JP2010156208A - Diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the regeneration efficiency of a diesel particulate filter provided in an exhaust gas discharge path, and to suppress odor and white smoke emissions, during regeneration, into the atmosphere. <P>SOLUTION: This diesel engine includes an aftertreatment device 46 composed of an oxidation catalyst 46a and the diesel particulate filter 46b collecting particulate matter PM in exhaust gas, and provided downstream of a supercharger TB. In the diesel engine, an exhaust pipe 63 upstream of the exhaust turbine 45 of the supercharger TB is formed of a bypass path 64, the bypass path 64 is provided with a second oxidation catalyst 65, and a throttle valve 66 is provided for regulating the volume of exhaust gas flowing in the bypass path 64. The second oxidation catalyst 65 is formed into a shape smaller than the oxidation catalyst 46a arranged downstream of the supercharger TB. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a diesel engine equipped with a diesel particulate filter and an oxidation catalyst.

In the exhaust system of a diesel engine, an oxidation catalyst (DOC) and a diesel particulate filter (DPF) are provided. (For example, refer to Patent Document 1).
JP 2008-75610 A

  The technology as described above has the following drawbacks. During regeneration of the DPF, the exhaust valve is closed and the exhaust gas temperature is raised to activate the oxidation catalyst (DOC) and the diesel particulate filter (DPF). Then, the unburned fuel is made to flow along with the exhaust gas by post-injection, burned by the oxidation catalyst (DOC), the temperature in the DPF is raised, the soot and particulate matter (PM) in the DPF are burned and burned in the atmosphere Fly.

However, since the temperature inside the oxidation catalyst (DOC) is not sufficiently increased at the start of post injection, a part of unburned fuel is discharged, resulting in a smell and white smoke.
The subject of this invention is providing the work vehicle carrying the diesel engine which eliminates the above malfunctions.

The above object of the present invention is achieved by the following configuration.
That is, according to the first aspect of the present invention, the aftertreatment device (46) including the diesel particulate filter (46b) for collecting the particulate matter (PM) in the exhaust gas and the oxidation catalyst (46a) is passed. In the diesel engine provided on the downstream side of the turbocharger (TB), a bypass path (64) is formed in the exhaust pipe (63) upstream of the exhaust turbine (45) of the supercharger (TB), and the bypass path ( 64) is provided with a second dioxide catalyst (65), and a throttle valve (66) for adjusting the amount of exhaust gas flowing in the bypass passage (64) is provided.

  According to the first aspect of the present invention, when unburned fuel is flowed by post-injection, a part of the unburned fuel is oxidized by the upstream second dioxide catalyst (65) to raise the temperature. Since the second dioxide catalyst (65) is arranged on the upstream side where the exhaust gas temperature is high, it is in an active state even during the forced regeneration operation of the DPF.

  The remaining fuel is oxidized by the downstream oxidation catalyst (46a) and further heated, soot and particulate matter (PM) collected in the diesel particulate filter (46b) is burned to the atmosphere. Drain inside. The throttle valve (66) is closed during the temperature increase mode operation in the forced regeneration of the diesel particulate filter (46b).

  The invention according to claim 2 is characterized in that the second dioxide catalyst (65) has a smaller shape than the oxidation catalyst (46a) arranged downstream of the supercharger (TB). The diesel engine is described.

  The action of the second aspect is the same as that of the first aspect, and the second dioxide catalyst (65) has a smaller shape than the oxidation catalyst (46a) arranged on the downstream side of the supercharger (TB).

  Since the present invention is configured as described above, according to the first aspect of the present invention, the two oxidation catalysts of the second oxidation catalyst (65) and the oxidation catalyst (46a) are used during the forced regeneration operation of the diesel particulate filter (46b). The temperature rises sufficiently by the action. As a result, the diesel particulate filter (46b) can be efficiently regenerated and part of the unburned fuel can be prevented from being discharged, so that the release of odors and white smoke into the atmosphere is suppressed. Become so.

  In the invention of claim 2, in addition to the effect of claim 1, the second dioxide catalyst (65) has a smaller shape than the oxidation catalyst (46a) disposed downstream of the supercharger (TB). The engine and exhaust system can be configured compactly.

The best mode for carrying out the present invention will be described.
FIG. 1 is an overall configuration diagram of a pressure accumulation type fuel injection device. The accumulator fuel injection device is applied to, for example, a multi-cylinder diesel engine, but may be a gasoline engine. The accumulator fuel injection device pressurizes the common rail 1 accumulating high-pressure fuel corresponding to the injection pressure, the pressure sensor 2 attached to the common rail 1, and the fuel pumped up from the fuel tank 3, and pumps the fuel to the common rail 1. A high-pressure pump 4, a fuel injection nozzle 6 for injecting high-pressure fuel accumulated in the common rail 1 into the cylinder 5 of the engine E, a control device (ECU) for controlling the operation of the high-pressure pump 4 and the fuel injection nozzle 6 Consists of ECU is an abbreviation for engine control unit.

Thus, the common rail 1 injects fuel to each cylinder 5 of the engine E, and makes the fuel supply a required pressure.
The fuel in the fuel tank 3 is sucked into the high-pressure pump 4 driven by the engine E through the fuel filter 7 through the suction passage, and the high-pressure fuel pressurized by the high-pressure pump 4 is guided to the common rail 1 through the discharge passage 8. Stored.

  The high-pressure fuel in the common rail 1 is supplied to the fuel injection nozzles 6 for the number of cylinders through the high-pressure fuel supply passages 9, and the fuel injection nozzles 6 are operated to the respective cylinders based on commands from the ECU 100. The surplus fuel (return fuel) from each fuel injection nozzle 6 is guided to a common return passage 10 by each return passage 10 and returned to the fuel tank 3 by this return passage 10.

  In addition, a pressure control valve 11 is provided in the high-pressure pump 4 to control the fuel pressure (common rail pressure) in the common rail 1. The pressure control valve 11 is connected to the fuel tank 3 from the high-pressure pump 4 by a duty signal from the ECU 100. The flow area of the return passage 10 for surplus fuel to the fuel is adjusted, whereby the amount of fuel discharged to the common rail 1 side can be adjusted to control the common rail pressure.

  Specifically, the target common rail pressure is set according to the engine operating conditions, and the common rail pressure is feedback-controlled through the pressure control valve 11 so that the common rail pressure detected by the rail pressure sensor 2 matches the target common rail pressure. It is configured.

  As shown in FIG. 2, the ECU 100 of the diesel engine E having the common rail 1 in the work vehicle (agricultural work machine) has three types of modes, a travel mode A, a normal work mode B, and a heavy work mode C in relation to the rotational speed and the output torque. The configuration has a control mode.

  The traveling mode A is droop control in which the output also varies with the variation of the engine speed. It is used when traveling without farming. For example, when the traveling speed is reduced or stopped by applying a brake, the engine speed decreases with an increase in the traveling load, so that the traveling speed can be safely reduced or stopped.

  The normal work mode B is isochronous control in which the engine speed is constant and the output is changed according to the load even when the load varies. It is used for normal farm work. For example, if it is a tractor, it is when the cultivated land is hard during plowing work and resistance is applied to the plowing blade. Is the time.

  In the heavy work mode C, in addition to the isochronous control in which the engine speed is constant and the output is changed according to the load even when the load fluctuates in the same manner as the normal work mode B, the engine speed is increased when the load is close to the limit. This is a control with heavy load control that increases In particular, it is used when farming near the load limit. For example, when plowing with a tractor, the engine output increases beyond the normal limit even when encountering hard cultivated land, so work can be performed efficiently without interruption. .

  These work modes A, B, and C are operations of a work mode changeover switch that can switch between the work modes A, B, and C, or a shift operation of a traveling speed change lever of a farm vehicle (tractor, combine, rice transplanter, etc.) Alternatively, it is configured to be switched by an on / off operation or the like of a work clutch (rotary if it is a tractor, and mowing part or threshing part if it is a combine).

  In diesel engine E, pilot injection that injects a small amount of fuel in a pulse manner prior to main injection makes it possible to shorten the ignition delay, reduce the knocking noise peculiar to diesel engine E, and reduce noise It has a simple structure.

  This pilot injection is performed only once or twice before the main injection. By using the accumulator fuel injection device of the common rail 1, pilot injection is performed according to the situation of the engine E. Thus, it becomes possible to reduce the noise and the generation of white smoke or black smoke due to incomplete combustion. Further, by performing pilot injection in which a small amount of fuel is pulse-injected prior to main injection, the amount of nitrogen oxides in the exhaust gas is reduced.

  FIG. 3 shows a side view of a tractor equipped with a diesel engine having the common rail 1 as described above, and FIG. 4 shows a plan view thereof. In the plan view, the cabin 14 shown in FIG. 3 is omitted.

  The tractor includes front wheels 12 and 12 and rear wheels 13 and 13 at the front and rear portions of the fuselage, and the rotational power of the engine E mounted on the front portion of the fuselage is appropriately decelerated by a transmission in the transmission case T so that the front wheels 12 , 12 and the rear wheels 13, 13.

  A steering handle 16 is supported on the handle post 15 in the cabin 14 at the center of the body, and a seat 17 is provided behind the steering handle 16. A forward / reverse lever 18 is provided below the steering handle 16 to switch the advancing direction of the aircraft to the front / rear direction. When the forward / reverse lever 18 is moved to the front side, the aircraft moves forward, and when it is moved backward, the aircraft moves backward.

  An accelerator lever 25 for adjusting the engine speed is provided on the opposite side of the forward / reverse lever 18 with the handle post 15 in between, and an accelerator for similarly adjusting the engine speed is provided at the right corner of the step floor 19. The pedal 23 and left and right brake pedals 24L, 24R for operating the left and right rear wheels 13, 13 are provided. A clutch pedal 20 is provided at the left corner of the step floor 19.

  The main transmission lever 26 is located at the left front portion of the seat 17, the auxiliary transmission lever 27 capable of selecting any of the low speed, medium speed, high speed and neutral positions is located behind the main transmission lever 26, and further on the right side thereof is the PTO transmission lever 28. Is provided. Further, on the right side of the seat 17, a position lever 29 for setting the height of the working machine 21 (rotary or the like), an automatic tilling lever 30 for automatically setting the tilling depth of the field, and the working machine 21 after these levers. The right-up switch 31 and the right-down switch 32 are arranged, and then the automatic horizontal switch 33 and the backup switch 34 of the work machine 21 are arranged. The backup switch 34 automatically raises the work machine 21 when the machine moves backward. The work machine 21 has a configuration in which a link 22 is connected to the rear of the machine body. The tractor performs work such as tillage in the field by driving the work machine 21 and running the machine body. 21a is a hydraulic cylinder which raises and lowers the working machine 21.

  FIG. 5 is a schematic diagram of intake and exhaust into the cylinder 5 of the engine, which is an embodiment of a four-cycle diesel engine. The air supercharged by the intake turbine 36 of the supercharger TB passes through the intake turbine 36 and the intercooler 37 from the air cleaner 35 and is sent from the intake manifold 38 into the cylinder 5. Reference numeral 39 is an intake valve, and 40 is a piston. A cam 48 opens and closes the intake and exhaust valves 39 and 41 via a rocker arm 49.

The exhaust gas combusted in the cylinder 5 passes through the exhaust manifold 42 from the exhaust valve 41 and is then discharged by driving the supercharger TB with the exhaust turbine 45 of the supercharger TB.
This diesel engine has an EGR (exhaust gas recirculation device) circuit 44 for mixing a part of the exhaust gas into the intake side. In the EGR circuit, a part of the exhaust gas is mixed into the intake side to reduce the amount of oxygen (O2), thereby reducing the generation of nitrogen oxide Nox. However, if the EGR rate increases too much, the amount of oxygen decreases and incomplete combustion occurs. Therefore, it is necessary to adjust the EGR rate according to the combustion state. This adjustment is performed by the EGR valve 43. The EGR circuit 44 connects between an exhaust pipe 55 on the downstream side of a post-processing device 46 described later and an intake pipe 56 on the upstream side of the intake turbine 36 of the supercharger TB. In addition, an EGR cooler 57 is provided in the middle of the EGR circuit 44. The amount of exhaust gas reduced into the cylinder 5 varies depending on how the EGR valve 43 is opened and closed.

  The exhaust gas that has passed through the exhaust turbine 45 passes through the aftertreatment device 46 and is discharged from the muffler 50 into the atmosphere. The post-processing device 46 includes an oxidation catalyst (DOC) 46a and a diesel particulate filter (DPF) 46b.

  The oxidation catalyst (DOC) 46a burns the incombustible material chamber, and the diesel particulate filter (DPF) is for collecting the granulated material (PM). The EGR valve 43 and the throttle valve 47 are controlled by the ECU 100. The post-treatment device 46 may be constituted only by a diesel particulate filter (DPF) 46b. If an oxidation catalyst (DOC) 46a is provided, the non-combustible material burns, so that the exhaust gas becomes cleaner.

  When the state of the exhaust gas is low (low load) continues for a long time, the DPF 46b has a concern that PM will accumulate and the capacity may be reduced. Therefore, a throttle valve 47 is provided on the lower side of the post-processing device 46, and when the throttle valve 47 is throttled, the pressure in the DPF 46b is kept high, so the temperature also rises. This makes it possible to regenerate the DPF 46b due to the influence of a high temperature. That is, when exhaust gas having a high temperature passes through the DPF 46b, the DPF 46b is regenerated by burning off the PM present in the DPF 46b.

  In the DPF regeneration operation for regenerating the DPF 46b, both the EGR valve 43 and the throttle valve 47 are throttled. Then, the gas temperature in the DPF 46b is raised together with the retard (retard) of the fuel injection timing so that the DPF 46b starts to be regenerated. This eliminates the need for fuel after-injection (in order to increase the exhaust gas temperature) or reduces the number of after-injections, so that the amount of fuel consumption can be suppressed and the environment is good.

  As a condition for performing such a DPF regeneration operation, the pressure sensor 52 is provided on the upper side of the post-processing device 46, the pressure sensor 53 is provided on the lower side of the post-processing device 46, and this pressure difference is a predetermined value or more. Then, since PM accumulates in the DPF 46b and becomes a resistance, the DPF regeneration operation is performed.

  Further, if the state in which the DPF regeneration operation is started continues for a long time, the DPF 46b is damaged due to an overheating state. Therefore, a temperature sensor 59 is provided on the lower side of the post-processing device 46, and when the value of the temperature sensor 59 exceeds a predetermined value, the DPF regeneration operation is stopped and the normal operation is resumed.

  In normal operation, the EGR valve 43 and the throttle valve 47 are simultaneously controlled to appropriately control the EGR amount. In particular, by having the throttle valve 47, the gas temperature in the DPF 46b can be kept high.

  The exhaust gas exhausted from the cylinder chamber 5 passes through the exhaust pipe 63 toward the exhaust turbine 45 of the supercharger TB, and forms a bypass path 64 in the middle of the exhaust pipe 63. A catalyst (DOC) 65 is provided. The second dioxide catalyst (DOC) 65 has a smaller size than the oxidation catalyst (DOC) 46a in the post-processing device 46.

  Then, when unburned fuel is flowed by post injection or the like, the throttle valve 66 is closed so that the exhaust gas flows to the bypass path 64. Then, a part of unburned fuel is oxidized at the second dioxide catalyst (DOC) 65 and the temperature of the unburned fuel is increased. Furthermore, since the remaining unburned fuel is oxidized by the oxidation catalyst (DOC) 46a and further rises in temperature, the combustion of the PM collected in the DPF 46b is promoted and the regeneration of the DPF 46b becomes possible quickly. .

Further, the throttle part 67 is provided immediately downstream of the second dioxide catalyst (DOC) 65. As a result, the exhaust resistance increases and the rise in the exhaust gas temperature is promoted.
Although described simultaneously in FIG. 5, a bypass circuit 68 is provided between the exhaust pipe 63 and the downstream side of the exhaust turbine 45 of the supercharger TB instead of the bypass circuit 64. May be. The bypass circuit 68 may be provided with the second dioxide catalyst (DOC) 65. 69 is a throttle valve. When the bypass circuit 68 is not used, the throttle valve 69 is closed.

  In addition, although not shown in the drawings, it is configured such that the water pool state of the fuel filter is determined by a water level sensor. When the water level is high and the sensor label determines that there is water, the water drain valve is opened, and water is controlled to be discharged until the label changes to no water.

  Specifically, if the water level position is high due to the label of the water level sensor and there is a possibility that water will be mixed into the fuel system, the water level label changes from 1 to 0, and water is drained until it is determined that the water level is low. Open the valve to drain the water. The discharged water is stored in a water tank. When the load state of the engine is determined by the ECU 100 and it is estimated that the load state is high and the NOx in the exhaust gas is high, the water in the water tank is injected into the CCB to reduce NOx. Like that. With such a configuration, it is possible to reduce NOx at low cost.

6A is a front view of the engine, and FIG. 6B is a side view.
The oxidation catalyst (DOC) 46a and the DPF 46b of the post-treatment device 46 described above are usually arranged in series. However, there is almost no space for mounting in a small work vehicle (tractor).

  In view of this, the DOC 46a and the DPF 46b are separated and mounted in an orthogonal manner. Specifically, the exhaust side of the supercharger TB and the DOC 46a are connected by the exhaust pipe 70, and the DPF 46b is disposed above the engine E in a form orthogonal to the DOC 46a. As a result, the DOC 46a and the DPF 46b can be arranged even in a narrow space (in the engine room).

  FIG. 7 illustrates the engine E, the DOC 46a, the DPF 46b, and the DPF valve 71. Even if the DOC 46a and the DPF 46b are provided, since a small amount of soot and PM remain in the exhaust gas, soot and the like are accumulated on the DPF valve 71 downstream of the DPF 46b. And if it accumulates to some extent, the operation | movement of the DPF valve 71 will worsen. Therefore, it is necessary to remove soot and the like accumulated in the DPF valve 71.

  When regenerating the DPF 46b, the DPF valve 71 is closed by a predetermined amount (not completely closed) to raise the temperature of the DPF 46b and burn the soot and PM in the DPF 46b. It is configured to remove soot and the like accumulated in the DPF valve 71 by operating.

  For example, once every 10 minutes during operation, the DPF valve 71 is opened and closed for a short time within a range that does not affect the engine performance, and soot or the like accumulated in the DPF valve 71 is dropped due to vibration during operation. Further, when the engine is started, the DPF valve 71 may be opened and closed for a short time when the key is turned on. Further, the DPF valve 71 may be opened and closed for a short time immediately after the engine is stopped. Thereby, the soot etc. which accumulated in DPF valve 71 can be removed efficiently.

  Further, a bypass circuit 72 that bypasses the DPF valve 71 is provided, and a pressure regulating valve 73 is provided in the bypass circuit 72. When regenerating the DPF 46b, the DPF valve 71 is fully closed. Then, the exhaust gas flows through the bypass circuit 72. Then, the pressure regulating valve 73 is automatically adjusted to control the pressure upstream of the DPF valve 71 to be constant. Thereby, there is little change with time due to accumulation of soot or the like on the DPF valve 71, and the DPF 46b can be regenerated with high accuracy.

  As shown in FIG. 8A, the DPF regeneration adjustment dial 74 is provided at an arbitrary position of the operation unit. This adjustment dial 74 determines fuel efficiency priority and DPF regeneration priority, and adjusts to what region post injection is set. The intermediate position of the adjustment dial 74 is in a normal standard state. As shown in FIG. 8B, the standard line moves when the adjustment dial 74 is adjusted.

  If fuel economy priority is selected by adjustment, post-injection is not performed and fuel consumption can be suppressed. If DPF regeneration priority is selected, fuel will be used for post-injection when the differential pressure before and after the DPF increases, but it will quickly enter the automatic regeneration mode and avoid manual regeneration as much as possible. become able to.

  In such regeneration of the DPF, since the detection is conventionally performed with a single parameter (for example, the differential pressure before and after the DPF), the accuracy is poor, and there is a scene in which useless fuel for post injection is used. Therefore, the configuration is such that the clogging of the DPF 46b is calculated from the four parameters of the operation time, the differential pressure across the DPF, the load factor map, and the continuous regeneration map. The integrated value of the soot accumulation amount is calculated as follows: (estimated value of soot from operation time) + (estimated value of soot from load factor) + (estimated value of soot from DPF differential pressure)-(reduction in continuous regeneration) Amount). Once the amount of soot accumulation can be calculated, the level and time required for the forced regeneration of the DPF 46b can be calculated and notified to the driver with high accuracy.

  In the case of agricultural machinery, it is often hated to regenerate the DPF during the season. Therefore, since it is desirable to perform it during the end of the season, the ash accumulation state of the DPF is diagnosed before long-term storage.

When the long-term storage button 75 provided in the driver's seat of a tractor, combine, rice transplanter or the like is turned on, the DPF 46b is forcibly regenerated and the Ash accumulation amount is estimated from the differential pressure after regeneration. From the time interval when the long-term storage button 75 is pressed, the remaining life time due to Ash clogging of the DPF is estimated. If it is determined that the limit value will be reached during the next season, display the necessity of maintenance. This makes it possible to clearly urge the maintenance to be performed during the end of the season. FIG. 9 shows this related diagram. The calculation formula for the estimated DPF remaining life due to clogging of Ash is:
(Pmax−P2) / (P2−P1) × Δt
It becomes.
If the estimated remaining life time is small with respect to Δt, the meter panel displays that Ash cleaning is performed during the season off period.

  Next, a configuration provided with the standard mode L1 and the low fuel consumption mode L2 shown in FIG. Switching between the standard mode L1 and the low fuel consumption mode L2 is performed by a fuel consumption mode switch provided in the driver's seat. Then, when the mode is switched to the low fuel consumption mode L2, the injection interval between the main injection and the after injection performed in the middle rotation region S1 or less is widened (FIG. 10 (b)), and the turbo timing is increased by delaying the injection timing. Configure as follows. Conventionally, although the fuel consumption mode for performing the control for advancing the injection timing has better fuel consumption performance than the standard mode, there has been a problem in that smoke generally tends to deteriorate.

  As described above, the timing of the after injection is delayed by widening the interval between the after injection and the main injection, and the exhaust temperature rises and the boost pressure rises by the combustion being pulled to the later stage. Therefore, smoke is reduced because the air flow rate is increased.

  If the injection interval is too wide in the standard mode, the after injection timing will be too late and smoke will increase, but in the fuel-efficient mode, the injection timing is advanced as a whole, so the injection interval Even after widening, the after-injection will not be too slow.

  The standard mode L3 and the low fuel consumption mode L4 shown in FIGS. 11 (a) and 11 (b) will be described. When the mode is switched to the low fuel consumption mode L4, the standard mode L3 is configured such that pilot injection and after injection are simultaneously added in a region higher than the high rotation / medium load region S2 that is single injection. Conventionally, the fuel economy mode that controls the advance of the injection timing has better fuel efficiency than the standard mode, but there is an adverse effect of the injection timing, and there is a tendency for noise deterioration and smoke deterioration especially in the single injection region near the rating. .

  Although the fuel economy is a little worse, it is possible to prevent the deterioration of fuel consumption even if noise and smoke are reduced by performing after injection that is effective in suppressing smoke and pilot injection that is effective in reducing noise and improving fuel efficiency. Thus, the fuel consumption improvement corresponding to the injection timing advance angle can be maintained. Since such control is performed only in the low fuel consumption mode, the adverse effect on the injection nozzle durability due to the increase in the number of injections is reduced.

  Next, as shown in FIG. 12A, the fuel efficiency mode of a turbo engine without an intercooler will be described. Compared to the standard full load curve L5, the torque in the full rotation high load range is reduced by 20%, the injection timing below the medium load range is advanced (2-4 degrees), and the output becomes the standard full load output On the other hand, a full load curve L6 (low fuel consumption mode) is set as a whole.

  As shown in FIG. 12B, the turbo engine without an intercooler increases the fuel injection amount even when the injection conditions such as the injection timing are constant, unlike the turbo engine with intercooler L8 and the naturally aspirated engine L9. . That is, there is a characteristic that NOx deteriorates as the turbo boost pressure increases (intake air temperature increases) (L7).

By utilizing such characteristics, it is possible to obtain an output curve with good fuel efficiency that does not deteriorate the overall NOx emission rate even if the injection timing is advanced by narrowing the output as a whole.
3 and 4 described above, the tractor has an accelerator pedal 23 that is operated by a foot and an accelerator lever 25 that is operated by a hand. The accelerator pedal 23 is the same as an automobile, and has a configuration in which the engine speed is increased only while the foot pedal is operated with a foot. Further, the accelerator lever 25 is operated by hand, and the engine rotation is maintained at that portion even if the hand is released from the accelerator lever 25.

  When the accelerator lever 25 is operated to maintain a constant engine speed, the effective range of the accelerator pedal 23 is from the engine speed set by the accelerator lever 25 to the no-load maximum speed. Configure as follows. In addition, a selection switch capable of selecting such a function is provided in the driver's seat. This makes it possible to variably adjust the engine speed depending on the work.

  As described above, when an engine equipped with a DPF is used for a combine, the engine and an electric motor are provided as a power source for the combine. And when discharging | emitting soot from the Glen tank of a combine, it is comprised so that selection of whether to use engine power or a motor is possible. When the soot is discharged by the motor, the DPF is forcibly regenerated during the soot discharge. This makes it possible to effectively use the soot discharge time for DPF regeneration, and to prevent the operation from being interrupted for the regeneration of the DPF.

In addition, the battery that drives the motor is charged by using the braking force of the vehicle, the turning force of the combine, or the braking force of the cutting, threshing unit, or the like.
FIG. 13 shows the parking brake lever 76 and its lever groove 77. In addition to the parking brake release position and the normal parking brake operating position, the parking brake lever 76 is provided with a position 78 for operating the parking brake and forcibly regenerating the DPF. Further, this position is provided in another groove 79 having a crank shape to prevent an operation error. As a result, the airframe stops only by operating the parking brake, and the DPF can be forcibly regenerated, so that the operability is improved.

  It can be used for farm vehicles such as tractors and combiners as well as general vehicles.

Overall configuration diagram of accumulator fuel injection system Diagram showing the relationship between engine speed and output torque in control mode Left side view of tractor Top view of tractor Schematic diagram of intake and exhaust systems (A) Front view of engine (b) Side view of engine Engine side view and exhaust system schematic diagram (A) Plan view of adjustment dial (b) Relationship diagram between engine speed and load factor Relationship between DPF usage time and differential pressure after DPF regeneration (A) Performance curve of engine speed and output (b) Schematic diagram of fuel injection timing (A) Performance curve of engine speed and output (b) Schematic diagram of fuel injection timing (A) Performance curve of engine speed and output (b) Relationship diagram between output and NOx emissions Plan view of parking brake lever and its groove

Explanation of symbols

PM Granulated material TB Supercharger 45 Exhaust turbine 46 Aftertreatment device 46a Oxidation catalyst (DOC)
46b Diesel particulate filter (DPF)
63 Exhaust pipe 64 Bypass path 65 Second dioxide catalyst 66 Throttle valve

Claims (2)

  An aftertreatment device (46) comprising a diesel particulate filter (46b) and an oxidation catalyst (46a) for collecting particulate matter (PM) in the exhaust gas is provided on the downstream side of the supercharger (TB). In the diesel engine, a bypass path (64) is formed in the exhaust pipe (63) upstream of the exhaust turbine (45) of the supercharger (TB), and the second dioxide catalyst (65) is provided in the bypass path (64). A diesel engine provided with a throttle valve (66) that adjusts the amount of exhaust gas that is provided and flows through the bypass path (64).   The diesel engine according to claim 1, wherein the second dioxide catalyst (65) has a smaller shape than an oxidation catalyst (46a) disposed downstream of the supercharger (TB).

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