole 41 through the introduction hole 40a and the lead-out hole 40b in the same manner as the introduction hole 40a and the lead-out hole 40b. So as to be substantially opposed to each other.

Further, in the sensor main body 40, a pair of mounting grooves 40 c and 40 c are recessed in the inner wall surface 41 a of the exhaust gas passage hole 41 toward the radially outer side of the exhaust gas passage hole 41. These mounting grooves 40c and 40c are provided at positions facing each other in the radial direction of the exhaust gas passage hole 41 as shown in FIG. A unit body (reflecting mirror unit) constituting the reflecting portion 6 is attached to each mounting groove 40c. Each reflecting portion 6 is provided such that the reflecting surfaces 60 a of the reflecting mirrors 60 face each other through the internal space of the exhaust gas passage hole 41.
Note that the sensor body 40 is provided with heat radiation fins 40d, which are hook-shaped portions extending outward in the radial direction, at both ends of the exhaust gas flow direction (see FIGS. 3 and 5). .

In the exhaust gas analysis sensor 4 having the above configuration, the laser light emitted from the irradiation unit 5 is guided into the exhaust gas passage hole 41 through the introduction hole 40a, and the laser light introduced into the exhaust gas passage hole 41 is After multiple reflection between the reflecting mirrors 60 and 60, the light is guided to the light receiving unit 7 through the lead-out hole 40b.
Hereinafter, the configuration of each part in the exhaust gas analysis sensor 4 will be described in detail.

  As shown in FIG. 3, the irradiation unit 5 includes an optical fiber 50 for infrared transmission. The optical fiber 50 is provided in a state of being positioned with respect to the sensor body 40 via the connection block 51. The optical fiber 50 is positioned by being connected to an incident light collimator 51 a provided for the connection block 51. The optical fiber 50 is provided in such a posture that its light projecting surface faces the introduction hole 40 a through the light passage hole 52 of the connection block 51. That is, the light transmission hole 52 is provided in the connection block 51 so that one end side faces the light projecting surface of the optical fiber 50 and the other end side faces the introduction hole 40a. Therefore, the light projecting surface of the optical fiber 50 faces the exhaust gas passage hole 41 through the light passage hole 52 and the introduction hole 40a. Then, the optical fiber 50 is positioned in a state where the laser beam to be irradiated is irradiated to a predetermined position with respect to the exhaust gas passage hole 41 through the light passage hole 52 and the introduction hole 40a.

  In this way, the optical fiber 50 provided in the irradiation unit 5 is connected to the controller 10 described above. The laser light emitted from the controller 10 is irradiated from the optical fiber 50 and guided into the exhaust gas passage hole 41 through the light passage hole 52 and the introduction hole 40a.

  Similarly, as shown in FIG. 3, the light receiving unit 7 includes a detector 70 that detects laser light. The detector 70 is provided in a state of being positioned with respect to the sensor main body 40 via the connection block 71. The detector 70 is positioned by being connected to a light receiving collimator 71 a provided for the connection block 71. The detector 70 is provided in such a posture that its light receiving surface faces the lead-out hole 40 b through the light passage hole 72 of the connection block 71. That is, the light passage hole 72 is provided in the connection block 71 such that one end side faces the light receiving surface of the detector 70 and the other end side faces the lead-out hole 40b. Therefore, the light receiving surface of the detector 70 is in a state of facing the exhaust gas passage hole 41 through the light passage hole 72 and the outlet hole 40b. The detector 70 is positioned in a state where the received laser beam is received at a predetermined position from the exhaust gas passage hole 41 through the outlet hole 40 b and the light passage hole 72.

  In this way, the detector 70 provided in the light receiving unit 7 is connected to the controller 10 described above. The laser light that has passed through the exhaust gas is guided to the outside of the exhaust gas passage hole 41 from the outlet hole 40 b through the light transmission hole 72 and is received by the detector 70. A light reception signal from the detector 70 is input to the controller 10.

  In addition, the structure of the irradiation part 5 and the light-receiving part 7 is not limited to this embodiment. For example, the laser beam irradiated from the irradiation unit 5 may be an ultraviolet laser beam or the like. Further, a laser diode or a photodiode may be used instead of the optical fiber 50 or the detector 70.

  As shown in FIGS. 3 to 5, the reflecting unit 6 includes a reflecting mirror 60 that forms a reflecting surface 60 a that reflects the laser light emitted from the irradiating unit 5, and a heating member for preventing condensation of the reflecting mirror 60. It has a heater 61, a buffer member 62 composed of a member that absorbs the difference in temperature deformation between the sensor body 40 and the reflecting mirror 60, and presser plates 63 and 64. A unit body is configured by accommodating the reflecting mirror 60 and the like in the casing 65 in a stacked state.

  Specifically, the casing 65 is configured as a rectangular parallelepiped casing, and has a space portion 65a for accommodating the reflecting mirror 60 and the like therein. In the space 65 a of the casing 65, the reflecting mirror 60, one presser plate 63, the heater 61, the buffer member 62, and the other presser plate 64 are housed in a stacked state. Thus, a unit body is constituted by the casing 65 and the reflecting mirror 60 accommodated in a state of being stacked in the casing 65.

  A slit 65b is formed on one side surface of the casing 65 along the longitudinal direction (the left-right direction in FIG. 4). That is, in the casing 65, the space portion 65a communicates with the external space via the slit 65b (opens to the outside by the slit 65b). As described above, the slit 65b is provided on the reflecting mirror 60 side with respect to the reflecting mirror 60 and the like housed in the state of being stacked in the space portion 65a. That is, the reflecting mirror 60 accommodated in the space portion 65a is in a state where the reflecting surface 60a is exposed to the external space so as to block the slit 65b from the inside (space portion 65a side).

  The reflection part 6 is configured by attaching the unit body as described above to the attachment groove 40 c formed in the inner wall surface 41 a of the exhaust gas passage hole 41. The unit body constituting the reflector 6 (hereinafter referred to as “reflecting mirror unit”) is such that the reflecting mirror 60 side (slit 65b side) is on the exhaust gas passage hole 41 side (inside) with respect to the mounting groove 40c. It is fixed in the fitted state. In the present embodiment, the screw member 66 is used when the reflecting mirror unit is fixed to the sensor body 40. That is, as shown in FIG. 5, the reflecting mirror unit has the casing 65 in contact with the bottom surface (outer surface) of the mounting groove 40 c and from the outside (outer peripheral surface side) of the sensor body 40 to the inside of the exhaust gas passage hole 41. The sensor body 40 is fastened and fixed by a plurality of (four in this embodiment) screw members 66 inserted in the direction. Each screw member 66 is screwed into the casing 65 through an insertion hole 40e formed in the sensor body 40.

  The reflecting mirror unit is positioned with respect to the mounting groove 40c with its casing 65 in close contact with the mounting groove 40c. In a state where the reflecting mirror unit is mounted in the mounting groove 40 c, the reflecting surface 60 a of the reflecting mirror 60 faces the exhaust gas passage hole 41. And each reflective mirror unit which comprises a pair of reflective part 6 is provided so that the mutual reflective mirrors 60 may oppose in parallel. Thereby, in a pair of reflection part 6, a mutually reflective surface 60a will be in the state which opposes in parallel. In addition, the reflecting mirror unit is in a state of being accommodated without protruding to the inner side (the axial center side of the exhaust gas passage hole 41) than the inner wall surface 41a of the exhaust gas passage hole 41 in a state of being attached to the attachment groove 40c.

  As described above, the exhaust gas analyzing sensor 4 includes a pair of reflecting mirror units (reflecting mirrors 60) disposed in the sensor body 40 and the pair of reflecting portions 6. The reflective surface 60a which opposes in parallel is provided. With this configuration, the laser light irradiated into the exhaust gas passage hole 41 from the irradiation unit 5 through the introduction hole 40a is reflected by the reflection surface 60a of the reflection unit 6 on one side (the light receiving unit 7 side, the lower side in FIG. 4). The light is reflected toward the reflecting surface 60a of the reflecting unit 6 (on the irradiation unit 5 side, the upper side in FIG. 4). The laser light is alternately reflected a predetermined number of times between the reflecting surfaces 60a and 60a facing each other, passes through the exhaust gas, and then reaches the light receiving unit 7 through the lead-out hole 40b.

  In addition, in the reflection part 6 of this embodiment, although the reflecting mirror unit which has the reflecting mirror 60 is set as the structure by which the reflecting mirror 60 grade | etc., Is accommodated in the casing 65, it is not limited to this. As a configuration for providing the reflecting mirror 60, for example, a unit body in a state where the reflecting mirror 60 is sandwiched between a pair of plate-like members is fixed to the sensor body 40 (that is, the casing 65 is omitted). Configuration).

As described above, the exhaust gas analysis sensor 4 according to the present embodiment reflects the laser light irradiated by the irradiation unit 5 toward the exhaust gas passage hole 41 by the reflection units 6 and 6 a predetermined number of times, thereby reducing the exhaust gas. After passing through the exhaust gas through a predetermined path in the passage hole 41, the light is received by the light receiving unit 7.
The exhaust gas analyzing sensor 4 according to the present embodiment covers the reflection surface 60a in the exhaust gas passage hole 41, and allows a passage hole portion 84 that allows laser light to enter and reflect on the reflection surface 60a in the predetermined path. And a cover ring 8 as an optical path limiting member.

The cover ring 8 will be described with reference to FIGS.
The cover ring 8 of the present embodiment includes a sleeve-like member formed in a cylindrical shape as a ring body 81 as a whole. A passage hole 82 through which the exhaust gas passes is formed by the inner peripheral surface of the cylindrical ring body 81.
As shown in FIGS. 3 to 5, the cover ring 8 is provided along the inner wall surface 41 a of the exhaust gas passage hole 41 in the exhaust gas analysis sensor 4. In the cover ring 8 of this embodiment, the length of the ring body 81 (length in the cylinder axis direction) is substantially the same (slightly longer) than the length of the exhaust gas passage hole 41 (length in the exhaust gas flow direction). (See FIG. 5). As a result, the cover ring 8 is in a state of covering the substantially entire inner wall surface 41 a of the exhaust gas passage hole 41 in a state of being provided in the sensor body 40.

  The passage hole 82 of the cover ring 8 is formed so that the size (diameter) thereof is substantially the same as the diameter of the through hole 36a of the pipe joint 36 and the hole 37a of the gasket 37 described above. Each member is configured so that the cover ring 8, the flange portion 36b of the pipe joint 36, and the gasket 37 are as close as possible with the pipe joint 36 and the gasket 37 attached to the exhaust gas analysis sensor 4. . With this configuration, the exhaust gas passing through the passage hole 82 of the cover ring 8 is prevented from leaking out to the flange portion 36b and the gasket 37 of the pipe joint 36 due to wraparound and the like.

  The cover ring 8 has a shielding part 83 as a part covering the reflection surface 60a. That is, the shielding part 83 is a part of the ring body 81 that covers the reflection surface 60 a in a state where the cover ring 8 is provided in the sensor body 40. Therefore, the cover ring 8 of the present embodiment corresponds to the reflection surface (hereinafter also referred to as “lower reflection surface”) 60a of the reflection unit 6 on one side (the light receiving unit 7 side, the lower side in FIG. 4) (lower). A reflection surface (hereinafter referred to as “lower shielding portion”) 83 and a reflection surface (hereinafter referred to as “upper side reflection surface 60a”). A shielding portion (hereinafter also referred to as “upper shielding portion”) 83 corresponding to 60a (covering the upper reflecting surface 60a).

As described above, the shielding portion 83 is a portion that covers the reflective surface 60a of the ring main body 81. With the cover ring 8 provided on the sensor main body 40, the shield main body 83 is provided with respect to the exhaust gas passage hole 41 side of the reflective surface 60a. It is the part that includes the projected part. Therefore, in the ring body 81, the lower shielding portion 83 is a portion that covers the lower reflecting surface 60a in a state where the cover ring 8 is provided in the sensor body 40 (indicated by reference numeral D1 in FIGS. 6 and 7). The upper shielding portion 83 is a portion that covers the upper reflecting surface 60a in a state where the cover ring 8 is provided in the sensor body 40 (see the range indicated by reference numeral D2 in FIGS. 6 and 7).
Thus, the cover ring 8 covers the reflection surface 60 a with the shielding portion 83 in the ring main body 81 in a state of being provided in the sensor main body 40.

Moreover, the cover ring 8 has the passage hole part 84 which accept | permits the incidence | injection and reflection with respect to the reflective surface 60a in the predetermined path | route in the waste gas passage hole 41 of the laser beam as mentioned above.
The passage hole portion 84 is an opening portion that penetrates the cylindrical wall portion of the cylindrical ring body 81 and serves as an optical path hole through which the laser light passes. A predetermined number of passage holes 84 are provided at predetermined positions in the shield 83 in the ring body 81. The position and the number of the passage holes 84 in the ring body 81 are determined by a predetermined path in the exhaust gas passage hole 41 for laser light.

  In the exhaust gas analyzing sensor 4 of the present embodiment, the predetermined path in the exhaust gas passage hole 41 of the laser light is reflected eight times between the reflecting surfaces 60a and 60a facing each other as shown by a one-dot chain line in FIG. It becomes a path that follows the reflection path that passes. In other words, the predetermined path in the present embodiment is such that the laser light irradiated into the exhaust gas passage hole 41 through the introduction hole 40a undergoes a total of eight reflections between the upper and lower reflection surfaces 60a and 60a. In this way, the exhaust gas passage 41 is led out of the exhaust gas passage hole 41 through the outlet hole 40b. Furthermore, in the predetermined path in the present embodiment, the laser beam irradiated into the exhaust gas passage hole 41 from the irradiation unit 5 through the introduction hole 40a is first reflected on the lower reflection surface 60a. After the first reflection, the reflection is alternately performed on the upper and lower reflection surfaces 60a and 60a, and after the eighth reflection is performed on the upper reflection surface 60a, the light is received by the light receiving unit 7 through the lead-out hole 40b. Led.

In such a predetermined path of the laser light in the exhaust gas passage hole 41, the passage hole portion 84 allows the incidence and reflection of the laser light on the reflection surface 60a. That is, the passage hole portion 84 is provided so as to allow passage of the laser light that follows the predetermined path in a state where the cover ring 8 is provided in the sensor body 40.
In addition, as shown in FIG. 4, in the present embodiment, the passage hole portion 84 allows the incident light and the reflected light to pass through the reflecting surface 60a at one reflection spot of the laser light with respect to the reflecting surface 60a. Therefore, in the cover ring 8 of the present embodiment, four passage hole portions 84 are provided in each of the upper shielding portion 83 and the lower shielding portion 83, and a total of eight passage hole portions 84 are provided.
In the cover ring 8, the ring body 81 has an introduction hole portion 85 a that allows laser light to enter the exhaust gas passage hole 41 through the introduction hole 40 a, and an exhaust gas passage hole 41 that emits laser light toward the outlet hole 40 b. A lead-out hole 85b that allows injection from the inside is provided.

  The size (diameter) of the passage hole portion 84 is set as follows. That is, in the exhaust gas analysis sensor 4, the laser light follows the predetermined path as described above in the exhaust gas passage hole 41. The predetermined path for the laser beam is realized by reflecting the laser beam a predetermined number of times (hereinafter referred to as “specified number”) by the reflecting surface 60a. Therefore, the size of the passage hole portion 84 is set to a size that the laser beam is not received by the light receiving portion 7 at a number other than the prescribed number of times. In other words, laser light whose number of reflections between the reflection surfaces 60a and 60a is different from the specified number of times is reflected by the reflection surface 60a (incident and reflected on the reflection surface 60a) by the shielding portion 83 of the cover ring 8. The size of the passage hole portion 84 is set so as to be blocked and the progress in the exhaust gas passage hole 41 is blocked in the middle.

  Specifically, as in this embodiment, in the exhaust gas analysis sensor 4 in which the prescribed number of reflections of laser light is 8, the incident angle of the laser light emitted from the irradiation unit 5 with respect to the exhaust gas passage hole 41 ( The laser beam that follows the path guided to the light receiving unit 7 after being reflected six times or ten times between the reflecting surfaces 60a and 60a due to the deviation of the optical axis) 83 prevents the reflection by the reflecting surface 60a. Actually, the size (diameter) of the passage hole portion 84 is, for example, about several millimeters.

  As described above, the cover ring 8 covers the reflection surfaces 60a and 60a by the shielding portion 83, and allows the incidence and reflection of the laser light that has undergone a predetermined number of reflections by the passage hole portion 84 to the reflection surfaces 60a and 60a. Thus, a path of laser light that follows a predetermined path is secured. In the cover ring 8, at least the inner peripheral surface of the ring main body 81 is a surface whose reflectance is sufficiently lower than the reflectance of the reflecting surface 60a.

  In the exhaust gas analysis sensor 4 provided with the cover ring 8 having the above-described configuration, first, laser light that follows a predetermined path is irradiated from the irradiation unit 5 into the exhaust gas passage hole 41 through the introduction hole 40a. Then, the light passes through the passage hole 84 in the lower shielding part 83 via the introduction hole 85a of the cover ring 8 and is reflected by the lower reflection surface 60a. The laser light reflected by the lower reflection surface 60 a passes through the exhaust gas passage hole 41 through the passage hole 84 in the lower shielding part 83 and passes through the passage hole 84 in the upper shielding part 83. Reflected by the upper reflecting surface 60a. Thereafter, the laser beam that has repeatedly reflected between the upper and lower reflecting surfaces 60a and 60a while passing through the passage hole 84 and has undergone the prescribed number of reflections is guided to the lead-out hole 40b through the lead-out hole 85b of the cover ring 8. The light receiving unit 7 receives the light.

  As described above, in the exhaust gas analysis sensor 4, the cover ring 8 is provided, so that the path of the laser light and the number of reflections are defined (restricted) in the configuration in which the laser light is multiply reflected in the exhaust gas to be analyzed. It is possible to guarantee the quantitativeness of the measurement value and to omit the work for confirming the number of reflections of the laser beam.

That is, the cover ring 8 allows the progress of only the laser light that follows a predetermined path in the exhaust gas passage hole 41 by the shielding portion 83 and the passage hole portion 84. In other words, the laser light that has undergone a number of reflections different from the specified number due to the deviation of the optical axis of the laser light for some reason is blocked by the cover ring 8 and is not received by the light receiving unit 7. (Measurement impossible state). Thus, the cover ring 8 can define (limit) the path of the laser light and the number of reflections.
As a result, only the laser beam that has passed the specified number of reflections can be received, so that the optical path length (measurement length) of the laser beam can be kept constant, and the quantitativeness of the measured value can be guaranteed. Further, as long as the laser beam is received by the light receiving unit 7, the number of reflections of the laser beam satisfies the specified number of times. Therefore, in order to confirm the number of reflections of the laser beam, from the exhaust path of the exhaust gas analyzing sensor 4 It is possible to omit troublesome work such as removal of the. That is, since the number of times of reflection of the laser beam is guaranteed by receiving the laser beam at the light receiving unit 7, whether or not the number of times of reflection of the laser beam is a specified number in a state where the exhaust gas analysis sensor 4 is attached to the exhaust path. This makes it possible to confirm the number of reflections of laser light.

  In addition, the predetermined | prescribed frequency | count about the predetermined path | route in the waste gas passage hole 41 of a laser beam, ie, reflection of a laser beam, is not limited to this embodiment. The number, position, and the like of the through holes 84 provided in the cover ring 8 are determined so as to correspond to a predetermined path (a prescribed number of reflections) of the laser light.

  In the present embodiment, the passage hole portion 84 in the cover ring 8 allows the incident light and the reflected light to pass through the reflection surface 60a at one reflection spot of the laser light with respect to the reflection surface 60a (see FIG. 4). However, the present invention is not limited to this. That is, the passage hole portion 84 allows the incident on the reflecting surface 60a (allows the incident light to pass) at one reflection spot of the laser beam on the reflecting surface 60a, and allows the reflection from the reflecting surface 60a (the reflection). The configuration in which the light is allowed to pass through may be provided separately (independently). In such a configuration, when the prescribed number of times of reflection of the laser beam is 8 as in the present embodiment, eight through hole portions 84 are provided in each of the upper shielding portion 83 and the lower shielding portion 83. A total of 16 pieces are provided in the cover ring 8.

  Further, in the present embodiment, the cover ring 8 as the optical path limiting member is configured to include the cylindrical ring main body 81, but is not limited thereto. As the optical path forming member according to the present invention, for example, members having portions corresponding to the shielding portion 83 and the passage hole portion 84 provided in the cover ring 8 of the present embodiment are provided on the upper and lower reflecting surfaces 60a and 60a. Alternatively, a configuration provided as a separate member may be used.

  The cover ring 8 is preferably a tubular member that follows the shape of the exhaust gas passage hole 41, and has a gap with respect to the inner wall surface 41 a that is the wall surface that forms the exhaust gas passage hole 41 with respect to the exhaust gas passage hole 41. It is provided in a separated state.

In the present embodiment, the cover ring 8 is configured as a tubular member that conforms to the shape of the exhaust gas passage hole 41 by including, as the ring main body 81, a sleeve-like member formed in a cylindrical shape as a whole as described above. Yes.
In the present embodiment, the exhaust gas passage hole 41 is formed as a cylindrical hole. That is, the inner wall surface 41a that forms the exhaust gas passage hole 41 is a wall surface that forms a cylindrical space. With respect to the exhaust gas passage hole 41 having such a shape, the cover ring 8 is formed in a cylindrical shape as a whole (its ring body 81). That is, the outer shape of the cylindrical cover ring 8 is a shape that follows the shape of the exhaust gas passage hole 41 that is a cylindrical hole. Thus, the cover ring 8 is configured as a tubular member that follows the shape of the exhaust gas passage hole 41.

Then, the cover ring 8 having the shape as described above is provided with respect to the exhaust gas passage hole 41 in a state in which a gap is separated from the inner wall surface 41a forming the exhaust gas passage hole 41.
That is, the cover ring 8 provided in the exhaust gas passage hole 41 has an outer diameter provided between the inner wall surface 41 a of the exhaust gas passage hole 41 and the outer peripheral surface 81 a of the ring body 81 in a state of being provided in the sensor body 40. The gap is set to have a predetermined size (width). As a result, the cover ring 8 is held in a state having a gap with the inner wall surface 41 a that forms the exhaust gas passage hole 41.

A configuration for fixing and positioning the cover ring 8 with respect to the sensor main body 40 (in the exhaust gas passage hole 41) will be described.
For fixing the cover ring 8 to the sensor body 40, a fixing bolt 87 as a fixing jig for the cover ring 8 is used. For positioning the cover ring 8 in the exhaust gas passage hole 41, spacer pins 88 as a positioning jig for the cover ring 8 are used. However, substantially, the fixing and positioning action for the cover ring 8 can be obtained by both the fixing bolt 87 and the spacer pin 88.

  As shown in FIG. 4, the fixing bolt 87 is provided in a state in which one end portion (tip portion) projects partially into the exhaust gas passage hole 41 through a through hole 40 f provided in the sensor body 40. The fixing bolt 87 has a screw portion 87a at least at its tip. On the other hand, in the cover ring 8, a screw hole 86 into which the screw portion 87 a of the fixing bolt 87 is screwed is provided in the ring main body 81. That is, with respect to the cover ring 8 provided in the exhaust gas passage hole 41, the fixing bolt 87 is screwed into the screw hole 86 from the outer peripheral side (from the outer peripheral surface 81a side), whereby the cover ring 8 is Fixed to the main body 40.

The through hole 40f into which the fixing bolt 87 is inserted is formed in the sensor main body 40 along the radial direction of the sensor main body 40 (the radial direction of the exhaust gas passage hole 41) from the outer peripheral surface side to the inner peripheral surface side ( It is provided so as to penetrate to the inner wall surface 41a side). Further, the through hole 40f and the screw hole 86 corresponding to the through hole 40f are shifted from the center position in the width direction (axial direction) of the exhaust gas passage hole 41 so as not to block the optical path of the laser beam. Provided (see FIG. 5).
In the present embodiment, as shown in FIG. 4, the through holes 40 f are provided at two positions at opposite positions on both sides of the exhaust gas passage hole 41 (both sides in the left-right direction in FIG. 4). Therefore, in the present embodiment, two fixing bolts 87 are used for fixing the cover ring 8, and these fixing bolts 87 are in the radial direction of the exhaust gas passage hole 41 and toward the axial center of the exhaust gas passage hole 41. And screwed into the cover ring 8 in a state of facing each other. The operation of the fixing bolt 87 is performed through the opening of the through hole 40f on the outer peripheral surface side of the sensor body 40.

  The fixing bolt 87 screwed into the cover ring 8 may be a pin-shaped member (hereinafter referred to as “fixing pin”) that fits into the cover ring 8. In this case, in the cover ring 8, a groove portion into which the fixing pin is fitted is provided at a predetermined position on the outer peripheral surface 81 a of the ring body 81. Then, the tip of the fixing pin inserted into the through hole 40f is fitted into the groove of the cover ring 8 provided in the exhaust gas passage hole 41, so that the cover ring 8 is attached to the sensor body. 40 is fixed.

As shown in FIG. 4, the spacer pin 88 is provided in a state in which one end portion (tip portion) projects partially into the exhaust gas passage hole 41 through a screw hole 40 g provided in the sensor body 40. The spacer pin 88 is screwed into the screw hole 40g. That is, a thread portion is formed on the outer peripheral surface of the spacer pin 88 and the inner peripheral surface of the screw hole 40g, and the spacer pin 88 is screwed into the screw hole 40g. As the spacer pin 88, a pin-shaped (bar-shaped) member whose outer peripheral surface is threaded such as a screw or a set screw is used.
The spacer pin 88 is formed on the outer peripheral surface 81a of the ring main body 81 with respect to the cover ring 8 in a state where the tip portion protruding into the exhaust gas passage hole 41 (from the inner wall surface 41a) is provided in the exhaust gas passage hole 41. Abut.

The screw hole 40g into which the spacer pin 88 is screwed is provided in the sensor body 40 along the radial direction of the sensor body 40 (the radial direction of the exhaust gas passage hole 41).
In the present embodiment, as shown in FIG. 4, the screw holes 40 g are provided in a total of four locations, two sets of opposing positions on both sides of the exhaust gas passage hole 41. Therefore, in the present embodiment, four spacer pins 88 are used for positioning the cover ring 8, and these spacer pins 88 are in the radial direction of the exhaust gas passage hole 41 and toward the axial center of the exhaust gas passage hole 41. Thus, each pair of spacer pins 88 abut against the cover ring 8 with the spacer pins 88 facing each other. The screw hole 40g extends so as to open to the outer peripheral surface side of the sensor body 40. Thereby, the operation of the spacer pin 88, that is, the adjustment of the protrusion length of the spacer pin 88 with respect to the exhaust gas passage hole 41 is performed through the opening on the outer peripheral surface side of the sensor body 40 of the screw hole 40g.

  Thus, the cover ring 8 is positioned in the exhaust gas passage hole 41 by the spacer pin 88. That is, the spacer pin 88 is positioned in a predetermined state in the exhaust gas passage hole 41 by adjusting the length of the spacer pin 88 protruding from the exhaust gas passage hole 41 (from the inner wall surface 41a). . Specifically, the cover ring 8 is arranged so that the distance between the outer peripheral surface 81a of the ring body 81 and the inner wall surface 41a of the exhaust gas passage hole 41 is uniform over the entire circumferential direction (center with respect to the exhaust gas passage hole 41). Positioned in the radial direction).

  As a configuration for positioning the cover ring 8 by the spacer pin 88, the spacer pin 88 may be screwed into the cover ring 8 side. In this case, a screw hole into which the spacer pin 88 is screwed is provided at a predetermined position in the ring main body 81 of the cover ring 8. The one end side of the spacer pin 88 is screwed into the screw hole, and the other end side of the spacer pin 88 is the inner wall surface of the exhaust gas passage hole 41 in a state where the cover ring 8 is provided in the exhaust gas passage hole 41. It becomes the structure which contacts 41a. In such a configuration, the cover ring 8 is positioned in a predetermined state in the exhaust gas passage hole 41 by adjusting the protruding length of the spacer pin 88 from the outer peripheral surface 81 a of the ring body 81.

As described above, the fixing bolt 87 and the spacer pin 88 are used to fix and position the cover ring 8 with respect to the sensor body 40. Thereby, the cover ring 8 is held with respect to the sensor body 40 in a state in which the relative position cannot be changed in each of the circumferential direction and the axial direction (thrust direction).
In the state where the cover ring 8 is provided with respect to the sensor main body 40, a gap having a predetermined size (width) exists between the outer peripheral surface 81 a of the ring main body 81 and the inner wall surface 41 a of the exhaust gas passage hole 41. To do.

  With the configuration as described above, the cover ring 8, which is a tubular member that follows the shape of the exhaust gas passage hole 41, is provided with respect to the exhaust gas passage hole 41 in a state where a gap is separated from the inner wall surface 41 a of the exhaust gas passage hole 41. As a result, the following effects can be obtained.

That is, in the configuration in which the cover ring 8 is provided in the exhaust gas passage hole 41 as described above, the high-temperature exhaust gas passes through the passage hole 82 of the ring body 81 in the cover ring 8. Further, the cover ring 8 covers substantially the entire inner wall surface 41 a of the exhaust gas passage hole 41 and is in a state in which a gap is separated from the exhaust gas passage hole 41. For this reason, the exhaust gas passing through the exhaust gas passage hole 41 can be isolated from the inner wall surface 41a and the reflecting surface 60a, and the sensor body 40 and the reflecting mirror 60 are directly exposed to the exhaust gas passing through the exhaust gas passage hole 41. Can be prevented. Thereby, thermal radiation and heat transfer from the high-temperature exhaust gas to the sensor body 40 and the reflecting mirror 60 can be reduced.
Further, since the cover ring 8 directly touches the high-temperature exhaust gas passing through the passage hole 82 of the ring body 81, the cover ring 8 is greatly influenced thermally from the exhaust gas. Therefore, as described above, the cover ring 8 is provided in a state of being spaced from the exhaust gas passage hole 41, so that the cover ring 8 does not directly touch the sensor body 40. The heat transfer to the sensor main body 40 via can be reduced.
In the present embodiment, the cover ring 8 is in contact with the sensor body 40 only through the fixing bolt 87 and the spacer pin 88. Also from this point, the contact area of the cover ring 8 with respect to the sensor body 40 is reduced, and heat input from the exhaust gas to the sensor body 40 via the cover ring 8 can be suppressed.

As described above, the heat influence of the exhaust gas passing through the exhaust gas passage hole 41 on the sensor body 40 and the reflecting mirror 60 can be reduced, so that in the exhaust gas analysis sensor 4, the irradiation unit 5, the reflection unit 6, and the light receiving unit 7. Can reduce the thermal effects of high-temperature exhaust gas on various optical devices, etc., and prevent malfunctions due to the thermal effects (for example, deviation of the optical axis of the laser beam, thermal deformation of members, loose fixing between members, etc.) can do. As a result, the measurement accuracy in the exhaust gas analysis sensor 4 can be improved.
For this reason, as a material which comprises the cover ring 8, materials with low heat conductivity, such as a ceramic, are used, for example.

  Further, the cover ring 8 is greatly affected mechanically by vibration and the like due to the high temperature exhaust gas passing through the passage hole 82 of the ring body 81 in addition to the thermal influence. In this respect, the cover ring 8 in the present embodiment is reliably fixed and positioned with respect to the sensor main body 40 (exhaust gas passage hole 41) by the fixing bolt 87 and the spacer pin 88. Thereby, while being able to improve the earthquake resistance of the cover ring 8 with respect to high temperature waste gas, the influence of a thermal deformation can be reduced. As a result, the stability of the restriction of the laser beam path by the cover ring 8 can be ensured without the cover ring 8 being displaced.

  The configuration for fixing and positioning the cover ring 8 with respect to the sensor main body 40 (within the exhaust gas passage hole 41) is not limited to the present embodiment. That is, the position and number of fixing bolts 87 and spacer pins 88 provided with respect to the cover ring 8, or the configuration of the jig itself used for fixing and positioning the cover ring 8 is not limited to this embodiment. .

As described above, in the exhaust gas analysis sensor 4, the laser light path (optical axis position) is limited by the cover ring 8 having the shielding portion 83 and the passage hole portion 84. For this reason, an accurate and simple adjustment mechanism is required for the optical axis of the laser beam.
Therefore, in the exhaust gas analysis sensor 4 of the present embodiment, the irradiation unit 5 and the light receiving unit 7 have the following configuration.

That is, the irradiation unit 5 and the light receiving unit 7 are respectively an alignment block 91 as a first optical path forming member, a collimator block 92 as a second optical path forming member, an adjusting bolt 93 as an adjusting member, and an elastic member. And an adjusting elastic body 94 as a member. The configuration including these members (alignment block 91, collimator block 92, adjustment bolt 93, and adjustment elastic body 94) is configured as a connection block 51 in the irradiation unit 5 and a connection block 71 in the light receiving unit 7, respectively. .
In addition, since the irradiation part 5 and the light-receiving part 7 have substantially the same configuration and are provided in a state of being substantially point-symmetric with respect to the axial center of the exhaust gas passage hole 41 as described above (see FIG. 3), the following Now, the configuration of the irradiation unit 5 will be specifically described with reference to FIGS. 8 and 9.

The alignment block 91 is fixed to the sensor body 40 and forms an inner light passage hole 91 a as a first light passage communicating with the exhaust gas passage hole 41.
The alignment block 91 is a substantially cylindrical member as a whole, and has an inner light transmission hole 91a in the axial center portion (cylinder shaft portion). The inner light passage hole 91 a is a straight hole and penetrates the substantially cylindrical alignment block 91. That is, the inner light passage hole 91a opens on both end surfaces of the substantially cylindrical alignment block 91.

  The alignment block 91 is fixed to the sensor main body 40 in a state where the inner light passage hole 91a communicates with an introduction hole 40a formed in the sensor main body 40 (the lead-out hole 40b in the light receiving unit 7 is the same hereinafter). The That is, in a state where the alignment block 91 is fixed to the sensor body 40, a linear hole is formed by the inner light passage hole 91a and the introduction hole 40a. The introduction hole 40 a communicates with the exhaust gas passage hole 41. As described above, the inner light passage hole 91a of the alignment block 91 communicates with the exhaust gas passage hole 41 through the introduction hole 40a.

The alignment block 91 is fixed to the sensor body 40 in a state in which the alignment block 91 is fitted in an attachment recess 40 h formed on the outer peripheral surface portion of the sensor body 40. When the alignment block 91 is fixed to the sensor body 40, a bolt 95 is used. The bolt 95 passes through a bolt insertion hole 91 b that penetrates in the cylinder axis direction in the alignment block 91 and is screwed into a screw hole 40 i formed in the sensor main body 40, so that the alignment block 91 is attached to the sensor main body 40. Fix it. The bolt 95 is operated from the opening side of the bolt insertion hole 91b on the outer end face 91c side in the alignment block 91. The outer end surface 91c of the substantially cylindrical alignment block 91 is a circular surface.
Although one bolt 95 is shown in FIG. 8, a plurality of bolts 95 are appropriately used for fixing the alignment block 91 to the sensor body 40. Further, the method for fixing the alignment block 91 to the sensor body 40 is not particularly limited to this embodiment. For example, the alignment block 91 may be fixed to the sensor body 40 by welding or the like.

  The collimator block 92 is provided with an adjustment bolt 93 so that the posture with respect to the alignment block 91 can be adjusted. The collimator block 92 holds the light incident collimator 51a to which the optical fiber 50 is connected as described above. That is, the collimator block 92 is adjusted in the irradiation direction of the laser beam to the exhaust gas passage hole 41 in the irradiation unit 5 by adjusting the posture with respect to the alignment block 91. Further, the collimator block 92 forms an outer light passage hole 92a as a second light passage communicating with the inner light passage hole 91a.

  The collimator block 92 is a substantially disk-shaped member having substantially the same diameter as the alignment block 91 as a whole, and has an outer light passage hole 92a at the axial center portion thereof. Further, the collimator block 92 has an abutting convex portion 92b that contacts the alignment block 91 on an inner side surface 92c that is a plate surface on one side thereof. The inner side surface 92c of the collimator block 92 having a substantially disc shape is a circular surface. The contact convex portion 92 b is a portion having a substantially columnar outer shape provided at a substantially central portion of the inner side surface 92 c of the collimator block 92. The outer light passage hole 92 a is a straight hole and penetrates the collimator block 92. That is, the outer light transmission hole 92a penetrates the part including the contact convex portion 92b in the axial direction in the collimator block 92 and opens to the end surfaces on both sides. The light incident collimator 51a is held at the outer end (outside of the inner side surface 92c) of the outer light passage hole 92a.

  The collimator block 92 is provided with respect to the alignment block 91 such that the outer light passage hole 92 a communicates with the inner light passage hole 91 a formed by the alignment block 91. That is, in a state where the collimator block 92 is provided with respect to the alignment block 91, a linear hole is formed by the outer light passage hole 92a and the inner light passage hole 91a. Therefore, the outer light passage hole 92a and the inner light passage hole 91a make a light passage hole 52 (also the light passage hole 72, the same applies hereinafter) in the connection block 51 (the connection block 71 for the light receiving unit 7). Composed.

  The collimator block 92 is provided with respect to the alignment block 91 in a state where the tip end surface 92 d of the abutment convex portion 92 b is in contact with the outer end surface 91 c of the alignment block 91. That is, in the collimator block 92, the front end surface 92d of the abutting convex portion 92b serves as a support surface for the alignment block 91. Accordingly, the collimator block 92 is provided in a state in which the inner side surface 92c thereof is in partial contact with the outer end surface 91c of the alignment block 91 via the contact convex portion 92b. Due to such partial contact of the collimator block 92 with the alignment block 91 via the contact protrusion 92b, the contact protrusion 92b is formed between the inner surface 92c of the collimator block 92 and the outer end surface 91c of the alignment block 91. A gap corresponding to the protruding length (hereinafter referred to as “adjustment gap”) is formed. Using this adjustment gap, the posture (angle) of the collimator block 92 with respect to the alignment block 91 is changed.

  That is, the collimator block 92 supported by the alignment block 91 via the contact protrusion 92b is in a state where the contact protrusion 92b is in contact with the outer end surface 91c of the alignment block 91 via the adjustment gap. It is tilted with respect to the alignment block 91. As described above, the collimator block 92 is tilted with respect to the alignment block 91, whereby the posture of the collimator block 92 with respect to the alignment block 91 (hereinafter also simply referred to as “posture”) is changed. As the attitude of the collimator block 92 changes, the incident light collimator 51a held by the collimator block 92 is displaced, and the angle (optical axis position) of the light projecting surface of the optical fiber 50 changes. That is, the irradiation direction of the laser beam by the irradiation unit 5 changes as the posture of the collimator block 92 changes. Therefore, the collimator block 92 is a member that adjusts the irradiation direction of the laser beam with respect to the exhaust gas passage hole 41 in the irradiation unit 5 by adjusting the posture with respect to the alignment block 91.

In the light receiving unit 7, the light receiving direction with respect to the laser light from the exhaust gas passage hole 41 is adjusted by adjusting the posture of the collimator block 92 with respect to the alignment block 91.
That is, in the light receiving unit 7, the light receiving collimator 71 a to which the detector 70 is connected is held in the collimator block 92 in the same manner as the light incident collimator 51 a in the irradiation unit 5. As the posture of the collimator block 92 changes, the light receiving collimator 71a held by the collimator block 92 is displaced, and the angle of the light receiving surface of the detector 70 changes. In other words, the light receiving direction of the laser light by the light receiving unit 7 is changed by changing the posture of the collimator block 92.
Such adjustment of the posture of the collimator block 92, that is, adjustment of the irradiation direction and the light receiving direction of the laser light is performed by operating the adjustment bolt 93.

The adjustment bolt 93 is a member for engaging the alignment block 91 and the collimator block 92 and adjusting the posture of the collimator block 92 with respect to the alignment block 91.
The adjustment bolt 93 is arranged in a direction parallel to the direction of penetration of the light passage hole 52 in the connection block 51, penetrates the collimator block 92 and is screwed into the alignment block 91.

  That is, the collimator block 92 has a screw hole 92e penetrating in a direction parallel to the outer light passage hole 92a. The adjustment bolt 93 passes through the screw hole 92e of the collimator block 92 in a screwed state. Further, the alignment block 91 has a screw hole 91e provided in a direction parallel to the inner light passage hole 91a and opened to the outer end face 91c. An adjustment bolt 93 that passes through the screw hole 92e of the collimator block 92 is screwed into the screw hole 91e of the alignment block 91. That is, the screw hole 91 e of the alignment block 91 and the screw hole 92 e of the collimator block 92 are provided at corresponding positions in the penetration direction of the light passage hole 52 in the connection block 51. Therefore, the adjustment bolt 93 is screwed into the screw hole 92e from the outer end face side of the collimator block 92 that is in contact with the alignment block 91 via the contact protrusion 92b, and is also passed through the adjustment space. Then, it is screwed into the screw hole 91e of the alignment block 91.

As described above, the adjustment bolt 93 is screwed into the alignment block 91 while penetrating the collimator block 92, thereby engaging the alignment block 91 with the collimator block 92.
Then, the posture of the collimator block 92 changes as the tightening degree (tightening torque) of the adjustment bolt 93 changes. Therefore, the posture of the collimator block 92 is adjusted by adjusting the tightening degree of the adjustment bolt 93. That is, by adjusting the tightening degree of the adjusting bolt 93, the irradiation direction of the laser beam to the exhaust gas passage hole 41 is adjusted in the case of the irradiation unit 5, and in the case of the light receiving unit 7, the direction from the exhaust gas passage hole 41 is adjusted. The light receiving direction with respect to the laser light is adjusted.
In the present embodiment, three adjustment bolts 93 are provided at substantially equal intervals in the circumferential direction of the light passage hole 52 of the connection block 51, as shown in FIG. FIG. 9 is a view taken in the direction of arrow A in FIG.

  The adjustment elastic body 94 is interposed between the alignment block 91 and the collimator block 92 that are engaged with each other by the adjustment bolt 93 as described above, and maintains the posture of the collimator block 92 with respect to the alignment block 91 by elasticity. .

The adjustment elastic body 94 is made of an elastic material such as rubber, and is a substantially disk-shaped member having substantially the same diameter as the alignment block 91 and the collimator block 92 as a whole. The adjustment elastic body 94 is sandwiched between the outer end surface 91c of the alignment block 91 and the inner side surface 92c of the collimator block 92 (pressed state), and between the alignment block 91 and the collimator block 92. Intervened. That is, the adjustment elastic body 94 is in a state of filling the adjustment gap between the outer end surface 91 c of the alignment block 91 and the inner side surface 92 c of the collimator block 92. Therefore, the adjustment elastic body 94 includes a through hole 94a in which the abutment convex portion 92b of the collimator block 92 that contacts the outer end surface 91c of the alignment block 91 is penetrated, and a bolt in which the adjustment bolt 93 is penetrated. And a hole 94b.
As the adjustment elastic body 94, for example, a rubber plate, an O-ring, a C-ring, or the like is used.

Thus, the posture of the collimator block 92 adjusted by the adjustment bolt 93 with respect to the alignment block 91 is maintained by the adjustment elastic body 94 interposed between the alignment block 91 and the collimator block 92.
That is, the adjustment elastic body 94 is elastically engaged between the alignment block 91 and the collimator block 92 by the adjustment bolt 93 and between the outer end face 91c and the inner side face 92c when the adjustment bolt 93 is tightened. A reaction force against a partial action (a part where the collimator block 92 is inclined with respect to the alignment block 91) is applied. Accordingly, a balance is maintained between the alignment block 91 and the collimator block 92 with respect to the engagement state and proximity action by the adjusting bolt 93, and the posture of the collimator block 92 with respect to the alignment block 91 is maintained.

  The adjustment elastic body 94 is constructed between the outer end face 91c of the alignment block 91 and the inner side face 92c of the collimator block 92, and the adjustment bolt between the alignment block 91 and the collimator block 92 as described above. The spring-like elastic member etc. which make the reaction force with respect to the engagement state by 93 and a proximity | contact action may be sufficient.

Here, in the present embodiment, as described above, the three adjustment bolts 93 provided at substantially equal intervals in the circumferential direction of the light transmission hole 52 of the connection block 51 are arranged as follows.
That is, as shown in FIG. 9, one of the three adjustment bolts 93 (93a) is supported with respect to a support portion (axial center portion) for the alignment block 91 by the abutting convex portion 92b of the collimator block 92. The sensor body 40 is provided on one side (right side in FIG. 9) in the circumferential direction. In other words, the adjustment bolt 93a is provided at a substantially central portion in the connection block 51 in a direction parallel to the axial direction of the sensor body 40 (vertical direction in FIG. 9). By operating the adjustment bolt 93 a provided at this position, the inclination of the sensor body 40 in the circumferential direction with respect to the alignment block 91 is adjusted with respect to the posture of the collimator block 92.

The other two of the three adjustment bolts 93 (93b, 93c) are arranged on both sides of the connection block 51 in the direction parallel to the axial direction of the sensor body 40 (vertical direction in FIG. 9). . In other words, these two adjustment bolts 93b and 93c are supported with respect to a support portion (axial center portion) for the alignment block 91 by the abutting convex portion 92b of the collimator block 92 along a direction parallel to the axial direction of the sensor body 40. Arranged on both sides. By operating the adjustment bolts 93b and 93c provided at such positions, the inclination of the sensor body 40 in the axial direction with respect to the alignment block 91 is adjusted with respect to the posture of the collimator block 92.
In the present embodiment, each of the irradiation unit 5 and the light receiving unit 7 includes three adjustment bolts 93, but the number of the adjustment bolts 93 is not limited.

  In the irradiation unit 5 and the light receiving unit 7 of the present embodiment having the above-described configuration, the three adjustment bolts 93 are operated, and the tightening degree thereof is adjusted, whereby the contact convex portion 92b is moved to the alignment block 91. The posture of the collimator block 92 that serves as a support for the is adjusted. Thereby, in the case of the irradiation part 5, the irradiation direction of the laser beam with respect to the exhaust gas passage hole 41 is adjusted, and in the case of the light receiving part 7, the light reception direction with respect to the laser beam from the exhaust gas passage hole 41 is adjusted.

  Thus, by configuring the irradiation unit 5 and the light receiving unit 7, accurate and simple adjustment (fine adjustment) of the optical axis of the laser beam is performed in a state where the exhaust gas analysis sensor 4 is attached to the exhaust path. It becomes possible. Thereby, in the configuration in which the cover ring 8 is provided, it is possible to satisfactorily cope with the restriction of the laser light path (optical axis position) by the cover ring 8.

  In the irradiation unit 5 and the light receiving unit 7, the adjustment elastic body 94 interposed between the alignment block 91 and the collimator block 92 is made of a material having a lower thermal conductivity than the material forming the alignment block 91. It is preferred that

  That is, when the alignment block 91 is made of a metal such as titanium, for example, the adjustment elastic body 94 is made of a rubber such as an O-ring, for example. Accordingly, the adjustment elastic body 94 is a member having a low thermal conductivity with respect to the alignment block 91.

  As described above, a member having a lower thermal conductivity than the alignment block 91 is used as the adjustment elastic body 94 interposed between the alignment block 91 and the collimator block 92, so that exhaust gas that becomes high temperature passes. Heat input due to heat conduction from the alignment block 91 close to the exhaust gas passage hole 41 to the collimator block 92 can be suppressed. As a result, it is possible to reduce the thermal effect on various optical components attached to the collimator block 92 such as the optical fiber 50 in the irradiating unit 5 and the detector 70 in the light receiving unit 7. Can be prevented.

The side view which shows the state which mounted the exhaust gas analyzer provided with the sensor for exhaust gas analysis which concerns on one Embodiment of this invention in the vehicle. The figure which shows the attachment structure with respect to the pipe joint of the sensor for exhaust gas analysis. (A) is an exploded perspective view. (B) is a side view. Front sectional drawing which shows the sensor for exhaust gas analysis. FIG. 4 is a partially enlarged view around an exhaust gas passage hole in FIG. 3. Side surface sectional drawing which shows the sensor for exhaust gas analysis. The top view which shows a cover ring. Similarly front view. The elements on larger scale of the irradiation part in FIG. FIG.

4 Sensor for exhaust gas analysis 5 Irradiation part 6 Reflection part 7 Light-receiving part 8 Covering (optical path limiting member)
40 Sensor body 41 Exhaust gas passage hole 41a Inner wall surface (wall surface)
84 Passing hole 91 Alignment block (first optical path forming member)
91a Inner light passage hole (first light passage)
92 Collimator block (second optical path forming member)
92a Outer light passage hole (second light passage)
93 Adjustment bolt (Adjustment member)
94 Elastic body for adjustment (elastic member)
60a Reflective surface

Claims (6)

The flange portion provided at the downstream end of the upstream piping and the upstream of the downstream piping are arranged at a position sandwiched between the upstream piping and the downstream piping for conveying the exhaust gas to be analyzed A sensor main body having a pair of abutting surfaces that abut each of the flange portions provided at the side end portions via a gasket and an exhaust gas passage hole through which the exhaust gas passes through the pair of abutting surfaces ;
An irradiation unit for irradiating an analysis laser beam toward the exhaust gas passage hole;
A reflecting portion for reflecting the laser light in the exhaust gas passage hole, and reflecting the laser light a predetermined number of times to transmit the exhaust gas in the exhaust gas through a predetermined path in the exhaust gas passage hole ;
A light receiving portion for receiving laser light transmitted through the exhaust gas in the exhaust gas passage hole;
A cylindrical member that covers the reflecting surface by being provided in the exhaust gas passage hole in a state of being spaced from a wall surface that forms the exhaust gas passage hole, and has an inner diameter that is upstream and downstream. The length of the pipe in the cylinder axis direction is substantially the same as the length of the exhaust gas passage hole, and a passage hole portion that allows incidence and reflection of the laser beam on the reflection surface in a predetermined path is provided. An optical path limiting member having,
A positioning jig for positioning the radial position of the optical path limiting member in the exhaust gas passage hole so as to be adjustable;
A sensor for exhaust gas analysis, comprising: The positioning jig is
The sensor body is provided with a spacer pin that is screwed into a screw hole that opens in the exhaust gas passage hole and protrudes into the exhaust gas passage hole, and a tip that contacts the outer peripheral surface of the optical path limiting member.
The exhaust gas analysis sensor according to claim 1. A fixing jig for fixing the radial position of the optical path limiting member in the exhaust gas passage hole;
The exhaust gas analysis sensor according to claim 2. The fixing jig is
The sensor body is rotatably provided in a through-hole penetrating from the outer peripheral surface of the sensor body to the exhaust gas passage hole, a tip portion projects into the exhaust gas passage hole, and a male screw formed at the tip portion is used as the optical path limiting member. Consisting of fixing bolts screwed into the formed screw holes,
The exhaust gas analysis sensor according to claim 3. The irradiation unit and the light receiving unit are:
A first optical path forming member fixed to the sensor body and forming a first optical path communicating with the exhaust gas passage hole;
By adjusting the posture with respect to the first optical path forming member, the irradiation direction of the laser light with respect to the exhaust gas passage hole in the irradiation unit or the light reception direction with respect to the laser light from the exhaust gas passage hole in the light receiving unit is adjusted. And a second optical path forming member forming a second optical path communicating with the first optical path,
An adjusting member for engaging the first optical path forming member and the second optical path forming member, and adjusting an attitude of the second optical path forming member with respect to the first optical path forming member;
The first optical path forming member of the second optical path forming member is interposed between the first optical path forming member and the second optical path forming member engaged with each other by the adjusting member, and elastically. An elastic member for maintaining a posture with respect to,
The exhaust gas analysis sensor according to any one of claims 1 to 4, wherein the sensor for exhaust gas analysis is provided. The elastic member is
6. The exhaust gas analysis sensor according to claim 5 , wherein the exhaust gas analysis sensor is made of a material having a lower thermal conductivity than a material constituting the first optical path forming member.

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