JP6515044B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as a farm work machine such as a tractor and a combine, a special work machine such as a crane car and a backfour, for example.

  2. Description of the Related Art Conventionally, some working vehicles such as agricultural vehicles such as tractors and combines and construction machines such as crawler cranes are equipped with two hydraulic continuously variable transmissions (HST) to which power from the engine is transmitted. One type of continuously variable transmission is configured to output straight driving power and turning power based on the engine output. The applicant of the present invention previously proposed in Patent Document 1 a work vehicle that can be turned by combining the straight-ahead power and the turning power output from each of the two hydraulic continuously variable transmissions with the left and right planetary gear mechanisms. ing.

  In addition, some conventional work vehicles include a hydraulic mechanical transmission (HMT) having a transmission efficiency higher than that of a hydraulic continuously variable transmission in a transmission case to which power is transmitted from an engine. The applicant previously filed an in-line hydraulic mechanical transmission in which the hydraulic pump and the hydraulic motor were arranged in series such that the input shaft of the hydraulic pump and the output shaft of the hydraulic motor were concentrically located. Patent Document 2 proposes.

  In an in-line hydro-mechanical transmission, an output shaft is fitted rotatably on an input shaft to which power is transmitted from an engine. Furthermore, the hydraulic pump, the cylinder block and the hydraulic motor are fitted on the input shaft. The cylinder block independently serves both for the hydraulic pump and for the hydraulic motor, and power is transmitted from the hydraulic motor to the output shaft. For this reason, in a serial type hydraulic mechanical transmission, unlike a general hydraulic mechanical transmission, it is possible to combine hydraulic shift power and engine power without intervention of a planetary gear mechanism and to output high power. It has the advantage that transmission efficiency can be obtained.

Japanese Patent Application Laid-Open No. 2002-059753 Japanese Patent Application Laid-Open No. 2005-083497

  By the way, in order to mount the hydro-mechanical transmission in Patent Document 2 on a medium- or large-sized work vehicle, it is necessary to increase the output of the hydro-mechanical transmission. In order to increase the output of the hydro-mechanical transmission, for example, the capacity of the hydro-mechanical transmission can be increased. However, simply increasing the capacity of the hydraulic mechanical transmission not only increases the size of the hydraulic mechanical transmission itself and increases the manufacturing cost, but also sacrifices the power transmission efficiency (especially the efficiency in the low load range) There was a problem that.

  In addition, even when the mechanism in Patent Document 1 is mounted on a large work vehicle, the mechanism becomes larger as the output of the hydraulic continuously variable transmission increases, so that the weight of the work vehicle is not only increased, but also power transmission Since the efficiency is lower than that of the hydraulic mechanical transmission, the shift range in the straight direction (main shift range) is limited.

  Furthermore, although the swash plate angle of the pump swash plate in the hydraulic mechanical transmission that generates the turning power is switched by the control amount to the oil pressure switching valve, the control amount varies from transmission to transmission. Need to adjust before. By the way, when the above adjustment is performed in the factory, the work vehicle is supported on the adjustment stand, and the adjustment is performed with the traveling unit such as the crawler or the wheel floating. Therefore, even if the control amount is adjusted, when the work vehicle is actually driven in a field or on the road, the work vehicle's turning amount with respect to the steering angle is insufficient because the frictional force and the reaction force from the installation surface are received. In some cases, the operability of the operator may be uncomfortable.

  This invention makes it a technical subject to provide the work vehicle which examined and improved the present condition as mentioned above.

The work vehicle according to the present invention comprises an engine mounted on a traveling body, a linear movement transmission path having a first continuously variable transmission, and a turning transmission path having a second continuously variable transmission, and In a working vehicle that drives left and right traveling units by combining an output and an output of the turning system transmission path, a control unit that changes a swash plate angle of the second continuously variable transmission is the second continuously variable transmission. The control amount for swash plate control with respect to the swash plate angle is adjustable, and the control unit corrects the control amount measured by changing the swash plate angle when adjusting the control amount for swash plate control. The control amount after correction is stored as the control amount for swash plate control , and in the case of adjusting the control amount for swash plate control on an adjustment stand where the traveling portion is in a floating state, the swash plate The turning curvature of the traveling vehicle is increased to the controlled variable measured by changing the angle Giving amount of offset is to store as said swash plate controlling the control amount.

  In the work vehicle, when the control unit adjusts the control amount for swash plate control on the road on which the traveling unit is grounded, the control amount measured by changing the swash plate angle is used as the control amount for swash plate control. It may be stored.

  The work vehicle further includes a setting condition designation unit that designates whether the measurement condition at the time of executing the adjustment operation of the control amount for swash plate control is on the adjustment stand or on the road, and the control unit However, the control amount for swash plate control may be adjusted according to the measurement condition designated by the setting condition designation unit.

  The work vehicle includes an inclination detection sensor that measures an inclination state of the traveling machine body, and the control unit executes the adjustment operation of the control amount for controlling the swash plate based on a signal from the inclination detection sensor. It may be determined whether the measurement condition at time is on the adjustment stand or on the road, and the control amount for controlling the swash plate may be adjusted according to the determined measurement condition.

  In the work vehicle, the control unit determines, on the basis of the load factor of the engine, whether the measurement condition at the time of executing the adjustment operation of the control amount for controlling the swash plate is on the adjustment stand or on the road. The control amount for controlling the swash plate may be adjusted according to the determined measurement condition.

  In the work vehicle, the control unit is configured of a first control unit that controls an output of the straight traveling transmission path and a second control unit that controls an output of the turning transmission path. The second control unit receives the output of the straight movement transmission path set by the control unit to set the output of the turning transmission path, and the second control unit is configured to perform the second stepless movement. The control amount for the swash plate angle of the transmission may be adjusted.

  According to the present invention, since the measured control amount is corrected and stored when adjusting the control amount for swash plate control, the road surface with which the traveling portion contacts during traveling on the road regardless of the place to be adjusted. It is possible to execute the turning operation according to the state or the field condition. Further, according to the present invention, when the turning adjustment is performed on the adjustment stand, the measured amount of control is given an offset amount and stored as a control amount for swash plate control, so that the traveling portion contacts when traveling on the road. It is possible to execute the turning operation according to the road surface condition or the field condition. Therefore, since the traveling body can be turned in accordance with the steering angle at the steering wheel, the responsiveness to the operation of the steering wheel by the operator can be improved, and as a result, the driving operability can be improved.

  According to the present invention, the turning adjustment can be performed on the road, and when it is performed on the road, the measured control amount is stored as the control amount for swash plate control, so the turning operation adjusted to the road surface condition or the field condition is adjusted. it can. Therefore, even after shipment from the factory, the operator can execute turning adjustment on the road. For example, by performing turning adjustment on the road surface or field generally used by the operator, the turning operation can be performed according to the operator's operation feeling. This makes it possible to perform a more stable driving operation when turning.

  According to the present invention, by providing the setting condition designation unit, the place where the turning adjustment is performed can be specified with certainty, so the control amount for swash plate control to be stored after the turning adjustment can be set to the optimum value.

  According to the present invention, by making it possible to automatically detect the place where the turning adjustment is being performed, it is not necessary to specify the place where the turning adjustment is being performed, and the complexity of the work at the time of executing the turning adjustment. Can be eliminated. Further, by making the designation of the place by the operator unnecessary, it is possible to prevent the storage of the improper control amount for swash plate control due to the operation mistake by the operator or the like.

It is a left side view of a tractor. It is a right side view of a tractor. It is a top view of a tractor. It is a left side view of a run body. It is a right side view of a run body. It is a top view of a run body. It is a plane explanatory view of a control seat part. It is a perspective view showing the composition around a steering wheel. It is a perspective view which shows the connection structure of a brake mechanism and a brake pedal. It is an explanatory view showing the relation between the amount of hydraulic fluid discharge of a hydraulic mechanical transmission, and the vehicle speed. It is a skeleton diagram of a power transmission system of a tractor. It is a hydraulic-circuit figure of a tractor. It is a block diagram showing composition of a control system of a tractor. It is a block explanatory view showing composition of a run control system of a tractor. It is explanatory drawing which shows the relationship of the parameter memorize | stored in the deceleration rate table and the turning / straight advance ratio table. It is a flowchart which shows travel control of a tractor. It is explanatory drawing which shows the relationship between the steering angle of the steering wheel in spin-turn mode, and the vehicle speed of a tractor. It is explanatory drawing which shows the relationship between the steering angle of the steering wheel in a brake turn mode, and the vehicle speed of a tractor. It is explanatory drawing which shows the relationship between the steering angle of the steering wheel in a slow turning turn mode, and the vehicle speed of a tractor. It is a flowchart which shows turning adjustment control. It is a flowchart which shows another example (2nd example) of turning adjustment control. It is a flowchart which shows another example (3rd example) of turning adjustment control.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 6, the traveling machine body 2 of the tractor 1 is supported by a pair of traveling crawlers 3 as a traveling portion. A diesel engine 5 (hereinafter simply referred to as an engine) is mounted on a front portion of the traveling body 2, and the tractor 1 is configured to travel forward and backward by driving the traveling crawler 3 by the engine 5. The engine 5 is covered by a bonnet 6. A cabin 7 is installed on the upper surface of the traveling body 2. Inside the cabin 7 are disposed a steering seat 8 and a steering handle 9 for steering the traveling crawler 3. At the left and right outer sides of the cabin 7, steps 10 for getting on and off by the operator are provided. A fuel tank 11 for supplying fuel to the engine 5 is provided on the left and right lower sides of the cabin 7, and the fuel tank 11 is covered by left and right rear fenders 21. A battery 817 for supplying power to the front of the fuel tank 11 is provided on the left side of the cabin 7 and is covered by the left rear fender 21 together with the fuel tank 11.

  The traveling vehicle 2 is configured by an engine frame 14 having a front bumper 12 and a transmission case (drive axle) 13 for turning, and left and right vehicle frames 15 detachably fixed to the rear of the engine frame 14. The axle 16 is rotatably protruded outward from the left and right ends of the turning transmission case 13, and an axle case 90 covering the axle 16 is provided on the left and right sides of the turning transmission case 13. Drive sprockets 62 are attached to the left and right ends of the turning transmission case 13 via axles 16. The rear portion of the machine body frame 15 is connected to a straight transmission case 17 for transmitting the rotational power from the engine 5 to the drive sprocket 62 by appropriately shifting the rotational power.

  As shown in FIGS. 1 to 4, the left and right track frames 61 are disposed on the lower surface side of the traveling body 2. The track frame 61 extends in the front-rear direction and is provided as a pair on the left and right sides, and is positioned on the outer sides of the engine frame 14 and the machine body frame 15. The left and right track frames 61 are connected to the engine frame 14 and the airframe frame 15 by lower frames 67 extending in the left-right direction. The front ends of the left and right track frames 61 are connected to an axle case 90 provided on the left and right sides of the turning transmission case 13. At the outside of each of the left and right track frames 61, a step 10a on which the operator gets on and off is provided.

  The left and right center portions of the lower frame 67 are fixed to the rear side surface of the engine frame 14 via the connection bracket 72. The left and right ends of a beam frame 68 extended in the left-right direction are connected to the front and rear middle portions of the left and right track frames 61. Further, the center of the beam frame 68 is connected to the center of the lower frame 67 via a reinforcing frame 70 provided in the front-rear direction. The rear beams 73 projecting inward at the rear of the left and right track frames 61 are connected to the rear housing 74 fixed on the left and right sides of the straight transmission case 17 so that the rear of the track frame 61 corresponds to the left and right sides of the straight transmission case 17 Fix it.

  The track frame 61 includes a drive sprocket 62 for transmitting the motive power of the engine 5 to the traveling crawler 3, a tension roller 63 for maintaining the tension of the traveling crawler 3, and a plurality of track rollers for holding the ground side of the traveling crawler 3 in a grounded state. An intermediate roller 65 for holding the non-grounded side of the traveling crawler 3 is provided. The drive sprocket 62 supports the front side of the traveling crawler 3, the tension roller 63 supports the rear side of the traveling crawler 3, the track roller 64 supports the grounded side of the traveling crawler 3, and the intermediate roller 65 does not support the traveling crawler 3. Support the ground side. The tension roller 63 is rotatably supported by the rear end of a tension frame 69 which is configured to be extensible and contractible rearward from the rear end of the track frame 61. The track roller 64 is rotatably supported at the front and rear of the equalizer frame 71 supported at the lower part of the track frame 61 so as to be able to swing back and forth.

  Further, a front dozer 80 is configured to be attachable to the front of the tractor 1. A pair of left and right dozer brackets 81 are fixed to the front side of the engine frame 14, the axle case 90 and the lower frame 67, and the U-shaped (U-shaped) support arms 83 of the front dozer 80 are left and right. It is detachably pivoted to the outside (airside) of the dozer bracket 81. The left and right dozer brackets 81 are connected to the side surfaces of the left and right engine frames 14 at the front end inner side (inboard side), and are connected to the upper surface of the lower frame 67 midway portion at the rear end, and the midway portion is the axle case 90 midway portion It is connected so as to be held at the top and bottom. The dozer bracket 81 is firmly fixed to the engine frame 14, the axle case 90, and the lower frame 67, so that the strength which can withstand heavy work by the front dozer 80 can be secured.

  A hydraulic lift mechanism 22 for moving up and down the ground work machine 18 such as a rotary tiller, for example, is detachably mounted on the rear portion of the straight transmission case 17. The ground work machine 18 is connected to the rear of the straight transmission case 17 via a three-point link mechanism 111 consisting of a pair of lower links 23 and a top link 24 on the left and right. A PTO shaft 25 for transmitting a PTO driving force to the ground work machine 18 is provided to project rearward on the rear side surface of the straight transmission case 17.

  As shown in FIGS. 4 to 6, a flywheel 26 is attached directly to the rear end of the output shaft (piston rod) 5a of the engine 5 projecting rearward from the rear side surface of the engine 5. The main driving shaft 27 protruding backward from the flywheel 26 and the input counter shaft 28 protruding forward from the front side of the straight transmission case 17 are connected via a power transmission shaft 29 having free shaft joints at both ends. . A straight forward input counter that protrudes backward from the turning transmission case 13 via a power transmission shaft 31 having free shaft joints at both ends on a straight forward output shaft 30 that protrudes forward from the lower front of the straight forward transmission case 17 The shaft 508 is connected. An output shaft (piston rod) 5a at the front end of the engine 5, which projects forward from the front side of the engine 5, projects rearward from the turning transmission case 13 via a power transmission shaft 711 having universal shaft joints at both ends. A turning input counter shaft 712 is connected.

  As shown in FIGS. 1 to 6, the hydraulic lifting mechanism 22 lifts the fulcrum to the upper surface lid of the left and right hydraulic lift cylinders 117 which are operated and controlled by the operation of the working part position dial 51 etc. The left and right lift arms 120 pivotally support the proximal end side via a shaft and the left and right lift rods 121 connecting the left and right lift arms 120 to the left and right lower links 23 are provided. A part of the right lift rod 121 is formed by a horizontal cylinder 122 for hydraulic pressure control, and the length of the right lift rod 121 is configured to be adjustable by extension and contraction by the horizontal cylinder 122. In a state where the ground work machine 18 is supported by the top link 24 and the lower links 23 on the left and right, the piston of the horizontal cylinder 122 is extended and contracted to change the length of the right lift rod 121. The inclination angle is configured to change.

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. 7 to 9 and the like. A steering column 32 is disposed in front of the steering seat 8 in the cabin 7. The steering column 32 is erected in such a manner as to be embedded on the back side of the dashboard 33 disposed on the front side inside the cabin 7. A steering handle 9 having a substantially round shape in plan view is attached to the upper end side of a handle shaft 921 that protrudes upward from the top surface of the steering column 32. A steering angle (steering wheel turning angle) detection mechanism 880 including a steering angle sensor 821 for detecting the steering angle of the steering wheel 9 is connected to the lower end of the steering wheel shaft 921 in the steering column 32.

  On the right side of the steering column 32, a working machine lift lever 34 for moving the hydraulic lifting mechanism 22 up and down, and a brake pedal 35 for braking the traveling machine 2 are disposed. On the left side of the steering column 32, the forward / reverse switching lever 36 (reverser lever) for switching the traveling direction of the traveling vehicle 2 between forward and reverse, and the hydraulic clutches 537, 539, 541 for power disconnection are disconnected. A clutch pedal 37 for operation is disposed. On the rear side of the steering column 32, a parking brake lever 43 for holding the brake pedal 35 in a depressed position is disposed.

  An erroneous operation preventing body 38 (reverser guard) extending along the forward and reverse travel switching lever 36 is disposed below the forward and reverse travel switching lever 36 on the left side of the steering column 32. By arranging the erroneous operation preventing body 38, which is a contact preventing tool, below the forward / reverse switching lever 36, when the user gets on / off the tractor 1, the operator is prevented from inadvertently contacting the forward / reverse switching lever 36. On the back upper side of the dashboard 33, an operation display panel 39 incorporating a liquid crystal panel is provided.

  An accelerator pedal 41 for controlling the rotational speed or the vehicle speed of the engine 5 is disposed on the right side of the steering column 32 in the floor plate 40 in front of the steering seat 8 in the cabin 7. Note that substantially the entire top surface of the floor plate 40 is formed flat. Side columns 42 are disposed on the left and right sides of the control seat 8. Between the control seat 8 and the left side column 42, an ultra low speed lever 44 (creep lever) for forcibly and significantly reducing the traveling speed (vehicle speed) of the tractor 1, and a traveling auxiliary shift in the straight transmission case 17 An auxiliary transmission lever 45 for switching the output range of the gear mechanism and a PTO transmission lever 46 for switching the driving speed of the PTO shaft 25 are disposed.

  Between the control seat 8 and the right side column 42, there is provided an arm rest 49 for mounting the arm and elbow of the operator seated on the control seat 8. The arm rest 49 is configured separately from the control seat 8, and the main shift lever 50 for increasing and decreasing the traveling speed of the tractor 1 and the dial for manually changing and adjusting the height position of the ground work machine 18 such as a rotary tiller. A working unit position dial 51 (lifting dial) of the formula and a work implement lifting switch 57 for lifting and lowering the hydraulic lifting mechanism 22 are provided. The arm rest 49 is configured to be able to flip up and rotate in multiple stages with the lower end of the rear end as a fulcrum. Further, in the present embodiment, the vehicle speed of the traveling machine body 2 increases when the main shift lever 50 is tilted forward, while the vehicle speed of the running body 2 decreases when the main shift lever 50 is tilted backward. Further, the armrest 49 is provided with a potentiometer (variable resistor) type main shift sensor 822 (see FIG. 13) for detecting the forward and backward tilting of the main shift lever 50.

  The right side column 42 has an operation monitor 55 having a touch panel function and capable of instructing each part of the tractor 1 in order from the front side, a throttle lever 52 for setting and holding the rotational speed of the engine 5, and a PTO shaft 25 PTO clutch switch 53 for switching power transmission from the to the ground work machine 18 such as a rotary cultivator, and a plurality of hydraulic pressure for switching the hydraulic external takeout valve 430 disposed on the upper surface side of the straight transmission case 17 An operation lever 54 (SCV lever) and a single double acting changeover switch 56 for switching the double acting valve mechanism 431 disposed on the front surface of the rear housing 74 are disposed. Here, the hydraulic pressure extraction valve 430 is for supplying and controlling hydraulic oil to hydraulic equipment of another working machine such as a front loader attached to the tractor 1 later. The double acting valve mechanism 431 is for operating the hydraulic lift cylinder 117 in a double acting manner by operating in conjunction with the lift valve mechanism 652 disposed on the upper surface side of the straight transmission case 17.

  Next, the relationship between the brake pedal 35 and the brake mechanism 751 will be described mainly with reference to FIGS. 8 and 9. In front of the steering column 32, a brake pedal support bracket 916 for supporting the brake pedal shaft 755 is fixed to the back surface of the board support plate (air cut plate) 901 (the steering seat 8 side). The base end boss portion 35 a of the brake pedal 35 is fitted on the brake pedal shaft 755, and the base end boss portion 35 a of the brake pedal 35 is connected to rotate integrally with the brake pedal shaft 755.

  A forwardly projecting pedal shaft arm 756 is fixed to both ends of the brake pedal shaft 755, and the pedal shaft arm 756 rotates with the brake pedal shaft 755. The base end boss of the clutch pedal 37 is also rotatably fitted on the brake pedal shaft 755. A clutch position sensor 829 (see FIG. 13) and a brake position sensor 828 are fixed to the left and right ends of the brake pedal shaft 755, respectively. The brake switch 851 is disposed at a position facing the pedal arm 35b of the brake pedal 35, and the clutch switch 852 (see FIG. 13) is disposed at a position facing the pedal arm 37b of the clutch pedal 37.

  On the left and right lower sides of the board support plate (air cut plate) 901, a pair of left and right brake operation shafts 757 are supported. A link boss body 758 connected to the braking arm 752 of the brake mechanism 751 in the turning transmission case 13 is rotatably fitted on the left brake operation shaft 757. Link arm 759 provided on the outer peripheral surface of link boss 758, lower end of vertically extending link rod 762 connected to left pedal shaft arm 756, and two-stage expansion and contraction in which braking operation of brake mechanism 751 is stepwise The upper end of the link body 763 is connected. The lower end of the two-stage telescopic link body 763 is connected to the tip of the link arm 767 at the rear end of the brake rod 766. The brake rod 766 is supported by link support brackets 764 and 765 fixed to the engine frame 14 and extends in the front-rear direction. The link arm 768 at the front end of the brake rod 766 is connected to the braking arm 752 of the brake mechanism 751 in the turning transmission case 13 via the connection plate 753.

  That is, the left end of the brake pedal shaft 755 is connected to the brake arm 752 of the brake mechanism 751 via the link rod 762, the two-stage telescopic link body 763, and the brake rod 766. Therefore, as the brake pedal shaft 755 is rotated as the brake pedal 35 is depressed, the braking arm 752 can be rotated, and the braking operation by the brake mechanism 751 can be performed. At this time, when the step amount of adjusting the traveling speed is small due to the action of the two-stage expansion / contraction link body 763 as compared with the case where there is a small amount of depression (play area of the brake mechanism 751) In the braking region), the depression force on the brake pedal 35 becomes large.

  A link boss body 760 having a link arm 761 is rotatably fitted on the right brake operation shaft 757. The upper end of a two-stage telescopic link body 769 for stepping on the brake pedal 35 is connected to the right pedal shaft arm 756, and a two-stage link arm 761 is provided protruding on the outer peripheral surface of the link boss 760. The lower end of the expandable link body 769 is connected. When the brake operation shaft 757 is turned in accordance with the depression of the brake pedal 35, the two-step telescopic link body 769 acts, whereby the amount of depression for adjusting the traveling speed is small (compared to the play area of the brake mechanism 751). When the amount of depression applied suddenly is large (the braking area by the brake mechanism 751), the depression force on the brake pedal 35 becomes large.

  The parking brake lever 43 is connected to one end of the locking member 771 via the parking brake arm 770. The side view bow shaped locking member 771 is pivoted to the brake pedal support bracket 916. On the left side surface of the pedal arm 35b of the brake pedal 35, a locking plate 775 to be engaged with the locking claw of the locking member 771 is provided. As a result, by operating the parking brake lever 43 in a state where the brake pedal 35 is depressed, the locking member 771 is locked to the locking plate 775, and the braking state (parked state) of the tractor 1 is maintained.

  Next, the internal structure of the transmission case 17 for going straight and the transmission case 13 for turning and the power transmission system of the tractor 1 will be described mainly with reference to FIGS. 4 to 6, 10 and 11. FIG. In the front chamber of the transmission case 17 for linear movement, a mechanical creep transmission gear mechanism 502 for shifting rotational power via a hydraulic mechanical continuously variable transmission 500 for linear movement and a forward-reverse switching mechanism 501 to be described later A transmission gear mechanism 503 is disposed. A forward / reverse switching mechanism 501 for switching the rotational power from the hydraulic mechanical continuously variable transmission 500 in the forward or reverse direction is disposed in the intermediate chamber of the straight transmission case 17. A PTO transmission mechanism 505 is disposed in the rear room of the straight transmission case 17 for appropriately shifting the rotational power from the engine 5 and transmitting it to the PTO shaft 25. The creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503 correspond to a traveling transmission gear mechanism that performs multi-speed shifting of the transmission output via the forward / reverse switching mechanism 501. A pump case 480 containing a working machine hydraulic pump 481 and a traveling hydraulic pump 482 driven by the rotational power of the engine 5 is attached to the front right side of the straight transmission case 17.

  A flywheel 26 is directly connected to an output shaft 5 a of the engine 5 protruding rearward from the rear side surface of the engine 5. An input countershaft 28 projecting forward from the front side of the straight transmission case 17 is connected to a main driving shaft 27 projecting backward from the flywheel 26 via a power transmission shaft 29 having a universal shaft joint at both ends. The rotational power of the engine 5 is transmitted to the input counter shaft 28 of the transmission case 17 for straight advance via the main driving shaft 27 and the power transmission shaft 29, and the hydraulic mechanical continuously variable transmission 500 and the creep transmission gear mechanism 502 or the traveling The transmission gear mechanism 503 appropriately shifts the gear. The transmission power via the creep transmission gear mechanism 502 or the travel auxiliary transmission gear mechanism 503 is transmitted to the gear mechanism in the turning transmission case 13 via the straight output shaft 30, the power transmission shaft 31, and the straight input counter shaft 508. It is transmitted.

  The hydraulic mechanical type continuously variable transmission (HMT) 500 for straight advance has the main transmission output shaft 512 concentrically arranged on the main transmission input shaft 511, and the hydraulic pump portion 521, the cylinder block and the hydraulic motor portion 522 are connected in series. It is a serial type (inline type) arranged in A main transmission input gear 513 is fitted on the rear end side of the input counter shaft 28 so as not to allow relative rotation. On the rear end side of the main shift input shaft 511, an input transmission gear 514 which is always meshed with the main shift input gear 513 is fixed. Therefore, the rotational power of the input counter shaft 28 is transmitted to the hydraulic mechanical continuously variable transmission 500 via the main transmission input gear 513, the input transmission gear 514 and the main transmission input shaft 511. A main transmission high-speed gear 516, a main transmission reverse gear 517, and a main transmission low-speed gear 515 are fitted on the main transmission output shaft 512 such that relative rotation is not possible. The input side of the main shift input shaft 511 and the output side of the main shift output shaft 512 are located on the same side (the rear side as viewed from the hydraulic mechanical continuously variable transmission 500).

  The hydraulic mechanical continuously variable transmission 500 includes a variable displacement hydraulic pump unit 521 and a fixed displacement hydraulic motor unit 522 operated by high pressure hydraulic fluid discharged from the hydraulic pump unit 521. The hydraulic pump portion 521 is provided with a pump swash plate 523 capable of changing the inclination angle with respect to the axis of the main shift input shaft 511 to adjust the hydraulic oil supply amount. The pump swash plate 523 is interlocked with a main shift hydraulic cylinder 524 for changing and adjusting the inclination angle of the pump swash plate 523 with respect to the axis of the main shift input shaft 511. In the embodiment, the main transmission hydraulic cylinder 524 is assembled to the hydraulic mechanical continuously variable transmission 500, and is unitized as one member.

  When the main shift hydraulic cylinder 524 is driven in proportion to the operation amount of the main shift lever 50, the inclination angle of the pump swash plate 523 with respect to the axis of the main shift input shaft 511 is changed accordingly. The pump swash plate 523 according to the embodiment adjusts the angle within a range between one (positive) maximum inclination angle and the other (negative) maximum inclination angle across a neutral angle of approximately zero inclination (the zero before and after the zero). It is possible, and when the traveling vehicle 2 is at the lowest speed, it is set to an angle inclined to either one (in this case, an inclination angle near the maximum and at the maximum).

  When the inclination angle of the pump swash plate 523 is substantially zero (neutral angle), the hydraulic pump unit 521 does not push and pull the input side plunger group. Although the cylinder block rotates in the same direction and at substantially the same rotational speed as the main shift input shaft 511, no hydraulic oil is supplied from the hydraulic pump portion 521, so the output side plunger group of the cylinder block and hence the hydraulic motor portion 522 are not driven. The main shift output shaft 512 rotates at substantially the same rotational speed as the main shift input shaft 511.

  Next, the switching structure between forward and reverse performed through the forward and reverse switching mechanism 501 will be described. On the rear side of the input counter shaft 28, a planetary gear mechanism 526 which is a forward high speed gear mechanism and a low speed gear pair 525 which is an forward low speed gear mechanism are disposed. The planetary gear mechanism 526 includes a sun gear 531 that rotates integrally with the input transmission gear 529 rotatably supported on the input counter shaft 28, and a carrier 532 that rotatably supports a plurality of planetary gears 533 on the same radius. And a ring gear 534 having internal teeth on the inner circumferential surface. The sun gear 531 and the ring gear 534 are rotatably fitted on the input counter shaft 28. The carrier 532 is fitted on the input counter shaft 28 in a non-rotatable manner. The sun gear 531 meshes with the planet gears 533 of the carrier 532 from the inner radius. Further, the internal teeth of the ring gear 534 mesh with the respective planetary gears 533 from the radially outer side. An output side transmission gear 530 integrally rotating with the ring gear 534 is also rotatably supported on the input counter shaft 28. The input-side low-speed gear 527 and the output-side low-speed gear 528 that constitute the low-speed gear pair 525 are integrally formed, and can rotate between the planetary gear mechanism 526 and the main shift input gear 513 of the input counter shaft 28 It is supported.

  A traveling relay shaft 535 and a traveling transmission shaft 536 extending in parallel with the input counter shaft 28, the main shift input shaft 511 and the main shift output shaft 512 are disposed in the straight transmission case 17. A forward / reverse switching mechanism 501 is provided on a traveling relay shaft 535 as a transmission shaft. That is, the traveling relay shaft 535 is provided with a forward high speed gear 540 connected by a wet multiplate type forward high speed hydraulic clutch 539, a reverse gear 542 connected by a wet multiplate type reverse hydraulic clutch 541, and a wet multiplate A forward low speed gear 538 connected by a forward low speed hydraulic clutch 537 of a mold is fitted. A traveling relay gear 543 is fitted non-rotatably between the forward high-speed hydraulic clutch 539 and the reverse gear 542 in the traveling relay shaft 535. A traveling transmission gear 544 always meshing with the traveling relay gear 543 is fitted on the traveling transmission shaft 536 such that relative rotation is not possible. The main transmission low speed gear 515 of the main transmission output shaft 512 is constantly meshed with the input low speed gear 527 of the low speed gear pair 525 on the input countershaft 28 side, and the output low speed gear 528 is always meshed with the forward low speed gear 538. The main transmission high speed gear 516 of the main transmission output shaft 512 always meshes with the input transmission gear 529 of the planetary gear mechanism 526 located on the input countershaft 28 side, and the output transmission gear 530 always meshes with the forward high speed gear 540. The main transmission reverse gear 517 of the main transmission output shaft 512 always meshes with the reverse gear 542.

  When the forward / reverse switching lever 36 is operated to the forward side, the forward low-speed hydraulic clutch 537 or the forward high-speed hydraulic clutch 539 is in a power connection state, and the forward low-speed gear 538 or the forward high-speed gear 540 and the traveling relay shaft 535 are connected relatively nonrotatably Be done. As a result, forward low speed or forward high speed rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the low speed gear pair 525 or the planetary gear mechanism 526, and power from the traveling relay shaft 535 to the traveling transmission shaft 536 It is transmitted. When the forward / reverse switching lever 36 is operated to the reverse side, the reverse hydraulic clutch 541 is in a power connection state, and the reverse gear 542 and the traveling relay shaft 535 are coupled so as to be relatively non-rotatable. As a result, the rotational power of reverse travel is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the main transmission reverse gear 517 and the reverse gear 542, and the power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536.

  The forward low speed hydraulic clutch 537 or the forward high speed hydraulic clutch 539 is determined to be in the power connection state by the forward operation of the forward / reverse switching lever 36 in accordance with the operation amount of the main shift lever 50. Further, when the forward / reverse switching lever 36 is in the neutral position, all the hydraulic clutches 537, 539, 541 are in the power disconnection state, and the traveling drive force from the main shift output shaft 512 is substantially zero (the main clutch disconnection state )become. Here, FIG. 10 shows the relationship between the hydraulic oil discharge amount (the inclination angle of the pump swash plate 523) of the hydraulic mechanical continuously variable transmission 500 and the vehicle speed of the tractor 1. In the embodiment, when the main shift lever 50 is operated to be neutral regardless of the operation state of the forward / reverse switching lever 36, the pump swash plate 523 is negative and the tilt angle near the maximum by reverse drive of the main shift hydraulic cylinder 524 (See white circle), and the main shift output shaft 512 and the traveling relay shaft 535 are in the lowest speed rotation state (approximately zero). As a result, the vehicle speed of the tractor 1 becomes substantially zero.

  When the main shift lever 50 is operated from neutral to medium speed by the drive of the main shift hydraulic cylinder 524, the pump swash plate 523 is negative and maximum when the main shift lever 50 is operated from the neutral position to the middle speed while the forward / reverse selector lever 36 is moved forward. It changes from the inclination angle in the vicinity (reverse rotation inclination angle) to the positive and maximum inclination angle (forward rotation inclination angle) through zero (see open square marks), and from the hydraulic motor unit 522 to the main shift output shaft 512 Increase the speed of the gear shift from approximately zero to high speed. At this time, the forward low-speed hydraulic clutch 537 is in a power connection state, and the forward low-speed gear 538 or the forward high-speed gear 540 and the traveling relay shaft 535 are connected so as not to be relatively rotatable. As a result, the rotational power of forward low speed is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the low speed gear pair 525, and the traveling relay shaft 535 rotates at the lowest speed by the accelerating power to the main transmission output shaft 512. It changes from the state to the forward intermediate speed rotation state (refer to the forward low speed range FL). Then, power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536.

  When the main shift lever 50 is operated to accelerate from the intermediate speed to the maximum speed in a state where the forward / reverse switching lever 36 is operated to the forward side, the inclination angle near positive and at the maximum by driving the main shift hydraulic cylinder 524 The pump swash plate 523 changes its power from the hydraulic motor section 522 to the main shift output shaft 512 from high speed from (the normal rotation inclination angle) to a negative and maximum inclination angle (reverse rotation inclination angle) through zero through zero. Slow down to approximately zero. At this time, the forward high-speed hydraulic clutch 539 is in a power connection state, and the forward high-speed gear 540 and the traveling relay shaft 535 are coupled so as not to be relatively rotatable. As a result, forward high-speed rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the planetary gear mechanism 526. That is, after the power from engine 5 and the decelerating power to main transmission output shaft 512 are combined in planetary gear mechanism 526, traveling relay shaft 535 is rotated from the forward intermediate speed rotation state to the maximum forward speed rotation state by the combined power. Change (see forward high speed zone FH). Then, power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536. The traveling body 2 is at the highest speed.

  When the main transmission lever 50 is operated from neutral to acceleration while the forward / reverse switching lever 36 is operated to the reverse side, the pump swash plate 523 is negative by the drive of the main transmission hydraulic cylinder 524 and the inclination angle near the maximum It changes from (reverse rotation inclination angle) to a positive and maximum inclination angle (forward rotation inclination angle) through zero, and accelerates the shift power from the hydraulic motor 522 to the main transmission output shaft 512 from substantially zero to high speed Let At this time, the reverse hydraulic clutch 541 is in a power connection state, and the reverse gear 542 and the traveling relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the rotational power of reverse travel is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the main transmission reverse gear 517 and the reverse gear 542, and the traveling relay shaft 535 is accelerated by the main transmission output shaft 512. Changes from the lowest speed rotation state to the reverse high speed rotation state (see reverse range R). Then, power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536.

  Next, the switching structure between ultra low speed, low speed and high speed which is executed via the creep transmission gear mechanism 502 which is a traveling transmission gear mechanism and the traveling auxiliary transmission gear mechanism 503 will be described. A mechanical creep transmission gear mechanism 502 and a traveling auxiliary transmission gear mechanism 503 for shifting rotational power via the forward / reverse switching mechanism 501, and a traveling counter coaxially extending with the traveling transmission shaft 536 in the transmission case 17 for linear movement. A shaft 545 and an auxiliary transmission shaft 546 extending parallel to the traveling counter shaft 545 are disposed.

  A transmission gear 547 and a creep gear 548 are provided on the rear side of the traveling countershaft 545. The transmission gear 547 rotatably fits on the traveling counter shaft 545 and is coupled to the traveling transmission shaft 536 so as to rotate integrally therewith. The creep gear 548 is rotatably fitted on the traveling counter shaft 545. Between the transmission gear 547 and the creep gear 548 of the travel counter shaft 545, a creep shifter 549 is spline-fit so as to be relatively non-rotatable and to be slidable in the axial direction. By turning on and off the ultra low speed lever 44, the creep shifter 549 slides and the transmission gear 547 and the creep gear 548 are alternatively connected to the traveling counter shaft 545. A reduction gear pair 550 is rotatably fitted on a portion of the auxiliary transmission shaft 546 in the front chamber. The input side reduction gear 551 and the output side reduction gear 552 constituting the reduction gear pair 550 are integrally formed, and the transmission gear 547 of the travel counter shaft 545 is always meshed with the input side reduction gear 551 of the auxiliary transmission shaft 546 The creep gear 548 is constantly meshed with the output side reduction gear 552.

  A low speed relay gear 553 and a high speed relay gear 554 are provided on the front side of the traveling countershaft 545. The low speed relay gear 553 is fixed to the traveling counter shaft 545. The high speed relay gear 554 is fitted on the traveling counter shaft 545 so as not to be relatively rotatable. A low speed gear 555 meshing with the low speed relay gear 553 and a high speed gear 556 meshing with the high speed relay gear 554 are rotatably fitted on the auxiliary transmission shaft 546 on the front side of the reduction gear pair 550. Between the low speed gear 555 and the high speed gear 556 of the auxiliary transmission shaft 546, the auxiliary transmission shifter 557 is spline-fit so as to be non-relatively rotatable and slidably in the axial direction. By operating the sub shift lever 45, the sub shift shifter 557 slides, and the low speed gear 555 and the high speed gear 556 are alternatively connected to the sub shift shaft 546. An intermediate position between the low speed gear 555 and the high speed gear 556 is an auxiliary shift neutral position in which the low speed gear 555, the high speed gear 556, and the auxiliary shift shifter 557 are disconnected.

  Furthermore, a relay shaft for straight drive 568 and a straight drive shaft 30 extending in parallel with the traveling counter shaft 545 and the auxiliary transmission shaft 546 are disposed. A driven gear 570 fitted non-rotatably to the relay shaft 568 for rectilinear advance is always meshed with the main moving gear 569 fitted non-rotatably to the front end side of the auxiliary transmission shaft 546. The straight advance output gear 583 fitted to the straight advance output shaft 30 non-rotatably is engaged with the straight advance relay gear 582 fitted non-rotatably to the rear end side of the straight advance relay shaft 568.

  The main transmission gear 569 of the auxiliary transmission shaft 546, the driven gear 570 and the relay relay gear 582 for the linear movement relay shaft 568, and the linear output gear 583 of the output shaft 30 for linear movement rotate the auxiliary transmission shaft 456 straight. A straight forward output gear mechanism 509 for transmitting power to the output shaft 30 is configured. The straight-ahead output gear mechanism 509 is provided with a straight-ahead pickup rotation sensor (straight-ahead vehicle speed sensor) 823. The straight-ahead pickup rotation sensor 823 is configured to detect the number of rotations of a linear output (straight vehicle speed). For example, the rectilinear advance pickup rotation sensor 823 is disposed opposite to the rectilinear relay gear 582, and the number of revolutions of the rectilinear output (straight vehicle speed) is detected from the number of revolutions of the rectilinear relay gear 582.

  In the embodiment, creep gear 548 is connected to travel counter shaft 545 so as not to be able to rotate relative to travel counter shaft 545 when super low speed lever 44 is operated while secondary transmission lever 45 is operated to the low speed side. Relatively non-rotatably connected, the traveling drive force at an extremely low speed is output from the output shaft 30 for straight traveling toward the transmission case 13 for turning. When the ultra low speed lever 44 is turned off and the sub transmission lever 45 is operated to the low speed side, the transmission gear 547 is connected non-rotatably to the travel counter shaft 545 and the low speed gear 555 can not be rotated relative to the sub transmission shaft 546 The traveling drive force at an extremely low speed is output to the turning transmission case 13 from the straight output shaft 30. When the ultra low speed lever 44 is turned off and the sub transmission lever 45 is operated to the high speed side, the transmission gear 547 is connected to the traveling counter shaft 545 so as not to be relatively rotatable, and the high speed gear 556 is not allowed to relatively rotate to the sub transmission shaft The traveling driving force having a higher speed than that of the straight output shaft 30 is output to the turning transmission case 13. Further, when the auxiliary transmission lever 45 is operated to the neutral position, the auxiliary transmission shaft 546, the low speed gear 555 and the high speed gear 556 are disconnected, and the power from the traveling transmission shaft 536 is interrupted by the traveling auxiliary transmission gear mechanism 503. .

  The power transmission shaft 31 connects the straight forward input counter shaft 508 that projects backward from the turning transmission case 13 and the straight forward output shaft 30 that projects forward from the lower front of the straight mission case 17. The transmission case 13 for turning includes a hydraulic stepless transmission (HST) 701 for turning that appropriately changes rotational power from the engine 5, and rotation of the output from the hydraulic stepless transmission 701 to the left and right traveling crawlers 3 ( A differential gear mechanism 702 for transmitting to the drive sprocket 62) and a pair of left and right planetary gear mechanisms 703 for combining the rotational power from the differential gear mechanism 702 and the rotational power from the straight transmission case 17 are provided.

  The hydraulic continuously variable transmission 701 has a pair of hydraulic pump units 704 and hydraulic motor units 705 arranged in parallel, and the power transmitted to the pump shaft 706 causes the hydraulic pump units 704 to the hydraulic motor units 705. Hydraulic oil is fed appropriately. In addition, a charge pump 707 for supplying hydraulic oil to the hydraulic pump unit 704 and the hydraulic motor unit 705 is attached to the pump shaft 706. The turning hydraulic CVT 701 changes and adjusts the inclination angle of the pump swash plate 708 in the hydraulic pump unit 704 to change the discharge direction and discharge amount of the hydraulic fluid to the hydraulic motor unit 705, thereby achieving hydraulic pressure. The rotation direction and the number of rotations of the motor shaft 709 protruding from the motor unit 705 are arbitrarily adjusted.

  The turning transmission case 13 arranges the turning input counter shaft 712 in parallel with the pump shaft 706 of the hydraulic pump unit 704, and the turning input gear 713 is fitted on the turning input counter shaft 712 so that relative rotation is not possible. ing. A turning relay shaft 714 is disposed parallel to the turning input counter shaft 712 and the pump shaft 706 between the turning input counter shaft 712 and the pump shaft 706, and the turning is always meshed with the turning input gear 713. The relay gear 715 is fitted to the turning relay shaft 714 so as not to be rotatable relative to the turning relay shaft 714. The pump input gear 710 constantly meshed with the turning relay gear 715 is fitted on the pump shaft 706 so as to be non-relatively rotatable, and the rotational power from the engine 5 transmitted to the turning input counter shaft 712 turns It is transmitted to the pump shaft 706 via the relay shaft 714.

  A differential gear mechanism 702 is constituted by a bevel gear mechanism in which a pair of left and right side gears 717 are engaged on both sides of a pinion gear 716 which is fitted to the rear end of the motor shaft 709 so as not to relatively rotate in the turning transmission case 13. There is. Further, the differential gear mechanism 702 extends in the left and right directions a pair of left and right turning output shafts 718 in which the side gear 717 is fitted at one end so as not to allow relative rotation. At the other end of each of the pair of left and right turning output shafts 718, a turning output gear 719 for transmitting power to the pair of left and right planetary gear mechanisms 703 is fitted in a relatively non-rotatable manner.

  The rotational power (pivotal rotational power) from the hydraulic motor unit 705 output from the motor shaft 709 is divided into forward and reverse rotational power by the differential gear mechanism 702, and left and right through the pair of left and right pivoting output shafts 718 It is transmitted to the pair of planetary gear mechanisms 703. That is, in the differential gear mechanism 702, it is transmitted to the left planetary gear mechanism 703 as reverse rotation power through the left turning output shaft 718 fitted with the left side gear 717, while the right side gear 717 is fitted. The power is transmitted to the right planetary gear mechanism 703 as forward rotational power via the right turn output shaft 718.

  A turning pickup rotation sensor (turning vehicle speed sensor) 824 is provided in the hydraulic motor unit 705 of the turning hydraulic CVT 701, and the turning pickup rotation sensor 824 detects the number of rotations of the turning output (turning vehicle speed) Are configured to For example, a pulse generation rotary wheel for turning is provided on the motor shaft 709, and the pickup rotation sensor for turning 824 is disposed opposite to the pulse generation rotary wheel for turning, and the number of revolutions of the pulse generation rotary wheel for turning is as follows. The number of revolutions of the straight ahead output (turning vehicle speed) is detected.

  In the turning transmission case 13, a brake mechanism 751 interlocked with the operation of the brake pedal 35 is provided on the rectilinear input counter shaft 508 to which the rotational power from the rectilinear transmission case 17 is transmitted. Then, the rectilinear input gear 720 is fitted on the front end of the rectilinear input counter shaft 508 so as not to be relatively rotatable. In addition, the relay shaft 721 for straight movement is disposed in parallel with the input counter shaft 508 for straight movement, and the relay gear 722 for straight movement, which is always meshed with the input gear 720 for straight movement, can not rotate relative to the relay shaft 721 for straight movement. I'm fit.

  A bevel gear mechanism in which a ring gear 724 is meshed with a pinion gear 723 which is fitted to the rear end of the relay shaft 721 for linear movement in a relatively non-rotatable manner is provided, and the ring gear 724 can not relatively rotate the output shaft 725 for linear movement It is made to fit in. Both ends of the straight output shaft 725 are respectively connected to the pair of left and right planetary gear mechanisms 703. The rotational power (linear rotational power) from the transmission case 17 for linear movement input to the input counter shaft 508 for linear movement is transmitted to the pair of left and right planetary gear mechanisms 703 via the output shaft 725 for linear movement. Further, the braking mechanism 751 operates in response to the operation of the brake pedal 35 to attenuate or stop the rotational power of the straight output shaft 725.

  The left and right planetary gear mechanisms 703 rotate one sun gear 726, a plurality of planet gears 727 meshing with the sun gear 726, a ring gear 728 meshing with the turning output gear 719, and a plurality of planet gears 727 on the same circumference. Each of the carriers 729 to be arranged is provided. Carriers 729 of the left and right planetary gear mechanisms 703 are disposed opposite to each other at appropriate intervals on the same axis. The left and right sun gears 726 are fixed to both ends of a straight output shaft 725 on which a ring gear 724 is fitted in the middle.

  The left and right ring gears 728 are rotatably fitted on the straight output shaft 725, and the outer teeth on the outer peripheral surface thereof are meshed with the left and right swing output gears 719 to be connected to the swing output shaft 718 ing. A carrier 729 fixed to the ring gear 728 rotatably supports the planetary gear 727. The left and right carriers 729 are rotatably fitted on the left and right differential output shafts 730. Further, the left and right output transmission gears 731 integrally rotating with the left and right planetary gears 727 mesh with the left and right differential input gears 732 that are non-rotatably fitted to the left and right differential output shafts 730. doing. Left and right differential output shafts 730 are connected to left and right relay shafts 735 via relay gears 733 and 734, and left and right relay shafts 735 are connected to left and right axles 16 via final gears 736 and 737. ing.

  The left and right planetary gear mechanisms 703 receive rotation power from the straight transmission case 17 via the straight relay shaft 721 and the straight output shaft 725 to rotate the sun gear 726 at the same rotation speed in the same direction. . That is, the left and right sun gears 726 receive rotational power from the transmission case 17 for linear movement as linear rotation, and transmit the rotational power to the differential output shaft 730 via the planetary gear 727 and the output side transmission gear 731. Accordingly, the rotational power transmitted from the straight transmission case 17 to the left and right planetary gear mechanisms 703 is transmitted from the left and right axles 16 to the respective drive sprockets 62 at the same rotational speed in the same direction. The traveling body 2 is moved straight (forward, backward) by driving at the same rotational speed in the direction.

  On the other hand, the left and right planetary gear mechanisms 703 receive rotational power from the hydraulic motor unit 705 via the differential gear mechanism 702 and the turning output shaft 718, and rotate the ring gears 728 in the same rotational speed and in opposite directions. Rotate. That is, the left and right ring gears 728 receive rotational power from the hydraulic motor unit 705 as rotational rotation, cause the carrier 729 to overlap rotational rotation with straight rotation from the sun gear 726, and rotate the planetary gear 727 and the output transmission gear 731. . Thus, the rotational power obtained by adding the turning rotation to the straight-ahead rotation is transmitted to one of the left and right differential output shafts 730 via the planetary gear 727 and the output side transmission gear 731, and the left and right differential output shafts 730 are transmitted. To the other, rotational power obtained by subtracting the turning rotation to the straight-ahead rotation is transmitted via the planetary gear 727 and the output-side transmission gear 731.

  The shift output from the straight input counter shaft 508 and the motor shaft 709 is transmitted to the drive sprockets 62 of the left and right traveling crawlers 3 via the left and right planetary gear mechanisms 703, and the vehicle speed of the traveling body 2 (traveling speed And the direction of travel are determined. In other words, when the hydraulic motor unit 705 of the hydraulic continuously variable transmission 701 is stopped and the left and right ring gears 728 are fixed stationary, the rotational power from the linear transmission case 17 is input to the linear input counter shaft 508 The rotation of the rectilinear input counter shaft 508 is transmitted to the left and right sun gears 726 at the same rotational speed on the left and right, the left and right traveling crawlers 3 are driven at the same rotation number in the same direction, and the traveling machine body 2 travels straight.

  Conversely, when the hydraulic motor unit 705 of the hydraulic continuously variable transmission 701 is driven in a state where the rotation of the straight transmission case 17 by the straight output shaft 30 is stopped and the left and right sun gears 726 are stationary fixed, the motor shaft 709 The left ring gear 728 rotates in the positive direction (reverse rotation) and the right ring gear 728 rotates in the reverse direction (forward rotation). As a result, one of the drive sprockets 62 of the left and right traveling crawlers 3 is forwardly rotated, and the other is backwardly rotated, and the traveling airframe 2 is turned in place (a signal turning spin turn).

  The left and right traveling crawlers 3 are driven by driving the left and right ring gears 728 by the turning rotation of the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 while driving the left and right sun gears 726 by the straight rotation from the transmission case 17 for straight traveling. The traveling airframe 2 turns to the left or right (U-turn) with a turning radius larger than the turning radius while moving forward or backward. The turning radius at this time is determined according to the speed difference between the left and right traveling crawlers 3.

  Next, a switching structure (three forward rotation steps and one reverse rotation step) of the drive speed of the PTO shaft 25 executed via the PTO transmission mechanism 505 will be described. A PTO transmission mechanism 505 for transmitting the motive power from the engine 5 to the PTO shaft 25 is disposed in the straight transmission case 17. In this case, a PTO input shaft 591 extending coaxially with the main transmission input shaft 511 is connected to the rear end side of the main transmission input shaft 511 via a PTO hydraulic clutch 590 for power transmission / reception. Further, in the transmission case 17 for rectilinear advance, a PTO transmission shaft 592, a PTO counter shaft 593 and a PTO shaft 25 extending in parallel with the PTO input shaft 591 are disposed. The PTO shaft 25 projects rearward from the rear surface of the straight transmission case 17.

  When the PTO clutch switch 53 is operated for power connection, the PTO hydraulic clutch 590 is in a power connection state, and the main shift input shaft 511 and the PTO input shaft 591 are connected so as not to allow relative rotation. As a result, rotational power is transmitted from the main shift input shaft 511 to the PTO input shaft 591. The PTO input shaft 591 is provided with a medium speed input gear 597, a low speed input gear 595, a high speed input gear 596, and a reverse shift gear 598 in this order from the front side. The medium speed input gear 597, the low speed input gear 595, and the high speed input gear 596 are fitted on the PTO input shaft 591 such that relative rotation is not possible. The reverse shift gear 598 is spline-fit to the PTO input shaft 591 so as to be non-relatively rotatable and axially slidable.

  On the other hand, the PTO transmission shaft 592 is rotatably fitted with the PTO medium speed gear 601 meshing with the medium speed input gear 597, the PTO low speed gear 599 meshing with the low speed input gear 595, and the PTO high speed gear 600 meshing with the high speed input gear 596. doing. A pair of front and rear PTO shift shifters 602 and 603 is spline-fitted to the PTO shift shaft 592 so as to be non-relatively rotatable and to be slidable in the axial direction. The first PTO shift shifter 602 is disposed between the PTO medium speed gear 601 and the PTO low speed gear 599. The second PTO shift shifter 603 is disposed on the rear end side relative to the PTO high speed gear 600. The pair of front and rear PTO shift shifters 602 and 603 are configured to slide in the axial direction in conjunction with the operation of the PTO shift lever 46. PTO transmission gear 604 is fixed between PTO low speed gear 599 and PTO high speed gear 600 of PTO transmission shaft 592.

  The PTO counter shaft 593 includes the PTO counter gear 605 meshing with the PTO transmission gear 604, the PTO relay gear 606 meshing with the PTO output gear 608 fitted non-rotatably to the PTO shaft 25, and the PTO reverse gear 607 Impossible to fit. By turning on the sub PTO lever 48 while the PTO gear shift lever 46 is in neutral operation, the reverse shift gear 598 slides, and the reverse shift gear 598 and the PTO reverse gear 607 of the PTO counter shaft 593 are engaged. ing.

  When the PTO shift lever 46 is shifted, the pair of front and rear PTO shift shifters 602 and 603 slide along the PTO shift shaft 592, and the PTO low speed gear 599, the PTO medium speed gear 601, and the PTO high speed gear 600 are PTO shift shafts. It is alternatively connected to 592. As a result, low-speed to high-speed PTO transmission output is transmitted from PTO transmission shaft 592 to PTO counter shaft 593 through PTO transmission gear 604 and PTO counter gear 605, and PTO relay gear 606 and PTO output gear 608 are further reduced. It is transmitted to the PTO shaft 25 via the same.

  When the sub PTO lever 48 is turned on, the reverse shift gear 598 meshes with the PTO reverse gear 607, and the rotational power of the PTO input shaft 591 is transmitted to the PTO counter shaft 593 via the reverse shift gear 598 and the PTO reverse gear 607. Then, the reverse PTO gear shift output is transmitted from the PTO counter shaft 593 to the PTO shaft 25 via the PTO relay gear 606 and the PTO output gear 608.

  Next, the hydraulic circuit 620 structure of the tractor 1 will be described with reference to FIG. The hydraulic circuit 620 of the tractor 1 includes a working machine hydraulic pump 481 and a traveling hydraulic pump 482 which are driven by the rotational power of the engine 5. In the embodiment, the rectilinear transmission case 17 is used as a working oil tank, and the hydraulic oil in the rectilinear transmission case 17 is supplied to the working machine hydraulic pump 481 and the traveling hydraulic pump 482. The traveling hydraulic pump 482 is connected to a closed loop oil path 623 connecting the hydraulic pump portion 521 and the hydraulic motor portion 522 in the hydraulic mechanical type continuously variable transmission 500 for going straight. While the engine 5 is operating, the hydraulic oil from the traveling hydraulic pump 482 is constantly replenished in the closed loop oil passage 623.

  The traveling hydraulic pump 482 also includes a main transmission hydraulic pressure switching valve 624 for the main transmission hydraulic cylinder 524 of the hydraulic mechanical continuously variable transmission 500, a PTO clutch solenoid valve 627 for the PTO hydraulic clutch 590, and a switching valve 628 operated thereby. And connected. Further, the traveling hydraulic pump 482 includes a forward low speed clutch solenoid valve 632, which operates the forward low speed hydraulic clutch 537, a forward high speed clutch solenoid valve 633, which operates the forward high speed hydraulic clutch 539, and a reverse clutch which operates the reverse hydraulic clutch 541. A solenoid valve 634 is connected to a master control solenoid valve 635 for controlling the supply of hydraulic fluid to the clutch solenoid valves 632 to 634.

  In addition, the hydraulic lift cylinders in the hydraulic lift mechanism 22 include a plurality of hydraulic external takeout valves 430 in which the work implement hydraulic pump 481 is stacked and disposed on the upper surface of the hydraulic lift mechanism 22 on the upper rear side of the straight transmission case 17. 117 A double acting control solenoid valve 432 for controlling the hydraulic oil supply to the upper side, a tilt control solenoid valve 647 for controlling the hydraulic oil supply to the horizontal cylinder 122 provided on the right lift rod 121, and the hydraulic pressure in the hydraulic lifting mechanism 22 The up oil pressure switching valve 648 and the down oil pressure switching valve 649 that control the hydraulic oil supply to the lower side of the lift cylinder 117, the up control solenoid valve 650 that switches the up oil pressure switching valve 648, and the down oil pressure switching valve 649 are operated. It is connected to the lowering control solenoid valve 651. The double acting valve mechanism 431 is constituted by a hydraulic circuit including the double acting control solenoid valve 432, and the raising and lowering valve mechanism 652 comprises an ascending hydraulic switching valve 648, a descending hydraulic switching valve 649, a climbing control electromagnetic valve 650 and descending. It comprises a hydraulic circuit by the control solenoid valve 651.

  When the tilt control solenoid valve 647 is switched and driven, the horizontal cylinder 122 expands and contracts, and the lower link 23 on the right side moves up and down with the lower link pin on the front side as a fulcrum. As a result, the ground working machine 18 tilts to the left and right with respect to the traveling machine body 2 via the left and right lower links 23, and the left and right inclination angle of the ground working machine 18 changes. By switching control of the double acting control solenoid valve 432, either a single acting type or a double acting type can be selected as a driving method of the hydraulic lift cylinder 117. That is, by switching the double acting control solenoid valve 432 according to the switching operation of the single double acting changeover switch 56, the drive system of the hydraulic lift cylinder 117 is set.

  When the hydraulic lift cylinder 117 is driven in a single-acting mode, the hydraulic lift cylinder 117 expands and contracts when the up hydraulic switching valve 648 or the down hydraulic switching valve 649 is switched to move both the lift arm 120 and the left and right lower links 23 together. Move up and down. As a result, the ground work machine 18 moves up and down, and the elevation height position of the ground work machine 18 changes. On the other hand, when the hydraulic lift cylinder 117 is driven by double acting, the hydraulic switch valve 648 or the descending hydraulic switch 649 is switched and simultaneously the double acting control solenoid valve 432 is switched to drive the hydraulic lift cylinder 117. Move it. Thus, the ground working machine 18 can be moved up and down, and when the ground working machine 18 is lowered, the ground working machine 18 can be pressurized toward the ground, and the ground working machine 18 can be held at the lowered position.

  Further, the hydraulic circuit 620 of the tractor 1 includes a charge pump 707 driven by the rotational power of the engine 5, and the charge pump 707 is a hydraulic pump portion 704 and a hydraulic motor portion 705 in the hydraulic continuously variable transmission 701 for turning. Is connected to a closed loop oil passage 740 connecting the In the embodiment, the rectilinear transmission case 17 is used as a working oil tank, and the hydraulic oil in the rectilinear transmission case 17 is supplied to the charge pump 707. Further, while the engine 5 is operating, the working oil from the charge pump 707 is always replenished in the closed loop oil passage 740. The hydraulic circuit 620 of the tractor 1 includes a swing hydraulic cylinder 741 for changing the angle of the pump swash plate 708 of the hydraulic pump unit 704 in the hydraulic continuously variable transmission 701, and a swing hydraulic switching valve 742 for the swing hydraulic cylinder 741.

  The hydraulic circuit 620 of the tractor 1 also includes a lubricating oil pump 518 driven by the rotational power of the engine 5 in addition to the working machine hydraulic pump 481 and the traveling hydraulic pump 482 described above. The lubricating oil pump 518 includes a PTO clutch hydraulic switching valve 641 that supplies hydraulic oil (lubricating oil) to the lubricating portion of the PTO hydraulic clutch 590, and a main transmission input shaft 511 that supports the hydraulic mechanical continuously variable transmission 500. The forward and low speed clutch hydraulic switching valve 642 that supplies the working oil (lubricating oil) to the lubricating portion of the lubricating portion and the forward moving low speed hydraulic clutch 537, and the forward that supplies the operating oil (lubricant) to the lubricating portion of the forward high speed hydraulic clutch 539 It is connected to a high-speed clutch hydraulic switching valve 643 and a reverse clutch hydraulic switching valve 644 which supplies hydraulic oil (lubricating oil) to the lubricating portion of the reverse hydraulic clutch 541. The hydraulic circuit 620 includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like.

  Next, a configuration for executing travel control of the tractor 1 will be described with reference to FIGS. 13 to 16. As shown in FIG. 13, the tractor 1 is provided with a work unit controller 810 that controls the state of the ground work machine 18, an engine controller 811 that controls the driving of the engine 5, and an operation display panel (meter panel) mounted on the dashboard 33. A meter controller 812 for controlling the display operation 39, a straight-ahead controller 813 for controlling the speed of the traveling body 2 and the like, and a turning controller 814 are provided.

  The controllers 810 to 814 and the operation monitor 55 respectively have a ROM for storing control programs and data, a RAM for temporarily storing control programs and data, and a CPU for executing various arithmetic processing and control. A timer for measuring time, an input / output interface and the like are provided, and they are communicably connected to each other via a CAN communication bus 815. The controllers 810 to 814 are connected to the battery 817 via the power supply key switch 816.

  Under the control of the engine controller 811, in the engine 5, the fuel of the fuel tank is pumped by the fuel pump to the common rail, and is stored in the common rail as a high pressure fuel. Then, the engine controller 811 controls the respective fuel injection valves to open and close (electronic control), so that the high pressure fuel in the common rail (not shown) makes the injection pressure, the injection timing and the injection period (injection amount) highly accurate. After being controlled, each injector (not shown) injects each cylinder of the engine 5.

  On the output side of the meter controller 812, the liquid crystal panel of the meter panel 39, various alarm lamps, and the like are connected. Then, the meter controller 812 outputs various signals to the meter panel 39 to control the on / off operation and the blinking operation of the alarm lamp, the display operation of the liquid crystal panel, the alarm operation of the alarm buzzer, and the like.

  A main shift sensor (main shift potentiometer) 822 for detecting the operation position of the main shift lever 50, and a pickup rotation sensor for straight ahead detection for detecting the number of revolutions (straight vehicle speed) of the straight output. 823, a forward / backward movement sensor (back and forth movement potentiometer) 825 for detecting the operation position of the forward / backward movement switching lever 36, an auxiliary transmission sensor 826 for detecting the operation position of the auxiliary transmission lever 45, and a creep for detecting the operation position of the ultra low speed lever 44 A sensor 827, a brake position sensor 828 detecting a depression amount of the brake pedal 35, a clutch position sensor 829 detecting a depression amount of the clutch pedal 37, a brake switch 851 detecting a depression of the brake pedal 35, a depression detection of the clutch pedal 37 Clutch switch 852 and parking brake Connecting the parking brake switch 853 for detecting the operation of a Kireba 43.

  A forward low speed clutch solenoid valve 632 operating the forward low speed hydraulic clutch 537, a forward high speed clutch solenoid valve 633 operating the forward high speed hydraulic clutch 539, and a reverse clutch solenoid valve operating the reverse hydraulic pressure clutch 541 on the output side of the straight ahead controller 813 634 and a main shift hydraulic pressure switching valve 624 for operating the main shift hydraulic cylinder 524 in accordance with the amount of tilting operation of the main shift lever 50 is connected.

  A steering angle sensor (steering potentiometer) 821 for detecting the amount of rotation (steering angle) of the steering handle 9 on the input side of the turning controller 814, and a pickup for rotation for turning for detecting the number of rotations of the turning output (turning vehicle speed) A turning vehicle speed sensor 824 is connected. On the other hand, on the output side of the swing controller 814, a swing hydraulic pressure switching valve 742 for operating the swing hydraulic cylinder 741 in accordance with the amount of rotational operation of the steering handle 9 is connected.

  On the input side of the work machine controller 810, a rolling sensor 864 for detecting the left and right inclination angle of the traveling machine 2 and a potentiometer type working unit position sensor 865 for detecting the relative left and right inclination angle of the ground work machine 18 with respect to the traveling machine 2 And a potentiometer type lift angle sensor 866 for detecting the pivot angle of the lift arm 120 connecting the hydraulic lifting mechanism 22 and the left and right lower links 23. A double-acting control solenoid valve 432, a PTO clutch hydraulic pressure switching valve 641, a tilt control solenoid valve 647, an elevation control solenoid valve 650, and a lowering control solenoid valve 651 are connected to the output side of the work implement controller 810.

  As shown in FIG. 14, the straight-ahead controller 813 controls the output of a straight-ahead transmission path having a hydraulic mechanical continuously variable transmission (first continuously variable transmission) 500, and a straight traveling calculation unit 831 and steering of the steering wheel 9. A memory 832 storing a deceleration rate table TA storing the deceleration rate of the straight traveling vehicle speed with respect to a corner, and a communication interface 833 connected to the CAN communication bus 815. The deceleration rate table TA in the memory 832 is, as shown in FIG. 15, the "spin turn mode (first mode)", "brake turn mode (second mode)", and "slow turning mode (third mode)" described later. And the deceleration rates TA1 to TA4 of the straight traveling vehicle speed with respect to the steering angle of the steering wheel 9 with respect to the four modes of "traveling mode (fourth mode)".

  Although the deceleration ratio table TA shown in FIG. 15 indicates the deceleration ratio when the steering handle 9 is rotated to the right in each mode (when the tractor 1 is turning right), the steering handle 9 is rotated to the left. The same applies to the speed reduction rate when it is caused (when the tractor 1 turns left). That is, when the steering handle 9 is respectively rotated in the left and right directions (when the tractor 1 is turned left and right), the steering angle obtained by rotating the deceleration rate in the designated mode from the neutral position (0 °) of the steering handle 9 The speed reduction rate table TA is read from the speed reduction rate table TA to set the speed reduction rate of the straight vehicle speed. The deceleration rate is a rate by which the straight traveling speed is multiplied, and when the deceleration rate is 100%, the straight traveling speed is not decelerated, and as the deceleration rate decreases, the straight traveling speed is decelerated. In addition, the steering wheel 9 is restricted by the steering angle detection mechanism (steering box) 880 from rotating from 0 °, which is a neutral position, to θe (for example, 250 °) or more to the left and right.

  As shown in FIG. 15, the deceleration rate table TA is a neutral area (so-called play area) of the steering wheel 9 when the steering angle of the steering wheel 9 is from 0 ° (neutral position) to θmi (eg, 15 °). In the dead zone, the deceleration rates TA1 to TA4 of the respective modes are set to 100%. Then, when the steering angle of the steering handle 9 is from θ mi to θ ma (for example, 245 °), the operation range of the steering handle 9 is set as the spin turn mode, brake turn mode, and travel mode deceleration rate TA1, TA2, TA4. While monotonously decreasing according to the steering angle, the deceleration rate TA3 in the slow turning mode is made constant at 100%. That is, the steering angle θmi is a neutral position (0 °) in control, and the steering angle θma is a maximum steering angle in control. At this time, the change rate of the deceleration rate with respect to the steering angle increases in the order of the traveling mode, the brake turn mode, and the spin turn mode. Further, when the steering angle of the steering handle 9 is θma to θe, the maximum range of the steering handle 9 is set, and in the spin turn mode, the brake turn mode, and the traveling mode, the deceleration rates TA1, TA2, TA4 have minimum values De1 to It becomes De3 (0 <De1 <De2 <De3 <100)%.

  As shown in FIG. 14, the turning controller 814 controls the output of a turning system transmission path having a hydraulic continuously variable transmission (second continuously variable transmission) 701, and a steering angle of the steering wheel 9 And a communication interface 843 connected to the CAN communication bus 815. The memory 842 stores a turning / straight ratio table TB (see FIG. 17) storing the turning / straight ratio of the straight traveling vehicle speed to the turning vehicle speed. As shown in FIG. 15, the turning / straight advance ratio table TB in the memory 842 is described later in “spin turn mode (first mode)”, “brake turn mode (second mode)”, and “slow turning mode (third mode) The turning / straight-forward ratios TB1 to TB4 with respect to the steering angle of the steering wheel 9 are stored with respect to the four modes of “)” and “traveling mode (fourth mode)”.

  In addition, the turning / straight forward ratio table TB shown in FIG. 15 indicates a turning / straight forward ratio in which the steering handle 9 in each mode is turned to the right (at the time of right turn of the tractor 1) as positive. There is. Further, the turning / straight advance ratio is a ratio to be multiplied by the straight traveling speed decelerated by the deceleration rate, and when the turning / straight advance ratio is 0, there is no turning speed and the straight traveling speed is the same for both left and right traveling crawlers 3 As the turning / straight advance ratio becomes higher, the turning speed becomes higher, so the speed difference between the left and right traveling crawlers 3 becomes larger. In the following, the turning / straightforward ratio when the steering handle 9 is turned to the right (right turn) will be mainly described, and the turn when the steering handle 9 is turned to the left (left turn) For the straight-ahead ratio, supplement in parentheses.

  As shown in FIG. 15, the turning / straight ratio table TB has a turning / straight ratio TB1 to TB4 of each mode of 0 in a neutral region where the steering angle of the steering wheel 9 is 0 ° to θmi (−θmi to 0 °). I assume. And, in the operation area of the steering wheel 9 where the steering angle of the steering wheel 9 becomes θmi to θma (-θma to -θmi), the turn / straight ratio of spin turn mode, brake turn mode, gentle turn mode, and travel mode The values of TB1 to TB4 are monotonously increased in accordance with the steering angle. At this time, the change ratio of the turning / straight-forward ratio with respect to the steering angle is large in the order of the slow turning mode, the running mode, the brake turn mode, and the spin turn mode.

  In the maximum range where the steering angle of the steering handle 9 is θma to θe (−θe to −θma), the turning / straight forward ratio becomes maximum values Ra1 to Ra4 (minimum values −Ra1 to −Ra4) in each mode. . In addition, as shown in FIG. 15, the maximum turning / straight advance ratios Ra1 to Ra4 (-Ra1 to -Ra4) are 0 <Ra1 <Ra2 <Ra3 <Ra4 (-Ra4 <-Ra3 <-Ra2 <-Ra1 <0). When the steering angle of the steering wheel 9 is in the maximum range, the maximum turning / straight-forward ratio Ra1 (-Ra1) is obtained in the slow turning mode, and the maximum turning / straight-forward ratio Ra2 (-Ra2) is obtained in the traveling mode. The maximum turn / straight ratio Ra3 (-Ra3) is obtained in the brake turn mode, and the maximum turn / straight ratio Ra4 (-Ra4) is obtained in the spin turn mode.

  In the straight-ahead controller 813, as shown in FIG. 16, the straight-ahead traveling computing unit 831 receives a signal from the forward and reverse sensor 825 to recognize which of "forward", "neutral" and "reverse" is designated, In response to signals from the shift sensor 826 and the creep sensor 827, it is recognized which one of "high speed", "low speed", "super low speed" and "neutral" is designated (STEP 1). The straight traveling calculation unit 831 receives a signal from the main shift sensor 822 and calculates a target value (hereinafter referred to as “straight reference target value”) of the straight traveling vehicle speed in the straight traveling state (steering angle is 0 °). Do (STEP 2).

  The straight movement controller 813 receives the signal from the steering angle sensor 821 through the turning controller 814 at the communication interface 833, and gives the signal from the steering angle sensor 821 to the straight traveling calculation unit 831 (STEP 3). When the straight-ahead traveling computation unit 831 receives a signal from the steering angle sensor 821 and recognizes the steering angle of the steering handle 9, it refers to the deceleration ratio table TA in the memory 832 to select the steering handle 9 in the designated mode. The deceleration rate of the straight vehicle speed corresponding to the steering angle is read out (STEP 4).

  Then, the straight traveling calculation unit 831 multiplies the read deceleration rate by the straight traveling reference target value based on the signal from the main shift sensor 822 to obtain the target value of the straight traveling vehicle speed according to the steering angle (hereinafter referred to as “straight ahead target Calculate “value” (step 5). The “straight forward vehicle speed” in the straight traveling reference target value and the straight traveling target value is a relative speed of the rotation speed of the traveling transmission shaft 536 in the transmission case 17 for straight traveling with respect to the rotation speed of the engine 5.

  The straight traveling calculation unit 831 receives signals from the brake position sensor 828 and the clutch position sensor 829, and confirms the presence or absence of depression of each of the brake pedal 35 and the clutch pedal 37 (STEP 6). Then, the straight traveling calculation unit 831 checks the presence or absence of the machine stop operation on the brake pedal 35, the presence or absence of the operation on the clutch pedal 37, and whether or not the forward / reverse switching lever 36 or the sub shift lever 45 is in the neutral position. (STEP 7).

  The straight-ahead traveling calculation unit 831 performs an aircraft stop operation, or when the clutch pedal 37 is depressed, or when the forward / reverse switching lever 36 or the auxiliary transmission lever 45 is in the neutral position (Yes in STEP 7). The communication interface 833 transmits a signal from the pickup rotation sensor 823 for going straight (hereinafter referred to as “go straight measured value”) to the turning controller 814 (STEP 8). After that, in the case of forward movement, the straight running arithmetic operation unit 831 controls the operation of the forward low speed clutch solenoid valve 632, the forward high speed clutch solenoid valve 633, and the reverse clutch solenoid valve 634 to advance forward low speed hydraulic clutch 537, forward high speed The hydraulic clutch 539 and the reverse hydraulic clutch 541 are disconnected (STEP 9).

  On the other hand, in the straight running arithmetic operation unit 831, there is no machine stop operation, there is no stepping operation on both the clutch pedals 37, and the forward / reverse switching lever 36 is at the forward position or reverse position, and the sub shift lever 45 is If it is in any of the ultra low speed position, the low speed position or the high speed position (No in STEP 7), the calculated straight traveling target value is transmitted from the communication interface 833 to the turning controller 814 (STEP 10). Thereafter, the straight running calculation unit 831 controls the operation of the forward low speed clutch solenoid valve 632, the forward high speed clutch solenoid valve 633, and the main shift hydraulic pressure switching valve 624 in the forward direction based on the calculated straight ahead target value. In the case of reverse, the operation of the reverse clutch solenoid valve 634 and the main shift hydraulic pressure switching valve 624 is controlled (STEP 11). As a result, all the hydraulic clutches 537, 539, 541 are in the power-off state, and the traveling drive force from the main shift output shaft 512 is substantially zero (the main clutch-off state).

  That is, in STEP 11, the straight running arithmetic operation unit 831 outputs the straight traveling transmission path (rotational speed by the straight output shaft 30) based on the straight measured value (signal from the straight pickup rotation sensor 823) and the straight target value. Feedback control (main transmission control). The rotational speed of the traveling transmission shaft 536 is confirmed from the signal from the pickup rotation sensor 823 for going straight on the basis of the transmission gear ratio specified by the signals from the auxiliary shift sensor 826 and the creep sensor 827, and compared with the straight target value. Control the output of the straight drive transmission path.

  In the turning controller 814, as shown in FIG. 16, the turning driving operation unit 841 receives a signal from the steering angle sensor 821 and recognizes the steering angle of the steering handle 9 (STEP 51). The turning and traveling calculation unit 841 reads out the turning and straight-ahead ratio according to the steering angle of the steering wheel 9 in the designated mode with reference to the turning / straight-forward ratio table TB in the memory 842 (STEP 52).

  Further, the turning controller 814 receives signals from the auxiliary shift sensor 826 and the creep sensor 827 through the straight movement controller 813 at the communication interface 843 and gives the turning traveling calculation unit 841 (STEP 53). The turning and traveling computation unit 841 recognizes which of “high speed”, “low speed”, and “super low speed” is designated as the sub-transmission based on the signals from the sub-transmission sensor 826 and the creep sensor 827. The turning and traveling calculation unit 841 reads the correction value of the turning / straight-forward ratio from the memory 842 based on the designated sub-shift, and corrects the turning / straight-forward ratio based on the designated sub-shift (STEP 54).

  Further, the turning controller 814 receives the straight driving target value or the straight driving actual measurement value (signal from the pickup rotation sensor for straight driving 823) calculated by the straight driving controller 813 by the communication interface 843 and gives it to the turning driving operation unit 841 (STEP 55). ). The turning driving calculation unit 841 confirms the straight traveling vehicle speed from the straight traveling target value or the straight traveling measurement value, and calculates the turning target value as the turning vehicle speed by multiplying the straight traveling vehicle speed by the corrected turning / straight traveling ratio (STEP 56) ). The “turning vehicle speed” in the turning target value is a relative speed of the rotational speed of the motor shaft 709 in the turning transmission case 13 with respect to the rotational speed of the engine 5.

  When the turning target value is calculated, the turning travel computation unit 841 controls the operation of the turning hydraulic pressure switching valve 742. At this time, the turning travel calculation unit 841 outputs the turning system transmission path (rotation by the motor shaft 709) based on the signal from the turning pickup rotation sensor 824 (hereinafter referred to as “turning measurement value”) and the turning target value. Feedback control (turn control) is performed (STEP 57).

  When the straight movement controller 813 is executing the main shift control, when the signal from the forward / backward movement sensor 825 is switched from "forward to reverse" or "reverse to forward", the forward low speed clutch solenoid valve 632 and the reverse clutch The solenoid valve 634 is controlled to switch the forward low speed hydraulic clutch 537 and the reverse hydraulic clutch 541. As described above, when switching between the forward low speed hydraulic clutch 537 and the reverse hydraulic clutch 541, the straight-ahead controller 813 controls such that either the forward low speed hydraulic clutch 537 or the reverse hydraulic clutch 541 is always connected.

  At this time, by changing the straight traveling reference target value (or the straight traveling target value), the main shift hydraulic pressure switching valve 624 is controlled to turn the main shift output shaft 512 and the traveling relay shaft 535 into the lowest speed rotation state again. The rotational speed of the main transmission output shaft 512 and the traveling relay shaft 535 is increased so that the original rotational speed is achieved. Therefore, the turning controller 814 can change the turning target value in the same manner as the straight driving target value by receiving the straight driving target value from the straight driving controller 813. As a result, the turning controller 814 reverses the output (the turning vehicle speed) of the turning system transmission path with respect to the operation of the steering handle 9 at the time of forward movement and reverse movement of the traveling airframe 2 and can contribute smooth maneuverability to the operator.

  The straight advance controller 813 performs forward low speed clutch electromagnetic when the main shift lever 50 is operated to the high speed side or the low speed side while the signal from the forward / reverse sensor 825 is "forward" while executing the main shift control. The valve 632 and the forward high speed clutch solenoid valve 633 are controlled to switch the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539. Thus, when switching between the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539, the straight-ahead controller 813 controls such that either the forward low speed hydraulic clutch 537 or the forward high speed hydraulic clutch 539 is always connected.

  At this time, the straight movement controller 813 controls the main shift hydraulic pressure switching valve 624 in accordance with the straight movement target value. Further, the turn controller 814 receives the straight advance target value from the straight advance controller 813 to set the output (turning vehicle speed) of the turning system transmission path in response to the operation of the steering handle 9. It is possible to output the turning system transmission path (turning vehicle speed) according to the output of the straight traveling system transmission path (straight vehicle speed) without affecting the switching of the clutch 539 and without performing complicated calculations.

  The straight-ahead controller 813 is a straight-line measurement value (a straight-ahead measurement (a straight-ahead operation) when the forward low speed hydraulic clutch 537, the forward high speed hydraulic clutch 539, and the reverse hydraulic Signal from the pickup pickup rotation sensor 823 to the turning controller 814. Then, the turning controller 814 sets an output (turning vehicle speed) of the turning system transmission path according to the straight traveling actual measurement value (signal from the pickup rotation sensor 823 for straight traveling). Therefore, even if the forward high-speed hydraulic clutch 539 and the reverse hydraulic clutch 541 are all disengaged, and the output of the straight transmission path (straight vehicle speed) does not correspond to the straight target value, the output of the turning transmission path ( Since the turning vehicle speed can be set optimally, the operator can operate the vehicle without discomfort.

  When the brake pedal 35 is depressed and the vehicle is stopped by a sudden braking operation or the like, the straight advance controller 813 advances forward low speed hydraulic clutch 537, forward high speed hydraulic pressure in a high speed region where the traveling speed (straight vehicle speed) is a predetermined speed or more. The clutch 539 and the reverse hydraulic clutch 541 are controlled to be in the disconnected state. At this time, the turning controller 814 sets the output (turning vehicle speed) of the turning system transmission path according to the straight traveling actual measurement value (signal from the pickup rotation sensor 823 for straight traveling). Therefore, when the braking control by the operation of the brake pedal 35 is being performed, the output (turning vehicle speed) of the turning system transmission route is obtained even if the output of the straight movement system transmission route (straight vehicle speed) does not correspond to the straight target value. Since the vehicle can be decelerated in accordance with the output of the straight drive transmission path (straight vehicle speed), the operator can operate the vehicle without discomfort.

  On the other hand, even when the vehicle stop operation is performed on the brake pedal 35, when the traveling speed (straight forward vehicle speed) is in a low speed area lower than the predetermined speed, the straight ahead controller 813 matches the forward and backward travel of the vehicle. Setting the straight travel target value so that the pump swash plate 523 of the hydraulic mechanical continuously variable transmission 500 is in the neutral state (0 °) with the forward low speed hydraulic clutch 537 or the reverse hydraulic clutch 541 engaged. Execute shift control (feedback control). At this time, the turning controller 814 may set the output (turning vehicle speed) of the turning system transmission path based on the straight traveling actual measurement value, or may set the output of the turning system transmission path based on the straight traveling target value.

  The turning controller 814 decelerates the output (turning vehicle speed) of the turning system transmission route in accordance with the deceleration of the output (straight vehicle speed) of the straight movement system transmission route. Then, when the steering handle 9 is operated, the turning controller 814 accelerates the output (turning vehicle speed) of the turning system transmission path, and the turning controller 814 decelerates the output of the straight traveling system transmission path (straight vehicle speed). The speed ratio of the left and right traveling crawlers 3 at the time of turning is determined based on the turning angle (steering angle) of the steering wheel 9.

  In addition, the operator operates the operation monitor 55 to reverse the inside of the turning when the steering wheel turning angle is large, thereby enabling a small turn (spin turn), "spin turn mode (first mode)", and spin turn mode. Compared with the brake turn mode (second mode) that can be executed until the brake turn that stops the turning inside when the steering wheel turning angle becomes near the maximum when the steering wheel turning angle becomes close to maximum, and the cutting is even blunter than the brake turn mode It is possible to select the "slow turning mode (third mode)" and the "traveling mode (fourth mode)" capable of coping with the high speed vehicle speed. When ultra low speed travel or low speed travel is specified by the ultra low speed lever 44 and the sub shift lever 45, the turning operation by any of the "spin turn mode", "brake turn mode", and "slow turning mode" is performed. Permitted. On the other hand, when high speed travel is designated by the ultra low speed lever 44, only the turning operation in the "travel mode" is permitted.

  Furthermore, the operator can adjust the turning force at the time of turning in a plurality of stages by operating the operation monitor 55. Therefore, the operator can select from a plurality of modes alternatively by operating the operation monitor 55, and can also make stepwise adjustment, so that appropriate traveling characteristics (swing characteristics) that match the field conditions etc. Can be selected easily.

  When the "spin turn mode" is specified, as shown in FIG. 18, when the turning angle of the steering handle 9 becomes the angle θt1 (θmi <θt1 <θma), the inner traveling crawler 3 is stopped and traveling When the turning angle of the steering handle 9 exceeds the angle θt1, the inner traveling crawler 3 is reversely rotated and the traveling airframe 2 is rotated by the spin turn. That is, when the turning angle of the steering handle 9 is less than the angle θt1, the inner traveling crawler 3 is decelerated, and when the turning angle of the steering handle 9 is the angle θt1, the inner traveling crawler 3 is stopped and the steering handle 9 is broken. When the angle exceeds the angle θt1, the inner traveling crawler 3 is reversely rotated. Thereby, the turning center and turning radius of the traveling vehicle body 2 can be changed in accordance with the amount of operation of the steering handle 9. Therefore, the traveling body 2 can be turned in a state close to the operation feeling to the steering handle 9, and as a result, the traveling body 2 can be stably traveled.

  When “brake turn mode” is specified, as shown in FIG. 19, when the turning angle of the steering handle 9 becomes an angle θt2 (θt1 <θt2 <θma) close to the maximum angle θma in control, the traveling fuselage Turn 2 by the brake turn. When the "slow turning mode" is specified, as shown in FIG. 19, even if the turning angle of the steering handle 9 is set to the control maximum angle θma or more, the inner traveling crawler 3 does not stop and the traveling airframe 2 is relaxed. Turn it. Further, even in the "traveling mode", the turning operation by the brake turn and the spin turn can not be performed.

  The swing controller 814 is configured to be able to adjust a control amount for swash plate control with respect to a swash plate angle of the pump swash plate 708 in the hydraulic continuously variable transmission 701. At this time, the swing controller 814 is a pump swash plate when adjusting the control amount for swash plate control in a state where the traveling machine body 2 is supported on an adjustment stand (not shown) in a manufacturing plant etc. and the traveling crawler 3 is floated. An offset amount is given to the control amount measured by changing the swash plate angle of 708, and is stored as a control amount for swash plate control. The offset amount is an offset amount for increasing the turning curvature of the traveling vehicle body 2, and the offset amount is added so as to increase the control current amount to the turning hydraulic pressure switching valve 742 serving as the control amount. On the other hand, when adjusting the control amount for swash plate control on the road where the traveling crawler 3 is grounded, the swing controller 814 stores the control amount measured by changing the swash plate angle of the pump swash plate 708 as the control amount for swash plate control. Do.

  When the turning controller 814 executes turning adjustment control for adjusting the control amount of the swash plate control to the hydraulic continuously variable transmission 701, the turning hydraulic pressure switching valve 742 is in a state where the output from the straight transmission case 17 is stopped. Measure the amount of control current for At this time, the turning controller 814 receives a signal from the turning vehicle speed sensor 824 and receives the number of revolutions of the engine 5 from the engine controller 811 to check the transmission gear ratio in the hydraulic continuously variable transmission 701 while measuring Measure the amount of control current when the gear ratio is reached.

  The turning controller 814 sets the map value of the control current amount for the gear ratio of the hydraulic continuously variable transmission 701 based on the relationship between the gear ratio at the measurement target point and the control current amount (for the gear ratio changed for each predetermined amount). A gear ratio / control amount table of the control current amount is calculated and stored in the memory 842. At this time, when turning adjustment control is performed on the adjustment stand, control is performed on the map values of the stored control current amount with respect to the values of the respective gear ratios calculated from the relationship between the transmission ratio at the measurement target point and the control current amount. Let the amount of offset be given to the amount of current. When turning adjustment control is performed on the road, the map value of the control current amount to be stored is taken as the value of each gear ratio calculated from the relationship between the transmission ratio at the measurement target point and the control current amount.

  When turning adjustment control is executed on the adjustment stand, the measured control amount is given an offset amount and stored as a control amount for swash plate control, so the road surface condition or the field condition with which the traveling crawler 3 contacts during traveling on the road. It is possible to execute the turning motion according to Therefore, since the traveling body 2 can be turned in accordance with the steering angle at the steering handle 9, the responsiveness to the steering wheel operation of the operator is improved, and as a result, the driving operability can be improved.

  When turning adjustment control can be performed on the road, and when it is performed on the road, the turning controller 814 stores the measured control amount as the control amount for swash plate control, so that the turning operation matched to the road surface condition or the field condition It can be adjusted. Therefore, even after factory shipment, the operator can execute the turn adjustment control on the road. For example, by executing the turn adjustment control on the road surface or field generally used by the operator, the turn according to the operator's operation feeling Operation becomes possible, and more stable driving operation can be performed when turning.

  An embodiment of swing adjustment control in the swing controller 814 will be described below with reference to the drawings.

<First Example of Turning Adjustment Control>
In this example, the operation monitor 55 is used as a setting condition designation unit that designates whether the measurement condition at the time of execution of the turn adjustment control is on the adjustment stand or on the road. The swing controller 814 adjusts the control amount for swash plate control in accordance with the measurement condition designated by the operation monitor 55. As described above, since the measurement conditions can be reliably identified by the operation monitor 55 serving as the setting condition designation unit, the control amount for swash plate control to be stored after the turning adjustment can be set to the optimum value. The details of the operation in this example will be described below with reference to the flowchart of FIG.

  As shown in FIG. 20, the turning controller 814 according to this example satisfies the start condition of the turning adjustment control described later (Yes in STEP 401), and allows the double acting valve mechanism 431 to be driven by the single double acting selector switch 56 (single double acting switching When the switch 56 is turned on (Yes in STEP 402), a turning adjustment response signal is transmitted to the meter controller 812 and the operation monitor 55 (STEP 403). Each of the meter controller 812 and the operation monitor 55 notifies the operator that the turning adjustment control is to be started by receiving the turning adjustment response signal.

  In STEP 401, as the start condition of the turning adjustment control, the forward / reverse switching lever 36 and the auxiliary transmission lever 45 are set to the neutral position, the rotation speed of the engine 5 is within the predetermined range, and the main transmission lever 50 is at the predetermined position. When the parking lever is set by the brake lever 43, the brake pedal 35 is depressed, and the driving of the double acting valve mechanism 431 is inhibited by the single double acting changeover switch 56 (the single double acting changeover switch 56 is turned off) The process proceeds to the standby acceptance operation of the ON operation to the movement changeover switch 56 (STEP 402). That is, while the output from the straight transmission case 17 to the turning transmission case 13 is stopped, the hydraulic stepless in the turning transmission case 13 is obtained with respect to the power from the engine 5 operated at the predetermined rotational speed. Differential power is generated by the transmission 701.

  After the turning controller 814 transmits the above-mentioned turning adjustment response signal (STEP 403), the control current amount to the turning hydraulic switching valve 742 is set to a predetermined rate so that the differential power at the time of turning right is output from the turning transmission case 13. The control current amount in the right turn is measured (STEP 404). At this time, the turning controller 814 first receives a signal from the turning vehicle speed sensor 824 for a predetermined period of time with the amount of control current being 0, and receives the signal from the hydraulic motor unit 705 of the hydraulic continuously variable transmission 701. Check that there is no output. After that, the turning controller 814 measures the control current amount for the transmission gear ratio to be a plurality of measurement target points by checking the signal from the turning vehicle speed sensor 824 while increasing the control current amount to the right turning side.

  When the turning controller 814 confirms that the gear ratio in the hydraulic continuously variable transmission 701 has become maximum, it decreases the amount of control current in a ramp shape with respect to time, and finally stops the supply of the amount of control current. (The control current amount is set to 0), and the right turn measurement is ended (STEP 405). Then, the turning controller 814 confirms whether the amount of control current at each measurement target point at the time of right turn measurement is within the normal range (STEP 406).

  When it is confirmed that the control current amount assumed in the right turn measurement is all within the normal range (Yes in STEP 406), the turn controller 814 causes the turning transmission case 13 to output the differential power during the left turn, The control current amount to the turning hydraulic pressure switching valve 742 is changed at a predetermined rate, and measurement of the control current amount in left turning is executed (STEP 407). When the turning controller 814 measures the amount of control current at all measurement symmetrical points in left turn, after stopping the supply of the amount of control current (STEP 408), the amount of control current at each measurement target point at the time of left turn measurement is normal. It is checked whether it is within the range (STEP 409).

  When the turning controller 814 confirms that the control current amounts assumed in the left turn measurement are all within the normal range (Yes in STEP 409), based on the relationship between the control current amount at each measurement target point and the gear ratio, A map value (a gear ratio / control amount table) of the control current amount with respect to the gear ratio in each of the right turn and the left turn is calculated (STEP 410). After that, the turning controller 814 confirms whether the traveling machine body 2 is installed on the adjustment stand or on the road based on the operation received by the operation monitor 55 at the start of the turning adjustment control (STEP 411).

  When traveling body 2 is mounted on the adjustment stand (Yes in STEP 411), turning controller 814 adds an offset amount to each of the calculated map values of the control current amount (STEP 412), and stores it in memory 842 ( STEP 413). On the other hand, when the traveling body 2 is on the road (No in STEP 411), the turning controller 814 stores the calculated map value of the control current amount as it is in the memory 842 (STEP 413). As described above, when the turning controller 814 stores the gear ratio / control amount table in the memory 842, the turning controller 814 transmits a turning adjustment completion signal to the meter controller 812 and the operation monitor 55 (STEP 403). The meter controller 812 and the operation monitor 55 each notify the operator that the turning adjustment control has been completed by receiving the turning adjustment completion signal.

  If the start condition of the turning adjustment control is not satisfied (No in STEP 401), or the amount of control current at each measurement target point during right turning measurement or left turning measurement is not within the normal range (No in STEP 406 or STEP 409) And the turning controller 814 transmits a measurement value abnormality signal to the meter controller 812 and the operation monitor 55 (STEP 415). The meter controller 812 and the operation monitor 55 each notify the operator of an abnormality in the turning adjustment control by receiving the measurement value abnormality signal.

Second Example of Turning Adjustment Control
In this example, based on the signal from the rolling sensor 864 that measures the left inclination state of the traveling vehicle 2, the turning controller 814 determines whether the measurement condition at the time of execution of the turning adjustment control is on the adjustment stand or on the road Is determined, and the control amount for swash plate control is adjusted according to the determined measurement condition. As described above, by making it possible to automatically detect the measurement conditions at the time of execution of the turn adjustment control, it is not necessary to specify the measurement conditions as in the first example described above, and the operation at the time of execution of the turn adjustment. It can eliminate complexity. Further, by making the designation of the place by the operator unnecessary, it is possible to prevent the storage of the improper control amount for swash plate control due to the operation mistake by the operator or the like. The details of the operation in this example will be described below with reference to the flowchart of FIG. In the present embodiment, the same reference numerals are attached to the same operation steps as those in the first embodiment, and the detailed description thereof is omitted.

  As shown in FIG. 21, the turning controller 814 of this example starts turning adjustment control, executes right turn measurement and left turn measurement, and controls the amount of control current at each measurement target point that falls within the normal range. When the map value of the control current amount for the gear ratio of the hydraulic CVT 701 is calculated (STEP 401 to STEP 410), the detection signal from the rolling sensor 864 at the time of right turn measurement and left turn measurement is used as a work machine It receives from the controller 810 (STEP 420).

  The turning controller 814 detects that centrifugal force is applied to the traveling airframe 2 from the detection signal of the rolling sensor 864, and confirms that the traveling airframe 2 has turned, thereby determining that the traveling airframe 2 is on the road Then, the map value of the calculated control current amount is stored in the memory 842 (STEP 413). On the other hand, when the turning controller 814 detects that centrifugal force is not applied to the traveling machine body 2 from the detection signal of the rolling sensor 864 and confirms that the traveling machine body 2 is not turning, the traveling machine body 2 is an adjustment stand. It is determined that it is above (Yes in STEP 411), and an offset amount is added to the calculated map value of the control current amount and stored in the memory 842 (STEP 412 and STEP 413).

<Third Example of Turning Adjustment Control>
In this example, the turning controller 814 determines whether the measurement condition at the time of executing the adjustment operation of the control amount for controlling the swash plate is on the adjustment stand or on the road based on the load factor of the engine. The control amount for swash plate control is adjusted according to the determined measurement condition. The details of the operation in this example will be described below with reference to the flowchart of FIG. In the present embodiment, the same reference numerals are attached to the same operation steps as those in the first embodiment, and the detailed description thereof is omitted.

  As shown in FIG. 22, the turning controller 814 of this example starts turning adjustment control, executes right turning measurement and left turning measurement respectively, and controls the amount of control current at each measurement target point that falls within the normal range. When the map value of the control current amount with respect to the gear ratio of the hydraulic continuously variable transmission 701 is calculated (STEP 401 to STEP 410), the load factor of the engine 5 calculated by the engine controller 811 is received (STEP 430).

  When it is detected that the load factor of the engine 5 is high and the load (frictional force etc.) from the ground contact surface is applied to the traveling body 2, the turning controller 814 determines that the traveling body 2 is on the road (STEP 411). No), the map value of the calculated control current amount is stored in the memory 842 (STEP 413). On the other hand, when the swing controller 814 detects that the load factor of the engine 5 is low and there is no load on the traveling body 2 from the ground contact surface, it determines that the traveling body 2 is on the adjustment stand (Yes in STEP 411) An offset amount is added to the calculated map value of the control current amount and stored in the memory 842 (STEP 412 and STEP 413).

  In each of the above-described examples, the offset amount to be added to the map value of the control current amount may be changed when executing the above-described turn adjustment control while the traveling machine body 2 is on the adjustment stand. That is, for example, for the tractor 1 mainly working in the wet field, while reducing the offset amount, the offset amount should be large for the tractor 1 mainly working in the dry field Then, for each tractor 1, the map value of the amount of control current optimal for the condition of the field or road surface that is the work place can be stored in the memory 842.

  Further, the configuration of each part in the present invention is not limited to the illustrated embodiment, and various changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 2 traveling body 3 traveling crawler 5 diesel engine 8 steering seat 9 steering handle 13 steering gear case 17 straight transmission case 500 hydraulic mechanical transmission 501 hydraulic mechanical transmission switching mechanism 502 creep transmission gear mechanism 503 secondary transmission gear mechanism 511 main transmission input Shaft 512 Main transmission output shaft 521 Hydraulic pump part 522 Hydraulic motor part 523 Pump swash plate 524 Main transmission hydraulic cylinder 526 Planetary gear mechanism 535 Traveling relay shaft 537 Forward low speed hydraulic clutch 539 Forward high speed hydraulic clutch 541 Reverse hydraulic clutch 624 Main transmission hydraulic pressure switching Valve 642 Forward low speed clutch hydraulic switching valve 643 Forward high speed clutch hydraulic switching valve 644 Reverse clutch hydraulic switching valve 701 Hydraulic continuously variable transmission (HST)
702 Differential gear mechanism 703 Planetary gear mechanism 704 Hydraulic pump unit 705 Hydraulic motor unit 706 Pump shaft 707 Charge pump 708 Pump swash plate 709 Motor shaft 741 Turning hydraulic cylinder 742 Turning hydraulic switching valve 813 Straight line controller 814 Turning controller 821 Steering angle sensor 822 Main shift sensor 823 Straight pick-up rotation sensor 824 Turning pick-up rotation sensor 825 Forward shift sensor 826 Secondary shift sensor 827 Creep sensor 828 Brake position sensor 829 Clutch position sensor 831 Straight travel calculation unit 832 Memory 833 Communication interface 841 Turn drive calculation unit 842 Memory 843 Communication interface 880 Steering angle (steering wheel turning angle) detection mechanism TA Deceleration rate table TB Turning / straight forward ratio table

Claims (6)

An engine mounted on a traveling body, a linear movement transmission path having a first continuously variable transmission, and a turning transmission path having a second continuously variable transmission, and an output of the linear movement transmission path and the turning transmission path In a work vehicle that combines the outputs of the two to drive the left and right traveling units,
A control unit that changes a swash plate angle of the second continuously variable transmission is configured to be able to adjust a control amount for swash plate control with respect to a swash plate angle of the second continuously variable transmission,
Wherein the control unit, the time of adjusting a swash plate controlling the control amount, said by changing the swash plate angle to correct the controlled variable measurement, used for storing the control amount after corrected as the swash plate control for controlling the amount of When adjusting the control amount for controlling the swash plate on an adjustment table where the traveling portion is in a floating state, the turning curvature of the traveling body is increased to the control amount measured by changing the swash plate angle. A working vehicle characterized by giving an offset amount on the side and storing it as the control amount for swash plate control . When the control unit adjusts the control amount for controlling the swash plate on the road on which the traveling unit is grounded, the control unit stores the control amount measured by changing the swash plate angle as the control amount for controlling the swash plate. The work vehicle according to claim 1 . It has a setting condition designating unit for designating whether the measurement condition at the time of execution of the adjustment operation of the control amount for controlling the swash plate is on the adjustment stand or on the road,
The work vehicle according to claim 2 , wherein the control unit adjusts the control amount for swash plate control in accordance with the measurement condition designated by the setting condition designation unit. It is equipped with an inclination detection sensor that measures the inclination state of the traveling body.
The control unit determines, based on the signal from the tilt detection sensor, whether the measurement condition at the time of execution of the adjustment operation of the control amount for controlling the swash plate is on the adjustment stand or on the road The work vehicle according to claim 2 , wherein the control amount for controlling the swash plate is adjusted in accordance with the measurement conditions. The control unit determines, based on the load factor of the engine, whether the measurement condition at the time of executing the adjustment operation of the control amount for controlling the swash plate is on the adjustment stand or on the road, and the determination The work vehicle according to claim 2 , wherein the control amount for controlling the swash plate is adjusted in accordance with a condition. The control unit is configured of a first control unit that controls an output of the linear movement transmission path, and a second control unit that controls an output of the turning transmission path, and is set by the first control unit. The second control unit receives the output of the straight movement transmission path to set the output of the turning transmission path, and the second control is a swash plate of the second continuously variable transmission. The work vehicle according to any one of claims 1 to 5 , wherein a control amount for a corner is adjusted.

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