JPH0660703B2 - Control device for raising / lowering the load box of the dump car - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a load box lifting / lowering control device for a dump truck that controls rising, stopping, and lowering of a load box.

(B) Conventional Technology In general, a dump manufacturer mounts a packing box on a dumping chassis provided by a chassis manufacturer and attaches a hydraulic cylinder for raising and lowering the packing box and a switching valve for controlling expansion and contraction of the hydraulic cylinder to a dump truck. Has been completed.

By the way, a dump operation lever is generally attached to the dump chassis on the chassis maker side, and this dump operation lever is also attached at the front position and the rear position by the chassis maker. In some cases, the packing box is raised, and the switching direction is reversed. In this case, when the dump operation lever and the switching valve are connected by a transmission member, a bell crank is inserted in the middle of either one. If the operator carelessly touches the bell crank when the luggage box is raised to perform maintenance and inspection of hydraulic equipment on the chassis frame, the switching valve switches to the down position and the luggage box suddenly descends. Will cause personal injury.

In order to solve this problem, in Japanese Patent Laid-Open No. 59-84635, when the switching position of the dump lever is reversed, the spool valve is mounted in the opposite direction so that the dump member can be dumped with a transmission member without a bell crank. The above-mentioned problem is solved by connecting the operation lever and the switching valve.

(C) Problems to be Solved by the Invention However, depending on the dumping chassis, if the spool valve is installed in the rearward and rearward direction, there is a chassis frame, fuel tank, etc. in the rearward direction, and a transmission member that attaches space is attached. There was a problem of not being.

(D) Means for Solving the Problems The present invention has been made to solve the above problems.
In the hydraulic circuit that connects the hydraulic pump and oil tank to the hydraulic cylinder, the sliding position of the spool valve that is inserted into the valve body causes the hydraulic pump to supply the pressure oil from the hydraulic pump to the hydraulic cylinder and the hydraulic position. In the control device for lifting and lowering the load box of the dump truck, which comprises a switching valve for controlling switching between a discharge position for discharging the hydraulic oil in the cylinder to an oil tank and a neutral position for short-circuiting the hydraulic pump and the oil tank, the valve body Is provided with a first valve chamber in the center, a second valve chamber and a third valve chamber in front and rear thereof, and a fourth valve chamber and a fifth valve chamber outside the second valve chamber and the third valve chamber, respectively. The first valve chamber is provided with a first port communicating with the hydraulic pump and a second port communicating with the hydraulic cylinder, and the second valve chamber and the third valve chamber are provided with a third port communicating with the hydraulic cylinder. With a fourth port, In addition, the fourth valve chamber and the fifth valve chamber are provided with a fifth port and a sixth port communicating with an oil tank, and a hydraulic pressure is provided in the middle of the first oil passage connecting the second port and the hydraulic cylinder. A check valve for preventing hydraulic fluid from the cylinder from flowing out to the second port is provided, and a spool valve that communicates the first valve chamber, the third valve chamber, and the fifth valve chamber at the neutral position is provided. When selected, a shielding member is provided in the middle of the third oil passage that connects the fourth port of the third valve chamber and the hydraulic cylinder, and the first valve chamber, the second valve chamber, and the fourth valve chamber are separated from each other. When the spool valve communicating is selected, the third valve in the second valve chamber
It is characterized in that a shielding member is interposed in the middle of the second oil passage that connects the port and the hydraulic cylinder.

(E) Action In the mounting state in which the front position of the dump operation lever attached to the dump chassis is to raise the load box and the rear position is to lower the load box, as shown in FIG. A shielding member is provided in the third oil passage, and the spool valve shown in the figure is used.

Then, at the neutral position of the dump operation lever, the hydraulic oil is circulated from the hydraulic pump to the oil tank, and at the front position of the dump operation lever, the hydraulic oil of the hydraulic pump flows into the hydraulic cylinder, and the hydraulic cylinder is extended to extend the load box. And then
At the rear position of the operation lever for dumping, the hydraulic oil of the hydraulic cylinder is discharged to the oil tank, the hydraulic cylinder shrinks, and the cargo box descends.

Next, in a mounting state in which the rear position of the dump operation lever attached to the dump chassis is raised and the front position is lowered, as shown in FIG. 3, a shielding member is provided in the second oil passage. Use the spool valve shown in the figure. Then, at the neutral position of the dump operation lever, the hydraulic oil from the hydraulic pump is circulated to the oil tank, and at the rear position of the dump operation lever, the hydraulic oil of the hydraulic pump flows into the hydraulic cylinder to extend the hydraulic cylinder. The luggage box is raised, and at the position in front of the dump operation lever, the hydraulic oil of the hydraulic cylinder is discharged to the oil tank, the hydraulic cylinder contracts, and the luggage box descends.

(F) Example Hereinafter, an example of the present invention will be described with reference to the drawings.
The switching valve (1) of the present invention is a hydraulic pump (P) and an oil tank.
(T) and the hydraulic cylinder (C) for raising and lowering the cargo box, which is interposed in the hydraulic circuit, and includes a switching valve (1) and a hydraulic pump (P).
And a spool valve (4) that is slidably inserted into a valve body (2) common to the valve body and a guide hole (3) formed in the valve body (2) in the longitudinal direction.
It is mainly composed of and.

The guide hole (3) has a first valve chamber (5) substantially in the center thereof, a second valve chamber (6) and a third valve chamber (7) before and after the first valve chamber, and a second valve chamber.
A fourth valve chamber (8) and a fifth valve chamber (9) are provided outside the (6) and the third valve chamber (7), respectively.

The first valve chamber (5) and the second valve chamber (6) are in communication with each other.
The second valve hole (11), in which the valve hole (10) communicates with each other between the first valve chamber (5) and the third valve chamber (7), includes the second valve chamber (6) and the fourth valve chamber. A third valve hole (12) communicating with each other is provided between (8), and a fourth valve hole (13) communicating with each other is further provided between the third valve chamber (7) and the fifth valve chamber (9). Each of the valve holes (10) (11) (12) (13) is a spool valve.
It is formed with the same diameter as (4).

A hydraulic pump (P) is provided on one side of the first valve chamber (5) through an oil passage.
The first port (14) for communicating with
A second port (16) is provided to communicate with the hydraulic cylinder (C) via the oil passage (15). On the other side of the second valve chamber (6) and the third valve chamber (7), a third port communicating with the hydraulic cylinder (C) via the second flow passage (17) and the third flow passage (18) (19) and 4th
Each port (20) is drilled.

A fifth port (21) and a sixth port (22), which communicate with an oil tank (T) through an oil passage, are formed at one side of the fourth valve chamber (8) and the fifth valve chamber (9), respectively. It is set up. The spool valve
(4) is the first large diameter portion (4a) and the second large diameter portion at the front and rear portions
(4b) are respectively formed, these are slidably fitted in the guide holes (3), and the hydraulic oil from the hydraulic pump (P) is returned to the oil tank (T) as shown in FIG. The first large diameter portion (4a) is fitted in the first valve hole (10) and the third valve hole (12) at the neutral position in the middle of the dump operation lever 26 for stopping the hydraulic pump (P). At the raising position of the forward switching, in which the hydraulic oil of the above flows into the hydraulic cylinder (C) and the load box is raised, the first large diameter portion (4a) has the first valve hole (10) and the second valve hole (11). And the third valve hole
When fitted to (12), the first large diameter part (4a) moves to the third position at the lower position of the backward switching, which lowers the load box for discharging the hydraulic oil from the hydraulic pump (P) to the oil tank (T). Fit in the valve hole (12).

Further, as shown in FIG. 3, the second large diameter portion (4b) is fitted into the second valve hole (11) and the fourth valve hole (13) in the neutral position, and the second large diameter portion (4b) is in the raised position. ) Is fitted in the first valve hole (10), the second valve hole (11) and the fourth valve hole (13), and the second large diameter portion (4b) is in the fourth valve hole (13) in the lowered position. Mating. Reference numeral (23) is a shielding member interposed in the middle of the second oil passage (17) or the third oil passage (18).

(24) is a check valve provided in the middle of the first oil passage (15) connecting the second port (16) and the hydraulic cylinder (C).
Prevent hydraulic fluid from (C) from flowing out to the second port (16).

(25) is a coupling portion provided at the front end of the spool valve (4), and this coupling portion (25) and a dump operation lever (2
6) are connected by a transmission member (27) such as a pushle wire.

The present invention is configured as described above, and when the dump operation lever (26) attached to the dump chassis is in the attached state in which the forward switch is in the up position and the rear switch is in the down position, As shown in FIG. 1, the third member (1
Shut off 8) and use the spool valve (4) shown.

Then, when the dump operation lever (26) is operated to the neutral position, the hydraulic oil from the hydraulic pump (P) receives the first port (14), the first valve chamber (5), the third valve chamber (7), the fifth valve chamber (7), and the fifth valve chamber (7). Valve chamber (9), 6th port (2
It will flow back through 2) to the oil tank (T) and the cargo box will stop.

Next, when the dump operation lever (26) is operated to the forward raised position, both the first valve hole (10) and the second valve hole (11) are spool valve.
Since it is shut off by (4), the hydraulic oil of the hydraulic pump (P) passes through the first port (14), the first valve chamber (5), the second port (16) and the first oil passage (15). The check valve (24) is opened to flow into the hydraulic cylinder (C), and the hydraulic cylinder (C) is extended to raise the load box.

When the dump operation lever (26) is operated to the rear lower position, the hydraulic oil in the hydraulic cylinder (C) is transferred to the second oil passage (17), the third port (19), the second valve chamber (6), and the second valve chamber (6). 1 valve chamber (5), 3rd valve chamber (7),
Oil tank (T) through the fifth valve chamber (9) and the sixth port (22)
, Which causes the hydraulic cylinder (C) to contract and the cargo box to descend. By the way, in the case where the dump operation lever (26) attached to the dump chassis is attached so that the front position is lowered and the rear position is raised,
As shown in the figure, the second oil passage (17) is shut off by the shielding member (23), and the spool valve (4) shown in the figure is used. When the dump operation lever (26) is operated to the neutral position, the hydraulic oil of the hydraulic pump (P) is supplied to the first port (14), the first valve chamber (5), the second valve chamber (6) and the fourth valve chamber. (8) Circulates to the oil tank (T) through the fifth port (21).

Next, when the dump operation lever (26) is operated to the rearward raised position, the hydraulic oil of the hydraulic pump (P) is transferred to the first port (14), the first
The check valve (24) is opened through the valve chamber (5), the second port (16) and the first oil passage (15) to flow into the hydraulic cylinder (C).

Further, when the dump operation lever (26) is operated to the front lower position, the hydraulic oil of the hydraulic cylinder (C) is supplied to the third oil passage (18), the fourth port (20), the third valve chamber (7), and the third valve chamber (7). 1 valve chamber (5), 2nd valve chamber
(6), through the fourth valve chamber (8) and the fifth port (21) into the oil tank (T).

(G) Effects of the Invention As described above, according to the invention of the present application, the shielding member is attached to one of the pair of the second oil passage and the third oil passage that communicates with the valve chamber from the hydraulic cylinder, and the spool valve that is fitted thereto is used. It is also possible to use it for a dumping chassis mounted so that the operating direction of the dumping operating lever is reversed, and since the transmission member can be installed only in the forward direction, the spool valve can be installed in the reverse direction as in the past. If it is attached to the, the transmission member will not be attached.

[Brief description of drawings]

1 and 3 are sectional views showing a control device of the present invention, and FIG.
The drawing is a cross-sectional view taken along the line AA in FIGS. 1 and 3. (P) is a hydraulic pump, (T) is an oil tank, (C) is a hydraulic cylinder, (1) is a switching valve, (2) is a valve body, (4) is a spool valve,
(5) is the first valve chamber, (6) is the second valve chamber, (7) is the third valve chamber, (8) is the fourth valve chamber, (9) is the fifth valve chamber, and (14) is the fourth valve chamber. 1 port, (15) first oil passage, (16) second port, (17) second oil passage, (18) third oil passage, (19) third port, (20) 4th port, (21)
Is the 5th port, (22) is the 6th port, (23) is the shielding member, (2
4) is a check valve.

Claims (1)

[Claims] 1. A pressure oil from a hydraulic pump is supplied to a hydraulic cylinder by a sliding operation of a spool valve fitted in a valve body in a hydraulic circuit connecting a hydraulic pump and an oil tank to a hydraulic cylinder. Control device for lifting and lowering the load box of the dump truck, which is provided with a switching valve for controlling switching between a supply position, a discharge position for discharging the hydraulic oil in the hydraulic cylinder to an oil tank, and a neutral position for short-circuiting the hydraulic pump and the oil tank. In the valve body, the first valve chamber is provided at the center, the second valve chamber and the third valve chamber are provided at the front and rear thereof, and the fourth valve chamber and the fifth valve chamber are provided outside the second valve chamber and the third valve chamber. Chambers are provided respectively, the first valve chamber is provided with a first port communicating with a hydraulic pump and the second port communicating with a hydraulic cylinder, and the second valve chamber and the third valve chamber are communicated with a hydraulic cylinder. 3rd to do
A first oil for connecting the second port and the hydraulic cylinder, and a fifth port and a sixth port for communicating with an oil tank are provided for the fourth valve chamber and the fifth valve chamber, respectively. A check valve for preventing hydraulic oil from the hydraulic cylinder from flowing out to the second port is provided in the middle of the passage, and in the neutral position, the first valve chamber, the third valve chamber, and the fifth valve chamber are provided.
If you select a spool valve that communicates with the valve chamber,
Select a spool valve in which a shielding member is provided in the middle of a third oil passage that connects the fourth port of the valve chamber and the hydraulic cylinder, and the first valve chamber, the second valve chamber and the fourth valve chamber communicate with each other. When I did
Second for connecting the third port of the second valve chamber and the hydraulic cylinder
A control device for lifting a cargo box of a dump truck, which has a shielding member interposed in the middle of an oil passage.