JPH0457600B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for controlling the operation of a load push-pull in a load push-pull type lift truck.

BACKGROUND TECHNOLOGY In recent years, with lift trucks such as forklifts, when loading and unloading loads on a loading section such as a fork or a platen, the loads are moved in synchronization in the opposite direction to the movement of the lift truck. There is a so-called load push-pull type lift truck designed to streamline cargo handling operations. As disclosed in, for example, Japanese Patent Application Laid-Open No. 57-195098, this lift truck includes a pantograph-like push-pull mechanism that moves the face plate on the platen back and forth by hydraulic operation, and a push-pull mechanism provided at the bottom of the face plate, which is hydraulically operated. It is equipped with a gripper mechanism that grips and releases the sheet pallet. When stacking the cargo on the platen, first, the gripper mechanism grips the sheet pallet laid under the cargo and moves the lift truck forward.
At this time, by moving the push-pull mechanism backward in synchronization with the amount of advance of the lift truck,
It becomes possible to stack the cargo on the platen without moving the ground position of the cargo. On the other hand, when loading and unloading cargo from the platen, the push-pull mechanism is advanced in synchronization with the retreat of the lift truck, and the face plate pushes out the cargo, making it possible to load and unload the cargo without moving the ground position. .

By the way, the load push-pull operating device disclosed in JP-A-57-195098 is provided with a vehicle speed detector and a face plate speed detector in order to automatically synchronize the push-pull mechanism movement and the vehicle movement. Since the oil amount controller is controlled based on the signals from both of these detectors, the device becomes complicated. Therefore, an oil discharge means that is driven by the movement of the vehicle and discharges an amount of oil corresponding to the amount of ground movement of the vehicle is designed to greatly simplify the structure by directly operating a push-pull mechanism.
This was proposed by the present applicant as Japanese Patent Application No. 306800/1983.

That is, this patent application No. 61-306800 is provided with an automatic circuit for operating the push-pull mechanism by the oil discharging means, and a manual circuit for operating the push-pull mechanism by normal lever operation.
An auto mode by the auto circuit and a manual mode by the manual circuit are selected by a mode select switch. Therefore, if you select auto mode,
The push-pull mechanism is operated by hydraulic oil discharged from the oil discharge means as the vehicle moves.

Problems to be Solved by the Invention However, in the load push-pull control device in which the push-pull mechanism is operated by the hydraulic oil selected by the mode select switch and discharged from the oil discharge means, it is difficult to If the operator (driver) accidentally switches the mode select switch to the auto mode side when the vehicle is simply running without loading or unloading, the push-pull mechanism will be activated because the oil discharge means will be driven. In particular, if the mode select switch is erroneously operated while the vehicle is traveling backwards with cargo loaded on the platen, the face plate of the push-pull mechanism will move forward on the platen. Then, there was a problem in that the face plate pressed against the cargo, causing the cargo to collapse or fall.

Therefore, the present invention focuses on the fact that the vehicle speed is low when loading and unloading luggage, but the vehicle speed when simply driving is high to a certain extent.If the vehicle speed is high to a certain extent, even if the mode select switch is switched to the auto mode, the push-pull mechanism It is an object of the present invention to provide a load push-pull control device for a lift truck in which the lift truck is prevented from being activated.

Means for Solving the Problems In order to achieve the above object, the load push pull control device for the lift truck of the present invention has a face plate provided above the cargo loading section as shown in FIG. , a load push-pull type lift truck equipped with a push-pull mechanism a that moves back and forth using hydraulic pressure, and that moves the push-pull mechanism a back and forth in synchronization with the direction opposite to the movement of the vehicle, which is driven as the vehicle moves. The amount of hydraulic fluid approximately corresponding to the amount of ground movement of the vehicle is supplied to the push-pull mechanism a.
a hydraulic fluid discharging means b for supplying the hydraulic fluid to the push-pull mechanism a; a hydraulic fluid management means c for supplying and blocking the hydraulic fluid discharged from the hydraulic fluid discharging means b to the push-pull mechanism a; a switching means d for switching to the side or the blocking side; a vehicle speed determining means e for determining whether the vehicle speed is less than or equal to a predetermined value; When d is set to the hydraulic fluid supply side, a prohibition means f is provided to set the hydraulic fluid management means c to the cutoff side.

Effect With the above-described configuration, the load push-pull control device for a lift truck of the present invention has the following functions even when the switching means d is set to the hydraulic fluid supply side when the vehicle speed is above a predetermined value. The prohibition means f allows the hydraulic fluid management means c to be set to the cutoff side. Therefore,
Even if the operator accidentally switches the switching means d to the hydraulic fluid supply side when the lift truck is simply running when the vehicle speed exceeds a predetermined value,
Activation of the push-pull mechanism will be prevented.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

That is, FIG. 2 shows a load push pull control device 10 for a lift truck showing one embodiment of the present invention.
This load push-pull control device 10 is used, for example, in a lift truck 100 as shown in FIG. That is, this lift truck 100 is a so-called load push-pull type lift truck, and a platen 101 (fork) serving as a cargo loading portion is mounted on a mast 10 erected in front of a vehicle body 102.
3, 104 via a lift cylinder 105 so as to be movable up and down, and a load push pull 110 is integrally attached above the platen 101. The platen 101 is mounted on a rail 106 fixed to a lift bracket (not shown) that moves along the masts 103 and 104 so as to be movable left and right. The load push-pull 110 includes a push-pull mechanism 111 and a gripper mechanism 112, and the push-pull mechanism 111 is supported integrally with the platen 101 on the rail 106 so as to be movable left and right, as shown in FIG. a pantograph-shaped lift mechanism 113,
A face plate 114 attached to the tip of this link mechanism 113, and a push-pull cylinder 1 that expands and contracts the link mechanism 113 using hydraulic pressure.
It consists of 15. On the other hand, the gripper mechanism 112 includes a grip portion 1 that is provided at the lower end of the face plate 114 and can be opened and closed in the vertical direction.
16, and a gripper cylinder (not shown) that opens and closes the grip portion 116 using hydraulic pressure.

The masts 103 and 104 are of a tilt type that can be tilted forward, and are tilted via a tilt cylinder (not shown), and
The platen 101 and the load push pull 1
10 is adapted to be side-shifted via a shift cylinder (not shown).

Furthermore, in the lift truck 100 of this embodiment, a seat retainer 117 is attached to the lower end of the rail 106 for use when recovering a sheet pallet placed under cargo. This sheet retainer 117 is provided with a grip portion for gripping a sheet pallet, similar to the gripper mechanism 112, and this grip portion is operated by a sheet retainer cylinder (not shown).

By the way, the load push-pull control device 10 shown in FIG. 2 particularly shows a hydraulic circuit 12 for operating the load push-pull 110 and the seat retainer 117, and 115 in the figure is a push-pull cylinder, 118 is a gripper cylinder, and 119 is a seat retainer cylinder. The push-pull cylinder 115 and the gripper cylinder 118 are arranged in parallel with each other, and the push-pull cylinder 115 has a rearward cylinder chamber 115a.
and the grip side cylinder chamber 118a of the gripper cylinder 118 are connected to the first hydraulic pressure supply circuit 14, and the push side cylinder chamber 115b of the push-pull cylinder 115 and the release side cylinder chamber 118b of the gripper cylinder 118 are connected to the first hydraulic pressure supply circuit 14. and are connected to the second hydraulic pressure supply circuit 16. A counterbalance valve 2 as a pressure control valve is provided upstream of the hydraulic fluid supply circuits 18 and 20 of the push-pull cylinder 115, which communicate with the first and second hydraulic pressure supply circuits 14 and 16, respectively.
Further, on the upstream side of the counterbalance valves 22 and 24, an electromagnetic switching valve 26 for supplying and cutting off hydraulic oil to the push-pull cylinder 115 is provided. Note that among the counterbalance valves 22 and 24, the extrusion side cylinder chamber 115
The balance valve 24 in b can be replaced with a throttle valve with a check valve. Further, the seat retainer cylinder 119 is arranged in parallel with the push-pull cylinder 115, and the supply and cutoff of hydraulic oil to the seat retainer cylinder 119 is performed by the electromagnetic switching valve 26. That is, the grip side cylinder chamber 119a of the seat retainer cylinder 119
is connected to the second hydraulic pressure supply circuit 16, and the release side cylinder chamber 119a is connected to the first hydraulic pressure supply circuit 14.
When the electromagnetic switching valve 26 cuts off the hydraulic oil supply to the push-pull cylinder 115, the first and second hydraulic pressure supply circuits 1
4 and 16 are supplied to the seat retainer cylinder 119. In addition, on the upstream side of the seat retainer cylinder 119, a throttle valve 28 with a check valve is provided on the side communicating with the gripping side cylinder chamber 119a, and a throttle valve 28 with a check valve is provided on the side communicating with the gripping side cylinder chamber 119a.
A pilot check valve 3 whose pilot pressure is the oil pressure on the second hydraulic pressure supply circuit 16 side is connected to the
0 is set. The push-pull cylinder 115, gripper cylinder 118, seat retainer cylinder 119, counterbalance valves 22, 24, and electromagnetic switching valve 26 constitute a push-pull sequence circuit 32.

The push-pull sequence circuit 32 is supplied with hydraulic oil whose source pressure is the oil discharged from an engine-driven oil pump 36 via a control valve 34. The control valve 34 is of a carry-over type operated by a lever 38, and the operation of the lever 38 switches the hydraulic oil supply to a tilt cylinder, a lift cylinder, a shift cylinder (not shown), and the push-pull sequence circuit 32. It's summery. In addition, when the control valve 34 is in a state where the lever is not operated, the hydraulic oil introduced into the control valve 34 is discharged from the carrier port 34a.

Ports 34b and 34c connected to the push-pull sequence circuit 32 of the control valve 34
and the push-pull cylinder 115 and gripper cylinder 11 of the push-pull sequence circuit 32.
8, the first and second hydraulic pressure supply circuits 1 on the upstream side of the branch point
4 and 16 refer to the third and fourth hydraulic pressure supply circuits 40 and 4.
2, and a manual circuit 44 is constructed between the control valve 34 and the push-pull sequence circuit 32 via third and fourth hydraulic pressure supply circuits 40 and 42. On the other hand, the carryover port 34a of the control valve 34
is connected to an orbiter 48 as a hydraulic fluid discharge means via a circuit 46, and left and right discharge ports 48a, 48b of the orbiter 48 are connected via fifth and sixth hydraulic pressure supply circuits 50, 52. , are connected to the first and second hydraulic pressure supply circuits 14 and 16 of the push-pull sequence circuit 32, similarly to the third and fourth hydraulic pressure supply circuits 40 and 42. Then, the orbiter 48 and the third,
The auto circuit 54 is connected to the push-pull sequence circuit 32 via the fourth hydraulic pressure supply circuits 50 and 52.
is configured.

When operating the load push pull 110, the manual circuit 44 is activated by operating the lever 38.
a manual mode in which pressure is supplied to the push-pull sequence circuit 32 via the
8, an auto mode in which hydraulic pressure is supplied via an auto circuit 54 can be switched by a mode changeover switch 56. Note that even when the mode changeover switch 56 is switched to the auto mode, the lever 3 of the control valve 34
8 operation, hydraulic oil can be supplied to the manual circuit 44, and the position of this lever 38 is input to the controller 58.

The orbiter 48 is generally known as a control valve for power steering for cargo handling vehicles, and its function is to discharge an amount of oil corresponding to the amount of rotation input to the input shaft, for example, the rotation angle of the steering wheel. This discharged oil is used for steering.

FIG. 5 is a cross section of the orbiter 48,
In the housing 200, left and right discharge ports 48a and 48b are formed spaced apart in the axial direction, and a tank port 201 and a pump port 202 are formed spaced apart in the circumferential direction from the left and right discharge ports 48a and 48b. ing. The left discharge port 48a is connected to the fifth hydraulic pressure supply circuit 50 of the auto circuit 54, and the right discharge port 48b is connected to the sixth hydraulic pressure supply circuit 52.
It is connected to the. In addition, the pump port 201 is a carryover port 34a of the control valve 34.
The tank port 202 is connected to a reservoir tank 60 via a drain circuit 58 .

A cylindrical sleeve 203 is fitted into the housing 200, and a cylindrical spool 204 is closely fitted into the sleeve 203 so as to be relatively rotatable.
In 04, each of the boats 48a, 48b, 201,
202 are formed with appropriate passages. A gear pump 206 is provided at one end of the housing 200 (the right end in the figure), and the internal teeth 205 are eccentric from the central axis.
7 are locked and connected in the rotational direction. The spool 204, the sleeve 203, and the drive 207 are connected to a pin 20 arranged perpendicularly to the axis.
They are connected to each other via 8.
At this time, the pin 208 is fitted into the sleeve 203 and the drive 207 without any play, but it is fitted into the spool 204 with some play in the circumferential direction (for example, a rotation angle of 10 degrees). ing. In addition, the spool 204 and the sleeve 203
A leaf spring 209 is provided between the leaf springs 209 and 209.
Centering of the spool 204 and sleeve 203 in the rotational direction is performed by this. Further, the spool 204 is provided with a housing 2.
The input shaft 62 (first
(see figure) is designed to be spline fitted.

When the orbit roll 48 is in a neutral state where no rotational force is input, the spool 204 and the sleeve 203
is centered and pump port 201
The hydraulic oil introduced from the left and right discharge ports 48
It is returned to the reservoir tank 60 from the tank port 202 without being discharged from a, 48b.
Next, when the vehicle is moving, when rotational force is input to the spool 204 via the input shaft 62, the spool 204
04 and the sleeve 203 are rotated relative to each other, and the hydraulic oil introduced from the pump port 201 is transferred to the gear pump 2.
Supplied within 06. Then, the internal teeth 205 of the gear pump 206 are moved from the spool 2 by the hydraulic pressure at this time.
04 rotates, and at this time, when the vehicle is in forward motion, hydraulic oil is supplied to the right discharge port 48.
When the vehicle is in a backward state, the hydraulic oil is discharged from the left discharge port 48a. Furthermore, when the internal teeth 205 rotate, the drive 207 and pin 2 rotate accordingly.
08, the sleeve 203 connects to the spool 2.
Rotate to follow the 04 rotation. Therefore, while the spool 204 continues to rotate, the sleeve 203 continues to follow with a slight phase difference, and hydraulic oil is continuously discharged from the right discharge port 48b or the left discharge port 48a, and this hydraulic oil The total discharge amount is approximately proportional to the amount of movement of the vehicle. Also,
When the push-pull cylinder 115 is operated by the hydraulic oil discharged from the orbit roll 48,
Face plate 11 of push-pull mechanism 111
4 is the push-pull cylinder 115 so that it is moved substantially synchronously in the opposite direction to the longitudinal movement of the vehicle.
, the discharge amount of the orbit roll 48, or the diameter of the rolling element 64 are determined. In detail, in this embodiment, the operating amount of the push-pull mechanism 111 is set to be slightly ahead of the discharge amount of the orbit roll 48. By doing this, the amount of movement of the vehicle and the amount of movement of the face plate 114 are actually generally synchronized.

By the way, the orbit roll 48 is attached to the mast 1 of the lift truck 100 as shown in FIG.
03, and 152 rotations of the wheels are input to the orbiter 48 via a chain 150. That is, in the wheel 152, as shown in FIG.
62, and as shown in FIG. 7, a small diameter sprocket 172 is provided on the transmission shaft 170 of the orbit roll 48, and the chain 1
50 are now being circulated.

The transmission shaft 170 is rotatably supported by a bracket 174 for fixing the orbit roll 48 to the mast 103, the small diameter sprocket 172 is fixed to one end of the transmission shaft 170, and the other parts of the transmission shaft 170 are fixed to one end of the transmission shaft 170. Large diameter gear 176 at the end
is fixed, and this large diameter gear 174 is meshed with a small diameter gear 176 fixed to the drive shaft 62 of the orbit roll 48. In this way, the rotation speed of the wheel 152 is determined by the large and small diameter sprockets 160, 172 and the large and small diameter gears 174, 1.
76, the speed is increased and transmitted to the orbiter 48.

In this embodiment, in the rotation transmission path from the wheels 152 to the orbit roll 48,
For example, the controller 58 may be located in the middle of the transmission shaft 170.
An electromagnetic clutch 180 is provided which opens and closes in response to a drive signal from the pump, and this electromagnetic clutch 180 is used as a hydraulic fluid management means. Therefore, the electromagnetic clutch 1
When the electromagnetic clutch 180 is connected, the rotation of the wheel 152 is transmitted to the orbit roll 48 to operate the orbit roll 48 to discharge hydraulic oil, and when the electromagnetic clutch 180 is disengaged, the Rotational input to the wheels 152 is cut off, the orbiter 48 is stopped, and hydraulic fluid is not discharged.

FIG. 8 shows an electrical circuit 182 for driving the electromagnetic clutch 180.
is built into the controller 58. That is, this electric circuit 182 has a comparator 184 as a vehicle speed determination means and a comparator 184 as a prohibition means.
A NAND circuit 186 is provided, and the comparator 1
An analog voltage signal obtained by converting a pulse-input vehicle speed signal via a D/A converter 188 is input to 84, and compared with a reference voltage set by a reference voltage setter 190, the comparator 184 determines the vehicle speed. It is determined whether or not is greater than a predetermined value, and if it is greater than a predetermined value, an "H" signal is output to the NAND circuit 186. On the other hand, a switching signal from the mode selection switch 56 as a switching means is input to the NAND circuit 186 via the transistor 192, and when the mode selection switch 56 is turned on to select the auto mode, the NAND circuit 186 is set to "L". A signal is now being output. The NAND circuit 1
86 is connected to the electromagnetic clutch 180 via a transistor 194, and when an "H" signal is output from the NAND circuit 186, the electromagnetic clutch 1
80 is turned on and connected. That is, when the vehicle speed is below a predetermined value (the output from the coparator 184 is an "L" signal), the mode changeover switch 5
NAND only when 6 is ON (output is “L” signal)
An "H" signal is output from the circuit 186, and the electromagnetic clutch 180 is turned on. Furthermore, when the vehicle speed is below a predetermined value, the electromagnetic clutch is turned off. In this embodiment, the comparator 184 and the NAND circuit 186 are used as the vehicle speed determining means and the inhibiting means, but it goes without saying that the present invention is not limited to this and that other circuits or mechanisms can be used.

Furthermore, in this embodiment, a normally closed first hydraulic pressure supply circuit operated by a drive signal from a controller 58 is provided between the third and fourth hydraulic pressure supply circuits 40 and 42 of the manual circuit 44.
An electromagnetic on-off valve 70 is provided, and the manual circuit 44 is operated by operating the lever 38 when the vehicle is stopped in auto mode.
When hydraulic oil is supplied to the push-pull sequence circuit 32 from the above, the first electromagnetic on-off valve 70 is automatically switched open when the gripper mechanism 112 completes gripping or release, and the subsequent push-pull sequence circuit The hydraulic oil supply to 32 is cut off. The completion of gripping and releasing of the gripper mechanism 112 is detected by a stroke sensor 72 that detects the time when the push-pull mechanism 111 starts operating.

Further, a normally closed second electromagnetic on-off valve 74 operated by a drive signal from the controller 58 is provided between the fifth and sixth hydraulic pressure supply circuits 50 and 52 of the auto circuit 54. By opening and closing the on-off valve 74, the amount of hydraulic oil supplied from the orbiter 48 to the push-pull sequence circuit 32 is corrected and controlled.

Furthermore, the first electromagnetic on-off valve 7 of the manual circuit 44
The third and fourth hydraulic pressure supply circuits 40 and 42 on the downstream side of 0 and the fifth and sixth hydraulic pressure supply circuits 50 and 52 on the downstream side of the second electromagnetic on-off valve 74 of the auto circuit 54 are connected to each other in pairs. The third and fourth hydraulic pressure supply circuits 40,
42 and the fifth and sixth hydraulic pressure supply circuits 50, 5
Pilot check valves 76, 76a, 78, 78a are provided which use the hydraulic pressure of the opposite circuit of 2 as the pilot pressure, and these pilot check valves 76, 7
6a, 78, and 78a prevent hydraulic oil from flowing from the manual circuit 44 to the auto circuit 54 or from the auto circuit 54 to the manual circuit 44.

The operation of the load push-pull actuating device 10 of this embodiment with the above configuration will be explained below using the flowchart shown in FIG. Note that this flowchart shows an example of a process in which the controller 58 executes a control program.

That is, in the flowchart above, turn on the power
However, when the mode changeover switch 56 is switched to the manual side, the manual mode is set in step 300. Note that in the manual mode, the first and second electromagnetic on-off valves 70 and 74 of the hydraulic circuit 12 are set to the closed side, respectively. In addition, the step 30
When the manual mode is set at 0, in step 301, the stroke sensor 72 detects the initial position S ₀ of the face plate 114 of the push-pull mechanism 111, and the initial rotation angle θ of the orbit roll 48 corresponding to this initial position S ₀ is determined. ₀ , (θ ₀ =k・S ₀ )
k: Find the coefficient and store it.

In the next step 302, the mode changeover switch 5
6 is switched to the auto side. If the auto mode is not set (NO), the process returns to step 300, while if the auto mode is set (YES), the process proceeds to the next step 303.
Incidentally, when the auto mode is set in this way, the electromagnetic clutch 180 is connected and set in a state where the hydraulic oil discharged from the orbiter 48 can be supplied to the push-pull sequence circuit 32.
In step 303, the position of the lever 38 as a manual circuit hydraulic pressure generating means is detected, and it is determined whether the lever 38 is in the neutral position, that is, the state in which hydraulic oil is supplied to the orbit roll 48 from the carryover port 34a of the control valve 34. Whether it is in the push position, that is, a state in which hydraulic oil is supplied to the fourth hydraulic pressure supply circuit 42 of the manual circuit 44, or in the pull position, that is, a state in which hydraulic oil is supplied to the third hydraulic pressure supply circuit 40 in the manual circuit 44. to decide. Then, in step 303, the lever 3
When it is determined that 8 is the neutral position, the process jumps to step 304, when it is determined that it is the push position, the process goes to step 305, and when it is determined that it is the pull position, the process goes to step 306.

In step 304, the first electromagnetic on-off valve 70 is switched to the opening direction, the hydraulic oil supplied from the third hydraulic pressure supply circuit 40 or the fourth hydraulic pressure supply circuit 42 is bypassed, and the push-pull sequence is activated from the manual circuit 44. The state is such that the supply of hydraulic oil to the circuit 32 can be cut off. On the other hand, if the push position or pull position is determined in step 303, the first electromagnetic on-off valve 70 is in the closed state at this point, so the fourth hydraulic pressure supply circuit 42 or the third hydraulic pressure supply The hydraulic oil discharged into the circuit 40 is supplied to the push-pull sequence circuit 32. Then, the push-pull sequence circuit 32 switches the counterbalance valves 22 and 24 to the push-pull cylinder 115.
Since the hydraulic oil is provided upstream of the gripper cylinder 118, the hydraulic oil is first supplied to the gripper cylinder 118. When the lever 38 is in the push position,
Release side cylinder chamber 1 of gripper cylinder 118
18b to release the grip portion 116, and when the lever 38 is in the pull position, hydraulic pressure is supplied to the grip side cylinder chamber 118a of the gripper cylinder 118 to grip the grip portion 116. Activate. Then, in steps 305 and 306, it is determined whether the gripper mechanism 112 has completed release or gripping. The completion of this release or gripping is performed by the stroke sensor 7, and the completion of release is detected when the extrusion operation of the face plate 114 starts, and the completion of gripping is detected when the retraction operation of the face plate 114 starts. When it is determined in step 305 that the release of the gripper mechanism 112 is completed and in step 306 that the gripping of the gripper mechanism 112 is completed (YES), the process proceeds to step 304 and the first electromagnetic on-off valve 70 is opened. The valve is switched to the valve side, and the supply of hydraulic fluid from the manual circuit 44 to the push-pull sequence circuit 32 is cut off. Therefore, the gripper mechanism 112
is placed on standby when the release or grip is completed. If it is determined in step 305 that the release has not been completed, the process returns to step 302, and if it is determined in step 306 that the grip has not been completed, the process returns to step 300. by the way,
In the steps 305 and 306, the gripper mechanism 1
When the operation (release, gripping) of 12 is completed, the lever 38 of the control valve 34 is returned to the neutral position by visual confirmation by the operator, and hydraulic oil is supplied from the carryover port 34a. When the operation is completed, the pilot lamp is turned on or a sound is emitted, thereby making it easier to confirm the completion of the operation.

Next, in step 307, it is determined whether the lever 38 of the control valve 34 is in the neutral position, that is, whether the lever 38 is in the manual circuit 44 or not.
Of course, it is determined that the cylinder is not in the supply position to the tilt cylinder, the lift cylinder, and the side shift cylinder. If it is determined that it is not in the neutral position (NO), the process returns to step 302 again.
If it is determined that the vehicle is in the neutral position (YES), hydraulic oil is being supplied from the carrier over port 34a to the orbit roll 48, and when the vehicle is moved, hydraulic oil is supplied from the orbit roll 48. can be discharged. At this time, since the electromagnetic clutch 180 has been switched to the valve closing side when switching to the auto mode, the hydraulic fluid discharged from the orbit roll 48 is
Push pull sequence circuit 3 from auto circuit 54
2. Therefore, the hydraulic fluid discharged from the orbiter 48 due to vehicle movement is supplied to the push-pull sequence circuit 32 via the auto circuit 54,
12 has already completed the release or grip operation, the counterbalance valves 22 and 24 are in the open state, and the hydraulic fluid is immediately supplied to the push-pull cylinder 115. Therefore, the push-pull mechanism 111 operates almost simultaneously with the start of vehicle movement.
When the vehicle is moving backward, the face plate 114 moves forward in synchronization with this, and when the vehicle is moving forward, the face plate 114 moves back in synchronization with this. Therefore, in the auto mode, the face plate 114
There is no relative movement with respect to the ground when the vehicle moves forward or backward, and it appears that the load supported by the face plate 114 is lowered from above the platen 101 in a fixed position as the vehicle moves backward, and as the vehicle moves forward. The sheets are then loaded onto the sheet pallet gripped by the gripper mechanism 112. When loading and unloading the cargo, there is no delay in the activation of the push-pull mechanism 111 immediately after the start of vehicle movement, so problems such as the cargo shifting do not occur.

In this way, in the auto mode, the push-pull mechanism 111 is operated in synchronization with the movement of the vehicle.
After it is determined in step 307 that the face plate 114 is in the neutral position, in step 308 the amount of movement of the face plate 114 from the reference value (S+S ₀ ) is determined.
is detected by the stroke sensor 72, and the rotation angle position (θ=θ+θ ₀ ) of the orbiter 48 from the reference value as the vehicle moves is calculated. and,
After the next step 309, the push-pull mechanism 11
1 operational correction is made. That is, step 30
At 9, the rotational angular velocity (dθ/dt) of the autobit roll 48 is detected, and the operating state of the push-pull mechanism 111 is determined based on the positive or negative relationship of this rotational angular velocity. If the rotational angular velocity is zero, this indicates that the orbiter 48 is stopped, that is, the vehicle is stopped, and in this case, the process returns to step 302 without performing correction control.

Next, if the rotational angular velocity is positive, it is determined that the vehicle is in the backward movement state (PUSH state), and step 3
10, and if the rotational angular velocity is negative, it is determined that the vehicle is in a forward state (PULL state),
Proceed to step 311. In the step 310, the face plate 1 obtained in the step 308 is
14 has reached the maximum amount δ _a , and if it has reached δ _a (YES), step 1 is executed.
12, the electromagnetic clutch 180 is turned OFF, that is, switched to the disconnection side to stop the operation of the orbiter 48 and cut off the hydraulic oil supply to the push-pull sequence circuit 32, thereby stopping the operation of the push-pull cylinder 115. stop. On the other hand, if it is determined in step 310 that the face plate 114 has not reached the maximum amount δ _a (NO),
Proceed to step 313 and engage the electromagnetic clutch 180.
ON, that is, with the connected state maintained, proceed to step 314, and check whether the difference between the actual stroke S of the face plate 114 and the target stroke kθ obtained from the rotation angle of the orbit roll 48 is larger than a positive value ε close to zero. judge whether In other words, it is determined whether the face plate 114 has moved too much than the target value, and if it has moved too much (YES)
Proceeds to step 315, where the second electromagnetic on-off valve 74
is switched ON, that is, to the valve open side, the hydraulic oil is bypassed, the operation of the push-pull cylinder 115 is temporarily stopped, and then the process returns to step 302. On the other hand, if the determination in step 314 is NO, the process proceeds to step 316, where the second electromagnetic on-off valve 74 is turned OFF, that is, switched or maintained in the closed state, and the push-pull cylinder 11 is turned off.
5 and then returns to step 302. Therefore, the second electromagnetic on-off valve 74
will be used for correction control.

Next, in step 311, it is determined whether the amount of movement S of the face plate 114 has reached the minimum amount δ _b , and if it has reached δ _b (YES), the process advances to step 317 and the electromagnetic clutch 180 is turned OFF. . If δ _b has not been reached (NO), proceed to step 3
Step 18 turns on the electromagnetic clutch 180, and step 319 judges whether the difference between the actual stroke S and the target stroke kθ is smaller than a negative value -θ close to zero. If YES, the process proceeds to step 320, where the second electromagnetic on-off valve 74 for correction control is turned on, and the process returns to step 302. If NO, the process proceeds to step 321, where the second electromagnetic on-off valve 74 is turned off. The process returns to step 302.

In addition, the load push-pull actuating device 1 described above
0 indicates operation in auto mode, but when operating in manual mode, mode selection switch 5
Since 6 is turned off, the electromagnetic clutch 180
is maintained in the disconnected state, and hydraulic oil is supplied from the manual circuit 44 to the push-pull sequence circuit 32 by operating the lever 38, so that the clipper mechanism 112 and the push-pull mechanism 111 can be operated.

By the way, in this embodiment, as shown in FIG. 8, a prohibition means is provided in the controller 58.
Since a NAND circuit 186 is provided, if the operator accidentally switches the mode selection switch 56 to the auto mode side while driving in manual mode, the electromagnetic clutch 180 will be turned on if the vehicle speed is above a predetermined value. This can prevent connections from occurring. That is, when the vehicle is simply moving without loading or unloading cargo (the vehicle speed at this time is relatively high), the electromagnetic clutch 180 is activated.
When connected, the orbiter 48 is activated, hydraulic oil is supplied to the push-pull sequence circuit 32, and the push-pull mechanism 111 is activated. However, in this embodiment, as described above, when the vehicle is simply moving at a speed higher than a predetermined speed, the NAND circuit 186 can cancel the auto mode signal "H" of the mode selection switch 56, so the electromagnetic clutch 180 is
OFF, that is, the disconnected state will be maintained,
Activation of the load push pull 110 can be prevented. In this embodiment, in the manual mode, the electromagnetic clutch 180 is disconnected and no rotational force is input to the orbit roll 48, so that the life of the orbit roll 48 can be significantly improved.

FIG. 10 is a low chart showing the processing in the electric circuit 182 shown in FIG. 8. When a vehicle speed signal is detected in step 350, the absolute value V of the vehicle speed including forward and reverse travel is , and a preset predetermined value δ _c , and if V<δ _c , proceed to step 352 to determine whether the mode is auto mode, and if YES, proceed to step 353, after connecting the electromagnetic clutch 180. Said step 3
Returned to 50. Note that the step 351
If it is determined that V≧δ _c , and in step 35
If it is determined NO (manual mode) in step 2, proceed to step 354 and set the electromagnetic clutch 1.
After turning off 80, the process returns to step 350.

FIG. 11 shows another embodiment, in which a normally closed electromagnetic on-off valve is operated by a drive signal from a controller 58 between the fifth and sixth hydraulic pressure supply circuits 50 and 52 of an auto circuit 54 as a hydraulic fluid management means. 80, the electromagnetic clutch 18 of the above embodiment
0 has been abolished. Therefore, in this embodiment, by setting the electromagnetic on-off valve 80 to the closed side in the auto mode, the orbiter 4
8 can be supplied to the push-pull sequence circuit 32, and by setting the electromagnetic on-off valve 80 to the open side in the manual mode, the left and right discharge ports 48a of the orbiter 48 can be supplied to the push-pull sequence circuit 32. , 48b is drained to the other port through the electromagnetic on-off valve 80, and the supply of hydraulic oil from the auto circuit 54 to the push-pull sequence circuit 32 is cut off.

Therefore, even in this embodiment, when the vehicle speed is above a predetermined value, the electromagnetic on-off valve 80 is set to the closed side even if the mode selection switch 56 is switched to the auto mode side. By providing a prohibition means for preventing this, the same function as in the embodiment described above can be achieved.

By the way, in this embodiment, the orbit roll 48 has a large diameter sprocket and a small diameter sprocket 160, 1
Since the rotation of the wheel 152 is reliably transmitted through the orbiter 72 and the chain 150 without causing any slip, the amount of hydraulic fluid discharged from the orbiter 48 can be reliably synchronized with the amount of vehicle movement. Note that the large diameter and small diameter sprockets 160, 172 are used as driving means for the orbit roll 48.
and chain 150, the first
As shown in FIG. 2, it may be composed of a large diameter gear 161 provided integrally with the wheel 152, and a small diameter gear 173 provided on the transmission shaft 170 of the orbiter 48 and meshed with the large diameter gear 161. . Further, as shown in FIG. 13, the driving means is a large-diameter bevel gear 161a provided integrally with the wheel 152.
A small diameter bevel gear 173a is meshed with the small diameter bevel gear 173a, and the rotation of this small diameter bevel gear 173a is controlled by a universal joint.
The signal may be input to the transmission shaft 170 via a shaft 151 provided with J ₁ and J ₂ .

Incidentally, although the orbit roll 48 has been disclosed as being attached to the mast 103 as shown in FIG.
8 is attached to the mast 103, the load push pull 110 is located near the mast 103, which is effective in terms of layout of hydraulic piping. In addition, the load push-pull type lift truck is
Normally, the masts 103 and 104 are tilted, but this tilt angle becomes extremely small due to the operation of the orbiter 48, and the masts 103 and 104 are tilted.
Since the tilt fulcrum of 04 is the center of the wheel 152 (axle), the relative position between the center of the wheel 152 and the orbit roll 48 remains unchanged. Therefore, the chain 150 and the like will not become loose or become disengaged.

In addition, since the 152 rotations of the wheels are accelerated and input to the orbit roll 48, the discharge capacity of the orbit roll 48 can be reduced to obtain the desired amount of hydraulic oil at a large rotation speed. Therefore, the accuracy of controlling the amount of hydraulic oil discharged from the orbit roll 48 can be greatly improved.

Effects of the Invention As explained above, in the lift truck load push-pull control device of the present invention, when the switching means is set to the hydraulic fluid supply side when the vehicle speed is above a predetermined value, the hydraulic fluid management A prohibition means is provided to set the switching means to the shutoff side, so if the operator accidentally switches the switching means to the hydraulic fluid supply side while the lift truck is running at a speed higher than a predetermined vehicle speed, such as when simply moving a load. In this case, since the hydraulic fluid management means can be held on the blocking side by the inhibiting means, it is possible to prevent the hydraulic fluid from being supplied from the hydraulic fluid discharging means to the push-pull mechanism. Therefore, even if the operator accidentally switches the switching means while the lift truck is moving, the push-pull mechanism will operate and the load on the loading section will not collapse or fall. This has an excellent effect in that it can reliably prevent this from happening.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the concept of a load push pull control device for a lift truck according to the present invention, and FIG.
FIG. 3 is a system diagram showing an embodiment of the present invention, FIG. 3 is a perspective view showing an embodiment of a lift truck in which the load push pull control device of the present invention is used, and FIG. 4 is a diagram of a lift truck according to the present invention. FIG. 5 is a cross-sectional view showing an embodiment of the hydraulic fluid discharging means used in the present invention, and FIG. 6 is a plan view of a push-pull mechanism used in the present invention. 7 is a cross-sectional view of a main part showing the mounting state of the hydraulic fluid discharge means used in the present invention. FIG. 8 is an electric circuit diagram configuring a main part of the load push-pull control device of the present invention. FIG. 9 is a flowchart showing an example of a process for executing a program during load push-pull operation of the load push-pull control device according to the present invention, and FIG. 10 is a flow chart showing the control in the load push-pull control device of the present invention. FIG. 11 is a flowchart showing an example of processing for executing the main part of the program; FIG. 11 is a system diagram showing the main part of another embodiment of the present invention; FIG.
FIG. 3 is a schematic configuration diagram showing other embodiments for driving the hydraulic fluid discharging means used in the present invention. 10... Load push-pull control device, 12... Hydraulic circuit, 32... Push-pull sequence circuit, 4
4...Manual circuit, 48...Orbitroll (hydraulic fluid discharge means), 54...Auto circuit, 56...Mode selection switch (switching means), 58...Controller, 80...Solenoid on-off valve (hydraulic fluid management means), 1
00... Lift truck, 101... Platen (resting part), 110... Load push pull, 111... Push pull mechanism, 114... Face plate, 1
80...Electromagnetic clutch (hydraulic fluid management means), 184
...Comparator (vehicle speed judgment means), 186...
NAND circuit (prohibited means).

Claims (1)

[Scope of Claims] 1. A push-pull mechanism for moving a face plate provided above a cargo loading section back and forth using hydraulic pressure, the push-pull mechanism being moved back and forth in synchronization with the direction opposite to vehicle movement. The load push-pull type lift truck includes: a hydraulic fluid discharge means that is driven as the vehicle moves and supplies the push-pull mechanism with an amount of hydraulic fluid that substantially corresponds to the amount of ground movement of the vehicle; and from the hydraulic fluid discharge means. A hydraulic fluid management means for supplying and cutting off the hydraulic fluid discharged to the push-pull mechanism, a switching means for switching the hydraulic fluid management means to a hydraulic fluid supply side or a hydraulic fluid shutoff side, and determining whether the vehicle speed is above or below a predetermined value. and a vehicle speed determining means for setting the hydraulic fluid management means to the cutoff side when the vehicle speed determining means determines that the vehicle speed is equal to or higher than a predetermined value and the switching means is set to the hydraulic fluid supply side. 1. A load push-pull control device for a lift truck, characterized in that it is provided with a means for inhibiting.