JP4958943B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle such as a tractor used for agricultural work or a wheel loader used for civil engineering work.

  Conventionally, in general, in the tractor or wheel loader described above, an engine is installed at the front of the body frame, a transmission case is installed at the rear of the body frame, and the body is supported by front and rear wheels. In this case, the transmission case is provided with a traveling transmission gear, a differential gear, a PTO transmission gear, etc., and transmits power from the engine at the front of the aircraft to the transmission case at the rear of the aircraft, The power is transmitted to the traveling portion (wheel) of the vehicle, and similarly, the power is transmitted from the PTO transmission gear to the working portion (for example, Patent Document 1). In the tractor or wheel loader described above, when driving the left and right traveling units, the power of the engine mounted on the front of the fuselage is transmitted via a hydraulic continuously variable transmission (HST), a traveling transmission gear mechanism, a differential gear mechanism, and the like. Transmitted to the left and right wheels.

  Further, as disclosed in Patent Document 2, a technique of providing an inline hydraulic continuously variable transmission as a hydraulic continuously variable transmission is also known. The hydraulic continuously variable transmission includes a hydraulic pump unit that transmits power from an engine via an input shaft, and a hydraulic motor unit that transmits hydraulic shift output to left and right wheels via an output shaft. The shaft is concentrically arranged, the hydraulic pump part is fitted on the input shaft on one side, and the hydraulic pressure on the other side of the cylinder block, sandwiching the cylinder block that fits and rotates integrally with the input shaft. The motor part was fitted on the input shaft. Moreover, the output shaft was arrange | positioned on the opposite side to the power input part of the input shaft.

JP-A-11-334395 JP 2002-89655 A

  For example, like a transmission structure of a tractor, a hydraulic continuously variable transmission (HST) is arranged on the outer surface of the front part of the transmission case, and a traveling auxiliary transmission gear, a differential gear, a PTO transmission gear, and the like are connected to the transmission case. When installed inside, there is a problem that the mission case and the hydraulic continuously variable transmission cannot be arranged compactly. Further, for example, in a transmission structure of a tractor in which the input side of the input shaft protrudes toward the engine on the front side of the transmission case, an installation space for the continuously variable transmission of Patent Document 2 is secured inside the transmission case. However, there was a problem that the mission case had to be enlarged.

The invention according to claim 1, in the transmission case, an input shaft to which power from an engine is transmitted, a travel main transmission CVT, in a work vehicle provided with a differential gear mechanism for driving the drive output The transmission case includes a front side wall member, a rear side wall member, and a partition wall that divides the front and rear sides, and the front side wall member, the rear side wall member, and the partition wall include a front chamber and a rear chamber inside the mission case. The input shaft is extended to the rear chamber from the front of the transmission case via the front side wall member and the partition wall, and the non-transistor provided on the input shaft is provided in the rear chamber. A step transmission, the differential gear mechanism, and a transmission actuator for continuously variable transmission control attached to the rear end side of the input shaft are arranged adjacent to each other, and the rear side wall member of the transmission case is attached and detached. Especially Thus, the continuously variable transmission is configured to be able to enter and leave the interior of the rear chamber, and in a state where the continuously variable transmission is mounted inside the rear chamber, the partition wall and the rear side wall member are disposed between the partition wall and the rear wall member. The continuously variable transmission is supported.

The invention according to claim 1, in the transmission case, an input shaft to which power from an engine is transmitted, a travel main transmission CVT, in a work vehicle provided with a differential gear mechanism for driving the drive output The transmission case includes a front side wall member, a rear side wall member, and a partition wall that divides the front and rear sides, and the front side wall member, the rear side wall member, and the partition wall include a front chamber and a rear chamber inside the mission case. The input shaft is extended to the rear chamber from the front of the transmission case via the front side wall member and the partition wall, and the non-transistor provided on the input shaft is provided in the rear chamber. A step transmission, the differential gear mechanism, and a transmission actuator for continuously variable transmission control attached to the rear end side of the input shaft are arranged adjacent to each other, and the rear side wall member of the transmission case is attached and detached. Especially Thus, the continuously variable transmission is configured to be able to enter and leave the interior of the rear chamber, and in a state where the continuously variable transmission is mounted inside the rear chamber, the partition wall and the rear side wall member are disposed between the partition wall and the rear wall member. Since the continuously variable transmission is supported , for example, a traveling auxiliary transmission gear, a differential gear, a PTO transmission gear, and the like are installed inside the transmission case as in a transmission structure of a tractor. In addition, it is possible to easily secure a space for installing the continuously variable transmission in the rear chamber of the transmission case. An operation of attaching / detaching the continuously variable transmission can be performed in a state where the differential gear mechanism is incorporated.

Also, is secured installation space, such as a traveling auxiliary transmission gear or PTO transmission gear into the front chamber of the transmission case, which is the input side of the entering force axis, the manufacturing cost for example, such as the transmission case of the tractor to compact or lightweight The assembly / disassembly workability or maintenance workability of the continuously variable transmission or the shift actuator can be improved.

It is a side view of the tractor for farm work. It is a diagonally rear perspective view of a tractor. It is side surface explanatory drawing of a tractor. It is a perspective view of a tractor airframe. It is a skeleton diagram of power transmission. It is explanatory drawing of the travel transmission part of a mission case. It is explanatory drawing of the PTO transmission part of a mission case. It is explanatory drawing of the transmission without a transmission of a transmission case. It is a hydraulic circuit diagram of the continuously variable transmission of the transmission case. It is a plane view sectional explanatory view of a mission case. It is expansion explanatory drawing of FIG. It is rear view explanatory drawing of a mission case. It is plane view explanatory drawing which shows the inside of a mission case. It is side view explanatory drawing which shows the inside of a mission case. It is a perspective explanatory view showing the inside of a mission case.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, drawings when an embodiment of the present invention is applied to a farm tractor as a work vehicle will be described. 1 is a side view of the tractor, FIG. 2 is a rear perspective view thereof, FIG. 3 is an explanatory side view thereof, FIG. 4 is a perspective view of the tractor body, and FIG. 5 is a skeleton diagram of power transmission.

  As shown in FIGS. 1 to 4, the tractor 1 supports a traveling machine body 2 by a pair of left and right rear wheels 4 as well as a pair of left and right front wheels 3, and is rear-mounted by an engine 5 mounted on the front part of the traveling machine body 2. By driving the wheel 4 and the front wheel 3, the vehicle is configured to travel forward and backward. The engine 5 is covered with a bonnet 6. In addition, a cabin 7 is installed on the upper surface of the traveling machine body 2, and a steering seat 8 and a steering handle 9 that moves the front wheel 3 to the left and right by steering are installed in the cabin 7. The A step 10 on which the operator gets on and off is provided on the outside of the cabin 7, and a fuel tank 11 for supplying fuel to the engine 5 is provided on the inside of the step 10 and below the bottom of the cabin 7.

  The traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a front axle case 13, and left and right machine body frames 16 that are detachably fixed to the rear portion of the engine frame 14 with bolts 15. A mission case 17 is connected to the rear portion of the body frame 16 for transmitting the rotation of the engine 5 to the rear wheels 4 and the front wheels 3 with appropriate speed change. In this case, the rear wheel 4 is rearwardly attached to the transmission case 17 so as to protrude outward from the outer surface of the transmission case 17 and to the outer end of the rear axle case 18. It is attached via a gear case 19 that is mounted so as to extend.

  A hydraulic working machine lifting mechanism 20 for lifting and lowering a working machine (not shown) such as a tiller is detachably attached to the upper surface of the rear portion of the mission case 17. The working machine such as a tiller is connected to the rear part of the mission case 17 via a lower link 21 and a top link 22. Further, a PTO shaft 23 for the working machine such as the tiller is provided on the rear side surface of the mission case 17 so as to protrude rearward.

Further, FIGS. 5 to 7 show the mission case 17. The mission case 17 is partitioned inside and behind by a partition wall 31. A front side wall member 32 is detachably fixed to the front side of the mission case 17 with bolts. A rear side wall member 33 is detachably fixed to the rear side of the mission case 17 with bolts. The mission case 17 is formed in a box shape, and a front chamber 34 and a rear chamber 35 are formed inside the mission case 17. The front chamber 34 and the rear chamber 35 are in communication with each other so that the hydraulic oil (lubricating oil) inside these chambers moves relative to each other.

  As shown in FIG. 5, the front side wall member 32 is provided with a front wheel drive case 69 described later. In the front chamber 34, a travel auxiliary transmission gear mechanism 30 and a PTO transmission gear mechanism 96, which will be described later, are arranged. In the rear chamber 35, a hydraulic continuously variable transmission 29, which is a traveling main transmission mechanism described later, and a differential gear mechanism 58 are arranged.

  An engine output shaft 24 is provided on the rear side surface of the engine 5 so as to protrude rearward. A flywheel 25 is attached to the engine output shaft 24 so as to be directly connected. Between a main drive shaft 26 projecting rearward from the flywheel 25 and a main transmission input shaft 27 projecting forward from the front surface of the transmission case 17 via an extendable power transmission shaft 28 having a universal joint at both ends. Connect. The rotation of the engine 5 is transmitted to the main transmission input shaft 27 in the transmission case 17, and then appropriately shifted by the hydraulic continuously variable transmission 29 and the traveling auxiliary transmission gear mechanism 30, via the differential gear mechanism 58. Thus, the driving force is transmitted to the rear wheel 4. Further, the rotation of the engine 5 that has been appropriately shifted by the traveling auxiliary transmission gear mechanism 30 is transmitted to the front wheels 3 via the front wheel drive case 69 and the differential gear mechanism 86 of the front axle case 13. Become.

  Next, FIG. 8 and FIG. 9 show an inline hydraulic continuously variable transmission 29 in which a main transmission output shaft 36 is concentrically arranged on the main transmission input shaft 27. A hydraulic continuously variable transmission 29 is installed in the rear chamber 35 via a main transmission input shaft 27. The rear end side of the main transmission input shaft 27 extends to the rear side wall member 33. The rear end side of the main transmission input shaft 27 opposite to the input side (front end side) of the main transmission input shaft 27 is rotatably supported by the rear side wall member 33 by a ball bearing 504.

  A cylindrical main transmission output shaft 36 is fitted on the front side of the hydraulic continuously variable transmission 29, that is, on the input side of the main transmission input shaft 27. A main transmission output gear 37 for taking out the main transmission output from the hydraulic continuously variable transmission 29 is provided on the main transmission output shaft 36. The middle of the main transmission output shaft 36 is penetrated by the partition wall 31, and the front end and the rear end protrude into the front chamber 34 and the rear chamber 35, respectively. The middle of the main transmission output shaft 36 is rotatably supported on the partition wall 31 by two sets of ball bearings 502. A main transmission output gear 37 is provided at the front end portion of the main transmission output shaft 36. The input side of the main transmission input shaft 27 protrudes forward from the front end of the main transmission output shaft 36 such that the input side of the main transmission input shaft 27 projects forward from the front end of the main transmission output shaft 36 via the roller bearing 503. (See FIG. 9).

  As will be described below, the hydraulic continuously variable transmission 29 includes a variable displacement type shifting hydraulic pump unit 500 and a constant displacement type shifting hydraulic pressure that operates with high-pressure hydraulic fluid discharged from the hydraulic pump unit 500. A motor unit 501.

  A cylinder block 505 for the hydraulic pump unit 500 and the hydraulic motor unit 501 is fitted on the main transmission input shaft 27 substantially in the middle between the partition wall 31 and the rear side wall member 33. The main transmission input shaft 27 and the cylinder block 505 are connected by a spline 525. The hydraulic pump unit 500 is disposed on one side of the main transmission input shaft 27 opposite to the input side with the cylinder block 505 interposed therebetween. A hydraulic motor unit 501 is disposed on the other side of the cylinder block 505 that is the input side of the main transmission input shaft 27.

  The hydraulic pump unit 500 is arranged in a first holder 510 that is fixed to the transmission case 17 facing the side surface of the cylinder block 505 and a first holder 510 that can change an inclination angle with respect to the axis of the main transmission input shaft 27. A pump swash plate 509, a shoe 508 slidably provided on the pump swash plate 509, a pump plunger 506 connected to the shoe 508 with a spherical universal joint, and a pump plunger 506 disposed in a cylinder block 505 so as to be freely accessible. And a first plunger hole 507 is provided. One end of the pump plunger 506 protrudes from the side surface of the cylinder block 505 toward the pump swash plate 509 (right side in FIG. 8). The hydraulic pump unit 500 includes a cylinder block 505, a pump plunger 506, a shoe 508, a pump swash plate 509, and a first holder 510.

  A sleeve 511 fitted to the main transmission input shaft 27, a roller bearing 512, and radial and thrust load roller bearings 513 are interposed between the main transmission input shaft 27 and the first holder 510. A nut 514 is provided behind the main transmission input shaft 27 to prevent the roller bearing 513 from coming out.

  The cylinder block 505 is provided with the same number of first spool valves 536 as the pump plungers 506. In addition, a first radial bearing 537 is disposed in the first holder 510. The first radial bearing 537 is provided in the first holder 510 so as to be inclined at a constant inclination angle with respect to the axis of the main transmission input shaft 27. In FIG. 8, the position rotated about 90 degrees with respect to the pump swash plate 509 (the front side of the drawing of FIG. 8) is separated from the side surface of the cylinder block 505 by about 180 degrees (the back side of the drawing of FIG. 8). The first radial bearing 537 is inclined and supported such that the first radial bearing 537 is close to the side surface of the cylinder block 505.

  On the other hand, the hydraulic motor unit 501 includes a second holder 519 arranged to face the side surface of the cylinder block 505, and a second holder 519 so as to maintain a constant inclination angle with respect to the axis of the main transmission input shaft 27. A motor swash plate 518 to be fixed, a shoe 517 slidably provided on the motor swash plate 518, a motor plunger 515 connected to the shoe 517 with a spherical universal joint, and the motor plunger 515 are disposed so as to be able to enter and leave the cylinder block 505. Second plunger hole 516 is provided. One end of the motor plunger 515 protrudes from the side surface of the cylinder block 505 in the direction of the motor swash plate 518 (left side in FIG. 8). The hydraulic motor unit 501 includes a cylinder block 505, a motor plunger 515, a shoe 517, a motor swash plate 518, and a second holder 519.

  A joint member 526 is fixed to the second holder 519 with a bolt 527. The output shaft 36 and the joint member 525 are connected by a spline 528.

  Between the main transmission input shaft 27 and the second holder 519, radial load roller bearings 520 and 521, a sleeve 522 fitted to the main transmission input shaft 27, a radial and thrust load roller bearing 523, Intervenes. A nut 524 is provided to prevent the roller bearing 523 from coming out of the main transmission input shaft 27.

  The cylinder block 505 is provided with the same number of second spool valves 540 as the motor plungers 515. In addition, a second radial bearing 541 is disposed in the second holder 519. The second radial bearing 541 is provided in the second holder 519 so as to be inclined at a constant inclination angle with respect to the axis of the main transmission input shaft 27. In FIG. 8, the cylinder block 505 is on the opposite side (back side in FIG. 8) about 180 degrees so that the position rotated about 90 degrees with respect to the motor swash plate 518 (front side in FIG. 8) is close to the side surface of the cylinder block 505. The second radial bearing 541 is configured to be tilted and supported so as to be separated from the side surface of the first radial bearing.

  The pump plungers 506 and the same number of motor plungers 515 as the pump plungers 506 are alternately arranged on the same circumference of the rotation center of the cylinder block 505.

  Further, a ring groove-shaped first oil chamber 530 and a ring groove-shaped second oil chamber 531 are formed in the shaft hole of the cylinder block 505 into which the main transmission input shaft 27 is inserted. The cylinder block 505 is formed with a first valve hole 532 and a second valve hole 533 that are arranged at substantially equal intervals on the same circumference of the rotation center. The first valve hole 532 and the second valve hole 533 communicate with the first oil chamber 530 and the second oil chamber 531, respectively. The first plunger hole 507 communicates with the first valve hole 532 via the first oil passage 534, and the second plunger hole 516 communicates with the second valve hole 533 via the second oil chamber 531.

  A first spool valve 536 is inserted into the first valve hole 532. The first spool valves 536 are arranged at substantially equal intervals on the same circumference of the rotation center of the cylinder block 505. The tip of the first spool valve 536 protrudes in the direction of the first holder 510 from the first valve hole 532 with the back pressure spring force, and the tip of the first spool valve 536 abuts the side surface of the outer ring 538 of the first radial bearing 537. Touched. Then, the first spool valve 536 reciprocates once in one rotation of the cylinder block 505, and the first plunger hole 507 is connected to the first oil chamber 530 or the second oil via the first valve hole 532 and the first oil passage 534. The chamber 2531 is configured to communicate with each other alternately.

  A second spool valve 540 is inserted into the second valve hole 533. The second spool valves 540 are arranged at substantially equal intervals on the same circumference of the rotation center of the cylinder block 505. The tip of the second spool valve 540 protrudes in the direction of the second holder 519 from the second valve hole 533 due to the back pressure spring force, and the tip of the second spool valve 540 contacts the side surface of the outer ring 542 of the second radial bearing 541. Touched. Then, the second spool valve 540 reciprocates once by one rotation of the cylinder block 505, and the second plunger hole 516 passes through the second valve hole 533 and the second oil passage 535, and passes through the first oil chamber 530 or the second oil. The chamber 2531 is configured to communicate with each other alternately.

  Further, a hydraulic oil supply oil passage 543 is formed in the central portion of the main transmission input shaft 27 in the axial direction. The supply oil passage 543 is opened at the rear end face of the main transmission input shaft 27 and communicates with the discharge port of the traveling hydraulic pump 95 described above. Further, the first charge valve 544 for supplying hydraulic oil in the hydraulic oil supply oil passage 543 to the first oil chamber 530 and the second charge valve 545 for supplying hydraulic oil in the hydraulic oil supply oil passage 543 to the second oil chamber 531. And are provided.

  And with respect to the hydraulic closed circuit formed between the first and second plunger holes 507 and 516 and the first and second oil chambers 530 and 531, the first and second charge valves 544 and 545 are passed through, The hydraulic oil is supplied from the hydraulic oil supply oil passage 543. It should be noted that hydraulic oil is supplied from the hydraulic oil supply oil passage 543 to the rotating portions of the hydraulic pump unit 500 and the motor unit 501 as lubricating oil via check valves.

  Further, the pump swash plate 509 is disposed on the outer periphery of the small diameter portion of the first holder 510 via an inclination angle adjustment fulcrum 555 (see FIG. 9). The pump swash plate 509 is provided such that its inclination angle is adjustable with respect to the axis of the main transmission input shaft 27. A main transmission hydraulic cylinder 556 for main transmission, which is a transmission actuator for changing the inclination angle of the pump swash plate 509 with respect to the axis of the main transmission input shaft 27, is provided (see FIG. 9). The first holder 510 is connected to the non-rotating portion of the transmission case 17 via a connecting means (not shown) so that the pump swash plate 509 does not rotate with respect to the main transmission input shaft 27.

  The main transmission operation of the inline hydraulic continuously variable transmission 29 will be described below. The hydraulic cylinder 556 is controlled by a main transmission lever or the like, and the inclination angle of the pump swash plate 509 is changed with respect to the axis line of the main transmission input shaft 27.

  First, even if the cylinder block 505 is rotated when the tilt angle of the pump swash plate 509 is kept substantially zero so that the pump swash plate 509 is substantially orthogonal to the axis of the main transmission input shaft 27, the first plunger hole The pump plunger 506 is supported in a substantially constant posture at 507 so that the pump plunger 506 does not move forward and backward, and the hydraulic oil in the first plunger hole 507 is not discharged from the first oil passage 534 toward the first valve hole 532 in the discharge stroke of the pump plunger 506. The hydraulic oil is not supplied from the first plunger hole 507 to the second plunger hole 516, and the motor plunger 515 does not advance. Further, since the hydraulic oil is not drawn into the first plunger hole 507 even during the suction stroke of the pump plunger 506, the hydraulic oil is not discharged from the second plunger hole 516 into the first plunger hole 507, and the motor plunger 515 does not retract.

  That is, when the tilt angle of the pump swash plate 509 is substantially zero, the transmission motor 501 is not driven by the transmission pump unit 500. Therefore, the motor swash plate 518 is fixed to the cylinder block 505 via the motor plunger 515, and the cylinder block 505 and the motor swash plate 518 rotate at the same rotational speed in the same direction. The main transmission output shaft 36 is rotated at substantially the same rotational speed, and the rotational speed of the main transmission input shaft 27 is transmitted to the main transmission output gear 37 without being changed.

  Next, when the pump swash plate 509 is tilted with respect to the axis of the main transmission input shaft 27, the rotation of the cylinder block 505 that rotates integrally with the main transmission input shaft 27 causes the outer ring 538 of the first radial bearing 537 to be The 1-spool valve 536 slides back and forth, and the first oil chamber 530 or the second oil chamber 531 communicates with the first plunger hole 507 alternately every half rotation of the cylinder block 505. Further, the second spool valve 540 slides back and forth at the outer ring 542 of the second radial bearing 541, and the first oil chamber 530 or the second oil chamber 531 alternates with the second plunger hole 516 every half rotation of the cylinder block 505. Communicated with A closed hydraulic circuit is formed between the first plunger hole 507 and the second plunger hole 516, and hydraulic oil is pumped from the first plunger hole 507 to the second plunger hole 516 in the discharge stroke of the pump plunger 506, The hydraulic fluid is returned from the second plunger hole 516 to the first plunger hole 507 during the suction stroke of the pump plunger 506, and the operation of the axial piston pump and the motor is performed.

  When the pump swash plate 509 is inclined in one direction (positive inclination angle) with respect to the axis line of the main transmission input shaft 27, the motor swash plate 518 is rotated in the same direction as the cylinder block 505, and the transmission motor 501 is rotated. The main transmission output shaft 36 is rotated at a higher rotational speed than the main transmission input shaft 27, and the rotational speed of the main transmission input shaft 27 is increased and transmitted to the main transmission output gear 37. . That is, the rotation speed of the transmission motor 501 driven by the transmission pump 500 is added to the rotation speed of the main transmission input shaft 27 and transmitted to the main transmission output gear 37. Therefore, the shift output (travel speed) from the main shift output gear 37 is proportional to the inclination (positive inclination angle) of the pump swash plate 509 within the range of the rotation speed higher than the rotation speed of the main transmission input shaft 27. As a result, the maximum traveling speed is reached at the maximum inclination (positive inclination angle) of the pump swash plate 509.

  Further, when the pump swash plate 509 is inclined in the other direction (negative inclination angle) with respect to the axis of the main transmission input shaft 27, the motor swash plate 518 is rotated in the direction opposite to the cylinder block 505, and the transmission motor The main transmission output shaft 36 is rotated at a lower rotational speed than the main transmission input shaft 27, and the rotational speed of the main transmission input shaft 27 is decelerated and transmitted to the main transmission output gear 37.

  That is, the rotation speed of the transmission motor 501 driven by the transmission pump 500 is subtracted from the rotation speed of the main transmission input shaft 27 and transmitted to the main transmission output gear 37. Therefore, the shift output (travel speed) from the main shift output gear 37 is proportional to the inclination (negative inclination angle) of the pump swash plate 509 within the range of the rotation speed lower than the rotation speed of the main transmission input shaft 27. As a result, the minimum traveling speed is reached at the maximum inclination (negative inclination angle) of the pump swash plate 509.

  Next, as shown in FIGS. 5 and 6, the front chamber 34 of the mission case 17 has a forward gear 41 and a reverse gear 43 for switching between forward and reverse, and a traveling auxiliary gear for switching between low speed and high speed. A transmission gear mechanism 30 is disposed.

  A description will be given of switching between forward and reverse movements through the forward gear 41 and the reverse gear 43. As shown in FIG. 6, a travel counter shaft 38 and a reverse rotation shaft 39 are disposed in the front chamber 34 where the main transmission output gear 37 is disposed. A forward gear 41 connected by a forward hydraulic clutch 40 and a reverse gear 43 connected by a reverse hydraulic clutch 42 are fitted on the travel counter shaft 38. The forward gear 41 is meshed with the main transmission output gear 37. The main transmission output gear 37 is meshed with a reverse gear 44 provided on the reverse shaft 39. The reverse gear 43 is meshed with a reverse output gear 45 provided on the reverse shaft 39.

  Then, by a forward operation of the main transmission lever (not shown), the clutch cylinder 47 is operated by the forward hydraulic solenoid valve 46 and the forward hydraulic clutch 40 is continued, and the main transmission output gear 37 and the travel counter shaft 38 are advanced. It connects so that it may be connected with the gear 41 (refer FIG. 5, FIG. 6).

  On the other hand, by a reverse operation of the main speed change lever (not shown), the reverse hydraulic solenoid valve 48 operates the clutch cylinder 49 to continue the reverse hydraulic clutch 42, and the main speed change output gear 37 and the travel counter shaft 38 move backward. It connects so that it may be connected with the gear 43 (refer FIG. 5, FIG. 6).

  When the main transmission lever (not shown) is supported at the neutral position, both the forward and reverse hydraulic clutches 40 and 42 are both disconnected and output to the front wheel 3 and the rear wheel 4. The main drive output gear 37 is configured so that the travel driving force is substantially zero (main clutch disengaged).

  Next, switching between the low speed and the high speed performed through the traveling auxiliary transmission gear mechanism 30 will be described. As shown in FIGS. 5 and 6, a traveling auxiliary transmission gear mechanism 30 and an auxiliary transmission shaft 50 are disposed in the front chamber 34 of the transmission case 17. Between the travel counter shaft 38 and the auxiliary transmission shaft 50, low-speed gears 51 and 52 for auxiliary transmission and high-speed gears 53 and 54 for auxiliary transmission are provided. Further, a low speed clutch 56 and a high speed clutch 57 which are continued or disconnected by the auxiliary transmission hydraulic cylinder 55 are provided. The low speed clutch 56 or the high speed clutch 57 is continued in the auxiliary speed change hydraulic cylinder 55 by operating the auxiliary speed change lever (not shown) or detecting the rotational speed of the engine 5. The high-speed gear 54 is connected, and the driving force is output from the auxiliary transmission shaft 50 to the front wheels 3 and the rear wheels 4.

  The rear end of the auxiliary transmission shaft 50 extends through the partition wall 31 and extends into the rear chamber 35 of the transmission case 17 (see FIG. 5). A pinion 59 is provided at the rear end portion of the auxiliary transmission shaft 50. In addition, a differential gear mechanism 58 that transmits traveling driving force to the left and right rear wheels 4 is disposed in the rear chamber 35. The differential gear mechanism 58 includes a ring gear 60 that meshes with a pinion 59 at the rear end of the auxiliary transmission shaft 50, a differential gear case 61 provided on the ring gear 60, and left and right differential output shafts 62. The differential output shaft 62 is connected to the rear axle 64 by a final gear 63 or the like, and is configured to drive the rear wheel 4 provided on the rear axle 64.

  Further, a brake 65 is installed on the differential output shaft 62, and the brake 65 is configured to be braked by operating the left and right brake pedals 66. On the other hand, when the steering angle of the handle 9 is detected, the brake cylinder 68 is actuated by the autobrake solenoid valve 67, the brake 65 is automatically braked, and a turning travel such as a U-turn is performed. Yes.

  Next, as shown in FIGS. 5 and 6, switching between the two-wheel drive and the four-wheel drive of the front and rear wheels 3, 4 will be described.

  A front wheel drive case 69 is provided on the front side wall member 32 of the mission case 17. The front wheel drive case 69 is provided with a front wheel input shaft 72 and a front wheel output shaft 73. The front wheel input shaft 72 is connected to the auxiliary transmission shaft 50 by gears 70 and 71. The front wheel output shaft 73 is fitted with a four-wheel drive gear 75 connected by a four-wheel drive hydraulic clutch 74 and a double speed gear 77 connected by a double speed hydraulic clutch 76. The four-wheel drive gear 75 and the double speed gear 77 are connected to the front wheel input shaft 72 by gears 78 and 79, respectively.

  Then, by the four-wheel drive operation of the switching lever (not shown) of the two-wheel drive and the four-wheel drive, the clutch cylinder 81 is operated by the four-wheel hydraulic solenoid valve 80 and the four-wheel drive hydraulic clutch 74 is continued, and the front wheel input shaft 72 and the front wheel output shaft 73 are connected by a four-wheel drive gear 75, and the front wheel 3 is driven together with the rear wheel 4.

  Next, as shown in FIGS. 5 and 6, switching of the double speed drive of the front wheels 3 will be described. Upon detection of the U-turn (direction change at the headland in the field) operation of the steering handle 9, the clutch cylinder 83 is operated by the double speed hydraulic solenoid valve 82, and the double speed hydraulic clutch 76 is continued. And the front wheel output shaft 73 are connected by a double speed gear 77 so that the front wheel 3 is driven at a speed approximately twice as high as that when the front wheel 3 is driven by the four-wheel drive gear 75. Configure.

  As shown in FIG. 5, the front wheel 3 is powered between a front wheel input shaft 84 projecting rearward from the front axle case 13 and a front wheel output shaft 73 projecting forward from the front surface of the transmission case 17. Are connected via a front wheel drive shaft 85 that transmits In addition, a differential gear mechanism 86 that transmits traveling driving force to the left and right front wheels 3 is disposed inside the front axle case 13.

  The differential gear mechanism 86 includes a ring gear 88 that meshes with a pinion 87 at the front end of the front wheel input shaft 84, a differential gear case 89 provided on the ring gear 88, and left and right differential output shafts 90. A front axle 92 is connected to the differential output shaft 90 by a final gear 91 or the like, and a front wheel 3 provided on the front axle 92 is driven. Further, on the outer surface of the front axle case 13, a hydraulic cylinder 93 for power steering that changes the traveling direction of the front wheel to the right and left by the steering operation of the steering handle 9 is disposed.

  As shown in FIGS. 5 and 7, on the front side of the front side wall member 32 of the mission case 17, a working machine hydraulic pump 94 for supplying hydraulic fluid to the working machine lifting mechanism 20, a mission case And a traveling hydraulic pump 95 for supplying hydraulic oil to each of the 17 transmission parts and the hydraulic cylinder 93 for power steering. A transmission case 17 is used in combination as an oil tank so that hydraulic oil in the case 17 is supplied to the hydraulic pumps 94 and 95.

  Next, as shown in FIGS. 5 and 7, switching of the driving speed of the PTO shaft 23 (four forward rotations and one reverse rotation) will be described.

  As shown in FIG. 7, a PTO transmission gear mechanism 96 that transmits power from the engine 5 to the PTO shaft 23 and a power from the engine 5 are transmitted to the hydraulic pumps 94 and 95 in the front chamber 34 of the mission case 17. A pump drive shaft 97 is provided. The PTO transmission gear mechanism 96 includes a PTO counter shaft 98 and a PTO transmission output shaft 99. The PTO input gear 101 connected by the PTO hydraulic clutch 100 is fitted on the PTO counter shaft 98. An input side gear 102 provided on the main transmission input shaft 27 and an output side gear 103 of the pump drive shaft 97 are engaged with the PTO input gear 101, and the pump drive shaft 97 is connected to the main transmission input shaft 27. .

  Then, by continuing the operation of the PTO clutch lever (not shown), the clutch cylinder 105 is operated by the PTO clutch hydraulic solenoid valve 104 (see FIG. 5), and the PTO hydraulic clutch 100 is continued. The PTO counter shaft 98 is connected to the PTO input gear 101.

  Further, a first speed gear 106, a second speed gear 107, a third speed gear 108, a fourth speed gear 109, and a reverse gear 110 are fitted on the PTO speed change output shaft 99 for PTO output (FIG. 5, see FIG.

  A shift shifter 111 is pivotally supported on the PTO shift output shaft 99 by a spline. The gears 106, 107, 108, 109, 110 are configured to be alternatively connected to the PTO shift output shaft 99 by a shift shifter 111. A shift arm 112 connected to a PTO shift lever (not shown) is engaged with the shift shifter 111. Then, a shift operation of the PTO shift lever (not shown) causes the shift shifter 111 to move linearly along the axis of the PTO shift output shaft 99 by the shift arm 112, and each gear 106, 107, 108, 109, Any one of 110 is selected and connected to the PTO shift output shaft 99 (see FIGS. 5 and 7). Therefore, the first, second, third, fourth, and reverse PTO shift outputs are transmitted from the PTO shift output shaft 99 to the PTO shaft 23 via the gears 113 and 114.

  In FIG. 6, a rotation detection gear 115 provided on the reverse rotation shaft 39 and a pickup 116 for detecting the rotation of the main transmission output gear 37 are installed facing each other, and the output rotation speed of the main transmission mechanism 29 is set by the pickup 116. Configure to detect. Further, a pickup 117 for detecting the rotation of the gear 78 of the front wheel input shaft 72 is installed, and the traveling speed (vehicle speed) is detected by the pickup 117 based on the rotation of the front wheel input shaft 72 and the auxiliary transmission shaft 50. Configure.

  As is apparent from the above, a transmission case 17 that transmits power from the engine 5 is provided, and an input shaft 27 that transmits power from the engine 5 and an output shaft 36 that transmits hydraulic shift output to the left and right wheels 3 and 4. The inline type continuously variable transmission 29 arranged on the same axis is disposed in the transmission case 17, and the hydraulic pump unit 500 is disposed on one side with the cylinder block 505 constituting the continuously variable transmission 29 interposed therebetween. In a working vehicle in which a hydraulic motor unit 501 is arranged on each side and the output shaft 36 is fitted on the input shaft 27 to form a double shaft configuration, hydraulic pressure is provided between the input side of the input shaft 27 and the cylinder block 505. The motor unit 501 is disposed, and the input side of the input shaft 27 and the output side of the output shaft 36 are disposed on the same side. Therefore, for example, even if the traveling auxiliary transmission gear, the differential gear, the PTO transmission gear, and the like are installed inside the transmission case 17 as in the transmission structure of the tractor 1, The installation space for the transmission 29 can be easily secured. An installation space such as a PTO transmission gear or a traveling auxiliary transmission gear is secured in the front portion of the transmission case 17 on the input side of the input shaft 27. For example, the transmission case 17 of the tractor 1 can be reduced in size or weight, and the manufacturing cost can be reduced. Can be reduced.

  An output shaft 36 is rotatably supported by a bearing 502 inside the transmission case 17, and a front side of a swash plate 518 of a hydraulic motor unit 501 provided in the continuously variable transmission 29 and a rear side of the output shaft 36. Are connected by a spline 528 so as to be separable. Therefore, the operation of attaching or removing the continuously variable transmission 29 can be performed in a state where the hydraulic pump unit 500 and the hydraulic motor unit 501 are respectively disposed on both sides of the cylinder block 505 and supported by the input shaft 27. The output shaft 36 can be pivotally supported on the transmission case 17 by a bearing structure independent of the continuously variable transmission 29, and the transmission case 36 is continuously variable with respect to the transmission case 17 with the output shaft 36 pivotally supported on the transmission case 17. The machine 29 can be attached and detached, and the continuously variable transmission 29 can be easily attached or removed.

  Further, the continuously variable transmission 29 and a differential gear mechanism 58 for transmitting power to the left and right wheels 4 are provided in the transmission case 17. Therefore, the continuously variable transmission 29 can be arranged in a compact manner by using the excess space inside the transmission case 17 provided with the differential gear mechanism 58. For example, the transmission case 17 of the tractor 1 can be reduced in size or weight, and the manufacturing cost can be reduced. Can be reduced.

  Further, the inside of the transmission case 17 is divided into front and rear, the transmission gear mechanisms 30 and 96 are arranged on the front side inside the transmission case 17, and the continuously variable transmission 29 and the differential gear mechanism are arranged on the rear side inside the transmission case 17. 58 is disposed. Therefore, the continuously variable transmission 29 can be installed in a compact manner by utilizing the rear space of the mission case 17 in which the differential gear mechanism 58 is provided. Moreover, the transmission gear mechanisms 30 and 96 such as the PTO transmission gear or the traveling auxiliary transmission gear arranged at the front part of the transmission case 17 and the continuously variable transmission 29 and the differential gear mechanism 58 arranged at the rear part of the transmission case 17 are used. For example, the inside of the box-shaped transmission case 17 can be used effectively, and the continuously variable transmission 29 can be arranged in a compact manner. For example, the transmission case 17 of the tractor 1 can be reduced in size or weight, and the manufacturing cost can be reduced.

  10 is a cross-sectional view in plan view of the mission case 17, FIG. 11 is an enlarged view in cross-section in plan view of the rear portion of the mission case 17, and FIG.

  As shown in FIGS. 6, 8, 10 to 12, the continuously variable transmission 29 and the differential gear mechanism 58 are provided in the rear chamber 35 of the transmission case 17. The differential gear mechanism 58 includes a differential lock mechanism 560 that stops the differential operation (the right and left differential output shafts 62 are always driven at a constant speed). A differential lock mechanism 560 is disposed on one side of the differential gear case 61, and the ring gear 60 is fixed to the other side of the differential gear case 61 with bolts. The end of the differential gear case 61 on the same side as the ring gear 60 installation side is supported by the bearing holder 559 by the bearing bearing 558. The bearing holder 559 is fixed to the mission case 17 with a bolt, and is configured such that a large-diameter bearing bearing 558 having a large load resistance is used.

  As shown in FIG. 11, a differential lock mechanism 560 is provided on one side and a ring gear 60 is provided on the other side with the differential gear case 61 interposed therebetween. The continuously variable transmission 29 is disposed on the same side as the side where the differential lock mechanism 560 is installed.

  The differential lock mechanism 560 includes a lock pin 561 that is detachably provided in the differential gear case 61, a slider 562 to which one end of the lock pin 561 is fixed, a lock arm 563 that the slider 562 engages, and a lock arm 563 that slides. And an operation shaft 564 that is movably supported. Normally, the lock pin 561 is supported so as to be separated from the differential gear 565 in the differential gear case 61 so that a differential output is transmitted from the differential gear case 61 to the left and right differential output shafts 62.

  On the other hand, when the lock pin 651 is engaged with the differential gear 565 by operating a differential lock lever (or pedal) (not shown), the differential gear 565 is fixed to the differential gear case 61, and the differential function of the differential gear 565 is changed. It stops so that the left and right differential output shafts 62 are driven at a constant speed.

  As shown in FIG. 12, a predetermined amount or more of hydraulic oil 566 is placed inside the mission case 17. The differential output shaft 62 is disposed at substantially the same height as the oil level (upper surface) of the hydraulic oil 566. The continuously variable transmission 29 is disposed at a position higher than the axis of the differential output shaft 62. Therefore, the continuously variable transmission 29 is disposed above the oil level of the hydraulic oil 566 inside the mission case 17.

  Next, assembly and removal of the continuously variable transmission 29 from the transmission case 17 will be described. When the continuously variable transmission 29 is incorporated into the transmission case 17, the continuously variable transmission 29 is attached to the main transmission input shaft 27, and the rear end of the main transmission input shaft 27 is supported by the rear side wall member 33 by the bearing 504. In this state, these are inserted into the transmission case 17 from behind, the main transmission input shaft 27 passes through the inner hole of the main transmission output shaft 36, and the joint member 525 is connected to the main transmission output shaft 36 by the spline 528. The continuously variable transmission 29 is assembled in the transmission case 17.

  On the other hand, when the continuously variable transmission 29 is removed from the main transmission input shaft 27, the continuously variable transmission 29 is attached to the main transmission input shaft 27, and the rear end of the main transmission input shaft 27 is attached to the rear side wall member 33 with a bearing 504. , The rear side wall member 33 is removed from the transmission case 17, and the joint member 525 connected to the main transmission output shaft 36 by the spline 528 is detached from the main transmission output shaft 36, and the partition wall 31 is connected to the main wall 31. With the speed change output shaft 36 pivotally supported by the bearing 502, the main speed change input shaft 27 and the continuously variable transmission 29 are removed together with the rear side wall member 33, and these are taken out behind the transmission case 17, Maintenance work for the continuously variable transmission 29 is performed.

  As is clear from the above, in a work vehicle in which the main transmission input shaft 27 to which power from the engine 5 is transmitted and the traveling main transmission continuously variable transmission 29 are provided in the mission case 17, the transmission case 17 A side wall member 32, a rear side wall member 33, and a partition wall 31 that divides the front and rear sides are provided, and the front side wall member 32, the rear side wall member 33, and the partition wall 31 provide a front chamber 34 and a rear chamber 35 inside the mission case 17. The main transmission input shaft 27 is extended to the rear chamber 35 from the front of the transmission case 17 via the front side wall member 32 and the partition wall 31, and continuously variable on the main transmission input shaft 27 inside the rear chamber 35. The machine 29 is arranged. Therefore, for example, even when the traveling auxiliary transmission gear, the differential gear, the PTO transmission gear, and the like are installed inside the transmission case 17 as in the transmission structure of the tractor, the rear case 35 is continuously set in the transmission case 17. The installation space for the transmission 29 can be easily secured. The operation of attaching and detaching the continuously variable transmission can be performed with the differential gear mechanism 58 incorporated.

  Further, the output shaft of the continuously variable transmission 29 is rotatably supported by the partition wall 31, and the traveling auxiliary transmission gear mechanism 30 to which the transmission output is transmitted from the main transmission output shaft 36 and the main transmission input shaft 27 to the engine 5. The PTO transmission gear mechanism 96 to which the rotational output of the vehicle is transmitted is disposed in the front chamber 34, and the differential gear mechanism 58 for travel drive output is disposed in the rear chamber 35. A continuously variable transmission 29 is disposed adjacent to the differential gear mechanism 58 for output, and a main transmission hydraulic cylinder 556 as a transmission actuator for controlling the continuously variable transmission 29 is disposed on the rear end side of the main transmission input shaft 27. Since the continuously variable transmission 29 is supported between the rear side wall member 33 and the partition wall 31, the front chamber 34 of the transmission case 17 on the input side of the main transmission input shaft 27 is provided. Traveling auxiliary transmission gear or PT Installation space for the transmission gear and the like is secured. For example, the transmission case 17 of the tractor can be reduced in size or weight to reduce the manufacturing cost. Or maintenance workability can be improved.

3 Front wheel 4 Rear wheel 5 Engine 17 Mission case 27 Main transmission input shaft 29 Continuously variable transmission 31 Partition wall 32 Front side wall member 33 Rear side wall member 34 Front chamber 35 Rear chamber 36 Main transmission output shaft 58 Differential gear mechanism 500 Hydraulic pressure Pump unit 501 Hydraulic motor unit 560 Differential lock mechanism

Claims (1)

In the transmission case, an input shaft to which power from an engine is transmitted, a travel main transmission CVT, in a work vehicle provided with a differential gear mechanism for driving the drive output,
The mission case includes a front wall member, a rear wall member, and a partition wall that divides the front and rear, and the front wall member, the rear wall member, and the partition wall include a front chamber and a rear chamber inside the mission case. Form the
Extending the input shaft to the rear chamber from the front of the mission case via the front side wall member and the partition wall,
Adjacent to the rear chamber are the continuously variable transmission provided on the input shaft, the differential gear mechanism, and a transmission actuator for controlling the continuously variable transmission attached to the rear end side of the input shaft. And then place
By attaching and detaching the rear side wall member of the transmission case, the continuously variable transmission can be put in and out of the rear chamber, and in the state where the continuously variable transmission is mounted in the rear chamber, The continuously variable transmission is supported between the partition wall and the rear wall member.
Work vehicle.

Images