JP2001164593A - Front loader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front loader capable of increasing the third circuits of two systems and improving a function without increasing the number of parts and without increasing a manufacturing cost. SOLUTION: In the front loader, a lift arm is vertically rotatably provided on a working machine side hitch, an attachment is vertically rotatably provided on the edge of the lift arm, a hydraulic cylinder for lift arm rotation for rotating the lift arm is interlocked and connected, a hydraulic cylinder for lift arm rotation for rotating the attachment is interlocked and connected, and a hydraulic pump is connected to both the hydraulic cylinders through a hydraulic circuit. The hydraulic circuit provides flow switching valves for switching a flow passage between each hydraulic cylinder and the hydraulic pump respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a front loader.

[0002]

2. Description of the Related Art In a conventional front loader, a lift arm is vertically rotatably arranged on a work machine side hitch detachably mounted on a tractor as the machine, and a bucket as an attachment is provided at a tip of the lift arm. Are arranged to be freely rotatable up and down, and a hydraulic cylinder for rotating the lift arm is interlockingly connected to the lift arm, and a hydraulic cylinder for turning the attachment is interlockingly connected to the attachment. The hydraulic cylinder and the hydraulic pump were connected via a hydraulic circuit.

In the conventional front loader, when a hydraulic working machine is mounted at the rear of the machine, a hydraulic cylinder is separately connected to a hydraulic pump via a control valve, and an operating member is connected to the control valve. I was

[0004]

However, in the above-mentioned conventional front loader, when a hydraulic working machine is mounted at the rear of the machine, a hydraulic cylinder, a control valve, and an operating member are separately prepared. Therefore, the number of parts increases, and there is a possibility that the manufacturing cost may increase.

In addition, the operator must operate not only an operation lever for operating the lift arm and the attachment but also an operation member for operating the hydraulic working machine, which makes the operation complicated. There was a risk.

[0006]

Therefore, according to the present invention, a lift arm is provided on the work machine side hitch so as to be vertically rotatable, and an attachment is provided at an end of the lift arm so as to be vertically rotatable. A lift arm rotating hydraulic cylinder for rotating the lift arm is linked to the lift arm, and a lift arm rotating hydraulic cylinder for rotating the attachment is linked to the attachment. In the front loader in which a hydraulic pump is connected via a hydraulic circuit, the hydraulic circuit is provided with a flow path switching valve for switching a flow path between each hydraulic cylinder and the hydraulic pump.

[0007] Each of the flow path switching valves is configured to switch to a flow path that connects and connects the hydraulic pump for rotating the lift arm and the hydraulic cylinder for rotating the attachment to the hydraulic pump when the power is turned on.

Further, the two flow path switching valves are disposed adjacent to the lift arm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A front loader according to the present invention
A lift arm is provided on the work machine side hitch so as to be vertically rotatable, and an attachment is provided at the end of the lift arm so as to be vertically rotatable. The lift arm is used to rotate the lift arm on the lift arm A hydraulic cylinder for rotation is interlockingly connected, while a hydraulic cylinder for lift arm rotation for rotating the attachment is interlockingly connected to the attachment, and a hydraulic pump is connected to both hydraulic cylinders via a hydraulic circuit.

Further, a flow path switching valve for switching a flow path between each hydraulic cylinder and the hydraulic pump is provided.

Therefore, when a hydraulic working machine is mounted on the rear of the machine or when a roll grab is mounted as an attachment, a hydraulic cylinder, control valve,
It is not necessary to prepare an operation member, and the function can be improved without increasing the number of parts and the manufacturing cost.

Further, after switching the flow path by the flow path switching valve, the operator can operate another hydraulic working machine by operating an operation lever for operating a lift arm or an attachment. The operation is simple, and the operability can be improved.

[0013] In addition, when each of the flow path switching valves is configured to switch to a flow path for connecting and connecting the hydraulic cylinder for lifting arm rotation and the hydraulic cylinder for attachment rotation to the hydraulic pump when the power is turned on, the flow path switching valve is also provided immediately after the power is turned on. In this case, the rotation operation of the frequently used lift arm and the rotation operation of the attachment can be performed without performing any special operation, and the operability can be improved.

Also, by disposing the two flow path switching valves adjacent to the lift arm, the visibility of the operator can be reduced as much as possible by the flow path switching valve. Operability can be improved.

[0015]

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

FIG. 1 is a view showing a front loader 1 as a working machine according to the present invention. The front loader 1 is detachably mounted on a tractor 2 as the machine.

As shown in FIG. 1, the tractor 2 has a prime mover unit 4 disposed at a front portion of the body frame 3 and a driving operation unit 5 disposed at a position immediately behind the prime mover unit 4. A pair of left and right front wheels 6 and 6 and rear wheels 7 and 7 are provided at lower front and rear portions of the body frame 3, respectively.

The tractor 2 has a pair of right and left hitch stays 8, 8 attached to a middle part of the body frame 3, and has a hitch 9, 9 on the hitch stays 8, 8; , 9, a portal-shaped connecting frame 10 is straddling the front view.

The front loader 1, as shown in FIG.
Work equipment side hitch detachably mounted on the machine side hitches 9,9
At 11 and 11, the base ends of a pair of left and right lift arms 12, 12 as operating parts, which are substantially in the shape of a letter in a side view, are pivotably connected to each other vertically.
Attachment hitch at the end of the lift arms 12,12
13 is attached to the attachment hitch 13
A bucket 14, which is an attachment as an operating part, is detachably attached to the bucket. In the figure, 25 is a stand, and 83 is a connecting pin.

The front loader 1 is provided between a lower part of the right work machine side hitch 11 and a middle part of the right lift arm 12 to lift and lower the lift arms 12 and 12. On the other hand, a support 16 is pivotally mounted on the right upper part of the lift arm 12 so as to be vertically rotatable, and a connecting rod 17 is provided between the rear part of the support 16 and the upper part of the right work machine side hitch 11. Are pivotally mounted, and each of the pivoting portions 18, 19, 20, 21 is arranged at the vertex position of a parallelogram, and the work machine side hitch 11, the lift arm 12, the support 16 and the connecting rod 17 are connected to each other. This constitutes a parallel link for moving the lift arm 12 up and down.

And a hydraulic cylinder for rotating the lift arm.
By extending the lift arm 15, the lift arms 12, 12 are raised, while the hydraulic cylinder 15 for rotating the lift arm is shortened, so that the lift arms 12, 12 are lowered.

Further, in the front loader 1, the base end of the connecting body 22 is attached to the front end of the lift arm 12 so as to be vertically rotatable. An attachment rotating hydraulic cylinder 23 for changing the attitude of the attachment by rotating the attachment is provided, and a connecting rod 24 is provided between the distal end of the connecting body 22 and the upper part of the attachment hitch 13. In the figure, reference numerals 76, 78, and 79 denote pivot portions, and reference numeral 84 denotes a connecting pin.

The distal end of the attachment is turned downward by extending the attachment turning hydraulic cylinder 23. At this time,
When the bucket 14 is mounted as an attachment, a dump operation is performed in which the tip of the bucket 14 is lowered downward. On the other hand, by shortening the attachment rotating hydraulic cylinder 23, the distal end of the attachment is rotated upward.
At this time, when the bucket 14 is mounted as an attachment, a squeeze operation is performed in which the tip of the bucket 14 is swung upward.

The front loader 1 has a lift arm rotation angle detecting means 71 for detecting the rotation angle of the lift arm 12 and an attachment rotation angle detecting means 72 for detecting the rotation angle of the attachment. Are provided.

The lift arm rotation angle detecting means 71 is provided at the pivot 21 between the support 16 and the connecting rod 17 at a potentiometer 73.
, And the detection arm 74 of the potentiometer 73 is slidably held by a pair of upper and lower pins 75, 75 erected on the connecting rod 17.
36, the rotation angle of the lift arm 12 is detected by the rotation angle of the detection arm 74 of the potentiometer 73.

The attachment rotation angle detecting means 72 includes a potentiometer 80 mounted on a pivot 78 between the attachment hitch 13 and the connecting rod 24, and a pair of upper and lower detecting arms 81 of the potentiometer 80 standing on the connecting rod 24. Pin 8
2 and 82 are slidably held, and the potentiometer 80 is connected to the controller 36 and the potentiometer 80
The rotation angle of the attachment is detected by the rotation angle of the detection arm 81.

FIG. 5 shows a hydraulic cylinder 15 for rotating the lift arm and a hydraulic cylinder 23 for rotating the attachment in order to operate the lift arm 12 and each operating part of the attachment.
FIG. 3 is a view showing a hydraulic circuit 27 interposed between the hydraulic circuit 27 and the hydraulic pump 26;

The hydraulic circuit 27 has a flow path switching valve 28 for changing the lifting operation of the lift arm 12 between the lift arm rotating hydraulic cylinder 15 for raising and lowering the lift arm 12 and the hydraulic pump 26. A pair of proportional control valves (not shown) are operatively connected to both ends of a spool 29 of the flow path switching valve 28, while an attachment rotating hydraulic cylinder 23 and a hydraulic pump 26 for changing the attitude of the attachment.
A flow path switching valve 32 for changing the posture of the attachment is interposed between the spool 33 and the spool 33 of the flow path switching valve 32.
A pair of proportional control valves (not shown) are linked to both ends of
Each proportional control valve is connected to a controller 36.

The hydraulic circuit 27 is mounted between the lift arm rotating hydraulic cylinder 15 and the hydraulic pump 26 as a lift arm side flow path 30 for operating the lift arm rotating hydraulic cylinder 15 and an attachment. A hydraulic cylinder 55 (see FIG. 10) for opening and closing the roll grab 54 and a third circuit side flow path 31 for operating a hydraulic cylinder for operating various hydraulic devices mounted on the rear of the machine. A flow path switching valve 56 for switching
On the other hand, between the attachment rotating hydraulic cylinder 23 and the hydraulic pump 26, an attachment side flow path 34 for operating the attachment rotating cylinder 23 and a hydraulic pressure for opening and closing the roll grab 54 mounted as the attachment are also provided. Via a flow path switching valve 57 for switching the flow path to a third circuit side flow path 35 for operating a cylinder 55 (see FIG. 10) and a hydraulic cylinder for operating various hydraulic devices attached to the rear part of the machine. Has been established.

Immediately after the power supply for operating the front loader 1 is turned on, the two flow path switching valves 56 and 57 are electromagnetic valves for moving the spools 85 and 86 of the flow path switching valves 56 and 57 forward and backward. Voltage is applied to 87 and 88, and both spools 85 and 86 are advanced to switch to the frequently used lift arm side flow path 30 and attachment side flow path 34, and the lift arm rotation hydraulic cylinder 15 and attachment rotation The hydraulic cylinder 23 and the hydraulic pump 26 are connected for communication.

In addition, the two flow path switching valves 56 and 57
As shown in the figure, the lift arm 12 is juxtaposed with a space in the front-rear direction on the left side. In the figure, 89 and 90 are brackets,
91 is a connector.

As described above, in this embodiment, the flow path for switching the flow path between the hydraulic cylinder 15 for rotating the lift arm and the hydraulic pump 26 and between the hydraulic cylinder 23 for rotating the attachment and the hydraulic pump 26 is provided. Separate hydraulic cylinders, control valves, and operating members are provided when a hydraulic work machine is installed at the rear of the machine or when a roll grab 54 is installed as an attachment, because the flow path switching valves 56 and 57 are provided. Therefore, two systems of third circuits can be added without increasing the number of parts and the manufacturing cost, and the function can be improved.

Moreover, the operator operates the flow path switching valve 5
After switching the flow path by 6,57, the other hydraulic working machine can be operated by operating the operation lever 42 for operating the lift arm 12 and the attachment, which will be described later, so that the operation is simple. Thus, the operability can be improved.

In this embodiment, each of the flow path switching valves 5
6 and 57 are configured to switch to a flow path for connecting and connecting the lift arm rotation hydraulic cylinder 15 and the attachment rotation hydraulic cylinder 23 to the hydraulic pump 26 when the power is turned on. The rotation operation of the frequently used lift arm 12 and the rotation operation of the attachment can be performed without performing any special operation, and thereby the operability can be improved.

In particular, in the present embodiment, since the two flow path switching valves 56 and 57 are disposed adjacent to the lift arm 12, respectively, the operator's view is blocked by the flow path switching valves 56 and 57. Can be reduced as much as possible, thereby also improving operability.

The front loader 1 is configured to operate each operation unit by performing PWM control of each proportional control valve by the controller 36.

An operation unit 37 is connected to the controller 36, and the operation unit 37 is disposed at a position on the right side of the operation operation unit 5.

That is, as shown in FIGS. 2 to 4, the bases of a pair of front and rear support members 38 and 39 are attached to the right side position of the driving operation unit 5 so as to be able to jump upward. 38,3
9 and a body casing 41 is attached to the front support body 38, and the body casing 41
A joystick-type operation lever 42 is erected on 41, and a float button 43, a horizontal button 44,
While the third circuit switching button 45 and the one-touch button 46 are provided respectively, the loader power switch is
47, a horizontal angle setting dial 48, and an auto button 49 are provided.

At the base end of the operation lever 42, the operation lever 42
A lever sensor 50 for detecting the direction and the swing angle at which the swing operation is performed is attached, and the lever sensor 50 and various operation members 43, 44, 45, 46, 47, 48, and 49 are connected to the controller 36. I have.

At the base end of the operation lever 42, there is provided a display panel 51 showing the operation of the lift arm 12 and the attachment in accordance with the swing operation of the operation lever 42. The operability is improved by making it easy to see in which direction the operation lever 42 should be rocked.

That is, the operation lever 42 is moved rearward (in FIG. 4,
When the swing operation is performed in the direction indicated by arrow 52), the flow path switching valve
By switching the spool 29 of 28 to the ascending flow path 53 and extending the hydraulic cylinder 15 for rotating the lift arm, the lift arm 12 is raised.

Further, the operation lever 42 is moved forward (in FIG.
When the swing operation is performed in the direction indicated by 58), the spool 29 of the flow path switching valve 28 is switched to the downward flow path 59, and the lift arm rotating hydraulic cylinder 15 is shortened, whereby the lift arm 12 is lowered.

At this time, when the float button 43 is pressed, the spool 29 of the passage switching valve 28 is switched to the float passage 60, and the lift arm rotating hydraulic cylinder 15 is moved.
To the hydraulic tank, and the lift arm 12 is lowered by its own weight.

When the operation lever 42 is swung leftward (in the direction indicated by an arrow 61 in FIG. 4), the flow path switching valve 32
By switching the spool 33 to the squeeze channel 62 and shortening the attachment rotating hydraulic cylinder 23,
The tip of the bucket 14 rotates upward, and the bucket 14
Is tilted backward to perform the squeeze operation.

When the operation lever 42 is swung rightward (in the direction indicated by an arrow 63 in FIG. 4), the flow path switching valve 32 is rotated.
By switching the spool 33 to the dump passage 64 and extending the attachment rotating hydraulic cylinder 23,
The tip of the bucket 14 rotates downward, and the bucket 14
Takes a forward leaning posture and performs a dump operation.

When the operating lever 42 is set upright,
The spool 29 of the flow path switching valve 28 is switched to the neutral flow path 65 to cut off the flow path between the lift arm rotating hydraulic cylinder 15 and the hydraulic tank, and the spool 33 of the flow path switching valve 32 is switched to the neutral flow path 66. Then, the flow path between the hydraulic cylinder 23 for rotating the attachment and the hydraulic tank is shut off, and the posture of the lift arm 12 and the bucket 14 is maintained.

When the operation lever 42 is swung in a diagonal direction, the lift arm 12 and the attachment operate in a combined manner. That is, the operation lever 42 is moved to the left rear side (FIG. 4).
When the swing operation is performed in the middle and in the direction indicated by the arrow 67), the attachment is squeezed while the lift arm 12 is raised, and when the operation lever 42 is operated to swing to the right rear (in the direction indicated by the arrow 68 in FIG. 4), When the lift arm 12 is lifted while the attachment is dumping, and the operation lever 42 is swung forward and left (in the direction indicated by an arrow 69 in FIG. 4), the attachment is squeezed while the lift arm 12 is lowered.
Move the operation lever 42 to the front right (in the direction indicated by the arrow 70 in FIG. 4).
When the swing operation is performed, the attachment is dumped while the lift arm 12 is lowered.

The larger the swing angle of the operating lever 42, the faster the hydraulic cylinder 15 for rotating the lift arm or the hydraulic cylinder 23 for rotating the attachment is extended and retracted.
12 or the attachment is operated at high speed.

FIG. 7 shows the spools of the flow path switching valves 56 and 57.
FIG. 9 is a diagram showing another electric circuit 92 for driving solenoid valves 87 and 88 for moving the 85 and 86 forward and backward, and shows a battery 93;
Connected to a third circuit switching button 45 with a lamp provided at the top of the operating lever 42, and relayed to the third circuit switching button 45.
While the solenoid valve 87 is connected via 94, the battery 93
A third circuit changeover switch 95 provided in the operation section 5 is connected, and an electromagnetic valve 88 is connected to the third circuit changeover switch 95. In the figure, 96 and 97 are bypass diodes.
When the electric circuit 92 is used, in an initial state, the spools 85 and 86 of the flow path switching valves 56 and 57 are urged to connect and connect the lift arm side flow path 30 and the hydraulic pump 26, and the attachment The side flow path 34 and the hydraulic pump 26 are connected for communication.

Then, when the third circuit switching button 45 is pressed, the relay 94 is operated, and the electromagnetic valve 87 is connected to the battery 93.
Is connected, the solenoid valve 87 is operated, and the flow path switching valve 56 switches from the lift arm side flow path 30 to the third circuit side flow path 31, while pressing the third circuit changeover switch 95,
An electromagnetic valve 88 is connected to the battery 93, and the electromagnetic valve 88 is operated to switch the flow path switching valve 57 from the attachment-side flow path 34 to the third circuit-side flow path 35.

When both the third circuit changeover button 45 and the third circuit changeover switch 95 are depressed, both solenoid valves 87 are actuated, and both flow path changeover valves 56, 57 are turned on by the third circuit changeover valve 56, 57. The flow paths are switched to the side flow paths 31 and 35, and the two circuit third flow paths 31 and 35 can be used at the same time, thereby improving operability and improving the electric circuit 92.
Has been simplified.

Further, the third circuit switching button 45 is operated with an operating lever.
Since it is arranged at the top of 42, the operator can operate the third circuit with one hand, so that the operability can be improved.

On the other hand, by disposing the third circuit changeover switch 95 on the instrument panel of the operation section 5, the third circuit changeover button 45 and the third circuit changeover switch 95 are arranged at positions separated from each other. Thus, erroneous operation of the third circuit changeover button 45 and the third circuit changeover switch 95 can be prevented.

FIG. 8 is a view showing another example of mounting the operation unit 37 of the front loader 1.
The muffler 100 is erected on the outer side of a column 99 formed at the right front corner of the cabin 98, while the operating section 37 is provided on the front side of the column 99, and the operating posture and column are turned down toward the operator. It is mounted so that the posture can be changed to the storage posture erect along the 99. In the figure, 101 is a steering column,
102 is a steering wheel, 103 is a seat, and 104 and 105 are side columns.

As described above, since the operation unit 37 is configured to be capable of changing the posture, the operation unit 37 can be moved up and down smoothly without obstruction by moving the operation unit 37 in the storage posture. Since it can be accommodated along the columns 99 of the cabin 98, the operation section 37 does not hinder the operator's view during the driving operation, and the safety can be improved.

FIG. 9 is a view showing the attachment hitch 13. The attachment hitch 13 has support plates 108, 109 attached to left and right ends of a pair of upper and lower connecting rods 106, 107, respectively.
A pair of left and right arm-side connecting plates 11 is provided at the rear of each of the supporting plates 108 and 109.
0, 111, 112, 113, and a pair of left and right attachment-side connecting plates 114, 115, 116, 11
7 is attached to the upper connecting rod 106, and tilt angle display means 118 for allowing the operator to visually check the tilt angle of the attachment is rotatable in the front-rear direction and movable in the left-right width direction. Provided.

The inclination angle display means 118 attaches a hook 120 to a front base end of a display body 119 having an inverted L-shape in a side view, and drills a bolt insertion hole at a rear base end of the display body 119.
A nut 121 is welded to the opening of the bolt insertion hole, a fixing bolt 122 is screwed to the nut 121, and the upper connecting rod 106 is held between the hook 120 and the fixing bolt 122.

By adjusting the display surface 123 of the display body 119 to be horizontal when the attachment is in the horizontal state, the operator can visually check the display surface 123 of the display body 119 and thereby adjust the attachment. The tilt angle can be checked.

As described above, since the inclination angle display means 118 is attached to the attachment hitch 13, even if the attachment is replaced with the attachment hitch 13, the inclination angle of the attachment can be confirmed by the inclination angle display means 118.

Further, since the inclination angle display means 118 is attached to the attachment hitch 13 so as to be rotatable in the front-rear direction, the inclination angle of the display body 119 can be adjusted according to the attachment even when the attachment is changed to the attachment hitch 13. By doing so, the inclination angle can be confirmed for any attachment.

Further, since the inclination angle display means 118 is attached to the attachment hitch 13 so as to be movable in the left-right width direction, the operator can adjust the mounting position of the inclination angle display means 118.

FIG. 10 is a view showing another tilt angle display means 124. The tilt angle display means 124 is pivotally mounted on the support 16 which is rotatably mounted on a middle part of the left and right lift arms 12. A display support arm 125 is pivotally attached to the portion 20 so as to be pivotable back and forth, and a connecting rod 12 is provided between upper end portions of the display support arm 125.
6 and the display body 127 is attached to the connecting rod 126 so as to be rotatable back and forth, while the distal end of the connecting rod 128 is pivotally attached to the middle of the display body supporting arm 125, and the base end of the connecting rod 128 is mounted. Is attached to a pivot 79 of the attachment hitch 13. In the figure, 129 is a fixing bolt.

The connecting rod 128 is configured such that the distal rod member 131 is accommodated at the distal end of a hollow cylindrical base rod member 130 so as to be able to advance and retreat, and the length thereof can be adjusted. In the figure,
132 is a fixing bolt.

By adjusting the length of the connecting rod 128, the connecting rod 128 and the display support arm 125 are adjusted.
The parallel link is formed by the display support arm 125, the lift arm 12, the attachment hitch 13 and the connecting rod 128 so that the pivot 133 and the pivots 20, 78, 79 are located at the top of the parallelogram. It is formed.

As a result, the display 127 rotates at an angle equal to the rotation angle of the attachment hitch 13. Therefore, the operator can visually check the rotation angle of the display 127 to change the rotation angle of the attachment. You can check.

FIG. 11 is a view showing the hydraulic cylinder 23 for rotating the attachment. The hydraulic cylinder 23 for rotating the attachment moves the distal-side cylinder body 135 inside the hollow cylindrical base-side cylinder body 134. It is housed freely. In the figure, 136 and 137 are bosses.

The base-side cylinder assembly 134 is fitted with seal rings 138 and 139 that slidably support the tip-side cylinder assembly 135 in the middle and at the tip, thereby providing a sealed base-side cylinder chamber. 140 and a tip side cylinder chamber 141 are formed. In the figure, reference numeral 142 denotes the distal cylinder structure
The partition members 143 and 144 slide along the inner side surface of the base-side cylinder structure 134, and 143 and 144 are hydraulic oil inlets.

A pressure gauge 145 for detecting the pressure in the chamber is connected to the base end cylinder chamber 140, and a marker 147 is rotatably mounted on the outer periphery of the display plate 146 of the pressure gauge 145. The pressure gauge 145 is provided in the operation section 5.

When the hydraulic cylinder 23 for rotating the attachment is extended by moving the distal cylinder member 135 out of the proximal cylinder member 134, the pressure in the proximal cylinder chamber 140 gradually decreases. Therefore, the pressure in the proximal cylinder chamber 140 detected by the pressure gauge 145 causes the hydraulic cylinder 23 for turning the attachment to rotate.
The cylinder length can be recognized.

Further, by setting the marker 147 at the position indicated by the display needle 148 of the pressure gauge 145 when the attachment is in the horizontal state, the attachment can be displayed from the display of the pressure gauge 145 disposed on the operation section 5. It can be determined whether or not it is in a horizontal state and the rotation angle of the attachment.

[0071]

The present invention is embodied in the form described above and has the following effects.

(1) In the present invention, a lift arm is vertically rotatably disposed on the work machine side hitch, and an attachment is vertically rotatably disposed at the tip of the lift arm. While the lift arm rotating hydraulic cylinder for rotating the lift arm is interlockingly connected, the attachment is linked with the lift arm rotating hydraulic cylinder for rotating the attachment,
In a front loader in which a hydraulic pump is connected to both hydraulic cylinders via a hydraulic circuit, the hydraulic circuit is provided with a flow path switching valve for switching a flow path between each hydraulic cylinder and the hydraulic pump. When a hydraulic work machine is installed at the rear of the machine or when a roll grab is installed as an attachment, there is no need to prepare separate hydraulic cylinders, control valves, and operating members, increasing the number of parts and increasing manufacturing costs. Therefore, two systems of third circuits can be added without inducing, and the function can be improved.

Further, after switching the flow path by the flow path switching valve, the operator can operate another hydraulic working machine by operating an operation lever for operating a lift arm or an attachment. The operation is simple, and the operability can be improved.

(2) In the present invention, each flow path switching valve is
When the power is turned on, it is configured to switch to the flow path for connecting and connecting the lift arm turning hydraulic cylinder and the attachment turning hydraulic cylinder to the hydraulic pump, so immediately after turning on the power, without performing any special operation,
It is possible to perform the rotation operation of the frequently used lift arm and the rotation operation of the attachment, thereby also improving the operability.

(3) In the present invention, since both the flow path switching valves are arranged adjacent to the lift arm, the visibility of the operator is less obstructed by the flow path switching valves as much as possible. This can also improve the operability.

[Brief description of the drawings]

FIG. 1 is a side view showing a front loader according to the present invention.

FIG. 2 is a plan view showing an operation unit.

FIG. 3 is a side view of the same.

FIG. 4 is a plan view showing a display panel.

FIG. 5 is an explanatory diagram showing a hydraulic circuit.

FIG. 6 is a side view showing a flow path switching valve.

FIG. 7 is an explanatory diagram showing an electric circuit of a third circuit.

FIG. 8 is a plan view showing a driving operation unit.

FIG. 9 is a perspective view showing an attachment hitch.

FIG. 10 is a side view showing an inclination angle display means.

FIG. 11 is a side sectional view showing an attachment rotating hydraulic cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front loader 2 Tractor 11 Work machine side hitch 12 Lift arm 13 Attachment hitch 14 Bucket 15 Lift arm rotation hydraulic cylinder 16 Support 17 Connection rod 22 Connection body 23 Attachment rotation hydraulic cylinder 24 Connection rod 26 Hydraulic pump 27 Hydraulic circuit 28 , 32 Flow path switching valve 30 Lift arm side flow path 31,35 Third circuit side flow path 34 Attachment side flow path 36 Controller 42 Operating lever 56,57 Flow path switching valve 87,88 Solenoid valve

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naoto Yamanaka 1-32 Chaya-cho, Kita-ku, Osaka City, Osaka Prefecture F-term in Yanmar Agricultural Machinery Co., Ltd. (reference) 2D003 AA01 AB03 AB04 BA01 BA06 BA07 CA06 DA04 DB02 DB04 2D012 BA06 2D015 BA01 BA04

Claims (3)

[Claims] 1. A lift arm is provided on a work machine side hitch so as to be vertically rotatable, and an attachment is provided at an end of the lift arm so as to be vertically rotatable, and the lift arm is turned on the lift arm. The hydraulic cylinder for lift arm rotation to rotate the attachment is connected to the attachment while the hydraulic cylinder for lift arm rotation is connected to the attachment, and the hydraulic pump is connected to both hydraulic cylinders via a hydraulic circuit. In the front loader, the hydraulic circuit is provided with a flow path switching valve for switching a flow path between each hydraulic cylinder and the hydraulic pump. 2. The apparatus according to claim 1, wherein each of the flow path switching valves is configured to switch to a flow path for connecting and connecting the hydraulic pump for rotating the lift arm, the hydraulic cylinder for rotating the attachment, and the hydraulic pump when the power is turned on. 1. The front loader according to 1. 3. The front loader according to claim 1, wherein the two flow path switching valves are arranged adjacent to the lift arm.