JP2009180180A - Work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a trouble caused by the deceleration of engine speed with respect to an abrupt change of a load at the working time of a working vehicle, to suppress the generation of smoke, to regulate the retrurn speed of the number of revolutions of an engine caused by the abrupt reduction of the load, and to prevent the abrupt acceleration of a machine body. <P>SOLUTION: A position detection means discriminating the descent position of a working machine connected to the working vehicle is provided at a suitable position. When the position detection means detects the descent of the working machine to a work start position, the rail pressure of a common rail is corrected and increased by a prescribed quantity and a pressure increase correction state is returned to an original state after a prescribed time has passed. The work of the working machine is controlled by isochronus control. When engine rotation speed drops in a full load state during work, the maximum rotation speed in the recovery of engine rotation speed to rated rotation speed caused by the abrupt reduction of the load is regulated in a range of prescribed rotation speed per unit time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a work vehicle equipped with a common rail engine.

  Conventionally, in an engine mounted on a tractor, an all-speed governor is used as a governor device that can perform a speed control operation in a range of all engine speeds from an idling speed to a maximum speed. This all-speed governor increases or decreases the engine torque in response to changes in the engine load to suppress fluctuations in the engine speed, and can stabilize the work speed and the work speed of the work device regardless of the engine load. In general, it has characteristics and is used not only for tractors but also for many other agricultural machines and civil engineering machines.

However, as the main tilling work performed by such a tractor, the working form using the rotary device and the tilling work using the plow device are greatly different from each other. The response by the governor device having one kind of governor characteristic is insufficient. Thus, there is a difference in desirable governor characteristics between plowing work and plowing work, and in the case of setting a single governor characteristic, the emphasis on plowing work and the emphasis on plowing work Since it becomes difficult to work in a suitable characteristic state, the first governor characteristic and the second governor characteristic having different characteristics are provided, and both governor characteristics can be selected, and each selected governor characteristic can be selected. On the basis of the above, there are disclosed ones in which the fuel supply amount adjusting mechanisms are operable (see, for example, Patent Document 1).
JP 2000-314330 A

  However, as described above, even if the first governor characteristic and the second governor characteristic are provided in accordance with the work characteristics in the plowing work and the plowing work by the tractor, the engine according to the load fluctuation is controlled by the adjusting mechanism of the governor device. In the case of adjusting and controlling the fluctuation of the engine speed by increasing or decreasing the torque, when a sudden load change occurs, such as at the start of tillage work or tillage work, automatic tillage in continuous tillage work Since draft control for control and tillage work is not possible, fuel supply sufficient to generate necessary torque due to insufficient adjustment cannot catch up, resulting in poor engine responsiveness and reduced engine speed. The problem was that it could lead to smoke.

In addition, when the engine speed is reduced due to the full load condition, when the load condition is suddenly reduced due to the end of the work at the end of the field, etc., the adjustment mechanism by the governor device causes the engine speed to increase rapidly within a certain range Therefore, the present invention is very dangerous because the airframe accelerates rapidly and the engine speed is increased when a sudden load change occurs, such as at the start of cultivation work in the tractor. To suppress the sudden increase in the engine speed when the load condition is suddenly reduced when the engine speed is reduced due to the full load condition. It is.

  According to the first aspect of the present invention, in a work vehicle equipped with a common rail type engine, position detection means (2) for determining a lowered position of the work machine (1) connected to the work vehicle is provided at an appropriate position. When it is detected in 2) that the work implement (1) has been lowered to the work start position, the rail pressure of the common rail (10) is corrected by a predetermined amount, and this pressure increase correction state is restored to the original state after a predetermined time. It is set as the structure of the working vehicle characterized by returning.

  With such a configuration, in a work vehicle equipped with a common rail engine, the work machine (1) connected to the work vehicle performs work, but the work vehicle is lowered to the work position and is in a work start state. When detected by the detection means (2), a sudden increase in load at the start of work is predicted, and the rail pressure of the common rail (10) at the time of transition is corrected in advance by a predetermined amount to the required torque. It is possible to improve the responsiveness of the engine by enabling fuel supply and returning to the original rail pressure after a predetermined time required for the correction processing.

  The invention according to claim 2 is configured such that the work on the work machine (1) is performed by isochronous control, and when the engine speed is reduced in the full load state during the work, the engine speed is reduced by abrupt reduction of the load state. The construction of the work vehicle according to claim 1, wherein the maximum rotational speed when the number is about to return to the rated rotational speed is regulated within a predetermined rotational speed per unit time.

  With such a configuration, when the work machine (1) performs work, it is performed using isochronous control. At this time, if the work load is close to the full load and the engine speed is decreasing, the reduced engine speed will return to the rated speed due to abrupt reduction of the load state due to the end of work, etc. However, by limiting the maximum engine speed at the time of this return rise to a predetermined speed (per unit time) that suppresses the sudden rise speed, it suppresses sudden acceleration of the engine speed. can do.

  According to the first aspect of the present invention, when the work machine (1) connected to the work vehicle equipped with the common rail engine is lowered to the work position and is in the work start state as described above, the work starts. By predicting an abrupt increase in load at times, the rail pressure of the common rail (10) at the time of transition is corrected in advance by a predetermined amount to allow fuel supply for the required torque. It is difficult for the governor device to deal with by returning to the original rail pressure after the lapse of a predetermined time necessary for this correction processing, thereby correcting the increase in the indicated rail pressure in advance to eliminate the rail pressure deviation. Since it is possible to compensate for the control region, it is possible to improve the engine responsiveness, to prevent a decrease in the engine speed against a sudden load increase, and to suppress the occurrence of smoke. ) Can be performed smoothly.

  In the invention of claim 2, as described above, when the work machine (1) is working using isochronous control, the work load becomes close to the full load and the engine speed is reduced. In this case, the maximum engine speed when the engine speed, which has been reduced due to sudden reduction of the load state, is going to return to the rated speed and increase, is set to the predetermined speed (unit time). To the range of hits). As a result, even in isochronous control with good rotation recovery, the engine speed returns slowly, so that the engine speed does not increase suddenly, preventing sudden acceleration of the fuselage and ensuring safe operation of the work vehicle The work according to (1) can be performed.

A tractor equipped with a common rail type diesel engine will be described as an example.
When the position detection means 2 for determining the lowering position of the work machine 1 (cultivation apparatus) connected to the tractor is provided at an appropriate position, and when the position detection means 2 detects that the cultivation apparatus 1 has been lowered to the cultivation work start position A rail pressure correction device for correcting the rail pressure of the common rail 10 by a predetermined amount and returning the pressure increase correction state to the original state after a predetermined time. In addition, in a tractor equipped with a common rail diesel engine, when the engine speed is reduced due to the full load state during the cultivation work by isochronous control by the cultivation device 1 connected to the tractor, the engine speed is reduced by sudden reduction of the load state. A sudden acceleration prevention device that regulates the maximum rotational speed when the motor tries to return to the rated rotational speed to a predetermined rotational speed (per unit time).

  The common rail type (accumulation type fuel injection) adopted in the common rail type diesel engine E is a common rail 10 (accumulation chamber) that adjusts the fuel supply to the fuel injection device that injects fuel into each cylinder to the required pressure. Is what you do.

  The outline of the operation of the common rail 10 is as follows. As shown in the system diagram of FIG. 3, the fuel in the fuel tank 11 is sucked into the high-pressure pump 13 driven by the engine E through the fuel filter 12 through the suction passage. The high-pressure fuel pressurized by the pump 13 is guided and stored in the common rail 10 by the discharge passage 14.

  The high-pressure fuel in the common rail 10 is supplied to the injectors 17 corresponding to the number of cylinders through the high-pressure fuel supply passages 16, and the injectors 17 are opened for each cylinder based on a command from an engine control unit 18 (hereinafter referred to as ECU). In operation, high-pressure fuel is injected and supplied into each combustion chamber of the engine E, and surplus fuel (return fuel) in each injector 17 is guided to a common return passage 20 by each return passage 19. Returned to the fuel tank 11.

  Further, a pressure control valve 21 is provided in the high-pressure pump 13 for controlling the fuel pressure (common rail pressure) in the common rail 10, and this pressure control valve 21 is sent from the high-pressure pump 13 to the fuel tank 11 by a duty signal from the ECU 18. This adjusts the flow area of the return passage 20 for surplus fuel to the rail, and the rail pressure can be controlled by adjusting the fuel discharge amount to the common rail 10 side.

  Specifically, the target common rail pressure is set according to the engine operating conditions, and the common rail pressure is fed back via the pressure control valve 21 so that the rail pressure detected by the rail pressure sensor 22 matches the target rail pressure. Control.

  As shown in the table of FIG. 4, the ECU 18 of the common rail diesel engine E in the farm work machine has three types of control modes, a traveling mode M1, a normal working mode M2, and a heavy working mode M3, in relation to the rotational speed and the output torque. Yes.

  The traveling mode M1 is used when traveling without farming as droop control in which the output fluctuates due to fluctuations in the rotational speed. For example, when the traveling speed is reduced or stopped by applying a brake, As the traveling load increases, the engine speed decreases, so the traveling speed can be reduced or stopped safely.

  The normal work mode M2 is used when performing normal farm work as isochronous control in which the rotation speed is constant and the output is changed according to the load even when the load fluctuates. Sometimes, when the cultivated land is hard and resistance is applied to the cultivating blade, the combine makes it easy for the operator to control the output and maintain the number of rotations even when there is a lot of harvest during harvesting and the load increases.

  In the heavy work mode M3, as in the normal work mode M2, the isochronous control that changes the output according to the load at a constant rotation speed even when the load fluctuates, and when the load limit is approached, the rotation speed is increased to increase the output. Control with heavy load control, especially used when farming near the load limit.For example, when plowing with a tractor, engine output even when encountering hard cultivated land Increases beyond the normal limit, so work is not interrupted.

  These work modes M1, M2, and M3 are configured to be switched by an operation of a work mode changeover switch, a shift operation of a travel shift lever, an operation of turning on and off a work clutch, or the like.

  Conventionally, in a diesel engine, it is known to perform pilot injection that injects a small amount of fuel in a pulse manner prior to main injection, thereby shortening the ignition delay and reducing the so-called knocking noise peculiar to the diesel engine. .

  This pilot injection is performed once or twice before the main injection. However, by using the system of the common rail 10, the state of the pilot injection is changed according to the state of the engine. The generation of white smoke or black smoke due to noise reduction or incomplete combustion can be suppressed.

  The tractor T equipped with the diesel engine E having the common rail 10 includes front wheels 23 and 23 and rear wheels 24 and 24 at the front and rear portions of the fuselage, as shown in the overall configuration of FIGS. 5 and 6. The rotational power of the mounted engine E is appropriately changed by a transmission in the transmission case M and transmitted to the front wheels 23 and 23 and the rear wheels 24 and 24.

  A steering handle 27 is supported on the handle post 26 in the cabin 25 and a seat 28 is provided behind the steering post 27 in the cabin 25. Below the steering handle 27, the advancing direction of the fuselage is switched to the front-rear direction. A forward / reverse lever 29 is provided. When the forward / reverse lever 29 is moved to the front side, the aircraft moves forward, and when it is moved backward, the aircraft moves backward.

  An accelerator lever 30 for adjusting the engine speed is provided on the opposite side of the forward / reverse lever 29 with the handle post 26 interposed therebetween, and an accelerator for similarly adjusting the engine speed is provided at the right corner of the step floor 31. The pedal 32 and left and right brake pedals 33L, 33R for operating the left and right rear wheels 24, 24 are provided. A clutch pedal 34 is provided at the left corner of the step floor 31.

  The main speed change lever 35 is located at the left front portion of the seat 28, the sub speed change lever 36 capable of selecting any of low speed, medium speed, high speed and neutral positions is located behind the main speed change lever 35, and further on the right side is the PTO speed change lever 37. Is provided. Further, on the right side of the seat 28, a position lever 38 for setting the height of the rotary device 1 as the tilling device 1, an automatic tilling lever 39 for automatically setting the tilling depth of the field, and a rotary after these levers. A right-up switch 40 and a right-down switch 41 of the apparatus 1 are arranged, and an automatic horizontal apparatus 42 and a backup switch 43 of the rotary apparatus 1 are arranged after that.

  The backup switch 43 automatically raises the rotary device 1 when the aircraft is moving backward. The rotary device 1 is connected to the rear of the aircraft by a link 44, and detects the lifting action position of the rotary device 1. A position sensor 2 as position detecting means 2 such as a potentiometer is provided at an appropriate position of the link 44.

  The tractor T performs operations such as tillage in the field by driving the rotary device 1 and running the machine body. When a sudden load change occurs at the start of the tillage work, the common rail Since the rail pressure of 10 does not catch up with the indicated value of the ECU 18 and is actually a small value, smoke is generated and fuel for securing necessary torque is insufficient, and the response of the engine E is poor. As a result, there was a problem that the engine speed decreased.

  For this reason, as shown in the flowchart of FIG. 1, when the position sensor 2 detects that the rotary device 1 is lowered to the plowing work position and is in a work start state, the load is suddenly increased at the start of the work or the like. Thus, the rail pressure of the common rail 10 at the time of transition is corrected in advance by about 10 megapascals.

  This rail pressure increase correction makes it possible to supply the fuel for the required torque by correcting the rail pressure during the transition in advance by a predetermined amount, and after the predetermined time required for this correction processing, the original rail pressure is corrected. The response to the engine E is improved by preliminarily increasing the indicated rail pressure at the time of transition to eliminate the deviation of the rail pressure, thereby improving the response of the engine E and increasing the engine speed against a sudden load increase. The fall prevention and the generation of smoke can be suppressed, and the tilling work by the rotary device 1 of the tractor T can be smoothly performed.

  Further, when the rotary device 1 is driven in the tractor T to perform the tilling work by isochronous control, when the engine speed is reduced due to the full load state, an operation of raising the rotary device 1 by the end of the work at the field end or the like is performed. When doing so, the load condition was suddenly reduced and the engine speed increased rapidly, which caused the aircraft to accelerate rapidly and was extremely dangerous.

  Therefore, as shown in the flowchart of FIG. 2A and the diagram of FIG. 2B, when the instruction output is 90% or more and the engine speed is 2000 rpm or less with respect to the full load output by the ECU 18, that is, In the state where the engine speed is reduced in the full load state, when the load state is suddenly reduced by raising the rotary device 1 due to the end of work at the end of the field, the engine speed is changed from the current speed to the rated speed. The return action is ascending.

  The maximum rotational speed of the engine speed at the time of returning to the rising state can be regulated within a predetermined rotational speed (per unit time) range in which the rapid ascent speed is suppressed by controlling the rail pressure of the common rail 10. Even in isochronous control with good returnability, the engine speed returns slowly, so that the engine speed does not increase suddenly, and sudden acceleration of the airframe is prevented and the tilling work by the rotary device 1 of the tractor T is safe. It can be performed.

  In addition, in the tractor T, when the plowing operation is being performed, the rotation of the headland at the end of the field and the like, after the end of the turn, the engine speed (vehicle speed) returns faster than the start of plowing in the conventional control. There was a problem that a lot of uncultivated land area remained on the ground.

  For this reason, when the tractor T turns in the tillage operation, the engine speed is decreased by isochronous control, and when the steering handle 27 is rotated more than a predetermined value, the rotary device 1 is automatically raised and the rear wheels 24 and 24 are moved. When the brake is activated and then the steering wheel 27 is returned to the substantially straight traveling state, the automatic turning control is performed such that the brake operation of the rear wheels 24 and 24 is released, and then the rotary device 1 is manually lowered.

  When the rotary device 1 is lowered, as shown in the flowchart of FIG. 7, when the fuel injection amount becomes 50% or more of the full load as monitored by the ECU 18, it is determined that tillage has started and the engine speed is Control to start rising and return to the rated speed.

  By performing such control, the engine speed (vehicle speed) is about to return immediately after the rotary device 1 starts plowing. Therefore, from the conventional turning state as shown in the diagram of FIG. The turning state of the present plan as shown in the diagram of FIG. 8 (b) is achieved, so that the area of the uncultivated land portion at the headland or the like at the end of the field can be reduced, and waste can be eliminated and the tilling time can be shortened. In addition, since control for increasing the engine speed starts immediately after the start of tilling, the tilling operation can be smoothly performed without causing a decrease in the rotation of the engine E.

  Further, as shown in the diagram of FIG. 9, when the steering handle 27 is turned more than a predetermined time in the all speed control without using the isochronous control, the automatic turning control as described above is performed when turning the tractor T in the tillage work. After that, the accelerator opening is once returned to 80%, and when it is determined that the tilling is started by the position detection of the rotary device 1 by the position sensor 2, the accelerator opening is controlled to return to 100%.

  By performing such control, the accelerator can be returned in two stages, so that the engine speed (vehicle speed) at the start of tilling is lower than that when the accelerator is 100%, and the initial load is reduced. The occurrence of smoke can be suppressed. In addition, since the accelerator opening is set to 100% simultaneously with the start of tilling, the decrease in the engine speed due to the load can be corrected to prevent the decrease.

  In the case of the engine E having a boost pressure sensor for detecting the boost pressure b and an atmospheric pressure sensor for detecting the atmospheric pressure, a sensor failure check is performed by comparing the detection values of the two sensors. However, there are not many examples that have been developed until these two sensors detect abnormality of the intake system.

  As shown in the conceptual diagram of FIG. 10A, the smaller of the two types of the torque limit by the accelerator opening a that limits the fuel injection amount of the engine E and the smoke limit by the boost pressure b is the final fuel. This is used as an injection amount restriction. When engine E is in steady operation, fuel is restricted by torque limit. Conversely, when boost pressure b is low and fuel is restricted by smoke limit, turbocharger supercharging delay is assumed. Is done.

  In such a state, as shown in the flowchart of FIG. 10 (b), in a normal working state excluding special operating conditions such as a free accelerator, particularly in the case of a combine, in an isochronous control state where the accelerator and the engine speed are constant. Since there is a lot of work with rated speed, boosting is performed over the normal smoke limit map 1 with the engine speed reduced below the threshold (torque point, etc.) using the smoke limit function using the boost pressure sensor. If the fuel injection amount is limited by the smoke limit map 2 provided with the pressure b as a lower limit, it is difficult to consider that the boost pressure b has not increased to the reference value as a normal state. The existing sensor is used as a malfunction of the intake system due to clogged air cleaner or leaking boost pressure. It can be easily detected by the low-cost structure.

  Further, in the engine E, the smoke limit map or the accelerator filter provided for suppressing the discharge of the black smoke against the sudden load can be switched by a selection switch, and the selection switch is set at the time of working (cultivation). Or a heavy work such as mowing) or a non-working (light work such as movement) can be installed at a part (for example, a work machine drive lever or a PTO switch) that can be detected and detected, and can be switched autonomously.

  With such a configuration, in the case of a farm work machine, it is possible to clearly determine when working or not working based on the position of the work machine drive lever or the like. Therefore, as shown in the flowchart of FIG. 11, signals based on these judgments are used. By setting the appropriate smoke limit map or accelerator filter by autonomously switching to the smoke limit map 1 or accelerator filter 1 when working, and the smoke limit map 2 or accelerator filter 2 when not working, The emission gas (black smoke) can be reduced.

  In the conventional electronic control engine, as shown in FIG. 12, the generation of an angle pulse by the crank wheel 46 that rotates in synchronization with the crankshaft 45 is read by the angle sensor 47, and at half the engine speed. The cam wheel 48, the cam sensor 49, and the ECU 50 that determine the ratio determine the stroke of each cylinder, and after the determination, fuel injection is started. Therefore, the cylinder cannot be determined while the crankshaft 45 rotates twice, and mechanical control is performed. There was the difficulty that startability was inferior to the engine.

  In order to improve these difficulties, the IC chips # 1, # 2, # 3 embedded in the recognition protrusion p corresponding to the top dead center of each cylinder provided in the cam wheel 48 before the stroke determination immediately after the engine is started. , # 4, the stroke can be discriminated, so that the starting time can be shortened by discriminating the cylinder, and the startability can be improved.

  In addition, the baffle plate 52 provided in the head cover 51 attached to the cylinder head of the engine has conventionally been provided with a hole for dropping oil that has got on the plate 52 due to pressure balance when the temperature drops. During operation (during high temperatures), the oil lifted from this hole and had an adverse effect.

  In order to improve such adverse effects, as shown in FIGS. 13 (a) and 13 (b), by mounting the shape memory alloy m in the hole h of the baffle plate 52, the hole h is closed during engine operation. In the case of the open air type (open type), it can act to prevent the oil from being lifted, and the hole h can be opened during stoppage (during low temperature) to cause the oil accumulated during operation to drop downward. In addition to being able to give consideration to the environment such as dripping prevention on the road surface and floor surface, in the case of a reduction type, the durability reliability is improved by avoiding losses to the turbocharger and intake system parts by sucking oil into the intake side. Can be planned. In addition, both types have the advantages of reducing oil consumption and improving maintainability.

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

The flowchart which shows the procedure which carries out pressure increase correction | amendment of the rail pressure of a common rail at the time of the cultivation work of a tractor. (A) The flowchart which shows the procedure which regulates the rapid raise of an engine speed by sudden load reduction at the time of tilling work of a tractor. (B) The diagram which shows the return state of the engine speed by sudden load reduction at the time of tilling work of a tractor. The system figure which shows the pressure accumulation type fuel injection diesel engine by a common rail. The diagram which shows the relationship between the engine speed and output torque by three types of control modes. The side view which shows the whole structure of the tractor which connected the rotary apparatus. The top view which shows the whole structure of a tractor. The flowchart which shows the procedure which raises and returns an engine speed by the fall of the rotary apparatus after turning at the time of the tilling work of a tractor. (A) The diagram which shows the state in which many uncultivated land parts in a headland etc. remain according to the increase timing of the engine speed after turning conventionally. (B) The diagram which shows the state in which the uncultivated land part in a headland etc. decreases according to the rise time of the engine speed after turning in this plan. The diagram which shows the state which divides and returns accelerator opening in two steps after turning and at the time of tilling start. (A) The conceptual diagram which shows the state of the fuel injection quantity by a torque limit (accelerator opening degree) and a smoke limit (boost pressure). (B) A flowchart showing a procedure for detecting an abnormality in the intake system based on a smoke limit map due to a decrease in rotation below a threshold when the engine speed is constant. The flowchart which shows the procedure which switches a smoke limit map or an accelerator filter autonomously by the prediction detection at the time of work or non-work. FIG. 5 is an operation diagram showing a state in which cylinder discrimination is performed by an IC chip provided on a cam wheel recognition protrusion of an electronically controlled engine. (A) The side view which shows the state (at the time of high temperature) which closed the hole of the baffle plate provided in the cylinder head of the engine with the shape memory alloy. (B) The side view which shows the state (at the time of low temperature) which opened the hole of the baffle plate provided in the cylinder head of the engine with the shape memory alloy.

Explanation of symbols

1 Working machine (cultivation equipment)
2 Position detection means (position sensor)
10 Common rail E Common rail engine T Work vehicle (tractor)

Claims (2)

  In a work vehicle equipped with a common rail engine, position detection means (2) for determining the lowered position of the work machine (1) connected to the work vehicle is provided at an appropriate position, and the position detection means (2) allows the work machine (1 ) Is lowered to the work start position, the rail pressure of the common rail (10) is corrected by a predetermined amount, and this pressure increase correction state is returned to the original state after a predetermined time. car.   The work machine (1) is configured to perform the work by isochronous control, and when the engine speed is reduced at the full load during the work, the engine speed is restored to the rated speed by abrupt reduction of the load state. The work vehicle according to claim 1, wherein the maximum rotational speed at the time of trying is regulated within a range of a predetermined number of revolutions per unit time.

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