JPH09290999A - Mechanism for horizontally setting fork of wheel loader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically set a fork in a horizontal direction when a fork lift equipment is erected from the condition where a mast is tilted rearward. SOLUTION: In a wheel loader in which a fork lift equipment of a mast structure capable of being tilted in the longitudinal direction by expanding/ contracting a tilt cylinder 10 in place of a shovel equipment, a horizontal condition detector 14 to detect the horizontal condition of 21 fork, and an electromagnetic detent 30 in which a spool 34S of a mast tiltation switch valve 34 is kept at the mast forward tilted position by forwardly tilting the mast tiltation switch valve 34 to control the tiltation in the longitudinal direction of the mast, and the spool 34S of the mast tiltation switch valve 34 is returned to the neutral position by detecting the horizontal condition of the fork of the horizontal condition detector 14, are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fork leveling mechanism for easily setting a fork of a forklift device in a horizontal state in a wheel loader equipped with a forklift device instead of a shovel device.

[0002]

2. Description of the Related Art A wheel loader is equipped with large low-pressure tires, has a high minimum ground clearance of a running body, and is of all-wheel drive so that it can be run or work on rough terrain or soft ground. Taking advantage of such characteristics not found in ordinary forklift trucks, a wheel loader equipped with a forklift device with a mast structure in place of the shovel device at the front of the wheel loader's vehicle body is suitable for cargo handling work on uneven terrain. Is used for.

In a wheel loader equipped with a forklift device instead of a shovel device, a hydraulic directional control valve for controlling the shovel device is generally used as a hydraulic directional control valve for controlling the forklift device.

By the way, the wheel loader adopts a vehicle body bending type steering system in which a front frame and a rear frame are flexibly connected at a center of a vehicle body by a center pin.
The driver's seat is located on the rear frame side, and work devices such as a shovel device and a forklift device are arranged at the front end of the front frame. Therefore, when the forklift device is mounted on the wheel loader, the driver's seat and the forklift device are separated from each other as compared with a general forklift truck.

In a wheel loader equipped with such a forklift device, when the mast of the forklift device is tilted backward, the operator moves the mast forward and tilts the fork horizontally for loading and unloading work. Visually determines whether or not the mast has become vertical, but it is difficult to make that determination because the mast is far from the operator, and cargo handling work may be performed with the fork not horizontal.

If the fork handling work is performed in a state where the fork is not horizontal, the fork cannot be sufficiently inserted into the pallet or the like during loading, and the fork cannot be completely pulled out during unloading, and the operator controls the longitudinal inclination of the mast. It was necessary to make fine adjustments to the operating lever and make adjustments.

With respect to the shovel device which is the original working device of the wheel loader, when the bucket is tilted forward to discharge the load on the truck or the like, the bucket is tilted backward. , To the position where the bottom of the bucket is horizontal, so that loading work is easy,
It is provided with a horizontal setting mechanism for the bottom surface of the bucket, which holds the spool of the hydraulic directional control valve that controls the forward and backward tilting of the bucket as it is at the rearwardly inclined position and returns the spool of the hydraulic directional control valve to the neutral position when the spool is horizontal.

Therefore, it is conceivable to use the horizontal setting mechanism of the bottom surface of the bucket for the fork horizontal setting mechanism. In that case, the direction of operating the horizontal setting mechanism is such that when the bucket of the shovel device is tilted backward, Since the mast of the device is in the opposite direction to that when tilted forward, the operating direction of the operating lever must be the same when tilting the bucket of the shovel device backward and when tilting the mast of the forklift device forward, resulting in erroneous operation. Easy and not preferable for safety.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a wheel loader equipped with a forklift device when the mast of the forklift device is tilted backward from a traveling state and the mast is erected for loading work to level the fork. , Once the mast is tilted forward, the mast can be automatically tilted forward until the fork is horizontal, and when the fork is horizontal, the tilting can be stopped, and the operator can tilt the mast forward and backward. (EN) Provided is a fork level setting mechanism for a wheel loader, which does not need to finely operate and adjust the operation lever for controlling the fork, and can easily insert a fork into a pallet during loading and extract a fork during unloading. With the goal.

It is another object of the present invention to provide an inexpensive fork leveling mechanism for a wheel loader that can be used without causing an erroneous operation.

[0011]

A fork horizontal setting mechanism for a wheel loader according to the present invention is a wheel loader equipped with a forklift device having a mast structure capable of tilting forward and backward by expanding and contracting a tilt cylinder instead of a shovel device. The spool of the hydraulic directional control valve is held at the forward tilted position of the mast by operating the horizontal detector that detects the horizontal state and the forward tilt of the mast of the hydraulic directional control valve that controls the tilting movement of the mast. Holding means for returning the spool of the hydraulic pressure direction switching valve to the neutral position by detecting the horizontal state of the fork of the detector.

From the traveling state in which the mast of the forklift device is tilted rearward, when the mast is tilted forward to stand up and the fork is leveled for loading and unloading work, the operator operates a hydraulic direction switching valve for controlling the longitudinal tilt of the mast. Operate the mast forward. Once the hydraulic directional control valve is operated to the mast forward tilting side, the spool of the hydraulic directional control valve is held at the mast forward tilted position by the holding means, and the mast continues to tilt forward.

When the fork becomes horizontal, the holding means releases the holding by detecting the horizontal state of the horizontal detector, and the spool of the hydraulic directional control valve returns to the neutral position, so that the tilting of the mast is stopped and the fork automatically moves. Set horizontally.

Therefore, it is not necessary for the operator to finely operate and adjust the operation lever for controlling the longitudinal inclination of the mast, and it is possible to easily insert the fork into the pallet for loading and to pull out the fork when unloading. .

When a hydraulic direction switching valve for controlling the front-back tilting of the bucket of the shovel device is used as the hydraulic direction switching valve for controlling the front-back tilting of the mast, and a holding means for the horizontal setting mechanism on the bottom surface of the bucket of the shovel device is used as the holding means. A reverse link is provided between the spool of the hydraulic directional control valve and the operating lever to transmit the operation of the operating lever to the spool in the reverse direction.

When the operation lever is tilted forward and backward, the operating lever is operated in the same direction as when the bucket of the shovel device is tilted forward and backward. The spool of the hydraulic directional control valve that is controlled operates in the opposite direction to the operation of the operation lever in the same direction when the bucket is tilted and when the mast is tilted. The holding means that operates by the backward tilting operation in the setting mechanism can operate by the forward tilting operation in the fork horizontal setting mechanism of the forklift device.

Therefore, when mounting the forklift device, since the parts of the horizontal setting mechanism on the bottom surface of the bucket of the shovel device can be used, an inexpensive fork horizontal setting mechanism can be obtained, and either the shovel device or the forklift device is used as the working device. Even when it is attached, the operator can operate with a common operating lever in common in the operating direction, so that erroneous operation can be prevented and safety can be improved.

[0018]

1 is a side view of the vicinity of a forklift device of a wheel loader equipped with a forklift device according to an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram when the shovel device is installed, and FIG. 3 is a forklift. Fig. 4 is a hydraulic circuit diagram when the device is installed, Fig. 4 is an explanatory view of a connection state between the spool of the hydraulic direction switching valve and the operating lever when the forklift device is mounted, and Fig. 5 is a spool and operation of the hydraulic direction switching valve when the shovel device is mounted. It is explanatory drawing of the connection state with a lever.

The wheel loader comprises a front frame 1 of the vehicle body.
In addition, a shovel device (not shown) as a working device and a forklift device 2 having a mast structure are detachable and replaceable. As shown in FIG. 1, the forklift device 2 has a known mast structure and has a mast 4 including an outer mast 5 and an inner mast 6, a carriage bracket 7 supported by the inner mast 6, a fork 8 attached to the carriage bracket 7, and a load collapse prevention. The inner cylinder 6 is provided with a backrest 9 for use, and the inner cylinder 6 is moved up and down by expansion and contraction of the lift cylinder 3 provided between the outer mast 5 and the inner mast 6. When the inner mast 6 moves up and down, the carriage bracket 7, the fork 8 and the backrest 9 supported by the inner mast 6 move up and down at the same time.

When the forklift device 2 is mounted on the front frame 1, the mast 4 of the forklift device 2 is
Between the front frame 1 and the front frame 1, a pair of left and right tilt cylinders 10 for tilting the mast 4 back and forth are provided.

On the cross beam 11 of the outer mast 5,
A magnetic metal piece 12 is attached, and a magnetic metal detector 13 is attached to the front frame 1 of the vehicle body.
The magnetic metal detector 13 has a normally open contact, and in combination with the magnetic metal piece 12, the contact is closed only when the mast 4 is in the backward tilted state, and the contact is opened when the mast 4 is vertical. By setting the positions of the metal piece 12 and the magnetic metal detector 13, a horizontal detector 14 that detects that the fork is in a horizontal state is configured.

The horizontal detector 14 can detect any angle other than horizontal by adjusting the positions of the magnetic metal piece 12 and the magnetic metal detector 13.
In the wheel loader, a pair of left and right booms are attached to the front frame 1 of the vehicle body in a state where the shovel device, which is the original working device thereof, is attached, and a bucket is provided at the tip of the lift arm. . The boom can be moved up and down by the expansion and contraction of the boom cylinder 16, and the bucket can be tilted rearward and forward by the expansion and contraction of the bucket cylinder 17 attached via the bucket link.

In this state, the hydraulic circuit for driving the shovel device of the wheel loader is as shown in FIG. That is, the hydraulic oil tank 21,
A hydraulic pump 22, a boom up / down switching valve 23, and a bucket tilt switching valve 24 are provided, and the hydraulic pump 22 is provided at pump ports of the boom up / down switching valve 23 and the bucket tilt switching valve 24.
Of the boom up / down switching valve 23 and the bucket tilt switching valve 24.
Are connected to the hydraulic oil tank 21.

Bottom side oil chamber 16B of the boom cylinder 16
An ascending pipeline 19 is connected to the boom raising / lowering switching valve 23 from one service port. To the rod-side oil chamber 16R of the boom cylinder 16, the descending pipeline 20 is connected from the other service port of the boom up / down switching valve 23.

Further, a bucket rearward tilt pipe 25 is connected to the bottom side oil chamber 17B of the bucket cylinder 17 from one service port of the bucket tilt switching valve 24. A bucket forward tilt conduit 26 is connected to the rod side oil chamber 17R of the bucket cylinder 17 from the other service port of the bucket tilt switching valve 24.

The boom raising / lowering switching valve 23 is a four-position manually operated hydraulic pressure direction switching valve, and can be switched among four positions of up, neutral, down and float by operating the operation lever 23L. When the boom up / down switching valve 23 is switched to the raised position, the ascending pipeline 19 communicates with the discharge pipeline 27 of the hydraulic pump 22, and the descending pipeline 20 communicates with the return pipeline 28. Bottom side oil chamber 16
B flows in and flows out of the rod side oil chamber 16R, the boom cylinder 16 extends, and the boom rises.

When the boom raising / lowering switching valve 23 is switched to the lowered position, the descending pipeline 20 communicates with the discharge pipeline 27 of the hydraulic pump 22, and the ascending pipeline 19 communicates with the return pipeline 28.
The hydraulic oil flows into the rod side oil chamber 16R of the boom cylinder 16 and flows out from the bottom side oil chamber 16B, the boom cylinder 16 is shortened, and the boom is lowered.

When the boom up / down switching valve 23 is switched to the float position, both the ascending pipeline 19 and the descending pipeline 20 communicate with the return pipeline 18, so that the boom cylinder 16 is shortened by the weight of the shovel device and the boom descends. To do.

The bucket tilt switching valve 24 is a three-position manually operated hydraulic directional switching valve, and can be switched to three positions of backward tilting, neutral position, and forward tilting by operating the operating lever 24L. When the bucket tilt switching valve 24 is switched to the backward tilt position, the bucket rear tilt pipe line 25 communicates with the discharge pipe line 27 of the hydraulic pump 22, and the bucket front tilt pipe line 26 returns to the return pipe line 28.
Hydraulic fluid flows into the bottom side oil chamber 17B of the bucket cylinder 17, flows out from the rod side oil chamber 17R, the bucket cylinder 17 extends, and the bucket tilts backward.

When the bucket tilt changeover valve 24 is switched to the forward tilt position, the bucket forward tilt conduit 26 communicates with the discharge conduit 27 of the hydraulic pump 22, and the bucket backward tilt conduit 25 returns to the return conduit 2.
8, the working oil flows into the rod side oil chamber 17R of the bucket cylinder 17 and flows out from the bottom side oil chamber 17B, so that the bucket cylinder 7 shortens and the bucket tilts forward.

With regard to this shovel device, when the bucket tilt switching valve 24 is switched to the backward tilt position, the electromagnetic detent 30 and the horizontal detector 31 that hold the spool 24S at that position by utilizing the attraction force of the electromagnet. It is equipped with a horizontal setting mechanism on the bottom of the bucket.

When the bucket is tilted forward to discharge the load on the truck or the like and then the bucket is tilted backward, the electromagnetic detent 30 moves the bucket tilt switching valve 24 to the position where the bottom surface of the bucket becomes horizontal. Spool 24S
When the horizontal detector 31 detects that the bottom surface of the bucket is horizontal, the electromagnetic detent 30 is deenergized and the spool 24S of the bucket tilt switching valve 24 is returned to the neutral position.

With the forklift device 2 installed, the hydraulic circuit for driving the forklift device 2 of the wheel loader is as shown in FIG. In this hydraulic circuit, the hydraulic oil tank 21, the hydraulic pump 22, and the boom up / down switching valve 2 used in the hydraulic circuit for driving the shovel device are used.
3. The bucket tilt switching valve 24 is used as the hydraulic oil tank 21, the hydraulic pump 22, the fork lift switching valve 33, and the mast tilt switching valve 34.

The fork lift switching valve 33 and the mast tilt switching valve 34 have pump ports at the pump ports 2 of the hydraulic pump 22.
7, the return pipe 28 is connected to the hydraulic oil tank 21 from the return ports of the fork lift switching valve 33 and the mast tilt switching valve 34.

An ascending pipeline 19 is connected to the bottom side oil chamber 3B of the lift cylinder 3 from one service port of the fork lift switching valve 33. Since the lift cylinder 3 is a single-acting cylinder, the other service port of the fork lift switching valve 33 is connected to the return line 28.

Further, to the bottom side oil chamber 10B of the tilt cylinder 10, a mast forward tilt pipe line 35 is connected from one service port of the mast tilt switching valve 34. A mast rearward tilting conduit 36 is connected to the rod side oil chamber 10R of the tilt cylinder 10 from the other service port of the mast tilt switching valve 34.

Since the fork lifting / lowering switching valve 33 uses the boom lifting / lowering switching valve 23, it is a 4-position manually operated hydraulic pressure directional switching valve. By operating the operating lever 33L,
It is possible to switch among four positions of rising, neutral, descending and float. When the fork lift switching valve 33 is switched to the raised position, the lift pipe 19 communicates with the discharge pipe 27 of the hydraulic pump 22, so that the working oil flows into the bottom side oil chamber 3B of the lift cylinder 3 and the lift cylinder 3 moves. Extend and fork 8
Rises.

When the fork raising / lowering switching valve 33 is switched to the lowered position, the ascending pipe line 19 communicates with the return pipe line 28.
The hydraulic oil flows out from the bottom side oil chamber 3B of the lift cylinder 3, the lift cylinder 3 is shortened, and the fork 8 descends.

Since the mast tilt changeover valve 34 uses the bucket tilt changeover valve 24, it is a 3-position manually operated hydraulic pressure direction changeover valve, and by operating the operation lever 34L,
It can be switched to three positions: backward tilt, neutral, and forward tilt. When the mast tilt changeover valve 34 is switched to the rearward tilt position, the mast rearward tilt line 36 communicates with the discharge line 27 of the hydraulic pump 22,
Since the mast forward tilt pipe line 35 communicates with the return pipe line 28, hydraulic oil flows into the rod side oil chamber 10R of the tilt cylinder 10 and flows out from the bottom side oil chamber 10B, and the tilt cylinder 10 is shortened. 4 leans back.

When the mast tilt changeover valve 34 is switched to the forward tilt position, the mast forward tilt conduit 35 communicates with the discharge conduit 27 of the hydraulic pump 22, and the mast rear tilt conduit 36 communicates with the return conduit 28. Since the hydraulic oil flows into the bottom side oil chamber 10B of the tilt cylinder 10 and flows out from the rod side oil chamber 10R, the tilt cylinder 10 extends and the mast 4 leans forward.

In this forklift device 2, when the bucket tilt switching valve 24 of the shovel device is switched to the backward tilt position, the electromagnetic detent 30 that holds the spool 24S at that position by utilizing the attraction force of the electromagnet is tilted by the mast. When the switching valve 34 is switched to the forward tilt position, it is used as a holding means for holding the spool 34S at that position, and this electromagnetic detent 30 is used as the magnetic metal detector 1 of the horizontal detector 14.
By connecting to 3, the fork horizontal setting mechanism is configured.

From the traveling state in which the mast 4 of the forklift device 2 is tilted rearward, when the mast 4 is tilted forward to stand up and the fork 8 is leveled for cargo handling work, the operator operates the operation lever of the mast tilt switching valve 34. Operate 34L to the front of the mast. Once the mast tilt changeover valve 34 is operated to the front tilt side of the mast, the horizontal detector 1 is operated in the rear tilt state.
Since the contact of the magnetic metal detector 13 of 4 is closed,
The electromagnetic detent 30 holds the spool 34S at the mast forward tilt position as it is, and the mast 4 continues to tilt forward.

When the fork 8 is in a horizontal state, the contact of the magnetic metal detector 13 is opened and the electromagnetic detent 30 is de-energized, and the spool 34S of the mast tilt switching valve 34 returns to the neutral position, so that the mast 4 tilts. Is stopped fork 8
Is automatically set horizontally.

To use the bucket tilt switching valve 24 of the shovel device as the mast tilt switching valve 34 and the electromagnetic detent 30 of the shovel device as the holding means of the fork horizontal setting mechanism, the spool 34 of the mast tilt switching valve 34 is used.
A reverse rotation link 40 is provided between S and the operation lever 34L to transmit the operation of the operation lever 34L to the spool 34S in the reverse direction.

In this reversing link 40, as shown in FIG. 4, one end of a link arm 41 rotatably supported by a base plate 48 has a ball joint 42 and a bifurcated joint 4.
3 is connected to the spool 34S via the link arm 4
The other end of the control lever 3 has a ball joint 44 at its other end.
It is connected to a control cable 45 that expands and contracts by 4L. This reversing link 40 has a base plate 48.
Is detachably attached to a boss 46 fixed to the vehicle body of the wheel loader with bolts 47. When the shovel device is attached, the reverse link 40 is removed and the control cable 45 is attached to the ball joint 4 as shown in FIG.
Connect directly to 2.

As described above, by the reverse rotation link 40, the spool 24S of the bucket tilt switching valve 24 and the spool 34S of the mast tilt switching valve 34 have the same operation lever when the bucket is tilted and when the mast 4 is tilted. Since it operates in the opposite direction to the operation in the direction, the holding means that operates by the backward tilt operation in the bucket bottom level setting mechanism of the shovel device operates by the forward tilt operation in the fork horizontal setting mechanism of the forklift device. become able to.

Therefore, when the forklift device 2 is mounted, since the horizontal level setting mechanism of the bottom surface of the bucket of the shovel device can be used, an inexpensive fork level setting mechanism can be obtained, and either the shovel device or the forklift device 2 can be used as the working device. Even when it is attached, the operator can operate with a common operating lever (24L = 34L) in common in the operating direction, so that erroneous operation can be prevented and safety can be improved.

[0048]

As described above, according to the fork horizontal setting mechanism for a wheel loader of the present invention, in a wheel loader equipped with a forklift device, the mast of the forklift device can be used for loading and unloading work when the mast is tilted backward. When erecting the mast and leveling the fork,
It is possible to tilt the mast forward until the fork is horizontal and then stop the tilt when the fork is horizontal by a single operation of tilting the mast forward. It is not necessary to finely operate and adjust the operation lever that controls the fork, and it is possible to easily insert the fork into the pallet during loading and to remove the fork during unloading.

Further, when the forklift device is mounted, the hydraulic directional control valve for controlling the longitudinal tilting of the mast is a hydraulic directional switching valve for controlling the longitudinal tilting of the bucket of the shovel device, and the holding means is a horizontal bottom surface of the bucket of the shovel device. By using the holding means of the setting mechanism and providing a reverse link between the spool of the hydraulic directional control valve and the operating lever, which reverses the direction of the operation of the operating lever and transmits it to the spool, Since the parts of the horizontal setting mechanism can be used, an inexpensive fork horizontal setting mechanism can be obtained, and even if either the shovel device or the forklift device is installed as the working device, the operator can use the common operating lever to have a common operation direction. Since it can be operated by holding it, erroneous operation can be prevented and safety can be improved.

[Brief description of drawings]

FIG. 1 is a side view of the vicinity of a forklift device of a wheel loader equipped with a forklift device according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram when the shovel device is attached.

FIG. 3 is a hydraulic circuit diagram when the forklift device is attached.

FIG. 4 is an explanatory view of a connection state between a spool of a hydraulic directional control valve and an operating lever when a forklift device is attached.

FIG. 5 is an explanatory view of a connection state between a spool of a hydraulic directional control valve and an operating lever when the shovel device is attached.

[Explanation of symbols]

 1 Front Frame 2 Forklift Device 3 Lift Cylinder 4 Mast 5 Outer Mast 6 Inner Mast 7 Carriage Bracket 8 Fork 10 Tilt Cylinder 12 Magnetic Metal Piece 13 Magnetic Metal Detector 14 Horizontal Detector 16 Boom Cylinder 17 Bucket Cylinder 19 Ascending Pipeline 21 Hydraulic Oil Tank 22 Hydraulic pump 23 Boom up / down switching valve 24 Bucket forward / backward switching valve 24L Operating lever 24S Spool 27 Discharge pipeline 28 Return pipeline 30 Electromagnetic detent 31 Horizontal detector 33 Fork lifting switching valve 34 Mast tilt switching valve 34L Operating lever 34S Spool 35 Mast forward tilt line 36 Mast rear tilt line 40 Reverse link

Claims (2)

[Claims] 1. In a wheel loader equipped with a forklift device having a mast structure capable of tilting forward and backward by expanding and contracting a tilt cylinder, instead of the shovel device, a horizontal detector for detecting that the fork is in a horizontal state, and a mast of the mast. By holding the spool of the hydraulic directional control valve in the forward tilted position of the mast by operating the hydraulic directional control valve that controls forward and backward tilting, the hydraulic directional control valve is detected by detecting the horizontal state of the fork of the horizontal detector. And a holding means for returning the spool to a neutral position, the horizontal fork setting mechanism of the wheel loader. 2. A hydraulic directional control valve for controlling the longitudinal tilting of the mast is used for the hydraulic directional control valve for controlling the longitudinal tilting of the mast, and a holding means for the horizontal setting mechanism on the bottom surface of the bucket of the shovel device is used for the holding means. 2. A fork horizontal setting for a wheel loader according to claim 1, further comprising a reverse link provided between the spool of the hydraulic directional control valve and the operating lever, the reverse link transmitting the operation of the operating lever to the spool by reversing the direction. mechanism.