JP2008169968A - Traveling control device for working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shift device for a working vehicle capable of absorbing dispersion between an operation amount of a shift lever and an operation amount of a hydraulic cylinder for turning a trunnion shaft. <P>SOLUTION: A transmission device including a static hydraulic type continuously variable transmission 34 for adjusting and outputting a turning angle of a trunnion shaft 92, and a shift lever 20 for setting an operation amount of a hydraulic cylinder 93 for determining a turning angle of the trunnion shaft 92 are provided. An output value T at the present position of a sensor 20a for detecting an operation position of the shift lever 20, the lowest vehicle speed instruction position A and the maximum vehicle speed instruction position B are stored, and a first value obtained by an equation (output ratio to hydraulic cylinder=(T-A)/(A-B)) is made to be in an output ratio with respect to the whole stroke amount of the hydraulic cylinder 93 corresponding to the turning angle of the trunnion shaft 92. The magnitude of the detection value of a trunnion shaft position sensor 92a obtained by operating the hydraulic cylinder 93 according to the first value is obtained as a ratio (second value) relative to a magnitude of the whole detection range of the sensor 92a. The controller 90 performs control so that the second value becomes equal to the first value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a traveling control device for a traveling vehicle having a transmission composed of a hydrostatic continuously variable transmission and a meshing transmission used in work vehicles such as tractors for agriculture, construction, and transportation.

  A work vehicle such as a tractor including a transmission including a hydrostatic continuously variable transmission and a meshing transmission is described in, for example, Japanese Patent Application Laid-Open No. 2002-250437.

In the transmission comprising the hydrostatic continuously variable transmission and the meshing transmission of the work vehicle, the forward / reverse lever determines the forward / reverse rotation direction of the trunnion shaft, and the trunnion shaft is rotated based on the operation amount of the shift lever. The output of the hydrostatic continuously variable transmission is performed by adjusting the operating amount of the hydraulic cylinder.
JP 2002-250437 A

  In the transmission, the rotation angle of the trunnion shaft of the hydrostatic continuously variable transmission by the transmission lever is adjusted by operating the trunnion shaft by the hydraulic cylinder according to the detection value of the detection sensor that detects the rotation angle of the transmission lever. Is going.

  However, the mounting position of the shift lever operation amount detection sensor varies from production lot to lot, and the hydraulic cylinder is operated based on the operation amount of the transmission lever, and the rotation of the trunnion shaft is made to correspond to the operation amount of the hydraulic cylinder. In the link mechanism that determines the amount of movement, it is inevitable that an assembly dimensional error will occur during assembly for each production lot.

  The problem of the present invention is that the ratio between the operation amount of the transmission lever and the operation amount of the hydraulic cylinder that rotates the trunnion shaft in correspondence with the sensor value that detects the operation amount of the transmission lever is an assembly size error for each production lot. It is an object of the present invention to provide a transmission device for a work vehicle that can absorb the dimensional error even if it varies depending on the situation.

The above-mentioned problem of the present invention is solved by the following means.
That is, according to the first aspect of the present invention, the hydrostatic continuously variable transmission (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92) and the hydrostatic continuously variable transmission. A transmission including a meshing transmission (38) for changing the device output to a plurality of shift stages, and a trunnion shaft for determining the rotation angle of the trunnion shaft (92) of the hydrostatic continuously variable transmission (34) A trunnion that is provided between a rotating hydraulic cylinder (93), a trunnion shaft (92), and the hydraulic cylinder (93), and detects a rotational angular position of the trunnion shaft (92) by the operation of the hydraulic cylinder (93). A shift lever (20) for setting the operation amount of the shaft position sensor (92a), the trunnion shaft turning hydraulic cylinder (93), and a shift lever position sensor for detecting the operation position of the shift lever (20). (20a), storage means for storing the output value (T) of the current position of the shift lever position sensor (20a), the output value (A) of the minimum vehicle speed instruction position, and the output value (B) of the maximum vehicle speed instruction position ( 90a) and 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) using the first value calculated by the following equation (1). Output ratio to
Output ratio to hydraulic cylinder = (TA) / (AB) (1)
The magnitude of the detected value of the trunnion shaft position sensor (92a) obtained by operating the hydraulic cylinder (93) according to the first value obtained by the equation (1) is determined by the trunnion shaft position sensor (92a). A travel control device for a work vehicle comprising a controller (90) that is obtained as a ratio to the size of the entire detection range, and that the ratio is set as a second value so that the second value is equal to the first value. is there.

  According to the first aspect of the present invention, the operation position of the transmission lever (20) is detected by the sensor (20a), and the output ratio to the trunnion shaft rotating hydraulic cylinder (93) corresponding to the detected value (T) ( (First value) (ratio of the operation amount of the hydraulic cylinder (93) to the total stroke amount) is always calculated for each work vehicle by the above equation (1), and the controller (90 ) Determines the operation amount of the hydraulic cylinder (93), and moves the trunnion shaft (92) by a predetermined rotation angle.

  At this time, the trunnion shaft (92) rotates corresponding to the operation amount of the hydraulic cylinder (93), and the rotation position of the trunnion shaft (92) is detected by the position sensor (92a). The ratio (second value) of the magnitude of the detection value of the trunnion shaft position sensor (92a) to the size of the entire detection range (for example, 0 to 5 volts becomes the entire detection range of the sensor (92a)) and the first Activating the controller (90) to ensure that one value is equal.

  According to the second aspect of the present invention, the hydrostatic continuously variable transmission (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92) and the hydrostatic continuously variable transmission. Rotation angle of the trunnion shaft (92) of the transmission including the meshing transmission (38) that outputs the output of the device (34) by changing the output to a plurality of shift stages, and the hydrostatic continuously variable transmission (34) A trunnion shaft rotating hydraulic cylinder (93) for determining the rotation, a link mechanism (95) for associating the rotation angle of the trunnion shaft (92) based on the operation amount of the hydraulic cylinder (93), and the link mechanism (95) The trunnion shaft position sensor (92a) for detecting the rotation angle position of the trunnion shaft (92) due to the operation of the hydraulic cylinder (93), and the shift lever for setting the operation amount of the trunnion shaft rotation hydraulic cylinder (93). (20), a stopper (93e) provided at the maximum extension setting position on the forward side of a piston rod (93a) provided in the trunnion shaft turning hydraulic cylinder (93), and a piston in the trunnion shaft turning hydraulic cylinder (93) A stopper (93f) provided at a minimum shortening set position on the reverse side of the rod (93a) and a neutral position of the trunnion shaft (92) detected by the trunnion shaft position sensor (92a) (the roller 95m is placed in the recess 95j1 of the cam 95j). Storage means (90a) for storing, as reference positions, the maximum extension setting position on the forward side and the minimum shortening setting position on the reverse side detected by the two stoppers (93e, 93f). ) And a hydraulic cylinder (93) for turning the trunnion shaft by the shift lever (20) based on the value of the storage means A travel control device for a working vehicle having a controller (90) for controlling the operating range.

  According to the first aspect of the present invention, the trunnion shaft that is determined according to the operating amount of the trunnion shaft rotating hydraulic cylinder (93) determined according to the operating amount of the transmission lever (20) and the operating amount of the hydraulic cylinder (93). Even if the relationship of the rotation angle of (92) (detected by the position sensor (92a)) varies due to an assembling error of related members, this variation can be absorbed, and this can be absorbed by all work vehicles. As a result, a highly accurate travel control device can be obtained.

  According to the second aspect of the present invention, the 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 the minimum shortening setting position on the reverse side are provided. Since the operating range of the trunnion shaft rotating hydraulic cylinder (93) can be controlled with the detection position of the trunnion shaft position sensor (92a) contacting the stopper (93f) as a reference position, the rotation of the trunnion shaft (92) can be controlled. An error or the like when assembling the link mechanism (95) for associating the moving angle can be absorbed.

Hereinafter, embodiments of the present invention will be described 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.

  Hereinafter, a tractor will be described 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 in the center of the aircraft, and a seat 9 is provided behind the steering handle 7. Below the steering handle 7 is provided a forward / reverse lever 10 for switching the advancing direction of the airframe to the front / rear direction. When the forward / reverse lever 10 is moved forward, 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 lever 10 with the handle post 6 in between, and an accelerator petal 15 and left and right brake petals 16 and 17 are arranged on the right corner of the step floor 13. A clutch pedal 19 is disposed at the left corner portion of 13.

  A shift lever 20 capable of selecting a gear position from 1st speed to 8th speed is located in the left front portion of the cockpit 9. A sub shift lever 21 capable of selecting any one of a low speed position, a medium speed position, a high speed position, and a neutral position is provided thereafter. Further, a PTO speed change lever 23 capable of selecting the 1st to 3rd speeds and the neutral position is provided on the rear side. Further, on the right side of the cockpit 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 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. ) Are provided.

  FIG. 3 is a diagram showing a traveling transmission system of a tractor having the hydrostatic continuously variable transmission 34 of the present 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 input shaft 33 to the hydrostatic continuously variable transmission 34. . The hydrostatic continuously variable transmission 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. 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 sub-transmission clutch 39 of the meshing transmission 38 is slidable in the left and right directions in FIG. 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 differential device 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 differential 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 auxiliary transmission clutch 39, and further 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 transmitted via the differential device 46. 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, the power input from the hydrostatic continuously variable transmission 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 input shaft 33 and the pump output shaft 66 rotate at a constant rotation 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 shift lever 20 is moved to an arbitrary position. The 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 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 (eight speed) of the speed change 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 shift lever 20 is moved to an arbitrary position (selectable from the first speed to the eighth speed according to the type of work), and the forward / reverse 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 regulated by the position of the 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 in the vicinity of the cockpit, and the speed change lever 20. FIG. 6 shows an enlarged view of the vicinity of the base of the speed change lever 20. The speed change lever 20 can change the speed stage from 1st to 8th speed, and a position sensor 22a 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 position sensor 20a is output to the controller 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 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 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 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 34 housed in the transmission case 91 (FIG. 8B) show the hydraulic pressure of the hydrostatic continuously variable transmission 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 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 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 lever 10 and the operation mode thereof. 11 (a) and 11 (c) are layout diagrams in which the forward shift switch 10a and the reverse shift switch 10b provided at the base of the forward / reverse lever 10 operate when the forward / reverse lever 10 is in the forward position and the reverse position. FIG. 11B shows a layout when the forward / reverse 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 lever 10 is tilted forward from the neutral position so that the forward shift switch 10a of the forward / reverse lever 10 is operated, it is ready to move in the forward direction, and the reverse shift switch 10b of the forward / reverse lever 10 is operated. When the forward / reverse lever 10 is tilted backward from the neutral position, it is ready to move in the reverse direction. It should be noted that acceleration in the forward and backward directions of the vehicle is only performed by the shift lever 20.

  Further, since an EEPROM 90a for storing the detected value of the position sensor 20a of the speed change lever 20 shown in FIG. 5 is arranged in the controller 90, first, the output value of the position sensor 20a corresponding to the current position of the speed change lever 20 is provided. (T), the value (A) of the minimum vehicle speed instruction position of the 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, there is a variation due to an error in assembling the link mechanism 95 that associates a variation in the mounting position of the position sensor 20a of the transmission lever 20 with a rotation angle of the trunnion shaft 92 of the hydrostatic continuously variable transmission 34 for each work vehicle. .

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 shift lever 20 is determined. Even if the relationship varies due to an assembling error of the related member, the variation can be absorbed. 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 position sensor 92a (FIG. 7) for detecting 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 position sensor 92a is connected to the other end of an arm 93c having one end rotatably provided on the opposite side of the rod 95d from the connecting portion of the arm 95e. Thereby, the 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 95j1 of the cam 95j is the neutral position of the trunnion shaft 92, which is also a reference value. Each set position detected by the position sensor 92a is stored in a memory (EEPROM) 90a of the controller 90 as a reference position.

  Further, the detection of the 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 34 can be controlled. 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 cockpit 9. The 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 shift lever 20 is from 1st to 8th speed. The operation position of each shift stage is detected by the shift 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 the forward / reverse lever 10 being neutral. However, the hydraulic cylinder 93 may not be neutral immediately after the engine is started. is there. 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 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 lever 10 is set to neutral in the traveling state during forward or reverse travel, the hydraulic cylinder 93 outputs a pulse (slowly) when the clutch pedal 19 is not depressed (the main clutch 32 is turned on and the clutch switch 97 is turned off). 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 a continuous output (fast). Further, when the clutch pedal 19 is depressed (the main clutch 32 is disengaged and the clutch switch 97 is turned on) and the shift lever 20 is operated while the forward / reverse lever 10 moves 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 vehicle is moved forward and backward by controlling the expansion and contraction of the hydraulic cylinder 93 in accordance with the states of the shift lever position sensor 20a and the forward / reverse lever shift switches 10a and 10b, 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 the turning operability is not good. Therefore, when traveling on a headland, the above-mentioned pillow control mode is set in which the traveling speed at the reverse speed is higher than the traveling speed at the above-mentioned forward position, and this mode can be selected by a switch that can be selected, for example, tilling the field during reverse traveling. Work efficiency can be improved. For example, when the speed change lever 20 at the time of forward movement is in the 3rd speed, the signal of the 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 3rd speed. 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 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.

  The present invention can be used as a travel control device for work vehicles such as tractors for agriculture, construction, and transportation.

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 cockpit, 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 (FIG. 7A) of the transmission case of the tractor during forward movement in FIG. 1 and a plan view of the hydrostatic continuously variable transmission 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 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 reverse tractor in FIG. 1 and a plan view of the hydrostatic continuously variable transmission housed in the transmission case (FIG. 10B). is there. The base of the forward / reverse lever indicates whether the forward / reverse lever of the tractor in FIG. 1 is in the forward position (FIG. 11 (a)), the neutral position (FIG. 11 (b)), or the reverse position (FIG. 11 (c)). It is a figure which shows arrangement | positioning of the shift switch provided in and its operation | movement aspect.

2 Front wheel 3 Rear wheel 5 Engine 6 Handle post
7 Steering handle 9 Seat 10 Forward / reverse lever 10a Forward shift switch 10b Reverse shift switch 11 Accelerator lever 11a Throttle sensor 13 Step floor 15 Accelerator petal 16, 17 Brake petal 19 Clutch pedal 20 Shift lever 20a Position sensor 21 Sub shift lever 23 PTO shift Lever 24 Position lever 25 Automatic tilling lever 27 Right up switch 28 Right down switch 29 Automatic horizontal switch 30 Backup switch 32 Main clutch 33 Hydrostatic continuously variable transmission input shaft 34 Hydrostatic continuously variable transmission 34a Hydraulic pump 34b Hydraulic pressure Motor 34c Hydraulic closed circuit 34d Swash plate 36 Traveling output shaft 39 Sub-transmission clutch 41 Gear 42 High-speed gear 43 Transmission shaft 45 Gear 46 Differential device 47 Medium-speed gear 4 , 50, 51, 53 Gear 55 Low speed gear 56, 57, 59, 60 Gear 61 Front wheel output shaft 63 Hydraulic clutch 64 Hydraulic clutch 65 Differential device 66 Pump output shaft 67 PTO forward / reverse clutch 68 PTO auxiliary transmission clutch 68a, 68b Gear 69 PTO shaft 70, 71, 71 a, 72, 73, 74 Gear 75 PTO transmission shaft 76, 77, 78, 79, 80 Gear 81, 83 Gear dock 84 PTO drive shaft 85 PTO auxiliary speed low speed gear 86 PTO auxiliary speed high speed gear 90 controller 90a EEPROM
91 Transmission case 92 Trunnion shaft 92a Position sensor 93 Trunnion shaft turning hydraulic cylinder 93a Piston rod 93c Arm 93d Turning shaft 93e, 93f Stopper 95 Link mechanism 95a Arm 95b Rod 95c Arm 95d Rod 95e Short arm 95f Boss 95g Plate 95h Link Arm 95j Cam 95j1 Recess 95k Fan-shaped member 95k1 Slot 95m Roller 95p Bolt 95q Shaft 95r Pin 95s Boss 95t Bolt 97 Clutch switch

Claims (2)

The hydrostatic continuously variable transmission (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92), and the output of the hydrostatic continuously variable transmission (34) are shifted to a plurality of speeds. A transmission including a meshing transmission (38) for changing to a stage and outputting;
A trunnion shaft turning hydraulic cylinder (93) for determining a turning angle of the trunnion shaft (92) of the hydrostatic continuously variable transmission (34);
A trunnion shaft position sensor (92a) that is provided between the trunnion shaft (92) and the hydraulic cylinder (93) and detects a rotational angle position of the trunnion shaft (92) by the operation of the hydraulic cylinder (93);
A speed change lever (20) for setting an operation amount of the trunnion shaft turning hydraulic cylinder (93);
A shift lever position sensor (20a) for detecting an operation position of the shift lever (20);
A storage means (90a) for storing the output value (T) of the current position of the shift lever position sensor (20a), the output value (A) of the minimum vehicle speed instruction position, and the output value (B) of the maximum vehicle speed instruction position;
The output value 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) is the first value calculated by the following equation (1). age,
Output ratio to hydraulic cylinder = (TA) / (AB) (1)
The magnitude of the detected value of the trunnion shaft position sensor (92a) obtained by operating the hydraulic cylinder (93) according to the first value obtained by the equation (1) is determined by the trunnion shaft position sensor (92a). A work comprising: a controller (90) obtained as a ratio to the size of the entire detection range and having the ratio as a second value so that the second value is equal to the first value. Vehicle travel control device. The hydrostatic continuously variable transmission (34) that outputs the power of the engine (5) by adjusting the rotation angle of the trunnion shaft (92), and the output of the hydrostatic continuously variable transmission (34) are shifted to a plurality of speeds. A transmission including a meshing transmission (38) for changing to a stage and outputting;
A trunnion shaft turning hydraulic cylinder (93) for determining a turning angle of the trunnion shaft (92) of the hydrostatic continuously variable transmission (34);
A link mechanism (95) for associating the rotation angle of the trunnion shaft (92) based on the operation amount of the hydraulic cylinder (93);
A trunnion shaft position sensor (92a) which is provided in the link mechanism (95) and detects the rotational angle position of the trunnion shaft (92) by the operation of the hydraulic cylinder (93);
A speed change lever (20) for setting an operation amount of the trunnion shaft turning hydraulic cylinder (93);
A stopper (93e) provided at the maximum extension setting position on the forward side of the piston rod (93a) provided in the trunnion shaft rotating hydraulic cylinder (93);
A stopper (93f) provided at a minimum shortening setting position on the reverse side of the piston rod (93a) of the trunnion shaft turning hydraulic cylinder (93);
The neutral position of the trunnion shaft (92) detected by the trunnion shaft position sensor (92a), the maximum extension set position on the forward side of the piston rod (93a) detected by the two stoppers (93e, 93f), and the reverse side Storage means for storing the minimum shortening setting position as a reference position;
A travel control device for a work vehicle, comprising: a controller (90) for controlling an operating range of a trunnion shaft turning hydraulic cylinder (93) by a shift lever (20) based on a value of the storage means.

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