JP3687310B2 - Tractor load control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a load control device that performs control so that a work load does not become excessive during ground work by a tractor.
[0002]
[Prior art]
When the work load increases during ground work by the tractor, there is a risk of engine stalling if the work is continued as it is.Therefore, when the engine speed fluctuates due to an increase in the work load, the work equipment is lifted to reduce the load. Perform load control to reduce.
[0003]
[Problems to be solved by the invention]
In the above load control, conventionally, when the work is temporarily stopped and then restarted, when the vehicle speed is changed by performing a speed change operation or a brake operation during the work, the work machine is moved up and down by the fluctuation of the engine speed, There was a problem that the ground working depth was disturbed.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is configured as follows. That is, the load control device for a tractor according to the present invention includes left and right brake pedals (24L) and (24R), and left and right brake pedal switches (25L) and (25R) that detect the depression of the left and right brake pedals. An engine speed sensor (13) for detecting the speed of the engine (5), and a load control device for a tractor on which the ground work machine (50) is mounted so as to be movable up and down, the engine speed sensor ( 13) When the rotational speed of the engine (5) detected by 13) falls to a predetermined lower limit value or when the rate of change of the engine rotational speed reduction exceeds a preset specified value, the work implement (50) is raised. performs load control increase output request is issued, that is until a predetermined time elapses or after the brake operation control is performed to regulate the control of the control device It is a symptom.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a state where a rotary cultivator is connected as a working machine to a tractor provided with a load control device of the present invention. The tractor 1 is a four-wheel drive vehicle having front wheels 2 and 2 and rear wheels 3 and 3 as drive wheels, and an engine 5 is mounted on the front of the fuselage, a clutch case 6 on the rear side, and then A mission case 7 is provided on each side.
[0008]
FIG. 2 is a transmission mechanism diagram of the tractor. The rotational power of the engine 5 is input to the transmission case 7 through the clutch 10 in the clutch case 6 so that the transmission can be turned on and off. The clutch 10 is turned on and off by a clutch pedal 11. A clutch pedal switch 12 is provided that switches between ON and OFF depending on whether or not the clutch pedal 11 is depressed. An engine speed sensor 13 that detects the engine speed only when the clutch is “ON” is provided on the lower transmission side of the clutch 10. The rotational power input to the mission case 7 is branched into two systems: a traveling drive force for driving the front wheels 2 and 2 and the rear wheels 3 and 3 and a PTO drive force for extracting external power.
[0009]
The traveling driving force is transmitted to only the rear wheels 3 and 3 after being switched between the forward and reverse rotations and decelerated by the forward / rearward transmission 15, the main transmission 16, and the auxiliary transmission 17, or is transmitted to the front wheels 2 and 2. It is transmitted to both the rear wheels 3 and 3. 18 in the figure is a 4WD switching device in which the front wheel and rear wheel rotation speeds are substantially equal to each other, and the front wheel rotation speed is approximately twice the rear wheel rotation speed. Switch between the “4WD” state and the “Rearwheel 2WD” state in which the front wheels are turned off and only the rear wheels are driven. For example, the main transmission 16 has four shift positions, and the sub-transmission 17 has two shift positions, “high speed” for traveling on the road and “low speed” for work. A main speed change lever 20 is provided as an operation part for shifting the main speed change device 16, and an operation position of the main speed change lever is detected by a speed change lever sensor 21 which is a speed change position detecting means.
[0010]
Further, brake devices 23L and 23R capable of individually braking the left and right rear wheels are provided in the transmission path to the rear wheels 3 and 3. Brake pedals 24L and 24R are provided as operating portions of the brake devices 23L and 23R, and brake pedal switches 25L and 25R serving as brake operation detecting means detect the depression of the brake pedal.
[0011]
On the other hand, the PTO drive force is extracted via the PTO transmission 27 to the PTO shaft 28 protruding rearward from the rear surface portion of the transmission case 7 and then transmitted to the work implement.
[0012]
The driver's seat 30 is installed above the mission case 7. A handle 31 for steering the front wheels 2 and 2 is provided in front of the driver seat 30, and the clutch pedal 11, brake pedals 24 </ b> L and 24 </ b> R are provided below the feet. Further, the main speed change lever 20 is provided on the left side of the driver's seat 30, and a controller 33 for performing various controls is provided on the right side. A position lever 35, a tilling depth setting dial 36, a load control mode switch 37, a deceleration start position setting dial 38, etc., which will be described later, are attached to the controller 33.
[0013]
Lift arms 41 and 41 that are turned up and down by a lifting hydraulic cylinder 40 are provided at the rear of the machine body. The elevating hydraulic cylinder 40 is controlled by a proportional solenoid valve 42. The front ends of the lift arms 41, 41 and the intermediate portions of the lower links 43, 43 are connected by lift rods 44, 44. By raising and lowering the lift arms 41, 41, the lower links 43, 43 and the top are connected. The work machine supported by the three-point link mechanism constituted by the link 45 moves up and down. The rotation angles of the lift arms 41 and 41 are detected by a lift arm sensor 46.
[0014]
The rotary tiller 50, which is a working machine, cultivates the soil with the tilling blades 51,. The rear part of the cover 52 covering the tilling blades 51,... Is a rotatable rear cover 52a, and the rotation angle of the rear cover 52a is detected by the depth sensor 53.
[0015]
FIG. 3 is a block diagram of the lift control device. On the input side of the controller 33, the clutch pedal switch 12, the engine speed sensor 13, the shift lever sensor 21, the brake pedal switches 25L and 25R, the position lever 35, the tilling depth setting dial 36, A load control mode switch 37, a deceleration start position setting dial 38, a lift arm sensor 46, a depth sensor 53, and the like are connected. Based on these pieces of information, the controller 33 raises a solenoid 42a or a solenoid for lowering the proportional solenoid valve 42. A command signal is output to 42b and the work implement is raised and lowered. The control by the controller 33 includes position control, tilling depth control, load control, and work implement lowering speed control described below.
[0016]
The position control is control when the work implement is manually raised and lowered, and the work implement is raised and lowered so that the work implement position is in accordance with the operation position of the position lever 35. The work machine position is determined by the detection value of the lift arm sensor 46.
[0017]
The plowing depth control is a control of the plowing depth by the rotary plowing device 50. The plowing depth control 53 calculates the actual plowing depth value from the rotation angle of the rear cover 52a detected by the depth sensor 53, and uses this plowing depth value to the plowing depth setting dial 36. The work implement (rotary tilling device) is moved up and down so that it matches the set plowing depth value entered.
[0018]
The load control is a control for preventing the work load from becoming too large, and there are three types of control shown in the respective flowcharts in FIGS. 4, 6 and 7. In any case, when the load control mode switch 37 is turned ON, the load control mode is set.
[0019]
In the first load control shown in FIG. 4, first, the input signals of the sensors and switches are read, and then it is determined whether or not the load control mode is selected. If not in mode, go back. In the load control mode, it is determined whether or not there is a lift output request due to fluctuations in engine speed. Specifically, when the engine speed falls to a predetermined lower limit value or when the rate of change in engine speed reduction exceeds a preset specified value, an increase output request is issued. When the load is reduced and the engine speed increases, a lowering output request is issued. If there is a lift output request, the lift output is turned on only when the clutch is “ON” and a certain time or more has elapsed since the clutch changed from “OFF” to “ON”. If any of these is not satisfied, the lifting output is turned off. The controller 33 is a control means for outputting a command for raising and lowering the work implement in accordance with fluctuations in the engine speed, and a regulation means for regulating the control of the control means.
[0020]
For example, as shown in FIG. 5, if the engine speed sensor value R decreases during ground work and falls below the lower limit value R _L , an increased output is output (T ₁ ), whereby the engine speed sensor value R When the value rises to some extent, a descending output is output (T ₂ ). When the clutch is disengaged due to work interruption or the like (T ₃ ), the engine speed sensor value R decreases to “0”. When the clutch is engaged and the work is resumed (T ₄ ), the engine speed sensor value R eventually becomes Returns to normal value. The engine speed sensor value R is the lower limit value R during the clutch “disengagement” (T ₃ → T ₄ ) and for a certain time t after the clutch changes from “disengagement” to “on” (T ₄ → T ₅ ). _{Since the} lift output is not output even if it is less than or equal to _L , the lift of the work implement is restricted when the engine speed is unstable while stopping, immediately after starting, or immediately after shift change, and the ground work depth such as tillage depth Is prevented from fluctuating greatly.
[0021]
The second load control shown in FIG. 6 is the same as the first load control until halfway, when there is a lift output request, when there is a shift operation, and when a certain time or more has elapsed after the shift operation. The lift output is turned on as long as possible, and if at least one of the above conditions is not satisfied, the lift output is turned off. The controller 33 is a control means for outputting a command for raising and lowering the work implement in accordance with fluctuations in the engine speed, and a regulation means for regulating the control of the control means.
[0022]
In the third load control shown in FIG. 7, it is the same as the first and second load controls up to the middle, and when there is a lift output request, there is a brake operation and a certain time or more has elapsed after the brake operation. The lift output is turned on only when it is present, and the lift output is turned off when at least one of the above conditions is not satisfied. The controller 33 is a control means for outputting a command for raising and lowering the work implement in accordance with fluctuations in the engine speed, and a regulation means for regulating the control of the control means.
[0023]
As for the second load control, as for the third load control, the lifting and lowering of the work implement at the time when the engine speed immediately after the brake operation is unstable is restricted, and the ground work depth such as tillage depth is controlled. It is prevented that the fluctuation is large.
[0024]
The work implement lowering speed control is a control for lowering the work implement to the working position. When the work implement is lowered to the position set by the deceleration start position setting dial 38, the ON time of the pulse output to the descending solenoid 42b is shortened. Then, the lowering speed of the work machine is reduced. The position where deceleration is started can be adjusted with the deceleration start position setting dial 38.
[0025]
FIG. 8 is a flowchart of deceleration start position adjustment. After reading the input signals of the sensors and switches, it is determined whether or not the safety mode has been released. Here, the safety mode is a control mode in which the output is not raised or lowered when the engine is started in order to prevent the work implement from being raised or lowered simultaneously with the start of the engine when the position lever 35 is operated while the engine is stopped. After the engine is started, the safety mode is canceled when the operation position of the position lever 35 is matched with the work machine position indicated by the lift arm sensor 46.
[0026]
If the safety mode is cancelled, it is next determined whether or not the depth sensor 53 is connected. When the depth sensor is connected, that is, when the work machine is mounted, the process proceeds to the next step. When the depth sensor is not connected, that is, when the work machine is not mounted, there is no point in proceeding, so the process is terminated.
[0027]
Next, it is determined whether or not the deceleration start position setting dial 38 has been rotated. If the deceleration start position setting dial 38 has been rotated, a deceleration start position adjustment start flag is set, and the deceleration start position setting dial value is set. The lift arms 31 and 31 are operated so that the lift arm sensor values match. If both match, the lift arms 31 are stopped. That is, when the deceleration start position setting dial 38 is turned to adjust the deceleration start position, the work implement is actually moved up and down to the deceleration start position at that time. For this reason, it is easy to grasp the deceleration start position sensuously and it is easy to adjust. Conventionally, after setting and operating the deceleration start position setting dial 38, the work implement is temporarily raised to the uppermost position, and then the work implement is lowered to visually check the position where the work implement lowering speed control starts to work. Because it had to be, adjustment was not easy.
[0028]
When the above setting is completed, after entering the safety mode, the deceleration start position adjustment start flag is canceled. This is to prevent the working machine from moving up and down due to the difference between the operating position of the position lever 35 and the actual working machine position when the working machine is moved up and down to the deceleration start position. is there. Then, when the position lever 35 is operated and the operation position of the position lever matches the actual work machine position, the safety mode is canceled.
[0029]
【The invention's effect】
As described above, the load control device of the tractor according to the present invention, until the older than a predetermined time after the braking operation, so even if there is fluctuation of the engine rotational speed does not output a command to lower the ground work machine, brake engine speed immediately after the operation is regulated elevator of the working machine in unstable point, ground working depth that varies greatly now be prevented.
[Brief description of the drawings]
FIG. 1 is a side view in which a rotary tiller is mounted on a tractor.
FIG. 2 is a transmission mechanism diagram of a tractor.
FIG. 3 is a block diagram of a lift control device.
FIG. 4 is a flowchart of first load control.
FIG. 5 is a time chart of an engine speed sensor value, a lift output, and a clutch on / off state.
FIG. 6 is a flowchart of second load control.
FIG. 7 is a flowchart of third load control.
FIG. 8 is a flowchart of deceleration start position adjustment control.
[Explanation of symbols]
1 Tractor 5 Engine 10 Clutch 11 Clutch pedal switch 13 Engine speed sensor 25L, 25R Brake pedal switch 33 Controller (control means, regulation means)
35 Position lever 36 Plowing depth setting dial 37 Load control mode switch 38 Deceleration start position setting dial 41 Lift arm 42a Lifting solenoid 42b Lowering solenoid 46 Lift arm sensor 50 Rotary plowing device (work machine)
53 Depth sensor

Claims (1)

Left and right brake pedals (24L) and (24R), left and right brake pedal switches (25L) and (25R) for detecting depression of the left and right brake pedals, and engine rotation for detecting the rotational speed of the engine (5) A load control device for a tractor equipped with a ground work machine (50) so as to be movable up and down, the number of revolutions of the engine (5) detected by the engine revolution number sensor (13) When the engine speed falls to a predetermined lower limit value or the rate of change in engine speed reduction exceeds a preset specified value, load control is performed so that an increase output request for raising the work machine (50) is issued, and the brake A load control device for a tractor that performs control to restrict control of the control device until a predetermined time or more elapses after the operation .

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