JPS608647Y2 - Agricultural tractor resistance control device - Google Patents

Description

[Detailed description of the invention] This invention tows a working machine behind an agricultural tractor via a three-point link mechanism such as a top link and a lower link, and raises and lowers the working machine using a hydraulic lift controlled by a hydraulic switching valve. At the same time, one side of a leaf spring formed in a substantially U-shape in a vertical direction is attached to the housing of the hydraulic lift, and the other side of the leaf spring is connected to the middle of the top link hinge that fixes the top link. This relates to a control device.

Conventionally, the traction resistance of the rotary work machine acts as this lifting force, and changes in the lifting force of the rotary work machine are detected via the top link, and the rotary work machine is raised and lowered to reduce this traction resistance. There was a technique to keep it almost constant.

However, the adjustment operation for keeping the traction force within a certain range in response to the soft and hard condition of the cultivated soil is cumbersome, and it is difficult to use it properly in fields and wet fields, for example.

Therefore, a plurality of mounting holes connecting the top links were formed on the top link hinge to adjust the force exerted by the top link on the hinge. When the work equipment lands, the action fulcrum is located between the top link extension line and the leaf spring, which may displace the top link hinge in the opposite direction to the direction in which traction resistance is detected. On the other hand, it is difficult to always properly detect the top link hinge by compressing the leaf spring by always positioning the leaf spring on the side of the top link extension line.

In particular, if the support height of the work equipment changes due to a change in the work position of the work equipment relative to the tractor, the connection angle of the top link to the top link hinge will shift, and the top link and plate will be attached to both ends of the hinge around the action fulcrum. There is a problem in that the springs are connected, and it is difficult to limit the detection operation of the top link hinge to only one direction in which the leaf spring is compressed.

The present invention solves the above-mentioned conventional drawbacks, and involves towing a working machine behind an agricultural tractor via a top link and a lower link, and raising and lowering the working machine using a hydraulic lift controlled by a hydraulic switching valve. A structure in which a top link hinge is fixed to the lift housing of the hydraulic lift via a plate spring formed in a substantially U-shape in a vertical direction, and a bent rear side part of the plate spring is connected to the middle of the hinge. A plurality of mounting holes for connecting the top links are provided in the top link hinge in multiple stages, and a pair of protrusions are formed on the upper and lower ends of the bracket that fixes the bent front side of the leaf spring, One end of the top link hinge is selectively supported by one of the protrusions through an action fulcrum so that the bent rear side of the spring is aligned with the top link hinge. The leaf spring is always positioned on the extension line of the top link when the work machine lands with respect to the action fulcrum, and the work machine does not touch the ground when the work machine lands on the tractor in the field or on the tilled soil in the field. Even if this support height changes and the support angle of the top link changes, by changing the action fulcrum of the top link hinge above and below the leaf spring, the leaf spring is always compressed by the hinge. The top link can be connected to the hinge close to the action fulcrum, and when the top link is tilted forward due to the high support height of the work equipment relative to the tractor as in the field, the action fulcrum is provided above the leaf spring. On the other hand, when the support height of the work equipment is low with respect to the tractor, such as in a field, and the top link is tilted backwards, an action fulcrum is provided below the leaf spring, which acts as a pushing force for the top link to pull the work equipment. Due to the resistance, the top link hinge and the leaf spring can always be displaced only in the same direction, and the top link can be connected safely and properly even near the working fulcrum of the top link hinge compared to the prior art, and unlike the prior art, the top link can be properly connected. Disadvantages such as restrictions on the connection position of the top link with respect to the action fulcrum due to changes in the connection angle of the top link with respect to the top link hinge can be easily resolved, and the top link hinge and leaf spring are displaced in only one direction. Accordingly, it is an object of the present invention to provide a resistance control device for an agricultural tractor that allows a resistance detection reference value using a leaf spring to be easily set.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 is a schematic side view of an agricultural tractor. In the figure, 1 is the machine base on which the engine part 2 is mounted, 3 is the clutch part installed behind the engine part 2, and 4 is the transmission part installed behind the clutch part 3. , 5 is a gate projecting to the rear of the mission section 4.
6 is a steering wheel, 7 is a seat, 8 is a rear wheel, and 9 is a rear axle.

Reference numeral 10 denotes a rotary working machine, which is attached to the rear of the tractor A by a three-point link mechanism of a top link 11 and a lower link 12. It is configured to rotate the rotary 14.

Furthermore, the above-mentioned rotary work machine 10 is constructed such that it can be freely raised and lowered by a hydraulic lift 15 fixed on the transmission section 4 via a lift arm 16, 16 and a lift rod 17.

The hydraulic lift 15, as shown in FIGS. 2 and 3,
A lifting shaft 19 is provided at the upper right side of the lift housing 18 , and a piston 22 is axially movably connected to a lift crank 20 fitted to the center of the shaft 19 via a piston rod 21 .
A hydraulic switching valve 23 is provided on the left side of the switching valve 23, and a port 23a on one side of the switching valve 23 is communicated with a cylinder chamber 26 on one side across the piston 22 via a high pressure oil passage 24b. The port 23b on the other side is communicated with the lift crank chamber 27 on the other side across the piston 22 via the communication hole 24c and the drain circuit 26, and the position control lever 28 for manual operation is operated to connect the lift crank chamber 27 via the cam 29. When the spool 30 is driven, the piston 22 and the piston rod 21 are axially moved, and the lifting shaft 19 is rotated via the lift crank 20.
6 is configured to swing.

31 is a cylinder head screwed to one side of the lift housing 18, 32 is a bracket screwed to the other side of the lift housing 18, and the bracket 32 has an inverted U-shaped leaf spring 33 bent therein. The front side portion 33a is attached via the member 35 with set bolts 34, 34, and the hinge 36 is attached with set bolts 37, 37 so that the stress of the top link hinge 36 acts on the bent rear side portion 33b of the leaf spring 33. provided through the bracket 3
2 and the top link hinge 36, one end 33b of an inverted U-shaped leaf spring 33 is fixed to the middle of the hinge 36.

The lower end of the top link hinge 36 is connected to the bracket 32
The top link hinge 36 is pivotally supported on the protruding portion 32a of the top link hinge 36 via a hinge pin 38 which serves as an action fulcrum, and a plurality of mounting holes 39, 39... are bored in multiple stages along the vertical direction on the rear side of the top link hinge 36. The base end of the top link 11 is fixed to the top link hinge 36.

Here, the leaf spring 33 has a folded shape with an expansion curved portion 33c, and is vertically attached between the bracket 32 and the top link hinge 36 of the hydraulic lift 15.

Moreover, a link mechanism 41 is connected to a pin 40 provided at the upper end of the top link hinge 36.

This link mechanism 41 operates when a resistance force greater than a preset force is applied to the leaf spring 33 by the leaf spring 33.
The first hydraulic lift 15 connected to the pin 40 drives the hydraulic lift 15 to automatically raise and raise the working machine 10.
a feedback lever 42; first and second swing plates 45, 45 that are swingably fitted to the lifting shaft 19 via a toothed plywood 43 (see FIG. 4);
A second feedback lever 47 is attached to the upper end of these swing plates 45 and 45 via a pin 46, and a plate 48 is stretched downward from the tip of the lever 47.
It consists of a shaft 49 provided on the plate 48, a cam 50 for moving and operating the spool 30 of the switching valve 23 fixed to the shaft 49, and a restoring spring 51.

The first feedback lever 42 includes a flat plate 42a pivotally supported by a pin 40, a threaded rod 42b fixed to the flat plate 42a, and a threaded rod 42d connected to the threaded rod 42b via an adjustment nut 42c. A dogleg-shaped flat plate 42e fixed to this threaded rod 42d is connected to the swing plate 44, 45 via a locking pin 52.

On the other hand, the second feedback lever 47 includes a flat plate 47a pivotally supported by a pin 46, and a threaded rod 4 fixed to the flat plate 47a.
7b, a dogleg-shaped threaded rod 47d connected to the threaded rod 47b via an adjustment nut 47c, and this threaded rod 4
7d and a flat plate 47e fixed thereto, and connected to the plate 48 mentioned above via a pin 53.

The spring 51 is stretched between retaining plates 54 and 55, one retaining plate 54 being pivotally connected to the pin 46, and the other retaining plate 55 having a plate shape with a guide plate 56 fixed at the tip. It is installed upright on the arm 57 of.

Furthermore, a leaf spring 33 at the upper end of the bracket 32
A pair of guide rods 59.59 integrally formed with the set bolts 58.58 of the bracket 32 are arranged in parallel on the left and right sides of the bracket 32, and are configured to guide the swinging of the top link hinge 36. 59.59 is inserted into the hole of the top link hinge 36.

Incidentally, a variable throttle valve 60 is provided in front of the connection port 24a in the high-pressure oil passage 24b to control the flow rate.

Further, 61 is a safety valve that adjusts the pressure of excess oil flowing through the drain circuit 26, and 62 is a branch port that communicates with a part of the high-pressure oil passage 24b, and the branch port 62 is closed with a plug.

Furthermore, 63 is an air breather device bent into a substantially ■-shape, 64 is a locking mechanism that prevents the rotary work machine 10 from being lowered when it is raised, and 65 and 65 are for connecting the lift rod 17. This is the lift arm pin.

Next, regarding the hydraulic circuit of the hydraulic lift, a high pressure oil passage 24b is connected from a chamber on one side of the piston 22, that is, a cylinder chamber 25, and ports 23a, 23 of the hydraulic switching valve 23.
A high-pressure oil circuit 24 leading to the lift crank chamber 27 via a communication hole 24c is formed in the lift housing 18, and a drain circuit 26 leading directly from the cylinder chamber 25 to the lift crank chamber 27 is formed. Drain circuit 2
After drilling a drain circuit 26 in the lift housing 1B in the same direction as the axis of the cylinder chamber 25, the drain circuit 26 is A communication hole 24c is formed so as to be orthogonal to and communicate with.

Moreover, a safety valve 61 is provided in a part of the drain circuit 26, and its pressure adjusting part 61a is exposed to the external force of the lift housing 18 so that it can be rotated from the outside.

By appropriately operating this pressure adjusting portion 61a, the pressure set by the spring 61b can be easily varied.

Next, regarding the breather mounting structure, above the lift crank 20 and above the lifting shaft 19
A concave, for example, dogleg-shaped low pressure chamber 66 is formed on the inner surface of the lift housing 18 on the side opposite to the discharge port 26a of the drain circuit 26, and the above-mentioned air breather device 63 is communicated with this low pressure chamber 66. ing.

Furthermore, if we add the return oil guide structure based on Fig. 2,
A guide piece 67, 67 is attached to the base end of the lift crank 20 and is configured to face the direction in which the return oil is discharged, and is configured to reduce the flow velocity of the return oil discharged from the discharge port 26a of the drain circuit 26. There is.

The present invention is constructed as described above, and when the rotary working machine 10 shown in FIG. is in a fixed state, a lifting force is applied to the rotary working machine 10 around the connecting fulcrum 12a, and this lifting force acts via the top link 11 on the top link hinge 36 which is pivotally supported by the shaft 38. ,
The lifting force acting on the hinge 36 is applied to the other side 33b of the leaf spring 33 as compression pressure.

When a compression force greater than a preset force is applied to the leaf spring 33, the top link hinge 36 supported by the protrusion 32a or 32b moves the compression panel of the expansion curved portion 33C of the leaf spring 33 using the shaft 38 as a fulcrum. rotate counterclockwise against the

Therefore, the pin 40 protruding from the hinge 36 moves,
The swing plate 4 is connected via the first feedback lever 42.
4.45 rotates clockwise, and the shaft 49 and the cam 5 are rotated through the second feedback lever 47 and each element 53.48.
0 is rotated, the spool 30 of the hydraulic switching valve 23 moves, and the high pressure oil passage 24b1 is connected from the - side port 23a.
Hydraulic oil is supplied to the cylinder chamber 25 of the hydraulic lift 15 through the variable orifice and the connection port 24a, and the piston 2
2 and the piston rod 21 move forward as shown in FIG.
Lifting shaft 19 via lift crank 20
The rotary working machine 10 is raised in the direction indicated by the arrow in FIG.
As clearly shown in the figure, when the operating fulcrum 38 of the top link hinge 36 is provided at both end sides of the leaf spring 33 via the lower protrusion 32 a, the connecting fulcrum 12 with the lower link 12 is provided.
The work equipment 10 rotates counterclockwise around point a and rises,
The top link hinge 36 is rotated counterclockwise around this working fulcrum 38 via the top link 11.

Furthermore, if an upper protrusion 32b having substantially the same shape as the lower protrusion 32a described above is formed on the upper part of the bracket 32 as shown by the imaginary line in FIG. 2, it will form an inverted U shape as shown in FIG. The leaf spring 33, the top link hinge 36, the first feedback lever 42, etc. can be installed on objects other than those mentioned above, and in the state shown in FIG. When the top link hinge 36 rotates counterclockwise and rises, the top link hinge 36 rotates clockwise about this operating fulcrum 38 via the top link 11.

When a lifting force is applied to the work equipment 10 due to an increase in traction resistance as described above, the top link hinge 36 is pushed through the top link 11, and this pushing force compresses the leaf spring 33 and operates the hydraulic switching valve 23. , the work equipment 10 is raised to keep the traction resistance below the set value, and when the hinge pin 38, which is the action fulcrum, is positioned below the leaf spring 33 as shown in Fig. 2, the work equipment 10 is landed on the ground in a field, etc. When the machine 10 is in a high position relative to the tractor A and the top link 11 is tilted forward, connecting the top link 11 to the mounting hole 39 near the hinge pin 38 will cause the extension of the top link 11 to connect with the leaf spring 33. A hinge pin 38 is located in between, and the top link hinge 3 is connected by the top link 11.
6 may not compress the leaf spring 33, but when the top link 11 is tilted forward like this, the 5th
When the hinge pin 38 is positioned above the leaf spring 33 as shown in the figure, the leaf spring 33 is always compressed via the top link hinge 36 by the pushing force of the forward-inclined top link 11.

On the other hand, as shown in FIG.
8, if the work equipment 10 that has landed in a field or the like is at a low position relative to the tractor A and the top link 11 is tilted backward, connect the top link 11 to the mounting hole 39 near the hinge pin 38. Then, as above,
The hinge pin 38 is located between the extension line of the top link 11 and the leaf spring 33. Even if the top link hinge 36 is pushed by the waist top link 11, there is a risk that the leaf spring 33 will not be compressed. When tilting, the hinge pin 3 is placed below the leaf spring 33 as shown in FIG.
8, the leaf spring 33 is always compressed via the top link hinge 36 by the pushing force of the rearwardly tilted top link 11.

As is clear from the above embodiments, the present invention allows the work machine 10 to be towed behind the agricultural tractor A via the top link 11 and the lower link 12, and the work machine 10 is pulled by the hydraulic lift 15 controlled by the hydraulic switching valve 23. A top link hinge 36 is fixed vertically to the lift housing 18 of the hydraulic lift 15 via a substantially U-shaped plate spring 33, and the plate spring 33 is fixed in the middle of the hinge 36. In the structure that connects the bent rear side portions 33b, a plurality of mounting holes 39 connect the top link 11
... are provided in multiple stages on the top link hinge 36, and a pair of protrusions 32a, 32b are provided on the upper and lower ends of the bracket 32 that fixes the bent front side portion 33a of the leaf spring 33.
each of the protrusions 32 so that the bent rear side portion 33b of the leaf spring 33 is aligned with the top link hinge 36.
a.

32b selectively supports one end side of the top link hinge 36 via the action fulcrum 38, and the top link when the work machine 10 lands on the action fulcrum such as the hinge pin 38 of the top link hinge 36. The leaf spring 33 is always positioned on the extension line side of the working machine 11, and the support height changes when the work implement 10 is on the ground for a tractor moving on a plowing platform in a field or on plowed soil in a field. Even if the support angle of the top link 11 changes, by changing the action fulcrum 38 of the top link hinge 36 above and below the leaf spring 33, the action fulcrum 38 is kept in a state where the leaf spring 33 is always compressed by the hinge 36. hinge 36 in close proximity to
The top link 11 can be connected to the top link 1, and the top link 1 can be
1 is tilted forward, the acting fulcrum 38 is located above the leaf spring 33.
At the same time, the working equipment 10 is
When the support height of the top link 11 is low and the top link 11 is tilted backward, an action fulcrum 38 is provided below the leaf spring 33, and the traction resistance of the working machine 10 acting as a pushing force of the top link 11 causes the top link hinge to tilt backward. 36 and the plate nomene 33 can always be displaced only in the same direction, and the top link 11 can be safely and properly connected near the operating fulcrum 38 of the top link hinge 36 compared to the conventional technology. Top link 1 to top link hinge 36
It is possible to easily eliminate problems such as the connection position of the top link 11 being restricted with respect to the action fulcrum 38 due to a change in the connection angle of the top link hinge 36 and the leaf spring 3.
By displacing 3 in only one direction, practical effects such as being able to easily set the resistance detection reference value by the plate spring 33 can be achieved.

[Brief explanation of drawings]

Figure 1 is a schematic side view of the agricultural tractor according to the present invention;
The figure is a longitudinal sectional view of the hydraulic lift, Figure 3 is a plan view of the hydraulic lift showing the main parts in section, Figure 4 is a partial cross-sectional view showing the related structure between the link mechanism and the lifting shaft, and Figure 5 is the top view. The attachment of the link hinge is a vertical sectional view of a hydraulic lift showing a modification. A... Agricultural tractor, 10... Rotary working machine, 11... Top link, 12... Field link, 12a... Connection fulcrum, 15...・・・
... Hydraulic lift, 18 ... Lift housing,
23...Hydraulic switching valve, 32...Bracket, 32a, 32b...Protrusion, 33...
...Plate spring, 33a...Bent front side part, 33b
...Bending rear side part, 36...Top link hinge, 38...Action fulcrum.

Claims (1)

[Scope of utility model registration request] The working machine 10 is towed behind the agricultural tractor A via the top link 11 and the lower link 12, and the hydraulic switching valve 23
The working machine 10 is configured to be raised and lowered by a hydraulic lift 15 controlled by a lift housing 1 of the hydraulic lift 15.
In this structure, the top link hinge 36 is fixed to the top link hinge 36 in the vertical direction via a substantially U-shaped plate spring 33, and the bent rear side part 33b of the plate spring 33 is connected to the middle of the hinge 36. A plurality of mounting holes 39 for connecting the top link 11 are provided in the top link hinge 36 in multiple stages, and the bending front side portion 33 of the leaf spring 33 is provided with a plurality of mounting holes 39 .
A pair of protrusions 32a and 32b are formed at the upper and lower ends of the bracket 32 that fixes the plate spring 33, and the protrusions 32a are arranged so that the bent rear side part 33b of the leaf spring 33 is aligned with the top link hinge 36. , 32b, the action fulcrum 3
Alternatively, one end side of the top link hinge 36 is supported via the fulcrum 38 of the top link hinge 36.
A resistance control device for an agricultural tractor, characterized in that the leaf spring 33 is always positioned on the extension line side of the top link 11 when the work implement 10 lands.