JP2006320251A - Plowing depth-controlling mechanism of tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controlling means performing a plowing depth control by mounting a rotary plowing unit at the rear part of a tractor and utilizing a rear cover equipped at the rear part of a rotary plowing device as a plowing depth sensor, capable of performing at least predictable plowing depth work even at a time of having an abnormality of the plowing depth sensor, and improving the accuracy of the plowing depth even in normal time. <P>SOLUTION: This tractor having a rear cover sensor 34 for detecting the unevenness of the ground surface, a plowing depth-setting dial for setting a target value of the plowing depth, a traveling speed sensor 37 for detecting the vehicle velocity, a plowing unit 13 and a controller 32 for controlling a lifting up and down mechanism so as to become the target depth set by the plowing depth-setting means by feeding back the output of the detector is provided by making the lifting up and down of a lift arm which is the plowing unit, as having narrow insensitive zone having a fixed width in the ≤A set speed of the vehicle speed, having a wide insensitive zone having a fixed width in ≥B set speed and between the set speed A and set speed B, changeable in accordance with the vehicle speed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to height control of a work machine mounted on the rear portion of a tractor, and in particular, mounts a rotary tiller device on the tractor, and uses a rear cover provided at the rear portion of the rotary tiller device as a tiller sensor to perform tiller depth control. It is related with the technique of the control means to perform.

Conventionally, a rotary tiller is installed at the rear of the tractor via an elevating mechanism, and the rear cover is pivotally supported at the rear of the tiller cover so that it can be pivoted up and down. The angle of the rear cover is detected by a sensor such as an angle sensor. The plowing depth control of the elevating mechanism that feeds back the output of No. 1 and achieves the set depth set by the plowing depth setting means is well known.
Here, while comparing the raising / lowering position of the ground working machine, that is, the plowing depth instructed by the setting unit such as the plowing depth lever of the control unit, with the current working depth of the rotary that is the ground working machine, the setter In the process of automatically following the tilling depth instructed at, when the traveling speed of the tractor increases, the delay in response to the follow command increases, and the sensing unit that senses the tilling depth is slightly on the ground surface. There is a problem that cultivating depth is vibrated and causes hunting due to excessive perception of excessive irregularities. Therefore, in Patent Document 1, with respect to the above-described tilling depth control, a delay in response operation and hunting are improved by providing a dead zone proportional to the height of the vehicle speed.
JP 56-75003 A

However, if the dead zone is changed simply in proportion to the traveling speed as in the above-mentioned Patent Document 1, when the speed sensor is abnormal, the tilling control does not function and the rotary tiller may move unpredictably. For example, when the value of the speed sensor suddenly becomes a small value due to noise or the like, the dead zone is also reduced, and a sudden elevation may be performed. Also, at the start of work where the vehicle speed is very low or when slipping occurs, applying the dead zone proportional to the vehicle side to the tilling depth control as it is will reduce the dead zone so that rapid lifting control will be performed instead. Accuracy may deteriorate.
Here, the problem to be solved is that in the control means for mounting the rotary tiller at the rear part of the tractor and using the rear cover provided at the rear part of the rotary tiller as the tiller sensor, the vehicle speed sensor Even when an abnormally large value or an abnormally small value is output, at least normal plowing work is possible, and the accuracy of tillage is improved.

  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, a sensor for detecting a tilling depth, a means for setting a tilling target value, a sensor for detecting a vehicle speed, and an actuator for raising and lowering a work implement are connected to a controller, In the tractor having a control device that controls the target depth set by the setting means, the dead zone for the working depth target value is a predetermined narrow constant width when the vehicle speed during work is less than the set speed A on the low speed side, A predetermined wide constant width is set at a speed higher than the set speed C on the high speed side, and is increased in proportion to the increase in the vehicle speed between the set speed A and the set speed C.

  According to a second aspect of the present invention, in the plowing depth control mechanism according to the first aspect, when the vehicle speed is less than the set speed A and the set speed C or more, the control gain of the actuator that raises and lowers the work implement is a constant value, and the set speed A The gain is increased in proportion to the increase in the vehicle speed at the set speed A less than the set speed B set between the set speed C and the set speed C, and the gain is decreased in proportion to the increase in the vehicle speed at the set speed B and less than the set speed C. Is.

  In claim 3, in the tilling depth control mechanism according to claim 1, when the vehicle speed is less than the set speed A and the set speed C or more, the upper limit value of the control gain of the actuator that raises and lowers the work implement is a constant value. When set speed A is less than set speed B set between set speed A and set speed C, the upper limit of the gain is increased in proportion to the increase in vehicle speed, and when set speed B is less than set speed C and is less than set speed C, it is proportional to the increase in vehicle speed. Thus, the upper limit value of the gain is reduced.

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

  According to the first aspect of the present invention, in the plowing depth control, even when the sensor for detecting the vehicle speed is abnormal, the control can be performed in the dead zone of the set value A or B. That is, plowing depth control that can be predicted even when the sensor for detecting the vehicle speed is abnormal is possible. Further, when the vehicle speed is very high or conversely very low, the plowing depth control is performed in a fixed dead zone, so that the accuracy is improved.

  In the second aspect, in addition to the effect of the first aspect, the control can be performed with the gain of the set value A or B even when the sensor for detecting the vehicle speed is abnormal. That is, plowing depth control that can be predicted even when the sensor for detecting the vehicle speed is abnormal is possible. In addition, when the vehicle speed is very high or conversely very low, the plowing depth control is performed with a constant gain, so that the accuracy is improved.

  In claim 3, in the tilling depth control mechanism according to claim 2, when the optimum gain obtained experimentally in all speed ranges is not known, only the upper limit value of the gain is set. 2 is obtained.

Next, embodiments of the invention will be described.
1 is a side view of a tractor equipped with a rotary tiller according to an embodiment of the present invention, FIG. 2 is a control block diagram of tilling depth control according to an embodiment of the present invention, and FIG. 3 is a control block circuit diagram, FIG. 4 is a diagram showing the relationship between the vehicle speed and the dead zone of the tilling depth control according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating the relationship between the vehicle speed and the gain of the tilling depth control according to the second embodiment of the present invention, and FIG. 6 illustrates the relationship between the vehicle speed and the gain upper limit value of the tilling depth control according to the third embodiment of the present invention. FIG.

<Tractor working machine>
Here, a tractor working machine equipped with a rotary tiller as an embodiment of the present invention will be described with reference to FIG.
In FIG. 1, a tractor 1 supports a front wheel 2 at a front portion and a rear wheel 3 at a rear portion, houses an engine 5 in a bonnet 4 on an engine frame, and a steering handle 6 on a dashboard 25 at a rear portion of the bonnet 4. The hydraulic case 8 is placed on the rear transmission case 9 of the steering handle 6, and the seat 7 is arranged above the hydraulic case 8. A main transmission lever 12, a position lever 10, a tilling depth setting dial 31 serving as a tilling depth setting means, and the like are disposed on the side portion of the seat 7.

  A rotary tiller 13 is mounted behind the mission case 9 via a work implement mounting device 11. The work implement mounting device 11 includes a top link 15 pivotally connected to a top link bracket attached to the rear surface of the mission case 9, and lower links 16 and 16 pivoted on both sides of the mission case 9 or the rear accelerator housing. Thus, lower ends of lift rods 17 and 17 pivoted to lift arms 14 and 14 projecting rearward from the hydraulic case 8 are pivotally connected to the front and rear middle portions of the lower links 16 and 16, respectively. The rotary tiller 13 is connected to the rear part of the lower links 16, 16, and the rotary tiller 13 can be moved up and down by rotating the lift arm 14. Note that one of the left and right lift rods 17 is constituted by a hydraulic cylinder, and the inclination of the work implement can be controlled by operating the hydraulic cylinder.

  The rotary tiller 13 transmits power to the gear case of the rotary tiller 13 via a universal joint or the like from the PTO shaft protruding rearward from the rear surface of the transmission case 9, and the transmission shaft in the main beam is transmitted from the gear case. Via the chain transmission mechanism of the chain case 19 arranged on the side, the power is transmitted to the tilling claw shaft laid horizontally between the lower part of the chain case 19 and the lower side plate on the opposite side, and fixed to the tilling claw shaft. The tilled claws 20, 20,... Can be rotated. Further, a tillage cover 30 is provided so as to cover the upper and upper rear of the rotation trajectory of the tip of the tilling claws 20, 20..., And the front end of the rear cover 22 is pivotally supported at the rear end of the tillage cover 30. Yes. Although not shown, the rotation of the rear cover 22 is transmitted via a link mechanism to a rear cover sensor 34 as a tilling depth detecting means including a potentiometer disposed at the rear of the tractor.

<Feedback depth control>
Next, feedback plowing depth control in the case where a tractor equipped with the above-described rotary plowing device performs plowing work will be described with reference to the block diagram of FIG. In FIG. 2, the signal is transmitted in the direction of the arrow, and the signal represents a positive coupling with + and a negative coupling with − at the junction indicated by “◯”.
Here, from the right side of the figure, the rotation angle of the rear cover 22 that is the current plowing position is detected by the rear cover sensor 34 and fed back to the controller 32 as the rear cover sensor value 36. Further, the control amount (gain) is calculated by the controller 32 from the deviation obtained by comparing and calculating the rear cover sensor value 36 and the tilling depth target value (set value) 33 set by the tilling depth setting dial 31 on the left side in the figure. Tilling work is performed by moving the lift arm 14 up and down by actuating the electromagnetic with a controlled amount. Here, the traveling speed value 38 is input to the controller 32 by the traveling speed detection sensor 37 that detects the traveling speed of the tractor. The role of the controller 32 at this time will be described in detail in each embodiment.

Next, Example 1 according to the present invention will be described with reference to FIG.
FIG. 3 shows the relationship between the traveling speed of the tractor 1 and the size of the dead zone for the tilling depth control. The dead zone means uncertainty regarding the behavior of the electromagnetic valve 23 that switches the supply of the pressure oil to the hydraulic cylinder that drives the tillage device 13 that actually performs the tillage operation. That is, in this embodiment, it is the detection sensitivity of the rear cover, and is regarded as the fluctuation width of the detection height with respect to the target value (set value). Therefore, if the width of the dead zone is large, it becomes insensitive, and even if the height differs greatly from the target value, the lift arm 14 is not actuated by the hydraulic cylinder. Even if the height is deviated, the hydraulic cylinder is driven so as to approach the target value.
A speed setting unit 24 for setting the setting speeds of A, B, and C described later is connected to the controller 32.

Here, the control which changes the dead zone width | variety of the above-mentioned tilling depth control according to the running speed of the tractor 1 shown in FIG. 4 and the following is demonstrated. The controller 32 operates the electromagnetic valve under the following conditions.
(1) If the speed is less than the set speed A, the dead zone width of the tilling depth control is constant at Z1.
(2) When the speed is higher than the set speed A and lower than the set speed B, the dead zone width of the tilling depth control is set to a value proportional to between Z1 and Z2.
(3) When the speed is equal to or higher than the set speed C, the dead zone width of the tilling depth control is constant at Z2.
However, the speed is A <C, the speed A is in the vicinity of the minimum value of the work speed, the speed C is in the vicinity of the maximum value of the work speed, and can be set by the speed setter 24. The dead zone is Z1 <Z2.

Specifically, the tilling depth control in the first embodiment detects the traveling speed by the traveling speed detection sensor 37, and in the low speed range where the detected value is the traveling speed up to A, the size of the dead zone is always a small value as Z1. As a result, the electromagnetic valve 23 is actuated when it is slightly separated from the plowing depth target value (set value) 33, and the elevation control is performed so that the target value is reached. Therefore, at the start of work or when the load becomes extremely low due to an increase in load or when the traveling speed is A or more and the traveling speed detection sensor 37 becomes an abnormally small value due to noise or the like. However, the work equipment does not move up and down sensitively, and the finish can be cleaned.
When the traveling speed is greater than or equal to A and less than the set speed C, the dead zone increases in proportion to the increase in traveling speed, and normal tilling control is performed.
When the traveling speed is equal to or higher than the set speed C, the size of the dead zone is Z2. Therefore, even when the traveling speed detection sensor 37 detects an abnormally fast value due to noise or the like, the dead zone width does not exceed Z2, and the dead zone becomes abnormally large during high-speed work, and there is a portion where the tilling depth control is not performed. Absent. In addition, since the work speed is too high, the dead zone becomes large and control delay does not occur.

Next, Example 2 according to the present invention will be described with reference to FIG.
FIG. 5 shows the relationship between the traveling speed of the tractor 1 and the magnitude of the tilling depth control gain. Here, the gain indicates that the pressure oil is applied to the hydraulic cylinder that is driven to move up and down of the tilling device 13 that actually performs the tilling work. This is a control input value from the controller to the electromagnetic valve 23 that switches oil feeding, and means the speed at which the lift arm 14 is rotated.

Compared with the tilling depth target value (setting value) 33 and the actual rear cover sensor value 36, the gain is increased so that the target value is faster as the difference is larger, and more hydraulic oil is supplied to the hydraulic cylinder. Refueling so that it operates quickly. However, if the lift arm 14 is moved quickly, the inertial force also increases, and the reaction of the tractor 1 that stops when reaching the target value also increases. Here, as shown in FIG. 4 and below, the gain of the above-mentioned tilling depth control according to the traveling speed of the tractor 1 is changed.
(1) If the speed is less than the set speed A, the working depth control gain is constant at G1.
(2) When the speed is greater than or equal to the set speed A and less than the set speed B, the gain of the tilling depth control is set to a value that increases between the gain values G1 and G2 in proportion to the increase in the traveling speed. When the speed is greater than or equal to the set speed B and less than the set speed C, the gain of the tilling depth control is set to a value that decreases between the gain values G2 and G3 in proportion to the increase in the traveling speed.
(3) When the speed is higher than the set speed C, the working depth control gain is constant at G3.
However, the speed is A <B <C, and the gain value is G3 <G1 <G2.

  In other words, in the second embodiment, the gain is G1, and the hydraulic cylinder is expanded and contracted at a speed corresponding to G1 when the traveling speed is lower than A. At a low working speed that is not less than the set speed A and less than the set speed B, the gain of the tilling depth control is increased in proportion to the increase in the traveling speed, and the hydraulic cylinder moves faster as the speed increases. In a high-speed working area that is greater than or equal to the set speed B and less than the set speed C, the working pressure is gradually decreased by decreasing the working depth control gain in proportion to the increase in traveling speed, Prevents the machine from moving up and down quickly. At a speed exceeding the set speed C or higher, the gain is decreased and the hydraulic cylinder is operated slowly. Thus, even if the traveling speed detection sensor 37 detects an abnormally high value or a low value, the gain values G1 and G3 output a low gain to prevent damage due to rapid expansion and contraction of the hydraulic cylinder.

Next, Embodiment 3 according to the present invention will be described with reference to FIG.
FIG. 3 shows the relationship between the traveling speed of the tractor 1 and the gain upper limit value of the tilling depth control.
Here, as shown in FIG. 6 and below, the above-mentioned tilling depth control gain upper limit value is changed according to the traveling speed of the tractor 1.
(1) If the speed is lower than the set speed A, the gain upper limit value of the tilling depth control is made constant at U1.
(2) When the speed is higher than the set speed A and lower than the set speed B, the gain upper limit value of the tilling control is increased in proportion to the increase in the traveling speed. When the speed is higher than the set speed B and lower than the set speed C, the gain upper limit value of the tilling depth control is decreased in proportion to the increase in the traveling speed.
(3) At the set speed C or higher, the gain upper limit value of the tilling depth control is made constant at U3.
However, the gain upper limit value is U3 <U1 <U2.

  That is, in Example 3, the gain is increased so that the target value becomes faster as the difference between the working depth target value (set value) 33 and the actual rear cover sensor value 36 increases. A large amount of pressure oil is supplied to the cylinder so as to operate quickly, but the upper limit of the gain is set by the traveling speed. In other words, the upper limit value of the gain is U1 for low-speed traveling where the traveling speed is less than A. At a low work speed that is equal to or higher than the set speed A and lower than the set speed B, the upper limit value of the working depth control gain is increased in proportion to the increase in the traveling speed. In a high-speed working area that is equal to or higher than the set speed B and lower than the set speed C, the upper limit value of the tillage control gain is decreased in proportion to the increase in the traveling speed. The gain upper limit value is set to a small value of U3 at a speed exceeding the set speed C or higher work area. Thus, even if the traveling speed detection sensor 37 detects an abnormally high value or a low value, the gain values G1 and G3 output a low gain to prevent damage due to rapid expansion and contraction of the hydraulic cylinder. In contrast to the second embodiment, when the optimum gain experimentally obtained in all speed ranges is not known, the same effect as the second embodiment can be obtained by setting only the upper limit value of the gain.

A side view of a tractor equipped with a rotary tiller concerning an embodiment of the present invention. The control block diagram of the tilling depth control which concerns on embodiment of this invention. The control block circuit diagram similarly. The figure showing the relationship between the vehicle speed and dead zone of the tilling depth control which concern on Example 1 of this invention. The figure showing the relationship between the vehicle speed of the plowing depth control which concerns on Example 2 of this invention, and a gain. The figure showing the relationship between the vehicle speed of the tilling depth control which concerns on Example 3 of this invention, and a gain upper limit.

Explanation of symbols

1 Tractor 13 Tillage Device 14 Lift Arm 22 Rear Cover 32 Controller 34 Rear Cover Sensor

Claims (3)

A sensor for detecting the working depth, a means for setting the working depth target value, a sensor for detecting the vehicle speed, and an actuator for moving the work implement up and down are connected to the controller, and the target depth set by the working depth setting means In a tractor having a control device to control
The dead zone for the working depth target value is set to a predetermined narrow constant width when the vehicle speed at the time of operation is less than the set speed A on the low speed side, set to a predetermined wide constant width above the set speed C on the high speed side, and set to the set speed A or higher. A plowing depth control mechanism for a tractor working machine characterized in that it becomes wider in proportion to the increase in the vehicle speed when the speed is lower than C. In the plowing depth control mechanism according to claim 1,
When the vehicle speed is less than the set speed A and greater than or equal to the set speed C, the control gain of the actuator for raising and lowering the work implement is a constant value, and the set speed A is less than the set speed B set between the set speed A and the set speed C. In the tractor working depth control mechanism, the gain is increased in proportion to the increase in the vehicle speed, and the gain is decreased in proportion to the increase in the vehicle speed when the speed is higher than the set speed B and lower than the set speed C. In the plowing depth control mechanism according to claim 1,
When the vehicle speed is lower than the set speed A and higher than the set speed C, the upper limit value of the control gain of the actuator that raises and lowers the work implement is set to a constant value, and is set below the set speed B set between the set speed A and the set speed C. The tractor working machine is characterized in that the upper limit value of the gain is increased in proportion to an increase in the vehicle speed at a speed A or higher, and the upper limit value of the gain is decreased in proportion to an increase in the vehicle speed at a set speed B or higher and lower than the set speed C. Plowing depth control mechanism.

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