JP2006217846A - Control system for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control system for working vehicle, working in such a way that a torque is calculated based on engine revolutions and fuel injection levels and torque variations are sensed in making a work, and when the torque variations come to a predetermined mode, it is judged that a slip occurred, thus making a control ensuring such a slip not to occur, in view of the fact that accurate load variations have been unable to be sensed so far. <P>SOLUTION: In a working vehicle loaded with a diesel engine equipped with an electronically controlled fuel injector and a means for calculating injection level for each cycle, there are also equipped a means 33 to detect the revolution of the crank shaft 25 of the engine, a working implement 7, an injection level control means for the fuel injector, a working implement lift control means and a working vehicle speed control means. The control system for the working vehicle works as follows: An engine torque is calculated based on fuel injection levels and engine revolutions, and it is judged that a wheel slip occurred when there is a sharp torque decrease following a sharp torque increase within a predetermined time discretionarily set in advance and the torque is sustained for a discretionarily set time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for accurately detecting a load and preventing engine stall and improving work accuracy and finish in a work vehicle equipped with a diesel engine equipped with an electronically controlled fuel injection device.

Conventionally, in a work vehicle equipped with a work machine, various techniques for detecting a load and performing control to improve work efficiency are known.
For example, a three-point link type work machine mounting device is disposed at the rear of the tractor, and a strain gauge type draft sensor is provided at the top link base of the work machine mounting device to detect a traction load. When the traction load detected by the sensor exceeds a certain level, the lift arm is controlled to be lifted by a certain amount (see, for example, Patent Document 1).
In the draft control mode, the traction load detected by the draft sensor is compared with the load set by the draft setting device, and the hydraulic cylinder is controlled to move up and down so that the traction load becomes the target traction load. When the torque fluctuation rate is large due to the electronic governor, the maximum torque point is shifted to the low speed side, and control is performed so that the torque curve characteristic becomes sticky in the high load region, so that the plow work The engine is also controlled so as to be suitable for the above (see, for example, Patent Document 2).

On the other hand, it has an engine speed detection means, an engine load detection means, a vehicle speed detection means, a vehicle running state detection means, and a rotation speed change rate detection means, and calculates a correction value of the supplied fuel according to the speed change rate. And the technique which supplied the fuel according to the correction value and was able to obtain the stable driving | operation is also well-known (for example, patent document 3).
Also, the target fuel injection amount and the current fuel injection amount, that is, the control rack position is detected, the load factor is calculated, the load is detected without using the draft sensor, and the lifting hydraulic cylinder is set so that the set load factor is obtained. A technique for controlling the above is also known (for example, Patent Document 4).
Further, the load applied to the engine is detected from the engine speed and the rack position, and the load deviation is calculated from the first engine load torque of the engine speed in this arbitrary span and the second engine load torque in the subsequent arbitrary span. A technique for obtaining and correcting the tilling depth deviation with a correction amount based on the load deviation is also known (for example, Patent Document 5).
In addition, the first engine load torque and the second engine load torque are obtained at fixed cycles (spans) to obtain the engine load change, and the load is accurately determined by reducing the influence of engine speed fluctuations and errors. A technique for detecting the load applied to the working unit to keep constant or keeping the rotation speed constant is also known (for example, Patent Document 6).
JP 2000-170564 A JP 2000-31505 A Japanese Patent Laid-Open No. 10-30470 Japanese Patent Laid-Open No. 10-309106 JP 2000-92913 A JP 2000-97100 A

  As described above, when the draft control is performed, in the configuration in which the traction force is directly detected using the load detection means such as a strain gauge, the detection means for directly detecting the traction force is required, the number of parts is increased, and wiring is also required. Therefore, the assembly man-hours increase and the cost increases.

In addition, when the load is calculated based on the engine speed and the position of the control rack and the height (plowing depth) and speed of the work implement are changed, the speed can be detected instantaneously. Because the sensor rack detects the position of the control rack after movement, the response delays and the load becomes too large and the engine stalls, or the finish changes slightly due to the delay in raising and lowering the work equipment. Further, even when the fuel injection amount is changed, the fuel rack is driven, so that a further delay occurs.
Therefore, the present invention uses an engine equipped with an electronically controlled fuel injection device as an internal combustion engine, calculates torque from the engine speed and the fuel injection amount, and detects the change state of the torque during operation. When the torque change has a predetermined shape, it is determined that the slip has occurred, and control is performed so that this slip does not occur.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  That is, in claim 1, in a work vehicle equipped with a diesel engine equipped with an electronically controlled fuel injection device and having means for calculating the injection amount for each cycle, the means for detecting the rotation of the crankshaft of the engine And a working machine mounted on the work vehicle, an injection amount control means for the fuel injection device, a means for controlling the lifting and lowering of the work machine, and a work vehicle speed control means. The engine torque is determined by the fuel injection amount and the engine speed. Is calculated, and after a sudden torque increase within a predetermined time arbitrarily set in advance, there is a sudden torque decrease, and when the torque lasts for a set time arbitrarily, it is determined that the wheel slips.

  According to a second aspect of the present invention, when the load calculated from the torque exceeds a predetermined value, the work implement is controlled to increase by a predetermined amount.

  According to a third aspect of the present invention, when the load calculated from the torque exceeds a predetermined value, the traveling speed is controlled to be decreased by a predetermined amount.

  According to a fourth aspect of the present invention, there is provided means for selecting whether the work implement is controlled to increase by a predetermined amount or the traveling speed is controlled to decrease by a predetermined amount when the load calculated from the torque exceeds a predetermined value. Is provided.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, it is not necessary to arrange a sensor for directly detecting the torque or the load, and the rapid torque fluctuation or the load fluctuation is detected quickly to reduce the cost while reducing the load and reducing the slip as much as possible. As a result, it is possible to deal with the problem quickly so that the work efficiency can be improved.

  In claim 2, when the load exceeding the set value increases, the work implement is raised, the load is reduced, the work can be continued without substantially reducing the traveling speed, the finish can be made clean, and the workability is also lowered. There is nothing.

  In claim 3, when the load exceeding the set value is increased, the traveling speed is reduced, the torque is increased, the work machine height (plowing depth) can be continued with almost no change, and the uniform depth. Can work.

  In claim 4, according to the state of the work place, the type of work, etc., it is possible to select whether the work implement is raised or the traveling speed is lowered, and the finish is most suitable for the work. Will be able to.

Next, embodiments of the invention will be described.
FIG. 1 is an overall side view of a tractor equipped with the load control device of the present invention, FIG. 2 is a control block diagram, FIG. 3 is a diagram showing changes in torque, and FIG. 4 is a diagram showing a control flowchart.

In this embodiment, a case will be described in which a work vehicle is a tractor, a plow is employed as a work machine mounted on the tractor, and a diesel engine equipped with an electronically controlled fuel injection device is employed as an internal combustion engine.
First, as shown in FIG. 1, the tractor 1 mounts a diesel engine 11 as an internal combustion engine on a front frame 2 at the front of the machine body, and the engine 11 is covered with a bonnet 6. A handle 10 is disposed at the rear of the bonnet 6, and a seat seat 12 is disposed behind the handle 10. A front wheel 4 is supported below the front frame 2, and a rear wheel 5 is supported on a transmission case 13 below the seat 12 via a rear axle housing. An accelerator lever as a rotational speed setting means is arranged in the vicinity of the handle 10, and a speed change lever 14 as a speed change means, a load setting device (plowing depth setting lever) 36 as a load setting means, etc. are arranged in the vicinity of the seat 12. The steering wheel 10, the seat seat 12, and the like are covered with a cabin 15 and serve as a driving operation unit 9.

  Further, a plow 7 as a towing work machine is attached to the rear portion of the tractor 1 via a three-point link type work machine mounting device 3. However, the working machine is not limited to the plow, and a rotary tiller, a mower, an excavator, a loader, or the like can be attached. The work implement mounting device 3 includes a top link 16 pivotally supported by a hitch bracket attached to the rear surface of the mission case 13, lower links 17 and 17 pivotally supported at the rear lower portion of the mission case 13, the lower link 17 and a lift arm. 18 and a lift rod 19 that connects the two.

The engine 11 includes an electronically controlled fuel injection device, and the control device 31 controls the valve opening of the electromagnetic injector 22 so that the rotation of the crankshaft 25 can be controlled. For example, in the case of a common rail type engine, fuel is pumped from a supply pump (high pressure port) 28 to the common rail 26, injected into the combustion chamber by opening the electromagnetic injector 22, and burned to reciprocate the piston 21 to drive the crankshaft. 25 is rotated. As shown in FIG. 2, a piston 21 is fitted into the cylinder 20 so that it can be moved up and down, and a fuel injection valve (injector) 22 is provided in the cylinder head above the cylinder 20 to inject fuel into the combustion chamber. I am doing so. The fuel injection valve 22 is provided with a solenoid 22a for controlling fuel injection to constitute an electromagnetic control valve (electromagnetic injector). By applying a control voltage to the solenoid 22a, the fuel injection valve 22 is opened and closed to provide fuel. Are injected and burned at a predetermined timing to drive the piston 21 up and down. The piston 21 is pivotally supported at the upper end of a connecting rod 24, and a crankshaft 25 serving as an output shaft is connected to the lower portion of the connecting rod so that the reciprocating motion of the piston 21 is converted into rotation of the crankshaft 25 and driven. I have to. That is, the output rotation of the engine 11 can be controlled by adjusting the fuel injection amount and the injection timing by controlling the opening and closing of the fuel injection valve 22.
Power is transmitted to the crankshaft 25 via the clutch or the transmission in the transmission case 13 to the rear wheel 5 or the front wheel 4 serving as drive wheels.

  The fuel injection valve 22 is connected to a common rail 26 serving as a fuel high-pressure accumulator. The common rail 26 is connected to a high-pressure pump 28 via a pipe 27. A common rail is provided between the common rail 26 and the high-pressure pump 28. A valve for maintaining a predetermined pressure is interposed in the valve 26. The high-pressure pump 28 is connected to a fuel tank 29 through a filter. A pipe for returning excess fuel to the fuel tank 29 is connected to the high-pressure pump 28 and the fuel injection valve 22. In the present embodiment, a single cylinder will be described, but the present invention can also be applied to a multi-cylinder engine.

The solenoid 22a is connected to a control device 31. The control device 31 has a pressure sensor 30 as a means for detecting the pressure in the common rail 26, and a pressure for adjusting the fuel pumping amount of the high-pressure pump 28. A control solenoid valve 32, a rotation speed sensor 33 for detecting the rotation speed of the crankshaft 25, an angle sensor 34 for detecting the angle of the crankshaft 25 or the camshaft, and an accelerator pedal or an accelerator lever as means for setting the rotation speed And a target load setting unit 36 that links a target load (traction force or tilling depth) with a setting lever or knob.
Further, the control device 31 is connected to an electromagnetic valve 37 for controlling the supply of pressure oil to the hydraulic cylinder for raising and lowering the work implement. The opening and closing of the electromagnetic valve 37 is controlled, pressure oil is supplied to the cylinder 38, and the lift arm 18 is turned up and down so that the work implement can be raised and lowered. The rotation of the lift arm 18 is detected by an angle sensor 42 disposed at the base thereof. The control device 31 includes a CPU (Central Processing Unit), a memory (ROM, RAM, etc.), an input / output circuit, a drive circuit, and the like.

  In this way, the output signal from the sensor is input to the control device 31 to calculate the target rotational speed and various states related to the operation, and the fuel injection is performed so that the rotational speed set by the rotational speed setter 35 is obtained. The fuel injection amount and the injection timing are controlled by controlling the valve 22 and the pressure control electromagnetic valve 32.

Next, a specific embodiment for calculating the engine torque and controlling the load so as to become the set load when there is a load variation will be described.
In the case of an engine equipped with an electronically controlled fuel injection device, when the engine speed is set by the engine speed setting device 35 and driven, the control device works to obtain the engine speed, and the engine speed at that time Torque can be calculated by detecting the fuel injection amount. That is, the engine speed is detected by the speed sensor 33, and the fuel injection amount can be calculated from the opening amount of the fuel injection valve 22, that is, the control signal to the solenoid 22a. A torque at an arbitrary time is calculated using a map or the like based on the engine speed and the fuel injection amount.

When the load changes suddenly during work, for example, when the plow 7 is attached to the work implement mounting device 3 and the towing work is performed at the set rotational speed, the load changes rapidly as follows. To control.
As shown in FIG. 3, the calculated torque is substantially T1 in a state where no overload is applied when working at the set rotational speed. If this torque rises rapidly at time t1, falls sharply from time t2 immediately after that, and torque converges continuously at time T3 from time t3, it is determined that the drive wheel has slipped. The work machine is raised by a predetermined amount or the predetermined speed is lowered so that the work can be continued. However, the rapid increase and decrease waveforms of the torque, that is, the time from t1 to t2, the time from t2 to t3, the torque difference between T1 and T2, and the torque difference between T2 and T3 are set respectively. Each allowable range (threshold value) is also set, and each value is stored in the memory so that it can be determined whether or not the waveform is as shown in FIG.

  For example, when the plow 7 hits a hard tiller when the engine is operated at the set rotational speed and the towing work is performed, the load increases rapidly. That is, the torque suddenly increases, the aircraft can hardly move forward, and the wheels are idle and slip. When this slip occurs, the torque decreases and the state is maintained, and the waveform is substantially the same as that shown in FIG.

When slip is detected with such a waveform, at time t4, the work implement is raised by a predetermined amount to reduce the load so that the work can be continued. That is, the hard tiller is avoided by the rise of the work implement, does not slip, and moves forward to return to the original torque T1. At this time, the forward speed returns to the speed before the torque fluctuation occurs, but since the tilling depth is shallow, the load gradually becomes smaller than the torque T1, so the work implement is lowered to the original height and the load is reduced. The torque T1 is restored to the state before the operation is started, and the operation is continued with the set load.
With this configuration, it is possible to detect an overload from torque fluctuation, prevent the work from being disabled, and continue the work.

In addition, the following control can be performed to prevent a reduction in work efficiency.
That is, control is performed so as to decrease the traveling speed at time t4 after the torque fluctuation occurs. When the traveling speed is reduced in this way, the torque increases and the hard cultivator can be pushed forward. At this time, there is almost no change in tilling depth, so the finish is beautiful. The means for slowing down the traveling speed is shifted to the low speed side by moving the speed change arm or speed change lever by an actuator such as a motor 41 or solenoid or cylinder. For example, a motor 41 is used as the actuator, the motor 41 is connected to the speed change lever 14, and the motor 41 is connected to the control device 31 via the drive circuit 40, and a control signal from the control device 31 is used. The speed change lever 14 is rotated to change the speed.

In this way, when a sudden torque fluctuation such as the waveform shown in FIG. 3 occurs where the torque suddenly increases and then decreases, it is determined that the control device 31 has slipped, and the speed change lever 14 is rotated to the low speed side. Lower the gear position of the transmission. That is, the actuator such as the motor 41 is driven so that the speed change arm of the speed change device or the speed change lever 14 of the driving operation unit 9 is rotated to the lower speed side so as to increase the speed ratio and decrease the output side rotational speed. To control. However, although it is possible to reduce the speed by reducing the rotational speed, it is not preferable because the torque is also reduced.
Then, when returning to the normal hard cultivator, the rotational speed increases and the torque also increases, so that the motor 41 is driven so that the transmission becomes the original gear position.

  In addition, when a sudden torque variation as described above occurs, it is possible to select whether to raise the work machine or reduce the vehicle speed. In other words, it may be more convenient to control either one depending on the work place, the work content, or the like. For example, in the case of an operation for forming a bowl-shaped ridge, if the speed decreases during the operation, the rotational speed of the rotary does not change, so there is some soil (roughness) and the shape changes to the size of the ridge. I can do it. Therefore, in the case of such work, it is preferable that the quality of the soil of the straw is substantially constant even if the working machine is lifted to change the tilling depth. In addition, in the case of operations such as forming flat ridges or plowing paddy fields, planting depths of crops such as rice will be different due to differences in plowing depth, resulting in different root elongation and unevenness. A part of the water may come out of the surface of the water, causing uneven growth of the crop and affecting the size of the harvest. Therefore, it is preferable to make the tilling depth constant even if the speed is temporarily reduced.

  Therefore, in order to set the mode, a changeover switch 39 is connected as a selection means to the control device 31, and the changeover switch 39 is disposed in the driving operation unit 9 near the seat so that the type of work, the field, the crop, the work It can also be switched according to the person or the like.

The above control will be described with reference to the flowchart shown in FIG.
At the time of work, the engine speed and the fuel injection amount are always detected, the torque is calculated from the values, and it is detected whether the torque has a torque fluctuation having a waveform as shown in FIG. 3 (S100). . The fuel injection amount is detected every two rotations of the crankshaft 25 (one cycle of the combustion stroke), and the torque is also detected each time. Conventionally, a method of detecting the rack position, calculating the fuel injection amount from the value, and calculating the torque has been adopted. With such a method, the detection cycle becomes longer and the error becomes larger. On the other hand, the present invention calculates torque by calculating the fuel injection amount from the opening of the fuel injection valve 22 in an engine equipped with an electronically controlled fuel injection device, particularly a common rail engine, and detects torque fluctuations. Therefore, sudden torque fluctuations can be determined instantaneously, and control can be performed with high accuracy.

  Then, it is determined whether or not the torque waveform is as shown in FIG. 3, that is, whether or not slip has occurred (S101). If slip occurs, which is the selection position of the changeover switch 39? If the judgment is made (S102) and it is selected to control the tilling depth, the cylinder 38 is extended and the lift arm 18 is lifted and rotated to raise the work implement by a predetermined amount (S103). If the vehicle speed is selected (S104), the motor 41 is driven to drop the transmission to the low speed stage and reduce the vehicle speed by a predetermined amount (S105). If neither the tilling depth nor the vehicle speed is selected, the current state is maintained (S111).

  In step S101, when slip does not occur, torque fluctuation does not occur, or when slip fluctuation does not occur because control is performed to avoid slip after torque fluctuation occurs. Next, it is determined whether or not the work implement has been lifted (S107). If the work implement has been lifted, the work implement is lowered to return to its original height (S108). If the work implement has not been raised, it is determined whether or not it has been decelerated (S109), and if it has decelerated, the transmission is shifted to the speed increasing side so as to return to the original speed (S110). If the work implement is not raised and decelerated, the current state is maintained (S111). By controlling as described above, the work can be stably performed.

The following control can also be performed.
In other words, when torque fluctuation occurs, it is possible to control both the control for raising the work implement and the mode for decelerating the vehicle speed. If it increases, then control is performed on the other side.
That is, the changeover switch 39 is a priority changeover means. For example, when vehicle speed reduction priority is selected by the changeover switch 39, if the load suddenly increases, control is performed to reduce the vehicle speed. If it is larger, the vehicle speed is reduced until it is reduced to a predetermined speed so that a further increase in torque can be obtained. However, if the running speed is too slow, it may stop, or if the speed is further reduced, the work may be adversely affected (excessive grinding, excessive spraying, etc.). Control is performed to raise the work machine that is the control.

  Further, when priority is given to raising the work implement, the work implement is raised due to a rapid increase in load, and when the load is still large, the work implement is repeatedly raised so that the necessary torque can be obtained. However, when the load cannot be reduced even if the work implement is raised, if the work implement is further raised, the predetermined tilling depth may not be obtained. To control.

More specifically, when the priority changeover switch 39 is switched to vehicle speed deceleration priority (plowing depth priority), a mode for lowering the traveling speed is given priority over the mode for raising the work implement when the load increases. Control. When the torque is changed by a predetermined amount or more when the work is performed at the set rotational speed, the motor 41 is operated so as to lower the transmission device by a predetermined step so as to decrease the traveling speed by a predetermined speed. If the torque cannot be increased even when the vehicle speed is reduced by a predetermined amount in this way, the predetermined speed is further reduced. In this way, when the load is large, the vehicle speed is reduced so that the tilling depth does not change.However, because the load is large, when the speed falls below the set speed, the control is automatically switched to a control that raises the work machine by a predetermined amount. is there.
In other words, if work is performed with the plowing depth priority selected and switched, when a sudden torque fluctuation (load increase) occurs and slip is detected, the vehicle speed is decreased by a predetermined amount until the slip can be avoided. If slip does not disappear even when the speed is reduced to the set speed, the work implement is raised by a predetermined amount, the above control is repeated until the desired torque is obtained, and the work is continued without stopping or stopping. This prevents a decrease in efficiency. When returning to the original load, both the vehicle speed and the work implement height (plowing depth) are restored to the original state.

In addition, when the priority changeover switch 39 is switched to work machine ascent priority (vehicle speed priority), control is performed in a mode in which the work machine is raised in preference to the mode in which the vehicle speed is lowered when the load increases. To do. Then, when working at the set number of revolutions, if a torque fluctuation that exceeds the set amount occurs, the hydraulic cylinder is extended so as to raise the work implement by a predetermined height. If the torque cannot be increased even when the work implement is raised by a predetermined amount, the height is further raised by a predetermined height. In this way, when the load is large, the work implement is raised so that the traveling speed does not change. However, if the height (plowing depth) of the work implement becomes higher than the set height due to the large load, Ascending / descending control is stopped so that the depth does not become too shallow, and the control is automatically switched to control for reducing the traveling speed by a predetermined amount.
In other words, when switching is performed with priority being given to vehicle speed, when a sudden torque fluctuation (load increase) occurs and slip is detected, the work implement is lifted by a predetermined amount until slip can be avoided. If slip does not disappear even when the work implement is raised to the set height, the travel speed is reduced by a predetermined amount, and the above control is repeated until the desired torque is obtained, and the work is continued without stopping or stopping. This prevents a reduction in work efficiency. When the original load is restored, the vehicle speed and the work implement height are also restored to the original state.

1 is an overall side view of a tractor equipped with a load control device of the present invention. Control block diagram. The figure which shows the change of a torque. The figure which shows a control flowchart.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tractor 3 Work implement mounting apparatus 11 Engine 14 Shift lever 22 Fuel injection valve (injector)
31 Control Device 33 Speed Sensor 35 Speed Setter 39 Changeover Switch

Claims (4)

  In a work vehicle equipped with a diesel engine equipped with an electronically controlled fuel injection device and having means for calculating the injection amount for each cycle, means for detecting rotation of the crankshaft of the engine, and work attached to the work vehicle Machine, an injection amount control means for the fuel injection device, a means for controlling the lifting / lowering of the work implement, and a work vehicle speed control means, and the engine torque is calculated from the fuel injection amount and the engine speed, and is arbitrarily set in advance. A control apparatus for a work vehicle, characterized in that a sudden torque drop occurs after a sudden torque increase within a predetermined time, and that the wheel slips if the torque lasts for an arbitrarily set time.   2. The work vehicle control device according to claim 1, wherein when the load calculated from the torque exceeds a predetermined value, the work machine is controlled to increase by a predetermined amount.   2. The work vehicle control device according to claim 1, wherein when the load calculated from the torque exceeds a predetermined value, the traveling speed is controlled to be decreased by a predetermined amount.   When the load calculated from the torque exceeds a predetermined value, there is provided means for selecting whether to control the work implement to increase a predetermined amount or to control the traveling speed to decrease by a predetermined amount. The work vehicle control device according to claim 1.

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