JPS5925693B2 - Cargo box lifting device in transport vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cargo box lifting device for a transport vehicle such as a truck.

Conventionally, in transportation vehicles such as trucks, the floor surface of the cargo box is located at a high position from the ground, and therefore there is a problem in that it is difficult to handle cargo between the cargo box and the ground.

Therefore, we have proposed a system in which the cargo platform is pushed down against the upward force of the suspension system when loading cargo, lowering the floor surface of the cargo box, and raising the cargo box when traveling so that the buffering effect of the suspension system is not restricted. It was done.

However, in conventional systems, the operating member for operating the lifting device for the cargo box is installed separately near the driver's seat, and the cargo box can only be raised or lowered by the driver operating the operating member. Ta.

Therefore, if the cargo box is lowered by mistake while driving,
Since the suspension system becomes locked and the cushioning effect is no longer working, the cargo box will vibrate as the axle moves up and down, causing problems such as not only the cargo being damaged or thrown off, but also damage to the vehicle body. Ta.

In order to solve the above-mentioned drawbacks, the present invention utilizes a sliding door that is always rotated downward when loading cargo, so that the lifting device for the cargo box can be operated in conjunction with the rotation of the sliding door. 1 is a pair of chassis frames 1 supported by a rear axle 3 via a leaf spring 2 which is a suspension device, and a load is mounted on the chassis frame 1. Box 4 is installed.

The cargo box 4 is composed of a floor plate 5, a front plate 6, side panels 7, and a sliding door 8, and the sliding door 8 rotates vertically at the rear lower part of the floor board 5 so that the rear part of the cargo box 4 can be opened and closed. It is pivotally supported 9 so that it can move, and when it is rotated upward, the rear part of the cargo box 4 is secured in a closed state by a locking device 10 attached to both side plates 7.

Reference numeral 11 denotes a switch mounted on the chassis frame 1 below the swing door shaft fulcrum 9, that is, at the lower rear of the cargo box 4. This switch 11 is a switch that the swing door 8 comes into contact with when the swing door 8 is rotated downward. The structure is such that it connects to an electric circuit, which will be described later.

Reference numeral 12 denotes a fluid pressure cylinder device for moving the chassis frame 1 closer to the rear axle 3 against the upward force of the leaf spring 2. As shown in FIG.
A triangular link member 14 with one end pivotally supported at the rear of the crossbeam 13, which is hung between the pair of chassis frames 1 so as to be able to move up and down.
A hook was passed between the hydraulic cylinder 15 whose base end was pivotally supported on the bottom of the crossbeam 13 and whose tip was pivotally supported on the other end of the link member 14, the rear axle 3 and the other end of the link member 14. The chassis frame 1 approaches the rear axle 3 when the hydraulic cylinder 15 is extended.

A protrusion 17 is provided on the front end side of the hydraulic cylinder 15, and when the hydraulic cylinder 15 extends a certain amount, the protrusion 17
comes into contact with the limit switch LS to "break" an electric circuit, which will be described later.

Next, the hydraulic circuit for operating the hydraulic cylinder 15 will be explained with reference to FIG. 3. A hydraulic pump 18 driven by an electric motor M and the hydraulic cylinder 15 are connected in a main channel 20 with a check valve 19 interposed in the middle. An auxiliary flow path 22 leading to a tank 21 is branched between the hydraulic cylinder 15 and the check valve 19 of the main flow path 20.

This auxiliary flow path 22 is equipped with a switching valve 23 that shuts off or communicates the auxiliary flow path 22, and this switching valve 23 is connected to a parking brake lever 24 via a rod 25, so that when the brake is actuated ( The auxiliary flow path 2 (dotted chain line in Figure 3)
2 is cut off, and when the brake is released (solid line in Figure 3), the auxiliary flow path 22 is brought into communication.

Reference numeral 26 denotes a flow path which is branched from between the pump 18 and the check valve 19 in the main flow path 20 and communicates with the tank 21, and an IJ-F valve 27 is interposed in the flow path 26.

Next, the electric circuit that controls the electric motor M will be explained with reference to FIG. 4. A first circuit 28 and a second circuit 29 are connected in parallel to the power supply, and a first circuit 28 and a second circuit 29 are connected in parallel to each other. The switch 11, the limit switch LS placed close to the hydraulic cylinder 15, and the relay R are provided in series, and the second circuit 2
9, a relay switch r and an electric motor M are provided in series.

In the embodiment, the switching valve is linked to the parking brake, but it may also be linked to the rotation of the sliding door or a change in the speedometer. To explain an example when the switching valve 23 is
When the solenoid SQL is energized, it is pressed by a spring 30 to connect the auxiliary flow path 22, and when the solenoid SQL is energized, it is switched against the force of the spring 30 and the auxiliary flow path 22 is cut off.

As shown in FIG. 6, the electrical circuit of the solenoid SQL includes a first circuit 31, a second circuit 32, and a third circuit 33 connected to the power supply in parallel, and the first circuit 31 includes a switch 11, a limit switch LS, and a relay R1. Furthermore, a relay R2 is provided in a fourth circuit 34 which is branched from between the switch 11 of the first circuit 31 and the limit switch LS and is provided in parallel to the first circuit 31, and a relay R2 is provided in the second circuit 32. A motor M is provided in series, and a relay switch r2 and a solenoid SQL are provided in series in the third circuit 33.

In addition, in the embodiment, the switching valve is provided in the middle of the auxiliary flow path,
Even if it is provided at a branch point from the main flow path, the present invention can be satisfied.

The present invention has the above-mentioned structure, and its operation will now be explained. When loading cargo onto the cargo box of a transportation vehicle, first, the parking brake lever 24 is moved to the third position so that the transportation vehicle does not move.
When the parking brake is operated by turning to the position indicated by the dashed line in the figure, the switching valve 23 blocks off the auxiliary flow path 22 in conjunction with the rotation.

In this state, rotate the fan door 8 downward (dotted chain line in Figure 1).
When the rear of the cargo box 4 is opened, the sliding door 8 comes into contact with the switch 11, and the switch 11 is turned on. At this time, the limit switch LS is turned on, so the first circuit 28 is activated, and the relay is activated. Electrify R.

As a result, the relay switch r becomes "closed", energizing the electric motor M, and the electric motor M starts rotating.

The pump 18 is driven by the rotation of the electric motor M, and oil is supplied to the hydraulic cylinder 15 through the main channel 20, and the hydraulic cylinder 15 expands, thereby causing the chassis frame 1 to resist the upward force of the leaf spring 2. Then, the vehicle approaches the rear axle 3, and the cargo box 4 is lowered.

When the cargo box 4 is lowered a certain distance, the protrusion 17 of the hydraulic cylinder 15 comes into contact with the limit switch LS, turning off the limit switch LS and cutting off the power to the relay R.

As a result, power to the electric motor M is also cut off, the pump 18 is stopped, and the lowering of the cargo box 4 is also stopped and held at the lowered position.

In this way, cargo is loaded with the floor plate 5 of the cargo box 4 at its lowest position.

The same applies when loading and unloading luggage. When loading is finished, the sliding door 8 is rotated upward (solid line in Figure 1), and the locking device 1 is
0 secures the fan door 8 to the side plate 7.

At that time, the switch 11, which was in the "on" position, was turned "off", and in order to run the vehicle, the 1 parking brake lever and the 2 -2 levers were pressed.
4 to the position shown by the solid line in Figure 3 to release the parking brake, the switching valve 23 will communicate with the auxiliary flow path 22, which had previously been extended against the force of the leaf spring 2. The hydraulic cylinder 15 contracts, and the cargo box 4 rises to its normal state due to the warp.

When traveling in this state, the hydraulic cylinder 15
Since the leaf spring 2 is connected to the tank 21 through the
can fully exert its buffering effect without being locked.

As described above, the present invention provides a transportation vehicle that rotates the sliding door at the rear of the cargo box downward, opens the rear of the cargo box, and loads and unloads cargo from the rear of the cargo box. This makes it possible to operate one drive source for lowering the cargo box, so there is no need for a separate operation to operate the drive source, and there is no need for an operation to be performed only when loading or unloading cargo.
In other words, since the drive source can be operated only when the sliding door is rotated downward, there is no possibility of erroneous operation such as the cargo box being lowered while the vehicle is traveling.

[Brief explanation of the drawing]

Fig. 1 is an overall view of a transport vehicle equipped with the present invention, Fig. 2 is an overall view of the fluid pressure cylinder device, Fig. 3 is a hydraulic circuit diagram, Fig. 4 is an electrical circuit diagram, Figs. 5 and 6. is another example. 1 is the chassis frame, 3 is the rear axle, 4 is the cargo box, 8
1 is a fan door, 11 is a switch, 12 is a fluid pressure cylinder device,
20 is a main flow path, 22 is an auxiliary flow path, 23 is a switching valve, and M is an electric motor.

Claims (1)

[Claims] 1.Equipped with a pair of chassis frames supported on an axle via a suspension device such as a leaf spring, and a cargo box provided on the chassis frame with a sliding door at the rear, and the sliding door can be rotated downward. Therefore, in a transportation vehicle in which the rear of the cargo box is opened and cargo is loaded and unloaded from the rear of the cargo box, the chassis frame is suspended from the crossbeam that is passed between the pair of chassis frames. A fluid pressure cylinder device is provided that operates to move closer to the axle against the pressure, and a pump that operates the fluid pressure cylinder device and a cylinder of the fluid pressure cylinder are communicated through a main pipe, and the operation of the pump is controlled by the fan door. A cargo box elevating device for a transport vehicle that is operated by a motor that is started by downward rotation.