JP2002087143A - Load receiving platform elevating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a load from falling from a load receiving platform when a vehicle is stopped while tilting. SOLUTION: A tilting valve 22 is controlled on the basis of a detected angle between a bed tilt angle sensor 53 and a tilt sensor 51, thereby keeping the load receiving platform 12 horizontal at an upper limit position. A lowering valve 25 is opened by a lowering switch 40, and pressure oil of a cylinder device 15 is discharged by the weight of the load receiving platform 12. When the load receiving platform is grounded, a tilt angle detected by the tilt sensor 51 is taken in from a table, and an oscillating action for lowering a tip end side of the load receiving platform 12 by the tilt angle. When the load receiving platform 12 is lifted up, the oscillating action for lifting the tip end side of the load receiving platform 12 by the original tilt angle is conducted by controlling the tilting valve 22. A lifting valve 23 is opened by a lift-up switch 41 to supply pressure oil into the lift cylinder device, thereby moving the load receiving platform 12 to the upper limit position. By detecting a tilt angle of the load receiving platform when stopping on a slope, the load receiving platform is kept horizontal, so that a load can be prevented from falling down from the load receiving platform even when loading/unloading on the slope.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loading / unloading device, and more particularly to a technique for securing a horizontal position of a loading device.
For example, the present invention relates to a technology that is effective when used for a loading / unloading device that is installed at the rear of a truck.

[0002]

2. Description of the Related Art In order to facilitate loading and unloading of luggage with respect to the rear part of a cargo truck, there is a truck equipped with a loading / unloading device at the rear of the truck. 2. Description of the Related Art Generally, a pallet truck lifting device includes a lift arm whose one end is rotatably supported on the pallet, and the pallet is rotatably supported at a free end of the lift arm. A tilt cylinder device that opens and closes the loading tray is interposed between the loading platform and the loading platform so as to form a parallel link in cooperation with the lift arm, and a lift arm is provided between the lifting arm and the loading platform. A lift cylinder device that raises and lowers the load receiving table by rotating is interposed. The tilt cylinder device and the lift cylinder device are driven by pressure oil of a hydraulic pump driven by a motor when closing the loading tray by the tilt cylinder device or when lifting the loading tray by the lift cylinder device, and when opening the loading tray. When the loading tray is lowered, the motor is not driven and operates by the weight of the loading tray.

That is, a lift cylinder device and a tilt cylinder device are branched and connected to a main oil passage to which pressure oil of a hydraulic pump driven by a motor is supplied / discharged. A lift valve is interposed in the path, and a tilt valve is interposed in the oil path to which the tilt cylinder device is connected. Then, the lift cylinder device is operated by the opening / closing operation of the lift valve in accordance with a command from the controller, and the lift arm is rotated. Similarly, the tilt cylinder device is operated by the opening / closing operation of the tilt valve to open and close the loading tray. It has become.

In this type of conventional loading tray lifting device, a loading platform tilt angle sensor for detecting a tilt angle of the loading platform with respect to the horizontal and a tilt sensor for detecting a tilt angle of the loading tray with respect to the loading platform are provided. By controlling the tilt valve based on the detection angle of the tilt angle sensor and the detection angle of the tilt sensor, the loading tray is automatically kept horizontal to prevent the load from falling off. .

[0005]

However, in the conventional loading / unloading device, when the vehicle is stopped on a slope or the like, it is determined based on the detection angle of the loading angle sensor and the detection angle of the tilt sensor. Even if the loading tray is controlled to maintain the loading tray horizontal at the upper limit position, when the loading tray is lowered and the loading tray is grounded, the deflection of the loading tray from the horizontal position at the grounding position is achieved. A swing angle corresponding to the inclination angle of the vehicle is generated as the angle. That is, a swing angle is generated depending on whether the vehicle has stopped forward or downward, and the swing angle also varies according to the inclination angle of the vehicle. For this reason, when the vehicle is stopped in an inclined state, when the receiving platform is grounded, a swinging motion is performed to lower the leading end side of the receiving platform according to the swing angle,
After that, when raising, it is necessary to make the receiving table horizontal to the road surface. However, after performing the swinging operation to make the tip end of the loading tray horizontal with respect to the road surface, and moving the loading tray to the upper limit position as it is, the tip end of the loading tray lowers at the upper limit position of the loading tray. There is a risk of falling off from

SUMMARY OF THE INVENTION It is an object of the present invention to provide a loading tray raising / lowering device capable of preventing the load from dropping from the loading tray even when the vehicle stops in an inclined state.

[0007]

According to the present invention, there is provided a lifting / lowering device for a receiving cradle according to the present invention.
A lift cylinder device that moves the lift member up and down, a tilt cylinder device that opens and closes the loading tray, a lift valve that controls the lift cylinder device, a tilt valve that controls the tilt cylinder device, and the lift cylinder device And a discharge valve for controlling the expansion and contraction operation of the tilt cylinder device, and a loading table elevating device including a controller for controlling the lift valve, the tilt valve and the discharge valve, A loading platform inclination angle sensor for detecting an inclination angle, a tilt sensor for detecting a tilt angle of the loading platform with respect to the loading platform, and a memory for storing a tilt angle of the loading platform at a ground contact position; and The tilt valve is controlled based on the detection angle of the carrier tilt angle sensor and the detection angle of the tilt sensor. And the tilting angle when the loading tray is grounded by controlling the discharge valve is stored in the memory and the tip end of the loading tray is lowered. Performing the swinging operation by controlling the tilt valve, and then performing the swinging operation by controlling the tilt valve to raise the tip end of the loading tray to the stored tilt angle when raising the loading tray, It is characterized in that the lift valve is controlled to move the receiving table to an upper limit position.

In the above-described means, the tilt angle when the loading tray is grounded is stored, and the tilting operation for lowering the tip end of the loading tray is performed. Thereafter, when the loading tray is raised, the tilt angle is stored. Since the cradle swings up to the tilt angle and moves the cradle to the upper limit position, the cradle tip does not lower even when the vehicle is tilted.
Luggage can be prevented from falling off.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

As shown in FIGS. 2 and 4, a loading tray lifting device 10 according to the present invention is installed at the rear end of the loading platform 2 of the truck 1. That is, the loading platform elevating device 10 includes a pair of lifting arms 11 as lifting members, and both lifting arms 11, 11 are arranged symmetrically at the rear end of the loading platform 2 and one end of each is rotated. It is freely supported. A loading table 12 is rotatably supported between the free ends of both lift arms 11,11. The loading tray 12 is formed of a material having corrosion resistance and rigidity, such as aluminum or iron, and is formed in a rectangular panel shape having a size corresponding to the loading tray 2. A cart stopper 13 is laid along the rear end near the end (hereinafter referred to as a rear end) on the upper surface of the loading tray 12 opposite to the loading platform 2. It is configured to prevent a loaded cart (not shown) from falling off.

A pair of tilt cylinder devices 14, 14 for opening and closing the loading tray 12 are symmetrically arranged between the lower surface of the trailing edge of the loading tray 2 and the front edge of the loading tray 12. Both tilt cylinder devices 1
Reference numerals 4 and 14 denote the loading tray 12 of the lift arm 11.
It is configured to reciprocate between a vertical posture and a horizontal posture with the support shaft as a rotation center. A pair of lift cylinder devices 15, 15 for raising and lowering the load receiving table 12 are interposed symmetrically between the lower surface of the rear end side of the load table 2 and the rear ends of the lift arms 11, 11, respectively. And both lift cylinder devices 15 and 15 are lift arm 1
The load receiving table 12 is moved up and down between a height position of the load table 2 and a ground contact position by rotating the load table 1 about a support shaft on the load table 2 side as a rotation center.

When the lift arms 11, 11 are moved up and down by the lift cylinder devices 15, 15, the tilt cylinder devices 14, 14 form a parallel link with the lift arms 11, 11. This allows
At the time of lifting and lowering, the loading tray 12 can maintain the horizontal posture.

As shown in FIG. 1, each of the tilt cylinder device 14 and the lift cylinder device 15 uses a single-acting hydraulic cylinder device. The tilt cylinder device 14 operates so as to close the loading tray 12 with the pressure oil supplied from the hydraulic pump 17 driven by the DC motor 16. Further, the lift cylinder device 15 operates so as to raise the loading tray 12 by the pressure oil of the hydraulic pump 17. When the loading tray 12 is opened, the pressurized oil supplied to the tilt cylinder device 14 is discharged by its own weight to be opened. When lowering the loading tray 12, the pressure oil supplied to the lift cylinder device 15 is discharged by its own weight to be lowered. The tank 18 is connected to the suction port of the hydraulic pump 17, and the main oil passage 1 connected to the discharge port of the hydraulic pump 17 is connected to the tank 18.
9 is an oil passage from the middle to the tilt cylinder device 14 (hereinafter, referred to as an oil passage).
This is called a tilt oil passage. ) 20 and the lift cylinder device 1
An oil passage 21 (hereinafter, referred to as an oil passage for lift) 21 is provided.

A control valve (hereinafter referred to as a tilt valve) 22 for controlling expansion and contraction of the tilt cylinder device 14 is provided in the tilt oil passage 20, and a lift cylinder device is provided in the lift oil passage 21. A control valve (hereinafter, referred to as a lift valve) 23 for controlling expansion and contraction of 15 is interposed. Both the tilt valve 22 and the lift valve 23
It consists of two ports, two positions, a spring offset, and an electromagnetic switching valve. A control valve (hereinafter, referred to as a lowering valve) 25 and a check valve 24 are provided in the main oil passage 19 in series with the hydraulic pump 17.

A discharge oil passage 27 is connected to the main oil passage 19 so as to bypass the hydraulic pump 17 and the check valve 24. A control valve (hereinafter, referred to as a discharge valve) 28 that controls expansion and contraction operations of the tilt cylinder device 14 and the lift cylinder device 15 is interposed in the discharge oil passage 27. The discharge valve 28 is constituted by a flow proportional valve. The discharge valve 28 increases and decreases the flow rate of the pressure oil in proportion to the command current from the computer, and optimally controls the raising / lowering operation and the opening / closing operation of the loading table 12. That is, the discharge valve 28 controls the operation of opening the load receiving table 12 by its own weight and the operation of lowering the load receiving table 12 by its own weight, and also tilts the hydraulic pump 17 from the hydraulic pump 17 when the load receiving table 12 is raised or closed. A part of the pressure oil sent to the cylinder device 14 or the lift cylinder device 15 is diverted by the discharge oil passage 27, and by controlling the flow rate of the diverted pressure oil, the closing operation and the raising operation of the loading tray 12 are also controlled. It is supposed to. A relief oil passage 19a is branched from the middle of the main oil passage 19 between the hydraulic pump 17 and the check valve 24 and is connected to the discharge oil passage 27. A relief valve 30 is interposed in the middle of the relief oil passage 19a. Has been established.

The DC motor 16 is connected to a battery 32 via a relay switch 29a of a motor relay 29. The battery 32 is connected to a power terminal 35a of the controller 35 via the main switch 33. The relay coil 29b of the motor relay 29 is connected to a motor relay terminal 35b. Further, a rotation sensor 34 for detecting the number of rotations is connected to the DC motor 16, and the rotation sensor 34 is connected to a motor rotation detection terminal 35 c of the controller 35.

The solenoid of the discharge valve 28 is connected to a current detection terminal 35 d of the controller 35 via a current detection resistor 31.
And is connected to a flow proportional valve terminal 35e. The solenoid of the lowering valve 25 is connected to a lowering valve terminal 35f of the controller 35, the solenoid of the lifting valve 23 is connected to a lifting valve terminal 35g of the controller 35, and the solenoid of the tilting valve 22 is connected to the controller 35. It is connected to the tilt valve terminal 35h.

The main oil passage 19 has a pressure sensor 3 for detecting a pressure at a connection portion between the lift oil passage 21 and the tilt oil passage 20.
6 is connected, and the output end of the pressure sensor 36 is connected to the pressure sensor terminal 35i of the controller 35.

An operation box 37 is connected to an operation signal terminal 35j of the controller 35.
Reference numeral 7 denotes a switch (hereinafter, referred to as an open switch) 38 for instructing an opening operation of the receiving tray 12, a switch (hereinafter, a close switch) 39 for instructing a closing operation of the receiving tray 12, and a load receiver. A switch (hereinafter, referred to as a lowering switch) 40 for instructing a lowering operation of the table 12.
And a switch (hereinafter, referred to as an up switch) 41 for instructing a lifting operation of the loading tray 12, and a reference value setting operation switch 42 and a reference value set switch 43 used for a reference value setting operation are provided. ing.

The input end of the controller 35 has a receiving tray 12
, A lift sensor 52 for detecting the lift position of the loading platform 12, and a loading platform tilt angle sensor 53 for detecting the loading platform 2 tilt angle.

As shown in FIGS. 2 and 4, the tilt sensor 51 is installed at a mounting portion between the load receiving table 12 and the lift arm 11, and measures the inclination of the load receiving table 12 with respect to the lift arm 11. It is configured to detect the opening angle of the receiving table 12. The lift sensor 52 is provided on the lift arm 11,
The height position of the load receiving tray 12 is detected by detecting the rotation angle of. Cargo tilt angle sensor 5
Numeral 3 denotes an inclination angle with respect to the loading platform 2 which serves as a reference for measuring the inclination of the loading platform 12 and the horizontal. In FIGS. 2 and 4, it is depicted as being attached to the loading platform 2; Is mounted on a board of a controller 35 installed on the loading platform 2.

The controller 35 is constituted by a microcomputer or the like, and detects programs and tables stored in a memory, the rotation sensor 34, the pressure sensor 36, the tilt sensor 51, the lift sensor 52, and the platform inclination angle sensor 53. Based on the value, the motor relay 29
And the operation of the discharge valve 28, the lowering valve 25, the lift valve 23, and the tilt valve 22.

Next, the loading / unloading device 1 according to the above configuration
The operation of 0 will be described.

In FIG. 1, when the condition for supplying the pressure oil is satisfied in a state where the main switch 33 is turned on, the relay coil 29b is connected to the controller 35.
And the relay switch 29a is turned on. As a result, the voltage of the battery 32 is
6 and the hydraulic pump 17 is rotationally driven by the DC motor 16, so that the pressure oil of the hydraulic pump 17 is supplied to the main oil passage 19. At this time, the controller 35 detects the rotation speed of the DC motor 16 from the rotation sensor 34 and calculates the pump flow rate of the hydraulic pump 17.

When the raising switch 41 is operated,
The solenoid of the lift valve 23 is excited by the controller 35 to switch the lift valve 23, and the pressure oil from the hydraulic pump 17 is supplied to the main oil passage 19 and the lift oil passage 21.
Is supplied to the lift cylinder device 15 via the above, and the receiving table 12 is raised.

Conversely, when the lower switch 40 is operated, the solenoid of the lift valve 23 is excited by the controller 35 and the solenoid of the lower valve 25 is excited and switched by the controller 35.
The pressurized oil inside is discharged by the weight of the loading tray 12 and returned to the tank 18 via the lift valve 23, the lowering valve 25, and the discharge valve 28.

When the close switch 39 is operated,
The solenoid of the tilt valve 22 is excited by the controller 35 to switch the tilt valve 22, and the pressure oil from the hydraulic pump 17 is supplied to the main oil passage 19 and the tilt oil passage 20.
, And is fed to the tilt cylinder device 14 to close the receiving table 12.

Conversely, when the open switch 38 is operated, the solenoid of the tilt valve 22 is excited by the controller 35, and the solenoid of the lowering valve 25 is excited and switched by the controller 35.
The pressurized oil inside is discharged by the weight of the loading table 12 and returned to the tank 18 via the tilt valve 22, the lowering valve 25, and the discharge valve 28.

Next, the operation of the controller for the horizontal maintenance control at the upper limit position of the loading tray when the loading tray 12 is moved up and down will be described with reference to the flowchart shown in FIG.

The first step shown in FIG.
It is called S1. This applies to each step. 4), the tilt valve 22 is controlled on the basis of the detection angle of the bed inclination angle sensor 53 and the detection angle of the tilt sensor 51, and as shown in FIG. Is maintained horizontal.

When the loading tray 12 is kept horizontal, it is determined in S2 whether the lowering switch 40 is on. If the down switch 40 is not on (NO), S2 is repeated. When the down switch 40 is on (YES)
Then, the controller 35 proceeds to S3.

In step S3, the solenoid of the lift valve 23 is excited in accordance with the operation of the lowering switch 40, and the solenoid of the lowering valve 25 is excited. As a result, the pressure oil in the lift cylinder device 15 is discharged by the weight of the load receiving table 12 and returned to the tank 18 via the lift valve 23, the lowering valve 25, and the discharge valve 28.

As shown in FIG. 4B, when the loading table 12 comes into contact with the road surface, the tilt angle detected by the tilt sensor 51 is stored in the memory of the controller 35 in S4. .

In step S5, a swing operation of lowering the distal end side is executed by controlling the tilt valve 22 as shown in FIG. 4C.

In S6, it is determined whether the raising switch 41 is on. If the raising switch 41 is not on (NO), S6 is repeated. Raise switch 41
Is ON (YES), the controller 35 proceeds to S7.

In S7, when the loading tray 12 is raised, the tilt valve 22 is controlled in S7 in order to perform a swinging operation of raising the tip side of the loading tray 12 by the tilt angle used in S5.

At this time, the detection angle of the tilt sensor 51 is monitored in S8, it is determined whether or not the tilt angle is the tilt angle stored in S4, and the current tilt angle is set to the tilt angle stored in S4. S7 and S8 are repeated until it becomes. Then, as shown in FIG. 4B, when the tilt angle has reached the stored tilt angle (YES), the process proceeds to S9.

In step S9, the solenoid of the lift valve 23 is excited according to the operation of the up switch 41. As a result, the pressure oil from the hydraulic pump 17 is supplied to the lift cylinder device 15 via the main oil passage 19 and the lift oil passage 21, and the load receiving pedestal 12 is raised.

When the receiving tray 12 reaches the upper limit position, as shown in FIG.
4 by the swing operation of S7 and S8 in FIG.
Since the original tilt angle of S4 shown in (b) is returned to the original state, even if the truck 1 is stopped on a slope or the like, the luggage on the loading tray 12 is removed from the loading tray 12. Dropping can be prevented.

As described above, according to the present embodiment, even when the lorry 1 is stopped on a slope or the like, the loading tray 12 at the upper limit position is kept horizontal.
Even when the luggage is lifted or lowered while the lorry 1 is stopped on a slope, it is possible to prevent the luggage on the loading tray 12 from falling off the loading tray 12.

It should be noted that the present invention is not limited to the above-described embodiment, but may be made without departing from the scope of the invention.
It goes without saying that various changes are possible.

For example, the lift member is not limited to be constituted by a lift arm having one end rotatably supported on a shaft, but may be constituted by an elevator supported at the rear end of the loading platform so as to be able to move up and down.

The controller 35 is not limited to being constituted by a microcomputer, but may be constituted by other electric circuits.

[0044]

As described above, according to the present invention,
Even if the vehicle is stopped in a state where the vehicle is inclined, it is possible to automatically prevent the load from dropping from the receiving tray.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a lifting / lowering device of a pallet truck according to an embodiment of the present invention.

FIG. 2 is a perspective view thereof.

FIG. 3 is a flowchart illustrating horizontal maintenance control of the loading tray during lifting and lowering of the loading tray.

FIG. 4 is a side view showing each operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lorry car, 2 ... Carrier, 10 ... Lifting device for cargo carrier, 1
DESCRIPTION OF SYMBOLS 1 ... Lift arm (lift member), 12 ... Loading table, 13
... Cart stopper, 14 ... Tilt cylinder device, 15 ...
Lift cylinder device, 16 DC motor, 17 hydraulic pump, 18 tank, 19 main oil path, 19a relief oil path, 20 oil path for tilt, 21 oil path for lift, 22
... Tilt valve, 23 ... Lift valve, 24 ... Check valve, 25
... lowering valve, 27 ... discharge oil passage, 28 ... discharge valve, 29 ...
Motor relay, 29a relay switch, 29b relay coil, 30 relief valve, 31 current detection resistor,
32: battery, 33: main switch, 34: rotation sensor, 35: controller, 35a: power supply terminal, 35
b: motor relay terminal, 35c: motor rotation detection terminal,
35d: current detection terminal, 35e: current proportional valve terminal, 35
f: Valve terminal for lowering, 35g: Valve terminal for lift, 35h ...
Tilt valve terminal, 35i pressure sensor terminal, 35j operation signal terminal, 36 pressure sensor, 37 operation box,
Reference numeral 38: Open switch, 39: Close switch, 40: Down switch, 41: Up switch, 42: Reference value setting work switch, 43: Reference value set switch, 51: Tilt sensor, 52: Lift sensor, 53: Cargo tilt angle Sensor.

Claims (1)

[Claims] A lift member rotatably supported by a loading platform of a vehicle, a loading tray rotatably supported by the lifting member, a lift cylinder device for lifting and lowering the lifting member, and opening and closing of the loading tray. A tilt cylinder device to be controlled, a lift valve for controlling the lift cylinder device, a tilt valve for controlling the tilt cylinder device, a discharge valve for controlling expansion and contraction operations of the lift cylinder device and the tilt cylinder device, In a loading platform elevating device including a controller for controlling the lift valve, the tilt valve and the discharge valve, a loading platform tilt angle sensor for detecting a tilt angle of the loading platform with respect to the horizontal, and A tilt sensor for detecting a tilt angle with respect to the carrier,
A memory for storing a tilt angle of the loading tray at a ground contact position, wherein the controller controls the tilt valve based on a detection angle of the loading platform tilt angle sensor and a detection angle of the tilt sensor. The loading tray is configured to be kept horizontal, and the tilt angle when the loading tray is grounded is controlled from the memory by controlling the discharge valve, and the tip angle of the loading tray is determined from the tilt angle. Control the tilt valve to perform a swing operation to lower
Thereafter, when raising the loading tray, the tilt valve is controlled to perform a swing operation of raising the tip end side of the loading tray to the tilt angle, and the lift valve is controlled to move the loading tray to the upper limit position. A lifting / lowering device for receiving a cradle, wherein