JP4901545B2 - Exhaust purification device - Google Patents

Description

  The present invention relates to an exhaust emission control device that reduces and removes nitrogen oxides (NOx) in engine exhaust using a liquid reducing agent or a precursor thereof.

  A liquid reducing agent or its precursor is injected and supplied upstream of the exhaust of the NOx reduction catalyst installed in the engine exhaust pipe, and the NOx and the reducing agent in the exhaust are subjected to a catalytic reduction reaction to purify NOx into harmless components. There has been proposed an exhaust emission control device. In such an exhaust purification device, the liquid reducing agent stored in the reducing agent tank or a precursor thereof is distributed to the exhaust pipe via a pump module that sucks and pumps the reducing agent and an addition module that controls the injection flow rate. It is supplied to the injection nozzle provided, and is supplied by injection upstream of the exhaust of the NOx reduction catalyst.

Each element which comprises these exhaust gas purification apparatuses is arrange | positioned at a vehicle by the layout as shown, for example in Unexamined-Japanese-Patent No. 2006-123717 (patent document 1). In particular, the pump module of the exhaust purification device (located in the reducing agent supply device in Patent Document 1) needs to be replaced with a built-in filter. The exhaust pipe and other parts are often located in
JP 2006-123717 A

  When the filter of the pump module is replaced, dripping of the liquid reducing agent or its precursor is unavoidable. However, in the case of the above-described conventional layout, the dripped liquid reducing agent or its liquid is added to the parts laid out under the pump module. Precursors can be deposited. If the attached liquid reducing agent or its precursor is dried and the solute is precipitated in a crystalline form, the appearance will deteriorate, so it should be improved.

  The present invention has been made in view of such a background, and proposes an exhaust emission control device in which a liquid reducing agent or a precursor thereof dripping when a filter of a pump module is replaced does not affect a lower part. .

To achieve the above object, according to the first aspect of the present invention, the exhaust purification device includes a reduction catalyst disposed in the engine exhaust pipe, and a nozzle that injects a liquid reducing agent or a precursor thereof upstream of the reduction catalyst. A pump module that is located above the heat source component and sucks and pumps the liquid reducing agent or its precursor stored in the reducing agent tank, and the injection flow rate of the liquid reducing agent or its precursor pumped from the pump module. It is characterized by including an addition module that is controlled and sent to the nozzle, and a reducing agent tray that is installed between the pump module and the heat source component, and whose entire bottom wall is inclined .

The invention according to claim 2 further includes a sensor which is provided at a predetermined position of the reducing agent tray and is used for detecting the liquid reducing agent or its precursor and issuing an alarm.
In a third aspect of the present invention, the reducing agent tray is characterized in that a drain pipe is connected to a bottom wall.
According to a fourth aspect of the present invention, the reducing agent tray has a bottom wall that is inclined toward a drain hole communicating with the drain pipe.

  According to a fifth aspect of the present invention, the reducing agent tray is characterized in that a drain member having a U-shaped cross section in which a groove communicating with the drainage hole on the side wall is connected to the side wall.

According to the first aspect of the present invention, since the reducing agent tray is installed below the pump module, the reducing agent tray receives the liquid reducing agent or its precursor dripped at the time of filter replacement. Can be prevented from adhering to the parts located below. In addition, the reducing agent tray acts as a shield for receiving hot air rising from a heat source component heat source such as an exhaust pipe located below the pump module, and can suppress an increase in temperature of the pump module.

According to the second aspect of the present invention, since the liquid reducing agent or its precursor leaking into the reducing agent receiving tray can be detected by the sensor other than when the filter is replaced, a liquid leakage alarm is issued to inform the user. be able to. .
According to the third aspect of the invention, by connecting the drain pipe to the bottom wall, the liquid reducing agent or its precursor that has been deposited on the reducing agent tray is guided to the place where there are no parts below by the drain pipe and discharged. be able to.

According to the fourth aspect of the present invention, the bottom wall is inclined toward the drainage hole, for example, a funnel shape, thereby facilitating the discharge of the liquid reducing agent or the precursor thereof, and the exhaust pipe below. When a heat source component such as the above is located, the inclined low wall acts as a streamlined shield for receiving hot air rising from the heat source, and the temperature rise of the pump module can be suppressed.
According to the invention of claim 5, the drain member connected to the side wall can discharge the liquid reducing agent or its precursor leaning on the reducing agent tray to a place where there are no parts below, and further, Since the drain member has a U-shaped cross section of the upper opening forming the groove, it can be easily cleaned when the groove is clogged with dust or the like.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows the overall configuration of an exhaust purification device that uses an aqueous urea solution as a precursor of a liquid reducing agent to reduce and purify NOx in engine exhaust.
A nitrogen oxidation catalyst 16 that oxidizes nitrogen monoxide (NO) to nitrogen dioxide (NO ₂ ) and an aqueous urea solution are injected along the exhaust circulation direction into the exhaust pipe 14 connected to the exhaust manifold 12 of the engine 10. An injection nozzle 18 for supplying, an NOx reduction catalyst 20 for reducing and purifying NOx using ammonia obtained by hydrolyzing a urea aqueous solution, and an ammonia oxidation catalyst 22 for oxidizing ammonia that has passed through the NOx reduction catalyst 20 Each is arranged. On the other hand, the urea aqueous solution stored in the reducing agent tank 24 is supplied to the injection nozzle 18 via the pump module 26 that sucks and pressure-feeds the urea aqueous solution and the addition module 28 that controls the injection flow rate.

  The pump module 26 is provided with an ECU (electronic control unit) 30, and a signal indicating an engine operating state is input from an engine ECU 32 that performs various controls of the engine 10 via a CAN (Controller Area Network) or the like. . The ECU 30 controls the pump module 26 and the addition module 28 in accordance with the input signal, and executes an appropriate urea aqueous solution injection supply from the injection nozzle 18.

In such an exhaust purification device, the urea aqueous solution injected and supplied from the injection nozzle 18 is hydrolyzed using water vapor in the exhaust and exhaust and converted to ammonia. It is known that the converted ammonia reacts with NOx in the exhaust gas in the NOx reduction catalyst 20 and is converted into water (H ₂ O) and nitrogen (N ₂ ). At this time, in order to improve the NOx purification efficiency in the NOx reduction catalyst 20, NO by the nitrogen oxidation catalyst 16 is oxidized to NO _2, it is improved in that the ratio between NO and NO ₂ in the exhaust gas suitable for reduction The On the other hand, the ammonia that has passed through the NOx reduction catalyst 20 is oxidized by the ammonia oxidation catalyst 22 disposed downstream of the exhaust gas, so that ammonia is prevented from being released into the atmosphere as it is.

2 to 4 show the pump module 26 in a state assembled to the frame F of the vehicle, and the reducing agent tray 40 installed therebelow.
A reservoir tank RT assembled to the frame F by a frame member is located below the reducing agent tray 40, and an exhaust pipe 14 is also located below the reservoir tank RT.
Reducing agent pan 40 includes stainless steel having corrosion resistance against the urea aqueous solution, a bottom wall 41, and side walls 42, 43 formed by bending both side portions of the bottom wall 41 upwardly, the. Further, the base end portion 44 on the frame F side and the tip end portion (free end portion) 45 on the opposite side are also bent upward to form a flange portion. The base end portions of the side walls 42 and 43 are fixed wall portions bent inward, and are fixed to the frame F by bolts 46.

A portion near the tip of the bottom wall 41 is supported by two fixed columns 47 erected from a frame member in which the reservoir tank RT is assembled. It is fixed. By supporting from below with the fixed pillar 47, the bottom wall 41 is made to be a downward slope toward the base end portion 44 on the frame F side. A drain pipe 49 is connected to the vicinity of the base end portion 44, and a drain hole 49 ′ communicating with the drain pipe 49 opens in the bottom wall 41. The drain pipe 49 extends from the bottom wall 41 and bends in the middle, and extends downward to a place where the reservoir tank RT and the exhaust pipe 14 are not present.

  The urea aqueous solution dripping at the time of replacing the filter of the pump module 26 is received by the reducing agent tray 40, and is led down to the place where there are no parts through the drain pipe 49 and discharged. Therefore, adhesion to the reservoir tank RT and the exhaust pipe 14 located below is prevented. In addition, when a heat source component such as the exhaust pipe 14 is positioned below, the reducing agent tray 40 acts as a shield for receiving the hot air rising from the heat source, thereby suppressing the temperature rise of the pump module 26. it can.

In the above, the reducing agent tray 40 provided with the drain pipe 49 is shown, but the drain pipe 49 may be omitted. In this case, it is necessary to wash the reducing agent tray 40 with water after filter replacement. Further, as shown by dotted lines in FIGS. 2 and 3, it is possible to add a cover functioning as a windshield or the like on the side wall 42 of the reducing agent tray 40.
5 to 7 show application examples of the reducing agent tray.

  The example shown in FIG. 5 is an example in which the reducing agent tray 40 is provided with a sensor 50 used for detecting an aqueous urea solution and giving an alarm. In the illustrated case, the sensor 50 is installed in the drain pipe 49. By providing the sensor 50, it is possible to detect the urea aqueous solution that has leaked to the reducing agent tray 40 at times other than when the filter is replaced, so that a liquid leak alarm can be issued to notify the user. The installation position of the sensor 50 is not limited to the drain pipe 49 and may be installed in the vicinity of the drainage hole 49 ′ on the upper surface of the bottom wall 41.

  In the example shown in FIG. 6, a drain member 51 having a U-shaped cross section with an opening at the top is connected to the side wall 43 (or 42), and a drainage groove by the drain member 51 is opened in the side wall 43. This is an example of communication with the liquid hole 51 ′. In the case of this example, the urea aqueous solution dripping on the bottom wall 41 is guided and discharged by the groove of the drain member 51 to the place where there is no part below. Since the drain member 51 has a substantially U-shaped cross section with an open top, the drain member 51 can be easily cleaned when the groove of the drain member 51 is clogged with dust or the like.

The example shown in FIG. 7 is an example in which the bottom wall 41 is inclined downward toward the drain hole 49 ′. In the case of the illustrated example, the drainage hole 49 ′ is provided in the central portion of the bottom wall 41, so that the bottom wall 41 is formed in a funnel shape, and the drain tube 49 is connected to the bottom of the funnel shape. According to this example, when the drained liquid reducing agent or its precursor is expelled, and the heat source component such as the exhaust pipe 14 is positioned below, the bottom wall 41 having a funnel shape is the heat source. It acts as a streamline shield that receives the hot air rising from the bottom as indicated by arrows, and the temperature rise of the pump module 26 can be suppressed. The inclined shape of the bottom wall 41 is not limited to a funnel shape, and may be various other shapes such as a triangular pyramid having a lower portion as a vertex.

1 is a configuration diagram of an exhaust purification device according to the present invention. The perspective view which showed arrangement | positioning of a pump module and a reducing agent receptacle. The side view which showed arrangement | positioning of a pump module and a reducing agent receptacle. The front view which showed arrangement | positioning of a pump module and a reducing agent receptacle. Explanatory drawing which showed the 1st application example of the reducing agent saucer. Explanatory drawing which showed the 2nd application example of the reducing agent saucer. Explanatory drawing which showed the 3rd application example of the reducing agent saucer.

Explanation of symbols

26 Pump module 40 Reductant tray 41 Bottom wall 42, 43 Side wall 49 Drain pipe 49 'drain hole 50 Sensor 51 Drain member 51' drain hole

Claims (5)

A reduction catalyst disposed in the engine exhaust pipe;
A nozzle for injecting a liquid reducing agent or a precursor thereof upstream of the exhaust of the reduction catalyst;
A pump module that is located above the heat source component and sucks and pumps the liquid reducing agent or its precursor stored in the reducing agent tank;
An addition module for controlling the injection flow rate of the liquid reducing agent or its precursor pumped from the pump module and sending it to the nozzle;
A reducing agent tray installed between the pump module and the heat source component and having an inclined bottom wall ;
An exhaust emission control device comprising:   The exhaust emission control device according to claim 1, further comprising a sensor provided on the reducing agent tray and used to detect a liquid reducing agent or a precursor thereof and to issue an alarm.   The exhaust gas purification apparatus according to claim 1 or 2, wherein the reducing agent tray has a drain pipe connected to a bottom wall.   The exhaust gas purification apparatus according to claim 3, wherein the reducing agent tray has a bottom wall inclined toward a drain hole communicating with the drain pipe.   The exhaust gas purification apparatus according to claim 1 or 2, wherein the reducing agent tray is connected to the side wall by a drain member having a U-shaped cross section in which a groove communicating with the drain hole of the side wall is formed. .

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