JPH0439307Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a control device for a front loader.

(Prior art) In a front loader that is attached to a vehicle such as a tractor, a bucket is installed at the tip of a boom that is pivotally connected to the boom so that it can be raised and lowered, and is equipped with a bucket that can perform dump and scoop operations using a bucket cylinder. The control valve that controls this bucket cylinder is configured to amplify the communication between both cylinder chambers of the bucket cylinder during dumping so that the dumping speed becomes faster than the rake speed.

(Problems to be Solved by the Invention) When scooping earth and sand into a bucket with this type of front loader, it is necessary to lower the boom and bring the bottom of the bucket into horizontal contact with the ground.

However, in the past, the dumping speed was faster than the rake speed, so it was cumbersome to operate when leveling the bottom of the bucket, and the bucket moved too much when correcting the dumping direction. .

In view of these problems, the present invention is designed to easily control the attitude of the bucket by controlling the dumping speed of the bucket when the boom is in the descending range.

(Means for Solving the Problems) As a means for solving the problem, the present invention provides a bucket 9, which is capable of dumping and rake operations using a bucket cylinder 8, at the tip of a boom 6 which is pivotally attached to the vehicle body 1 so as to be able to move up and down. The bucket cylinder 8 is provided so that the dumping speed of the bucket 9 is faster than the rake speed.
In a front loader equipped with a bucket control valve 25 for controlling the
1 and 36 are activated, limiting means 30 and 33 are provided for limiting the opening degree of the bucket control valve 25 during dumping.

(Function) When the boom 6 is in the descending region A, the detection means 21,
36 works to detect it. In response to this, the limiting means 30 and 33 operate to limit the opening degree of the bucket control valve 25 during dumping compared to the rising range. Therefore, even though the bucket 9 is of a type that increases the speed during dumping, the dumping operation is slow.

(Example) Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment. In FIG. The front loader 2 is pivotally attached to the upper end of the mounting frame 3 with a pivot 4,
It also includes a pair of left and right booms 6 that can be raised and lowered by a boom cylinder 5, and a bucket 9 that is pivotally attached to the tip of the boom 6 with a pivot 7 and that can be operated by a bucket cylinder 8 for dumping and rake operations. It consists of 10 is a three-point link mechanism, 11 is a hydraulic system, 12 is a driver's seat, and 13 is a cabin.

Reference numeral 14 denotes an operating lever, which is provided on a support base 15 attached to the mounting frame 3 as shown in FIG. 3 so as to be tiltable in all directions, front and back and left and right. The support base 15 is provided with a rise command device 16 and a descent command device 17 that give a rise command and a descent command in conjunction with the forward and backward operation of the operation lever 14, and also provide a dump command and a scoop command in conjunction with the left and right operation of the operation lever 14. A dump command device 18 and a rake command device 19 are provided for giving commands. In addition, these command units 1
Reference numerals 6 to 19 are constituted by variable resistors, and are adapted to issue a command proportional to the operating angle of the operating lever 14.

A cam 20 is provided on the base side of the boom 6 as shown in FIG. 4, and a cam 20 is provided on the mounting frame 3 side.
Detection means 21 are provided which are actuated by the cam 20 when the boom 6 is in the lowering region A.

FIG. 5 shows a hydraulic circuit, and 22 is a boom control valve for controlling the boom cylinder 5, which is of an electromagnetic proportional type having a rising solenoid 23 and a descending solenoid 24. Reference numeral 25 denotes a bucket control valve for controlling the bucket cylinder 8, which is of an electromagnetic proportional type having a dump solenoid 26 and a squirt solenoid 27. The bucket control valve 25 is configured to increase speed by communicating both cylinder chambers with the pump port during dumping, so that the dumping speed becomes faster than the rake speed. 28 is a control valve of the hydraulic system 11.

FIG. 1 shows a drive circuit for control valves 22 and 25,
A rise command device 16 is connected to the rise solenoid 23 of the boom control valve 22, and a descent command device 1 is connected to the fall solenoid 24 of the boom control valve 22.
7 are connected to each other. A dump command device 18 is connected to the dump solenoid 26 of the bucket control valve 25, and a scoop command device 19 is connected to the squeezing solenoid 27, and the two of the detection means 21 are connected between them.
Switches 28 and 29 are interposed. The switches 28, 29 have a contacts 28a, 29a and b contacts 28b, 29b.
Current limiting resistors 30 and 31 are connected to 9a. The resistor 31 is set to a resistance value such that when the rake command device 18 issues a fully open command, the bucket control valve 25 is brought into a half-port state toward the rake side. The resistor 30 is set to a resistance value such that the bucket control valve 25 is in the half-port state when the dump command device 19 issues a full open command. Note that this resistor 30 constitutes a limiting means.

In the above configuration, when the boom 6 is lowered from the position of the imaginary line B in FIG. 17 gives a descending command. This allows the boom control valve 2
2 switches to the lowering side, the boom cylinder 5 contracts, and the boom 6 lowers. When the boom 6 descends to the descending area A where the bucket 9 is located near the ground, the detection means 21 is activated by the cam 20.
The switches 28 and 29 are b contacts 28b and 29b
The a contact point 28a, 29a is then switched.

When the bucket 9 reaches near the ground as shown by the imaginary line C in FIG. 2, operate the operating lever 14 left and right.
The bucket cylinder 8 is actuated by the bucket control valve 25, and the bucket truck 9 is operated in the dump or scoop direction to correct its attitude so that the bottom surface of the bucket truck 9 is horizontally grounded. In this case, if the bucket 9 is lowered forward, the rake command 1 is moved by the operation lever 14.
A squeezing command is given to the bucket control valve 25 through the resistor 31, so even if the operating lever 14 is moved to the maximum angle, the current is limited by the resistor 31, and the bucket control valve 25 is forced to the half port. The bucket 9 moves slowly in the rake direction.

Furthermore, if the bucket 9 is lowered forward, a dump command is given by the dump command device 18, but in this case as well, there is a resistor 30, which limits the opening degree of the bucket control valve 25 to the half-port state. Even though both cylinder chambers of the bucket cylinder 8 communicate with each other, the dumping speed of the bucket 9 can be made as slow as the above-mentioned rake speed. Therefore, the bucket 9 will not move too much in the dump/screw direction.
The attitude of the bucket bag 9 can be easily corrected to a horizontal state.

6 to 8 illustrate a second embodiment of the present invention, which uses mechanical means, whereas FIG. 1 uses electrical means. Reference numeral 32 denotes a valve device mounted on the mounting frame 3, in which a mechanical bucket control valve 25 is incorporated, and is interlocked with left and right operations of the operating lever 14. Reference numeral 33 denotes a U-shaped regulating body constituting a limiting means, which is supported by a bracket 35 of the mounting frame 3 so as to be movable in parallel via a parallel link mechanism 34 . One link 35 of the parallel link mechanism 34 has a detection rod (detection means) 36 that projects forward,
A cam 37 is attached to the side surface of the boom 6 in correspondence with the tip of the detection rod 36. When the boom 6 descends to the descending area A as shown in FIG. 8, the detection rod 36 is swung by the cam 37 as shown in the imaginary line in FIG. 7, and the parallel link mechanism 3
4, the regulating body 33 approaches the operating lever 14 side as shown by the imaginary line in the figure. Therefore, the operating lever 14
Even if the bucket control valve 25 is operated toward the dump position Δ in the direction of the arrow in FIG. 6, it is restricted by the regulating body 33 and the bucket control valve 25 opens only about half the port. 38 is a helical spring, and 39 is a stopper.

9 to 11, the attitude of the bucket cart 9 is detected by the detection means 40, and when the bucket cart 9 is within a range of about ±10 degrees from the horizontal bottom surface, the dump/sweet speed of the bucket cart 9 is limited. show something

The detection means 40 is a vertical plumb body 34 pivotably supported on the bucket bag 9 side by a support shaft 42 as shown in FIG.
and a cam 44 provided thereon, and is operated by the cam 44. This detection means 40 consists of two switches 45 and 46,
The switches 45, 46 are a contacts 45a, 46
b, b contacts 45b, 46b, and a contact 4
The point that resistors 47 and 48 are connected to 5a and 46a is the same as in FIG.

(Effect of the invention) According to the invention, when the boom 6 is in the descending region A, the detecting means 21 and 36 detect this, and the limiting means 30 and 33 limit the opening degree of the bucket control valve 25 during dumping. Therefore, even though the speed is increased during dumping, the attitude of the bucket cart 9 in the descending region A can be easily corrected.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, in which FIG. 1 is an electric circuit diagram, FIG. 2 is an overall side view, FIG. 3 is a layout diagram of a command unit, and FIG. FIG. 4 is a side view of the detection section, and FIG. 5 is a hydraulic circuit diagram. 6 to 8 show a second embodiment of the present invention, in which FIG. 6 is a rear view, FIG. 7 is a cross-sectional plan view, and FIG. 8 is an explanatory view of the operation. Figures 9 to 1
1 discloses another control device, FIG. 9 is a circuit diagram, FIG. 10 is a side view of the bucket, and FIG. 11 is a side view of the detection section. 1...Tractor body, 2...Front loader,
6...Boom, 8...Bucket cylinder, 9...
Bucket, 21...Detection means, 22...Boom control valve, 25...Bucket control valve, 28, 29...
Switch, 30...Resistance (limiting means), 33...
Regulator (restriction means), 36...detection rod (detection means).

Claims (1)

[Scope of utility model registration request] A bucket 9 capable of dumping and rake operations is provided at the tip of a boom 6 that is pivotally attached to the vehicle body 1 so as to be able to rise and lower. Detecting means 21, 36 for detecting that the boom 6 is in the descending region A;
limiting means 3 for limiting the opening degree of the bucket control valve 25 during dumping when the detecting means 21, 36 are activated;
0,33.