JPS6238832Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hoist control device for raising and lowering the dump body of a dump truck.

Normally, a dump truck raises the dump body using a medium such as hydraulic pressure, but for this purpose, a hydraulic pump driven by an internal combustion engine mounted for driving, a valve to control this hydraulic pressure source, and a valve to raise and lower the dump body are used. It is equipped with a cylinder for

A hoist lever connected to the valve by a link is provided in the driver's seat so that the driver can operate the valve.

However, in large vehicles, the hydraulic equipment becomes larger and the driver's operating force on the hoist lever increases, so an air source is used to reduce the driver's operating force.

An example of this is shown in FIG.

The hoist valve 1 is a hydraulic valve with four positions: raise R, hold H, lower L, and float F.
These four positions are connected to the first and second cylinders 2 and 2.
3 is used for positioning. These cylinders 2 and 3 are connected to the dump control valve 5 through a cam by operating the dump control lever 4.
It operates by opening and blowing air.

FIG. 1 shows the holding state, in which no air is sent from the dump control air valve 5 and the spool 7 of the hoist valve 1 is automatically set to the holding position by the neutral spring 8.

Now, if dump control lever 4 is raised and operated to R, dump control air valve 5
The air from the air reservoir 9 enters the rod side chamber 2a of the first cylinder 2, and the air from the air reservoir 9 enters the rod side chamber 2a of the first cylinder 2.
is activated, and the spool 7 connected to the dump control lever 4 is raised and moved to the R position. In the case of lowering L and floating F other than raising R, move the spool 7 in the same manner.

In this way, the hoist valve 1 controlled by the operation of the dump control lever 4 is the third
As shown in the figure, the hydraulic pressure source from the pump 10 is switched to flow to the hoist cylinder 11, and the hoist cylinder 11 is moved up and down.

However, if the hoist cylinder 11 is kept in the raised R or lowered L position, the hoist cylinder 11 will extend and contract to the end of its stroke, and the oil pressure will become high until the safety valve is set. If it remains like this for a long time, the oil temperature will rise and damage various equipment. I was afraid.

The present invention was developed in view of the above circumstances, and its purpose is to prevent the oil from becoming hot due to the high pressure generated when the hoist cylinder expands and contracts to the end of its stroke, thereby preventing damage to various equipment. There is a particular thing.

Hereinafter, the present invention will be explained with reference to FIG. 3 and subsequent figures.

In the drawing, 12 is a vehicle body frame, and 13 is a dump body. A base end of a hoist cylinder 14 is swingably connected to the dump body 13, and a rod 15 of the hoist cylinder 14 is swingably connected to the vehicle body frame 12. Rod 1
A lever 16 is fixed to the end of the lever 5. Further, first and second air valves 17 and 18 are attached to the vehicle body frame 12 and are actuated by contact with a lever 16 caused by the swinging of the rod 15.

What is shown in FIG. 6 is an explanation of the configuration of the hoist control device for a dump truck according to the present invention, and what is shown in FIG.
19 is an air reservoir, 20, 21, and 22 are dump control air valves operated by the dump control lever 4, and 23 and 24 are first and second valves for operating the hoist valve 26. 2 cylinders,
25 is a compressor.

The hoist valve 26 has the same structure as the hoist valve 1 shown in FIG. 1, and the spool 27 of the hoist valve 26 is automatically set to the holding position by a neutral spring 28.

The spool 27 is connected by a pin 30 to one end of a lever 29 having a swing center P in the center, and the piston rod 31 of the first cylinder 23 is connected to one end of the lever 29 by this pin 30. There is.

A long hole 33 is formed at the end of the piston rod 32 of the second cylinder 24.
A pin 34 at the other end of the lever 29 is inserted into the hole.

Further, a breather 24c is provided in the head side chamber 24a of the second cylinder 24.

The discharge side of the air reservoir 19 is connected to the input ports 20a, 21a, 22a of each dump control air valve 20, 21, 22, and the port 20b of the dump control air valve 20 on the lowering side is connected to the 2 cylinders 24
The second air valve 18 is connected to the rod side chamber 24b of the first pipe line 35. Port 21b of dump control valve 21 on floating side
is connected to the head side chamber 23a of the first cylinder 23 via a second conduit 36. Also, the port 22b of the dump control valve 22 on the upward side is the third port.
It is connected to the rod side chamber 23b of the first cylinder 23 via a pipe line 37, the first air valve 17 is provided in the third pipe line 37, and the port 21c of the dump control valve 21 on the floating side is connected to the fourth pipe line 37. 38 to the port 18a of the second air valve 18.

Further, the operation circuit for the hoist cylinder 14 has the same configuration as that in FIG. 3.

Next, the operation will be explained.

FIG. 6 shows the holding state, in which air is not sent from the dump control air valves 20, 21, 22 to the first and second cylinders 23, 24, and the spool 27 of the hoist valve 26 is a neutral spring. 28, it is automatically set to the holding H position.

Now, when the dump control lever 40 is raised and operated to R, the dump control air valve 22 is opened, air from the air reservoir 19 enters the rod side chamber 23b of the first cylinder 23, and air from the head side chamber 23a is transferred to the second pipe 36, It escapes to the outside air via the dump control air valve 21, the fourth pipe line 38, and the second air valve 18.

For this purpose, the first cylinder 23 is compressed to move the spool 27 of the hoist valve 26 up to the R position.

Therefore, the hoist cylinder 14 is extended and the dump body 13 is tilted backward.

When the hoist cylinder 14 is fully extended, the lever 16 operates the first air valve 17 to close the third conduit 37, and the rod side chamber 23b of the first cylinder 23 communicates with the atmosphere via the first air valve 17. No air is supplied to the first cylinder 23 side, the spool 27 of the hoist valve 1 is returned to the neutral position by the neutral spring 8, and the hoist valve 26 is placed in the holding H state.

Further, when the dump control lever 40 is lowered and operated to L, the dump control air valve 20 is opened and air from the air reservoir 19 enters the rod side chamber 24b of the second cylinder 24. Air in the head side chamber 24a escapes into the atmosphere from the breather 24c.

Therefore, the second cylinder 24 is contracted and the spool 27 of the hoist valve 26 is moved down to the L position.

Therefore, the hoist cylinder 14 is contracted and the dump body 13 is lowered.

When the hoist cylinder 14 is in its most compressed state, the lever 16 operates the second air valve 18.

For this purpose, air from the air reservoir 19 is transferred to the dump control air valve 20, the first pipe 3
5, second air valve 18, fourth pipe line 38, floating side dump control valve 21, second pipe line 36
It flows into the head side chamber 23a of the first cylinder 23 through the first cylinder 23, and expands the first cylinder 23.

Therefore, the spool 27 of the hoist valve 26
is converted from lowering L to floating H.

As mentioned above, in the raised R state, the hoist valve 26 is automatically switched from raised R to hold H when the hoist cylinder 14 rises, and in the lowered L state, the hoist valve 26 is automatically switched when the hoist cylinder 14 descends. The hoist valve 26 is switched from lowering L to floating E.

When the hoist valve 26 is in the holding state H and floating state F, the hydraulic pressure source 10 is connected to the tank 10' as shown in FIG. This eliminates high pressure and increases in oil temperature.

Since the present invention is as detailed above, the raised R
In this state, when the hoist cylinder 14 rises, the hoist valve 2 is automatically changed from raising R to holding H.
6 is switched, and when the hoist cylinder 14 is lowered to lower L, it will automatically lower to L when the hoist cylinder 14 is lowered.
It is possible to prevent the oil from becoming hot due to the high pressure generated when the hoist valve 26 is switched from to float E and the hoist cylinder 14 expands and contracts to the stroke end.

This prevents damage to each device due to the high temperature of the oil.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram of a hoist valve operating device using a conventional hoist control device, FIG. 2 is a configuration explanatory diagram of a conventional hoist control device, and FIG. 3 is a hoist cylinder operating circuit diagram.
Figure 4 is a side view of the dump truck, Figure 5 is the side view of the dump truck, and Figure 5 is the side view of the dump truck.
FIG. 6 is an enlarged view of part V in FIG. 6, an explanatory diagram of the configuration of a hoist valve operating device using a hoist control device according to the present invention, and FIG. 7 is an explanatory diagram of the configuration of an embodiment of the present invention. 14 is a hoist cylinder, 17 is a first air valve, 18 is a second air valve, and 26 is a hoist valve.

Claims (1)

[Scope of utility model registration request] Raise R, hold H, lower L of hoist valve 26
and the first and second cylinders 23 and 24 for positioning the four positions of the float F, and the second air cylinder 2 by operating the dump control lever 40.
Dump control air valve 20 on the lower side that supplies and shuts off air to the rod side chamber 24b of No. 4.
, a dump control air valve 21 on the floating side that supplies or cuts off air to the head side chamber 23a of the first air cylinder 23 by operating the dump control lever 40; The dump control air valve 22 on the raising side supplies and cuts off air to the rod side chamber 23b, and switches to operate when the hoist cylinder 14 is extended to cut off the supply of air to the rod side chamber 23b of the first cylinder 23. a first air valve 17 that discharges air to the atmosphere to bring the hoist valve 26 into the holding H state; and a dump control air valve 21 on the floating side that switches when the hoist cylinder 14 is contracted and controls the air supplied to the second cylinder 24. The head side chamber 2 of the first air valve 23 is
3a to bring the hoist valve 26 into a floating state.