JP2018159368A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor cover of an exhaust gas purification device capable of suitably protecting a sensor installed in the exhaust purification device with a simple structure. SOLUTION: A purifying material (particulate filter) 5 for purifying an exhaust gas 3 discharged from an engine, a casing 7 installed in a flow path of the exhaust gas 3 and holding the purifying material 5, and a purifying material. A differential pressure pipe 15 provided with a differential pressure sensor 14 that is arranged before and after the purifying material 5 and measures the differential pressure before and after the purifying material 5 and a sensor (temperature sensor) that measures the exhaust gas 3 flowing through the flow path. ) 12, And a sensor cover 16 connected to the differential pressure pipe 15 and arranged from the differential pressure pipe 15 to the periphery of the sensor 12. [Selection diagram] Fig. 1

Description

  The present invention relates to an exhaust emission control device provided with a cover for protecting sensors from flying stones and the like.

  The exhaust gas discharged from the engine contains particulate matter (Particulate Matter), NOx, etc., so the particulate filter, oxidation catalyst, and selective reduction catalyst are placed in the middle of the exhaust pipe through which the exhaust gas flows. It has been practiced to purify exhaust gas with a purifying material such as.

  FIG. 5 shows an example of such an exhaust purification device, in which particulates in the exhaust gas 3 are collected in the middle of the exhaust pipe 4 through which the exhaust gas 3 discharged from the engine 1 through the exhaust manifold 2 flows. The particulate filter 5 and the selective reduction catalyst 6 having the property of allowing NOx to react with the reducing agent on the downstream side of the particulate filter 5 are respectively held in parallel by the casings 7 and 8 and arranged in parallel. The rear end portion of the particulate filter 5 and the front end portion of the selective catalytic reduction catalyst 6 are connected by an S-shaped connecting flow path 9, and the exhaust gas 3 discharged from the rear end portion of the particulate filter 5 is forward. And is introduced into the front end portion of the adjacent selective catalytic reduction catalyst 6.

  As shown in the enlarged view of FIG. 6, the communication channel 9 surrounds the rear end portion of the particulate filter 5 and makes the exhaust gas 3 just after exiting from the rear end portion collide with the wall surface to make a substantially right angle. A gas collecting chamber 9A that collects while changing its direction in a certain direction, and a mixing pipe 9B that extracts the exhaust gas 3 collected in the gas collecting chamber 9A to the front and includes an injector 10 for adding a reducing agent in the middle. Then, the exhaust gas 3 guided forward by the mixing pipe 9B collides with the wall surface and is dispersed while changing the direction in a substantially right angle direction, and the dispersed exhaust gas 3 is dispersed at the front end portion of the selective catalytic reduction catalyst 6. An S-shaped structure is formed by the gas dispersion chamber 9C surrounding the front end so as to be introduced.

  If such a configuration is adopted, particulates in the exhaust gas 3 are collected by the particulate filter 5, and a reducing agent is added to the exhaust gas 3 from the injector 10 in the middle of the mixing pipe 9B on the downstream side. As a result of reacting with NOx in the exhaust gas 3 on the selective catalytic reduction catalyst 6, simultaneous reduction of particulates and NOx in the exhaust gas 3 is achieved.

  At this time, the exhaust gas 3 discharged from the rear end portion of the particulate filter 5 is folded forward by the connecting flow path 9 and then introduced into the front end portion of the adjacent selective catalytic reduction catalyst 6. A long distance from the reducing agent addition position in the middle of the communication flow path 9 to the selective catalytic reduction catalyst 6 is ensured, and the flow of the exhaust gas 3 is turned back to turbulently flow to reduce the reducing agent and the exhaust gas 3. Is promoted.

  In addition, the particulate filter 5 and the selective catalytic reduction catalyst 6 are arranged in parallel, and the connecting flow path 9 is arranged between the particulate filter 5 and the selective catalytic reduction catalyst 6, so that the whole The configuration becomes compact, and the mountability to the vehicle is greatly improved.

  Furthermore, an oxidation catalyst 11 that oxidizes the unburned fuel in the exhaust gas 3 is provided as a purification material in the front stage in the casing 7 in which the particulate filter 5 is held.

  The particulate filter 5 is a filter having a porous honeycomb structure made of ceramic such as cordierite, and the inlets of the respective flow paths partitioned in a lattice shape are alternately sealed, and the flow paths in which the inlets are not sealed. About, its exit is sealed. Thus, when the exhaust gas 3 passes through the particulate filter 5, the particulates in the exhaust gas 3 are collected and deposited on the inner surface of the porous thin wall, and the porous thin wall defining each flow path Only the exhaust gas 3 that permeates the gas is discharged downstream.

  Here, the particulate filter 5 needs to be appropriately burned and removed before the exhaust resistance increases due to clogging, so that the particulate filter 5 needs to be regenerated. Therefore, the flow-through type oxidation catalyst 11 is placed in front of the particulate filter 5. The particulate filter 5 is forcibly regenerated by adding fuel to the exhaust gas 3 upstream of the oxidation catalyst 11 when the amount of particulate accumulation has increased.

  That is, the fuel (HC) added on the upstream side of the particulate filter 5 undergoes an oxidation reaction while passing through the preceding oxidation catalyst 11, and the particulate filter immediately after the inflow of the exhaust gas 3 heated by the reaction heat. The catalyst bed temperature of 5 is raised, the particulates are burned out, and the particulate filter 5 is regenerated.

  In order to execute this type of fuel addition, for example, post injection may be added at a non-ignition timing later than the compression top dead center following the main injection of fuel performed near the compression top dead center. Alternatively, a separate injector may be provided in the flow path on the upstream side of the oxidation catalyst 11, and fuel may be injected from the injector and added to the exhaust gas 3.

  As a document describing the technology related to the exhaust gas purification apparatus as described above, for example, there is Patent Document 1 below.

JP 2009-74420 A JP 2004-293348 A

  By the way, the standards for exhaust gas emission tend to be stricter year by year. In the exhaust gas purification apparatus as described above, the exhaust gas and each of the purification materials are monitored and the state thereof is grasped to improve the purification efficiency. It is demanded. In recent years, on-board failure diagnosis devices that monitor the occurrence of failures in exhaust gas purification devices, turn on warning lights, etc. to notify the driver of the occurrence of failures and record the details of failures. (Onboard diagnosis: abbreviated as OBD) is required in each country, and in order to meet these requirements, it is necessary to attach various sensors to the exhaust emission control device.

  In the example shown in FIG. 6, in order to measure the temperature of the exhaust gas 3 before and after the oxidation catalyst 11, the position immediately before the oxidation catalyst 11 in the exhaust pipe 4 and between the oxidation catalyst 11 and the particulate filter 5 in the casing 7. Are provided with a temperature sensor 12 and a temperature sensor 13, respectively, and a differential pressure sensor 14 for measuring the differential pressure before and after the particulate filter 5. The differential pressure sensor 14 is provided in the middle of the differential pressure pipe 15 routed from a position immediately before the oxidation catalyst 11 in the exhaust pipe 4 to a position on the outlet side of the particulate filter 5 in the casing 7. Based on the value of the differential pressure detected by the sensor 14, the execution of forced regeneration of the particulate filter 5 is determined and the failure of the particulate filter 5 is determined. In executing the forced regeneration, for example, the temperature of the exhaust gas 3 detected by the temperature sensor 12 or the temperature sensor 13 can be used as a reference for the forced regeneration timing or the amount of fuel added.

  Although illustration is omitted here, also in the casing 8 holding the selective catalytic reduction catalyst 6, for example, a temperature sensor for measuring the temperature of the exhaust gas 3 at an appropriate position, or the concentration of NOx in the exhaust gas 3 It is also possible to install sensors such as a concentration sensor for measuring the pressure, and use the detection value of the sensors as a reference for determining the amount of reducing agent injected from the injector 10. In addition, various sensors are installed in the exhaust gas purification device such as a PM sensor for detecting particulates contained in the exhaust gas 3 downstream of the particulate filter 5.

  Such sensors are fixed to sensor bosses provided on the outer surfaces of the exhaust pipe 4 and the casings 7 and 8, for example, and are arranged so that the probe extends from the sensor boss toward the center of the exhaust pipe 4 and the casings 7 and 8. That is, the base end portion of the sensors protrudes from the sensor boss toward the outside of the exhaust pipe 4 and the casings 7 and 8, and in this way, the stones that are jumped off by the tire during driving of the vehicle. There is a risk of damage due to collision.

  As a measure for preventing breakage, for example, a protective wall-like protective member may be arranged around the sensors (see Patent Document 2 above). The structure for supporting the protective member is large, which increases the weight of the entire exhaust gas purification device and increases the material cost. In particular, when a large number of sensors must be arranged for the exhaust gas purification device as described above, the influence on the weight and the cost is increased according to the number of the sensors, and the mountability and the cost are reduced. There is concern about the deterioration.

  In view of such circumstances, the present invention intends to provide an exhaust purification device that can suitably protect a sensor installed in the exhaust purification device with a simple structure.

  The present invention relates to a purifying material for purifying exhaust gas discharged from an engine, a casing that is installed in a flow path of the exhaust gas and that holds the purifying material, and is routed before and after the purifying material. A differential pressure pipe provided with a differential pressure sensor for measuring the differential pressure before and after the purifier, a sensor for measuring exhaust gas flowing through the flow path, and the differential pressure pipe connected to the differential pressure pipe. The present invention relates to an exhaust emission control device comprising a sensor cover arranged around the sensor.

  Thus, in this way, the sensor cover can be supported by a simple structure, the mounting position of the sensor cover can be freely selected, and the entire sensor cover can be made small. In addition, it is easy to set the shape and size of the sensor cover so that the sensor can be effectively protected with a minimum area against flying stones and the like.

  In concrete implementation of the exhaust emission control device of the present invention, the sensor cover includes an attachment portion fixed so as to be wound around the differential pressure pipe, a protective surface portion deployed in the vicinity of the sensor, and the attachment portion. A support portion extending over the protective surface portion, and the mounting portion, the protective surface portion, and the support portion may be configured as a single metal plate.

  According to the exhaust emission control device of the present invention, the following various excellent effects can be obtained.

  (I) According to the first aspect of the present invention, the sensor installed in the exhaust emission control device can be suitably protected with a simple structure.

  (II) According to the invention described in claim 2 of the present invention, since the entire sensor cover is composed of a single metal plate, the structure for protecting the sensor can be further simplified. .

It is a schematic diagram which shows an example of the exhaust gas purification apparatus by implementation of this invention. It is a perspective view which shows the principal part of this invention. It is a figure which shows an example of the form of the sensor cover which comprises the principal part of this invention, (A) is a front view, (B) is sectional drawing equivalent to the IIIB-IIIB arrow of (A). It is a perspective view which shows another example of the form of the sensor cover which comprises the principal part of this invention. It is a whole block diagram which shows an example of the conventional exhaust gas purification apparatus. It is a figure which shows the principal part of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 3 show an example of a form of an exhaust emission control device according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIGS. 5 and 6 denote the same components, and the basic configuration is the same as the conventional one shown in FIGS. 5 and 6. 5. The explanation will be made by borrowing the reference numerals in FIG.

  As shown in FIG. 1, the exhaust purification apparatus of this embodiment is exhausted from the engine 1 through the exhaust manifold 2 (see FIG. 5) in the middle of the exhaust pipe 4 through which the exhaust gas 3 flows. A particulate filter 5 for collecting particulates, and a selective reduction catalyst 6 are held in parallel by casings 7 and 8 on the downstream side of the particulate filter 5. An oxidation catalyst 11 that oxidizes the unburned fuel in the exhaust gas 3 is provided in the front stage of the particulate filter 5 in the casing 7.

  The rear end portion of the particulate filter 5 and the front end portion of the selective catalytic reduction catalyst 6 are connected by an S-shaped connecting flow path 9, and the exhaust gas 3 discharged from the rear end portion of the particulate filter 5 is forward. And is introduced into the front end portion of the adjacent selective catalytic reduction catalyst 6. The communication channel 9 surrounds the rear end portion of the particulate filter 5 and causes the exhaust gas 3 immediately after coming out of the rear end portion to collide with the wall surface and collect the gas collecting chamber while changing the direction in a substantially perpendicular direction. 9A, the exhaust gas 3 collected in the gas collecting chamber 9A is extracted forward, and a mixing pipe 9B provided with an injector 10 for adding a reducing agent in the middle thereof is guided forward by the mixing pipe 9B. A gas dispersion surrounding the front end so that the exhaust gas 3 collides with the wall surface and is dispersed while being turned in a substantially right angle direction, and the dispersed exhaust gas 3 can be introduced into the front end of the selective catalytic reduction catalyst 6. The chamber 9C is configured to form an S-shaped structure.

  A temperature sensor 12 and a temperature sensor 13 are provided at a position upstream of the casing 7 in the exhaust pipe 4 and a position between the oxidation catalyst 11 and the particulate filter 5 in the casing 7, respectively. A differential pressure pipe 15 is routed from the exhaust pipe 4 to the casing 7 and before and after the particulate filter 5, and a differential pressure sensor 14 is provided in the middle of the differential pressure pipe 15. The differential pressure is measured.

  Although not shown here, in addition to the temperature sensors 12 and 13, a temperature sensor for measuring the temperature of the exhaust gas 3 at various points in the flow path, and a NOx sensor for measuring the concentration of NOx. Alternatively, various sensors for measuring the exhaust gas 3 are installed in the exhaust purification device, such as a PM sensor for detecting particulates contained in the exhaust gas 3 downstream of the particulate filter 5.

  In the case of the present embodiment, a feature is that a sensor cover 16 for protecting the temperature sensor 12 is attached in the middle of the differential pressure pipe 15.

  As shown in FIGS. 1 and 2, the temperature sensor 12 has a base end portion 12 a fixed to a sensor boss 17 welded to the exhaust pipe 4, and a probe 12 b extending from the base end portion 12 a toward the center of the exhaust pipe 4. It is arranged in a stretched form.

  The differential pressure pipe 15 is provided between the position immediately before the oxidation catalyst 11 in the exhaust pipe 4 and the position on the outlet side of the particulate filter 5 in the casing 7 as shown in FIGS. The differential pressure sensor 14 measures the differential pressure around the particulate 5.

  The sensor cover 16 is a member that is connected to the differential pressure pipe 15 and is arranged from the differential pressure pipe 15 to the periphery of the temperature sensor 12. As shown in FIGS. 2 and 3, the base end portion of the temperature sensor 12 with respect to the vehicle. A protective surface portion 16a that is positioned in front of 12a and forms a vertical surface along the left-right direction of the vehicle, an attachment portion 16b that attaches the entire sensor cover 16 to the differential pressure pipe 15, and a protective surface portion 16a and an attachment portion 16b. The support part 16c which connects between is provided.

  The protective surface portion 16a is a metal plate-like member that is deployed in the vicinity of the base end portion 12a of the temperature sensor 12 and is disposed so as to cover a necessary front range that is a concern such as stepping stones during driving of the vehicle. In this embodiment, the development range of the protective surface portion 16a is the front of the base end portion 12a, but the range in which the protective surface portion 16a is deployed is not limited to this. For example, when it is considered necessary to protect the base end portion 12a of the temperature sensor 12 from the front side as well as the front side due to the positional relationship with peripheral devices, as shown in FIG. It is good also as a shape extended so that a U-shape may be drawn by planar view from the front to right and left. In addition, as long as the temperature sensor 12 or its base end portion 12a can be appropriately protected, the protective surface portion 16a can take various shapes and arrangements.

  As shown in FIG. 3, the attachment portion 16 b is a metal plate-like member that is fixed so as to be wound around the outer surface of the differential pressure pipe 15. When installing the mounting portion 16b on the differential pressure pipe 15, for example, a metal plate constituting the mounting portion 16b is wound around the differential pressure pipe 15, and the mounting portion 16b is brazed to the differential pressure pipe 15. Thus, the mounting portion 16 b can be fixed to the differential pressure pipe 15. In addition, when fixing the mounting portion 16b, for example, the materials of the mounting portion 16b wound around the differential pressure pipe 15 are caulked, the materials constituting the mounting portion 16b are welded together, or fastened with a bolt or the like. Various methods can be employed.

  The support portion 16c is a member that extends from the attachment portion 16b to the protection surface portion 16a and supports the protection surface portion 16a at an appropriate position with respect to the attachment portion 16b. The protective surface portion 16a, the support portion 16c, and the mounting portion 16b may be configured as separate components. However, the sensor cover 16 including the protective surface portion 16a, the support portion 16c, and the mounting portion 16b is attached to a single metal plate. It can also be formed simply by bending.

  Thus, in the exhaust emission control device having the above-described configuration, the sensor cover 16 is attached to the differential pressure pipe 15 to increase the degree of freedom of the layout of the sensor cover 16 with respect to the temperature sensor 12 and include the support structure. In addition, the entire sensor cover 16 can be reduced in size. That is, if the object to which the sensor cover is to be attached is the casing 7, for example, a support structure that covers the entire circumference of the casing 7 is installed to fix the sensor cover, and the sensor cover is increased in size. I will invite you. Alternatively, the sensor cover may be supported by a bracket or the like that supports the exhaust purification device with respect to the vehicle. In such a case, the position where the sensor cover is supported and the position where the temperature sensor 12 is installed are separated from each other. Inevitably, the sensor cover is too large. In this regard, if the sensor cover 16 is attached to the differential pressure pipe 15 as in the present embodiment, the differential pressure pipe 15 is a thin tubular member, so that the sensor cover 16 is supported by the attachment portion 16b having a simple structure. Is possible.

  At that time, since the differential pressure pipe 15 is routed over the front and rear of the casing 7, in developing the protective surface portion 16 a to an appropriate position with respect to the base end portion 12 a of the temperature sensor 12, The attachment position of the attachment portion 16b can be freely selected, and the entire sensor cover 16 can be further reduced in size by making the attachment portion 16b as close as possible to the protective surface portion 16a. On the other hand, it becomes easy to set the protection surface portion 16a so that the base end portion 12a of the temperature sensor 12 can be effectively protected with a minimum area against flying stones and the like.

  Here, the case where the sensor cover 16 is installed with respect to the temperature sensor 12 has been described as an example, but this is merely a representative example, and the installation target and shape of the sensor cover are not limited to the above-described examples. For example, for the temperature sensor 13, a sensor cover similar to the sensor cover 16 can be installed from the position near the temperature sensor 13 in the differential pressure pipe 15 to the periphery of the temperature sensor 13. The shape and position of the sensor cover can be appropriately changed according to the positional relationship between the pressure differential pipe 13 and the differential pressure pipe 15 and other conditions. In addition, although a temperature sensor, a concentration sensor, and a PM sensor (not shown) can be provided, the sensor cover of the exhaust emission control device of the present invention can be similarly applied to these other sensors.

  As described above, the exhaust purification apparatus of the present embodiment is installed in the purification material (particulate filter) 5 for purifying the exhaust gas 3 discharged from the engine 1 and the exhaust gas 3 flow path for purification. A casing 7 that holds the material 5, a differential pressure pipe 15 that is routed across the purification material 5 and includes a differential pressure sensor 14 that measures a differential pressure before and after the purification material 5, and flows through the flow path. A sensor (temperature sensor) 12 for measuring the exhaust gas 3 to be measured and a sensor cover 16 connected to the differential pressure pipe 15 and arranged around the sensor 12 so as to be simple. The sensor cover 16 can be supported by the structure, the mounting position of the sensor cover 16 can be freely selected, and the entire sensor cover 16 can be made small. Moreover, it becomes easy to set the shape and size of the sensor cover 16 so that the sensor 12 can be effectively protected with a minimum area against flying stones and the like.

  Further, in the present embodiment, the sensor cover 16 includes an attachment portion 16b that is fixed so as to be wound around the differential pressure pipe 15, a protective surface portion 16a that develops in the vicinity of the sensor 12, and a portion from the attachment portion 16b to the protective surface portion 16a. Since the mounting portion 16b, the protective surface portion 16a, and the entire supporting portion 16c are formed of a single metal plate, the structure for protecting the sensor 12 is further simplified. can do.

  Therefore, according to the present embodiment, the sensor installed in the exhaust emission control device can be suitably protected with a simple structure.

  The exhaust emission control device of the present invention is not limited to the above-described embodiment. For example, as the purifying material, various types of catalysts can be installed in addition to the particulate filter, the selective reduction catalyst, and the oxidation catalyst. In addition to the S-shaped exhaust purification device as described above, for example, the purifying material is wrapped. The present invention can be applied to an exhaust purification device having only one casing, a plurality of casings arranged in series, and various other modifications can be made without departing from the scope of the present invention. Of course.

1 Engine 3 Exhaust Gas 5 Cleaner (Particulate Filter)
7 Casing 12 Sensor (Temperature sensor)
14 differential pressure sensor 15 differential pressure pipe 16 sensor cover 16a protective surface part 16b mounting part 16c support part

Claims (2)

  A purifying material for purifying exhaust gas discharged from the engine, a casing that is installed in the exhaust gas flow path and embraces the purifying material, and is routed across the purifying material, and in the middle of the purifying material A differential pressure pipe provided with a differential pressure sensor for measuring the differential pressure before and after, a sensor for measuring exhaust gas flowing through the flow path, and connected to the differential pressure pipe, from the differential pressure pipe to the periphery of the sensor An exhaust purification device comprising a sensor cover disposed over the top.   The sensor cover includes a mounting portion that is fixed so as to be wound around the differential pressure pipe, a protective surface portion that develops in the vicinity of the sensor, and a support portion that extends from the mounting portion to the protective surface portion, 2. The exhaust emission control device according to claim 1, wherein the mounting portion, the protective surface portion, and the support portion are all formed of a single metal plate.

Images