JP5038923B2 - Exhaust gas analyzer - Google Patents

Description

  The present invention relates to a technology of an exhaust gas analyzer, and more specifically, a component in exhaust gas by irradiating the exhaust gas in an exhaust path for exhausting exhaust gas from an internal combustion engine with laser light and detecting the laser light transmitted through the exhaust gas. The present invention relates to an improved technology of an exhaust gas analyzer having a measuring unit for measuring concentration.

  2. Description of the Related Art Conventionally, as a device for measuring and analyzing the concentration and temperature of exhaust gas discharged from an internal combustion engine such as an engine such as an automobile, a measuring unit (exhaust gas analysis sensor) including a light source and a detector unit in an exhaust path ) Is directly arranged, and the configuration of the exhaust gas analyzer configured to measure the component concentration in the exhaust gas in real time by detecting the laser beam transmitted through the exhaust gas flowing through the exhaust path is known. .

  Specifically, the configuration of a conventional exhaust gas analyzer includes irradiating a laser beam toward an exhaust gas passage hole through which exhaust gas discharged from an internal combustion engine passes, and after reflecting the laser beam multiple times with a reflecting mirror, It is configured to detect laser light that has passed through. As described above, the exhaust gas analyzer multi-reflects the laser light by the pair of reflecting mirrors facing each other in the exhaust gas passage hole of the measurement unit, and ensures a longer distance (measurement length) through which the laser light passes through the exhaust gas. Thus, the measurement accuracy is improved.

  By the way, the above-mentioned conventional exhaust gas analyzer is used for, for example, a test for evaluating performance characteristics of a gasoline engine as an internal combustion engine from component concentrations in exhaust gas. At that time, when the engine is operated in an abnormal combustion state, a large amount of exhaust gas contamination such as soot and carbon suit is included in the exhaust gas due to abnormal combustion. When exhaust gas containing a large amount of exhaust gas dirt is measured with an exhaust gas analyzer, exhaust gas dirt adheres to the surface of the reflector exposed to the exhaust gas passage hole when the exhaust gas passes through the exhaust gas passage hole. There was a case.

  In particular, in the configuration of the exhaust gas analyzer described above, it is necessary to accurately multiple-reflect the laser light by the reflecting mirror, and thus when the exhaust gas dirt adheres to the surface of the reflecting mirror, the reflectance of the laser light decreases, As a result, there is a problem that the measurement accuracy of the component concentration in the exhaust gas is lowered and accurate analysis cannot be performed. Further, when the measurement is continued for a long time, the reflectance of the laser beam by the reflecting mirror is gradually lowered, and there is a problem that the accuracy is not constant between the initial stage and the latter stage of the measurement.

  Therefore, in the configuration of the conventional exhaust gas analyzer, for example, as shown in Patent Document 1, a photocatalyst layer is provided on the surface of a reflecting mirror, and a laser diode that generates a photocatalyst beam for irradiating the photocatalyst layer is provided. A configuration has been proposed in which the photocatalyst layer is activated by irradiating the reflecting mirror through the optical fiber to remove the exhaust gas dirt adhering to the surface of the reflecting mirror (see Patent Document 1).

  However, in the configuration of the exhaust gas analyzer disclosed in Patent Document 1, it is necessary to provide a reflecting mirror having a photocatalyst layer separately provided on the surface and a laser diode that generates a photocatalyst light beam. However, there is a problem that the manufacturing cost increases. Therefore, conventionally, there has been a demand for a structure capable of keeping the surface of the reflecting mirror clean with a simpler configuration as an exhaust gas analyzer.

  On the other hand, several exhaust gas analyzers having a configuration in which a purge gas is allowed to flow in an analysis path have been proposed so far from the viewpoint of removing exhaust gas dirt adhering to the path. For example, in Patent Document 2, in an exhaust gas measuring apparatus having a sampling line for introducing exhaust gas to an analyzer, an inert gas is used as a purge gas downstream of the sampling line in order to remove dirt in the sampling line. The structure provided with the purge line for supplying is disclosed (refer patent document 2).

Certainly, when the configuration disclosed in Patent Document 2 is applied to the exhaust gas analyzer having the above-described configuration and purge gas is supplied to the surface of the reflecting mirror in the exhaust gas analyzer, exhaust gas contamination is caused on the surface of the reflecting mirror by the purge gas. It can be expected that the exhaust gas fouling that adheres to the surface of the reflecting mirror is removed. However, if the purge gas is mixed into the exhaust gas to be measured, the concentration and flow rate of the exhaust gas change, and as a result, the component concentration in the exhaust gas cannot be stably measured and accurate analysis cannot be performed. There was a problem.
JP 2006-343293 A JP 2003-75309 A

  Accordingly, the present invention relates to an exhaust gas analyzer, which solves the above-described conventional problems, and provides an exhaust gas analyzer that can keep the surface of the reflecting mirror clean with a simple configuration and stabilize the measurement accuracy. It is for the purpose.

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

  That is, according to the first aspect of the invention, there is provided a measuring unit that measures the component concentration in the exhaust gas by irradiating the exhaust gas in the exhaust path for discharging the exhaust gas of the internal combustion engine with laser light and detecting the laser light that has passed through the exhaust gas. In the exhaust gas analyzer, the measurement unit is provided with an exhaust gas passage hole through which the exhaust gas in the exhaust path passes, and a reflecting mirror that multi-reflects the laser light emitted toward the exhaust gas passage hole is provided. In addition to the main body part and the exhaust gas passing through the exhaust gas passage hole, the exhaust gas is separated from the exhaust path, and the purge path for blowing the diverted exhaust gas toward the surface of the reflecting mirror is provided. .

  According to a second aspect of the present invention, the purge path is constituted by an internal hollow pipe member, one end is connected to a pipe constituting the exhaust path, and the other end is connected to the main body.

  According to a third aspect of the present invention, the purge path is provided with a filter member for removing exhaust gas dirt in the exhaust gas in the path.

  According to a fourth aspect of the present invention, the other end of the purge path is connected to one end side in the longitudinal direction of the reflecting mirror in the main body.

  According to a fifth aspect of the present invention, the measurement unit includes a recirculation path that recirculates the exhaust gas blown from the purge path toward the reflecting mirror to the exhaust path.

  7. The exhaust gas flow rate according to claim 6, wherein the purge route blows the separated exhaust gas toward the surface of the reflecting mirror in accordance with the timing when the exhaust gas in the exhaust route that has not been divided passes through the exhaust gas passage hole. Adjustment means are provided.

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

  Since it is set as the structure shown in Claim 1, the surface of a reflective mirror can be kept clean with a simple structure, the reflection loss of the laser beam in a reflective mirror surface is reduced, and the measurement precision of the component density | concentration of waste gas is stabilized. be able to.

  Since it is set as the structure shown in Claim 2, a purge path | route can be easily provided with respect to the measurement part of the existing exhaust gas analyzer.

  Since it is set as the structure shown in Claim 3, the surface of a reflective mirror can be reliably cleaned by converting the waste gas in the purge path | route sprayed toward a reflective mirror cleanly.

  Since it was set as the structure shown in Claim 4, the exhaust gas from the purge path | route sprayed toward the reflective mirror can be spread over the whole surface effectively along the length direction of a reflective mirror, and the surface of a reflective mirror is made. It can be surely cleaned.

  Since it was set as the structure shown in Claim 5, the exhaust gas density | concentration in an exhaust path can be kept substantially constant by recirculating exhaust gas to an exhaust path, even if it is a case where a measurement part is installed in the several places of an exhaust path. The component concentration in the exhaust gas can be measured continuously.

  Since the configuration described in claim 6 is adopted, even if the measurement conditions such as the exhaust gas flow rate in the exhaust path change with time, the flow rate of the exhaust gas supplied to the reflecting mirror is appropriately adjusted according to the change in the measurement conditions. Therefore, it is possible to reduce the influence on the measurement result due to the concentration change of the exhaust gas and improve the measurement stability.

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 according to an embodiment of the present invention is mounted on a vehicle, FIG. 2 is a side view of a measurement unit of the exhaust gas analyzer of the first embodiment, and FIG. 4 is a vertical sectional view of the position near the reflecting mirror in FIG. 2, FIG. 5 is a horizontal sectional view of the position near the reflecting mirror in FIG. 2, and FIG. 6 is the measuring section shown in FIG. FIG. 7 is a side view of the measuring unit of the exhaust gas analyzer of the second embodiment, FIG. 8 is a side view of the measuring unit of the exhaust gas analyzer of the third embodiment, and FIG. FIG. 10 is a vertical sectional view of a position near the reflecting mirror of the measurement unit of the exhaust gas analyzer of the fifth embodiment.
In the following embodiment, as shown in FIG. 4, the length direction as the longitudinal direction of the main body 50 is defined as the X direction, and the width direction as the short direction is defined as the Y direction.

First, the overall configuration of the exhaust gas analyzer 1 of the first 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 that is an internal combustion engine disposed in an automobile 2. Specifically, the exhaust gas analyzer 1 includes a plurality of measuring units 5, 5... Disposed at a plurality of locations in the exhaust path 3 described above, and a laser oscillation / light receiving controller connected to the measuring unit 5. 6 and a computer device 7 connected to the controller 6.

  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, A muffler 34, an exhaust pipe 35, and the like are included. 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.

  The measurement units 5, 5... Of the present embodiment are arranged at four locations in the exhaust path 3, specifically, between the engine 20 and the exhaust pipe 31 on the upstream side of the first catalyst device 32, They are disposed between the first 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, respectively.

  In the exhaust gas analyzer 1, the concentration of exhaust gas flowing through the exhaust path 3 is continuously increased by receiving infrared laser light from the controller 6 and receiving laser light after passing through the exhaust gas in each measuring unit 5. Measured in real time. Then, the obtained data is sent from the controller 6 to the computer device 7 to analyze the components in the exhaust gas.

  The controller 6 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 6 is provided with a differential type photodetector (not shown) connected to the measurement unit 5, and the signal light received by the measurement unit 5 is guided and attenuated through the exhaust gas. The signal light of the laser beam that has been transmitted and the laser beam that has not passed through the exhaust gas is output to the connected computer device 7. In the computer apparatus 7, the output signal from the controller 6 is analyzed, and the exhaust gas is analyzed 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, the spot exhaust gas can be measured in one section of the exhaust path 3 by each measuring unit 5. In particular, as in the present embodiment, by providing the measurement units 5 at a plurality of locations in the exhaust path 3, it is possible to instantaneously measure how the exhaust gas changes in a predetermined section of the exhaust path 3, and the exhaust gas Can be continuously measured in real time.

Next, the configuration of the measurement unit 5 will be described in detail below.
In the exhaust gas analyzing apparatus 1 of the present embodiment, the measurement units 5, 5... Attached to the exhaust path 3 are configured substantially the same. Hereinafter, as an example, the measurement unit 5 disposed between the first catalyst device 32 and the second catalyst device 33 will be described.

  As shown in FIG. 2, the measurement unit 5 of the present embodiment irradiates the exhaust gas in the exhaust path 3 that exhausts the exhaust gas of the engine 20 with laser light, and detects the laser light that has passed through the exhaust gas to detect the laser light in the exhaust gas. The component concentration is measured, and the predetermined amount of the exhaust path 3 is determined in a state where the main body 50 is sandwiched from the front and rear directions by the pipe joints 36 and 36 provided at the connection parts of the pipes 3a and 3a constituting the exhaust path 3. It is attached to the part of.

  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 measuring section 5 (the main body section 50) is sandwiched between the opening ends of the pair of pipe joints 36 and 36 on the side where the flange section 36b is provided via a gasket (not shown), and the flange sections 36b and 36b are connected to each other. It 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 the pipe 3a, and is configured so that the flow of exhaust gas is not hindered. In addition, a gasket (not shown) has a hole having substantially the same diameter as the through hole 36a and the like, and even if the measuring part 5 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 3.

  In this way, the measurement unit 5 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 through holes 36a of the one pipe joint 36. Then, the gas passes through the exhaust gas passage hole 50a of the main body 50 and is sent to the downstream side of the exhaust path 3 from the through hole 36a of the other pipe joint 36.

  Note that a purge path 55 and a reflux path 56 described later are connected to the pipe joint 36 of this embodiment, and the exhaust gas in the exhaust path 3 is diverted from the exhaust path 3 to the purge path 55 via the pipe joint 36. On the other hand, the exhaust gas blown toward the reflecting mirror 52 provided in the measurement unit 5 is recirculated from the recirculation path 56 to the exhaust path 3 via the pipe joint 36 (see FIG. 5). Details of the purge path 55 and the reflux path 56 will be described later.

  As shown in FIGS. 2 to 5, the measurement unit 5 of the present embodiment has a circular exhaust gas passage hole 50 a that is formed from a rectangular thin plate material and through which exhaust gas in the exhaust passage 3 passes through a substantially central part. , The irradiation unit 51 that irradiates the analysis laser light into the exhaust gas passage hole 50a, and a pair that multi-reflects the laser light emitted from the irradiation unit 51 into the exhaust gas passage hole 50a. Reflecting mirrors 52, 52, a light receiving portion 53 for detecting laser light transmitted through the exhaust gas, a sleeve-shaped cover ring 54 disposed in the exhaust gas passage hole 50a, and an exhaust gas passing through the exhaust gas passage hole 50a. Separately, the exhaust gas is diverted from the exhaust path 3, the purge path 55 for blowing the diverted exhaust gas toward the surfaces of the reflecting mirrors 52 and 52, and the exhaust gas blown toward the reflecting mirror 52 is recirculated to the exhaust path 3. It is composed of a flow path 56 and the like.

  The main body 50 is assembled with the irradiation unit 51 and the light receiving unit 53 so that the light projecting surface and the light receiving surface face the central direction of the exhaust gas passage hole 50a. It is arranged facing the upper and lower positions so as to face the hole 50a, and is fixed in a parallel state so that the laser beam irradiated from the irradiation unit 51 crosses the exhaust gas passage hole 50a perpendicularly to the exhaust path 3. (See FIG. 3).

  Laser light is emitted from the irradiation unit 51 along a cross section orthogonal to the exhaust path 3, and the laser light emitted from the irradiation unit 51 is received by the light receiving unit 53. In the present embodiment, the irradiation unit 51 and the light receiving unit 53 are connected to the controller 6 described above, and the infrared laser light emitted from the controller 6 is irradiated to the exhaust gas passage hole 50a via the irradiation unit 51, and the exhaust gas is discharged. The laser beam transmitted therethrough is received by the light receiving unit 53 and a light reception signal is input to the controller 6.

  The reflecting mirrors 52 and 52 are formed in the shape of a long plate in plan view, and are arranged so as to be substantially parallel across the exhaust gas passage hole 50a along the length direction of the main body 50 (X direction in FIG. 5). Yes. The laser light emitted from the irradiation unit 51 by the reflecting mirrors 52 and 52 is reflected by the one reflecting mirror 52 toward the other reflecting mirror 52 and is alternately reflected by the pair of reflecting mirrors 52 and 52 to receive light. It reaches the light receiving portion 53 on the side (see FIGS. 3 and 5). As described above, in the measurement unit 5 of the present embodiment, the laser beam irradiated by the irradiation unit 51 is reflected by the pair of reflecting mirrors 52 and 52 a plurality of times in one cross section orthogonal to the exhaust path 3 and then the light receiving unit 53. Is received.

  The cover ring 54 is a cylindrical member having a passage hole 54a, and is formed such that the outer diameter of the passage hole 54a is smaller than the inner diameter of the exhaust gas passage hole 50a (see FIGS. 3 and 4). Further, the width of the cover ring 54 is formed substantially the same as the width of the main body 50. A pair of elongated laser light passage small holes (not shown) are formed on the peripheral surface of the cover ring 54, and each laser light passage small hole is directed from the irradiation unit 51 into the exhaust gas passage hole 50a. The laser light irradiated in this way is provided on the optical path of the laser light so that it is reflected a plurality of times between the reflecting mirrors 52 and 52 and received by the light receiving portion 53.

  As shown in FIGS. 4 and 5, the main body 50 of this embodiment is provided with a plurality of mounting holes 50b, 50b,... That connect the external space and the internal space of the exhaust gas passage hole 50a. The pipe member 55a of the purge path 55 and the pipe member 56a of the reflux path 56, which will be described later, are fitted into the mounting holes 50b, 50b,. The mounting hole 50b of this embodiment is drilled along the length direction (X direction in FIG. 5) of the main body 50 in a substantially horizontal state with respect to the surface of the reflecting mirror 52 provided in the main body 50. Is opened to the external space, and the other end is opened toward the exhaust gas passage hole 50a. In the present embodiment, four mounting holes 50b, 50b,... Are formed in one main body 50, and the connection end 55b of the purge path 55 and the connection end 56b of the reflux path 56 are respectively fitted into the mounting holes 50b. The

  The attachment hole 50b has an opening on the exhaust gas passage hole 50a side opened on the surface side of the main body 50 on the end side in the length direction (X direction in FIG. 5) of the reflecting mirror 52, and the connection end 55b of the purge path 55 The exhaust gas discharged from the exhaust gas is sprayed toward the surface of the reflecting mirror 52, and the exhaust gas sprayed from the connecting end 56b of the reflux path 56 to the reflecting mirror 52 is introduced into the reflux path 56 and discharged from the exhaust gas passage hole 50a. The

Next, the configuration of the purge path 55 and the reflux path 56 will be described in detail below.
In this embodiment, a pair of purge paths 55 and reflux paths 56 are provided for the main body 50. In the following embodiments, unless otherwise specified, one of the purge paths 55 and the reflux paths 56 is provided. Although the configuration will be described, the other configuration is assumed to be configured similarly.

  As shown in FIGS. 4 to 6, the purge path 55 divides the exhaust gas from the exhaust path 3 separately from the exhaust gas passing through the exhaust gas passage hole 50 a of the main body 50, and the split exhaust gas is reflected by the reflecting mirrors 52 and 52. It is a diversion path provided for spraying toward the surface. Specifically, the purge path 55 of the present embodiment is configured by a pipe member 55a formed hollow inside, and the pipe member 55a constituting the purge path 55 has one end connected to the pipe 3a constituting the exhaust path 3. The other end of the connection end 55 b is connected to the main body 50.

  One end of the pipe member 55 a is connected to the pipe joint 36 and opened to the through hole 36 a of the pipe joint 36. Therefore, a part of the exhaust gas that passes through the through hole 36a of the pipe joint 36 from the exhaust path 3 is diverted into the pipe member 55a through one end of the pipe member 55a (see FIG. 6).

  The connection end 55 b is fitted into a mounting hole 50 b formed in the main body 50. As described above, one end of the mounting hole 50b is opened to the external space, and the other end is opened toward the exhaust gas passage hole 50a. Therefore, the mounting hole 50b is diverted from the connection end 55b fitted into the mounting hole 50b. The discharged exhaust gas is discharged toward the exhaust gas passage hole 50a. And since the attachment hole 50b is opened so that it may open to the one end side of the length direction (X direction in FIG. 4) of the reflective mirror 52, the waste gas discharged | emitted from the connection end 55b is waste gas passage hole 50a. It is sprayed toward the surface of the reflecting mirror 52 exposed to.

  In the purge path 55 of the present embodiment, exhaust gas is blown toward the surface of the reflecting mirror 52 from one end side to the other end side in the length direction of the reflecting mirror 52 (X direction in FIG. 5). In other words, the laser beam emitted from the irradiation unit 51 is alternately reflected by the pair of reflecting mirrors 52 and 52 in the direction orthogonal to the flow of the exhaust gas passing through the exhaust gas passage hole 50a by the purge path 55. Exhaust gas is blown across the optical path until it reaches the light receiving unit 53 on the side.

  Further, the purge path 55 is provided with a filter member 55c in the middle of the pipe member 55a and reaching the connection end 55b, and the exhaust gas in the purge path 55 passes through the filter member 55c to be contained in the exhaust gas. Exhaust dirt such as soot and carbon suit is removed. That is, the exhaust gas diverted from the exhaust path 3 to the purge path 55 is converted to a clean state by removing exhaust gas contamination such as soot and carbon suit between the connection end 55b of the purge path 55 and from the connection end 55b. It is sprayed toward the reflecting mirror 52.

  The material of the filter member 55c is not particularly limited. For example, a laminated metal filter such as a laminated metal mesh filter or a laminated metal non-woven filter that filters exhaust gas dirt such as soot and carbon suit, and a fine material formed from a heat-resistant ceramic. A hole filter or the like can be used.

  Since the flow rate of the exhaust gas diverted from the exhaust path 3 to the purge path 55 affects the flow rate of the exhaust gas passing through the exhaust gas passage hole 50a from the exhaust path 3, the length and the diameter of the purge path 55 (pipe member 55a) are , And is set as appropriate to minimize such influence. Preferably, the exhaust gas diverted from the exhaust path 3 to the purge path 55 is appropriately sprayed on the surface of the reflecting mirror 52 in accordance with the timing when the exhaust gas not diverted from the exhaust path 3 passes through the exhaust gas passage hole 50a. It is set (for example, see FIG. 8).

  As described above, in the measurement unit 5 of the present embodiment, the purge path 55 is provided, so that the exhaust gas in the exhaust path 3 flows from the pipe joint 36 to the purge path 55 (pipe member 55a →→ filter member 55c → connection end 55b. ) → mounting hole 50b → exhaust gas passage hole 50a → reflecting mirror 52 and configured to be blown toward the surface of reflecting mirror 52 (see FIG. 6).

  On the other hand, as shown in FIGS. 4 to 6, the recirculation path 56 is a path for recirculating exhaust gas blown from the purge path 55 toward the reflecting mirror 52 to the exhaust path 3. The reflux path 56 of the embodiment is configured by a pipe member 56 a formed in the hollow inside, and the pipe member 56 a configuring the reflux path 56 is the other pipe having one end connected to the pipe 3 a configuring the exhaust path 3. Connected to the joint 36, the other connection end 56 b is connected to the main body 50.

  The connection end 56b is an attachment hole 50b formed in the main body 50, and is located at a position facing the attachment hole 50b into which the connection end 55b of the purge path 55 is inserted with the reflector 52 interposed therebetween. 50b is inserted. The exhaust gas blown from the purge path 55 along the length direction of the reflecting mirror 52 is introduced into the pipe member 56a from the connection end 56b fitted in the mounting hole 50b. That is, when the exhaust gas divided into the purge path 55 is blown toward the surface of the reflecting mirror 52 in the exhaust gas passage hole 50a, a part of the exhaust gas is sent as it is to the downstream side of the exhaust gas passage hole 50a. Most of them are introduced into the reflux path 56 (the pipe member 56a) through the connection end 56b.

  One end of the pipe member 56 a is connected to the pipe joint 36 and opened to the through hole 36 a of the pipe joint 36. Therefore, the exhaust gas in the pipe member 56 a of the reflux path 56 is sent to the through hole 36 a of the pipe joint 36 through one end of the pipe member 56 a and is refluxed to the exhaust path 3.

  As described above, in the measurement unit 5 of the present embodiment, the reflux path 56 is provided, so that the exhaust gas struck toward the surface of the reflecting mirror 52 causes the exhaust gas passage hole 50a → the attachment hole 50b → the reflux path 56 (connection). It is configured to flow from the end 56b → the pipe member 56a) → the pipe joint 36 and to be returned to the exhaust path 3 (see FIG. 6).

  As described above, the exhaust gas analyzer 1 of the present embodiment irradiates the exhaust gas in the exhaust path 3 that exhausts the exhaust gas of the engine 20 with laser light, and detects the laser light that has passed through the exhaust gas, thereby detecting the components in the exhaust gas. In the exhaust gas analyzer 1 having the measuring unit 5 for measuring the concentration, the measuring unit 5 is provided with an exhaust gas passage hole 50a through which the exhaust gas in the exhaust passage 3 passes and is irradiated toward the exhaust gas passage hole 50a. Separately from the main body 50 in which the reflecting mirror 52 for multiple reflection of light is disposed and the exhaust gas passing through the exhaust gas passage hole 50a, the exhaust gas is diverted from the exhaust passage 3, and the diverted exhaust gas is directed to the surface of the reflecting mirror 52. Since the purge path 55 for spraying is provided, the surface of the reflecting mirror 52 can be kept clean with a simple configuration, the reflection loss of the laser beam on the surface of the reflecting mirror 52 is reduced, and the component concentration of the exhaust gas The measurement accuracy can be stabilized.

  That is, in the exhaust gas analyzer 1, a purge path 55 is provided in the measurement unit 5, which separates the exhaust gas from the exhaust path 3 separately from the exhaust gas passing through the exhaust gas passage hole 50 a and blows the split exhaust gas toward the surface of the reflecting mirror 52. Therefore, it is possible to prevent the exhaust gas (purge gas) supplied from the purge path 55 from adhering exhaust gas dirt such as soot and carbon suit contained in the exhaust gas to the surface of the reflecting mirror 52, The exhaust gas dirt adhering to the surface of the reflecting mirror 52 can be removed, and the surface of the reflecting mirror 52 can be kept clean. Further, since the exhaust gas (purge gas) can be supplied to the surface of the reflecting mirror 52 simply by providing the purge path 55 in this way, the measuring unit 5 can be configured simply.

  Further, in the exhaust gas analyzer 1 of the present embodiment, the concentration of the component in the exhaust gas is measured from the amount of absorption corresponding to each component contained in the exhaust gas to be measured in the measuring unit 5, and the component concentration of the exhaust gas is measured by the laser. It is affected by the exhaust gas concentration on the optical path. As in this embodiment, the exhaust gas in the exhaust path 3 is divided by the purge path 55 and blown to the surface of the reflecting mirror 52, so that the exhaust gas diverted from the exhaust path 3 is reflected by the reflecting mirror 52. Since the laser light path in the vicinity of the surface is crossed, the influence of the exhaust gas concentration on the laser light path can be reduced, and the analysis accuracy of the component concentration in the exhaust gas can be improved.

  In particular, the purge path 55 of the present embodiment is constituted by an internal hollow pipe member 55 a, one end is connected to the pipe 3 a (pipe joint 36) constituting the exhaust path 3, and the other end is connected to the main body 50. Therefore, the purge path 55 made of the pipe member 55a can be easily provided for the existing measurement unit 5.

  Further, the purge path 55 of the present embodiment is provided with a filter member 55c that removes exhaust gas contamination such as soot and carbon suit in the exhaust gas in the purge path 55, so that the exhaust gas blown to the reflecting mirror 52 from the purge path 55. By converting (purge gas) to clean, the surface of the reflecting mirror 52 can be reliably cleaned.

  Further, since the purge path 55 of the present embodiment is connected to one end side in the length direction of the reflecting mirror 52, the exhaust gas from the purge path 55 sprayed toward the surface of the reflecting mirror 52 is reflected by the reflecting mirror 52. It is possible to effectively spread the entire surface along the length direction, and the surface of the reflecting mirror 52 can be surely cleaned.

  Further, the measurement unit 5 of the present embodiment includes a reflux path 56 that recirculates the exhaust gas sprayed from the purge path 55 toward the reflecting mirror 52 to the exhaust path 3, and is thus sprayed on the surface of the reflecting mirror 52. Since the exhaust gas from the purge path 55 can be sent out of the exhaust gas passage hole 50a without staying on the surface of the reflecting mirror 52, the measurement accuracy of the exhaust gas component concentration can be further stabilized. In particular, the exhaust gas concentration in the exhaust path 3 can be kept substantially constant by recirculating the exhaust gas to the exhaust path 3. For example, even when the measurement units 5 are installed at a plurality of locations in the exhaust path 3. The component concentration in the exhaust gas can be measured continuously.

  In addition, as a structure of the exhaust gas analyzer 1, it is not limited to the Example mentioned above, A various change is possible unless it deviates from the objective of this invention.

  That is, as the configuration of the measurement unit 5, the exhaust gas analyzer 1 of the first embodiment described above is provided with the purge path 55 and the reflux path 56 (see FIG. 2), but the inner reflux path 56 is not necessarily provided. Absent. Specifically, as in the second embodiment shown in FIG. 7, only the purge path 55 may be provided in the measurement unit 5 and the reflux path 56 may be omitted. In such a configuration, the exhaust gas blown to the reflecting mirror 52 from the purge path 55 is sent downstream of the exhaust path 3 through the exhaust gas passage hole 50a. By comprising in this way, the measurement part 5 can be comprised more simply and compactly.

  Further, as the configuration of the purge path 55, as in the third embodiment shown in FIG. 8, the separated exhaust gas is adjusted in accordance with the timing at which the exhaust gas in the exhaust path 3 that has not been diverted passes through the exhaust gas passage hole 50a. A pump member 55d as exhaust gas flow rate adjusting means for blowing toward the surface of the reflecting mirror 52 may be separately provided. Specifically, the pump member 55d is connected to the controller 6 described above, and is configured to be able to adjust the flow rate of the exhaust gas blown to the reflecting mirror 52 out of the exhaust gas in the purge path 55. The controller 6 controls the pump member 55d. By controlling the opening and closing of a valve (not shown) or the like, the flow rate of exhaust gas blown from the purge path 55 to the reflecting mirror 52 is controlled.

  As a method of adjusting the exhaust gas flow rate by the pump member 55d, first, when the exhaust gas F1 on the upstream side of the exhaust path 3 reaches one pipe joint 36, a part of the exhaust gas F1 in the exhaust path 3 is purged with the purge path 55. Divided into. The exhaust gas F3 that has not been split into the purge path 55 eventually reaches the exhaust gas passage hole 50a from one of the pipe joints 36. On the other hand, the flow rate of the exhaust gas F2 branched into the purge path 55 by the pump member 55d is controlled so as to synchronize with the timing at which the exhaust gas F3 not split into the purge path 55 reaches the exhaust gas passage hole 50a. Exhaust gas F4 is sprayed on the surface of the reflecting mirror 52.

  In the above-described embodiment (for example, refer to FIG. 2 and the like), the separated exhaust gas is directed toward the surface of the reflecting mirror 52 in accordance with the timing when the exhaust gas in the exhaust passage 3 that has not been divided passes through the exhaust gas passage hole 50a. The length and the diameter of the pipe member 55a of the purge path 55 are appropriately set so as to be sprayed. However, when the measurement conditions such as the exhaust gas flow rate in the exhaust path 3 change over time, the measurement cannot be performed. There is a problem that it is inferior in stability. By providing a separate pump member 55d in the purge path 55 as in the present embodiment, even when the measurement conditions such as the exhaust gas flow rate in the exhaust path 3 change with time, the reflecting mirror 52 is changed according to the change in the measurement conditions. Since the flow rate of the exhaust gas supplied to can be adjusted as appropriate, it is possible to reduce the influence on the measurement result due to the concentration change of the exhaust gas and to improve the measurement stability.

  Further, as a configuration of the purge path 55, as in the fourth embodiment shown in FIG. 9, as a purge path 155, one end of a pipe member 155 a is connected to a pipe 3 a constituting the exhaust path 3. The other pipe joint 36 connected to the downstream side of the exhaust path 3 may be connected, and the other end may be connected to the main body 50. Specifically, in the configuration of the purge path 155, a part of the exhaust gas that has passed through the exhaust gas passage hole 50a of the exhaust gas in the exhaust path 3 is diverted into the purge path 155 and sprayed onto the surface of the reflecting mirror 52. Configured.

  In the first embodiment described above, the purge path 55 is connected to one end side in the length direction of the reflecting mirror 52 (X direction in FIG. 5) with respect to the main body 50. The connection position between the main body 50 and the main body 50 is not particularly limited. For example, the main body 50 may be connected to one end of the reflecting mirror 52 in the width direction (Y direction in FIG. 5).

  Further, as the configuration of the main body 50, in the exhaust gas analyzer 1 of the first embodiment described above, the mounting hole 50b is formed along the length direction of the main body 50 in a substantially horizontal state with respect to the surface of the reflecting mirror 52. Although it is provided (refer to FIG. 4), for example, as in the fifth embodiment shown in FIG. It may be perforated. That is, as in the configuration of the main body 50, the attachment hole 50b is formed in an inclined state with respect to the surface of the reflecting mirror 52, so that the connection end 55b of the purge path 55 inserted into the attachment hole 50b. Since the exhaust gas is blown from the oblique direction to the surface of the reflecting mirror 52, the entire surface can be more effectively distributed along the length direction of the reflecting mirror 52.

The side view which showed the state which mounted the exhaust gas analyzer which concerns on one Example of this invention in the vehicle. The side view of the measurement part of the exhaust gas analyzer of the first embodiment. The perspective view of the measurement part of FIG. 2 similarly. FIG. 3 is a vertical sectional view of the vicinity of the reflecting mirror in FIG. 2. FIG. 3 is a horizontal cross-sectional view of the vicinity of the reflecting mirror in FIG. The side view which showed a mode that waste gas flows in the measurement part shown in FIG. The side view of the measurement part of the exhaust gas analyzer of 2nd Example. The side view of the measurement part of the exhaust gas analyzer of 3rd Example. The side view of the measurement part of the exhaust gas analyzer of 4th Example. The vertical sectional view of the position near the reflecting mirror of the measurement part of the exhaust gas analyzer of the fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas analyzer 3 Exhaust path 3a Piping 5 Measuring part 20 Engine 36 Pipe joint 50 Main body part 50a Exhaust gas passage hole 51 Irradiation part 52 Reflector 53 Light receiving part 55 Purge path 55a Pipe member 55b Connection part 55c Filter member 56 Reflux path 56a Pipe Member 56b Connection part

Claims (6)

In the exhaust gas analyzer having a measurement unit that measures the component concentration in the exhaust gas by irradiating the exhaust gas in the exhaust path for discharging the exhaust gas of the internal combustion engine with laser light and detecting the laser light that has passed through the exhaust gas,
The measuring unit is
An exhaust gas passage hole through which the exhaust gas in the exhaust path passes is formed, and a main body portion in which a reflecting mirror that multi-reflects the laser light irradiated toward the exhaust gas passage hole is disposed,
Separately from the exhaust gas passing through the exhaust gas passage hole, an exhaust gas analyzer comprising a purge path for diverting the exhaust gas from the exhaust path and blowing the diverted exhaust gas toward the surface of the reflecting mirror .   2. The exhaust gas analysis according to claim 1, wherein the purge path is constituted by an internal hollow pipe member, one end is connected to a pipe constituting the exhaust path, and the other end is connected to the main body. apparatus.   The exhaust gas analyzer according to claim 1, wherein the purge path is provided with a filter member that removes exhaust gas contamination in the exhaust gas in the path.   4. The exhaust gas analyzer according to claim 1, wherein the other end of the purge path is connected to one end side in a longitudinal direction of the reflecting mirror in the main body.   The said measurement part is equipped with the recirculation | reflux path | route which recirculates the exhaust gas sprayed toward the said reflective mirror from the said purge path | route to the said exhaust path, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The exhaust gas analyzer according to 1.   The purge path is provided with exhaust gas flow rate adjusting means for blowing the split exhaust gas toward the surface of the reflecting mirror in accordance with the timing at which the exhaust gas in the exhaust path that has not been split passes through the exhaust gas passage hole. The exhaust gas analyzer according to any one of claims 1 to 5, wherein:

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