JP2007292168A - Vehicle speed control device for tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and easily set an appropriate vehicle speed control target speed depending on a sub shifting operation position for smooth auto cruise travel. <P>SOLUTION: A first means controls the angle of a trunnion shaft 1 of an HST to be kept at a set angle and sets the set angle depending on the shift position of a sub transmission device 2. A second means controls the angle of the trunnion 1 of the HST to keep a vehicle speed at a set vehicle speed and sets the set vehicle speed depending on the shift position of the sub transmission device 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle speed control device for a tractor.

A tractor having an HST is known to travel by adjusting a trunnion shaft by stepping on an HST pedal and controlling the vehicle speed continuously (see, for example, Patent Document 1).
JP-A-5-106731254541 (first page, FIG. 1).

  When working with a working device mounted on a tractor, it may be desirable to keep the working vehicle speed at the same vehicle speed as the previous work and repeat the work. Moreover, the vehicle speed varies depending on the type, form, load, etc. of the work implement. However, the tractor is equipped with a sub-transmission device, and the presence of this sub-transmission device complicates the constant maintenance setting of the vehicle speed (auto-cruise) or the speed change operation.

  According to the first aspect of the present invention, the angle of the HST trunnion shaft (1) is controlled to be maintained at the set angle, and the set angle is set according to the shift position of the auxiliary transmission (2). It is set as the structure of the vehicle speed control apparatus of the tractor characterized by these. The HST is driven at a predetermined traveling vehicle speed by the HST motor being driven by the hydraulic pressure of the HST pump according to the angle of the trunnion shaft 1 and being driven for transmission. At the time of auto-cruise setting, the position of the trunnion shaft 1 is set to the angular position at the time of the previous traveling and the set angle is maintained. At this time, when the driver operates the auxiliary transmission 2, the setting angle of the trunnion shaft 1 is controlled to rotate to the angular position of each other trunnion shaft 1 corresponding to each transmission position of the auxiliary transmission 2. Thus, this angle is maintained and controlled.

  The invention according to claim 2 controls the angle of the trunnion shaft (1) of the HST to maintain the vehicle speed at the set vehicle speed, and sets the set vehicle speed according to the shift position of the auxiliary transmission (2). It is set as the structure of the vehicle speed control apparatus of the tractor characterized by the above. At the time of auto cruise setting, the trunnion shaft 1 is controlled to rotate so as to maintain a constant set traveling vehicle speed. At this time, when the driver operates the auxiliary transmission device 2 to change the auxiliary transmission position, the rotation speed of the trunnion shaft 1 is controlled so that the set vehicle speed set for each auxiliary transmission position is maintained. Be controlled.

  According to the first aspect of the present invention, when the automatic cruise is set, the angular position of the trunnion shaft 1 is set and maintained for each shift position of the sub-transmission device 2. In addition, an appropriate control target angle of the trunnion shaft 1 can be set accurately and easily, and smooth auto-cruising can be performed.

  According to the second aspect of the present invention, since the vehicle speed set for each shift position of the auxiliary transmission device 2 is maintained at the time of auto-cruise setting, an appropriate vehicle speed control target corresponding to the artificial operation selection of the auxiliary transmission device 2 is maintained. The speed can be set accurately and easily, and a smooth auto cruise can be performed.

  Based on the illustrated example, the tractor vehicle body in the riding mode has front and rear wheels in conjunction with the HST (hydrostatic continuously variable transmission), the forward / reverse switching device 4, the auxiliary transmission 2 and the like by driving the engine 3. 6 is configured to drive four wheels. A work machine can be attached to the front or rear of the vehicle body for work. The HST has a variable displacement type HST pump driven by the input shaft 7 and a fixed displacement type in which the output shaft 8 is linked. The HST motor is arranged in a closed hydraulic circuit, and the inclination of the swash plate that is rotated by the trunnion shaft 1 is inclined. By changing the angle, the operating amount of the HST pump guided thereby is changed to change the transmission speed of the HST motor. This shift can be performed in a stepless manner from the neutral position to the high speed position by stepping on the HST pedal 10. The pedal position sensor 11 detects the depression amount of the HST pedal 10, and the trunnion shaft 1 is rotated via the electric motor by the detection of the position sensor 11, and is rotated to an angular position corresponding to the depression amount. The HST pump by the input shaft 7 is driven. The rotation angle of the trunnion shaft 1 is detected by the trunnion position sensor 14, and feedback control is performed so that the trunnion shaft 1 is accurately rotated according to the amount of depression. The auxiliary transmission 2 receives the transmission of the output shaft 8 output from the HST, shifts the gear to the low speed position L, the medium speed position M, or the high speed position H and transmits it to the differential gear 9 to transmit the wheels 6. To drive. The forward / reverse switching device 4 can be switched between the forward position 16F and the reverse position 16R by operating the switch 16 with the forward / reverse switching lever 24.

  The HST shifting operation by the HST pedal 10 is detected by the pedal position sensor 11 by detecting the depression amount of the pedal 10, and the trunnion shaft 1 is rotated by the trunnion output 13 from the controller 12, so that the HST continuously variable transmission is performed. I do. The rotation angle of the trunnion shaft 1 is detected by the trunnion position sensor 14 to perform feedback control. The trunnion output 13 is provided with a trunnion forward rotation relay 13F for forward rotation of the trunnion shaft 1 to the forward side and a reverse relay 13R for reverse rotation to the reverse side. Further, on the input side of the controller 12, there are an auto cruise switch 15 for setting auto cruise, switch switches 16F and 16R for switching the traveling direction of the vehicle body between the forward side and the reverse side, a vehicle speed sensor 17 for detecting the vehicle speed, In addition, a memory 1 switch 18 and a memory 2 switch 19 that can store a plurality of rotational angle positions of the trunnion shaft 1 are arranged. These storage 1 switches 18 are used to set the target control angle of the trunnion shaft 1 for working in a low vehicle speed range as in the front loader work in a plurality of areas. Can be stored and set as positions L1, M1, and H1. The storage 2 switch 19 sets a target control angle of the trunnion shaft 1 for working in a relatively high vehicle speed range such as plow work in a plurality of storage areas, and stores it in the sub-transmissions L, M, and H. 2 is stored and set as positions L2, M2, and H2. These target control angles are feedback-controlled by detection of the trunnion position sensor 14. Further, the controller 12 is provided with an auto cruise 1 switch 20 and an auto cruise 2 switch 21 so as to control the storage area at the location of the memory 1 and the storage area at the location of the memory 2 according to the auto cruise control conditions. Is selected and switched. Further, a sub-transmission sensor 22 that detects a shift position of the sub-transmission device 2 and a forward / reverse sensor that detects whether the trunnion shaft 1 is rotated from the neutral position N to the forward position F side or the reverse position R side. 23 etc. are arranged.

  As a general tractor working vehicle speed, the low speed position L of the sub-shift position is set to snow removal work or lawn mowing work, the medium speed position M is set to lawn mowing work or towing work, etc., and the high speed position H is set on the road Although it is set at the time of traveling or the like, in a specific work, for example, a plow work may be performed also in the auxiliary transmission H2, L2, and M2. In addition, since the front loader or the like may perform even at the high speed position H1 than the auxiliary gear shifts L1 and M1, the angle value of the control target of the trunnion shaft 1 for each of the auxiliary gear shift positions L, M, and H is set in advance. Or, it is set by the switches 18 and 19 while performing the work.

  Here, the vehicle speed control device according to the present invention controls the angle of the HST trunnion shaft 1 to be maintained at a set angle, and sets the set angle in accordance with the shift position of the auxiliary transmission 2. is there. The HST is driven at a predetermined traveling vehicle speed by the HST motor being driven by the hydraulic pressure of the HST pump according to the angle of the trunnion shaft 1 and being driven for transmission. At the time of auto-cruise setting, the position of the trunnion shaft 1 is set to the angular position at the time of the previous traveling and the set angle is maintained. At this time, when the driver operates the auxiliary transmission 2, the setting angle of the trunnion shaft 1 is controlled to rotate to the angular position of each other trunnion shaft 1 corresponding to each transmission position of the auxiliary transmission 2. Thus, this angle is maintained and controlled.

  If the sub-shift is selected to the low speed L, medium speed M, or high speed H position during work travel and the memory 1 switch 18 or memory 2 switch 19 is pressed to turn it on (main routine A1 in FIG. 4), these work travel conditions , And on the basis of setting software for the constant reference control target value, detected angle values L1, M1, H1, L2, M2, and H2 by the trunnion position sensor 4 as shown in FIG. 2 are stored in the memory as shift values. Then, the stored angle value becomes the control target reference angle value at the time of auto-cruise setting for the subsequent work travel. This angle value is set for each of the sub-shift positions L, M, and H by performing the sub-shift operation. In addition, the auxiliary shift positions L, M, and H are set for each of a plurality of storage areas. Further, since the shift values L1, M1, H1, L2, N2, and H2 are often set for each work, not all shift angle values are always set.

  When the angle value serving as the control target reference is set in this way, the auto cruise switch 15 is turned on, so that the auto cruise 1 switch 20 or the auto cruise 2 switch 21 is turned on as in the main routine A2 of FIG. Turn on. When the auto cruise 1 switch 20 is turned on, the rotation control is performed so as to maintain the angle value of the trunnion shaft 1 set by the memory 1 switch 18, and when the memory 2 switch 21 is turned on, the memory 2 switch 19 is set. Control to maintain the angle value. Then, the angular position of the trunnion shaft 1 corresponding to the current auxiliary transmission position is controlled and maintained. When the reverse sensor 23 detects the neutral position N or when the auto-cruise 1 switch 20 and the auto-cruise 2 switch 21 are OFF, the trunnion shaft 1 is operated to the neutral position (stop) as in subroutine B1 of FIG. Or operated to the operation position by the HST pedal 10.

  The auto-cruise 1 switch 20 and the auto-cruise 2 switch 21 are operated by the driver to select a low-speed area storage angle value or a high-speed area storage angle value at the same auxiliary shift position. Although the switch 18 and the storage 2 switch 19 are selected as a low-speed and high-speed two-layer area, this may be, for example, a low-, medium-, and high-speed three-layer area. In this case, a memory 3 switch is provided. It is also possible to store the angle values over various operations and register and set the angle values of all the areas by the switches 18 and 19 for each of the sub-shift positions L, M and H.

  Further, based on FIGS. 1, 5, and 6, instead of storing the angle of the trunnion shaft 1, auto cruise is performed by storing the actual traveling vehicle speed. The angle is controlled to maintain the vehicle speed at the set vehicle speed, and the set vehicle speed is set according to the shift position of the auxiliary transmission 2. At the time of auto cruise setting, the trunnion shaft 1 is controlled to rotate so as to maintain a constant set traveling vehicle speed. At this time, when the driver operates the auxiliary transmission device 2 to change the auxiliary transmission position, the rotation speed of the trunnion shaft 1 is controlled so that the set vehicle speed set for each auxiliary transmission position is maintained. Be controlled.

  Also in this vehicle speed storage mode, the auto cruise control is performed as shown in FIG. 6 and is performed in substantially the same manner as the angle value storage of the trunnion shaft 1. By storing the actual vehicle speed in this way, the vehicle speed value is used as a reference value for the control target, so that auto-cruise control is performed, so that a constant vehicle speed can always be maintained even when the vehicle speed tends to fluctuate on a slope. .

  Next, based on FIG. 7, the angle value or the vehicle speed value of the trunnion shaft 1 is stored in each storage area even when the work is performed while the tractor moves backward R by operating the reverse switch 16R. The auto cruise setting can be performed while the stored values are called by the auto cruise switches 18 and 19. In the case of working while frequently repeating forward and backward as in the lawn mowing work, the efficiency of the work can be improved by setting the auto cruise even during the backward movement.

  Next, mainly based on FIGS. 8 to 10, when the forward / reverse switching lever 24 is switched to the reverse position R during forward travel in the automatic cruise setting, the trunnion shaft is moved backward to the vehicle speed when traveling forward by the automatic cruise. 1 is configured to be driven. Further, when the forward / reverse switching lever 24 is operated to the forward position F, the trunnion shaft 1 is driven forward to the previous vehicle speed again. When working while frequently repeating forward and reverse, there is no need to operate the auto-cruise switch every time forward and reverse are switched, and it is possible to travel at a constant vehicle speed set for auto-cruise at the same vehicle speed for both forward and reverse. The operation can be made simple and easy.

  When the auto cruise switch 15 is turned on during work travel, the angle value of the trunnion shaft 1 at this time is stored in the memory as in the main routines A1 and A2 of FIG. Then, auto-cruise control during forward travel is performed. At this time, if the flag during auto-cruise control is reset or the flag is OFF, the trunnion shaft 1 is rotated to a position corresponding to the amount of depression of the HST pedal 10 as in subroutine B1 of FIG. Further, when the forward / reverse switching lever 24 is switched to the reverse position R, if the PTO switch 25 is turned on as in the subroutine B2 of FIG. 9, the vehicle speed is maintained at the same vehicle speed as that stored as described above. The trunnion shaft 1 is controlled to rotate. At this time, the auto-cruise can be set so that the reverse side vehicle speed is a constant amount or a constant vehicle speed that is slower than the forward side vehicle speed. On the other hand, in switching the auto cruise from the reverse side vehicle speed to the forward side, the auto cruise is set so that the vehicle speed becomes high at a constant amount or at a constant rate. At this time, such an auto-cruise setting is made possible when the PTO switch 25 is turned on and the PTO clutch is engaged. When the forward / reverse switching lever 24 is set to the neutral position N and the reverse position R and then set to the forward position F again, the speed is automatically increased, or the speed is automatically increased when the reverse position R is set. In some cases, there is a danger, so that the safety is assumed to be performed while the PTO switch 25 is turned on.

  Next, mainly based on FIGS. 11 to 13, in the tractor that drives the HST trunnion shaft 1 according to the depression amount of the HST pedal 10, the pulse output of the trunnion drive motor is determined from the output pulse length of the normal driving. To shorten the shock when starting. In FIG. 11, when the trunnion shaft 1 transmits from the neutral position N (vehicle speed 0 km / h), only the first predetermined number of pulses (for example, 3 pulses) are output to the trunnion drive motor. It is configured to output at a half speed of time and start at a slow speed. When the vehicle starts from a stop state, the pulse ON time (10 ms) is long at the normal pulse output length, so the start shock is large and uncomfortable, but this ON time is halved (1/2 × 10 ms) Make a smooth start.

  In FIG. 12, the output to the trunnion drive motor is performed for half the original pulse output ON time, and when the vehicle body starts moving, the pulse output is performed as usual. Further, in FIG. 13, when the output to the trunnion drive motor is completed after a certain time (for example, 3 seconds) has elapsed after the completion of the output to the trunnion drive motor, only the first three pulses are the original pulse output ON time. The output is half the length of. When starting, when suddenly increasing / decelerating, or when increasing / decreasing with an acceleration / deceleration switch during auto-cruise traveling, smooth start / acceleration / deceleration can be performed.

  Next, mainly based on FIG. 14, in the configuration in which the trunnion shaft 1 of HST speed change is driven by the trunnion drive motor and the trunnion shaft 1 is mechanically driven to the neutral side by the brake operation, the brake sensor is turned on. Also, when in a special mode, it is configured to switch to a state where trunnion drive output is performed. When the brake ON signal is input, the trunnion shaft 1 is automatically returned to the neutral position, so that the drive output of the trunnion shaft 1 is not performed. However, in a special mode, even if the brake signal is ON, the trunnion drive output is performed, so that it is possible to run the machine even if the brake sensor fails.

  Next, based on FIG. 15 and FIG. 16, a partially different example of auto-cruise control traveling will be described. In FIG. 15, when the machine is turned on and the vehicle speed is zero, when the auto cruise switch 15 is pressed, the auto cruise vehicle speed stored in the memory is called and read, and the trunnion shaft 1 is driven until this vehicle speed is reached. Thus, the vehicle is configured to perform auto cruise driving. By storing the driver's favorite auto-cruise speed in the memory, when the work is performed again at a later date, the work can be performed at the same auto-cruise speed as the previous time. In addition, auto-cruise traveling can be performed even when the vehicle speed is 0 (stopped).

  In FIG. 16, while the auto-cruise switch 15 is being pressed at a vehicle speed of 0, numbers at constant intervals are sequentially displayed on the monitor, and when the auto-cruise switch 15 is released, the displayed value is the target. The vehicle speed is set, the trunnion shaft 1 is driven until the target vehicle speed is reached, and the auto-cruise driving is performed when the target vehicle speed is reached. In addition, it is possible to easily select a preferred auto cruise speed.

  Next, partially different trunnion axis control will be described mainly based on FIGS. 17 to 19. The trunnion shaft 1 depends on the weight and size of the working machine even if the working machine is mounted on the tractor vehicle body that operates the position of the trunnion shaft according to the amount of depression of the conventional HST pedal. It is difficult to achieve the same vehicle speed even if the is operated at the same position. For this reason, in FIG. 17, in the tractor that performs travel control by driving the trunnion shaft 1 using HST as the transmission device, the target maximum vehicle speed is determined at the sub-shift H, and the target maximum vehicle speed and the trunnion shaft are determined. When the travel HST pedal 10 is depressed to the maximum at the sub-shift H speed, the trunnion shaft 1 is driven forward until the value of the vehicle speed sensor 17 reaches the target maximum vehicle speed, and the target maximum vehicle speed is reached. When reaching, the trunnion shaft 1 position is held. When the pedal 10 is depressed to the maximum at the sub-shift H speed, for example, if the performance of this machine is satisfactory, the request can be satisfied with respect to the request that the vehicle speed be 40 km / h.

  In FIG. 18, the target vehicle speed is determined according to the depression amount (%) of the pedal 10, and the trunnion shaft 1 is driven until the vehicle speed is reached. Even if there is a large change in the weight of the entire machine between when the work machine is worn and when it is not worn, the running is stabilized by positioning the trunnion shaft 10 at a vehicle speed corresponding to the position of the pedal 10. Further, since the trunnion shaft 1 is driven so as to reach the target vehicle speed in accordance with the position of the pedal 10, it is not necessary to adjust the reference value of the trunnion shaft 1 (the trunnion forward maximum position, the trunnion neutral position), etc. Will be less. As an example, the target maximum vehicle speed is set to 40 km / h, and this is calculated by multiplying the pedal depression amount (%) based on this vehicle speed.

  In FIG. 19, the trunnion shaft 1 is driven so that the target maximum vehicle speed (M speed) is obtained when the pedal 10 is stepped on to the maximum position at the sub-shift M, and the pedal 10 is stepped on to the maximum position at the sub-shift L. The trunnion shaft 1 is driven so that the target maximum vehicle speed (L speed) is output when Similarly, the sub-transmission H is configured such that the target vehicle speed is determined according to the depression amount (%) of the pedal 10 and the trunnion shaft 1 is driven until the vehicle speed is reached. The target maximum vehicle speed is set to 20 km / h for the sub-shift M and 10 km / h for the sub-shift L.

  Next, a mode in which the control of the trunnion shaft 1 is controlled when the linear lever 24 is moved to the reverse position and the sub-shift H is performed will be described mainly based on FIGS. In FIG. 20, in a mode in which the HST trunnion shaft 1 is driven by a motor to perform variable speed travel, the forward / reverse switching lever 24 (linear lever) for operating the forward / reverse switching switch 16 is put in the reverse position, When the vehicle speed at the time of reverse travel exceeds a constant speed (for example, 10 km / h), the trunnion shaft 1 drive position is restrained so as not to drive output to the reverse speed increase side from the present, and no further speed is generated. And

  In FIG. 21, when the linear lever 24 is put in the reverse drive position and the sub-shift H, the output pulse cycle to the trunnion shaft 1 drive motor is double the output pulse cycle at forward output speed increase. Thus, the duty ratio is shortened by increasing the OFF time, and the motor drive is controlled at a slow speed.

  Next, mainly based on FIG. 22, in the mode in which the shift control is performed by driving the motor of the HST trunnion shaft 1, a steering sensor for detecting the steering angle of the wheel (tire) 6 is provided, and the vehicle speed is a constant value (for example, In a situation where the vehicle is traveling at a high speed exceeding 10 km / h), the trunnion shaft 1 is decelerated and rotated at a slow speed when the angle of the wheel 6 is deviated from the neutral position by a certain angle (for example, 30 degrees) or more. It is what. Even if the wheels 6 are directed to the left and right during high-speed travel, the trunnion shaft 1 can be driven at a slow speed toward the deceleration side to decelerate and travel safely.

  Next, in the 4WS control in which the tractor wheel 6 (front wheel and rear wheel) travels mainly based on FIG. 23, the front wheel and the rear wheel are configured to be expanded and contracted by independent hydraulic cylinders. An angle sensor is provided, and this hydraulic cylinder is operated by the turning angle of the steering handle. At this time, the steering angle of the steering wheel and the steering angle of the wheel are not associated with each other, so that the shift is likely to occur. For this reason, when the steering wheel is set to the straight traveling state during traveling and when a deviation is detected, this is corrected. In this embodiment, it is dangerous to correct the steering angle deviation of the wheel 6 when the vehicle speed is at a certain level, such as when traveling on the road. Therefore, when the vehicle speed is equal to or higher than a certain value (for example, 10 km / h), the hydraulic pressure The correction by the valve switching provided in the hydraulic circuit of the cylinder is not performed, so that high-speed traveling or the like can be safely operated.

The block diagram of a vehicle speed control apparatus part. The graph which shows the rotation angle of the trunnion shaft by the auto cruise. The flowchart. The transmission route figure of a tractor. The graph which shows the vehicle speed by the auto cruise. The flowchart. The flowchart of the auto-cruise control at the time of advancing ahead. Block diagram of auto-cruise control with forward and reverse switching. The flowchart. The perspective view of the forward / reverse switching lever and the operating angle of the trunnion shaft. The flowchart of the output control of the trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of the output control of a trunnion drive motor. The flowchart of 4WS control.

Explanation of symbols

1 trunnion shaft 2 auxiliary transmission

Claims (2)

  A vehicle speed control device for a tractor, characterized in that the angle of the HST trunnion shaft (1) is controlled to be maintained at a set angle, and the set angle is set in accordance with the shift position of the auxiliary transmission (2). .   Controlling the angle of the HST trunnion shaft (1) to maintain the vehicle speed at a set vehicle speed, and setting the set vehicle speed in accordance with the shift position of the auxiliary transmission (2) apparatus.

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