JP6908340B2 - Work vehicle and exhaust purification device for work vehicle - Google Patents

Description

The present invention relates to a work vehicle and an exhaust gas purification device for the work vehicle.

Conventionally, an exhaust purification device that purifies nitrogen oxides (NOx) contained in engine exhaust using ammonia (NH _{3) as a reducing agent is known.} This exhaust purification device injects urea water into the exhaust system upstream of the selective reduction catalyst (hereinafter also referred to as "SCR (Selective Catalytic Reduction) catalyst") provided in the exhaust system of the engine, and the urea water is hydrolyzed. The ammonia and NOx produced by this are subjected to a selective reduction reaction with an SCR catalyst to purify them into harmless components.

The exhaust purified by such an exhaust purification device is discharged to the outside air through an exhaust pipe. For example, in the invention described in Patent Document 1, a tail pipe as an exhaust pipe is connected to a muffler portion including a silencer, a diesel particulate filter (DPF: Diesel Particulate Filter), and an oxidation catalyst. ing.

Generally, in an exhaust gas purification device using an SCR catalyst, a NOx sensor that detects the amount of nitrogen oxides (NOx) contained in the exhaust on the upstream side of the SCR catalyst and an exhaust gas on the downstream side of the SCR catalyst It is equipped with a NOx sensor that detects the amount of NOx contained. The NOx sensor on the downstream side is provided, for example, in the discharge portion of the muffler portion described above.

Japanese Unexamined Patent Publication No. 2013-19199

By the way, in the tail pipe described in Patent Document 1, the muffler cannot be directly seen from the open end surface on the downstream side of the tail pipe to the open end surface on the downstream side of the discharge pipe provided in the muffler portion. It is designed to prevent raindrops from entering the inside of the part.

However, in the above-mentioned tail pipe, since the axis of the discharge pipe protruding upward and the axis of the midstream portion of the tail pipe are concentric, raindrops that infiltrate from the downstream portion of the tail pipe and collide with the midstream portion. May fall downward and enter the discharge pipe. In addition, there is a possibility that the progress of raindrops that have entered from the downstream part will be non-straight due to the influence of exhaust gas, etc., and it is also possible that the raindrops move along the axis of the middle stream part and fall directly into the discharge pipe. ..

Therefore, when the above configuration is applied to a work vehicle equipped with a urea selective catalyst reduction device and an exhaust pipe is connected to the discharge section of the urea selective catalyst reduction device, raindrops adhere to the NOx sensor provided in the discharge section. There was a risk.

(1) According to one aspect of the present invention, the work vehicle is equipped with an exhaust gas purification device for an engine, and a sensor that detects an exhaust component purified by the exhaust gas purification device at an exhaust pipe connection port of the exhaust gas purification device. A work vehicle having an exhaust pipe structure for guiding purified exhaust gas to the outside of the vehicle, wherein the exhaust pipe structure is a first curved pipe provided on the exhaust downstream side of the exhaust pipe connection port. A second curved pipe portion that is externally inserted through a gap formed around the portion and the gas discharge side end portion of the first curved pipe portion, and a gas discharge side end of the second curved pipe portion. An exhaust pipe having a straight pipe portion extending from the portion to the upper part of the work vehicle is provided, and all of the projected images of the pipe cross section of the straight pipe portion in the direction of the axis of the straight pipe portion and toward the upstream side of the exhaust are the second curved lines. The exhaust pipe connecting port and the first curved pipe portion so that the projected image is projected on the inner wall of the pipe portion and the projected image is not projected on the inner wall of either the first curved pipe portion or the exhaust pipe connecting port. , The shape and arrangement of the straight pipe portion and the second curved pipe portion are defined.
(2) According to another aspect of the present invention, the exhaust purification device of the work vehicle is equipped with a urea selective catalyst reduction device that purifies the exhaust of the engine, and a NOx sensor is attached to the exhaust pipe connection port of the urea selective catalyst reduction device. An exhaust purification device provided with a gap formed around the first curved pipe portion provided on the exhaust downstream side of the exhaust pipe connection port and the gas discharge side end portion of the first curved pipe portion. The straight pipe portion includes a second curved pipe portion externally inserted through the pipe, and an exhaust pipe having a straight pipe portion extending upward from the gas discharge side end of the second curved pipe portion to the upper side of the work vehicle. All of the projected images of the pipe cross section in the direction of the axis of the straight pipe portion and toward the upstream side of the exhaust pipe are projected on the inner wall of the second curved pipe portion , and the projected images are the first curved pipe portion and the exhaust. Not projected onto any inner wall of the tube connection port .

According to the present invention, it is possible to prevent water droplets that have entered the exhaust pipe from adhering to a sensor that detects an exhaust component, such as a NOx sensor.

FIG. 1 is an external view of the work vehicle as viewed from the left side. FIG. 2 is an external view of the work vehicle as viewed from above. FIG. 3 is an external view of the work vehicle as viewed from the rear. FIG. 4 is a diagram showing the arrangement of the SCR housing and the exhaust pipe, and shows the case when viewed from the right side of the vehicle. FIG. 5 is a diagram showing the arrangement of the SCR housing and the exhaust pipe, and shows the case where the SCR housing and the exhaust pipe are viewed from the rear of the vehicle. FIG. 6 is a diagram showing the shape of the exhaust pipe. FIG. 7 is a diagram illustrating the function of the exhaust pipe. FIG. 8 is a diagram illustrating a curved pipe portion provided on the exhaust side of the exhaust pipe.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. 1 to 3 are views showing the appearance of the work vehicle 1, FIG. 1 is a view seen from the left side of the vehicle, FIG. 2 is a view seen from above the vehicle, and FIG. 3 is a view seen from the rear of the vehicle. The work vehicle 1 in the present embodiment is an engine type forklift. The engine is a general diesel engine, but may be a gasoline engine.

The work vehicle 1 is provided with a cargo handling mast 3 at the front portion of the vehicle body 2. A fork 8 is provided on the cargo handling mast 3 so as to be able to move up and down. The cargo handling mast 3 is tilted in the left-right direction shown by the tilt cylinder 4 provided on the vehicle body 2. The vehicle body 2 includes a driver's cab 6 including a driver's seat 5, front wheels 7A and rear wheels 7B for moving the vehicle body 2, and a storage unit 9 provided with a prime mover, a hydraulic circuit, and the like. An exhaust pipe 11 is provided behind the driver's cab 6.

As shown in FIG. 3, the exhaust pipe 11 is fixed to the pillar 60 on the rear right side of the driver's cab 6 by the support members 61 and 62. The exhaust pipe 11 is fixed so as to be displaced toward the outside of the vehicle with respect to the pillar 60. By arranging the exhaust pipe 11 in this way, as shown in FIG. 2, the exhaust pipe 11 is arranged so as to overlap the pillar 60 when viewed from the operator of the driver's seat 5. As a result, it is possible to prevent the exhaust pipe 11 from causing a decrease in rear visibility.

4 and 5 are views showing the arrangement of the SCR (selective catalytic reduction) housing 10 and the exhaust pipe 11 mounted on the vehicle body frame of the work vehicle 1. FIG. 4 is a view seen from the right side of the vehicle, and FIG. 5 is a view seen from the rear of the vehicle. In FIG. 5, the right side portion of the vehicle provided with the SCR housing 10 and the exhaust pipe 11 is shown, and the left side portion of the vehicle is not shown.

In FIG. 4, the DPF housing 12 is mounted as shown by the alternate long and short dash line, and the SCR housing 10 is connected to the subsequent stage of the DPF housing 12. The DPF housing 12 includes a diesel oxidation catalyst (DOC) device and a diesel particulate filter (DPF) device. The DOC device is placed in front of the DPF device, oxidizes hydrocarbons and carbon monoxide in the exhaust gas, and raises the temperature of the exhaust gas with the heat generated at that time, thereby promoting combustion in the DPF device in the subsequent stage. do. The DPF device is a device that captures and burns particulate matter (PM) in the exhaust gas.

The SCR housing 10 is a device provided with an SCR catalyst and selectively reducing and purifying nitrogen oxides (NOx) contained in the exhaust gas. An injector 102 is provided in the SCR housing 10, and urea water supplied from a urea water tank (not shown) is injected into a pipe 101 upstream of the SCR catalyst. The jetted urea water is hydrolyzed to produce ammonia. NOx in the exhaust undergoes a reduction reaction with ammonia by the SCR catalyst, and is discharged as nitrogen and water.

A NOx sensor 103 is provided at the SCR inlet on the upstream side of the injector 102, and a NOx sensor 104 is also provided on the exit side of the SCR housing 10. The NOx sensor 104 is attached to an exhaust pipe connection port 105 provided in the upper part of the housing of the SCR housing 10. The urea water supply amount is controlled so that the reduction reaction is efficiently performed according to the NOx concentration detected by the NOx sensors 103 and 104. A curved pipe portion 106 is provided on the exhaust downstream side of the exhaust pipe connection port 105. In the present embodiment, the curved pipe portion 106 is bolted to the exhaust pipe connecting port 105, but may be provided integrally with the exhaust pipe connecting port 105.

As shown in FIG. 5, the exhaust pipe 11 includes a curved pipe portion 111, a straight pipe portion 112, and a curved pipe portion 113 in this order from the exhaust upstream side. Although the details will be described later, the curved tube portion 111 is extrapolated to the curved tube portion 106 through a gap. The exhaust pipe 11 is fixed to the pillar 60 on the rear right side of the cab 6 by the support members 61 and 62. Since the curved pipe portion 106 is bent in the direction of the right side of the vehicle, the exhaust pipe 11 is displaced in the direction of the right side of the vehicle with respect to the pillar 60. The curved pipe portion 113 provided at the gas discharge side end of the straight pipe portion 112 is bent to the rear of the vehicle. A protective guard 114 is attached to the exhaust pipe 11 which becomes hot during operation. As shown in the enlarged view of part A in FIG. 4 and the enlarged view of part B in FIG. 5, a large number of holes are formed in the protection guard 114.

FIG. 6 is a diagram showing the shape of the exhaust pipe 11. FIG. 6A is a view of the exhaust pipe 11 viewed from the rear of the work vehicle, as in the case of FIG. FIG. 6 (b) is a view taken along the line E of FIG. 6 (a). The exhaust pipe 11 includes a curved pipe portion 111, a straight pipe portion 112, and a curved pipe portion 113 in this order from the exhaust upstream side to the exhaust downstream side. Exhaust gas flows in through the opening of the curved pipe portion 111, passes through the straight pipe portion 112, and is discharged to the outside air through the opening of the curved pipe portion 113.

FIG. 7 is a diagram for explaining the function of the exhaust pipe 11, and shows a detailed structure from the exhaust pipe connection port 105 of the SCR housing 10 to the straight pipe portion 112 of the exhaust pipe 11. Note that FIG. 7 shows a case where the exhaust pipe 11 is viewed from the rear of the vehicle. As described above, an exhaust pipe connection port 105 in which the NOx sensor 104 is arranged is provided in the upper part of the SCR housing 10.

The exhaust pipe connection port 105 includes a curved pipe portion 106 that is bent to the right side of the vehicle. The curved pipe portion 111 of the exhaust pipe 11 is externally inserted into the gas discharge side end of the curved pipe portion 106 via the gap G. The straight pipe portion 112 is provided so as to extend upward from the gas discharge side end portion of the curved pipe portion 111 to the upper side of the work vehicle.

The exhaust gas EG discharged from the exhaust pipe connection port 105 flows into the straight pipe portion 112 through the curved pipe portion 106 and the curved pipe portion 111. Then, the exhaust gas EG guided upward by the straight pipe portion 112 is discharged into the atmosphere from the curved pipe portion 113 (see FIG. 6) of the exhaust pipe 11. A gap G is formed around the portion where the curved pipe portion 106 is inserted with respect to the curved pipe portion 111. Therefore, due to the ejector effect generated by the flow of the exhaust gas EG from the curved pipe portion 106 to the curved pipe portion 111, the outside air flows into the curved pipe portion 111 through the gap G as shown by the broken line. The temperature of the exhaust gas drops due to the inflow of the outside air.

Further, since the curved pipe portion 106 and the curved pipe portion 111 are provided between the exhaust pipe connecting port 105 having the NOx sensor 104 and the straight pipe portion 112, the straight pipe is provided with respect to the axis of the exhaust pipe connecting port 105. The axis of the portion 112 is displaced to the right side of the vehicle. The pipe cross section (cross section relating to the inner diameter) S1 of the exhaust pipe connection port 105 completely overlaps with the projected image S21 on the same plane as the pipe cross section S1 when the pipe cross section S2 of the straight pipe portion 112 is projected in the axial direction. Never.

By the way, when water droplets such as rain enter the exhaust pipe 11 from the curved pipe portion 113 shown in FIG. 6, the water droplets collide with the inner wall of the curved pipe portion 113 or fall inside the straight pipe portion 112. In the case of the configuration shown in FIG. 7, since the curved pipe portion 111 is provided on the exhaust upstream side (lower side in the drawing) of the straight pipe portion 112, the water droplet WD falling along the axis of the straight pipe portion 112 is curved. It will collide with the region 20 indicated by the two-point difference line on the inner wall of the pipe portion 111. The region S20 indicated by the two-point difference line indicates a projection region when the pipe cross section S2 of the straight pipe portion 112 is projected in the axial direction.

The operation and effect of the work vehicle equipped with the exhaust gas purification device of the embodiment described above will be described.
(C1) A work vehicle equipped with an exhaust gas purification device is equipped with an SCR housing 10 which is a urea selective catalytic reduction device for purifying engine exhaust gas, and is provided with a NOx sensor 104 at an exhaust pipe connection port 105 of the SCR housing 10. .. The exhaust gas purified by the exhaust purification device is discharged to the outside of the vehicle through the exhaust pipe structure. The exhaust pipe structure is externally inserted into a first curved pipe portion 106 provided on the exhaust downstream side of the exhaust pipe connecting port 105 and a gas discharge side end portion of the first curved pipe portion 106 via a gap G. 2 curved pipe portion 111, and an exhaust pipe 11 having a straight pipe portion 112 extending upward from the gas discharge side end portion of the second curved pipe portion 111, and a pipe cross section of the straight pipe portion 112. The projected image of S2 in the direction of the axis of the straight pipe portion and toward the upstream side of the exhaust is projected on the region S20 of the inner wall of the second curved pipe portion 111.

Therefore, water droplets WD such as rain that infiltrate the exhaust pipe 11 and fall on the straight pipe portion 112 collide with the region S20 of the inner wall of the curved pipe portion 111 and flow down along the inner wall of the curved pipe portion 111. It is discharged to the outside of the exhaust pipe 11 through the gap G between the 111 and the curved pipe portion 106. As a result, it is possible to prevent water droplets flowing in from the opening 113a of the curved pipe portion 113 from entering the curved pipe portion 106. That is, it is possible to prevent raindrops from adhering to the NOx sensor 104 provided in the exhaust pipe connection port 105 and causing the NOx sensor 104 to fail.

FIG. 8 is a diagram illustrating a curved pipe portion 113 provided on the exhaust side of the exhaust pipe 11. In the example shown in FIG. 8A, the curved pipe portion 113 is bent to the right side in the drawing, and the normal vector n of the opening 113a of the curved pipe portion 113 points in the horizontal direction. Therefore, the water droplets WD that can enter through the opening 113a of the curved pipe portion 113 are limited to those that can enter obliquely with respect to the opening 113a as shown by the broken line arrow in FIG. Further, most of the water droplets WD that have infiltrated diagonally collide with the inner wall of the curved pipe portion 113 and the inner wall of the straight pipe portion 112.

(C2) That is, by providing the curved pipe portion 113 at the gas discharge side end of the straight pipe portion 112, water droplets falling in the axial direction of the straight pipe portion 112 can be slightly suppressed, which is shown in FIG. The amount of water to be drained from the gaps G of the curved pipe portions 106 and 111 can be suppressed to a small amount.

(C3) Further, as shown in FIG. 8B, the direction of the normal vector n of the opening 113a is configured to face vertically downward from the horizontal, thereby further suppressing the intrusion of water droplets into the exhaust pipe 11. be able to.

(C4) Further, as shown in FIGS. 2 and 3, the exhaust pipe 11 is fixed to the pillar 60 behind the driver's cab 6 provided in the work vehicle 1, and is shown in FIG. As described above, the exhaust pipe 11 can be easily arranged at a position deviated from the pillar 60 in the outward direction of the vehicle.
In the exhaust pipe 11 of the embodiment, the extension line (not shown) of the line segment connecting the driver's eye point EP (see FIG. 2) and the rear pillar 60 is at least in a part of the straight pipe portion 112. The straight pipe portion 112 is fixed to the rear pillar 60 so as to pass through. That is, as shown in FIG. 2, the exhaust pipe 11 can be arranged so as to overlap the pillar 60 when viewed from the operator of the driver's seat 5. As a result, it is possible to prevent the exhaust pipe 11 from causing a decrease in rear visibility.

The embodiments described above are merely examples of embodiment of the present invention, and the technical scope of the present invention is not limitedly interpreted by them. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features, and other aspects considered within the scope of the technical idea of the present invention are also within the scope of the present invention. Included in. For example, in the above embodiment, a work vehicle provided with both an SCR device (selective catalytic reduction device) and a DPF device as an exhaust purification system has been described as an example, but it can be implemented in the following modified examples.

(1) The same can be applied to a work vehicle equipped with only an SCR device.
(2) Although the exhaust pipe of the engine type forklift has been described as an example, the description is not limited to this, and the present invention can be applied to various work vehicles (wheel loaders and the like) equipped with a urea selective catalyst reduction device.
(3) Although the urea selective catalytic reduction device has been described as an example for exhaust gas purification, it is not necessarily limited to the urea selective catalytic reduction device.

(4) The NOx sensor was shown as a sensor that deteriorates due to the adhesion of raindrops that enter from the exhaust port of the exhaust pipe structure, but it is a sensor that detects other exhaust gas components and deterioration due to moisture progresses. The present invention can also be applied to an exhaust gas purification device equipped with a sensor.
A vehicle equipped with such an exhaust purification device is equipped with a sensor for detecting the components of the exhaust purified by the exhaust purification device at the exhaust pipe connection port of the exhaust purification device, and guides the purified exhaust gas to the outside of the vehicle. It has an exhaust pipe structure. The exhaust pipe structure consists of a first curved pipe portion provided on the downstream side of the exhaust of the exhaust pipe connection port and a second curved pipe externally inserted through a gap at the gas discharge side end portion of the first curved pipe portion. A portion and an exhaust pipe having a straight pipe portion extending upward from the work vehicle from the gas discharge side end portion of the second curved pipe portion are provided. In the exhaust pipe structure, the projected image of the pipe cross section of the straight pipe portion in the direction of the axis of the straight pipe portion and toward the upstream side of the exhaust is projected on the inner wall of the second curved pipe portion so as not to be projected on the exhaust pipe connection port. The shapes and arrangements of the exhaust pipe connection port, the first curved pipe portion, the straight pipe portion, and the second curved pipe portion are defined.

1 ... Work vehicle, 10 ... SCR housing, 6 ... Driver's cab, 11 ... Exhaust pipe, 12 ... DPF housing, 60 ... Pillar, 103, 104 ... NOx sensor, 105 ... Exhaust pipe connection port, 106, 111, 113 ... Curved pipe part, 112 ... Straight pipe part, S1, S2 ... Piping cross section, S20 ... Region, S21 ... Projected image

Claims (7)

It is equipped with an engine exhaust purification device, and is equipped with a sensor that detects the components of the exhaust purified by the exhaust purification device at the exhaust pipe connection port of the exhaust purification device, and exhaust that guides the purified exhaust gas to the outside of the vehicle. A work vehicle equipped with a pipe structure
The exhaust pipe structure is
A first curved pipe portion provided on the exhaust downstream side of the exhaust pipe connection port, and
Work from the second curved pipe portion that is externally inserted through a gap formed around the gas discharge side end portion of the first curved pipe portion, and the gas discharge side end portion of the second curved pipe portion. With an exhaust pipe having a straight pipe portion extending above the vehicle,
All of the projected images of the pipe cross section of the straight pipe portion in the direction of the axis of the straight pipe portion and toward the upstream side of the exhaust are projected on the inner wall of the second curved pipe portion, and the projected image is the first curved pipe. The shape and arrangement of the exhaust pipe connection port, the first curved pipe portion, the straight pipe portion, and the second curved pipe portion are determined so as not to be projected on the inner wall of either the portion or the exhaust pipe connecting port. Working vehicle. In the work vehicle according to claim 1,
The exhaust gas purification device is a urea selective catalyst reduction device, and the sensor is a NOx sensor, a work vehicle. In the work vehicle according to claim 1 or 2.
The exhaust pipe is a work vehicle further having a third curved pipe portion provided at the gas discharge side end portion of the straight pipe portion. In the work vehicle according to claim 3,
The discharge side opening of the third curved pipe portion is a work vehicle in which the normal of the opening cross section is horizontal or faces vertically below the horizontal. In the work vehicle according to any one of claims 1 to 4.
The straight pipe portion is a work vehicle fixed to a rear pillar of a driver's cab provided in the work vehicle. In the work vehicle according to claim 5.
The straight pipe portion is fixed to the rear pillar so that the extension line of the line segment connecting the driver's eye point and the rear pillar passes through at least a part of the area of the straight pipe portion. vehicle. It is an exhaust purification device for work vehicles equipped with a urea selective catalyst reduction device that purifies engine exhaust and a NOx sensor at the exhaust pipe connection port of the urea selective catalyst reduction device.
A first curved pipe portion provided on the exhaust downstream side of the exhaust pipe connection port, and
Work from the second curved pipe portion that is externally inserted through a gap formed around the gas discharge side end portion of the first curved pipe portion, and the gas discharge side end portion of the second curved pipe portion. With an exhaust pipe having a straight pipe portion extending above the vehicle,
All of the projected images of the pipe cross section of the straight pipe portion in the direction of the axis of the straight pipe portion and toward the upstream side of the exhaust gas are projected on the inner wall of the second curved pipe portion , and the projected image is the first curved pipe. An exhaust purification device for a work vehicle that is not projected onto the inner wall of either the section or the exhaust pipe connection port.

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