JPH09248011A - Draft adjustment device for tractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust the transmission power of a traction load in draft control in a tractor work. SOLUTION: A ground work machine is connected to the rear part of a tractor, the work machine is made freely elevatable and lowerable through a lift linkage mechanism by a hydraulic circuit provided with a lift control valve and a lift cylinder and the work machine is elevated/lowered so as to maintain the traction load of the work machine almost fixed while detecting the push pull force of the top link of the lift linkage mechanism and feeding it back to the lift control valve. In this case, an adjustment actuator 10 for receiving hydraulic power supplied by an electromagnetic proportional solenoid valve 9 operated by a draft adjustor 8 and correcting the transmission of the push pull force is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a draft adjusting device for adjusting or switching the draft (traction load) of a tractor.

[0002]

Although a draft spring is provided as a draft feedback mechanism,
The pressure adjustment of the draft spring is difficult because the operation is troublesome because the connecting position of the top link and the lift link mechanism is changed or the draft spring is selected and replaced according to the load.

[0003]

According to the present invention, a ground work implement 22 is connected to a rear portion of a tractor, and a hydraulic circuit 3 having a lift control valve 1 and a lift cylinder 2 is used to perform the above-mentioned work via a lift link mechanism 4. The working machine 22 can be lifted up and down, and the pulling force of the top link 5 of the lift link mechanism 4 is detected and fed back to the lift control valve 1 to maintain the towing load of the working machine 22 substantially constant. In the draft controller 7 that moves up and down, the adjustment actuator 10 that receives the hydraulic pressure supplied by the electromagnetic proportional solenoid valve 9 operated by the draft adjuster 8 and corrects the transmission of the pushing and pulling force.
The tractor draft adjusting device is provided with.

[0004]

EFFECT OF THE INVENTION Lift link mechanism 4 at the rear of the tractor vehicle body
The ground work implement 22 is attached to the ground to perform plowing work while moving forward. Top link 5 depending on the towing load of this work machine
The action force that pushes forward is generated, and the draft spring 6
The lift cylinder 2 is fed back to the lift control valve 1 against the control actuator 10 and the adjustment actuator 10.
The draft control is performed so that the drag force of the working machine is maintained constant while adjusting the hydraulic pressure supply amount to the work machine.

This work machine towing load can be changed and adjusted according to the size of the work towing load of the work machine. When the work towing load is changed, the draft is adjusted according to the installed work machine. At this time, the draft adjuster 8 is operated. By operating the draft controller 8, the electromagnetic proportional solenoid valve 9 is opened / closed in proportion to the adjustment amount to supply hydraulic pressure to the adjusting actuator 10, and the adjusting actuator 10 is supplied via the electromagnetic proportional solenoid valve 9. Depending on the oil pressure, the reaction force to the work towing load is adjusted to be large or small, and when the work machine has a large load, the oil pressure becomes large and the reaction force to the work towing load becomes large. This has the same effect as increasing the pressure, and on the contrary, it has the same effect as weakening the work machine with a light load.

As described above, the draft adjuster 8 is operated and adjusted by the operator, and the hydraulic pressure of the adjusting actuator 10 is adjusted by electromagnetically changing the electromagnetic proportional solenoid valve 9 to tension the draft spring 6. Since it is the same as adjusting the pressure, no complicated mechanism is required, the configuration can be simplified, and the operation can be performed accurately and easily.

[0007]

EXAMPLE A tractor vehicle body 11 has front wheels 13 steered by a steering wheel 12 and rear wheels 15 pivotally mounted on a rear portion of a cockpit 14, and is driven by an engine E mounted on the front portion. In a possible four-wheel drive traveling mode, a hydraulic case 17 is provided above the transmission case 16 at the rear of the vehicle body 11, and the lift cylinder 2, the piston 19 and the lift arm shaft 18 rotated by the lift cylinder 2 are provided inside.
Etc., and the lift arm 20 integrated with the lift arm shaft 18 can be vertically rotated by the hydraulic pressure supplied and discharged from the lift control valve 1 arranged outside the hydraulic case 17.

The lift link mechanism 4 has a top link 5 and a lower link 21 attached to a rear portion of a mission case 16 so as to be vertically rotatable, and a plow as a ground working machine (hereinafter, working machine) 22 is attached to a rear end of these. This working machine 22 is mounted by rotating the lower link 21 up and down via the lift rod 23 by the rotation of the lift arm 20.
Can be raised to the height of the non-working position or lowered to the working position. A reference numeral 24 is a position lever provided on the lateral side of the cockpit 14, and the lift control valve 1 can be manually operated to move the lift arm 20 up and down. Reference numeral 25 is a lift angle sensor composed of a potentiometer, which can detect the angle of the lift arm shaft 18.

The transmission case 16 and the hydraulic case 1
A draft link 27 connecting the top link 5 with a connecting pin 26 and a draft cylinder 28 having a draft spring 6 therein are provided between a rear end portion of the draft spring 7 and the rear end portion. The draft link 27 has a lower end pivotally supported by a pin 29 so as to be rotatable forward and backward with respect to the mission case 16, and a pin 32 connects the upper end with a piston 31 at a rear end of a rod 30 inserted into the cylinder 28. are doing. Reference numeral 33 is a pin hole for adjustment.

The front end of the rod 30 is a controller CPU
A control arm 34 for adjusting and controlling the lift control valve 1 is interlocked therewith. The draft spring 6 is elastically pushed so as to press the rod 30 toward the rear side draft link 27 side, and when the draft link 27 is swung back and forth around the pin 29 by the forward and backward movement of the top link 5, the rod 30 is moved. When the rod 30 is moved back and forth against the resilience of the draft spring 6 and the rod 30 is moved forward, the lift control valve 1 is switched to the up position to lift the work implement 22 by the lift arm 20 to reduce the work load. On the contrary, when the rod 30 is moved to the rear side, the lift control valve 1 is switched to lower to lower the working machine 22 so that the draft (traction load) always maintains a constant region. .

The adjusting actuator 10 includes a rod 3
A piston 31 integral with the rear end of 0 is fitted into the rear part of the draft cylinder 20 accommodating the draft spring 6 so as to be movable back and forth, and is always urged backward by the draft spring 6 at a constant pressure. . A hydraulic circuit 35 for operating an oil pressure adjusted by the electromagnetic proportional solenoid valve 9 is connected in the draft cylinder 20, and the top link 5 and the draft link 2 are connected by the oil pressure P1.
The hydraulic pressure P1 can be adjusted by the electromagnetic proportional solenoid valve 9 so as to oppose the pressing force D from the 7 side.

Further, such a proportional solenoid valve 9
Is set to the light load work machine position V1 by changing the volume (current value) by the draft adjuster 8 on the side of the cockpit 14.
To the normal load working machine position V2, and further to the heavy load working machine position V3. The volume control input is output to the electromagnetic proportional solenoid valve 9 via the controller CPU, and the hydraulic pressure to the draft cylinder 28 by the hydraulic circuit 35 can be adjusted. In the electromagnetic proportional solenoid valve 9,
There is a characteristic graph G in which the hydraulic pressure P1 of the hydraulic circuit 35 to the draft cylinder 28 changes substantially proportionally according to the output current A from the controller CPU.

The volume adjustment by the draft adjuster 8 is performed for the standard load work machine V2 having a standard load.
When the light load work machine V1 is connected, the low current value A1 is set, and when the heavy load work machine V3 is connected, the high current value A3 is set. The hydraulic pressure sent to the draft cylinder 28 by these current values is low at low current value A1 and high at high current value A3.

The hydraulic circuit 3 operated by the output from the controller 7 has a tank port T and a hydraulic pump P. The hydraulic pressure sent from the hydraulic pump P is lifted by the flow visor 36 and lift control. The flow can be divided into a circuit having the valve 1 and the like, a circuit of a hydraulic operation system such as a clutch and a gear shift, and can be sent to the proportional solenoid valve 9 and the draft cylinder 28 via the hydraulic circuit 35. In feedback interlocking of the pressing force interlocking with the rod 30 against the draft spring 6 from the top link 5, the proportional solenoid valve 9 is operated based on the volume adjusted by the draft adjuster 8, and the hydraulic pressure in the draft cylinder 28 is increased. Is applied to push the rod 30 against the draft spring 6 to correct the pushing force from the top link 5 side.

4 and 5, the difference from the above example is that
A draft sensor 41 for detecting a draft is provided in the mounting portion of the lower link 21, and has an oil damper 42 and a pressure switch 43 for detecting a change in oil pressure in the oil damper 42. Draft control is performed by inputting it to the draft controller CPU, so that the configuration can be simplified.

A rod 45 connected to the lower link 21 is inserted into a bracket 44 of the mission case 16 so that the rod 45 can be moved back and forth, and a spring 46 springs the rod 45 forward. The oil damper 42 fits the piston 48 in the cylinder, fixes the cylinder to the bracket 44, and
When the lower link 21 is moved back and forth against the spring 46 by the pulling force, the piston 48 of the draft sensor 41 is connected to the tip of the rod 45 by a connecting piece 49.
The hydraulic pressure of the oil damper 42 changes due to the movement in the same direction, and is detected by the hydraulic pressure switch 43, and the raising solenoid 1U or the lowering solenoid 1D of the lift control valve 1 is output to perform draft control. Reference numeral 50 is a draft control switch for automatically performing draft control, and reference numeral 51 is a monitor lamp for displaying a light during the draft control.

In FIG. 6, a point different from the above example is that the mounting position of the oil damper 42 is changed to the bolt 52 and the nut 5.
It is easy to adjust to 3. Reference numeral 54 designates a rod portion of the piston 48 as an angular shaft portion having a hexagonal cross section, which can be rotated by applying a spurner. The bolt 52 and the connecting piece 49 can be screwed and adjusted. When changing the draft transmission,
The position of the piston 48 of this oil damper 42 is adjusted.

In FIG. 7, the difference from the above example is that instead of the oil damper 42, the draft sensor 4 is provided by a potentiometer 55 provided on the hydraulic case 17 which is higher than the rod 45 which is the support connecting position of the lower link 21.
1, the damage to the meter, the harness, etc. can be reduced, and the left and right lower links can be configured independently, so that finer draft control can be performed. A protrusion 56 is integrally formed on the connecting piece 49, and the protrusion 56 is interposed between the bifurcated rotary arms 57 of the potentiometer 5 to press and move the spring 46 of the lower link 21. D can be detected by the rotation of the rotating arm 57 by the re-potentiometer 5, and draft control can be performed.

[Brief description of drawings]

FIG. 1 is a side view of a draft spring portion shown in a partial block diagram.

FIG. 2 is a hydraulic block circuit diagram and a control block diagram.

FIG. 3 is a side view of the tractor.

FIG. 4 is an exploded perspective view of a draft sensor part showing another embodiment and a plan view of a part thereof.

FIG. 5 is a block circuit diagram of the draft control.

FIG. 6 is a plan view of a draft sensor part showing another embodiment.

FIG. 7 is an exploded perspective view of a draft sensor part showing another embodiment and a plan view of a part thereof.

[Explanation of symbols]

 1 Lift Control Valve 2 Lift Cylinder 3 Hydraulic Circuit 4 Lift Link Mechanism 5 Top Link 6 Draft Spring 7 Draft Controller 8 Draft Adjuster 9 Electromagnetic Proportional Solenoid Valve 10 Adjusting Actuator

Claims (1)

[Claims] 1. A ground work implement 22 is connected to a rear portion of a tractor, and a hydraulic circuit 3 having a lift control valve 1 and a lift cylinder 2 makes the work implement 22 movable up and down via a lift link mechanism 4, and The push-pull force of the top link 5 of the lift link mechanism 4 is detected and fed back to the lift control valve 1 to maintain the pulling load of the work implement 22 substantially constant.
In the draft controller 7 for moving up and down 2, the draft adjustment of the tractor is provided with an adjustment actuator 10 for receiving the hydraulic pressure supplied by the electromagnetic proportional solenoid valve 9 operated by the draft adjuster 8 and correcting the transmission of the pushing and pulling force. apparatus.