JP2019058130A - Tractor - Google Patents

Abstract

To provide a tractor capable of performing effectively filter reproduction of an exhaust gas purification device of a diesel engine, in the tractor equipped with an implement.SOLUTION: In a tractor loaded with an exhaust gas purification device of a diesel engine E for performing filter reproduction 68 automatically by monitoring clogging of a diesel particulate filter, automatic filter reproduction 68 is not performed during an auto lift function time when an implement is lifted by performing turning operation of a steering handle. The automatic filter reproduction 68 is performed, while auto acceleration function works, for raising rotation of the engine E at a high load time.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a tractor equipped with a diesel engine, and more particularly to a tractor equipped with an exhaust gas purification device for mounting a working machine on an airframe and purifying exhaust gas.

  A diesel engine is equipped with an exhaust gas purification device provided with a diesel particulate filter (DPF) that collects particulate matter (PM) contained in exhaust gas. A filter regeneration process is necessary to burn the particulate matter deposited on the DPF to regenerate the DPF.

  The filter regeneration process is a process of burning and reducing particulate matter accumulated in the DPF by raising the exhaust temperature of the diesel engine, and is performed in a state where the diesel engine discharges high-temperature exhaust gas under high load conditions. There is a tendency that the noise is high and the amount of exhaust gas is also large.

  For this reason, in patent document 1, it is registered in the map data mounted on the work vehicle as a filter regeneration prohibited area in the vicinity of a livestock shed etc., and control is performed so as not to perform filter regeneration processing while working in the filter regeneration prohibited area. .

  According to the patent document 1, "the filter regeneration control device 25 normally operates the injector, the common rail, and the supply pump based on control signals such as the operation amount of the accelerator lever, the operation amount of the accelerator pedal, the crank position, and the cam position. Control is etc. ”(page 5, lines 7 to 9), and it is not described specifically at what timing the filter regeneration processing is to be performed.

Patent No. 5699099 gazette

  The filter regeneration process in the exhaust gas purification device of the diesel engine is performed in a state where the exhaust gas is at high temperature, but when the tractor is traveling on the road or under a light load operation, the diesel engine is driven by middle rotation and the exhaust gas becomes high temperature In some cases, even if the filter regeneration treatment is performed, the particulate matter deposited on the DPF can not be effectively reduced by combustion.

  An object of the present invention is to allow a diesel engine exhaust gas purification apparatus to effectively perform filter regeneration processing in a tractor equipped with a work machine.

  The object of the present invention is solved by the following technical means.

  The invention according to claim 1 is a tractor equipped with an exhaust gas purification device for a diesel engine E that automatically performs filter regeneration processing by monitoring clogging of the diesel particulate filter 46b and performing operation when the steering handle 16 is turned. The automatic filter regenerating process 68 is not performed at the time of the automatic lift function in which the machine 21 ascends.

  According to the second aspect of the present invention, there is provided a tractor equipped with an exhaust gas purification device for a diesel engine E that automatically performs filter regeneration processing by monitoring clogging of the diesel particulate filter 46b and rotating the engine E at high load. A tractor is characterized in that the filter regeneration process 68 is performed while the ascending auto acceleration function is acting.

  The invention of claim 3 is characterized in that, when the work machine 21 is a cultivator, the filter regeneration process 68 of the diesel particulate filter 46b is performed at the time of tillage operation. It shall be the tractor described in Section.

  In the invention of claim 1, the diesel particulate filter 46b is automatically subjected to filter regeneration processing before clogging is monitored and the limit is reached, but at the time of the auto lift function, the engine load is lightened and the temperature of exhaust gas is lowered. Therefore, filter regeneration processing such as post injection is not performed, and wasteful consumption of fuel and dilution of engine oil are prevented.

  In the invention of claim 2, since the filter regeneration process is performed when the auto acceleration function works and the engine E is rotating at a high speed, the particulate matter accumulated in the diesel particulate filter 46b due to the high temperature of the exhaust gas An effective filter regeneration process is performed.

  In the invention of claim 3, in addition to the effect of any one of claims 1 or 2, when the tilling work is performed by the working machine 21, the engine E has a high load and the temperature of the exhaust gas is high, A filter regeneration process for burning the particulate matter deposited on the particulate filter 46b is effectively performed.

Overall Configuration of Accumulator Fuel Injection System Diagram showing the relationship between engine speed and output torque in the control mode Left side view of the tractor Top view of the tractor Schematic of intake and exhaust system Control block diagram of filter regeneration process

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

  FIG. 1 is an entire configuration diagram of a pressure accumulation type fuel injection device. The accumulator fuel injection system is applied to, for example, a multi-cylinder diesel engine. Then, the accumulator fuel injection system pressurizes the common rail 1 for accumulating high pressure fuel equivalent to the injection pressure, the rail pressure sensor 2 attached to the common rail 1, and the fuel drawn up from the fuel tank 3 to the common rail 1. Control unit (ECU) for controlling the operation of the high pressure pump 4, the fuel injection nozzle 6 for injecting high pressure fuel accumulated in the common rail 1 into the cylinder 5 of the engine E, the high pressure pump 4 and the fuel injection nozzle 6 It consists of 100 mag. The ECU is an abbreviation of an engine control unit.

  As described above, the common rail 1 injects the fuel to the cylinders 5 of the engine E, and makes the fuel supply pressure required.

  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 by the suction passage, and the high pressure fuel pressurized by the high pressure pump 4 is conducted to the common rail 1 by the discharge passage 8 It is stored.

  The high-pressure fuel in the common rail 1 is supplied to the fuel injection nozzles 6 for the number of cylinders by the high-pressure fuel supply passages 9, and the fuel injection nozzles 6 operate based on the command from the ECU 100. The surplus fuel (return fuel) at each fuel injection nozzle 6 is introduced into the five chambers and is introduced to the common return passage 10 a by each return passage 10 and returned to the fuel tank 3.

  The high pressure pump 4 is provided with a pressure control valve 11 for controlling the fuel pressure in the common rail 1 (common rail pressure). The pressure control valve 11 receives the fuel tank 3 from the high pressure pump 4 according to a duty signal from the ECU 100. The flow passage area of the return passage 10 for surplus fuel is adjusted, whereby the fuel discharge amount 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 engine operating conditions, and the common rail pressure is feedback controlled via 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 has composition.

  As shown in FIG. 2, the ECU 100 of the diesel engine E having the common rail 1 in a work vehicle (agriculture work machine) has a droop control A (traveling mode A) and an isochronous control B (normal operation mode B) in relation to the rotational speed and output torque. And heavy load control C (heavy work mode C).

  In the droop control A (traveling mode A), the output also fluctuates due to the fluctuation of the engine speed. It is used when traveling without traveling in farming. For example, when the traveling speed is reduced or stopped by applying a brake, the engine rotational speed decreases with an increase in the traveling load, so that the traveling speed can be safely reduced or stopped.

  The isochronous control B (normal operation mode B) is isochronous control in which the engine speed is constant even if the load changes and the output is changed according to the load. It is used when performing normal agricultural work. For example, in the case of a tractor, when the cultivated land is hard and resistance is applied to the cultivating blade at the time of tillage work, and when it is a combine, the output fluctuates and the number of rotations is maintained even when the load is increased It is time.

  Heavy load control C (heavy work mode C) is the same as isochronous control (normal work mode B), in addition to isochronous control that changes the output according to the load at constant engine speed even if the load changes, and load limit It is control which added heavy load control which raises the rotation speed and raises the output as it gets close. In particular, it is used when performing farming work near the load limit. For example, when carrying out a cultivating operation with a tractor, even if hard cultivated land is encountered, the engine output increases beyond the normal limit, so work can be performed without interruption, enabling efficient work. .

  In these operation modes A, B and C, operation of each operation mode changeover switch capable of switching each operation mode A, B and C, or shift operation of a traveling shift lever of an agricultural work vehicle (tractor, combine, rice transplanter, etc.) Or, it is configured to be switched by the on / off operation or the like of the working clutch (in the case of a tractor, it is a rotary, and in the case of a combine, it is a reaper or a threshing part).

  Furthermore, as shown in FIG. 6, the steering angle sensor 16a that outputs the steering angle of the steering wheel 16 as a control signal input to the control device 100, the auto accelerator switch 65, the auto lift switch 66, and the extension of the hydraulic cylinder 21a. There is provided a hydraulic cylinder sensor 67 for detecting the

  The control device 100 is provided with a front pressure sensor 52 and a rear pressure sensor 53 etc. of the diesel particulate filter 46b, and the differential pressure between the front pressure sensor 52 and the rear pressure sensor 53 detects clogging of the diesel particulate filter 46b. The rotation control signal is output to the filter regeneration processing 68 described later.

  The auto accelerator switch 65 is a switch that enables high output of the diesel engine E in isochronous control in the normal operation mode B and heavy load control in the heavy operation mode C. The auto lift switch 66 is a switch that extends the hydraulic cylinder 21a and raises the work machine 21 when the steering handle 16 is turned a predetermined angle or more, and the steering angle of the steering handle 16 is input to the control device 100 by the steering angle sensor 16a. The extension of the hydraulic cylinder 21 a is input to the control device 100 by the hydraulic cylinder sensor 67.

  The filter regeneration process 68 of the diesel particulate filter (DPF) 46b, which will be described later, is a process of monitoring clogging of the DPF 46b and incinerating particulate matter, which is carried out during work, but the auto accelerator switch 65 is turned on. When the engine E is at high output, the hydraulic cylinder 21a is extended and the working machine 21 is lifted, and the engine E is not loaded when the load is light.

  In the diesel engine E, by performing pilot injection in which a small amount of fuel is injected in a pulsed manner prior to the main injection, the ignition delay can be shortened, knock noise specific to the diesel engine E can be reduced, and noise can be reduced. Configuration.

  Although this pilot injection was performed once or twice before the main injection, by using the pressure accumulation type fuel injection device of the common rail 1, the pilot injection according to the condition of the engine E It is possible to reduce the generation of white smoke or black smoke due to noise reduction and incomplete combustion. In addition, by performing pilot injection in which a small amount of fuel is injected in a pulsed manner prior to the main injection, the amount of nitrogen oxides in the exhaust gas can be reduced.

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

  The tractor is provided with front wheels 12, 12 and rear wheels 13, 13 on the front and back of the machine body, and the rotational power of the engine E mounted on the front of the machine body is appropriately decelerated by the transmission in the transmission case T. , 12 and the rear wheels 13, 13.

  A steering wheel 16 is supported at the steering wheel post 15 in the cabin 14 at the center of the airframe, and a seat 17 is provided behind the steering wheel 16. Below the steering wheel 16, a forward / backward advancing lever 18 is provided to switch the traveling direction of the vehicle in the front-rear direction. When the forward and reverse lever 18 is moved forward, the machine moves forward, and when it is moved backward, the vehicle moves backward. The steering angle of the steering wheel 16 is detected by a steering angle sensor 16a (FIG. 6).

  In addition, an accelerator lever 25 for adjusting the engine speed is provided on the opposite side of the front-back lever 18 across the steering wheel post 15, and an accelerator for adjusting the engine speed is similarly provided at the right corner of the step floor 19. The pedals 23 and left and right brake pedals 24L, 24R for operating the brakes on 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 shift lever 26 is located on the left front side of the seat 17 and there is an auxiliary shift lever 27 located behind the PTO shift lever 27 which can select any one of low, medium, high and neutral positions. Is provided. Further, on the right side of the seat 17, there are provided a position lever 29 for setting the height of the working machine 21 (rotary etc.), an automatic plowing depth lever 30 for automatically setting the tillage depth of the field, The right raising switch 31 and the right lowering switch 32 are disposed, and thereafter, the automatic horizontal switch 33 and the automatic lift switch 34 of the working machine 21 are disposed. The auto lift switch 34 automatically raises the work implement 21 when the machine turns or reverses. The work implement 21 is configured to be connected to the rear of the machine by a link 22. The tractor drives the working machine 21 to travel the machine to perform operations such as tilling in a field. Reference numeral 21 a denotes a hydraulic cylinder that raises and lowers the work machine 21.

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

  The exhaust gas burned in the cylinder 5 is configured to be discharged by driving the supercharger TB by the exhaust turbine 45 of the supercharger TB after passing through the exhaust manifold 42 from the exhaust valve 41.

  This diesel engine has an EGR (exhaust gas recirculation device) circuit 44 for mixing a part of the exhaust gas on the intake side. By mixing a part of the exhaust gas into the intake side in the EGR circuit, the amount of oxygen (O2) is reduced to reduce the generation of nitrogen oxide NOx. However, if the EGR rate (exhaust gas recirculation rate) increases too much, the amount of oxygen decreases and the combustion becomes incomplete, so it is necessary to adjust the EGR rate depending on the combustion state. This adjustment is performed by the EGR valve 43. The EGR circuit 44 connects between an exhaust pipe 55 downstream of the post-processing device 46 described later and a suction pipe 56 upstream of the intake turbine 36 of the turbocharger TB. Further, an EGR cooler 57 is provided in the middle of the EGR circuit 44. Depending on the degree of opening and closing of the EGR valve 43, the amount of reduction of the exhaust gas into the cylinder 5 changes.

  Exhaust gas after passing through the exhaust turbine 45 passes through the aftertreatment device 46 and is exhausted from the muffler 50 to the atmosphere. The aftertreatment device 46 is composed of an oxidation catalyst (DOC) 46a and a diesel particulate filter (DPF) 46b.

  The oxidation catalyst (DOC) is for burning non-combustible substances, and the diesel particulate filter (DPF) is for trapping particulate matter (PM). The EGR valve 43 and the throttle valve 47 are controlled by the filter regeneration process 68 of the ECU 100. The post-processing device 46 may be composed only of the DPF 46b. If the oxidation catalyst (DOC) 46a is provided, the non-combustible substance burns, resulting in a cleaner exhaust gas.

  In the DPF 46b, when the exhaust gas temperature is low (low load) for a long time, PM may be accumulated, and the performance may be reduced. Therefore, a throttling valve 47 is provided on the lower side of the post-processing device 46. When the throttling valve 47 is squeezed, the pressure in the DPF 46b is held high, and the temperature also becomes high. As a result, the DPF 46b can be regenerated due to the influence of high temperature. That is, when the high temperature exhaust gas passes through the DPF 46b, the PM present in the DPF 46b is burned off to regenerate the DPF 46b.

  In the filter regeneration process 68 for regenerating the DPF 46b, both of the EGR valve 43 and the throttle valve 47 are throttled. Then, the gas temperature in the DPF 46 b is raised together with the retard (retarding angle) of the fuel injection timing so that the DPF 46 b enters the filter regeneration process. This makes it possible to eliminate the need for after-injection of fuel (to raise the temperature of the exhaust gas) or to reduce the number of after-injections, so that the amount of fuel consumption can be reduced, which is good for the environment.

  As conditions for performing such filter regeneration processing, the front pressure sensor 52 is provided on the upper side of the post-processing device 46, and the rear pressure sensor 53 is provided on the lower side of the post-processing device 46, and this pressure difference is a predetermined value. If it becomes above, since PM accumulates in DPF 46b and it is in the state of resistance, filter regeneration processing is performed. Further, instead of the front pressure sensor 52, an intermediate pressure sensor 58 may be provided between the DOC 46a and the DPF 46b.

  In addition, if the filter regeneration processing continues for a long time, the filter is overheated and the DPF 46b is damaged. 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 filter regeneration process 68 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 maintained high.

  The configuration as described above eliminates the need for the intake throttle. That is, since the intake side pressure is high in an engine with a supercharger, an exhaust throttle valve or intake throttle is required to secure the amount of EGR gas, and control interlocking with the EGR valve is required, but such a system is unnecessary. It becomes.

  In addition, since the turbocharger TB takes out the exhaust gas upstream of the DPF 46b, the performance deterioration due to the contamination of the turbocharger TB can be prevented. Then, since the EGR gas is cooled by the EGR cooler 57, the effect on NOx reduction is enhanced.

  As described above, in the DPF forced regeneration mode in which the filter regeneration process is performed, the exhaust throttle valve 47 is narrowed, and the EGR valve 43 is fully closed by the 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.

  Since the filter regeneration process 68 is efficiently performed in a state where the temperature of the exhaust gas is high, the auto accelerator switch 65 is turned on to carry out the engine E under heavy load, and the hydraulic cylinder 21a is expanded to perform work. When the load on the engine E is light as the aircraft 21 rises, it is not implemented.

  Further, since the temperature sensor 59 is provided on the downstream side of the DPF 46b, it may be added to the condition for performing filter regeneration processing in which the detected value by the temperature sensor 59 is increased to a predetermined value or more.

  In addition, when stopping the traveling of the airframe and performing the filter regeneration process of the DPF 46b, the engine rotational speed is set to a low rotational speed to increase the supplied oxygen amount, and the throttle valve 47 is squeezed to decrease the exhaust gas flow rate. It was easy to raise the temperature. However, if the engine speed is changed to or near low idle during regeneration, the particulate matter (PM) burns rapidly due to the increase of the supplied oxygen amount and the decrease of the flow velocity. As a result, the temperature may rise rapidly and the DPF 46 b may be damaged. Therefore, it is necessary to manage the amount of PM so that the maximum temperature does not exceed the allowable temperature.

  For this purpose, when the temperature sensor 59 exceeds a predetermined value, the engine speed is increased to the middle speed range. As a result, the exhaust gas flow rate is increased, so the maximum temperature is reduced, and damage to the DPF 46b can be prevented. In addition, when the value of the predetermined value of the temperature sensor 59 is controlled in the vicinity of the limit value, the filter regeneration process of the DPF 46b can be efficiently performed.

  In order to raise the engine speed to the medium speed range, the engine speed may be once raised to the maximum speed and then decelerated to the medium speed range, whereby the exhaust gas flows once at the maximum speed, so preheating is possible. Thus, the DPF 46b can be prevented from being heated and exceeding the threshold temperature.

  Also, in the filter regeneration process of the DPF 46b, when shifting the engine speed 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. The post injection is restarted at As a result, a rapid rise in the exhaust gas temperature can be suppressed, and damage to the DPF 46b can be prevented.

  When the differential pressure before and after the DPF 46b becomes equal to or higher than a predetermined value and the operation is finished, the driver selects the filter regeneration processing mode of the DPF 46b with the selection switch 67 after the operation, thereby automatically performing the filter regeneration processing 68 of the DPF 46b. After the regeneration process, the engine is automatically stopped. That is, the differential pressure before and after the DPF 46 b is monitored by the differential pressure between the front pressure sensor 52 and the rear pressure sensor 53. If the pressure difference across DPF 46b immediately before the stop of the engine is equal to or more than a predetermined value, a warning lamp or an alarm is notified, and the driver operates a switch (not shown) that regenerates the DPF 46b.

  Then, even when the engine key is in the off position, the engine is kept idling in the idling state by selecting the regeneration mode, and the filter regeneration process of the DPF 46b is executed. When the differential pressure before and after the DPF 46b becomes equal to or less than a predetermined value, the engine is automatically stopped.

  As a result, the regeneration of the DPF 46b and the engine stop can be performed automatically even after the work is completed, so that the driver can perform other work away from the machine.

  If the filter regeneration process after turning off the engine key is frequent or the engine is rapidly stopped during heating, a work method or engine suitable for the filter regeneration process from the control device 100 to the portable terminal of the tractor owner It is good to notify the timing of the stop.

  When the post-injection is performed to perform the filter regeneration process of the DPF 46b, as shown in FIG. 5, the air on the intake side may be sent from the pipe line 61 to the upstream side of the DPF 46b. That is, when the regeneration of the DPF 46b is performed, the valve 60 may be opened to send the air on the intake side upstream of the turbocharger TB having a large amount of oxygen to the upstream side of the DPF 46b. This improves the reproduction efficiency.

  Also, the temperature of the DPF 46b may be monitored by the temperature sensors 62, 59, and the temperature rise during regeneration may be confirmed in three steps. First, intake throttling (not shown) is performed, and temperature rise confirmation in the throttling state of the intake is performed. Next, the first post injection is performed to check the temperature rise. At this point in time, if the temperature before and after DPF 46b has not reached 250 ° C., no further temperature rise can be expected even if the second post injection is performed, so regeneration is temporarily interrupted. Of course, if the temperature is 250 degrees or more, the second post injection is performed to perform the filter regeneration process of the DPF 46b. It is preferable to add up the post injection amount and give a warning of oil change when the predetermined amount is reached.

  As shown in FIG. 5, an air-fuel ratio sensor 63 is provided downstream of the DPF 46b.

  In the case where the post-injection is performed to perform the filter regeneration process of the DPF 46b, if the fuel injection amount is too large, the fuel efficiency deteriorates, and if it is small, the temperature does not rise and the regeneration can not be performed. Therefore, the value of the air-fuel ratio sensor 63 is fed back to the control device 100 to determine the injection amount. Thus, appropriate fuel consumption can be achieved, and filter regeneration processing of the DPF 46b can be performed. Further, instead of the air-fuel ratio sensor 63, a pressure value in the intake manifold may be fed back.

  When performing the filter regeneration process of the DPF 46b as described above, in the case of a plurality of cylinders, the combustion of some of the cylinders may be stopped. As described above, by stopping the combustion of some of the cylinders, the engine friction may be the same or the load per cylinder may be increased to raise the exhaust temperature.

  When the tractor is given map data to recognize its own position in the field, the filter reproduction processing may be automatically performed during work by setting the position where the filter reproduction processing of the DPF 46b is to be performed.

  If the tractor has a communication function, the sales company will know the frequency of use by notifying the user's mobile terminal or sales company of the operating time and the amount of fuel used after the work is completed, and the user will be notified It is good to be able to prompt maintenance even without it.

  Since oil change of the engine E is performed by opening the drain plug of the oil pan, if opening and closing of the drain plug is detected by a sensor and the date and time are stored, it becomes easy to confirm the maintenance time of oil change.

E diesel engine 16 steering wheel 21 working machine 46b diesel particulate filter (DPF)
68 Filter regeneration processing

Claims (3)

  In a tractor equipped with a diesel engine (E) exhaust gas purification device that monitors clogging of the diesel particulate filter (46b) and automatically performs filter regeneration (68), turning the steering handle (16) will turn A tractor characterized in that the automatic filter regeneration process (68) is not performed at the time of the automatic lift function in which the work machine (21) rises.   In a tractor equipped with a diesel engine (E) exhaust gas purification device that monitors clogging of the diesel particulate filter (46b) and automatically performs filter regeneration (68), rotation of the engine (E) at high load A tractor characterized in that the filter regeneration process (68) is performed while the auto accel- erator function is operating to ascend.   The filter regeneration process (68) of the diesel particulate filter (46b) is carried out at the time of tilling operation when the work machine (21) is a tiller. Tractor described in.

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