JP2003267682A - Forklift truck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase forward visibility by improving a piping structure to cylinders disposed on a lift bracket. <P>SOLUTION: The lift bracket 6 is mounted with a solenoid-operated control valve 32 for controlling flows of hydraulic fluid from a hydraulic power source 13 to the hydraulic cylinders 11 and 12 disposed on the lift bracket 6 in response to an operation of operating levers 22a and 22b disposed on a vehicle body 2. Hoses 29a and 29b for supplying and recovering hydraulic fluid between the hydraulic power source 13 and the solenoid-operated control valve 32 are entrained about a rotatable pulley 30 hung from a mast 5, and are each connected to the hydraulic power source 13 and the solenoid-operated control valve 32. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forklift equipped with a hydraulic device for cargo handling work.

[0002]

2. Description of the Related Art Conventionally, a forklift having a structure shown in FIGS. 5 and 6, for example, has been known. That is, a reach type forklift 1 which is a kind of forklift shown in FIG. 5 has a body frame 2 which constitutes a vehicle body.
And a pair of left and right straddle arms 3 extending forward at the bottom of the body frame 2, and these straddle arms 3
In between, a carriage 4 mounted so as to be movable in the front-rear direction of the vehicle, a pair of left and right masts 5 standing upright in front of the carriage 4 and arranged in front of the vehicle body frame 2, and guiding to these masts 5. The lift bracket 6 is mounted so as to be lifted and lowered, and a pair of left and right forks 7 mounted on the lift bracket 6. Then, for example, the fork 7 is inserted from the tip into a through hole provided in the pallet and the pallet is placed on the fork 7.

On the carriage 4, a pair of lift cylinders 8 which are operated by hydraulic pressure to move the lift bracket 6 up and down are arranged in parallel with the mast 5, and at the bottom of the vehicle body frame 2, the vehicle body is mounted. A reach cylinder 9 (not shown) that is installed between the rear end of the frame 2 and the carriage 4 and that moves the carriage 4 in the front-rear direction and that is operated by hydraulic pressure is provided.

A fork 7 is supported on the lift bracket 6 by a shaft 10 (not shown), and a fork is provided by a tilt cylinder 11 (not shown) provided on the lift bracket 6 and operated by hydraulic pressure. 7 is tilted in the vertical direction about the shaft 10. Further, the lift bracket 6 has a shaft 10
There is provided a side shift cylinder 12 (not shown) that is hydraulically actuated to slide the fork 7 in the left-right direction along.

A hydraulic device 13 (not shown) as a hydraulic source for supplying hydraulic oil to the lift cylinder 8, the reach cylinder 9, the tilt cylinder 11, and the side shift cylinder 12 is provided in the body frame 2. A side cover 14 that covers the sides of the hydraulic device 13 and a top cover 15 that covers the upper side of the hydraulic device 13 are provided. Here, the hydraulic device 13 includes an oil tank 16 (not shown) in which hydraulic oil is stored, and a pump 17 (not shown) that sucks and pressurizes the hydraulic oil from the oil tank 16.
And a motor 18 (not shown) that drives this pump 17.
It is composed of and. Furthermore, body frame 2
A control valve 19 (not shown) for controlling the supply of hydraulic oil from the hydraulic device 13 to each cylinder is provided therein.

Further, the rear right side of the vehicle body frame 2 serves as a driver's seat 20, and a steering handle 21 for steering the vehicle is provided above the top cover 15 and on the left side of the driver's seat 20. Various operating levers 22 and accelerator levers for operating the control valve 19 are provided on the front side of the.

On the other hand, a hose for supplying and collecting hydraulic oil is provided between the control valve 19 and each cylinder.

Here, since the tilt cylinder 11 and the side shift cylinder 12 are constructed so as to move up and down together with the lift bracket 6, the hoses 23a for supplying and recovering the working oil to the tilt cylinder 11 and the side shift cylinder 12 are provided. Each of 23b, 24a, and 24b is provided so as to be able to cope with this lifting operation. That is, as shown in FIG. 6, the hoses 23a, 23b, 24
a and 24b are rotatable pulleys 2 suspended on a mast 5.
It is in a state of being hung on 5, 26.

[0009]

However, in the conventional construction in which the hose is hung on the pulley, the larger the number of cylinders arranged in the lift bracket 6, the larger the number of hoses, and as a result, the hose provides a forward view. There is a problem that the workability is deteriorated due to the blockage, for example, it becomes difficult for the operator to visually recognize the tip position of the fork 7. That is, the lift cylinder 6 and the tilt cylinder 1
1 and the side shift cylinder 12 are provided, the hoses provided are the hoses 23a, 23b, 24a, 2
4b in total, but since they are hung on the pulleys 25 and 26, 8 hoses obstruct the forward field of view.

Further, in the high lift type mast, since all the hoses connected to the cylinders mounted on the lift bracket 6 must be lengthened, the piping loss due to the hoses increases and the efficiency decreases. There are also problems.

This problem is not limited to the case where the tilt cylinder 11 and the side shift cylinder 12 are mounted on the lift bracket 6, but instead of these cylinders, other cylinders, for example, the fork 7 during cargo handling work. The same problem occurs when an attachment device cylinder for driving an attachment device used in association with each other is provided.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to improve the piping structure to the cylinder provided in the lift bracket to improve the forward visibility.

[0013]

In order to achieve the above-mentioned object, the invention of claim 1 is provided with a lift bracket which can be moved up and down along a mast mounted in front of a vehicle body, and the lift bracket is provided with left and right lift brackets. A forklift provided with a pair of forks and a plurality of hydraulic cylinders for hydraulically driving the forks, and a forklift including a hydraulic source for supplying hydraulic oil to the vehicle main body is provided in the vehicle main body. An electromagnetic control valve that controls the flow of hydraulic oil from the hydraulic source to the hydraulic cylinder according to the operation of the operation lever is disposed on the lift bracket, and between the hydraulic source and the electromagnetic control valve. A hose for supplying and collecting hydraulic oil is hung on a rotatable pulley suspended on the mast and Characterized in that it is connected to the source and the electromagnetic control valve.

According to this structure, since the electromagnetic control valve is arranged on the lift bracket, the pipe between the hydraulic source and the hydraulic cylinder provided on the lift bracket is connected to the hydraulic source and the electromagnetic type. It can be configured with a hose provided between the control valve and a hose provided between the electromagnetic control valve and the hydraulic cylinder. And, the hose that should be provided so as to correspond to the lifting operation of the lift bracket is the hose between the hydraulic power source and the electromagnetic control valve.This hose is hung on the rotatable pulley suspended on the mast and Since they are respectively connected to the hydraulic pressure source and the electromagnetic control valve, the lift bracket can be raised and lowered without any trouble. Therefore, irrespective of the number of hydraulic cylinders provided in the lift bracket, only two hoses for hooking the pulley are provided, that is, the hose for supplying hydraulic oil from the hydraulic source to the electromagnetic control valve and the hydraulic source from the electromagnetic control valve. Since this is a hose for collecting hydraulic oil, it is possible to prevent the front field of view from being blocked by a large number of hoses as in the conventional case.

According to a second aspect of the present invention, there is provided the forklift according to the first aspect, further comprising a hydraulic circuit for supplying hydraulic fluid from the hydraulic source to another hydraulic cylinder different from the hydraulic cylinder, An electromagnetic shutoff valve capable of opening the hydraulic circuit according to the operation of the lever is provided.

According to this structure, the hydraulic circuit can be opened by the electromagnetic shut-off valve in response to the operation of the operation lever, and the supply of hydraulic oil to other hydraulic cylinders can be cut off. Therefore, when it is not necessary to supply hydraulic oil to other hydraulic cylinders while the operating lever is being operated, or the operation of the hydraulic cylinders provided on the lift bracket is given priority over the operation of other hydraulic cylinders. If desired, the hydraulic circuit can be opened so that the hydraulic oil is supplied only to the hydraulic cylinder provided in the lift bracket.

According to a third aspect of the present invention, in the forklift according to the first or second aspect, the hydraulic cylinder includes a tilt cylinder that tilts the fork vertically and a side shift cylinder that slides the fork horizontally. Or a cylinder for an attachment device, which is provided on the lift bracket and drives an attachment device used in association with the fork.

According to this structure, when the tilt bracket and the side shift cylinder or the cylinder for the attachment device are provided in the lift bracket,
Instead of providing a hose between the hydraulic source and each of the above cylinders, provide a hose between the hydraulic source and the electromagnetic control valve and a hose between the electromagnetic control valve and each of the above cylinders. Thus, the supply and recovery of the hydraulic oil to each of the above cylinders can be performed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a reach type forklift will be described below with reference to FIGS. Here, FIG. 1 is a perspective view showing a main part of a mast in the present embodiment, FIG. 2 is a front view showing a lift bracket in the present embodiment, and FIG. 3 is a hydraulic circuit diagram showing the present embodiment. FIG. 4 is a block diagram showing a control system in this embodiment. The same structure as the conventional reach type forklift will be described with reference to FIG.

As shown in FIG. 5, the reach type forklift 1 according to the present embodiment has a pair of left and right straddle arms 3 extending forward from the lower portion of the vehicle body frame 2, and both straddle arms 3 are provided with the straddle arms 3. Are provided with reach rails in the extending direction. A carriage 4 is mounted between the straddle arms 3 and is movable back and forth along the reach rail. A pair of left and right masts 5 are provided upright on the front portion of the carriage 4, and a lift bracket 6 guided by these masts 5 is provided. The lift bracket 6 is provided with a pair of left and right forks 7. Also, the carriage 4
In the carriage 4, a pair of left and right lift cylinders 8 for moving the lift bracket 6 up and down are arranged along the mast 5.
A reach cylinder 9 which is erected upright and is installed at a lower portion of the vehicle body frame 2 between a rear end portion of the vehicle body frame 2 and the carriage 4 to move the carriage 4 in the front-rear direction.
(Not shown).

A road wheel 40 is rotatably provided at the tip of each straddle arm 3.
Drive wheels 41 for traveling and steering and caster wheels 42 for auxiliary are arranged on the rear bottom surface of the body frame 1. A rear right portion of the body frame 2 is opened rearward as a driver's seat 20 on which an operator rides. Inside the body frame 2, although not shown in FIG. A hydraulic device 13 (not shown) that supplies hydraulic oil to the cylinder, a control device 28 (not shown) that controls these devices, and a battery are mounted. The rear side portion of the vehicle body frame 1 is covered with an openable / closable side cover 14, and the upper portion of the vehicle body frame 1 is entirely covered with a top cover 15.

Further, a steering handle 21 for steering the vehicle is provided above the top cover 15 on the left side of the driver's seat 20, and various operations are performed on the front side of the driver's seat 20 so as to project from the top cover 15. A lever 22 and an accelerator lever are provided. A head guard 43 for protecting the driver from falling objects is arranged so as to cover the driver seat 20 and the top cover 15.

By the way, as shown in the hydraulic circuit diagram of FIG. 3, the hydraulic device 13 as the hydraulic source mounted in the vehicle body frame 2 includes an oil tank 16 for storing hydraulic oil, and this oil. A pump 17 that pressurizes and discharges the hydraulic oil sucked from the tank 16, and a motor 18 that receives electric power from a battery and drives the pump 17.
It is composed of and. Then, as shown in FIGS. 1 and 3, the supply of the hydraulic oil from the hydraulic device 13 to each cylinder provided on the lift bracket 6 is performed by the hose 29a.
The hydraulic oil is collected from the cylinders provided in the lift bracket 6 to the hydraulic device 13 via the hose 29.
It is designed to be performed via b. Also, hose 2
9a and 29b are hung on a rotatable pulley 30 suspended from the mast 5, so that the lift bracket 6 can be moved up and down.

In the body frame 2, the hydraulic system 1
A control valve 31 for controlling the supply of hydraulic oil from the lift cylinder 8 and the reach cylinder 9 is provided, and the control valve 31 is connected to the lift cylinder 8 and the reach cylinder 9. Then, a pipe connecting the hydraulic device 13 and the control valve 31 and a pipe connecting the control valve 31 and the control valve 31, the lift cylinder 8 and the reach cylinder 9 to the other hydraulic cylinders according to the present invention. A hydraulic circuit that supplies hydraulic oil from a source is configured.

As shown in FIG. 2, a pair of left and right forks 7 are supported on the lift bracket 6 by a shaft 10, and a double-acting tilt operated by hydraulic pressure provided on the lift bracket 6 is used. Cylinder 11
Thus, the fork 7 is tilted in the vertical direction about the shaft 10. Further, the fork 7 is slid on the lift bracket 6 along the axis 10 in the left-right direction,
A double-acting side shift cylinder 12 operated by hydraulic pressure is provided. Also, the lift bracket 6
Is equipped with an electromagnetic control valve 32,
Hoses 29a and 29b are connected to the control valve 32. The control valve 32 is configured to operate by applying an applied voltage of a predetermined value or more to a solenoid that drives the spool, and the valve opening degree is variable by the operation of the spool according to the applied voltage.

As shown in FIGS. 1 and 3, between the control valve 32 and the tilt cylinder 11, a hose 33a for supplying hydraulic oil to the bottom side of the tilt cylinder 11 and a head side of the tilt cylinder 11 are provided. A hose 33b for supplying hydraulic oil is provided,
When the hydraulic oil is supplied to the bottom side of the tilt cylinder 11, the hydraulic oil on the head side is collected by the control valve 32 via the hose 33b, and when the hydraulic oil is supplied to the head side of the tilt cylinder 11. The hydraulic oil on the bottom side is collected by the control valve 32 via the hose 33a.

The side shift cylinder 1 is provided between the control valve 32 and the side shift cylinder 12.
Hose 34a for supplying hydraulic oil to the bottom side of No. 2
And a hose 34b for supplying hydraulic oil to the head side of the side shift cylinder 12, and when the hydraulic oil is supplied to the bottom side of the side shift cylinder 12, the hydraulic oil on the head side is The side shift cylinder 12
When the hydraulic oil is supplied to the head side, the hydraulic oil on the bottom side is collected by the control valve 32 via the hose 34a.

When hydraulic oil is supplied from the control valve 32 to the bottom side of the tilt cylinder 11,
When the tilt cylinder 11 is extended and the tip of the fork 7 is tilted so as to be directed upward, a so-called tilt-up operation is performed, and when hydraulic oil is supplied from the control valve 32 to the head side of the tilt cylinder 11, the tilt cylinder 11 is moved. 11 is shortened and fork 7
A so-called tilt-down operation is performed in which the tip of the is tilted downward.

When hydraulic oil is supplied from the control valve 32 to the bottom side of the side shift cylinder 12, the side shift cylinder 12 is extended and the fork 7 is slid to the right, so-called right shift operation. When hydraulic oil is supplied from the control valve 32 to the head side of the side shift cylinder 12, the side shift cylinder 12 is shortened and the fork 7 is slid to the left, which is a so-called left shift operation.

Further, as shown in FIG. 3, the hydraulic device 13
An electromagnetic shutoff valve 35 is provided in the middle of a pipe connecting the control valve 31 and the control valve 31, and the shutoff valve 35 is configured to operate by applying a predetermined applied voltage to a solenoid that drives a spool. ing. Then, when the shut-off valve 35 is operated, the pipe from the hydraulic device 13 to the control valve 31 is opened, and the flow of the hydraulic oil is cut off. Further, the pipes connecting the hydraulic device 13 and the control valve 32, that is, the hoses 29 a and 29 b are connected between the hydraulic device 13 and the shutoff valve 35.

By the way, of the operation levers 22, a tilt lever 22a for performing a tilt-up / tilt-down operation of the fork 7 is provided with a potentiometer 36a for detecting a lever operation amount, and the fork 7 shifts right / left. A potentiometer 36b for detecting the lever operation amount is attached to the side shift lever 22b for performing the left shift operation. Further, among the operation levers 22, the lift lever 22c for operating the expansion and contraction of the lift cylinder 7 and the reach lever 22d for operating the expansion and contraction of the reach cylinder 9 output an ON signal when the lever operation is performed. The micro switches 37c and 37d are attached so as to do so.

Then, the control device 28 controls the lever operation amounts detected by the potentiometers 36a and 36b,
Based on the ON signals output from the micro switches 37c and 37d, the motor 18 forming the hydraulic device 13,
Control valve 32 and shutoff valve 3
5 is controlled.

As shown in FIG. 4, potentiometers 36a and 36b and microswitches 37c and 37d are connected to the input side of the control device 28, and the lever operation amounts are input from the potentiometers 36a and 36b, respectively. Lift lever 22 from switches 37c and 37d
An ON signal is input when c or the reach lever 22d is operated. The motor 18, the control valve 32, and the shutoff valve 35 are provided on the output side of the control device 28.
Are connected and are controlled as detailed below.

When the operator operates the tilt lever 22a or the side shift lever 22b and the lever operation amount is input to the control device 28, the control device 28 operates the motor 18 at a predetermined rotation speed and performs other operations. It is determined whether the lever 22 is operated. The rotation speed of the motor 18 here is set in advance so that the pump 17 can generate the hydraulic pressure required to operate each cylinder.

Now, the lift lever 22c and the reach lever 22d are not operated, and the micro switch 37
If no ON signal is input from c and 37d, the control device 28 applies an applied voltage to the shutoff valve 35 to operate it, and shuts off the flow of hydraulic oil to the control valve 31. Further, the control valve 32 is supplied with an applied voltage that is set in advance according to the lever operation amount to operate the control valve 32, thereby supplying hydraulic oil to the tilt cylinder 11 or the side shift cylinder 12. The voltage applied to the control valve 32 here is the control valve 3
Since it corresponds to the opening degree of 2, the control valve 32 is opened and closed at the opening degree according to the lever operation amount.
Therefore, the operator can operate the lever at a desired cylinder operating speed by adjusting the amount of hydraulic oil supplied to the tilt cylinder 11 and the side shift cylinder 12 by operating the lever.

Further, in this way, the control valve 31
When it is not necessary to supply the hydraulic oil to the control valve 32, the shutoff valve 35 is operated to smoothly supply the hydraulic oil from the hydraulic device 13 to the control valve 32.

On the other hand, the lift lever 22c or the reach lever 22d is operated, and the micro switch 37
If the ON signal is input from c and 37d, the control device 28 does not operate the shutoff valve 35, and controls the control valve 32 according to the lever operation amount detected by the potentiometers 36a and 36b similar to the above. Take control. Further, if the ON signals are input from the microswitches 37c and 37d during the operation of the shutoff valve 35, the control device 28 eliminates the voltage applied to the shutoff valve 35 and causes the hydraulic device 13 to control the control valve 3.
Allow hydraulic oil to flow to 1.

When it is necessary to supply hydraulic oil to the control valve 31 as described above, the shutoff valve 35 is not operated or deactivated so that the supply of hydraulic oil from the hydraulic device 13 to the control valve 31 is hindered. The hydraulic oil can be supplied from the hydraulic device 13 to the control valve 32 without coming.

As described above, according to the present embodiment, only two hoses 29a and 29b can be hung on the pulley 30 suspended on the mast 5, and a large number of hoses as in the conventional art can be used. Can be prevented from being blocked. Further, in the conventional high-lift type mast, all the hoses connected to the cylinders arranged on the lift brackets had to be lengthened, but according to the present embodiment, only the hoses 29a and 29b are lengthened. Therefore, it is possible to reduce the piping loss due to the hose and to suppress the cost increase related to the hose. Further, the cylinder for causing the fork 7 included in the lift bracket 6 to perform a predetermined operation, that is, the tilt cylinder 11 and the side shift cylinder 12, has a controller 28 if the operator operates the tilt lever 22a or the side shift lever 22b. Since it is controlled and operated by, the operability is not impaired due to the change of the piping structure.

Although it is not always necessary to provide the shutoff valve 35 in carrying out the present invention,
It is preferable to provide it. Further, in the above embodiment, the case where the cylinders included in the lift bracket 6 are the tilt cylinder 11 and the side shift cylinder 12 has been described, but the present invention is not limited to this, and the lift bracket 6 is mounted. The same effect can be obtained even with an attachment device cylinder that drives an attachment device that is used in association with the fork 7, and in particular, the greater the number of cylinders, the greater the effect.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

[0042]

According to the invention described in claim 1, regardless of the number of hydraulic cylinders provided in the lift bracket,
Since only two hoses can be hooked on the pulley, it is possible to prevent the front view from being obstructed by a large number of hoses as in the conventional case.

According to the second aspect of the invention, the hydraulic circuit is opened when it is not necessary to supply hydraulic oil to another hydraulic cylinder while the operating lever is being operated. The hydraulic oil can be supplied only to the hydraulic cylinder provided on the lift bracket.

According to the third aspect of the present invention, it is possible to supply and recover the working oil to the tilt cylinder provided on the lift bracket and the side shift cylinder or the cylinder for the attachment device without any trouble.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a mast according to an embodiment of the present invention, a part of which is shown in an exploded view.

FIG. 2 is a front view showing a lift bracket according to an embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 4 is a block diagram showing a control system according to an embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional forklift.

FIG. 6 is a perspective view showing a main part of a mast of a conventional forklift truck, in which a part thereof is disassembled and shown.

[Explanation of symbols]

1 Reach type forklift 2 Body frame (vehicle body) 5 masts 6 Lift bracket 7 forks 8 lift cylinders 9 Reach cylinder 11 Tilt cylinder 12 Side shift cylinder 13 Hydraulic system 22 Operation lever 28 Control device 29a, 29b hose 30 pulley 32 control valve 33a, 33b hose 34a, 34b hose 35 shut-off valve

Claims (3)

[Claims] 1. A lift bracket that can be moved up and down along a mast mounted in front of a vehicle body, and the lift bracket includes a pair of left and right forks and a plurality of hydraulic cylinders that hydraulically drive the forks. Along with
In a forklift including a hydraulic source for supplying hydraulic oil to the vehicle body in the vehicle body, the flow of the operating oil from the hydraulic source to the hydraulic cylinder is controlled according to the operation of an operating lever provided on the vehicle body. An electromagnetic control valve is disposed on the lift bracket, and a hose for supplying and collecting hydraulic oil between the hydraulic pressure source and the electromagnetic control valve is suspended on the mast and is rotatable. While hanging on the pulley,
A forklift that is connected to the hydraulic power source and the electromagnetic control valve, respectively. 2. A forklift having a hydraulic circuit for supplying hydraulic oil from the hydraulic source to another hydraulic cylinder different from the hydraulic cylinder, the electromagnetic circuit capable of opening the hydraulic circuit in response to an operation of the operation lever. The forklift according to claim 1, further comprising a shutoff valve. 3. The hydraulic cylinder is provided in a tilt cylinder for tilting the fork in the vertical direction, a side shift cylinder for sliding the fork in the horizontal direction, or the lift bracket, and is used in association with the fork. An attachment device cylinder for driving the attachment device, and the forklift according to claim 1 or 2.