JP2018064468A - Work machine lifting control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost of manufacturing a work machine lifting control device.SOLUTION: A work machine lifting control device 100 includes: a hydraulic cylinder 40 for lifting and lowering a plow 20 with respect to a tractor 10; a stroke sensor 80 for detecting a lifting/lowering position of the plow 20; a load sensor 82 for detecting traction force; and a controller 60 for controlling expansion and contraction of the hydraulic cylinder 40. The controller 60 includes a target plow position correction part 63 for correcting a target plow position on the basis of a traction force deviation. The target plow position correction part 63 includes: a draft correction calculation part 66 for calculating a draft correction amount on the basis of draft sensitivity and the traction force deviation; and an avoidance correction calculation part 67 for calculating an avoidance correction amount on the basis of the avoidance sensitivity and the traction force deviation only when the detection value of the load sensor 82 is greater than the target traction force.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a work implement lifting / lowering control device that controls lifting / lowering of a work implement.

  Patent Document 1 discloses a work implement lifting control device that controls the lifting and lowering of a work implement (plow) that is connected to a work vehicle so as to be movable up and down. In this work implement lifting control apparatus, draft control for raising and lowering the work implement according to the traction force with which the work vehicle pulls the work implement is performed.

JP 2012-191857 A

  In the working machine lifting control device described in Patent Document 1, when the work vehicle pulling the working machine slips due to the working machine hitting an obstacle, the working machine is forcibly raised to avoid the obstacle. Executed. In order to detect such slip of the work vehicle, it is necessary to provide a sensor for detecting the rotation speed of the axle and a sensor for detecting the vehicle speed of the work vehicle such as a GPS receiver. For this reason, in the work implement lifting control apparatus that executes control for avoiding obstacles, the manufacturing cost may increase.

  This invention is made | formed in view of said problem, and it aims at suppressing the raise of the manufacturing cost of a working machine raising / lowering control apparatus.

  According to a first aspect of the present invention, there is provided an actuator for elevating and lowering the work machine relative to the work vehicle by extending and contracting, a lift position detector for detecting a lift position of the work machine relative to the work vehicle, and a traction force for the work vehicle to pull the work machine A traction force detector to detect, and a control unit that controls expansion and contraction of the actuator based on a lift position deviation that is a difference between a preset target lift position and a detection value of the lift position detector. It has a target lift position correction unit that corrects the target lift position based on the traction force deviation that is the difference between the set target traction force and the detection value of the traction force detector, and the target lift position correction section converts the traction force deviation to the target lift position. A first correction calculation unit for calculating a first correction amount for correcting the target lift position based on a first sensitivity set in advance and a tractive force deviation based on the first sensitivity, and the first correction amount Further, only when the detection value of the tractive force detector is larger than the target tractive force, the target lift is calculated based on the preset second sensitivity and the tractive force deviation, which is the degree to which the tractive force deviation is reflected in the correction of the target lift position. And a second correction calculator that calculates a second correction amount for correcting the position.

  In the first invention, in a state where the detection value of the traction force detector is larger than the target traction force and the work implement may collide with an obstacle, the target lift position of the work implement is calculated based on the traction force deviation. In addition to the first correction amount, the work implement is corrected in a direction to avoid the obstacle by the second correction amount calculated based on the traction force deviation in the same manner as the first correction amount. For this reason, the work implement can avoid an obstacle even if a detector for detecting the slip of the work vehicle is not provided.

  The second invention further includes a second correction amount initialization determination unit that determines whether the target lift position correction unit initializes the second correction amount, and the second correction amount initialization determination unit includes: The second correction amount is initialized when the detection value of the tractive force detector is smaller than a preset allowable tractive force or when the tractive force deviation is smaller than a preset allowable tractive force deviation. .

  In the second invention, the target lift position of the work implement is corrected by the second correction amount only when there is a high possibility that the work implement will collide with an obstacle, such as when the detection value of the traction force detector exceeds the allowable traction force. Is done. Therefore, since the working machine is not displaced unnecessarily, the work by the working machine can be executed stably.

  The third invention is characterized in that the magnitudes of the first sensitivity and the second sensitivity can be changed by an operator.

  In the third aspect of the invention, the operator can arbitrarily change the magnitudes of the first sensitivity and the second sensitivity according to the situation of the work, so that the stability of the work by the work machine can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the raise of the manufacturing cost of the raising / lowering control apparatus of a working machine can be suppressed.

It is the schematic which shows the structure of a working vehicle provided with the working machine raising / lowering control apparatus which concerns on embodiment of this invention. It is the schematic which shows the operation panel mounted in the working vehicle provided with the working machine raising / lowering control apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the control part in the working machine raising / lowering control apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the control part in the modification of the working machine raising / lowering control apparatus which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  A work implement lifting control apparatus 100 according to an embodiment of the present invention controls lifting of a work implement that is connected to a work vehicle such as a tractor so as to be movable up and down by extending and contracting an actuator.

  First, with reference to FIG. 1, the whole structure of the tractor 10 which is a work vehicle provided with the working machine raising / lowering control apparatus 100 is demonstrated.

  The tractor 10 includes a plow 20 as a work machine, a three-point hitch mechanism 30 that connects the plow 20 to the vehicle body of the tractor 10, and a hydraulic cylinder 40 as an actuator that raises and lowers the plow 20 relative to the tractor 10 by expanding and contracting. A pump 41 that discharges hydraulic oil supplied to the hydraulic cylinder 40, an engine 50 that is a travel drive source of the tractor 10 and that drives the pump 41, and a control valve 45 that controls supply and discharge of hydraulic oil to and from the hydraulic cylinder 40. And a controller 60 as a control unit that controls expansion and contraction of the hydraulic cylinder 40 by controlling opening and closing of the control valve 45. The work implement lifting control device 100 is mainly configured by a hydraulic cylinder 40 that raises and lowers the plow 20 with respect to the tractor 10 and a controller 60 that controls expansion and contraction of the hydraulic cylinder 40.

  The plow 20 is a working machine used for tilling the field, and is pulled by the tractor 10 through the three-point hitch mechanism 30 to crush the topsoil of the field and soften the soil. The working machine is not limited to the plow 20 and may be of any type as long as it can plow the field by being pulled by the tractor 10.

  The three-point hitch mechanism 30 has a pair of lower links 32 whose one end 32 a is swingably connected to the rear lower part of the vehicle body of the tractor 10, and one end 31 a is swingable to the vehicle body of the tractor 10 above the lower link 32. A pair of lift arms 33 that are swingably connected to the rear of the vehicle body of the tractor 10, swing according to the expansion and contraction of the hydraulic cylinder 40, and the other end of the lift arm 33. 33 b and a middle part of the lower link 32, and a lift rod 34 that transmits the swing of the lift arm 33 to the lower link 32. The plow 20 is detachably connected to the other end 31 b of the top link 31 and the other end 32 b of the pair of lower links 32.

  The hydraulic cylinder 40 is a single-acting ram type cylinder having a cylindrical main body 40a and a rod 40b protruding from the main body 40a. The base end portion of the main body portion 40 a is connected to the vehicle body of the tractor 10, and the tip end portion of the rod 40 b is connected to the intermediate portion of the lift arm 33. For this reason, when the hydraulic cylinder 40 is extended, the lift arm 33 to which the rod 40b is connected rotates around the one end 33a, and the other end 33b side moves upward. Accordingly, the lift rod 34 also moves upward, so that the lower link 32 connected to the lift rod 34 rotates about one end 32a and the other end 32b moves upward. As a result, the plow 20 connected to the other end 32b of the lower link 32 also moves upward. As described above, when the hydraulic cylinder 40 extends, the plow 20 rises with respect to the vehicle body of the tractor 10, and when the hydraulic cylinder 40 contracts, the plow 20 descends with respect to the vehicle body of the tractor 10.

  One hydraulic cylinder 40 is provided for each lift arm 33. The hydraulic cylinder 40 is not limited to a ram type cylinder, and may be a single action type or a double action type piston type cylinder. Further, the hydraulic cylinder 40 may be provided on only one of the pair of lift arms 33.

  The pump 41 is a gear pump that sucks and discharges hydraulic oil stored in the tank 42, and is always rotating when the engine 50 is in an operating state. The pump 41 is connected to the hydraulic cylinder 40 via the control valve 45. The pump 41 is not limited to a gear pump, and may be any type of pump such as a piston pump or a vane pump. The drive source of the pump 41 is an electric motor or liquid instead of the engine 50. A pressure motor may be used.

  The control valve 45 opens, and discharges the hydraulic oil in the hydraulic cylinder 40 to the tank 42 by opening the valve and the extension-side electromagnetic valve 45a that supplies the hydraulic oil discharged from the pump 41 to the hydraulic cylinder 40. A contraction-side electromagnetic valve 45b. The extension-side solenoid valve 45a and the contraction-side solenoid valve 45b are opened with an opening area corresponding to the position of the valve body, with the valve body moving to a position where the electromagnetic force generated by energizing the solenoid and the spring force of the spring balance. This is a proportional solenoid valve.

  Opening and closing of the extension side solenoid valve 45a and the contraction side solenoid valve 45b is controlled by the controller 60, and the extension side solenoid valve 45a is opened and the contraction side solenoid valve 45b is closed, so that the hydraulic cylinder 40 is extended. The hydraulic cylinder 40 contracts by closing the electromagnetic valve 45a and opening the contraction side electromagnetic valve 45b.

  The controller 60 includes a CPU (central processing unit) that performs expansion / contraction control of the hydraulic cylinder 40, a ROM (read only memory) that stores control programs and setting values necessary for the processing operation of the CPU, and various sensors. And a RAM (random access memory) for temporarily storing the detected information.

  The controller 60 includes a detection value of a stroke sensor 80 as a lift position detector that detects the lift position of the plow 20 relative to the vehicle body of the tractor 10 and a load as a traction force detector that detects the traction force that the tractor 10 pulls the plow 20. The detection value of the sensor 82 is input. The controller 60 receives a signal from the operation panel 70 operated by the operator. The controller 60 executes position control, draft control, and obstacle avoidance control, which will be described later, based on detection values input from various sensors, parameters input from the operation panel 70, and the like.

  The stroke sensor 80 is assembled to the main body 40a of the hydraulic cylinder 40, and detects the absolute stroke amount of the rod 40b that moves forward and backward with respect to the main body 40a. The stroke sensor 80 has a magnetic detection unit such as a Hall IC, and the stroke sensor 80 outputs an electrical signal corresponding to a change in magnetic field that changes according to the displacement of the rod 40b. The stroke sensor 80 is not limited to the above configuration, and may be of any type as long as the absolute stroke amount of the rod 40b can be detected.

  Here, as described above, the lift arm 33 to which the rod 40 b of the hydraulic cylinder 40 is connected is connected to the lower link 32 via the lift rod 34. For this reason, the stroke amount of the rod 40 b corresponds to the displacement of the plow 20 in the vertical direction with respect to the tractor 10.

  The lift position detector that detects the lift position of the plow 20 relative to the tractor 10 is not limited to the stroke sensor 80 that detects the amount of expansion / contraction of the hydraulic cylinder 40, and corresponds to the displacement of the plow 20 in the vertical direction relative to the tractor 10. Any sensor can be used as long as it can detect the displacement. For example, a rotation angle sensor that detects the rotation angle of the lift arm 33 and the lower link 32 that change when the plow 20 moves up and down with respect to the tractor 10 is provided as a lift position detector. Based on the value, the amount of displacement of the plow 20 in the vertical direction relative to the tractor 10 can be grasped. Further, by providing both the stroke sensor 80 and the rotation angle sensor, the displacement amount of the plow 20 can be accurately detected.

  The load sensor 82 is a load cell formed in a columnar shape, is provided at one end 32 a of the lower link 32, and is used as a connection pin that connects the vehicle body of the tractor 10 and the lower link 32. The load sensor 82 is supported at both ends by the vehicle body of the tractor 10 and at the center by the lower link 32. Between the central portion and both end portions, a strain generating portion that generates strain due to a load acting on the load sensor 82 is provided, and a strain gauge is attached to the strain generating portion. The load sensor 82 outputs an electrical signal proportional to the load by changing the resistance of the strain gauge according to the strain amount in the strain generating portion. Note that the load sensor 82 is not limited to one using a strain gauge, and may be a piezoelectric type using a piezoelectric element or a magnetostrictive type using a magnetostrictive material. The mounting position of the load sensor 82 is not limited to the one end 32 a of the lower link 32, and similarly to the one end 32 a of the lower link 32, the load sensor 82 is attached to one end 31 a of the top link 31 on which a force that pulls the plow 20 acts. There may be.

  As shown in FIG. 2, the operation panel 70 has an operation lever 72 capable of setting the height of the plow 20 relative to the tractor 10, a plurality of dials 73 to 75 for setting parameters input to the controller 60, Is provided. Parameters set by the operation lever 72 and the dials 73 to 75 will be described later.

  Next, a specific configuration of the controller 60 will be described with reference to FIG.

  The controller 60 includes a plow position deviation calculation unit 61 that calculates a deviation between a target plow position as a target lift position of the plow 20 relative to the vehicle body of the tractor 10 and an actual plow position detected by the stroke sensor 80, and a plow position deviation calculation. An expansion / contraction determination unit 62 that determines whether to raise or lower the plow 20 based on the deviation calculated by the unit 61, a target traction force that the tractor 10 pulls the plow 20, and an actual traction force detected by the load sensor 82 A target plow position correction unit 63 as a target lift position correction unit that corrects the target plow position based on the traction force deviation that is the difference between the two. In the following description, the direction in which the depth of the plow 20 decreases, that is, the direction in which the plow 20 rises is defined as the plus side, and the direction in which the depth of the plow 20 increases, that is, the direction in which the plow 20 descends is defined as the minus side.

  A target plow position is input to the plow position deviation calculation unit 61, and a detection value of the stroke sensor 80 that detects the position of the plow 20 that changes during the tilling operation is input as an actual plow position. The plow position deviation calculation unit 61 calculates a deviation between the input target plow position and the actual plow position, and the calculated deviation is input to the expansion / contraction determination unit 62.

  The expansion / contraction determination unit 62 determines how large the target plow position or the actual plow position is based on the deviation calculated by the plow position deviation calculation unit 61. Then, a drive current is supplied to the expansion side electromagnetic valve 45a or the contraction side electromagnetic valve 45b according to the determination result.

  Specifically, when the actual plow position is lower than the target plow position, that is, when the depth of the plow 20 is deeper than the target, the plow 20 must be raised, so the expansion / contraction determination unit 62 A current is supplied to the extension side electromagnetic valve 45a, and the hydraulic cylinder 40 is extended. On the other hand, when the actual plow position is higher than the target plow position, that is, when the depth of the plow 20 is shallower than the target, the plow 20 must be lowered. An electric current is supplied to the valve 45b, and the hydraulic cylinder 40 is contracted. The current value supplied to each electromagnetic valve 45a, 45b is set by PI control based on the difference between the actual plow position and the target plow position so that the actual plow position converges quickly to the target plow position. It is preferable.

  The target plow position correction unit 63 is calculated by a traction force deviation calculation unit 65 that calculates a traction force deviation that is a difference between the target traction force set by the operator and the actual traction force detected by the load sensor 82, and is calculated by the traction force deviation calculation unit 65. A tractive force deviation calculated by a draft correction calculation unit 66 as a first correction calculation unit that calculates a draft correction amount as a first correction amount for correcting the target plow position based on the calculated tractive force deviation, and a tractive force deviation calculation unit 65 The avoidance correction calculation unit 67 as a second correction calculation unit that calculates an avoidance correction amount as a second correction amount for correcting the target plow position based on And an avoidance correction application determination unit 68 that determines whether or not the situation is present.

  The detection value of the load sensor 82, that is, the actual traction force that the tractor 10 pulls the plow 20 is input to the traction force deviation calculation unit 65, and the operator is operated via the operation lever 72 of the operation panel 70 during draft control described later. The target traction force set by is input. In the traction force deviation calculation unit 65, the traction force deviation is calculated by subtracting the actual traction force from the target traction force, and the calculated absolute value of the traction force deviation is input to the draft correction calculation unit 66 and the avoidance correction application determination unit 68. . The tractive force deviation is a positive value when the target tractive force is larger than the actual tractive force, and a negative value when the target tractive force is smaller than the actual tractive force.

  The draft correction calculation unit 66 receives the tractive force deviation calculated by the tractive force deviation calculation unit 65 and the draft sensitivity as the first sensitivity set by the operator via the draft sensitivity dial 73 of the operation panel 70. Is done. The draft sensitivity is a degree indicating how much the tractive force deviation is reflected when the target plow position is corrected. In the draft correction calculation unit 66, a draft correction amount for correcting the target plow position is calculated based on the magnitude of the traction force deviation and the magnitude of the draft sensitivity.

  Specifically, in the draft correction calculation unit 66, the input draft sensitivity is used as the integral gain Ki and multiplied by the tractive force deviation calculated for each predetermined control step. Then, an integrated value obtained by continuing to add the multiplication value of the tractive force deviation and the integral gain Ki is output as a draft correction amount. The draft correction amount becomes a positive value when the target traction force continues to be larger than the actual traction force, and becomes a negative value when the target traction force continues to be smaller than the actual traction force. The draft sensitivity may be used as the proportional gain Kp. In this case, the product of the tractive force deviation and the proportional gain Kp is the draft correction amount.

  Thus, the draft correction amount calculated by the draft correction calculation unit 66 is output with respect to the target plow position, and the target plow position is subtracted and corrected. For this reason, when the draft correction amount is positive, that is, when the target traction force is larger than the actual traction force, the target plow position is lowered according to the draft correction amount, that is, the plow with respect to the field. The depth of 20 is corrected in the increasing direction. On the other hand, when the draft correction amount is negative, that is, when the actual traction force is greater than the target traction force, the target plow position is increased according to the draft correction amount, that is, the plow 20 for the field. It is corrected in the direction of decreasing the depth of.

  Further, the magnitude of the draft sensitivity input to the draft correction calculation unit 66 can be changed by the operator operating the draft sensitivity dial 73. When the draft sensitivity is increased, the degree of reflection of the tractive force deviation with respect to the correction of the target plow position increases.For example, even when the tractive force deviation is small, the target plow position is greatly corrected, and the actual tractive force becomes the target tractive force. Priority is given to convergence. On the other hand, when the draft sensitivity is reduced, the degree of reflection of the traction force deviation with respect to the correction of the target plow position is reduced. For example, even when the traction force deviation is large, the target plow position is not corrected much, and the actual plow position is reduced. It is prioritized to converge to the target plow position.

  The traction force deviation calculated by the traction force deviation calculation unit 65 is input to the avoidance correction calculation unit 67 via the avoidance correction application determination unit 68 and set by the operator via the avoidance sensitivity dial 74 of the operation panel 70. The avoidance sensitivity as the second sensitivity is input. The avoidance sensitivity is a degree indicating how much the tractive force deviation is reflected when the target plow position is corrected. The avoidance correction calculator 67 calculates an avoidance correction amount for correcting the target plow position based on the magnitude of the traction force deviation and the magnitude of the avoidance sensitivity.

  Specifically, in the avoidance correction calculation unit 67, the input avoidance sensitivity is used as the integral gain Ki and multiplied by the traction force deviation calculated for each predetermined control step. Then, the integrated value obtained by continuing to add the multiplication value of the tractive force deviation and the integral gain Ki is output as the avoidance correction amount. The avoidance sensitivity may be used as the proportional gain Kp. In this case, the multiplication value of the tractive force deviation and the proportional gain Kp is the avoidance correction amount. The calculation in the avoidance correction calculation unit 67 is performed only when it is determined by the avoidance correction application determination unit 68 that the calculation of the avoidance correction amount is to be executed.

  The avoidance correction application determination unit 68 determines whether or not the input absolute value of the traction force deviation is negative, that is, whether or not the actual traction force is greater than the target traction force. Then, the avoidance correction application determination unit 68 outputs the traction force deviation to the avoidance correction calculation unit 67 only when it is determined that the actual traction force is greater than the target traction force, and otherwise, the traction force is output to the avoidance correction calculation unit 67. Does not output deviation. That is, the avoidance correction calculation unit 67 calculates the avoidance correction amount only when the actual traction force exceeds the target traction force due to the plow 20 hitting an obstacle or the like. For this reason, the avoidance correction amount calculated by the avoidance correction calculation unit 67 is always a negative value.

  The avoidance correction amount calculated in this way by the avoidance correction calculating unit 67 is output with respect to the target plow position, and the target plow position is subtracted and corrected. Since the avoidance correction amount is always a negative value, the target plow position is increased in accordance with the size of the avoidance correction amount, that is, the depth of the plow 20 with respect to the field is reduced, and the plow 20 detects an obstacle. It is corrected in the direction to avoid.

  Further, the magnitude of the avoidance sensitivity input to the avoidance correction calculation unit 67 can be changed by the operator operating the avoidance sensitivity dial 74. When the avoidance sensitivity is increased, the degree of reflection of the traction force deviation with respect to the correction of the target plow position is increased. For example, even when the actual traction force slightly exceeds the target traction force, the plow 20 avoids the obstacle at the target plow position. Will be greatly corrected in the direction. When the avoidance sensitivity is reduced, the degree of reflection of the traction force deviation with respect to the correction of the target plow position is reduced. For example, even when the actual traction force greatly exceeds the target traction force, the plow 20 avoids the obstacle at the target plow position. There will be little correction in the direction.

  The target plow position correction unit 63 further includes an avoidance correction initialization determination unit 69 as a second correction amount initialization determination unit that determines whether or not to initialize the avoidance correction amount calculated by the avoidance correction calculation unit 67. .

  The detection value of the load sensor 82, that is, the actual traction force that the tractor 10 pulls the plow 20 is input to the avoidance correction initialization determination unit 69 and is set by the operator via the allowable traction force dial 75 of the operation panel 70. The permissible traction force is input. The avoidance correction initialization determination unit 69 compares the input actual traction force with the allowable traction force, and when the actual traction force is smaller than the allowable traction force, the avoidance correction calculation unit 67 calculates the avoidance correction amount as an initial value. The initialization signal to be converted is output to the avoidance correction calculation unit 67.

  When the initialization signal is input to the avoidance correction calculation unit 67, the avoidance correction calculation unit 67 resets the avoidance correction amount, which is an integrated value obtained by integrating the multiplication value of the traction force deviation and the integral gain Ki, to zero. That is, as long as the actual traction force does not exceed the allowable traction force, the avoidance correction amount is continuously reset, and the avoidance correction calculation unit 67 does not substantially calculate the avoidance correction amount. In this way, the avoidance correction initialization determination unit 69 functions so that the target plow position is corrected by the avoidance correction amount only when the actual traction force rises to some extent and exceeds the allowable traction force. When the initialization signal is input to the avoidance correction calculation unit 67, instead of resetting the avoidance correction amount, the avoidance sensitivity that is the integral gain Ki is zero while the initialization signal is input. You may do it.

  The magnitude of the allowable traction force input to the avoidance correction initialization determination unit 69 can be changed by the operator operating the allowable traction force dial 75. When the allowable traction force is set to be large, the target plow position is difficult to be corrected in a direction in which the plow 20 avoids the obstacle. For this reason, when there are many obstacles such as stones in the field, and it is desired to avoid that the plow 20 frequently rises by avoiding stones and the plowing depth becomes shallow, the allowable traction force is set to be large. On the other hand, when the allowable traction force is set to a small value, the target plow position is easily corrected in a direction in which the plow 20 avoids an obstacle. For this reason, when there are few obstacles, such as a stone, in an agricultural field, and it wants to avoid that a tilling work is inhibited by obstacles, such as a stone which exists occasionally, permissible tractive force is set small.

  Next, the control executed by the controller 60 will be described with reference to FIG.

  First, position control for controlling the depth of the plow 20 with respect to the farm field to be the target depth will be described.

  The position control is executed when the draft sensitivity dial 73 and the avoidance sensitivity dial 74 are operated to the off position. When the draft sensitivity dial 73 and the avoidance sensitivity dial 74 are in the off position and the draft sensitivity and the avoidance sensitivity are not input to the controller 60, the draft correction amount and the avoidance correction amount are not calculated in the target plow position correction unit 63. Therefore, the target plow position is input to the plow position deviation calculation unit 61 without being corrected. In addition, a control mode changeover switch (not shown) may be provided, and the position control and draft control described later may be changed over by switching the control mode changeover switch.

  Therefore, in the position control, the position of the plow 20 relative to the vehicle body of the tractor 10 set by the operator operating the operation lever 72 of the operation panel 70 is maintained regardless of the magnitude of the traction force with which the tractor 10 pulls the plow 20. Is done.

  Specifically, first, the target plow position is set according to the operation position of the operation lever 72 by the operator. The relationship between the operation position of the operation lever 72 and the target plow position is stored in the controller 60 in advance. Thus, in the position control, the target plow position is determined based on the operation of the operation lever 72 by the operator. Simultaneously with the setting of the target plow position, the actual plow position is detected by the stroke sensor 80. The target plow position and the actual plow position are input to the plow position deviation calculation unit 61 in the controller 60.

  The plow position deviation calculation unit 61 calculates a deviation between the input target plow position and the actual plow position, and the calculated deviation is input to the expansion / contraction determination unit 62. The expansion / contraction determining unit 62 determines how large the target plow position or the actual plow position is based on the deviation calculated by the plow position deviation calculating unit 61, and the expansion side solenoid valve is determined according to the determination result. A drive current is supplied to 45a or the contraction-side electromagnetic valve 45b.

  When the actual plow position is lower than the target plow position, that is, when the depth of the plow 20 with respect to the field is deeper than the target, the plow 20 must be raised, so the expansion / contraction determination unit 62 Then, an electric current is supplied to the extension side electromagnetic valve 45a, and the hydraulic cylinder 40 is extended. As the hydraulic cylinder 40 extends, the plow 20 moves upward via the three-point hitch mechanism 30 and approaches the target plow position.

  On the other hand, when the actual plow position is higher than the target plow position, that is, when the depth of the plow 20 with respect to the field is shallower than the target, the plow 20 must be lowered. 62 supplies a current to the contraction-side electromagnetic valve 45b to contract the hydraulic cylinder 40. As the hydraulic cylinder 40 contracts, the plow 20 moves downward via the three-point hitch mechanism 30 and approaches the target plow position.

  The position of the plow 20 that changes by changing the amount of expansion / contraction of the hydraulic cylinder 40 is always detected by the stroke sensor 80, and is input to the plow position deviation calculation unit 61 as the actual plow position. In this way, in the position control, the controller 60 feedback-controls the expansion / contraction amount of the hydraulic cylinder 40 based on the detected actual plow position so that the position of the plow 20 converges to a predetermined target position.

  Next, draft control for changing the target position of the plow 20 so that the traction force with which the tractor 10 pulls the plow 20 converges to the target traction force during the tilling work will be described.

  In the above-described position control, the position of the plow 20 relative to the tractor 10 is controlled to be constant regardless of the magnitude of the traction force with which the tractor 10 pulls the plow 20. Since the plow 20 is structurally pulled deeply into the field by being pulled, the plow 20 is plowed at a certain depth by keeping the position of the plow 20 relative to the tractor 10 by position control. Is possible. However, the field does not always have the same hardness even if the depth is the same. If the position of the plow 20 with respect to the tractor 10 is forced to be kept constant, according to the change in the field hardness. The tillage resistance may change, and the vehicle speed of the tractor 10 that pulls the plow 20 may vary greatly.

  On the other hand, in the draft control, when the traction force that the tractor 10 pulls the plow 20 becomes larger than the target traction force, the target depth of the plow 20 is reduced, and when the traction force becomes smaller than the target traction force, the target of the plow 20 is reduced. By increasing the depth, the traction force is converged to the target traction force. As a result, the tilling depth is maintained within a certain range, and stable tilling work can be performed without the vehicle speed of the tractor 10 changing.

  The draft control is executed by operating the draft sensitivity dial 73 to a position other than OFF when the plow 20 is in the plowing state by the position control. By switching from position control to draft control, the target plow position is changed to the actual plow position detected by the stroke sensor 80 when switching to draft control. Further, the target traction force can be set by the operation lever 72 by switching from the position control to the draft control. Note that the position control may be switched to the draft control by switching a control mode switch (not shown). In addition to the operation lever 72, a lever or the like for setting a target traction force may be provided.

  In this way, when the draft sensitivity dial 73 is at a position other than OFF and the draft sensitivity is input to the controller 60, the target plow position correction unit 63 calculates the draft correction amount. For this reason, the target plow position is corrected according to the draft correction amount and then input to the plow position deviation calculation unit 61. That is, in the draft control, the target plow position changes according to the change in the traction force that the tractor 10 pulls the plow 20.

  Specifically, the traction force with which the tractor 10 pulls the plow 20 is detected by the load sensor 82, and the detected value is input to the traction force deviation calculation unit 65 of the controller 60 as the actual traction force. In the traction force deviation calculation unit 65, the traction force deviation is calculated by subtracting the actual traction force detected by the load sensor 82 from the target traction force set by the operation lever 72. The absolute value of the calculated traction force deviation is a draft correction calculation. Input to the unit 66. Then, the draft correction calculation unit 66 calculates the draft correction amount based on the magnitude of the traction force deviation and the draft sensitivity set by the draft sensitivity dial 73, and the target plow position is corrected by the calculated draft correction amount. The

  If the target traction force is greater than the actual traction force and the draft correction amount is a positive value, the draft correction amount is subtracted from the target plow position, and the corrected target plow position depends on the draft correction amount. Become lower. That is, since there is still a margin before the actual traction force becomes the target traction force, the target plow position is corrected in the direction in which the depth of the plow 20 with respect to the field is increased, that is, in the direction in which the tillage resistance is increased. On the other hand, when the actual traction force is greater than the target traction force and the draft correction amount is a negative value, the draft correction amount is added to the target plow position, and the corrected target plow position is the magnitude of the draft correction amount. It becomes high according to. That is, since the actual traction force exceeds the target traction force, the target plow position is corrected in the direction in which the depth of the plow 20 with respect to the field is reduced, that is, in the direction in which the tillage resistance is reduced.

  In addition, when the draft sensitivity is increased by the operator, the degree of reflection of the traction force deviation with respect to the correction of the target plow position increases, so that the actual traction force easily converges to the target traction force and is cultivated according to changes in the field hardness. The depth is also variable. On the other hand, when the draft sensitivity is reduced by the operator, the degree of reflection of the traction force deviation with respect to the correction of the target plow position is reduced, so that the actual plow position easily converges to the target plow position and reacts to changes in field hardness. The plowing depth becomes almost constant. For this reason, the operator sets the draft sensitivity to be higher if the field is soft and the change in tillage resistance is small, and sets the draft sensitivity to be lower if the field is hard and the change in tillage resistance is large. To do. As a result, it becomes possible to plow at a certain depth regardless of the hardness of the field.

  The target plow position corrected in the draft control is input to the plow position deviation calculator 61, and the plow position deviation calculator 61 calculates the deviation between the actual plow position and the corrected target plow position. Since the subsequent control is the same as the position control, the description is omitted.

  Thus, in the draft control, the expansion / contraction amount of the hydraulic cylinder 40 is feedback-controlled so that the actual traction force converges to the target traction force.

  Next, the obstacle avoidance control for avoiding the plow 20 colliding with the obstacle will be described.

  In the draft control described above, the target depth of the plow 20 is changed in accordance with the change in the traction force with which the tractor 10 pulls the plow 20. However, there may be obstacles such as stones that are not crushed by the plow 20 in the field. When the plow 20 approaches such an obstacle, if the plow 20 is not raised immediately, the plow 20 may hit the obstacle and the plow 20 may be damaged or the tractor 10 may stop suddenly. In particular, when the field is hard and the draft sensitivity is set to be low, the target depth of the plow 20 changes slowly, so that the plow 20 tends to hit an obstacle.

  Therefore, in the obstacle avoidance control, when the actual traction force increases as the plow 20 approaches the obstacle, the plow 20 collides with the obstacle by correcting the target depth of the plow 20 in the direction of decreasing the depth. As a result, the tractor 10 is prevented from suddenly stopping.

  The obstacle avoidance control is executed when the avoidance sensitivity dial 74 is operated to a position other than OFF in the state where the above-described draft control is being executed. In a state where the avoidance sensitivity dial 74 is at a position other than OFF and the avoidance sensitivity is input to the controller 60, the target plow position correction unit 63 calculates an avoidance correction amount in addition to the draft correction amount. For this reason, the target plow position is corrected according to the draft correction amount and the avoidance correction amount and then input to the plow position deviation calculation unit 61.

  That is, in the obstacle avoidance control, when the traction force with which the tractor 10 pulls the plow 20 becomes larger than the target traction force, the target plow position is changed upward, that is, the depth of the plow 20 with respect to the field is decreased. Can easily avoid obstacles.

  Specifically, first, it is determined whether or not the absolute value of the traction force deviation calculated by the traction force deviation calculation unit 65 is negative, that is, whether or not the actual traction force is larger than the target traction force. It is determined by. When the avoidance correction application determination unit 68 determines that the actual traction force is larger than the target traction force, the avoidance correction calculation unit 67 determines the traction force deviation and the avoidance sensitivity dial 74 based on the avoidance sensitivity dial 74. Thus, the avoidance correction amount is calculated, and the target plow position is corrected by the calculated avoidance correction amount.

  Since the avoidance correction amount calculated by the avoidance correction calculation unit 67 is always a negative value, the avoidance correction amount is added to the target plow position, and the corrected target plow position is set to the size of the avoidance correction amount. Increases accordingly. Further, since the draft correction amount is added to the target plow position in addition to the avoidance correction amount, the target plow position is further corrected in a direction to avoid the obstacle.

  Thus, in a state where the actual traction force exceeds the target traction force and the plow 20 may collide with the obstacle, the target plow position is a direction in which the depth of the plow 20 relative to the field is reduced, that is, the obstacle is avoided. Since the direction is corrected, it is possible to reliably avoid the plow 20 from colliding with an obstacle. Further, since the obstacle avoidance control is performed using the load sensor 82 that is also used for draft control, it is not necessary to separately provide sensors for detecting the slip of the tractor 10. For this reason, the raise of the manufacturing cost of the working machine raising / lowering control apparatus 100 can be suppressed.

  Further, depending on the state of the field, even if there are many obstacles such as stones, there is no need to raise the plow 20 and avoid them as long as it is crushed by the plow 20. That is, every time the actual traction force becomes higher than the target traction force, if the target plow position is corrected in the direction in which the depth of the plow 20 with respect to the field becomes shallower by the avoidance correction amount, the tilling work with a sufficient depth becomes stable. May not be done.

  Therefore, in the obstacle avoidance control, when the allowable traction force is set by the allowable traction force dial 75, the avoidance correction amount for correcting the target plow position in the avoidance correction calculation unit 67 until the actual traction force exceeds the allowable traction force. The operation of is not executed.

  Specifically, when the actual traction force is smaller than the allowable traction force set by the operator via the allowable traction force dial 75, the avoidance correction initialization determination unit 69 sends an initialization signal to the avoidance correction calculation unit 67. Output. When the initialization signal is input to the avoidance correction calculator 67, the avoidance correction calculator 67 resets the avoidance correction amount to zero. That is, unless the actual traction force exceeds the allowable traction force, the avoidance correction calculation unit 67 is in a state where the avoidance correction amount is not substantially calculated.

  Thus, only when the actual traction force rises to some extent and exceeds the allowable traction force, the avoidance correction amount is calculated by the avoidance correction calculation unit 67, so that the plow 20 is not rapidly increased unnecessarily. Only when there is a possibility of colliding with an obstacle, the plow 20 can be rapidly raised. The allowable traction force is empirically set by the operator to be slightly smaller than the traction force when the plow 20 hits an obstacle that is not crushed by the plow 20.

  In the obstacle avoidance control, the corrected target plow position is input to the plow position deviation calculation unit 61, and the plow position deviation calculation unit 61 calculates the deviation between the actual plow position and the corrected target plow position. Since the subsequent control is the same as the position control, the description is omitted.

  Thus, in the obstacle avoidance control, the target plow position is corrected by the avoidance correction amount in addition to the draft correction amount, so that the expansion / contraction amount of the hydraulic cylinder 40 is fed back so as to avoid the collision of the plow 20 with the obstacle. Control.

  It is also possible to stop the draft control and add only the obstacle avoidance control to the position control by setting the avoidance sensitivity dial 74 to a position other than OFF and setting the draft sensitivity dial 73 to the OFF position. is there. In this case, the target plow position is corrected by the avoidance correction amount only when the actual traction force exceeds the target traction force.

  According to the above embodiment, there exist the effects shown below.

  In the work implement lifting control device 100, in a state where the actual traction force is larger than the target traction force and the plow 20 may collide with an obstacle, the target plow position is determined based on the draft correction amount and the avoidance correction amount. Correction is made in a direction in which the depth of 20 becomes shallow, that is, in a direction to avoid an obstacle. Therefore, the plow 20 is prevented from colliding with an obstacle, and the tractor 10 is prevented from suddenly stopping, so that stable tilling work can be performed.

  Further, since the detection value of the load sensor 82 that is also used for the calculation of the draft correction amount is used for the calculation of the avoidance correction amount, control for avoiding the plow 20 from colliding with the obstacle is executed. Therefore, it is not necessary to separately provide sensors for detecting the slip of the tractor 10. For this reason, the raise of the manufacturing cost of the working machine raising / lowering control apparatus 100 can be suppressed.

  Next, a modification of the present embodiment will be described with reference to FIG.

  In the above embodiment, the detection value of the load sensor 82 is input to the avoidance correction initialization determination unit 69 and the allowable traction force set by the operator via the allowable traction force dial 75 of the operation panel 70 is input. Instead, as shown in FIG. 4, the traction force deviation calculated by the traction force deviation calculation unit 65 and the allowable traction force deviation set by the operator via an allowable traction force deviation dial (not shown) are used for avoidance correction initialization determination. The configuration may be such that it is input to the unit 69. In this case, the avoidance correction initialization determination unit 69 compares the input traction force deviation with the allowable traction force deviation. If the traction force deviation is smaller than the allowable traction force deviation, the avoidance correction calculated by the avoidance correction calculation unit 67 is performed. An initialization signal for initializing the amount is output to the avoidance correction calculation unit 67.

  Hereinafter, the configuration, operation, and effect of the embodiment of the present invention will be described together.

  The work implement lifting control device 100 includes a hydraulic cylinder 40 that raises and lowers the plow 20 relative to the tractor 10 by expanding and contracting, a stroke sensor 80 that detects a lift position of the plow 20 relative to the tractor 10, and the tractor 10 pulls the plow 20. A load sensor 82 that detects the traction force to be moved, and a controller 60 that controls expansion and contraction of the hydraulic cylinder 40 based on a lift position deviation that is a difference between a preset target plow position and a detection value of the stroke sensor 80. 60 has a target plow position correction unit 63 that corrects a target plow position based on a traction force deviation that is a difference between a preset target traction force and a detection value of the load sensor 82. The target plow position correction unit 63 includes: Pre-set draft sensitivity, which is the degree to which the tractive force deviation is reflected in the correction of the target plow position In addition to the draft correction calculation unit 66 for calculating the draft correction amount for correcting the target plow position based on the traction force deviation and the draft correction amount, the traction force only when the detected value of the load sensor 82 is larger than the target traction force. An avoidance correction calculating unit 67 for calculating an avoidance correction amount for correcting the target plow position based on a preset avoidance sensitivity, which is a degree to which the deviation is reflected in the correction of the target plow position, and the traction force deviation.

  In this configuration, when the actual traction force is larger than the target traction force and the plow 20 may collide with an obstacle, the target plow position is determined by the draft correction amount and the avoidance correction amount, and the depth of the plow 20 with respect to the field. Is corrected in the direction of shallowing, that is, in the direction of avoiding obstacles. Therefore, the plow 20 is prevented from colliding with an obstacle, and the tractor 10 is prevented from suddenly stopping, so that stable tilling work can be performed. Further, since the detection value of the load sensor 82 that is also used for the calculation of the draft correction amount is used for the calculation of the avoidance correction amount, control for avoiding the plow 20 from colliding with the obstacle is executed. Therefore, it is not necessary to separately provide sensors for detecting the slip of the tractor 10. For this reason, the raise of the manufacturing cost of the working machine raising / lowering control apparatus 100 can be suppressed.

  The target plow position correction unit 63 further includes an avoidance correction initialization determination unit 69 that determines whether or not to initialize the avoidance correction amount. The avoidance correction initialization determination unit 69 detects the detection value of the load sensor 82. Is smaller than the preset allowable traction force, or when the traction force deviation is smaller than the preset allowable traction force deviation, the avoidance correction amount is initialized.

  In this configuration, only when the actual traction force exceeds the allowable traction force, the avoidance correction calculation unit 67 calculates the avoidance correction amount and corrects the target plow position. For this reason, it becomes possible to raise the plow 20 rapidly only when the plow 20 may collide with an obstacle, and the plow 20 is not raised unnecessarily. As a result, stable tillage work can be performed.

  The magnitudes of the draft sensitivity and the avoidance sensitivity can be changed by the operator.

  In this configuration, the operator can arbitrarily change the draft sensitivity and the avoidance sensitivity. For this reason, by changing the draft sensitivity and avoidance sensitivity according to the field conditions, it is possible to freely control how much of position control, draft control, and obstacle avoidance control is executed. Can be set to As a result, the stability of tillage work can be improved.

  As mentioned above, although embodiment of this invention was described, the said embodiment showed only a part of application example of this invention, and the meaning which limits the technical scope of this invention to the specific structure of the said embodiment. Absent.

  For example, in the above embodiment, a hydraulic cylinder is used as the actuator, but the present invention is not limited to this, and the actuator may be an electric actuator.

  DESCRIPTION OF SYMBOLS 100 ... Work implement raising / lowering control apparatus, 10 ... Tractor (work vehicle), 20 ... Plow (work machine), 30 ... Three-point hitch mechanism, 40 ... Hydraulic cylinder (actuator), 50 ... Engine, 60 ... Controller (control unit), 70 ... Operation panel, 80 ... Stroke sensor (lift position detector), 82 ... Load sensor (traction force detector)

Claims (3)

A working machine lifting control device that controls lifting of a working machine that is connected to a work vehicle so as to be movable up and down,
An actuator for elevating and lowering the work implement with respect to the work vehicle by extending and contracting;
A lift position detector for detecting a lift position of the work implement with respect to the work vehicle;
A traction force detector for detecting a traction force with which the work vehicle pulls the work implement;
A control unit that controls expansion and contraction of the actuator based on a lift position deviation that is a difference between a preset target lift position and a detection value of the lift position detector;
The control unit includes a target lifting position correction unit that corrects the target lifting position based on a traction force deviation that is a difference between a preset target traction force and a detection value of the traction force detector,
The target lifting position correction unit is
A first correction for calculating a first correction amount for correcting the target lift position based on the first sensitivity set in advance, which is the degree to which the tractive force deviation is reflected in the correction of the target lift position, and the tractive force deviation. An arithmetic unit;
Apart from the first correction amount, a preset second sensitivity that is a degree to reflect the traction force deviation in the correction of the target lift position only when the detection value of the traction force detector is larger than the target traction force. And a second correction calculator that calculates a second correction amount for correcting the target lift position based on the traction force deviation. The target lift position correction unit further includes a second correction amount initialization determination unit that determines whether or not to initialize the second correction amount,
When the detected value of the traction force detector is smaller than a preset allowable traction force, or when the traction force deviation is smaller than a preset allowable traction force deviation, the second correction amount initialization determination unit The work implement lifting control device according to claim 1, wherein the second correction amount is initialized.   The work implement lifting control device according to claim 1, wherein the first sensitivity and the second sensitivity can be changed by an operator.

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