JP2002004324A - Front loader - Google Patents

Abstract

(57) [Abstract] [Problem] To prevent a natural fall of a lift arm. A lift arm (4) is provided on a machine (2) via hitches (10, 26) so as to be vertically rotatable, and an attachment (5) is provided at the tip of the lift arm (4) so as to be vertically rotatable. In a front loader in which a hydraulic cylinder 6 for rotation and a hydraulic cylinder 7 for attachment rotation are connected to a hydraulic pump P via a control valve 8, an electromagnetic check valve is provided to a lifting circuit R 1 of the hydraulic cylinder 6 for lift arm rotation. 9 were provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a front loader in which a lift arm is attached to a main body such as a tractor via a hitch so as to be vertically rotatable, and an attachment such as a bucket is attached to the tip of the lift arm so as to be vertically rotatable. was there.

Such a front loader includes a hydraulic cylinder for rotating a lift arm and a hydraulic cylinder for rotating an attachment. The two cylinders and a hydraulic pump are connected via a hydraulic circuit provided with a control valve. The lift arm and the attachment are operated from the working machine via the control valve.

[0004] This type of front loader is usually provided with a manual stop valve so that the lift arm does not unexpectedly lower during transportation, for example.

[0005]

However, the manual stop valve provided in the conventional front loader described above is
The operator cannot operate the stop valve, for example, when operating a tractor equipped with a front loader, the operator must step down from the driver's seat and operate the stop valve.

An object of the present invention is to provide a general-purpose combine which can solve the above-mentioned problems.

[0007]

According to the first aspect of the present invention, a lift arm is vertically rotatably disposed on the machine via a hitch, and an attachment is vertically rotatable at the tip of the lift arm. In the front loader, a hydraulic cylinder for rotating the lift arm and a hydraulic cylinder for rotating the attachment are connected to a hydraulic pump via a control valve. Provided.

The present invention according to claim 2 is characterized in that a normally closed type electromagnetic check valve is provided between the lift arm hydraulic cylinder and the lift port of the control valve.

Further, the present invention according to claim 3 is characterized in that the power supply of the electromagnetic check valve is linked to a key switch of the apparatus.

Further, the present invention according to claim 4 is characterized in that the power supply of the electromagnetic check valve is linked to a drive switch of the apparatus.

Further, the invention according to claim 5 is characterized in that the power supply of the electromagnetic check valve is linked to a loader power switch.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a lift arm is vertically rotatable on a machine such as a tractor via a hitch, and an attachment such as a bucket is vertically rotatable at the tip of the lift arm. A hydraulic cylinder for rotating a lift arm and a hydraulic cylinder for rotating an attachment are connected to a hydraulic pump via a hydraulic circuit provided with a control valve, respectively. An electromagnetic check valve is provided in the ascending circuit.

That is, the opening and closing of the ascending circuit can be selected by the electric drive of the electromagnetic check valve, and the lift arm is prevented from lowering naturally while it is closed.

The electromagnetic check valve can be configured to be solenoid-driven between a closed position and an open position. In the closed position, the flow of hydraulic oil is interrupted even by the weight of the attachment and the lift arm, so that the lock state is established. Can be held.

Therefore, in the case of carrying a long distance without using a front loader, the arm does not descend naturally and the safety is improved.

The electromagnetic check valve may be a normally closed type, and may be disposed between the lift arm hydraulic cylinder and an ascending port of the control valve. That is, external operations and maintenance are also possible.

Further, it is preferable that the power supply of the electromagnetic check valve can be linked with a key switch on the main unit side so that a switching operation can be performed from the main unit side. The operator can operate without getting off the driver's seat or the like on the main unit side, so that it is not troublesome and the work load can be reduced.

The key switches on the machine side to be linked include, for example, a machine drive switch, that is, an engine key switch of the tractor and a power switch for a loader. The electromagnetic check valve is in the closed position, so that even if there is a leak from the control valve, the lift arm can be prevented from falling naturally.

The electromagnetic check valve is preferably provided with a manual switching lever, and even if a trouble occurs in the electric system and the electric drive of the electromagnetic check valve becomes ineffective, the operation of the front loader can be performed by operating the manual switching lever. Becomes possible.

[0020]

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

FIG. 1 is an explanatory view of the front loader according to the present embodiment, and FIG. 2 is a hydraulic circuit diagram of the front loader.

As shown in FIG. 1, a front loader 1 according to the present embodiment is detachably attached to a tractor 2 as a working machine as a working machine.

The tractor 2 has a pair of left and right front and rear wheels 23, 2
A prime mover unit 21 is disposed in front of a body frame 20 provided with 4, and a driver's cab 22 is provided immediately behind the prime mover unit 21.

A pair of right and left hitch stays 25 are provided in the middle of the body frame 20, and a hitch 26 on the machine side is erected on each of the hitch stays 25.

Then, between the upper ends of the hitch 26 of the machine,
A connection frame 27 having a portal shape as viewed from the front is straddled.

The front loader 1 is provided with the hitch 26
The work machine-side hitch 10 is detachably attached to the work machine-side hitch 10 via the docking pins 3, 3, and the base ends of the pair of left and right lift arms 4 It is pivotally attached.

An attachment hitch 50 is pivotally attached to the distal end of the lift arm 4 so as to be vertically rotatable, and a bucket 5 is detachably attached to the attachment hitch 50 as an attachment. Reference numeral 41 denotes a stand attached to the distal end of the lift arm 4.

The front loader 1 further includes a lift arm hydraulic cylinder 6 for raising and lowering the lift arms 4, 4 between the lower part of the work machine side hitch 10 on the right side in the machine body traveling direction and the middle of the lift arm 4. A rear portion of a substantially triangular support plate 42, which is provided vertically rotatably in the middle of the lift arm 4 on the right side,
A connecting rod 43 is rotatably attached to the upper part of the connecting rod 43.

In FIG. 1, reference numeral 10b denotes a pivot portion between the work machine side hitch 10 and the lift arm 4, 10a and 42a denote pivot portions between the work machine side hitch 10 of the connecting rod 43 and the support plate 42, and 42b denotes a support plate. A pivot between the lift arm 4 and the lift arm 4. By arranging these pivots 10a, 42a, 42b, and 10b so as to be the vertices of a parallelogram, the work implement side hitch 10, the lift arm 4, and the support plate A parallel link for raising and lowering the lift arm 4 is formed by the link 42 and the connecting rod 43.

With this configuration, the lift arms 4, 4 can be raised by extending the lift arm hydraulic cylinder 6, and the lift arms 4, 4 can be lowered by contracting the hydraulic cylinder 6. Can be.

The front loader 1 has lift arms 4,
The base end of the connector 13 is vertically rotatably attached to the distal end of 4, and the attachment is rotated between the distal end of the connector 13 and the support plate 42 to change the posture of the attachment. An attachment hydraulic cylinder 7 is provided. A connecting rod 44 is provided between the distal end of the connecting body 13 and the upper part of the attachment hitch 50.

With this configuration, the distal end of the attachment can be turned downward by extending the hydraulic cylinder for attachment 7. At this time, the bucket 5 as an attachment performs a dumping operation in which its tip is swung downward. On the other hand, if the attachment hydraulic cylinder 7 is contracted, a tilt operation is performed in which the tip of the bucket 5 is swung upward.

The hydraulic cylinders 6, 7 for operating the lift arms 4, 4 and the bucket 5 are connected to a hydraulic pump P in a hydraulic circuit shown in FIG.

In FIG. 2, reference numeral 8 denotes a control valve. The control valve 8 includes a lift passage switching valve 81 interposed between the lift arm hydraulic cylinder 6 and the hydraulic pump P; A bucket flow switching valve 82 is provided between the attachment hydraulic cylinder 7 and the hydraulic pump P, and a main flow switching valve 83 is provided between each of the flow switching valves 81 and 82 and the hydraulic pump P. It has. Further, proportional control valves 86 are connected to spools 84, 85 of the elevating / bucket flow path switching valves 81, 82, respectively.

Reference numeral 87 denotes an ascending port of the control valve 8, which is connected to one end of a hydraulic hose communicating with the outgoing chamber 61 of the hydraulic cylinder 6 for the lift arm. A lower port 88 of the control valve 8 is connected to one end of a hydraulic hose communicating with the return chamber 62 of the hydraulic cylinder 6 for the lift arm. Reference numeral 89 denotes a dump port of the control valve 8, which is connected to one end of a hydraulic hose that communicates with the outward chamber 71 of the hydraulic cylinder 7 for attachment. A tilt port 90 of the control valve 8 is connected to one end of a hydraulic hose communicating with the return chamber 72 of the hydraulic cylinder 7 for attachment.

The control valve 8 and the hydraulic cylinder 6 for the lift arm and the hydraulic cylinder 7 for the attachment are connected to the control valve 8 and the hydraulic cylinder 7 for the attachment through the ports 87, 88, 89, and 90 in accordance with the operation of the up / down flow path switching valve 81. In between, lift arm raising circuit R1, lift arm lowering circuit R2, bucket dump circuit R
3. A bucket tilt circuit R4 is formed. T is a tank.

In the above configuration, the gist of the present invention is that the lifting circuit R1 of the lift arm hydraulic cylinder 6 is provided.
The electromagnetic check valve 9 is provided.

That is, when the up / down flow path switching valve 81 is switched to the up position and the hydraulic pressure is applied to the up circuit R1,
The opening and closing of the lift circuit R1 can be selected by electrically driving the spool 91 of the electromagnetic check valve 9 by a solenoid, and the lift arm 4 is prevented from lowering naturally while it is closed.

The electromagnetic check valve 9 is divided into a closed position 9a provided with a check valve 9 'interposed and an open position 9b communicating with the oil passage. As described above, the position can be changed by driving the solenoid. And

In this embodiment, such an electromagnetic check valve 9 is used.
Is a normally closed type that takes the closed position 9a when the spool 91 is not operating.

The electromagnetic check valve 9 can be arranged between the lift arm hydraulic cylinder 6 and the ascending port 87 of the control valve 8, for example, inside the lift arm 4 on the right side in the machine traveling direction. The mounting position and the mounting method may be the same as the mounting configuration of the third circuit check valve described later.

In this embodiment, the power supply of the electromagnetic check valve 9 is electrically linked with an engine key (not shown) provided in the cab 22 of the tractor 2 (see FIG. 1).

Therefore, unless the engine key is operated to drive the engine, the check valve function operates, and even if hydraulic oil leaks from the control valve 8, the hydraulic oil for the lift arm The lock state can be maintained without acting. Therefore, for example, when the front loader 1 is not used as a working machine, there is no possibility that the lift arm 4 will naturally descend.

The power supply of the electromagnetic check valve 9 may be linked with a loader power switch (not shown).

Therefore, even when the vehicle is traveling on the tractor 2 without using the front loader or when the front loader 1 is transported over a long distance, the lift arm 4 does not naturally descend and is safe. .

In any case, the electromagnetic check valve 9 is of a normally closed type, and its driving power supply is linked to a key switch of the machine (tractor 2) to enable switching operation from the tractor 2 side. Thus, the operator can easily operate the electromagnetic check valve 9 without getting off the cab 22 and reduce the work load.

In this embodiment, the electromagnetic check valve 9 is provided with a manual switching lever 92.

That is, even if a trouble occurs in the electric system and the electric drive of the electromagnetic check valve 9 becomes ineffective, the operation of the manual switch lever 92 enables the front loader 1 to be operated as a working machine. is there.

As described above, according to the present embodiment, the electromagnetic check valve 9 is provided between the lift arm hydraulic cylinder 6 and the ascending port 87 of the control valve 8, so that hydraulic oil for the lift arm Leakage to the cylinder 6 can be prevented, and natural lift of the lift arm 4 can be prevented.

Further, since the electromagnetic check valve 9 can be electrically driven from the tractor 2 side, the operation is simplified, and even if the electric system fails, the electromagnetic check valve 9 is manually operated from the outside. Switching is possible. Further, maintenance of the electromagnetic check valve 9 can be easily performed from outside.

Here, a case where the third circuit cylinder 11 is provided in the front loader 1 will be described.

FIG. 3 shows a hydraulic circuit of the front loader 1 having the third circuit cylinder 11.

In this hydraulic circuit, a manually switching type of up / down flow path switching valve 81 'and a bucket flow path switching valve 82' are provided.
And, as shown, the third circuit cylinder 11
Is connected via a circuit switching valve 12 to a flow path connecting the hydraulic cylinder for attachment 7 and the control valve 8.

In this embodiment, a double-operating type leak check valve 14 is provided between the third circuit cylinder 11 and the circuit switching valve 12. That is,
A check valve 14 'is provided on each of the outward and return sides of the oil passage so that the check valve 14' on the return side does not open unless high oil pressure is applied during cylinder operation. Since the hydraulic oil does not return from the third circuit 11, the third circuit cylinder 11 does not operate at a leak level.

As shown in FIG. 4, the leak prevention check valve 14 is connected and fixed via a mounting plate 47 to a steel hydraulic pipe 46 disposed inside the lift arm 4 on the right side in the body traveling direction. ing.

That is, conventionally, a check valve is provided for each attachment. However, here, a check valve 14 for preventing leakage is provided on the lift arm 4 so that it is not necessary to provide a check valve for each attachment, thereby reducing costs. I'm trying. In addition, by removing the check valve from the attachment, the hydraulic piping of the attachment can be neatly laid out, and there is no risk of obstructing the field of view, and the check valve is not damaged by the work.

FIG. 5 shows the specific mounting of the check valve 14 for preventing leakage.

As shown, the inner surface of the lift arm 4
A mounting plate 47 having an L-shaped cross section is provided on 4a, and the leak prevention check valve 14 is mounted on the plate 47 so as to sandwich the hydraulic pipe 46 therebetween. Reference numeral 48 denotes a mounting bolt, which passes through the leak prevention check valve 14 and is screwed to the mounting plate 47.

By the way, the arrangement position and the arrangement method of the leak prevention check valve 14 described above can be applied to the above-described electromagnetic check valve 9 according to the present invention.

The third circuit cylinder 11 can be applied to, for example, an automatic docking device for attachments, a so-called automatic hitch.

That is, conventionally, the check valve is not provided in the automatic hitch, and when a force is applied to the docking pin of the automatic hitch unexpectedly, there is a possibility that the docking pin comes off due to the leak of the circuit switching valve and the attachment comes off. However, as described above, the provision of the leak prevention valve check valve 14 on the lift arm 4 makes it possible to easily apply the present invention to an automatic hitch, thereby preventing the attachment from falling off and improving safety. be able to.

In the hydraulic circuit shown in FIG. 6, reference numeral 11 'denotes an automatic hitch cylinder serving as a third circuit cylinder. The automatic hitch cylinder 11' is connected to the lift arm hydraulic cylinder 6 via a circuit switching valve 12 '. The flow path is connected to the valve 8.

A double-operating type leak check valve 14 is also provided between the automatic hitch cylinder 11 'and the circuit switching valve 12'.

The specific mounting position and mounting method of the leak prevention check valve 14 may be as described with reference to FIGS.

[0065]

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

(1) According to the first aspect of the present invention, the lift arm is vertically rotatably disposed on the machine via a hitch, and an attachment is vertically rotatable at the tip of the lift arm. Then, in a front loader in which a hydraulic cylinder for rotating the lift arm and a hydraulic cylinder for rotating the attachment are respectively connected to a hydraulic pump via a hydraulic circuit provided with a control valve, an electromagnetic check is performed on a lifting circuit of the hydraulic cylinder for the lift arm. By providing the valve, it is possible to prevent the lift arm from lowering spontaneously even if there is a leak from the control valve while opening and closing the lifting circuit is selected and closed, thereby increasing safety.

(2) According to the second aspect of the present invention, a normally closed type electromagnetic check valve is provided between the hydraulic cylinder for the lift arm and the ascending port of the control valve. Closed, there is no natural fall of the lift arm. In addition, since the lift arm hydraulic cylinder and the lift port of the control valve are provided between the lift arm hydraulic cylinder and the control valve, external maintenance can be easily performed.

(3) According to the third aspect of the present invention, the power supply of the electromagnetic check valve is linked with the key switch of the main unit, so that the operation can be switched from the main unit, and the operator can operate the switch. The operation can be performed without getting off the driver's seat on the side of the machine, and the work load can be reduced without any trouble.

(4) According to the fourth aspect of the present invention, the power supply of the electromagnetic check valve is interlocked with the drive switch of the apparatus, so that, for example, even when a long distance is conveyed without using a front loader. The safety is improved because the arm does not descend naturally.

(5) According to the fifth aspect of the present invention, the power supply of the electromagnetic check valve is linked to the power switch for the loader, so that when the switch is turned off, the lift arm can be prevented from falling naturally. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a front loader according to the present embodiment.

FIG. 2 is an explanatory diagram showing a hydraulic circuit of the front loader.

FIG. 3 is an explanatory diagram illustrating an example of a hydraulic circuit when a third circuit is provided.

FIG. 4 is an explanatory view showing a mounting state of a check valve for preventing leakage in a side view.

FIG. 5 is an explanatory diagram of a mounting plate of a check valve for preventing leakage as viewed from the front.

FIG. 6 is an explanatory diagram when the third circuit is applied to an automatic hitch cylinder.

[Explanation of symbols]

P Hydraulic pump R1 Lift circuit (lift arm lift circuit) 1 Front loader (work equipment) 2 Tractor (this machine) 4 Lift arm 5 Bucket (attachment) 6 Hydraulic cylinder for lift arm (hydraulic cylinder for lift arm rotation) 7 Attachment Hydraulic cylinder (hydraulic cylinder for rotating attachment) 8 Control valve 9 Solenoid check valve 10 Hitch for work machine 26 Hitch for machine

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masakazu Komatsu 1-32 Chaya-cho, Kita-ku, Osaka-shi, Osaka F-term in Yanmar Agricultural Machinery Co., Ltd. 2D003 AA01 AB03 AB04 BA07 CA06 DA04 EA04

Claims (5)

[Claims] A lift arm is vertically rotatably arranged on the machine via a hitch, and an attachment is vertically rotatable at an end of the lift arm. A hydraulic cylinder for rotating the lift arm is provided. A front loader in which a hydraulic cylinder for rotating an attachment is connected to a hydraulic pump via a control valve, wherein an electromagnetic check valve is provided in a lifting circuit of the hydraulic cylinder for a lift arm. 2. The front loader according to claim 1, wherein a normally closed type electromagnetic check valve is provided between the lift arm hydraulic cylinder and an ascending port of the control valve. 3. The front loader according to claim 1, wherein the power supply of the electromagnetic check valve is linked to a key switch of the apparatus. 4. The front loader according to claim 3, wherein a power supply of the electromagnetic check valve is linked to a drive switch of the apparatus. 5. The front loader according to claim 3, wherein the power of the electromagnetic check valve is linked to a power switch for the loader.