JPH024829Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an elevating device for the platform of a dump truck, and more particularly to an elevating device for the platform of a dump truck, in which the platform is rotatably supported on a frame and can be raised and lowered by a power cylinder.

A dump truck has a loading platform rotatably supported at the rear end of a frame, and a power cylinder is interposed between the frame and the loading platform. Therefore, by raising the platform, the earth and sand loaded on the platform can easily fall and be lowered, and for this reason, it is widely used in civil engineering work and the like. In order to unload the earth and sand loaded on the loading platform, for example, a dump lever provided on the driver's seat may be operated. In other words, by rotating the dump lever in the upward direction, oil is supplied from the hydraulic pump driven by the engine output to the power cylinder, the piston rod of the power cylinder is pushed out, and the loading platform is raised. It turns out.

In the conventional dump truck, the above-mentioned dumping operation can be freely performed regardless of the vehicle posture of the dump truck. Therefore, even when the vehicle is tilted in the longitudinal direction or in the width direction of the vehicle, the dumping operation of the cargo platform can be performed. However, when the loading platform is raised by a dump operation, the center of gravity of the vehicle becomes higher, making it unstable and possibly causing it to overturn. Therefore, conventionally, the driver has judged this based on experience and feeling, and has determined whether the dump operation is possible. Therefore, with such conventional dump trucks, the lifting operation of the loading platform is not necessarily carried out in a safe manner, and therefore it cannot be expected that the operation will always be carried out safely. .

The present invention was developed in view of these problems, and by making dumping operations impossible when the inclination angle of the vehicle body exceeds a predetermined value, it is possible to create a dump truck with higher safety. The purpose of this invention is to provide a device for lifting and lowering a loading platform.

In order to achieve such an object, the present invention provides a loading platform rotatably mounted on a frame, a hydraulic cylinder that extends and contracts to raise and lower the loading platform, and a dump lever that is manually operated. In the dump truck, the lever is moved from a neutral position to a raised position and a lowered position to extend and retract the hydraulic cylinder, thereby raising and lowering the loading platform. On the other hand, only when the inclination angle of the vehicle body detected through the detection means exceeds a predetermined value, the damping lever is abutted and engaged from the raised position side to push the damping lever in the raised position back to the neutral position. The damping lever is characterized in that a means is provided for preventing the dump lever in the neutral position from being operated to the raised position while allowing it to be operated to the lowered position.

In the lifting device for the loading platform of a dump truck configured as described above, when the tilt angle of the vehicle body is in a normal state, that is, when the tilt angle of the vehicle body is smaller than a predetermined value, the blocking means does not interfere with the dump lever. The dump lever located at the neutral position can be operated to either the raised position or the lowered position, and as the dump lever is operated (moved), the hydraulic cylinder is operated to expand and contract, and the platform is raised and lowered.

However, when the tilt angle of the vehicle body becomes larger than a predetermined value, a tilt signal is output from the detection means. Then, the blocking means, which had been separated from the damping lever up to that point, projects and engages the damping lever from the raised position side, thereby pushing the damping lever back to the neutral position. Furthermore, since the blocking means abuts and engages with the dump lever from the raised position side, even though the damp lever is prevented from moving (operating) from the neutral position to the raised position, It can be moved (operated) to the lowered position.

Therefore, if the tilt angle of the vehicle body is larger than a predetermined value, the dump lever in the neutral position cannot be operated to the raised position, and furthermore, if the tilt angle of the vehicle body is larger than the predetermined value while the loading platform is being raised. Even if the dump lever is pushed back to the neutral position, the height of the loading platform (height of the center of gravity) will not increase beyond that point.

In addition, since the dump lever can be moved (operated) to the lowered position even in this tilted state, the center of gravity is lowered by moving the dump lever to the lowered position, thereby preventing tipping accidents. can do.

In addition, for example, the hydraulic cylinder control circuit does not have an on-off valve, and the movement of the dump lever itself is restricted to prevent the platform from rising when it is tilted, so the hydraulic circuit does not become complicated. Alternatively, since there is no need to increase the number of valves that cause pressure loss, an increase in cost and a decrease in efficiency can be suppressed.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a dump truck according to this embodiment, in which a loading platform 1 includes a frame 2 constituting the vehicle body.
It is rotatably supported at the rear end via a bracket 3 and a hinge pin 4. A hydraulic cylinder 5 is provided between the loading platform 1 and the frame 2 in order to rotate the loading platform 1 about the hinge pin 4. The hydraulic cylinder 5 is connected to an oil pump 7 and a reservoir 8 via a switching control valve 6. Switching of the switching control valve 6 is performed, for example, by a dump lever 9 provided inside the cab of the dump truck.

The dump lever 9 is rotatably supported around a fulcrum pin 10, and a notch 11 is provided in one side of the lower end thereof. The notch 11 is the piston rod 13 of the air cylinder 12.
It is adapted to be engaged with a pin 14 implanted in the. The air cylinder 12 is connected to an air tank (not shown) via a solenoid valve 15. When the solenoid valve 15 is closed, the piston rod 13 is moved back by the return spring 16 provided inside, and the pin 14
The engagement with the notch 11 is released, and the dump lever 9 is in a state where it can freely rotate.

Next, the circuit for rotating the loading platform 1 will be explained with reference to FIG. 2. The battery 17 is connected to the key switch 18 and the power take-off switch 19.
It is designed to be connected to the coil 20 via. Further, the power take-off switch 19 is connected to a parallel circuit of an attitude detection switch 21 that detects the longitudinal attitude of the vehicle body and an attitude detection switch 22 that detects the lateral attitude of the vehicle body. The coil of the solenoid valve 15 and the alarm buzzer 23 are connected to the output ends of the solenoid valves 21 and 22.

In the above configuration, when the loading platform 1 in a horizontal state is to be rotated and raised, the key switch 18 is closed and the power take-off switch 19 is also closed. Then, the battery 17 and the power take-off coil 20 are connected, and the coil 20 is excited. By energizing this coil 20, the engine output is supplied to the oil pump 7 shown in FIG.
The oil pump 7 will be driven. In this state, when the dump lever 9 shown in FIG. 1 is rotated in the upward direction, that is, clockwise, about the fulcrum pin 10, the oil pressurized by the pump 7 is supplied to the hydraulic cylinder 5. The piston rod is pushed out and the loading platform 1 is raised as shown by the chain line in FIG.

When the loading platform 1 has been raised to a predetermined angle, the dump lever 9 is returned to the position shown in FIG.
will be maintained in that state. Next, when the loading platform 1 is to be lowered, the dump lever 9 may be rotated counterclockwise about the fulcrum pin 10, contrary to the above-described operation. Then, since the oil flow is reversed from that in the above case, the loading platform 1 will be lowered.

The above operations are performed when the attitude of the vehicle body is approximately horizontal; however, for example, when the vehicle body is tilted at a predetermined angle or more in the longitudinal direction or the lateral direction, the attitude detection switches 21 and 22 are activated. At least one side will be closed. Note that these switches 21 and 22 are constructed of, for example, mercury switches, and are made conductive when the vehicle body is tilted in the longitudinal direction or in the lateral direction by a predetermined angle or more. and at least one switch 2
1 and 22 are closed, this causes the coil of the solenoid valve 15 to be energized and the sound alarm buzzer 23 to sound.

When the solenoid valve 15 is energized and opened, compressed air is supplied from an air tank (not shown) to the air cylinder 12 through the solenoid valve 15, and the piston rod 13 is pushed out. Accordingly, the pin 14 engages with the notch 11 of the damp lever 9, thereby preventing the damp lever 9 from rotating clockwise. That is, the pin 14 implanted in the piston rod 13 of the air cylinder 12 is connected to the damp lever 9 in the neutral position.
Since it is adapted to engage with the lower end of the notch 11, the dump lever 9 is prevented from rotating further in the clockwise direction, thereby preventing the lifting movement of the loading platform 1. . Also, if the tilt angle of the vehicle body becomes larger than a predetermined value while the loading platform is rising, the piston rod 13 will protrude and operate to prevent pin 1.
4 comes into contact with the notch 11 of the dump lever 9 from the downward direction, so the dump lever 9 is in the raised position.
is pushed back by contact with the pin 14 to prevent the loading platform from rising any further. This prevents the loading platform from rising in a state where the vehicle body inclination is greater than a predetermined value.

Therefore, it is possible to prevent the loading platform from being raised while the vehicle body is tilted in the longitudinal or lateral direction and becoming unstable, thereby raising the center of gravity and making the vehicle body unstable. Safety will be significantly improved. In addition, as mentioned above, pin 14
is designed to engage with the lower end of the notch 11 of the dump lever 9, so even if this notch 11
Even if the pin 14 is engaged with the damp lever 9, it is possible to rotate the dump lever 9 in the downward direction. This is because when lowering the cargo platform, the center of gravity of the vehicle body is lowered, making it more stable, and there is no need to prevent even the lowering operation.

Although the present invention has been described above with reference to an illustrated embodiment,
The present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention. For example, the above embodiment relates to a dump truck in which the loading platform is rotatably supported at the rear end of the frame and is tilted rearward.
The present invention can also be applied to, for example, a side dump truck in which the loading platform is rotated to the side. Further, various design changes can be made to the attitude detection switch, the locking mechanism of the dump lever 9, etc. in the above embodiment.

As described above, the present invention includes a means for detecting the inclination angle of the vehicle body of a dump truck, and a means for preventing the upper part of the dump lever from moving in the direction.
When the inclination angle of the vehicle body exceeds a predetermined value, the dump lever is prevented from moving in the raising direction, thereby preventing the loading platform from rising. Therefore, according to the present invention, it is possible to prevent the loading platform from being raised in an unstable state where the vehicle body is tilted, thereby reliably preventing rollover accidents and the like. Furthermore, the movement (operation) of the dump lever is restricted to prevent the cargo bed from rising only when the vehicle body inclination angle exceeds a predetermined value.
There is no need to add a valve to the hydraulic circuit leading to the hydraulic cylinder, thereby simplifying the configuration of the hydraulic circuit. For this reason, it is possible to suppress an increase in the cost of the hydraulic circuit and an increase in pressure loss.Moreover, since the dump lever can be operated in the lowering direction (downward position) in any situation, the dump lever can be moved to the up position. There is no problem caused by locking the device so that it cannot be operated.
In addition, since the structure prevents the dump lever from moving in the raising direction and prevents the loading platform from rising, it is possible to accurately detect whether the vehicle body inclination angle exceeds a predetermined value based on the feeling of operating the dump lever. This can be recognized, and the hydraulic cylinder or the like will not fall into an overload state, making it possible to simplify the hydraulic circuit and increase its safety.

[Brief explanation of the drawing]

FIG. 1 is a side view of a main part showing a lifting device for a dump truck platform according to an embodiment of the present invention, and FIG. 2 is a circuit diagram used in this lifting device. In addition, in the symbols used in the drawings, 1... loading platform, 2
...Frame, 5...Hydraulic cylinder, 6...Switching control valve, 9...Dump lever, 11...Notch, 12...Air cylinder, 14...Lock pin, 15...Solenoid valve,
21... Attitude detection switch (front-back direction), 22... Attitude detection switch (lateral direction).

Claims (1)

[Scope of utility model registration request] a loading platform rotatably mounted on a frame; a hydraulic cylinder that extends and contracts to raise and lower the loading platform;
A dump vehicle is provided with a manually operated dump lever, and the hydraulic cylinder is telescopically operated by moving the dump lever from a neutral position to a raised position and a lowered position to raise and lower the loading platform. a detection means for detecting an inclination angle of a vehicle body of a dump truck; and a detecting means for abutting and engaging the dump lever from a raised position side only when the inclination angle of the vehicle body detected through the detection means exceeds a predetermined value. A dump truck characterized by having a means for pushing the dump lever in the raised position back to the neutral position to prevent the dump lever in the neutral position from being operated to the raised position while allowing it to be operated to the lowered position. Lifting device for car loading platform.