JP2019044691A - Tractor - Google Patents

Abstract

To prevent sticking of an EGR valve.SOLUTION: A tractor is mounted with a diesel engine E which has an EGR circuit 44 for recirculating a part of exhaust gas to the intake side, and is provided with an EGR cooler 57 for cooling the exhaust gas recirculated to the EGR circuit 44 and an EGR valve 43 for regulating a recirculating amount of the exhaust gas. The EGR cooler 57 performs cooling with cooling water of the engine E and, when the temperature of the cooling water of the engine E is equal to or less than a predetermined temperature, closes the EGR valve 43 to temporarily suspend the recirculation of the exhaust gas to the intake side. Further, when the temperature of the cooling water of the engine E exceeds the predetermined temperature, the EGR cooler opens the EGR valve 43 to resume the function of recirculating a part of the exhaust gas to the intake side.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a tractor that is an agricultural machine, and more particularly to a tractor having a configuration that prevents an EGR valve of an EGR circuit from sticking.

  A technique for improving the accuracy of an EGR valve and performing opening / closing control in units of several degrees is disclosed (for example, see Patent Document 1).

JP 2013-209972 A

  The technique as described above has a problem that the valve itself is expensive for improving the accuracy of the EGR valve.

  The subject of this invention is providing the tractor 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, in a tractor equipped with a diesel engine E having an EGR circuit 44 that reduces part of the exhaust gas to the intake side, an EGR cooler that cools the exhaust gas reduced to the EGR circuit 44 57 and an EGR valve 43 that adjusts the reduction amount of exhaust gas, and the EGR cooler 57 is cooled by the cooling water of the engine E. When the cooling water temperature of the engine E is lower than a predetermined temperature, the EGR valve The tractor is characterized in that 43 is closed and the reduction of exhaust gas to the intake side is temporarily interrupted.

  According to a second aspect of the present invention, when the cooling water temperature of the engine E exceeds a predetermined temperature, the EGR valve 43 is opened to resume the function of reducing a part of the exhaust gas to the intake side. The tractor according to claim 1.

  According to a third aspect of the present invention, in a tractor equipped with a diesel engine E having an EGR circuit 44 that reduces part of the exhaust gas to the intake side, an EGR cooler 57 that cools the exhaust gas reduced to the EGR circuit 44; An EGR valve 43 for adjusting the reduction amount of the exhaust gas is provided, and the EGR cooler 57 is cooled by the cooling water of the engine E. After the engine is started, the EGR valve 43 is closed within a predetermined time and the intake of the exhaust gas The reduction to the side is temporarily interrupted, and even within a predetermined time after the engine is started, if the cooling water temperature of the engine E exceeds the predetermined temperature, the EGR valve 43 is opened and the exhaust gas is discharged. The tractor is characterized in that the portion is reduced to the intake side.

  Since the present invention is configured as described above, the EGR valve 43 can be prevented from sticking in the first to third aspects of the invention.

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 Diagram showing changes in elapsed time and EGR rate Flow chart of EGR opening correction Intercooler abnormality detection flowchart Diagram showing engine load factor and intake air temperature in intake manifold Diagram showing the relationship between elapsed time and PM deposition Perspective view of engine, aftertreatment device and bonnet

  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 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. 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 increases. 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. As a result, the flow rate of the exhaust gas is increased, so that the maximum temperature is lowered and damage to the DPF 46b can be prevented. 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 consumption 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.

  When regenerating the DPF 46b as described above, in the case of a plurality of cylinders, the combustion of some cylinders may be stopped. Thus, by stopping the combustion of some cylinders, the exhaust temperature may be increased by increasing the load per cylinder even if the engine friction is the same.

  In the EGR valve 43, soot and HC adhere and become a liquid that is integrated with moisture such as condensation. In such a state, the EGR valve 43 operates. However, when the engine is stopped and the engine is cooled, the viscous liquid is fixed, and when the engine is restarted, the EGR valve 43 may not move. In order to solve such a problem, the EGR valve 43 is provided with a cleaning function. That is, the EGR valve 43 is forcibly operated during the after-run after the engine is stopped to remove the viscous liquid, so that the EGR valve 43 does not stick even if the engine is cooled.

  The EGR cooler 57 is cooled by engine cooling water. Reference numeral 80a is a cooling water supply pipe, and reference numeral 80b is a cooling water drain pipe. When exhaust gas is cooled with engine cooling water, if the temperature of the cooling water is too low, dew condensation water is generated from the exhaust gas, and if the dew condensation water and soot are mixed and adhere to the EGR valve 43, the EGR valve 43 When the movement becomes worse and the engine is stopped and the engine is cooled, the EGR valve 43 is fixed by a mixture of condensed water and soot.

  Therefore, when the engine coolant temperature is equal to or lower than a predetermined temperature (less than 60 degrees), the EGR valve 43 is closed to temporarily interrupt the function of reducing part of the exhaust gas to the intake side. When the engine coolant temperature becomes 60 ° C. or more, the EGR valve 43 is opened to resume the function of reducing a part of the exhaust gas to the intake side. Thereby, the malfunction that the EGR valve 43 adheres and cannot operate | move can be prevented.

  In addition, after the engine is started, the EGR valve 43 is closed within a predetermined time period to temporarily interrupt the function of reducing a part of the exhaust gas to the intake side. And if the time after engine start exceeds 10 minutes, it will be set as the structure which opens the EGR valve 43 and resumes the function to reduce a part of exhaust gas to the intake side. The predetermined time is about 10 minutes, but it varies depending on the engine displacement.

  Even within the predetermined time after the engine is started, if the coolant temperature of the engine E exceeds the predetermined temperature, the EGR valve 43 is opened to reduce part of the exhaust gas to the intake side.

  An O2 sensor 81 (FIG. 5) is provided on the upstream side of the post-processing device 46, and the numerical value from the O2 sensor 81 is constantly monitored. Then, the EGR rate R1 estimated from the change in O2 (oxygen) at the determined rotation / load is calculated.

  The EGR rate R2 with respect to the operation time obtained in advance experimentally is compared with the EGR rate R1, the smaller EGR rate is adopted, and then the EGR rate opening correction amount is calculated to perform correction (see FIG. 6, FIG. 7).

  Although the EGR rate obtained from the current O2 sensor 81 is an accurate value, a measurement error occurs due to a difference in environment and driving conditions. Therefore, the opening degree is corrected in comparison with the EGR rate change obtained experimentally in advance. Thus, since it is possible to prevent an excessive or excessive correction, a stable EGR opening degree correction can be performed.

  A temperature sensor 38 a is provided in the intake manifold 38 and a temperature sensor 42 a is provided in the exhaust manifold 42. If the intake air temperature (value of the temperature sensor 38a) in the intake manifold 38 is higher than the load factor / exhaust temperature (value of the temperature sensor 42a), it is determined that an abnormality has occurred in the cooling of the intercooler 37. The meter panel is configured to display an abnormality / inspection display (FIG. 9). FIG. 8 shows correction of the threshold line. When the current exhaust gas temperature is higher than the reference exhaust gas temperature, the threshold line is corrected to plus (+). If the current exhaust temperature is lower than the reference exhaust temperature, the threshold line is corrected to minus (−). It is determined whether or not the current intake air temperature is higher than the threshold line.

  Normally, the intake air temperature after passing through the intercooler 37 increases as the load factor increases, but the intake air temperature in the intake manifold 38 does not necessarily increase as the load factor increases. This is because it is affected by the EGR gas.

  If the intake air temperature (the value of the temperature sensor 38a) relative to the exhaust temperature (the value of the temperature sensor 42a) is higher than expected with the load factor as a reference, there is a possibility that an abnormality has occurred in the cooling of the intercooler 37. Yes, prompt inspection work. As a result, the abnormal state of the intercooler 37 can be reliably determined early.

  Next, another method for regenerating the DPF 46b will be described.

  Conventionally, in a configuration in which regeneration is started by selecting the maximum (Max) of either the PM accumulation amount or the operation time, there is a possibility that regeneration needs to be continuously performed in a short time.

  Therefore, the configuration is as follows. In a configuration in which DPF regeneration is performed by selecting either the predicted PM accumulation amount or the operation time maximum (Max), if the threshold value due to operation time is reached earlier than the regeneration threshold value of the predicted PM accumulation amount, the estimated PM accumulation amount The reproduction is not carried out until the average DPF regeneration interval Xave performed in the above or the minimum (Min) selected time of the regulation time Y is selected. As indicated by F in FIG. 10, when the maximum (Max) is selected from the predicted PM accumulation amount and the accumulated operation time, regeneration based on the accumulated operation time can occur continuously after the regeneration based on the estimated PM accumulation amount is completed.

  Therefore, even if the regeneration time due to the driving time is reached, continuous regeneration is performed by waiting for the regeneration until the average regeneration interval time Xave or the regulation time Y (if the regeneration interval is too long, it is limited by the specified time). Can be prevented from being implemented.

  As a result, even if the regeneration threshold value due to the operation time is reached, if the operation time from the previous regeneration is too short, the regeneration is not performed, so that the regeneration at a time that is not actually necessary can be forgotten. .

  Further, when the manual regeneration cycle is shorter than the past automatic regeneration cycle (for example, 50% of the automatic regeneration cycle), if it is determined that there is an abnormality together with the past average load factor, a display prompting inspection is performed. Thereby, abnormality can be detected at an early stage, and troubles in the engine main body and the aftertreatment device can be prevented in advance.

  FIG. 11 shows the shape of the hood 82 that covers the engine E. A post-processing device 46 is mounted above the rear portion of the engine E. The post-processing device 46 is a DOC simple substance, a DPF simple substance, a combination of DOC and DPF, or the like. Moreover, SCR may be sufficient. The bonnet 82 covers the upper side of the engine E, but is configured to be as close to the engine E as possible. And in the part in which the post-processing apparatus 46 is mounted, the recessed part 82a is formed in the bonnet 82 so that the substantially upper half of the post-processing apparatus 46 may enter. By forming the recess 82a in the bonnet 82, the height H is generated, but there is no problem because it is within a limited range. Further, a net-like heat exhaust port 82b is provided.

  Thereby, the bonnet 82 part can be comprised compactly, and maintainability improves. Further, by providing the net-like heat exhaust port 82b, it is possible to prevent heat from being accumulated around the post-processing device 46.

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

E Engine 43 EGR valve 44 EGR circuit 57 EGR cooler

Claims (3)

  In a tractor equipped with a diesel engine (E) having an EGR circuit (44) for reducing part of the exhaust gas to the intake side, an EGR cooler (57) for cooling the exhaust gas reduced to the EGR circuit (44); When an EGR valve (43) for adjusting the amount of exhaust gas reduction is provided, and the EGR cooler (57) is cooled by the cooling water of the engine (E), and the cooling water temperature of the engine (E) is below a predetermined temperature The tractor is characterized in that the EGR valve (43) is closed to temporarily stop the reduction of the exhaust gas to the intake side.   The configuration is such that when the cooling water temperature of the engine (E) exceeds a predetermined temperature, the EGR valve (43) is opened to resume the function of reducing a part of the exhaust gas to the intake side. The tractor according to 1.   In a tractor equipped with a diesel engine (E) having an EGR circuit (44) for reducing part of the exhaust gas to the intake side, an EGR cooler (57) for cooling the exhaust gas reduced to the EGR circuit (44); An EGR valve (43) for adjusting the reduction amount of the exhaust gas is provided, and the EGR cooler (57) is cooled by the cooling water of the engine (E). After the engine starts, the EGR valve (43 ) Is closed, and the reduction of exhaust gas to the intake side is temporarily interrupted. Even within a predetermined time after the engine is started, if the cooling water temperature of the engine (E) exceeds the predetermined temperature, A tractor characterized in that the EGR valve (43) is opened to reduce part of the exhaust gas to the intake side.

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