JP2021071054A - Urea water dispersion device and mounting structure for urea water dispersion device - Google Patents

Abstract

To provide a urea water dispersion device capable of maintaining a temperature of a collision plate at a higher temperature, and a mounting structure for the urea water dispersion device.SOLUTION: A urea water dispersion device 70 that disperses urea water used for a selective reduction catalyst provided in an exhaust passage of an internal combustion engine in an exhaust pipe includes: a collision plate 71 disposed on the upstream side in the exhaust pipe 12A to disperse urea water that has been discharged from a urea water addition valve 61 and collided into the form of fine particles; a heat receiving plate 72 disposed on the downstream side in the exhaust pipe 12A and having a heat receiving surface 72A receiving heat of exhaust gas flowing in the exhaust pipe 12A; and a connecting part 73 connecting the collision plate 71 and the heat receiving plate 72 to each other. In the urea water dispersion device 70, the collision plate 71, the connecting part 73 and the heat receiving plate 72 are integrally formed of one metallic member.SELECTED DRAWING: Figure 2

Description

The present invention relates to a urea water disperser that disperses urea water used in a selective reduction catalyst provided in an exhaust path of an internal combustion engine in an exhaust pipe to atomize and homogenize it, and a mounting structure of the urea water disperser.

In vehicles equipped with an internal combustion engine, a urea SCR system is widely used in order to reduce NOx contained in exhaust gas. The urea SCR system has a selective reduction catalyst provided in the exhaust path to reduce and purify NOx, an addition valve that discharges urea water into the exhaust gas on the upstream side of the selective reduction catalyst, and fine particles of the discharged urea water. It has a urea water disperser that makes it uniform and uniform. In order to purify NOx with a selective reduction catalyst, it is essential to reform urea water into ammonia gas, and in order to efficiently reform urea water into ammonia gas, atomization is effective. Further, in order to further improve the purification efficiency of NOx with the selective reduction catalyst, uniform ammonia gas is required. In addition, the urea water dispersion device that atomizes and homogenizes the urea water discharged from the addition valve has a collision plate on the side facing the addition valve that disperses the collided urea water in all directions and atomizes and homogenizes it. I have.

For example, Patent Document 1 discloses a vaporizer (corresponding to a urea water disperser) having a tubular body and a plurality of blades (corresponding to a collision plate). The tubular body is arranged in the exhaust pipe so as to be coaxial with the exhaust pipe. Further, the plurality of blades are arranged so as to protrude radially inward in the radial direction close to the circumferential direction at the upstream edge portion of the tubular body, and to leave a passage in the central portion.

Further, for example, in Patent Document 2, an annular flange portion engaged with the inner wall of the exhaust pipe and a disk-shaped first wall structure coaxially arranged so as to be upstream of the flange portion. And a mixer (corresponding to a urea water disperser) having a conical second wall structure connecting the first wall structure and the flange portion are disclosed. The first wall structure has a triangular vane formed in a triangular shape so as to atomize and homogenize the additive (urea water), and the second wall structure has a bent vane on the downstream side. , A trapezoidal shape is formed so as to swirl the mixed gas of the exhaust gas and the additive (to make a spiral flow in the exhaust pipe), and a bent vane is formed on the downstream side.

Japanese Unexamined Patent Publication No. 2008-274941 International Publication No. 2009/131666

The temperature of the exhaust gas in the exhaust pipe of the internal combustion engine after warming up is, for example, about 200 [° C.], but the collision plate of the urea water disperser shows the operating state of the internal combustion engine, the state of the outside air, and the urea from the addition valve. The temperature fluctuates greatly depending on the discharge state of water, etc. For example, in a state after a cold start and before the completion of warm-up, in winter when the outside air temperature is low, or when urea water hits the collision plate, the temperature of the collision plate may drop significantly. Urea water is an aqueous solution of urea, and the boiling point of water is 100 [° C.], and the boiling point of urea is about 135 [° C.]. Here, when the temperature of the collision plate is in the range of 100 [° C.] to 135 [° C.], water evaporates but urea does not evaporate, so that urea may precipitate and accumulate to form a deposit. If the deposit deposited on the collision plate is peeled off, the selective reduction catalyst may be damaged.

Therefore, it is desired to suppress the precipitation of urea on the collision plate of the urea water dispersion device, and it is desired to extend the period for maintaining the temperature of the collision plate at a state higher than 135 [° C.]. That is, there is a demand for a urea water dispersion device capable of maintaining the temperature of the collision plate at a higher temperature. Although the precipitation of urea can be suppressed even if the temperature of the collision plate is less than 100 [° C.], it is not preferable to make it less than 100 [° C.] because it becomes difficult to reform the collided urea water into ammonia gas.

The vaporizer (corresponding to a urea water dispersion device) described in Patent Document 1 has a tubular body and a collision plate which is a plurality of blades arranged at an edge on the exhaust upstream side of the tubular body. There is. However, Patent Document 1 does not describe maintaining the temperature of the collision plate at a higher temperature and the structure for that purpose.

Further, the mixer (corresponding to the urea water dispersion device) described in Patent Document 2 has a flange portion, a disk-shaped first wall structure having a triangular bent portion, and a conical shape having a trapezoidal bent portion. It has a second wall structure. However, Patent Document 2 does not describe maintaining the temperature of the collision plate at a higher temperature and the structure for that purpose.

The present invention has been devised in view of these points, and provides a urea water disperser capable of maintaining the temperature of the collision plate at a higher temperature, and a mounting structure for the urea water disperser. Is the subject.

In order to solve the above problems, the first invention is a urea water dispersion device for dispersing urea water used in a selective reduction catalyst provided in an exhaust path of an internal combustion engine in an exhaust pipe, and is located upstream in the exhaust pipe. It has a collision plate that is arranged and discharged from the urea water addition valve to disperse the collided urea water into fine particles, and a heat receiving surface that is arranged on the downstream side in the exhaust pipe and receives the heat of the exhaust gas flowing in the exhaust pipe. It has a heat receiving plate, a connecting portion that connects the collision plate and the heat receiving plate, and the collision plate, the connecting portion, and the heat receiving plate are integrally molded by one metal member. , Urea water disperser.

Next, the second invention is the urea water dispersion device according to the first invention, wherein the collision plate and the heat receiving plate are each a plurality of each, and the connecting portion is in the longitudinal direction of the exhaust pipe. The divided connecting portion has a tubular shape around the axis along the axis and is divided into a plurality of divided connecting portions in the circumferential direction to form a plurality of divided connecting portions, and the divided connecting portion to which one or more of the collision plates are attached The heat receiving plate is not attached to the divided connecting portion to which one or more of the heat receiving plates are attached and the collision plate is not attached, and the collision plate and the heat receiving plate are attached. The split connecting portion is a urea water dispersion device which is an integrally molded product made of one metal member.

Next, the third invention is the urea water dispersion device according to the first invention or the second invention, in which the heat receiving surfaces are arranged so as to intersect with respect to the longitudinal direction of the exhaust pipe. It is a urea water disperser.

Next, the fourth invention is a urea water disperser according to any one of the first to third inventions, wherein the urea water disperser is a tubular connecting portion and the said. A plurality of the collision plates extending radially inward from the periphery of the upstream edge of the connecting portion in the exhaust pipe, and radially inward from the periphery of the downstream edge of the connecting portion in the exhaust pipe. When the urea water disperser is viewed from the upstream side of the exhaust pipe, the urea water disperser has a plurality of heat receiving plates extending from the gaps between the collision plates, and the heat receiving surfaces of the plurality of heat receiving plates are provided. A urea water disperser in which the relative positions of the plurality of heat receiving plates are adjusted with respect to the respective positions of the plurality of collision plates so that at least a part of the above can be seen.

Next, the fifth invention is a mounting structure of the urea water disperser for mounting the urea water disperser according to any one of the first to fourth inventions in the exhaust pipe, and is in the exhaust pipe. Is provided with a mounting claw for fixing the urea water disperser in the exhaust pipe at a position radially inward by a predetermined distance from the inner wall of the exhaust pipe, and the urea water disperser is provided with the mounting claw. It is a mounting structure of a urea water dispersion device that is mounted on the exhaust pipe and fixed at a position away from the inner wall of the exhaust pipe without directly contacting the inner wall of the exhaust pipe.

According to the first invention, since the collision plate, the connecting portion, and the heat receiving plate are integrally molded by a metal member having high thermal conductivity, the heat of the exhaust gas received by the heat receiving plate is connected. Since it can be conducted to the collision plate through the portion, the temperature of the collision plate can be maintained at a higher temperature.

According to the second invention, each of the plurality of divided connecting portions is a divided connecting portion in which a collision plate and a heat receiving plate are attached, and a divided connecting portion in which neither a collision plate nor a heat receiving plate is attached. It is said that. As a result, the connecting portion (divided connecting portion) that does not need to conduct the heat of the exhaust gas received by the heat receiving plate can be disconnected, so that the heat of the exhaust gas received by the heat receiving plate is more efficiently conducted to the collision plate. Can be made to.

According to the third invention, the heat of the exhaust gas can be received more efficiently on the heat receiving surface as compared with the case where the heat receiving surface is arranged so as to be parallel to the longitudinal direction of the exhaust pipe.

According to the fourth invention, the collision plate and the heat receiving plate can be arranged so that the flow of the exhaust gas receiving heat on the heat receiving surface is not obstructed by the collision plate. As a result, the heat of the exhaust gas can be received more efficiently on the heat receiving surface.

According to the fifth invention, since the urea water disperser is fixed at a position where it does not come into direct contact with the inner wall of the exhaust pipe, it is possible to prevent the heat of the exhaust gas received by the heat receiving plate from being conducted to the exhaust pipe and efficiently. It can be conducted to the collision plate.

It is a figure explaining the example of the structure of the internal combustion engine system provided with the urea water dispersion device of this invention. It is a perspective view explaining the structure of the exhaust pipe on the upstream side and the exhaust pipe on the downstream side at the place where the urea water dispersion device of the first embodiment is attached. It is a figure explaining the state in which the urea water dispersion device of 1st Embodiment is installed in an exhaust pipe. FIG. 3 is a sectional view taken along line IV-IV in FIG. 3, and is a diagram for explaining a state in which the urea water dispersion device of the first embodiment is installed in the exhaust pipe. This is an example of a development view of a urea water dispersion device that is integrally molded with one metal member. It is a perspective view explaining the structure of the exhaust pipe on the upstream side and the exhaust pipe on the downstream side at the place where the urea water dispersion device of the second embodiment is attached. It is a figure explaining the state in which the urea water dispersion apparatus of 2nd Embodiment is installed in an exhaust pipe.

Hereinafter, the urea water dispersion device 70 according to the present invention will be described in detail with reference to the drawings based on the embodiment. When the X-axis, Y-axis, and Z-axis are described in the drawing, the axes are orthogonal to each other, the Z-axis direction indicates the direction vertically upward, and the X-axis direction is the exhaust pipe. The longitudinal direction indicates the horizontal direction from the upstream to the downstream of the exhaust, and the Y-axis direction indicates the horizontal direction orthogonal to the Z-axis direction and the X-axis direction.

● [Overall configuration of internal combustion engine system 1 (Fig. 1)]
The overall configuration of the internal combustion engine system 1 provided with the urea water dispersion device 70 according to the present invention will be described with reference to FIG. The internal combustion engine 10 in the example of FIG. 1 is a diesel engine. Here, the internal combustion engine 10 discharges harmful substances such as particulate matter (PM), nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) together with the exhaust gas.

As shown in FIG. 1, an exhaust gas purification device 40 is provided in the exhaust passages (exhaust gas passage, exhaust gas path) 12 of the internal combustion engine 10. The exhaust gas purification device 40 includes an upstream exhaust gas purification device 41 and a downstream exhaust gas purification device 45 arranged on the downstream side of the upstream exhaust gas purification device 41. Inside the upstream exhaust gas purification device 41, a first oxidation catalyst (DOC: Diesel Oxidation Catalyst) 42 and a particulate matter removal filter (DPF: Diesel Particulate Filter) 43 are provided from the upstream side.

The first oxidation catalyst 42 is made of a cell-shaped cylinder formed of a ceramic columnar shape or the like, and a large number of through holes are formed in the axial direction thereof, and the inner surface thereof is coated with a precious metal such as platinum (Pt). There is. Then, the first oxidation catalyst 42 oxidizes and removes carbon monoxide (CO), hydrocarbons (HC) and the like contained in the exhaust gas by passing the exhaust gas through a large number of through holes at a predetermined temperature. ..

The particulate matter removal filter (hereinafter referred to as “DPF”) 43 is formed in a columnar shape or the like by a porous member made of a ceramic material or the like, and has a honeycomb structure cell shape in which a large number of small holes are provided in the axial direction. It forms a tubular body, and each small hole is closed with a sealing member at an end that is alternately different from each other. Then, the DPF 43 collects particulate matter (PM) by passing the exhaust gas flowing into each small hole from the upstream side through the porous material, and causes only the exhaust gas to flow out to the downstream side through the adjacent small hole. ..

A fuel addition valve 28 and an exhaust temperature detection device 36A (for example, an exhaust temperature sensor) are provided on the upstream side of the first oxidation catalyst 42 (upstream side of the upstream exhaust gas purification device 41). The fuel addition valve 28 is a fuel for raising the temperature of the exhaust gas by reacting with the exhaust gas in the first oxidation catalyst 42 when the DPF 43 in which fine particles are deposited is regenerated (when the particulate matter is burned and incinerated). Is injected. Further, an exhaust temperature detection device 36B (for example, an exhaust temperature sensor) is provided on the downstream side of the first oxidation catalyst 42 and on the upstream side of the DPF 43.

An exhaust temperature detection device 36C (for example, an exhaust temperature sensor) is provided on the downstream side of the DPF 43. Further, in the upstream exhaust gas purification device 41, the exhaust pressure on the downstream side of the first oxidation catalyst 42 and on the upstream side of the DPF 43 (corresponding to the pressure in the exhaust pipe) and the pressure in the exhaust pipe on the downstream side of the DPF 43. A differential pressure sensor 35 for detecting the differential pressure (pressure difference) is provided.

Further, the downstream exhaust gas purification device 45 arranged on the downstream side of the upstream exhaust gas purification device 41 has a urea water addition valve (reducing agent addition valve) 61, a urea water dispersion device 70, and a selective reduction catalyst from the upstream side. (SCR: Selective Catalytic Reduction) 46 and a second oxidation catalyst 47 are provided. The selective reduction catalyst (hereinafter referred to as “SCR”) 46 is connected to the downstream side of the DPF 43 via an exhaust pipe 12A. The urea water addition valve 61 is arranged on the downstream side of the DPF 43 of the exhaust pipe 12A and on the upstream side of the urea water dispersion device 70 and the SCR46, and is arranged every predetermined time (for example, 200 ms to 400 ms). Urea water (reducing agent solution) is added (discharged) to the exhaust gas toward the urea water dispersion device 70. Further, the exhaust pipe 12A is provided with a NOx sensor 37A on the upstream side of the urea water addition valve 61.

The second oxidation catalyst 47 is connected to the downstream side of the SCR 46 via an exhaust pipe 12B. The exhaust pipe 12B is provided with an exhaust temperature detection device (catalyst temperature detection device) 36D (for example, an exhaust temperature sensor) on the downstream side of the SCR46. Further, the exhaust pipe 12B is provided with a NOx sensor 37B on the downstream side of the exhaust temperature detection device 36D. Each of the NOx sensors 37A and 37B outputs a detection signal according to the NOx concentration in the exhaust gas.

The urea water addition valve 61 is connected to the urea water tank (reducing agent tank) 65 via the supply pipe 62 and the urea water pump 63. The urea water pump 63 is an electric pump that is rotationally driven by a drive signal from the control device (ECU) 50, and can rotate in either the forward or reverse direction. The forward rotation of the urea water pump 63 sucks up the urea water (reducing agent solution) 67 in the urea water tank 65, and the urea water 67 is supplied to the urea water addition valve 61 via the supply pipe 62. Further, the urea water 67 in the supply pipe 62 is sucked back by the reverse rotation of the urea water pump 63, and flows into the urea water tank 65. The supply pipe 62 may be provided with a water pressure sensor that detects the pressure of the urea water 67 in the supply pipe 62.

The urea water tank 65 is provided with a level gauge (remaining amount detecting device) 68 for detecting the remaining amount (water level) of the urea water 67 stored in the urea water tank 65. The level gauge (remaining amount detecting device) 68 outputs a signal to the control device (ECU) 50 according to the remaining amount of the urea water 67 in the urea water tank 65 reduced from the full tank (for example, 13 liters). To do. Further, in the urea water tank 65, a concentration sensor 69 for detecting the concentration of the urea water 67 stored in the urea water tank 65 is provided. The concentration sensor (concentration detection device) 69 outputs a signal corresponding to the concentration of the urea water 67 in the urea water tank 65 to the control device (ECU) 50.

The urea water dispersion device 70 is arranged between the urea water addition valve 61 and the SCR46, and has a collision plate 71 (see FIGS. 2 and 4) with which the urea water discharged from the urea water addition valve 61 collides. Then, the urea water that has collided with the collision plate 71 is uniformly dispersed in the exhaust pipe and atomized. The atomized urea water is reformed into ammonia gas by the heat of the exhaust gas, mixed in the exhaust gas so as to be uniform, and reaches SCR46.

SCR46 is a catalyst that detoxifies nitrogen oxides (NOx) by using urea water (reducing agent solution) added by the urea water addition valve 61. Specifically, the urea water added (injected) from the urea water addition valve 61 is hydrolyzed by the exhaust heat of the exhaust gas, and at that time, ammonia (NH ₃ ) is generated by the reaction represented by the following formula (1). Will be done.
(NH ₂ ) ₂ CO + H ₂ O → 2 NH ₃ + CO ₂ ... (1)

Then, when the exhaust gas passes through the SCR46, the nitrogen oxides (NOx) in the exhaust gas are selectively reduced and purified by the ammonia adsorbed on the SCR46. At that time, NOx is reduced and purified by performing a reduction reaction as shown in the following formulas (2) to (4).
4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O ・ ・ ・ (2)
6NO ₂ + 8NH ₃ → 7N ₂ + 12H ₂ O ・ ・ ・ (3)
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O ・ ・ ・ (4)

When NOx is reduced and purified by the ammonia represented by the above formulas (2) to (4), if the ammonia cannot completely react with the NOx and becomes surplus, the surplus ammonia passes through the exhaust pipe 12B on the downstream side of the SCR46. It flows into the second oxidation catalyst 47. In such a case, the second oxidation catalyst 47 oxidizes and removes the excess ammonia that has flowed in.

The fuel addition valve 28, the urea water addition valve 61, and the urea water pump 63 are driven by a control signal from the control device (ECU: Electronic Control Unit) 50. The control device 50 is a known one including a CPU, RAM, ROM, timer, EEPROM and the like. The CPU executes various arithmetic processes based on various programs and maps stored in the ROM. Further, the RAM temporarily stores the calculation result of the CPU, the data input from each detection device, and the like, and the EEPROM stores, for example, the data to be saved when the internal combustion engine 10 is stopped.

Further, the exhaust temperature detection device 36A outputs a detection signal according to the temperature of the exhaust gas in the exhaust pipe on the upstream side of the first oxidation catalyst 42 to the control device 50. Further, the exhaust temperature detection device 36B outputs a detection signal according to the temperature of the exhaust gas flowing on the downstream side of the first oxidation catalyst 42 and the upstream side of the DPF 43 to the control device 50. Further, the exhaust temperature detection device 36C outputs a detection signal according to the temperature of the exhaust gas on the downstream side of the DPF 43 and the upstream side of the SCR 46 to the control device 50. Further, the exhaust temperature detection device 36D outputs a detection signal according to the temperature of the exhaust gas on the downstream side of the SCR 46 and the upstream side of the second oxidation catalyst 47 to the control device 50.

The differential pressure sensor 35 detects the exhaust pressure on the downstream side of the first oxidation catalyst 42 and on the upstream side of the DPF 43 (corresponding to the pressure inside the exhaust pipe) and the pressure inside the exhaust pipe on the downstream side of the DPF 43 according to the differential pressure. The signal is output to the control device 50. The NOx sensor 37A outputs a detection signal according to the NOx concentration of the exhaust gas on the upstream side of the urea water addition valve 61 to the control device 50. The NOx sensor 37B outputs a detection signal according to the NOx concentration of the exhaust gas on the downstream side of the SCR 46 and the upstream side of the second oxidation catalyst 47 to the control device 50.

The control device 50 includes a detection signal of the intake air flow rate detection device 31 (for example, an air flow meter) provided in the intake passage 11, a detection signal of the accelerator opening degree detection device 33, and a detection signal of the rotation detection device 34. It has been entered. Further, the control device 50 includes the detection signals of the exhaust temperature detection devices 36A, 36B, 36C and 36D described above, the detection signals of the differential pressure sensor 35, the detection signals of the NOx sensors 37A and 37B, the level gauge 68 and the concentration sensor. 69 detection signals are input.

Then, the control device 50 can detect the operating state of the internal combustion engine 10 based on these input detection signals. Further, the control device 50 receives the detected operating state of the internal combustion engine 10 and the request from the driver based on the detection signal from the accelerator opening degree detecting device 33, and the cylinders of the internal combustion engine 10 from the injectors 14A to 14D. A control signal for controlling the amount of fuel injected into the engine, the amount of unburned fuel added (injected) from the fuel addition valve 28, and the amount of urea water added (injected) from the urea water addition valve 61 is output.

Then, the control device 50 (corresponding to the flow rate related amount detecting device) determines the fuel consumption (g / s) per second injected from each injector 14A to 14D every predetermined time (for example, about 10 msec to 100 msec). Calculate and store in RAM in chronological order. Further, the control device 50 (corresponding to the differential pressure detecting device) calculates the differential pressure (pressure difference) from the detection signal input from the differential pressure sensor 35 every predetermined time (for example, about 10 msec to 100 msec). , Stored in RAM in chronological order.

The fuel injected into the exhaust gas from the fuel addition valve 28 is burned by an oxidation reaction with oxygen remaining in the exhaust gas by the first oxidation catalyst 42, and the exhaust gas temperature rises due to the heat generation. When the floor temperature of the DPF43 rises due to the high temperature exhaust gas and reaches a predetermined temperature or higher (for example, 590 ° C. or higher), the particulate matter (PM) deposited in the DPF43 is burned and incinerated. By maintaining such a state for a predetermined time, the particulate matter (PM) deposited in the DPF43 is burned and removed, and the particulate matter (PM) in the exhaust gas is collected. The function can be restored (regenerated).

The intake air flow rate detection device 31 (for example, an intake air flow rate sensor) is provided in the intake passage 11 of the internal combustion engine 10 and outputs a detection signal according to the flow rate of the air sucked by the internal combustion engine 10 to the control device 50. The accelerator opening degree detecting device 33 (for example, the accelerator opening degree sensor) outputs a detection signal according to the opening degree of the accelerator operated by the driver (that is, the load requested by the driver) to the control device 50. The rotation detection device 34 (for example, a rotation sensor) outputs a detection signal corresponding to the rotation speed of the crankshaft of the internal combustion engine 10 (that is, the engine rotation speed) to the control device 50, for example.

● [Urea water dispersion device 70A of the first embodiment (FIGS. 2 to 5)]
Next, the details of the urea water dispersion device 70A, which is the first embodiment of the urea water dispersion device 70 shown in FIG. 1, will be described with reference to FIGS. 2 to 5. In the urea water dispersion device 70A of the first embodiment, the connecting portion 73 is not divided (see FIG. 2). FIG. 2 shows an exploded perspective view of the upstream exhaust pipe 12AU in the exhaust pipe 12A, the downstream exhaust pipe 12AL in the exhaust pipe 12A, and the urea water dispersion device 70A. Further, FIG. 3 (FIG. III-III is a cross-sectional view of FIG. 4) shows exhaust gas with the urea water disperser 70A attached at a position between the upstream exhaust pipe 12AU and the downstream exhaust pipe 12AL shown in FIG. It is a figure which looked at the urea water disperser 70A from the upstream side. FIG. 4 is a sectional view taken along line IV-IV in FIG.

● [Overall structure of urea water dispersion device 70A (FIGS. 2 to 5)]
As shown in FIGS. 2 to 4, the urea water dispersion device 70A of the first embodiment includes a collision plate 71, a heat receiving plate 72, and a connecting portion 73 connecting the collision plate 71 and the heat receiving plate 72. have. It should be noted that the number of the collision plate 71 and the heat receiving plate 72 may be one or more, and in the present embodiment, an example in which the collision plate 71 and the heat receiving plate 72 are each three will be described.

The collision plate 71 has a collision region 71A (see FIG. 2) with which the urea water 67A (see FIG. 4) discharged substantially linearly from the urea water addition valve 61 collides, and is arranged on the upstream side in the exhaust pipe 12A. Then, the urea water 67A (see FIG. 4) discharged from the urea water addition valve 61 and colliding with the collision region 71A is dispersed in the form of fine particles. Further, the plurality of collision plates 71 extend radially inward from the periphery of the upstream edge portion of the tubular connecting portion 73 in the exhaust pipe 12A. The collision region 71A is provided so as to correspond to the injection hole provided in the urea water addition valve 61. In the present embodiment, the injection holes of the urea water addition valve 61 show three examples, and the collision region 71A shows three examples.

The heat receiving plate 72 is arranged on the downstream side in the exhaust pipe 12A and has a heat receiving surface 72A that receives (absorbs heat) the heat of the exhaust gas flowing in the exhaust pipe 12A. Further, the plurality of heat receiving plates 72 extend radially inward from the periphery of the downstream edge portion of the tubular connecting portion 73 in the exhaust pipe 12A. At least a part of the heat receiving surface 72A is arranged so as to intersect the longitudinal direction of the exhaust pipe 12A (that is, the direction in which the exhaust gas flows in the exhaust pipe 12A), not parallel to each other. As a result, as compared with the case where the heat receiving surface is arranged so as to be parallel to the longitudinal direction of the exhaust pipe 12A, the exhaust gas is more likely to hit the heat receiving surface, and more heat can be received from the exhaust gas. The longitudinal direction of the exhaust pipe 12A is a direction parallel to the central axis 12AJ of the exhaust pipe 12A.

The connecting portion 73 has a tubular shape substantially coaxial with the exhaust pipe 12A, and connects the plurality of collision plates 71 and the plurality of heat receiving plates 72. The connecting portion 73 has a tubular shape around the axis (around the central axis 12AJ) along the longitudinal direction of the exhaust pipe 12A.

The urea aqueous dispersion device 70A is manufactured as an integrally molded product by, for example, bending and bending one member having the shape shown in the developed view of FIG. The urea water disperser 70A is, for example, an integrally molded product made of one metal member (a metal plate in the shape of the developed view of FIG. 5) which is durable against the temperature of exhaust gas and has a relatively high thermal conductivity. It is said that. Since the urea water dispersion device 70A is an integrally molded metal product having high thermal conductivity, the heat of the exhaust gas received by the heat receiving plate 72 is transferred to the collision plate 71 via the connecting portion 73, and the heat of the collision plate 71 is transferred to the collision plate 71. The temperature can be maintained at a higher temperature. Although FIG. 5 shows an example in which the heat receiving plate 72 is formed by bending, a notch may be made in the region of the connecting portion 73 and the heat receiving plate 72 may be formed by cutting and raising.

Further, as shown in FIG. 3, when the urea water dispersion device 70A is viewed from the upstream side of the exhaust pipe 12A, at least a part of each heat receiving surface 72A of the plurality of heat receiving plates 72 is formed through the gaps between the plurality of collision plates 71. As can be seen, the relative positions of the plurality of heat receiving plates 72 with respect to the respective positions of the plurality of collision plates 71 are adjusted. That is, in FIG. 3, the position of the heat receiving plate 72 with respect to the position of the collision plate 71 is adjusted (the position is set so as not to overlap) so that the entire heat receiving plate 72 is not covered by the collision plate 71. As a result, the heat receiving plate 72 can receive the heat of the exhaust gas more efficiently.

● [Mounting structure of urea water dispersion device 70A in the exhaust pipe 12A (FIGS. 2 to 4)]
Next, with reference to FIGS. 2 to 4, a mounting structure and the like for mounting the urea water dispersion device 70A in the exhaust pipe 12A will be described. As shown in FIG. 2, the exhaust pipe 12A is divided into an upstream side exhaust pipe 12AU and a downstream side exhaust pipe 12AL at a position where the urea water dispersion device 70A is attached. A urea water dispersion device 70A is attached to the boundary between the upstream exhaust pipe 12AU and the downstream exhaust pipe 12AL.

As shown in FIGS. 3 and 4, the downstream exhaust pipe 12AL (exhaust pipe 12A) is located at a position radially inward by a predetermined distance L1 from the inner wall of the downstream exhaust pipe 12AL (exhaust pipe 12A). A mounting claw 12AT for fixing the urea water dispersion device 70A is provided in the exhaust pipe 12A. The mounting claw 12AT is provided so as to extend from the upstream end of the downstream exhaust pipe 12AL toward the upstream side. Then, as shown in FIGS. 3 and 4, the urea water dispersion device 70A is attached to the mounting claw 12AT and fixed at a position away from the inner wall of the exhaust pipe 12A without directly contacting the inner wall of the exhaust pipe 12A. There is.

As shown in FIG. 4, the mounting claw 12AT and the urea water dispersion device 70A (connecting portion 73) are welded and fixed at the welded portion W1. The upstream exhaust pipe 12AU and the downstream exhaust pipe 12AL are welded at the welded portion W2 so as to be continuous in the circumferential direction. Since the thermal conductivity of the welded portions W1 and W2 is low, in FIG. 4, the heat received from the exhaust gas by the heat receiving plate 72 of the integrally molded urea water dispersion device 70A is almost transferred from the welded portion W1 to the mounting claw 12AT. Instead, it is transmitted from the connecting portion 73 to the collision plate 71. Therefore, the heat received by the heat receiving plate 72 can be efficiently transferred to the collision plate 71 without being released to the exhaust pipe 12A.

Further, since the urea water dispersion device 70A is fixed to the mounting claw 12AT radially inward by a predetermined distance L1 from the inner wall of the exhaust pipe 12A, as shown in FIGS. 3 and 4, the inner wall surface of the exhaust pipe 12A and the inner wall surface of the exhaust pipe 12A A space K1 around the disperser, which is a space having a predetermined distance L1, is formed between the urea water disperser 70A and the outer peripheral surface. As a result, the high-temperature exhaust gas also flows in the space K1 around the disperser, and the urea water disperser 70A can be wrapped with the high-temperature exhaust gas, so that the urea water disperser 70A (that is, the collision plate 71) is heated to a higher temperature. Can be maintained.

● [Urea water dispersion device 70B of the second embodiment (FIGS. 6 and 7)]
Next, the details of the urea water dispersion device 70B, which is the second embodiment of the urea water dispersion device 70 shown in FIG. 1, will be described with reference to FIGS. 6 and 7. The urea water dispersion device 70B of the second embodiment is different from the first embodiment in that the connecting portion 73B is divided into a plurality of divided connecting portions 73C to 73F (see FIG. 7). The points are the same as those in the first embodiment. Hereinafter, the differences from the first embodiment will be mainly described, and the same points will be omitted. FIG. 6 shows an exploded perspective view of the upstream exhaust pipe 12AU in the exhaust pipe 12A, the downstream exhaust pipe 12AL in the exhaust pipe 12A, and the urea water dispersion device 70B. Further, FIG. 7 is a view of the urea water disperser 70A viewed from the exhaust upstream side in a state where the urea water disperser 70B is attached at a position between the upstream exhaust pipe 12AU and the downstream exhaust pipe 12AL shown in FIG. Is.

● [Overall structure of urea water dispersion device 70B (FIGS. 6 and 7)]
As shown in FIGS. 6 and 7, the urea water dispersion device 70B of the second embodiment includes a collision plate 71, a heat receiving plate 72, and a connecting portion 73B connecting the collision plate 71 and the heat receiving plate 72. have. It should be noted that the number of the collision plate 71 and the heat receiving plate 72 may be one or more, and in the present embodiment, an example in which the collision plate 71 and the heat receiving plate are each three will be described.

The collision plate 71 has a collision region 71A and disperses the collision urea water 67A (see FIG. 4) in the form of fine particles. Since the collision plate 71 and the collision area 71A are the same as those in the first embodiment, the description thereof will be omitted.

The heat receiving plate 72 has a heat receiving surface 72A, receives the heat of the exhaust gas, and transfers the received heat to the collision plate 71 via the connecting portion 73B. Since the heat receiving plate 72 and the heat receiving surface 72A are the same as those in the first embodiment, the description thereof will be omitted.

The connecting portion 73B has a tubular shape around the axis (around the central axis 12AJ) along the longitudinal direction of the exhaust pipe 12A, and is divided into a plurality of divided connecting portions in the circumferential direction. In the examples shown in FIGS. 6 and 7, an example of division into the divided connecting portions 73C to 73F is shown. As shown in FIG. 7, a division gap 73Z is provided between adjacent division connection portions.

One or more heat receiving plates 72 are attached to the split connecting portion to which one or more collision plates 71 are attached, and the heat receiving plate 72 is attached to the divided connecting portion to which no collision plate 71 is attached. Is not installed at all. In the examples shown in FIGS. 6 and 7, two collision plates 71 and two heat receiving plates 72 are attached to the split connecting portion 73C, and one collision plate 71 and one heat receiving plate 72 are attached to the split connecting portion 73E. Is attached, and neither the collision plate 71 nor the heat receiving plate 72 is attached to the split connecting portions 73D and 73F. The split connecting portions 73C and 73E to which the collision plate 71 and the heat receiving plate 72 are attached are integrally molded by one metal member.

With the above structure, in the connecting portion 73B, the divided connecting portions 73D and 73F, which are portions that do not contribute to the conduction of heat from the heat receiving plate 72 to the collision plate 71, can be separated. Therefore, the heat received from the exhaust gas by the heat receiving plate 72 can be efficiently transferred to the collision plate 71 without being transmitted to the unnecessary divided connecting portions 73D and 73F.

The urea water disperser and the mounting structure of the urea water disperser of the present invention are not limited to the configuration, shape, structure and the like described in the present embodiment, and various modifications and additions are made without changing the gist of the present invention. It can be deleted. For example, the number of collision plates 71 and the number of heat receiving plates 72 may be one or more, respectively, and are not limited to three. The number of collision plates 71 and the number of heat receiving plates 72 are not the same. You may. Further, the shape and size of the collision plate 71, the shape and size (relative size) of the heat receiving plate 72, and the like are not limited to the shape and size shown in the present embodiment. Further, the material of the urea water dispersion device is not particularly limited as long as it is a metal (including an alloy) having durability against the temperature of the exhaust gas and having a relatively high thermal conductivity.

The urea water disperser and the mounting structure of the urea water disperser described in the present embodiment can be applied to various uses and internal combustion engines of various fuels such as general vehicles, industrial vehicles, and power generation systems.

The numerical values used in the description of the present embodiment are examples, and are not limited to these numerical values. Further, when the above (≧), the following (≦), the larger (>), the less than (<), etc. are described, the equal sign may or may not be included.

1 Internal combustion engine system 10 Internal combustion engine 12 Exhaust passage 12A, 12B Exhaust pipe 12AJ Central axis 12AL Downstream exhaust pipe 12AU Upstream exhaust pipe 12AT Mounting claw 28 Fuel addition valve 36A to 36D Exhaust temperature detector 37A, 37B NOx sensor 40 Exhaust gas Purification device 41 Upstream exhaust gas purification device 42 First oxidation catalyst 43 Particulate substance removal filter (DPF)
45 Downstream exhaust gas purification device 46 SCR (selective reduction catalyst)
47 Second oxidation catalyst 50 Control device 61 Urea water addition valve 65 Urea water tank 67, 67A Urea water 68 Level gauge 69 Concentration sensor 70, 70A, 70B Urea water disperser 71 Collision plate 71A Collision area 72 Heat receiving plate 72A Heat receiving surface 73 , 73B Connecting part 73C to 73F Divided connecting part 73Z Dividing gap K1 Disperser peripheral space L1 Predetermined distance W1, W2 Welded part

Claims (5)

A urea water dispersion device that disperses urea water used in a selective reduction catalyst provided in the exhaust path of an internal combustion engine in an exhaust pipe.
A collision plate arranged on the upstream side in the exhaust pipe and discharging the urea water discharged from the urea water addition valve to disperse the collisional urea water into fine particles, and a collision plate.
A heat receiving plate arranged on the downstream side in the exhaust pipe and having a heat receiving surface for receiving the heat of the exhaust gas flowing in the exhaust pipe,
A connecting portion that connects the collision plate and the heat receiving plate,
Have,
The collision plate, the connecting portion, and the heat receiving plate are integrally molded by one metal member.
Urea water disperser. The urea water dispersion device according to claim 1.
There are a plurality of the collision plate and the heat receiving plate, respectively.
The connecting portion has a tubular shape around the axis along the longitudinal direction of the exhaust pipe, and is divided into a plurality of parts in the circumferential direction to form a plurality of divided connecting portions.
One or more of the heat receiving plates are attached to the divided connecting portion to which the one or more of the collision plates are attached.
The heat receiving plate is not attached to the split connecting portion to which the collision plate is not attached.
The split connecting portion to which the collision plate and the heat receiving plate are attached is made of one metal member and is integrally molded.
Urea water disperser. The urea water dispersion device according to claim 1 or 2.
The heat receiving surfaces are arranged so as to intersect the longitudinal direction of the exhaust pipe.
Urea water disperser. The urea water dispersion device according to any one of claims 1 to 3.
The urea water disperser is
With the tubular connecting part,
A plurality of the collision plates extending inward in the radial direction from the periphery of the upstream edge portion of the connecting portion in the exhaust pipe.
A plurality of heat receiving plates extending inward in the radial direction from the periphery of the downstream edge of the connecting portion in the exhaust pipe.
Have,
When the urea water dispersion device is viewed from the upstream side of the exhaust pipe, the plurality of collisions are made so that at least a part of each of the heat receiving surfaces of the plurality of heat receiving plates can be seen from the gaps between the plurality of collision plates. The relative positions of the plurality of heat receiving plates with respect to the respective positions of the plates are adjusted.
Urea water disperser. A mounting structure for a urea water dispersion device for mounting the urea water dispersion device according to any one of claims 1 to 4 in an exhaust pipe.
Inside the exhaust pipe, a mounting claw for fixing the urea water dispersion device is provided in the exhaust pipe at a position radially inward by a predetermined distance from the inner wall of the exhaust pipe.
The urea water dispersion device is attached to the mounting claw and fixed at a position away from the inner wall of the exhaust pipe without directly contacting the inner wall of the exhaust pipe.
Mounting structure of urea water disperser.

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