JP2013096294A - Tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tractor including a diesel engine for predicting an accurate PM accumulation amount with an inexpensive constitution.SOLUTION: This tractor includes the diesel engine having a diesel particulate filter (46b) for collecting a particulate matter (PM) in the exhaust gas. The constitution of the tractor includes a second predicting means (L2) in an ECU (100). The second predicting means cranks the engine in the state that the fuel is not jetted, detects the pressures before and after a DPF (46b) with pressure sensors (58 and 53) and determines the differential pressure when the cranking engine speed becomes stable, and determines the PM amount accumulated in the DPF(46b) based on the differential pressure.

Description

  The present invention relates to a tractor equipped with a diesel engine equipped with a diesel particulate filter (DPF).

  In the case of regenerating a diesel particulate filter (DPF), in predicting the amount of soot accumulated in the DPF, the PM accumulation amount is predicted by detecting the hydrocarbon content in the fuel (for example, Patent Document 1). reference.).

JP 2005-2817 A

  In the technology as described above, a system for detecting the hydrocarbon content in the fuel is expensive. You must also consider the location of the system.

  The subject of this invention is providing the tractor carrying the diesel engine which eliminates the malfunctions mentioned above and predicts PM deposit amount with sufficient precision.

  The above object of the present invention is achieved by the following configuration.

  That is, according to the first aspect of the present invention, in a tractor equipped with a diesel engine equipped with a diesel particulate filter (46b) that collects particulate matter (PM) in the exhaust gas, the engine is operated without injecting fuel. When the cranking engine speed is stabilized, the pressure before and after the DPF (46b) is detected by the pressure sensor (58, 53) to obtain the differential pressure, and the differential pressure is accumulated in the DPF (46b). The second predicting means (L2) for determining the amount of PM that is present is configured in the ECU (100) as a tractor.

  According to the second aspect of the present invention, in a tractor equipped with a diesel engine equipped with a diesel particulate filter (46b) that collects particulate matter (PM) in exhaust gas, an air pump (69 ), And the pipe from the air pump (69) is connected to the upstream side of the DPF (46b), and the air pump (69) is connected to the upstream side of the DPF (46b) while the power is on and the engine is stopped. The pressure sensor (58, 53) detects the pressure before and after the DPF (46b) at this time to determine the differential pressure, and the PM amount accumulated in the DPF (46b) is determined from this differential pressure. 3 is a tractor characterized in that the prediction means (L3) is configured in the ECU (100).

  The invention according to claim 3 is characterized in that the ECU (100) includes first predicting means (L1) for predicting the amount of PM accumulated in the DPF (46b) from the fuel injection amount and the elapsed time. The tractor according to claim 1 or claim 2 is provided.

  Since the present invention is configured as described above, according to the first and second aspects of the invention, it is possible to accurately predict the amount of PM accumulated in the DPF 46b.

  In the invention of claim 3, the PM amount can be predicted and regenerated while the machine body is working.

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 Block diagram of PM amount prediction Schematic diagram of DPF exhaust system Engine performance chart Schematic diagram of DPF exhaust system Schematic diagram of DPF exhaust system Schematic diagram of an agricultural building Flow chart at startup Flow chart at start

  The best mode for carrying out the present invention will be described.

  In addition, although each Example described later is illustrated or described separately or mixed for easy understanding, these can be combined in various ways, and can be configured according to their description order and expression. -The action and the like are not limited, and there are of course cases where a synergistic effect is produced.

  FIG. 1 is an overall configuration diagram of a pressure accumulation type fuel injection device. The accumulator type 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 that accumulates 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, the fuel injection nozzle 6 and the like 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, and if it is a combine, the output fluctuates to maintain the rotation speed even when the harvest is heavy and the load increases during harvesting 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.

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

  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. Moreover, it is good also as a structure which provides the pressure sensor 58 between DOC46a and DPF46b instead of the pressure sensor 52. FIG.

  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.

  With the configuration as described above, an intake throttle is not required. In other words, since the intake side pressure is high in an engine with a supercharger, an exhaust throttle valve or an intake throttle is required to secure the amount of EGR gas, and control in conjunction with the EGR valve is required, but such a system is unnecessary. It becomes.

  Further, since the exhaust gas downstream of the DPF 46b is taken out, it is possible to prevent the performance deterioration caused by the dirt of the supercharger TB. And since EGR gas is cooled by the EGR cooler 57, an effect becomes large with respect to NOx reduction.

  As described above, in the DPF forced regeneration mode in which the regeneration operation of the DPF is performed, the exhaust throttle valve 47 is throttled and the EGR valve 43 is fully closed by ON-OFF control. Therefore, NO is increased because the exhaust gas is not reduced, and this NO is converted to NO2 by the oxidation catalyst (DOC) 46a, and regeneration of the DPF 46b is promoted.

  Further, when the engine rotation shifts to low idle during the forced regeneration of the DPF 46b, the EGR valve 43 is fully opened. Since the temperature sensor 59 is provided on the downstream side of the DPF 46b, it may be added to the condition that the detection value by the temperature sensor 59 has risen to a predetermined value or more.

  When the DPF 46b is forcibly regenerated by restricting the throttle valve 47, the engine speed is reduced to increase the supply oxygen amount, and the exhaust gas flow rate is decreased to increase the temperature easily. However, when the engine speed is changed to low idle or in the vicinity thereof during regeneration, soot burns rapidly due to an increase in the amount of supplied oxygen and a decrease in the flow velocity. As a result, the temperature may rise rapidly and the DPF 46b may be damaged. Therefore, it is necessary to manage the soot that the maximum temperature does not exceed the allowable temperature.

  For this reason, when the temperature sensor 59 exceeds a predetermined value, the engine speed is increased to a medium speed range. Accordingly, the flow rate of the exhaust gas is increased, so that the maximum temperature is lowered and the DPF 46b can be prevented from being damaged. Further, when the predetermined value of the temperature sensor 59 is controlled in the vicinity of the limit value, the DPF 46b can be efficiently regenerated.

  In order to increase the engine speed to the middle speed range, it may be configured to once increase to the maximum speed and then decelerate to the middle speed range, so that the exhaust gas once flows at the maximum speed. For example, it is possible to prevent the DPF 46b from being heated and exceeding the threshold temperature.

  Further, during the forced regeneration of the DPF 46b, when the engine speed is shifted to low idle as described above, the post-injection is interrupted, and then the engine speed is increased to the maximum speed and shifted to the medium speed range. Then, post-injection is resumed. Thereby, since the rapid rise in the exhaust gas temperature can be suppressed, damage to the DPF 46b can be prevented.

  When the differential pressure across the DPF 46b exceeds a predetermined value, the driver selects the regeneration mode of the DPF 46b after the operation with the selection switch 67, so that the DPF 46b is automatically regenerated. After the DPF 46b is regenerated, the engine is automatically stopped. To be configured. The differential pressure across the DPF 46b is monitored by pressure sensors 58 and 53. If the differential pressure across the DPF 46b immediately before the engine stops is equal to or greater than a predetermined value, a warning lamp or alarm notifies the driver, and the driver operates a switch (not shown) for regenerating the DPF 46b.

  Even when the engine key is in the cut position, since the regeneration mode is selected, the engine keeps rotating in the idling state and performs regeneration of the DPF 46b. When the differential pressure before and after the DPF 46b falls below a predetermined value, the engine is automatically stopped.

  Thus, even after the work is completed, the DPF 46b can be automatically regenerated and the engine can be stopped, so that the driver can leave the machine and perform other work.

  When the DPF 46b is regenerated, the intake side air may be sent from the pipe 61 to the upstream side of the DPF 46b as shown in FIG. That is, when the DPF 46b is regenerated, the valve 60 may be opened so that the intake air on the upstream side of the turbocharger TB having a large amount of oxygen is sent to the upstream side of the DPF 46b. Thereby, the reproduction efficiency is improved.

  Alternatively, the temperature of the DPF 46b may be monitored by the temperature sensors 62 and 59, and the temperature increase during regeneration may be confirmed in three steps. First, the intake is throttled (not shown), and the temperature rise in the throttled state of intake is confirmed. Next, the first post injection is performed to check the temperature rise. At this time, if the temperature before and after the DPF 46b does not reach 250 degrees, further temperature rise cannot be expected even if the second post-injection is performed. Therefore, the regeneration is temporarily interrupted. Of course, if it is 250 degrees or more, the second post injection is performed to regenerate the DPF 46b.

  As shown in FIG. 5, an air-fuel ratio sensor 63 is provided on the downstream side of the DPF 46b. When the post-injection is performed to regenerate the DPF 46b, if the fuel injection amount is too large, the fuel consumption is deteriorated. If the fuel injection amount is small, the temperature does not increase and the regeneration cannot be performed. Therefore, the injection amount is determined by feeding back the value of the air-fuel ratio sensor 63 to the ECU 100. As a result, the fuel efficiency becomes appropriate and the DPF 46b can be regenerated. Further, instead of the air-fuel ratio sensor 63, a pressure value in the intake manifold may be fed back.

  As shown in FIG. 6, the ECU 100 includes first PM deposition prediction means L1 that predicts the PM deposition amount in the DPF 46b. This predicts the amount of PM accumulated in the DPF 46b from the fuel injection amount (engine speed) and the elapsed time. However, the first predicting means L1 is not accurate, and an error occurs due to engine load fluctuation or the like.

  Therefore, the engine is cranked in a state in which fuel is not injected (a state in which the engine is not intentionally started), and the pressure before and after the DPF 46b at this time is detected by the pressure sensors 58 and 53 to obtain the differential pressure. When the engine speed is stabilized, the amount of PM accumulated in the DPF 46b is obtained from this differential pressure. The value of this PM amount is more accurate than that obtained from the first predicting means L1 because the present differential pressure is detected.

  Specifically, the second prediction means L2 having the horizontal axis as the differential pressure and the vertical axis as the PM amount is stored in the ECU 100, and is obtained from the second prediction means L2. The value obtained from the second predictor L2 is compared with the value obtained from the first predictor L1, and if they are substantially the same, the value of either the second predictor L2 or the first predictor L1 is controlled. Used for etc.

  On the other hand, when the value obtained from the second predictor L2 and the value obtained from the first predictor L1 are different (difference equal to or greater than a predetermined value), the value of the second predictor L2 is used.

  However, since the value of the second predicting means L2 is the state when cranking is performed without operating the engine, it cannot be determined when the engine is actually operating. The determination of the automatic regeneration execution of the DPF 46b during the actual engine operation is performed by the first prediction means L1. The value of the second predicting means L2 is used when it is desired to know the PM amount value with high accuracy before or after operation. Then, it is used for determination of manual regeneration execution.

  As a result, excessive fuel consumption due to excessive regeneration during manual regeneration can be suppressed, and problems such as oil dilution can be reduced.

  In obtaining the PM accumulation amount from the first predicting means L1, the correction is made by the engine temperature together with the differential pressure. In particular, when the engine temperature is high, it can be considered after heavy load operation. When the heavy load operation is performed, the exhaust gas temperature also rises, so that the PM in the DPF 46b is burned out, and the amount of accumulated PM is small. Therefore, although correction is performed by the temperature correction unit H1, the PM accumulation amount is subtracted by a predetermined ratio when the engine temperature is equal to or higher than a predetermined value for a predetermined time. As a result, the PM accumulation amount can be detected with high accuracy, so that excessive fuel consumption and oil dilution due to excessive regeneration operation can be prevented.

  In obtaining the PM accumulation amount from the second predicting means L2, the PM accumulation amount may be corrected from the fluctuation speed (differential value) of the engine speed and the pressure differential pressure before and after the DPF 46b.

  Although the maximum allowable PM deposition amount in the DPF 46b is determined in advance, exhaust gas may increase and PM may burn by increasing the idling speed. Therefore, when the idling speed is changed to a high value, the regeneration frequency of the DPF 46b can be lowered by increasing the upper limit of the PM allowable accumulation amount. Further, when changing the idling speed to a higher value, it is better to enter the manual regeneration region of the DPF 46b. When entering the manual regeneration area, it is basically necessary to interrupt and regenerate the work, but the work can be continued by changing the idling speed to a higher value. Further, the idling rotation speed may be changed to be higher when the set threshold value is exceeded, depending on the preference of the operator.

  FIG. 7 illustrates another method for accurately measuring the differential pressure across the DPF 46b, that is, for accurately detecting the PM deposition amount.

  An air pump 69 is provided at an arbitrary position of the machine body, and a pipe 70 from the air pump 69 is connected to the upstream side of the DPF 46b.

  While the engine is stopped (power is turned on), air is sent to the upstream side of the DPF 46 b by the air pump 69, and the differential pressure across the DPF 46 b at this time is measured by the pressure sensors 58 and 53. The PM amount accumulated in the DPF 46b is predicted by the third prediction means L3 from the differential pressure at this time. The third prediction means L3 is configured to store data measured in advance through experiments or the like.

  As a result, the amount of PM in the DPF 46b can be accurately detected, and wasteful DPF regeneration and fuel consumption can be suppressed.

  FIG. 8 shows a performance curve S1 in which the horizontal axis is the engine speed and the vertical axis is the output, and an iso-fuel consumption curve S2 and an equi-exhaust temperature line S3 are shown therein. When the DPF 46b is regenerated during normal operation (automatic regeneration), the DPF 46b automatically shifts to a point with a higher exhaust temperature (P → Q) even under operating conditions that generate the same output. Further, at the time of the transition, the fuel consumption is also taken into consideration (equal fuel consumption curve S2). Thereby, the regeneration of the DPF 46b can be efficiently performed, and the fuel consumption can be suppressed as compared with the conventional automatic regeneration.

  FIG. 9 shows a configuration in which the oxidation catalyst 46a arranged on the upstream side of the DPF 46b is divided into an upstream oxidation catalyst 46a1 and a downstream oxidation catalyst 46a2. A large amount of noble metal is supported on the upstream side oxidation catalyst 46a1, and the activation temperature is set to 200 ° C. The downstream oxidation catalyst 46a2 reduces the loading of the noble metal and the activation temperature is set to 250 ° C.

  During forced regeneration, unburned fuel contained in the exhaust gas adheres to the upstream oxidation catalyst 46a1 and the downstream oxidation catalyst 46a2. When the exhaust gas temperature reaches 200 ° C., the fuel undergoes an oxidation reaction in the upstream side oxidation catalyst 46a1 to raise the exhaust gas temperature. The exhaust gas temperature rises due to the oxidation heat of the upstream oxidation catalyst 46a1, thereby warming the downstream oxidation catalyst 46a2, and the downstream side oxidation catalyst 46a2 also starts the oxidation reaction.

  In this way, by arranging two types of oxidation catalysts having different noble metal loadings, the exhaust gas treatment performance of the oxidation catalyst can be improved without increasing the amount of noble metal used compared to the case of arranging one oxidation catalyst. It can be improved.

  FIG. 10 is a modification of FIG. 9, and arrows indicate the flow of exhaust gas. The downstream side oxidation catalyst 46a2 is coaxially arranged on the outer periphery of the upstream side oxidation catalyst 46a1. Such a configuration is effective for shortening the length of the oxidation catalyst.

  Reference numeral 71 in FIG. 11 denotes an agricultural building, in which a solar panel 72 is mounted on the roof. The agricultural building 71 has a power storage system 73. The electric power generated in the daytime is stored in the electric storage system 73, and the surplus electric power is sold to the electric power company. At night, the power stored in the power storage system 73 is used. For example, it is used for lighting necessary for cultivation of plants in the agricultural building 71. Further, when an agricultural machine such as a tractor is housed in the agricultural building 71, the heater 74 is heated by the power storage system 73, and the DPF 46b mounted on the tractor or the like is warmed and regenerated by this heat. Use. This enables low-cost agriculture.

  The flowchart in FIG. 12 relates to the start-up fuel injection amount control of the engine with the DPF. The angular acceleration of the engine at the start is determined, and if the angular acceleration is increasing, the injection amount at the start is reduced. When there is no change in angular acceleration, the starting injection amount is increased to a threshold value.

  As a result, the amount of PM emission is reduced by reducing black smoke at start-up, and the amount of PM deposited on the DPF can be reduced.

  FIG. 13 is a flowchart of the injection control at the start. In an agricultural machine such as a tractor equipped with a DPF, after-injection is added when detection of engine speed equal to or less than low idle rotation or change in engine rotation acceleration exceeding a certain level is detected. When the engine rotational speed is detected below the low idle speed or is not detected from a change in the engine rotational acceleration above a certain level, after-injection is stopped after a predetermined time (for example, after 5 seconds).

  As a result, when the engine speed (at the time of start) below the low idle rotation or the engine speed is accelerated, the amount of PM discharged increases rapidly, and at this time, the PM reduction is effective. By adding after-injection, the amount of PM emission is reduced, and early clogging of the DPF can be prevented.

PM Granulated material L1 First predictor L2 Second predictor L3 Third predictor 46b Diesel particulate filter (DPF)
53 Rear pressure sensor 58 Front pressure sensor 69 Air pump 70 Piping 100 ECU

Claims (3)

  In a tractor equipped with a diesel engine equipped with a diesel particulate filter (46b) that collects particulate matter (PM) in exhaust gas, the engine is cranked without fuel injection, and the cranking engine speed When the pressure becomes stable, the pressure before and after the DPF (46b) is detected by the pressure sensor (58, 53) to obtain a differential pressure, and from this differential pressure, a second predicting means for obtaining the amount of PM accumulated in the DPF (46b) ( A tractor characterized in that L2) is configured in the ECU (100).   In a tractor equipped with a diesel engine equipped with a diesel particulate filter (46b) that collects particulate matter (PM) in exhaust gas, an air pump (69) is provided at an arbitrary position of the airframe. 69) is connected to the upstream side of the DPF (46b), and the air pump (69) sends air to the upstream side of the DPF (46b) while the power is on and the engine is stopped. The pressure before and after the DPF (46b) is detected by a pressure sensor (58, 53) to determine a differential pressure, and from this differential pressure, a third predictor (L3) that determines the amount of PM deposited in the DPF (46b) ) In the ECU (100).   The first predicting means (L1) for predicting the amount of PM accumulated in the DPF (46b) from the fuel injection amount and the elapsed time is configured in the ECU (100). The described tractor.

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