JP2007131090A - Working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle capable of improving driving operability and the like while simplifying a structure of a vehicle-speed maintaining mechanism. <P>SOLUTION: A vehicle-speed maintaining mechanism comprises a lock arm having a plurality of lock pawls to be detachably engaged, and a locking element. The lock arm is connected with the shift pedal, and the lock element is coupled with a manual operation lever for maintaining the vehicle speed. Engagement of the lock pawls and the locking element can be maintained by an energizing force of an initial position return spring for returning the shift pedal from a treading position to an initial position and making the vehicle speed zero. <P>COPYRIGHT: (C)2007,JPO&INPIT

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. More specifically, the present invention relates to holding a shift pedal at a predetermined depression position to keep the vehicle speed of a traveling machine body constant. The present invention relates to a work vehicle having a vehicle speed maintenance mechanism (auto cruise mechanism).

  Conventionally, in general, in a working vehicle such as a tractor or a wheel loader described above, when power is transmitted to traveling parts such as left and right traveling wheels or traveling crawlers, power is transmitted from an engine mounted on a traveling machine body in the working vehicle to a transmission case. Thus, it is configured to output to the left and right traveling parts via the transmission mechanism of the transmission case.

In this case, in a conventional work vehicle, a transmission case is provided in the traveling machine body, a hydrostatic continuously variable transmission is provided in the transmission case, and power from the engine is input to the continuously variable transmission. In addition, power is transmitted from the continuously variable transmission to the traveling unit via the transmission case. And a speed change pedal for increasing and reducing the speed change output of the hydrostatic continuously variable transmission, and a vehicle speed maintaining mechanism (pedal lock mechanism) for keeping the vehicle speed (moving speed) of the traveling body substantially constant. ing. The vehicle speed maintaining mechanism includes a plurality of locking claws (locked portions) that are detachably engaged and one locking body (locking portion), and one of the plurality of locking claws. The shift pedal is held at a predetermined depression position by engagement between one and the locking body (see, for example, Patent Document 1).
JP-A-8-80770

  In the prior art, the shift pedal is provided with the locking body (locking portion), and the locking arm (locking member) is provided with the plurality of locking claws (locked portions) to maintain the vehicle speed manually. A locking arm is connected to an operation lever (lock lever), and the locking body and the locking claw can be locked or unlocked via the manual operation lever. Therefore, when the manual operation lever is unlocked, the force at which the output of the continuously variable transmission returns to zero, for example, the speed change swash plate of the hydraulic pump (or hydraulic motor) of the continuously variable transmission has zero output. The shift pedal returns to the initial position in a very short time due to the force for returning to the position or the spring force for maintaining the shift swash plate and the shift pedal at the initial position. Therefore, in a work vehicle such as a tractor or a wheel loader that often performs agricultural work or civil engineering work in a place where the running road surface resistance is large (the distance traveled by inertia is short), the shift pedal suddenly returns to the initial position, There is a problem that the moving speed is instantaneously decelerated from a constant speed to zero vehicle speed, and a large impact (moment of inertia) is generated in the operator or the working unit. For example, when the manual operation lever is unlocked due to an erroneous operation during work such as farm work or civil engineering work, the vehicle speed is drastically decelerated, causing the traveling machine body and the working unit to tilt greatly, Or fallen soil or compost from the wheel loader bucket.

  The object of the present invention is that the vehicle speed maintaining mechanism can be configured with a simple structure by the locking claw and the locking body, but the locking claw and the locking mechanism are caused by an erroneous operation of the manual operation lever for maintaining the vehicle speed. It is an object of the present invention to provide a work vehicle that can easily prevent disengagement from a locking body and improve driving operability.

  To achieve the above object, a power transmission device for a work vehicle according to a first aspect of the present invention includes an engine mounted on a traveling machine body including a traveling unit, and a hydraulic continuously variable transmission that shifts power from the engine. A transmission case that transmits a shift output from the hydraulic continuously variable transmission to the traveling unit via a shift output gear; and a shift pedal that is coupled to a shift operation unit of the hydraulic continuously variable transmission via a shift mechanism. And a vehicle speed maintaining mechanism that holds the shift pedal in the depressing operation position, wherein the vehicle speed maintaining mechanism includes a locking arm having a plurality of locking claws that are detachably engaged, A stop body, the locking arm is connected to the speed change pedal, the locking body is connected to a manual operation lever for maintaining the vehicle speed, and the speed change pedal is returned from the depressed position to the initial position so that the vehicle speed is substantially zero. To make By the biasing force of the initial position return spring, in which are configured to be able to maintain the engagement between the locking member and the locking claw.

  According to a second aspect of the present invention, in the power transmission device for a work vehicle according to the first aspect, a locking link is rotatably disposed on the traveling machine body, and one end side of the locking link is disposed on the manual operation lever. And the locking body is arranged on the other end side of the locking link.

  According to a third aspect of the present invention, in the power transmission device for a work vehicle according to the second aspect, one end side of a locking arm is connected to the shift pedal, and a plurality of the engagement members are connected to the other end side of the locking arm. A pawl is formed, and the locking body of the locking link and the locking claw of the locking arm are arranged to face each other.

  According to a fourth aspect of the present invention, in the power transmission device for a work vehicle according to the third aspect, the shift pedal includes a forward pedal and a reverse pedal, and the forward pedal is driven by a spring force of one initial position return spring. The reverse pedal is returned from the depressed position to the initial position, and the shift operation portion of the hydraulic continuously variable transmission is returned to the output zero position.

  According to a fifth aspect of the present invention, in the power transmission device for a work vehicle according to the fourth aspect, the forward pedal and the reverse pedal are rotated on the pedal frame of the traveling machine body via the forward pedal shaft and the reverse pedal shaft. Via a check mechanism that supports each of the forward pedal and the reverse pedal, and connects the shift operation portion of the continuously variable transmission to prevent simultaneous depression of the forward pedal and the reverse pedal. Thus, the forward pedal and the reverse pedal are connected to each other so that the stepping operation directions of the forward pedal and the reverse pedal are substantially matched.

  According to the first aspect of the present invention, the engine mounted on the traveling machine body including the traveling unit, the hydraulic continuously variable transmission that shifts the power from the engine, and the traveling unit via the transmission output gear. A transmission case that transmits a shift output from the hydraulic continuously variable transmission, a shift pedal that is connected to a shift operation portion of the hydraulic continuously variable transmission via a shift mechanism, and the shift pedal is held in a step-on operation position. In a work vehicle including a vehicle speed maintaining mechanism, the vehicle speed maintaining mechanism includes a locking arm having a plurality of locking claws that can be engaged and disengaged, and a locking body. A stop arm is connected, the locking body is connected to a manual operation lever for maintaining the vehicle speed, and an urging force of an initial position return spring for returning the shift pedal from the depressed position to the initial position to make the vehicle speed substantially zero. , Said locking claw Since the engagement with the locking body can be maintained, the force for returning the shift pedal from the depressed position to the initial position (force for returning the shift output of the hydraulic continuously variable transmission to zero) The engagement between the locking claw and the locking body can be continued. That is, since the operating force of the manual operating lever that the operator pushes (pulls) with one hand is smaller than the pressing force of the shift pedal that the operator steps on with the foot, the initial position return spring is operated by the operating force of the manual operating lever. The force can be set large, and the engagement between the locking claw and the locking body is not easily released by the operation of the manual operation lever. Therefore, it is possible to easily prevent the engagement between the locking claw and the locking body due to an erroneous operation of the manual operation lever, and to improve driving operability and the like. Even if the initial position return spring force is larger than the operation force of the manual operation lever, the operator can easily step on the shift pedal with his / her foot, and the shift operation portion of the hydraulic continuously variable transmission can be It can be easily returned to the output zero position.

  According to the invention which concerns on Claim 2, it arrange | positions the latching link to the said traveling body so that rotation is possible, it connects the one end side of the said latching link with the said manual operation lever, Since the locking body is disposed, the locking body is integrally formed on the locking link as compared to the conventional structure in which a plurality of the locking claws are formed on the locking link. The locking link can be configured to be lightweight and simple. Therefore, since the locking body can be easily supported at a position separated from the locking claw by a spring force smaller than the initial position return spring force, the locking body is engaged with the locking claw. The operation force of the manual operation lever can be reduced.

  According to the invention of claim 3, one end side of the locking arm is connected to the shift pedal, a plurality of the locking claws are formed on the other end side of the locking arm, and the locking link is engaged. Since the stationary body and the locking claws of the locking arm are arranged to face each other, the strength of the plurality of locking claws formed on the locking arm can be easily improved. That is, even if the locking arm is formed with high rigidity so as to improve the strength of the locking claw, the locking arm can be formed lighter than the shift pedal. Compared with the conventional structure in which the locking claw is formed, the highly rigid locking arm and the locking claw can be easily formed without impairing the speed change function of the shift pedal.

  According to a fourth aspect of the present invention, the shift pedal is composed of a forward pedal and a reverse pedal, and the forward pedal and the reverse pedal are returned from the depressed position to the initial position by the spring force of one of the initial position return springs. In addition, since the shift operation unit of the hydraulic continuously variable transmission is configured to return to the output zero position, the output zero position of the shift operation unit of the hydraulic continuously variable transmission can be easily set. it can. That is, an output zero adjustment unit that maintains the shift operation unit at the output zero position by the initial position return spring, and an initial position adjustment unit that returns the forward pedal and the reverse pedal to the initial position by the initial position return spring are adjusted. The parts can also be formed and the output zero adjustment unit and the initial position adjustment unit can be easily configured. Therefore, the assembly workability and maintenance workability of the forward pedal and the reverse pedal can be improved.

  According to the fifth aspect of the present invention, the forward pedal and the reverse pedal are pivotally supported on the pedal frame of the traveling machine body via the forward pedal shaft and the reverse pedal shaft, respectively, and the forward pedal and the reverse pedal are supported. One of the pedals is connected to the speed change operation portion of the continuously variable transmission, and the forward pedal and the reverse pedal are connected via a check mechanism that prevents simultaneous operation of the forward pedal and the reverse pedal. Since the forward operation directions of the forward pedal and the reverse pedal are configured to substantially coincide with each other, the operator can step on the forward pedal and the reverse pedal on the front side of the foot. For example, the forward pedal and the reverse pedal can be placed close to the front side of the right foot of the operator who is seated on the control seat of the traveling body, and the operator moves the right foot to the left and right to step on the forward pedal or the reverse pedal. Can be. Therefore, compared with the conventional structure in which the operator steps on the forward pedal on the front side of the foot and steps on the reverse pedal on the rear side of the foot, the function of preventing the simultaneous depression of the forward pedal and the reverse pedal is not impaired. The pedal operability can be improved.

  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 plan view of the traveling aircraft body, FIG. 3 is an enlarged plan view of the latter half of the traveling aircraft body, and FIG. 4 is an enlarged plan view of a peripheral portion of a step frame of the traveling aircraft body. 5 is a perspective view of a pedal or the like operated by an operator, FIG. 6 is a sectional side view of the mission case and the mission front case, FIG. 7 is an explanatory front view of the mission front case, and FIG. 8 is a hydraulic circuit diagram.

  As shown in FIGS. 1 and 2, the tractor 1 supports a traveling machine body 2 with a pair of left and right rear wheels 4 as well as a pair of left and right front wheels 3, and an engine 5 mounted on the front portion of the traveling machine body 2. The two rear wheels 4 and the two front wheels 3 are driven to drive forward and backward. The traveling machine body 2 has an engine frame 8 having a front bumper 6 and a front axle case 7, a clutch housing 10 having a main clutch 9 for interrupting power output from the engine 5, and a speed change of the engine 5 as appropriate. A transmission case 11 for transmitting to the rear wheels 4 and the front wheels 3, a transmission front case 12 for connecting the transmission case 11 to the clutch housing 10, and outward from the outer surface of the clutch housing 10. It comprises a pair of left and right step frames 13 that are detachably mounted so as to protrude.

  The rear end side of the engine frame 8 is connected to the left and right outer surfaces of the engine 5. The front side of the clutch housing 10 is connected to the rear side of the engine 5. The front side of the mission case 11 is connected to the rear side of the clutch housing 10 via a mission front case 12.

  The engine 5 is covered with a hood 14. A steering column 15 is erected on the upper surface of the clutch housing 10. A steering handle 16 that is steered by moving the front wheels 3 to the left and right is disposed on the upper surface side of the steering column 15. A control seat 17 is disposed on the upper surface of the mission case 11. Flat floor boards 18 are respectively provided on the upper surfaces of the pair of left and right step frames 13. Both front wheels 3 are attached to the engine frame 8 via a front axle case 7. Further, as shown in FIG. 3, both rear wheels 4 are connected to the transmission case 11 via a rear axle case 11a that is detachably mounted so as to protrude outward from the outer surface of the transmission case 11. Installed. The upper surface side of both rear wheels 4 is covered with left and right rear fenders 4a.

  On the upper surface of the transmission case 11, a hydraulic working machine lifting mechanism 20 for lifting and lowering a working machine 19 such as a tiller connected to the rear part of the traveling machine body 2 is detachably attached. Further, a PTO shaft 21 for transmitting a driving force to the work machine 19 is provided on the rear side surface of the transmission case 11 so as to protrude rearward. The work machine 19 is connected to the rear portion of the mission case 11 via a three-point link mechanism 24 including a pair of left and right lower links 22 and one top link 23. When the left and right lift arms 20a of the work implement lifting mechanism 20 are connected to the left and right lower links 22 via the lift links 20b and the work implement lift mechanism 20 is operated, the work implement 19 moves up and down. .

  A hydrostatic continuously variable transmission (HST) 25 described later is disposed on the front side surface of the mission front case 12. The hydrostatic continuously variable transmission 25 is installed in the rear part of the clutch housing 10. The rotation of the engine 5 is transmitted to the continuously variable transmission 25 via a main drive shaft 26 protruding rearward from the main clutch 9, and then the output from the continuously variable transmission 25 is transmitted by a sub transmission gear mechanism 59 described later. The gears are appropriately shifted and transmitted to the rear wheels 4 and the front wheels 3. On the other hand, the rotation of the engine 5 from the main drive shaft 26 is transmitted to a PTO output reduction gear mechanism 62, which will be described later, via a PTO transmission shaft 62a and a PTO clutch 62b, and is appropriately decelerated by the PTO output reduction gear mechanism 62. Then, it is transmitted to the PTO shaft 21.

  Next, with reference to FIG.4 and FIG.5, the structure of the control part which the operator of the control seat 17 operates is demonstrated. A clutch pedal 31 for disengaging the main clutch 9 is disposed on the left side of the control column 15 protruding upward from the floor plate 18 in front of the control seat 17. A clutch release mechanism 39 that disconnects the main clutch 9 and a clutch-containing spring 40 that maintains the clutch pedal 31 in the initial position are connected to the clutch pedal 31, and the clutch pedal 31 is maintained in the initial position by the clutch-containing spring 40. Will be. A clutch operating shaft 302 is pivotally supported on the clutch housing 10, and a release fork of the clutch disengaging mechanism 39 in the clutch housing 10 is disposed on the clutch operating shaft 302. Further, a boss 31b at the base end of the pedal arm 31a of the clutch pedal 31 is rotatably fitted to a brake operation shaft 262, which will be described later, and the clutch pedal 31 is connected to the clutch operation shaft 302 via the clutch operation link mechanism 303. (See FIG. 5). By depressing the clutch pedal 31, the main clutch 9 is disengaged. The clutch operation link mechanism 303 includes a first clutch link 305 fixed to the boss portion 31b, a second clutch link 304 fixed to the clutch operation shaft 302, and a clutch rod 306 connected to the links 304 and 305. Consists of.

  On the other hand, a single brake pedal 33 for operating the left and right rear wheel braking brake mechanism 32 and a parking brake lever 34 are arranged to the right of the steering column 15. Left and right rear wheel braking brake mechanisms 32 are connected to the brake pedal 33 via left and right brake rods 32a, and the brake mechanism 32 is activated by the operation of the brake pedal 33, and the left and right rear wheels 4 are braked. It will be. Further, the brake pedal 33 is maintained in the depressed position by the operation of the parking brake lever 34, and the braking of the rear wheel 4 is continued even if the operator lifts his / her foot from the brake pedal 33. A brake operation bearing portion 261 is integrally formed at the bottom of the clutch housing 10 by casting. A brake operation shaft 262 is rotatably supported on the brake operation bearing portion 261 (see FIG. 6). The left and right brake rods 32a are connected to the brake pedal 33 via a brake operation shaft 262 (see FIG. 5).

  Further, to the right of the steering column 15, there are a forward pedal 36 and a reverse pedal 37 that operate the trunnion arm 35 for speed change operation of the continuously variable transmission 25, and a cruise lever 38 that maintains the forward pedal 36 in the stepping operation position. Is arranged. A trunnion arm 35 is connected to the forward pedal 36 and the reverse pedal 37 via a speed change link mechanism 300, and the stepless transmission 25 is operated by a stepping operation of the forward pedal 36 or the reverse pedal 37, so that the continuously variable transmission 25 is moved forward or reverse. A shifting operation is performed.

  The structure of the clutch housing 10, the transmission front case 12, and the transmission case 11 will be described with reference to FIGS. The interior of the clutch housing 10 is partitioned by a housing inner wall 50 so as to be divided into front and rear, and a housing front chamber 51 and a housing rear chamber 52 are formed inside the clutch housing 10. The interior of the mission front case 12 is partitioned by a front wall 53 so as to be divided into front and rear, and a front case front chamber 54 and a front case rear chamber 55 are formed inside the mission front case 12. The interior of the mission case 11 is partitioned by a mission inner wall 56 so as to be divided into front and rear, and a mission front chamber 57 and a mission rear chamber 58 are formed inside the mission case 11.

  In a closed space formed by the housing rear chamber 52 and the front case front chamber 54, a continuously variable transmission 25 disposed in front of the front wall 53 is provided. In the closed space formed by the front case rear chamber 55 and the mission front chamber 57, an auxiliary transmission gear mechanism 59 and a front wheel drive mechanism 60 are provided. A rear wheel differential gear mechanism 61 and a PTO output reduction gear mechanism 62 are provided inside the mission rear chamber 58.

  Next, the main transmission structure of the continuously variable transmission 25 will be described. The continuously variable transmission 25 includes a transmission hydraulic pump 63 and a transmission hydraulic motor 64 that is operated by the hydraulic pump 63 (see FIG. 7). A front end side of the transmission input shaft 65 of the continuously variable transmission 25 protrudes from the housing front chamber 51 through a through hole 50 a in the housing inner wall 50. The rear end side of the main drive shaft 26 is connected to the front end side of the speed change input shaft 65 via a coupling 66. A main transmission output shaft 67 of the continuously variable transmission 25 protrudes inside the front case rear chamber 55. A main transmission output gear 68 is fitted on the main transmission output shaft 67. A counter input gear 70 is fitted on the counter shaft 69 of the auxiliary transmission gear mechanism 59. A counter input gear 70 is engaged with the main transmission output gear 68. The continuously variable transmission output from the main transmission output shaft 67 is transmitted to the counter shaft 69 via the main transmission output gear 68 and the counter input gear 70.

  Next, the auxiliary transmission gear mechanism 59 will be described. The counter shaft 69 is integrally formed with a sub-speed first speed (low speed) counter gear 71 and a sub-speed second speed (medium speed) counter gear 72. Further, the counter shaft 69 is fitted with a sub-speed third speed (high speed) counter gear 73. Also, a sub-speed 1-speed output gear 74 meshed with the first-speed counter gear 71, a sub-speed 2-speed output gear 75 meshed with the 2-speed counter gear 72, and a 3-speed sub-gear 3 meshed with the 3-speed counter gear 73 A high-speed output gear 76 is provided. A first speed output gear 74 and a third speed output gear 76 are rotatably fitted to the sub transmission output shaft 77 of the sub transmission gear mechanism 59. The auxiliary transmission output shaft 77 is fitted with an auxiliary transmission slider 78 that is slidable in the axial direction and rotates integrally. A second speed output gear 75 is formed integrally with the auxiliary transmission slider 78.

  Therefore, the second-speed output gear 75 is engaged with the second-speed counter gear 72 by moving the auxiliary transmission slider 78 by operating the auxiliary transmission shifter 79. On the other hand, the first speed output gear 74 or the third speed output gear 76 is selectively connected to the auxiliary transmission slider 78 via the first speed clutch pawl 80 or the third speed clutch pawl 81. In other words, the rotation of the auxiliary transmission output shaft 77 is shifted in three stages via any one of the first speed output gear 74, the second speed output gear 75, and the third speed output gear 76.

  On the other hand, the rear end side of the auxiliary transmission output shaft 77 protrudes into the mission rear chamber 58. A pinion gear 82 for transmitting a rotational force to the rear wheel differential gear mechanism 61 is integrally formed on the rear end side of the auxiliary transmission output shaft 77. The power from the auxiliary transmission output shaft 77 is transmitted to the left and right rear wheels 4 via the pinion gear 82 and the differential gear mechanism 61.

  Next, the front wheel drive mechanism 60 will be described. A front wheel output shaft 85 of the front wheel drive mechanism 60 is connected to the front end side of the auxiliary transmission output shaft 77 via front wheel drive gears 83 and 84. A front wheel drive gear 84 that is rotatably fitted on the rear end side of the front wheel output shaft 85 protruding into the front case rear chamber 55, and the front wheel drive gear 84 is engaged with and disengaged from the front wheel output shaft 85. A front wheel output clutch 86 is arranged for locking in a possible manner. Further, an intermediate portion of the front wheel output shaft 85 is supported by the front wall 53 via a ball bearing. The front end side of the front wheel output shaft 85 protrudes into the front case front chamber 54.

  The rear end side of the front wheel transmission shaft 88 is connected to the front end side of the front wheel output shaft 85 via a universal shaft joint 250. The front end side of the front wheel transmission shaft 88 is extended toward the front side of the traveling machine body 2, and the driving force is transmitted from the front end side of the front wheel transmission shaft 88 to the front wheel 3 via the front axle case 7. . The front wheel transmission shaft 88 is fitted with a shaft cover 89 made of synthetic resin pipe, and the front wheel transmission shaft 88 is protected by the shaft cover 89.

  As shown in FIG. 7, a front wheel drive extraction shaft 85 is disposed between the continuously variable transmission 25 and the transmission link mechanism 300. That is, the hydraulic continuously variable transmission 25 is fixed to the transmission front case 12 while being inclined toward the right side of the traveling machine body 2 in a front view. A space for installing the front wheel drive take-off shaft 85 can be easily secured in the transmission front case 12 with the link mechanism 300.

  In addition, the shift link mechanism 300 disposed on the right side of the traveling machine body 2 in the traveling direction and the lower end side of the trunnion arm 35 disposed on the right side of the hydraulic continuously variable transmission 25 are brought close to each other, so that the clutch housing 10 right side walls can be arranged to face each other. In addition, the right side surface of the hydraulic continuously variable transmission 25 and the upper end side of the trunnion arm 35 can approach each other, and the trunnion shaft 301 for supporting the trunnion arm 35 on the hydraulic continuously variable transmission 25 can be formed in a short length. Become. The trunnion shaft 301 is formed from a base material of a hexagonal columnar rod body by cutting, and assembled to the case of the hydraulic continuously variable transmission 25 from the outside of the clutch housing 10 to form a trunnion shaft 301 formed into a square column shape. A trunnion arm 35 is detachably fixed to the distal end side of the head.

  FIG. 8 shows a hydraulic circuit 200 of the tractor 1 according to this embodiment, which includes a working machine hydraulic pump 94 and a charging hydraulic pump 95 that are operated by the rotational force of the engine 5. The charging hydraulic pump 95 is connected to a double-acting steering hydraulic cylinder 202 for power steering by the steering handle 16 via a steering control valve 201 for power steering. The working machine hydraulic pump 94 is connected to a lifting hydraulic switching valve 204 for supplying hydraulic oil to a single-acting lifting hydraulic cylinder 203 in the working machine lifting mechanism 20.

  Therefore, the operator operates the position lever 205 to switch the lifting hydraulic switching valve 204 to operate the lifting hydraulic cylinder 203 and rotate the lift arm 20a, so that the work machine 19 is connected via the lower link 22. Will be raised or lowered.

  As shown in FIG. 8, the variable displacement shift hydraulic pump 63 of the hydraulic continuously variable transmission 25 described above, and a constant displacement shift hydraulic pressure that operates with high-pressure hydraulic fluid discharged from the hydraulic pump 63. The suction side and discharge side of the motor 64 are connected via a closed loop oil passage 207. By adjusting the angle of the swash plate 208 of the transmission hydraulic pump 63 driven through the transmission input shaft 65, the rotational speed of the main transmission output shaft 67 driven through the transmission hydraulic motor 64 is changed. become. The hydraulic circuit 200 described above includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like, as shown in FIG.

  Next, with reference to FIGS. 9 to 15, a mounting structure for the forward pedal 36 and the reverse pedal 37 will be described. As shown in FIGS. 9 and 13, the base frame 310 is detachably fastened to the side surface on the right side in the traveling direction of the clutch housing 10 by a plurality of bolts 311. A vertical plate 314 is integrally fixed to the base frame 310 by welding via front and rear horizontal plates 312 and 313. That is, the pedal unit frame 309 that is rectangular in plan view for assembling the forward pedal 36 and the reverse pedal 37 is formed of the base frame 310, the front and rear lateral plates 312 and 313, and the longitudinal plate 314. The pedal unit frame 309 is disposed on the right side surface of the clutch housing 10 below the right step frame 13 in the traveling direction (forward).

  As shown in FIGS. 12 and 13, the base frame 310 and the vertical side plate 314 extend along the right side surface of the clutch housing 10 so as to be substantially parallel to the front-rear direction (traveling direction) of the traveling machine body 2. . The forward pedal shaft 315 and the reverse pedal shaft 316 are pivotally supported on the base frame 310 and the vertical side plate 314, and the forward pedal shaft 315 and the reverse pedal shaft 316 are disposed between the front and rear lateral plates 312 and 313. One end sides of the forward pedal shaft 315 and the reverse pedal shaft 316 protrude outward from the vertical side plate 314. A boss 318 on the base end side of the pedal arm 317 of the forward pedal 36 is fitted on one end side of the forward pedal shaft 315 on the outer side of the vertical side plate 314. Further, the boss portion 320 on the base end side of the pedal arm 319 of the reverse pedal 37 is fitted on one end side of the reverse pedal shaft 316 on the outer side of the vertical side plate 314.

  Accordingly, the forward pedal 36 and the reverse pedal 37 are disposed so as to be rotatable around the axis lines of the forward pedal shaft 315 and the reverse pedal shaft 316. The pedal arm 317 of the forward pedal 36 and the pedal arm 319 of the backward pedal 37 are provided so as to project diagonally forward and upward from the forward pedal shaft 315 and the backward pedal shaft 316, and the backward pedal 37 is obliquely rearward of the forward pedal 36. Is arranged. Both the forward pedal 36 and the reverse pedal 37 are stepped on in substantially the same direction diagonally forward and downward. The stepping operation directions (obliquely forward and downward) of the clutch pedal 31, the brake pedal 33, the forward pedal 36, and the reverse pedal 37 described above substantially coincide with each other.

  As shown in FIGS. 12 and 14, stop arms 321 and 322 are fixed to the boss portion 318 of the forward pedal shaft 315 and the boss portion 320 of the reverse pedal shaft 316. Bolt-shaped forward stoppers 323 and reverse stoppers 324 for bringing the stop arms 321 and 322 into contact with each other are arranged on the outer surface of the vertical side plate 314. A forward stopper 323 and a backward stopper 324 are screwed to a stopper receiving bracket 325 fixed to the vertical side plate 314 by welding so that the positions thereof can be adjusted. Accordingly, the stop arms 321 and 322 abut against the forward stopper 323 and the reverse stopper 324, and the stepping operation in the speed increasing direction of the forward pedal 36 and the reverse pedal 37 is restricted, and the maximum speed on the forward side and the reverse side is set to the forward stopper 323. And the reverse stopper 324 is set.

  As shown in FIG. 11 and FIG. 14, the proximal end portion of the pressing arm 326 is fixed to the forward pedal shaft 315, and the contact roller 328 is rotatable at the distal end portion of the pressing arm 326 via the roller shaft 327. Pivot. Further, the base end portion of the swing arm 329 is fixed to the reverse pedal shaft 316. The swing arm 329 is integrally formed with a pressure receiving piece 330 and a locking piece 331. The pressure receiving piece 330 is brought into contact with the contact roller 328, and a tension spring 332 is connected to the roller shaft 327 and the locking piece 331. Therefore, the contact roller 328 and the pressure receiving piece 330 always come into contact with each other by the spring force of the tension spring 332.

  Further, as shown in FIGS. 11 and 14, the base end portion of the speed change arm 333 is fixed to the reverse pedal shaft 316, and the front end portion of the speed change arm 333 is expanded and contracted via the connecting pin 334 and the joint bracket 335. One end of the adjustable speed change rod 336 is connected. The other end side of the speed change rod 336 is connected to the trunnion arm 35 described above via a connecting shaft 337.

  In addition, a neutral holding spring 339 sandwiched between the clutch housing 10 via a spring holder 338 is disposed. A locking shaft 341 is fixed to the clutch housing 10 via a neutral adjustment body 340. Both ends of the neutral holding spring 339 are locked to the connecting shaft 337 and the locking shaft 341. The neutral adjustment body 340 is fixed to the clutch housing 10 by one fulcrum bolt 342 for neutral adjustment and two neutral adjustment bolts 343. The neutral adjustment bolt 343 is passed through the long hole-type neutral adjustment hole 344 of the neutral adjustment body 340. A shift regulation hole 345 is formed in the neutral adjustment body 340, and the coupling shaft 337 is passed through the long hole-shaped shift regulation hole 345.

  As shown in FIG. 11, the shift restriction hole 345 is formed to be long in the circumferential direction around the trunnion shaft 301. Therefore, the trunnion arm 35 is rotated forward or backward about the trunnion shaft 301 in the continuously variable transmission range in which the connecting shaft 337 moves within the speed regulation hole 345.

  On the other hand, the neutral adjustment hole 344 of the neutral adjustment body 340 is formed long in the circumferential direction around the fulcrum bolt 342. Accordingly, the neutral adjustment bolt 343 is loosened, the neutral adjustment body 340 is rotated around the fulcrum bolt 342, the locking shaft 340 is moved to adjust the neutral (zero output) position, and the transmission restriction hole 345 is By moving, the continuously variable transmission range of the connecting shaft 337 is adjusted.

  As shown in FIGS. 12 and 13, the base end portion of the treading force adjustment link 346 is fixed to the forward pedal shaft 315. One end side of the pedal force frame 349 is connected to one of a plurality of pedal force adjustment holes formed in the pedal force adjustment link 346 via a pedal force adjustment pin 348. Further, the base end portion of the connection link 351 and the base end portion of the pedaling force link 352 are fixed to the rotatable cylindrical shaft body 350 on the pedal operation shaft 262 described above. A distal end portion of the connection link 351 is connected to the other end side of the pedaling force frame 349 via a connection pin 353. A pedal force damper 355 is connected to the tip of the pedal force link 352 via a support pin 354. The pedal force damper 355 is assembled to the outside of the clutch housing 10 via a damper mounting shaft 356 (see FIG. 5).

  Next, the shifting operation of the continuously variable transmission 25 executed by operating the forward pedal 36 and the reverse pedal 37 will be described. First, when an operator sitting on the control seat 17 depresses the forward pedal 36 with the right foot, the pressing arm 326 is rotated around the forward pedal shaft 315 and the swing arm 329 is moved backward by the contact roller 328. Rotate around 316. The transmission arm 333 is rotated on the reverse pedal shaft 316 by the rotation of the swing arm 329, the transmission rod 336 is pushed by the transmission arm 333, and the trunnion arm 35 and the trunnion shaft 301 are resisted against the force of the neutral holding spring 339. Rotates in the forward direction (clockwise in FIG. 11), operates the continuously variable transmission 25 to the forward side, drives the front wheels 3 and the rear wheels 4 to the forward side, and moves the traveling machine body 2 in the forward direction. Let

  Therefore, when the forward pedal 36 is depressed, the moving speed of the traveling machine body 2 can be changed in proportion to the amount of depression of the forward pedal 36, and until the stop arm 321 comes into contact with the forward stopper 323, or the connecting shaft 337 is controlled to change speed. The forward pedal 36 can be depressed to increase the speed toward the forward side until it contacts the one end side of the hole 345. Further, when the forward pedal 36 is stepped on and the swing arm 329 is rotated, the reverse pedal 37 is rotated around the reverse pedal shaft 316 in the direction opposite to the stepping operation direction.

  On the other hand, when the operator sitting on the control seat 17 steps on the reverse pedal 37 with the right foot, the transmission arm 333 on the reverse pedal shaft 316 is rotated via the swing arm 329, and the transmission rod 333 is rotated by the transmission arm 333. 336 is pulled, the trunnion arm 35 and the trunnion shaft 301 are rotated in the reverse direction (counterclockwise in FIG. 11) against the force of the neutral holding spring 339, and the above-described continuously variable transmission 25 is operated in the reverse direction. Then, the front wheel 3 and the rear wheel 4 are driven backward, and the traveling machine body 2 is moved in the reverse direction.

  Therefore, when the reverse pedal 37 is depressed, the moving speed of the traveling machine body 2 can be changed in proportion to the amount of depression of the reverse pedal 37 until the stop arm 322 comes into contact with the reverse stopper 324 or the connecting shaft 337 is controlled to change the speed. The reverse pedal 37 can be depressed to increase the reverse speed until it contacts the other end of the hole 345. Further, when the reverse pedal 37 is depressed, the pressing arm 326 is rotated via the contact roller 328 by the rotation of the swing arm 329, and the forward pedal 36 is moved in the direction opposite to the stepping operation direction. It is rotated around 315.

  When the foot is released from the forward pedal 36 or the reverse pedal 37, the forward pedal 36 and the reverse pedal 37 gently return to the neutral position (output zero position) by the regulation of the pedal force damper 355 by the neutral holding spring 339 force, The shift output of the continuously variable transmission 25 is maintained at substantially zero.

  Next, referring to FIG. 9, FIG. 11, FIG. 14 and FIG. 15, a vehicle speed maintenance mechanism (automatic mechanism) for maintaining the vehicle speed of the traveling machine body 2 at a predetermined level by holding the forward pedal 36 in the predetermined depression position. The cruise mechanism will be described. The vehicle speed maintaining mechanism 361 includes a plurality of locking claws 362 and a single locking body 363 that are detachably engaged. The locking body 363 and the locking claw 362 are disposed so as to face each other so as to be able to contact and separate.

  As shown in FIG. 9, one end side of the clutch operation shaft 302 is protruded from the clutch housing 10 to the right side of the traveling machine body 2 in the traveling (forward) direction, and a side view L is formed at the protruding end portion of the clutch operation shaft 302. The middle of the locking link 364 is pivotally supported, one end of the locking link 364 is connected to the cruise lever 38 as a manual operation lever, and the other end of the locking link 364 is a protrusion-shaped engagement. The stop body 363 is formed integrally.

  As shown in FIG. 11, one end of an arcuate locking arm 365 in a side view is connected to the forward pedal shaft 315, and a plurality of locking claws 362 are continuously provided on the outer peripheral edge of the other end of the locking arm 365. Form. The direction in which the locking body 363 engages or disengages from the locking claw 362 is made substantially orthogonal to the tangent of the circumferential locus in which the locking arm 365 is rotated by the neutral holding spring 339. Engagement surfaces of the locking claw 362 and the locking body 363 are substantially orthogonal to the tangent line of the circular locus on which the locking arm 365 rotates. Therefore, when the forward pedal 36 is further depressed in the speed increasing direction, the locking body 363 is released in the direction of disengagement by the speed increasing side locking claw 362 adjacent to the locking claw 362 engaged with the locking body 363. The engagement between the locking claw 362 and the locking body 363 is released.

  That is, the shape of the locking claw 362 and the locking body 363 is such that the rotational moment that the locking arm 365 rotates by the neutral holding spring 339 acts as a force for engaging the locking body 363 with the locking claw 362. Form. The turning force (neutral holding spring 339 force) of the locking arm 365 for engaging the locking body 363 with the locking claw 362 is the force of the cutting holding spring 366 for holding the cruise lever 38 at the cutting position of the steering column 15. It becomes several times larger than (the force for releasing the locking body 363 from the locking claw 362) or several times larger than the operating force for the operator to move the cruise lever 38 from the vehicle speed maintaining position (entering position) to the cutting position. Thus, the latching arm 365 is configured to return to the initial position by the neutral holding spring 339.

  Therefore, the locking body 363 does not disengage from the locking claw 362 by the force that returns the cruise lever 38 to the cutting position by the cutting holding spring 366. Further, the locking body 363 does not disengage from the locking claw 362 by the pushing operation force that returns the cruise lever 38 from the vehicle speed maintenance position (entry position) to the cutting position. The rotational moment that the locking arm 365 is rotated by the neutral holding spring 339 acts as an engaging force on the locking claw 362 and the locking body 363, and the forward pedal 36 is returned from the depressed position to the initial position, so that the vehicle speed is substantially zero. The engagement of the locking claw 362 and the locking body 363 can be maintained by the force of the neutral holding spring 339 as an initial position return spring.

  Next, the vehicle speed maintaining operation (auto cruise operation) of the vehicle speed maintaining mechanism (auto cruise mechanism) 361 described above will be described with reference to FIGS. When the cruise lever 38 is pulled up against the cutting and holding spring 366 by the operator while the forward pedal 36 is depressed by the operator, the locking link 364 is moved from the imaginary line position to the solid line position as shown in FIG. It rotates around the clutch operating shaft 302 and the locking body 363 is engaged with the locking claw 362. Therefore, even if the operator removes his / her foot from the forward pedal 36, the forward pedal 36 is maintained in the depressed position, the front wheels 3 and the rear wheels 4 are driven at a substantially constant speed, and tilling work etc. while moving at a substantially constant speed. Is done. On the other hand, when the forward pedal 36 is depressed by the operator while the locking body 363 is engaged with the locking claw 362, the locking body 363 is released from the locking claw 362 and the cruise lever 38 and the engagement lever 362 are engaged. The stop link 364 is cut from the solid line position to the virtual line position (initial position) and returned by the holding spring 366, and the vehicle speed holding operation (auto cruise operation) that moves at a substantially constant speed is released.

  As is clear from the above description and FIGS. 9, 11, and 15, the engine 5 mounted on the traveling machine body 2 including the front wheel 3 and the rear wheel 4 as a traveling unit, and the power from the engine 5 are shifted. A hydraulic continuously variable transmission 25, a transmission case 11 for transmitting a shift output from the hydraulic continuously variable transmission 25 to the front wheels 3 and the rear wheels 4 via a sub transmission gear mechanism 59 as a shift output gear, and hydraulic pressure The forward pedal 36 and the reverse pedal 37 as the shift pedal, the forward pedal 36 and the reverse pedal 37 are connected to the trunnion arm 35 as the speed change operation unit of the variable continuously variable transmission 25 via the speed change link mechanism 300 as the speed change mechanism. In a work vehicle including a vehicle speed maintaining mechanism 361 that is held at the stepping operation position, the vehicle speed maintaining mechanism 361 includes a plurality of locking claws 362 that are detachably engaged. An arm 365 and a locking body 363 are provided, the locking arm 365 is connected to the forward pedal 36, and the locking body 363 is connected to a cruise lever 38 as a manual operation lever for maintaining the vehicle speed. The engagement between the locking claw 362 and the locking body 363 can be maintained by the biasing force of the neutral holding spring 339 as an initial position return spring for returning the pedal 37 from the depressed position to the initial position to make the vehicle speed substantially zero. Since it is configured as described above, it is locked using a force for returning the forward pedal 36 and the reverse pedal 37 from the depressed position to the initial position (a force for returning the shift output of the hydraulic continuously variable transmission 25 to zero). The engagement between the claw 362 and the locking body 363 can be continued. That is, since the operating force of the cruise lever 38 that the operator pushes (pulls) with one hand is smaller than the stepping force of the forward pedal 36 that the operator steps on with her foot, the force of the neutral holding spring 339 is larger than the operating force of the cruise lever 38 The engagement between the locking claw 362 and the locking body 363 is not easily released by the operation of the cruise lever 38. Therefore, it is possible to easily prevent the engagement between the locking claw 362 and the locking body 363 due to an erroneous operation of the cruise lever 38, and to improve driving operability. Even if the neutral holding spring 339 force is larger than the operating force of the cruise lever 38, the operator can easily step on the forward pedal 36 and the reverse pedal 37 with his / her foot, and the trunnion arm of the hydraulic continuously variable transmission 25. 35 can easily be returned to the output zero position.

  As apparent from the above description and FIG. 15, the locking link 364 is rotatably disposed on the traveling machine body 2, one end side of the locking link 364 is connected to the cruise lever 38, and the other end of the locking link 364 is connected. Since the locking body 363 is arranged on the side, the locking body 363 is integrally formed on the locking link 364 as compared to the conventional structure in which a plurality of locking claws 362 are formed on the locking link 364. Thus, the locking link 364 can be configured to be lightweight and simple. Therefore, since the locking body 363 can be easily supported at a position away from the locking claw 362 by a spring force smaller than the neutral holding spring 339 force, the cruise lever for engaging the locking body 363 with the locking claw 362 The operation force of 38 can be reduced.

  As apparent from the above description and FIGS. 14 and 15, one end of the locking arm 365 is connected to the forward pedal 36, and a plurality of locking claws 362 are formed on the other end of the locking arm 365. Since the locking body 363 of the locking link 364 and the locking claw 362 of the locking arm 365 are arranged to face each other, the strength of the plurality of locking claws 362 formed on the locking arm 365 is simplified. Can be improved. That is, even if the locking arm 365 is formed with high rigidity so that the strength of the locking claw 362 is improved, the locking arm 365 can be made lighter than the forward pedal 36. Compared to the conventional structure in which the pawl 362 is formed, the highly rigid locking arm 365 and the locking pawl 362 can be easily formed without impairing the speed change function of the forward pedal 36.

  As is clear from the above description and FIGS. 11 and 14, the shift pedal is composed of the forward pedal 36 and the reverse pedal 37, and the forward pedal 36 and the reverse pedal 37 are moved from the depressed position by the spring force of one neutral holding spring 339. Since the trunnion arm 35 of the hydraulic continuously variable transmission 25 is returned to the initial position and the trunnion arm 35 of the hydraulic continuously variable transmission 25 is returned to the output zero position. The position can be set easily. In other words, the output zero adjustment unit that maintains the trunnion arm 35 at the output zero position by the neutral holding spring 339 and the initial position adjustment unit that returns the forward pedal and the reverse pedal to the initial position by the neutral holding spring 339 also serve as adjustment parts. The neutral adjustment body 340 as an output zero adjustment part and an initial position adjustment part etc. can be comprised easily. Therefore, the assembly workability and maintenance workability of the forward pedal 36 and the reverse pedal 37 can be improved.

  As is clear from the above description and FIGS. 12 and 14, the forward pedal 36 and the reverse pedal 37 are rotated to the pedal unit frame 309 as the pedal frame of the traveling machine body 2 via the forward pedal shaft 315 and the reverse pedal shaft 316. As a restraining mechanism that supports each of the forward pedal 36 and the reverse pedal 37 and the trunnion arm 35 of the continuously variable transmission 25 to prevent simultaneous depression of the forward pedal 36 and the reverse pedal 37. The forward pedal 36 and the reverse pedal 37 are connected via the pressing arm 326 and the swing arm 329, and the respective stepping operation directions of the forward pedal 36 and the reverse pedal 37 are substantially matched. Therefore, the operator can step on the forward pedal 36 and the reverse pedal 37 separately on the front side of the foot. For example, the forward pedal 36 and the reverse pedal 37 can be disposed close to the front side of the right foot of the operator seated on the control seat 17 of the traveling machine body 2, and the operator moves the right foot to the left and right to move the forward pedal 36 or the reverse pedal 37. Can be stepped on. Therefore, compared with the conventional structure in which the operator steps on the forward pedal 36 on the front side of the foot and the reverse pedal 37 on the rear side of the foot, the function of preventing the simultaneous depression operation of the forward pedal 36 and the reverse pedal 37 is not impaired. The stepping operability of 37 can be improved.

It is the whole tractor side view. It is a top view of the traveling body of a tractor. It is an enlarged plan view of the latter half part of the traveling machine body. It is an enlarged plan view of the peripheral part of the step frame of the traveling machine body. It is a perspective view of the pedal etc. which an operator operates. It is a section side view of a mission case and a mission front case. It is front explanatory drawing of a mission front case. It is a hydraulic circuit diagram. It is side explanatory drawing, such as a forward pedal, a reverse pedal, and a speed change link mechanism. It is side surface explanatory drawing, such as a forward pedal and a reverse pedal. FIG. 10 is an enlarged side view of the transmission link mechanism and the like of FIG. 9. It is expansion side explanatory drawing, such as a forward pedal and a reverse pedal of FIG. It is plane explanatory drawings, such as a forward pedal and a reverse pedal. FIG. 14 is an enlarged plan view of the forward pedal and the reverse pedal of FIG. 13. It is a side view explaining operation of a cruise lever or the like.

Explanation of symbols

2 traveling body 3 front wheel (traveling part)
4 Rear wheels (traveling part)
5 Engine 11 Mission case 25 Hydraulic continuously variable transmission 35 Trunnion arm (shift operation section)
36 Forward pedal
37 Reverse pedal (shift pedal)
38 Cruise lever (manual operation lever)
59 Sub-transmission gear mechanism (shift output gear)
300 Transmission link mechanism (transmission mechanism)
309 Pedal unit frame (pedal frame)
315 Forward pedal shaft 316 Reverse pedal shaft 326 Press arm (checking mechanism)
329 Swing arm (checking mechanism)
339 Neutral holding spring (initial position return spring)
361 Vehicle speed maintaining mechanism 362 Locking claw 363 Locking body 364 Locking link 365 Locking arm

Claims (5)

An engine mounted on a traveling machine body having a traveling unit, a hydraulic continuously variable transmission that shifts power from the engine, and a shift from the hydraulic continuously variable transmission to the traveling unit via a transmission output gear A work vehicle comprising: a transmission case for transmitting an output; a shift pedal coupled to a shift operation portion of the hydraulic continuously variable transmission via a shift mechanism; and a vehicle speed maintaining mechanism for holding the shift pedal in a stepping operation position. In
The vehicle speed maintaining mechanism includes a locking arm having a plurality of locking claws that are detachably engaged with each other, and a locking body. The vehicle speed maintaining mechanism is configured to connect the locking arm to the shift pedal and perform manual operation for maintaining the vehicle speed. Connecting the locking body to the lever;
The engagement between the locking claw and the locking body can be maintained by the biasing force of the initial position return spring for returning the speed change pedal from the depressed position to the initial position to make the vehicle speed substantially zero. A working vehicle characterized by that.   A locking link is rotatably disposed on the traveling machine body, one end side of the locking link is connected to the manual operation lever, and the locking body is disposed on the other end side of the locking link. The work vehicle according to claim 1.   One end side of a locking arm is connected to the shift pedal, a plurality of locking claws are formed on the other end side of the locking arm, the locking body of the locking link, and the locking arm The work vehicle according to claim 2, wherein the engaging claws are arranged to face each other.   The shift pedal includes a forward pedal and a reverse pedal, and the forward pedal and the reverse pedal are returned from the depressed position to the initial position by a spring force of one initial position return spring, and the hydraulic continuously variable transmission is The work vehicle according to claim 3, wherein the speed change operation unit is configured to be returned to the output zero position. The forward pedal and the reverse pedal are pivotally supported on a pedal frame of the traveling machine body via a forward pedal shaft and a reverse pedal shaft, respectively, and either one of the forward pedal or the reverse pedal and the continuously variable transmission. The forward pedal and the reverse pedal are connected via a check mechanism that connects a shift operation unit of the machine and prevents simultaneous operation of the forward pedal and the reverse pedal, and the forward pedal and the reverse pedal are respectively connected. 5. The work vehicle according to claim 4, wherein the stepping operation direction is substantially matched.

Images