JPS5937254B2 - Elevation control device for loading platform in cargo handling vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lift control device for a loading platform in a cargo handling vehicle, mainly a tailgate lifter.

A cargo receiving platform that also serves as a tailgate is raised and lowered via a parallel link mechanism to the rear of the vehicle frame carrying a cargo box while maintaining a substantially horizontal state, and cargo on the ground is loaded onto the cargo box, or the cargo on the cargo box is A cargo handling vehicle called a so-called tailgate lifter, which unloads cargo onto the ground, can freely adjust the lifting speed of the cargo platform depending on the size of the cargo load. It is desirable to be able to slowly and efficiently load and unload cargo by bringing the receiving platform into contact with the cargo box without causing any impact.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lift control device for a cargo platform in a cargo handling vehicle, which has a simple structure and is capable of achieving the above object.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
Figure 1 shows the rear part of the tailgate lifter.
A cargo box 3 is mounted on the vehicle frame 1 via a support 2.

At the rear of the vehicle frame 1, a cargo receiving platform 5, which also serves as a tailgate for the cargo box 3, is supported substantially horizontally via a conventionally known parallel link mechanism 4.

A single-acting lift cylinder 6 supported by the vehicle frame 1 is connected to the parallel link mechanism 4, and the cargo receiving platform 5 can be moved up and down via the parallel link mechanism 4 by the expansion and contraction of the lift cylinder 6. can.

The lift cylinder 6 is supplied with hydraulic oil generated from a power unit (PU) supported by the vehicle frame 1.

Incidentally, since the parallel link mechanism 4 has a conventionally known structure, a detailed explanation of its structure will be omitted.

FIG. 2 shows a hydraulic circuit diagram of the power unit PU for operating the lift cylinder 6.

In this hydraulic circuit diagram, batch IJ B and electric motor M
are connected via a power supply circuit 7, and an open/close switch S that can be opened and closed arbitrarily is connected to this limit circuit 7 via a relay R. When the open/close switch S is closed, the relay R is turned on. When excited, the power supply circuit 7 is closed and the electric motor M is driven.

A hydraulic pump P is connected to the electric motor M, and a hydraulic oil passage 8 connected to a discharge port of the hydraulic pump P communicates with a high pressure chamber a of the lift cylinder 6. A reflux oil passage 9 communicating with the reservoir T is connected.

In the middle of the return oil path 9, there is a manual switching valve (■) that can be switched at will.When this switching valve (V) is switched downward as shown in FIG. When the flow of the return oil passage 9 from the hydraulic oil passage 8 to the oil sump T is blocked and the switching valve ■ is switched upward, the flow rate of the return oil flowing from the hydraulic oil passage 8 to the oil sump T is reduced by the variable throttle 11. can be variably adjusted.

In FIG. 2, 12 is a check valve installed in the middle of the hydraulic oil passage 8, and 13 is a relief valve installed in the middle of the oil passage that communicates the hydraulic oil passage 8 with the oil sump T. .

As shown in FIG. 3, the operation lever 14 of the switching valve V protrudes outside through the casing 16 of the power unit (PU), and the opening/closing switch S is located near the grip 15 of the operation lever 14. It is provided.

Therefore, the operator can grip the grip portion 15 and open/close the on-off switch S at the same time as switching the five-way switching valve (2).

Next, to explain the operation of the present invention, in order to raise the cargo receiving platform 5, the operator must press the grip part 1 of the operating lever 14.
If the on-off switch S provided near the hydraulic pump P is closed to drive the electric motor M, and at the same time the switching valve ■ is switched to the lower side by operating the operating lever 14, the pressure oil from the hydraulic pump P passes through the hydraulic oil path. The high pressure chamber a of the lift cylinder 6
The cargo receiving platform 5 can be raised by extending the lift cylinder.

In addition, when the switching valve ■ is switched upward using the operating lever 14, a part of the pressure oil in the hydraulic oil passage 8 can be returned to the oil sump T through the variable throttle 11, and the loading platform 5 can be moved at low speed. The loading platform 5 can be raised slowly, and the speed of the loading platform 5 can be adjusted by controlling the variable throttle 1 by operating the operating lever 14.
It can be adjusted by adjusting the degree of aperture.

Therefore, depending on the weight of the cargo on the loading platform 5, etc.
The rising speed of the loading platform 5 can be adjusted appropriately.
At the end of the rise, the lifting speed of the cargo receiving platform 5 is made particularly slow so that the receiving platform 5 can be brought into contact with the rear part of the cargo box 3.

When lowering the cargo platform 5, l means that when the opening/closing switch S is opened, the oil in the high pressure chamber of the lift cylinder 6 will be transferred to the cargo platform 5 and the parallel link mechanism 4. The oil is returned to the oil sump T through the variable throttle 11 due to its own weight, so that the loading platform 5 can be lowered slowly and the lowering speed can be freely adjusted.

As described above, according to the present invention, the cargo box 3 mounted on the vehicle frame 1, the cargo receiving platform 5 connected to the rear of the vehicle frame 1 via the parallel link mechanism 4, and the A cargo handling vehicle having at least a lift cylinder 6 which is connected to each other and which can raise and lower the loading platform 5 via the parallel link mechanism 4, and a power unit (PU) that supplies hydraulic oil to the lift cylinder 6.
The PU is connected to an electric motor M connected to a power supply circuit 7 equipped with an open/close switch S that can be opened and closed as desired, and is connected to the electric motor M, and applies pressure to the lift cylinder 6 via a hydraulic oil path 8. A hydraulic pump P capable of supplying oil is interposed in the middle of a return oil passage 9 that communicates the middle of the hydraulic oil passage 8 with the oil sump T, and the return oil passage 9 is interrupted or conducted so that the flow rate can be adjusted. The flow rate of the hydraulic oil returned from the hydraulic oil passage 8 to the oil sump T via the return oil passage 9 is controlled by the open/close state of the open/close switch S. Regardless of the switching operation lever 1
It can be adjusted arbitrarily with only the switching operation in step 5.
Therefore, in particular, when the on-off switch S is in the closed state □, the amount of oil supplied to the lift cylinder 6 and therefore the rising speed of the loading platform 5 can be adjusted arbitrarily. According to the amount of oil discharged from the cargo receiving platform 5, the descending speed of the cargo receiving platform 5 can be adjusted to increase or decrease as desired. In addition, the rising speed (or descending speed) of the loading platform 5 is controlled slowly, particularly at the end of its ascent (or end of its descent), to reduce the impact upon contact with the rear end of the cargo box (or the ground). This makes it possible to load and unload cargo quietly and accurately.

Furthermore, the single common switching operation lever 15 is used not only as a lever for adjusting the descending speed of the loading platform 5 but also as an adjusting lever for the ascending speed, so that the structure is simple and can contribute to cost reduction.

In addition, since the on-off switch S is provided on the switching operation lever 14 of the switching valve (1), it is possible to easily perform two operations: switching the switching valve V and opening/closing the on-off switch S at the same time. The loading platform 5 can be raised and lowered quickly, improving work efficiency.

[Brief explanation of drawings]

FIG. 1 is a rear perspective view of a tailgate t-IJ softer equipped with the device of the present invention, FIG. 2 is a hydraulic circuit diagram of a power unit and a lift cylinder, and FIG. 3 is a perspective view of the power unit. 1...-Car frame, 3...Cargo box, 4...
・・Parallel link mechanism, 5... Loading platform, 6...
...Lift cylinder, 7...Power circuit, 8.
...Hydraulic oil path, 9...Return oil path, PU.
...Power unit, M...Electric motor, T...Oil sump, S...Open/close switch,
P...Hydraulic pump.

Claims (1)

[Claims] 1 A loading box 3 mounted on a vehicle frame 1, a loading platform 5 connected to the rear of the vehicle frame 1 via a parallel link mechanism 4, and a loading platform 5 connected to the parallel link mechanism 4, which is connected to the parallel link mechanism 4.
A cargo handling vehicle having at least a lift cylinder 6 capable of raising and lowering the loading platform 5 via a lift cylinder 6 and a power unit PU supplying hydraulic oil to the lift cylinder 6,
The power unit PU includes an electric motor M connected to a power supply circuit 7 equipped with an open/close switch S that can be opened and closed as desired, and a lift cylinder 6 connected to the electric motor M via a hydraulic oil path 8. A hydraulic pump P capable of supplying pressure oil to the hydraulic oil passage 8 is interposed in the middle of the return oil passage 9 that communicates the middle of the hydraulic oil passage 8 with the oil sump T, and the return oil passage 9 can be blocked or the flow rate can be adjusted. A control device for lifting and lowering a cargo receiving platform in a cargo handling vehicle, comprising a switching valve (1) which can be switched arbitrarily to conduct the switching valve (2), and the opening/closing switch S is provided on the switching lever 14 of the switching valve (2).