JP2008267547A - Transmission control device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission control device of a working vehicle, capable of securing smooth transmission by preventing a transmission shock when normally operating a transmission lever, and also capable of securing readiness of a body operation against the rapid reverse travelling operation of a forward and backward movement switching lever. <P>SOLUTION: This transmission control device of the working vehicle is equipped with a control part 90 to control the operating rotation ratio of a continuously variable transmission mechanism 34 for forward and backward movement along a target rotation ratio corresponding to the operation of the forward and backward movement switching lever 10 and the main transmission lever 20. The control part 90 performs transmission control to change the operating rotation ratio to the target rotation ratio by a deviation corresponding change rate due to a change rate in accordance with a difference between the operating rotation ratio and the target rotation ratio, and only when the forward and backward movement switching lever 10 receives reverse travelling operation exceeding its neutral stop position, it performs transmission control at a rapid change rate set to a higher change rate exceeding the deviation corresponding change rate, as to a range to the neutral position of the forward and backward movement variable transmission mechanism 34. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shift control device for a work vehicle that performs vehicle speed control of a traveling transmission system by a forward / reverse continuously variable transmission mechanism by a forward / reverse switching lever and a main shift lever.

  As shown in Patent Document 1, a forward / reverse selection lever for selecting forward / reverse travel, a main speed change lever for selecting the vehicle speed of a work vehicle, and continuously moving forward / reverse travel speed according to the selected positions of both levers. 2. Description of the Related Art A work vehicle including a forward / reverse continuously variable transmission mechanism that is abbreviated as “HST transmission mechanism” is known.

This work vehicle can be switched to the vehicle speed intended by the operator according to the operation of the forward / reverse switching lever and the main transmission lever via the control unit that drives and controls the trunnion shaft that adjusts the rotation ratio of the HST transmission mechanism. In addition, a shift operation that limits the driving speed of the trunnion shaft prevents a shift shock even by a rapid lever operation, thereby enabling a smooth shift.
JP 2002-250437 A

  However, when the operator operates the forward / reverse switching lever to reversely move the aircraft, even if the operator suddenly performs the switching operation, the work vehicle continues inertial deceleration for a while until the aircraft stops. Since the gear is shifted in a pattern in which it gradually stops and then reverse operation is started and the speed is increased to the indicated speed, not only will the confusion be caused by the discrepancy between the lever operation and the aircraft operation, but the operator's There was a problem that the rhythm of a series of intended work was disturbed and the work efficiency was lowered.

  The problem to be solved is to prevent shift shock during shift by normal lever operation to ensure a smooth shift, and to respond quickly to rapid reverse switching operation of the forward / reverse switching lever An object of the present invention is to provide a shift control device for a work vehicle that can ensure the above.

  The invention according to claim 1 relates to the operation position of the forward / reverse switching lever (10) capable of selecting forward / backward and neutral stop positions and the main transmission lever (20) capable of selecting positions of a plurality of vehicle speeds. Shift control of a work vehicle having a control unit (90) for performing shift control of the travel transmission system by controlling the operation rotation ratio of the forward / reverse continuously variable transmission mechanism (34) in accordance with the target rotation ratio of the corresponding travel transmission system. In the apparatus, the control unit (90) controls the shift of the operation rotation ratio to the target rotation ratio by the deviation corresponding change rate according to the change rate according to the difference from the target rotation ratio, and the forward / reverse switching lever (10) is controlled. Only when a reverse operation exceeding the neutral stop position is received, the above-mentioned deviation can be accommodated for the range until the neutral operation that is zero transmission of the forward / reverse continuously variable transmission mechanism (34) is reached. Characterized by shift control in a rapid rate of change is set larger becomes the rate of change exceeds rate.

  When the shift control device for the work vehicle performs a reverse operation beyond the neutral stop position of the forward / reverse switching lever 10, the operation rotation ratio of the forward / reverse continuously variable transmission mechanism 34 is relatively controlled by the control unit 90 until the neutral operation is performed. Shift control is performed at a rapid change rate of a large change rate, the aircraft stops, then reverse travel is started, and shift control is performed at a deviation corresponding change rate according to the difference from the target rotation ratio within a range that does not satisfy the rapid change rate The target vehicle speed is reached.

  The invention according to claim 2 relates to the operation positions of the forward / reverse switching lever (10) capable of selecting forward / backward and neutral stop positions and the main transmission lever (20) capable of selecting positions of a plurality of vehicle speeds. Shift control of a work vehicle having a control unit (90) for performing shift control of the travel transmission system by controlling the operation rotation ratio of the forward / reverse continuously variable transmission mechanism (34) in accordance with the target rotation ratio of the corresponding travel transmission system. In the apparatus, the control unit (90) controls the shift of the operation rotation ratio to the target rotation ratio by a deviation-corresponding change rate according to a change rate according to a difference from the target rotation ratio, and the target rotation ratio is set to be in a deceleration direction. Only when the speed change control is performed with a rapid change rate set to a large change rate exceeding the deviation-corresponding change rate, and the operation rotation ratio is set to a predetermined value before the target position in the deceleration direction. Characterized by shift control to the target speed ratio by deviation corresponding rate of change due to the change rate corresponding to a difference between the target rotation ratio.

  In the above-described shift control apparatus for a work vehicle, the deceleration of the traveling vehicle body is operated in response to the lever operation in the range up to the vehicle speed corresponding to the predetermined residual in the deceleration process.

  According to the first aspect of the present invention, the operating speed ratio of the traveling transmission system to the target speed ratio corresponding to the vehicle speed of the operation position of the forward / reverse switching lever 10 and the main speed change lever 20 is changed according to the difference from the target speed ratio. By configuring the forward / reverse continuously variable transmission mechanism 34 to perform shift control according to the deviation-corresponding change rate due to the deviation, smooth shift control can be ensured when the main shift lever 20 is operated. When the switching lever 10 is reversely operated rapidly, the airframe travel is suddenly stopped in response to the lever operation without inertia of the airframe, and then the vehicle speed is increased with a relatively smooth change to the target vehicle speed when the reverse operation is started. Therefore, the rapid forward / reverse switching operation in accordance with the operator's intention is possible by the sudden stop without a sense of incongruity and the subsequent smooth reverse acceleration.

According to the second aspect of the present invention, the operating rotation ratio of the traveling transmission system corresponding to the vehicle speed at the operation position of the forward / reverse switching lever 10 and the main transmission lever 20 is changed according to the difference from the target rotation ratio. By configuring the forward / reverse continuously variable transmission mechanism 34 to perform shift control according to the deviation-corresponding change rate due to the deviation, smooth shift control can be ensured when the main shift lever 20 is operated. During processing, the vehicle speed is increased according to the difference to the target vehicle speed, and during deceleration processing, the vehicle is decelerated to the target vehicle speed at the rapid change rate.
Therefore, the speed increasing operation can prevent the gear shift shock even by a rapid lever operation and ensure a smooth gear shifting, while the deceleration operation is decelerated without inertia traveling in accordance with the lever operation. The same effect as described above can be obtained for the rapid operation of the advance switch lever 10.

  Embodiments specifically configured based on the above technical idea will be described below with reference to the drawings. In this specification, the left and right directions in the forward direction of the work vehicle are referred to as left and right, respectively, the forward direction is referred to as front, and the reverse direction is referred to as rear.

A tractor will be described below as an example of a work vehicle.
1 is an overall side view, FIG. 2 is a plan view of the tractor of FIG. 1, FIG. 3 is a power diagram of the transmission of the tractor of FIG. 1, and FIG. 4 is a control block diagram of the transmission.

  The tractor shown in FIGS. 1 to 3 includes front wheels 2 and 2 and rear wheels 3 and 3 in the front and rear portions of the airframe, and appropriately reduces the rotational power of the engine 5 mounted on the front portion of the airframe by a transmission in the transmission case. Thus, the front wheels 2 and 2 and the rear wheels 3 and 3 are communicated.

  A steering handle 7 is supported on the handle post 6 at the center of the airframe, and a control seat 9 is provided behind the steering handle 7. Below the steering handle 7 is provided a forward / reverse switching lever 10 for switching the traveling direction of the airframe to the forward / backward direction. When the forward / reverse switching lever 10 is moved to the front side, the aircraft moves forward, and when it is moved backward, it moves backward. An accelerator lever 11 is provided on the opposite side of the forward / reverse switching lever 10 across the handle post 6, and an accelerator petal 15 and left and right brake petals 16 and 17 are disposed at the right corner of the step floor 13. A clutch pedal 19 is disposed at the left corner of the floor 13.

  A main transmission lever 20 that can select a gear position from 1st speed to 8th speed is located at the left front portion of the control seat 9, and an auxiliary transmission lever 21 that can select any one of low speed, medium speed, high speed, and neutral positions. A PTO speed change lever 23 is provided on the rear side, and further on the rear side thereof, from which 1st to 3rd speeds and a neutral position can be selected. Further, on the right side of the control seat 9, a position lever 24 for setting the height of a working machine (not shown), an automatic tilling depth lever 25 for automatically setting the tilling depth of the field, and behind these levers 24, 25 Is provided with a right-up switch 27 and a right-down switch 28, followed by an automatic horizontal switch 29 (on to keep the tractor's absolute horizontal position horizontal with respect to the horizontal plane of the earth, not horizontal with respect to the field scene). ) And a backup switch 30 (when the forward / reverse switching lever 10 is in the reverse position, the work machine raising link 31 raises the work machine) and a work machine (not shown) is located behind the machine body. The link 31 for connecting the two) is provided.

  FIG. 3 is a diagram showing a traveling transmission system of a tractor having a hydrostatic continuously variable transmission mechanism (forward / reverse continuously variable transmission mechanism) 34 according to this embodiment. The rotational power of the engine 5 is transmitted to the main clutch 32 that is operated by depressing the pedal-operated clutch pedal 19, and then transmitted from the hydrostatic continuously variable transmission mechanism input shaft 33 to the hydrostatic continuously variable transmission mechanism 34. . The hydrostatic continuously variable transmission mechanism 34 includes a hydraulic closed circuit 34c having a variable displacement hydraulic pump 34a and a constant displacement hydraulic motor 34b, and is introduced from an input shaft 33 of the hydrostatic continuously variable transmission mechanism 33. The hydraulic pump 34a is operated by motive power, and pressure oil corresponding to the inclination angle of the swash plate 34d provided in the hydraulic pump 34a is supplied from the hydraulic closed circuit 34c to the hydraulic motor 34b, and the travel output shaft 36 is supplied by the hydraulic motor 34b. To drive the power to the meshing transmission 38.

  The auxiliary transmission clutch 39 of the meshing transmission 38 is slidable to the left and right in FIG. 3, and when it is in the illustrated position, the power from the travel output shaft 36 is transmitted from the high-speed gear 42 via the gear 41 to the auxiliary transmission clutch. 39 is transmitted from the auxiliary transmission clutch 39 to the gear 45 of the transmission shaft 43, and the rotation of the transmission shaft 43 is driven through the deb unit 46 at the traveling speed of the auxiliary transmission high speed stage.

  Further, when the auxiliary transmission clutch 39 is moved to the right from the position shown in FIG. 3 and the auxiliary transmission clutch 39 is engaged with the gear 45 and the medium speed gear 47 of the transmission shaft 43, the power from the travel output shaft 36 is transmitted to the gear. 41 is transmitted from the gear 49 to the subtransmission clutch 39 through the gear 50, the gear 51, and the gear 47 sequentially, and further transmitted from the subtransmission clutch 39 to the gear 45 of the transmission shaft 43. The movement of the rear wheel 3 is driven at the traveling speed of the intermediate speed stage through the fat device 46.

  When the auxiliary transmission clutch 39 further moves to the right side and engages with the gear 45 and the low speed gear 55 of the transmission shaft 43, the power from the travel output shaft 36 is transferred from the gear 49 to the gear 56 via the gear 41, and further from the gear 56. Is transmitted to the gear 57, transmitted from the gear 55 coaxial with the gear 57 to the sub-transmission clutch 39, and further transmitted from the sub-transmission clutch 39 to the gear 45 of the transmission shaft 43. The rear wheel 3 is driven at the traveling speed of the sub-speed stage.

  Even if the sliding position of the auxiliary transmission clutch 39 is on the left or right side, the output from the transmission shaft 43 is transmitted to the front wheel output shaft 61 via the gears 53, 59, 60, etc. in order. At this time, if the hydraulic clutch 63 is connected, the front wheel 2 is driven together with the rear wheel 3 via the differential device 65, and if the hydraulic clutch 64 is connected, the front wheel speed is increased. It becomes. The hydraulic clutch 63 and the hydraulic clutch 64 are not connected at the same time, and if the hydraulic clutch 63 and the hydraulic clutch 64 are not connected together, only the rear wheel 3 is driven.

  On the other hand, power input from the hydrostatic continuously variable transmission mechanism input shaft 33 to the variable displacement hydraulic pump 34a is transmitted from the pump output shaft 66 to the PTO drive system. The PTO drive system includes a PTO forward / reverse clutch 67 and a PTO auxiliary transmission clutch 68. When the tractor travels on the road, either one or both of the clutches 67 and 68 are in an unconnected state to drive the work machine. The PTO drive system is not driven.

  When working with the work implement in the field, the accelerator lever 11 is pulled toward the operator side (front side) and the engine speed is set to the rated speed, or a constant speed from the rated speed to the maximum speed. The hydraulic continuously variable transmission mechanism input shaft 33 and the pump output shaft 66 rotate at a constant rotational speed. The state shown in FIG. 3 is a neutral state, and the PTO shaft 69 directly connected to the pump output shaft 66 rotates together.

  When the PTO forward / reverse clutch 67 is slid in the left direction in the figure, the PTO forward / reverse clutch 67 meshes with the gear 70 and the gear 71 of the PTO shaft 69, so that the power of the PTO shaft 69 is the gear 70, the PTO forward / reverse clutch 67, and the gear 71. , The PTO transmission shaft 75 is driven through the gear 71a, the gear 72, the gear 74, the gear 78, the gear 77, and the gear 76 sequentially (PTO reverse rotation). When the PTO forward / reverse clutch 67 is slid in the right direction in the figure, the power of the PTO shaft 69 drives the PTO transmission shaft 75 through the gear 70, the PTO forward / reverse clutch 67, the gear 73, the gear 77, and the gear 76 sequentially. (PTO normal rotation).

  The power from the gear 78 interlocking with the driving of the gear 74 integrated with the gear 72 is also transmitted to the PTO transmission shaft 75, and when the PTO auxiliary transmission clutch 68 is in the position moved to the left most from the illustrated position, the gear 79 and the gear The gear dock 81 is engaged with the gear dock 83 provided in the PTO auxiliary transmission clutch 68 via 80, and the PTO first speed is obtained by the PTO drive shaft 84. When the PTO auxiliary transmission clutch 68 moves left or right from the illustrated position, power is transmitted to the PTO auxiliary transmission low speed gear 85 or the PTO auxiliary transmission high speed gear 86 that meshes in each case, and the gear 85, gear 68a. When the power is sequentially transmitted to the PTO drive shaft 84, the PTO second speed is obtained, and when the power is sequentially transmitted to the gear 86, the gear 68b and the PTO drive shaft 84, the PTO third speed is obtained.

  The tractor having the above-described configuration depresses the clutch pedal 19 when traveling on the road, and sets the auxiliary transmission lever 21 to a position suitable for traveling on the road (basically, the high-speed position may be set to the medium-speed position or the low-speed position). Next, the main transmission lever 20 is moved to an arbitrary position. The main speed change lever 20 can be selected from a minimum speed of 1st speed to a maximum speed of 8th speed, but the basic speed when traveling on the road is 8th speed.

  Next, the forward / reverse switching lever 10 is moved forward or backward, and the engine pedal is increased by stepping on the accelerator pedal 15 while slowly releasing the clutch pedal 19 (with the main clutch 32 connected). At this time, even if the accelerator pedal 15 is fully depressed, the maximum speed is restricted to the position of the maximum speed stage (8th speed) of the main transmission lever 20.

  Further, when working in the field, after depressing the clutch pedal 19, the sub-shift lever 21 is set to an appropriate position (basic is a low speed or medium speed position). Next, the main speed change lever 20 is moved to an arbitrary position (selectable from 1st speed to 8th speed according to the type of work), and the forward / reverse switching lever 10 is moved to the forward position. The accelerator lever 11 is moved to the pilot side (front side), and the engine speed is set to a rated speed or a maximum speed greater than the rated speed. Next, the clutch pedal 19 is moved forward (with the main clutch 32 connected). At this time, the engine speed is set between the rated speed and the maximum speed equal to or higher than the rated speed, but the working speed is restricted by the position of the main transmission lever 20.

  Note that the accelerator pedal 11 is used instead of the accelerator pedal 15 when the work implement is used in the field. Further, when traveling on the road, the accelerator pedal 15 is used and the accelerator lever 11 is not used. When driving on the road, the accelerator pedal 15 can be operated in the same way as when driving a car, and the engine rotation must be kept constant when working in the field. . Therefore, the accelerator lever 11 is operated during the work, and even if the hand is released from the accelerator lever 11 during the work, it does not return to the original position. Therefore, it is possible to maintain a constant engine speed by maintaining the operated accelerator position.

  FIG. 5 shows a left side view of only the handle post 6, the airframe near the control seat, and the main transmission lever 20. FIG. 6 is an enlarged view of the vicinity of the base portion of the main transmission lever 20. The main speed change lever 20 can change the speed stage from 1st to 8th speed, and a lever position sensor 20a capable of detecting a position position corresponding to each speed stage is provided at the base of the lever 20. The detection value of the lever position sensor 20a is output to a controller (control unit) 90 (FIG. 4).

  7 and 8 are plan views of the transmission case 91 (FIGS. 7A and 8A) and a plan view of the hydrostatic continuously variable transmission mechanism 34 housed in the transmission case 91. FIG. The figure (FIG.7 (b), FIG.8 (b)) is shown. FIG. 9 is a side view of the transmission case 91 as viewed from the direction of arrow A in FIG. As shown in FIGS. 5 to 9, a link mechanism 95 that connects the hydraulic cylinder 93 that rotates the trunnion shaft 92 of the hydrostatic continuously variable transmission mechanism 34 and the trunnion shaft 92 that protrudes outside the transmission case 91 is provided. It is attached to the outer wall portion of the transmission case 91.

  The other end of the arm 95a having one end rotatably connected to the tip of the piston rod 93a of the cylinder 93 is rotatably supported on the outer wall of the transmission case 91, and the other end of the arm 95a is supported on the other end. One end of a rod 95b provided in a direction orthogonal to the longitudinal direction of the arm 95a is rotatably provided, and the other end of the rod 95b is substantially parallel to the arm 95a via a rotatable short arm 95c. The end of the rod 95d, whose length can be adjusted in the direction, is pivotally connected. The other end of the rod 95d whose length can be adjusted is rotatably connected to one end of a short arm 95e, and a boss 95f is fixed to the other end of the short arm 95e.

  The boss 95f is fixed to the shaft 95q with a bolt 95p. The shaft 95q is rotatably supported with respect to the transmission case 91, and a plate 95g is fixed to one end of the shaft 95q. The other end of the plate 95g is rotatably connected to a link arm 95h via a pin 95r, and the link arm 95h is rotatably connected to a cam 95j integrated with the trunnion shaft 92. Here, the cam 95j is fixed to the boss 95s, and the boss 95s is fixed to the trunnion shaft 92 by a bolt 95t.

  The plate 95g and the link arm 95h are connected by a pin 95r, and the connecting portion by the pin 95r has an arc-shaped elongated hole 95k1 of a fan-like member 95k fixed to the transmission case 91 with a shaft 95q as a pivot. Since the pin 95r is slidable only in the long hole 95k1, the rotation range of the cam 95j is also restricted within the range interlocked with the sliding of the pin 95r.

  By the link mechanism 95, the operation of the hydraulic cylinder 93 is interlocked with the arm 95a, the rod 95d, etc., and the cam 95j rotates together with the trunnion shaft 92. Further, the cam 95j is rotated by the cylinder 93 while the side surface of the cam 95j is in contact with the side surface of the roller 95m supported by the transmission case 91.

  The state shown in FIG. 7 shows a state in which the trunnion shaft 92 faces the swash plate 34d of the hydraulic pump 34a of the hydrostatic continuously variable transmission mechanism 34 toward the vehicle forward side, and is a plan view of the transmission case 91 of FIG. FIG. 8A) and a plan view of the hydrostatic continuously variable transmission mechanism 34 housed in the transmission case 91 (FIG. 8B) show the hydraulic pressure of the hydrostatic continuously variable transmission mechanism 34. The state where the swash plate 34d of the pump 34a is directed to the neutral position is shown, and the position where the roller 95m fits into the recess 95j1 of the cam 95j is the neutral position of the trunnion shaft 92. The roller 95m is pressed by a spring from the x direction in FIG. 10 shows a plan view of the transmission case 91 (FIG. 10A) and a plan view of the hydrostatic continuously variable transmission mechanism 34 housed in the transmission case 91 (FIG. 10B). The state shows a state in which the swash plate 34d of the hydraulic pump 34a of the hydrostatic continuously variable transmission mechanism 34 is disposed facing backward.

  FIG. 11 is a diagram showing the arrangement of shift switches 10a and 10b provided at the base of the forward / reverse switching lever 10 and the operation mode thereof. 11A and 11C, the forward shift switch 10a and the reverse shift switch 10b provided at the base of the forward / reverse switching lever 10 when the forward / reverse switching lever 10 is in the forward position and the reverse position are operated. FIG. 11B shows a layout diagram when the forward / reverse switching lever 10 is in the neutral position and does not come into contact with either the forward shift switch 10a or the reverse shift switch 10b.

  When the forward / reverse switching lever 10 is tilted forward from the neutral position so that the forward shift switch 10a of the forward / reverse switching lever 10 is operated, it is ready to move in the forward direction, and the reverse shift switch 10b of the forward / reverse switching lever 10 is operated. Thus, when the forward / reverse switching lever 10 is tilted backward from the neutral position, preparation for moving in the backward direction is made. It should be noted that acceleration in the forward and reverse directions of the vehicle is only performed by the main speed change lever 20.

  Further, since an EEPROM 90a for storing the detected value of the lever position sensor 20a of the main transmission lever 20 shown in FIG. 5 is arranged in the controller 90, first, a lever position sensor corresponding to the current position of the main transmission lever 20 is used. The output value (T) of 20a, the value (A) of the minimum vehicle speed instruction position of the lever position sensor 20a, and the value (B) of the maximum vehicle speed instruction position are stored in the EEPROM 90a.

Next, the controller 90 calculates the first value as an output ratio to the hydraulic cylinder 93 with respect to the total stroke amount of the trunnion shaft turning hydraulic cylinder 93 corresponding to the turning angle of the trunnion shaft 92 by the following equation (1). .
Output ratio to hydraulic cylinder = (TA) / (AB) (1)

  In this way, the hydraulic cylinder 93 is operated according to the first value obtained by the above equation (1). The magnitude of the detected value of the trunnion shaft position sensor 92a obtained at that time is the same as that of the trunnion shaft position sensor 92a. Corresponding to a detection range, for example, any voltage value between 0 and 5 volts. Therefore, the detection value of the trunnion axis position sensor 92a is transmitted to the controller 90, and the controller 90 obtains the magnitude of the detection value of the trunnion axis position sensor 92a as a ratio to the magnitude of the entire detection range of the trunnion axis position sensor 92a. This is the second value. The controller 90 controls the obtained second value to be equal to the first value, and when the first value and the second value are equal, the electromagnetic valve (not shown) of the trunnion shaft rotating hydraulic cylinder 93 is shown. (The oil in the cylinder 93 does not leak out and the cylinder piston is held at the position where the output is stopped).

  In general, variation due to an error or the like when assembling the link mechanism 95 that correlates the variation in the mounting position of the lever position sensor 20a of the main transmission lever 20 and the rotation angle of the trunnion shaft 92 of the hydrostatic continuously variable transmission mechanism 34 is different for each work vehicle. It is in.

However, according to this embodiment, the rotation angle of the trunnion shaft 92 determined by the operation amount of the trunnion shaft rotating hydraulic cylinder 93 and the operation amount of the trunnion shaft rotating hydraulic cylinder 93 determined according to the operation amount of the main transmission lever 20. This variation can be absorbed even if there is variation due to the assembly error of related members. By implementing this for all work vehicles, a highly accurate travel control device can be obtained.
However, if the signal from the trunnion shaft position sensor 92a does not reach the value calculated by the equation (1) even after a predetermined time has elapsed, the output to the hydraulic cylinder 93 is stopped and an alarm is issued.

  A trunnion shaft position sensor 92a (FIG. 7) that detects the rotation position of the trunnion shaft 92 by the operation of the trunnion shaft rotation hydraulic cylinder 93 is configured to detect the degree of rotation of the rotation shaft 93d. The trunnion shaft position sensor 92a is coupled to the other end of an arm 93c having one end rotatably provided on the opposite side of the connecting portion of the arm 95e at the tip of the rod 95d. Thereby, the trunnion shaft position sensor 92a detects the movement (position) of the trunnion shaft 92. The position sensor 92a of the trunnion shaft 92 includes a stopper 93e provided at the maximum extension setting position on the forward side of the piston rod 93a of the trunnion shaft rotating hydraulic cylinder 93 and a stopper 93f (FIG. 9) provided at the minimum shortening setting position on the reverse side. Each set position is set as a reference value that allows the trunnion shaft 92 to rotate. The position where the roller 95m fits into the recess 95jl of the cam 95j is the neutral position of the trunnion shaft 92, and this is also set as the reference value. Each set position detected by the trunnion axis position sensor 92a is stored in a memory (EEPROM) 90a of the controller 90 as a reference position.

  Further, detection of a trunnion shaft position sensor 92a contacting the stopper 93e provided at the maximum extension setting position on the forward side of the piston rod 93a of the hydraulic cylinder 93 for turning the trunnion shaft and the stopper 93f provided at the minimum shortening setting position on the reverse side. Since the rotation range of the trunnion shaft rotation hydraulic cylinder 93 can be controlled using the position as a reference position, the dimensions of the link mechanism 95 for associating the rotation angle of the trunnion shaft 92 of the hydrostatic continuously variable transmission mechanism 34 are as follows. Errors and the like can be absorbed.

A switch for entering a mode for adjusting the reference value of the position sensor 92a of the rotational position of the trunnion shaft 92 is provided on the operation panel of the control seat 9. This switch is covered with a cover and is included in the switch group. The names are arranged to be similar to each other so that switches for adjusting the reference values of the respective position sensors can be easily identified. The reason is that, when there are a large number of sensors to be adjusted, a switch having a similar name is attached to the switch group in the adjustment mode so as to prevent the switch from entering the adjustment mode.

  The operation position of the main speed change lever 20 is from 1st to 8th speed. The operation position of each gear position is detected by the lever position sensor 20a, and the hydraulic cylinder is controlled by the controller 90 with these detected values as target positions. 93 is operated to turn the trunnion shaft 92.

  The control output to the hydraulic cylinder 93 at this time is a pulse output, and the pulse cycle can be changed according to the deviation between the target position and the current position. That is, when the deviation is large, the pulse output cycle is shortened to make the operation of the trunnion shaft turning hydraulic cylinder 93 relatively fast, and when the deviation is small, the pulse output cycle is made long and the trunnion shaft turning hydraulic cylinder is made. The operation of 93 is made relatively slow.

  If the control output to the target position of the trunnion shaft turning hydraulic cylinder 93 is a continuous output instead of a pulse output, when the trunnion shaft 92 is operated, the operating speed of the hydraulic cylinder 93 is too fast and the vehicle traveling speed is suddenly accelerated or suddenly increased. Although the vehicle may be decelerated, the vehicle can be smoothly accelerated and decelerated by using the control output as a pulse output.

  At this time, the difference in operation speed can be reduced by changing the pulse on time or changing the pulse cycle on the expansion side and the contraction side of the piston rod 93a of the trunnion shaft turning hydraulic cylinder 93. This is because the piston (not shown) that bisects the oil chamber inside the cylinder at the end of the rod 93a traversing the hydraulic cylinder 93 is divided into the side where the piston rod 93a is located (extended side) and the side where the piston rod 93a is not located (contracted). This is to adjust the oil chamber cross-sectional area on the side).

  The engine is started by depressing the clutch pedal 19 and turning the clutch switch 97 (FIG. 4) on (clutch disengagement) and setting the forward / reverse switching lever 10 to neutral, but when the hydraulic cylinder 93 is not neutral immediately after engine startup. There is. This is because if the engine 5 is turned off during forward travel, the trunnion shaft turning hydraulic cylinder 93 may stop operating in a state other than the neutral position.

  Therefore, when the trunnion shaft turning hydraulic cylinder 93 is not in the neutral position, an output is made to return the hydraulic cylinder 93 to the neutral position, and the warning buzzer is continuously sounded until the hydraulic cylinder 93 returns to the neutral position. As a configuration, driving safety is enhanced.

  Further, when the engine is started, if the trunnion shaft turning hydraulic cylinder 93 is in a position other than the neutral position, continuous output is used instead of pulse output in order to increase the operating speed of the hydraulic cylinder 93 in order to quickly return to the neutral position.

  When the engine is started, the forward / reverse switching lever 10 is always in the neutral position, but if the clutch pedal 19 is returned and the main clutch 32 is engaged, the vehicle may start. For this purpose, as described above, the hydraulic cylinder 93 is operated with continuous output instead of pulse output, so that the trunnion shaft rotating hydraulic cylinder 93 is quickly returned to the neutral position when the engine is started. At this time, an alarm buzzer is sounded to alert the operator.

  Further, when the forward / reverse switching lever 10 is set to neutral in the traveling state during forward or reverse travel, when the clutch pedal 19 is not depressed (the main clutch 32 is turned on and the clutch switch 97 is turned off), the hydraulic cylinder 93 outputs a pulse ( When the clutch pedal 19 is depressed (the main clutch 32 is disengaged and the clutch switch 97 is engaged), the hydraulic cylinder 93 returns to neutral with continuous output (fast). Further, when the clutch pedal 19 is depressed (the main clutch 32 is disengaged and the clutch switch 97 is engaged) and the main speed change lever 20 is operated while the forward / reverse switching lever 10 is moving forward or backward, the target position is obtained with continuous output (fast).

  As described above, when the control output to the target position of the trunnion shaft rotating hydraulic cylinder 93 is a pulse output and the pulse cycle is changed according to the deviation between the target position and the current position, the position sensor 92a of the trunnion shaft 92 is used. If the value of does not change significantly, increase the ON time ratio within a predetermined period (pulse period) consisting of ON / OFF of the pulse output and increase the ON time (increase the pulse output) It is good also as a structure which correct | amends.

  This is because, for example, when the temperature of the lubricating oil is low and the trunnion shaft turning hydraulic cylinder 93 does not operate in a pulse cycle with a short on time, the on time within the predetermined pulse cycle is made longer to turn the trunnion shaft. This is because the hydraulic cylinder 93 needs to be corrected to increase the operation output.

However, the speed at which the trunnion shaft rotating hydraulic cylinder 93 moves to the target position (depending on the pulse on time) can be changed in accordance with the position of the auxiliary transmission lever 21.
This is because if the sub-transmission device selects the low speed stage, even if the hydraulic cylinder 93 is brought to the target position as quickly as possible, it will not be suddenly accelerated or decelerated. If it is selected, if the movement to the target position of the trunnion shaft turning hydraulic cylinder 93 is quickly performed, the vehicle is suddenly accelerated or decelerated. In this case, the moving speed to the target position of the hydraulic cylinder 93 is comparatively delayed. . Thus, the response of the hydraulic cylinder 93 is improved even when traveling at a low speed.

  Further, the hydraulic cylinder 93 is controlled to expand and contract in accordance with the state of the lever position sensor 20a and the forward / reverse switching lever shift switches 10a and 10b, and the vehicle is moved forward and backward, but the throttle sensor 11a (FIG. 4) is provided at the base of the accelerator lever 11. And the operation speed (by changing the pulse on time) of the trunnion shaft rotating hydraulic cylinder 93 may be changed according to the position of the throttle sensor 11a.

  With the above configuration, when the engine speed is low, the response of the operation speed of the trunnion shaft rotating hydraulic cylinder 93 is improved, and when the engine speed is high, the target speed can be changed with good feeling.

  Further, by providing a headland control mode switch that can increase the traveling speed when traveling backward as compared with the traveling speed when traveling forward, the maneuverability at the headland is improved. In headlands (corner corners), there are times when forward and reverse are repeated to change the direction of the vehicle, but in that case, if the traveling speed is slower than the traveling speed when moving forward, You may feel that turning performance is not good. Therefore, when traveling on a headland, the headland control mode is set in which the traveling speed at the time of reverse traveling is made faster than the traveling speed at the time of forward movement, and the switch that can be selected by this mode, for example, tilling of the field during reverse traveling Work efficiency can be improved.

  For example, when the main speed change lever 20 at the time of forward movement is in the third speed, the signal of the lever position sensor 20a is input to the controller 90, and the controller 90 controls the hydraulic cylinder 93 so that the trunnion shaft 92 is in the position to output the third speed. However, when moving backward from this state, the controller 90 controls the hydraulic cylinder 93 so that, for example, the trunnion shaft 92 is in a position for producing the fourth speed or the fifth speed even if the main speed change lever 20 is at the third speed.

  However, it is desirable that the headland control mode is selected only at the rotary work speed (for example, only at the sub-shifting low speed) because there is an unexpected problem if the vehicle moves fast when backing up on the road.

(Forward / backward switching control)
Next, the forward / reverse switching control of the shift control device of the hydrostatic continuously variable transmission mechanism (forward / reverse continuously variable transmission mechanism) will be described.
As shown in the control block diagram of FIG. 12, the shift control device includes a controller (control unit) 90 that includes sensor switches 10a and 10b of the forward / reverse switching lever 10, a lever position sensor 20a of the main shift lever 20, and a trunnion shaft position sensor 92a. Are connected to each other, and the signals are input, and control outputs of an extension output 93x and a contraction output 93y are output to the drive cylinder 93 of the trunnion shaft 92 so that these operating tools are reflected in the control of the hydrostatic continuously variable transmission mechanism 34.

  The shift control process by the controller 90 controls the operation rotation ratio of the forward / reverse continuously variable transmission mechanism 34 according to the target rotation ratio of the travel transmission system corresponding to the operation positions of the forward / reverse switching lever 10 and the main shift lever 20. With the shift control configuration, smooth shift control can be ensured when the main shift lever 20 is operated.

  As shown in the flowchart of FIG. 13, the control processing of the reverse operation of the forward / reverse switching lever 10 is performed when the trunnion cylinder position is opposite to the lever instruction position during the reverse operation of the forward / reverse switching lever 10 (S1, S2). If there is, the trunnion cylinder 93 is driven at a rapid change rate according to the maximum expansion / contraction speed by continuous output (S4a), and at the same side, the trunnion cylinder 93 is driven at a deviation corresponding change rate according to the deviation to the target position by the pulse output (S4b).

  With the above control process, when the reverse operation is performed beyond the neutral stop position of the forward / reverse switching lever 10 during traveling, the operation rotation ratio of the hydrostatic continuously variable transmission mechanism (34) is relatively large until the neutral operation. The speed is controlled at a rapid change rate, the aircraft stops, and then reverse travel is started, and the speed is controlled at a deviation corresponding change rate corresponding to the difference from the target rotation ratio within a range that does not satisfy the rapid change rate to reach the target vehicle speed. .

  Therefore, if the forward / reverse switching lever 10 is operated in a reverse direction rapidly, the aircraft travels immediately in response to the lever operation without inertia of the aircraft, and then enters a reverse direction to achieve a relatively smooth change to the target vehicle speed. Therefore, a quick forward / reverse switching operation in accordance with the operator's intention can be realized by a stop operation with a good response and no sense of incongruity and a smooth reverse acceleration thereafter.

  As another control processing example, as shown in the flowchart of FIG. 14, at the time of shifting (S11, S12), except for shifting to the speed increasing side (S13), a rapid change rate to the target rotation ratio is obtained. By performing the speed change control (S14b), the traveling body is decelerated in response to the lever operation in the deceleration process.

  Therefore, the speed increasing operation can prevent the gear shift shock even by a rapid lever operation and ensure a smooth gear shifting, while the deceleration operation is decelerated without inertia traveling in accordance with the lever operation. The same effect as described above can be obtained for the rapid operation of the advance switch lever 10. If necessary, the rapid change rate may be a deviation corresponding change rate for a range within a predetermined residual near the target rotation ratio.

(Start control)
Next, the aircraft start control by the forward / reverse switching lever 10 will be described.
When starting the aircraft, as shown in the flow chart of FIG. 15, the shift control (S24a) is performed at the deviation corresponding change rate only in the case of the shift operation by the operation of the forward / reverse switching lever 10 (S21 to S23), In other cases, the shift control (S24b) is performed at a rapid change rate.

  By controlling in this way, shock can be reduced when the vehicle starts with the forward / reverse switching lever 10, and in other cases, the operation can be performed with an emphasis on response. The “other case” is, for example, a case where the main speed change lever 20 is operated in a state where the forward / reverse switching lever 10 is inserted and the vehicle is traveling without a clutch. If necessary, the rapid change rate may be a deviation corresponding change rate for a range within a predetermined residual near the target rotation ratio.

(Clutch compatible control)
Next, clutch operation support control will be described.
In the conventional shift control, when the forward / reverse switching lever 10 is moved forward or backward, the trunnion cylinder 93 is in the position designated by the main shift lever 20. For example, the trunnion cylinder 93 is also at the highest speed position on the forward side when the main transmission lever 20 is at the eighth speed. When the engine is stopped in this state, the trunnion remains at the position because of the hydraulic cylinder. When the engine is started again, it takes time for the trunnion cylinder 93 to return to the neutral position, and there is a problem that the aircraft moves even when the forward / reverse switching lever 10 is in the neutral position.

  In order to solve this problem, as shown in the flowchart of the clutch operation support control in FIG. 16, when the trunnion cylinder target position is on the high speed side (S31, S32), the clutch is depressed and the tractor is stopped. In the state (S33), the trunnion cylinder target position is changed to around the medium speed (S34).

  In a normal case, when the tractor is stopped, the forward / reverse switching lever 10 is pulled out or the clutch pedal 19 is turned off to stop. In this case, since the trunnion cylinder 93 is neutral, it is neutral when the tractor stops, and the engine is then turned off, so there is not much danger of moving when the engine is started again.

  On the other hand, the above-described control configuration is effective for solving the above-described problem when the clutch is disengaged. By setting the trunnion cylinder target near the middle speed, if the engine is turned off and restarted in that state, the trunnion cylinder can be brought to neutral during engine cranking from the middle speed of the trunnion cylinder and start moving. Sex can be avoided.

  On the other hand, in the above control configuration, when the clutch is disengaged and then the engine is stopped, the control is performed in consideration of the safety at the time of the subsequent restart. Conversely, since the connection of the foot clutch and the connection by the trunnion cylinder operation (change in vehicle speed) are doubled, there is a possibility that a sense of incongruity may occur during re-running.

  In order to solve this problem, in the above configuration, when the clutch depressed state is released, the transition control is performed at a rapid change rate so that the original trunnion cylinder target position can be quickly obtained. With this configuration, the clutch switch 97 is set to the stepping side from the torque transmission point (half clutch start point) of the main clutch, so that when it is turned from ON to OFF, the original trunnion target position is reached at a rapid transition speed. By returning to, it becomes a start with the main clutch by foot, and can start without a sense of incongruity.

(Speed increase sensitivity adjustment)
Next, speed-up sensitivity adjustment will be described.
As shown in the perspective view of FIG. 17, when starting with the forward / reverse switching lever 10, the speed increase sensitivity switch (or volume) 10s that can change the operating speed of the trunnion cylinder 93 until it reaches the target trunnion position is moved back and forth. It is provided on the grip of the advance switching lever 10 or the like.

  If the operating speed is slowed down, there is no shock but a start with a time lag occurs. Conversely, if the operating speed is increased, a shock can be produced with a slight time lag. In this way, the speed increase sensitivity switch 10s can provide a start feeling according to the needs of the operator.

(Another control example)
Next, another configuration example of the clutch correspondence control will be described.
The foot clutch is often quickly engaged in the working speed range, and the above-described problems related to the clutch correspondence control may not be solved in the working speed range. In addition, if the tractor moves without applying the clutch control, it is extremely low in the working speed range, and does not cause much problem at the same level as missions other than HST that moves around.

  Therefore, the clutch-adaptive control is limitedly applied to the case where the sub-shift is “high speed”, so that the trunnion target is not changed unnecessary in the working speed range, and immediately returns to the target vehicle speed even if the foot clutch is quickly connected. be able to.

(Shifting range expansion)
Next, the unfolding type of the main transmission lever 20 will be described.
As shown in the perspective view of FIG. 8, the main transmission lever deployment change switch 20 s is provided in the vicinity of the main transmission lever 20 or on the knob of the main transmission lever 20. The main shift lever deployment change switch 20s can change the deployment formula based on the calculation formula of the target position of the trunnion corresponding to the shift position of the main shift lever 20, and the function of the switch 20s can be easily understood by the above relational arrangement. In addition, by adopting a configuration in which a switch is provided on the knob of the main transmission lever 20, the change can be easily performed with one lever.

  Conventionally, there is only one type of unfolding type, and the 1st to 8th speed of the main transmission lever 20 corresponds to the 1st to 8th speed on the trunnion forward side or the reverse side. This is changed by operating the switch so that, for example, the 1st to 8th speeds of the main transmission lever 20 correspond to the 1st to 5th speeds on the trunnion forward side or reverse side. By this change, the increment of the vehicle speed change due to the lever operation can be reduced.

  As another development example, a mode in which the low speed range is widely developed (low speed range expansion mode), a mode in which the high speed range is broadly expanded (high speed range expansion mode), and 1st to 8th speeds are developed on a one-to-one basis. By providing a three-position switch capable of selecting the normal mode (full mode), the increment of the vehicle speed change due to the lever operation can be reduced. Further, the development is doubled, and it becomes very easy to understand by making about two kinds of high speed range and low speed range.

As another development example, the low speed range expansion mode is deployed from 1st to 5th speed in full mode, and the high speed range expansion mode is deployed from 4th speed to 8th speed in full mode. It is configured to wrap the maximum speed and the minimum speed of the high-speed range expansion mode.
By such a development process, when it is a work speed near the boundary between the low speed range expansion mode and the high speed range expansion mode, when it is desired to slightly increase or decrease the vehicle speed due to load fluctuation, etc., by wrapping as described above, There is no need to switch modes one by one.

  The change of the main shift lever deployment change switch in the above is to change the mode during driving by making the change ability only when the tractor is stopped (clutch = “disengaged” or forward / reverse switching lever = “N”). If the trunnion cylinder target changes, sudden deceleration and rapid acceleration may occur, which may be dangerous, so such a problem can be solved.

  In addition, when the mode is changed by operating the main shift lever deployment change switch 20s and the mode is changed from the low speed range expansion mode or the high speed range expansion mode to the full mode, the trunnion cylinder target by the expansion formula in the original mode is set. A control process that allows acceleration / deceleration from the point in time when the trunnion cylinder target by the expansion formula in the full mode coincides is configured.

  With this configuration, when the target is set to the trunnion cylinder position calculated by the expansion formula in the mode after the change immediately after the operation of the main shift lever deployment change switch 20s, sudden deceleration and sudden increase may be dangerous. Therefore, such a problem can be solved.

It is a left view of the tractor of one Example of this invention. It is a top view of the tractor of FIG. It is a power diagram of the transmission of the tractor of FIG. It is a control block diagram of the transmission of the tractor of FIG. FIG. 2 is a left side view of only the handle post, the fuselage in the vicinity of the control seat, and the shift lever of the tractor of FIG. 1. FIG. 5 is an enlarged view of a base portion of the speed change lever of FIG. 4. FIG. 7 is a plan view of the transmission case of the tractor during forward movement (FIG. 7A) and a plan view of the hydrostatic continuously variable transmission mechanism housed in the transmission case (FIG. 7B). is there. FIG. 8 is a plan view of the transmission case of the tractor in the neutral state of FIG. 1 (FIG. 8A) and a plan view of the hydrostatic continuously variable transmission mechanism housed in the transmission case (FIG. 8B). is there. It is the side view of the transmission case seen from the arrow A direction of Fig.8 (a). FIG. 10 is a plan view (FIG. 10A) of the transmission case of the tractor during reverse travel of FIG. 1 and a plan view of the hydrostatic continuously variable transmission mechanism housed in the transmission case (FIG. 10B). is there. The forward / reverse switching lever of the tractor in FIG. 1 is in the forward position (FIG. 11 (a)), neutral position (FIG. 11 (b)), or reverse position (FIG. 11 (c)). It is a figure which shows arrangement | positioning of the shift switch provided in the base part, and its operation | movement aspect. It is a control block diagram of a transmission control device. It is a flowchart of the control processing at the time of reverse operation. It is a flowchart of another example of control processing. It is a flowchart of the control processing at the time of start operation. It is a flowchart of the control processing at the time of clutch operation. It is a perspective view of a speed-up sensitivity adjustment switch attached state. It is a perspective view of a main transmission lever deployment change switch attached state.

Explanation of symbols

2 Front wheel 3 Rear wheel 5 Engine 10 Forward / reverse switching lever 10a Forward shift switch (sensor switch)
10b Reverse shift switch (sensor switch)
DESCRIPTION OF SYMBOLS 19 Clutch pedal 20 Main transmission lever 20a Lever position sensor 32 Main clutch 33 Hydrostatic continuously variable transmission mechanism input shaft 34 Hydrostatic continuously variable transmission mechanism (back and forth continuously variable transmission mechanism)
36 Traveling output shaft 90 Controller (control unit)
92 trunnion shaft 92a trunnion shaft position sensor 93 trunnion shaft rotating hydraulic cylinder 93x output 93y output 97 clutch switch

Claims (2)

The forward / reverse switching lever (10) capable of selecting forward / backward and neutral stop positions and the main transmission lever (20) capable of selecting positions of a plurality of vehicle speeds, the target rotation of the driving transmission system corresponding to the operation position. In a shift control device for a work vehicle having a control unit (90) for performing a shift control of the traveling transmission system by controlling an operation rotation ratio of the forward / reverse continuously variable transmission mechanism (34) according to the ratio,
The control unit (90) shifts the operation rotation ratio to the target rotation ratio by a deviation corresponding change rate according to a change rate according to the difference from the target rotation ratio, and the forward / reverse switching lever (10) is neutrally stopped. Only when a reverse operation exceeding the position is received, the speed until the neutral movement, which is zero transmission of the forward / reverse continuously variable transmission mechanism (34), is set to a large change rate exceeding the deviation corresponding change rate. A shift control apparatus for a work vehicle, wherein the shift control is performed at a change rate. The forward / reverse switching lever (10) capable of selecting forward / backward and neutral stop positions and the main transmission lever (20) capable of selecting positions of a plurality of vehicle speeds, the target rotation of the driving transmission system corresponding to the operation position. In a shift control device for a work vehicle having a control unit (90) for performing a shift control of the traveling transmission system by controlling an operation rotation ratio of the forward / reverse continuously variable transmission mechanism (34) according to the ratio,
The control unit (90) shifts the operation rotation ratio to the target rotation ratio by a deviation corresponding change rate according to a change rate according to a difference from the target rotation ratio, and when the target rotation ratio is in a deceleration direction. As long as the shift control is performed at a rapid change rate set to a large change rate exceeding the deviation-corresponding change rate, the operation rotation ratio changes in accordance with the difference from the target rotation ratio before a predetermined value of the target position in the deceleration direction. A shift control apparatus for a work vehicle, wherein shift control is performed to a target rotation ratio based on a deviation corresponding change rate based on a rate.

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