JPS6126320Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mast device for a cargo handling vehicle such as a forklift, and more particularly to a hydraulic circuit for a so-called full free view mast device.

A full-free mast is used, for example, in shipboard work where the height is restricted, and has a structure in which the movable mast does not rise while the fork rises to the mast height.

The conventional full-free mast device 100 has a structure as shown in FIGS. 3 and 4, and includes a main lift cylinder 103 for driving the movable mast 102 up and down with respect to the fixed mast 101, and a main lift cylinder 103 for moving the movable mast 102 up and down with respect to the fixed mast 101. The lift cylinder 106 is provided with a full-free lift cylinder 106 for vertically moving an elevating body 104 and a fork 105 suspended thereon, and these are arranged in the center of the left and right mast frame members, one in front and one in the rear.

A chain sheave 107 is attached to the head of the piston rod of the full-free lift cylinder 106, and a lift chain 108 is wrapped around the chain sheave 107.
It is made to rise at twice the speed of expansion and contraction. For this reason, the lift cylinder 106 suddenly
The length is approximately half that of the main lift cylinder 103.

As shown in FIG. 5, the hydraulic circuit is connected to an oil pipe 110 for supplying pressure oil to the lower chamber 109 of the main lift cylinder 103, and passes through the piston rod 111 and piston 112 of the lift cylinder 103. The outlet of the first oil passage 113 and the lower chamber 114 of the full-free lift cylinder 106
and is connected by an oil pipe 115.

Both the lift cylinders 103 and 106 are single-acting hydraulic cylinders, but each of the upper chambers 116 and
117 is provided with return oil pipes 118 and 119.

These oil pipes 118, 119 are connected to each cylinder 1.
03, 106, the oil leaked into the upper chambers 116, 117 through the seals of the pistons 112, 121 is returned to the tank T. 11
It functions to prevent damage to the 2,121 seals.

In the past, the upper chambers 116 and 117 were simply opened to the atmosphere by opening them, so foreign matter could be sucked into the upper chambers along with the atmosphere and deteriorate the seal of the piston. The inside of the upper chamber and the piston rod were susceptible to rust.

For this reason, the return oil pipe 118, 1
19, but conventionally, as shown in FIG. 5, another second oil passage 122 is bored in the piston rod 111 of the main lift cylinder 103, and one end of this is opened to the upper chamber 116. I have to.

In the figure, 123 is a flow control valve, 124 is a switching valve, P is a hydraulic pump, and T is a tank.

With this configuration, the oil pipes 118 and 119 can be so-called fixed pipes, and there is no need to use a high-pressure hose and a winder, making piping convenient.

However, there are two oil passages 113 and 122 in the piston rod 111 of the main lift cylinder 103.
Drilling is extremely difficult because these oil pipes are not concentric with the piston rod and must be formed into a relatively long and thin piston rod.

Further, the conventional full free mast device 100 has the following features:
As shown in FIG. 3, the main lift cylinder 103
The full-free lift cylinder 106 is placed in the center of the left and right mast frame members, and the presence of the main lift cylinder 103, which is approximately the same height as the mast, significantly obstructs the forward view.

Therefore, this improvement was called for.

This invention was devised to solve the problems mentioned above, and its main purpose is to
To provide a hydraulic circuit for a full-free view mast device which has two main lift cylinders and is of a so-called view mast type in which these cylinders are arranged at the rear of left and right mast frame members, etc., and the forward field of view is significantly improved.

Another purpose of this invention is to take advantage of the fact that there are two main lift cylinders to form a return oil passage in the piston rod of one of the main lift cylinders, thereby making the piping easier and the work easier. To provide a complete hydraulic circuit for free-view mast equipment.

Hereinafter, the details will be explained based on FIG. 1 and FIG. 2 showing one embodiment of the present invention.

The present invention is applied to a full free view mast device 1 as shown in FIG.

The device 1 includes a fixed mast 2, a movable mast 3 that can be raised and lowered with respect to the fixed mast, an elevating body 4 that moves up and down along the movable mast 3, and left and right forks 5 suspended from the elevating body 4. , left and right main lift cylinders 6 and 7 for driving the moving mast 3 up and down.
A full-free lift cylinder 9 is fixed to the moving mast 3 and has a chain sheave 8 on its piston rod head, and a full-free lift cylinder 9 has one end fixed to the moving mast 3 and the other end to the elevating body 4 and connected to the chain sheave 8. The main part thereof is composed of a lift chain 10 that is stretched over the lift chain 10.

The main lift cylinders 6 and 7 are arranged behind the left and right mast frame members and fixed to the fixed mast 2, and the tips of their piston rods are fixed to the movable mast 3, respectively.

Since the full-free lift cylinder 9 employs a chain mechanism, it may be approximately half the height of the moving mast 3.

In such a full free view mast device 1, since the main lift cylinders 6 and 7 are arranged at the rear of the mast frame material, the central portion of the mast device is open and the forward field of vision is extremely good. Although there is a full-free lift cylinder 9 in the center, its height is approximately half that of the movable mast 3, so it has no effect at all during normal fork work or traveling.

The present invention is applied to such a mast device 1, and utilizes one of the two main lift cylinders 6 and 7 to form a return oil passage in the piston rod to create a full-free lift cylinder 9.
The feature lies in the fact that the return oil pipe is connected.

FIG. 2 shows the hydraulic circuit.

The left and right main lift cylinders 6, 7 and the full-free lift cylinder 9 are both single-acting hydraulic cylinders, but have the same form as a double-acting type.
5, 16, piston rods 17, 18, 19, upper chambers 20, 21, 22 and lower chambers 23, 24, 2.
5 are formed respectively.

Therefore, tank T, hydraulic pump P, switching valve 26,
Oil pipe 28 passing through flow control valve 27
are branched and connected to the lower chambers 23, 24 of the main lift cylinders 6, 7.

In the present invention, an oil passage 29 for supplying pressure oil is bored in the piston 14 and piston rod 17 of the left main lift cylinder 6, and the inlet 3
0 is open to the lower chamber 23, and the outlet 31 is open to the head of the piston rod 17.

The outlet 31 of the oil passage 29 and the lower chamber 25 of the full-free lift cylinder 9 are connected by an oil pipe 32.

The right main lift cylinder 7 has an oil passage 33 formed in its piston rod 18, and an inlet 3 thereof.
4 is provided at the head of the piston rod 18, and an outlet 35 opens near the piston 15 and is constantly connected to the upper chamber 21.

Therefore, the upper chamber 2 of the lift cylinder 9 for full free
2 and the inlet 34 of the oil passage 33 are connected by an oil pipe 36. Further, oil pipes 37 and 38 are connected to the upper chambers 20 and 21 of the left and right main lift cylinders 6 and 7, leading to the tank T. Each of the upper chambers 20, 21, 2
2. Oil pipes 36, 37, 38 and oil passage 33 should be filled with oil.

The pressure receiving area of the piston 16 of the full-free lift cylinder 9 is the same as that of the main lift cylinders 6 and 7.
The pressure receiving area of the pistons 14 and 15 is larger than that of the pistons 14 and 15, and when pressure oil is supplied, first the two piston rods 19 of the full-free lift cylinder 9 extend,
The piston rods 17, 18 of the main lift cylinders 6, 7 are made to extend at the point where they are fully extended.

When the full-free lift cylinder 9 and the main lift cylinders 6 and 7 are extended, each upper chamber 2
The oil in tanks 0, 21, and 22 is returned to tank T.
Conversely, if each cylinder 9, 6, 7 is shortened, the tank T
The upper chamber 20, 21, 22, oil pipes 36, 37, 38, and oil passage 33 are always filled with oil.

Therefore, the interior of the upper chambers 20, 21, 22 will not rust, and foreign matter will not flow in with the outside air and damage the seals.

As mentioned above, according to the present invention, the main lift cylinder is made into a view mast type in which there are two and these are placed at the rear of the left and right mast frame members, so it is completely free between the left and right mast frame members. Even if a lift cylinder is present, its height is low, so forward visibility is significantly improved, and work efficiency is improved.

In particular, taking advantage of the fact that there are two main lift cylinders, a return oil passage is formed in the piston rod of one of the main lift cylinders, and this oil passage is connected to the upper chamber of the full-free lift cylinder with a fixed oil pipe. This greatly simplifies the work and piping.

Since one oil passage can be concentrically bored in each of the piston rods of both main lift cylinders,
This provides various effects such as ease of machining and the ability to make piston rods without affecting their strength.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view showing the outline of the full free view mast device according to the present invention, FIG. 2 is a schematic hydraulic circuit diagram showing the hydraulic circuit of the present invention, and FIG.
FIG. 4 is a schematic plan view showing the outline of a conventional full-free mast device, FIG. 4 is a schematic side view showing the same outline, and FIG. 5 is a schematic hydraulic circuit diagram showing the hydraulic circuit of the same device. 1...Full free view mast device, 2...Fixed mast, 3...Moving mast, 4...Elevating body, 5
...Fork, 6,7...Main lift cylinder, 9...Full free lift cylinder, 14...
... Piston, 17, 18 ... Piston rod, 2
0-22...Upper chamber, 23-25...Lower chamber, 28...
...Oil pipe, 29...Oil passage, 30...Inlet, 31...
Outlet, 32... Oil pipe, 33... Oil path, 34... Inlet, 35... Outlet, 36-38... Oil pipe.

Claims (1)

[Scope of utility model registration request] left and right main lift cylinders 6 and 7 for driving the movable mast 3 up and down relative to the fixed mast 2;
It is equipped with a full-free lift cylinder 9 for vertically driving an elevating body 4 and a fork 5 suspended thereon with respect to the movable mast 3, and the main lift cylinders 6 and 7 are arranged near the left and right mast frame members. At the same time, the full-free lift cylinder 9 is half the height of the movable mast 3 and is installed approximately in the center of the left and right mast frame members. The piston 14 has a lower chamber 2 of this
The piston rod 18 of the other main lift cylinder 7 is provided with an inlet 34 and an inlet 34 that opens into the head of the piston rod 17. An oil passage 33 with an outlet 35 reaching the upper chamber 21 is bored, and each of the lower chambers 23 and 24 of the left and right main lift cylinders 6 and 7 is connected to a hydraulic pump P.
An oil pipe 28 connects the outlet 32 of the oil passage 29 of one main lift cylinder 6 and the lower chamber 25 of the full-free lift cylinder 9, and an oil pipe 32 connects the upper chamber 22 of the full-free lift cylinder 9 to the other main lift. The inlet 34 of the oil passage 33 of the cylinder 7 is the oil pipe 36
The upper chamber 20 of both main lift cylinders 6, 7,
21 and the tank T are connected to each other by oil pipes 37 and 38, respectively.A hydraulic circuit of a full free view mast device.