JP5976760B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as an agricultural machine or a construction machine.

  In recent years, as high-order exhaust gas regulations related to diesel engines (hereinafter simply referred to as engines) have been applied, exhaust gas that purifies air pollutants in exhaust gases on agricultural machinery and construction machinery equipped with engines. It is being demanded to install a gas purification device. A diesel particulate filter (hereinafter referred to as DPF) is known as an exhaust gas purification device (see Patent Documents 1 and 2).

  The DPF collects particulate matter (hereinafter referred to as PM) in the exhaust gas. If the exhaust gas temperature is about 300 ° C. or higher, for example, the DPF burns and removes the PM and collects its own PM. Can be recovered (self-regenerating). However, if the engine is driven at low speed and low torque and the exhaust gas temperature is low, PM is not removed by combustion but accumulates in the DPF (cannot self-regenerate). If the amount of PM accumulated in the DPF exceeds a specified amount, the flow resistance in the DPF increases, resulting in a decrease in engine output. Therefore, the DPF is often forcibly regenerated by forcibly increasing the output horsepower of the engine and raising the temperature of the exhaust gas.

JP 2000-145430 A Japanese Patent Laid-Open No. 2003-27922

  By the way, a work vehicle such as a tractor on which an engine and a DPF are mounted performs a sowing work, a fertilization work, or a harvesting work while pulling a ground work machine such as a sowing machine, a fertilizer spreader, or a harvesting machine. When performing these various operations, the work vehicle may travel in the field at a relatively low speed (for example, creep speed). When the work vehicle is traveling at low speed, the engine is driven at low speed and low torque, and the exhaust gas temperature is low. Therefore, during various operations while traveling at a low speed, PM continues to accumulate in the DPF. Therefore, the DPF is easily clogged, and if left as it is, the problem of an increase in exhaust pressure caused by the clogging is caused. It will be. Conventionally, when the DPF is forcibly regenerated during various operations while traveling at a low speed, the output torque of the engine has been increased or the rotational speed of the engine has been increased. However, in the former case, a means for forcibly increasing the output torque is required separately, which causes a problem that the number of parts increases. In the latter case, the vehicle speed may increase.

  Therefore, the present invention has a technical problem to provide a work vehicle that solves such a problem.

The present invention relates to a work vehicle comprising an engine mounted on a traveling machine body, a continuously variable transmission that shifts power from the engine, and an exhaust gas purification device that is disposed in an exhaust system of the engine. A regenerator for combusting and removing particulate matter in the purifier, and a storage unit for storing an output characteristic map indicating a relationship between the engine speed and the torque. a hydraulic pump unit for hydraulic oil supply amount by the tilt angle of the plate is adjusted, and a shifting hydraulic motor operating at hydraulic oil discharged from the hydraulic pump unit, said output characteristic map output is equal output line included showing the relationship between the rotational speed and torque of the engine in the case where the horsepower is constant, the engine operating point about the rotational speed and torque of the engine is self-regenerating the exhaust gas purifying device In the case in low-speed low-torque side that can not, based on the equal output line passing through the engine operating point of the low-speed low-torque side a like output lines included in the output characteristic map, the engine operation of the low-speed low-torque side If the engine operating point on the high speed and low torque side where the point and the output horsepower are equal and the exhaust gas purification device can self-regenerate is present, the engine operating point on the low speed and low torque side is referred to as the engine operating point on the high speed and low torque side. And changing the gear ratio of the continuously variable transmission by changing the inclination angle of the pump swash plate so as not to change the vehicle speed of the traveling machine body, and not operating the regeneration device. .

In the work vehicle, when the engine operating point is on the low-speed low-torque side, based on the iso-output line included in the output characteristic map and passing through the engine operating point on the low-speed low-torque side If the engine operating point on the low-speed low-torque side is equal to the engine operating point on the low-speed low-torque side and the output horsepower is equal, and the high-speed low-torque side engine operating point capable of self-regeneration is not specified , The engine exhaust gas temperature may be forcibly increased.

According to the present invention, in a work vehicle comprising: an engine mounted on a traveling machine body; a continuously variable transmission that shifts power from the engine; and an exhaust gas purification device that is disposed in an exhaust system of the engine. Provided with a regenerator for burning and removing particulate matter in the gas purifier, and when the engine operating point relating to the rotational speed and torque of the engine is on the low speed and low torque side where the exhaust gas purifier cannot self-regenerate, When there is an engine operating point on the low-speed low-torque side where the output horsepower is equal to the engine operating point on the low-speed low-torque side and the exhaust gas purification device is capable of self-regeneration, the engine operating point on the low-speed low torque side is Shift to the engine operating point on the high-speed, low-torque side, and change the gear ratio of the continuously variable transmission so that the vehicle speed of the traveling machine body is not changed In other words, since the regeneration device is not operated, for example, even during various operations while running at a low speed, the exhaust gas purification device is performed without performing forced regeneration of the exhaust gas purification device while maintaining the vehicle speed. Can eliminate clogging. Therefore, it is possible to improve the workability of the work vehicle.

Further, according to the present invention, when the engine operating point is on the low speed and low torque side, the engine operating point on the low speed and low torque side is equal to the output horsepower and the exhaust gas purifying device can self-regenerate at high speed and low speed. When the engine operating point on the torque side does not exist, the regeneration device is operated to forcibly increase the exhaust gas temperature of the engine, so that the output horsepower of the engine can be directly adjusted according to the situation, or the regeneration device The exhaust gas purifying device can be regenerated by operating. As a result, the number of operations of the regenerator can be reduced and the operation time can be shortened, so that the efficiency of regeneration of the exhaust gas purifier can be improved and the effect of suppressing the deterioration of fuel consumption can be achieved.

It is a side view of the tractor as a work vehicle. It is a top view of a tractor. It is a hydraulic circuit diagram of a tractor. It is a skeleton figure of the power transmission system in a tractor. It is a figure explaining the relationship between a vehicle speed and the gear ratio of a continuously variable transmission. It is fuel system explanatory drawing of an engine. It is a functional block diagram which shows the relationship between an engine and an exhaust gas purification apparatus. It is a functional block diagram which shows the relationship between ECU and a speed change controller. It is a figure explaining the injection timing of fuel. It is explanatory drawing of an output characteristic map. It is a flowchart which shows the flow of DPF regeneration control. It is a flowchart which shows the detail of gear ratio control.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(1). Schematic Structure of Tractor First, the schematic structure of a tractor 141 that is an example of a work vehicle will be described with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the traveling machine body 142 of the tractor 141 is supported by a pair of left and right front wheels 143 and a pair of left and right rear wheels 144. The tractor 141 is configured to travel forward and backward by driving the rear wheel 144 and the front wheel 143 with the engine 70 mounted on the front portion of the traveling machine body 142. The engine 70 is covered with a hood 146. A cabin 147 is installed on the upper surface of the traveling machine body 142. Inside the cabin 147, a steering seat 148 and a steering handle 149 for moving the steering direction of the front wheel 143 to the left and right by steering are installed. A step 150 where the operator gets on and off is provided on the outer side of the cabin 147, and a fuel tank 151 for supplying fuel to the engine 70 is provided on the inner side of the step 150 and below the bottom of the cabin 147. .

  As shown in FIGS. 1 and 2, the steering handle 149 in the cabin 147 is provided on a steering column 190 located in front of the steering seat 148. A throttle lever 197 for setting and maintaining the rotational speed of the engine 70 and a pair of left and right brake pedals 191 for braking the traveling machine body 142 are provided on the right side of the steering column 190. On the left side of the control column 190, a forward / reverse switching lever 198 and a clutch pedal 192 for switching the traveling direction of the traveling machine body 142 between forward and reverse are disposed. A parking brake lever 200 that holds the brake pedal 191 in the depressed position is provided on the back side of the steering column 190.

  An accelerator pedal 199 is disposed on the right side of the brake pedal 191. The accelerator pedal 199 increases / decreases the rotational speed in a range beyond this, with the rotational speed of the engine 70 set by the throttle lever 197 as the lower limit rotational speed. On the right column of the control seat 148, a work machine lifting lever 193 for manually changing and adjusting the height position of the rotary tiller 164 as a ground work machine, a PTO speed change lever 194, a main speed change lever 201 for speed change operation, etc. Is arranged. A sub-transmission lever 195 is disposed on the left column of the control seat 148, and a differential lock pedal 196 is disposed in front of the left column.

  As shown in FIGS. 1 and 2, the traveling aircraft body 142 includes an engine frame 154 having a front bumper 152 and a front axle case 153, and left and right aircraft frames 156 that are detachably fixed to the rear portion of the engine frame 154 with bolts. Consists of. A transmission case 157 is connected to the rear part of the body frame 156 for appropriately shifting the driving force of the engine 70 and transmitting it to the rear wheels 144 and the front wheels 143. The rear wheel 144 is attached via a rear axle case 158 mounted so as to protrude outward from the outer surface of the mission case 157. In the mission case 157, a continuously variable transmission 159 (see FIGS. 3 and 4) for shifting the driving force from the engine 70 is provided.

  On the rear upper surface of the mission case 157, a hydraulic working machine lifting mechanism 160 that lifts and lowers the rotary tiller 164 is detachably attached. The rotary cultivator 164 is connected to the rear portion of the mission case 157 via a three-point link mechanism including a pair of left and right lower links 161 and a top link 162. On the rear side surface of the mission case 157, a PTO shaft 163 for transmitting a PTO driving force to the rotary tiller 164 protrudes backward.

  As shown in FIGS. 1 and 2, a seeder 170 for sowing is attached to the rear side of the rotary tiller 164 so as to be exchangeable with a fertilizer spreader (not shown). The seeder 170 includes a tank 171 for putting seeds therein, a feeding unit 172 that feeds seeds in the tank 171 by a fixed amount, and an electric motor 173 that drives a feeding roller (not shown) of the feeding unit 172. The seeds in the tank 171 are sowed on the already cultivated ground behind the rotary tiller 164 from the feeding portion 172. In addition, when a fertilizer spreader is attached to the rotary tiller 164, the fertilizer (chemical | medical agent) of a fertilizer spreader will be spread on the already cultivated ground behind the rotary tiller 164.

(2). Next, the structure of the hydraulic circuit 210 of the tractor 141 will be described with reference mainly to FIG. The hydraulic circuit 210 of the tractor 141 includes a working hydraulic pump 204 and a traveling hydraulic pump 205 that are driven by the rotational power of the engine 70. The working hydraulic pump 204 and the traveling hydraulic pump 205 are provided on the front side of the front side wall member 222 in the mission case 157 (see FIG. 4). The working hydraulic pump 204 is connected to a control electromagnetic valve 211 for supplying hydraulic oil to the lifting control hydraulic cylinder 215 of the working machine lifting mechanism 160. The control solenoid valve 211 is configured to be switchable by operating the work implement lifting lever 193. When the control electromagnetic valve 211 is switched by the work implement lifting lever 193, the lift control hydraulic cylinder 215 is extended and contracted to lift the lift arm 169 connecting the work implement lifting mechanism 160 and the left and right lower links 161 (see FIG. 1). Rotate up and down. As a result, the rotary tiller 164 moves up and down via the lower link 161.

  The traveling hydraulic pump 205 supplies hydraulic oil to the continuously variable transmission 159 of the mission case 157 and the hydraulic cylinder 203 for power steering. In this case, the mission case 17 is also used as a hydraulic oil tank, and the hydraulic oil inside the mission case 157 is supplied to the hydraulic pumps 204 and 205. The traveling hydraulic pump 205 is connected to a power steering hydraulic cylinder 203 via a power steering control valve 212, while an automatic brake electromagnetic valve 246 for a brake cylinder 247 for a pair of left and right brake operating mechanisms 245 is provided. Is also connected.

  Further, the traveling hydraulic pump 205 is operated by a PTO clutch hydraulic electromagnetic valve 249 that operates the PTO clutch 248 of the PTO transmission mechanism 228, a proportional control valve 213 and a starting electromagnetic valve 217 for the continuously variable transmission 159, and the like. A switching valve 214, a high-speed clutch electromagnetic valve 251 for operating the auxiliary transmission hydraulic cylinder 250 of the auxiliary transmission mechanism 227, a forward clutch electromagnetic valve 253 for the forward hydraulic clutch 252 of the forward / reverse switching mechanism 226, and a backward hydraulic clutch 254 Are connected to a four-stroke hydraulic solenoid valve 257 for the four-wheel drive hydraulic clutch 256 of the two-wheel drive and four-wheel drive switching mechanism 229, and a double speed hydraulic solenoid valve 259 for the double speed hydraulic clutch 258.

  The PTO clutch hydraulic solenoid valve 249, the forward clutch solenoid valve 253, the reverse clutch solenoid valve 255, the four-wheel drive hydraulic solenoid valve 257, and the double speed hydraulic solenoid valve 259 operate these clutch cylinders by appropriately controlling them. Thus, the hydraulic clutches 248, 252, 254, 256, and 258 are configured to be switched and driven. The hydraulic circuit 210 also includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like.

(3). Next, the power transmission system of the tractor 141 will be described with reference mainly to FIG. A front side wall member 222 is fixed to the front surface of the mission case 157 formed in a hollow box shape, and a rear side wall member 223 is detachably fixed to the rear surface. The interior of the mission case 157 is divided into a front chamber 224 and a rear chamber 225 by a partition wall 221. Although illustration is omitted, the front chamber 224 and the rear chamber 225 communicate with each other so that the internal hydraulic fluid can move between them. On the front chamber 224 side of the mission case 157, a forward / reverse switching mechanism 226 that switches the rotational power from the continuously variable transmission 159 in the forward or reverse direction, and a mechanical type that shifts the rotational power via the forward / backward switching mechanism 226. The sub-transmission mechanism 227, the PTO transmission mechanism 228 for appropriately changing the rotational power from the engine 70 and transmitting it to the PTO shaft 163, and the two-wheel drive and four-wheel drive switching mechanism for switching between the front and rear wheels 143 and 144. 229 is arranged. On the rear chamber 225 side, a continuously variable transmission 159 and a differential gear mechanism 230 that transmits rotational power via the auxiliary transmission mechanism 227 to the left and right rear wheels 144 are disposed.

  A flywheel 231 is attached to an engine output shaft 74 protruding rearward from the engine 70 so as to be directly connected. The flywheel 231 and the main shaft 232 extending rearward therefrom are connected via a main clutch 233 for power transmission. The main drive shaft 232 and the main transmission input shaft 234 projecting forward from the transmission case 157 are connected via a power transmission shaft 235 having universal shaft joints at both ends. The rotational power of the engine 70 is transmitted from the engine output shaft 74 to the main transmission input shaft 234 via the main driving shaft 232 and the power transmission shaft 235, and then appropriately shifted by the continuously variable transmission 159 and the auxiliary transmission mechanism 227. The transmission power is transmitted to the left and right rear wheels 144 via the differential gear mechanism 230. Shift power by the continuously variable transmission 159 and the auxiliary transmission mechanism 227 is also transmitted to the left and right front wheels 153 via the two-wheel drive / four-wheel drive switching mechanism 229 and the differential gear mechanism 236 in the front axle case 153.

  The continuously variable transmission 159 inside the rear chamber 225 is an inline type in which a main transmission output shaft 237 is concentrically arranged on a main transmission input shaft 234, and includes a variable displacement hydraulic pump unit 240 and the hydraulic pressure. And a constant displacement type hydraulic motor unit 241 that operates with high-pressure hydraulic fluid discharged from the pump unit 240. The hydraulic pump unit 240 is provided with a pump swash plate 242 that can change the inclination angle with respect to the axis of the main transmission input shaft 234 and adjust the amount of hydraulic oil supplied thereto. Associated with the pump swash plate 242 is a main transmission hydraulic cylinder 243 that changes and adjusts the inclination angle of the pump swash plate 242 with respect to the axis of the main transmission input shaft 234. By changing the inclination angle of the pump swash plate 242 by driving the main transmission hydraulic cylinder 243, the amount of hydraulic oil supplied from the hydraulic pump unit 240 to the hydraulic motor unit 241 is changed and adjusted, and the main transmission of the continuously variable transmission 159 is changed. A speed change operation is performed.

  That is, when the switching valve 214 is operated by hydraulic oil from the proportional control valve 213 that operates in proportion to the operation amount of the main transmission lever 201, the main transmission hydraulic cylinder 190 is driven, and accordingly, the main transmission input shaft 234 is driven. The inclination angle of the pump swash plate 242 with respect to the axis is changed. The pump swash plate 242 of the embodiment adjusts the angle in a range between one (positive) maximum inclination angle and the other (negative) maximum inclination angle with a neutral angle of substantially zero inclination (before and after including zero) interposed therebetween. It is possible to set the angle so that the vehicle body 142 is inclined at one of the lowest vehicle speeds (in this case, it is negative and the inclination angle near the maximum) (see FIG. 5).

  When the inclination angle of the pump swash plate 242 is substantially zero (neutral angle), the hydraulic motor unit 241 is not driven by the hydraulic pump unit 240 and the main transmission output shaft 237 is driven at substantially the same rotational speed as the main transmission input shaft 234. Rotates. When the pump swash plate 242 is tilted in one direction (positive tilt angle) with respect to the axis line of the main transmission input shaft 234, the hydraulic pump unit 240 increases the speed of the hydraulic motor unit 241 to operate the main transmission input shaft. The main transmission output shaft 237 rotates at a rotational speed faster than H.234. As a result, the rotational speed of the hydraulic motor unit 241 is added to the rotational speed of the main transmission input shaft 234 and transmitted to the main transmission output shaft 237. For this reason, in the range of the rotational speed higher than the rotational speed of the main transmission input shaft 234, the transmission power (vehicle speed) from the main transmission output shaft 237 is proportional to the inclination angle (positive inclination angle) of the pump swash plate 242. Be changed. When the pump swash plate 242 is positive and has an inclination angle near the maximum, the traveling machine body 142 reaches the maximum vehicle speed (see the white squares in FIG. 5).

  When the pump swash plate 242 is inclined in the other direction (negative inclination angle) with respect to the axis line of the main transmission input shaft 234, the hydraulic pump unit 240 operates the hydraulic motor unit 241 to decelerate (reverse) and shift the main transmission. The main transmission output shaft 237 rotates at a lower rotational speed than the input shaft 234. As a result, the rotational speed of the hydraulic motor unit 241 is subtracted from the rotational speed of the main transmission input shaft 234 and transmitted to the main transmission output shaft 237. Therefore, the transmission power from the main transmission output shaft 237 is changed in proportion to the inclination angle (negative inclination angle) of the pump swash plate 242 within the range of the rotation speed lower than the rotation speed of the main transmission input shaft 234. . When the pump swash plate 242 is negative and has an inclination angle near the maximum, the traveling machine body 142 has the minimum vehicle speed (see the white circles in FIG. 5).

  In the embodiment, when the switching valve 214 is operated with hydraulic fluid from a starting electromagnetic valve 217 that is operated in accordance with a command from a work machine (transmission) controller 271 described later, regardless of the operation position of the main transmission lever 201. The main transmission hydraulic cylinder 243 is driven, and accordingly, the inclination angle of the pump swash plate 242 with respect to the axis of the main transmission input shaft 234 is changed.

(4). Next, the structure of the engine 70 and its surroundings will be described with reference to FIGS. 6 and 7. As shown in FIG. 6, the engine 70 is a four-cylinder diesel engine, and includes a cylinder block 75 with a cylinder head 72 fastened on the upper surface. An intake manifold 73 is connected to one side of the cylinder head 72, and an exhaust manifold 71 is connected to the other side. A common rail device 117 that supplies fuel to each cylinder of the engine 70 is provided below the intake manifold 73 on the side surface of the cylinder block 75. An intake pipe 76 connected to the intake upstream side of the intake manifold 73 is connected to an intake throttle device 81 and an air cleaner (not shown) for adjusting the intake pressure (intake amount) of the engine 70.

  As shown in FIG. 7, the fuel tank 118 is connected to the injectors 115 for the four cylinders in the engine 70 via the common rail device 117 and the fuel supply pump 116. Each injector 115 is provided with an electromagnetic switching control type fuel injection valve 119. The common rail device 117 includes a cylindrical common rail 120. A fuel tank 118 is connected to the suction side of the fuel supply pump 116 via a fuel filter 121 and a low pressure pipe 122. The fuel in the fuel tank 118 is sucked into the fuel supply pump 116 via the fuel filter 121 and the low pressure pipe 122. The fuel supply pump 116 of the embodiment is disposed in the vicinity of the intake manifold 73. On the other hand, a common rail 120 is connected to the discharge side of the fuel supply pump 116 via a high-pressure pipe 123. The common rail 120 is connected to injectors 115 for four cylinders via four fuel injection pipes 126.

  In the above configuration, the fuel in the fuel tank 118 is pumped to the common rail 120 by the fuel supply pump 116, and high-pressure fuel is stored in the common rail 120. Each fuel injection valve 119 is controlled to open and close, whereby high-pressure fuel in the common rail 120 is injected from each injector 115 to each cylinder of the engine 70. That is, by electronically controlling each fuel injection valve 119, the injection pressure, injection timing, and injection period (injection amount) of the fuel supplied from each injector 115 are controlled with high accuracy. Therefore, nitrogen oxide (NOx) from the engine 70 can be reduced, and noise and vibration of the engine 70 can be reduced.

  As shown in FIG. 9, the common rail device 117 is configured to execute the main injection A in the vicinity of the top dead center (TDC). In addition to the main injection A, the common rail device 117 executes a small amount of pilot injection B for the purpose of reducing NOx and noise at a crank angle θ1 of about 60 ° before the top dead center, Pre-injection C is executed for the purpose of reducing noise immediately before the crank angle θ2, and after-injection is performed for the purpose of reducing PM and promoting exhaust gas purification at the crank angles θ3 and θ4 after top dead center. D and post-injection E are executed.

  The pilot injection B is injected at a timing that is greatly advanced with respect to the main injection A, thereby promoting the mixing of fuel and air. The pre-injection C is performed prior to the main injection A to shorten the ignition timing delay in the main injection A. After-injection D is injected at a time close to main injection A, thereby activating diffusion combustion and re-burning PM (reducing PM). The post-injection E is supplied to the DPF 50, which will be described later, as unburned fuel without contributing to the actual combustion process by being injected at a timing that is largely retarded with respect to the main injection A. The unburned fuel supplied to the DPF 50 reacts on a diesel oxidation catalyst 53 described later, and the exhaust gas temperature in the DPF 50 rises due to the reaction heat. The level of the peaks in the graph in FIG. 9 roughly represents the difference in the fuel injection amount at each of the injection stages A to E.

  As shown in FIG. 7, a fuel supply pump 116 is connected to the fuel tank 118 via a fuel return pipe 129. A common rail return pipe 131 is connected to the end of the cylindrical common rail 120 in the longitudinal direction via a return pipe connector 130 that limits the pressure of fuel in the common rail 120. That is, surplus fuel from the fuel supply pump 116 and surplus fuel from the common rail 120 are collected in the fuel tank 118 via the fuel return pipe 129 and the common rail return pipe 131.

  An exhaust pipe 77 connected to the exhaust downstream side of the exhaust manifold 71 is connected to an exhaust throttle device 82 for adjusting the exhaust pressure of the engine 70 and a DPF 50 which is an example of an exhaust gas purification device. Exhaust gas discharged from each cylinder to the exhaust manifold 71 is purified through the exhaust pipe 77, the exhaust throttle device 82, and the DPF 50, and then released to the outside.

  As shown in FIG. 6, the DPF 50 is for collecting PM and the like in the exhaust gas. The DPF 50 according to the embodiment is configured by accommodating a diesel oxidation catalyst 53 such as platinum and a soot filter 54 in series in a substantially cylindrical filter case 52 in a casing 51 made of a heat-resistant metal material. A diesel oxidation catalyst 53 is disposed upstream of the filter case 52 and a soot filter 54 is disposed downstream of the exhaust. The soot filter 54 has a honeycomb structure having a large number of cells partitioned by porous partition walls that can filter exhaust gas.

  An exhaust introduction port 55 that communicates with the exhaust downstream side of the exhaust throttle device 82 in the exhaust pipe 77 is provided on one side of the casing 51. One side of the casing 51 and one side of the filter case 52 are closed by a first side wall plate 56 and a second side wall plate 57. The other side of the casing 51 is closed by a first lid plate 59 and a second lid plate 60. Between the two cover plates 59 and 60, an exhaust sound attenuation chamber 63 communicating with the filter case 52 via a plurality of communication pipes 62 is formed. Further, a substantially cylindrical exhaust outlet pipe 61 passes through the second lid plate 60. A plurality of communication holes 58 that open toward the exhaust sound attenuation chamber 63 are formed on the outer peripheral surface of the exhaust outlet pipe 61. The exhaust outlet pipe 61, the exhaust sound attenuation chamber 63, and the like constitute a silencer 64.

  An exhaust gas introduction pipe 65 is inserted into an exhaust introduction port 55 formed on one side of the casing 51. The tip of the exhaust gas introduction pipe 65 projects across the casing 51 to the side surface opposite to the exhaust introduction port 55. A plurality of communication holes 66 opening toward the filter case 52 are formed on the outer peripheral surface of the exhaust gas introduction pipe 65. A portion of the exhaust gas introduction pipe 65 that protrudes from the side surface opposite to the exhaust introduction port 55 is closed by a lid 67 that is detachably screwed to the portion.

  The DPF 50 is provided with a DPF differential pressure sensor 68 that detects a clogged state of the soot filter 54 as an example of a detection unit. The DPF differential pressure sensor 68 detects a pressure difference between the exhaust pressures upstream and downstream of the soot filter 54 in the DPF 50 (exhaust gas differential pressure between the inlet side and the outlet side). In this case, the upstream exhaust pressure sensor 68 a constituting the DPF differential pressure sensor 68 is attached to the lid 67 of the exhaust gas introduction pipe 65, and the downstream exhaust pressure is interposed between the soot filter 54 and the exhaust sound attenuation chamber 63. A sensor 68b is attached.

  Since there is a specific relationship between the pressure difference between the upstream and downstream of the DPF 50 and the PM accumulation amount in the soot filter 54 (DPF 50), based on the pressure difference detected by the DPF differential pressure sensor 68, The PM accumulation amount in the DPF 50 is obtained by calculation. Then, the regeneration control of the soot filter 54 (DPF 50) is executed by controlling the operation of the intake throttle device 81, the exhaust throttle device 82, or the common rail 120 based on the calculation result of the PM accumulation amount.

  In the above configuration, the exhaust gas from the engine 70 enters the exhaust gas introduction pipe 65 through the exhaust introduction port 55, and is ejected into the filter case 52 from each communication hole 66 formed in the exhaust gas introduction pipe 65. Then, the diesel oxidation catalyst 53 and the soot filter 54 are passed through in this order for purification treatment. PM in the exhaust gas is collected by the soot filter 54 (porous partition between each cell). Exhaust gas that has passed through the diesel oxidation catalyst 53 and the soot filter 54 is discharged from the exhaust outlet pipe 61 to the outside through the silencer 64.

  When the exhaust gas passes through the diesel oxidation catalyst 53 and the soot filter 54, if the exhaust gas temperature exceeds a reproducible temperature (for example, about 250 to 300 ° C.), the action of the diesel oxidation catalyst 53 causes NO in the exhaust gas. (Nitric oxide) is oxidized to unstable NO2 (nitrogen dioxide). Then, the PM collecting ability of the soot filter 54 is recovered by oxidizing and removing the PM deposited on the soot filter 54 with O (oxygen) released when NO 2 returns to NO. That is, the soot filter 54 (DPF 50) is regenerated.

(5). Configuration Related to Engine Control Next, a configuration related to control of the engine 70 will be described with reference to FIGS. As shown in FIGS. 7 and 8, the tractor 141 includes, as control means, an ECU 11 that operates a fuel injection valve 119 for each cylinder in the engine 70, and a work machine (transmission) controller 271. The ECU 11 includes a CPU 31 that executes various arithmetic processes and controls, a ROM 32 that stores various data in a fixed manner, an EEPROM 33 that stores control programs and various data in a rewritable manner, and a RAM 34 that temporarily stores control programs and various data. A timer 35 for measuring time, an input / output interface, and the like. The work machine controller 271 also has a CPU 281, a ROM 282, an EEPROM 283, a RAM 284, a timer 285, an input / output interface, and the like, like the ECU 11.

  As a guideline, the ECU 11 and the work machine controller 271 that are the control means are combined and controlled so that the length of the harness of the input / output system equipment is as short as possible. (Omitted). The ECU 11 and the work machine controller 271 are electrically connected to each other via a CAN communication bus 272. ECU11 of embodiment is arrange | positioned at the engine 70 or its vicinity (refer FIG. 2). The work machine controller 271 is disposed, for example, below the control seat 148 in the cabin 147 (see FIG. 2). Note that three or more control means may be connected via a communication bus. Each input / output system device to be described later may be connected to any control means.

  On the input side of the ECU 11, at least a rail pressure sensor 12 that detects the fuel pressure in the common rail 120, an electromagnetic clutch 13 that rotates or stops the fuel pump 116, and the rotational speed of the engine 70 (camshaft position of the engine output shaft 74). Engine speed sensor 14 as a rotational speed detection means to detect, injection setter 15 for detecting and setting the number of fuel injections of the injector 115 (number of times during the fuel injection period of one stroke), intake air for detecting the intake gas temperature of the intake system A temperature sensor 17, an exhaust temperature sensor 18 for detecting the exhaust gas temperature of the exhaust system, a coolant temperature sensor 19 for detecting the coolant temperature of the engine 70, a fuel temperature sensor 20 for detecting the fuel temperature in the common rail 120, and a DPF Differential pressure sensor 68 (upstream exhaust pressure sensor 68a and downstream exhaust pressure sensor 68b) There has been connected.

  An electromagnetic solenoid of each fuel injection valve 119 for the four cylinders of the engine is connected to the output side of the ECU 11. That is, the high-pressure fuel stored in the common rail 120 is injected from the fuel injection valve 119 in a plurality of times during one stroke while controlling the fuel injection pressure, the injection timing, the injection period, and the like, so that nitrogen oxide (NOx ), And complete combustion with reduced generation of soot and carbon dioxide is performed to improve fuel efficiency. Further, on the output side of the ECU 11, an intake throttle device 81 for adjusting the intake pressure (intake amount) of the engine 70, an exhaust throttle device 82 for adjusting the exhaust pressure of the engine 70, and a failure notification of the ECU 11 are notified. An ECU failure lamp 22, an exhaust temperature warning lamp 23 for notifying an abnormally high exhaust gas temperature in the DPF 50, a regeneration lamp 24 that is turned on when the DPF 50 is regenerated, and the like are connected.

  As shown in FIG. 8, the work machine controller 271 includes various output-related electromagnetic valves, that is, a forward clutch electromagnetic valve 253 for the forward hydraulic clutch 252, a reverse clutch electromagnetic valve 255 for the reverse hydraulic clutch 254, and a sub-shift. A high-speed clutch electromagnetic valve 251 for the hydraulic cylinder 250, a proportional control valve 213 for operating the main transmission hydraulic cylinder 243 in proportion to the operation amount of the main transmission lever 201, a four-drive hydraulic electromagnetic valve 257 for the four-drive hydraulic clutch 256, and double speed Hydraulic oil is supplied to the double speed hydraulic solenoid valve 259 for the hydraulic clutch 258, the left and right autobrake solenoid valves 246, the PTO clutch hydraulic solenoid valve 249 for the PTO clutch 248, and the lift control hydraulic cylinder 215 of the work machine lift mechanism 160. A control electromagnetic valve 211 and the like are connected.

  Further, the work machine controller 271 includes various sensors and switches related to input, that is, a steering potentiometer 290 that detects the amount of rotation (steering angle) of the steering handle 149, and the forward and backward switch lever 198 from the operation position. A forward / reverse potentiometer 291 that detects the on / off state of the reverse hydraulic clutches 252, 254, a main transmission output shaft rotation sensor 292 that detects the output rotation speed of the main transmission output shaft 237, and a throttle position sensor that detects the operating position of the throttle lever 197 16, a vehicle speed sensor 25 for detecting the rotational speed (vehicle speed) of the front and rear four wheels 143, 144, a four-wheel drive mode switch 293 for switching the four-wheel drive hydraulic solenoid valve 257, and a double speed mode switch 294 for switching the double-speed hydraulic solenoid valve 259 , Brake pedal that detects the presence or absence of depression of the brake pedal 191 Switch 295, auto brake switch 296 for switching the auto brake solenoid valve 246, main transmission potentiometer 297 for detecting the operation position of the main transmission lever 201, sub transmission lever sensor 298 for detecting the operation position of the sub transmission lever 195, etc. Is connected.

  In the EEPROM 33 of the ECU 11 or the EEPROM 283 of the work machine controller 271, an output characteristic map M (see FIG. 10) indicating the relationship between the rotational speed N of the engine 70 and the torque T (load) is stored in advance. The output characteristic map M is obtained by experiments or the like. In the output characteristic map M shown in FIG. 10, the rotational speed N is taken on the horizontal axis and the torque T is taken on the vertical axis. The output characteristic map M is a region surrounded by a solid line Tmx drawn upwardly. A solid line Tmx is a maximum torque line representing the maximum torque for each rotational speed N.

  The output characteristic map M shown in FIG. 10 is divided vertically by a boundary line BL representing the relationship between the rotational speed N and the torque T when the exhaust gas temperature is the regeneration boundary temperature (about 300 ° C.). The upper region across the boundary line BL is a reproducible region Re in which PM deposited on the soot filter 54 can be removed by oxidation, and the lower region is unreproducible in which PM is deposited on the soot filter 54 without being removed by oxidation. Region Im. The output characteristic map M also shows a series of equal output lines PL. The equal output line PL is a line indicating the relationship between the rotational speed N and the torque T when the output horsepower of the engine 70 is constant. Since the product of the rotational speed N and the torque T is proportional to the output horsepower, the output characteristic map M in FIG. 10 shows the iso-output line PL as an inverse proportional curve.

  The ECU 11 obtains the torque T of the engine 70 from the rotational speed detected by the engine speed sensor 14 and the throttle position detected by the throttle position sensor 16, and uses the torque T and the output characteristic map M to perform target fuel injection. The fuel injection control for calculating the amount and operating the common rail device 117 based on the calculation result is executed. The fuel injection amount of the common rail device 117 is adjusted by adjusting the valve opening period of each fuel injection valve 119 and changing the injection period to each injector 115.

(6). Aspects of DPF regeneration control Next, an example of DPF 50 regeneration control by the ECU 11 will be described with reference to the flowcharts of FIGS. 11 and 12. As a control mode of the engine 70 (control format related to DPF 50 regeneration), at least a normal operation mode for running on the road and various operations, and a regeneration priority mode for increasing the exhaust gas temperature when the clogged state of the DPF 50 exceeds a specified level. There is. In the regeneration priority mode, the intake throttle device 81 or the exhaust throttle device 82 is closed to a predetermined opening based on the detection information of the differential pressure sensor 68 to limit the intake air amount or the exhaust air amount, or the post-injection E in the DPF 50 The exhaust gas temperature in the DPF 50 is raised (about 560 ° C.) by burning the unburned fuel supplied to the fuel in the diesel oxidation catalyst 53. As a result, the PM in the DPF 50 (soot filter 54) is forcibly removed by combustion.

  As can be seen from the description of the regeneration priority mode, for example, the engine 70, the intake throttle device 81, the exhaust throttle device 82, the common rail device 117, and the like are members involved in the DPF 50 regeneration operation. These devices 70, 81, 82, 117 constitute a regeneration device that burns and removes the PM in the DPF 50.

  The normal operation mode and the regeneration priority mode are executed based on a command from the ECU 11. That is, the algorithms shown in the flowcharts of FIG. 11 and FIG. 12 are stored in the EEPROM 33, and each mode is executed by calling the algorithm to the RAM 34 and then processing the CPU 31.

  As shown in the flowchart of FIG. 11, in the DPF 50 regeneration control, first, the PM accumulation amount in the DPF 50 is estimated based on the detection result of the differential pressure sensor 68 (S01), and the estimation result is equal to or greater than the specified amount (specified level). Whether or not (S02). Detection by the differential pressure sensor 68 is appropriately performed every time. When it is determined that the PM accumulation amount is less than the specified amount (S02: NO), the routine returns and the normal operation mode is continued. When it is determined that the PM accumulation amount is equal to or greater than the prescribed amount (S02: NO), the current rotational speed N1 and torque T1 of the engine 70, the current vehicle speed V1, and the rotational speed R1 of the main transmission output shaft 237 are read ( S03), using the current rotational speed N1, torque T1 and output characteristic map M, the current engine operating point Q1 is obtained (S04), and whether or not the current engine operating point Q1 is within the reproducible region Re. It discriminate | determines (S05). If the current engine operating point Q1 is within the recyclable region Re (S05: YES), the exhaust gas temperature is higher than the regeneration boundary temperature, and the PM accumulated in the DPF 50 (soot filter 54) can be removed by oxidation (self-regeneration). Return to the normal operation mode.

  If the current engine operating point Q1 is within the non-recoverable region Im (S05: NO), the DPF 50 is in a state where it cannot self-regenerate. From the relationship with the boundary line BL, it is determined whether or not there is a target engine operating point Q2 on the high-speed low-torque side that has the same output horsepower as the current engine operating point Q1 and allows the DPF 50 to self-regenerate (S06). . Since the current engine operating point Q1 and the target engine operating point Q2 have the same output horsepower, they are located on a common iso-output line PL.

  When the target engine operating point Q2 does not exist (S06: NO), the regeneration lamp 24 is turned on (S07), and the regeneration priority mode is executed (S08). In the regeneration priority mode, as described above, the load on the engine 70 is increased by limiting the intake / exhaust amount using the intake throttle device 81 or the exhaust throttle device 82. Along with this, the output horsepower increases to maintain the set rotational speed by the throttle lever 197, and the exhaust gas temperature from the engine 70 rises. Further, the unburned fuel supplied into the DPF 50 by the post injection E of the common rail 120 is combusted by the diesel oxidation catalyst 53, thereby increasing the exhaust gas temperature in the DPF 50. As a result, the PM in the DPF 50 is burned and removed, and the PM collection capability of the DPF 50 is restored. The regeneration priority mode according to the embodiment is executed, for example, about several tens of minutes. After the time has elapsed, the opening degree of the intake throttle device 81 and the exhaust throttle device 82 returns to the original state before the narrowing and the common rail 120. Stops post injection E. After that, it returns and executes the normal operation mode.

  When the target engine operating point Q2 exists (S06: YES), the fuel injection amount of the common rail device 117 is such that the torque T decreases (T1 → T2) as the rotational speed N of the engine 70 increases (N1 → N2). Is adjusted to shift the engine operating point from the current Q1 to the target engine operating point Q2 (S09). Then, by correcting the applied voltage of the proportional control valve 213 according to a command from the work machine controller 271, the main transmission hydraulic cylinder 243 is operated to change and adjust the inclination angle of the pump swash plate 242 in the hydraulic pump unit 240, The amount of hydraulic oil supplied to the hydraulic motor unit 241 is controlled, and the gear ratio of the continuously variable transmission 159 is changed and adjusted so that the rotational speed R of the main transmission output shaft 237 remains at the detection value R1 in step S03. (Gear ratio control, S10). Here, the gear ratio refers to the ratio (R / N) of the rotational speed R of the main transmission output shaft 237 to the rotational speed N of the engine 70.

  With this control, the engine operating point Q is changed and the rotational speed N of the engine 70 is increased, but the rotational speed R of the main transmission output shaft 237 can be kept constant by adjusting and changing the speed ratio. That is, the vehicle speed V of the traveling machine body 142 can be kept constant before and after the change of the engine operating point Q.

  The gear ratio control in step S10 is executed, for example, as shown in the flowchart of FIG. That is, the vehicle speed V2 after the transition to the engine operating point Q2 is read (S11), and the post-transition vehicle speed V2 is greater than the pre-transition vehicle speed V1 read in step S03 (S12: YES), the main transmission output shaft 237 The gear ratio of the continuously variable transmission 159 is decreased so that the rotation speed R becomes the detected value R1 in step S03 (S13), and the process returns to step S12. If the post-transition vehicle speed V2 is smaller than the pre-transition vehicle speed V1 (S14: YES), the gear ratio of the continuously variable transmission 159 is set so that the rotational speed R of the main transmission output shaft 237 becomes the detected value R1 in step S03. (S15), and the process returns to step S12. If the vehicle speed V1 before the transition and the vehicle speed V2 after the transition are the same (S14: NO), the process returns to the normal operation mode.

  As is clear from the above description, the engine 70 mounted on the traveling machine body 142, the common rail fuel injection device 117 that injects fuel into the engine 70, and the continuously variable transmission that changes the power from the engine 70. 159 and an exhaust gas purifying device 50 disposed in the exhaust system of the engine 70, the engine operating point Q related to the rotational speed N and torque T of the engine 70 is the exhaust gas purifying device. 50 is on the low speed and low torque side where self-regeneration is not possible, the engine operating point Q is shifted to the high speed and low torque side where the exhaust gas purification device 50 can self-regenerate, and the vehicle speed V of the traveling machine body 142 is changed. Since the transmission ratio of the continuously variable transmission 159 is changed and adjusted so as not to be While maintaining the vehicle speed V, the clogging of the possible elimination of the exhaust gas purifying device 50 without performing the forced regeneration of the exhaust gas purifying device 50. Accordingly, the workability of the work vehicle 141 can be improved.

  Further, at the engine operating point Q2 on the high speed and low torque side, the exhaust gas purification device 50 can self-regenerate under the condition that the output horsepower is equal to the engine operating point Q1 on the low speed and low torque side. The output horsepower of the engine 70 is used as a reference for shifting the engine operating point Q. For this reason, the vehicle speed V of the work vehicle 141 can be easily and accurately maintained.

  Furthermore, it has regenerators 70, 81, 82, 117 for burning and removing particulate matter in the exhaust gas purifier 50, and the engine operating point Q1 is a low speed at which the exhaust gas purifier 50 cannot self-regenerate. When there is no engine operating point Q2 on the low torque side when the engine operating point Q1 on the low speed low torque side and the output horsepower are equal and the exhaust gas purifying device 50 can self-regenerate, there is no engine operating point Q2. Since the regenerators 70, 81, 82, and 117 are operated, the exhaust gas is adjusted by directly adjusting the output horsepower of the engine 70 or operating the regenerators 70, 81, 82, and 117 depending on the situation. The purification device 50 can be regenerated. For this reason, the number of operations of the regenerators 70, 81, 82, 117 can be reduced and the operation time can be shortened, the efficiency of regeneration of the exhaust gas purifying device 50 can be improved, and the effect of contributing to the suppression of fuel consumption deterioration can be achieved. Play.

(7). Others The present invention is not limited to the above-described embodiment, and can be embodied in various forms. The configuration of each part is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, instead of detecting the rotational speed R of the main transmission output shaft 237, it is also possible to detect the vehicle speed V (rotational speed of the front and rear wheels 143, 144) and perform the gear ratio control based on this, as an equivalent meaning. The continuously variable transmission 159 is not limited to the in-line type described above, and various types such as a mechanical type such as a belt type and a ring cone, a hydrostatic transmission, and a hydromechanical transmission can be adopted.

11 ECU (control means)
50 DPF (Exhaust Gas Purifier)
70 Engine 81 Intake throttle device 82 Exhaust throttle device 117 Common rail device 120 Common rail 141 Tractor (work vehicle)
142 traveling machine body 164 rotary tiller (ground work machine)
200 seeder

Claims (2)

In a work vehicle comprising an engine mounted on a traveling machine body, a continuously variable transmission that shifts power from the engine, and an exhaust gas purification device disposed in an exhaust system of the engine,
A regenerator for burning and removing particulate matter in the exhaust gas purifier , and a storage unit for storing an output characteristic map indicating the relationship between the engine speed and torque ,
The continuously variable transmission includes a hydraulic pump unit in which a hydraulic oil supply amount is adjusted by an inclination angle of a pump swash plate, and a transmission hydraulic motor unit that operates with hydraulic oil discharged from the hydraulic pump unit. And
The output characteristic map includes an iso-output line indicating the relationship between the engine speed and torque when the output horsepower is constant,
When the engine operating point related to the rotational speed and torque of the engine is on the low-speed low-torque side where the exhaust gas purifying device cannot self-regenerate, the engine on the low-speed low-torque side is an iso-output line included in the output characteristic map When there is an engine operating point on the high-speed low-torque side where the output horsepower is equal to the engine operating point on the low-speed low-torque side based on the iso-output line passing through the operating point and the self-regeneration of the exhaust gas purification device is possible The continuously variable transmission is performed by changing the engine operating point on the low-speed and low-torque side to the engine operating point on the high-speed and low-torque side and changing the inclination angle of the pump swash plate so as not to change the vehicle speed of the traveling machine body. Change the gear ratio of the machine, do not activate the forced regeneration of the regeneration device,
Work vehicle. When the engine operating point is on the low-speed low-torque side, the low-speed low-torque is based on the iso-output line included in the output characteristic map and passing through the engine operating point on the low-speed low-torque side. If the engine operating point on the high-speed low-torque side where the output horsepower is equal to the engine operating point on the side and the exhaust gas purifying device can self-regenerate cannot be specified , the regenerator is operated and the exhaust gas of the engine To forcibly raise the temperature,
The work vehicle according to claim 1.

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