JPS62201799A - Fork retractable detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to a fork insertion/removal detection device for detecting insertion and removal of forks into and from a pallet in a forklift truck equipped with at least two parallel forks.

By conventional technology forklift! Generally, cargo to be transported is placed on a pallet and supported by forks via the pallet. This pallet includes fork insertion portions into which forks can be inserted, and these fork insertion portions are usually separated by a partition wall. Then, the fork is inserted into the fork insertion portion of the pallet, and after the forklift is moved to a predetermined unloading position while supporting the load, the fork is extracted from the pallet.

Problems to be Solved by the Invention The fork is inserted into and removed from the pallet by moving the forklift forward and backward. Conventionally, it has been difficult to detect whether the fork has been properly inserted into or removed from the pallet. Nothing was being done. When a forklift is operated unmanned and transports, loads, and unloads cargo automatically, it is necessary to install a detection device that automatically detects the movement of the fork. was not provided, and if it was to be operated by a man,
The driver could do the work while watching the movement of the fork, but it is not easy to see the fork while driving, and in the end, the driver has no choice but to work based on his senses.

Means for Solving the Problems Against this background, the first invention of the present application is to arrange a projector on one side of two forks facing each other and a light receiver on the other side facing each other. The system detects whether a fork is inserted into or removed from a pallet depending on whether the light traveling from the projector to the receiver is blocked.

Further, the second invention is such that a projector is disposed on one of the mutually opposing side surfaces of the tips of the two forks, and a light receiver is disposed on the other side so as to face each other, and at a position above the base end of the fork. A load detector is provided to detect when the load has reached the base end of the fork, and a first timer is provided to measure the time from when the light receiver stops receiving light until the load detector detects the load. , at least one of a second timer is provided for measuring the time from when the cargo detector stops detecting the cargo until the light receiver receives the light, and the time measured by the at least one of the second timers is a predetermined reference time. A determination means is provided for determining that an abnormality has occurred in the insertion and removal of the fork into and out of the pallet when the fork exceeds this value.

Effect of the first invention When the fork is inserted into the fork insertion part of the pallet, the light emitted from the projector is blocked by the partition wall that partitions between the fork insertion parts, and the light receiver does not receive the light, so that the fork is inserted into the pallet. It is detected that it has been inserted. On the other hand, if the fork is pulled out from the barre 7),
The light from the projector can now be received by the receiver without being blocked by the partition wall, and it is detected that the fork has been pulled out from the pallet.

Effects of the first invention As described above, in the fork insertion/removal detection device according to the first invention, it is possible to determine whether the fork is inserted into the pallet or not.
Furthermore, it is possible to detect whether or not it has been extracted. If a predetermined detection result is not obtained by the detection device, it means that the fork is not correctly inserted into or removed from the pallet.

When a forklift is operated by a man, the driver can know whether the fork is being inserted into and removed from the pallet normally by whether the detection device outputs the expected detection result, and based on this, the forklift The vehicle can be operated reliably. In addition, by installing an appropriate number of such detection devices and selecting their installation positions appropriately, it is possible to detect a desired point in the movement of the fork during insertion and removal from a pallet, regardless of whether the vehicle is being operated manned or unmanned. The state of the fork can be detected.

For example, if two detection devices are provided at the tip and base ends of the fork, it is possible to detect the start and end of insertion of the fork into the pallet, the start and end of extraction, and the detection of the fork. It is possible to detect whether the pallet has been completely inserted into the pallet or whether it has been pulled out.

Effect of the second invention Furthermore, in the fork insertion/removal detection device according to the second invention, in addition to the projector and receiver being provided at the tip of the fork, the load detector is provided above the base end of the fork. When the fork is inserted, the detection result of the load detector is obtained, and when the fork is removed, the light receiver receives light, indicating that the fork is completely inserted into the pallet or completely removed. It will be detected that this occurs. Further, by providing a timer and a determination means in the projector, the light receiver, and the load detector, if an abnormality occurs when the fork is inserted into or removed from the pallet, it will be actively detected. Normally, a forklift is driven at a nearly constant speed when inserting or removing a fork into or out of a pallet, and the time required for the pallet to move relative to the fork between the emitter, receiver, and load detector is fixed. Therefore, by setting the reference time including the error, if the reference time is exceeded, it can be determined that an abnormality has occurred in inserting and removing the fork from the pallet.

Effect of the second invention If it is possible to detect that the fork has been completely inserted and removed from the pallet, the forklift can be moved to the pallet by obtaining the detection result and causing the forklift to perform the next operation. It will not be lifted up if it is only inserted halfway or not fully pulled out, so there is no risk of the cargo falling over. Moreover, since the timer and the determination means can detect at an early stage that an abnormality has occurred in the insertion and removal of the fork into and out of the pallet, the abnormal situation can be quickly dealt with.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 and 2 are diagrams showing a counterbalance forklift truck equipped with a fork insertion/removal detection device according to an embodiment of the present invention. In the figure, 2 is the vehicle body,
Front wheels are driving wheels4. The rear wheel is said to be a steering wheel. The vehicle body 2 is provided with a balance weight 8 at the rear and a head guard 10 above. At the front of the vehicle body 2, as is well known, cargo handling devices including a fork 12, an outer mast 14, and an inner mast 16 are provided. The inner mast 16 is guided vertically by the outer mast 14 via rollers, and this inner mast 16 is further guided by the lift bracket 1.
It is designed to guide you through 8. Lift bracket 18
A finger bar 20 is attached to the finger bar 20 via a side shift attachment 19, and a pair of forks 12 are attached to the finger bar 20. When the inner mast 16 is raised by the operation of the lift cylinder 22, the lift bracket 18 is raised by a chain (not shown). The finger bar 20 and the fork 12 are raised together. The lower end of the outer mast 14 is attached to the vehicle body 2 so as to be rotatable about one axis, and the operation of the tilt cylinder 24 causes the cargo handling equipment including the outer mast 14 to be tilted forward or backward. Further, by the operation of the side shift cylinder 26, the finger bar 20 and the fork 12 are side-shifted relative to the lift bracket 18 in the left-right direction of the vehicle body 2.

This forklift 28 is used for container vanning to load cargo into containers, and can be operated manned by a driver, but can also be operated unmanned by being guided by a guide wall 30 or guide line 32 as shown in FIG. It is possible to do so. The forklift 28 travels while being guided by a guide wire 32 at a location away from the container, and is guided by a guide wall 30 and the subsequent container side walls near and within the container. Lateral displacement sensors 34 and 36 are attached to the sides of the vehicle body 2 to detect the distance and traveling attitude of the vehicle body 2 relative to the guide wall 30 by contacting the guide wall 30. It is designed to be able to run. These lateral displacement sensors 34 and 36 are disclosed in Japanese Patent Application No. 60-1 filed by the present applicant.
It is described in detail in the specification of No. 00846, and
Since it is not essential for understanding the present invention, the explanation will be omitted here.

Further, as shown in FIGS. 1 and 2, big amplifier coils 38 are fixed to the lower surface of the outer mast 14 of the vehicle body 2 with bolts, respectively, for detecting the magnetic field of the guide wire 32 when moving forward. A pair of pickup coils 40 for detecting the magnetic field of the guide wire 32 during backward movement are fixed to the lower surface with bolts.

The load W transported by the forklift 28 is placed on a pallet 42 as shown in FIG. The pallet 42 is a hollow box with openings at both ends, and the inside thereof is partitioned by a support wall 44 extending in a direction perpendicular to the opening, forming a pair of fork insertion portions 46. 12 is forklift 2
8 is inserted into and extracted from the fork insertion portion 46 by moving forward and backward. As shown in FIGS. 1 and 3, a light emitter 48 is concentrically embedded in the opposing sides of the tips of the pair of forks 12, and a light receiver 50 is embedded concentrically in the other. The light projector 48 and the light receiver 50 constitute a photoelectric switch 52 shown in FIG.

The light emitted from the floodlight 48 is
If the fork 12 is inserted into the pallet 42, it will be blocked by the support wall 44 and cannot be received by the light receiver 50. On the other hand, if the fork 12 is pulled out from the pallet 42, the light receiver 5 will not be able to receive it.
It becomes a state where it can be accepted as 0.

As is clear from FIGS. 1 and 2, the fork 12
A load detection device 60 is provided at one end of the frame to which the finger bar 20 is fixed, located above the base end of the frame. As is clear from FIGS. 5 and 6, this load detection device 6° is equipped with a sensor box 62, and this sensor box 62 has two mounting holes 64 formed in one side wall where the finger bar 20 is inserted. It is fixed with bolts to a fixed frame. A cylindrical guide tube 66 is fixed to the sensor box 62 and extends in the front-rear direction (left-right direction in FIG. 6) across its front and rear walls. The rear end opening of this guide tube 66 is connected to the sensor box 62.
Although it is closed by the rear wall, the front end opening opens forward by being fitted into a hole 68 formed in the front wall of the sensor box 62. From the front end opening of the guide wI66, a round bar-shaped contact door 0 that can come into contact with the back surface of the cargo W is slidably inserted in the front-rear direction, and functions as a contact member. Two metal bolts 72 and 74 are screwed into the rear end portion of the contact rod 70 in the diametrical direction with their legs abutting each other, and are inserted from the outer circumferential surface of the contact rod 70 toward its center line. It is fixed in a symmetrical protruding position.

The guide cylinder 66 has two elongated holes 7 passing through its cylinder wall.
6 and 78 are formed along the front-rear direction, and two holes (72.74) are formed through these elongated holes 76 and 78.
is projected to the outside of the guide tube 66. bolt 72
and 74 are movable back and forth within slots 76 and 78, thereby preventing rotation of contact rod 70 about its centerline. A small-diameter portion 80 is integrally provided in a portion of the contact rod 70 that is further rearward than the portion to which the bolts 72 and 74 are fixed, and the resulting shoulder surface and the rear wall of the sensor box 62 are connected to each other. In between, a spring 82 is provided as a biasing means in a pre-compressed state. The contact door 0 is normally biased by the spring 82 to the forward end position where the bolts 72 and 74 are in contact with the front ends of the elongated holes 76 and 78, but when the fork 12 is inserted into the pallet 42, the load It is pushed by W and is made to retreat against the biasing force of the spring 82. The fork 12 is inserted until the load W hits a stopper 84 fixed to the front end of the finger bar 20, and the position of the contact rod 70 in this state is the rearward end position.

When the load W hits the stopper 84, the fork 12 is inserted into the pallet 42 up to its base end, and can support the load W in the most stable state. and,
Contact rod 70 at the rearward end position of sensor box 62
A proximity switch 88 is provided at a position opposite to the bolt 72 .

A bracket 90 is fixed to the sensor box 62 so as to extend in the front-rear direction at right angles to the bolt 72, and a proximity switch 88 is fixed to this bracket 90. The proximity switch 88 includes a detection head 94 that can face the head end face of the bolt 72 with a small gap therebetween, and outputs an output signal when the head end face of the bolt 72 comes to face the detection head 94. emanate.

FIG. 7 shows a control circuit for controlling the unattended running of the forklift 28 as described above. In this figure 12
0 is a microprocessor (CPU: central processing unit), which is connected to the 10 interface 124 together with the memory 122 . The I10 interface 124 includes the above-mentioned photoelectric switch 52 and proximity switch 88, as well as
Lateral displacement sensors 34, 36. pickup coil 38
In addition to 40 and 40, various sensors necessary for operating the forklift 28 unmanned are connected.

The I10 interface 124 further includes a travel control circuit 1.
40. Steering control circuit 142. A brake control circuit 144 and a cargo handling control circuit 146 are connected, a drive motor 148 for driving the drive wheels 4 is connected to the travel control circuit 140, and a steering motor 150 for steering the steering wheel 6 is connected to the steering control circuit 142. It is connected. Further, an electromagnetic brake 152 that brakes the motor shaft of the drive motor 148 is connected to the brake control circuit 144, and an electromagnetic valve 156 that controls the oil pressure to the hydraulic brake 154 that brakes each drive wheel 4.
is connected. The cargo handling control circuit 146 also includes the lift cylinder 22°, tilt cylinder 24. Electromagnetic valve 15 that supplies hydraulic pressure to the side shift cylinder 26, etc.
8 is connected, and by controlling the operation of the electromagnetic valve 158, the operation of the cargo handling device 160 including the fork 12 and the lift bracket 18 is controlled. Further, the microprocessor 120 has a built-in timer, and the microprocessor 120 and the fork 12 are inserted into the pallet 42 by this timer and the program shown in FIG. 10 and FIG. When the receiver 50 is connected to the emitter 48
A timer (first timer) that measures the time from when the proximity switch 88 stops emitting a signal until the proximity switch 88 emits a signal when the fork 12 is removed from the pallet 42. vessel 50
It is designed to function as a timer (second timer) that measures the time until it receives light. forklift 2
8, when the fork 12 is inserted into and removed from the pallet 42, the fork 12 is run at a constant speed suitable for that purpose, so the time required to insert and remove the fork 12 is approximately constant, and the time required for each time plus the error is T and T2 are stored in advance in the memory 122 as reference times required for inserting and extracting the fork 12 into and from the pallet 42, respectively.

In the forklift truck 28 configured as described above, the proximity switch 88. The CPU 120 processes activation signals from various switches and sensors including the photoelectric switch 52 according to programs stored in the memory 122 in advance, and starts, stops, steers, accelerates and decelerates the forklift 28.
- Automatically control special standby, cargo transfer, etc.

An example of the operation of such a forklift 28 will be explained based on FIGS. 8 and 9. This example shows a case where cargo W sent by a chain conveyor 164 installed on a platform 162 is sequentially loaded into a container 168 retrofitted to the platform 162 via a span plate 166. First, until the cargo W is sent by the chain conveyor 164, the forklift 28 is kept on standby at a waiting station ST0 behind station ST. When this is detected by a predetermined sensor, etc., the standby station ST
, the cargo receiver is made to run empty to station ST. In this case, the forklift 28 is guided by the guide line 32 and travels. In other words, the detection signals from the Pinocqua boost coils 38 and 40 are transmitted to the I10 interface 124.
is sent to the CPU 120 via the vehicle body 2.
The steering control circuit 142 is controlled so that the vehicle travels along the guide line 32.

During this unloaded running, there is nothing blocking the light from the projector 48, and the photoelectric switch 52 is in the ON state.
The contact door 0 shown in FIG. 6 is at the forward end position and the proximity switch 88 is in the OFF state.

Then, the forklift 28 receives the cargo at station ST.
, the fork 12 must be inserted into the fork insertion portion 46 of the pallet 42 (if it is moved forward, the photoelectric switch 52 is turned off in step Sl as shown in FIG. 1θ).
A determination is made as to whether or not F has been reached. If the determination result is No, it means that the fork 12 has not yet been inserted into the fork insertion portion 46, and step Sl (hereinafter simply 8
It is expressed as 1. The same process is repeated for other steps. When the fork 12 is inserted into the fork insertion part 46, the light from the projector 48 is blocked by the support wall 44,
Since the light receiver 50 no longer receives light, the photoelectric switch 52 is turned off, the determination result of Sl becomes YES, step 82 is executed, and the first timer starts counting time. The microprocessor 120 starts counting time using a timer.

Subsequently, S3 is executed, and it is determined whether the proximity switch 88 is in the ON state.
Since it takes time to contact S3, during that time S3
The determination result is No, and S4 is executed. In S4, it is determined whether the measured time has reached the reference time T1 or not, and here as well, initially the reference time T1
Since this has not been reached, the determination result is No, and the program execution returns to S3. If the fork 12 is inserted into the pallet 42 without any trouble until the load W contacts the stopper 84, the proximity switch 88 is turned on within the reference time T1 indicated in -1-, and before the determination result in S4 becomes YES. When the determination result in step 83 is YES, step 85 is executed, the drive motor 148 is stopped, the electromagnetic brake 152 and the hydraulic brake 154 are activated, the forklift 28 is stopped, and a predetermined cargo handling operation is performed. , the pallet 42 is lifted by lifting up the fork 12.

On the other hand, if the insertion of the fork 12 into the fork insertion portion 46 is not smooth and the load W does not come into contact with the stopper 84 within the reference time T□, the determination result in S4 becomes YES, and in S6 is executed, the forklift 28 is brought to an emergency stop, and the next cargo handling operation is not performed.

Therefore, there is no fear that the fork 12 will be lifted up before it is inserted into the pallet 42 to the base end, and that the cargo W will fall over.

Furthermore, if there is a worker inside the platform 162 while the forklift 28 is running with no load, the worker can stop the forklift 28 by blocking the light emitted by the projector 48 himself. That is, if the worker enters between the forks 12, blocks the light from the floodlight 48, and then leaves the forklift 28, S1 becomes YES, and although S2 is executed, the proximity switch 88 is not turned on, so S3 is executed. The determination result in S4 becomes NO, and after the reference time T□ has elapsed, the determination result in S4 becomes YES, and the forklift 28 is brought to an emergency stop at 86.

After the fork 12 is inserted into the pallet 42, the forklift 28 is lifted up and runs unmanned along the guide wall 3o and the side wall 170 of the container 168 continuous thereto with the cargo W lifted. That is, the detection signals from the lateral displacement sensors 32 and 34 are sent to the CPU 120 via the I10 interface 124, and the CPU 120 maintains a predetermined distance between the vehicle body 2 and the guide wall 30 or the container side wall 170. In addition, the steering control circuit 142 is controlled so that the traveling attitude of the vehicle body 2 is parallel to the guide wall 30 and the like, so that the forklift 28 travels along the guide wall 30 and the container side wall 170. After entering the container 168, the forklift 28 is stopped with the load W on the fork 12 in contact with the already loaded load. Thereafter, the fork 12 is lowered, and with the pallet 42 placed on the floor of the container 168, the forklift 28 is moved backward, and the fork 12 is extracted from the pallet 42. In this backward movement process, as shown in FIG. 1), it is first determined at stt whether or not the proximity switch 88 is OFF. When the contact rod 70 separates from the load W as the forklift 28 retreats and the proximity switch 88 turns OFF, the determination result in S1) becomes YES, S12 is executed, and the second timer starts timing. The CPU 20 starts measuring time using a built-in timer. Then, in S13, it is determined whether the photoelectric switch 52 is turned on or not. Until the fork 12 is completely removed from the pallet 42, the light from the projector 48 is blocked by the support wall 44, and the light from the light receiver 52 is blocked. Therefore, the determination result of Si2 is NO, and S14 is executed. In S14, it is determined whether or not the measured time has reached the reference time T2, and while the measured time has not reached the reference time T2, the determination result in step 514 is NO, and the process returns to S13.

Then, if the fork 12 is pulled out from the pallet 42 without any problem, the light receiver 50 is transferred to the light emitter 48 within the reference time T2.
Therefore, the judgment result in S14 is YE.
Before it becomes S, the judgment result of 513 becomes YES and 315
is executed, the forklift 28 is driven normally, and the forklift 28 is returned to the standby station ST0 while the forklift 12 is lifted.

On the other hand, if the fork 12 is not pulled out smoothly from the pallet 42 and gets caught on the pallet 42, the photoelectric switch 52 will not turn on even if the measurement time reaches the reference time T2. Therefore, the determination result in S14 becomes YES, and the forklift 28 is brought to an emergency stop in S16. Therefore, fork 12
The cargo W will not be lifted or run without being completely removed from the pallet 42, and the cargo W will not fall over or be dragged by the forklift 28.

As is clear from the above description, S3 and S4 of the memory 122, the part that stores the programs of S13 and S14, and the CPU 12 that executes the programs.
0 constitutes the determination means.

In addition, the forklift 28 receives the cargo at station ST,
The actual forward distance after loading the cargo W is detected based on a rotational speed sensor (not shown) that detects the rotational speed of the drive wheels 4, while the cargo is received from the station ST to the cargo in the container 168. The required traveling distance to the unloading position is stored in advance in the memory 122, and the load W supported by the fork 12 is placed at a position just adjacent to the load W already placed in the container 168. There is. In addition, the required traveling distance is calculated by the CPU 120 as a value obtained by subtracting the length of the cargo W in the front and back direction from the previous distance every time the cargo W is carried into the container 168, and is newly stored in the memory 122. It will be done.

In the above embodiment, the CPU 120 is used for both inserting and extracting the fork 12 into and from the pallet 42.
However, if it is impossible for the fork 12 to run while dragging the pallet 42 during insertion or extraction, The timer may be omitted.

Further, in the embodiment described above, a transmission type photoelectric switch is used to detect whether the fork 12 is inserted into or removed from the pallet 40, but a reflection type photoelectric switch may also be used. That is, a light emitter and a light receiver are provided on one of the opposing surfaces of the pair of forks 12, and a reflective surface is provided on the other side to reflect the light from the light emitter and send it to the light receiver.In this case, the reflective surface is It functions as a light projector that projects light to a light receiver by reflection.

Further, the cargo detector is not limited to a contact type equipped with the contact rod 70, but a non-contact type such as a photoelectric switch or a proximity switch may be provided near the rear end of the cargo.

Furthermore, in the above embodiment, a case has been described in which the forklift 28 for container vanning is provided with the fork insertion/removal detection device according to the present invention. It is also possible to install it on a forklift that transports.

Although not illustrated in detail, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a counterbalance forklift truck equipped with a fork insertion/removal detection device according to an embodiment of the present invention, and FIG. 2 is a side view thereof. FIG. 3 is a perspective view showing the fork of the forklift;
The figure is a perspective view showing a pallet used for transporting cargo by the forklift. FIG. 5 is a front view showing the load detector installed in the forklift;
The figure is a VT-VI cross-sectional view in FIG. 5. FIG. 7 is a block diagram schematically showing the control circuit of the forklift. FIG. 8 is a plan view schematically showing an example of how the forklift is used, and FIG. 9 is a side view thereof. FIG. 10 and FIG. 1) are flowcharts showing programs for inserting a fork and removing a fork from the forklift, respectively. 12: Fork 28: Forklift 42: Pallet 44: Support wall 46: Fork insertion part 48: Emitter 50: Light receiver 52: Photoelectric switch 60: Load detection device 70: Contact rod 72.74: Bolt
88: Proximity switch 94: Detection head 120: Microprocessor (CPU) 122: Memory t'X30

Claims (2)

[Claims] (1) In a forklift truck equipped with at least two forks parallel to each other, a light emitter is disposed on one side of the two forks facing each other, and a light receiver is disposed on the other side so as to face each other, and the light emitter 1. A fork insertion/removal detection device, characterized in that insertion/removal of a fork into/from a pallet is detected based on whether or not light directed from the fork to a light receiver is blocked. (2) In a forklift truck equipped with at least two forks that are parallel to each other, a light projector is arranged on one side of the mutually opposing sides of the tips of the two forks, and a light receiver is arranged on the other side so as to face each other. At the same time, a load detector is provided at a position above the base end of the fork to detect when the load has reached the base end of the fork, and the load detector detects when the light receiver stops receiving light. At least one of a first timer that measures the time until the cargo detector detects the cargo, and a second timer that measures the time from when the cargo detector stops detecting the cargo until the light receiver receives the light, and A fork insertion/removal detection device comprising a determination means for determining that an abnormality has occurred in insertion/removal of a fork into/from a pallet when the time measured by at least one of the fork exceeds a predetermined reference time.