JP2006129776A - Structure for operating lever of tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent careless lowering of an implement lifted to the upper limit even when friction holding power applied to a position control lever is set at a small value in a structure for operating a lever of a tractor composed so that a position control valve controlling the operation of a hydraulic cylinder for lifting and lowering the implement is artificially regulated and operated with the position control lever. <P>SOLUTION: This structure for operating the lever of the tractor is equipped with a lifting locking mechanism 24 for preventing the movement of the position control lever 20 operated to the upper limit position in the lowering direction. The lifting locking mechanism 24 is obtained by composing a lever engaging member 25 arranged on the lowering operation side of the position control lever 20 operated to the upper limit position so as to freely rotate around the shaft center in the lever operating direction. Thereby, the lifting locking mechanism 24 in which the lever engaging member 25 can be changed over to emerge and retreat from a lever operating route suitably functions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tractor lever operating structure in which a position control valve for operating and controlling a hydraulic cylinder for raising and lowering a work device is manually adjusted by a position control lever.

In general, in a so-called manual position control structure in which the position control valve is manually adjusted by the position control lever, the position control lever can be operated arbitrarily so that the connected working device can be adjusted and held at an arbitrary height. It is comprised so that friction may be hold | maintained at a position (for example, refer patent document 1).
JP 2003-333902 A

  In a tractor that performs manual position control, the tractor main body will rise and fall or tilt forward and backward due to softness and undulations in the field, and the ground clearance of the work equipment connected to the rear of the machine will change. In an operation where it is desired to keep the ground height constant, the driver frequently adjusts the position control lever according to the change in the attitude of the aircraft. When the position control lever is frequently adjusted as described above, it is desirable to reduce the friction holding force applied to the position control lever in order to perform the lever operation easily and easily.

  However, if the frictional holding force applied to the position control lever is reduced, the position control lever moves in the downward direction due to its own weight or inertia when the work equipment is raised to the upper limit and travels on the road. There is a risk, and there is a limit to reducing the frictional holding force applied to the position control lever.

  The present invention has been made paying attention to such points, and even if the frictional holding force applied to the position control lever is set to a small value, the working device that has been raised to the upper limit may be inadvertently lowered. The purpose is to avoid.

According to a first aspect of the present invention, there is provided a lever operating structure for a tractor configured to artificially adjust a position control valve for operating and controlling a hydraulic cylinder for raising and lowering a working device by a position control lever,
A lift lock mechanism is provided that prevents the position control lever operated to the upper limit position or the vicinity thereof from moving in the lowering direction.

  According to the above configuration, in normal work, the work device can be moved up and down to a height corresponding to the lever position by arbitrarily adjusting the position control lever, and at the time of non-working travel such as traveling on the road Is raised to the upper limit. In this case, after the position control lever is operated to the upper limit position or the vicinity thereof, the position control lever is prevented from moving to the lowering side by using the ascending lock mechanism. As a result, it is possible to prevent the position control lever from moving to the lowering side and dropping the work device due to vibrations during running or airframe shaking.

  Therefore, according to the first aspect of the present invention, the frictional holding force for holding the position control lever at an arbitrary operation position is set to be small so that the lever can be operated easily and easily, but the operation is raised to the upper limit. The device can be moved and moved without inadvertent lowering.

According to a second invention, in the first invention,
The ascending lock mechanism is configured such that a lever locking member disposed on the lowering operation side of the position control lever operated to the upper limit position or the vicinity thereof can be switched to and from the lever operation path.

  According to the above configuration, by retracting the lever locking member with respect to the lever operation path, the position control lever can be arbitrarily moved in the entire operation range, and the lever locking member is moved with respect to the lever operation path. By projecting, the position control lever operated to the upper limit position or the vicinity thereof can be locked and held in the downward direction so as not to move, and the first invention can be suitably implemented.

According to a third invention, in the second invention,
The lever locking member is configured to be rotatable around an axis along the lever operating direction.

  According to the above configuration, the lever locking member that locks the position control lever does not rotate even when an external force is applied to the lowering side, and the switching operation is easy, but the position control lever is moved to the upper limit position. Or it can hold | maintain reliably in the vicinity.

According to a fourth invention, in the second or third invention,
Friction resistance means for imparting resistance to the switching operation of the lever locking member is provided.

  According to the above configuration, the lever locking member itself is not arbitrarily switched due to vibration or airframe fluctuation, and the lever locking member is arbitrarily switched to the locking action state during normal work, thereby obstructing the lever operation. The lever locking portion can be properly functioned without switching from the lever locking operation state to the release state without permission.

  FIG. 1 and FIG. 2 respectively show an entire side surface and an entire plane of a tractor that is mainly used for agricultural purposes and has a lever operation structure according to the present invention. This tractor includes a front wheel 1 that is steered and a rear wheel 2 that is a propulsion wheel, and an engine 3 is mounted laterally at the front of the body, and a three-point link mechanism 4 for connecting a work device to the rear of the body. In addition, a pair of left and right lift arms 5 that drive this up and down are provided, and a driver seat 6 is disposed between the left and right rear wheels 2.

  FIG. 3 shows a hydraulic circuit for hydraulically driving the lift arm 5. The lift arm 5 is driven by a single-acting hydraulic cylinder 7. The lift arm 5 is driven upward by the hydraulic cylinder 7 being extended by pressure oil supply, and the hydraulic cylinder 7 is shortened by oil discharge. By doing so, the lift arm 5 is configured to descend by its own weight. The hydraulic cylinder 7 is controlled by a position control valve 8.

  The position control valve 8 includes a main spool 11, a lowering valve 12, a relief valve 13, an unloading valve 14, and the like, and the hydraulic cylinder 7 and the cylinder port c of the position control valve 8 are connected to a drop adjusting valve 15. Connected through. The main spool 11 is urged in the downward direction D by the spring 16 and the lowering valve 12 urged to the lowering prevention position that prevents the discharge of the pressure oil from the cylinder port c follows the main spool 11 in one-sided manner. It is configured to be displaced.

  A balance link 17 is swingably connected to the end of the main spool 11, and both ends of the balance link 17 are fed from an adjustment arm 18 a extending from a position adjustment shaft 18 and a feedback extending from a feedback shaft 19. The arms 19a are engaged with each other. Further, the position adjusting shaft 18 and the position control lever 20 arranged on the right side of the driver's seat 6 so as to swing back and forth are linked to each other, and the feedback shaft 19 and the lift arm 5 are linked to each other.

  The position control valve 8 configured as described above operates as follows.

  For example, when the position control lever 20 is operated backward from the neutral state shown in FIG. 3, the position adjusting shaft 18 is rotated counterclockwise in FIG. 3 in conjunction with this operation, and the balance link 17 is connected to the feedback arm 19a. The main spool 11 is shifted in the upward direction U against the spring 16, the pressure oil is sent out from the cylinder port c, supplied to the hydraulic cylinder, and lifted. The arm 5 is driven up. In this case, the lowering valve 12 is biased and held at the lowering prevention position.

  When the lift arm 5 is displaced upward, this displacement is fed back to the feedback shaft 19 as a counterclockwise rotation in FIG. 3, and the balance link 17 is moved downward in the direction D around the engagement point with the adjusting arm 18a. As a result, the main spool 11 is shifted in the descending direction D. Then, when the feedback shaft 19 is rotated to a predetermined rotation position corresponding to the rotation operation position of the position adjusting shaft 18, the main spool 11 is returned to the neutral position and the ascending operation is stopped.

  Further, when the position control lever 20 is operated forward from the neutral state shown in FIG. 3, the position adjusting shaft 18 is rotated in the clockwise direction in FIG. 3, and the balance link 17 is connected to the feedback arm 19a. The main spool 11 is shifted in the descending direction D, the descending valve 12 that contacts and follows this is switched to the open position, and the cylinder port c descends. By communicating with the tank via the valve 12, the oil from the hydraulic cylinder 7 can be drained, and the lift arm 5 is lowered by its own weight.

  When the lift arm 5 is displaced downward, this displacement is fed back to the feedback shaft 19 as a clockwise rotation in FIG. 3, and the balance link 17 swings in the upward direction U about the engagement point with the adjustment arm 18a. The main spool 11 is shifted in the upward direction U. When the feedback shaft 19 is rotated to a predetermined rotation position corresponding to the rotation operation position of the position adjustment shaft 18, the main spool 11 is returned to the neutral position and the lowering operation is stopped.

  That is, when the position control lever 20 is operated, the lift arm 5 moves up and down to a height corresponding to the operation position and automatically stops. When the position control lever 20 is operated to the rearmost position, the lift arm 5 is set to a position slightly lower than the mechanical lift limit of the lift arm itself, and the position control lever 20 is operated to the foremost position. In this state, the position control valve 8 is maintained in the lowered state without being returned to neutral regardless of the feedback operation accompanying the downward displacement of the lift arm 5, and the lift arm 5 is lowered to its mechanical lower limit. It is set so as to provide a possible state, a so-called floating state.

  The position control lever 20 is provided through a long operation hole 22 in the front and rear formed in the lever guide 21 on the side of the driver's seat, and a swing holding point P is provided with a friction holding mechanism 23 using a disc spring. The position control lever 20 can be held at an arbitrary operation position.

  Further, as shown in FIGS. 4 to 7, the lift lock mechanism 24 that prevents the position control lever 20 operated to the upper limit position of the operation hole 22 or the vicinity thereof from moving forward (downward direction) is a lever guide. 21 is equipped. The upper limit position of the position control lever 20 is set by a contact restriction with a stopper 37 attached to the lever guide 21, and this stopper 37 is engaged with a part of the operation hole 22 to prevent rotation. It is fixed with a bolt 38.

  The ascending lock mechanism 24 is configured by supporting a lock fitting 25 formed by bending a round bar in an inverted L shape around a fulcrum x heading in the front-rear direction via a fulcrum bracket 26 so that it can be turned left and right. . The bracket 26 is formed of a spring plate material bent so as to embrace the fulcrum shaft portion 25a of the lock fitting 25, penetrates from above the slit 27 of the lever guide 21, and is fixed to the lower surface of the guide. The support bracket 28 is connected with bolts 29. Then, by adjusting the tightening condition of the bolt 29, the lock fitting 25 is not turned over to the left and right, and an appropriate frictional resistance that can be easily turned over is given.

  The lock fitting 25 of the ascending lock mechanism 24 is normally rotated to the left and frictionally held in a position retracted from the operation hole 22, and the position control lever 20 can be arbitrarily operated in the entire operation range. In addition, after the position control lever 20 is operated to the upper limit position, the position of the position control lever 20 is moved forward (downward) from the upper limit position by turning the lock fitting 25 to the right and turning it over to intersect the lever operation path. When the lift arm 5 is raised to the upper limit and the working device connected to the three-point link mechanism 4 is moved up and moved, the position control lever 20 is caused by the vibration and shaking of the airframe. Can be prevented from moving in the downward direction by its own weight or inertia.

[Other Examples]
The raising lock mechanism 24 can be implemented in various forms, and some other examples will be exemplified below.

  (1) As shown in FIGS. 8 and 9, a lever locking member 25 formed by bending a metal plate material into a U shape is attached to a U-shaped bracket 31 welded and fixed to the upper surface of the lever guide 21 via a fulcrum bolt 32. In addition to being pivotally connected around the fulcrum x in the front-rear direction so that it can be turned to the left and right, and by adjusting the tightening of the nut 33 attached to the fulcrum bolt 32, the lever locking member 25 is moderately turned over. The ascending lock mechanism 24 can also be configured to provide frictional resistance.

  (2) As shown in FIGS. 10 and 11, a hook-shaped locking bracket 34 is pivotally connected to the side surface of the position control lever 20 so as to be able to swing by its own weight around the lateral fulcrum y, and near the upper limit of the lever guide 21. When the receiving bracket 35 is provided and the position control lever 20 is operated to the upper limit position or in the vicinity thereof, the slope s formed at the end of the locking bracket 34 comes into contact with the receiving bracket 35 and the locking bracket 34 gets on. The ascending lock mechanism 24 that is swung up and is automatically engaged with the locking fitting 35 to prevent the position control lever 20 from moving forward (in the descending direction) can be configured.

  (3) For simplicity, as shown in FIGS. 12 and 13, the lever locking member 25 made of a bar can be rotated around the fulcrum in the vertical direction by a connecting bolt 36 to the lever guide 21 with an appropriate rotational resistance. Tightened and installed, the position control lever 20 at the upper limit position is prevented from moving forward (downward direction) by the rotational resistance of the lever locking member 25 that is rotated to a posture crossing the lever operation path. The ascending lock mechanism 24 can also be configured.

  (4) As shown in FIG. 14, the position control lever 20 is configured by a plate lever that can be elastically deformed to the left and right, and the engaging portion that directly holds and holds the position control lever 20 at the upper limit position of the operation hole 22. The ascending lock mechanism 24 can also be configured by connecting 22a.

Overall side view of tractor Overall view of the tractor Hydraulic circuit diagram for position control Side view of position adjustment operation section Top view of the position adjustment operation section Vertical front view of the position adjustment operation section Disassembled perspective view of the position adjustment operation unit Side view of position adjustment operation part in other embodiment (1) Longitudinal front view of the position adjusting operation unit in another embodiment (1) Side view of position adjustment operation part in other embodiment (2) The top view of the position adjustment operation part in another Example (2) Side view of position adjustment operation part in other embodiment (3) The top view of the position adjustment operation part in another Example (3) The top view of the position adjustment operation part in another Example (4)

Explanation of symbols

7 Hydraulic cylinder 8 Position control valve 20 Position control lever 24 Upper limit lock mechanism 25 Lever locking member x fulcrum

Claims (4)

A tractor lever operating structure in which a position control valve for operating and controlling a hydraulic cylinder for raising and lowering a work device is configured to be manually adjusted by a position control lever,
A tractor lever operating structure comprising a lift lock mechanism for preventing the position control lever operated to an upper limit position or the vicinity thereof from moving in a downward direction.   2. The lift lock mechanism is configured such that a lever locking member provided on a lowering operation side of the position control lever operated to an upper limit position or the vicinity thereof is configured to be able to be switched back and forth with respect to a lever operation path. The described tractor lever operating structure.   3. The lever operating structure for a tractor according to claim 2, wherein the lever locking member is configured to be rotatable around an axis along the lever operating direction.   4. The lever operating structure for a tractor according to claim 2, further comprising friction resistance means for applying resistance to the switching operation of the lever locking member.

Images