JPH0446492Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a position control device for a tractor, and the present invention is designed to release residual pressure generated from a control valve during position control by the downward movement of a position lever. This is what I did.

(Prior art) A position control device that controls the position of a hydraulic system for raising and lowering a tractor's work equipment is controlled in conjunction with a position lever that is rotatable around a support shaft when it is operated in the raising or lowering direction. When the valve is activated and the hydraulic system is operated to the set position of the position lever, the control valve is configured to return to neutral via the feedback mechanism.

(Problems to be Solved by the Invention) However, since the control valve operating system is mechanically constructed, there is always some backlash or play. Therefore, conventionally, when the position lever is slowly operated to the up position, the control valve operates in the upward direction, but even if the hydraulic system operates to the set position, the control valve does not fully operate due to backlash or play. In some cases, the country did not return to neutrality. If this happens, the residual pressure generated from the control valve will act on the hydraulic system and other hydraulic equipment, reducing their lifespan.

The present invention was provided for the purpose of solving such conventional problems.

(Means for Solving the Problems) As a means for solving the above-mentioned problems, the present invention provides a hydraulic system for lifting and lowering work equipment, which is operated by a position lever that is rotatable around a support shaft. In a tractor position control device that is equipped with a control valve so that the lever returns to neutral when the position lever is operated to the set position, a rotary fixed plate that engages with the position lever through play is rotated around a support shaft. The position lever is supported by a spring that applies frictional resistance to the rotary fixed plate so that the rotary fixed plate rotates around the support shaft when the position lever is operated and is fixed when the operation is stopped. A spring is provided between the position lever and the rotating fixed plate to bias the position lever in the downward direction.

(Function) When the position lever 10 is operated in the upward direction and then released, the rotation fixed plate 34 is stopped by the spring 37, so the spring 41 between the rotation fixed plate 34 and the position lever 10 Since the position lever 10 is then returned in the downward direction by the amount of play, the control valve 23 can be easily returned to neutral.

(Embodiment) Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. In FIG. 3, 1 is a tractor body; 2 is a tractor body;
PTO axis, 3 is the rear axle case. 4 is a hydraulic device for lifting and lowering the working machine, and has a lift arm 6 that is rotatable around an arm shaft 5. 7 is the rear wheel fender, 8 is the fuel tank, and 9 is the driver's seat. 10 is a position lever, and 11 is a draft lever, which are guided around a support shaft 13 along a guide plate 12 provided inside one rear wheel fender 7.

Position lever 10 and draft lever 11
As shown in FIGS. 1 and 2, the boss portion 14,
It is fitted onto the support shaft 13 via the support shaft 15, and is interlocked and connected to the operation shafts 20 and 21 via interlocking links 16 and 17 and levers 18 and 19. operating shaft 20,
21 is inserted and supported in a side wall portion of the hydraulic device 4 and a spacer 22 attached thereto so as to be concentric between the inside and the outside, and is interlocked with the operating portion of the control valve 23 inside the hydraulic device 4, respectively. A fixed support plate 26 is provided on the spacer 22 via a collar 24 and bolts 25,
The outer end of the operating shaft 20 is inserted into and supported by this. Each lever 18, 19 is sandwiched between a spacing plate 27 and a friction plate 28, and is urged toward the spacer 22 by a spring 29 interposed between it and the support plate 26.
A predetermined frictional resistance is applied.

It is fixed to a mounting plate 30 at the outer end of the support shaft 13, and the mounting plate 30 is attached to the support plate 26 with a collar 31 and bolts 32 with the support shaft 13 inserted into the support plate 26. A mounting plate 3 is attached to the support shaft 13.
A collar 33 is fitted between the collar 33 and the support plate 26, and a rotating fixing plate 34, a pair of friction plates 35 and a receiving plate 36 sandwiching the rotation fixing plate 34 are fitted into the collar 33, and these are attached to the mounting plate. A spring 37 interposed between the support plate 30 and the support plate 36 urges the support plate 26 side so as to generate a predetermined frictional resistance.
The rotation fixing plate 34 is provided with a spring pin 38 and has an engagement hole 39 formed therein. Engagement hole 3
9 is an engagement pin 4 provided on the position lever 10.
0 is engaged, and a spring 41 that biases the position lever 10 in the downward direction is hung between the engagement pin 40 and the spring hook pin 38. The engagement hole 39 has a slightly larger diameter than the engagement pin 40, as shown in FIG. After operating the position lever 10 in the upward direction, if the operating force is released, the position lever 10 is configured to return to the downward direction by the amount of play due to the spring 41.

The PTO shaft 2 is supported by a PTO transmission case 42 at the rear end of the tractor body 1. In particular, the PTO shaft 2 is connected to the transmission case 4 through a bearing 43 as shown in FIG.
2 is supported by the rear wall boss portion 44 of the bearing 4
An oil seal 45 is fitted on the rear side of 3. The oil seal 45 is held down from the rear by a dust seal support 46. The dust seal support body 46 can be attached to and detached from the boss portion 44 by bolts 47, and a dust seal 48 is fitted thereto. The dust seal 48 is for protecting the oil seal 45 during wet field work, etc., and if it is damaged, it can be replaced very easily by removing the dust seal support 46. In addition, seals 45, 4 are installed on the outer periphery of the PTO shaft 2.
A sleeve 49 is tightly fitted into a portion corresponding to 8.

In the above configuration, when controlling the position of the hydraulic device 4, the position lever 10 is moved to the support shaft 13.
All you have to do is move it up and down in the rotation direction, and the basic operation is almost the same as the conventional one.

Now, the operation when the position lever 10 at the lower position A is operated to the upper position B will be explained. When the position lever 10 is operated in the upward direction (arrow a), it rotates in the upward direction around the axis of the operating shaft 20 via the link 16 and the lever 18, and the internal control valve 23 controls the hydraulic system 4. It works to raise the lift arm 6. On the other hand, when the lift arm 6 rotates in the upward direction, the control valve 23 operates to return to neutral via a feedback mechanism (not shown).

In such control, position lever 1
0 to the upper limit position (imaginary line B' in Fig. 1), the engagement pin 40 engages with the left end side of the engagement hole 39 as shown in Fig. 5. , the rotation fixed plate 34 is rotated in the upward direction (arrow a) while resisting frictional resistance by the spring 37. Then, when the position lever 10 is released at the upper limit position,
Since the rotation fixing plate 34 is fixed due to the frictional resistance of the spring 37, the position lever 10 is moved toward the engagement pin 40 by the force of the spring 41 in the direction of arrow b.
The position lever 10 is pulled back in the downward direction (arrow c) within the range of play between the engagement hole 39 and the engagement hole 39, and the position lever 10 stops at the solid line position in FIG. Therefore, since the control valve 23 side acts in the downward direction only slightly through the link 16, lever 18, and operating shaft 20, even if there is backlash or play in the operating system, the neutral return can be smoothly performed by the feedback mechanism. This prevents the generation of residual pressure as in the conventional case.

(Effects of the invention) According to the invention, after the position lever is operated in the upward direction to a predetermined position, the spring moves the position lever downward by the amount of play between the rotating fixed plate and the position lever. Therefore, the neutral return operation of the control valve can be ensured, and the conventional generation of residual pressure and the problems associated with this can be solved.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional side view of the main parts showing an embodiment of the present invention, Fig. 2 is a cross-sectional rear view of the main parts, Fig. 3 is a cross-sectional side view of the rear of the tractor, and Fig. 4 is the PTO of the tractor.
A cross-sectional view of the shaft seal portion and FIG. 5 are operation explanatory views. 4...Hydraulic system, 10...Position lever,
13... Support shaft, 23... Control valve, 34... Rotation fixing plate, 37, 41... Spring, 39... Engagement hole, 4
0... Engagement pin.

Claims (1)

[Scope of utility model registration request] A tractor position that is operated by a position lever that is rotatable around a support shaft and equipped with a control valve that returns to neutral when the hydraulic system for raising and lowering the work equipment operates to the position set by the position lever. In the control device, a rotating fixed plate that engages with a position lever through a play space is supported around a support shaft,
A spring that applies frictional resistance is provided to the rotational fixation plate so that the rotation fixation plate rotates around the support shaft when the position lever is operated and is fixed when the operation is stopped, and the rotation fixation plate is fixed to the position lever. A position control device for a tractor, characterized in that a spring is provided between a plate and a spring that biases a position lever in a downward direction.