JP6487774B2 - Work vehicle - Google Patents

Description

  For example, the present invention relates to a work vehicle such as a farm work machine such as a tractor and a special work machine such as a crane truck.

  Conventionally, work vehicles such as tractors and crawler cranes have been provided with two hydraulic continuously variable transmissions (HST) to which power from the engine is transmitted, and engine outputs from each of the two hydraulic continuously variable transmissions. There are some that output straight power and turning power based on the above. The applicant of the present application previously proposed a work vehicle in Patent Document 1 that can turn by combining the straight 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 work vehicles such as tractors and wheel loaders include a hydraulic mechanical transmission (HMT) having a transmission efficiency higher than that of a hydraulic continuously variable transmission in a transmission case that transmits power from an engine. The applicant of the present application has previously made a series-type (in-line type) hydraulic mechanical transmission in which the hydraulic pump and the hydraulic motor are arranged in series so that the input shaft of the hydraulic pump and the output shaft of the hydraulic motor are positioned concentrically. Is proposed in Patent Document 2.

  In an inline type hydraulic mechanical transmission, an output shaft is fitted on an input shaft to which power is transmitted from an engine so as to be relatively rotatable. Further, a hydraulic pump, a cylinder block, and a hydraulic motor are fitted on the input shaft. The cylinder block alone serves as both a hydraulic pump and a hydraulic motor, and power is transmitted from the hydraulic motor to the output shaft. For this reason, unlike a general hydraulic mechanical transmission, an in-line type hydraulic mechanical transmission can output a combination of hydraulic shift power and engine power without interposing a planetary gear mechanism. It has the advantage that transmission efficiency can be obtained.

JP 2002-59753 A JP 2005-83497 A

  Incidentally, in order to mount the hydraulic mechanical transmission in Patent Document 2 on a medium-sized or large work vehicle, it is necessary to increase the output of the hydraulic mechanical transmission. In order to increase the output of the hydraulic mechanical transmission, for example, the capacity of the hydraulic 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 but increases the manufacturing cost, but also sacrifices the power transmission efficiency (especially in the low load range). There was a problem.

  Further, even when the mechanism in Patent Document 1 is mounted on a large work vehicle, the mechanism becomes larger with the increase in output of the hydraulic continuously variable transmission, which not only increases the weight of the work vehicle but also transmits power. Since the efficiency is lower than that of the hydraulic mechanical transmission, the speed change range (main speed change range) in the straight direction is limited.

  Furthermore, the controller that controls the running operation needs to control the swash plate angles of the two hydraulic continuously variable transmissions by integrating the signals from the main shifting, forward / reverse, and turning operating tools. Control flow must be executed by the controller. For this reason, the controller has a high calculation load in the control flow of the traveling operation, which may cause the operator to feel uncomfortable.

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

A work vehicle according to the present invention includes an engine mounted on a traveling machine body, a straight traveling system transmission path having a first continuously variable transmission, and a turning system transmission path having a second continuously variable transmission, wherein the straight traveling system transmission path In a work vehicle that combines the output and the output of the turning system transmission path to drive the left and right traveling units, a control unit that controls the output of the straight traveling system transmission path and the output of the turning system transmission path in an interlocking manner; A steering handle that can be rotated, and the control unit decelerates the output of the turning transmission path as the output of the linear transmission path is decelerated, and the steering handle is operated. If, then accelerated the output of the orbiting system transmission path, by decelerating the output of the linear system transmission path, to determine the speed ratio of the left and right traveling unit during turning based on the steering angle of the steering wheel And the control unit The linear control transmission configured by the first control unit configured to control the output of the linear transmission path and the second control unit configured to control the output of the turning transmission path, and set by the first control unit. The output of the turning system transmission path is set by the second control unit receiving the output of the path .

  In the work vehicle, the control unit includes a first control unit that controls an output of the straight drive system electric path and a second control unit that controls an output of the turning system electric path. The second control unit receives the output of the straight-ahead transmission path set by the control unit, and thereby sets the output of the turning transmission path, so that each of the first and second control units Since the control can be performed in a distributed manner, the amount of calculation can be reduced, and travel control with good responsiveness can be executed. In the second control unit, since the output from the first control unit is received and the output of the turning system transmission path is set, traveling control is executed more smoothly without complicating the calculation. It will be.

  In addition, the work vehicle of the present invention includes an engine mounted on a traveling machine body, a linear transmission path having a first continuously variable transmission, and a turning transmission path having a second continuously variable transmission, and the linear transmission In a work vehicle that drives the left and right traveling units by combining the output of the route and the output of the turning system transmission route, a control unit that controls the output of the straight traveling system transmission route and the output of the turning system transmission route in an interlocking manner And a shift operating tool for designating the output of the straight traveling system transmission path, and a detector for detecting the output of the linear travel system transmission path, and the control unit receives a command value from the transmission operating tool. In addition, the output of the turning system transmission path is set by alternatively selecting the actual measurement value from the detector, so that the output of the turning system transmission path optimum for the traveling state of the traveling machine body is always set. can do. Therefore, the operator can stably maneuver even when the traveling vehicle body turns, thereby improving the maneuverability and executing a stable driving operation.

  In the work vehicle, the linear transmission path includes a forward / reverse switching mechanism, and the forward / backward switching mechanism includes a reverse clutch, a forward low speed clutch, and a forward high speed clutch, The control unit controls so that one of the clutches is always connected at the time of switching between the reverse clutch and the forward low speed side clutch, or at the time of switching between the forward low speed side clutch and the forward high speed side clutch. Thus, since the output of the straight traveling system transmission path is always output, the output of the turning system transmission path can be set to a value that matches the output of the straight traveling system transmission path. Accordingly, it is possible to prevent runaway or the like when the turning operation is executed at the time of clutch switching, thereby contributing to stable operability.

  In the work vehicle, when each clutch is disengaged during traveling, the command value and the actual measurement value are increased by setting the output of the turning system transmission path according to the actual measurement value from the detector. Even when different, it is possible to turn at the turning center and turning radius corresponding to the current running state of the traveling machine body. Therefore, the operator can operate the traveling body without a sense of incongruity, and the smooth maneuverability can be contributed to the operator.

  In the work vehicle, when the brake is operated during traveling, the control unit sets the output of the turning system transmission path according to the actual measurement value from the detector, and the traveling speed is a high speed region where the traveling speed is equal to or higher than a predetermined speed. Then, while controlling each clutch in a disengaged state, in a low speed region where the traveling speed is less than a predetermined speed, control is performed so that any one of the clutches is connected, so that a command value and an actual measurement value are obtained. Can be turned at the turning center and turning radius corresponding to the current traveling state of the traveling machine body. Therefore, the operator can operate the traveling body without a sense of incongruity, and the smooth maneuverability can be contributed to the operator.

  According to the present invention, the traveling machine body can be turned in accordance with the operation amount of the steering handle, which can contribute to improvement in operability. In addition, since the output of the straight traveling system transmission path and the output of the turning system transmission path are linked, not only the vehicle speed at the time of turning becomes close to the operator's sense of steering, but also the behavior of the traveling machine body can be stabilized.

  According to the present invention, the turning center and turning radius of the work vehicle can be changed in accordance with the operation amount of the steering handle. Therefore, the traveling machine body can be turned in a state close to the sense of operation of the steering handle, and as a result, the traveling machine body can be stably driven.

  According to the present invention, since control can be performed in a distributed manner by each of the first and second control units, it is possible to reduce the amount of each calculation and to execute travel control with good responsiveness. And in the 2nd control part, since the output from the 1st control part is received and the output of a turning system transmission course is set up, traveling control is performed more smoothly without the calculation becoming complicated. It becomes.

It is a left view of a tractor. It is a right view of a tractor. It is a top view of a tractor. It is a top view of a traveling body. It is a plane explanatory view of a control seat part. It is a perspective view which shows the structure of the steering handle periphery. It is the perspective view which looked at the control seat part from the left front. It is explanatory drawing which simplified and showed the power transmission system of the mission case for straight advance. It is explanatory drawing which simplified and showed the power transmission system of the mission case for turning. It is a skeleton figure of the power transmission system of a tractor. It is explanatory drawing which shows the relationship between the hydraulic oil discharge amount of a hydraulic mechanical transmission, and a vehicle speed. It is a hydraulic circuit diagram of a tractor. It is a block diagram which shows the structure of the control system of a tractor. It is block explanatory drawing which shows the structure of the traveling control system of a tractor. It is a flowchart which shows the traveling control operation | movement of a tractor. It is explanatory drawing which shows the relationship of the parameter memorize | stored in the deceleration rate table. It is explanatory drawing which shows the relationship of the parameter memorize | stored in the turning / straight drive ratio table. It is explanatory drawing which shows the relationship between the steering angle of a steering handle, and the vehicle speed of a tractor. It is a figure which shows the operation screen for rotation mode selection in the monitor for operation. It is a figure which shows the operation screen for turning force specification in the monitor for operation.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings for a farm tractor. As shown in FIGS. 1 to 4, the traveling machine body 2 of the tractor 1 is supported by a pair of left and right traveling crawlers 3 as traveling portions. A diesel engine 5 (hereinafter simply referred to as an engine) is mounted on the front of the traveling machine body 2, and the traveling crawler 3 is driven by the engine 5 so that the tractor 1 travels forward and backward. The engine 5 is covered with a bonnet 6. A cabin 7 is installed on the upper surface of the traveling machine body 2. Inside the cabin 7, a steering seat 8 and a steering handle 9 for steering the front wheel 3 are arranged. Steps 10 on which the operator gets on and off are provided on the left and right outer sides of the cabin 7. A fuel tank (not shown) that supplies fuel to the engine 5 is provided on the left and right sides of the cabin 7, and the upper side of the fuel tank is covered with left and right rear fenders 21.

  The traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a turning mission case (drive axle) 13, and left and right machine frame 15 detachably fixed to a rear portion of the engine frame 14. The axle 16 is rotatably protruded outward from the left and right ends of the turning mission case 13. Sprockets 62 are attached to the left and right ends of the turning mission case 13 via axles 16. The rear part of the body frame 15 is connected to a straight traveling mission case 17 for appropriately changing the rotational power from the engine 5 and transmitting it to the sprocket 62.

  As shown in FIGS. 1 to 4, left and right track frames 61 are arranged on the lower surface side of the traveling machine body 2. The track frame 61 extends in the front-rear direction and is provided in a pair of left and right sides, and is positioned on both outer sides of the engine frame 14 and the body frame 15. The left and right track frames 61 are connected to the engine frame 14 and the body frame 15 by a lower frame 67 extending in the left-right direction. The front ends of the left and right track frames 61 are connected to the left and right end portions of the turning mission case 13. The left and right central portions of the lower frame 67 are fixed to the rear side surface of the engine frame 14 via a connection bracket 72. Rear beams 73 projecting inward at the rear of the left and right track frames 61 are connected to rear housings 74 fixed to the left and right side surfaces of the straight traveling mission case 17 so that the rear part of the track frame 61 is connected to the left and right side surfaces of the transmission case 17. Fix it.

  The track frame 61 includes a drive sprocket 62 that transmits the power of the engine 5 to the traveling crawler 3, a tension roller 63 that maintains the tension of the traveling crawler 3, and a plurality of track rollers that hold the ground side of the traveling crawler 3 in a grounded state. 64 and an intermediate roller 65 that holds the non-grounding side of the traveling crawler 3. The driving 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 grounding side of the traveling crawler 3, and the intermediate roller 65 supports the non-traveling crawler 3. Support the ground side. The tension roller 63 is rotatably supported by a rear end of a tension frame 69 configured to be extendable and retractable rearward from the rear end of the track frame 71. The track roller 24 is rotatably supported on the front and rear of an equalizer frame 71 supported on the lower portion of the track frame 61 so as to be swingable back and forth.

  A hydraulic lifting mechanism 22 that lifts and lowers a ground working machine (not shown) such as a rotary tiller is detachably attached to the rear portion of the straight traveling case 17. The ground work machine is connected to the rear part of the straight traveling transmission case 17 via a three-point link mechanism 111 including a pair of left and right lower links 23 and a top link 24. A PTO shaft 25 for transmitting a PTO driving force to a working machine such as a rotary tiller is provided on the rear side surface of the straight traveling case 17 so as to protrude rearward.

  As shown in FIGS. 3 and 4, a flywheel 26 is attached to the rear end of the output shaft (piston rod) 5 a of the engine 5 projecting rearward from the rear side surface of the engine 5. A main shaft 27 projecting rearward from the flywheel 26 and an input counter shaft 28 projecting forward from the front side of the straight traveling mission case 17 are connected via a power transmission shaft 29 having universal shaft joints at both ends. . The straight output shaft 30 that protrudes forward from the lower front portion of the straight transmission case 17 has a linear input counter that protrudes backward from the turning mission case 13 via a power transmission shaft 31 having universal joints at both ends. The shaft 508 is connected. The front end of the output shaft (piston rod) 5a of the engine 5 protruding forward from the front side surface of the engine 5 protrudes rearward from the turning mission case 13 via a power transmission shaft 711 having universal joints at both ends. The turning input counter shaft 712 is connected.

  As shown in FIGS. 1 to 4, the hydraulic lifting mechanism 22 is provided with lift fulcrums on the left and right hydraulic lift cylinders 117 that are controlled by operation of the working unit position dial 51 and the upper lid of the transmission case 17. Left and right lift arms 120 that pivotally support the base end side through a shaft so as to be rotatable, and left and right lift rods 121 that connect 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 control, and the length of the right lift rod 121 is configured to be adjustable by the horizontal cylinder 122. When the ground work machine is supported by the top link 24 and the left and right lower links 23, the piston of the horizontal cylinder 122 is expanded and contracted to change the length of the right lift rod 121. The angle is configured to change.

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. A steering column 32 is disposed in front of the control seat 8 in the cabin 7. The steering column 32 is erected in a state of being embedded in 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 the handle shaft 9a that protrudes upward from the upper surface of the steering column 32. A steering angle sensor 821 for detecting the steering angle of the steering handle 9 is embedded in the vicinity of the lower end of the handle shaft 9a below the floor board 40.

  On the right side of the steering column 32, a brake pedal 35 for performing a braking operation on the traveling machine body 2 is disposed. On the left side of the steering column 32, a forward / reverse switching lever 36 (reverser lever) for switching the traveling direction of the traveling machine body 2 between forward and reverse and a power transmission clutch (not shown) are disconnected. A clutch pedal 37 is provided. A parking brake lever 43 for holding the brake pedal 35 in the depressed position is disposed on the rear side of the steering column 32.

  An erroneous operation preventing body 38 (reverser guard) extending along the forward / reverse switching lever 36 is disposed on the left side of the steering column 32 and below the forward / reverse switching lever 36. By disposing an erroneous operation prevention body 38 as a contact preventer below the forward / reverse switching lever 36, the operator is prevented from inadvertently contacting the forward / reverse switching lever 36 when getting on and off the tractor 1. An operation display panel 39 incorporating a liquid crystal panel is provided on the upper rear side of the dashboard 33.

  An accelerator pedal 41 for controlling the rotational speed of the engine 5 or the vehicle speed is arranged on the right side of the steering column 32 on the floor plate 40 in front of the control seat 8 in the cabin 7. Note that substantially the entire top surface of the floor plate 40 is formed as a flat surface. Side columns 42 are arranged on both 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 greatly reducing the traveling speed (vehicle speed) of the tractor 1 and a traveling sub-shift in the straight traveling mission case 17 are provided. An auxiliary transmission lever 45 for switching the output range of the gear mechanism and a PTO transmission lever 46 for switching the drive speed of the PTO shaft 25 are arranged.

  Between the control seat 8 and the right side column 42, an armrest 49 for placing an arm or elbow of an operator seated on the control seat 8 is provided. The armrest 49 is configured separately from the control seat 8 and has a main transmission lever 50 that increases and decreases the traveling speed of the tractor 1 and a dial type that manually changes and adjusts the height position of a ground working machine such as a rotary tiller. Working part position dial 51 (elevating dial). In addition, the armrest 49 is configured to be able to be turned up and rotated in a plurality of stages with the rear end lower part as a fulcrum. In the present embodiment, the vehicle speed of the traveling machine body 2 increases when the main transmission lever 50 is tilted forward, while the vehicle speed of the traveling machine body 2 decreases when the main transmission lever 50 is tilted backward. Furthermore, the armrest 49 includes a potentiometer (variable resistor) type main transmission sensor 822 (see FIG. 13) that detects the forward / backward tilt of the main transmission lever 50.

  The right side column 42 has, in order from the front side, an operation monitor 55 having a touch panel function and capable of commanding each part of the tractor 1, a throttle lever 52 for setting and maintaining the rotational speed of the engine 5, and a PTO shaft 25. A plurality of PTO clutch switches 53 for switching off power transmission from a power tiller to a working machine such as a rotary tiller and a hydraulic external take-off valve (not shown) disposed on the upper surface side of the straight traveling mission case 17. A hydraulic operation lever 54 (SCV lever) is disposed. Here, the hydraulic external take-off valve is for controlling supply of hydraulic oil to hydraulic equipment of another work machine such as a front loader that is retrofitted to the tractor 1.

  Next, the internal structure of the straight traveling mission case 17 and the turning mission case 13 and the power transmission system of the tractor 1 will be described with reference mainly to FIGS. 3, 4, and 8 to 10. In the front chamber of the straight traveling case 17, there are a hydraulic mechanical continuously variable transmission 500 for straight traveling, a mechanical creep transmission gear mechanism 502 for shifting rotational power via a forward / reverse switching mechanism 501, which will be described later, and a traveling auxiliary gear. A transmission gear mechanism 503 is disposed. A forward / reverse switching mechanism 501 that switches 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 transmission case 17 for straight travel. A PTO transmission mechanism 505 that appropriately changes the rotational power from the engine 5 and transmits it to the PTO shaft 25 is disposed in the rear chamber of the straight traveling mission case 17. The creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503 correspond to a traveling transmission gear mechanism that multi-shifts the transmission output via the forward / reverse switching mechanism 501. A pump case 480 accommodating a working machine hydraulic pump 481 driven by the rotational power of the engine 5 and a traveling hydraulic pump 482 is attached to the front part of the right outer surface of the straight traveling case 17.

  A flywheel 26 is directly connected to an output shaft 5a of the engine 5 that protrudes rearward from the rear side surface of the engine 5. An input counter shaft 28 projecting forward from the front side of the straight traveling mission case 17 is connected to a main driving shaft 27 projecting rearward from the flywheel 26 through a power transmission shaft 29 having universal joints at both ends. The rotational power of the engine 5 is transmitted to the input counter shaft 28 of the straight traveling mission case 17 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 auxiliary gear The speed is appropriately changed by the transmission gear mechanism 503. The shifting power via the creep transmission gear mechanism 502 or the traveling auxiliary transmission gear mechanism 503 is transmitted to the traveling gear mechanism 507 in the turning mission case 13 via the front output shaft 30, the power transmission shaft 31, and the straight traveling input counter shaft 508. Is transmitted to.

  In a straight-forward hydraulic mechanical continuously variable transmission (HMT) 500, a main transmission output shaft 512 is concentrically disposed on a main transmission input shaft 511, and a hydraulic pump unit 521, a cylinder block, and a hydraulic motor unit 522 are arranged in series. Are in-line type (in-line type). A main transmission input gear 513 is fitted on the rear end side of the input counter shaft 28 so as not to be relatively rotatable. An input transmission gear 514 that is always meshed with the main transmission input gear 513 is fixed to the rear end side of the main transmission input shaft 511. Accordingly, 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 so as not to rotate relative to each other for traveling output. The input side of the main transmission input shaft 511 and the output side of the main transmission output shaft 512 are located on the same side (both rear 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 constant displacement hydraulic motor unit 522 that is operated by high-pressure hydraulic oil discharged from the hydraulic pump unit 521. The hydraulic pump unit 521 is provided with a pump swash plate 523 that can change the inclination angle with respect to the axis of the main transmission input shaft 511 and adjust the amount of hydraulic oil supplied. A main transmission hydraulic cylinder 524 that changes and adjusts the inclination angle of the pump swash plate 523 with respect to the axis of the main transmission input shaft 511 is linked to the pump swash plate 523. In the embodiment, the main transmission hydraulic cylinder 524 is assembled to the hydraulic mechanical continuously variable transmission 500 and unitized as one member.

  When the main transmission hydraulic cylinder 524 is driven in proportion to the operation amount of the main transmission lever 50, the inclination angle of the pump swash plate 523 with respect to the axis of the main transmission input shaft 511 is changed accordingly. The pump swash plate 523 of the embodiment is angle-adjusted in a range between one (positive) maximum inclination angle and the other (negative) maximum inclination angle with a neutral angle of substantially zero inclination (before and after including zero) interposed therebetween. It is possible to set an angle that is inclined to one of the two times when the vehicle speed of the traveling machine body 2 is the lowest (in this case, an inclination angle that is negative and near 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 substantially the same rotational speed as the main transmission input shaft 511, there is no hydraulic oil supply from the hydraulic pump unit 521, so the output side plunger group of the cylinder block and thus the hydraulic motor unit 522 are not driven. The main transmission output shaft 512 rotates at substantially the same rotational speed as the main transmission input shaft 511.

  When the pump swash plate 523 is tilted in one direction (which may be referred to as a positive tilt angle or a forward tilt angle) with respect to the axis line of the main transmission input shaft 511, the hydraulic pump unit 521 is configured as an input side plunger group. Is pushed and pulled to supply hydraulic oil to the hydraulic motor unit 522, and the hydraulic motor unit 522 is rotated in the same direction as the main transmission input shaft 511 via the output side plunger group of the cylinder block. At this time, because the cylinder block rotates in the same direction and substantially the same rotational speed as the main transmission input shaft 511, the main transmission output shaft 512 rotates at a higher rotational speed than the main transmission input shaft 511. That is, the rotational speed of the hydraulic motor unit 522 is added to the rotational speed of the main transmission input shaft 511 (also referred to as the rotational speed of the cylinder block) and transmitted to the main transmission output shaft 512. As a result, in the range of the rotational speed higher than the rotational speed of the main transmission input shaft 511, the main transmission output is proportional to the inclination angle of the pump swash plate 523 (which may be referred to as a positive inclination angle or a forward rotation inclination angle). The speed change power of the shaft 512 is changed. When the pump swash plate 523 is positive and has an inclination angle near the maximum, the main transmission output shaft 512 rotates at a high speed, but the traveling machine body 2 has an intermediate speed corresponding to the intermediate speed from the lowest speed (substantially zero) to the highest speed. (See the white squares in FIG. 11).

  When the pump swash plate 523 is inclined in the other direction (which may be referred to as a negative inclination angle or a reverse inclination angle) with respect to the axis line of the main transmission input shaft 511, the hydraulic pump unit 521 causes the input-side plunger group to move. The hydraulic oil is supplied to the hydraulic motor unit 522 by pushing and pulling, and the hydraulic motor unit 522 is rotated in the direction opposite to the main transmission input shaft 511 via the output side plunger group of the cylinder block. At this time, the cylinder block rotates in the same direction and substantially the same rotational speed as the main transmission input shaft 511, so that the main transmission output shaft 512 rotates at a lower rotational speed than the main transmission input shaft 511. That is, the rotational speed of the hydraulic motor unit 522 is subtracted from the rotational speed of the main transmission input shaft 511 (which may be referred to as the rotational speed of the cylinder block) and transmitted to the main transmission output shaft 512. As a result, the main transmission output shaft is proportional to the tilt angle of the pump swash plate 523 (which may be referred to as a negative tilt angle or a reverse tilt angle) within a range of rotational speed lower than the rotational speed of the main shift input shaft 511. The shifting power of 512 is changed. When the pump swash plate 523 is negative and has an inclination angle near the maximum, the main transmission output shaft 512 is at the lowest speed (substantially zero) (see the white circle in FIG. 11). Although details will be described later, in the embodiment, when the pump swash plate 523 is negative and has an inclination angle near the maximum, the traveling machine body 2 is configured to have the lowest speed (substantially zero) or the highest speed.

  A pump drive gear 484 is fitted on the pump drive shaft 483 that drives both the working machine and traveling hydraulic pumps 481 and 482 so as not to be relatively rotatable. The pump drive gear 484 connects the main transmission input gear 513 of the input countershaft 28 via a flat gear mechanism 485 so that power can be transmitted. The straight traveling mission case 17 includes a lubricating oil pump 518 that supplies hydraulic oil to the hydraulic mechanical continuously variable transmission 500, the forward / reverse switching mechanism 501 and the like. The pump gear 520 fixed to the pump shaft 519 of the lubricating oil pump 518 is always meshed with the input transmission gear 514 of the main transmission input shaft 511. Therefore, the working machine and traveling hydraulic pumps 481 and 482 and the lubricating oil pump 518 are driven by the rotational power of the engine 5.

  Next, a forward / backward switching structure executed via the forward / reverse switching mechanism 501 will be described. A planetary gear mechanism 526 that is a forward high-speed gear mechanism and a low-speed gear pair 525 that is a forward low-speed gear mechanism are disposed on the rear side of the input counter shaft 28. The planetary gear mechanism 526 includes a sun gear 531 that rotates integrally with an input-side transmission gear 529 that is rotatably supported on the input counter shaft 28, a carrier 532 that rotatably supports a plurality of planetary gears 533 on the same radius, In addition, a ring gear 534 having internal teeth on the inner peripheral surface is provided. 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 so as not to be relatively rotatable. The sun gear 531 meshes with each planetary gear 533 of the carrier 532 from the inside of the radius. Further, the inner teeth of the ring gear 534 mesh with the planetary gears 533 from the radially outer side. An output side transmission gear 530 that rotates integrally 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 constituting the low-speed gear pair 525 are integrated, and can rotate between the planetary gear mechanism 526 and the main transmission input gear 513 in the input counter shaft 28. It is pivotally supported.

  In the straight traveling mission case 17, an input counter shaft 28, a main transmission input shaft 511, and a traveling relay shaft 535 extending in parallel with the main transmission output shaft 512 and a traveling transmission shaft 536 are arranged. A forward / reverse switching mechanism 501 is provided on a travel relay shaft 535 serving as a transmission shaft. That is, the traveling relay shaft 535 has a forward high-speed gear 540 coupled by a wet multi-plate forward high-speed hydraulic clutch 539, a reverse gear 542 coupled by a wet multi-plate reverse hydraulic clutch 541, and a wet multi-plate. A forward low-speed gear 538 connected by a forward low-speed hydraulic clutch 537 of the mold is fitted. A travel relay gear 543 is fitted between the forward high speed hydraulic clutch 539 and the reverse gear 542 in the travel relay shaft 535 so as not to be relatively rotatable. A travel transmission gear 544 that always meshes with the travel relay gear 543 is fitted to the travel transmission shaft 536 so as not to be relatively rotatable. The main transmission low speed gear 515 of the main transmission output shaft 512 is always meshed with the input low speed gear 527 of the low speed gear pair 525 on the input counter shaft 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 is always meshed with the input transmission gear 529 of the planetary gear mechanism 526 on the input counter shaft 28 side, and the output transmission gear 530 is always meshed with the forward high speed gear 540. A main transmission reverse gear 517 of the main transmission output shaft 512 is always meshed 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 forward high-speed gear 540 and the travel relay shaft 535 are connected to each other so as not to be relatively rotatable. Is done. As a result, forward low-speed or high-speed rotational power is transmitted from the main transmission output shaft 512 to the travel relay shaft 535 via the low-speed gear pair 525 or the planetary gear mechanism 526, and power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536. Communicated. When the forward / reverse switching lever 36 is operated to the reverse side, the reverse hydraulic clutch 541 enters a power connection state, and the reverse gear 542 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the reverse rotational power 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 motive power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536.

  Note that which of the forward low-speed hydraulic clutch 537 and the forward high-speed hydraulic clutch 539 is in the power connection state by the forward operation of the forward / reverse switching lever 36 is determined according to the operation amount of the main transmission lever 50. When the forward / reverse switching lever 36 is in the neutral position, all the hydraulic clutches 537, 539, and 541 are in the power cut state, and the traveling drive force from the main transmission output shaft 512 is substantially zero (the main clutch disengaged state). )become.

  Here, FIG. 11 shows the relationship between the hydraulic oil discharge amount (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 speed change lever 50 is neutrally operated regardless of the operating state of the forward / reverse switching lever 36, the pump swash plate 523 is negative and has an inclination angle near the maximum (reverse rotation inclination) by driving the main speed change hydraulic cylinder 524. (See white circles), the main transmission output shaft 512 and the travel relay shaft 535 are in the lowest speed rotation state (substantially zero). As a result, the vehicle speed of the tractor 1 becomes substantially zero.

  When the main transmission lever 50 is operated from the neutral to the intermediate speed while the forward / reverse switching lever 36 is operated to the forward side, the pump swash plate 523 is negative and maximum when the main transmission hydraulic cylinder 524 is driven. It changes from a nearby inclination angle (reverse rotation inclination angle) through zero to a positive and maximum vicinity inclination angle (forward rotation inclination angle) (see white squares), and from the hydraulic motor unit 522 to the main transmission output shaft 512. The speed change power is increased 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 travel relay shaft 535 are connected so as not to be relatively rotatable. As a result, the forward low-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, and the traveling relay shaft 535 is rotated at the lowest speed by the increased 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 region FL). Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536.

  When the main transmission lever 50 is operated from the intermediate speed to the maximum speed while the forward / reverse switching lever 36 is operated to the forward side, the inclination angle is positive and near the maximum by driving the main transmission hydraulic cylinder 524. (Forward rotation tilt angle) changes from zero to a negative and maximum tilt angle (reverse rotation tilt angle) through zero, and the pump swash plate 523 shifts the shift power from the hydraulic motor unit 522 to the main shift output shaft 512 from a high speed. Decelerate to almost 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 travel 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 travel relay shaft 535 via the planetary gear mechanism 526. That is, after the power from the engine 5 and the deceleration power to the main transmission output shaft 512 are combined in the planetary gear mechanism 526, the travel relay shaft 535 is moved from the forward intermediate speed rotation state to the forward maximum speed rotation state by the combined power. Change (see forward high speed range FH). Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536. The traveling machine body 2 has the highest speed.

  When the main transmission lever 50 is operated from the neutral side to the acceleration side 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 is reached. It changes from (reverse rotation tilt angle) to a positive and near-maximum tilt angle (forward rotation tilt angle) through zero, and the shift power from the hydraulic motor unit 522 to the main shift output shaft 512 is increased 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 travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the reverse rotational power 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 driven by the increased power to the main transmission output shaft 512. Changes from the lowest speed rotation state to the reverse high speed rotation state (see reverse region R). Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536.

  In the embodiment, the swash plate inclination angle of the hydraulic pump unit 521 is changed from the normal rotation inclination angle to the reverse rotation inclination angle through zero to reduce the transmission power to the main transmission output shaft 512 from high speed to zero, In the planetary gear mechanism 526, the power from the engine 5 and the deceleration power to the main transmission output shaft 512 are combined, and the transmission shaft 535 is changed from the forward intermediate speed rotation state to the forward maximum speed rotation state by the combined power. Thus, without increasing the capacity of the hydraulic mechanical continuously variable transmission 500, it is possible to reliably realize the expansion of the shiftable range using the planetary gear mechanism 526, and to increase the efficiency and light weight of the hydraulic mechanical transmission 500. It is possible to accurately achieve both reduction in cost and cost and increase in output of the straight traveling mission case 17.

  Further, in the embodiment, the swash plate inclination angle of the hydraulic pump unit 521 is changed from the reverse rotation inclination angle to the forward rotation inclination angle through zero, thereby increasing the shift power to the main transmission output shaft 512 from zero to high speed. Since the transmission shaft 535 is changed from the lowest speed rotation state to the forward intermediate speed rotation state by the accelerating power to the main transmission output shaft 512, the output at the time of zero start for starting the tractor 1 from the state where the initial speed is zero. Torque can be secured reliably. Therefore, it is possible to improve the slow speed performance of the tractor 1 while achieving both high efficiency, light weight and low cost of the hydraulic mechanical transmission 500 and high output of the straight traveling mission case 17.

  Next, an ultra-low speed, low-speed and high-speed switching structure executed through the creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503, which are traveling transmission gear mechanisms, will be described. In the straight transmission case 17, 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 that extends coaxially with the traveling transmission shaft 536. A shaft 545 and an auxiliary transmission shaft 546 extending in parallel with the travel counter shaft 545 are disposed.

  A transmission gear 547 and a creep gear 548 are provided on the rear side of the travel counter shaft 545. The transmission gear 547 is rotatably fitted to the travel counter shaft 545 and connected to the travel transmission shaft 536 so as to rotate integrally. The creep gear 548 is fitted on the travel counter shaft 545 so as not to be relatively rotatable. A creep shifter 549 is spline-fitted between the transmission gear 547 and the creep gear 548 of the travel counter shaft 545 so as not to be relatively rotatable and slidable in the axial direction. The creep shifter 549 slides by turning the ultra low speed lever 44 on and off, and the transmission gear 547 and the creep gear 548 are alternatively connected to the travel counter shaft 545. A reduction gear pair 550 is rotatably fitted to 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 have an integral structure, and the transmission gear 547 of the travel counter shaft 545 always meshes with the input side reduction gear 551 of the auxiliary transmission shaft 546, The creep gear 548 is always 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 travel counter shaft 545. The low speed relay gear 553 is fixed to the travel counter shaft 545. The high-speed relay gear 554 is fitted on the travel counter shaft 545 so as not to be relatively rotatable. A low-speed gear 555 that meshes with the low-speed relay gear 553 and a high-speed gear 556 that meshes 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. A sub-transmission shifter 557 is spline-fitted between the low-speed gear 555 and the high-speed gear 556 in the sub-transmission shaft 546 so as not to be relatively rotatable and slidable in the axial direction. By operating the sub transmission lever 45, the sub transmission shifter 557 slides and the low speed gear 555 and the high speed gear 556 are alternatively connected to the sub transmission shaft 546.

  Further, a straight traveling relay shaft 582 and a straight traveling output shaft 30 extending in parallel with the travel counter shaft 545 and the auxiliary transmission shaft 546 are disposed. A driven gear 570 fitted to the straight-traveling relay shaft 568 so as not to rotate relative to the main driving gear 83 fitted to the front end side of the auxiliary transmission shaft 546 so as not to rotate relatively is always meshed. A straight travel relay gear 582 fitted on the front end side of the straight travel relay shaft 568 so as not to rotate relative to the straight travel relay shaft 568 is always meshed with a straight travel output gear 583 fitted on the straight travel output shaft 30 so as not to rotate relatively.

  The main drive gear 569 of the subtransmission shaft 546, the driven gear 570 and the rectilinear relay gear 572 of the rectilinear relay shaft 568, and the rectilinear output gear 573 of the rectilinear output shaft 30 are used to linearly rotate the subtransmission shaft 456. A straight output gear mechanism 568 for transmitting power to the output shaft 30 is configured. The rectilinear output gear mechanism 568 is provided with a rectilinear pickup rotation sensor (straight vehicle speed sensor) 823, and the rectilinear pickup rotation sensor 823 detects the rotational speed of the rectilinear output (straight vehicle speed). For example, the straight traveling relay gear 582 is disposed so as to face the straight traveling pickup rotation sensor 823, and the rotational speed of the straight traveling output (straight traveling vehicle speed) is detected from the rotational speed of the straight traveling relay gear 582.

  In the embodiment, when the super low speed lever 44 is turned on and the sub transmission lever 45 is operated to the low speed side, the creep gear 548 is connected to the travel counter shaft 545 so as not to be relatively rotatable, and the low speed gear 555 is connected to the sub transmission shaft 546. It is connected so that it cannot rotate relative to the traveling transmission shaft 536, travel counter shaft 545, auxiliary transmission shaft 546, and straight traveling relay shaft 568. Is output. The ultra-low speed lever 44 and the auxiliary transmission lever 45 are interlocked and connected via a shift check member (details will be described later), and the high-speed side operation of the auxiliary transmission lever 45 and the entry operation of the ultra-low speed lever 45 are performed. It is configured to prohibit compatibility. That is, the sub-shift lever 45 cannot be operated to the high speed side when the ultra-low speed lever 44 is operated and the ultra-low speed lever 44 cannot be operated when the sub-speed lever 45 is operated to the high speed side. .

  When the super 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 to the travel counter shaft 545 so as not to rotate relative to it, and the low speed gear 555 cannot be rotated relative to the sub transmission shaft 546. To the transmission case 13 through the traveling transmission shaft 536, the traveling counter shaft 545, the sub-transmission shaft 546, the straight traveling relay shaft 568, and the like. Is done. When the super 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 travel counter shaft 545 so as not to rotate relative to it, and the high speed gear 556 cannot be rotated relative to the sub transmission shaft 546. The traveling drive shaft 536 outputs a traveling drive force at a higher speed than the straight traveling output shaft 30 to the turning mission case 13 via the traveling transmission shaft 536, the traveling counter shaft 545, the auxiliary transmission shaft 546, the straight traveling relay shaft 568, and the like. The

  A straight transmission input countershaft 508 that protrudes backward from the turning mission case 13 and a straight output shaft 30 that protrudes forward from the lower front portion of the straight transmission case 17 are connected by a power transmission shaft 31. The turning mission case 13 includes a turning hydraulic continuously variable transmission (HST) 701 for appropriately changing the rotational power from the engine 5, and an output rotation from the hydraulic continuously variable transmission 701 to the left and right traveling crawlers 3 ( A differential gear mechanism 702 that transmits to the sprocket 62), and a pair of left and right planetary gear mechanisms 703 that combine the rotational power from the differential gear mechanism 702 and the rotational power from the straight traveling mission case 17.

  In the hydraulic continuously variable transmission 701, a pair of hydraulic pump units 704 and a hydraulic motor unit 705 are arranged in parallel, and the power transmitted to the pump shaft 706 is transferred from the hydraulic pump unit 704 to the hydraulic motor unit 705. The hydraulic oil is fed appropriately. A charge pump 707 for supplying hydraulic oil to the hydraulic pump 704 and the hydraulic motor 705 is attached to the pump shaft 706. The turning hydraulic continuously variable transmission mechanism 701 changes the discharge angle and discharge amount of the hydraulic oil to the hydraulic motor unit 705 by changing and adjusting the inclination angle of the pump swash plate 708 in the hydraulic pump unit 704, thereby changing the hydraulic pressure. The motor shaft 709 protruding from the motor 705 is configured to arbitrarily adjust the rotation direction and the number of rotations.

  In the turning mission case 13, the turning input counter shaft 712 is arranged 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 as not to be relatively rotatable. ing. Between the turning input counter shaft 712 and the pump shaft 706, a turning relay shaft 714 is arranged in parallel with 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 on the turning relay shaft 714 so as not to rotate relative to the pivot shaft 714. A pump input gear 710 that is always meshed with the turning relay gear 715 is fitted to the pump shaft 706 so as not to be relatively rotatable, and the rotational power transmitted from the engine 5 transmitted to the turning input counter shaft 712 is turned. It is transmitted to the pump shaft 706 via the relay shaft 714 for use.

  In the turning mission case 13, a differential gear mechanism 702 is configured by a bevel gear mechanism in which a pair of left and right side gears 717 are meshed with both sides of a pinion 716 that is fitted to the rear end of the motor shaft 709 so as not to rotate relatively. Yes. In addition, the differential gear mechanism 702 has a pair of left and right turning output shafts 718 each having a side gear 717 fitted at one end thereof so as not to rotate relative to each other. A turning output gear 719 for transmitting power to the pair of left and right planetary gear mechanisms 703 is fitted to the other end of each of the pair of left and right turning output shafts 718 so as not to be relatively rotatable.

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

  The hydraulic motor unit 705 of the turning hydraulic type continuously variable transmission mechanism 701 is provided with a turning pickup rotation sensor (turning vehicle speed sensor) 824, and the turning pickup rotation sensor 824 detects the rotation speed of the turning output (turning vehicle speed). It is configured to do. For example, a turning pulse generating rotating wheel is provided on the motor shaft 709, and a turning pickup rotation sensor 824 is arranged to face the turning pulse generating rotating wheel, and depending on the number of rotations of the turning pulse generating rotating wheel, The number of rotations of the straight output (turning vehicle speed) is detected.

  In the turning mission case 13, a brake mechanism 751 connected to the brake pedal 35 via the brake link body 750 is provided on the straight-going input counter shaft 508 to which the rotational power from the straight-running mission case 17 is transmitted. . Then, the linear input gear 720 is fitted to the front end of the linear input counter shaft 508 so as not to be relatively rotatable. Further, the straight travel relay shaft 721 is arranged in parallel with the straight travel input counter shaft 508, and the straight travel relay gear 722 that is always meshed with the straight travel input gear 720 is not rotatable relative to the straight travel relay shaft 721. It is fitted.

  A bevel gear mechanism is provided in which a ring gear 724 is engaged with a pinion 723 that is fitted to the rear end of the linear relay shaft 721 so as not to be relatively rotatable. It is put on. Both ends of the straight output shaft 725 are connected to a pair of left and right planetary gear mechanisms 703, respectively. The rotational power (straight forward rotational power) from the straight traveling mission case 17 input to the straight traveling input counter shaft 508 is transmitted to the pair of left and right planetary gear mechanisms 703 via the straight traveling output shaft 725. In addition, the brake mechanism 751 performs a braking operation in accordance with the operation of the brake pedal 35, so that the rotational power of the straight output shaft 725 is attenuated or stopped.

  The left and right planetary gear mechanisms 703 rotate one sun gear 726, a plurality of planet gears 727 meshed with the sun gear 726, a ring gear 728 meshed with the turning output gear 719, and a plurality of planet gears 727 on the same circumference. And a carrier 729 which can be arranged. The carriers 729 of the left and right planetary gear mechanisms 703 are arranged on the same axis so as to face each other with an appropriate interval. The left and right sun gears 726 are fixed to both ends of a straight output shaft 725 in which a ring gear 724 is fitted in the middle.

  The left and right ring gears 728 are rotatably fitted to the straight output shaft 725, and the external teeth on the outer peripheral surface thereof are engaged with the left and right turning output gears 719 to be connected to the turning 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 to the left and right differential output shafts 730. The left and right output transmission gears 731 that rotate together 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. The left and right differential output shafts 730 are connected to the left and right relay shafts 735 via relay gears 733 and 734, and the left and right relay shafts 735 are connected to the left and right axles 16 via final gears 736 and 737. ing.

  Each of the left and right planetary gear mechanisms 703 receives rotational power from the straight traveling mission case 17 via the straight traveling relay shaft 721 and the straight traveling output shaft 725, and rotates the sun gear 726 at the same rotational speed in the same direction. . That is, the left and right sun gears 726 receive the rotational power from the straight traveling mission case 17 as straight forward rotation, and transmit it to the differential output shaft 730 through the planetary gear 727 and the output side transmission gear 731. Therefore, the rotational power transmitted from the straight traveling mission case 17 to the left and right planetary gear mechanisms 703 is transmitted from the left and right axles 16 to the drive sprockets 62 at the same rotational speed in the same direction, and the left and right traveling crawlers 3 are transmitted to the same. Driven at the same number of rotations in the direction, the traveling machine body 1 moves straight (forward, backward).

  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 cause the ring gear 728 to rotate in the opposite directions at the same rotational speed. Rotate. That is, the left and right ring gears 728 receive the rotational power from the hydraulic motor unit 705 as turning rotation, and the carrier 729 causes the turning rotation to be superimposed on the straight rotation from the sun gear 726 to rotate the planetary gear 727 and the output side transmission gear 731. . As a result, the rotational power obtained by adding the rotational rotation to the straight 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. Rotational power obtained by subtracting the turning rotation from the rectilinear rotation is transmitted through the planetary gear 727 and the output side transmission gear 731.

  The speed change outputs from the linear input counter shaft 508 and the motor shaft 709 are transmitted to the drive sprockets 62 of the left and right traveling crawlers 3 via the left and right planetary gear mechanisms 703, respectively, so that the vehicle speed (traveling speed) of the traveling machine body 2 is increased. ) And the direction of travel is determined. That is, when the rotational power from the straight traveling mission case 17 is input to the straight traveling input counter shaft 508 with the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 stopped and the left and right ring gears 728 stationary and fixed. The rotation of the input counter shaft 508 for straight travel is transmitted to the left and right sun gears 71 at the same left and right rotational speed, the left and right traveling crawlers 3 are driven at the same rotational speed in the same direction, and the traveling machine body 2 travels straight.

  On the contrary, when the rotation of the straight traveling transmission case 17 by the straight traveling output shaft 30 is stopped or by the braking action of the brake mechanism 750, the rotation of the straight traveling input counter shaft 508 is stopped and the left and right sun gears 71 are fixed stationary. In this state, when the hydraulic motor unit 705 of the hydraulic continuously variable transmission 701 is driven, the rotational power from the motor shaft 709 causes the left ring gear 728 to rotate forward (reverse) and the right ring gear 728 to reverse Rotate (forward rotation). As a result, one of the drive sprockets 62 of the left and right traveling crawlers 3 is rotated forward, the other is rotated backward, and the traveling machine body 2 is turned on the spot (revolution turning spin turn).

  Further, the left and right traveling crawlers 3 are driven by driving the left and right ring gears 728 by turning the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 while driving the left and right sun gears 726 by rotating straight from the transmission case 17 for straight traveling. The traveling body 2 turns left or right (U-turn) with a turning radius larger than the belief 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, the drive speed switching structure (three forward rotations and one reverse rotation) of the PTO shaft 25 executed via the PTO transmission mechanism 505 will be described. The straight traveling mission case 17 is provided with a PTO transmission mechanism 505 that transmits power from the engine 5 to the PTO shaft 25. 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 interruption. Further, the straight traveling mission case 17 is provided with a PTO transmission shaft 592, a PTO counter shaft 593, and a PTO shaft 25 extending in parallel with the PTO input shaft 591. The PTO shaft 25 protrudes rearward from the rear surface of the straight traveling mission case 17.

  When the power connection operation is performed on the PTO clutch switch 53, the PTO hydraulic clutch 590 is in a power connection state, and the main transmission input shaft 511 and the PTO input shaft 591 are coupled so as not to be relatively rotatable. As a result, rotational power is transmitted from the main transmission input shaft 511 toward 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 shifter gear 598 in 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 so as not to be relatively rotatable. The reverse shifter gear 598 is spline-fitted to the PTO input shaft 591 so as not to rotate relative to the PTO input shaft 591 and to be slidable in the axial direction.

  On the other hand, the PTO transmission shaft 592 is rotatably fitted with a PTO medium speed gear 601 that meshes with the medium speed input gear 597, a PTO low speed gear 599 that meshes with the low speed input gear 595, and a PTO high speed gear 600 that meshes with the high speed input gear 596. doing. A pair of front and rear PTO transmission shifters 602 and 603 are spline-fitted to the PTO transmission shaft 592 so as not to be 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 speed shifter 603 is disposed on the rear end side with respect 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. A PTO transmission gear 604 is fixed between the PTO low-speed gear 599 and the PTO high-speed gear 600 in the PTO transmission shaft 592.

  The PTO counter shaft 593 has a PTO counter gear 605 that meshes with the PTO transmission gear 604, a PTO relay gear 606 that meshes with a PTO output gear 608 that is non-rotatably fitted to the PTO shaft 25, and a PTO reverse gear 607. It is impossible to fit. When the sub-PTO lever 48 is engaged with the PTO speed change lever 46 in a neutral state, the reverse shifter gear 598 slides and the reverse shifter gear 598 meshes with the PTO reverse gear 607 of the PTO counter shaft 593. 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 595, the PTO medium speed gear 597, and the PTO high speed gear 596 are moved to the PTO shift shaft. 592 is alternatively connected. As a result, the low-speed to high-speed PTO shift outputs are transmitted from the PTO shift shaft 592 to the PTO counter shaft 593 via the PTO transmission gear 604 and the PTO counter gear 605, and further, the PTO relay gear 607 and the PTO output gear 608 are transmitted. Is transmitted to the PTO shaft 25.

  When the sub PTO lever 48 is turned on and operated, the reverse shifter gear 598 is engaged 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 shifter gear 598 and the PTO reverse gear 607. Then, the reverse PTO shift output is transmitted from the PTO counter shaft 593 to the PTO shaft 25 via the PTO relay gear 607 and the PTO output gear 608.

  Note that the PTO speed change lever 46 and the sub PTO lever 48 are interlocked and connected via a PTO restraining member (details will be described later). It is configured to prohibit both coexistence. In other words, the PTO speed change lever 46 cannot be shifted to any position other than neutral when the sub PTO lever 48 is engaged, and the sub PTO lever 48 cannot be engaged when the speed change operation is performed other than neutral. ing.

  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 that are driven by the rotational power of the engine 5. In the embodiment, the straight traveling mission case 17 is used as a working oil tank, and the working oil in the straight traveling mission 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 passage 623 that connects the hydraulic pump 521 and the hydraulic motor 522 in the straight-forward hydraulic mechanical continuously variable transmission 500. While the engine 5 is being driven, the hydraulic oil from the traveling hydraulic pump 482 is always replenished to the closed loop oil passage 623.

  The traveling hydraulic pump 482 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 electromagnetic valve 627 for the PTO hydraulic clutch 590, and a switching valve 628 operated thereby. And connected to. Further, the traveling hydraulic pump 482 includes a forward low speed clutch electromagnetic valve 632 that operates the forward low speed hydraulic clutch 537, a forward high speed clutch electromagnetic valve 633 that operates the forward high speed hydraulic clutch 539, and a reverse clutch that operates the reverse hydraulic clutch 541. The solenoid valve 634 is connected to a master control solenoid valve 635 that controls the supply of hydraulic oil to the clutch solenoid valves 632 to 634.

  In addition, the work machine hydraulic pump 481 is connected to a control valve mechanism 635 that supplies hydraulic oil to the left and right hydraulic lift cylinders 117 in the hydraulic lifting mechanism 22. Although not shown, the control valve mechanism 635 includes a plurality of hydraulic external take-out valves stacked on the upper surface of the hydraulic lifting mechanism 22 on the rear side of the upper surface of the straight traveling mission case 17 and a horizontal cylinder provided on the right lift rod 121. An inclination control solenoid valve that controls the supply of hydraulic oil to 122, an ascending hydraulic pressure switching valve and a descending hydraulic pressure switching valve that control the hydraulic oil supply to the hydraulic lift cylinder 117 in the hydraulic lifting mechanism 22 are provided.

  In the control valve mechanism 635, when the tilt control electromagnetic valve is switched and driven, the horizontal cylinder 122 expands and contracts, and the right lower link 23 moves up and down using the lower link pin on the front side as a fulcrum. As a result, the ground work machine 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 tilt angles of the ground work machine change. When the raising hydraulic pressure switching valve or the lowering hydraulic pressure switching valve is switched, the hydraulic lift cylinder 117 expands and contracts, and both the lift arm 120 and the left and right lower links 23 move up and down. As a result, the ground work machine moves up and down, and the height position of the ground work machine changes.

  The hydraulic circuit 620 of the tractor 1 includes a charge pump 707 that is driven by the rotational power of the engine 5, and the charge pump 707 connects the hydraulic pump 702 and the hydraulic motor 703 in the turning hydraulic continuously variable transmission 701. It is connected to a closed loop oil passage 740. In the embodiment, the straight traveling mission case 17 is used as a working oil tank, and hydraulic oil in the straight traveling mission case 17 is supplied to the charge pump 707. Further, the working oil from the charge pump 707 is always replenished to the closed loop oil passage 740 while the engine 5 is being driven. The hydraulic circuit 620 of the tractor 1 includes a swing hydraulic cylinder 741 that changes the angle of the pump swash plate 708 of the hydraulic pump 702 in the hydraulic continuously variable transmission 701, and a swing hydraulic pressure switching valve 742 for the swing hydraulic cylinder 741.

  The hydraulic circuit 620 of the tractor 1 includes a lubricating oil pump 518 that is driven by the rotational power of the engine 5 in addition to the aforementioned working machine hydraulic pump 481 and traveling hydraulic pump 482. The lubricating oil pump 518 includes a PTO clutch hydraulic pressure 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 lubrication section, the forward low speed clutch hydraulic pressure switching valve 642 that supplies hydraulic oil (lubricating oil) to the lubrication section of the forward low speed hydraulic clutch 537, and the forward movement that supplies hydraulic oil (lubricating oil) to the lubrication section of the forward high speed hydraulic clutch 539. The high-speed clutch hydraulic pressure switching valve 643 is connected to a reverse clutch hydraulic pressure switching valve 644 that 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 the traveling control of the tractor 1 will be described with reference to FIGS. As shown in FIG. 13, the tractor 1 includes an engine controller 811 that controls the driving of the engine 5, a meter controller 812 that controls the display operation of the operation display panel (meter panel) 39 mounted on the dashboard 33, A linear controller 813 and a turning controller 814 that perform speed control and the like are provided.

  The controllers 811 to 814 and the operation monitor 55 are each a CPU for executing various arithmetic processes and controls, a ROM for storing control programs and data, a RAM for temporarily storing control programs and data, A timer for time measurement, an input / output interface, and the like are provided, and are connected to each other via a CAN communication bus 815 so as to communicate with each other. The engine controller 811 and the meter controller 812 are connected to the battery 817 via the power application key switch 816.

  Based on the control by the engine controller 811, in the engine 5, the fuel in the fuel tank is pumped to the common rail by the fuel pump and stored as high-pressure fuel in the common rail. The engine controller 811 controls the opening and closing (electronic control) of each fuel injection valve so that the high-pressure fuel in the common rail (not shown) can accurately control the injection pressure, the injection timing, and the injection period (injection amount). After being controlled, each injector (not shown) is injected into each cylinder of the engine 5.

  A steering angle sensor (steering potentiometer) 821 for detecting a rotation amount (steering angle) of the steering handle 9 is connected to the input side of the meter controller 812. In addition, a liquid crystal panel and various alarm lamps in the meter panel 39 are connected to the output side of the meter controller 812. The meter controller 812 receives a detection signal from the steering angle 821 and detects the steering angle of the steering handle 9. Further, the meter controller 812 outputs various signals to the meter panel 39, and controls alarm lamp turn-on / off operation, blinking operation, liquid crystal panel display operation, alarm buzzer alarming operation, and the like.

  On the input side of the rectilinear controller 813, there are a main shift sensor (main shift potentiometer) 822 for detecting the operation position of the main shift lever 50, and a straight pick-up rotation sensor (straight vehicle speed sensor) for detecting the rotation speed (straight vehicle speed) of the straight output. 823, a forward / reverse sensor (forward / reverse potentiometer) 825 for detecting the operation position of the forward / reverse switching lever 36, a sub-transmission sensor 826 for detecting the operation position of the sub-transmission lever 45, and a creep for detecting the operation position of the ultra-low speed lever 44) A sensor 827, a brake sensor 828 that detects depression of the brake pedal 35, and a clutch sensor 829 that detects depression of the clutch pedal 37 are connected.

  On the output side of the rectilinear controller 813, a forward low speed clutch electromagnetic valve 632 that operates the forward low speed hydraulic clutch 537, a forward high speed clutch electromagnetic valve 633 that operates the forward high speed hydraulic clutch 539, and a reverse clutch electromagnetic valve that operates the reverse hydraulic clutch 541. 634 and a main transmission hydraulic pressure switching valve 624 that operates the main transmission hydraulic cylinder 524 in accordance with the tilting operation amount of the main transmission lever 50 is connected.

  A turning rotation sensor (turning vehicle speed sensor) 824 for detecting the rotation speed (turning vehicle speed) of the turning output is connected to the input side of the turning controller 814, while the steering handle 9 is connected to the output side of the turning controller 813. A swing hydraulic pressure switching valve 742 for operating the swing hydraulic cylinder 741 according to the rotation operation amount is connected.

  As shown in FIG. 14, the rectilinear controller 813 includes a rectilinear travel calculation unit 831 that controls the output of a rectilinear transmission path having a hydraulic mechanical continuously variable transmission (first continuously variable transmission) 500, and steering of the steering handle 9. A memory 832 that stores a deceleration rate table TA (see FIG. 16) that stores a deceleration rate of a straight vehicle speed with respect to a corner, and a communication interface 833 connected to the CAN communication bus 815 are provided. As shown in FIG. 15, the straight traveling calculation unit 831 receives a signal from the forward / reverse sensor 825, recognizes whether “forward”, “neutral”, or “reverse” is designated, and performs the auxiliary transmission sensor 826 and creep. In response to the signal from the sensor 827, it is recognized which one of “high speed”, “low speed”, and “super low speed” is designated (STEP 1). The straight travel calculation unit 831 receives a signal from the main speed change sensor 822 and calculates a target value of the straight vehicle speed (hereinafter referred to as “straight forward reference target value”) in the straight travel state (the steering angle is 0 °). (STEP 2).

  The rectilinear controller 813 receives the signal from the steering angle sensor 821 through the meter controller 812 by the communication interface 833, and gives the signal from the steering angle sensor 821 to the rectilinear travel calculation unit 831 (STEP 3). When the straight traveling calculation unit 831 receives the signal from the steering angle sensor 821 and recognizes the steering angle of the steering handle 9, it reads the deceleration rate of the straight vehicle speed based on the deceleration rate table TA in the memory 832 (STEP 4). . The straight travel calculation unit 831 then multiplies the straight deceleration reference target value based on the signal from the main transmission sensor 822 by the read deceleration rate, thereby obtaining a straight vehicle speed target value corresponding to the steering angle (hereinafter referred to as “straight travel target”). Value ”) is calculated (STEP 5). The “straight vehicle speed” in the straight travel reference target value and the straight travel target value is a relative speed of the rotational speed of the traveling transmission shaft 536 in the straight traveling mission case 17 with respect to the rotational speed of the engine 5.

  The straight traveling calculation unit 831 receives signals from the brake sensor 828 and the clutch pedal sensor 829 and confirms whether or not the brake pedal 35 and the clutch pedal 37 are depressed (STEP 6). The rectilinear travel calculation unit 831 uses the rectilinear pickup rotation sensor 823 when there is a depression operation on at least one of the brake pedal 35 and the clutch pedal 37 or when the forward / reverse switching lever 36 is in the neutral position (Yes in STEP 7). Is transmitted from the communication interface 833 to the travel controller 814 (STEP 8). On the other hand, the straight traveling calculation unit 831 calculates when there is no depression operation on at least one of the brake pedal 35 and the clutch pedal 37, or when the forward / reverse switching lever 36 is in the forward position or the reverse position (No in STEP 7). The straight target value is transmitted from the communication interface 833 to the travel controller 814 (STEP 9).

  When the straight travel target value is calculated, the straight travel calculation unit 831 controls the operations of the forward low speed clutch solenoid valve 632, the forward high speed clutch solenoid valve 633, and the main transmission hydraulic pressure switching valve 624 in the case of forward travel, while in the case of reverse travel. Controls the operation of the reverse clutch solenoid valve 634 and the main transmission hydraulic pressure switching valve 624. At this time, the rectilinear travel calculation unit 831 feeds back the output of the rectilinear transmission path (rotation speed by the rectilinear output shaft 30) based on the rectilinear measured value (signal from the rectilinear pickup rotation sensor 823) and the rectilinear target value. Control (main shift control) is performed (STEP 10). It should be noted that the rotational speed of the traveling transmission shaft 536 is confirmed from the signal from the straight-ahead pickup rotation sensor 823 based on the transmission gear ratio specified by the signals from the auxiliary transmission sensor 826 and the creep sensor 827, and compared with the straight-ahead target value. Thus, the output of the straight-ahead transmission path is controlled.

  As shown in FIG. 14, the turning controller 814 includes a turning travel calculation unit 841 that controls the output of the turning system transmission path having a hydraulic continuously variable transmission (second continuously variable transmission) 701, and the steering angle of the steering handle 9. A memory 842 that stores a turn / straight ratio ratio table TB (see FIG. 17) that stores a turn / straight ratio of a straight vehicle speed and a turning vehicle speed, and a communication interface 843 that is connected to the CAN communication bus 815. As shown in FIG. 15, the turning controller 814 receives the signal from the steering angle sensor 821 through the meter controller 812 by the communication interface 843, and gives the signal from the steering angle sensor 821 to the turning travel calculation unit 841 (STEP 51). When the turning travel calculation unit 841 receives the signal from the steering angle sensor 821 and recognizes the steering angle of the steering handle 9, it reads the turning / straight forward ratio based on the turning / straight forward ratio table TB in the memory 842 (STEP 52). ).

  Further, the turning controller 814 receives signals from the auxiliary transmission sensor 826 and the creep sensor 827 through the straight-line controller 813 by the communication interface 843, and provides the signals to the turning calculation unit 841 (STEP 53). The turning travel calculation unit 841 recognizes whether “high speed”, “low speed”, or “ultra-low speed” is designated as the sub-shift based on signals from the sub-shift sensor 826 and the creep sensor 827. The turning traveling calculation unit 841 reads the correction value of the turning / straight-ahead ratio from the memory 842 based on the designated sub-shift, and corrects the turning / straight-ahead ratio based on the designated sub-shift (STEP 54).

  Further, the turning controller 814 receives the straight target value or the straight measured value (signal from the straight pick-up pickup rotation sensor 823) calculated by the straight controller 813 by the communication interface 843, and gives it to the turning calculation unit 841 (STEP 55). ). The turning travel calculation unit 841 confirms the straight traveling vehicle speed from the straight traveling target value or the straight traveling actual measurement value, and calculates the turning target value to be 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 mission case 13 with respect to the rotational speed of the engine 5.

  When the turning travel calculation unit 841 calculates the turning target value, it 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 actual measurement value”) and the turning target value. (Speed) is feedback controlled (turning control) (STEP 57).

  When the main speed control is being executed, the linear controller 813 switches the forward low-speed clutch solenoid valve 632 and the reverse clutch when the signal from the forward / reverse sensor 825 is switched from “forward to backward” or “backward to forward”. The electromagnetic valve 634 is controlled to switch between 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 linear controller 813 performs control so that one of the forward low speed hydraulic clutch 537 and the reverse hydraulic clutch 541 is always connected.

  At this time, the main shift hydraulic pressure switching valve 624 is controlled by changing the rectilinear reference target value (or the rectilinear target value) so that the main shift output shaft 512 and the travel relay shaft 535 are in the lowest speed rotation state, and then again. The rotational speeds of the main transmission output shaft 512 and the travel relay shaft 535 are increased so that the original rotational speed is obtained. Therefore, the turning controller 814 can change the turning target value in the same way as the straight traveling target value by receiving the straight traveling target value from the straight traveling controller 813. Thereby, the turning controller 814 can reverse the output (turning vehicle speed) of the turning system transmission path with respect to the operation of the steering handle 9 when the traveling machine body 2 moves forward and backward, thereby contributing to smooth controllability to the operator.

  When the main shift control is being executed and the signal from the forward / reverse sensor 825 is in the “forward” state and the main shift lever 50 is operated to the high speed side or the low speed side, the linear controller 813 performs the forward low speed clutch electromagnetic. The valve 632 and the forward high speed clutch electromagnetic valve 633 are controlled to switch the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539. As described above, when switching between the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539, the linear advance controller 813 performs control so that one of the forward low speed hydraulic clutch 537 and the forward high speed hydraulic clutch 539 is always connected.

  At this time, the rectilinear controller 813 controls the main transmission hydraulic pressure switching valve 624 in accordance with the rectilinear target value. In addition, the turning controller 814 receives the straight target value from the straight controller 813 to set the output (turning vehicle speed) of the turning system transmission path for the operation of the steering handle 9, so that the forward low-speed hydraulic clutch 537 and the forward high-speed hydraulic pressure are set. Without affecting the switching of the clutch 539 and without performing complicated calculations, the output of the turning system transmission path (turning vehicle speed) corresponding to the output of the straight traveling system transmission path (straight traveling vehicle speed) can be achieved.

  When the forward controller 813 controls the forward low-speed hydraulic clutch 537, the forward high-speed hydraulic clutch 539, and the reverse hydraulic clutch 541 to be disengaged by depressing the clutch pedal 37 or the like, The signal from the pickup rotation sensor 823 is transmitted to the turning controller 814. Then, the turning controller 814 sets the output (turning vehicle speed) of the turning system transmission path based on the actually measured value (signal from the straight-forward pickup rotation sensor 823). Therefore, even if the forward high speed hydraulic clutch 539 and the reverse hydraulic clutch 541 are all disconnected, 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 ( (Turning vehicle speed) can be set optimally, so that the operator can operate the vehicle without a sense of incongruity.

  When the brake pedal 35 is depressed, the rectilinear controller 813 controls each of the forward low speed hydraulic clutch 537, the forward high speed hydraulic clutch 539, and the reverse hydraulic clutch 541 in a high speed region where the traveling speed (straight forward vehicle speed) is equal to or higher than a predetermined speed. On the other hand, in the low speed region where the traveling speed (straight forward vehicle speed) is less than the predetermined speed, the forward low speed hydraulic clutch 537 or the reverse hydraulic clutch 541 is controlled in accordance with the forward and backward travel of the vehicle. At this time, the straight-ahead controller 813 and the turning controller 814 set the output (turning vehicle speed) of the turning system transmission path based on the straight-ahead actual measurement value (signal from the straight-ahead pickup rotation sensor 823). Accordingly, when the braking control by the operation of the brake pedal 35 is being executed, the output of the turning system transmission path (turning vehicle speed) is obtained even if the output of the straight traveling system transmission path (straight traveling vehicle speed) does not correspond to the straight traveling target value. Since the vehicle can be decelerated in accordance with the output (straight vehicle speed) of the straight transmission path, the operator can operate the vehicle without a sense of incongruity.

  The turning controller 814 decelerates the output (turning vehicle speed) of the turning system transmission path as the output (straight running vehicle speed) of the straight running system transmission path is reduced. When the steering handle 9 is operated, the turning controller 814 increases the output of the turning system transmission path (turning vehicle speed), and the turning controller 813 reduces the output of the straight traveling system transmission path (straight vehicle speed). Thus, the speed ratio of the left and right traveling crawlers 3 during turning is determined based on the turning angle of the steering handle 9.

  When the traveling controller 813 and the turning controller 814 execute the above-described control, as shown in FIG. 18, when the turning angle of the steering handle 9 is less than a predetermined value R1, the inner traveling crawler 3 is decelerated and the steering handle When the turning angle of 9 is the predetermined value R1, the inner traveling crawler 3 is stopped, and when the turning angle of the steering handle 9 exceeds the predetermined value R1, the inner traveling crawler 3 is reversely rotated. Thereby, according to the operation amount of the steering handle 9, the turning center and turning radius of the traveling machine body 2 can be changed. Accordingly, the traveling machine body 2 can be turned in a state close to the sense of operation of the steering handle 9, and as a result, the traveling machine body 2 can be stably driven.

  In addition, as shown in FIG. 19, the operator operates the operation monitor 55 so that an automatic deceleration is applied during turning to make a small turn (spin turn), and in the first half of the steering angle compared to the standard mode. It is possible to select “soft mode”, which is light on the cutting edge, and “humid field mode”, which is light on the latter half of the steering angle compared to the standard. Furthermore, as shown in FIG. 20, the operator can adjust the turning force at the time of turning in a plurality of stages by operating the operation monitor 55. Accordingly, the operator can select one of a plurality of modes by operating the operation monitor 55, and can also make stepwise adjustments. Therefore, an appropriate traveling characteristic (turning characteristic) suitable for the field situation or the like is possible. Can be selected easily.

  When the “standard mode” is designated, as described above, when the turning angle of the steering handle 9 exceeds the predetermined value R1, the inner traveling crawler 3 is reversely rotated, and the traveling aircraft body 2 is turned by a spin turn. When “soft mode” is designated, when the turning angle of the steering handle 9 is maximized, the inner traveling crawler 3 is stopped and the traveling vehicle body 2 is turned by a brake turn. When “wet paddy mode” is designated, the inner traveling crawler 3 does not stop even if the turning angle of the steering handle 9 is maximized, and the traveling machine body 2 is turned gently.

  The steering handle 9 is attached such that the maximum turning angle from the neutral position to the left and right is limited by an angle θ1 (for example, 250 °) that is between 180 ° and 270 °. When “standard mode” is instructed from the screen of FIG. 19 on the operation monitor 55, when the center turning force (standard value) is instructed from the screen of FIG. θ2 is equivalent to the maximum turning angle θ1 on the mechanism (for example, 245 °). When the maximum turning force (strong) is instructed from the screen of FIG. 20, the maximum turning angle θ2 of the steering handle 9 for control is smaller than the maximum turning angle θ1 on the mechanism (for example, 210 °). It becomes. When the minimum turning force (weak) is instructed from the screen of FIG. 20, the maximum turning angle θ2 of the steering handle 9 for control becomes an angle (for example, 280 °) larger than the maximum turning angle θ1 on the mechanism. .

  As described above, since the maximum turning angle θ2 for control can be switched based on the turning force instructed by the operation on the operation monitor 55, the traveling machine body 2 can be operated in accordance with the operability desired by the operator. it can. In addition, when the maximum turning force (strong) is designated, it is possible to control the operator with high responsiveness by reducing the maximum turning angle θ2 of the steering handle 9 for control. At this time, since the play in the steering of the steering handle 9 can be increased, the steering handle 9 can be turned without difficulty. On the other hand, when the maximum turning force (weak) is designated, the steering angle can be restricted by increasing the maximum turning angle θ2 of the steering handle 9 for control, so that the sudden turning of the traveling machine body 2 is restricted. The traveling machine body 2 can be driven stably.

  In addition, the structure of each part in this invention is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

2 traveling machine body 3 traveling crawler 4 rear wheel 5 diesel engine 8 control seat 13 turning mission case 17 rectilinear transmission case 500 hydraulic mechanical transmission 501 forward / reverse switching mechanism 502 creep transmission gear mechanism 503 auxiliary transmission gear mechanism 511 main transmission input Shaft 512 Main transmission output shaft 521 Hydraulic pump section 522 Hydraulic motor section 523 Pump swash plate 524 Main transmission hydraulic cylinder 526 Planetary gear mechanism 535 Travel 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 pressure switching valve 643 Forward high speed clutch hydraulic pressure switching valve 644 Reverse clutch hydraulic pressure 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 Swing hydraulic cylinder 742 Swing hydraulic pressure switching valve 813 Straight controller 814 Swing controller 821 Steering angle sensor 822 Main transmission sensor 823 Linear pick-up rotation sensor 824 Turning pick-up rotation sensor 825 Forward / reverse sensor 826 Sub-transmission sensor 827 Creep sensor 828 Brake sensor 829 Clutch sensor 831 Straight traveling calculation unit 832 Memory 833 Communication interface 841 Turning traveling calculation unit 842 Memory 843 Communication interface TA Deceleration rate table TB Turning / straight running ratio table

Claims (3)

An engine mounted on the traveling machine body, a linear transmission path having a first continuously variable transmission, and a turning transmission path having a second continuously variable transmission, an output of the linear transmission path and the turning transmission path In a work vehicle that combines the outputs of
A controller that controls the output of the straight transmission path and the output of the turning transmission path in conjunction with each other, and a steering handle that can be rotated;
Wherein the control unit causes the speed of the output of the orbiting system transmission path in accordance with the deceleration of the output of the linear system transmission route, when the steering wheel is operated, it is accelerated to an output of said turning system transmission path , by decelerating the output of the linear system transmission path, and determines the speed ratio of the left and right traveling unit during turning based on the steering angle of the steering wheel,
The control unit includes a first control unit that controls an output of the straight traveling system transmission path, and a second control unit that controls an output of the turning system transmission path,
A work vehicle characterized in that an output of the turning system transmission path is set by the second control section receiving an output of the straight traveling system transmission path set by the first control section . When either one of the brake pedal and the clutch pedal of the work vehicle is depressed, the measured value of straight traveling is transmitted from the first control unit to the second control unit. The work vehicle according to claim 1. When both the brake pedal and the clutch pedal of the work vehicle are not depressed, a target value for straight traveling is transmitted from the first control unit to the second control unit. The work vehicle according to claim 1 or 2.

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