JPS5929448B2 - dump truck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load detection device used for overload prevention in a dump truck.

Although the weight that can be loaded in a dump truck is set, it is difficult to confirm the actual weight loaded, and overloading can cause damage to roads, bridges, etc. This causes accidents such as rollovers inside the vehicle.

The present invention is a load detection device for a dump truck that has been made in view of the above, and is installed in the hydraulic circuit of a tilting telescopic cylinder connected to a dump cargo box, and detects the load of the cargo box and determines a set value. It consists of a sensing mechanism that senses and issues a sensing signal when the above occurs, and a detection electric circuit that has a main switch and a detection actuator that is closed in response to the signal.

Embodiments of the present invention will be described based on the drawings.

Embodiment 1 As shown in FIG. 1, a chassis 2 of a dump truck 1 has a support shaft 3.
A cargo box 4 is mounted so that it can be tilted freely.

A telescopic cylinder 5 for tilting is provided between the cargo box 4 and the chassis 2.
are connected, and the cargo box 4 is raised and lowered by the expansion and contraction of the telescoping cylinder 5.

The telescopic cylinder 5 has a hydraulic circuit 6 as shown in FIG.
is connected to the supply path 7 of the hydraulic circuit 6, and an operation switching valve 8 is connected to the supply path 7 of the hydraulic circuit 6.
A pump 9 is provided via.

A sensing mechanism 10 is connected to the supply path 7.

The sensing mechanism 10 is formed by a pressure switch 11, the operating pressure is set by a spring 12, and the contact 1 is activated when activated.
Close 3.

The contacts 13 of the pressure switch 11 are connected to a detection electrical circuit 14 which includes a main switch 15 which is normally held in the open position, a power source 16 and a detection actuator 17.

The detection actuation body 17 is provided with an alarm, an indicator light, a stop mechanism for the loading device, etc. connected and wired as appropriate.

To explain the effect, when the loading box 4 is slightly raised so that the load of the loading box 4 is applied to the telescopic cylinder 5, the pressure in the supply path 7 increases in relation to the load, and when it exceeds the set pressure of the pressure switch 11. When the contact 13 closes, the detection operating body 17 of the detection electric circuit 14 is activated, and alarms, displays, loading stops, etc. are performed.

Embodiment 2 In this embodiment, as shown in FIG.
An operation switching valve 8 and a pump 9 are installed.

A safety valve 20 is connected in parallel from the supply path 7 to the discharge path 19.

Further, a switch valve 21 and a relief valve 22 are connected in parallel from the supply path 7 to the discharge path 19.

Branching from between the switch valve 21 and the IJ-F valve 22, a sensing mechanism 10 using the pressure switch 11 similar to the previous example is installed.
The contact 13 of the pressure switch 11 is connected to a detection electric circuit 14 having a detection actuation body 17.

The switch valve 21 is a solenoid valve that operates in response to the tilting of the cargo box 4 without being related to the operation of the detection electric circuit 14, and when the cargo box 4 is in a lowered horizontal state, the chassis 2 and the cargo are connected to each other. Limit switch provided between box 4 (not shown)
etc., to enable the relief valve 22 to operate (a mechanical switch valve may also be used; in this case, a limit switch or the like is not required and may be mounted directly on the cargo box or chassis).

The 1,11J-f valve 22 is activated and opened when the supply pressure cuff to the telescopic cylinder 5 is higher than its set pressure, and makes the telescopic cylinder 5 unable to extend in an overloaded state.

In addition, 23 is a reverse valve, which is installed in the supply path γ so that the oil discharged from the pump 9 can pass in the direction (upward in FIG. 3) of supplying the oil to the telescopic cylinder 5, and its set pressure is very small to prevent reverse flow. This is enough to press the valve body to prevent this.

Further, the set pressure of the safety valve 20 is higher than the set pressure of the IJ-F valve 22, and is set to the maximum pressure that prevents damage to the hydraulic circuit 18.

The set pressure of the IJ IJ-f valve 22 is normally set to a hydraulic pressure corresponding to the maximum load of loading, and the set pressure of the pressure switch 11 is set equal to this.

24 is an oil sump.

Next, to explain the first case, when the operation switching valve 8 is switched to the left position (rising side) in order to raise the cargo box 4 from the horizontal state, the oil discharged from the pump 9 is transferred to the supply path 7 and the cargo box 4 is in the horizontal state. It is supplied to the switch valve 21 which is in operation and conduction nearby.

At this time, if the load of the cargo box 4 is large in an overloaded state, the hydraulic pressure in the hydraulic circuit 18 increases, and when the pressure exceeds the set pressure of the pressure switch 11, the contact 13 closes and the detection electric circuit 14 is activated. At the same time, the relief valve 22 is activated and the oil discharged from the pump 9 is returned to the oil reservoir 24. In any case, the hydraulic cylinder 5 does not extend and the cargo box 4 does not rise.

When the loading capacity is appropriate, the oil discharged from the pump 9 is supplied to the supply path 7 and the ° switch valve 21 side, but the pressure must not rise to the level that activates the pressure switch 11 and the relief valve 22. This corresponds to the increase in supply pressure required for elongation.

Example 3 In this example, as shown in FIG.
The hydraulic circuit 25 of the telescopic cylinder 5 for tilting is as shown in Example 1.
Similarly, a pump 9 is connected to the supply path 7 via an operation switching valve 8.
is provided, and a sensing mechanism 26 is connected to the supply path 7.

As shown in FIG. 5, the sensing mechanism 26 includes a rotary plate 30 fixed to the rotating shaft 29 of the pointer 28 of the oil pressure gauge 27, a magnet piece 31 attached to the rotary plate 30, and a magnetic piece 31 attached to the rotating plate 30. A reed switch 32 is fixed at a predetermined rotational position opposite to the reed switch 32, and the reed switch 32 is closed when the magnet piece 31 rotates and approaches.

The reed switch 32 is connected to a detection electric circuit 14 having a main switch 15 , a power source 16 and a detection actuator 17 .

In this example, as in the other side, when the load of the cargo box 4 is large and the pressure in the supply path 7 of the telescopic cylinder 5 increases, the rotating plate 31 moves as the pointer 28 of the pressure gauge 27 rotates. And magnet piece 3
1 is close to the reed switch 32 and the reed switch 3
2 is closed, and the detection operating body 17 of the detection electric circuit 14 is activated.

In addition, in the sensing mechanism 26 of this example, in addition to fixing the magnet piece 31 to the rotary plate 30, the magnet piece 31 is fixed facing the reed switch 32, and the rotary plate 30 having a slit is provided between the magnet pieces 31 and the reed switch 32. Alternatively, the reed switch 32 may be activated when the position of the slit matches the position of the magnet piece 31.

Further, a non-contact switch may be used instead of the reed switch 32.

Therefore, according to the load detection device of the present invention as described above, there is a sensing mechanism that detects the load of a cargo box and operates to generate a sensing signal when the load exceeds a set value, and a main switch that is normally in the open position. and a detecting electric circuit having a detecting actuating body that is closed by the above-mentioned signal, and in order to operate an alarm or the like in the detecting electric circuit when the load exceeds a set value. Overloading of cargo can be easily confirmed and prevented.

Furthermore, by using an existing telescopic cylinder and attaching it to the hydraulic circuit, it can be installed easily and inexpensively.

[Brief explanation of the drawing]

Fig. 1 is a side view schematically showing a dump truck, Fig. 2 is a basic circuit diagram showing Embodiment 1, Fig. 3 is a basic circuit diagram showing Embodiment 2, and Fig. 4 is a basic circuit showing Embodiment 3. FIG. 5 is a sectional view of a main part illustrating the sensing mechanism of the third embodiment. 1...Dump truck, 2...Chassis, 3.
...Spindle, 4...Cargo box, 5...
Telescopic cylinder, 6.18°25...Hydraulic circuit,
10.26... Sensing mechanism, 14... Electric circuit for detection, 17... Detection actuation body.

Claims (1)

[Claims] 1. In the hydraulic circuit of the tilting telescopic cylinder connected to the dump cargo box, the hydraulic circuit detects the weight loaded on the cargo box, and when the weight exceeds a set value, the sensing mechanism is activated and issues a signal. 1. A dump truck characterized in that it has a main switch that is normally held in an open position, and is also equipped with a detection electric circuit that has a detection actuator that is closed by a signal from the sensing mechanism. load detection device.