JP5030155B2 - Work vehicle - Google Patents

Description

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

  Conventionally, in a tractor as a work vehicle, a transmission speed change mechanism for driving output, a differential gear mechanism for transmitting power to left and right wheels, and a PTO shaft output for a transmission case to which power is transmitted from an engine. And a PTO transmission mechanism. The PTO shaft is for transmitting engine power to the working unit, and protrudes outward from the mission case. The power input from the engine into the transmission case is transmitted to the left and right wheels via the traveling speed change mechanism and the differential gear mechanism, and is also transmitted to the PTO shaft via the PTO speed change mechanism.

Some tractors of this type include a reverse PTO mechanism in a mission case (see, for example, Patent Document 1). The reverse PTO mechanism is for independently rotating the output of the PTO shaft independently of the driving direction (rotation direction) of the travel transmission mechanism. In this case, since the PTO shaft can be driven in reverse rotation independently by the action of the reverse PTO mechanism, for example, when the stone is bitten into the working part, the bite that has been bitten without having to reverse the traveling machine body There is an advantage that can be removed.
JP 2002-127776 A

  However, in the conventional configuration, the PTO shaft is provided at the rear portion of the transmission case, whereas the PTO transmission mechanism and the reverse PTO mechanism are installed together with the traveling transmission mechanism on the front side of the transmission case (to the PTO shaft). Therefore, the number of parts increases depending on the combination of the traveling transmission mechanism and the PTO-related mechanism (PTO transmission mechanism and reverse PTO mechanism). As a result, the structure of the power transmission path on the upstream side of the PTO clutch becomes complicated, resulting in a large transmission case and an increase in cost. The first technical problem in the present invention is to realize a configuration corresponding to independent reverse drive of the PTO shaft without complicating the structure of the power transmission path on the upstream side of the PTO clutch.

  By the way, there is rarely an opportunity to actually perform an operation to drive the PTO axis in the reverse direction. For this reason, it is considered that such an operation should be designed with emphasis on prevention of erroneous operation rather than improvement in operability. In this regard, when adopting a configuration in which the forward rotation operation and the reverse drive operation of the PTO axis can be executed by one operation means, the operator erroneously operates the one operation means and reverses the PTO axis when unnecessary. The possibility of driving cannot be denied. The second technical problem in the present invention is to suppress malfunction of the PTO shaft due to erroneous operation by the operator.

In order to achieve this technical problem, the invention of claim 1 is directed to a transmission case for transmitting power from an engine mounted on a traveling machine body, a PTO shaft for transmitting the power of the engine to a working part, and the PTO shaft. And a PTO transmission mechanism for changing the output of the PTO shaft, and in the vicinity of the PTO shaft (18) in the transmission case (15), A reverse switching mechanism (51) capable of transmitting power branched from the downstream side of the PTO clutch (39) is provided. When the PTO speed change mechanism (40) is in its neutral state, the reverse switching mechanism ( 51) a work vehicle that is reversed drivable configuration at power via the low-speed gear constituting the PTO transmission mechanism (40) (44), high-speed gear (45) and a neutral and reverse (46) and a reverse clutch (52) for interrupting transmission of the branch power to the reverse switching mechanism (51) are disposed on the PTO shaft (18), and the PTO speed change When the mechanism (40) is in the neutral state and the reverse clutch (52) is in the engaged state, the high speed gear (45) and the reverse rotation switching mechanism (51) are connected via the reverse clutch (52), The PTO shaft (18) is configured to be driven in reverse by driving the neutral / reverse gear (46) with rotational power from the reverse switching mechanism (51) .

  According to the first aspect of the present invention, the reverse rotation switching capable of transmitting the rotational power branched from the downstream side of the PTO clutch in the vicinity of the PTO shaft in the transmission case in which the rotational power is transmitted from the engine mounted on the traveling machine body. The PTO speed change mechanism that includes a mechanism and shifts the output of the PTO shaft is configured to be capable of being driven in reverse rotation by power via the reverse rotation switching mechanism when in the neutral state.

  Since the vicinity of the PTO shaft is a place where a space is easily secured even in the inside of the mission case, the PTO clutch can be provided by providing the reverse rotation switching mechanism for driving the PTO shaft to rotate in such a place. The configuration corresponding to the independent reverse drive of the PTO shaft can be easily realized without complicating the structure of the power transmission path on the upstream side (for example, a traveling speed change mechanism for traveling output). For this reason, the mission case can be reduced in size and weight, and as a result, the manufacturing cost can be reduced.

  In addition, a configuration is adopted in which the PTO shaft is driven in reverse by allowing the PTO speed change mechanism to be driven in reverse by power via the reverse switching mechanism when in the neutral state. That is, since the PTO transmission mechanism is used as a configuration for driving the PTO shaft in the reverse direction, the PTO shaft is not driven in the reverse direction as long as the PTO transmission mechanism is in a state other than neutral. Therefore, not only contributes to the compactness of the power transmission path from the PTO clutch to the PTO shaft, but also has an effect of reliably preventing malfunction of the PTO shaft.

The PTO shaft is provided with a reverse clutch for interrupting transmission of the branch power to the reverse switching mechanism by operation of the PTO reverse operation means. As a result, the power transmission path from the PTO clutch to the PTO shaft can be made compact. This also helps to reduce the size and weight of the mission case and thus reduce the manufacturing cost.

  Embodiments in which the present invention is applied to a tractor as a work vehicle will be described below with reference to the drawings (FIGS. 1 to 8). 1 is a left side view of the tractor, FIG. 2 is a plan view of the interior of the cabin, FIG. 3 is a skeleton diagram of the power transmission system, FIG. 4 is a side sectional view of the rear of the transmission case, and FIG. FIG. 6 is an explanatory view showing a high speed state of the PTO transmission mechanism, FIG. 7 is an explanatory view showing a neutral state of the PTO transmission mechanism, and FIG. 8 is a state where the PTO transmission mechanism is neutral and includes a reverse clutch. It is explanatory drawing shown.

(1). First, an outline of the tractor 1 will be described with reference to FIGS. 1 and 2.

  The traveling machine body 2 of the tractor 1 in the embodiment is supported by a pair of left and right rear wheels 4 as well as a pair of left and right front wheels 3 as a traveling unit. The tractor 1 is configured to travel forward and backward by driving the front wheels 3 and the rear wheels 4 with a diesel engine 5 mounted on the front portion of the traveling machine body 2. The engine 5 is covered with a bonnet 6. A cabin 7 (steering unit) is installed on the upper surface of the traveling machine body 2, and the steering handle 8 is steered inside the cabin 7 so as to move the steering direction of the front wheel 3 left and right by steering. 9 (round handle) is arranged. A step 10 on which the operator gets on and off the cabin 7 is provided, and a fuel tank 11 for supplying fuel to the engine 5 is provided on the inner side of the cabin 10 and below the bottom of the cabin 7. .

  As shown in FIGS. 1 and 2, the steering handle 9 in the cabin 7 is disposed on a steering column 100 located in front of the steering seat 8. On the left side of the control column 100, a forward / reverse switching lever 101 for switching the traveling direction of the traveling machine body 2 between forward and reverse, and a hydraulic clutch (not shown) for disconnecting power from the engine 5 are disconnected. A clutch pedal 102 for operation is arranged. On the right side of the steering column 100, a pair of left and right brake pedals 103 for braking the traveling machine body 2 are disposed. On the right side of the steering column 100 (in the vicinity of the brake pedal 103) of the floor plate 104 in the cabin 7, an accelerator pedal 105 for increasing and decreasing the engine speed is disposed.

  Side columns 106 and 107 are provided on the left and right sides of the control seat 8. On the left side column 106, the output of the hydraulic continuously variable transmission 20 (described later) and the rotational speed of the sub-transmission lever 108 for maintaining a predetermined range according to the working state, and the output of the PTO shaft 18 (described later) are provided. A PTO speed change lever 109 serving as a PTO speed change operating means for switching between a plurality of speeds (in the embodiment, two forward rotations) and a neutral position is disposed. A parking brake lever 110 for holding the brake pedal 103 in the depressed position is disposed in front of the auxiliary transmission lever 108. A PTO reverse lever 111 as a PTO reverse operation means for performing a reverse drive operation of the PTO shaft 18 to be described later is provided on the rear side of the backrest 8a of the control seat 8 and behind the PTO speed change lever 109. 109 is arranged separately. The PTO reverse lever 111 of the embodiment is configured to be capable of rotating back and forth around the vertical axis 112.

  On the right side column 107, a main transmission lever 113 for stepping forward, stopping, retreating and changing the vehicle speed of the traveling machine body 2 and a working part such as a potato harvester arranged behind the traveling machine body 2 A working unit adjustment lever 114 and the like for manually changing and adjusting the height position (not shown) are disposed.

  On the other hand, as shown in FIG. 1, the traveling machine body 2 includes an engine frame 13 having a front bumper 12 and a front axle case (not shown), and left and right left and right fixed to the rear portion of the engine frame 13 with bolts. A body frame 14 is provided. A transmission case 15 is mounted on the rear part of the body frame 14 for appropriately shifting the power from the engine 5 and transmitting it to the front wheels 3, the rear wheels 4, and a PTO shaft 18 described later. The rear wheel 4 is attached via a rear axle case (not shown) mounted so as to protrude outward from the outer surface of the mission case 15. The upper part of the left and right rear wheels 4 is covered with a fender 16 fixed to the body frame 14.

  On the rear upper surface of the mission case 15, a hydraulic lifting mechanism 17 for lifting and lowering a working portion such as a potato harvester is detachably attached. Although not shown in detail, the working unit is connected to the rear part of the mission case 15 via a three-point link mechanism. On the rear surface of the mission case 15, a PTO shaft 18 for transmitting a PTO driving force to the working unit is provided to project rearward.

(2). Next, the power transmission system of the tractor 1 will be described with reference to FIG.

  In the tractor 1 of the embodiment, the power of the engine 5 is transmitted to the transmission case 15 via the hydraulic continuously variable transmission 20 and distributed from the transmission case 15 to the front wheels 3, the rear wheels 4 and the PTO shaft 18. It is configured. The hydraulic continuously variable transmission 20 includes a variable displacement hydraulic pump 21 and a hydraulic motor 22. The motor output shaft 24 that protrudes from the hydraulic motor 22 is obtained by changing and adjusting the inclination angle of a rotary swash plate (not shown) in the hydraulic pump 21 to change the discharge direction and discharge amount of the hydraulic oil to the hydraulic motor 22. The rotation direction and the number of rotations are arbitrarily adjusted. The hydraulic continuously variable transmission 20 according to the embodiment is provided adjacent to the mission case 15 or is externally attached to the mission case 15.

  The hydraulic continuously variable transmission 20 has two power transmission paths: a power transmission path via a pump output shaft 23 protruding from the engine 5 and penetrating the hydraulic pump 21; and a power transmission path via a motor output shaft 24 protruding from the hydraulic motor 22. Have a route. The hydraulic continuously variable transmission 20 according to the embodiment is a hydraulic / mechanical machine that rotationally drives the front wheels 3 and the rear wheels 4 by combined power composed of rotational power via the pump output shaft 23 and rotational power via the motor output shaft 24. And a hydraulic drive mode (HST mode) in which the front wheel 3 and the rear wheel 4 are driven to rotate only by the rotational power via the motor output shaft 24. Yes.

  In the HMT mode, the transmission switching mechanism 25 in the transmission case 15 combines the rotational power via the pump output shaft 23 and the rotational power via the motor output shaft 24, and the combined power is transmitted from the transmission switching mechanism 25. It is transmitted to the intermediate shaft 26. In the HST mode, only the rotational power via the motor output shaft 24 is transmitted to the intermediate shaft 26 via the transmission switching mechanism 25.

  In any mode, the rotational power transmitted to the intermediate shaft 26 is branched to the front wheel 3 side and the rear wheel 4 side via the auxiliary transmission mechanism 27. On the front wheel 3 side, a front wheel output that rotatably supports the left and right front wheels 3 via the auxiliary transmission mechanism 27, the front wheel speed increasing mechanism 28, the propulsion shaft 29 having universal joints at both front and rear ends, and the front axle mechanism 30. Power is transmitted to the shaft 31. On the rear wheel 4 side, power is transmitted from the auxiliary transmission mechanism 27 via the rear wheel differential mechanism 32 to the rear wheel output shaft 33 that rotatably supports the left and right rear wheels 4. The intermediate shaft 26, the auxiliary transmission mechanism 27, the front wheel speed increasing mechanism 28, the rear wheel differential mechanism 32, and the like are accommodated in the transmission case 15 in the same manner as the transmission switching mechanism 25 described above.

(3). Outline of PTO Drive System Next, an outline of the PTO drive system will be described with reference to FIGS.

  The rotational power of the pump output shaft 23 is transmitted to the PTO speed change mechanism 40 disposed in the rear portion of the transmission case 15 via the power transmission interrupting PTO clutch 39 regardless of the selected mode. As shown in FIG. 4, in the embodiment, a wet multi-plate clutch is employed as the PTO clutch 39. Part of the power of the pump output shaft 23 is charged from the upstream side of the PTO clutch 39 in the pump output shaft 23 through the transmission gear mechanism 38 (see FIGS. 3 and 4). It is branched and transmitted to a pump (not shown).

  The PTO transmission mechanism 40 is for shifting the output of the PTO shaft 18 in a plurality of stages (two forward rotations in the embodiment) and neutrally, and is concentrically connected to the pump output shaft 23 via the PTO clutch 39. The PTO propulsion shaft 41 and a low speed gear 44, a high speed gear 45 and a neutral / reverse gear 46 which are fitted on the PTO shaft 18 extending in parallel with the PTO propulsion shaft 41 are provided.

  Although not shown in detail, when the PTO shift lever 109 is shifted to a position other than neutral (low speed side or high speed side), the PTO clutch cylinder is operated by the switching drive of the PTO clutch hydraulic solenoid valve, and the PTO clutch 39 Is in a power connection state. As a result, the pump output shaft 23 and the PTO propulsion shaft 41 are connected so as to rotate integrally, and rotational power is transmitted from the pump output shaft 23 toward the PTO propulsion shaft 41.

  The PTO propulsion shaft 41 is integrally fixed with a low speed input gear 42 that always meshes with the low speed gear 44 of the PTO shaft 18 and a high speed input gear 43 that always meshes with the high speed gear 45 of the PTO shaft 18. The PTO propulsion shaft 41 is connected to the PTO shaft 18 so that power can be transmitted by meshing of the gears 42 and 44 (or 43 and 45).

  The low speed gear 44 and the high speed gear 45 correspond to forward rotation gear means for shifting the forward driving force of the PTO shaft 18, and the neutral / reverse gear 46 is a deceleration that receives the rotational power from the reverse rotation switching mechanism 51. This corresponds to gear means. In the embodiment, the low speed gear 44 is located on the protruding end side of the PTO shaft 18, and the high speed gear 45 is located on the base end side. A neutral / reverse gear 46 is located between the low speed gear 44 and the high speed gear 45.

  A shift slider 47 is spline-fitted to the PTO shaft 18 so as not to be relatively rotatable and to be slidable in the axial direction. The low speed gear 44, the high speed gear 45, and the neutral / reverse gear 46 are selectively connected to the PTO shaft 18 by the action of the speed change slider 47. A shift shift fork 48 that is slidable along a shifter shaft 49 arranged in parallel to the PTO propulsion shaft 41 and the PTO shaft 18 is engaged with the shift slider 47. The shift shift fork 48 is linked to a PTO shift lever 109 in the cabin 7 via a PTO shift link mechanism 50.

  The shift shift fork 48 is slid along the shifter shaft 49 and the shift slider 47 is slid along the PTO shaft 18 by the shift operation of the PTO shift lever 109, so that the gears 44- Any one of 46 is connected to the PTO shaft 18. When the low-speed gear 44 is selected, or when the high-speed gear 45 is selected, the low-speed or high-speed rotational power in the forward direction (forward drive force) is transferred from the PTO propulsion shaft 41 to the PTO shaft. 18 and the PTO shaft 18 is rotationally driven in the forward rotation direction (see FIGS. 5 and 6). Since power cannot be transmitted directly from the PTO propulsion shaft 41 to the neutral / reverse gear 46, when the neutral / reverse gear 46 is in the neutral state, rotational power from the reverse rotation switching mechanism 51 (to be described later) is transmitted to the neutral / reverse gear 46. Unless it is transmitted, the rotational power is not transmitted to the PTO shaft 18 and the drive is stopped (see FIGS. 4 and 7).

  A reverse rotation switching mechanism 51 for driving the PTO shaft 18 to rotate in reverse using the rotational power of the PTO propulsion shaft 41 is disposed in the mission case 15 below the PTO shaft 18. The reverse rotation switching mechanism 51 includes a reverse rotation clutch 52 attached to the proximal end portion of the PTO shaft 18 and a counter shaft 53 arranged in parallel with the PTO propulsion shaft 41 and the PTO shaft 18.

  The reverse clutch 52 is for interrupting power transmission to the counter shaft 53, and is fitted to the base end portion of the PTO shaft 18 so as to be relatively rotatable and slidable in the axial direction. In the embodiment, a meshing dog clutch is employed as the reverse rotation clutch 52. A clutch gear 54 is integrally formed at the outer peripheral front end of the reverse clutch 52. The clutch gear 54 is always meshed with a relay gear 58 rotatably supported by a relay shaft 57 between the PTO shaft 18 and the counter shaft 53.

  When the reverse clutch 52 is slid rearward (see FIG. 8), the reverse clutch 52 is connected to the high speed gear 45 so as to rotate integrally. When the reverse clutch 52 is slid forward and is in a disconnected state (see FIGS. 4 to 7), the connection between the two clutches 52 and 45 is released. The reverse clutch 52 is engaged with a reverse shift fork 55 that is slidable along the shifter shaft 49 described above. The reverse shift fork 55 is linked to the PTO reverse lever 111 in the cabin 7 via the PTO reverse link mechanism 56.

  On the counter shaft 53, a reverse rotation input gear 59 having a large diameter and a large number of teeth and a reverse rotation output gear 60 having a small diameter and a small number of teeth are fixed. The reverse rotation input gear 59 is always meshed with the relay gear 58 of the relay shaft 57, and the reverse rotation output gear 60 is always meshed with the neutral / reverse gear 46 of the PTO shaft 18.

  In this case, if the PTO speed change mechanism 40 is in a neutral state, the PTO shaft 18 can be driven in reverse by the rotational power from the reverse switching mechanism 51. In the embodiment, when the PTO speed change mechanism 40 is in the neutral state and the reverse rotation clutch 52 is in the engaged state, the neutral / reverse rotation gear 46 is rotationally driven by the rotational power from the reverse rotation switching mechanism 51, whereby the PTO shaft 18 is It is configured to drive in reverse.

  That is, the reverse rotation shift fork 55 is slid along the shifter shaft 49 by the reverse rotation operation of the PTO reverse rotation lever 111, and the reverse rotation clutch 52 is slid rearward along the PTO shaft 18, whereby the reverse rotation clutch 52 is engaged. Then, the reverse clutch 52 and the high speed gear 45 are connected so as to rotate integrally.

  At this time, if the PTO speed change lever 109 is operated to the neutral side and the neutral / reverse gear 46 is selected by the speed change slider 47 (if the PTO speed change mechanism 40 is in the neutral state), the high speed gear 45 is set to the PTO shaft. The neutral / reverse gear 46 and the PTO shaft 18 are connected so as to rotate integrally. Then, the rotational power of the PTO propulsion shaft 41 downstream from the PTO clutch 39 is transferred from the high speed input gear 43 to the reverse rotation input gear 59 of the counter shaft 53 via the high speed gear 45, the clutch gear 54 and the relay gear 58. The torque is transmitted from the reverse rotation output gear 60 of the counter shaft 53 to the PTO shaft 18 through the neutral / reverse gear 46 as rotational power (reverse driving force) in the reverse direction. As a result, the PTO shaft 18 is rotationally driven in the reverse direction (see FIG. 8). In the embodiment, the reverse rotation speed of the PTO shaft 18 at this time is set to be slower than the normal rotation speed at a low speed (the speed when the PTO shaft 18 is driven to rotate in the normal rotation direction at a low speed). Yes.

  Note that when the PTO speed change lever 109 is shifted to a position other than neutral (low speed side or high speed side) and the PTO reverse rotation lever 111 is operated reversely, the neutral / reverse gear 46 can freely rotate with respect to the PTO shaft 18. Therefore, the rotational power via the reverse rotation switching mechanism 51 is not transmitted to the PTO shaft 18. In particular, in the embodiment, the shift shift fork 48 and the reverse shift fork 55 slide and move along the common shifter shaft 49, and the shift position of the shift shift fork 48 in the high speed state (see FIG. 6) The sliding position of the reverse shift fork 55 (see FIG. 8) is set so as to partially overlap. For this reason, even if the PTO speed change lever 109 is operated to shift to the high speed side and the PTO reverse rotation lever 111 is operated to enter the reverse rotation, the shift forks 48 and 55 are engaged with each other. There is no situation where both are connected to the high speed gear 45 at the same time.

(4). Detailed structure of each part constituting the PTO drive system Next, a detailed structure of each part constituting the PTO drive system will be described with reference to FIGS.

  As shown in FIG. 4, the PTO propulsion shaft 41 is rotatably supported by ball bearings 61 and 62 provided on the rear upper side in the mission case 15. The low speed input gear 42 of the PTO propulsion shaft 41 is located on the rear side of the PTO propulsion shaft 41 corresponding to the low speed gear 44 of the PTO shaft 18. The high speed input gear 43 is positioned on the front side of the PTO propulsion shaft 41 corresponding to the high speed gear 45 of the PTO shaft 18.

  The PTO shaft 18 passes through a shaft hole 63 formed on the rear surface of the mission case 15 in a posture parallel to the PTO propulsion shaft 41, and ball bearings 64, 65 provided in the vicinity of the rear center in the mission case 15. It is pivotally supported by. The PTO shaft 18 includes a low speed gear 44, a neutral / reverse gear 46, a high speed gear 45, and a reverse clutch 52 in order from the protruding end side (rear side, right side in FIGS. 4 to 8) to the base end side (front side). Is attached.

  As shown in FIGS. 5 to 8, the low speed gear 44 and the high speed gear 45 are rotatably supported by the PTO shaft 18 via corresponding ball bearings 66 and 67, respectively. A ball bearing 69 is fitted on the rear boss 68 integrally formed on the rear surface side of the high speed gear 45, and the neutral and reverse gear 46 can be rotated by the ball bearing 69 fitted on the rear boss 68. Is pivotally supported. The reverse clutch 52 is rotatably supported on the PTO shaft 18 via a roller bearing 70.

  A plurality of low-speed engagement protrusions 72 are formed at appropriate intervals along the circumferential direction at the outer peripheral front end portion of the front boss portion 71 integrally formed on the front surface side of the low-speed gear 44. The rear boss 73 integrally formed on the rear surface side of the neutral / reverse gear 46 protrudes further rearward than the rear boss 68 of the high speed gear 45, and the inner peripheral rear end of the rear boss 73 in the neutral / reverse gear 46. A plurality of neutral engaging projections 74 are formed at appropriate intervals along the circumferential direction. A plurality of high-speed engagement protrusions 75 are also formed at appropriate intervals along the circumferential direction at the inner peripheral rear end of the rear boss 68 in the high-speed gear 45.

  A plurality of reverse rotation projections 77 are formed at appropriate intervals along the circumferential direction at the inner peripheral front end portion of the front boss portion 76 integrally formed on the front side of the high speed gear 45, while A plurality of reverse engaging claws 78 that can be engaged with the reverse engaging protrusions 77 of the high speed gear 45 are formed at the outer peripheral rear end of the clutch 52 at appropriate intervals along the circumferential direction.

  Between the low-speed gear 44 and the neutral / reverse gear 46 on the outer periphery of the PTO shaft 18, there are a pair of front and rear spline portions 81, 82 having spline grooves, and the spline portions 81, 82 have spline holes. The speed-change slider 47 is fitted so as not to be relatively rotatable and to be slidable in the axial direction.

  A plurality of rear engagement claws 83 that can be engaged with the low-speed engagement protrusion 72 of the low-speed gear 44 and both the front and rear spline portions 81 and 82 are appropriately provided along the circumferential direction at the rear end portion of the inner periphery of the speed change slider 47. It is formed at intervals. A plurality of central engaging claws 84 that can be engaged with both the front and rear spline portions 81 and 82 are formed in the central portion of the inner periphery of the speed change slider 47 at appropriate intervals along the circumferential direction. Furthermore, a plurality of front engagement claws 85 that can be engaged with the high-speed engagement protrusions 75 of the high-speed gear 45 and the front spline portions 81 are appropriately provided along the circumferential direction at the inner peripheral front end of the speed change slider 47. It is formed at intervals. A plurality of outer peripheral engaging claws 86 that can be engaged with the neutral engaging protrusions 74 of the neutral / reverse gear 46 are formed at appropriate intervals along the circumferential direction at the outer peripheral front end of the speed change slider 47. .

  The relay shaft 57 that rotatably supports the relay gear 58 is fixed to the partition wall in the mission case 15 so as to protrude rearward. The countershaft 53 is rotatably supported by ball bearings 87 and 88 provided on the lower side of the rear part in the mission case 15. The reverse input gear 59 of the counter shaft 53 is positioned on the front side of the counter shaft 53 corresponding to the relay gear 58 of the relay shaft 57. The reverse output gear 60 is located on the rear side of the counter shaft 53 corresponding to the neutral and reverse gear 46 of the PTO shaft 18.

  Hereinafter, the switching operation of the PTO transmission mechanism 40 will be described. As shown in FIG. 5, the PTO speed change lever 111 is disengaged between the reverse rotation engagement protrusion 77 of the high speed gear 45 and the reverse rotation engagement claw 78 of the reverse rotation clutch 52 by the reverse rotation operation of the PTO reverse rotation lever 111. When the gear 109 is shifted to the low speed side, the speed change slider 47 moves rearward along the PTO shaft 18 and the low speed engagement projection 72 of the low speed gear 44 and the rear engagement claw 83 of the speed change slider 47 engage. At the same time, the rear spline portion 82 of the PTO shaft 18 and the center engaging claw 84 of the speed change slider 47 are engaged. As a result, the PTO shaft 18 is driven to rotate in the forward direction at a low speed.

  As shown in FIG. 6, when the PTO speed change lever 109 is shifted to the high speed side while the PTO reverse rotation lever 111 is operated to rotate in the reverse direction, the speed change slider 47 moves forward along the PTO shaft 18 and the high speed gear 45 is moved. The high-speed engagement protrusion 75 and the front engagement claw 85 of the speed change slider 47 are engaged, and the rear spline portion 82 of the PTO shaft 18 and the center and rear engagement claws 84 and 83 of the speed change slider 47 are engaged. To do. As a result, the PTO shaft 18 is driven to rotate in the forward rotation direction at a high speed.

  As shown in FIG. 7, when the PTO speed change lever 109 is operated to the neutral side while the PTO reverse rotation lever 111 is operated to rotate in the reverse direction, the speed change slider 47 moves along the PTO shaft 18, The neutral engaging projection 74 and the outer peripheral engaging claw 86 of the transmission slider 47 are engaged, and the rear spline portion 82 of the PTO shaft 18 and the front and central engaging claws 85 and 84 of the transmission slider 47 are engaged. . As a result, the PTO shaft 18 is stopped.

  As shown in FIG. 8, when the PTO reverse lever 111 is operated to enter the reverse direction while the PTO speed change lever 109 is operated to the neutral side, the reverse rotation clutch 52 moves rearward along the PTO shaft 18 and the high speed gear 45 The reverse rotation projection 77 and the reverse rotation engagement claw 78 of the reverse rotation clutch 52 are engaged. As a result, the PTO shaft 18 is rotationally driven in the reverse direction at a slower speed than during the low speed forward rotation driving.

(5). According to the above-described configuration, the rotational power branched from the downstream side of the PTO clutch 39 in the vicinity of the PTO shaft 18 in the mission case 15 to which the rotational power is transmitted from the engine 5 mounted on the traveling machine body 2. The transmission reverse rotation switching mechanism 51 is provided, and when the PTO speed change mechanism 40 is in a neutral state, the PTO shaft 18 can be driven in reverse rotation by the power from the reverse rotation switching mechanism 51.

  Since the vicinity of the PTO shaft 18 is a place where it is easy to secure a space in the inside of the mission case 15, a PTO clutch 39 is provided by providing a reverse rotation switching mechanism 51 for driving the PTO shaft 18 to rotate in such a place. The configuration corresponding to the independent reverse drive of the PTO shaft 18 can be easily realized without complicating the structure of the power transmission path (for example, the transmission switching mechanism 25 and the auxiliary transmission mechanism 27) on the upstream side. For this reason, the mission case 15 can be reduced in size and weight, and as a result, can contribute to manufacturing cost reduction.

  In the embodiment, the PTO shaft 18 has a reverse clutch 52 for interrupting transmission of rotational power from the PTO propulsion shaft 41 to the reverse rotation switching mechanism 51 on the PTO shaft 18, and a PTO shift for shifting the output of the PTO shaft 18. Since the mechanism 40 is arranged, and the high speed gear 45 constituting the forward transmission gear means in the PTO transmission mechanism 40 and the reverse switching mechanism 51 are connected via the reverse clutch 52 so that the power can be disconnected. The PTO-related mechanism is gathered around the PTO shaft 18 and the vicinity thereof, and the power transmission path from the PTO clutch 39 to the PTO shaft 18 can be made compact. This also helps to reduce the size and weight of the mission case 15 and thus reduce the manufacturing cost.

  Further, when the PTO transmission mechanism 40 is in the neutral state and the reverse clutch 52 is in the engaged state, the neutral / reverse gear 46 serving as the reduction gear means is driven by the rotational power from the reverse rotation switching mechanism 51, thereby causing the PTO shaft 18. Are configured to be driven in reverse. As can be seen from this configuration, the neutral / reverse gear 46, which is the final gear for PTO output, and the reverse switching mechanism 51 exist separately, so that the neutral / reverse gear 46 is effectively utilized by utilizing the space near the PTO shaft 18. It is possible to increase the diameter (increase the number of teeth), and it is possible to easily obtain the reverse driving force decelerated with a large reduction ratio.

  In addition, since the neutral / reverse gear 46 that constitutes the PTO transmission mechanism 40 is used as a configuration for driving the PTO shaft 18 in the reverse direction, the PTO shaft can be used as long as the PTO transmission mechanism 40 is in a low speed or high speed driving state. 18 is not rotationally driven in the reverse direction. Therefore, not only contributes to the compactness of the power transmission path from the PTO clutch 39 to the PTO shaft 18, but also the malfunction of the PTO shaft 18 can be reliably prevented.

  By the way, there is rarely an opportunity to execute an operation to drive the PTO shaft 18 in the reverse direction, and it is considered that such an operation should be designed with emphasis on prevention of erroneous operation rather than improvement in operability. In this regard, when adopting a configuration in which the forward shifting operation and the reverse driving operation of the PTO shaft 18 can be executed by one operating means, the operator erroneously operates the one operating means, and when unnecessary, the PTO shaft 18 is operated. The possibility of driving in reverse cannot be denied.

  In contrast, in the embodiment, a PTO reverse lever as a PTO reverse operation means for executing a reverse drive operation of the PTO shaft 18 separately from the PTO speed change lever 109 as a PTO speed change operation means for changing the speed of the PTO speed change mechanism 40. 111 is provided, the operator executes the shift operation of the PTO transmission mechanism 40 (forward rotation shift operation of the PTO shaft 18) and the reverse drive operation of the PTO shaft 18 by operating the levers 109 and 111, respectively. Must. For this reason, it is possible to remarkably prevent or reduce an erroneous operation of rotating the PTO shaft 18 in the direction opposite to the direction in which the PTO shaft 18 is desired to be rotated, and to improve the safety when driving the PTO shaft 18.

  In addition, since the PTO reverse lever 111 that is not normally operated is disposed behind the PTO speed change lever 109, the presence of the PTO reverse lever 111 does not get in the way during normal work, and it is possible to prevent erroneous operation. It is highly effective.

(6). Others The present invention is not limited to the above-described embodiment, and can be embodied in various forms. For example, the present invention is not limited to a tractor but can be applied to agricultural machines such as rice transplanters and combines, and special work vehicles such as wheel loaders. Further, the PTO speed change operation means and the PTO reverse rotation operation means are not limited to the lever type, but may be a button type (switch type). In addition, the configuration of each unit is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention.

It is a left view of a tractor. It is a top view inside a cabin. It is a skeleton figure of a power transmission system. It is side surface sectional drawing of a mission case rear part. It is explanatory drawing which shows a state with a low speed PTO transmission mechanism. It is explanatory drawing which shows a state with a high speed PTO transmission mechanism. It is explanatory drawing which shows the state in which the PTO transmission mechanism is neutral. It is explanatory drawing which shows the state in which the PTO transmission mechanism is neutral and a reverse clutch is included.

DESCRIPTION OF SYMBOLS 1 Tractor 2 Traveling machine body 3 Front wheel 4 Rear wheel 5 Engine 7 Cabin 17 Hydraulic lifting mechanism 18 PTO shaft 20 Hydraulic continuously variable transmission 39 PTO clutch 40 PTO transmission mechanism 41 PTO propulsion shaft 44 Low speed gear 45 High speed gear 46 Reverse gear 47 Shift slider 51 Reverse switching mechanism 52 Reverse clutch 53 Counter shaft 54 Clutch gear 109 PTO speed change lever 111 PTO reverse speed lever

Claims (1)

A PTO shaft (18) for transmitting the power of the engine (5) to the working part to a transmission case (15) to which power is transmitted from the engine (5) mounted on the traveling machine body (2), and the PTO shaft ( a PTO clutch (39) for Tsugidan power transmission to 18), wherein comprises a PTO transmission mechanism (40) for shifting the output of the PTO shaft (18), of the transmission in the case (15) wherein In the vicinity of the PTO shaft (18), there is a reverse rotation switching mechanism (51) capable of transmitting power branched from the downstream side of the PTO clutch (39), and the PTO speed change mechanism (40) A work vehicle configured to be capable of reverse drive with power via the reverse switching mechanism (51) when in a neutral state ;
In order to cut off transmission of the branch power to the low speed gear (44), the high speed gear (45) and the neutral / reverse gear (46) constituting the PTO transmission mechanism (40) and the reverse switching mechanism (51). Of the reverse clutch (52) is disposed on the PTO shaft (18),
When the PTO transmission mechanism (40) is in a neutral state and the reverse clutch (52) is in an engaged state, the high speed gear (45) and the reverse rotation switching mechanism (51) are connected via the reverse clutch (52). The PTO shaft (18) is reversely driven by driving the neutral and reverse gear (46) with rotational power from the reverse switching mechanism (51).
Work vehicle.

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