JP3605991B2 - Tractor load control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a load control device for a tractor, and more particularly to a load control device for a tractor that raises and lowers a working machine when there is a change in engine speed.
[0002]
[Prior art]
The load control device of the tractor is provided with a means for detecting the engine speed and a means for calculating a rate of change of the engine speed within a predetermined time, and the means for constantly grasping the fluctuation of the engine speed. In addition, when the engine speed fluctuates due to an increase in the workload, the engine speed is controlled to be maintained within a predetermined range to prevent engine stall.
[0003]
The load control method is roughly divided into work implement lifting / lowering processing and deceleration processing. The work implement lifting / lowering processing is to output a work implement elevation command when the engine speed fluctuates and to reduce the load by raising the work implement. The deceleration processing is performed when the engine speed fluctuates. To reduce the load by decelerating the body.
[0004]
There are several conditions for starting the load control. For example, the load control is started when the engine speed decreases due to a work load and the engine speed falls below a preset lower limit. Alternatively, the load control is started when the rate of change increases as the engine speed decreases and the rate of change exceeds a specified value.
[0005]
[Problems to be solved by the invention]
In a conventional load control device for a tractor, when a change-down command of a transmission is output in a deceleration process when a change rate of an engine speed exceeds a specified value, soil in a field is reduced. When the rate of change of the engine speed exceeds the specified value many times due to lump, etc., the shift down of the transmission is frequently performed by the deceleration process, so the vehicle speed decreases and the work efficiency deteriorates significantly. Become.
[0006]
Therefore, when controlling the load on the tractor, there arises a technical problem to be solved in order to prevent a reduction in work efficiency by not performing deceleration processing frequently, and the present invention solves this problem. The purpose is to do.
[0007]
[Means for Solving the Problems]
The present invention has been proposed in order to achieve the above object, and is a tractor in which a ground working machine is connected to the rear of an aircraft in a vertically movable manner, wherein a means for detecting an engine speed and a change rate of the engine speed are provided. Calculating means for determining the traction load of the work implement from the fluctuations in the engine speed, and when the engine speed fluctuates due to the increase in the load, the engine speed decreases and the rate of change exceeds the specified value. And outputs a deceleration command for the transmission when the engine speed is equal to or lower than a preset lower limit value so that the engine speed is maintained within a predetermined range. in the tractor to perform the load control, the engine speed is detected less the lower limit value, and performs deceleration processing of only the transmission when the continuous prescribed duration or more of the following the lower limit, deceleration Predetermined time after performing the physical is a deceleration prohibition time domain, further deceleration processing is to provide a load control device of the tractor which is not performed.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a tractor 1 in which an engine 3 is mounted on a front portion of an airframe 2, and an electronically controlled governor 4 is mounted on a side of the engine 3. The power of the engine 3 is reduced by a transmission provided in the transmission case 5 and transmitted to the rear wheels 6 for two-wheel drive, or transmitted to the rear wheels 6 and the front wheels 7 for four-wheel drive. In the transmission case 5, the PTO system power is branched from the traveling system power and transmitted to the PTO shaft 8. The engine speed is detected by an engine speed sensor 9.
[0009]
On the other hand, a working machine 16 for tilling is connected to a rear portion of the body 2 via a link mechanism 15. The link mechanism 15 is a three-point link system including a top link 17 and left and right lower links 18. The distal ends of the left and right lift arms 19 and the left and right lower links 18 are connected by lift rods 20, respectively.
[0010]
When the lift arm 19 is rotated by the operation of the lift cylinder 21 provided at the upper part of the transmission case 5, the lower link 18 moves up and down, and the work machine 16 moves up and down. The rotation angle of the lift arm 19 is detected by a lift arm sensor 22. Further, a rear cover 24 is rotatably attached to the rear end of the main cover 23 of the work machine 16, and the depth sensor 25 detects the rotation angle of the rear cover 24.
[0011]
Here, a controller 29 is provided near the driver's seat 28. The controller 29 is provided with a position lever 30, a tillage setting dial 31, a load control mode switch 32, and the like. A vehicle speed sensor 33 is provided below the driver's seat 28. Further, a work implement elevating switch 35 is provided near the steering wheel 34, and a steering angle sensor 37 is mounted on the steering shaft 36.
[0012]
FIG. 2 shows a shift lever 40 provided in the vicinity of the driver's seat 28. The shift lever 40 is designed to shift back and forth along a guide groove 42 of a lever guide box 41, and after a rotation range thereof. From the side to the front side, each operation position of the sub-shift, such as “ultra low speed (LL)”, “rotary (L)”, “plow / scratch (M)”, “neutral (N)”, “running (H)” Is provided.
[0013]
For example, “ultra-low speed” is an operation position for traveling at ultra-low speed such as creeping operation. When the shift lever 40 is shifted to “ultra-low speed”, the speed increasing button 43 provided on the grip portion of the shift lever 40 is operated. Alternatively, the main shift can be shifted from the first gear to the fourth gear by pressing the deceleration button 44. Similarly, at other operation positions, by pressing the speed-up button 43 or the deceleration button 44, the main shift is shifted up or down by one step within the shiftable area of each operation position of the sub-shift. The auxiliary transmission has a large reduction ratio for each operation position, and the main transmission has a small reduction ratio for each operation position. Therefore, a fine shift is performed by pressing the speed-up button 43 or the deceleration button 44.
[0014]
The shift position of the shift lever 40 is detected by a shift position sensor 45, which will be described later. Based on the detected value of the shift position sensor 45 and the pressing operation of the speed-up button 43 or the deceleration button 44, the controller 29 sends the main transmission and the sub-transmission. A signal is sent to the switching valve of the device to switch between the main transmission gear and the auxiliary transmission gear. At the same time, a signal is sent to a display device 46 provided in the lever guide box 41 to display the shift position of the transmission.
[0015]
As described above, when shifting the shift lever 40 to each operation position, a single shift lever 40 can be used to electrically switch between the main shift and the sub-shift without the need to depress the clutch pedal.
[0016]
FIG. 3 is a block diagram of the load control device for the tractor. The setting signals of the position lever 30, the tillage depth setting dial 31, the load control mode switch 32, and the like are input to the controller 29. Further, detection signals from the engine speed sensor 9, the lift arm sensor 22, the depth sensor 25, the vehicle speed sensor 33, and the like are input to the controller 29. The controller 29 calculates the actual tillage depth value from the rotation angle of the rear cover 24 detected by the depth sensor 25, and works so that the actual tillage depth value matches the set tillage depth value input by the tillage depth setting dial 31. The plowing depth of the machine 16 is controlled. In such a case, a control signal is output to the ascending solenoid 50 or the descending solenoid 51 of the electromagnetic proportional valve in order to move the lift machine 21 up and down by moving the lift cylinder 21 up and down.
[0017]
In addition, a control signal is output from the controller 29 to the main shift first stage solenoid 55 to the main shift fourth stage 58 based on the pressing operation of the speed-up button 43 or the deceleration button 44 described above, and the main shift gear is shifted. Switch. The shift position of the shift lever 40 is detected by a shift position sensor 45. The forward / reverse lever sensor 47 determines whether the forward / reverse lever is set to forward or reverse. Although not shown, the forward / reverse clutch is composed of a pair of wet multi-plate clutches. When the forward / reverse lever is set to forward, a control signal is sent from the controller 29 to the forward step-up solenoid 60. Output and connect the forward / reverse clutch to the forward position. On the other hand, when the forward / reverse lever is set to reverse, a control signal is output from the controller 29 to the reverse step-up solenoid 61, and the forward / reverse clutch is connected to the reverse position.
[0018]
Further, when the load control mode switch 32 is turned on, load control is performed as described later. At this time, the load control mode lamp 52 is turned on to notify the operator that load control is being executed.
[0019]
Next, the load control of the present invention will be described with reference to the flowchart of FIG. 4. In order to determine the traction load of the work implement 16 from the engine speed, the controller 29 periodically controls the engine speed by the engine speed sensor 9. R is detected, and a change rate D of the engine speed during a certain time Δt is calculated (step 100). Further, the lower limit value R _L of the engine rotational speed according to a preset tilling depth value, previously determined specified value D _R of the rate of change of when the engine speed drops, the engine speed R is relatively the workload increase lowered, when the rate of change D exceeds a specified value D _R (step 101), it executes a working machine lifting process by the load control (step 120).
[0020]
In this work machine lifting / lowering process, a work machine lift command is output from the controller 29 to the lift solenoid 50. At that time, the lift cylinder 21 is extended and driven, the lift arm 19 is rotated upward, the lower link 18 is lifted via the lift rod 20, and the work implement 16 is automatically raised. The height of the work machine 16 is detected by the lift arm sensor 22. Then, when the load is reduced and the engine speed R increases, the controller 29 outputs a work implement lowering command to the lowering solenoid 51. Therefore, the working machine 16 is automatically lowered by the reverse action.
[0021]
Meanwhile, when the engine speed R is began to decrease gradually, the although the change rate D in the engine speed is within the specified value D _R, there is the engine speed R is less than or equal to the lower limit R _L (Step 102). At this time, the vehicle speed S of the body 2 is detected by the vehicle speed sensor 33. If the vehicle speed S is 1 km / h or more, that is, if the body 2 is not stopped (step 103), the counting of the timer t is started (step 104). .
[0022]
When the timer t has elapsed for the prescribed duration time tm or more, the routine proceeds to step 105. Here, when the previous deceleration process is executed, a certain period of time (a time longer than the specified continuation time tm, for example, 5 to 10 seconds) is set as a deceleration prohibition time region, and no further deceleration process is performed in this deceleration prohibition time region. Stipulated. This is because it may be difficult to return the engine speed by load control depending on field conditions, and the engine speed may not be sufficiently increased even if the main transmission is shifted down by one stage due to the deceleration process. At this time, if the deceleration process is further executed, the engine speed further decreases. Therefore, by setting the above-described deceleration prohibition time region, unnecessary deceleration is prevented (step 106).
[0023]
Thus, when the time is not within the deceleration prohibition time area, deceleration processing by load control is executed (step 110). Here, based on the detection value of the shift position sensor 45 and the pressing operation of the speed-up button 43 or the deceleration button 44, the controller 29 previously knows the shift positions of the main transmission and the sub-transmission, and in the deceleration processing Outputs a deceleration command from the controller 29 to any of the main shift first stage solenoid 55 to the main shift third stage 57 to automatically shift down the main shift by one stage. After the downshift is performed, the deceleration process ends.
[0024]
If the engine speed R has not decreased to the lower limit value _RL in step 102, the load is light, so the timer t is cleared (step 107), and the process returns to the beginning to perform load control. repeat.
[0025]
On the other hand, the case where the vehicle speed S has not reached 1 km / h in step 103 will be described. For example, the work machine 16 is lowered while the machine body 2 is stopped by depressing the clutch pedal on a headland or the like, and then the clutch pedal When the work is performed to release the airframe 2 and the rotary tilling claws try to cut into the ground, the engine speed R decreases even when the airframe 2 is stopped or moving forward at a low speed. It may be lower than the lower limit value _RL . If the deceleration process is executed at this time, the main shift is downshifted after the start of the body 2, so that an uncomfortable feeling occurs in the operation of the operator. In such a case, the timer t is cleared without performing the deceleration process. After that (step 107), the process returns to the beginning and repeats the load control.
[0026]
Further, if the timer t is less than the specified continuation time tm in step 105, the process proceeds to step 108, and if the work machine ascending output processing has been performed, and if the work machine descending output is being performed or immediately after the descending output is stopped, (Step 109) A deceleration process by load control is executed even within the specified duration time tm (Step 110).
[0027]
As described above, when the load control is performed by detecting the fluctuation of the engine speed, in principle, the engine speed is reduced to be equal to or lower than the lower limit value _RL , and the engine speed is maintained to be equal to or lower than the lower limit value _RL for the specified duration time tm or longer. It is stipulated that the deceleration process is performed only when the speed is reduced. For example, as shown in FIG. 5, when the engine speed is the rate of change D exceeds a specified value D _R decreases, there is the working machine increases output working machine lifting process is executed at the time of t ₁ , whereby if increased engine speed to some extent, there is a working machine lowers the output at time t _2. Then, the engine speed gradually decreases, defined duration tm from equal to or less than a lower limit value R _L performs deceleration processing at the time of the t ₄ has elapsed at time t _3. After the deceleration processing is executed, as described above, the deceleration prohibition time area is set for a certain time after that, so that further deceleration processing is not performed.
[0028]
Further, as shown in FIG. 6, the engine speed is reduced, when the change rate D in the engine speed exceeds a prescribed value D _R at time point and t ₆ of t _5, respectively each time work machine Although the elevating process is executed, the engine speed does not decrease to the lower limit value _RL, so that the deceleration process is not executed. Therefore, the deceleration process is not performed more frequently than necessary, and the work time in the field is shortened, and the work efficiency is improved.
[0029]
Then, when the working machine lifting process change rate D of the engine speed exceeds the specified value D _R again is executed at the time of t _7, the engine speed is temporarily below the lower limit value R _L at time t ₈ If this happens, immediately after working machine descending output or during working machine falling output stop after working machine increases output, at the time t ₉ the engine speed is equal to or less than the lower limit value R _L again at the time of t ₈ The deceleration process is executed even if the specified duration tm has not elapsed since the engine speed became equal to or lower than the lower limit value _RL .
[0030]
In other words, even when the duration after the engine speed falls below the lower limit value _RL is short, if the situation when the work implement lifting and lowering processing is executed is heavy load, the engine is not driven by the work implement elevation output. After the rotation speed is restored, the engine rotation speed may become lower than or equal to the lower limit value _RL again due to the work implement lowering output. In such a case, a deceleration process is executed to reduce the load.
[0031]
Here, the working machine lifting process by load control, as shown in FIG. 7, the engine speed is reduced relatively large output work machine increase command when the rate of change D exceeds a specified value D _R Although than is, the output conditions and stop condition after increasing the output of the rising command changes the engine speed magnitude at that point in time t _n. FIG. 8 is a flowchart showing the work machine ascending output and the stop of the work machine ascending output.
[0032]
Now, for example, as shown in FIG. 9, (approximately 400rpm be defined by the rotational speed difference) when the engine speed is greater than or equal to about 2500rpm defines a prescribed value _{D R} of the rate of change of about -0.16, when the front and rear engine speed is about 2000rpm to change the specified value _{D R} about -0.12 (rotational speed difference of about 250 rpm). Then, in the following engine speed is about 1500rpm defines the specified value _{D R} about -0.07 (rotational speed difference of about 100 rpm).
[0033]
That is, when the engine speed at the time when the change rate D is calculated is relatively high, the work machine is prevented from rising and the frequent lifting and lowering operations of the work machine are prevented because the engine has room. On the other hand, when the engine speed at the time when the change rate D is calculated is relatively low, the engine has no margin and tends to stall.
[0034]
On the other hand, the condition for stopping the work implement ascent output is changed according to the state of return of the engine speed at time point tn _{+ 1} in FIG. For example, as shown in FIG. 10, when the engine speed after the work implement rises is about 1500 rpm or less, the engine speed _RS for stopping the work implement rise is changed to the minimum engine speed R _S during the work implement elevation processing. ₀ + 100 rpm, and the working machine rising output is not stopped until this time. However, when the engine speed is about 2,000 rpm, the engine speed _RS for stopping the working machine rising is set to the minimum engine speed R ₀ + 50 rpm. . Then, when the engine speed is about 2500 rpm or more, it is defined that the work implement ascent output is stopped immediately at that time.
[0035]
That is, when the engine speed at a certain point after the work implement rises is relatively low, the engine has no margin and tends to stall, so the work implement rise output is not stopped until the engine speed becomes high to some extent. Let the numbers recover enough. On the other hand, when the engine speed is relatively high, there is room in the engine, so the work implement ascending output is stopped as soon as the engine speed slightly increases to prevent the work implement from moving too much.
[0036]
Next, the speed increasing process after the deceleration process will be described. After the main speed is automatically shifted down by one stage by the above-described deceleration process, as the engine speed increases and returns, the controller 29 sends the main speed second stage solenoid 56 through the main speed fourth stage solenoid. The main gear is automatically shifted up by one stage by outputting a speed increase command to any one of the gears 58. FIGS. 11 and 12 show flowcharts of the speed increasing process.
[0037]
When the deceleration process is performed (step 301), the engine speed is restored to some extent. However, if the speed increase process is immediately performed, the engine speed may again decrease and the deceleration process may be required. Therefore, after the deceleration processing implementation performs accelerated processing when waking up the engine speed R is near rated speed _{R T} are equipped with field conditions and working conditions (for example, approximately _R T -100 rpm) (step 302).
[0038]
When the operator manually performs the acceleration / deceleration operation (step 303) or when the operator performs the reverse operation using the forward / reverse lever (step 304), the memory of the execution of the deceleration processing is cleared and the load control is newly performed. Is not performed until there is a deceleration process. This is because the contents of the work often change when a manual operation is performed by the operator. For example, when changing from the adjacent tilling to the headland tilling, the pitching and rolling of the body increase, and the load variation increases. Therefore, even if the speed increasing process is performed, the speed must be reduced again immediately after that, and in such a case, the speed increasing process is not performed.
[0039]
Here, when performing the tilling work in the field, the tilling is performed while traveling straight from one end of the field to the other end, and the work machine is raised at the end of the field and then turned. Then, after the turning is completed, the work machine is lowered, and this time, the plow is plowed while traveling straight in the reverse direction in the field. In this way, when the vehicle travels straight a certain distance and repeats the operation of raising the work machine, turning the machine, and lowering the work machine, the travel distance of one process from the work machine lowering to the next work machine raising is substantially equal. Will be the same.
[0040]
Therefore, when the working machine is raised and lowered, the traveling distance from when the working machine is lowered to when the working machine is raised again next time is measured. First, immediately after the work implement descends (step 401), the counting of the distance L is started (step 402). If there is no condition for clearing the count of the distance L (step 403), the process returns to the beginning and proceeds from step 401 to step 410. If the work machine is not descending (that is, the first work machine lifting / lowering process is completed), the process returns to step 411. To determine whether or not the work machine has just risen.
[0041]
When the work implement lifting / lowering processing is performed again after the first work implement lifting / lowering processing is completed, the distance L is stored in the memory immediately after the work implement rises (step 411) (step 412). In that case, the count clear condition of the distance L is satisfied (step 403), and the count of the distance L is cleared (step 404).
[0042]
Thus, every time the work implement lifting / lowering process is performed, the distance L from immediately after the work implement lowering to immediately after the next work implement elevation is stored, and the previous distance L is referred to in step 305. From the difference between the previous distance L and the current travel distance L _NOW after the work machine has been lowered, a remaining distance L _REM until the next work machine ascent is calculated (step 306). Then, if there is a remaining distance _{L REM} than the specified value _{L R} (step 307), to implement the speed increasing process automatically first speed shift up the main transmission (step 310). However, if the remaining distance L _REM less than the predetermined value L _R, because the turning point is imminent, not performed accelerated process for inhibiting the accelerating of the turning immediately before.
[0043]
The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.
[0044]
【The invention's effect】
As described above, according to the present invention, the means for detecting the engine speed and the means for calculating the rate of change of the engine speed are provided, and the traction load of the working machine is determined from the fluctuation of the engine speed, and the increase in the load is determined. When the engine speed fluctuates, the work implement raising command is output when the engine speed decreases and the rate of change exceeds a specified value, and when the engine speed is detected to be equal to or less than a preset lower limit value. A tractor that outputs a deceleration command to the transmission and controls the load so that the engine speed is maintained within a predetermined range. The deceleration process of the transmission is executed only when the following is continued for the specified duration or more.If the change rate of the engine speed does not reach the lower limit even when the rate of change of the engine speed exceeds the specified value, the deceleration process of the transmission is performed. Not row. That is, even if the engine speed decreases to some extent, if the engine speed is lower than the lower limit for a short time, the engine speed is restored by the work implement elevating process, and the deceleration process is not performed. In addition, a certain time after the execution of the deceleration processing is set as a deceleration prohibition time area, and further deceleration processing is not performed. Therefore, the deceleration process is not performed more frequently than necessary, and the work time in the field is shortened, and the work efficiency is improved.
[0045]
For this reason, frequent downshifts due to the deceleration process are eliminated, and the vehicle speed can be maintained high to improve the working efficiency.
[Brief description of the drawings]
The figure shows an embodiment of the present invention.
FIG. 1 is a side view of a tractor.
FIG. 2 is a plan view of a shift lever and a lever guide box.
FIG. 3 is a block diagram of a tillage depth control and a load control system.
FIG. 4 is a flowchart illustrating an example of a load control process.
FIG. 5 is a timing chart showing an example of fluctuations in engine speed and lifting and lowering of a work implement.
FIG. 6 is a timing chart showing another example of the fluctuation of the engine speed and the lifting and lowering of the work implement.
FIG. 7 is a timing chart of fluctuations in the engine speed and stop of the work machine rise output.
FIG. 8 is a flowchart of work machine ascending output and ascending output stop.
FIG. 9 is a graph showing a relationship between an engine speed, which is a work implement ascending output condition, and a rate of change thereof.
FIG. 10 is a graph showing a relationship between an engine speed and a stop speed, which are conditions for stopping a work implement ascending output.
FIG. 11 is a flowchart of a speed increasing process after the deceleration process.
FIG. 12 is a flowchart for measuring a traveling distance during a lifting step.
[Explanation of symbols]
1 Tractor 2 Body 9 Engine speed sensor 16 Work implement 29 Controller

Claims (1)

A tractor having a ground work machine connected to the rear part of the fuselage so as to be able to move up and down, provided with a means for detecting an engine speed and a means for calculating a rate of change of the engine speed. Judging from the fluctuation, when the engine speed fluctuates due to an increase in the load, when the engine speed decreases and the rate of change exceeds a specified value, a work implement raising command is output, and the engine speed is set in advance. A tractor that outputs a deceleration command for the transmission when it detects a value equal to or less than the lower limit and performs load control so that the engine speed is maintained within a predetermined range .
The deceleration process of the transmission is performed only when the engine speed is less than or equal to the lower limit value and the lower limit value or less is maintained for a specified duration or more, and deceleration is prohibited for a certain time after the deceleration process is performed. A load control device for a tractor, wherein a time domain is set and further deceleration processing is not performed.

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