Diesel engine exhaust emission control device for work vehicle

Abstract

To inexpensively attach a DPF device and an SCR device required for purifying exhaust gas of a diesel engine mounted to a work vehicle to a traveling vehicle body.SOLUTION: In a work vehicle, a diesel engine 40 is mounted to a front part of a traveling vehicle body 10. In a diesel engine exhaust device for the work vehicle, a DPF device 4 placed on an engine body 41 of the diesel engine 40 and an SCR device 5 mounted to an SCR bracket 25 that is integral with the engine body 41 to separate from the DPF device 4 are coupled by an exhaust pipe 52, and exhaust gas is discharged from the SCR device 5 to a tail pipe 42 attached to the traveling vehicle body 10.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an exhaust gas purification device for a diesel engine mounted on a work vehicle. [Background technology]

[0002] Agricultural vehicles and civil engineering vehicles such as tractors and combine harvesters are equipped with diesel engines, and in order to purify the exhaust gas, urea water is supplied to the exhaust gas to convert nitrogen oxides (NOx) into NO. 2 An SCR (selective catalytic reduction) device that reduces CO2 to 100% and a DPF (diesel particulate filter) device that collects and incinerates particulate matter (PM) in the exhaust gas are installed in the exhaust gas discharge path.

[0003] For example, in the tractor described in Patent Document 1, a DPF device is installed on the diesel engine body mounted inside the bonnet at the front of the vehicle body, and an SCR device is attached to the lower part of a tail pipe that is erected along a cabin support pillar that is erected on the vehicle body, and the DPF device and SCR device are connected by a urea mixing pipe and a bellows-shaped connecting pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6177005 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional tractor diesel engine exhaust gas purification system, the DPF device is attached to the diesel engine and the SCR device is attached to the cabin support of the running body, so a bellows-shaped connecting pipe is required to prevent vibrations from the diesel engine body from being transmitted to the SCR device.

[0006] An object of the present invention is to inexpensively install a DPF device and an SCR device, which are necessary to purify the exhaust gas from a diesel engine mounted on a work vehicle, on the running body of the vehicle. [Means for solving the problem]

[0007] The above object of the present invention can be achieved by the following technical means.

[0008] The invention of claim 1 relates to a diesel engine exhaust system for a work vehicle equipped with a diesel engine 40 at the front of a traveling body 10, characterized in that a DPF device 4 mounted on an engine body 41 of the diesel engine 40 and an SCR device 5 mounted on an SCR bracket 25 integrated with the engine body 41 and separated from the DPF device 4 are connected by an exhaust pipe 52, and exhaust is discharged from the SCR device 5 to a tail pipe 42 attached to the traveling body 10.

[0009] The invention of claim 2 provides the diesel engine exhaust system for a work vehicle according to claim 1, characterized in that the SCR bracket 25 is attached to a rear plate 37 of the engine body 41.

[0010] The invention of claim 3 provides the diesel engine exhaust system for the work vehicle according to claim 1, characterized in that the SCR bracket 25 is attached to the side frame 38 of the traveling vehicle body 10 on which the diesel engine 40 is mounted.

[0011] The invention of claim 4 provides the diesel engine exhaust system for the work vehicle according to claim 1, characterized in that the SCR bracket 25 is attached to a transmission case 45 directly connected to the engine body 41 of the diesel engine 40.

[0012] The invention of claim 5 relates to a diesel engine exhaust system for a work vehicle, characterized in that a DPF device 4 and an SCR device 5 are provided in the exhaust gas flow path of a diesel engine 40, and a water separation case 47 is provided in the exhaust gas flow path exiting the SCR device 5 to swirl the exhaust gas and centrifuge the water in the exhaust.

[0013] The invention of claim 6 relates to a diesel engine exhaust system for a work vehicle, characterized in that in the work vehicle having a DPF device 4 and an SCR device 5 provided in the exhaust gas flow path of the diesel engine 40, a NOx sensor 55 is provided in the tail pipe 42, and a sensor protection guide 56 is provided at the upper part of the exhaust side to increase the gas flow rate or to divert the gas flow. Effect of the Invention

[0014] In the invention of claim 1, the DPF device 4 is mounted on the engine body 41 of the diesel engine 40, and effectively performs regeneration processing by burning PM that becomes hot due to heat generated by the engine and clogs the filter, and the SCR device 5 provided away from the DPF device 4 converts NOx in the exhaust gas into NO by supplying urea water. 2 However, since the SCR device 5 is mounted on the SCR bracket 25 that is integrated with the engine body 41, the DPF device 4 and the SCR device 5 resonate with the engine, and a bellows-shaped connecting pipe for absorbing vibrations between the DPF device 4 and the SCR device 5 is not required, and it is possible to directly connect the DPF device 4 and the SCR device 5 with the exhaust pipe 52, which allows the exhaust piping to be constructed at low cost.

[0015] In the invention of claim 2, the SCR bracket 25 for mounting the SCR device 5 is attached to the rear plate 37 of the engine body 41, so that the DPF device 4 and the SCR device 5 resonate with each other, eliminating the need for a bellows-shaped connecting pipe to absorb vibrations.

[0016] In the invention of claim 3, the side frame 38 of the vehicle body 10 on which the diesel engine 40 is mounted directly receives the vibrations of the engine body 41, causing the attached SCR bracket 25 to resonate, so that the DPF device 4 and the SCR device 5 enter a resonant state, eliminating the need for a bellows-shaped connecting pipe to absorb the vibrations.

[0017] In the invention of claim 4, by attaching the SCR bracket 25 to the transmission case 45 which is directly connected to the engine body 41 and resonates with it, the SCR device 5 resonates with the DPF device 4, eliminating the need for a bellows-shaped connecting pipe to absorb vibrations.

[0018] In the invention of claim 5, the exhaust gas that has passed through the SCR device 5 passes through the water separation chamber 48, whereby the urea water contained in the exhaust gas is centrifuged and recovered, so that the urea water can be reused.

[0019] In the invention of claim 6, the NOx sensor 55 detects the concentration of NOx as the exhaust gas passes through the SCR device 5 and passes through the tail pipe 42. However, a sensor protection guide 56 provided on the upper part of the exhaust side of the NOx sensor 55 speeds up the flow of the exhaust gas or deflects the flow to the side, so that rainwater entering from the outlet side of the tail pipe 42 does not fall on the NOx sensor 55, and deterioration of the NOx sensor 55 does not progress. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a right side view showing a tractor as an example of a work vehicle according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a plan view of a tractor according to an embodiment of the present invention, excluding a cabin. [Diagram 3] 1 is a perspective view of an exhaust gas treatment device for a diesel engine of a tractor according to an embodiment of the present invention. [Figure 4] 1 is a perspective view of a water separation chamber provided in an exhaust gas exhaust path of a tractor according to an embodiment of the present invention. FIG. [Diagram 5] 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6] FIG. 11 is a perspective view showing a water separation chamber of another embodiment of the tractor according to the present invention. [Figure 7] 7 is a cross-sectional view taken along line AA in FIG. 6. [Figure 8] 1 is a front cross-sectional view of an exhaust pipe showing a NOx sensor provided in an exhaust pipe of a tractor according to an embodiment of the present invention. [Figure 9] FIG. 2 is a side cross-sectional view of an exhaust pipe of a tractor according to an embodiment of the present invention. [Figure 10] FIG. 11 is a cross-sectional view of an exhaust pipe side of a NOx sensor of another embodiment of a tractor according to the present invention. [Figure 11]1 is a front cross-sectional view of an exhaust pipe showing a NOx sensor provided in an exhaust pipe of a tractor according to an embodiment of the present invention. [Figure 12] FIG. 1 is a side view showing the arrangement of an SCR device of a tractor according to an embodiment of the present invention. [Figure 13] FIG. 4 is a side view showing another arrangement of the SCR device of the tractor according to the embodiment of the present invention. [Figure 14] FIG. 2 is a flowchart showing a regeneration process of an SCR device of a tractor according to an embodiment of the present invention. [Figure 15] FIG. 2 is a diagram showing a urea water supply piping diagram of an SCR device of a tractor according to an embodiment of the present invention. [Figure 16] FIG. 11 is a diagram showing urea water supply piping of an SCR device of another embodiment of a tractor according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0022] FIG. 1 shows a side view of a work vehicle (tractor) equipped with a diesel engine 40 whose output is controlled by a common rail, and FIG. 2 shows a plan view of the tractor without the cabin 14.

[0023] The tractor is configured to have a pair of left and right front wheels 12, 12 and a pair of left and right rear wheels 13, 13 under a traveling body 10, and the rotational power of a diesel engine 40 mounted on a side frame 38 of the traveling body 10 inside a bonnet 50 at the front of the machine is appropriately reduced in speed by a gearbox inside a transmission case 45 and transmitted to the front wheels 12, 12 and rear wheels 13, 13 to travel the traveling body 10 and drive a working machine 21 (rotary, etc.) attached to the rear of the traveling body 10. A tail pipe 42 for discharging exhaust gas from the diesel engine 40 is erected on the bonnet 50, and its upper end is bent forward to prevent rainwater from directly entering.

[0024] A steering handle 16 is supported on a handle post 15 inside a cabin 14 at the center of the traveling body 10, and a seat 17 is provided behind it. A forward / reverse lever 18 for switching the traveling direction of the traveling body 10 between forward and backward is provided below the steering handle 16. When the forward / reverse lever 18 is operated forward, the vehicle moves forward, and when operated backward, the vehicle moves backward.

[0025] An accelerator lever for adjusting the engine speed is provided on the opposite side of the forward / reverse lever 18 across the handle post 15, and an accelerator pedal 23 for similarly adjusting the engine speed, and left and right brake pedals 24L, 24R for applying the brakes to the left and right rear wheels 13, 13 are provided on the right corner of the step floor 19. A clutch pedal 20 is provided on the left corner of the step floor 19.

[0026] The main speed change lever 26 is located at the front left side of the seat 17, and the sub-speed change lever 27, which can select any one of low, medium, high and neutral positions, is located behind it, and the PTO speed change lever 28 is provided on the right side of it. Furthermore, on the right side of the seat 17, there are a position lever 29 for setting the height of the working implement 21 (rotary, etc.), an automatic tilling depth lever 30 for automatically setting the tilling depth of the field, and behind these levers, a right-up switch 31 and a right-down switch 32 for the working implement 21 are located, and further behind these, an automatic level switch 33 and a backup switch 34 for the working implement 21 are located. The backup switch 34 automatically raises the working implement 21 when the machine moves backward. The working implement 21 is connected to the rear of the machine by a link 22. The tractor drives the working implement 21 to run the machine, thereby performing work such as tilling in the field. 21a is a hydraulic cylinder for raising and lowering the working implement 21.

[0027] 3 is an enlarged perspective view showing the exhaust gas path of a diesel engine 40. A DPF device 4 is mounted on the top of the engine body 41, and exhaust gas generated in the cylinders inside the engine body 41 is introduced and PM contained in the exhaust is removed by a filter. PM that accumulates in the filter is incinerated by appropriately warming up the engine and regenerated.

[0028] The SCR device 5 is mounted on the SCR bracket 25 attached to the rear plate 37 of the engine body 41 on the side of the diesel engine 40, and is connected to the DPF device 4 by an exhaust pipe 52 to send exhaust gas to the SCR device 5. Urea water is injected from a urea water injection device 53 provided in the exhaust pipe 52, and NOx in the exhaust is converted into NO by a catalytic reaction in the SCR device 5. 2 Reduce to.

[0029] 4 and 5 are drawings showing the internal structure of the SCR device 5. The SCR device 5 and the water separation chamber 48 are provided in a cylindrical SCR case 5A. The exhaust gas entering the SCR case 5A from the gas inlet 52A passes through the water separation chamber 48 to remove moisture, and the SCR device 5 produces NOx by catalytic reaction. 2 and discharged from gas outlet 52B.

[0030] The water separation chamber 48 has a cylindrical inner wall 47A and an outer wall 47B, and fine holes 47C are provided in the outer wall 47B. The exhaust gas is swirled and the moisture is released to the outer periphery by centrifugal force. The moisture flows downward through the fine holes 47C and flows out from the bottom of the SCR case 5A, and the urea water is stored in the water case 49.

[0031] 6 and 7 show another embodiment of the SCR device 5, in which the inner wall 47A of the water separation chamber 48 is also provided with fine holes 47D to improve separation of water.

[0032] 8, 9, and 10 show a configuration in which a NOx sensor 55 that detects NOx in exhaust gas discharged from the SCR device 5 is provided inside the tail pipe 42, and a sensor protection guide 56 is provided above the NOx sensor 55 to increase the flow rate of the exhaust gas and blow away rainwater so that it does not hit the NOx sensor 55. In Figures 8 and 9, the gas passage of the sensor protection guide 56 above the NOx sensor 55 is narrowed, narrowing the flow path upward so that the exhaust gas is blown up strongly, preventing water from falling on the NOx sensor 55 as the exhaust gas is blown up. Also, the sensor protection guide 56 in Figure 10 blows the exhaust gas to the side above the NOx sensor 55 to prevent water from falling on the NOx sensor 55.

[0033] 11, fine holes 47D through which exhaust gas flows are provided around the insertion opening of connecting pipe 57 that is inserted into SCR case 5A, and NOx sensor 55 is provided outside of the holes 47D to prevent rainwater flowing in from connecting pipe 57 from directly contacting NOx sensor 55. Glass wool 58 is wrapped around the connection between connecting pipe 57 and tail pipe 42 to prevent exhaust gas and rainwater from leaking out.

[0034] Fig. 12 shows an example of the arrangement of the SCR device 5 mounted on the SCR bracket 25. It is preferable to arrange the SCR device 5 between the intake fan 43 and the radiator 44 of the diesel engine 40 to expose it to engine cooling air and prevent freezing. Also, as shown in Fig. 13, it is also preferable to arrange the SCR device 5 on the side of the engine body 41 so that the SCR device 5 is warmed by the heat generated by the engine body 41.

[0035] Since the SCR device 5 is erected on the right side of the bonnet 50, in front of the cabin 14, when the operator sits in the seat 17 inside the cabin 14 looks forward, the SCR device 5 is not obscured by the right side pillar and does not obstruct the forward visibility, making it easier to operate the tractor.

[0036] Figure 14 is a flowchart of the regeneration process of the DPF device 4. When the PM deposition increases, a regeneration process is performed to incinerate the PM by raising the exhaust temperature of the diesel engine 40 to a high temperature. When the regeneration process is interrupted halfway or the engine is stopped, a process is performed to increase the exhaust temperature by slightly closing the intake slot even after the post-injection ends during the regeneration process. With this control, HC poisoning is eliminated and a decrease in purification efficiency is prevented.

[0037] Also, the AdBlue injection amount, NOx emission amount, and total operation time are monitored. When the total operation time is long and the decrease in NOx with respect to the AdBlue injection amount is low, it is determined that the purification efficiency has dropped, and control is performed to carry out the next DPF regeneration for 40 minutes. In this way, HC poisoning is eliminated by maintaining an exhaust temperature of 400°C or higher for 30 to 40 minutes.

[0038] Also, the AdBlue injection amount, NOx emission amount, and total operation time are monitored. When the total operation time is long and the decrease in NOx with respect to the AdBlue injection amount is low, it is determined that the purification efficiency has dropped. When the next DPF regeneration request is reported, an instruction is given to the operator to perform a service regeneration to prevent the occurrence of HC poisoning.

[0039] Figures 15 and 16 are piping diagrams for supplying urea water to the SCR device 5. Urea water flows from the pipe WP3 from the engine body 41 through the dosing motor 61 and the urea tank 62 to the centrifugal water pump 60 and circulates. In the piping circuit of Figure 15, a three-way solenoid valve 63 is provided in the pipe WP3, sent to the dosing motor 61 through the pipe WP6, merged into the supply pipe WP1, sent to the urea tank 62 through the pipe WP4, and merged into the supply pipe WP1 from the urea tank 62 through the pipe WP5. Also, in the piping circuit of Figure 16, a three-way solenoid valve 63 is provided inside the urea tank 62, sent from the engine body 41 to the urea tank 62 through the pipe WP3, sent to the dosing motor 61 through the pipe WP6 from the three-way solenoid valve 63, merged into the supply pipe WP1 through the pipe WP2, and merged into the supply pipe WP1 through the pipe WP from the three-way solenoid valve 63.

Description of Symbols

[0040] 4 DPF device 5 SCR device 10 Running vehicle 25 SCR bracket 37 Rear plate 38 Side Frame 40 Diesel Engine 41 Engine body 42 Tailpipe 45 Transmission case 47 Water Separator Case 52 Exhaust pipe 55 NOx sensor 56 Sensor Protection Guide

Claims

1. This diesel engine exhaust system for a work vehicle is characterized in that in a work vehicle having a diesel engine (40) mounted on the front of a traveling body (10), a DPF device (4) placed on the engine body (41) of the diesel engine (40) and an SCR device (5) mounted on an SCR bracket (25) integral with the engine body (41) and separated from the DPF device (4) are connected by an exhaust pipe (52), and exhaust is discharged from the SCR device (5) to a tail pipe (42) attached to the traveling body (10).

2. 2. The diesel engine exhaust system for a work vehicle according to claim 1, wherein the SCR bracket (25) is attached to a rear plate (37) of the engine body (41).

3. 2. The diesel engine exhaust system for a work vehicle according to claim 1, wherein the SCR bracket (25) is attached to a side frame (38) of a traveling vehicle body (10) on which the diesel engine (40) is mounted.

4. 2. The diesel engine exhaust system for a work vehicle according to claim 1, wherein an SCR bracket (25) is attached to a transmission case (45) that is directly connected to an engine body (41) of the diesel engine (40).

5. A diesel engine exhaust system for a work vehicle, comprising a DPF device (4) and an SCR device (5) provided in an exhaust gas flow path of a diesel engine (40), and a water separation case (47) for swirling the exhaust gas and separating water in the exhaust by centrifugal force in the exhaust gas flow path exiting the SCR device (5).

6. A diesel engine exhaust system for a work vehicle, in which a DPF device (4) and an SCR device (5) are provided in an exhaust gas flow path of a diesel engine (40), is provided with a NOx sensor (55) in a tail pipe (42), and a sensor protection guide (56) for increasing the flow rate of gas or diverting the flow of gas is provided at the upper part of the exhaust side.

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