JP3083962B2 - Cargo handling equipment for cargo handling vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cargo handling device for controlling a tilting speed when a mast is tilted back and forth in a cargo handling vehicle such as a forklift.

[0002]

2. Description of the Related Art A cargo handling device in a cargo handling vehicle such as a forklift includes a mast supported on the front surface of a vehicle body so as to be able to tilt forward and backward, a fork mounted on the mast so as to be able to move up and down, a lift cylinder for moving the fork up and down, It comprises a tilt cylinder that tilts the mast, and a control valve that supplies fluid pressure to the lift cylinder and the tilt cylinder via each liquid flow path.

When loading cargo, the vehicle body is moved forward with the mast slightly tilted forward,
Put the cargo on the fork. After that, the mast is tilted slightly rearward to level the fork, thereby ensuring the stability of the cargo when the vehicle moves. At this time, the operating speed of the tilt cylinder in the tilting operation of the mast is shown in FIG.
As described above, the apparatus is operated at a constant speed regardless of the weight of the cargo to be loaded.

[0004]

In recent years, in order to carry out cargo handling efficiently, the speed of cargo handling devices has been increased and the mast tilting speed has tended to be increased. However, if the tilting speed of the mast is increased, if the weight of the cargo to be loaded is heavy (at the time of maximum load), the load will move at a constant speed, that is, at a high speed from the start. There is a risk that the cargo collapses or the vehicle body falls due to the recoil.

[0005] Therefore, reducing the tilting speed of the mast in anticipation of safety is against the speeding up of the cargo handling work, and when the cargo is not loaded (when there is no load), the mast is not moved. It has been desired to increase the tilting speed of the robot.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a cargo handling device for a cargo handling vehicle that improves the safety by varying the mast tilting speed according to the weight of the cargo.

[0007]

As shown in FIG. 1, a fork 11 mounted on a front surface of a vehicle body 1 and having a front-rear tiltable mast 10 is mounted on the mast 10 so as to be movable up and down. Lift cylinder 12, which raises and lowers
13, a tilt cylinder 14, which tilts the mast 10,
15 and a control valve 17 for supplying fluid pressure to the lift cylinders 12 and 13 and the tilt cylinders 14 and 15 via the respective liquid flow paths 18 and 19, according to the weight of the cargo when the mast 10 is tilted. Tilt cylinder 1
4 and 15 are provided with a tilting speed control means for controlling the operating speed.

The tilting speed control means includes a flow control valve 6 for limiting the flow rate of the fluid flowing through a liquid flow path 19 connecting the control valve 17 and the tilt cylinders 14 and 15.
1, the control valve 17 and the lift cylinder 12,
A pilot pipe 62 for supplying a pilot pressure of the fluid flowing through the liquid flow path 18 connecting the flow path 13 to the flow control valve 61. The flow control valve 61 varies the flow rate of the fluid by the pilot pressure from the pilot pipe 62.

[0009]

In the above means for solving the problems, when loading cargo, the tilt cylinders 14 and 15 are extended to
Lean forward. At this time, since no cargo is placed on the fork 11, the pilot pressure from the liquid flow path 18 is not applied from the pilot pipe 62 to the flow rate control valve 61, and the fluid flowing through the liquid flow path 19 flows through the flow rate control valve 61. Flows to the control valve 17 without being restricted by the
0 leans forward at a faster speed than when the cargo is placed.

[0010] Then, put the cargo on the fork 11,
The mast 10 is tilted backward by shortening the tilt cylinders 14 and 15. At this time, the weight of the cargo is
The pilot pressure is applied to a flow control valve 61 via a pilot pipe 62 and flows through a liquid flow path 19 between the tilt cylinders 14 and 15 and the control valve 17. Is limited to a flow rate according to the weight of the cargo by the flow control valve 61,
The tilt cylinders 14 and 15 are shortened at a lower speed than when no load is applied, and the mast 10 tilts backward slowly. Thereafter, when the cargo becomes horizontal, the shortening of the tilt cylinders 14 and 15 is stopped, and the backward tilt of the mast 10 is stopped. Then, the cargo is kept horizontal on the fork 11.

Next, when unloading the cargo, the tilt cylinders 14 and 15 are extended, and the mast 10 is tilted forward. At this time, a pilot pressure according to the weight of the cargo is applied to the flow control valve 61 from the pilot pipe 62, and the fluid flowing through the liquid flow path 19 between the tilt cylinders 14, 15 and the control valve 17 is subjected to flow control. The valve 61 restricts the flow rate according to the weight of the cargo, and the tilt cylinder 14,
15 extends at a lower speed than when no load is applied, and the mast 10 tilts forward slowly. The cargo is unloaded from the fork 11 without collapse.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, a forklift, which is a cargo handling vehicle of this embodiment, has a drive wheel 2 mounted on a front portion of a lower portion of a vehicle body 1 and a turning wheel 3 mounted on a rear side. And an unillustrated engine and transmission, a drive transmission mechanism for transmitting a driving force from these to the drive wheels 2, and the like, and a cargo handling device 4 is disposed on the front surface of the vehicle body 1. In FIG. 2, 5 is a steering wheel, and 6 is a driver's seat.

As shown in FIGS. 1 and 2, the cargo handling device 4 includes a mast 10 supported on the vehicle body 1 so as to be able to tilt back and forth.
0, and a pair of lift cylinders 12, which lift and lower the fork 11,
13, a pair of tilt cylinders 14 and 15 for tilting the mast 10, a pump 16 driven by rotation of the engine to generate hydraulic pressure, and a hydraulic pressure from the pump 16 to the lift cylinders 12 and 13 and the tilt cylinders 14 and 15. A control valve 17 for supplying, a liquid flow path 18 on the lift side connecting the control valve 17 to the lift cylinders 12 and 13, and a liquid flow path 19 on the tilt side connecting the control valve 17 and the tilt cylinders 14 and 15.
20.

As shown in FIG. 2, the tilt cylinders 14 and 15 have the tail 21 side rotatably mounted on the vehicle body 1 via the pin 22 and the rod 23 side mounted on the mast 10 with the pin 2.
4 so as to be rotatable. The lift cylinders 12 and 13 are arranged at the rear of the mast 10.

As shown in FIG. 1, the control valve 17 includes a lift control valve 30 for controlling hydraulic pressure to the lift cylinders 12 and 13, a tilt control valve 31 for controlling hydraulic pressure to the tilt cylinders 14 and 15, and a pump 16 A diversion valve 32 that diverts the oil pressure from the mast control valve 30 and the tilt control valve 31 and a pump (not shown) to another system is provided in a single casing. The control valve 17 includes a P port to which the pump 16 is connected, a PF port to which a pump to another system is connected, and an A port to which the lift-side liquid flow path 18 is connected.
_{A where one} port is connected to one tilt-side liquid flow path 19
_{B to which two} ports are connected to the other tilt-side liquid flow path 20
_{It has two} ports and a T port to which a tank (not shown) is connected.

[0016] Then, the lift side liquid flow path 18, one side is connected to the A ₁ port of the control valve 17, the other side is connected to the tail side branches near the lift cylinder 12, 13. Also, one tilt-side liquid flow path 19
The one side is connected to the A _2-port of the control valve 17 is connected to the other side is branched in the vicinity of the tilt cylinder 14, 15 to the respective rod 23 side. The other tilt side liquid flow path 20, one side is connected to the B ₂ port of the control valve 17 is connected to the other side is branched in the vicinity of the tilt cylinder 14, 15 to each tail 21 side.

The lift control valve 30 is a three-position switching valve having a five-port a to e, a port is connected to the tilt control valve 31, b port is connected to A ₁ port of the control valve 17, the port c Flow dividing valve 32 through pipe 33
The d port is connected to a connection pipe 34 branched from the pipe 33 between the flow dividing valve 32 and the c port and connected to the tilt control valve 31, and the e port is connected from the P port of the control valve 17 to the flow dividing valve 32. Is connected to a drain pipe 36 which is branched from the pipe 35 and connected to the T port. A lift control lever 37 disposed on the driver's seat 6 is attached to the spool of the lift control valve 30. The first position 30A in which the fork 11 is lifted by the lift control lever 37, and the first position 30A in which the fork 11 is stopped. The two positions 30B and the third position 30C for lowering the fork 11 can be switched freely. The first position 30A connects the db port, the second position 30B connects the ca port, and the third position 30B. The be port is communicated by 30C. Further, return springs 38 are provided at both ends of the lift control valve 30, and a check valve 39 for preventing the flow of hydraulic oil from the d port to the connection pipe 34 is interposed between the d port and the connection pipe 34. Have been.

The tilt control valve 31 is a three-position switching valve having 6 ports f to k.
Is connected to the 7 T ports, g ports are connected to the A _2-port, h port is connected to the B ₂ port, i the port is connected to a port of the lift control valve 30, j port via the connecting pipe 34 The d port of the lift control valve 30 and the pipe 33 are connected to each other, and the k port is connected to the drain pipe 36. A mast tilt lever 40 disposed in the driver's seat 6 is attached to the spool of the tilt control valve 31. The first position 31A in which the mast 10 is tilted backward by the mast tilt lever 40, and the tilt of the mast 10 is adjusted. It is switchable between a second position 31B for stopping and a third position 31C for tilting the mast 10 forward, and i is changed by the first position 31A.
The -f port, the jg port, and the hk port are communicated with each other, the if port is communicated with the second position 31B, and the if port, gk port, and jh port are communicated with the third position 31C. Are communicated with each other. Further, return springs 41 are provided at both ends of the tilt control valve 31, and a check valve 42 for preventing the flow of the hydraulic oil from the j port to the connection pipe 34 is disposed in the connection pipe 34 near the j port. . A throttle valve 43 is disposed in each of the if port and the jg port at the first position 31A and the if port and the gk port at the third position 31C. Further, a pressure control valve 44 is interposed in the passage of the g-k port at the third position 31C downstream of the throttle valve 43 in the flow direction of the hydraulic oil, and the pressure control valve 44 is connected to the j-h port. Is operated by the pilot pressure from the passage. The throttle valve 43 and the pressure control valve 44 control the oil pressure to the tilt cylinders 14 and 15 and the pressure of the return oil from the rod 23 side when the tilt control valve 31 is operated, so that the tilt cylinders 14 and 15 Operation is prevented.

The flow dividing valve 32 has three ports 1 to n. Even if the flow rate from the P port changes, it senses the pressure of the PF port and keeps the flow rate flowing to the PF port as constant as possible. It has the function of diverting. And
The l port is connected to the c port of the lift control valve 30 via a pipe 33, is connected to the d port of the lift control valve 30 and the j port of the tilt control valve 31 via a connection pipe 34, and the m port is a communication pipe. The port 45 is connected to the PF port, and the port n is connected to the port P via the pipe 35. In addition, a relief pipe 46 communicating with a drain pipe 36 from a P port to a T port is connected to a communication pipe 45 from the m port to the PF port of the flow dividing valve 32, and a communication pipe 45 is connected to the relief pipe 46. A relief valve 47 for flowing hydraulic oil to the drain pipe 36 when the inside reaches the operating pressure is arranged. In FIG. 1, reference numeral 48 denotes a relief valve from the P port to the drain pipe 36, 49 and 50 are throttle valves, 51 is a check valve, and 52 and 53 are guide pipes.

In this embodiment, the tilting speed control means for controlling the operating speed of the tilt cylinders 14, 15 in accordance with the weight of the cargo so that the cargo does not collapse when the mast 10 is tilted. Is provided. This tilting speed control means includes a flow control valve 61 for limiting the flow rate of hydraulic oil flowing through the tilt-side liquid flow path 19 between the control valve 17 and the tilt cylinders 14 and 15, and a flow control valve 61 for controlling the control valve 17 and the lift cylinders 12 and 13. The pilot pressure of the hydraulic oil flowing through the lift side liquid flow path 18
And a pilot pipe 62 provided to the controller.

The flow control valve 61 is of a load sensing type disposed in the middle of one of the tilt side liquid flow paths 19, and is provided with a pilot pressure from a pilot pipe 62 to allow the tilt cylinders 14, 15 from the rod 23 side. Variable return oil flow. That is, the variable flow rate of the flow control valve 61 is set so that the tilting speed of the mast 10 is reduced in inverse proportion to the weight of the cargo, as shown in FIG.

One side of the pilot pipe 62 is connected to the middle of the liquid passage 18 on the lift side, and the other side is connected to the flow control valve 61. The pilot pipe 62 provides the flow control valve 61 with an operating oil pressure of the lift-side liquid flow path 18, that is, a pilot pressure according to the lift cylinder internal pressure applied by the weight of the cargo to be loaded.

In the above configuration, when loading cargo, the fork 11 is first stopped at the lowest position, and the mast tilting lever 40 is operated forward. Then, the tilt control valve 31 of the control valve 17 is moved to the third position 31.
C, the hydraulic oil from the pump 16 flows from the branch valve 32 through the pipe 33 to the tank via the ca port of the lift control valve 30 and the if port of the tilt control valve 31, and from the pipe 33 It flows to the j port of the tilt control valve 31 via the connection pipe 34, and flows from the B ₂ port of the control valve 17 to the other tilt side liquid flow path 20 via the jh port. And the tilt cylinders 14, 15
The hydraulic oil is sent to the tail 21 side of the mast 10, the rod 23 extends, and the mast 10 leans forward. At this time, since no cargo is placed on the fork 11, the lift-side liquid flow path 18
Pressure from the pilot pipe 62 to the flow control valve 61, the rod 2 of the tilt cylinders 14, 15
Return oil from 3 side, from one of the tilt side liquid flow path 19 without being limited by the flow control valve 61 via the A _2-port of the control valve 17, g of the tilt control valve 31
The port is returned from the −k port to the tank through the drain pipe 36, and the extension speed of the tilt cylinders 14, 15, that is, the forward tilting speed of the mast 10, is faster than when the cargo is placed as shown in FIG. Tilt at speed.

When the mast 10 is tilted slightly forward, the mast tilt lever 40 is switched to the stop side to stop the extension of the tilt cylinders 14 and 15. Then, the mast 10 is tilted slightly forward, and in this state, the vehicle body 1 is advanced so that the fork 11 is inserted into a lower portion of the cargo, and the cargo is placed on the fork 11.

[0025] Thereafter, when switched to the rear tilt-side mast tilting lever 40, the tilt control valve 31 is switched to the first position 31A, the hydraulic oil via the A ₂ port from the j-g ports of the tilt control valve 31, whereas Flows through the tilt-side liquid flow path 19 to the rod 23 side of the tilt cylinders 14 and 15, the tilt cylinders 14 and 15 are shortened, and the mast 10 tilts backward. At this time, the weight of the cargo is
The pilot pressure is applied to the flow control valve 61 via a pilot pipe 62, and the hydraulic oil flowing through one tilt-side liquid flow path 19 is
The flow rate is controlled by the flow control valve 61 to a flow rate corresponding to the weight of the cargo, and the tilt cylinders 14 and 15 are shortened at a lower speed than when no load is applied, and the mast 10 tilts backward slowly. Then, when the mast 10 is tilted rearward and the cargo becomes horizontal, the mast tilt lever 40 is switched to the stop side to stop the shortening of the tilt cylinders 14 and 15. Then, the rearward inclination of the mast 10 stops, and the cargo is kept horizontal on the fork 11.

Next, when lifting the cargo to a high place such as a shelf, if the lift operation lever 37 is operated upward, the lift control valve 30 is switched to the first position 30A, and the pump 1 is turned on.
6 flows from the flow dividing valve 32 through the pipe 33 and the connection pipe 34 to the d port of the lift control valve 30, and d−
The lift cylinders 12 and 13 are connected from the lift-side liquid flow path 18 through the port a and the port A _{1 of the} control valve 17.
, The lift cylinders 12 and 13 extend, and the fork 11 rises. When the fork 11 reaches a position slightly higher than the shelf, the lift operation lever 3
7 is switched to the stop side, the extension of the lift cylinders 12, 13 is stopped, and the ascent of the fork 11 is stopped. In this state, the vehicle body 1 is moved to position the cargo above the shelves.

[0027] When operating the mast tilting lever 40 before tilt-side, tilt control valve 31 is switched to the third position 31C, the tilt side liquid flow path 20 B from the _second port other of the hydraulic oil control valve 17 Then, the rod 23 flows to the tail 21 side of the tilt cylinders 12 and 13 and extends. At this time, the pilot pressure from the pilot pipe 62 is given to the flow control valve 61 and the tilt cylinder 1
Return oil to the _{A 2} port from the rod 23 side of 4 and 15 is,
The flow rate is controlled by the flow control valve 61 to a flow rate corresponding to the weight of the cargo, the tilt cylinders 14 and 15 extend at a lower speed than when no load is applied, and the mast 10 leans forward slowly. Then, when the lower surface of the fork 11 contacts the shelf,
By operating the mast tilt lever 40 to the stop side,
Is stopped and the vehicle body 1 is moved backward, the cargo is separated from the fork 11 and the cargo is dropped on the shelf.

As described above, the flow rate of the hydraulic oil flowing through one tilt-side liquid flow path 19 is restricted by the flow control valve 61 in accordance with the weight of the cargo, and the mast 10 is driven at a low speed in accordance with the weight of the cargo. Lean forward and backward. Therefore,
At maximum load, the mast 10 moves slowly, and even if the driver mistakenly tilts the mast 10 suddenly, the load of the cargo does not suddenly move and the load does not collapse. Accidents such as falling out of balance will not occur, and even inexperienced drivers can safely load and unload cargo, improving safety. In addition, when the load is light or no load, the mast 10 tilts at a higher speed than at the maximum load, so that the load can be quickly loaded, and the work speed can be increased, and the work efficiency can be improved. improves.

Further, the present invention can be realized by a simple method of merely providing the flow control valve 61 and the pilot pipe 62 in the conventional cargo handling device, and can be easily retrofitted to the vehicle body 1 using existing equipment. There is no need to manufacture new equipment, and the cost can be reduced as a cargo handling vehicle.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention. For example, in the above embodiment, the tilting speed of the mast 10 is gradually reduced from the conventional constant speed. However, as shown in FIG. If it is set, the speed of the cargo handling device can be further increased. Also,
The tilting speed may be set in two stages as shown in FIGS. In this case, this can be realized by interposing a pressure control valve in the pilot pipe 62 and applying a pilot pressure to the flow control valve 61 when the pressure in the lift-side liquid flow path 18 reaches the operating pressure.

The tilting speed of the mast 10 is controlled by arranging the flow control valve 61 in one of the tilt side liquid flow paths 19 of the tilt cylinders 14 and 15 and the control valve 17. The other tilt-side liquid flow path 20 between the cylinders 14 and 15 and the control valve 17
May be arranged.

Furthermore, the pilot pressure of the lift cylinders 12, 13 is directly applied to the flow control valve 61 to vary the flow rate. However, the internal pressure of the lift cylinders 12, 13 is detected by a sensor or the like, and based on the signal, Alternatively, the flow control valve 61 may be controlled.

Furthermore, a load sensing type flow control valve 61 is used as the tilting speed control means. As shown in FIG. 4, a throttle flow path 71 in which a throttle valve 70 is disposed in the tilt liquid flow path 19 is branched. Thus, the tilt-side liquid flow path 19 and the throttle flow path 71 may be switched by the switching valve 72. This is the pilot pressure from the lift side liquid flow path 18,
That is, the switching valve 72 is switched in accordance with the weight of the cargo, and the hydraulic oil passes through the throttle passage 71, so that the mast 1
The tilting speed of 0 becomes slow. Further, if the switching of the switching valve 71 can be operated by the driver, the driver can switch the tilting speed when the mast 10 is tilted forward or backward, respectively. That is, even if the cargo is somewhat heavy, the mast 10 can be tilted at a high speed when the cargo can be safely unloaded (for example, when the cargo is unloaded at a low position or when the height of the cargo is low). Therefore, cargo handling work can be performed efficiently and quickly.

Then, the flow control valve 61 and the pilot pipe 62 are connected to the control valve 17 and the lift cylinder 1.
Although they are provided between the control valves 2 and 13 and the tilt cylinders 14 and 15, they may be integrated in the control valve 17 and integrated.

[0035]

As is apparent from the above description, according to the present invention, the flow rate of the fluid flowing through the liquid flow path from the tilt cylinder to the control valve is limited by the flow rate control valve in accordance with the weight of the cargo. Tilt at a speed corresponding to the weight of the cargo. That is, since the mast moves slowly at the maximum load, even if the driver mistakenly performs a sudden tilting operation of the mast, the load does not suddenly move and the load does not collapse. Further, when the load is light or no load is applied, the mast tilts at a higher speed than at the time of the maximum load, so that it is possible to carry out a quick load operation and to cope with an increase in the speed of the operation. Therefore, an accident such as the vehicle body falling out of balance is not caused, and safety is improved, and work efficiency is improved by speeding up work.

Further, the present invention can be realized by a simple method of providing a flow control valve and a pilot pipe in a conventional cargo handling device, and can be easily retrofitted to a vehicle body using existing devices. There is no need to manufacture, and the cost can be reduced as a cargo handling vehicle.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cargo handling device of a cargo handling vehicle according to an embodiment of the present invention.

FIG. 2 is a side view of a forklift.

FIG. 3 is a diagram showing the relationship between the weight of the cargo and the tilting speed of the mast.

FIG. 4 is a configuration diagram of a cargo handling device according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle main body 10 Mast 11 Fork 12, 13 Lift cylinder 14, 15 Tilt cylinder 17 Control valve 18 Lift side liquid flow path 19 Tilt side liquid flow path 61 Flow control valve 62 Pilot pipe

Claims (1)

(57) [Claims] 1. A mast capable of tilting forward and backward is supported on a front surface of a vehicle body, and a lift cylinder for raising and lowering a fork attached to the mast so as to be able to move up and down, a tilt cylinder for tilting the mast, the lift cylinder and the tilt A control valve for supplying fluid pressure to the cylinder through each liquid flow path, and a tilting speed control means for controlling an operation speed of the tilt cylinder according to the weight of the cargo when tilting the mast is provided , The tilting speed control means
Connects the control valve and tilt cylinder
Flow control valve that limits the flow rate of the fluid flowing through the flowing liquid flow path
And the control valve and the lift cylinder are connected
Controlling the pilot pressure of the fluid flowing through the flowing liquid flow path
And a pilot pipe provided to the valve.
The flow rate of the fluid by the pilot pressure from the pilot pipe
Handling apparatus handling vehicle, characterized in that the variable.