JP2006336696A - Speed-change controller of agricultural work vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily provide a working speed according to an operator by reducing speed change operations during the operation of a tractor. <P>SOLUTION: This speed-change controller of the tractor comprises a controller which counts the cumulative use time of a main speed change shift position on a main speed-change device 3 for each auxiliary speed-change shift position and, when an auxiliary speed-change device 21 is operated, immediately outputs to a main speed-change position with the longest use time at the auxiliary speed-change shift position after operating a speed-change lever 20. The speed of the main speed-change device 3 is controllably increased or decreased according to the fluctuation of a load on an engine while setting the main speed-change shift position with the longest use time at the highest speed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a shift control device for an agricultural vehicle, and more particularly, to reduce an operator's shift operation by automatically shifting according to a variable load of the agricultural vehicle.

  Conventionally, a shift control device in a farm vehicle, for example, an agricultural tractor, transmits rotational power of an engine to front and rear wheels via a main transmission and a sub-transmission, and the main transmission is automatically or manually operated by driving an actuator. 2. Description of the Related Art There is known a configuration in which switching is possible and a sub-transmission device is configured to be mechanically switchable by a shift lever shift operation.

When the sub-shift is in a position suitable for work, there is a configuration in which the main shift is shifted to the storage position at the shift position with the longest previous work time in conjunction with the sub-transmission device (Patent Document 1). With this configuration, when the work is started, if the work content is the same, the speed change control can be immediately performed at the speed change position in accordance with the operator's intention, which facilitates the operation and is convenient.
JP 2004-251351 A

  However, during a work operation, a shift to a predetermined gear position corresponding to the change in work load has been unavoidable. That is, when the operator determines that the load is high, the speed is shifted to the deceleration side to cope with the increase in load, and when the load is released, the operation is returned to the original gear position and continued. Therefore, it is necessary to repeat deceleration and return shifting according to the load fluctuation, and the operation is troublesome.

  Also, in the form of shifting the main shift to the longest shift position in the previous work time in conjunction with the auxiliary transmission, a shift position that matches the operator's intention can be obtained if the work contents are the same. If the work content is changed as in, for example, a scraping hello work, the work speed is changed, so that a speed change operation is required, and it is necessary to shift from a shift depending on the shift position to a gear position corresponding to the work content.

  The present invention reduces the inconvenience of shifting operation during work, and easily obtains a work speed according to the operator.

For this reason, this invention took the following technical means.
According to the first aspect of the present invention, the cumulative use time of the main transmission shift position of the main transmission (3) is counted for each auxiliary transmission shift position, and the shift is performed when the auxiliary transmission (21) is operated. In a tractor shift control apparatus provided with a controller (10a) that immediately outputs to a main shift shift position having the longest use time at the sub shift shift position after operation of the lever (20), the main control unit having the longest use time The transmission shift position is set to the highest speed, and the structure of the tractor shift control apparatus is configured to increase / decrease the speed of the main transmission (3) according to engine load fluctuations.

  As described above, during operation, the main transmission position stored in the controller (19a) is set to the highest speed, and the main transmission (3) is configured to increase / decrease in accordance with engine load fluctuations. When the load increases at speed, the speed is automatically reduced, and when the load is reduced, the original speed stage is restored, so that frequent button switch operations are not required even during work.

  According to the second aspect of the present invention, when shifting to the speed-increasing side from the main shift shift position having the longest use time by manual operation, the shift position is set to the highest position according to engine load fluctuations. The transmission (3) is configured to increase and decrease speed. As a result, the acceleration / deceleration selection range intended by the operator can be followed.

  According to a third aspect of the present invention, in the above, the uppermost speed is set on the side of the main shift position where the usage time is the longest during work. With this configuration, the operator's intended working speed can be obtained, and when the load is large, the speed is automatically decelerated, and when there is a margin, the speed can be increased to one step, thereby reducing manual shifting during work. , Improve work efficiency.

  According to a fourth aspect of the present invention, the main transmission device (3) is configured to increase / decrease the speed according to engine load fluctuations with the most frequently used main transmission shift position as the highest speed. The acceleration after decelerating is sometimes configured to increase when the load factor has more margin than the determined load factor for a specified time immediately after deceleration and continues for a specified time. By performing the speed increasing operation when the predetermined margin state continues, frequent speed increasing / decreasing operations are eliminated.

  According to the first aspect of the present invention, the main shift position with the longest usage time is set to the highest speed during work, and the main shift is increased or decreased according to engine load fluctuations. When the load increases at the speed at which the user wants to work, the vehicle automatically decelerates, and when the load is reduced, the original speed stage is restored, so that frequent button switch operations are unnecessary even during the work.

  According to the second aspect of the present invention, when shifting to the speed increasing side from the main shift shift position having the longest use time by manual operation, the main shift is increased / decreased according to the engine load variation with the shift position as the highest position. Because the speed is increased, the acceleration / deceleration range can be expanded to follow the acceleration / deceleration selection range intended by the operator, but first, the operator can make fine adjustments after entering the main shift shift position that is frequently used last time. Therefore, the operation is easy and quick without significant change control.

  According to the third aspect of the present invention, during the work, the work speed intended by the operator can be obtained by setting the uppermost speed side of the main shift shift position having the longest use time to the highest speed, and the load is large. In this case, the vehicle is automatically decelerated, and when there is a margin, the speed can be increased up to one step, thereby reducing manual shifting during work and improving work efficiency.

  According to a fourth aspect of the present invention, the main shift shift position with the longest use time is set to the highest speed, and the main shift is increased or decreased according to the engine load fluctuation. The subsequent acceleration is increased when there is a margin in the load factor from the judgment load factor for the specified time immediately after deceleration and continues for the specified time or longer, so the speed increases when the specified margin state continues. Thus, frequent acceleration / deceleration operations are eliminated.

Hereinafter, the case where this invention is mounted in the agricultural tractor (henceforth, tractor T) used as a working vehicle is demonstrated based on drawing.
First, the configuration of the tractor T will be described.

  As shown in FIG. 2, the tractor T includes an engine E inside the bonnet 11, transmits the rotational power of the engine E to the transmission mechanism in the clutch housing 12 and the transmission case 13, and appropriately decelerates with various transmissions described later. After that, the vehicle is configured to travel by being transmitted to the rear wheel 2R or the front and rear wheels 2F, 2R as the traveling wheels.

  A steering handle 16 that steers the front wheel 2F is provided in front of the cockpit 15 of the tractor T, and a forward / reverse switching lever 17 that switches the vehicle forward and backward, and an accelerator lever 18 that adjusts the rotational speed of the engine E are provided below the steering handle 16. Is provided. A lever holding mechanism having a friction braking member is provided at the rotation base of the accelerator lever 18 and connected to a speed control mechanism (governor mechanism) G on the engine side via a wire. Thus, the accelerator position (throttle position) of the engine E is held at the set position.

  Further, a clutch pedal, left and right brake pedals 20 and 20 and an accelerator pedal 1 are provided below the steering handle 16, and the rotation base of the accelerator pedal 1 is urged to return the engine speed to the deceleration side. A spring is provided, and an accelerator pedal position sensor 1 s for detecting the depression operation is provided. Similarly to the accelerator lever 18, the rotation base of the accelerator pedal 1 is connected to the speed control mechanism G of the engine E through a wire, and is thereby set by the accelerator lever 18. With the held accelerator setting position as a lower limit, the engine speed is increased only when the accelerator pedal 1 is depressed, and when the depression is released, the original position set by the accelerator pedal 18 is restored.

  In a work vehicle such as the tractor, the accelerator lever 18 is generally operated at a constant speed with the engine rotation set to a high rotation position (full throttle position). The lever 18 is set to the low rotation position, and the accelerator pedal 1 is depressed to adjust the engine speed, that is, the vehicle speed.

  Further, as shown in FIG. 3, a y-type shift lever 20 is provided on the side of the cockpit 15, and a sub-transmission device 21 to be described later is moved in three stages (H, L, M). Further, a shift lever position sensor 20s for detecting a lever operation position is provided at the rotation base of the shift lever 20, and a pair of front and rear shift switches (shift up switch 20A, shift switch) for switching the main transmission 3 are provided on the lever gripping portion. A down switch 20B) is provided, and the shift position of the main transmission 3 is switched one by one through an energization command of the controller 10 by an operator's switch operation.

  Similarly, on the side of the cockpit 15 is provided a working machine lifting lever 22 for changing the rotation angle of the lift arm 32 at the rear of the vehicle body, that is, the height of the rotary working machine R in the figure. A potentiometer 22s for detecting the operation position is provided. Further, behind the lever guides of these levers 20 and 22, a tilling depth setting device 24 for setting the tilling depth of the rotary working machine R and a turning control on / off switch 23 for turning on and off the operation of the turning control device are provided. . The turning control on / off switch 23 raises the work implement R in conjunction with the turning operation of the tractor T, increases the peripheral speed of the front wheel 2F relative to the peripheral speed of the rear wheel 2R, The control for braking the rear wheel brake is turned on and off.

  These detectors 20s, 22s... And setting devices 23, 24... Are connected to the travel controller 10a or the work machine controller 10b which is the control means 10 of the present invention.

  A tractor T includes a cylinder case 31 that houses a hydraulic cylinder 30 for raising and lowering the work implement, and a lift arm 32 that supports the case 31 on the left and right sides by rotating the piston of the cylinder 30 up and down. Yes. Further, a link mechanism 29 is provided at the rear part of the vehicle body, and the working machine R is connected to the link mechanism 29. On one side of the lift arm 32, a lift arm angle sensor 32s is provided at the rotation base.

  Accordingly, the work machine controller 10b performs position control, more specifically, a proportional pressure control valve for raising the work machine so that the operation angle of the work machine elevating lever 22 and the set angle of the lift arm 32 are matched. The solenoid 33 or the work implement lowering control valve solenoid 34 is energized to raise and lower the work implement R.

Next, the power transmission path of the tractor T will be described with reference to FIG.
The rotational power of the engine E is intermittently operated by the main clutch 40 in the clutch housing 13. When the clutch 40 is engaged, the first main transmission 3 a provided with the power in the transmission case 13 is moved forward and backward. The switching device 41, the second main transmission 3b serving as the gear transmission of the present application, and the auxiliary transmission 21 are sequentially transmitted.

  The engine E is provided with an accelerator position sensor 35 in the speed governor G, an engine rotation sensor 36 on the output shaft, and the engine load state of the vehicle is detected by both sensors 35 and 36.

  The first main transmission 3a is a hydraulic clutch transmission having a high and low two-stage clutch (Hi clutch Ch, Lo clutch Cl), and either a high or low clutch plate is pressure-bonded by a piston inside the clutch. Thus, the rotational power can be switched between high and low, and the power is transmitted to the forward / reverse switching device 41.

  The forward / reverse switching device 41 is also a hydraulic clutch type switching device having two clutches (forward clutch Cf, reverse clutch Cr), and either one of the clutches according to the operating position of the forward / reverse switching lever 17. Select to synchronize with entering. The rotational power is transmitted to the second main transmission 3b by forward rotation or reverse rotation.

  The clutches Cf and Cr of the forward / reverse switching device 41 also serve as a booster clutch for switching the shift position of the main transmission 3, and adjust the pressure of the clutch disc by the proportional pressure control valve. The switching control valve communicates with either the front or rear clutch Cf (or Cr). That is, when the main transmission 3 is switched, the clutches Cf and Cr are both disconnected prior to the switching operation, and the forward clutch Cf or the reverse clutch Cr is engaged after the switching operation is completed.

  The second main transmission 3b is a synchromesh gear transmission having a "3-4 speed" shifting hydraulic cylinder 5A and a "1-2 speed" shifting hydraulic cylinder 5B, which are piston-type shifting actuators. Of the two hydraulic cylinders 5A and 5B, the piston of one cylinder 5A (5B) is extended or shortened, and the shifter 4A (4B) engaged with the tip portion is moved back and forth so that four gear sets The rotational power is transmitted to the auxiliary transmission 21 through one gear set. Specifically, the piston of the hydraulic cylinder 5A for shifting the “3-4 speed” shifts to the left side in the figure to become “4th speed”, and the piston shortens to the right side in the figure to become “3rd speed”. The “1-2 speed” shifting hydraulic cylinder 5B is configured to be “second speed” when the piston extends to the left side in the drawing, and “first speed” when the piston is shortened to the right side in the drawing.

  Thus, by combining the shift positions of the first main transmission device 3a and the second main transmission device 3b, the main transmission device 3 is configured to have 2 × 4 = all 8-speed shift positions. When shifting the main transmission 3, the shift position of the transmission 3 is increased or decelerated one by one by pressing the shift up switch 20A and the shift down switch 20B. Further, as will be described later, it is configured to increase or decrease the speed by the depression operation and depression operation of the accelerator pedal 1.

  The auxiliary transmission 21 is a sliding mesh gear type transmission that is switched by a manual operation of the transmission lever 20 via a mechanical interlocking mechanism such as a wire or a link mechanism, and is transmitted from the second main transmission 3b. The rotational power is transmitted through one of three gear sets from “H speed” to “M speed” and “L speed”, and output from the output shaft 45.

  As shown in FIG. 4, the tractor T having the main transmission 3 and the sub-transmission 21 configured as described above is capable of shifting in 24 steps forward and backward by combining respective gear sets. The reverse shift position may be configured such that, for example, the high speed position is cut to reduce the number of steps.

  The rotational power transmitted to the output shaft 45 is transmitted to the left and right rear wheels 2R via the rear wheel differential mechanism 46, and the front wheel speed increasing device 48 and the front wheel differential mechanism 49 are transmitted via the front wheel power branch gear 47. Via the front wheel 2F.

  The front wheel drive shaft 7 that receives power from the front wheel power branch gear 47 is provided with a rear wheel rotation sensor 8 to detect the rotation output from the main auxiliary transmission by the sensor 8, or the transmission gear is When it is not in the position, it is configured to detect the rotation of the running wheel from the traveling wheel side.

  The left and right drive shafts output from the rear wheel differential mechanism 46 are each provided with a disc-type brake device 50, and the left and right brake pedals are depressed or the brake hydraulic cylinders 9L and 9R are driven. The rear wheels 2 </ b> R and 2 </ b> R are braked by pressing them independently or simultaneously on the left and right sides.

  The front wheel speed increasing device 48 is configured to switch the rotation transmitted to the front wheels 2F in conjunction with the turning operation of the tractor T from the constant speed to the double speed when the turning control on / off switch 23 is turned on. .

Next, the control system of the tractor T will be described with reference to FIG.
The control means 10 of the tractor T comprises a travel controller 10a and a work machine operation controller 10b, each of which has a CPU for processing information of various sensors and setting devices, a RAM for temporarily storing the information, and the present invention. It has a configuration in which a ROM for storing a control program for the gear shift control and a timer are stored.

  The travel controller 10a includes a shift up switch 20A, a shift down switch 20B, a shift lever position sensor 20s, an accelerator position sensor 35, an engine rotation sensor 36, an accelerator pedal position sensor 1s, and a rear wheel rotation sensor. 8. Potentiometer-type main shift position sensors 6A and 6B for detecting shifter positions of the shift hydraulic cylinders 5A and 5B, and pressure sensors 55 for the Hi clutch Ch and Lo clutch Cl provided in the oil passage of the first main transmission 3a. , 56 are provided.

  The output section includes a solenoid 66 for a switching control valve for communicating pressure oil to the Hi clutch, a solenoid 67 for a switching control valve for communicating pressure oil to the Lo clutch, and a proportional pressure control valve for boosting the forward / reverse switching device 41. Solenoid 57, solenoids 60, 61, 62, 63 for switching control valves for driving the shift hydraulic cylinders 5A and 5B to switch the second main transmission 3b from the first speed to the fourth speed position, the left rear wheel 2L and the right rear Solenoids 64 and 65 of a proportional pressure control valve for braking the wheel 2R are provided in a connected manner.

  Further, the work controller 10b is provided with a turning control on / off switch 23, a tilling depth setting device 24, a potentiometer 22s at the base of the position lever 22, a lift arm angle sensor 32s, and the like connected to the input unit, and an output unit. Solenoids 33 and 34 of a switching control valve for raising and lowering the work implement, a liquid crystal monitor 68, an alarm buzzer 69 and the like are connected.

In the tractor T configured as described above, the shift control by the accelerator pedal is performed as in the flowcharts showing the outline of the control shown in FIGS.
That is, it is determined whether or not the engine speed corresponding to the throttle position is output from the throttle position sensor and the engine rotation sensor. If this determination is YES, the main shift position is increased by one step from the current position. Further, in the determination of NO, if the rotational speed is still within a predetermined range, the current main shift position is maintained, and if it is below the predetermined value, it is determined that the load is high and the main shift position is determined as the current position. 1 step down from Fig. 6
Note that the shift control in FIG. 6 is performed at the road traveling speed (the sub shift H (high) speed in this embodiment), but the shift control based on the engine speed and the load state is performed based on FIG. .

  First, when the engine key switch is turned on for the tractor T and the power is turned on, the travel controller 10a reads the states of the sensors and operation switches, and stores the shift positions of the main and auxiliary transmissions and the engine speed. . When the accelerator pedal 1 is stepped on, it is determined by means such as map processing whether the shift position can be increased or decreased depending on the engine speed and the load state (steps 101 to 104).

  If the automatic shift output is ON according to the determination, it is determined whether the shift is performed by the shift hydraulic cylinders 5A and 5B, that is, when the auxiliary transmission 21 is set to L speed, In this case, the speed is changed from the second speed to the third speed, from the fourth speed to the fifth speed, from the sixth speed to the seventh speed, and so on. It is determined whether or not the speed is changed from the fourth speed to the fourth speed and from the third speed to the second speed (step 106). Then, if the determination in step 106 is YES, it is subsequently determined whether or not the current shift operation is in progress (step 108). If this determination is YES, the shift instruction is canceled and other processing is performed. To return.

Thereby, after completing one shift operation, a new shift is performed, and it is possible to prevent a plurality of shift stages from being skipped and the vehicle speed from being changed abruptly.
Further, when the determination in step 108 is NO, that is, when it is determined that the shift operation is not currently performed, the current shift position is stored, and the control valve of the forward / reverse switching device 41 is energized. Stop and cut the clutches Cf and Cr. Then, a timer in the controller is operated to drive the hydraulic cylinder according to each shift position.

  Further, there is a case where the vehicle speed is changed by the accelerator according to the field condition while the accelerator operation is performed in the throttle half-open state such as a scraping operation. In such a case, when the vehicle is automatically decelerated, there is a problem that the gear shift is contrary to the intention of the operator who changes the vehicle speed by the accelerator. Therefore, when it is determined in step 104 whether or not acceleration / deceleration is to be performed, automatic acceleration / deceleration is not performed during the accelerator operation by the operator. For the same reason as described above, automatic acceleration / deceleration is not performed when the accelerator operation position is not equal to or greater than the specified rotation instruction. This is also because the shift may occur contrary to the operator's intention, and at the same time, it is difficult to determine the load factor because it is less than the prescribed rotation. It should be noted that, by setting a configuration in which the shift operation is prohibited not only during the accelerator operation but also during the operation, this can be solved even if a delay time occurs in the follow-up of the engine speed.

  Next, the main shift control at the working speed at the sub-shift L and M speed will be described. For example, the rotary work in which the traction resistance is not large is performed at the low speed stage and the main transmission apparatuses 3a and 3b are mainly operated at "2 to 4 speeds", but the plow work in which the traction resistance is relatively large is performed. Is the low speed stage, and the main transmissions 3a and 3b are mainly operated at "1 to 2 speed". Thus, even if the sub-shift shift position is the same, the shift positions of the main transmissions 3a and 3b that are frequently used differ from work to work. For example, after the sub-shift is switched to low speed (L), the main shift device can be switched by the controller 10a. The shift position of the shift shifts, and the operation of the increase / decrease shift switches 20A and 20B is required again.

  Therefore, when the auxiliary transmission 21 is switched, the following configuration is adopted in order to reduce the subsequent operation of the increase / decrease shift switches 20A and 20B. That is, as shown in the flowchart of FIG. 8, the main shift shift positions of the main transmissions 3a and 3b are accumulated for each work mode and for each sub shift shift position of “L”, “M”, and “H”. The usage time is counted (FIG. 9), and when the auxiliary transmission 21 is operated, it is immediately output to the main transmission shift position having the longest usage time at the auxiliary transmission shift position after the lever 20 is operated. Therefore, the controller 10a is provided with a memory M for storing a main shift position. The memory M may be a separate memory for each work mode, or a separate memory area for storing the main shift shift position for each work mode may be provided in a single memory.

  In this way, by providing the memory M for storing for each work mode and for each sub shift shift position, for example, in the rotary work (depth mode) and the plow work (draft mode), each work mode can be supported. Since the main shift shift position in the vehicle speed range can be stored, it is possible to work in the vehicle speed range suitable for each. The flowchart of FIG. 9 shows a storage procedure when, for example, a rotary work is selected.

  Note that FIG. 10 shows an example of data on the cumulative use time of the main shift shift position for traveling, and it is the most used in the previous work every time the sub-shift is switched to L (low) speed or M (medium) speed. Shift control is performed to an initial position, which is a shift position having a long accumulated time, and the accumulated time of the work is stored in a memory and is immediately switched to the shift position having the longest accumulated time when the sub-shift is switched.

  FIG. 11 relates to the improvement of the shift control based on the accumulated work time in which the main shift shift position is stored and immediately set to the shift position at the next work. During work on the field such as rotary tillage work, when the engine load is detected and it is judged that the load is large, it automatically performs deceleration control, and conversely, load control that automatically increases speed control when the load is reduced is executed. Configure accordingly.

  That is, it is determined whether or not the auxiliary transmission 21 is at the road running position and whether or not it is immediately after the shift (steps 202 and 203). Here, immediately after the shift, the main shift is shifted to the memory position corresponding to the sub-shift position, and this shift position is set as the highest shift position of the automatic shift during this work (step 204).

  Thereafter, the main shift position is counted every predetermined short time (for example, 1 minute) and stored in the storage unit (step 206). Here, it is determined whether or not the maximum shift position count position is different from the current memory position (step 207). If different, the memory position of the current sub-shift position is changed (step 208).

Further, whether or not there is a manual shift is determined, and when the manual shift is performed, the manual shift position is changed to the highest shift position of the automatic shift (steps 209 and 210).
The above-described preparation is made, and the shift control is performed by the load during work. At the same time, the engine load factor is measured from the engine throttle opening and the actual engine speed (step 211). When the measured engine load ratio is greater than a predetermined value for a predetermined time or longer (step 212), the main shift is automatically controlled by one speed reduction (load automatic deceleration control), and the load decreases. Even if the specified time is not allowed to increase, the specified time is not allowed. The load factor at this time is stored in the storage means (step 213).

  In step 212, the engine load factor does not continue for a specified time or more, and there is a margin in the engine load (step 214). The engine is decelerating due to the large load (step 215). If it is determined (step 216), an automatic speed increase instruction is given (step 217).

  When deceleration is not being performed in step 215, it is determined whether or not there has been a change from a heavy load state without a shift (step 218). If so, the tractor is forcibly only the rear wheels. The slip ratio in the driving 2WD state is confirmed (step 219). If the slip is large (step 220), the front wheel is also driven to a 4WD state, and the main shift is decelerated (step 221).

  In the case of performing the above configuration / action, the following effects are obtained. First, in step 205, if the memory position is set to the highest speed during the operation and the main shift is increased or decreased according to the engine load fluctuation, the deceleration process is automatically performed when the load increases at the speed at which the operator wants to work. However, when the load is reduced, the original speed stage is restored, and frequent button switch operations are unnecessary even during work.

  Further, in the above, when shifting from the memory shift position by manual operation to the speed increasing side, the main shift is increased or decelerated in accordance with the engine load fluctuation with the shift position as the highest position (steps 209 and 210). The intended acceleration / deceleration sensation becomes possible.

  Further, during the operation, the uppermost speed is set on the upper side of the memory position. With this configuration, the operator's intended working speed can be obtained, and when the load is large, the speed is automatically decelerated, and when there is a margin, the speed can be increased to one step, thereby reducing manual shifting during work. , Improve work efficiency.

  When shifting to a position different from the memory shift position by manual operation, with the configuration in which the shift position is set to the highest speed and automatic acceleration / deceleration is performed according to engine load fluctuations, for example, if the work is changed from rotary tillage work to alternative harrow work, the work speed However, since the changed shift position is a shift position suitable for the operator, it is necessary to change the maximum shift position when the shift position is automatically increased or decreased by a load. With this configuration, automatic acceleration / deceleration control that matches the work speed intended by the operator can be performed.

  As described above, in the configuration in which the memory position is the highest speed and the main shift is increased / decreased according to the engine load fluctuation, the acceleration after the deceleration operation when the load factor is large is a specified time immediately after the deceleration. If the load factor is more than the determined load factor and the speed is increased when the load has continued for a specified time or longer, the speed increase operation is performed when the predetermined margin state continues, so that frequent acceleration / deceleration operations are eliminated.

  Automatic deceleration during work is configured to decelerate one step when the engine load is larger than a specified value for a specified time or longer (steps 212 and 213). Even if the engine speed changes temporarily, however, it will not decelerate and frequent acceleration / deceleration will be eliminated.

  As described above, the memory position is set to the highest speed, and the main shift is increased or decreased according to the engine load fluctuation. The speed increase during work is performed when the engine rotation instruction is equal to or higher than the specified rotation. (Step 217), it is possible to increase the speed only when the engine speed instruction that can be increased is instructed, and depending on how the engine load factor is detected, the engine is immediately stalled due to the increased speed. Or a problem such as a command to instruct deceleration is issued immediately.

  In a configuration in which acceleration / deceleration is performed by changing the load during work, when the engine load changes when the speed is not changed to a direction in which a sufficient margin is generated in the load, the front wheel drive is temporarily turned off (2WD) and the rear wheels It is determined whether or not the vehicle is slipping, and if the slip is determined, the travel shift can be decelerated one step (steps 218 to 212). Although this load will be small, if left as it is, slip will become large and it will be difficult to continue the work, but by judging the slip and decelerating it, it will be efficient without putting an extra burden on the operator Work can be continued.

Next, the improvement of the shift control based on the load during work will be described.
During tractor operations, some tractors with an automatic transmission control mechanism are subjected to automatic transmission control so that a predetermined transmission position is obtained in accordance with load fluctuations and throttle opening. Since such shift control includes control on the speed increasing side, there is a risk that gear shifting control to the speed increasing side unintended by the operator may be performed unexpectedly.

  FIG. 13 shows an example thereof. For example, it is assumed that the tractor T in field work is provided with automatic shift control means by engine load control. A GPS positioning sensor 80 for receiving position information transmitted from a GPS satellite is mounted on the tractor T, and means (controller 10a) for inputting the field position information of the traveling tractor based on the position information and the field map information. And means for determining whether or not the current position of the tractor is the end of the field. In FIG. 13, after the key switch is turned on, the controller 10a determines whether or not the automatic shift operation mode is selected. If the operation is automatic operation, the current position information is acquired by the GPS positioning sensor, while the field currently being worked on. Field map information is obtained (steps 301 to 304). In this way, it is determined whether or not it is at the end of the field (step 305). If it is at the end of the field, the control to the speed increasing side of the shift by the engine load control is restricted and the current shift position is determined. Are confirmed (steps 306 and 307). If the result of step 307 indicates that the vehicle is at the highest acceleration / deceleration position, the main shift is lowered by one step (steps 308 and 309). If it is determined NO in step 308, a shift by manual operation is possible, and consideration is given to compensate for a reduction in work efficiency associated with automation, and an automatic deceleration instruction at the time of rotating tillage is prohibited.

  In addition, 81 is a gyro sensor and can recognize the direction of the tractor T. The GPS positioning sensor 80 and the gyro sensor 81 are mounted in the vicinity of the liquid crystal display panel 82, and information from the GPS positioning sensor 80 and additional field map information are separately obtained by a controller (not shown) built in the back surface of the display panel 82. And the position of the tractor T in the field is displayed on the liquid crystal display panel 82 surface. The operator performs the tilling work and the like while confirming the liquid crystal display, and automatically calculates the distance from the end of the field set in advance on the map information while automatically recognizing the position information of the tractor T in the field. In this configuration, the process of step 305 can be executed.

  As described above, a GPS positioning device that receives position information transmitted from a GPS satellite is mounted on a tractor, and the tractor includes means for inputting field position information of a traveling tractor based on the position information and field map information. Is configured to determine whether or not the current position is the end of the field, and the speed-up side shift control is not performed at the end of the field, thereby preventing unexpected speed increase control. In addition, safety can be ensured without colliding with structures such as concrete ridges and drain pipes.

In addition, the forced deceleration configuration at the end of the field is unsuitable for skilled operators, but it is possible to prohibit a deceleration instruction at the time of plowing as in step 308, so that the work efficiency is not lowered easily.
Further, the example shown in FIG. 14 is provided with a traction load detecting means during the plowing operation to be pulled to the rear part of the tractor T so as to efficiently perform the shift control.

  In FIG. 14, when the automatic speed change operation is started, each detection value is input by the wheel rotational speed detection means and the traction load detection means (steps 401 to 404). When the traction load decreases and the wheel rotation speed increases (steps 405 and 406), the respective rates of change are then obtained. When it is determined that the traction change rate α is large compared to the predetermined value α0 set in advance and the rotation change rate β is large compared to the predetermined value β0 (step 407), the slip state is determined. The estimated main shift is decelerated by one step (step 408). If NO is determined in step 407, and the traction change rate α is less than the predetermined value α0 and the rotation change rate β is less than the predetermined value β0 (step 409), the shift is rather increased because it is not a slip state. (Step 410).

  In step 407 described above, the traction load increases on the uphill during the plowing operation, and if the slip increases, the traction force decreases conversely and proper traction cannot be performed. By carrying out deceleration control before falling into such a slip state, the traction force is secured and the operation is continued. Moreover, in said step 409, since load becomes light gradually and the margin has come out in traction force, work efficiency can be improved by increasing speed.

  In the determination from the state of step 409, if the accelerator operation opening is near the maximum and the engine load factor is equal to or greater than the specified value, the shift prohibition is canceled and the operation to the deceleration side is configured. Thus, since the operator's intention to achieve the maximum capacity is a situation in which the load must be greatly decelerated, by allowing only the deceleration, it is not necessary to cause a situation such as an engine stall.

The power transmission mechanism diagram of a tractor. The whole tractor side view. The perspective view which shows the cockpit seat part of a tractor. The figure which shows the relationship between each shifting position and the operating position of an actuator. The figure which shows the connection state of a controller. flowchart. flowchart. flowchart. flowchart. The graph which shows an example of accumulation time. flowchart. The liquid crystal display panel part front view. flowchart. flowchart.

Explanation of symbols

E engine T tractor 1 accelerator pedal 3 second main transmission 5A “3-4 speed” shifting hydraulic cylinder 5B “1-2 speed” shifting hydraulic cylinder 10 control means 21 auxiliary transmission

Claims (4)

 The cumulative use time of the main transmission shift position of the main transmission (3) is counted for each auxiliary transmission shift position, and when the auxiliary transmission (21) is operated, the auxiliary gear after the operation of the transmission lever (20) is performed. In a tractor shift control apparatus provided with a controller (10a) that immediately outputs to a main shift shift position having the longest use time at the shift shift position, the engine having the longest use main shift shift position as the highest speed engine. A tractor shift control device that performs image deceleration control of the main transmission (3) in accordance with load fluctuations.   When shifting to the speed increasing side from the main shift shift position having the longest usage time by manual operation, the main transmission (3) is configured to increase / decrease the speed according to the engine load variation with the shift position as the highest position. The tractor shift control device according to claim 1.   The tractor shift control apparatus according to claim 1 or 2, wherein the uppermost speed is set to the uppermost side of the main shift shift position having the longest use time during work.   In the structure in which the main transmission shift position with the longest use frequency is set to the highest speed and the main transmission (3) is increased or decreased according to the engine load fluctuation, the acceleration after the deceleration operation is performed when the load factor is large. 3. The tractor speed change control device according to claim 1, wherein the tractor speed change control device is configured to increase the speed when the load factor is more than the determined load rate immediately after the deceleration and continues for more than the specified time.

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